• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.440-447
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• 1999

The frosting characteristics on the vertical parallel plates with three cooling plates were experimentally investigated. The experimental parameters were the cooling plate temperature, the air humidity, the air temperature, the air Reynolds number, and the location. The frosting conditions were limited to air temperatures from 10 to $15^{\circ}C$ , air Reynolds numbers from 1600 to 2270, air humidity ratios from 0.00275 to 0.0037kgw/kga and cooling plate temperatures from -10 to $-20^{\circ}C$. Frost growth and density toward the front of the plate were more thick and dense than toward the rear. Frost growth increased with decreasing plate temperature and increasing humidity. In the conditions of the laminar flow, dew point below $0^{\circ}C$and non-cyclic frosting period, frost thickness increased with increasing air temperature. The reason of increasing frost thickness with increasing air temperature was sublimation-ablimation process. The average growth thickness along the locations showed little dependence on the Reynolds numbers.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.10
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• pp.724-732
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• 2012

The microchannel evaporator with louver fin using carbon dioxide are analyzed according to the frost growth. To predict the performance of microchannel evaporator with the frost growth under low temperature, the simulation condition of previous studies was applied. As a result, the frost thickness increases and its increasing rate is reduced when the operating time increases. Frost thickness increases gradually below the quality of 0.74, and then it decreases rapidly. In addition, the frost growth of present model under same surface temperature is very similar trends with Moallem's test results. In case of low temperature application, the dimensionless frost thickness increases dramatically and it is about 0.86 after 10 minutes.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.2
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• pp.122-128
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• 2006

In this paper, frosting experiments were conducted with variations of frosting parameters in order to obtain the correlations of frost properties. As a result, the local thickness, density, and surface temperature of the frost layer were presented. The dimensionless correlations for the frost thickness, frost density, frost surface temperature and heat transfer coefficient were derived as functions of dimensionless frosting parameters by using a dimensional analysis.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1546-1551
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• 2004

This paper presents a mathematical model to predict the frost properties and heal and mass transfer within the frost layer formed on a cold plate. The laminar flow equations for the air-side are analyzed. and the empirical correlations of local frost properties are employed in order to predict the frost layer growth. The correlations of local frost density and effective thermal conductivity of frost layer, obtained from various experimental conditions, are derived as functions of various frosting parameters (Reynolds number, frost surface temperature, absolute humidity and temperature of moist air, cooling plate temperature, and frost density). The numerical results are compared with experimental data and the results of various models to validate the present model, and agree well with experimental data within a maximum error of 10%. The heat and mass transfer coefficients obtained from the numerical analyses are presented, as the results, it is found that the model for frost growth using the correlation of heat transfer coefficient without solving air flow have a limitation in its application.

• The Safety technology
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• no.178
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• pp.15-17
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• 2012

1960년대는 흔히 국가산업발전의 태동기로 표현되지만, 당시 우리나라는 산업다운 산업이 전무한 불모지나 다름없었다. 이런 상황 속에 1969년 안전보호구 전문 생산업체 '성안세이브'가 설립됐다. 우리나라가 경제대국으로 올라서리라고는 아무도 예상 못했던 시절이기에, 작은 보호구업체의 성공을 전망한 이는 아무도 없었다. 그러나 약 40여 년의 세월이 지난 지금, 성안세이브는 국내를 넘어 세계시장을 공략하는 보호구업계 선도기업으로 우뚝 섰다. 이처럼 성안세이브가 거침없는 성장가도를 달릴 수 있었던 비결은 무엇일까. 이에 대한 해답을 찾기 위해 사업장을 직접 찾아가 봤다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.4
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• pp.307-316
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• 2008

The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fin-tube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ${\pm}$10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at $3^{\circ}C$ & 80% is increased 40% than that of $-3^{\circ}C$ & 80%, and the frost thickness at $3^{\circ}C$ & 90% is increased 30% than that of $3^{\circ}C$ & 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.8 no.2
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• pp.48-54
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• 2012

To analyze the cooling performance of fin-tube evaporator in the refrigerator truck using R744 according to frost growth, the analytical model of evaporator was developed under frost and non-frost conditions. The performance of fin-tube evaporator was investigated with frost thickness and indoor temperature. Besides, the performance of evaporator under frost condition was compared to that under non-frost condition. As a result, area of air passage and system performance were decreased as the frost thickness increased. The cooling capacity was reduced by 10%, 20%, 30% when the frost thickness was 0.7 mm, 1.1 mm, and 1.6 mm respectively. At these conditions, the block ratio was 31%, 48%, and 71%. In addition, the outlet quality of refrigerant was not over 1 when the frost thickness was 1.6 mm in spite of high indoor air temperature.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1575-1579
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• 2010

