• Steel and Composite Structures
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• 제14권3호
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• pp.205-227
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• 2013

Current design standards do not provide adequate guidelines for the fire design of cold-formed steel compression members subject to flexural-torsional buckling. Eurocode 3 Part 1.2 (2005) recommends the same fire design guidelines for both hot-rolled and cold-formed steel compression members subject to flexural-torsional buckling although considerable behavioural differences exist between cold-formed and hot-rolled steel members. Past research has recommended the use of ambient temperature cold-formed steel design rules for the fire design of cold-formed steel compression members provided appropriately reduced mechanical properties are used at elevated temperatures. To assess the accuracy of flexural-torsional buckling design rules in both ambient temperature cold-formed steel design and fire design standards, an experimental study of slender cold-formed steel compression members was undertaken at both ambient and elevated temperatures. This paper presents the details of this experimental study, its results, and their comparison with the predictions from the current design rules. It was found that the current ambient temperature design rules are conservative while the fire design rules are overly conservative. Suitable recommendations have been made in relation to the currently available design rules for flexural-torsional buckling including methods of improvement. Most importantly, this paper has addressed the lack of experimental results for slender cold-formed steel columns at elevated temperatures.

• 한국전기전자재료학회논문지
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• 제22권12호
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• pp.1078-1083
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• 2009

Generally Lighting system consists of lamp and luminaire. When a fluorescent lamp is installed in luminaire, power and light output is changed by ambient temperature. Particularly electrodeless lamp depends on the changes that are mercury pressure with amalgam temperature and magnetic properties with ferrite temperature. It has finally influence on optical efficiency. In this study, the temperature change of ferrite and cold spot, vessel are measured at transitional state and then same characteristics are measured with increase of ambient temperature. At transitional state, luminous flux is related to temperature change of cold spot that compare with behavior of mercury pressure and light output. At increase of ambient temperature, we analyzed change that efficiency and electrical, optical characteristics of elecrodeless lamp are related to ferrite core and cold spot temperature.

• 전기학회논문지
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• 제57권5호
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• pp.833-838
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• 2008

Generally Lighting system consists of lamp and luminaire. When a fluorescent lamp is installed in luminaire, power and light output is changed by ambient temperature. Particularly electrodeless lamp depends on the changes that are mercury pressure with amalgam temperature and magnetic properties with ferrite temperature. It has finally influence on optical efficiency. In this study, the temperature change of ferrite and cold spot, vessel are measured at transitional state and then same characteristics are measured with increase of ambient temperature. At transitional state, luminous flux is related to temperature change of cold spot that compare with behavior of mercury pressure and light output. At increase of ambient temperature, we analyzed change that efficiency and electrical, optical characteristics of elecrodeless lamp are related to ferrite core and cold spot temperature. Additionally, spectrum, color temperature and coordination are measured to check that is relation with ambient temperature.

• 한국자동차공학회논문집
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• 제23권4호
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• pp.428-435
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• 2015

This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is $3.1-4.2^{\circ}C$ lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 춘계학술대회 논문집
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• pp.65-69
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• 2009

Generally Lighting system consists of lamp and luminaire. When a fluorescent lamp is installed in luminaire, power and light output is changed by ambient temperature. Particularly electrodeless lamp depends on the changes that are mercury pressure with amalgam temperature and magnetic properties with ferrite temperature. It has finally influence on optical efficiency. In this study, the temperature change of ferrite and cold spot, vessel are measured at transitional state and then same characteristics are measured with increase of ambient temperature. At transitional state, luminous flux is related to temperature change of cold spot that compare with behavior of mercury pressure and light output. At increase of ambient temperature, we analyzed change that efficiency and electrical, optical characteristics of electrodeless lamp are related to ferrite core and cold spot temperature.

• 한국포장학회지
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• 제23권1호
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• pp.27-36
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• 2017

