• Journal of the Korea Institute of Building Construction
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• v.16 no.5
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• pp.413-419
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• 2016

In the cold-weathering concrete construction, it is important to ensure stable strength development of concrete in a low temperature environment. In this study, Non-curing cement(NCC) using the classified high fineness cement and self-heating powder was investigated for stable strength development without curing in a low temperature environment (less than $0^{\circ}C$). The actual size Mock-Up tests by various cement type and curing condition are performed to evaluate the strength development and hydration heat of concrete.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.460-466
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• 2017

The common petroleum can make precipitation such as a wax in a polar region due to severely cold weather condition, which can cause problems to fuel supply system. The petroleum product used in the polar region has thus been manufactured and sold suitable for the cold environment. However it is difficult to supply such petroleum products on time since these were mainly supplied abroad. In this article, the original fuel properties were first analyzed in order to find alternative fuel products for polar region. Jet fuel which is excellent cold characteristics was chosen and the fuel properties was tested by adding a constant concentration of lubricant additives to the jet fuel. As a result, the lubricant additive R621 showed the best lubricity, and adding 1000 mg/L of R621 content to the jet fuel was sufficient to enhance the lubricity. We envision that the jet fuel added 1000 mg/L of R621A can be suitable for alternative special antarctic blend diesel (SAB) in an severe polar environment.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.493-498
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• 1999

Many concrete pavements closed to the end of service life in out country need to repair. We investigated material and mix designs for thin bonded concrete overlay and applied it to concrete pavement rehabilitation. The concrete with Type III cement showed earlier strength and better durability than the concrete with Type I cement. Designed concrete mixture with TypeIII cement made it possible to open the road earlier against heavy vehicles, increased traffic despite of cold weather in winter. In the field examination after four month, there was no defects like as shrinkage crack, spalling, surface abrasion and scaling, and good traffic condition has been maintained.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.11a
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• pp.255-256
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• 2011

This study investigates the effect of a curing condition on the temperature history and strength development of concrete under -10℃. Combination of various curing methods was applied, i.e. a conventional form was combined with compressed insulation, heat panel and heat cable. Results showed that the concrete cured by a single use of a conventional form resulted in serious deterioration of early strength development. However, other concretes cured by the proposed curing methods maintained the temperature of the concretes between 5 and 20℃, and thus resulted in no frost damage.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.131-132
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• 2021

According to the domestic specification, the curing of the specimen for strength management used to determine the time of the mold deformity of the structure concrete in early spring and early autumn is cured in the field structure condition. However, when the seal curing is performed in the field, the temperature of the specimen is very low compared to the temperature of the actual structure, so the strength of the structure concrete predicted based on the strength of the specimen is much undervalued than the actual one, which causes the mold to be deformed. Therefore, this study analyzed the temperature history and compressive strength characteristics of the specimen for strength management through other sealing curing at 5℃ and concrete of the actual structure, and presented the most suitable curing method.

• Journal of Environmental Science International
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• v.30 no.12
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• pp.1027-1039
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• 2021

In this study, we investigated the optimal meteorological conditions for cloud seeding using aircraft over the Korean Peninsula. The weather conditions were analyzed using various data sources such as a weather chart, upper air observation, aircraft observation, and a numerical model for cloud seeding experiments conducted from 2018 to 2019 by the National Institute of Meteorological Sciences, Korea Meteorological Administration. Cloud seeding experiments were performed in the seasons of autumn (37.0%) and winter (40.7%) in the West Sea and Gangwon-do. Silver iodide (70.4%) and calcium chloride (29.6%) were used as cloud seeding materials for the experiments. The cloud seeding experiments used silver iodide in cold clouds. Aircraft observation revealed relatively low temperatures, low liquid water content, and strong wind speeds in clouds with a weak updraft. In warm clouds, the cloud seeding experiments used calcium chloride. Observations included relatively high temperatures, high liquid water content, and weak wind speeds in clouds with a weak updraft. Based upon these results, we determined the comprehensive meteorological conditions for cloud seeding experiments using aircraft over the Korean Peninsula. The understanding of optimal weather conditions for cloud seeding gained from this study provide information critical for performing successful cloud seeding and rain enhancement.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.5
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• pp.910-926
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• 2022

Suitability for the human body, freedom to move and thermal insulation are important design considerations in military clothing. This study investigates the performance and wearer-satisfaction of the functional inner winter uniform currently used in Korea; it is hoped that our data can inform the development of a future version. Interviews were conducted, in which the participants suggested various improvements. The uniforms were mainly worn for guard duty or as daily attire in cold weather. The participants chose how many layers to wear according to the current situation, rather than sticking to the layering recommended in the manual. Layering choices did not significantly affect combat efficiency but were found to affect wearers' comfort. Wearers' satisfaction was found to depend on the convenience of the clothing, whether it was in the appropriate size, freedom to move and thermal insulation. Also, this study suggests a problem with the current size system, as the analysis of size distribution, across all sizes, the range of current production is insufficient to cover the demand.