본 연구에서는 우리나라 6개 지점(강릉, 서울, 인천, 대구, 부산, 목포)에서 관측한 약 100년간(1912-2009년, 단 1950-1953년 제외)의 일최고/최저기온 및 일강수 자료를 이용하여 각 지점별로 다양한 기후지수를 산출하고 이들의 변화를 살펴보았다. 기온 관련 기후지수로는 여름일수, 영하일수, 결빙일수, 서리일수, 열대야일수, 냉방도일, 난방도일, 일교차, 식물성장일수, 일최고/최저기온의 월최고값 및 월최저값 등을 분석하였으며, 강수 관련 기후지수로 강수량, 강수일수, 강수강도, 호우일수, 미우일수, 최고 일강수 및 5일 연속 최고 강수량, 연속건조일수 및 연속습윤일수, 극한 강수일의 강수량 등을 계산하였다. 다음은 6개 지점의 기후지수를 평균한 결과이다. 6개 지점 모두에서 최저기온의 상승률이 최고기온의 상승률보다 크게 나타남에 따라 분석기간 동안 일교차는 점차 줄어드는 경향($-0.12^{\circ}C$/10년)을 보였고, 최저기온에 근거한 기후지수인 서리일수 (최저기온이 $-5^{\circ}C$ 미만, -2.6일/10년), 영하일수(최고기온이 $0^{\circ}C$ 미만, -1.0일/10년) 등의 감소와 평균기온의 상승에 따른 성장계절길이(growing season length)의 증가(+3.53일/10년)가 뚜렷하게 나타났다. 일강수와 관련된 주요변화로 미우일수(일강수량이 1 $mmday^{-1}$ 이하)는 감소(-0.75일/10년)했지만, 10 $mmday^{-1}$ (+0.32일/10년), 20 $mmday^{-1}$ (+0.27일/10년), 30 $mmday^{-1}$ (+0.25일/10년), 50 $mmday^{-1}$ (+0.17일/10년), 80 $mmday^{-1}$(+0.09일/10년) 이상 내린 강수일수는 증가하였다. 강수강도(강수량이 1 $mmday^{-1}$ 이상일 때의 강수량과 강수일수 기준)는 0.23 $mmday^{-1}$/10년로 증가했다.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.346-352
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• 2016

To investigate the oviposition preference and development of azuki bean weevil (Callosobruchus chinensis L.), the following six different leguminous seeds were used in this study: red bean (Vigna angularis (Willd.) Ohwi & Ohashi), black soybean (Glycine max (L.) Merr.), soybean (Glycine max (L.) Merr.), seoritae (Glycine max (L.) Merr.), small black bean (Rhynchosia nulubilis) and kidney bean (Phaseolus vulgaris var. humilis Alef.). In the study of oviposition preference, the numbers of eggs per leguminous seed on red bean, black soybean, soybean, seoritae and small black bean were 1.23, 0.61, 0.69, 1.05 and 1.13, respectively. The maximum daily number of eggs was observed at 48 hours and the minimum was at 96 hours. According to each host leguminous seed, developmental time for each host seed was different. The shortest adult emergence time was on red bean (25.27 days). The other five leguminous seeds increased or doubled the adult emergence time. Adult emergence rates feeding on red bean, seoritae, black soybean, soybean, small black bean were 83.33%, 28.23%, 27.87%, 20.44%, and 11.59%, respectively. Emergence rate on red bean was four times higher than the rate on other seeds. The longevity of emerged female adults was almost all longer than that of males. The male adults weighed the lowest of feeding on small black bean. Female adults weighed the lowest of feeding on soybean. Adult weights were the heaviest for both males and females feeding on red bean. As a result, hosts of azuki bean weevil could decrease oviposition rate, emergence rate, adult longevity, and adult weight but increase emergence time. Especially in kidney bean, adult was not completely emerged. No eggs were laid. These results suggest that there might be emergence inhibitors in kidney bean. These imformation might be used to control damages caused by azuki bean weevils.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.1
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• pp.31-36
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• 2023

The number of people living with a pets is increasing. The size of related industries are expanding. There is an increasing demand for various designs, functions, and materials for pet accessories. Therefore, this study proposes the development of a pet jewelry design using a phosphorescent pigment. The phosphorescent pigments have an advantage of emitting light by themselves even in dark places. The final design was derived by manufacturing this as a gemstone cutting-type resin and applying it to the development of jewelry design for pets.