• The Korean Journal of Pharmacology
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• v.32 no.3
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• pp.357-371
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• 1996

Lithium (Li) is known to be used not only during acute manic psychosis but also acute depressive phase in manic-depression. In the present study, it was attempted to investigate the effect of lithium on catecholamine (CA) secretion from the isolated perfused rat adrenal gland and to clarify the mechanism of its action. Replacement of $Na^+$ (118.4 mM) by lithium in the normal Krebs-bicarbonate solution used to perfuse the gland produced gradually an increased response in the spontaneous catecholamine release, which was peaked at $30{\sim}60$ min after its perfusion. Li-Krebs solution was perfused into an adrenal vein for 2 hours in every experiments. Li-Krebs-evoked CA secretory responses were depressed significantly under loading with $Ca^{++}-free$ medium. This CA secretion evoked by lithium loading was also reduced markedly by the pretreatment with nicardipine ($10^{-6}$ M), TMB-8 ($10^{-5}$ M) and chlorisondamine ($10^{-6}$ M) for 20 min, respectively, while was not affected by preloading with a pirenzepine ($2{\times}10^{-6}$ M)-containing Krebs. $Na^+$ pump inhibition by pretreatment with ouabain ($10^{-4}$ M) for 20 min did make the marked depression in Li-evoked CA secretory responses. Moreover, Li-evoked CA release was also diminished markedly by preloading with tetrodotoxin ($5{\times}10^{-7}$ M)-contaming Krebs for 20 min. All these experimental results taken together suggest that lithium enhances CA secretion in a $Ca^{++}$-dependent fashion by its accumulation in the adrenomedullary chromaffin cells of the rat, and that this secretory effect may be meidated by a dual mechanism: (i) chromaffin cell depolarization and subsequent opening of voltage-sensitive $Ca^{++}$ channels and (ii) activation of a $[Li]_i-[Ca]_0$ counter-transport system.

• Journal of Chest Surgery
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• v.35 no.5
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• pp.365-368
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• 2002

Background: Coronary artery bypass grafting(CABG) imposes large amount of medical costs, which are greatly affected by the surgical approach, quality of perioperative care and associated co-morbidities. Recently, off-pump CABG(OPCAB) has been introduced and performed with increasing frequency. To evaluate the efficacy of OPCAB in view of financial impact, we analyzed the costs and medical resources of OPCAB and compared with conventional CABG. Material and Method: From January 1998 to July 1999, 184 patients underwent CABG operation; 111 patients with OPCAB(group I) and 73 patients with conventional CABG(group II). We prospectively collected clinical data including risk factors and retrospectively reviewed the hospital resources. Result: Preoperative parameters including risk factors, postoperative mortality, morbidity and length of hospital stay were not different between the two groups, Duration of stay in the intensive care unit(ICU) (51.3 vs 128.3 hours, p<0.01) and ventilator, support time(14.9 vs 56.2 hours, p<0.01) were significantly shorter in the OPCAB group. Total hospital coats were 17,220,000 add 21,250,000(Korean Won) in group I and II, respectively(p<0.01). There were significant differences in operation fee, costs for operative materials, transfusion and diagnostic radiology between two groups. In group I, all the resources except diagnostic radiology were significantly decreased compared with group II. Conclusion: OPCAB has a beneficial effect on hospital charge and resource utilization. Shorter duration of the ICU stay and ventilatory support time may reduce the total hospital costs.

• Journal of Chest Surgery
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• v.35 no.11
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• pp.779-784
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• 2002

