• Journal of Chest Surgery
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• v.32 no.2
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• pp.171-174
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• 1999

Background: Hyperhidrosis of the palms, axillae and face has a strong negative impact on social and professional life. The present existing non-operative therapeutic options seldom give sufficient relief and have a transient effect. A definitive cure can be obtained by upper thoracic sympathectomy. However, this is offset by the occurrence of a high rate of side effects, such as embarrassing compensatory sweating. Material and Method: From Sep. 1997 to Feb. 1998, 89 cases of the needle(2 mm) thoracoscopic thoracic sympathicotomy were performed. The second thoracic ganglion was resected by cutting with a endoscissors. Result: A bilateral procedure takes less than 25 min and requires just one night in hospital. There have been no mortality or life-threatening complications. One patient(<2%) required intercostal drainage because of pneumothorax. Primary failure occurred in one cases(<2%) and recurrent hyperhidrosis occurred in no cases. The patients with failure was successfully re-sympathicotomy. At the end of postoperative follow-up(median 3 months), 96.6% of the patients were satisfied. Compensatory sweating occurred in 57 cases(64.0%) with fourteen of those cases classified as either embarrassing in 10 cases(11.2%) or disabling in 4 cases(4.5%). Conclusion: Endoscopic transthoracic sympathicotomy is an efficient, safe and minimally invasive surgical method for the treatment of palmar and craniofacial hyperhidrosis.

• Nuclear Engineering and Technology
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• v.19 no.1
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• pp.22-33
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• 1987

The confirmed integrity of nuclear fuel cladding materials is an important object during steady state and transient operations at nuclear power plant. In this context, the clad material yielding behavior is especially important because of pellet-clad gap expansion. During the steep power excursion, the in-pile irradiation behavior differences between uranium-dioxide fuel pellet and zircaloy clad induce the contact pressure between them. If this pressure reaches the zircaloy clad yield pressure, the zircaloy clad will be plastically deformed. After the reactor power resumed to normal state, this plastic permanent expansion of clad tube give rise to the pellet-clad gap expansion. In this paper, the simple mandrel expansion test method which utilizes thermal expansion difference between copper mandrel and zircaloy tube was adopted to simulate this phenomenon. That is, copper mandrel which has approximately three times of thermal expansion coefficient of zircaloy-4 (PWR fuel cladding material) were used in this experiment at the temperature range from 400C to 700C. The measured plastic expansion of zircaloy outer radius and derived mathematical relations give the yield pressure, yield stress of zircaloy-4 clad at the various clad wall temperatures, the activation energy of zircaloy tube yielding, and pellet-clad gap expansion. The obtained results are in good agreement with previous experimental results. The mathematical analysis and simple test method prove to be a reliable and simple technique to assess the yielding behavior and gap expansion measurement between zircaloy-4 tube and uranium-dioxide fuel pellet under biaxial stress conditions.

• Journal of Chest Surgery
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• v.31 no.7
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• pp.668-673
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• 1998

During the past several years, the maze operation has become the most effective method of treatment for chronic atrial fibrillation. When the maze procedure is done concomittantly with other cardiac operations, surgeons, in their initial experiences, may be concerned about the additional operative risks and uncertainty of the results. We performed the Cox-maze III procedure in six cases of chronic atrial fibrillation associated with mitral, mitral & aortic, or coronary arterial disease. Maze III procedure was done with open mitral commissurotomy(3 cases), mitral valve replacement(1 case), aortic and mitral valve replacement(1 case), and two-vessel coronary bypass graft(1 case). In spite of rather prolonged aortic cross clamp time, cardiac recovery was uneventful in all cases. No cases required reexploration for postoperative bleeding. All patients showed regular sinus rhythms immediate or between 2 and 20 days postoperateratively. Transient postoperative supraventricular arrhythmarias were easily controlled by various antiarrhythmic agents. In follow up evaluations, all cases showed regular sinus rhythm on ECG and the right and left atrial transport function was confirmed by Doppler echocardiography in all except one. Though our experience was limited in case number, the Cox-maze III procedure was effective in controlling the chronic atrial fibrillation without serious additional operative risks.

