• Journal of Korean Society for Atmospheric Environment
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• v.29 no.6
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• pp.734-744
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• 2013

In this study, the telematics device was installed on the car (OBD-II) to collect the information on the operation conditions from each sample vehicle. Based on the information the domestic driving pattern was analysed and the ratio of cold start length was estimated. As a result of analysis for driving pattern, we found a difference in the frequency of driving on the hourly or seasonal basis. Then, the driving pattern of the rush hours, weekdays, and weekends could be derived. Also, from the study, an average of 2.22 times per day occurred in a single trip and average driving distance for the trip was 15.72 km. In addition, the proportion of cold start length was analyzed to be 16.11%. The seasonal cold start length has big difference from season to season (Winter 26.63%, Summer 8.22%, Intermediate 12.65%). There was an inverse relationship between the outside temperature and ratio of cold start length. In order to improve the accuracy of the cold emission estimation, it is necessary to apply domestic ratio of cold start length that driving pattern and temperature in Korea is reflected.

• Journal of the Korean Solar Energy Society
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• v.32 no.6
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• pp.141-148
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• 2012

Ceiling cassette type air conditioner has been a main stream as a heating/cooling system recently in school, Korea. In this study, indoor thermal environments made by ceiling cassette type air conditioner were investigated by CFD simulation. Concentrations of $CO_2$ were investigated by a field measurement. Indoor thermal environment with the velocity inlet angle of $45^{\circ}$ from the ceiling in heating season was very ununiform so that thermal area was divided into two parts those the one is window side which is cold, and the other is corridor side which is hot. In cooling season under the same condition, there are areas too hot or too cold. If the velocity inlet angle is set in $30^{\circ}$ from the ceiling, indoor thermal environments was improved greatly in cooling season and heating season, too. Also, from the field measurement of $CO_2$ concentrations, it was suggested to install ventilators with proper air volume considered the number of class students.

• Journal of Environmental Science International
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• v.25 no.8
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• pp.1057-1063
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• 2016

The heat budget is investigated in the Gumi Reservoir of the Nakdong river. In warm climate season, solar radiation effects play a important role in the change of water temperature. The features of the surface heat balance are almost derived by the latent heat flux and the solar radiation flux. On the other hand, in cold climate season, change of heat stored in the water is mainly dominated by latent and sensible heat transfer between water and air, since flux of solar radiation and loss of outgoing long wave radiation balance approximately. For the annual averages, net flux of radiation, evaporation(latent heat) loss are dominant in the Gumi reservoir. The evaporation losses are dominant from spring to early winter. This means that the Gumi reservoir rolls like a lake of thermal medium or deep depth.

• Journal of Environmental Science International
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• v.20 no.3
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• pp.309-319
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• 2011

In this study, we investigated the effects of Upo-swamp upon local thermal environment with nighttime cooling rate. To do this, we set up the AWS(Automatic Weather observation System) over the central part of Upo-swamp on the early October 2007. We conducted the study by comparing the AWS data with another weather data observed by several meteorological observations of the Korea Meteorological Administration located at the vicinity of Upo-swamp for one year. The air temperature of Upo-swamp was higher than that of the surrounding in cold-climate season. But it was opposite in warm-climate season. We confirmed that Upo-swamp roles to mitigate the daily and annual air temperature ranges. And the daily air temperature variation of Upo-swamp lagged behind the land one. This phenomenon represent that the heat reservoir capacity of Upo-swamp is much larger than that of the ground.

• Journal of Ecology and Environment
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• v.34 no.3
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• pp.251-257
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• 2011

The purpose of this study was to investigate the acclimation responses of Tamarix chinensis to cold stress. We evaluated the acclimation responses by measuring biomass, daily elongation rate, chlorophyll content, and total soluble carbohydrate content. The plant samples comprised leaves from seedlings of 2 different ages (8 and 12 weeks); the leaves were collected 0, 2, and 4 weeks after cold treatment. We found that the cold-treated samples showed reduced daily elongation rates and chlorophyll content. Further, these samples showed more than 8-fold increase in the total soluble carbohydrate content. However, the seedling ages did not have a significant influence on the growth of cold-treated seedlings. On the basis of these findings, we can conclude that T. chinensis seedlings aged less than 1 year old show acclimation to cold stress by accumulating soluble carbohydrates. This study may help us understand how T. chinensis seedlings acclimatize to their first cold season.

