• 대한의용생체공학회:학술대회논문집
• /
• 대한의용생체공학회 1996년도 춘계학술대회
• /
• pp.207-212
• /
• 1996

We developed pneumatic blood pump and its driving system as a pediatric ventricular assist device. The blood pump is diaphragm type system and its blood contacting area is coated with Bio-Span. The driving unit Is consists of dual pumps, valves for the reliable blood pumping and its controller uses 80C196(Intel) as a main processor. The acute animal experiment was performed with dogs and its body weight is about 20 kg. The maximum cardiac output is about 2.1 l/min and the pressure and flow curves showed reliable operation as assist device.

• 대한설비공학회지:설비저널
• /
• 제14권1호
• /
• pp.21-30
• /
• 1985

One of the problems with the Boiling Water Reactor involves the flow and thermal mixings in the suppression water pool high pressure steam discharge into the pool in case of emergency core relief. Varioos heat sensitive devices and pumps for the reactor core cooling are installed in the middle of the suppression pool. Especially the pumps utilize pool water in order to cool the reactor core in emergency cases. In this case, the water temperature for the reactor cool ins should be below a certain temperature specified by the reactor design. In the present investigation, in other to determine the optimum locations of these pumping devices, numerical solutions have been obtained for the model to determine the f low mixing characteristics. Experimental investigations have also been carried out for the flow mixing and for the thermal mixing in the pool during the discharge. Considering that the discharge steam through the Quenching Device becomes hot water immediately in the water pool, the steam- equivalent hot water has been utilized. Examining these characteristices, it becomes possible to deform me the best locations for RCIC, LPCI , HPCI pumps in the suppression water pool for the emermency reactor core cooling.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
• /
• pp.327-330
• /
• 2004

It is shown that the hot carrier degradation due to enhanced hot holes trapping dominates PMOSFETs lifetime both in thin and thick devices. Moreover, it is found that in 0.13 ${\mu}m$ CMOSFET the PMOS lifetime under CHC (Channel Hot Carrier) stress is lower than the NMOSFET lifetime under DAHC (Drain Avalanche Hot Carrier) stress. Therefore. the interface trap generation due to enhanced hot hole injection will become a dominant degradation factor. In case of thick MOSFET, the degradation by hot carrier is confirmed using charge pumping current method and highly necessary to enhance overall device lifetime or circuit lifetime in upcoming nano-scale CMOS technology.

• 대한기계학회논문집B
• /
• 제27권9호
• /
• pp.1256-1261
• /
• 2003

Since the viscous effect increases as the size of device decreases, viscous-driven micropump is a promising mechanism in microscale applications. In the present study, a dual-rotor type pump which contains two counter-rotating cylinders for improving performance characteristics is proposed. First, for flows in the single-rotor type pump, the present unstructured grid simulation method is validated by comparing its results to the previous results. Next, the performance of the dual-rotor type pump is evaluated by the parametric studies and is compared to that of the previous single-rotor type pump. The flow characteristics are qualitatively similar to those of single-rotor type pump. However, the performance of the micropump with tandem rotors is still better than that of previous pumping type, e.g. much larger flow rate, smaller driving region, higher efficiency, and wider operation range.

• Journal of Chest Surgery
• /
• 제22권2호
• /
• pp.202-211
• /
• 1989

We experienced a series of animal experimental studies of the total artificial heart in 1988. So called, "Korean Heart* was used in this study, which is developed and fabricated in the Department of Biomedical Engineering, College of Med., S.N.U.. "Korean Heart" is a Rolling-Cylinder Motor-Driven type which is a newly developed electromechanical heart over the shortcomes of the previous artificial hearts, especially pneumatic type. The advantages of the "Korean Heart" are total implantability, quiet and smooth movement, small size fittable in oriental people, etc. The animal experiments were performed two times, as an assist device in sheep and total artificial heart implant experiment in calf weighing 100 kg. After total implantation, the artificial heart was well functioned in movement and hemodynamic control. So that, the calf was recovered excellently, which was able to stand up by herself and take an oral intake. Total survival time was 100 hours and the cause of death was a sudden pumping failure [electrical connection problem]. Several postoperative laboratory results almost within normal limits and no hemolysis, but in autopsy, the multiple thromboembolic findings were seen at the lung and kidney.n at the lung and kidney.

