• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1993년도 한국우주과학회보 제2권2호
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• pp.17-17
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• 1993

The wall shear stress in the vicinity of end-to end anastomoses under steady flow conditions was measured using a flush-mounted hot-film anemometer(FMHFA) probe. The experimental measurements were in good agreement with numerical results except in flow with low Reynolds numbers. The wall shear stress increased proximal to the anastomosis in flow from the Penrose tubing (simulating an artery) to the PTFE: graft. In flow from the PTFE graft to the Penrose tubing, low wall shear stress was observed distal to the anastomosis. Abnormal distributions of wall shear stress in the vicinity of the anastomosis, resulting from the compliance mismatch between the graft and the host artery, might be an important factor of ANFH formation and the graft failure. The present study suggests a correlation between regions of the low wall shear stress and the development of anastomotic neointimal fibrous hyperplasia(ANPH) in end-to-end anastomoses. 30523 T00401030523 ^x Air pressure decay(APD) rate and ultrafiltration rate(UFR) tests were performed on new and saline rinsed dialyzers as well as those roused in patients several times. C-DAK 4000 (Cordis Dow) and CF IS-11 (Baxter Travenol) reused dialyzers obtained from the dialysis clinic were used in the present study. The new dialyzers exhibited a relatively flat APD, whereas saline rinsed and reused dialyzers showed considerable amount of decay. C-DAH dialyzers had a larger APD(11.70${\pm}$1.32mmHg/min)compared to CF dialyzers(4.32${\pm}$0.55mmHg/min)(p<0.05). However, there was no observable difference in the UFR between the two dialyzers. Neither APD nor UFR showed any significant increase with an increasing number of reuses for up to more than 20reuses. A substantial number of failures observed in APD(larger than 20mmHe/min)on the reused dialyzers(2 out of 40 CP and S out 26 C-DAK) were attributed to the Possible damage on the fibers. The CF 15-11 HFDs which failed APD test did not show changes in the UFR compared to normal dialyzers indicating that APD is a more sensitive test than UFR test to evaluate the integrity of the fibers. 30527 T00401030527 ^x For quantitative measurement of reflected light from a clinical diagnostic strip, a prototype old reflectance photometer was designed. The strip loader and cassette were made to obtain more accurate reflectance parameters. The strip was illuminated at 45˚c through optical fiber and the intensity of reflected light was determined at rectanguLat angle using a photodiode. The kubelka-munk coefficient and reflection optical density were determined ar four different wavelengths(500,550,570 and 610nm) for blood glucose strip. For higher concentration than 300mg/41 about glucose, a saturation state of abforbance was observed at 500,550 and 570nm. The correlation between glucose concentration and parameters was the best at 610nm. 30535 T00401030535 ^x Radiation-induced fibrosarcoma tumors were grown on the flanks of C3H mice. The mice were divided into two groups. One group was injected with Photofrin II, intravenously (2.5mg/kg body weight). The other group received no Photofrin II. Mice from both groups were irradialed for approximately 15 minutes at 100,300, or 500 mW/cm2 with the argon (488nm/514.5 nm), dye(628nm) and gold vapor (pulsed 628 nm) laser light. A photosensitizer behaved as an added absorber. Under our experimental conditions, the presence of Photolfrin II increased surface temperature by at least 40% and the temperature rise due to 300 mW/cm2 irradiation exceeded values for hyperthermia. Light and temperature distributions with depth were estimated by a computer model. The model demonstrated the influence of wavelength on the thermal process and proved to be a valuable tool to investigate internal temperature rise. 30536 T00401030536 ^x We investigated the structural geometry of thirty-eight Korean femurs. The purpose of this study is to identify major geometrical differences between Korean femurs 3nd others that we believe belong to Caucasians so that we would be able to get insights into the femoral component design that fits Asians including Koreans. We utilized computerized tomography (CT) images of femurs extracted from cadavers. The CT images were transformed into bitmap data by using a film scanner, and then analyzed by using a commercially available software called Image v.1.0 and a Macintosh IIci computer.The resulting data were compared with already published data. The major results show that the geometry of the Korean femurs is significantly different from that of Caucasians: (1) the anteversion angle and the canal flare index are greater by the amount of approximately 8˚ and 0.5, respectively, (2) the shape of the isthmus cross section is more round, and (3) the distance between the teaser trochanter and the proximal border of the isthmus is shelter by about 15 mm. The results suggested that the femoral component suitable for Asians should be different from the currently-used components designed and manufactured mostly by European or American companies. 30537 T00401030537 ^x It is well known that nonlinear propagation characteristics of the wave in the tissue may give very useful information for the medical diagnoisis. In this paper, a new method to detect nonlinear propagation characteristics of the internal vibration in the tissue for the low frequency mechanical vibration by using bispectral analysis is proposed. In the method, low frequency vibration of f0( = 100Hz) is applied on the surface of the object, and the waveform of the internal vibration x (t) is measured from Doppler frequency modulation of silmultaneously transmitted probing ultrasonic waves. Then, the bispectra of the signal x (t) at the frequencies (f0, f0) and (f0, 2f0) are calculated to estimate the nonlinear propagation characteristics as their magnitude ratio, w here since bispectrum is free from the gaussian additive noise we can get the value with high S/N. Basic experimental system is constructed by using 3.0 MHz probing ultrasonic waves and the several experiments are carried out for some phantoms. Results show the superiority of the proposed method to the conventional method using power spectrum and also its usefulness for the tissue characterization. 