• 대한기계학회논문집B
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• 제34권7호
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• pp.715-720
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• 2010

본 논문은 고분자전해질막 연료전지의 공기 공급을 위해 전기침투현상에 기반을 둔 공기 공급 방법을 제안하고 이를 실험적으로 평가하였다. 작동 유체의 구동을 위해서 전기침투펌프를 낮은 주파수의 교류 전기장에서 사용하였다. 작동 유체는 유연한 막에 의해 막 밀봉하였고, 막의 움직임에 의해 연료전지 내로 공기를 공급하였다. 본 연구에서는 전기침투현상 기반 공기펌프를 사용하여 연료전지의 공기 공급을 성공적으로 설명하였다. 펌프의 출력은 연료전지에서 생성되는 출력을 초과하였지만, 본 논문에서는 펌프의 출력 당 연료전지의 출력비를 줄이기 위한 몇 가지 방법들에 대해 설명하였다.

• 한국산업보건학회지
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• 제19권3호
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• pp.240-249
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• 2009

HRSG(Heat Recovery Steam Generator) building is large enclosed structure included various heat sources. This building needs to appropriately keep internal air temperature for worker's safety and operability of control devices. In this study, ventilation analysis is performed to find proper ventilation method for temperature control. Ventilation analysis is applied to entire internal space of the building with standard $k-{\varepsilon}$ model and enhanced wall treatment because of large size of the structure. And the ventilation method is considered natural and forced convection with two louver structures which has damper or not. Louver structure affect directly air circulation in near HRSG and lower region of the building. Forced ventilation provides strong inertial force which cause upward airflow. From the analysis, it is found that design requirement for internal air temperature can be satisfied by forced ventilation method with louver structure without damper.

• 한국화재소방학회논문지
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• 제16권3호
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• pp.77-83
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• 2002

질소, 아르곤, 이산화탄소와 같은 불활성가스 및 이들의 혼합물을 소화약제로 하여 n-Heptane을 연료로한 cup-burner test 장치에서 불꽃소화농도와 연소시 배가스의 조성을 측정하였다. 이성분 불활성가스계 혼합소화약제의 소화농도는 혼합물의 구성비를 이용한 모델에 의해 잘 예측됨을 알 수 있었다. 불활성 가스계 혼합 소화약제에 의한 소화작용에 있어서 혼합가스의 평균비중이 클수록 소화 성능이 우수하였다. 또한 밀폐된 공간의 구조가 소화에 영향을 미칠 수 있음을 확인하였다. 연소시 배가스 중 이산화탄소 조성은 사용하는 소화약제의 양이 증가할수록 감소하였다. 일산화질소 발생은 소화약제의 질소 함량과는 상관이 없으며 공기유량을 크게 하여 불꽃을 크게 했을 때 검출되었다.

• 한국가스학회지
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• 제23권6호
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• pp.97-102
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• 2019

본 연구에서는 우리나라 가정에서 가장 많이 쓰이고 있는 LNG를 대상이며 수요가 증가함에 따라 가스사고는 늘어나고 있는 실정이다. 그 중 사용자취급부주의로 인한 사고가 가장 많은데 이를 효과적으로 미연에 방지 하고자 시나리오를 구축하여 정보제공을 하고자한다. 가정에서의 가스누출은 밀폐 된 공간이며 이에 따른 적합한 gaussian model을 적용하였다. 4차 산업 혁명으로 스마트 홈 제어 기술이 발전함에 따라 가스누출사고를 예측하고 방지하고자 프로그램으로 정보제공을 할 수 있는 토대를 만들어 스마트 홈 안전 플랫폼에 적용하고자 한다.

• 설비공학논문집
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• 제17권2호
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• pp.191-199
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• 2005

Double pane window system, in which an air layer with a finite width is filled between glasses, is used in order to increase the insulation efficiency. In the present study, a conjugate heat transfer problem of a double pane window system has been studied numerically in order to investigate the effect of an air layer on the heat transmittance of the double pane window system using a finite element method based on P2P1 basis function. In this study on the conjugate heat transfer of a double pane window system, numerically predicted Nusselt numbers with or without conjugate heat transfer effect have been compared with an available existing empirical formula. It has been found that a Nusselt number from an existing formula for an enclosed space is different from that obtained from the present conjugate heat transfer analysis mainly due to the effects of a very high aspect ratio and conjugate heat transfer mechanism. Furthermore, it has been shown that the numerically estimated optimal air thickness of the double pane window system with conjugate heat transfer effect is a little bit longer than that obtained without considering conjugate heat transfer effect.

