• 한국자동차공학회논문집
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• 제19권6호
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• pp.10-16
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• 2011

Diesel particulate filter is being recognized that it is the most effective technologies to reduce particulate matter. In this study, to determine the characteristics of the cell-open-type pDPF, we employed p-DPF to exhaust gas tunnel of diesel engine and surveyed filtration efficiency and BPT on the basis of PM which is exhausted from engine. In this paper the soot loading mass in DPF can be predicted from increase of differential pressure of DPF so that we can measure filtration efficiency and Balance Point Temperature (BPT) by soot loading mass. The result of the research showed that the filtration efficiency is 65% in ESC mode with 0.7mm hole diameter. For the results of the characteristics of filtration efficiency and BPT according to mass_exh, we found that if mass_exh increases, filtration efficiency increases and BPT decreases.

• 대한기계학회논문집B
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• 제32권10호
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• pp.769-775
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• 2008

In this study, the investigations on the dimpled type Exhaust Gas Recirculation (EGR) cooler have been focused on the high heat exchanger efficiency. To overcome low heat exchanger efficiency of general EGR cooler, the dimpled type EGR cooler was developed. It was ensured the improvement of the performance of the dimpled type EGR cooler related to the heat exchange based on a series of the experiment. These results were caused by the increase of thermal surface area in accordance with the dimple's one. The estimation model of the heat exchanger efficiency using the Effectiveness-NTU method was also developed in order to verify the validity of experimental result. Also, the program for the estimation of the heat exchanger efficiency on the EGR cooler with regard to the dimpled tube shape was developed. Resultantly, it was confirmed that the dimpled type EGR cooler could be served better performance than the conventional one in view of the heat exchanger efficiency.

• 대한기계학회논문집
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• 제12권5호
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• pp.968-975
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• 1988

본 연구에서는 직선보간과 원호보간에서 계산효율을 향상시킬 수 있는 방법을 제시하여 이 방법과 가감속 구간을 고려한 하드웨어 보간기를 설계 및 제작하였고, 이 것을 스텝 모터에 의해 구동되는 밀링머시인에 연결하여 보간기의 성능을 알아보았다.

• 드라이브 ㆍ 컨트롤
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• 제16권2호
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• pp.15-21
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• 2019

In this study, the maximum system efficiency of the electro-hydrostatic actuators was experimentally investigated, where small size external gear pumps with volumetric displacement under 1.3 cc/rev were combined with a 400W servomotor as the prime mover. Since the efficiency data of the servomotor, gear pumps and hydraulic cylinder were not provided by the suppliers, experimental apparatuses for their efficiency measurement were extra built up. When a gear pump with a volumetric displacement of 1.27cc/rev was used on an electro-hydrostatic actuator system, the maximum system efficiency was not higher than 70%. This was because the most effective operation ranges of the motor and pump did not coincide each other. In order to match their operation ranges as one of the most crucial design factors, a speed reduction mechanism can be used, such as a timing belt. It was shown in the study that the maximum system efficiency could be increased from 70% to 76% in that way.

• 대한기계학회논문집B
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• 제40권6호
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• pp.409-415
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• 2016

본 연구에서는 유량 $70.7m^3/min$, 양정 87m의 양흡입 원심펌프의 수력 손실 절감을 위해 표면 마찰거칠기를 변화시킨 실험을 수행하였다. 초기 표면 거칠기를 $100{\sim}110{\mu}m$에서 $0{\sim}0.08{\mu}m$로 변경한 후 표면 거칠기 변화가 전체 펌프의 효율 증가 및 펌프 운전시 소요되는 전력 원단위 변화 측정을 수행하였다. 표면 마찰 거칠기 개선 부위는 물과 접하는 펌프 내부 임펠러와 케이싱 표면으로 하였고 코팅 방식을 적용하였다. 그 결과 펌프 효율은 약 0.8~1.79% 증가하였으며, 전력원단위는 4.38 ~ 6.04% 절감 효과를 가져 왔다. 이와 같은 결과는 임펠러 및 내부 케이싱의 표면 거칠기가 펌프의 성능에 작지 않은 영향을 미칠 뿐만 아니라 표면 거칠기 개선을 통해 마찰에 의한 수력 손실을 줄여서 펌프 성능 향상과 상당한 에너지의 절감 효과를 얻을 수 있음을 확인하였다.

