• 대한원격탐사학회지
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• 제38권6_2호
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• pp.1607-1622
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• 2022

본 연구의 목적은 도시폭염 저감을 위한 기법인 쿨루프를 연구지역에 적용하여 토지피복 객체 간 지표 온도와 흡수일사 간 공간적 상관관계 분석으로 실질적 효과 파악을 목적으로 한다. 이를 위해 실제 쿨루프가 적용된 경상남도 김해시 장유무계동 인근을 연구지역으로 선정하였으며, 드론 DJI Matrice 300 RTK에 열적외 영역센서 FLIR Vue Pro R, 가시광선 영역센서 H20T와 다중분광영역 센서인 Micasense Red-Edge를 활용하여 계측하였다. 계측 일정은 2021년 7월 27일 아침 7시 15분부터 약 1시간 30분 간격으로 총 9장의 열지도와 동일 시간대의 흡수일사 분포도, 쿨루프(113개) 및 일반옥상(367개) 지붕 객체를 추출하였다. 흡수일사 분포도는 ArcGIS의 3D 분석 기능인 Solar Radiation Analysis Tool을 통해 산출한 전천일사 분포도에 Micasense Red Edge를 통해 촬영한 Blue, Green Red, Near Infrared, Red Edge Range 영역대 센서의 조합을 통해 구축한 연구 지역의 알베도 값을 반영하여 구축한다. 전술된 자료를 기반으로 일반옥상과 쿨루프 지붕 객체별 지표온도와 흡수일사 간 Pearson 상관계수를 산출하였다. 분석 결과 일 평균 기준 일반옥상 0.550, 쿨루프 0.387의 상관계수 값을 나타내고 있었다. 하지만, 시간대별 상관성의 변화를 파악한 결과 분석일 기준 태양고도가 높은 시기인 11시 30분과 13시의 경우 일반옥상과 쿨루프 간 상관계수의 차이는 0.022, 0.024 값을 보여 유사한 상관성을 보이고 있다. 그 외 시간대는 일반옥상의 상관계수 값이 쿨루프 보다 약 0.1 이상 높은 값을 보이고 있다. 본 연구는 드론을 통해 취득한 고해상도 영상을 활용하여 쿨루프의 실질적 일사차단 영향의 가능성을 대조군이 되는 일반 옥상과의 상관성 비교를 통해 파악한 사례 연구이다. 향후 본 연구 결과를 기반으로 효율적인 도시열섬 저감기법 적용이 가능할 것으로 사료된다.

• KIEAE Journal
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• 제17권1호
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• pp.49-54
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• 2017

Purpose: Temperature in urban areas increase much more than suburban areas and it is called urban heat island (UHI) phenomenon. There are several solutions to control UHI phenomenon such as green roof system, water space construction, and cool roof system. However, application of green roof system and cool roof system to some of the buildings which compose the city has a critical limit. Therefore, in order to diminish the temperature rising and UHI phenomenon due to climate change of the city, it needs to approach from the viewpoint of site or city, rather than the viewpoint of individual buildings. This study is aims at analyzing UHI phenomenon by characteristics of surface materials and suggesting the solutions to reduce UHI phenomenon by types of complex. Method: Literature reviews were conducted to analyze the cause, mitigating plan, and recent trends of UHI phenomenon. For the simulation analysis, the type of complex was classified 3 representative complex. Based on measured reflectivity, simulation about UHI phenomenon was conducted by setting 4 strategies; albedo of roof, road pavement, green roof system, and vegetating around buildings. Result: As the results of simulating the UHI reduction factor by types of complex, it showed that the effect of temperature reduction on the building roof layer is more effective than adjusting the reflectivity of buildings such as green roof system, planting near the buildings in both the detached house complex, apartment complex, and commercial complex.

• 전기학회논문지P
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• 제63권4호
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• pp.283-289
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• 2014

A Fresnel lens is an optical component which can be used as a cost-effective, lightweight alternative to conventional continuous surface optics. Fresnel lens solar concentrators continue to fulfill a market requirement as a system component in high volume cost effective Concentrating Photovoltaic (CPV) electricity generation. The basic principles of the fresnel lens are reviewed and some practical examples are described. To investigate the performance space of the Fresnel lens, a fast simulation method which is a hybrid between raytracing and analytical computation is employed to generate a cache of simulation data. Injection molders are warming up to the idea of cycling their tool surface temperature during the molding cycle rather than keeping it constant. Heat and cool process are now also finding that raising the mold wall temperature above the resin's glass-transition or crystalline melting temperature during the filling stage and product performance in applications from automotive to packaging to optics. This paper deals with the suitability of Fresnel lenses of imaging and non-imaging designs for solar energy concentration. The concentration fresnel lens confirmed machinability and optical transmittance and roughness measure through manufactured the prototype.

