• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.321-327
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• 2015

This study presents an HFC152a refrigerant air conditioner as an alternative to HFC134a, which is currently used in mobile air conditioning systems. Cool-down performance tests of an HFC152a air conditioning system were conducted and compared to a baseline HFC134a air conditioner. The experimental set-up consisted of a belt-driven compressor, a sub-cooled type condenser, an evaporator, and a block-type thermal expansion valve (TXV). A drop-in test was carried out on the mobile air conditioning system under various vehicle running speeds in a climate-controlled wind tunnel (CWT). Additionally, to optimize the HFC152a air conditioning system, the effects of the TXVs on the performance were studied. The results show that compared to the HFC134a air conditioning system, the refrigerant charge quantity was reduced by approximately 20%, the discharge pressure was reduced by about 350~430 kPa, and the air discharge temperature at vehicle running conditions was $0.5{\sim}1.5^{\circ}C$ lower. In addition, good compressor durability was expected due to the lower compression ratio.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1209-1214
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• 2009

Various automatic temperature control systems have been used widely in Korea for the conservation of heating energy and the enhancement of thermal comfort in residential buildings. But the heating control performance for automatic temperature control systems extensively vary with the design and operational conditions of the heating system, the climate condition and others. It was introduced in this study a numerical calculation program package to analyze heating control characteristics of the automatic temperature control system. This package is able to analyze the room air temperature, return water temperature, supplied heating flux and flow rate, and so on. One the other hand, the simulation results were verified by comparing with the field test results.

• Journal of Climate Change Research
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• v.3 no.4
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• pp.259-270
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• 2012

Mobile air conditioning(MAC) systems of light-duty vehicles consume the most energy among auxiliary parts. Vehicle $CO_2$ reduction policies in Korea, US EPA and EU include the strategies to reduce additional $CO_2$ by MAC operation with providing incentive for the high-efficient MAC technologies. It is under development how to estimate MAC $CO_2$ and to differentiate advanced or high-efficient MAC system in US EPA and EU. The additional energy by MAC operation would beaffected by not only driving patterns but also environmental conditions such as temperature and humidity. In this study, we estimated MAC $CO_2$ of Korean light-duty vehicles with various driving cycles and environmental conditions. Test results were corrected to reference conditions for varied temperature and humidity during tests to get the comparable data for test vehicles. The test results showed that high-efficient MAC technologies have potential to reduce MAC $CO_2$ approximately by 50%. Considering the rate of MAC $CO_2$ to vehicle $CO_2$, it is expected that the introduction of high-efficient MAC technologies would considerably reduce vehicle $CO_2$ emission in MAC operation.

• Structural Engineering and Mechanics
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• v.51 no.5
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• pp.755-771
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• 2014

Environmental changes, especially global climate change, are creating new challenges to the development of the Arctic regions, which have substantial energy resources. And attention to offshore structures has increased with oil and gas development. The structural impact response of an explosion-resistant profiled blast walls normally changes when it operates in low temperatures. The main objectives of this study are to investigate the structural response of blast walls in low temperature and suggest useful guidelines for understanding the characteristics of the structural impact response of blast walls subjected to hydrocarbon explosions in Arctic conditions. The target temperatures were based on the average summer temperature ($-20^{\circ}C$), the average winter temperature ($-40^{\circ}C$) and the coldest temperature recorded (approximately $-68^{\circ}C$) in the Arctic. The nonlinear finite element analysis was performed to design an explosion-resistant profiled blast wall for use in Arctic conditions based on the behaviour of material properties at low temperatures established by performing a tensile test. The conclusions and implications of the findings are discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4D
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• pp.513-521
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• 2008

The objective of this study is the evaluation of the impact on the construction condition due to historical observation data and IPCC SRES A2 climate change scenario. For this purpose, daily precipitation and daily mean temperature data which have been observed over the past 30 years by Korea Meteorological Administration are collected and applied. Also, A2 scenarios during 2011~2040 and 2051~2080 are used for this analysis. According to the results of trend analyses on annual precipitation and annual mean temperature, they are on the increase mostly. The available working day and the day occurred an extreme event are used as correlation indices between climate factor and construction condition. For the past observation data, linear regression and Mann-Kendall test are used to analyze the trend on the correlation index. As a result, both working day and extreme event occurrence day are increased. Likewise, for the future, variation analysis showed the similar result to that of the past and the occurrence frequency of extreme events is increased obviously. Therefore, we can project to increase flood damage potential on the construction site by climate change.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.2
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• pp.79-88
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• 2015

