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컨테인먼트가 적용된 데이터센터의 CFD 모델링 기법 및 열 관리 성능 평가
함상우(Ham, Sang-Woo),정재원(Jeong, Jae-Weon) 대한건축학회 2015 대한건축학회논문집 Vol.31 No.1
The main purpose of this study is to evaluate thermal management performance of data center with cold-aisle containment by using computational fluid dynamics (CFD) analysis. The main challenge of containment modeling in CFD is to consider the air leakage across the containment, which was neglected or considered based on the researchers’ subjective assumption or complex measurement process. To properly evaluate the thermal management performance of containment, this study utilizes the building airtightness measurement data from building airflow simulation program (CONTAM) to model air leakage across containment. Based on the modeling strategy, the CFD simulation is conducted on modular data center test bed, and an experiment is also implemented in identical condition of CFD simulation. As a result, pressure distribution in the data center is properly modeled with the air leakage model, and the temperature measurement data are in good agreement with CFD results. Unlike intuition, the thermal management performance of containment is not excellent since there is some hot air recirculation through gaps between racks and the floor. This study also suggests that this recirculation can be alleviated by sealing the gaps between racks and the floor through CFD simulation.
경도제거용 나노여과막의 표면 특성 분석 및 막오염기작 연구
함상우 ( Sang Woo Ham ),김영진 ( Young Jin Kim ),김충환 ( Chung Hwan Kim ),( Ho Kyong Shon ),홍승관 ( Seung Kwan Hong ) 한국물환경학회 2013 한국물환경학회지 Vol.29 No.4
In recent years, NF (nanofiltration) membrane has been receiving great attention for hardness removal and has begun to replace traditional lime soda ash softening process, particularly in Florida, USA, mainly due to less sludge production and easy operation. This study aimed to provide detailed surface characteristics of various commercial NF membranes by performing sophisticated surface analysis, which would help more fundamentally understand the performance of NF membranes. More specifically, a total of 7 NF membranes from top NF/RO manufacturers in the world were examined for basic performance tests, surface analysis, and fouling potential assessment. The results demonstrated that NF membranes are classified into two groups in terms of surface zeta potential; they are highly negatively charged ones, and neutral and/or less negatively charged ones. Their hydrophobicities, measured by contact angle, varied from hydrophilic to slightly hydrophobic ones. The AFM measurements showed various surface roughness, ranging from 23 nm (smooth) to 162 nm (rough) of average peak height. Lab-scale fouling experiments were performed using feedwater obtained from conventional water treatment plants in the province of Korea, and their results attempted to correlate to surface characteristics of NF membranes. However, unlike typical RO membranes, no clear correlation was found in this study, indicating that fouling mechanisms of NF membrane may be different from those of typical RO membranes, and both cake deposition and pore blocking mechanisms should be considered simultaneously.
모듈러 데이터 센터에 적용된 다양한 외기냉방 시스템의 급기 조건 및 지역별 에너지 절감효과 분석
함상우(Ham, Sang-Woo),김민휘(Kim, Min-Hwi),정재원(Jeong, Jae-Weon) 대한건축학회 2014 대한건축학회논문집 Vol.30 No.6
The main purpose of this paper is to analyze energy saving potentials of various economizers in modular data center by thermal conditions and locations in response to explosive IT demand and data centers" energy consumption increase. To investigate holistic energy saving potentials, various server thermal characteristics, economizers, and locations are analyzed on a modular data center. As a results, economizers can save cooling coil load 75-100% according to their running conditions, and indirect air-side economizer showed better performance than direct air-side economizer. Even though there is more chiller energy saving with server inlet temperature increase, total energy saving decreased more sharply due to fan energy increase. Furthermore, there should be more energy saving potentials in high latitude climates regardless of type of economizers.
PTFE막을 이용한 빗물 중수 통합형 MBR 시스템 개발 및 성능 평가
이태섭 ( Tae Seop Lee ),김영진 ( Young Jin Kim ),함상우 ( Sang Woo Ham ),홍승관 ( Seung Kwan Hong ),박병주 ( Byung Joo Park ),신용일 ( Yong Il Shin ),정인식 ( In Sik Jung ) 한국물환경학회 2012 한국물환경학회지 Vol.28 No.2
The surface characteristics and performance of PTFE (polytetrafluoroethylene) hollow fiber membranes have been systematically investigated at lab- and pilot-scale to assess their application to membrane-bioreactor, particularly for integrating wastewater reclamation and rainwater harvesting. The PTFE membrane expressed some surface features, such as hydrophobicity, which might enhance membrane fouling. However, lab-scale performance and cleaning experiments under various conditions demonstrated that the PTFE membrane could produce the desirable water flux with good cleaning efficiency, implying easy operation and maintenance due to superior chemical resistance of PTFE membranes. Most of effluent water qualities were met with Korean standard for discharge and reuse, except color. Color level was further reduced by blending with rainwater at 75:25 ratio. Based on the lab-scale experimental results, the pilot plant was designed and operated. Pilot operation clearly showed sTable performance with satisfactory water quality, suggesting that PTFE membrane could be applied for decentralized MBR integrated with rainwater use.