Study on Evaluation of Local Cooling Performance using Piezoelectric and Thermoelectric Modules

Hoo-suk Oh(오후석 ),Byung-Hui Choi(최병희) 한국산학기술학회 2017 한국산학기술학회논문지 Vol.18 No.2

본 논문에서는 소형 전자기기와 같은 발열부 온도 제어를 위해 압전 소자와 열전 소자를 이용하여 국소부 냉각 성능을 실험적으로 조사해 보았다. 실험은 열전 소자를 이용하여 실험 영역내에 냉각부를 형성하고, 압전 소자에 80Hz와 110Hz의 인가주파수를 각각 적용하여, 압전 소자를 작동시켰을 때와 작동시키지 않았을 때 열전 소자에 의해 형성된 시험부의 냉각 영역에서 온도 분포를 측정하였다. 또한, 냉각 영역의 온도측정 결과를 토대로 압전 소자를 적용하였을 때와 적용하지 않았을 때 냉각 영역의 성능 계수를 계산하고, 가시화 장치를 구성한 후 시험부내에 냉각 영역의 열유동 현상도 확인해 보았다. 실험결과, 온도분포 측정 실험 결과와 성능 계수 계산 결과로 부터 압전 소자를 작동하지 않은 경우보다 압전 소자를 작동한 경우에서 냉각 성능이 개선되는 것을 확인할 수 있었다.. 또한, 가시화 결과를 토대로 열전 소자에 의해 형성된 냉각영역에 압전 소자를 작동시켰을 경우에 냉각 영역의 국소부에 압전 소자에 의한 상하 진동의 강제 대류 현상이 발생하면서 냉각영역 전체에 고르게 분포하는 유동을 형성하고 냉각 성능이 개선되는 원인을 확인할 수 있었다. This paper investigated experimentally the performance of cooling systems using thermoelectric and piezoelectric modules for local heating and temperature control, such as a handheld electronic devices. The temperature distribution of the cooling region using thermoelectric modules was measured when the piezoelectric module was and was not with a frequency of 80Hz and 110Hz. The coefficients of performance were also calculated by the temperature results, and the thermo-flow phenomena in the cold region was visualized under the same conditions. The results of the temperature distribution measurements and the coefficient of performance showed that the cooling performance of the cooling system using thermoelectric modules can be improved by operating the piezoelectric module. In addition, when the piezoelectric module was operated based on the result of visualization in the cold region, which was formed by thermoelectric modules, the performance thermoelectric cooling was improved by the thermo-flow formed in the entire cold region as the forced convection of vibration was generated on the local cold region by the piezoelectric module.

구형 폭발파에 대한 해석적 해

오후석(Hoo-Suk Oh),김정은(Jeong Eun Kim),곽호영(Ho-Young Kwak) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10

Vapor cloud explosions(VCEs) are serious hazards in refining and petrochemical industries. Until now, several empirical models have been proposed to access the damage due to the explosions. An analytical solution of a spherical blast waves due to violent explosion by TNT or any other explosives was obtained by solving the Euler equations in this study. Our calculation results are in good agreement with the results by Multi-Energy method, a well known empirical model. The results may be applied to evaluating the damages due to the explosion.

고분자 전해질 연료전지의 엑서지 및 열경제학적 해석

오후석(Hoo-Suk Oh),곽호영(Ho-Young Kwak) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

Exergy and thermoeconomic analysis were performed for a 1.5-㎾ Polymer-Electrolyte Membrane Fuel Cell (PEMFC) plants which offers many advantage for cogeneration in the aspect of high electrical efficiency and low emissions. The unit costs of products of the system were evaluated by using MOPSA(Modified Productive Structure Analysis) which has been developed by the phase-change laboratory in Chung-Ang University. For full load condition, the electrical efficiency and the unit cost of electricity are about 48% and 0.091 $/㎾h respectively, which tum out to be 120% higher than the cost obtained for the 1000-㎾ gas turbine cogeneration plant, 0.076 $/㎾h. This fuel cell system may be viable economically when the initial investment cost per power is reduced to the level of the gas turbine cogeneration plant.

개인 및 사고원인 특성이 재난안전인식에 미치는 영향분석

오후,임동균,Oh, Hoo,Yim, Dong-Kyun 한국안전학회 2021 한국안전학회지 Vol.36 No.2

The purpose of this study is to diagnose the level of disaster safety perception (disaster safety importance, accident possibility, personal safety, and regional safety) of local residents, and to analyze the impact of individual and accident cause characteristics. The analysis method used multiple regression analysis, and the main analysis results are as follows. First, disaster safety importance and accident possibility were higher as residents who had experience in safety education and were willing to visit the safety experience center in the province. Second, disaster safety importance was higher as the cause of the accident was the lack of response 119 and police. And accident possibility was higher as the cause of the accident was the lack of prior treatment by the state and local governments. Third, personal safety and regional safety were higher for men, and especially personal safety was lower as residents with children. The results of this study can be used as basic data for establishing regional customized disaster safety policies based on the perception of local residents, who are policy consumers.

