• Journal of Chest Surgery
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• 제19권2호
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• pp.273-279
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• 1986

Total anomalous pulmonary venous return is a cardiac malformation in which there is no direct connection between any pulmonary vein and the left atrium but, rather all the pulmonary veins connect to the right atrium or one of its tributaries. TAPVC is a relatively uncommon anomaly, accounting for only about 1.5-3% of cases of congenital heart disease. Recently improvement in intraoperative techniques did eventually bring substantial improvements in the results in infants. 4 cases of TAPVC was successfully treated with one-stage operation, in the Dept. of Thoracic and Cardiovascular Surgery, National Medical Center in which 2 cases are supracardiac types and the other 2 cases are cardiac types. Sex ratio was 1:1, and the range of age was 2 years-18 years. The common pulmonary venous sinus was connected to the left vertical vein and innominate vein: in 2 supracardiac types and coronary sinus in 2 cardiac types. All cases are operated with standard cardiopulmonary bypass, and the hospital mortality was 0%.

• 한국유체기계학회 논문집
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• 제14권1호
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• pp.61-65
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• 2011

A series of water tests of a fuel pump for liquid rocket engines are performed at a room temperature. According to the test results, the head coefficient of the pump follows the conventional similarity rule - unlike this, the pump shows better efficiency with higher rotational speed. Also, it is found that the pressure at the rear bearing outlet is higher than expected because the inlet of bypass pipe line is narrow. Furthermore, the cavitation performance of the fuel pump is found to be sufficient for the engine operation and is better at the lower flow ratio and higher rotational speed.

• 한국전산유체공학회지
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• 제2권2호
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• pp.51-58
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• 1997

A reliable computational solver has been developed for the analysis of three-dimensional inviscid compressible flows around a nacelle of a high bypass ratio turbofan engine, The numerical algorithm is based on the modified Godunov scheme to allow the second order accuracy for space variables, while keeping the monotone features. Two step time integration is used not only to remove time step limitation but also to provide the second order accuracy in a time variable. The multi-block approach is employed to calculate the complex flow field, using an algebraic, conformal, and elliptic method. The exact solution of Riemann problem is used to define boundary conditions. The accuracy of the developed solver is validated by comparing its results around the isolated nacelle in the cruise flight regime with the solution obtained using a commercial code "RAMPANT. "

• Journal of Chest Surgery
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• 제12권2호
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• pp.105-109
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• 1979

Since 1973, 40 patients with Patent Ductus Arteriosus were operated in The Department of Thoracic and Cardiovascular Surgery, Korea University Medical College. Clinical analysis of these cases: 1. Age ranged from 8 months old to 28 years old Sex ratio was 22 females to 18 males. 2. Pulse pressure widening above 50 mmHg was appeared in 27 patients. In 31 patients, continuous machinery murmur was heard on left second and third intercostal space, but 9 patients has holosystolic murmur on left sternal border. 3. Retrograde Aortography was performed in 11 patients and right heart catheterization, 17 patients, In 8 patients, pulmonary hypertension [above 30 mmHg in` systole] was noted. 3 out of 8 patients was combined with Ventricular Septal Defect. Severe pulmonary hypertension [above 80mmHg in systole] was presented in 3 patients. 4. In 38 patients, operative method was performed with multiple suture ligation of PDA, and in 2 patients, suture closure through pulmonary arteriotomy under cardiopulmonary bypass. 5. One operative death occurred in a patient in this group. Cause of death was right heart failure after multiple suture ligation of PDA and pulmonary artery bandings.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.258-263
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• 2000

River water is higher in temperature than the surrounding environment during the winter. It is highly suitable a heat source for heat pump system. Despite its suitability, however, it is not widely used, due to its fouling and corrosive nature in heat exchanger tubes of evaporator. It is designed prior-treatment system which come into direct contact with the river water, such as auto-seamer, ozone generator for bactericidal test and auto-cleaning system. And it is analyzed treatment effects for its operation. It is designed two-stage compression heat pump system using R-134a with heating load 35.16kW, ad analyzed its performance. As a result it is obtained 3.08 COP when mid-point pressure is 1,200kPa, and bypass ratio of flowing refreigerant to high-stage compressor is 25.1%

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2004년도 제22회 춘계학술대회논문집
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• pp.779-783
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• 2004

First this paper introduces an advanced FADEC (Full Authority Digital Electric Control) for current and future jet engines.It is designed to realize not only stable thrust control, but also performance improvement, reliability enhancement, service life extension, etc. It can be built by using current micro-processor with high computational power and there exists no difficulties but reliability problem of the micro- processor. Next, the simulation results of SFC minimization control are shown. The target engine is a supersonic, low-bypass ratio, 2-spool, combined cycle turbofan, designated as HYPR90T, which consists of a turbo engine for under Mach 3 flight and a ram engine for over Mach 3 flight. he results can then be used for performance optimization of the engine, which plays important role in the advanced FADEC.