• Current Optics and Photonics
• /
• 제1권2호
• /
• pp.113-117
• /
• 2017

With the increasing use of high-power laser diode bars (LDBs) and stacked LDBs, the issue of thermal control has become critical, as temperature is related to device efficiency and lifetime, as well as to beam quality. To improve the thermal resistance of an LDB set, we propose and analyze a bypass heat sink with a top canopy structure for an LDB set, instead of adopting a thick submount. The thermal bypassing in the top-canopy structure is efficient, as it avoids the cross-sectional thermal saturation that may exist in a thick submount. The efficient thickness range of the submount in a typical LDB set is guided by the thermal resistance as a function of thickness, and the simulated bypassing efficiency of a canopy is higher than a simple analytical prediction, especially for thinner canopies.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2010년도 제35회 추계학술대회논문집
• /
• pp.618-619
• /
• 2010

움직이는 부품 없이 오직 온도구배만으로 추진제를 낮은 온도에서 높은 온도로 자체 펌핑이 가능한 열적발산장치를 설계 제작하였으며, 진공환경에서 누센수에 따른 멤브레인 압력구배 효율을 분석하였다. 본 논문에서는 한지 멤브레인을 사용하여 누센펌프의 펌핑 효율을 분석하였다.

• 한국광학회지
• /
• 제17권5호
• /
• pp.455-460
• /
• 2006

광섬유 연결 반도체레이저를 여기원으로 하는 단면여기 세라믹 Nd:YAG 레이저의 출력 특성과 레이저 출력에 영향을 미치는 열 영향에 대하여 연구하였다. 반사율이 90.4 %인 출력거울을 사용하였을 경우 약 33.8 %의 최대 출력 효율을 얻었고, 기울기 효율은 39.3 %를 나타내었다. 세라믹 Nd:YAG의 열렌즈 효과에 의해 여기 파워 6 W 이상에서 출력 감소 현상이 나타났으며, 12 W 부근에서 레이저가 발진되지 않았다.

• 한국진공학회지
• /
• 제16권5호
• /
• pp.371-376
• /
• 2007

분자선 에피택시(molecular beam epitaxy, MBE)로 성장된 InGaAs 양자점 레이저 다이오드(quantum dot laser diode, QD-LD)와 InGaAs 양자우물 레이저 다이오드(quantum well laser diode, QW-LD)의 특성을 비교하였다. 펄스 입력전류 하에서 문턱전류밀도(threshold current density, $J_{th}$), 특성온도(characteristic temperature, $T_0$), 온도에 따른 발진파장의 변화도($d{\lambda}/dT$)를 측정한 결과, 양자우물 레이저 다이오드는 $J_{th}\;=\;322\;A/cm^2,\;T_0\;=\;55.2\;K,\;d{\lambda}/dT\;=\;0.41\;nm/^{\circ}C$로 측정되었으며, 양자점 레이저 다이오드는 $J_{th}\;=\;116\;A/cm^2,\;T_0\;=\;81.8\;K,\;d{\lambda}/dT\;=\;0.33\;nm/^{\circ}C$로 측정되었다. 양자점 레이저 다이오드는 양자우물 레이저 다이오드와 비교하였을 때, 문턱전류밀도 및 발진 광 파워가 상대적으로 우수한 결과를 보여주었다.

• 한국자동차공학회논문집
• /
• 제19권2호
• /
• pp.26-34
• /
• 2011

Hybrid powertrain systems have been developed to improve the fuel efficiency of internal combustion engines. In the case of a parallel hybrid powertrain system, an engine and a motor are directly coupled. Because of the hardware configuration of the parallel hybrid system, friction and the pumping losses of internal combustion engines always exists. Such losses are the primary factors that result in the deterioration of fuel efficiency in the parallel-type hybrid powertrain system. In particular, the engine operates as a power consumption device during the fuel-cut condition. In order to improve the fuel efficiency for the parallel-type hybrid system, cylinder deactivation (CDA) technology was developed. Cylinder deactivation technology can improve fuel efficiency by reducing pumping losses during the fuel-cut driving condition. In a CDA engine, there are two operating modes: a CDA mode and an SI mode according to the vehicle operating condition. However, during the mode change from CDA to SI, a serious fluctuation of the air-fuel ratio can occur without adequate control. In this study, an air-fuel ratio control algorithm during the mode transition from CDA to SI was proposed. The control algorithm was developed based on the mean value CDA engine model. Finally, the performance of the control algorithm was validated by various engine experiments.