• 대기
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• 제30권3호
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• pp.249-256
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• 2020

We investigate regional differences in the characteristics of cold surges that occurred over the South Korea during winter season (December-February, 1981/1982~2017/2018). A significant regional contrast of cold surge characteristics exists and we found that this is closely related to the spatially inhomogeneous distribution of winter-mean climatological surface temperature in association with the complex topography of the Korean peninsula. For the regions of the temperature below -1℃ (Region1; R1), the frequency of cold surges is inversely proportional to the surface temperature almost linearly. In case of the regions above -1℃ (Region2; R2), cold surge frequency does not exhibit any clear dependency on the surface temperature. Duration and number of occurrences of cold surge between the two regions showed clear difference. Dynamical evolution of cold surges before the onset showed a sharp contrast between R1 and R2. In R1, cold surface air temperature (SAT) was already predominant over East-Asia before the onset and the cold temperature was sustained after the occurrence. On the contrary, warm SAT was predominant over East-Asia before the onset in R2. The SAT suddenly drops just after the cold surge occurrence. We present different origin of wave activity and propagation characteristics between the two types: Wave-activity flux (WAF) was relatively weaker and wave disturbances moved eastward in R1 along with the WAF mainly directing eastward. In case of R2, WAF was stronger and directing southeastward in the upstream of South Korea movement erasing predominant warmer air eventually causing sudden temperature drops over southern provinces over South Korea.

• 대한임상전기생리학회지
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• 제5권2호
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• pp.61-72
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• 2007

INTRODUCTION: Local heat and cold application has been frequently used as means of muscle relaxation and blood circulation or reinforcing muscle strength, relaxing muscle tension in clinical situation. In particular, it has been known that long-term heat and cold application for relaxing muscle tension inhibits muscle spasticity or tension. But, it has been rarely reported that what influences of heat and cold application on activation of muscle action potential. Therefore, this study aims to analyze surface temperature and electromyography activities according to the heat and cold application. METHODE: Subjects of this research were 10 normal men and women (5 men, 5 women). Hot pack and cold pack was applied to vastus medialis muscle of thigh and rectus femoris muscle for 20 min. Surface temperature of vastus medialis muscle and rectus femoris muscle was measured, knee joint of subjects was in $45^{\circ}$ flexion, sitting on a chair, maximal isometric contraction was induced, surface electromyography (sEMG) signals were collected and root mean square (RMS) and median frequency (MOF) were analyzed. All measurements were conducted before and immediately after experiment, 10 min., 20 min. and 30 min. after experiment. Data were analyzed with SPSS 12.0 program, comparison of changes in superficial temperature and sEMG signals through repeated measurement was conducted with repeated measures ANOVA and significance level $\alpha$ was 0.05. RESULTS: Changes of surface temperature of vastus medialis muscle according to cold application were radically decreased immediately after application, but it was recovered after 30 min. of application and it showed significant difference (F4. 36=72.216, P<0.001). Surface temperature of rectus femoris also showed radical decrease immediately after application, but it was recovered after 30 min. of application and showed significant difference (F4. 36=88.930, P<0.001). Changes of surface temperature of vastus medialis muscle according to heat application were radically increased immediately after application, but it was recovered after 30 min. of application and it showed significant difference (F4. 36=27.267, P<0.001). Surface temperature of rectus femoris also showed radical decrease immediately after application, but it was recovered after 30 min. of application and showed significant difference (F4. 36=19.774, P<0.001). Changes of sEMG by heat and cold application were no statistical difference. Surface temperature of skeletal muscle after heat and cold application showed significant change for 30 min., but it was found that increase or decrease of surface temperature had not great influence on sEMG activities.