• Journal of the Korea Concrete Institute
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• v.24 no.5
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• pp.567-575
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• 2012

A research was conducted to develop a 2-D nonlinear Galerkin finite element analysis of reinforced concrete structures subjected to high temperature with experiments. Algorithms for calculating the closed-form element stiffness for a triangular element with a fully populated material conductance are developed. The validity of the numerical model used in the program is established by comparing the prediction from the computer program with results from full-scale fire resistance tests. Details of fire resistance experiments carried out on reinforced concrete slabs, together with results, are presented. The results obtained from experimental test indicated in that the proposed numerical model and the implemented codes are accurate and reliable. The changes in thermal parameters are discussed from the point of view of changes of structure and chemical composition due to the high temperature exposure. The proposed numerical model takes into account time-varying thermal loads, convection and radiation affected heat fluctuation, and temperature-dependent material properties. Although, this study considered standard fire scenario for reinforced concrete slabs, other time versus temperature relationship can be easily incorporated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.1
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• pp.760-767
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• 2020

Sustainable growth of hydroelectric power plants is expected in consideration of climate change and energy security. However, hydroelectric power plants always have a risk of water hammer damage, and safety assurance is very important. The water hammer phenomenon commonly occurs during operations such as rapid opening and closing of the valves and pump/turbine shutdown in pipe systems, which is more common in cases of emergency shutdown. In this study, a computational numerical model was developed using the MOC-FDM scheme to reflect the mechanism of water hammer occurrence. The proposed model was implemented in boundary conditions such as reservoir, pipeline, valve, and pump/turbine conditions and then applied to simulate hypothetical case studies. The analysis results of the model were verified using the analysis results at the main points of the pipe systems. The model produced reasonably good performance and was validated by comparison with the results of the SIMSEN package model. The model could be used as an efficient tool for the safety assessment of hydroelectric power plants based on accurate prediction of transient behavior in the operation of hydropower facilities.

• Journal of Broadcast Engineering
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• v.13 no.4
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• pp.544-553
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• 2008

With the development of video editing technology, there are growing uses of overlay text inserted into video contents to provide viewers with better visual understanding. Since the content of the scene or the editor's intention can be well represented by using inserted text, it is useful for video information retrieval and indexing. Most of the previous approaches are based on low-level features, such as edge, color, and texture information. However, existing methods experience difficulties in handling texts with various contrasts or inserted in a complex background. In this paper, we propose a novel framework to localize the overlay text in a video scene. Based on our observation that there exist transient colors between inserted text and its adjacent background a transition map is generated. Then candidate regions are extracted by using the transition map and overlay text is finally determined based on the density of state in each candidate. The proposed method is robust to color, size, position, style, and contrast of overlay text. It is also language free. Text region update between frames is also exploited to reduce the processing time. Experiments are performed on diverse videos to confirm the efficiency of the proposed method.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.463-463
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• 2014

Dye-sensitized solar cells (DSSCs) have generated a strong interest in the development of solid-state devices owing to their low cost and simple preparation procedures. Effort has been devoted to the study of electrolytes that allow light-to-electrical power conversion for DSSC applications. Several attempts have been made to substitute the liquid electrolyte in the original solar cells by using (2,2',7,7'-tetrakis (N,N-di-p-methoxyphenylamine)-9-9'-spirobi-fluorene (spiro-OMeTAD) that act as hole conductor [1]. Although efficiencies above 3% have been reached by several groups, here the major challenging is limited photoelectrode thickness ($2{\mu}m$), which is very low due to electron diffusion length (Ln) for spiro-OMeTAD ($4.4{\mu}m$) [2]. In principle, the $TiO_2$ layer can be thicker than had been thought previously. This has important implications for the design of high-efficiency solid-state DSSCs. In the present study, we have fabricated 3-D Transparent Conducting Oxide (TCO) by growing tin-doped indium oxide (ITO) nanowire (NWs) arrays via a vapor transport method [3] and mesoporous $TiO_2$ nanoparticle (NP)-based photoelectrodes were prepared using doctor blade method. Finally optimized light-harvesting solid-state DSSCs is made using 3-D TCO where electron life time is controlled the recombination rate through fast charge collection and also ITO NWs length can be controlled in the range of over $2{\mu}m$ and has been characterized using field emission scanning electron microscopy (FE-SEM). Structural analyses by high-resolution transmission electron microscopy (HRTEM) and X-Ray diffraction (XRD) results reveal that the ITO NWs formed single crystal oriented [100] direction. Also to compare the charge collection properties of conventional NPs based solid-state DSSCs with ITO NWs based solid-state DSSCs, we have studied intensity modulated photovoltage spectroscopy (IMVS), intensity modulated photocurrent spectroscopy (IMPS) and transient open circuit voltages. As a result, above $4{\mu}m$ thick ITO NWs based photoelectrodes with Z907 dye shown the best performing device, exhibiting a short-circuit current density of 7.21 mA cm-2 under simulated solar emission of 100 mW cm-2 associated with an overall power conversion efficiency of 2.80 %. Finally, we achieved the efficiency of 7.5% by applying a CH3NH3PbI3 perovskite sensitizer.