30541 T00401030541 ^x This paper describes the implementation of a computerized radial pulse diagnosis by aids of a clinical expert. On this base, we composed of the radial pulse diagnosis system in korean traditional medicine. The system composed of a radial pulse wave detection system and a radial pulse diagnosis system. With a detection system, we detected Inyoung and Cheongu radial pulse wave and processed it. Then, we have got the characteristic parameters of radial pulse wave and also quantified that according to the method of Inyoung-Cheongu Comparison Radial Pulse Diagnosis. We defined the jugement standard of radial pulse diagnosis system and then we confirmed the possibility for realization of automatic radial pulse diagnosis in korean traditional medicine. 30545 T00401030545 ^x Microspheres are expected to be applied to biomedical areas such as solid-phase immunoassays, drug delivery systems, immunomagnetic cell separation. To synthesize microspheres for biomedical application, "two stage shot growth method" was developed. The uniformity ratio of synthesized microspheres was always smaller than 1.05. And the surface charge density (or the number of ionizable functional groups) of the microspheres synthesized by "two stage shot growth method" was 6~13 times higher than that of the microspheres synthesized by conventional seeded batch copolymerization. As a previous step for biomedical application, adsorption experiments of bovine albumin on microspheres were carried out under various conditions. The maximum adsorbed amount was obtained in the neighborhood of pH 4.5. Isoelectric point of bovine albumin is pH 5.0, so experimental result shows that it shifted to acid area. The adsorption isotherm was obtained, the plateau region was always reached at 2.Og/L (bulk concentration of bovine albumin).The effect of the kind and the amount of surface functional group was also examined. 30575 T00401030575 ^x A medical image workstation was developed using multimedia technique. The system based on PC-486DX was designed to acquire medical images produced by medical imaging instruments and related audio information, that is, doctors' reporting results. Input information was processed and analyzed, then the results were presented in the form of graph and animation. All the informations of the system were hierarchically related with the image as the apex. Processing and analysis algorithms were implemented so that the diagnostic accuracy could be improved. The diagnosed information can be transferred for patient diagnosis through LAN(local area network). 30592 T00401030592 ^x In the conventional infrared imaging system, complex infrared lens systems are usually used for directing collimated narrow infrared beams into the high speed 2-dimensional optic scanner. In this paper, a simple reflective infrared optic system with a 2-dimensional optic scanner is proposed for the realization of medical infrared thermography system. It has been experimentally proven that the intfrared thermography system composed of the proposed optic system has the temperature resolution of 0.1˚c under the spatial resolution of lmrad, the image matrix size of 256 X 240, and tile imaging time of 4 seconds. 30593 T00401030593 ^x In this paper, MIIS (Medical Image Information System) has been designed and implemented using INGRES RDBMS, which is based on a client/server architecture. The implemented system allows users to register and retrieve patient information, medical images and diagnostic reports. It also provides the function to display these information on workstation windows simultaneously by using the designed menu-driven graphic user interface. The medical image compression/decompression techniques are implemented and integrated into the medical image database system for the efficient data storage and the fast access through the network. 30594 T00401030594 ^x In this paper, computerized BEAM was implemented for the space domain analysis of EEG. Trans-formation from temporal summation to two-dimensional mappings is formed by 4 nearest point inter-polaton method. Methods of representation of BEAM are two. One is dot density method which classify brain electrical potential 9 levels by dot density of gray levels and the other is colour method which classify brain electrical 12 levels by red-green colours. In this BEAM, instantaneous change and average energy distribution over any arbitrary time interval of brain electrical activity could be observed and analyzed easily. In the frequency domain, the distribution of energy spectrum of a special band can easily be distinguished normality and abnormality. 30608 T00401030608 ^x Laboratory information system (LIS) is a key tool to manage laboratory data in clinical pathology. Our department has developed an information system for routine hematology using down-sized computer system. We have used an IBM 486 compatible PC with 16MB main memory, 210 MB hard disk drive, 9 RS-232C port and 24 pin dot printer. The operating system and database management system were SCO UNIX and SCO foxbase, respectively. For program development, we used Xbase language provided by SCO foxbase. The C language was used for interface purpose. To make the system use friendly, pull-down menu was used. The system connected to our hospital information system via application program interface (API), so the information related to patient and request details is automatically transmitted to our computer. Our system interfaced with fwd complete blood count analyzers(Sysmex NE-8000 and Coulter STKS) for unidirectional data tansmission from analyzer to computer. The authors suggests that this system based on down-sized computer could provide a progressive approach to total LIS based on local area network, and the implemented system could serve as a model for other hospital's LIS for routine hematology. 30609 T00401030609 ^x To develop an artificial bone substitute that is gradually degraded and replaced by the regenerated natural bone, the authors designed a composite that is consisted of calcium phosphate and collagen. To use as the structural matrix of the composite, collagen was purified from human umbilical cord. The obtained collagen was treated by pepsin to remove telopeptides, and finally, the immune-free atelocollagen was produced: The cross linked atelocollagen was highly resistant to the collagenase induced collagenolysis. The cross linked collagen demonstrated an improved tensile strength. 