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내부 구조에 따른 염분차 발전용 단위셀에서의 유동특성 연구
박천동(Chun Dong Park),홍성국(Sung Kook Hong),김찬수(Chan Soo Kim),황교식(Kyo Sik Hwang),정남조(Nam Jo Jeong) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Salinity Gradient Power (SGP) is potentially one of the largest sources of renewable energy on earth. SGP is completely renewable and less periodic than other renewable sources like wind and solar energy. Reversed Electrodialysis (RED) uses the transport of salt ions through membranes. RED consists of a stack of alternating cathode and anode exchanging permselective membranes. The fluid distribution and pressure drop are one of the important factors in RED performance. In this study, the fluid distribution and pressure drop characteristics of unit cell in RED with different intermembrance structures were investigated numerically. The result indicated that the reduction in pressure drop was achieved in the proposed intermembrane structure as compared with the existing structure using woven type spacer. It was also confirmed that the characteristics on pressure loss was affected by variation of the structure parameter.
외부유로 내벽에 설치된 핀 형상에 따른 이중관 열교환기의 열전달 및 유동에 대한 수치해석적 연구
박천동(Chun Dong Park),이동현(Dong Hyun Lee),박병석(Byung-Sik Park),최재준(Jaejoon Choi) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.2
본 연구에서는 이중관 지중열교환기의 내부에 삽입되는 유로의 외벽에 설치된 핀 형상에 따른 유동 및 열전달 특성의 변화를 수치해석적으로 분석하였다. 해석에는 상용 CFD 소프트웨어인 Ansys Fluent를 이용하였으며, SST k-ω 난류 모델을 적용하였다. 지중열교환기의 성능을 높일 수 있는 핀의 형상을 찾기 위하여 핀의 각도(15°, 30°, 45°, 60°), 높이비(0.1, 0.3, 0.5), 그리고 핀 간의 간격비(1, 3, 5)를 변화시키며 해석을 수행하였다. 그 결과 핀의 각도와 높이가 증가하면서 대부분의 핀 형상에서 외각유로의 외벽과 내벽에서 Nusselt 수가 증가하는 경향이 나타났다. 하지만 핀 각도 15°, 높이 비 0.3 이하의 형상에서 핀이 설치되지 않은 경우보다 외벽의 열전달계수는 증가하며 내벽의 열전달 계수가 감소하는 결과를 관찰하였다. 또한 핀 간의 간격이 감소할 경우 외벽의 열전달계수는 큰 변화가 없으나 내벽의 열전달계수는 감소하는 경향이 나타났다. In this study, the flow and heat transfer characteristics of the finned annular passage were investigated numerically. The annular passage simulates co-axial geothermal heat exchanger, and fins are installed on its inner wall to reduce heat loss from the production passage (annulus) to injection passage (inner pipe). A commercial CFD program, Ansys Fluent, was used with SST k-ω turbulence model. The effects of the geometric parameters of the fin on the inner tube were analyzed under the periodic boundary condition. The result indicated that most parameters had a tendency to increase with an increase in the height and angle of the fin. However, it was confirmed that the Nusselt number of the inner tube on the coaxial 15, 5, 0.3 was lower than that of the smooth tube. Additionally, the Nusselt number of the inner tube exhibited a tendency of decreasing with a decrease in the spacing in Coaxial 15, Sf, 0.3.
하수슬러지를 활용하여 제조한 흡착제의 고정흡착층에서의 H2S 흡착특성
박천동 ( Chun Dong Park ),윤주영 ( Ju Young Youn ),박영성 ( Yeong Seong Park ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.4
H2S adsorption characteristics of adsorbent made by sewage sludge were investigated. For analyses of the manufactured adsorbent, various methods such as Iodine adsorptivity, scanning electron microscope (SEM), and measurements of BET surface area and pore volume were adopted. As the major adsorption characteristic, breakthrough curve was measured by using a continuous fixed bed adsorption column for operating variables such as adsorption temperature (25~45˚C), aspect ratio (L/D)(3~9), gas flow rate (0.1~2.0 liter/min) and H2S gas concentration (50~200ppm). The experimental result showed that the carbonization and activation of sewage sludge are very important for the improvement in H2S adsorption capacity.