• 대기
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• 제28권4호
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• pp.383-392
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• 2018

This study investigates synoptic characteristics of cold surges over South Korea during winter season (December-February). A total of 63 cold events are selected by quantile regression analysis using daily mean temperature observations from 11 KMA stations for 38 years (1979/80-2016/17). Large-scale pressure pattern during the cold surges is well characterized by high over Siberia and low over Aleutian regions, which elucidates cold advection over the Korean peninsula. However, the large-scale pattern cannot successfully explain the observed sudden decrease of temperature during the cold surges. Composite analyses reveal that a synoptic-scale cyclone developing over the northern Japan is a key feature that significantly contribute to the enhancement of cold advection by increasing pressure gradient over the Korean peninsula. Enhanced sensible and latent heat fluxes are observed over the southern ocean of Korea and Japan during the cold surges due to temperature and humidity differences between the near surface and the lower atmosphere over the ocean. The evaporated water vapor transported toward the center of the surface cyclone and condenses in the lower-to-middle troposphere. The released energy likely promotes the development of the surface cyclone by inducing positive PV near the surface of the heating region.

• 대한공간정보학회지
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• 제23권4호
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• pp.11-16
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• 2015

시공간적 기온정보는 지구온난화와 기후변화의 이해에 있어서 중요한 기상요소이다. 본 연구에서는 인공위성 원격탐사로부터 획득된 공간적으로 균질한 지표면 정보를 이용하여 우리나라 지상기온 평가 알고리즘을 개발하였다. LST(Land Surface Temperature), NDWI(Normalized Difference Water Index), NDVI(Normalized Difference Vegetation Index)를 독립변수로 하는 지상기온 추정을 위한 다중회귀모형을 제안하고, 우리나라의 지역기후변화를 고려하기 위하여 온난시즌과 한랭시즌에 대한 모형의 회귀상수 및 회귀계수를 도출하였다. 개발된 기온 추정 알고리즘에 의해 산출된 온난 및 한랭시즌의 기온정보는 지상관측기온과 비교하여 우수한 상관관계를 보였고, $3^{\circ}C$ 미만의 RMSE와 거의 0에 가까운 BIAS로 매우 높은 일치성을 보였다. 따라서 인공위성 지표면 원격탐사자료를 활용하고 온난 및 한랭시즌의 구분을 적용한 기온 평가 알고리즘은 우리나라의 지역기후를 평가하는데 있어서 간략하고 유용한 수단이 될 수 있으리라 기대된다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.19-22
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• 2003

The purpose of this study is to analyze the curing effect of planar surface heater for concreting in cold weather. Some experiments were conducted to evaluate the temperature history of concrete structures cured with heating sheets. Results are as follows ; (1) The temperature of concrete showed continuously rising trend with the heating by planar surface heater under the cold environmental condition of 3~-12$^{\circ}C$. And after about 24 hours the maximum temperature of concrete was reached at 25~3$0^{\circ}C$. (2) The temperature of slab concrete heated by planar surface heater of 130W/$m^2$ was at least $25^{\circ}C$ higher than that of an exterior air, and the curing performance was much more effective than heating by hot wind machine. (3) Through the curing by planar surface heater for 48 hours, the concrete maturity of about 1.5 times to heating by hot wind machine was acquired.

• Journal of Forest and Environmental Science
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• 제35권4호
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• pp.232-239
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• 2019

This study was carried out to establish an efficient selection condition for cold-tolerant individuals among evergreen Quercus spp. To select higher cold-tolerant individuals among four species of evergreen Quercus spp. (Q. acuta, Q. glauca, Q. myrsinaefoila, and Q. salicina), an-year-old seedlings of each species were exposed to low temperature in serial, and then examined for the death of cell tissue and the surface temperature was monitored. It was shown that the higher numbers of seedlings of Q. myrsinaefolia were survived than the others when those seedlings are exposed to cold stress. Thus, selection of the cold tolerant individuals was conducted on Q. myrsinaefolia seedlings. The limit low temperature condition for selecting cold-tolerant individuals was -6℃ for 24 hrs because no seedling of Q. myrsinaefolia was survived after exposed to -7℃ for 24 hours. It was shown that the leaf surface temperature of the selected individuals was higher than those of the non-selected individuals when they were exposed to cold-stress while monitoring them using thermal graphic camera. The results in this study can be used for expanding afforestation area of tree species of the warm temperate zone for preparation of climate change.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.7-11
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• 2003

This study investigate the hydration heat history with variation of surface insulating material in cold weather concreting. According to the results, the temperature of concrete lowers below zero in 24hours, so early frost damage occurs in the case of exposure and 1 fold bubble sheet, but the lowest temperature keeps above zero, so a adiabatic effect is very favorable in the case of double bubble sheet and 부직포. Compressive strength of core specimen at 7 and 28 days is highest In the case of double bubble sheet and 부직포. But, considering convenience of construction and economical efficiency, it is thought that the most effective surface insulating material is 1 fold bubble sheet +blanket.