30618 T00401030618 ^x This paper is a study on the design of adptive filter for QRS complex detection. We propose a simple adaptive algorithm to increase capability of noise cancelation in QRS complex detection with two stage adaptive filter. At the first stage, background noise is removed and at the next stage, only spectrum of QRS complex components is passed. Two adaptive filters can afford to keep track of the changes of both noise and QRS complex. Each adaptive filter consists of prediction error filter and FIR filter The impulse response of FIR filter uses coefficients of prediction error filter. The detection rates for 105 and 108 of MIT/BIH data base were 99.3% and 97.4% respectively. 30619 T00401030619 ^x To develop an artificial bone substitute that is gradually degraded and replaced by the regenerated natural bone, the authors designed and produced a composite that is consisted of calcium phosphate and collagen. Human umbilical cord origin pepsin treated type I atelocollagen was used as the structural matrix, by which sintered or non-sintered carbonate apatite was encapsulated to form an inorganic-organic composite. With cross linking atelocollagen by UV ray irradiation, the resistance to both compressive and tensile strength was increased. Collagen degradation by the collagenase induced collagenolysis was also decreased. 30620 T00401030620 ^x We have developed a monoleaflet polymer valve as an inexpensive and viable alternative, especially for short-term use in the ventricular assist device or total artificial heart. The frame and leaflet of the polymer valve were made from polyurethane, To evaluate the hemodynamic performance of the polymer valve a comparative study of flow dynamics past a polymer valve and a St. Jude Medical prosthetic valve under physiological pulsatile flow conditions in vitro was made. Comparisons between the valves were made on the transvalvular pressure drop, regurgitation volume and maximum valve opening area. The polymer valve showed smaller regurgitation volume and transvalvular pressure drop compared to the mechanical valve at higher heart rate. The results showed that the functional characteristics of the polymer valve compared favorably with those of the mechanical valve at higher heart rate. 30621 T00401030621 ^x Explosive evaporative removal process of biological tissue by absorption of a CW laser has been simulated by using gelatin and a multimode Nd:YAG laser. Because the point of maximun temperature of laser-irradiated gelatin exists below the surface due to surface cooling, evaporation at the boiling temperature is made explosively from below the surface. The important parameters of this process are the conduction loss to laser power absorption (defined as the conduction-to-laser power parameter, Nk), the convection heat transfer at the surface to conduction loss (defined as Bi), dimensionless extinction coefficient (defined as Br.), and dimensionless irradiation time (defined as Fo). Dependence of Fo on Nk and Bi has been observed by experiment, and the results have been compared with the numerical results obtained by solving a 2-dimensional conduction equation. Fo and explosion depth (from the surface to the point of maximun temperature) are increased when Nk and Bi are increased.To find out the minimum laser power for explosive evaporative removal process, steady state analysis has been also made. The limit of Nk to induce evaporative removal, which is proportional to the inverse of the laser power, has been obtained. 30622 T00401030622 ^x N1 and N2 gross neural action potentials were measured from the round window of the guinea pig cochlea at the onset of the acoustic stimuli. N1-N2 audiograms were made by means of regulating stimulant intensities in order to produce constant N1-N2 potentials as criteria for different input tone pip frequencies. The lowest threshold was measured with an input tone pip I5 dB SPL in intensity and 12 KHz in frequency when the animal was in normal physiological condition. The procedure of experimental measurements is explained in detail. This experimental approach is very useful for the investigation of the Cochlear function. Both noN1inear and active functions of the Cochlea can be monitored by N1-N2 audiograms. 30623 T00401030623 ^x In electrical impedance tomography(EIT), we use boundary current and voltage measurements toprovide the information about the cross-sectional distribution of electrical impedance or resistivity. One of the major problems in EIT has been the inaccessibility of internal voltage or current data in finding the internal impedance values. We propose a new image reconstruction method using internal current density data measured by NMR. We obtained a two-dimensional current density distribution within a phantom by processing the real and imaginary MR images from a 4.77 NMR machine. We implemented a resistivity mage reconstruction algorithm using the finite element method and sensitivity matrix. We presented computer simulation results of the mage reconstruction algorithm and furture direction of the research. 30624 T00401030624 ^x A new method of digital image analysis technique for discrimination of cancer cell was presented in this paper. The object image was the Thyroid eland cells image that was diagnosed as normal and abnormal (two types of abnormal: follicular neoplastic cell, and papillary neoplastic cell), respectively. By using the proposed region segmentation algorithm, the cells were segmented into nucleus. The 16 feature parameters were used to calculate the features of each nucleus. A9 a consequence of using dominant feature parameters method proposed in this paper, discrimination rate of 91.11% was obtained for Thyroid Gland cells. 30625 T00401030625 ^x An electrical stimulator was designed to induce locomotion for paraplegic patients caused by central nervous system injury. Optimal stimulus parameters, which can minimize muscle fatigue and can achieve effective muscle contraction were determined in slow and fast muscles in Sprague-Dawley rats. Stimulus patterns of our stimulator were designed to simulate electromyographic activity monitored during locomotion of normal subjects. Muscle types of the lower extremity were classified according to their mechanical property of contraction, which are slow muscle (msoleus m.) and fast muscle (medial gastrocneminus m., rectus femoris m., vastus lateralis m.). Optimal parameters of electrical stimulation for slow muscles were 20 Hz, 0.2 ms square pulse. For fast muscle, 40 Hz, 0.3 ms square pulse was optimal to produce repeated contraction. Higher stimulus intensity was required when synergistic muscles were stimulated simultaneously than when they were stimulated individually. Electrical stimulation for each muscle was designed to generate bipedal locomotion, so that individual muscles alternate contraction and relaxation to simulate stance and swing phases. Portable electrical stimulator with 16 channels built in microprocessor was constructed and applied to paraplegic patients due to lumbar cord injury. The electrical stimulator restored partially gait function in paraplegic patients. 