• 설비공학논문집
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• 제23권1호
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• pp.38-46
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• 2011

The hybrid defrost process combined with hot-gas bypass defrost and electric heater defrost was experimentally evaluated about its defrost performance in the fin-tube evaporators of household refrigerators. Also the hybrid defrost process was compared with only electric heater defrost process. The defrost efficiency of the hybrid defrost process was shown two times higher than electric heater defrost process. The defrost time of the hybrid defrost process was shorten about 10%~50% than electric heater defrost process. Thermal shock after defrost process was decreased about 50% for the case of the hybrid defrost. It was found that energy consumption ratio of defrost process was reduced up to 7.4% compared with 22.4% of electric heater defrost at the condition of $25^{\circ}C$ ambient temperature.

• Journal of Chest Surgery
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• 제26권5호
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• pp.355-359
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• 1993

Ten consecutive patients with abdominal aortic aneurysm were treated in Chungnam National University Hospital from May of 1985 to June of 1993. Pulsating palable mass was the most common first sign [7 patients]. The ratio of male to female was 8:2. The age ranged from 53 to 73 years with mean age of 65 years. The etiology and location of the aneurysm was atherosclerosis and infrarenal aorta in all. Dacron graft interposition [straight graft-1, bifurcation graft-7] and wrapping with aneurysmal sac were performed in 8 patients. In one patient with infected abdominal aortic aneurysm, we performed aneurysmectomy and left axillo-bifemoral bypass with 8 mm PTFE graft. And in another patient with complete thrombotic obstruction of infrarenal aortic aneurysm, we performed the suturing of the proximal part of the abdominal aortic aneurysm and aorto-bifemoral bypass with 18 x 9 mm PTFE graft. There was one operative death with the mortality rate of 11 % and 8 complications in 4 patients; ARF[2], duodenal ulcer[1], mechanical ileus[1], genitourinary dysfunction[2] and wound infection with abdominal abscess[1]. Because of the high operative mortality after rupture of the aneurysm, we think it is better to operate on early at the diagnosis of abodominal aortic aneurysm is made.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제37회 추계학술대회논문집
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• pp.842-849
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• 2011

Open Rotor 엔진은 차세대 항공기를 위한 잠재적 기술향상을 제공할 수 있는 여러 신기술중의 하나이다. Open Rotor 엔진은 일반적 고바이패스 터보팬 엔진보다 향상된 추진 저하율을 가지며 고바이패스비와 공기역학적 진보한 형상의 팬 블레이드 설계의 결합으로 우수한 연료소모율을 구현한다. Open Rotor 엔진 성능 모델은 F404 터보제트 엔진를 코어로 사용한 GE36 엔진의 설계 및 시험데이터를 기반으로 해석하였다. 시험데이터를 이용하여 Open Rotor 엔진 성능 모델을 검증하였으며 최신 차세대 터보프롭 엔진 성능과의 비교를 통하여 적절하게 구성되었음을 확인하였다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.38-39
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• 2019

Mechanical properties of concrete containing furnace slag according to the CBS Dust Replacement Ratio were analyzed. The experimental study found that the compressive strength was excellent in the early age when the CBS Dust was replaced, and the drying shrinkage was excellent, and the replacement of CBS Dust 5% on the concrete containing the furnace slag would have a positive effect.

• Journal of Chest Surgery
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• 제37권6호
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• pp.511-516
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• 2004

배경: 관상동맥우회술 시 내유동맥편의 골격화 채취법의 이론적인 장점들의 하나는 골격화 채취가 내유동맥의 채취에 필연적으로 수반되는 흉골로의 혈류 공급의 감소를 최소화시킨다는 것이다. 저자들은 술 전과 술 후 각각 골주사를 통하여 좌측 및 우측 흉골로의 흡수율을 비교 분석하여, 술 후 내유동맥편의 채취 방법에 따른 흉골로의 혈류 감소의 차이를 증명하고자 하였다. 대상 및 방법: 2002년 4월부터 2003년 3월까지 시행한 48예의 관상동맥우회술 환자들 중 술 전 및 술 후 1일째 골주사를 시행한 27예의 환자를 대상으로 하였다. 8예의 환자에서 양측 내유동맥을 모두 사용하였으며(BIMA군), 19예의 환자에서 좌내유동맥만을 사용하였는데(LIMA군), 이 중 골격화 채취를 하여 사용한 환자가 12예(LIMA_skel군), 경상 채취하여 사용한 환자가 7예(LIMA_ped군)였다. 골주사를 시행 후 임의의 정중선을 기준으로 흉골의 좌측 부분에 관심 영역을 그리고 흉골의 반대편에 이 영역의 대칭영상을 만들어 또 하나의 관심 영역을 만든 후 각 관심 영역의 화소 당 평균 계산치를 택하여 좌우비를 산출 하였다. 결과: LIMA군에서 좌우비는 수술 전 94.6$\pm$4.1%에서 술 후 87.9$\pm$6.9%로 감소한 반면(p=0.003), BIMA군에서는 통계적으로 유의한 변화를 보이지 않아 좋은 대조를 보였다. LIMA_skel군 과 LIMA_ped군에서의 좌우비는 각각 수술 전 95.3$\pm$4.2% 및 93.4$\pm$3.9% 에서 술 후 88.3$\pm$7.7% 및 87.4$\pm$5.8%로 감소하였으나 감소 정도를 분율로 표시하였을 때 LIMA_skel군이 -7.44$\pm$7.08, LIMA-ped 군이 -6.17$\pm$9.08로 통계적인 유의성은 없었다. 결론: 술 후 흉골의 골주사 흡수의 감소는 내유동맥의 채취가 채취방법에 상관없이 동측의 흉골의 혈류 공급을 감소시킴을 시사하였다. 내유동맥의 골격화 채취가 비골격화 채취에 비하여 흉골의 혈류 공급의 보존 측면에서 월등한 이점을 보이지는 않았다.

