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Yoo, Jiwon,Chang, Seong Jin,Lee, Jongki,Wi, Seunghwan,Kim, Sumin Elsevier 2019 JOURNAL OF CLEANER PRODUCTION Vol.213 No.-
<P><B>Abstract</B></P> <P>Cross Laminated Timber (CLT) is attracting worldwide attention, due to its durability, usability, and many other advantages. However, since CLT is made of timber, analysis of the hygrothermal performance is essential. In this study, the basic hygrothermal values are measured to obtain the exact hygrothermal performances. The values are put into the simulation with various assemblies which has hygroscopic effects. The effectors are the type of insulation, the presence of the vapor retarder, the climate condition and the type of standards. The final goal of this paper is to find the optimal CLT assemblies. The thermal conductivity, thermal transmittance coefficient, and water vapor resistance factor were measured. The thermal transmittance coefficient of the wall system was measured by using TCi and facing thermo-hygrostat, and applied in the simulation. The water vapor resistance was measured by conducting dry-cup test. In addition, the various conditions that affect the thermal moisture behavior were applied to the simulation for getting stable hygrothermal results. As a result, the standard of Passive house and Domestic wooden house, the climate condition, the presence of breathable water proofing paper, and the insulation alternatives of Expended Polystyrene (EPS) and Extruded Polystyrene (XPS) were applied. It was concluded that breathable waterproofing paper should be installed inside, and the applications of both XPS and EPS made no difference to moisture but the application of Mineral Wool was adversely affect to hygrothermal performance of the CLT wall system. The thickness of insulation should be designed according to the Passive house standard (0.15 W/m<SUP>2</SUP>K) rather than the Domestic (Korea) Wooden house standard (0.21 W/m<SUP>2</SUP>K).</P>
Design of Full-Order Flux Observer for Induction Motor Drive Robust to Rotor Time Constant Variation
Jiwon Yoo,Joohyun Lee,Seung-Ki Sul 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper proposes a novel full-order flux observer for flux estimation of an induction motor robust to rotor time constant variation. The influence of rotor time constant error in the conventional full-order flux observer is analyzed in the frequency domain, and it is verified that the proposed method has better property on the rejection of the rotor time constant error on flux estimation. The proposed observer is designed on the synchronous reference frame with a simple synchronous speed estimator which doesn’t require additional control loop such as phase locked loop or position estimator which was commonly used when constructing the observer on the synchronous reference frame. The reduced influence of rotor time constant error to the observer is verified with simulation and experimental results.
Spent coffee grounds as supporting materials to produce bio-composite PCM with natural waxes
Yoo, Jiwon,Chang, Seong Jin,Wi, Seunghwan,Kim, Sumin Elsevier 2019 CHEMOSPHERE - Vol.235 No.-
<P><B>Abstract</B></P> <P>Novel kinds of bio composite Phase change materials were prepared by the use of bio-wastes. Of the by-products, coffee wastes, which is currently consumed and abandoned as coffee as a drink, was used as the supporting material for PCM. It was found through chemical composition of FTIR of SCBW, SCPW, SCGW and that the coffee wastes were effectively vacuum impregnated into each natural wax. As a result of TGA, the thermal stability of SCBW, SCPW, SCGW and SCNW was checked. In addition, the DSC results were used to determine the heat storage performance of each material. Micro-morphological analysis with FE-SEM showed whether the impregnation was successful. The use of bio-compatible PCM by-products is economical as well as environmentally friendly and is sufficient for building applications in terms of thermal performance compared to other bio-composites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Composites are made with PCM using coffee grounds as supporting materials. </LI> <LI> Bio-supporting material and bio-PCM are vacuum impregnated to create a complete bio-composites. </LI> <LI> Analyze thermal performance of coffee grounds itself and coffee grounds impregnated with PCM. </LI> <LI> SCGs hardly restricted the phase change behavior of PCM (wax). </LI> <LI> Dynamic heat transfer analysis shows that wax/SCG composite has time lag effect. </LI> </UL> </P>
WUFI를 이용한 공동주택 붙박이가구의 층별 · 형태별 결로 생성 비교 평가
유지원(Jiwon Yoo),장성진(Seong Jin Chang),이종기(Jongki Lee),위승환(Seunghwan Wi),김수민(Sumin Kim) 한국가구학회 2018 한국가구학회지 Vol.29 No.1
Recently, as the continuously increasing of the one-person households, builders were focusing on a built-in furniture development for efficiency. Through the dead space of the space can be reduced. Also, Condensation that occurs in a built-in furnitures installation space may result in different results depending on the room’s direction, floor, finish, adjacent room effect, occupant’s lifestyle. In this background, it can be considered in terms of functional aspect and morphological aspect by using WUFI2D simulation system. As a result, the tendency of occurrence of condensation was examined by comparing the water content and the growth potential of fungus graph which came from WUFI2D. Results of this study are as followings: Built-in furniture, both top & bottom open, is more stable to condensation than the built-in furniture with the top or bottom open. Also, Among from the top floor built-in furniture to the bottom of it, the bottom one is more stable to condensation.
유지원 ( Jiwon Yoo ),장성진 ( Seong Jin Chang ),김수민 ( Sumin Kim ) 한국목재공학회 2019 한국목재공학회 학술발표논문집 Vol.2019 No.1
Cross Laminated Timber (CLT)는 내구성, 유용성 및 기타 여러 장점으로 전 세계적으로 주목을 받고 있다. 그러나 CLT는 목재로 만들어진 재료이기 때문에 열습기 분석이 필수적이다. 본 연구에서는 벽체의 열습기 성능을 정확하게 분석하기 위한 시뮬레이션을 실행할 수 있도록 필수적으로 요구되는 열습기 물성 값을 측정하였다. 먼저 열전도율, 열관류율 및 수증기 저항 계수를 측정하였다. 이러한 열습기 물성값은 시뮬레이션에 적용되어 정확한 값을 도출하고자 하였고, 다양한 CLT 벽체 조합을 적용하여 가장 안정적인 열습기 거동을 보이는 벽체 조합을 찾고자 하였다. 다양한 벽체 조합으로써 18.9월 기준으로 전 후 변경된 건축물의 에너지 절약 설계 기준 차이, 기후 조건, 통기성 방수지의 유무, EPS (Expanded Polystyrene), XPS (Extruded Polystyrene) 의 단열재 대안이 고려되었다. 그 결과 통기성 방수지는 내부에 설치해야하며, XPS와 EPS의 적용은 수분 관련하여 벽체에 아무런 영향을 주지 않지만 미네랄 울의 적용은 CLT 벽체 시스템의 열습기 성능에 악영향을 미친다는 결론이 도출되었다. 단열재 두께는 건축물 에너지 절약 설계 기준 변경 전의 단열 성능 (0.21W/㎡K)과 변경 후의 단열 성능 (0.15W/㎡K)을 고려했을 때 후자의 경우가 열습기 성능이 우수한 것으로 판단되었다.