• 국제초고층학회논문집
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• 제1권2호
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• pp.107-116
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• 2012

The overarching objective of this study is to predict the convective heat transfer around a human body under forced strong airflow conditions assuming a strong wind blowing through high-rise buildings or an air shower system in an enclosed space. In this study, computational fluid dynamics (CFD) analyses of the flow field and temperature distributions around a human body were carried out to estimate the convective heat transfer coefficient for a whole human body assuming adult male geometry under forced convective airflow conditions between 15 m/s and 25 m/s. A total of 45 CFD analyses were analyzed with boundary conditions that included differences in the air velocity, wind direction and turbulence intensity. In the case of approach air velocity $U_{in}=25m/s$ and turbulent intensity TI = 10%, average convective heat transfer coefficient was estimated at approximately $100W/m^2/K$ for the whole body, and strong dependence on air velocity and turbulence intensity was confirmed. Finally, the formula for the mean convective heat transfer coefficient as a function of approaching average velocity and turbulence intensity was approximated by using the concept of equivalent steady wind speed ($U_{eq}$).

• 한국산학기술학회논문지
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• 제15권5호
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• pp.2533-2538
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• 2014

본 연구에서는 노래방 화재의 위험성을 예측하기 위하여 2-zone model CFAST소프트웨어를 이용하여 해석을 수행하였다. 모델은 3차원 비정상 상태이다. 또한, CFAST의 해석 결과와 실제 화재 재현 실험결과를 비교 분석하여 CFAST의 정확성이 검증되었다. 해석 결과 화재가 발생된 방에서 화재발생 5분 이내에 산소농도는 10% 까지 감소하며, 이산화탄소 농도는 5%까지 증가하였다. 따라서 노래방과 같은 밀폐된 공간에서는 유독가스에 의한 질식으로 더 위험한 상황이 발생한다는 것을 예측할 수 있다.

• Journal of Ship and Ocean Technology
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• 제8권3호
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• pp.18-25
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• 2004

Sound reception system is required to detect the sound and the quadrantal direction of the other ship's horn sound, to overcome the effects of enclosed wall for navigation space, functioning as a sound barrier. However, the realized systems can only provide quadrantal information of the other ship. This paper presents a new arrangement of microphones, having geometrically symmetric deployment with the same distances between sensors and the same angles between adjacent sensors with respect to the geometrical center. The sound pressures received at microphones are transformed into the related envelope signals by applying Hilbert transform. The time delays between microphones are estimated by the correlation functions between the derived envelope signals. This envelope base processing mitigates the noises related to the reflection by ship and sea surface. Then, the directional information is easily defined by using the estimated time delays. The suggested method is verified by the generated signals using boundary element method for a small ship model with sea surface wave. The estimated direction is quite similar to the true one and therefore the proposed approach can be used as an efficient sound reception system.

• 한국지열·수열에너지학회논문집
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• 제14권4호
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• pp.53-60
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• 2018

This study was conducted for analysis of a heat pump system using waste heat in an enclosed space such as a green house. The model was developed with mathematical equations in literature and Engineering Equation Solver (EES) was used to get the solution of the developed equations. The simulation results have 5% of reliability comparing the results with actual test data of heat pump system's dynamic operation. The operating performance of the system was calculated with variation of working fluid temperature in the thermal storage tank such as $25^{\circ}C$, $35^{\circ}C$, $45^{\circ}C$ and $55^{\circ}C$. As a result, the system's the highest total heating capacity shows 280 kWh and the storage tank's operating time decreased as the starting storage tank's temperature was high.

• 한국의류학회지
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• 제46권3호
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• pp.390-406
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• 2022

This study aims to establish the optimal environmental conditions for storing textile products. Four textile products (cotton, wool, nylon, cotton/polyurethane) were used to produce experimental fabrics according to artificial contamination and washing conditions. Each fabric was subjected to three environmental conditions (A: 20-25℃/20% RH, B: 20-25℃/50% RH, C: 30-35℃/65% RH) for 4-12 weeks. Changes in textile characteristics include tensile strength, wrinkle recovery rate, and odor intensity. Results show that the change in tensile strength for the four test fabrics slightly decreased with a storage time of 4 to 12 weeks. The wrinkle recovery rate of the fabrics was the lowest under the C condition. UV exposure causes a substantial decrease in the tensile strength of the textiles. The change in odor characteristics was the highest for the odor intensity in the C condition. For storing textile products for sustainable management, it is desirable to maintain a temperature of 20 to 25℃ with a relative humidity of 50% RH or less and to provide ventilation in an enclosed storage space that can also block UV rays.