30626 T00401030626 ^x Two-Dimensional modelling of the Cochlear biomechanics is presented in this paper. The Laplace partial differential equation which represents the fluid mechanics of the Cochlea has been transformed into two-dimensional electrical transmission line. The procedure of this transformation is explained in detail. The comparison between one and two dimensional models is also presented. This electrical modelling of the basilar membrane (BM) is clearly useful for the next approach to the further. Development of active elements which are essential in the producing of the sharp tuning of the BM. This paper shows that two-dimension model is qualitatively better than one-dimensional model both in amplitude and phase responses of the BM displacement. The present model is only for frequency response. However because the model is electrical, the two-dimensional transmission line model can be extended to time response without any difficult. 30627 T00401030627 ^x A method has been proposed for the fully automatic detection of left ventricular endocardial boundary in 2D short axis echocardiogram using geometric model. The procedure has the following three distinct stages. First, the initial center is estimated by the initial center estimation algorithm which is applied to decimated image. Second, the center estimation algorithm is applied to original image and then best-fit elliptic model estimation is processed. Third, best-fit boundary is detected by the cost function which is based on the best-fit elliptic model. The proposed method shows effective result without manual intervention by a human operator. 30628 T00401030628 ^x The intelligent trajectory control method that controls moving direction and average velocity for a prosthetic arm is proposed by pattern recognition and force estimations using EMG signals. Also, we propose the real time trajectory planning method which generates continuous accelleration paths using 3 stage linear filters to minimize the impact to human body induced by arm motions and to reduce the muscle fatigue. We use combination of MLP and fuzzy filter for pattern recognition to estimate the direction of a muscle and Hogan's method for the force estimation. EMG signals are acquired by using a amputation simulator and 2 dimensional joystick motion. The simulation results of proposed prosthetic arm control system using the EMf signals show that the arm is effectively followed the desired trajectory depended on estimated force and direction of muscle movements. 30638 T00401030638 ^x A new neural network architecture for the recognition of patterns from images is proposed, which is partially based on the results of physiological studies. The proposed network is composed of multi-layers and the nerve cells in each layer are connected by spatial filters which approximate receptive fields in optic nerve fields. In the proposed method, patterns recognition for complicated images is carried out using global features as well as local features such as lines and end-points. A new generating method of matched filers representing global features is proposed in this network. 30659 T00401030659 ^x An implementation scheme of the magnetic nerve stimulator using a switching mode power supply is proposed. By using a switching mode power supply rather than a conventional linear power supply for charging high voltage capacitors, the weight and size of the magnetic nerve stimulator can be considerably reduced. Maximum output voltage of the developed magnetic nerve stimulator using the switching mode power supply is 3,000 volts and switching time is about 100 msec. Experimental results or human nerve stimulations using the developed stimulator are presented. 30768 T00401030768 ^x In this paper, we describe the design methodology and specifications of the developed module-based bedside monitors for patient monitoring. The bedside monitor consists of a main unit and module cases with various parameter modules. The main unit includes a 12.1" TFT color LCD, a main CPU board, and peripherals such as a module controller, Ethernet LAN card, video card, rotate/push button controller, etc. The main unit can connect at maximum three module cases each of which can accommodate up to 7 parameter modules. They include the modules for electrocardiograph, respiration, invasive blood pressure, noninvasive blood pressure, temperature, and SpO2 with Plethysmograph.

• 대한소아치과학회지
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• 제26권2호
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• pp.399-415
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• 1999

세포내 유리칼슘(free calcium, $Ca^{2+}$)은 세균에서 고등동물에 이르기까지 거의 모든 세포에서 세포 고유작용을 조절하는 중요한 세포내 신호전달체계(signal transduction system)의 매개체이다. 타액선 세포에서 부교감 신경 자극으로 타액분비가 증가될 때에도 세포내 $Ca^{2+}$ 농도 증가가 가장 중요한 역할을 한다. 그러나 췌장(pancreas)의 경우 세포내 $Ca^{2+}$ 이외에도 인접세포를 전기적 화학적으로 연결해주는 gap junction이 외분비 기능을 직접적으로 조절할 가능설이 제시되었다. 타액선 세포에서도 세포막에 고농도의 gap junction이 존재하고 있으며 gap junction을 통해 인접세포들이 전기적, 화학적으로 연계되어 있어 gap junction이 타액선 세포의 기능을 직접적으로 조절할 가능성을 내포하고 있다. 따라서 gap junction이 타액선의 타액분비 작용에도 중요한 역할을 하며 이러한 작용이 세포내 $Ca^{2+}$ 농도를 조절하여 이루어질 것이라는 가정하에 이를 확인하는 실험을 시행하였다. 흰쥐 악하선에서 유리되는 타액양을 측정하기 위해서 악하선으로 혈액을 공급하는 동맥에 가는 관을 삽입하여 생리 식염수를 관류하면서 타액선관을 통해 타액을 채취하였다. 세포내 $Ca^{2+}$ 농도는 분리한 악하선 acini 내에 $Ca^{2+}$ 농도 변화에 민감하게 반응하는 형광물질인 fura-2를 축적시키고 형광 분석기를 사용하여 형광강도를 측정하여 다음과 같은 결과를 얻었다. 1. CCh 투여로 타액 분비가 증가하였을 때 gap junction을 봉쇄하는 약물인 octanol(1 mM)을 투여하면 타액분비가 봉쇄되었으며 이는 가역적 반응이었다. 2. CCh투여로 세포내 $Ca^{2+}$ 농도가 증가하였을 때 1mM octanol을 투여하면 세포내 $Ca^{2+}$ 농도가 CCh 투여전의 상태로 감소되었다. 3. Octanol은 CCh에 의하여 유발된 초기 $Ca^{2+}$ 증가를 억제하지는 못한 반면에 후기 $Ca^{2+}$ 농도를 감소시켰다. 4. 세포막 $Ca^{2+}$ 통로를 열어주는 약물인 thapsigargin($1{\mu}M$)을 투여하여 세포내 $Ca^{2+}$ 농도를 증가시킨 후 1mM octanol을 투여하면 세포내 $Ca^{2+}$ 농도가 thapsigargin 투여 전의 상태로 감소하였다. 5. 2,5-di-tert-butyl-1,4-benzohydroquinone(TBQ)의 투여로 세포막을 통한 $Ca^{2+}$ 농도의 주기적 변동인 $Ca^{2+}$의 oscillation이 유발되었는데, 이때 1mM octanol을 투여한 경우에 $Ca^{2+}$농도의 oscillation이 정지하여 역시 gap junction을 봉쇄하면 TBQ에 의해서 유발된 세포내 $Ca^{2+}$ 농도의 주기적 변동이 사라지고 $Ca^{2+}$ 농도의 감소가 나타남을 확인하였다. 6. Gap junction을 봉쇄하는 또 다른 약물인 glycyrrhetinic acid($100{\mu}M$)도 CCh 자극으로 인한 타액분비를 억제하였다. 이상의 결과로 미루어 gap junction은 흰쥐 악하선 세포로부터의 타액분비 조절에 중요한 역할을 하는데, 이는 gap junction이 세포막 $Ca^{2+}$ 통로를 조절함으로써 수용체 자극으로 유발된 세포내 $Ca^{2+}$ 농도 변화에 영향을 미친 결과인 것으로 추측된다.