• 한국수소및신에너지학회논문집
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• 제29권1호
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• pp.11-18
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• 2018

A high efficiency integrated reforming system for improving the efficiency of the 5 kW PEMFC system used as the back up power of building was studied. The separated reforming system consisted of three parts - A steam reformer with two stage concentric circular shape, a heat exchanger type steam generator and a CO shift reactor. Temperature and steam carbon ratio (SCR) were control variables during operation. The operating conditions were optimized based on the thermal efficiency of the steam reformer as reformate gas composition changes at different temperature. In experiments, water was fully vaporized in the steam generator up to SCR 3.5 and the maximum thermal efficiency was achieved at the operating temperature around $700^{\circ}C$ in the steam reforming reactor. With the results of the separated reforming system research, we improved the shape of high efficiency integrated reformer. The performance evaluation of the integrated reformer was based on optimized operating conditions in SCR 3.5. As a result, the developed integrated reforming system maintained an efficiency of 76% and constant performance over 3,000 hours.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.115-122
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• 2019

In order to improve the current efficiency and reduce the energy consumption in the electrosynthesis of ammonium persulfate, electrolytic properties of a perfluorosulfonic cation exchange membrane named PGN membrane and the $Al_2O_3$ ceramic membrane in the electrosynthesis of ammonium persulfate were studied and compared in a pilot electrolytic cell using a welded platinum titanium as the anode and a Pb-Sb alloy as the cathode. The effect of cell voltage, electrolyte flow rate and electrolysis time of the electrolytes on the current efficiency and the energy consumption were studied. The results indicated that the PGN membrane could improve current efficiency to 95.12% and reduce energy consumption to $1110kWh\;t^{-1}$ (energy consumption per ton of the ammonium persulfate generated) under the optimal operating conditions and the highest current efficiency of the $Al_2O_3$ ceramic membrane was 72.61% with its lowest energy consumption of $1779kWh\;t^{-1}$. Among 5 times of the electrolysis of the electrolytes, the lowest current efficiency of the PGN membrane was 85.25% with the highest energy consumption of $1244kWh\;t^{-1}$ while the lowest current efficiency of the $Al_2O_3$ ceramic membrane was 67.44% with the highest energy consumption of $1915kWh\;t^{-1}$, which suggested the PGN membrane could be used in the 5-stage electrolytic cell for the industrially continuous electrosynthesis of ammonium persulfate. Therefore the PGN membrane can be efficient to improve the current efficiency and reduce the energy consumption and can be applied in the industrial electrosynthesis of ammonium persulfate.

• 대한기계학회논문집B
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• 제39권3호
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• pp.261-269
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• 2015

본 연구에서는 전산유체역학 상용 코드를 이용하여 곡유로 채널형 수소 개질기에 대한 수치 해석적 연구를 수행하였다. 상용코드에서 제공하는 연소모델의 사전 검증을 위하여 원통 채널형 개질기 형를 가지는 선행연구모델(23)에 대한 수치해석을 선행하여 수행하였고, 95% 이상 일치하는 결과를 얻을 수 있었다. 선행연구모델의 수치해석을 통해 연소모델에 대한 해석 타당성검증이 완료된 후, 반응기 형태 변화가 메탄올 전환율과 수소생성에 미치는 영향을 파악하여 기존보다 유로의 길이가 증가한 곡유로 채널형 개질기를 설계하고, 유량조건($10/15/20{\mu}l/min$)을 변수로 수치해석을 수행하였다. 그 결과 원통 채널형 개질기와 곡유로 채널형 개질기에서 발생하는 유동 특성 및 물질전달 특성을 파악할 수 있었고, 그리고 유량에 따른 메탄올 전환율 및 수소 생성에 관한 유용한 정보를 얻을 수 있었다.

• 대한기계학회논문집B
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• 제35권4호
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• pp.399-407
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• 2011

고체산화물 연료전지(SOFC)와 가스터빈을 결합한 하이브리드 발전시스템에서 가스터빈의 규모별 성능차이가 시스템의 성능에 미치는 영향에 대하여 해석하였다. 이를 위해 kW급, MW 이하급, 수 MW급 등 서로 다른 세 가지 가스터빈을 선정하여 사용하였다. 가스터빈이 순 출력을 거의 내지 못하는 kW급 시스템에서도 연료전지 단독 시스템과 비교해 효율이 증가하였으며, 가스터빈의 출력이 커질수록 (즉, 성능이 좋아질수록) 하이브리드 시스템에서 가스터빈이 차지하는 비중이 커지고 시스템의 효율이 높아짐을 확인하였다. 가스터빈의 압력비 증가에 따른 성능 변화를 살펴본 결과 세 가지 하이브리드 시스템에서 모두 출력은 증가하지만, 효율의 변화는 크지 않음을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.644-649
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• 2000

A new cyclone system for the vacuum cleaner to collect dusts has been studied experimentally and numerically to meet the constant suction power, hygienic exhaust and a reduction of maintenance cost. The cyclone system of the vacuum cleaner consists of twin cyclones for improving dust collection efficiency. The first. cyclone catches large dust particles and the second one having two separated flows to decrease pressure drop collects small dust particles. The optimal design factors such as dust collection efficiency, pressure drop, and cut-size are investigated from the experimental results by the Taguchi method. Cyclone cleaner systems designed in this study has a good Performance taking into account the dust collection efficiency of 93% and the cut-size of $1.6{\mu}m$ in mass median diameter at the flow rate of 1 CMM. The cyclone vacuum cleaner showed the potential to be an effective method to collect dusts generated in the household.