• 한국유체기계학회 논문집
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• 제15권5호
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• pp.27-31
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• 2012

Turbine inlet temperature is steadily increasing to achieve high specific thrust and efficiency of gas turbine engines. Turbine cooling technology is essential to increase turbine inlet temperature. For this study, a small or medium sized aircraft engine of 10,000 lbf class with the turbine inlet temperature of $1,400^{\circ}C$, the engine overall pressure ratio of 32.2, and the bypass ratio of 5 was set as the baseline model and its performance analysis was performed at the design point. The engine has the performance of 10,013 lbf thrust and the specific fuel consumption of 0.362 lbm/hr/lbf. The thrust and the specific fuel consumption of the baseline model were compared with those of similar class engines. Based on these results, the turbine design requirements were assigned. In addition, the parametric analysis of the engine, related to aerodynamic and cooling design of the high pressure turbine, was performed. Based on the baseline model engine, the influence of turbine inlet temperature, cooling flow ratio, and high pressure turbine efficiency variations on the engine performance was analyzed.

• 대한토목학회논문집
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• 제37권1호
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• pp.239-246
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• 2017

국내 중소하천의 횡단구조물인 보 또는 낙차공은 대부분 고정식 콘크리트 구조물이며, 저층수의 배제가 쉽지 않다. 횡단구조물로 인해 유사가 퇴적되며, 유사에 흡착한 오염물들이 그대로 하천의 바닥을 오염시키고 있다. 이에 저층수 및 퇴적유사에 대한 관심이 증가하고 있는 실정이며, 이러한 대안의 하나로 횡단구조물 상류와 하류를 하상 아래로 연결시키는 구조물로써, 보 상류 저층의 물 및 유사 배제를 목적으로 저층수배출관을 설치하는 방안이 있다. 그러나 사석이 유입되고, 배제 되지 않을 경우 효율성이 크게 저하될 가능성이 있다. 이에 본 연구에서는 저층수 배출관 내 사석을 배제할 수 있는 능력에 대한 연구를 수행하였다. 사석과 거동이 유사한 유사(sediment)의 한계조건(critical condition) 중 한계전단력(critical shear stress) 유도과정과 달랑베르의 원리(d'Alembert principle)를 응용하여 이동 중인 사석이 배제될 수 있는 조건(${\tau}_c{^*}$)을 유도하였다. 그러나 저층수 배출관 내 유입된 사석은 정지상태가 아닌 이동 중이므로, Lagrangian 기법을 활용하여 수리실험에서 도출된 유속으로 상대속도(relative velocity)를 제시하였다. 수리실험은 축척효과(scale effect)를 최소화하기 위해 폭이 5.0 m이고, 높이가 1.0 m인 광폭 개수로를 제작하였으며, 사용된 사석은 가공된 완전 구형을 사용하였다. 실험 결과 유속과 구형 입자 속도와의 비가 0.5~0.7 사이로 나타났으며, 이러한 결과를 유도된 식에 적용하여, 최종적으로 사석이 배제되는 조건을 도출하게 되었다. 구간은 입자레이놀즈수($Re_p$)와 무차원 한계 전단력(${\tau}_c{^*}$)에 따라 크게 3가지로 구분되었다. 배제 구간(exclusion section), 확률적 배제 구간(probabilistic exclusion section), 비배제 구간(no exclusion section)이다. 본 연구결과는 횡단구조물의 저층수 배출관 설계시 유용한 기초 정보를 제공할 수 있을 것이다.

• Journal of Chest Surgery
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• 제25권12호
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• pp.1570-1577
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• 1992

