• 제목/요약/키워드: Two Stage Valve

검색결과 59건 처리시간 0.027초

High Resolution HC$_3$N Observations toward the Central Region of Sagittarius B2

  • H.S-Ching;Oh, M.ishi;M.Morimoto
    • 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.

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스파크점화기관에서 흡기제어 방식이 부분부하 성능에 미치는 영향(1) - 스로틀링과 마스킹의 비교 (Effect of Intake Flow Control Method on Part Load Performance in SI Engine(1) - Comparison of Throttling and Masking)

  • 강민균;엄인용
    • 한국자동차공학회논문집
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    • 제22권2호
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    • pp.156-165
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    • 2014
  • This paper is the first investigation on the effect of flow control methods on the part load performance in a spark ignition engine. For comparison of the methods, two control devices, port throttling and masking, were applied to a conventional engine without any design change of the intake port. Steady flow evaluation shows that steady flow rates per unit opening area and swirl ratio are very low compared with the port throttling and saturated from mid-stage valve lift, however, swirl increases slightly as the lift is higher in case of 1/4 masking control. In the part load performance, the effect of simple port throttling on lean misfire limit expansion is limited and insufficient; on the other hand a masking improves the limit considerably without any port modification for increasing swirl. Also the results show that the intake flow control improves the combustion with following two mechanisms: stratification induced by the combination of the flow pattern and the fuel injection timing attribute to ignition ability and the intensified flow ensure fast burn. In addition fuel consumption reduces under the flow controls and the reduction rate is different according to the operation conditions and control methods. At the Stoichiometric and/or low speed and low load the throttling method is more advantageous; however vice versa at lean and high load condition. Finally, the throttling is more efficient for HC reduction than masking, on the other side the NOx emissions increase under the masking and decrease under the port throttling compared with conventional port scheme.

가속도계를 이용한 탄성파 기반 누수탐지 기술 분석 (Analysis of Elastic Wave Based Leakage Detection Technology Using Accelerometers)

  • 최광묵;이호현;신강욱;홍성택
    • 한국정보통신학회논문지
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    • 제24권9호
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    • pp.1231-1240
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    • 2020
  • 상수도 배관은 땅속에 매설되어 있어서 배관의 노후화에 따른 누수를 맨눈으로 탐지하기가 불가능하며, 누수음을 감지함으로써 배관의 누수를 탐지하는 기술이 주로 사용된다. 본 논문에서는 상수도 배관의 양단에 두 개의 가속도계를 부착·취득한 데이터 간의 도달 시간 차이를 계산하여 누수 지점을 탐지하는 알고리즘을 개발하였다. 배관의 누수 시험은 17.2m의 배관에 4.3m, 8.6m, 12.9m 지점에 밸브를 설치하고, 밸브의 개도율을 30%, 70%로 변경해 가면서 누수 지점을 분석하였으며, 밸브가 30%, 70%씩 개방된 정도의 배관 내 압력 강하에 대해서는 누수를 탐지할 수 있는 것으로 확인되었다. 초기 단계의 누수를 탐지하는 것이 매우 중요하며, 본 연구에서 적용한 알고리즘으로부터 초기의 누수 지점의 탐지가 가능할 것으로 판단된다.

대형 2행정 디젤기관에 있어서 일체형 전자제어 축압분배 실린더 주유기 시스템의 주유 불균일률에 관한 연구 (A Study on Inequality Rate of Integrated Cylinder Lubricator System with an Accumulated Distribution by the Electronic Control in a Large Two-stroke Diesel Engine)

  • 배명환;정화;김수민;배창환
    • 한국자동차공학회논문집
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    • 제22권2호
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    • pp.123-133
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    • 2014
  • Minimizing the cylinder wear and the consumption rate of cylinder oil in a large two-stroke diesel engine is of great economic importance. A motor-driven cylinder lubricator for Sulzer RT-flex large two-stroke diesel engines developed by authors is in need of improving the lubricating system to lubricate cylinder parts optimally by an electronically controlled quill device according to changes of engine load and revolution speed. In order to apply the developed accumulating distributor to an integrated cylinder lubricator by the electronically controlled system as the third research stage, the lubricating system is improved in the electronically controlled quill device with a solenoid valve. In this study, the effects of lubricator revolution speed, driving pressure(or plunger stroke) and cylinder back pressure on oil feed rate and lubrication inequality rate are investigated by using the integrated cylinder lubricator system with an accumulated distribution by the electronic control(I.C.S.), and the oil feed rate and lubrication inequality rate of I.C.S. are compared with those of the motor-driven cylinder lubricator by the electronically controlled quill system equipped with an accumulating distributor(E.D.S.). It is found that the oil feed rate of I.C.S. is smaller than that of E.D.S. due to the reduction of delivery velocity by the higher delivery pressure, and the variances of lubrication inequality rate for I.C.S. have become smaller than those of E.D.S. as the driving pressure in all experimental conditions increases, except for the driving pressure of 26 bar(plunger stroke 2 mm) at the cylinder lubricator speed of 120 rpm.