• Nuclear Engineering and Technology
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• 제47권6호
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• pp.746-755
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• 2015

To investigate the effect of hydrogen and oxygen contents on hydride reorientations during cool-down processes, zirconium-niobium cladding tube specimens were hydrogen-charged before some specimens were oxidized, resulting in 250 ppm and 500 ppm hydrogen-charged specimens containing no oxide and an oxide thickness of $0.38{\mu}m$ at each surface. The nonoxidized and oxidized hydrogen-charged specimens were heated up to $400^{\circ}C$ and then cooled down to room temperature at cooling rates of $0.3^{\circ}C/min$ and $8.0^{\circ}C/min$ under a tensile hoop stress of 150 MPa. The lower hydrogen contents and the slower cooling rate generated a larger fraction of radial hydrides, a longer radial hydride length, and a lower ultimate tensile strength and plastic elongation. In addition, the oxidized specimens generated a smaller fraction of radial hydrides and a lower ultimate tensile strength and plastic elongation than the nonoxidized specimens. This may be due to: a solubility difference between room temperature and $400^{\circ}C$; an oxygen-induced increase in hydrogen solubility and radial hydride nucleation energy; high temperature residence time during the cool-down; or undissolved circumferential hydrides at $400^{\circ}C$.

• Safety and Health at Work
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• 제8권4호
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• pp.327-328
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• 2017

Despite provision of drinking water as the most common method of occupational heat stress prevention, there remains confusion in hydration messaging to workers. During work site interactions in a hot and humid climate, workers commonly report being informed to consume tepid fluids to accelerate rehydration. When questioned on the evidence supporting such advice, workers typically cite that fluid absorption is delayed by ingestion of chilled beverages. Presumably, delayed absorption would be a product of fluid delivery from the gut to the intestines, otherwise known as gastric emptying. Regulation of gastric emptying is multifactorial, with gastric volume and beverage energy density the primary factors. If gastric emptying is temperature dependent, the impact of cooling is modest in both magnitude and duration (${\leq}5$ minutes) due to the warming of fluids upon ingestion, particularly where workers have elevated core temperature. Given that chilled beverages are most preferred by workers, and result in greater consumption than warm fluids during and following physical activity, the resultant increased consumption of chilled fluids would promote gastric emptying through superior gastric volume. Hence, advising workers to avoid cool/cold fluids during rehydration appears to be a misinterpretation of the research. More appropriate messaging to workers would include the thermal benefits of cool/cold fluid consumption in hot and humid conditions, thereby promoting autonomy to trial chilled beverages and determine personal preference. In doing so, temperature-based palatability would be maximized and increase the likelihood of workers maintaining or restoring hydration status during and after their work shift.

• 아시안잔디학회지
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• 제9권3호
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• pp.253-260
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• 1995

This study is aimed to understand the effects of temperature, light and GA soaking treatment on the seed germination of perennial ryegrass 'Dandy', creeping hentgrass 'Penlinks', tall fescue 'Arid' and Kentucky hluegrass 'Nasaw'. These experiments are carried in vitro, and their results obtained are summarized as the followings ; The optimum temperature for seed germination of perennial ryegrass 'Dandy' was found to he ranged at 20~30$^{\circ}C$, and the optimum temperature for germination of creeping bentgrass 'Penlinks', tall fescue 'Arid' and kentucky bluegrass 'Nasaw' seeds was found to be ranged at 20~25$^{\circ}C$, whereas the germination percentage under the below or above temperature of this range decreased. The germination of perennial ryegrass 'Dandy' and tall fescue 'Arid' seeds showed no effect on light, and while the germination percentage of creeping hentgrass 'Penlinks' increased more highly under the dark condition than under the light condition. The germination percentage decreased according to the higher temperature. The germination of Kentucky bluegrass 'Nasaw' seeds increased more highly under the dark condition than under the light condition at 20~25$^{\circ}C$, whereas the germination percentage under the dark condition at 15$^{\circ}C$ and 30$^{\circ}C$ decreased. In case of GA soaking treatment of seeds, all the cool season turfgrasses tested showed their own promoting effects on seed germination. The early germination of tall fescue 'Arid' was good without the soaking times. Creeping bentgrass 'Penlinks' and perennial ryegrass 'Dandy' had re-spectively the highest germination percentage at 10min and 1hr soaking treatment, and the longer the soaking time, the lesser the germination percentage. Kentucky bluegrass 'Nasaw' obtained the best results at 24has soaking treatment, and the longer the soaking time, the better the ger-mination percentage.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.296-301
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• 2003