• Atmosphere
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• v.32 no.4
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• pp.277-295
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• 2022

The global weather prediction model, Korean Integrated Model (KIM), has been in operation since April 2020 by the Korea Meteorological Administration. This study assessed the performance of heat waves (HWs) in Korea in 2020. Case experiments during 2018-2020 were conducted to support the reliability of assessment, and the factors which affect predictability of the HWs were analyzed. Simulated expansion and retreat of the Tibetan High and North Pacific High during the 2020 HW had a good agreement with the analysis. However, the model showed significant cold biases in the maximum surface temperature. It was found that the temperature bias was highly related to underestimation of downward shortwave radiation at surface, which was linked to cloudiness. KIM tended to overestimate nighttime clouds that delayed the dissipation of cloud in the morning, which affected the shortage of downward solar radiation. The vertical profiles of temperature and moisture showed that cold bias and trapped moisture in the lower atmosphere produce favorable conditions for cloud formation over the Yellow Sea, which affected overestimation of cloud in downwind land. Sensitivity test was performed to reduce model bias, which was done by modulating moisture mixing parameter in the boundary layer scheme. Results indicated that the daytime temperature errors were reduced by increase in surface solar irradiance with enhanced cloud dissipation. This study suggested that not only the synoptic features but also the accuracy of low-level temperature and moisture condition played an important role in predicting the maximum temperature during the HWs in medium-range forecasts.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.1
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• pp.25-37
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• 2008

When livestock facilities in Korea have been changed larger and denser, rearing conditions have been getting worse and the productivity of animal production have been decreased. Especially in the cold season, the minimized ventilation has generally been operated to save energy cost in Korea resulting in very poor environmental condition and high mortality. While the stability, suitability, and uniformity of the rearing condition are the most important for high productivity, the ventilation configuration is the most important to improve the rearing condition seasonally. But, it is so difficult to analyze the internal air flow and the environmental factors by conducting only field experiment because the weather condition is very unpredictable and unstable as well as the structural specification can not be easily changed by the researchers considering cost and labor. Accordingly, an aerodynamic computer simulation was adopted to this study to overcome the weakness of conducting field experiment and study the aerodynamic itself. It has been supposed that the airflow is the main mechanism of heat, mass, and momentum transfers. To make the simulation model accurately and actually, simplified pig models were also developed. The accuracy of the CFD simulation model was enhanced by 4.4 % of errors compared with the data collected from field experiments. In this paper, using the verified CFD model, the CFD computed internal rearing condition of the mechanically ventilated pig house were analyzed quantitatively as well as qualitatively. Later, this developed model will be computed time-dependently to effectively analyze the seasonal ventilation efficiency more practically and extensively with tracer gas decay theory.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.385-397
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• 1982

The climatic impacts have been the environmental constraints with soil characteristics to achieve self sufficiency of food production in Korea. In this paper, the distribution and appearance of impacts and the changes in climatological status due to recent trend of early transplanting of rice are widely discussed to derive some countermeasures against the impacts, being focussed on cultural A long term analysis of the climatic impact appearances of the last 74 years showed that drought, strong wind, flood, cold spell and frost were the major impacts. Before 1970's, the drought damage was the greatest among the climatic impacts; however, the expansion and improvement of irrigation and drainage system markedly decreased the damage of drought and heavy rain. The appearance of cold damage became more frequent than before due to introduction of early transplanting for more thermophilic new varieties. Tongillines which were from Indica and Japonica crosses throw more attention to cold damage for high yields to secure high temperature in heading and ripening stages and lead weakness to cold and drought damage in early growth stage after transplanting. The plants became subject to heavy rain in ripening stage also. For the countermeasures against cold damage, the rational distribution of adequate varieties according to the regional climatic conditions and planting schedule should be imposed on the cultivation. A detoured water way to increase water temperature might be suggestable in the early growth stage. Heavy application of phosphate to boost rooting and tillering also would be a nutritional control method. In the heading and ripening stages, foliar application of phosphate and additional fertilization of silicate might be considerable way of nutritional control. Since the amount of solar radiation and air temperature in dry years were high, healthy plants for high yield could be obtained; therefere, the expansion of irrigation system and development of subsurface water should be performed as one of the national development projects. To minimize the damage of strong wind and rainfall, the rational distribution of varieties with different growing periods in the area where the damage occurred habitualy should be considered with installation of wind breaks. Not only vertical windbreaks but also a horizontal wind break using a net might be a possible way to decrease the white heads in rice field by dry wind. Finally, to establish the integrated countermeasures against the climatic impacts, the detailed interpretation on the regional climatic conditions should be conducted to understand distribution and frequency of the impacts. The expansion of observation net work for agricultural meteorology and development of analysis techniques for meteorological data must be conducted in future together with the development of the new cultural techniques.