• 한국태양에너지학회 논문집
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• 제33권3호
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• pp.36-41
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• 2013

The reflection plate in twin-glass evacuated tube solar collector is controlled to reduce the overheat during the summer time. The sliding type and folding types are suggested and tested. The sliding type changes the plate angle and the folding type changes the opening angle of the reflection plate. By scattering the focus of the reflected radiation from the reflection plate, the temperature rise of the working fluid can be reduced. The sliding type shows the best results in overheat reduction. When solar radiation is 900 $W/m^2$, the temperature rise in one sliding type collector is reduced about $2^{\circ}C$ compared to that of the normal solar collector. When this method is applied to seven series-collectors in the field, the reduction of temperature rise during the summer time should be significant.

• 대기
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• 제29권5호
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• pp.627-637
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• 2019

Severe and long-lasting heat waves over Korea and many regions in the Northern Hemisphere (NH) during the 2016 summer, have been attributed to global warming and atmospheric teleconnection coupled with tropical convective activities. Yet, what controls subseasonsal time scale of heat wave has not been well addressed. Here we show a critical role of two dominant boreal summer intraseasonal oscillation (BSISO) modes, denominated as BSISO1 and BSISO2, on modulating temporal structure of heat waves in the midst of similar climate background. The 2016 summer was characterized by La Nina development following decay of strong 2015/2016 El Nino. The NH circumglobal teleconnection pattern (CGT) and associated high temperature anomalies and heat waves were largely driven by convective activity over northwest India and Pakistan during summer associated with La Nina development. However, the heat wave event in Korea from late July to late August was accompanied by the phase 7~8 of 30~60-day BSISO1 characterized by convective activity over the South China Sea and Western North Pacific and anticyclonic circulation (AC) anomaly over East Asia. Although the 2010 summer had very similar climate anomalies as the 2016 summer with La Nina development and CGT, short-lasting but frequent heat waves were occurred during August associated with the phase 1~2 of 10~30-day BSISO2 characterized by convective activity over the Philippine and South China Sea and AC anomaly over East Asia. This study has an implication on importance of BSISO for better understanding mechanism and temporal structure of heat waves in Korea.

• 한국환경과학회지
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• 제20권11호
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• pp.1425-1435
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• 2011

Time-series change in Gyeongpo beach shoreline was illustrated using DGPS(Differential Global Positioning System, resolution < 0.6m) observation from April, 2009 to April, 2010. The shoreline was subdivided into 12 areas, and westward and eastward movement of shoreline position at each area was calculated. In general, the shoreline moved toward sea during summer, and it moved toward land during winter. The southern and northern part of the shoreline had different pattern in time-series. The shoreline in the southern part moved toward sea during summer and moved toward land during winter, but time-series pattern of the shoreline in the northern part was more complicated than that in the southern part. Pattern of time-series change in the northern part was made up of three different types; the first is that the shoreline moves continuously toward land, and the second thing is that the shoreline's movement is the opposite to the southern part, and the third thing is that the shoreline maintains a state of equilibrium without any great fluctuation. The total length of the shoreline was the largest during winter and the smallest during summer. In general, time-series change in the shoreline had positive(+) relationship with sea surface pressure and wind speed.

• 한국초지조사료학회지
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• 제10권2호
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• pp.89-95
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• 1990

This experiment was carried out to determine the effects of nitrogen(N) fertilizer levels (0, 120, 240 and 360kg $ha^{-1}Y^{-1}$ Y-') on seasonal grass growth, dry matter (DM) yield and botanical composition in pasture under shade condition. Investigation date was on 7 , 14, 21, 28 and 35 days after harvesting in spring (May), summer (July) and autumn (Sept.), 1988, respectively. Shade degree was controlled artificially ca. 45-50%, and each annual level of N was distributed 5 times equally. Grass growth and DM productivity were most vigorous in spring. Higher DM yield was produced with N 240 kg spring, and Nl2Okg in summer and autumn. Higher significant relationships, in spring, were found between grass height and DM, and N level and DM yield. However, low relationships were observed between those in summer and autumn. In botanical composition, grass coverage was decreased in summer and autumn, and bareland was increased, especially in higher N plots. Based on the results, it is suggested that 200kg $ha^{-1}$ of N in this experiment is more effective for forage production and pasture persistence. Also a littie more amount of N (50-70kg $time^{-1}$) in spring, and low level of N (20-30kg $time^{-1}$) in summer and autumn may be desirable.

