• 한국가스학회지
• /
• 제11권4호
• /
• pp.35-40
• /
• 2007

본 연구는 마이크로핀관에서 이소부탄과 프로판의 증발 열전달 특성에 대해 실험적으로 조사하였다. 시험부는 외경 12.70 mm이고, 높이가 0.25 mm인 75개 핀이 원주방향으로 삽입되어 있다. 실험결과, 탄화수소계 냉매의 평균 열전달계수는 프레온계 냉매인 HCFC22보다 높을 것으로 나타났고, 높은 질랑유속에서는 이소부탄 > 프로판 순으로 나타났다. 마이크로핀관에서 증발 열전달 계수는 평활관에 비해 약 $80{\sim}100%$ 정도가 향상되었다. 이러한 본 연구 결과로부터 탄화수소계 냉매를 냉동 공조 시스템의 냉매로 사용하여 열교환장치를 설계할 경우에는 유리하리라 생각된다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
• /
• pp.1076-1079
• /
• 1993

A fuzzy digital controller is combined an autopilot system for compensating the cross coupling effect of the induced roll due to the dynamic characteristic of three fin torpedo. However the utilization of fuzzy chip has many interfacing problems with typical microprocessors of the guidance and control unit. Since a fuzzy digital controller on a microprocessor uses a finite word length A/D converters arul D/A converters, ADC and DAC may generate nonlinear effects such as deadband and limit cycle phenomena. In this paper, the robustness of fuzzy digital controller is tested with ADC a finite word length.

• 대한조선학회논문집
• /
• 제49권2호
• /
• pp.174-181
• /
• 2012

In this paper, the Flow Control Fin(FCF) optimization has been carried out using computational fluid dynamics(CFD) techniques. This study focused on evaluation for the performance of the FCF attached in the stern part of the ship. The main advantage of FCF is to enhance the resistance performance through the lift generation with a forward force component on the foil section, and the propulsive performance by the uniformity of velocity distribution on the propeller plane. This study intended to evaluate these functions and to find optimized FCF form for minimizing viscous resistance and equalizing wake distribution. Four parameters of FCF are used in the study, which were angle and position of FCF, longitudinal location, transverse location, and span length in the optimization process. KRISO 300K VLCC2(KVLCC2) was chosen for an example ship to demonstrate FCF for optimization. The optimization procedure utilized genetic algorithms (GAs), a gradient-based optimizer for the refinement of the solution, and Non-dominated Sorting GA-II(NSGA-II) for Multiobjective Optimization. The results showed that the optimized FCF could enhance the uniformity of wake distribution at the expense of viscous resistance.

• 디지털융복합연구
• /
• 제16권12호
• /
• pp.185-195
• /
• 2018

본 연구는 한국과 미국의의 핀테크 산업 고용창출효과를 비교분석하여 한국의 핀테크 산업의 발전을 모색하고자 한다. 분석에 사용된 산업연관표는 한국과 미국 모두 동일한 산업분류와 통화 단위로 구성된 WIOD를 이용하였다. 또한 분석을 위해 핀테크 산업을 ICT분야와 금융분야를 하나의 산업으로 구성 하였다. 뿐만 아니라 본 연구는 두 국가의 핀테크 산업 특성을 구분하기 위해 핀테크 산업 외에도 ICT분야와 금융분야의 고용창출효과도 함께 비교하였다. 분석결과, 한국은 핀테크 산업에 100만 달러의 투자 또는 생산이 이루어질 때 취업유발효과는 11.33명, 고용유발효과는 9.47명으로 총20.8명의 고용창출효과를 나타냈고 미국의 경우 취업유발효과는 8.07명, 고용유발효과는 7.72명으로 고용창출효과는 총15.79명으로 나타났으나 절대적인 비교에서는 한국이 더 높게 나타났다. 하지만 국가 산업 전체 평균 고용창출효과를 기준으로 분류한 결과 한국의 핀테크 산업은 고용유발효과가 높은 고용유발우위 산업으로 미국은 취업유발효과와 고용유발효과가 모두 높은 고용창출우위 산업으로 분류되었다.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.525-530
• /
• 2003