상용 소프트웨어를 이용한 스파크 점화 기관의 시뮬레이션에 관한 연구 (Study on the simulation of a spark ignition engine using BOOST)

  • 정창식;우석근;류순필;윤건식
    • Journal of Advanced Marine Engineering and Technology
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    • 제40권9호
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    • pp.733-742
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    • 2016
  • 연료 경제와 유해 배출 가스 저감을 목적으로 최근 들어 LNG 또는 합성 가스를 사용하는 박용 가스 기관이 주목받고 있다. 예혼합 연소를 하는 오토 사이클로 작동하는 가스 기관을 구현할 경우 EGR 또는 SCR을 적용하지 않고도 Tier III의 규제를 충족할 수 있는 것으로 확인되고 있다. 본 연구에서는 오토 사이클로 작동하는 기관에 대한 시뮬레이션 기술을 산업 기술 현장에 제공하기 위한 목적으로, 실험적으로 접근이 용이한 소형 가솔린 기관을 대상으로 상용 소프트웨어인 BOOST를 이용한 시뮬레이션을 시행하였다. 이 연구는 두 단계로 구성되어 이미 시행한 첫 번째 단계에서는 흡기 및 배기 계통에 대한 최적의 모델링 방법에 관한 연구가 수행되었다. 이번 연구는 이전의 연구에서 선정된 흡 배기 계통의 해석 모델을 적용한 상황에서 실린더 내 과정을 해석하고 최종적으로 주요 성능 인자들을 계산하는 방법을 정립하였다. 이 연구를 통하여 실험에의 의존이 적은 연소 및 열전달 모델과 밸브 유량계수 모델을 선정하고 관련 상수들을 결정하는 방법을 확립하였다. 이들을 이용하여 실린더로 유입되는 공기량, 실린더 내 순간 압력 변화 및 도시평균유효압력을 효과적으로 예측할 수 있음을 확인하였다.

숀 증후군의 외과적 치료 (Surgical Experiences of Shone's Syndrome)

  • 원태희;이정렬;김용진;노준량
    • Journal of Chest Surgery
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    • 제30권9호
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    • pp.862-868
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    • 1997
  • 서울대학교병원 흉부외과에서는 1985년부터 1994년까지 총 9례의 숀 증후군 환자를 치험하였다. 남자 환 아가 떼이었고 여자 환아가 1례이었다. 첫 수술을 시행한 연령은 깨월에서 11세까지로 평균 연령은 33.0 $\pm$ 31.0 개월이었다. 선천성 승모판 협착증 및 대동맥 축착증은 모든 환아에서 존재하였고 승모판 상부 링 및 대동맥하 협착은 각각 4례의 환아에서 발견되었다. 2례의 환아에 있어서는 숀 증후군의 4가지 병변 모두를 가지고 있었다. 3례의 환아에 있어서는 한번에 완전 해부학적 교정술을 시행하였으며 나머지 2례의 환아에 있어서는 개흉술 하에 대동맥 축착증을 교정하고 나중에 정중 흉골 절개 하에 나머지 병변을 교정하는 단계적 수술을 시행하였다. 9례의 환아에 있어서 총 45개의 수술적 치료를 시행하여 1례당 평균 수술적 치료 는 5.0 $\pm$ 0.7개이었다 세번째 수술을 시행한 환아는 2례이었으며 각각 지속적인 승모판 협착으로 승모판 치 환술을 시행한 환아와 지속적인 대동맥 축착으로 대동맥 축착 성형술을 시행한 환아이었다. 한번에 완전 교정술을 시행한 환아와 1차 단계적 수술을 시행한 환아에 있어서 수술 사망률은 없었으나 2차 단계 \ulcorner수술을 시행한 6례중 2례가 사망하여 수술 사망률은 22.2%이었으며 사망한 2례 모두 1차 대동칵 축착증 교정술후 계속되는 심부전 및 인공 호흡기 이탈이 되지 않아 각각 1차 수술 후 9일과 15일 후에 완전 교정술을 시행했던 환아들로 모두 좌심실 형성부전에 의한 심부전으로 사망하였다. 세번째 수술시 사망한 환아는 없었다. 생존한 7례 모두 11개월에서 12년까지(평균 6.7 $\pm$ 3.6년)장기 추적 조사하였으며 모두 뉴욕 심장 협회 활 동도 1군에 속해 있었으며 판막 치환술로 인하여 쿠마딘을 복용하고 있는 환아와 마지막 추적조사시 흉부 X선 사진상 약간의 심비대가 있어 디곡신을 복용하고 있는 환아를 제외하고는 어떤 약도 복용하고 있지 않았 다 결론적으로 숀 증후군은 수술 사망률 및 이환율이 높은 질환이긴 하나 각각의 해부학적 병변의 특징을 잘 파악하여 적절한 치료를 한다면 좋은 장기성적을 기대할 수 있다는 것이다.