The vascular surgery is the field that has developed in early 20 century and is progressing nowadays. Recent advance in surgical technique accompanying with excellent medical diagnosis and treatment, prompt angiographic usage, development of variable prosthetic material, and concomitant use of anti-coagulant have made remarkable results of vascular surgery. 83 cases of vascular surgery have been performed at Thoracic and Cardiovascular Surgery Department of Pusan National Unversity Hosaital since 1971 till 1990, for 20 years and their results are followed. Patient ductus arteriosus and Buerger`s disease were omited in this study. 1. The age distribution shows that the fifth and sixth decades are most frequently affected and mean age was 56.1 years old. Male to female ratio is 1: 2.32. 2. Among the 83 cases of all, number of occlusive vascular disease is 46 and that of aneurysmal disease is 33. 3. In clinical manifestation, most common symptom of occlusive disease is pulselessness and pain was next. Mass sensation is most commonly complained by patients of aneurysmal disease. 4. CT scan was more important in diagnosis of aneurysmal diseases and angiogram was more commonly used in occlusive diseases. 5. The common site of arterial occlusion was common iliac artery, femoral artery, aortic bifurcation, and external iliac artery, as its frequency rate. The most commonly affecting portion of aortic aneurysm was abdminal aorta, and descending thoracic aorta and femoral artery were next 6. Preoperative associated diseases were atherosclerosis[41 cases], hypertension[21 cases], valvular heart disease[11 cases], and diabetes mellitus[9 cases], etc, 7. Operative methods in ocllusive diseases were thrombectomy[36.9%], endarterectomy [10.9%], and bypass graft insertion[52.7%]. Among the bypass graft, Y-graft was used in 7 case, straight graft was used in 17 cases, and saphenous venous graft was used in 2 cases. 8. Postoperative complications were developed in 17 cases, and morbidity rate was 36. 9. Eleven patient were died within 1 month after operation, so operative mortality rate was 13.3%. 10. Duration of patency was beteween 7 and 58 months[average 27.5 months] in occlusive diseases and their 5-year patency rate was 56.3%. Duration of patency of aneurysmal disease was 20 months in aveage and their 5-year patency rate was 51.3%. 11. Patients of eleven cases of occlusive disease and two cases of aneurysmal disease required reoperation for variable reason. 12. 35 cases of patient have used anticoagulants: coumadin, ticlid, and persanthin-ASA combination.

• Journal of Chest Surgery
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• 제18권4호
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• pp.692-699
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• 1985

Fifty cases of Open Heart Surgery due to congenital and acquired heart disease were done using the cardiopulmonary bypass in the Department of Thoracic and Cardiovascular surgery, Chosun University Hospital from November, 1980 to June, 1985. 1. The age of the congenital heart disease was from 7 to 29 years, the mean age was 14.5 years. In the acquired heart disease, the age was from 14 to 48 years, and the mean age was 22.3 years. The ratio of male to female was about 1.8:1. 2. The number of congenital cyanotic heart disease were 7 patients, congenital acyanotic heart disease were 17 patients and acquired valvular heart disease were 26 patients. All of the acquired heart disease was one or more valve disease. 3. Preoperative symptoms of the congenital heart disease were exertional dyspnea [cyanotic 100%, acyanotic 70.6%] and palpitation [cyanotic 28.6%, acyanotic 76.1%], and the acquired heart diseases were exertional dyspnea [92.3%], palpitation [34.1 %], and chest discomfort [30.8%]. 4. The method of the myocardial protection during the cardiopulmonary bypass were mild or moderate hypothermia, intermittent coronary perfusion of the cardioplegic solution, topical myocardial hypothermia with 4oC Hartmann`s solution. 5. In the cases of the valve replacement, postoperative oral anticoagulant therapy was started at oral intake of food using the warfarin and persantin, and the prothrombin time was maintained 30-50% of control value during 3-6 months for tissue valve replacement and permanently for metal valve replacement. 6. The postoperative complications were appeared in 24 cases and the complications were wound infection, occipital alopecia, hemorrhage etc. 7. The mortality after open heart surgery was 8 percents and the cause of death was low cardiac output syndrome, right heart failure, DIC, and Left ventricle rupture.

• Journal of Preventive Medicine and Public Health
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• 제57권3호
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• pp.260-268
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• 2024

Objectives: Regional disparities in cardiovascular care in Korea have led to uneven patient outcomes. Despite the growing need for and access to procedures, few studies have linked regional service availability to mortality rates. This study analyzed regional variation in the utilization of major cardiovascular procedures and their associations with short-term mortality to provide better evidence regarding the relationship between healthcare resource distribution and patient survival. Methods: A cross-sectional study was conducted using nationwide claims data for patients who underwent coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), stent insertion, or aortic aneurysm resection in 2022. Regional variation was assessed by the relevance index (RI). The associations between the regional RI and 30-day mortality were analyzed. Results: The RI was lowest for aortic aneurysm resection (mean, 26.2; standard deviation, 26.1), indicating the most uneven regional distribution among the surgical procedures. Patients undergoing this procedure in regions with higher RIs showed significantly lower 30-day mortality (adjusted odds ratio [aOR], 0.73; 95% confidence interval, 0.55 to 0.96; p=0.026) versus those with lower RIs. This suggests that cardiovascular surgery regional availability, as measured by RI, has an impact on mortality rates for certain complex surgical procedures. The RI was not associated with significant mortality differences for more widely available procedures like CABG (aOR, 0.96), PCI (aOR, 1.00), or stent insertion (aOR, 0.91). Conclusions: Significant regional variation and underutilization of cardiovascular surgery were found, with reduced access linked to worse mortality for complex procedures. Disparities should be addressed through collaboration among hospitals and policy efforts to improve outcomes.