Recently, the number of coronary artery bypass surgery(CABG) is increasing according to the increasing incidence of coronary artery disease. However, CABG is not a definite corrective surgery; therefore, in some patients, redo-CABG may be required. We retrospectively reviewed our redo-CABG experiences to help future redo-CABG. Material and Method: From January 1991 to April 2001, 14 cases of redo-CABG were performed in Yonsei Cardiovascular Center(M:F＝12:2) and mean age was 61,7 $\pm$ 7.1(47-72) years. Mean time from 1st. CABG to redo-CABG was 121.9 $\pm$ 50.5(6.1-179.6) months. Thirteen cases were conventional on-pump CABG and one case was off-pump CABG. In two patients, mitral valve re-replacement and mitral valve repair were performed each. All redo-CABG were performed through mid-sternotomy. During redo-CABG, left internal mammary artery and saphenous vein grafts were used in 6 patients, left internal mammary artery and left radial artery grafts were used in 2 patients, left internal mammary artery and gastroepiploic artery were used in one patient and only greater saphenous veins were used in 5 cases(In one case, cephalic vein was also used). The number of mean distal anastomosis was 2.1 $\pm$ 0.9(1-4). Result: There were no operative death and no perioperative myocardial infarctions and cerebrovascular accidents or other heart related complications. Mean follow up duration was 40.1 $\pm$ 38.6(1.1-118.5) months. During follow up period, angina was re-developed in one patient 13 months after operation. Two patients died of end-stage renal failure 14.8 months and 116.3 months after redo-CABG, respectively. During follow up period, coronary angiography was performed in 3 patients, and all grafts were patent. At last follow up, mean Canadian class was 1.3. Kaplan-Meier survival at 9 years was 90.0 $\pm$ 9.5% and event free survival at 9 years was 71.4 $\pm$ 6.9%. Conclusion: After redo-CABG, all patients improved their angina symptom and daily activity. And long-term survival after redo-CABG was excellent. Therefore, if patients have indications for redo-CABG, thenredo-CABG must be strongly recommended and performed.

• Journal of Chest Surgery
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• v.39 no.10 s.267
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• pp.754-758
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• 2006

Background: Surgical role for acute coronary syndrome has been reduced in recent years due to development of drug eluting stent. We evaluated the surgical results of acute coronary syndrome in our hospital. Material and Method: Between January 2001 and August 2005, 416 patients underwent coronary artery bypass grafting (CABG) under diagnosis of non-ST-elevation acute coronary syndrome (NSTE ACS). Mean age was $61.8{\pm}9.0$ years and 276 (66.3%) patients were male. 324 (77.9%) patients had triple vessel disease and 92 (22.1%) had left main disease at angiographic study. 236 (56.7%) patients had hypertension and 174 (41.8%) had diabetes mellitus. Conventional on-pump CABG was performed in 194 patients (46.6%) and off-pump CABG in 222 (53.4%). Total arterial revascularization with no touch technique was done in 97 patients (23.3%). The number of total distal anastomosis was 1,306 and the number per patient was $3.21{\pm}1.71$. Result: Surgical mortality rate was 1.0% (4 patients) and postoperative complication rate was 15.6% (65 patients). Graft patency was checked at mean $3.7{\pm}7.6$ months (from 1 to 37 months) postoperatively with multi-directional computed tomography in 152 patients. Left internal mammary artery was patent in 95.3%, right internal mammary artery in 98.1%, radial artery in 92.2% and saphenous vein in 89.0%. Conclusion: The surgical treatment of NSTE ACS showed relatively low mortality rate and good graft patency rate. Further study is needed to compare the long term results with drug eluting stent.

• Journal of Chest Surgery
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• v.47 no.2
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• pp.100-105
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• 2014

Background: We evaluated the safety and efficacy of percutaneous extracorporeal membrane oxygenation (ECMO) in patients with primary graft dysfunction after heart transplantation. Methods: Of 65 patients (44 males and 21 females) who underwent heart transplantation from January 2006 to December 2012, 13 patients (group I) needed peripheral ECMO support due to difficulty in weaning from cardiopulmonary bypass (CPB) and 52 patients (group II) were weaned from CPB without mechanical support. The mean age of the patients at the time of operation was $54.4{\pm}13.6$ years. There were no differences in the preoperative characteristics of the two groups. Multivariable analysis was performed to identify the risk factors for ECMO therapy. Results: All group I patients were successfully weaned from ECMO after $53{\pm}9$ hours of circulatory support. Early mortality occurred in four patients (1 [7.7%] in group I and 3 [5.8%] in group II, p>0.999). There were no differences in the postoperative complications between the two groups, with the exception of reoperation for bleeding. A greater number of group I patients underwent reoperation for bleeding (5 [38.5%] in group I vs. 6 [11.5%] in group II, p=0.035). In multivariable analysis, preoperative mechanical support (ECMO and intra-aortic balloon pump) and longer CPB time were the risk factors of ECMO therapy for graft dysfunction (odds ratio, 6.377; 95% confidence interval, 1.519 to 26.77; p=0.011 and odds ratio, 1.010; 95% confidence interval, 1.001 to 1.019; p=0.033). Conclusion: Percutaneous ECMO support could be a viable option for rescuing patients when graft dysfunction refractory to medical management develops after heart transplantation.