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관상동맥우회 재수술의 임상적 고찰 (Clinical Experiences of redo-CABG)

  • 임상현;곽영태;이삭;장병철;강면식;조범구;유경종
    • Journal of Chest Surgery
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    • 제35권11호
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    • pp.779-784
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    • 2002
  • 최근 들어 관상동맥 질환자의 수가 급격히 증가하면서 관상동맥 우회술의 수도 급격히 증가하고 있다. 그러나 관상동맥 우회술은 영구적인 완전 교정술이 아니기 때문에 재수술이 필요할 수 있다. 저자들은 관상 동맥우회 재수술의 임상결과를 후향적 방법으로 고찰하여 보았다. 대상 및 방법: 1991년 1월부터 2001년 4월까지 연세 심장혈관 병원에서 관상동맥우회 재수술을 시행 받은 14명을 대상으로 하였으며 (남자:12명, 여자:2명), 평균 연령은 61.7$\pm$7.1(47~72세) 세였다. 처음 수술 받은 날부터 재수술시까지의 평균 기간은 121.9$\pm$50.5(6.1~179.6 개월) 개월이었다. 재수술시 13명의 환자들은 일반적인 심폐체외순환하에 수술을 하였고 1명의 환자는 심폐체외순환 없이 수술을 시행하였다. 동반 수술로는 1명의 환자에서 승모판막 재치환술을 시행하였고, 1명의 환자에서는 승모판막륜 성형술을 시행하였다. 재수술은 모두 정중 흉골절개하에 시행하였다. 재수술시 사용한 이식 혈관은 좌측 내흉동맥과 대 복재정맥을 사용한 경우가 6례, 좌측 내흉동맥과 좌측 요골 동맥을 사용한 경우가 2례, 좌측 내흉 동맥과 위장관 동맥을 사용한 경우가 1례, 대 복재정맥만을 사용한 경우가 5례(1례는 cephalic vein도 같이 사용) 있었으며, 평균 이식 편수는 2.1$\pm$0.9(1~4개) 개였다. 결과: 14명의 환자들 중에서 수술과 관련한 사망이나 조기 사망은 없었으며, 합병증은 신부전증, 호흡부전 및 경막하 출혈이 각각 1례 있었다. 평균 추적 관찰 기간은 40.1$\pm$38.6(1.1~l18.5) 개월 이었다. 추적기간 중 1명의 환자가 재수술 후 13개월에 협심증이 재발했고, 2명의 환자가 재수술 후 14.8개월 및 116.3개월에 만성 신부전증으로 사망하였다. 추적 기간 중에 3명의 환자에서 관상동맥 조영술을 시행하였는데 이식 혈관들은 모두 개존성을 보였다. 마지막 외래 내원시 생존 환자들의 평균 Canadian class는 1.3이었고, 재수술 후 9년까지 사건(event)이 없을 확률은 71.4$\pm$6.9%였으며, 생존률은 90.0$\pm$9.5%였다. 결론: 관상동맥우회 재수술은 수술 후에 환자 상태의 호전을 기대할 수 있고, 장기간의 생존률도 우수하기에, 수술적응이 된다면 수술을 적극적으로 고려하여야 할 것으로 생각한다.

산전 초음파로 발견된 선천성 신 요로 기형의 발생률과 임상 결과: 단일 기관 연구 (Incidence and outcome of congenital anomalies of the kidney and urinary tract detected by prenatal ultrasonography: a single center study)