오리엔탈 나리 '시베리아'의 건식저장 기간에 따른 절화 보존 시 수분함량 변화와 절화수명을 구명하고자 하였다. 본 실험에서 저장 기간에 따라 저온 저장($5^{\circ}C$)을 한 다음 절화수명에 관계된 수분 및 품질 변화와 개화 정도를 검토하여 '시베리아' 나리의 절화 수확 후 관리 기술에 관계된 기본적인 자료를 얻고자 하였다. '시베리아' 나리를 채화하여 저온에서 건식저장 기간에 따라 3일, 6일, 12일한 후 절화보존 동안에 생체중 변화, 수분균형, 개화정도 등을 조사하였으며 대조구로서 상온 건식저장과 비교하였다. 저온 건식저장 후에 '시베리아' 나리의 수분함량은 건식저장 기간에 영향을 받아 저장하는 기간이 짧을수록 높아져 저장 3일이 다른 처리구보다 높아지는 경향을 보였다. 꽃의 수분함량은 절화보존 시 지속적으로 증가하는데, 저장 기간이 짧을수록 수분이 높게 유지되었다. 생체중 변화는 건식저장 기간에 영향을 받아 저장 기간이 짧았던 것에서 생체중의 증가 정도가 컸으며 음(-)의 값에 이르는 기간이 늦어지는 것으로 나타났다. 또한 절화보존 시 생체중 변화는 저온 건식저장 3일이 생체중 증가 정도가 완만하게 변하며 수분균형도 8일째에 음(-)의 값에 도달하는 것으로 나타났다. 그러나 저장 온도 차이에 따른 생체중 변화는 상온에서 저장한 절화가 저온저장보다 증감 정도가 더 빠른 것으로 나타났다. 개화정도는 '시베리아' 나리의 건식저장 기간이 길어질수록 개화시기가 빨라지며, 절화가 빨리 시들어 상품으로써 유지 기간이 짧아졌다. 개화상태를 비교해 보면 3일 저온 건식저장이 다른 처리보다 개화하는 속도가 늦었으나 절화수명은 다른 처리구보다 길게 나타났다. '시베리아' 나리의 저온 건식저장은 저장 기간이 짧을수록 저장 후 수분함량이 높고 수분 균형값이 음(-)에 늦게 도달하였으며 개화상태가 좋고 절화수명도 길어지는 것으로 나타났다. '시베리아' 나리는 건식저장을 통한 작물체내 수분 함량 감소가 절화보존 시 개화 특성에도 영향을 미쳐 저장기간이 길수록 절화수명이 감소하여 상품 가치를 떨어뜨렸다. '시베리아' 나리 절화를 소비자가 이용 시, 상품 가치 유지를 위해서는 기존 결과의 6일 동안 저온 건식저장도 절화수명을 단축시키므로 저장 기간을 최소화하는 것이 절화 품질 유지를 위해 바람직하다고 판단된다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.646-648
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• 2003

The electrical and optical characteristics of the cold cathode fluorescent lamps (CCFL) were measured and investigated under the wide ambient temperatures ranging from $-30^{\circ}C$ up to $+100^{\circ}C$. The highest luminous efficiency of the CCFL of 55 lm/W was obtained at the ambient temperature of $50^{\circ}C$.

• Journal of Biosystems Engineering
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• 제37권3호
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• pp.184-191
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• 2012

Purpose: This study was conducted to investigate the storage and quality characteristics of brown rice under the low temperature warehouse conditions using ambient cold air in the winter. Methods: This new technique maintains rough rice warehouse temperature below $15^{\circ}C$ without cooling operation until the end of May. Four hundred tons of rough rice were stored in the low temperature grain warehouse, and were aerated from the top to the bottom using ambient cold air in February. The quality of rough rice was evaluated from February through October. Results: The results were as followings. Moisture contents of rough rice in the low temperature storage had decreased less than the ordinary temperature storage. Cracked rate of brown rice in the ordinary temperature storage and low temperature storage increased by 4~10.8% and 1.6~7.2%, respectively. The germination rate of rough rice under the ordinary and the low temperature warehouse decreased by 15.0~25.0% and 1.7~8.0%, respectively. The acid value of brown rice under the ordinary and the low temperature warehouse increased by 3.67~6.72 KOH mg/100g and 3.08~4.08 KOH mg/100g, respectively. Conclusions: The result indicates that low temperature storage using ambient winter air showed better maintaining germination of rice, less change of physiological activities and cracked kernel, and better maintaining of rice quality, comparing the ordinary temperature storage.

• 원예과학기술지
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• 제34권6호
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• pp.807-817
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• 2016

Many onion growers and researchers assert that differences in soil type, agricultural practices, weather, and duration of prolonged onion cultivation in a particular field could affect onion bulb quality. This study evaluates the bulb quality of onions grown in different regions and determines the correlations between bulb characteristics and postharvest loss during cold and ambient storage. Soil and onion bulbs were collected from fields in six onion growing regions in Korea, during the growing season of 2011-2012. The fresh weight, dry matter content, and carbon (C), sulfur and magnesium contents of the onion bulbs were significantly affected by the location in which they were grown. Bulbs grown in Muan had the greatest number of scales, thinnest scale thickness, and the highest total soluble solids (TSS) and total flavonoids (TF). Bulbs originating from Jecheon had the lowest pyruvic acid (PA), total phenolics and TF. Storage loss of bulbs from the different regions was similar in refrigerated storage, but differed in ambient temperature storage. Bulb fresh weight was positively correlated with scale thickness (r = 0.617) and cold storage loss (CSL; r = 0.398). Dry matter content was positively correlated with C (r = 0.958) and TF (r = 0.256) contents, while it was negatively correlated with CSL (r = -0.424). CSL was primarily affected by the fresh weight, as well as the dry matter, C, and PA contents of the bulbs, while ambient storage loss was primarily influenced by the amount of TSS.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.517-522
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• 2005

A cold storage refrigerator using phase change material(PCM) has been developed and its performance test results are provided here. The inner temperature of the refrigerator is controlled with forced convection driven by a fan using a DC battery. At the first, to freeze all the PCM of the ambient temperature by a built-in refrigerating machine, it took about 8 and 10 hours respectively at the refrigerator and the freezer mode. Then, without external power supply, the inner temperature of the cold storage refrigerator has been maintained at $-18{\pm}1^{\circ}C$ during 14 hours at the freezer mode and maintained at $3{\pm}^{\circ}C$ during 34 hours at the refrigerator mode. Just after the end of its valid usage as a refrigerator or a freezer, it took about 6 hours to refreeze the PCM for its reuse. During the test, the ambient temperature was kept at $30^{\circ}C$.