A study on the engineering design and numerical thermo-hydraulic analysis for KSTAR TF coil structure cooling system has been conducted. The numerical analyses have been done to verify the engineering design of cooling using the commercial code, FLUENT and in-house code for calculating helium properties which varies with cooling tube's heat transfer. Through the engineering design process based on the steady heat balance concepts, the circular stainless steel tube with inner diameter of 4 mm for TF coil has been selected as cooling tube. From normal operation mode analysis results, total 28 cooling tubes were finally chosen. Also, three dimensional cool down analysis for TF coil with designed cooling tube was satisfied with next three design criteria. First is cooling work termination within a month, second is maximum temperature difference within 50 K in TF coil structure and third is exit helium pressure above 2 bar. Consequently, these cool down scenario results can afford to adopt as operating scenario data when KSTAR facilities operate.

• 한국작물학회지
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• 제44권1호
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• pp.64-69
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• 1999

Gelatinization characteristics of 111 glutinous rice varieties were evaluated by Rapid Visco Analyzer. Gelatinization viscosity of glutinous rice tested varied with ecotypes or varietal groups: indica, japonica, and Tongil type. Indica rice showed the highest average value of initial pasting temperature. The average values for peak, hot, and cool viscosities were highest in Tongil-type rice, and lowest in japonica rice. Japonica showed the lowest breakdown and consistency, but the highest setback value. Indica was lower in alkali digestion value (ADV), and shorter in gel length after gelatinization thanjaponica and Tongil-type. Glutinous rices tested could be divided into six groups by cluster analysis based on their gelatinization characteristics. Group I-A was mostly early maturing japonica varieties while I-B was mostly indica and Tongil-type rices. Groups II-A and II-B were consisted of very early maturingjaponica, and III-A and III-B included medium or medium late maturingjaponica varieties. Group III-A showed the lowest average values of peak, hot, cool, and consistency viscosities, and also in breakdown and setback ratios. Group I-B revealed the highest values in peak, hot, cool, breakdown, and consistency viscosities. ADV was low in groups I-A, I-B, and II-B, and gel consistency was not different among the six varietal groups. Principal component analysis using seven traits related with gelatinization produced four effective components, and the first and second components were highly correlated with all the gelatinization characters evaluated.

• 천문학회보
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• 제37권2호
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• pp.143.1-143.1
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• 2012

We attempt to investigate the main reason of the asymmetrical light curves of contact and near-contact eclipsing binary base on the hypothesis that cool spot was produced on late type star while hot spot was produced from transferred material from their companion star hitting surface. We select 7 eclipsing binary systems which showed asymmetric light curves and mass transfer. Period variation and mass transfer rate were obtained from O-C diagram. Radial velocity curves and light curves of those 7 eclipsing binary system were adopted from available literature in order to obtain the absolute dimension. For four contact eclipsing binary system (AD Phe, EZ Hya, AG Vir and VW Boo), their component stars belonged to spectral type G to K was fitted by cool spot model. While the other two near-contact systems (RT Scl and V1010 Oph) and one contact system (SV Cen) was fitted by cool spot model. The densities of the materials are adopted from stellar model which calculate by stellar structure code. The calculated spot temperature turns out to agree with the photometric solution but there are no correlate between period variation rate and type of spot.

• Journal of Animal Science and Technology
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• 제61권1호
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• pp.47-53
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• 2019

This study was performed to evaluate the microbial and temperature changes of boxed beef during transport and distribution under vacuum and modified atmosphere packaging (MAP), and to compare between excision and swab sampling for 15 days. The top round and striploin (quality grade 1) from Hanwoo steers at 2 days post-slaughter were obtained from a local meat processing plants and chilled at $4{\pm}2^{\circ}C$ in a cold room. The boxes were transported under refrigeration ($4{\pm}2^{\circ}C$) to the laboratory within half an hour. Vacuum and MAP packs were subsequently taken out from cool boxes, and microbiological examinations were carried out at 0, 6, 12, and 24 h of storage time. MAP was more effective than vacuum packaging for the inhibition of total aerobic, lactic acid bacteria and Pseudomonas (p < 0.05). Microbial loads of swab methods were slightly lower than those of excision ones (p < 0.05). The results of this study could be utilized by meat consumers in future studies as well as by manufacturers to determine the ideal storage conditions for cool boxed meat, thus ensuring reduced economic losses due to spoilage.