• Journal of Advanced Marine Engineering and Technology
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• 제37권8호
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• pp.816-821
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• 2013

본 논문은 자연대류 상에서 수동적으로 냉각되는 다양한 하이브리드 휜들과 핀 휜의 열성능에 대한 수치연구결과를 보고한다. 연구된 하이브리드 휜들은 basic hybrid fin (BHF), hollow hybrid fin (HHF), solid hybrid fin (SHF) 이다. 다양한 방열율에 대한 HF들과 PF의 열성능을 조사하기 위해 CFD 휜 모델이 개발되었다. 휜들의 열성능은 각각의 휜에 대해 휜 베이스 면적에 대한 열전달계수, $h_a$와 질량에 대한 열전달계수, $h_m$ 을 정량화하여 분석되었다. 연구결과는 SHF의 $h_a$가 PF 보다 23% 더 큼을 보여주고, HHF의 $h_m$은 PF 보다 무려 140% 더 크며, HHF의 질량기반 성능, 즉 $h_m$은 BHF 보다 40% 더 우수함이 밝혀졌다.

• Journal of Advanced Marine Engineering and Technology
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• 제37권1호
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• pp.35-39
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• 2013

본 논문은 자연대류상에서 냉각되는 하이브리드 휜 히트싱크(Hybrid Fin Heat Sink, HFH)의 열특성에 대한 수치연구결과를 보고한다. HFH는 평판휜이 결합된 내부유로가 있는 핀 휜으로 이루어진 하이브리드 휜으로 구성된다. HFH의 열성능은 상용 CFD 소프트웨어를 이용하여 수치적으로 연구되었고 핀 휜 히트싱크(Pin Fin Heat Sink, PFH)의 열성능과 비교되었다. 수치연구결과를 통해 HFH의 베이스면적기반, 질량기반 열전달계수가 PFH 보다 각각 12%, 37% 우수함을 발견했다. 증대된 표면적과 가벼운 무게는 PFH보다 우수한 HFH의 열성능을 설명할 수 있다.

• Journal of Advanced Marine Engineering and Technology
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• 제39권6호
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• pp.586-591
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• 2015

본 연구는 자연대류상의 LED 모듈의 경량열관리를 위한 하이브리드 휜 히트싱크(HF HS)의 열성능을 수치적으로 조사한 결과에 대해 논하였다. 할로우 하이브리드 휜 히트싱크(HHF HS)와 솔리드 하이브리드 휜 히트싱크(SHF HS)가 HF HS로 제안되고, 신뢰성있는 수치결과를 획득하기 위하여 3차원 CFD 해석이 수행되었다. 3차원 CFD 연구는 HHF HS와 SHF HS의 성능에 대한 휜 공간과 내부유로직경의 영향을 조사하였다. 연구결과는 HHF HS의 질량기반 열저항이 핀휜 히트싱크(PF HS) 보다 20~32% 작음을 보여주고, 유로직경의 증가에 따라 HHF HS의 질량기반 열저항이 감소함을 보인다. 이 결과는 주로 질량감소와 내부유로를 통한 열방출의 결합효과에 기인한다. 고전적인 PF HS 대비 상당히 우월한 HHF HS의 질량기반 열성능은 자연대류상의 LED 모듈의 경량열관리 적용 가능성을 제시한다.

• 한국수산과학회지
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• 제53권4호
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• pp.572-576
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• 2020

As grouper aquaculture production intensifies worldwide, hybrids are increasingly produced to induce heterosis of traits such as rapid growth and strong environmental adaptability. In this study, we compared the morphological characteristics of a hybrid grouper to those of its parent species Epinephelus moara and E. lanceolatus. The coefficients of external and skeletal traits evaluated using soft X-rays did not differ significantly among groups; however, several patterns were detected among measured traits. The body depth (BD), length of caudal peduncle (LCP), and pre-anal fin length (PAL) of the hybrid were the same as those of E. moara, whereas the pre-pectoral fin length (PPL) and interorbital width (IOW) of the hybrid were the same as those of E. lanceolatus. Traits that did not differ significantly among the three groups included pre-dorsal fin length (PDL), pre-ventral fin length (PVL), length of anal fin (LAF), and length of dorsal fin (LDF), whereas the depth of caudal peduncle (DCP) and snout length (SNL) showed intermediate traits, and eye diameter (ED) was significantly smaller in the hybrid. Therefore, intermediate traits such as DCP and SNL and specific traits such as ED may be used as indices for hybrid classification.