• Journal of Chest Surgery
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• 제33권7호
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• pp.531-540
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• 2000

연구배경; 심근세포내 에너지원인 단원 pool의 고갈이나 당대사의증가와 이로 인한 유산의 심근세포내 축적은 허혈 심근세포 손상의 중요한 원인으로 알려져 있다. 그러나 역설적으로 당원이 결핍된 용액으로 짧은 기간 동안 허혈-재관류를 반복(IP)한 경우와 유사한 결과를 가져올 수 있는 가능성을 조사하여 세포내 신호전달체계 중 PKC와의 관련성을 알아보고자 하였다. 대상 및 방법 ; Langendorff방법에 따라 관류하여 기준설 혈역학 값이 유지되면 전체허혈(5분)-재관류(10분) 1회 실시로 IP를 유도하고 45분 동안 전체 허혈후 120분 동안 재관류하였다. (IP군. n=13). 허혈 대조군(n=10)에서는 IPdjqt이 45분 동안 전체 허혈후 120 동안 재관류를 실시하였다. Glucose 결핍용액 투여 전처치군(n=12)에서는 기준선 혈역학 값이 유지되면 5분 동안 glucose를 포함하지 않은 관류액으로 관류한 후 10분 동안 표준 관류액으로 측정하였으며 실험 종료후 PKC활성도는 PKC-specific peptide와 32P-${\gamma}$-ATP incorporation으로 PKC활성도(nmol/g tissue)를 측정하였따. PKC 동종효소의 발현정도는 단클론항체($\alpha$,$\beta$,$\delta$,$\varepsilon$,ζ 등)를 사용하여 Western blot로 확인하였다. 심근경색 크기는 1% tetrazolium chloride로 염색하여 형태 계측하였다. 결과; 45분 동안 허혈LVDP(LV developed pressure), dP/dt 등은 다른 실험군에 비하여 IPrns에서 현저히 증가하였으나 glucose 결핍용액 투여 전처치군에서는 허혈 대조군과 큰 차이가 없었으며 관혈류량은 모든 실험군 사이에서 차이를 나타내지 않았다. 그러나 glucose 결핍용액 트여 저너치군(15$\pm$3.9%)과 IP군(19$\pm$1.2%)에서는 허혈 대조군(39$\pm$2.7%)에 비하여 심근경색 범위의 현저한 감소를 볼 수 있었다. (p<0.05). PKC 활성도는 기준선과 비교하여 허혈 대조군에서는 87% 정도를 감소하였으며 (p<0.05), IP 실시한 후와 IP후 45분 동안 허혈을 실시한 결우에는 각각 119, 145%로 현저히 증가하였다. (p<0.01). PKC 동종효소중 $\beta$, $\delta$, ζ 등에서는 발현정도에 유의한 변화가 없었던 반면 $\alpha$ 및 $\varepsilon$에서 양적인 변화를 관찰할 수 있었다. PKC-$\alpha$의 세포질분획의 발현은 기준선이나허혈 대조군과 비교하여 IPgn에 증가하는 경향을 나타내었으나, 이외의실험군에서는 큰 변화를 볼 수 없었다. PKC-$\alpha$의 세포막분획은 IP후롸, glucose 결핍용액 투여 전처치후, glucose 결핍용액 투여 전치치후 45분 동안 허혈후에 증가하는 경향을 나타내었다. PKC-$\varepsilon$의 세포질분획의 발현은 기준선이나 허혈 대조군과 비교하여 IPgn나 IPgn 45분 동안 허혈후, glucose 결핍용액 투여 전처치에 증가하는 경향을 나타내었으며 PKC-$\varepsilon$의 세포막분획은 IP후 45분 동안 허혈후, 또는 glucose 결핍용액 투여 전처치후에 발현이 증가하는 경향을 나타내었다. 결론 ; 이상으로 적출 관류 토끼 심장에서 glucose 결핍용액 투여로 전처치할 경우 후속된 장시간 동안의 허혈에 대하여 좌심실기능 회복 증가는 기대할 수 없으나 심근경색 범위가 감소되거나 한정되는 보호효과가 있음을 알 수 있었다.