• The Korean Journal of Pharmacology
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• v.2 no.1 s.2
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• pp.49-69
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• 1966

For the purpose of stydying the pharmacodynamic action of methemoglobin, the author made the following experiments: 1. Preparation of hemoglobin and methemoglobin solutions: Red cell suspension from rabbit blood was hemolysed with distilled water and then divided into two portions. One portion was dialysed through cellophane paper and made isotonic with the proper amount of sodium chloride. The second portion was treated with sodium nitrite to convert hemoglobin to methemoglobin, dialysed through cellophane paper and made isotonic. 2. The concentration of methemoglobin in solution, plasma and urine was determined by Horecker and Brackette's method, and that of hemoglobin by the cyanmethemoglobin method. 3. The concentration of methemoglobin and hemoglobin in the plasma and urine of rabbits was measured at several intervals of time after infusion of the above samples. 4. The blood pressure and respiration of rabbits were recorded on a kymograph, and the effects of the samples on them were observed. 5. The effects of the samples on the movements of the in-situ heart and the isolated intestine of rabbits were studied. 6. The kidneys of rabbits were excised 4 to 5 hours after injection of the samples, and histopathological examinations were made. These experiments revealed the following results: 1. When methemoglobin solution was allowed to stand in room air, there was no decrease in the concentration of methemoglobin. 2. When methemoglobin solution was mixed with whole blood and incubated at $37^{\circ}C$, the concentration of methemoglobin decteased gradually. 3. After the infusion of methemoglobin and hemoglobin solutions, the rate of disappearance of methemoglobin in the plasma was more rapid than that of hemoglobin in the plasma. The higher the initial concentration in the plasma, the larger was the rate of disappearance of methemoglobin. 4. The rate of disappearance of methemoglobin was exceedingly rapid for 30 minutes after the infusion. 5. The urinary excretion of methemoglobin was more rapid than that of hemoglobin. 6. It would seem that the circulating blood contains substances which are promptly mobilized in the plasma to reduce methemoglobin to hemoglobin. 7. Moderate amounts of methemoglobin solution caused some rise in the blood pressure and a transient acceleration of the respiration of the rabbits. These effects of methemoglobin were milder than those of hemoglobin. 8. The movements of the in-situ heart and the isolated intestine of rabbits were accelerated by methemoglobin. These accelerating effects were milder than those of hemoglobin. 9. In the kidneys of rabbits treated with methemoglobin solution, hyperemia of the glomeruli, cloudy swelling and hemoglobin deposit in the tubular epithelium, hemoglobin casts in the tubular lumina of the proximal tubules, and interstitial congestion were constantly observed. There was no definite difference between the histological findings in the rabbit kidneys injected with methemoglobin, and those injected with hemoglobin solutions.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.22-30
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• 1995

To predict preoperatively the safety of permanent occlusion of an internal carotid artery with $^{99m}Tc$-HMPAO brain single photon emission computed tomography(SPECT) from an objective point of view, Twenty-four patients underwent balloon test occlusion (BTO) of the internal carotid arteries because of neck and skull base tumors. The authors assessed the uptake of both middle cerebral artery territories before and during BTO with $^{99m}Tc$-HMPAO brain SPECT using semiquantitative analysis method and compared the results with other factors(neurologic examination, arterial stump pressure and electroenceph-alogram). Nineteen patients had not experienced neurological deteriorating or any problem during BTO. Their comparative uptakes of the middle cerebral artery territories were 95 to 101% of the pre-BTO state. The remaining five patients showed severe neurologic symptoms such as transient hemiplegia and unconsciousness. Their comparative uptake of the middle cerebral artery territories were 77 to 85% of the pre-BTO state, and were well matched with other factors. $^{99m}Tc$-HMPAO brain SPECT before and during BTO seems to be a simple and objective method for prediction of permanent neurologic deficits when the comparative uptake of middle cerebral artery territories during BTO is lower than 85% of that before BTO.

• Journal of Chest Surgery
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• v.32 no.1
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• pp.22-26
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• 1999

Background: Treatment of adult patent ductus arteriosus(PDA) has many difficulty such as pulmonary hypertension, arterial wall calcification, aneurysmal chage of ductus. We tried to evaluate the effect of surgical interruption of PDA on postopeative change of heart size. Material and Method : From 1987 to 1997 we experienced 30 cases of the ligation of patent ductus arteriosus in adult at the department of cardiovacular surgery in Masan Samsung General Hospital. Result: There were 9 males and 21 females and their ages ranged from 16 to 44 years, with a mean age of 26.1 years. 15 patients had pulmonary hypertension and 9 patients complained of dyspnea with a degree of functional NYHA class III. Operation method was double or triple ligation using Teflon felt. Postoperative complications were wound dehiscence in 3 patients and transient hoarseness in 1 patient. The mean preoperative cardiothoracic ratio was 54.7%, and mean postoperative cardiothoracic ratio was 51.9%. The change of cardiothoracic ratio was more typical in the cases who had congestive heart failure. Their mean preoperative cardiothoracic ratio was 64.8% and the mean postoperative cardiothoracic ratio was 58.5% there was no postoperative deaths. Conclusion: We canclude that the improvement in cardiothoracic ratio may result from surgical intervention of PDA.