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유동관성에 따른 Micro-Gap 판형 열교환기 내부 유동분배 수치해석
박장민(Jang Min Park),윤석호(Seok Ho Yoon),이공훈(Kong Hoon Lee),송찬호(Chan Ho Song) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.11
본 연구에서는 micro-gap 판형 열교환기 내부의 열유동 특성에 대한 수치해석을 수행하였다. 특히 유량 조건에 따라 열교환기의 주 채널로부터 각 micro-gap 으로의 유동분배에 대한 유동관성의 영향에 대하여 조사하였다. 열교환기 주 채널의 유동을 레이놀즈 수 100 부터 10000 까지 변화시키며 그에 따른 각 micro-gap 으로의 유동분배와 온도분포의 불균일 정도를 평가하였다. 수치해석 결과 유동분배는 유동관성에 의해 크게 영향을 받는 것으로 나타났으며, 관성 효과를 감소시킬 수 있는 헤더 설계를 통해 유동분배 불균일 정도를 줄일 수 있었다. 또한 micro-gap 을 통과한 유체의 온도분포의 불균일 정도는 주유량이 증가함에 따라 증가 후 감소 추세를 나타냈다. This paper presents numerical study on flow and heat transfer characteristics in micro-gap plate heat exchanger. In particular, we investigate the effect of flow inertia on the flow distribution from single main channel to multiple parallel micro-gaps. The flow regime of the main channel is varied from laminar regime (Reynolds number of 100) to turbulent regime (Reynolds number of 10000) by changing the flow rate, and non-uniformity of the flow distribution and temperature field is evaluated quantitatively based on the standard deviation. The flow distribution is found to be significantly affected by not only the header design but also the flow rate of the main channel. It is also observed that the non-uniformity of the temperature field has its maximum at the intermediate flow regime.
Sol-Gel 방법을 이용하여 제작된 Pt이 첨가된 Fe<sub>2</sub>O<sub>3</sub> 나노 입자의 가스 감지 특성
장민형,임유성,최승일,박지인,황남경,이문석,Jang, Min-Hyung,Lim, Yooseong,Choi, Seung-Il,Park, Ji-In,Hwang, Namgyung,Yi, Moonsuk 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.5
$Fe_2O_3$ is one of the most important metal oxides for gas sensing applications because of its low cost and high stability. It is well-known that the shape, size, and phase of $Fe_2O_3$ have a significant influence on its sensing properties. Many reports are available in the literature on the use of $Fe_2O_3$-based sensors for detecting gases, such as $NO_2$, $NH_3$, $H_2S$, $H_2$, and CO. In this paper, we investigated the gas-sensing performance of a Pt-doped ${\varepsilon}$-phase $Fe_2O_3$ gas sensor. Pt-doped $Fe_2O_3$ nanoparticles were synthesized by a Sol-Gel method. Platinum, known as a catalytic material, was used for improving gas-sensing performance in this research. The gas-response measurement at $300^{\circ}C$ showed that $Fe_2O_3$ gas sensors doped with 3%Pt are selective for $NO_2$ gas and exhibita maximum response of 21.23%. The gas-sensing properties proved that $Fe_2O_3$ could be used as a gas sensor for nitrogen dioxide.
조영제 사용 전 피부반응검사 후 발생한 조영제 과민반응의 발생 빈도와 임상 양상
박보배 ( Bo Bae Park ),박창한 ( Chang Han Park ),노인영 ( In Young Nho ),김해성 ( Hae Sung Kim ),강남규 ( Nam Kyu Kang ),장석일 ( Suk Il Chang ),김장민 ( Jang Min Kim ) 대한천식알레르기학회(구 대한알레르기학회) 2016 Allergy Asthma & Respiratory Disease Vol.4 No.6
Purpose: Hypersensitivity reactions to contrast media (CM) are one of the most common causes of drug adverse reactions. The overall prevalence of immediate hypersensitivity reaction (IHR) was 0.16%-7.7% to nonionic CM. Although IHR to CM has been traditionally considered nonallergic, there is growing evidence that the mechanism of IHR to CM is mediated by IgE. It can be severe, even fatal, and a legal problem. To reduce IHR, the prescreening skin test is on the rise. Methods: We reviewed cases of IHR to CM during enhanced computed tomography (CT) from 2008 to 2015 at a secondary hospital in South Korea. Patients who underwent enhanced CT were performed the 2-step prescreening skin test before nonionic CM-enhanced CT. If patients had adverse reactions to CM, the reactions were reported. IHR to CM was defined as an immediate reaction within 1 hour after CM administration. The Ring and Messmer system was used to classify the severity of reactions by grades I to IV, and we defined grades III and IV as severe reactions. Results: A total of 30,105 CM-enhanced CT cases were recruited from 2008 to 2015. A total 46 patients with CM adverse reactions were reported. The IHR were noted in 30 of the total patients (0.1%), of which 6 had severe reaction. Conclusion: The prevalences of IHR and severe IHR to CM were 0.1% and 0.02%, respectively. Further studies are needed to evaluate the usefulness of prescreening skin tests to prevent IHR to CM. (Allergy Asthma Respir Dis 2016:4:442-448)
박장민(Jang Min Park),송찬호(Chan Ho Song),윤석호(Seok Ho Yoon),이공훈(Kong Hoon Lee) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6
Flow and heat transfer characteristics in a microchannel heat exchanger are investigated numerically. Particularly, we study the effect of flow inertia on the flow distribution from a single main channel to multiple parallel microchannels. The flow regime of the main channel is varied from laminar regime to turbulent regime. The non-uniformity of the flow distribution and temperature field is evaluated quantitatively based on a standard deviation. According to the numerical results, the flow distribution is significantly affected by the flow rate of the main channel and the header design, and the non-uniformity of the temperature field is maximum at the intermediate flow regime.
산림지역의 유출특성을 고려한 남강댐유역내 주요 하천관측지점에 대한 홍수유출량 추정
김성재,박태양,장민원,김상민,Kim, Sung-Jae,Park, Tae-Yang,Jang, Min-Won,Kim, Sang-Min 한국농공학회 2010 한국농공학회논문집 Vol.52 No.6
The objective of this study is to estimate the flood runoff for three guaged stations within Namgang-Dam watershed which are operated by KWATER. For a flood runoff simulation, HEC-HMS was applied and the simulated runoff was compared with observed from 2004 to 2008. The watershed area of Sancheong, Shinan, and Changchon were 693.6 $km^2$, 413.4 $km^2$, and 346.48 $km^2$, respectively. The average runoff ratio of observed runoff for three watersheds were 0.725, 0.418, and 0.586, respectively. The dominant land cover of three watersheds are forest with the value of 71.6 %, 73.1 %, and 82.0 %. Three different cases according to the potential maximum retention of forest areas for calculating the curve number were applied to decrease the error between the simulated and observed. The simulated peak runoff of case 3 which applied the 90 % of potential maximum retention of curve number which is equivalent to AMCI for all the AMCI, AMCII, and AMCIII conditions showed least root mean square error (RMSE). The case 1, which was suggested by previous study, showed high discrepancy between the simulated and observed. Since the forest area consists of more than 70 % for all three watersheds, the application of curve number for forest is critical to improve the estimation errors. Further research is required to estimate the more accurate curve number for forest area.