• Radiation Oncology Journal
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• 제19권1호
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• pp.66-73
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• 2001

목적 : 붕소-중성자 포획치료법(Boron Neutron Capture Therapy, BNCT)을 위해 원자력병원 싸이클로트론에서 발생되는 최대에너지 34.4 MeV의 속중성자(Fast neutron)를 70 cm 파라핀으로 감속시킨 후 선량 특성을 조사하였다. 그 결과를 토대로 열외중성자(Epithermal neutron) 선량 측정법에 대한 프로토콜을 확립하여 원자로에서 방출되는 열외 중성자 선량 특성 평가의 기초를 삼고, 가속기를 이용한 BNCT 연구에 대한 타당성 여부를 조사하고자 한다. 대상 및 방법 : 공기 중 선량 및 물질 내 선량 분포 측정을 위해 Unidos 10005 (PTW, Germany) 전기계와 조직 등가 물질인 A-150 플라스틱으로 제작된 IC-17 (Far West, USA) 및 IC-18, ElC-1 이온함을 사용하였고, 감마선의 측정을 위해서는 마그네슘으로 제작된 IC-l7M 이온함을 이용하였으며 조직등가 기체와 아르곤 기체를 분당 5cc 씩 주입하며 측정하였다. 중성자, 광자, 전자가 혼합된 장의 모의 수송 해석을 위해 이용되는 Monte Carlo N-Particle (MCNP) transport code를 사용하여 2차원적 선량 분포 및 에너지 분포를 계산하였으며 이 결과를 측정값과 비교하였다. 결과 : BNCT에서의 유효 치료 깊이인 물 팬텀 4 cm에서의 선량은 치료기 1 MU 당 $6.47\times10^{-3}\;cGy$로 미세하였으며, 이때 감마 오염도(contamination)는 $65.2{\pm}0.9\%$로 중성자보다는 감마선에 의한 선량 기여분이 우세하였다. 깊이에 따른 선량 분포 특성에서는 중성자 선량은 선형적으로 감쇠 되었고, 감마선량은 지수적으로 보다 급격히 감쇠되는 경향을 보였으며 전체 선량의 $D_{20}/D_{10}$은 0.718 이었다. MCNP에 의한 에너지 분포 전산 계산의 결과 2.87 MeV 이하에서 중성자 피크가 나타났으며, 저에너지 영역에서는 감마선이 연속적으로 분포되는 양상을 보였다. 결론 : 벽 물질이 서로 다른 두 개의 이온함을 사용한 직접 선량 측정과 MCNP 전산 시뮬레이션을 이용한 공간 선량분포 계산으로 미세 속중성자 빔에 대한 선량 특성을 파악할 수 있었으며, 원자로 열외중성자 주(Epithermal neutron column)에 대한 선량 평가 자료로 확보하였다. 아울러 가속기에 대한 연구가 진행되어 고전압, 고전류를 발생시키는 전원 공급장치와 표적핵(Target) 물질이 개발되고 비스무스나 납 등에 의해 감마 오염도를 줄일 경우, 싸이크로트론에 의한 보론-중성자 포획치료도 가능해질 것으로 판단된다.

• 지능정보연구
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• 제27권1호
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• pp.191-207
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• 2021

오늘날 이동통신은 급증하는 데이터 수요에 대응하기 위해서 주로 속도 향상에 초점을 맞추어 발전해 왔다. 그리고 5G 시대가 시작되면서 IoT, V2X, 로봇, 인공지능, 증강 가상현실, 스마트시티 등을 비롯하여 다양한 서비스를 고객들에게 제공하기위한 노력들이 진행되고 있고 이는 우리의 삶의 터전과 산업 전반에 대한 환경을 바꿀 것으로 예상되고 되고 있다. 이러한 서비스를 제공하기위해서 고속 데이터 속도 외에도, 실시간 서비스를 위한 지연 감소 그리고 신뢰도 등이 매우 중요한데 5G에서는 최대 속도 20Gbps, 지연 1ms, 연결 기기 106/㎢를 제공함으로써 서비스 제공할 수 있는 기반을 마련하였다. 하지만 5G는 고주파 대역인 3.5Ghz, 28Ghz의 높은 주파수를 사용함으로써 높은 직진성의 빠른 속도를 제공할 수 있으나, 짧은 파장을 가지고 있어 도달할 수 있는 거리가 짧고, 회절 각도가 작아서 건물 등을 투과하지 못해 실내 이용에서 제약이 따른다. 따라서 기존의 통신망으로 이러한 제약을 벗어나기가 어렵고, 기반 구조인 중앙 집중식 SDN 또한 많은 노드와의 통신으로 인해 처리 능력에 과도한 부하가 발생하기 때문에 지연에 민감한 서비스 제공에 어려움이 있다. 그래서 자율 주행 중 긴급 상황이 발생할 경우 사용 가능한 지연 관련 트리 구조의 제어 기능이 필요하다. 이러한 시나리오에서 차량 내 정보를 처리하는 네트워크 아키텍처는 지연의 주요 변수이다. 일반적인 중앙 집중 구조의 SDN에서는 원하는 지연 수준을 충족하기가 어렵기 때문에 정보 처리를 위한 SDN의 최적 크기에 대한 연구가 이루어져야 한다. 그러므로 SDN이 일정 규모로 분리하여 새로운 형태의 망을 구성 해야하며 이러한 새로운 형태의 망 구조는 동적으로 변하는 트래픽에 효율적으로 대응하고 높은 품질의 유연성 있는 서비스를 제공할 수 있다. 이러한 SDN 구조 망에서 정보의 변경 주기, RTD(Round Trip Delay), SDN의 데이터 처리 시간은 지연과 매우 밀접한 상관관계를 가진다. 이 중 RDT는 속도는 충분하고 지연은 1ms 이하이기에 유의미한 영향을 주는 요인은 아니지만 정보 변경 주기와 SDN의 데이터 처리 시간은 지연에 크게 영향을 주는 요인이다. 특히, 5G의 다양한 응용분야 중에서 지연과 신뢰도가 가장 중요한 분야인 지능형 교통 시스템과 연계된 자율주행 환경의 응급상황에서는 정보 전송은 매우 짧은 시간 안에 전송 및 처리돼야 하는 상황이기때문에 지연이라는 요인이 매우 민감하게 작용하는 조건의 대표적인 사례라고 볼 수 있다. 본 논문에서는 자율 주행 시 응급상황에서 SDN 아키텍처를 연구하고, 정보 흐름(셀 반경, 차량의 속도 및 SDN의 데이터 처리 시간의 변화)에 따라 차량이 관련정보를 요청해야 할 셀 계층과의 상관관계에 대하여 시뮬레이션을 통하여 분석을 진행하였다.