• Journal of Chest Surgery
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• v.38 no.10 s.255
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• pp.717-720
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• 2005

Here we report a case of posterior left ventricular (LV) free wall rupture following postinfarct ventricular septal rupture (VSR). A 58-year-old man was transferred to the hospital under the impression of acute myocardial infarction. Posterior VSR was seen on echocardiographic examination. The intraaortic balloon pump catheter was introduced percutaneously and the emergent operation was proposed. Sudden circulatory collapse was developed shortly after the anesthetic induction and the patient's chest was hurriedly opened while on cardiopulmonary resuscitation. The acute cardiac tamponade was seen and the blood was seen pumping from the longitudinal tear at the mid-level of LV posterior wall, measuring 2 cm in length. The cardiopulmonary bypass was set and LV reconstruction was done. The postoperative recovery was delayed due to the brain injury presumably caused by preoperative cardiac arrest.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.622-628
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• 2016

As the suction pad-supporting bike carrier attached to a car may be subject to an excessive dynamic load due to random vibrations and centrifugal forces during driving, its structural safety is of great concern. To examine this, the finite-element method with a fluid-structure interaction should be used because the pressure on the pad bottom is changed in real time according to the fluctuations of the force or the moment applied on the pad. This method, however, has high computing costs in terms of modeling efforts and software expense. Moreover, the accuracy of computation is not easily guaranteed. Therefore, a new method combining the experiment and computation is proposed in this paper: the bottom pressure and contact area of the pad under varying loads was measured in real time and the acquired data are then used in the nonlinear elastic finite-element calculations. The computational and experimental results obtained with the product under development showed that the safety margin of the pad under the axial loading is relatively sufficient, whereas with an excessive rotational loading, the pad is vulnerable to separation or a local surface damage; hence, the safety margin may not be secured. The predicted contact behavior under the variation of the magnitude and type of the loading were in good agreement with the one from the experiment. The proposed analysis method in this study could be used in the design of similar vacuum pad systems.

• Journal of the Korean Society of Safety
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• v.12 no.4
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• pp.214-219
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• 1997

The mechanical seals, which are installed in rotating machines like pump and compressor, are generally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage, crack, breakage, fast and severe wear, excessive torque, and squeaking results in big problems. To identify abnormal phenomena on mechanical seals and to propose the proper monitoring parameter for the failure of mechanical seals, sliding wear experiments were conducted. Acoustic emission, torque, and temperature were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. Except for the initial part of every experiment, the variation of acoustic emission was well coincided with torque variation during the experiments. This study concludes that acoustic emission and torque are proper monitoring parameters for the failure of mechanical seals. The intensity of acoustic emission signals is measured in root mean square voltage. Temperature of sealing face will be used as a parallel parameter for increasing the reliability of monitoring system.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.154-154
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• 2011

화석연료의 가격 및 공급의 불안정과 온실가스감축 국제 규제 강화 등에 대한 대안으로 여기는 신 재생에너지는 높은 초기 투자 부담으로 인하여 관련기술의 연구개발과 보급정책 등 전과정에 걸친 정책 지원체계가 필요하다. 본 연구에서는 지열에너지를 이용하는 지열냉난방기술에 중점을 두고 이에 대한 중장기 정책 포트폴리오 작성을 위한 기술 및 정책적 접근방안을 제시하고자한다. 지열에너지의 가장 큰 특징은 기후 등에 영향을 크게 부하가 변하는 태양광, 풍력 등과 달리 일정한 부하를 유지함으로써 안정적인 에너지공급이 가능하다는 것이다. 또, 품질 측면에서도 화석연료를 이용한 기존의 연료보다 쾌적한 환경을 조성하여 고급에너지로 평가받고 있다. 반면, 설비를 갖추기 위한 천공, 히트펌프 설치 등에 큰 비용이 든다는 단점을 가지고 있다. 현재 히트펌프 제작기술은 국산화를 완료한 상태로 사실상 기술개발에 의한 큰 폭의 원가절감은 기대하기 힘든 상황이다. 하지만, 유사분야인 시스템 에어컨이 표준화 및 대량생산을 통한 시장 보급 확대로 보급단가가 하락한 것을 고려해 볼 때 이를 통한 가격하락은 어느 정도 기대해 볼 수 있을 것으로 생각된다. 에너지 외적인 측면에서 볼 때도 지열에너지의 공급은 상당한 의미를 갖는다. 건물 냉 난방용 이외에 다양한 용도의 개발을 통해 비닐하우스나 온실 등에 지열에너지를 이용할 경우 정부차원에서 농어촌에 대한 지원이 가능하다. 또, 기존의 에너지원을 조달하는데 어려움이 있는 산간, 도서지방에서는 도시지역보다 투자대비 큰 효과를 볼 수 있어 지역간 에너지 불균형 해도에도 도움이 될 수 있다. 이와같은 지열에너지의 특성에 따라 향후 발전방향을 정리해 보았다. 핵심기술인 지열 히트펌프의 산업구조와 시장 보급 확대를 통한 가격하락을 기대한다. 지역개발 및 고립지역에서 타 신 재생에너지와 함께 독립적인 전력, 냉난방 등의 완전 에너지 공급시스템을 갖출 수 있다. 또한 특수 작물 등의 고급 농수산물 생산등의 용도개발을 통해 지열에너지 공급역량을 성장시킬 수 있을 것이다. 이와 함께 중장기 비젼을 제시하기 위해 추진되어야 할 연구과제로는 시장 보급 확대에 따른 가격경쟁력 도달 가능성에 대한 연구를 통해 산업육성 방안 마련, 타 신 재생에너지기술과 복합 설치에 의한 시너지 효과 및 이에따른 초기 투자비 증가에 대한 대책, 보급 잠재량 조사, 지열시스템의 자금 조달 및 관련 정책 검토 등이 있을 수 있다.