일교차가 당뇨병성 창상의 치유에 미치는 영향: 동물 실험 연구
원성훈,천동일,조재호,박인근,이영,Won, Sung Hun,Chun, Dong-Il,Cho, Jaeho,Park, In Keun,Yi, Young 대한족부족관절학회 2020 대한족부족관절학회지 Vol.24 No.4
Purpose: Diabetic foot ulcers are closely related to body surface heat, which can be affected easily by temperature differences. This study examined the correlation between the healing process of diabetic wounds and abnormal diurnal temperature through an animal study. Materials and Methods: Rats in the abnormal diurnal temperature group and control group were given a 10 mm sized full-thickness skin ulcer. Wound size progression was observed in both groups. H&E and Masson's trichrome staining was performed at 14 days after wound formation, and the number of vessels per unit area and histology analysis were performed. The changes in the ulcer were measured through three dimensional cross-section area using INSIGHT<sup>®</sup> devices. Results: The wound recovery period (granulation ingrowing) was 24 days in the abnormal diurnal temperature model and 20 days in the control group. The thickness of scar tissue was 402±23.19 ㎛ in the control group and 424.5±36.94 ㎛ in the diurnal temperature model. Neovascular formation was counted as 5.1±0.97 for the control group and 4.16±0.94 for the diurnal temperature model group. Conclusion: Delayed and inferior diabetic wound healing was observed in the abnormal diurnal temperature group, which was characterized by greater diurnal variations than the typical growth environment.
대항류 채널에서 이온전도성 세라믹 분리막의 산소투과에 관한 수치해석
정우남(Woo-Nam Jung),이대근(Dae Keun Lee),홍성국(Sung-Kook Hong),박천동(Chun-Dong Park),유지행(Ji-Haeng Yu) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
An oxygen transport membrane (OTM) has been receiving remarkable attention because of its potential to produce high-purity oxygen energy-efficiently and economically comparing with conventional cryogenic air separation system. Recently, The KIER reported outstanding oxygen permeation of dual-phase membrane (80% GDC20% LSCF) with modified surface by LSC. In present study, a two-dimensional numerical study was conducted to estimate the oxygen permeation characteristics affected by its various operating conditions in a preliminary OTM module design step. The planar and counterflow type module design was chosen for effective usage of membrane area and to prevent mass transport limitation. Parametric studies show that the oxygen flux is significantly affected by oxygen partial pressure difference between feed-retentate and permeate streams, air feeding mass and working temperature.
소옥천 유역 비점오염 관리를 위한 취약성 지수분석 및 평가에 관한 연구
갈병석 ( Byung-seok Kal ),문현생 ( Hyun-saing Mun ),홍선화 ( Seon-hwa Hong ),박천동 ( Chun-dong Park ),길한뉘 ( Han-nui Gil ),박재범 ( Jae-beom Park ) 한국지리정보학회 2019 한국지리정보학회지 Vol.22 No.2
본 연구에서는 대청호 상류에 위치한 소옥천을 대상으로 유역 및 오염원 특성을 조사하여 각 특성별 지수를 분석하고 취약지역을 분석하였다. 다양한 유역 및 오염원 자료를 지수화하기 위하여 표준화법인 Dimension Index법을 적용하였으며 선정된 지수와 수질모니터링 자료와의 상관성 분석을 통해 각 오염원별 영향인자를 도출하였다. 오염원별 영향인자에 미치는 특성들은 각각의 유의성에 차이가 있었으며 BOD와 COD는 인구밀도와 대지면적 비율, T-N은 CN과 논면적 비율, T-P는 인구밀도와 대지면적 비율에서 유의한 영향이 있는 것으로 검토되었다. 오염원별 영향인자로 판단된 지수를 이용하여 취약지역 우선순위를 산정하였고 배출부하량을 고려하여 산정된 취약 지역과 순위를 비교·검토하였다. 배출부하량은 비점오염 대책 수립시 많이 사용되고 있으나 호소나 하천에 유입되는 유달부하량과 차이가 있어 수질 모니터링 자료와의 상관성 분석시 수질과 유의미한 값이 낮게 나타났다. 따라서 효율적인 비점오염 관리를 위해서는 취약지역 선정과 함께 수질과 상관성 높은 영향인자를 분석하고 해당 인자에 대한 관리가 우선으로 필요할 것으로 판단된다. In this study, the characteristics of watershed and pollution source were investigated in SoOakcheon located in the upper stream of Daecheong Lake. The Dimension Index method was applied to index various watershed and pollution source data. The influence factors of each pollutant source were derived through correlation analysis between selected index and water quality monitoring data. BOD and COD were significantly influenced by population density and land area ratio, T-N by CN and rice area ratio, and T-P by population density and land area ratio, respectively. The discharge load is often used to establish non-point source countermeasures, but there is a difference between the water load and the water load in the lake or river. Therefore, in order to manage non-point pollution efficiently, it is necessary to analyze influential factors with high correlation with water quality and to manage the relevant factors with priority.