• Earthquakes and Structures
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• 제5권1호
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• pp.1-22
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• 2013

Soft storey failure mechanism is a common collapse mode for masonry-infilled (MI) reinforced concrete (RC) buildings subjected to severe earthquakes. Simple analytical equations correlating global with local ductility demands are derived from pushover (PO) analyses for seismic assessments of regular MI RC frames, considering the critical interstorey drift ratio, number of storeys and lateral loading configurations. The reliability of the equations is investigated using incremental dynamic analyses for MI RC frames of up to 7 storeys. Using the analytical ductility relationship and a coefficient-based method (CBM), the response spectral accelerations and period shift factors of low-rise MI RC frames are computed. The results are verified through published shake table test results. In general applications, the analytical ductility relationships thus derived can be used to bypass the onerous PO analysis while accurately predicting the local ductility demands for seismic assessment of regular MI RC frames.

• 항공우주시스템공학회지
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• 제17권5호
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• pp.11-18
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• 2023

The architecture of the Fuel Thermal Management System (FTMS) in a commercial aircraft engine was built to model and simulate the fuel system. The study shows the thermal interactions between the fuel and engine lubrication oil through the mission profile of a high bypass ratio, two-spool turbofan engine. Fuel temperature was monitored as it flowed through each sub-component of the fuel system during the mission. The heat load in the fuel system strongly depended on the fuel flow rate, and was significantly increased for the periods of cruise and descent with decrease of fuel flow rate, rather than for the periods of take-off. Due to the thermal interaction in the pump housing, the fuel temperature at the outlet of the low-pressure pump was increased (4.0, 9.2, and 30.0) % over the case without thermal interaction for take-off, cruise, and descent, respectively.

• 한국항공우주학회지
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• 제43권4호
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• pp.326-333
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• 2015

최적화 프로그램과 연동시키기 위한 터보팬 엔진 성능해석 프로그램을 개발하고, 최적화 기법인 Particle Swarm Optimization을 이용하여 전투기 엔진의 주요 설계변수인 바이패스비, 팬 압축비, 고압압축기 압축비 및 버너출구온도에 대한 성능 최적화를 수행하였다. 최적화 목표는 순추력과 비연료소모율을 다목표 함수로 설정하였으며, 두 개의 목표에 대해 가중치를 주어 각 가중치별 최적 설계점을 도출하였다. 기본 모델은 F-18 전투기와 T-50 고등훈련기에 쓰이고 있는 F404 터보팬 엔진을 선정하여 분석을 수행하였다. 본 연구 결과로 네 개의 변수에 대한 최적 조건을 도출하고, 다양한 설계조건에 대한 최적 설계점 추이를 분석하였다.

• 자원리싸이클링
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• 제30권1호
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• pp.35-43
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• 2021

본 연구에서는 제철 및 시멘트 제조공정에서 발생하는 부산물을 재활용하기 위한 기초 연구로 시약급 Na2SO4와 KCl을 사용하여 K2SO4를 제조하였다. K2SO4 제조 시 최적조건을 도출하기 위해 Na2SO4와 KCl의 몰 비율, 용액의 포화도 및 교반 온도를 제어하였으며, 주사전자현미경, X-선 회절분석기 등을 사용하여 수득시료의 미세구조 관찰 및 결정성을 분석·평가하였다. 순수 K2SO4를 수득할 수 있는 구간은 Na2SO4와 KCl의 몰 비율 1:6-18, 용액의 포화도 160% 이하, 교반 온도 20℃, 50℃이었다. 또한 K2SO4의 높은 결정성 확보 및 최종 수득량 증대, 에너지 소모 최소화를 고려한 최적 조건은 Na2SO4와 KCl의 몰 비율 1:6, 용액의 포화도 140%, 교반 온도 20℃이었다.