This paper is concerned with a control allocation strategy using the dynamic inversion which generates the nominal control input trajectories, and autopilot design using the time-varying control technique which is time-varying version of pole placement of linear time-invariant system for an agile missile with aerodynamic fin and thrust vectoring control. Dynamic inversion can decide the amount of the deflection of each control effector, aerodynamic fin and thrust vectoring control, to extract the maximum performance by combining the action of them. Time-varying control technique for autopilot design enhance the robustness of the tracking performance for a reference command. Nonlinear simulations demonstrates the dynamic inversion provides the effective nominal control input trajectories to achieve the angle of attack command, and time-varying control technique exhibits good robustness for a wide range of angle of attack.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제15권1호
• /
• pp.25-33
• /
• 2007

The investigation has been made into the prediction of heat exchange performance of a counter flow type double-tube condenser for natural refrigerant mixtures composed of Propane/n-Butane or Propane/i-Butane in a smooth tube and micro-fin tube. Under various heat transfer conditions, mass flux, pressure drop and heat transfer coefficient of the mixed refrigerants were calculated using a prediction method, when the length of condensing tube, total heat transfer rate, mass flux and outlet temperature of coolant were maintained constant. Also, the predicted results were compared with those of HCFC22. The results showed that the mixed refrigerants of Propane/n-Butane or Propane/i-Butane could be substituted for HCFC22, while the pressure drop and overall heat transfer coefficient of the refrigerants were evaluated together.

• 설비공학논문집
• /
• 제13권7호
• /
• pp.557-563
• /
• 2001

Small capacity gas absorption systems for cooling and heating have been favorably considered to reduce the seasonal imbalance of electrical loads and LNG consumption recently. A multifunctional plate-fin heat exchanger was adopted as an absorber and the performance was tested and analyzed to reduce the size and weight of the absorption heat pump. The test was performed using breadboard type ammonia absorption machine. The performance was compared with the plate type absorber and there was little difference in heat and mass transfer characteristics. The heat and mass transfer performance was a function of poor solution and vapor flow rates and the mass transfer was dependent on vapor flow rate more than heat transfer.

• Animal cells and systems
• /
• 제11권2호
• /
• pp.135-139
• /
• 2007

One specimen of the percophid fish, Pteropsaron evolans Jordan and Snyder and two specimens of the labrid fish, Xyrichtys verrens (Jordan and Evermann) were newly collected from Jeju Island of Korea. P. evolans is characterized by having one pair of spines at snout, cheek without scales, and elongated first dorsal fin in male. X. verrens is easily distinguished by having tip of pectoral fin black, many rows of scales on cheek, and an elongated pelvic fin. We describe as new to Korean fish fauna and propose new Korean names, "Sil-nun-tung-i" for the former and "Jang-mi-ok-du-nol-rae-gi" for the latter.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
• /
• pp.869-873
• /
• 1992

A fuzzy controller is designed for compensating the cross-coupling effect of induced roll due to the dynamic characteristics of three fin torpedo. Since the utilization of fuzzy-coprocessor has many interfacing problems with typical microprocessors of the guidance and control unit, the simplified fuzzy inference method based on nonfuzzy-processor is proposed to implement fuzzy controllers of three fin torpedo. This method provides a flexible rule-base design to guarantee the robust control. The good potential of the proposed design is shown through real-time simulations using both a mathematical model on AD-100 computer and an implemented controller on Intel 80C186/80C 187 microprocessors employing 12bit A/D converter.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.1067-1072
• /
• 2009

In vapor compression systems which use refrigerant as a working fluid, the oil is commonly used for compressor lubrication. Since the presence of lubrication oil can change the characteristics properties of refrigerant, the oil affects the heat transfer performance of heat exchanger to a large extent. In this paper, we focus on the effect of PVE oil experimentally on heat transfer performance of the fin-tube heat exchangers which use R410A as a refrigerant. To evaluate the heat transfer performance, the refrigerant to air type test facility chamber has been used. Fin-tube heat exchanger with grooved has been tested while according to the oil mass fraction variation from nearly zero to 1.7 wt%. It was found that the low level of oil mass fraction has an obvious effect on heat transfer performance, while the high level seems no significant influence. The influence of the oil mass fraction to heat transfer performance, however, is different between evaporation and condensation.