• 한국안전학회지
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• 제14권1호
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• pp.3-9
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• 1999

The vortex tube is a simple device which splits a compressed gas stream into a cold stream and a hot stream without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air supply system. In this study, the insulation effect of surface on the efficiency of vortex tube was performed experimentally. The experiment is carried out for nozzle area ratio of 0.194, diameter ratio of cold end orifice of 0.6 and input pressure ranging from 0.2Mpa to 0.5Mpa. The purpose of this study is focused on the effect of surface insulation of vortex tube with the variation of cold air mass flow ratio. The results indicate that the temperature difference of cold and hot air are higher about 12% and 30% than that of not insulated vortex tube respectively. Furthermore, for the insulated vortex tube, the similarity relation for the prediction of cold end temperature as the function of cold air mass flow ratio and input pressure is obtained.

• 해양환경안전학회지
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• 제22권3호
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• pp.286-295
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• 2016

With the results of observations in 2013 and 2014 including ocean buoys, in-situ investigations and wind data, we examined the spatio-temporal variation of cold water masses along the eastern coast of Korea. Usually, a cold water mass first appears along the northern part of the eastern coast from May to July, and then along the southern part of the eastern coast from late June to mid-August. Cold water masses appear 3~5 times a year and remain for 5~20 days in the southwestern part of the East Sea. A distinctive cold water mass appeared usually in mid-July in this area, the surface temperature of which was below $10^{\circ}C$ in some cases. During the appearance of a cold water mass in the southwestern part of the East Sea, the horizontal temperature gradient was large at the surface and a significant low water temperature below $8^{\circ}C$ appeared at the bottom level. This appearance of cold water masses clearly corresponded to southwesterly winds, which generated coastal upwelling.

• 한국지리정보학회지
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• 제23권3호
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• pp.263-274
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• 2020

한국 남동해역은 매년 하계에 집중적으로 냉수대가 형성되어 빈번한 이상해황이 발생한다. 본 연구에서는 이 해역에서 발생하는 표층수온 분포의 공간 변화를 분석하기 위해 2018년 6월에서 9월까지 고리와 정자 부이에서 관측한 해양현장 수온 데이터와 GHRSST Level 4 재분석 해수면 온도(sea surface temperature: SST) 자료를 이용하였다. 부이 자료는 두 지점의 시계열적 수온 변동 분석에, GHRSST 자료는 연구해역 전반에 걸친 일별 SST의 분산과 가중공간중심(weighted mean center: WMC)을 계산하는데 이용하였다. 부이의 수온이 낮아지면 연구해역 SST의 분산이 증가하는 경향을 보였으나, 전 기간 일치하게 나타나지는 않았다. 이는 GHRSST가 재분석 자료로 연안의 민감한 수온변화를 반영하지 못하기 때문이다. 이와 같이 전 해역의 SST 변화를 대표하는 통계적 분산만으로는 연안의 국지적인 소규모의 수온변화를 파악하거나, 냉수대 발생해역의 위치 및 범위를 탐지하기에는 한계가 있다. 따라서 차가운 수괴가 발생하는 공간적인 위치를 정량적으로 파악하기 위해 WMC를 활용하여 분석한 결과 냉수대가 발생했을 때, WMC가 연구해역의 공간중심(mean center: MC)으로부터 북서 해역 쪽에 위치하였다. 이는 SST의 WMC 위치 정보를 통해 차가운 표층수온의 분포가 어디에서 어느 정도 나타나는지를 정량적으로 파악할 수 있음을 의미하며, 향후 냉수대 규모 및 지역 확산 범위 탐지에 WMC의 활용 가능성을 알 수 있었다.