• 한국기계기술학회지
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• 제13권4호
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• pp.165-168
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• 2011

In this paper, the hybrid tube expander unit for fin and tube type heat exchanger are developed by means of enlarging and inserting the smooth tube with a small diameter to a finned tube having larger diameter. In other word, the tube expander tool that is easy to attach and remove from tube is developed. The hybrid tube expander unit developed in this study can move easily and enlarge the tube without fixing at tube sheet. Also, this unit has a function removing scales inside tube by replacing a tube expander ball.

• Journal of Mechanical Science and Technology
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• 제20권7호
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• pp.1068-1076
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• 2006

A plate-fin type recuperator for a gas turbine/fuel cell hybrid power generation system was designed, manufactured, and tested. Performance analysis shows that the performance of the system is directly affected by the performance of the recuperator. Therefore, the recuperator should be designed and manufactured carefully, and its performance should be tested and verified before it is integrated into the system. In this paper, the developing procedure including designing, manufacturing, and testing of a cross flow plate-fin type recuperator was presented. Performance test results showed that the design requirements of the recuperator were almost satisfied. Based on the test results, improved design to reduce the size of the recuperator was suggested.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2105-2110
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• 2004

Plate-fin type recuperators for the gas turbine/fuel cell hybrid power generating system were designed using commercial design software, MUSE. Heat transfer efficiency and total pressure drop in the recuperator were calculated to confirm required recuperator performance. Both counter flow and cross flow type plate-fin recuperators were designed. Results show that the counter flow type has higher efficiency and short core length, but the cross flow type is simpler to construct because the cross flow type does not need additional distributors. Two or three headers for the each recuperator core will be designed and tested to evaluate best header design. The designed recuperators and headers which will be designed later will be constructed, tested, and used in gas turbine/fuel cell hybrid power generating system.

• 설비공학논문집
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• 제23권1호
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• pp.38-46
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• 2011

The hybrid defrost process combined with hot-gas bypass defrost and electric heater defrost was experimentally evaluated about its defrost performance in the fin-tube evaporators of household refrigerators. Also the hybrid defrost process was compared with only electric heater defrost process. The defrost efficiency of the hybrid defrost process was shown two times higher than electric heater defrost process. The defrost time of the hybrid defrost process was shorten about 10%~50% than electric heater defrost process. Thermal shock after defrost process was decreased about 50% for the case of the hybrid defrost. It was found that energy consumption ratio of defrost process was reduced up to 7.4% compared with 22.4% of electric heater defrost at the condition of $25^{\circ}C$ ambient temperature.

• Advances in Computational Design
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• 제6권1호
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• pp.31-42
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• 2021

This research aims to demonstrate the optimal geometrical design of splayed multiple cross-sectional pin fin heat sinks (SMCSPFHS), which are a type of side-inlet-side-outlet heat sink (SISOHS). The optimiser strength Pareto evolutionary algorithm2 (SPEA2)is employed to explore a set of Pareto optimalsolutions. Objective functions are the fan pumping power and junction temperature. Function evaluations can be accomplished using computational fluid dynamics(CFD) analysis. Design variablesinclude pin cross-sectional areas, the number of fins, fin pitch, thickness of heatsink base, inlet air speed, fin heights, and fin orientations with respect to the base. Design constraints are defined in such a way as to make a heat sink usable and easy to manufacture. The optimum results obtained from SPEA2 are compared with the straight pin fin design results obtained from hybrid population-based incremental learning and differential evolution (PBIL-DE), SPEA2, and an unrestricted population size evolutionary multiobjective optimisation algorithm (UPSEMOA). The results indicate that the splayed pin-fin design using SPEA2 issuperiorto those reported in the literature.

• 한국태양에너지학회 논문집
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• 제36권3호
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• pp.53-61
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• 2016

Solar assisted heat pump system uses solar thermal energy as a heat source of evaporator of heat pump. So, COP can be enhanced as well as collector efficiency. For improving performance of this system, some research about hybrid solar collector that has fin-and-tube heat exchanger has been conducted. This collector can get a thermal energy from ambient air for liquid heating, so heated liquid can be used as a heat source of evaporator in heat pump even the solar radiation is not enough. In this study, numerical analysis was conducted for confirming heat gain of liquid according to fin height and pitch of fin-and-tube heat exchanger in collector. As a result, higher heat gain was obtained on lower fin height and narrow fin pitch, but the pressure drop also increased with increment of heat gain. Thus the JF factor considering both heat transfer enhancement and pressure drop was investigated and the maximum value was shown when the fin height and pitch were 40mm and 45mm. So it is considered that this installation condition has a highest heat transfer improvement when comparing with pressure drop. However heat gain of liquid at this condition was less than the other installation conditions of fin pitch on same height. Then, after establishing a proper minimum heat gain of liquid, actual production and experiment of collector will be conducted with fin height and pitch showing maximum JF factor and satisfying selected minimum heat gain of liquid on the basis of results of this study.