미세유로에서 나노유체의 강제 대류 열전달

정정열(Jung-Yeul Jung),오후석(Hoo-Suk Oh),곽호영(Ho-Young Kwak),최경빈(Kyong-Bin Choi),고창복(Chang-Bok Ko) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5

Convective heat transfers of a nanofluid in rectangular microchannel were measured. An integrated microsystem consisting of a single microchannel on one side and two localized heaters and seven polysilicon temperature sensors along the channel on the other side were fabricated. Aluminum dioxide (Al₂O₃) suspended nanofluids with various particle volume fractions were used in experiment to investigate the effect of the volume fraction of the nanoparticles to the convective heat transfer and fluid flow in microchannels. The convective heat transfer coefficient with Al₂O₃ suspended nanofluid was measured to be increased up to 30 % compared to the distilled water at a volume fraction of 1.8 vol.% without major friction loss. A new type of convective heat transfer correlation was proposed to correlate experimental data of heat transfer for nanofluids in microchannels.

전자장치 냉각을 위한 콘 형상 모세관을 이용한 모세관 펌프 루프

정정열(Jung-Yeul Jung),오후석(Hoo-Suk Oh),곽호영(Ho-Young Kwak),이대근(Dae Keun Lee),고창복(Chang-Bok Ko) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11

A capillary pumped loop (CPL) was developed using cone shaped capillary structure for cooling electronic device. Cone shaped capillary structure was constructed by sand blast with 32 ㎛-diameter Al₂O₃ nano particles. The CPL fabricated was tested under various conditions such as different relative heights, fill ratios and heat fluxes. The operation conditions of CPL were varied depending on relative height, fill ratio and heat flux. With an allowable temperature of 55 ℃ on the evaporator surfaces, the CPL can handle a heat flux of about 0.8 W/㎝². Steady state operation condition was achieved within 10 minutes.

열경제학적 방법에 의한 동력플랜트나 냉동플랜트 내 구성기기의 성능저하 진단

유영필(Yungpil Yoo),오시덕(Si-Doek Oh),오후석(Hoo-Suk Oh),곽호영(Ho-Young Kwak) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.4

무부하급가속검사방법을 이용한 디젤자동차의 매연프로브 성능에 관한 연구

김재열(Jae-Yeol Kim),채일석(Il-Seok Chae),오후석(Hoo-suk Oh) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.9

Inspection of vehicle systems is regularly performed by the state to ensure the emission status and the safety of vehicles. Thereby, the safety and quality of life can be improved by reducing green-house gases and fine dust, which are the main causes of vehicle defects and air pollution. This study analyzed the soot measuring probes used in the free acceleration mode method, at no-load condition, looking at the efficiency of a probe to measure soot emissions from diesel vehicles. In this study, a technique that can improve the inhalation efficiency of the probe over the (a) probes and the improved (b) probes was applied to probes (c). Probe (c) involves a structure designed close to the center of the circumference of the exhaust pipe. Results showed that the suction efficiency was improved by adding a variable center unit.

도시재생사업 인지도가 장소애착에 미치는 영향

오후(Oh, Hoo),장인수(Jang, In Soo),황희연(Hwang, Hee Yun) 한국지역지리학회 2016 한국지역지리학회지 Vol.22 No.3

도시재생(Urban Regeneration)은 지역의 경제적 발전과 활성화 도모를 궁극적 목표로 한다. 도시재생사업의 목표달성과 지속적 운영을 위해서는, 그 장소를 찾는 사람들의 인식을 살펴야 하며 이러한 인식은 그 장소에 많은 관심 과 방문을 유도함으로써 지역 활성화 등의 실현수단이 되는 장소애착(place attachment)으로 대변된다. 이에 본 연구 는 도시재생사업을 진행 중인 청주시 중앙동을 중심으로 물리적 환경과 활동 프로그램에 대한 인지도를 측정하였고 다중회귀분석을 실시하여 인지도가 장소애착 형성에 영향을 주었는지 분석하였다. 분석 결과, 이용객은 도시재생사업 요인을 인지함으로써 ‘나는 이곳에 오래 머무르고 싶다’, ‘나는 현재 장소의 모습이 바뀌면 그리울 것이다’라는 장소애 착을 형성하지만 ‘이곳은 다른 곳과 차별적이다’라는 장소애착은 형성하지 못하고 있다. 결과적으로, 물리적 환경과 활동 프로그램을 동시에 반영하고 보다 풍부한 이용객의 심리를 형성하는 도시재생사업의 방향을 제시하였다. The ultimate goal of urban regeneration is the economic development and activation of region. In order to continue to management the urban regeneration projects and to achieve a goal, we should look at the recognition of people visiting the place. This recognition is represented as a place attachment. Place attachment is the realizing means for local activation by inducing a lot of attention and a visit to place. Accordingly, this study was selected the Jungang-dong in Cheongju as a case study and measured awareness of the physical environment and activity programs. Based on the survey, this study analyzed the impacts of awareness of urban regeneration project on place attachment by carrying out multiple regression analysis. According to the analytical results, Visitors formed an place attachment called ‘I want to stay here longer’ and ‘I will miss here if this place has changed’. However, visitors are unable to form an place attachment called ‘Here is a distinctive place’. Finally, this study suggests the direction of urban regeneration projects to reflect the physical environment and activities programs at the same time and form the rich psychology of visitors.

공간계획에서 취약계층 고려방식의 개선방안

오후(Oh Hoo),김보은(Kim Bo Eun),배민기(Bae Min Ki) 한국환경정책학회 2019 한국환경정책학회 학술대회논문집 Vol.2019 No.10