• Korean Journal of Agricultural Science
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• v.12 no.1
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• pp.139-152
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• 1985

본 NEWASA 지역의 접수관정관개 개발에 따른 정제성분석 연구는 IBRD-EDI와 INDIA RESERVE BANK의 College of Banking이 공동주최한 Trainers Trining for Rural Finance (1985. 1.19-3.1)의 일환으로 1985. 2. 14-19 까지 NEWASA BLOCK에 대한 정수정관개의 경제적 효율성을 평가하기 위하여 농가조사를 실시하였고, 그 분석결과를 정리한 것으로 농지는 넓으나 농업용수가 부족한 본 지역은 빈곤과 저생산성 농촌잠재 실업을 특징으로 하고 있다. 농촌소득의 제고와 농촌실업의 고용확대는 전 인구의 80% 이상이 농민인 본지역뿐만 아니라 선언도 경제개발의 중심과제이다. 호당 6 acres 규모의 관개가 가능한 Dug-well Irrigation Development는 연평균 강우량이 650m/m에 불과한 인도의 Plateau 지역에서는 농촌빈곤과 실업문제의 해결, 토지 이용율제고를 통한 토지생산성 향상등 농촌경제개발의 중심과제로서 인도정부가 추진하는 핵심적인 농업정책이다. 본 지역의 농가호당 평균 소유농지연적은 8.67 acres(3.5ha)로써 모두가 Rainfed farming으로 현재 본 지역의 관개율은 17.5%에 불과하다. 농작물은 Jowar라고 하는 내한성 작물이 재배되며, 관개 조건하에서는 Jowar, Wheat, Sugarcane이 재배된다. With and Without Dug-Well Irrigation 조건하에서 각 작물별 ha당 생산성을 보면 Jowar는 0.86 ton/ha에서 2.22 ton/ha으로 증산되고 Wheat는 2.96 ton/ha, Sugarcane는 98.8 ton/ha이 생산된다. 한편 Dug-well Irrigation 전후의 농가소득의 변화를 보면 시행전의 4,275Rs가 되어 4배의 농가소득이 증가된다. 이와 같은 농업소득을 획득하기 위해서는 Dug-well에 대한 Initial Investment로서 33,400Rs(2,137,600원)이 투자되어야 하는데 종류별 융자 기간을 보면 Dug-well 15년(95%융자) Pump Set 9년(95%융자), Woriking capital 1년이며 인도의 Union Bank에서 융자하고 있다. 결론적으로 이러한 Dug-well Irrigation Development에 따른 IRR는 Before Financing시에는 29%이며 After Financing 시에는 24%이고 B/C ratio는 두경우에 있어 1.89, 1.24를 각각 나타냈다. 따라서, 본 사업은 재무적인 측면 즉 농가소득증대와 농촌고용증대 및 토지이용면에서 타당성이 크며 Dug-well Irrigation은 인도의 농업성장 및 경제개발의 관건으로 생각된다. 한국의 수리개발 기술 및 농업기술(Bio-chemical, Mechanical & Hydrological Technology)이 이전된다면 보다 괄목할 만한 농업발전이 이룩될 것을 생각된다.