• Asian-Australasian Journal of Animal Sciences
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• 제11권6호
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• pp.739-745
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• 1998

Sixteen periparturient Holstein cows calving during summer and autumn were fed to meet maintenance plus last 2 month of gestation level of TDN (MP) and 1.2 time of MP level (HMP). Dry matter intake of cows fed at HMP level during summer and autumn decreased by 1 and 2% of the offered feed in 1 week prepartum, respectively, and cows fed at MP level consumed all of the offered feed. Rectal temperatures at 08 : 30 h of cows fed at HMP level were higher than those of cows fed at MP level. Blood hematocrit and hemoglobin of cows increased during summer and were higher for cows fed at HMP level. Plasma total protein and glucose of cows during summer were higher than those during autumn, and the increased feed intake elevated plasma total protein and glucose. Plasma urea-N of cows fed at MP level was higher than that of cows fed at HMP level during autumn. The increased feed intake decreased plasma nonesterified fatty acid of cows during summer and autumn. These results suggest that blood components of periparturient cows are altered by calving season and feeding level.

• 한국지역사회생활과학회지
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• 제14권3호
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• pp.13-19
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• 2003

The purpose of this study was to investigate the UVA radiation protection effects of summer hats currently on the market with the purpose of making it possible to choose a hat with suitable UVA protection. Twelve different summer hats from the market were selected for the experiment. The results are summarized as follows: It is more effective to wear a hat than not wear a hat to block UVA radiation. Summer hats with the greatest degree of protection, from highest to lowest, are cotton, straw2, and straw1. In the area of the forehead, which is rarely influenced by the irradiation angle, the cotton hat was the most effective in protecting from UVA radiation because the material density was greater than that of the straw hats. A hat with a 8.5 cm brim was more effective at blocking UVA radiation on the jaw than 6 cm, 4 cm, and 0 cm wide brims, but it still couldn't block the radiation completely. Irradiation amounts at 11:00 AM on the forehead, jaw! s and left and right cheeks were lower than amounts measured on the back of the neck. This revealed that irradiation amounts depend on the shape of the hat and time of day. A hat with a brim encircling the head was found to be more effective in blocking UVA radiation than a hat with only a front or side brim.

• 대한지역사회영양학회지
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• 제12권2호
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• pp.142-149
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• 2007

To evaluate the seasonal differences of nutrient intake and serum biochemical indices (total cholesterol, HDL-, LDL- cholesterol, TG, MDA : malondialdehyde, TAS : total antioxidant status, folate) in Korean college women with a mean age of 20.15y, this study was conducted twice: once in winter and a second time in summer. Anthropometric assessment was also measured in the two seasons. As a result body fat mass (p<0.05), body fat% (p<0.05), and abdominal fat% (p < 0.01) in the summer were significantly lower than those in winter. Intake of fat (p < 0.05), polyunsaturated fatty acid (p < 0.01), zinc (p < 0.05), and vitamin E (p < 0.05) were at significantly higher levels in the summer period compared with the winter period. In addition, nutrients with an intake level less than 75% RI of KDRIs were folate in winter and calcium, and folate in the summer. Total cholesterol (p < 0.05) and HDL-cholesterol in summer, according to lipid profiles, were significantly lower than those in winter. Although MDA, one of the products of lipid peroxidation, remained unchanged, TAS was significantly higher in summer than in winter. The level of folate in summer showed significantly lower than that in winter. The present study suggests that nutrient intake of college women women differs according to the seasons and anthropometric indices and serum biochemical indexes were associated with seasons. Thus nutritional education programs on the basis of season are needed for college women.

• 한국발생생물학회지:발생과생식
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• 제17권2호
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• pp.111-119
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• 2013

Golden hamsters reproduce in a limited time of a year. Their sexual activities are active in summer but inactive in winter during which day length does not exceed night time and environmental conditions are severe to them. The reproductive activities are determined by the length of light in a day (photoperiod). Melatonin is synthesized and secreted only at night time from the pineal gland. Duration of elevated melatonin is longer in winter than summer, resulting in gonadal regression. The present study aimed at the influences of continuous melatonin treatments impinging on the gonadal function in male golden hamsters. Animals received empty or melatonin-filled capsules for 10 weeks. They were divided into long photoperiod (LP) and short photoperiod (SP). All the animals maintained in LP (either empty or melatonin-filled capsules) showed large testes, implying that melatonin had no effects on testicular functions. Animals housed in SP displayed completely regressed testes. But animals kept in SP and implanted with melatonin capsules exhibited blockage of full regression by SP. These results suggest that constant release of melatonin prohibits the regressing influence of SP.

• 교육시설
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• 제2권3호
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• pp.31-38
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• 1995

The paper is to evaluate existing school building system with respect to students' comforts in the class room in Korea. This paper compared three styles of different school building system builted during last 20 years. Using statistical analysis, at first, the paper found that box-style structure is efficient for sustaining heat in the class room because it is compactly constructed. Secondly, air conditioning in the class room is important factor affected students' comforts in the summer time and for the smog occurring in the heating class room. Thirdly, we should compactly construct school building because the compactiveness of building components is important factor for student comforts. Fouthly, heating system in the class room should be changed. The system using gas or electricity insteded of coals should be introduced in the class room for the smog of the stove in winter time and for freshness in summer time.

• 건축사
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• 통권592호
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• pp.116-121
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• 2018