• 안보군사학연구
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• 통권8호
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• pp.49-168
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• 2010

Just before the Korean War, the total number of the North Korean troops was 198,380, while that of the ROK(Republic of Korea) army troops 105,752. That is, the total number of the ROK army troops at that time was 53.3% of the total number of the North Korean army. As of December 2008, the total number of the North Korean troops is estimated to be 1,190,000, while that of the ROK troops is 655,000, so the ROK army maintains 55.04% of the total number of the North Korean troops. If the ROK army continues to reduce its troops according to [Military Reform Plan 2020], the total number of its troops will be 517,000 m 2020. If North Korea maintains the current status(l,190,000 troops), the number of the ROK troops will be 43.4% of the North Korean army. In terms of units, just before the Korean War, the number of the ROK army divisions and regiments was 80% and 44.8% of North Korean army. As of December 2008, North Korea maintains 86 divisions and 69 regiments. Compared to the North Korean army, the ROK army maintains 46 Divisions (53.4% of North Korean army) and 15 regiments (21.3% of North Korean army). If the ROK army continue to reduce the military units according to [Military Reform Plan 2020], the number of ROK army divisions will be 28(13 Active Division, 4 Mobilization Divisions and 11 Local Reserve Divisions), while that of the North Korean army will be 86 in 2020. In that case, the number of divisions of the ROK army will be 32.5% of North Korean army. During the Korean war, North Korea suddenly invaded the Republic of Korea and occupied its capital 3 days after the war began. At that time, the ROK army maintained 80% of army divisions, compared to the North Korean army. The lesson to be learned from this is that, if the ROK army is forced to disperse its divisions because of the simultaneous invasion of North Korea and attack of guerrillas in home front areas, the Republic of Korea can be in a serious military danger, even though it maintains 80% of military divisions of North Korea. If the ROK army promotes the plans in [Military Reform Plan 2020], the number of military units of the ROK army will be 32.5% of that of the North Korean army. This ratio is 2.4 times lower than that of the time when the Korean war began, and in this case, 90% of total military power should be placed in the DMZ area. If 90% of military power is placed in the DMZ area, few troops will be left for the defense of home front. In addition, if the ROK army continues to reduce the troops, it can allow North Korea to have asymmetrical superiority in military force and it will eventually exert negative influence on the stability and peace of the Korean peninsular. On the other hand, it should be reminded that, during the Korean War, the Republic of Korea was attacked by North Korea, though it kept 53.3% of troops, compared to North Korea. It should also be reminded that, as of 2008, the ROK army is defending its territory with the troops 55.04% of North Korea. Moreover, the national defense is assisted by 25,120 troops of the US Forces in Korea. In case the total number of the ROK troops falls below 43.4% of the North Korean army, it may cause social unrest about the national security and may lead North Korea's misjudgement. Besides, according to Lanchester strategy, the party with weaker military power (60% compared to the party with stronger military power) has the 4.1% of winning possibility. Therefore, if we consider the fact that the total number of the ROK army troops is 55.04% of that of the North Korean army, the winning possibility of the ROK army is not higher than 4.1%. If the total number of ROK troops is reduced to 43.4% of that of North Korea, the winning possibility will be lower and the military operations will be in critically difficult situation. [Military Reform Plan 2020] rums at the reduction of troops and units of the ground forces under the policy of 'select few'. However, the problem is that the financial support to achieve this goal is not secured. Therefore, the promotion of [Military Reform Plan 2020] may cause the weakening of military defence power in 2020. Some advanced countries such as Japan, UK, Germany, and France have promoted the policy of 'select few'. However, what is to be noted is that the national security situation of those countries is much different from that of Korea. With the collapse of the Soviet Unions and European communist countries, the military threat of those European advanced countries has almost disappeared. In addition, the threats those advanced countries are facing are not wars in national level, but terrorism in international level. To cope with the threats like terrorism, large scaled army trops would not be necessary. So those advanced European countries can promote the policy of 'select few'. In line with this, those European countries put their focuses on the development of military sections that deal with non-military operations and protection from unspecified enemies. That is, those countries are promoting the policy of 'select few', because they found that the policy is suitable for their national security environment. Moreover, since they are pursuing common interest under the European Union(EU) and they can form an allied force under NATO, it is natural that they are pursing the 'select few' policy. At present, NATO maintains the larger number of troops(2,446,000) than Russia(l,027,000) to prepare for the potential threat of Russia. The situation of japan is also much different from that of Korea. As a country composed of islands, its prime military focus is put on the maritime defense. Accordingly, the development of ground force is given secondary focus. The japanese government promotes the policy to develop technology-concentrated small size navy and air-forces, instead of maintaining large-scaled ground force. In addition, because of the 'Peace Constitution' that was enacted just after the end of World War II, japan cannot maintain troops more than 240,000. With the limited number of troops (240,000), japan has no choice but to promote the policy of 'select few'. However, the situation of Korea is much different from the situations of those countries. The Republic of Korea is facing the threat of the North Korean Army that aims at keeping a