• Horticultural Science & Technology
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• v.29 no.6
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• pp.561-567
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• 2011

Cold tolerance of the native Rhododendron species which are on the verge of extinction in Korean nature were compared with the introduced species and its mechanism were studied physiologically with the investigation of the leaf angle, leaf curling, and photosynthetic activity. The degree of cold tolerance measured with the leaf burning after winter season was higher in the native species, Rhododendron brachycarpum and Rhododendron brachycarpum var. roseum than all the introduced species. 'Nova Zembla', an introduced species, showed high sensitivity to the low temperature. Changes in leaf angle by the low temperature were bigger in 2 native species and 'Parker's Pink' than the other introduced species and small comparatively in 'Nova Zembla' and 'Cunningham's White' cultivar. Leaf curling also occurred strongly in 2 native species by the low temperature. While, it was comparatively little and mild in the other introduced species. Therefore these results suggested that the leaf movement such as leaf angle change and curling adapted to the low temperature is positively related to the cold tolerance of 2 native species. By the way, such relationship is not explainable in the cold-sensitive 'Parker's Pink' cultivar showing comparatively stronger leaf movement. Photosynthetic activity measured before the winter season was high in the cold-tolerant R. brachycarpum and its recovery after winter season was faster in the 2 native species and the introduced 'Cynosure' cultivar than the other introduced species. They were the lowest in the most cold-sensitive 'Nova Zembla'. This phenomena occurred similarly even in the stomatal conductivity, suggesting that the movement of water from the roots to the leaves is better and then the leaf burning after winter season become small in the cold-tolerant species. The recovery of photosynthetic activity and stomatal conductivity was comparatively slower in the cold-sensitive 'Parker's Pink'. From the above results, leaf behavior adapted to the low temperature during the winter season and water movement to the leaves are related collectively to the cold tolerance represented as the leaf burning in the Rhododendron species is suggested.

• Current Research on Agriculture and Life Sciences
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• v.15
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• pp.39-46
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• 1997

In 1996, a cold-water damage occured in the paddy field at the downstream of the Umoon dam. To study the cause and the preventive measures of the cold-water damage a field study was performed during the growing season of 1997. Field measurements such as water temperatures at reservoir, irrigation canal and in the paddy field were made. As a result, there was no cold-water damage due to the right irrigation water management practice in 1997. The cold-water damage is possible to happen, however, and the preventive measures were provided.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.6
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• pp.73-82
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• 2005

This study was performed to evaluate the need for heating wastewater to enhance treatment efficiency of organic matter (BOD, SS) during cold winter in newly developed Absorbent Biofilter System (ABS) which was established in the Suwon Campus of the Seoul National University. Treatments consisted of non-heating (2000 year) and heating(2001, 2002 year), and sampled data were analyzed during cold winter period as well as post winter period to investigate the influence of heating after winter season. Even the average air temperature showed only $0.4^{\circ}C$ difference between two experimental years, the difference in the average effluent temperature during cold winter period between heating and non-heating experiment was approximately $11^{\circ}C$. The average effluent concentration of organic matter in non-heating treatment exceeded the Korean standards for water quality of discharged effluent in riparian area (BOD and SS 10 mg/L); however, the standards were met in case of heating treatment during both winter and post winter period. Therefore, the need fur heating wastewater during cold winter season in ABS was justified. On the other hand, there was no improvement of treatment efficiency in T-N and T-p, but we observed the more activated nitrification as increasing the wastewater temperature. Because the average underground temperature was $5^{\circ}C$ higher than the average air temperature during cold winter period, we recommend that the ABS can be established in the underground rather than on-ground for saving the heating cost.

• Journal of Ecology and Environment
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• v.32 no.3
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• pp.145-148
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• 2009

To understand whether experience of cold season in reproductive behaviors in the adults of Amaurobius ferox, the paired adults of a female and a male were exposed under 'cold-treated environment' and 'not cold-treated environment', respectively. I investigated effects of the cold treatment on the brood production of A. ferox. In not cold treatment in which male-female pairs were formed in October at a temperature of $20^{\circ}C$ (${\pm}2^{\circ}C$) and continuously kept under not cold-treated environment, only 3 of 50 pairs successfully reproduced (reproduction was defined as the emergence of spiderlings). In cold treatment where individuals were kept in cold conditions for 3 months prior to pair formation, 57 out of 60 couples succeeded in reproducing. Females which did not experience the low temperature displayed strong aggressiveness toward males. This behavioral inhibition might the primary barrier to copulation of A. ferox that decrease following a period of low temperature. The reproductive inhibition might help the females to allocate the maximum amount of energy in a given environment to reaching the adult stage and to delay reproduction in unfavorable wintering conditions.

• Atmosphere
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• v.28 no.4
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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.