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안정수,양선규,천세영,정문기,최영돈,An, Jeongsoo,Yang, Sunkyu,Chun, Seyoung,Chung, Moonki,Choi, Youngdon 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.5
This paper presents Raman scattering of liquid water to obtain the characteristics with variation of temperature. Very clear Stokes-Raman signals were observed, which shows H-O vibration stretching and H-O-H vibration bending. The obtained spectrum were processed by FFT filter to extract the noise and base. The spectral shape of the H-O stretching provided a various sensitive signature which allowed temperature to be determined by a curve-fitting technique. Those are Maximum Intensity, Maximum Wave Length, FWHM(Full Width at Half Maximum), PMCR(Polymer Monomer Concentration Ratio) and TSIR(Temperature Sensitive Intensity Ratio). TSIR method shows the highest accuracy of $0.1^{\circ}C$ in mean error and $0.32^{\circ}C$ In maximum error.
Stoichiometry 변화에 따른 PEMFC내에서의 플러딩에 관한 실험적 연구
한성호(Han SeongHo),김경록(Kim KyoungRock),최영돈(Choi YoungDon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
This is the experimental research that tries to explain a variety of stoichiometry is how to affect the performance and the flooding phenomenon of proton exchange membrane fuel cell. A value of stoichiometry changes to 1.2, 2.0 and 2.5 as its variation, either a temperature of cell changes to 50, 60 and 70. Into the comparison between theoretical and experimental value, this study analyzes that a variety of stoichiometry is how to affect flooding of cathode in the proton exchange membrane fuel cell. The effect of air stoichiometry, cell temperature, air humidity, different flow fields are also discussed in this paper. This study has accomplished the measurement of performance as the variety of stoichiometry in the cathode of proton exchange membrane fuel cell, moreover it has recorded the visualization of flooding in the cathode with a high-speed micro camera.
고준영(Junyoung Ko),김지수(Jisu Kim),최영돈(Youngdon Choi),박현국(H. K. Park),정성욱(Seong-ook Jung) 대한전자공학회 2015 대한전자공학회 학술대회 Vol.2015 No.6
The voltage biasing circuit is widely used in many application such as sensor, analog circuit, and memory circuit. However, the supply voltage noise can cause an error between the voltage biasing circuit block and a target block of biasing voltage. Especially, in the PRAM, the effect of supply voltage noise on sensing circuit has been increased. This research proposed the supply voltage noise tolerant voltage biasing (SVNTVB) scheme to alleviate the effect of supply voltage noise on the sensing circuit of PRAM. The proposed SVNTVB achieves under 5mV of VSG mismatch when the supply voltage noise is 30mV.
연료전지 분리판의 리브 높이 변화에 따른 응답성 변화에 관한 실험적 연구
윤성호(Sungho Yun),최남현(Namhyeon Choi),남기훈(Kihoon Nam),이장일(Jangil Lee),최영돈(Youngdon Choi) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
In the present study, using a variation of rib height, the transient response and the performance are investigated. The cell voltage is acquired according to the current density change(0.8A/cm2 to 1.0A/cm2) under same stoichiometry and relative humidity. The different level of undershoots appeared at the different clamping pressure(1.5MPa and 2.0MPa) and different rib height. At 1.5MPa clamping pressure, rib manufactured cutting 100μm height goes to steady state faster than reference plate and has lower maximum undershoot voltage. But performance is lower than reference plate due to increasing contact resistance.
한성호(WonKap.Kim),김원갑(SeongHo.Han),최영돈(YoungDon.Choi) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
This paper reports the characteristics of the three dimensional turbulent flow in the rectangular<br/> -sectioned 180 degree bends by Hot-wire anemometer. Grande and Kool proposed a cooling law for the<br/> measurements of the flow through the narrow passage. The authors noticed that the calibration<br/> coefficients of original method are not constant and fairly sensitive to the flow approaching angle.<br/> Measured voltages are converted to three velocity and six Reynolds stress components using the<br/> modified method in which the coefficients are treated as a function of approaching angle.
외기온도 변화에 따른 집단에너지 다중 열공급 최적제어 알고리즘 개발에 관한 수치해석적 연구
변재기(Jaeki Byun),최남현(Namhyeon Choi),남기훈(Kihoon Nam),최영돈(Youngdon Choi),신종근(Jongkeun Shin) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
In the present study, we developed optimal heat supply algorithm which minimize the heat loss through the distribution pipe line in group energy apartment. Heating load variation of group energy apartment building in accordance with outdoor air temperature was predicted by the correlation obtained from calorimeter measurements of whole households of apartment building. Supply water temperature and mass flow rate were conjugately controlled to minimize the heat loss rate through distribution pipe line. Group heating apartment located in Hwaseong city, Korea, which has 1,473 households devided in 4 regions, was selected as the object apartment for verifing the present heat supply control algorithm. Compared to the original heat supply system, 10.4% heat loss rate reduction can be accomplished by employing the present control algorithm.
상대습도 변화에 따른 PEM Fuel Cell 내에서의 플러딩에 관한 실험적 연구
김경록(Kim KyoungRock),한성호(Han SeongHo),안득균(Ahn DeukKuen),최영돈(Choi YoungDon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
This is the experimental research that tries to explain a variety of RH is how to affect the cell performance and the flooding phenomenon of proton exchange membrane fuel cell (PEMFC). A value of RH changes to 0%, 50% and 90% as its variation, either stoichiometric flow rate changes to 1.5, 2 and 4. Into the comparison between theoretical and experimental value, this study analyzes that a variety of RH is how to affect flooding in the cathode of the proton exchange membrane fuel cell. The effect of air stoichiometry, air humidity and different flow fields are also discussed in this paper. This study has accomplished the measurement of performance as the variety of RH in the cathode of proton exchange membrane fuel cell, moreover it has recorded the visualization of flooding in the cathode with a high-speed micro camera.
루버 핀 열교환기를 가지는 자동차용 히트펌프 시스템의 착상 특성 연구
임홍영(Hong Young Lim),송준영(Junyoung Song),신성홍(Sunghong Shin),김학규(Hakkyu Kim),오광헌(Kwanghun Oh),최영돈(Youngdon Choi) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
The present study investigated the heating performance and frosting phenomenon of the heat pump system for vehicle, which is being developed to increase fuel efficiency of EV(Electric Vehicle) with maintaining thermal comfort. The experimental setup of a heat pump system consists of an electric compressor, an exterior louvered fin-flat tube condenser, an interior condenser, and an evaporator, block type thermal expansion valve and reservoir tank, which are used in actual HVAC system for vehicle. In this study, frosting phenomenon patterns of outside condenser having uniform air flow rate was visualized and heat pump performance is examined experimentally. In addition, the frosting phenomenon is compared with different compressor rpm. As results, non-uniform frosting phenomenon and non-frosting area in exterior condenser was occurred. The heating performance based on air side of interior condenser outlet was maximized within 4min. The heating performance was reduced 5.3% after 27min and 42% after 90min because of frosting in exterior condenser.