large-scale military force. In addition, the countries surrounding Korea are also super powers containing strong military forces. Therefore, to cope with the actual threat of present and unspecified threat of future, the importance of maintaining a carefully calculated large-scale military force cannot be denied. Furthermore, when considering the fact that Korea is in a peninsular, the Republic of Korea must take it into consideration the tradition of continental countries' to maintain large-scale military powers. Since the Korean War, the ROK army has developed the technology-force combined military system, maintaining proper number of troops and units and pursuing 'select few' policy at the same time. This has been promoted with the consideration of military situation in the Koran peninsular and the cooperation of ROK-US combined forces. This kind of unique military system that cannot be found in other countries can be said to be an insightful one for the preparation for the actual threat of North Korea and the conflicts between continental countries and maritime countries. In addition, this kind of technology-force combined military system has enabled us to keep peace in Korea. Therefore, it would be desirable to maintain this technology-force combined military system until the reunification of the Korean peninsular. Furthermore, it is to be pointed out that blindly following the 'select few' policy of advanced countries is not a good option, because it is ignoring the military strategic situation of the Korean peninsular. If the Republic of Korea pursues the reduction of troops and units radically without consideration of the threat of North Korea and surrounding countries, it could be a significant strategic mistake. In addition, the ROK army should keep an eye on the fact the European advanced countries and Japan that are not facing direct military threats are spending more defense expenditures than Korea. If the ROK army reduces military power without proper alternatives, it would exert a negative effect on the stable economic development of Korea and peaceful reunification of the Korean peninsular. Therefore, the desirable option would be to focus on the development of quality of forces, maintaining proper size and number of troops and units under the technology-force combined military system. The tableau above shows that the advanced countries like the UK, Germany, Italy, and Austria spend more defense expenditure per person than the Republic of Korea, although they do not face actual military threats, and that they keep achieving better economic progress than the countries that spend less defense expenditure. Therefore, it would be necessary to adopt the merits of the defense systems of those advanced countries. As we have examined, it would be desirable to maintain the current size and number of troops and units, to promote 'select few' policy with increased defense expenditure, and to strengthen the technology-force combined military system. On the basis of firm national security, the Republic of Korea can develop efficient policies for reunification and prosperity, and jump into the status of advanced countries. Therefore, the plans to reduce troops and units in [Military Reform Plan 2020] should be reexamined. If it is difficult for the ROK army to maintain its size of 655,000 troops because of low birth rate, the plans to establish the prompt mobilization force or to adopt drafting system should be considered for the maintenance of proper number of troops and units. From now on, the Republic of Korean government should develop plans to keep peace as well as to prepare unexpected changes in the Korean peninsular. For the achievement of these missions, some options can be considered. The first one is to maintain the same size of military troops and units as North Korea. The second one is to maintain the same level of military power as North Korea in terms of military force index. The third one is to maintain the same level of military power as North Korea, with the combination of the prompt mobilization force and the troops in active service under the system of technology-force combined military system. At present, it would be not possible for the ROK army to maintain such a large-size military force as North Korea (1,190,000 troops and 86 units). So it would be rational to maintain almost the same level of military force as North Korea with the combination of the troops on the active list and the prompt mobilization forces. In other words, with the combination of the troops in active service (60%) and the prompt mobilization force (40%), the ROK army should develop the strategies to harmonize technology and forces. The Korean government should also be prepared for the strategic flexibility of USFK, the possibility of American policy change about the location of foreign army, radical unexpected changes in North Korea, the emergence of potential threat, surrounding countries' demand for Korean force for the maintenance of regional stability, and demand for international cooperation against terrorism. For this, it is necessary to develop new approaches toward the proper number and size of troops and units. For instance, to prepare for radical unexpected political or military changes in North Korea, the Republic of Korea should have plans to protect a large number of refugees, to control arms and people, to maintain social security, and to keep orders in North Korea. From the experiences of other countries, it is estimated that 115,000 to 230,000 troops, plus ten thousands of police are required to stabilize the North Korean society, in the case radical unexpected military or political change happens in North Korea. In addition, if the Republic of Korea should perform the release of hostages, control of mass destruction weapons, and suppress the internal wars in North Korea, it should send 460,000 troops to North Korea. Moreover, if the Republic of Korea wants to stop the attack of North Korea and flow of refugees in DMZ area, at least 600,000 troops would be required. In sum, even if the ROK army maintains 600,000 troops, it may need additional 460,000 troops to prepare for unexpected radical changes in North Korea. For this, it is necessary to establish the prompt mobilization force whose size and number are almost the same as the troops in active service. In case the ROK army keeps 650,000 troops, the proper number of the prompt mobilization force would be 460,000 to 500,000.