  • 임진아;이주훈;박영서;김건석;원혜성
    • Clinical and Experimental Pediatrics
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    • 제52권4호
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    • pp.464-470
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    • 2009
  • 목 적 : 산전 초음파로 발견된 선천성 신 요로 기형의 빈도와 임상 결과에 대해 알아보고자 하였다. 방 법 : 1989년 10월부터 2007년 10월까지 18년간 산전 초음파에서 발견되어 출생 후 서울아산병원 소아청소년과에서 선천성 신 요로 기형이 진단된 906예를 대상으로 의무 기록과 검사 결과를 조사하였다. 결 과 : 발생 빈도는 수신증, 다낭성 이형성 신, 중복 신장, 방광 요관 역류, 단일 신, 수뇨관 신증, 이소성 신장, 다낭성 신, 요관류, 후부 요도 판막의 순이었다. 수신증은 520예로 57.4%를 차지하였으며 이 중 20%가 수술이 필요하였다. 다낭성 이형성 신은 25.4%에서 다른 동반된 신 요로 기형이 있었다. 중복 신장은 57.9%에서 수술이 필요하였다. 방광 요관 역류는 남아에서 10배 많았다. 상염색체 열성형 다낭성 신의 7예 중 2예가 만성 신부전으로 진행하였다. 후부 요도 판막은 9예(1%)로 빈도가 낮았으며, 그 중 1예가 만성 신부전으로 진행하였다. 결 론 : 산전 초음파로 발견되는 선천성 신 요로 기형은 그 종류가 다양하며 임상 결과는 많은 예에서 양호하여 특별한 처치가 필요 없는 경우도 많으나, 일부에서는 신장 기능을 감소시키는 원인이 되거나, 반복적인 요로 감염의 원인이 되어 수술이 필요한 경우가 있으며 특히 양쪽 신장에 발생하는 기형은 적절한 처치를 하지 않으면 만성 신부전으로 진행하는 원인이 될 수 있다. 그러므로 각각의 기형에 대한 정확한 분포와 임상 결과를 알기 위해서는 장기적으로 다기관 뿐 아니라 전국적인 조사 연구가 필요하다.

심장 종양의 수술적인 치료의 임상적 고찰 (Clinical Experience of the Surgical Treatment of Cardiac Tumor)

  • 방정희;우종수;최필조;조광조;김시호;박권재
    • Journal of Chest Surgery
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    • 제43권4호
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    • pp.375-380
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    • 2010
  • 배경: 심장의 원발성 종양은 아주 드문 질환이다. 이중 대부분의 경우는 양성인 점액종이고 이는 조기의 수술적인 치료로 거의 완치되는 반면 육종과 같은 악성종양은 수술적 제거가 어렵고 예후도 안 좋은 것으로 알려져 있다. 본원에서는 심장 종양으로 수술적인 치료를 했던 환자를 모아서 분석해 보았다. 대상 및 방법: 1993년 8월부터 2008년 12월까지 심장 종양으로 수술적인 치료를 하였던 28명의 환자를 대상으로 의무 기록 검토를 통한 후향적 분석을 하였다. 결과: 환자의 연령은 20세에서 76세 사이로 평균 $54.2{\pm}15.6$세였다. 남자가 11명(39%), 여자가 17명(61%)이었다. 15예(54%)에서 심부전의 증상 호전을 위해 응급 수술을 시행하였다. 술 전 주 증상은 호흡곤란이 15예(54%)로 제일 많았다. 전 환자에서 술 전 심장초음파로 진단이 되었다. 수술 시 종양의 크기는 장축이 2∼40 cm의 범위로 평균 $7.0{\pm}6.9$ cm였으며 종양의 부착부위는 18예(64%)에서 심방중격에, 9예(32%)에서 좌심방에, 2예(7%)에서 승모판막윤에, 2예(7%)에서 좌심실에 위치하고 있었다. 수술은 전 환자에서 양 심방절개를 통해 접근하였고 25예(89%)에서 완전절제가 가능하였다. 조직검사에서 육종이 4예(14%), 지방종이 1예(4%), 점액종이 23예(82%)였으며 완전절제를 못했던 3예는 모두 육종이었다. 술 후 사망은 없었다. 외래 추적은 24예(86%)에서 가능했으며 평균 추적 기간은 $46.8{\pm}42.7$개월이었다. 추적 환자 중 만기 사망은 조직검사에서 육종이었던 3명이 있었다. 육종으로 수술했던 환자로 재발 혹은 타 조직으로 전이하여 1예에서 2차례 재수술, 1예에서 전이 부위 절제술, 1예에서는 항암치료만을 했던 환자였다. 평균 재발 및 전이기간은 각각 $12.7{\pm}10.8$개월, $20.5{\pm}16.8$개월이었다. 결론: 심장 종양의 대부분인 점액종은 색전 등의 위험을 야기할 수 있으므로 조기에 수술함이 원칙이고 수술적 제거로 근본적인 치료가 가능하다. 악성종양인 육종은 발견 시 이미 상당히 진행되어 있는 경우가 많고 주위 조직으로의 침윤이 심해 수술적인 제거가 어려운 경우가 많다. 그러나 심부전 증상 등의 증상완화를 위해서는 가능한 부위의 절제를 함으로써 환자의 향후 삶의 질을 높일 수 있는 방편으로 보인다.