Preparations need to be made for Korean pine(Pinus koraiensis) in anticipation of climate change because Korean pine is an endemic species of South Korea and the source of timber and pine nut. Therefore, climate change adaptation policy has been established to conduct an impact assessment on the distribution of Korean pine. Our objective was to predict the distribution of Korean pine while taking into account uncertainty and afforestation conditions. We used the 5th forest types map, a forest site map and BIOCLIM variables. The climate scenarios are RCP 4.5 and RCP 8.5 for uncertainty and the climate models are 5 regional climate models (HadGEM3RA, RegCM4, SNURCM, GRIMs, WRF). The base period for this study is 1971 to 2000. The target periods are the mid-21st century (2021-2050) and the end of the 21st century (2071-2100). This study used the MaxEnt model, and 50% of the presences were randomly set as training data. The remaining 50% were used as test data, and 10 cross-validated replicates were run. The selected variables were the annual mean temperature (Bio1), the precipitation of the wettest month (Bio13) and the precipitation of the driest month (Bio14). The test data's ROC curve of Korean pine was 0.689. The distribution of Korean pine in the mid-21st century decreased from 11.9% to 37.8% on RCP 4.5 and RCP 8.5. The area of Korean pine at an artificial plantation occupied from 32.1% to 45.4% on both RCPs. The areas at the end of the 21st century declined by 53.9% on RCP 4.5 and by 86.0% on RCP 8.5. The area of Korean pine at an artificial plantation occupied 23.8% on RCP 4.5 and 7.2% on RCP 8.5. Private forests showed more of a decrease than national forests for all subsequent periods. Our results may contribute to the establishment of climate change adaptation policies for considering various adaptation options.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.5
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• pp.84-90
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• 2014

The aim of this paper is to investigate the application of solar energy in reducing cabin thermal load. When a vehicle is parked under the sun in summer, the interior temperature can reach up to $70^{\circ}C$ depending on the solar intensity. Solar power, one of the green energies, is used in automobile air conditioning systems, in order to operate the blower. The power supply of a blower's voltage has been used in a solar sunroof experiment. At the climate wind tunnel, cabin temperature changes were conducted with various operating modes of an air handling system and the preventilation parking conditions of several vehicles, outdoors, was also examined. The test results of the solar sunroof, 39.3W power and 14.1% efficiency were obtained. The thermal load behavior was analysed with the air handling system operating mode differently according to the cabin temperature. By simply operating the blower, average cabin temperature decreased between $5^{\circ}C{\sim}10^{\circ}C$ in those vehicles parked outdoors in summer. This reveals that cabin thermal comfort can be improved without consuming the vehicle's extra energy, and that the performance of the air-conditioning system is better than those currently found in vehicles. Moreover, fuel economy will be increased as a result of the reduction in the use of the air-conditioning system, and many other human advantages will be gained. Such advantages include minimized VOCs and a healthy cabin environment.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1477-1482
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• 2023

This study examines marine heat wave (MHW) in the Northeast Asia region from 2012 to 2021, utilizing geostationary satellite Communication, Ocean, and Meteorological Satellite (COMS)/Meteorological Imager sensor (MI) and GEO-KOMPSAT-2A (GK-2A)/Advanced Meteorological Imager sensor (AMI) Sea Surface Temperature (SST) data. Our analysis has identified an increasing trend in the frequency and intensity of MHW events, especially post-2018, with the year 2020 marked by significantly prolonged and intense events. The statistical validation using Optimal Interpolation (OI) SST data and satellite SST data through T-test assessment confirmed a significant rise in sea surface temperatures, suggesting that these changes are a direct consequence of climate change, rather than random variations. The findings revealed in this study serve the necessity for ongoing monitoring and more granular analysis to inform long-term responses to climate change. As the region is characterized by complex topography and diverse climatic conditions, the insights provided by this research are critical for understanding the localized impacts of global climate dynamics.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.39-46
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• 2005

The present study concerns an experimental study of a R-22 heat pump system consisted of liquid and liquid heat exchangers. The test was performed for various systems of a single-, tandem-, and two stage-cycle at the same environmental conditions of temperature. Various experiments of the heat pump system were peformed to compare the heating capacity and COP, when the outdoor temperature is near $-15^{\circ}C$ and the indoor temperature is $20^{\circ}C.$ As the results of the present study, the system of Tandem(parallel) cycle showed the best heating performance, while the discharge temperature of refrigerant was too high. In case of the system of two stage cycle, the performance characteristics were significantly improved by employing the inter cooler.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.6
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• pp.287-293
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• 2014

Internal combustion engines release 30~40% of the energy from fossil fuels into the atmosphere in the form of exhaust gases. By utilizing this waste heat, plenty of energy can be conserved in the auto industry. Thermoelectric generation is one way of transforming the energy from engine's exhaust gases into electricity in a vehicle. The thermoelectric generators located on the exhaust pipe have been developed for vehicle applications. Different experiments with thermoelectric generators have been conducted under various test conditions as following examples: hot gas temperature, hot gas mass flow rate, coolant temperature, and coolant mass flow rate. The experimental results have shown that the generated electrical power increases significantly with the temperature difference between the hot and the cold side of the thermoelectric generator and the gas flow rate of the hot-side heat exchanger. In addition, the gas temperature of the hot-side heat exchanger decreases with the length of the thermoelectric generator, especially at a low gas flow rate.