• Journal of the Korean GEO-environmental Society
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• v.19 no.7
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• pp.13-18
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• 2018

Recently, road subsidence has been increasing in urban areas, threatening the safety of citizens. In the lower part of the road, various road facilities such as water supply and drainage pipelines and telecommunication facilities are buried, and the deterioration of the facilities causes the road subsidence. In particular, in the case of old sewer pipes which are attracting attention as a main cause of road subsidence, the management of sewer pipe replacement, repair and reinforcement is being performed depending on the burial year. Therefore, in this study, we tried to suggest a reliable road subsidence risk assessment method considering various sewer specifications and surrounding environment information and CCTV exploration result and GPR exploration result.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.1
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• pp.37-42
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• 2013

Double pipe system in which PB pipe is inserted in CD pipe buried in the concrete slab is widely used for cold and hot water supplies in apartment housings. The system, however becomes complicated and the overlaying pipes in the concrete slab weaken the compressive strength of the slab. Also, insufficient insulation increases energy loss. In this work, the problems of the double pipe system are studied and plans A, B, and C are suggested for improvement. In terms of compressive strength of the concrete slab, plan A(total pipe length 73 m) was the weakest and plan B(2 m) was the strongest. Energy loss of plan A was the largest with 558.9 W and plan B was the lowest with 220.7 W. However, considering the combined effect of strength and heat loss, plan C becomes the best choice, which retains the advantage of the double pipe system.

• Solar Energy
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• v.15 no.2
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• pp.13-24
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• 1995

Korean traditional Ondol with the sensible heat storage medium has been for a long time used as residential heating system, in these days the concrete Ondol without the heat storage medium was realized as the heating system in the private houses and the apartments. This floor heating system is good for our health. But the concrete Ondol is not desirable for the energy saving and for the maintenance of comfortable room temperature because the heat storage medium is not employed in the concrete Ondol. And as the hot water circulating pipes are buried under the concrete floor, the concrete Ondol system has some kind of problems to be improved. Therefore the new type of Ondol system was developed in this study. And the new Ondol was consisted of latent heat storage material as heat storage medium with a great heat capacity and bioceramics as medium to maintain comfortable room temperature. In this study, the heat transfer characteristics of latent heat storage-bioceramic Ondol was analyzed theoretically.

• Journal of the Korean GEO-environmental Society
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• v.21 no.9
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• pp.25-32
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• 2020

The underground utilities installed under the ground is an important civil engineering structure, such as water supply and sewerage pipes, underground power lines, various communication lines, and city gas pipes. Such underground utilities can be exposed to risk due to external factors such as concentrated rainfall and vehicle load, and it is important to select and construct an appropriate backfill material. Currently, a method mainly used is to fill the soil around the underground utilities and compact it. But it is difficult to compact the lower part of the buried pipe and the compaction efficiency decreases, reducing the stability of the underground utilities and causing various damages. In addition, there are disadvantages such as a decrease in ground strength due to disturbance of the ground, a complicated construction process, and construction costs increase because the construction period becomes longer, and civil complaints due to traffic restrictions. One way to solve this problem is to use a liquid filler. The liquid filler has advantages such as self-leveling ability, self-compaction, fluidity, artificial strength control, and low strength that can be re-excavated for maintenance. In this study, uniaxial compression strength test and fluidity test were performed to characterize the mixed soil using marine clay, stabilizer, and in-situ soil as backfill material. A freezing-thawing test was performed to understand the strength characteristics of the liquid filler by freezing, and in order to examine the effect of the filling materials on the corrosion of the underground pipe, an electrical resistivity test and a pH test were performed.

• Journal of the Korean Home Economics Association
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• v.43 no.1 s.203
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• pp.145-165
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• 2005

In 1937, most Korean compatriot who lived in Yunhaeju moved to Kazakhstan and Uzbekistan in Central Asia following the deportation policy of Russia. Korean compatriot have kept their traditional life style for 140 years, without a deep relationship with Korea. This study examined the heating systems of Korean compatriot in Yunhaeju, Kazakhstan and Uzbekistan, Russia. A literature review and field research, based on Ethnography as a research method, was employed. The results of the research were as following: 1) Korean compatriot in Yunhaeju use a Pechika, which is a radiator that uses hot water, and a Gudul as the main heating systems, but the use of a Pechika was most common. A Pechika functions for cooking as well as for warming the house. The room with the Gudul was connected to the kitchen, so this space was used as a place for cooking and eating, for family members to meet. Many kinds of fuel, like gas and electricity, were used to power the heating systems. 2) Korean compatriot in Kazakhstan use radiators, with hot water as the main heating system, with ratio using Gudul used in this region being the highest of all the three areas. The most common fuels used for a Gudul were wood and coal, and gas was also used in cooking. The room with the Gudul was planned to be located beside the fireplace, without any walls. The people using a Gudul use that place for eating and meeting, as well as for family members to sleep. 3) The main heating system of Korean compatriot in Uzbekistan was a radiator using hot water, and those with pipes containing hot water buried under the floor were very common. The function is very similar to that of a Gudul, so most people using this type of radiator would sleep on the floor. Those people with a traditional Gudul not using them were mostly in Uzbekistan. The reason for this was that the family members had diminished, so it was hard work for elderly parents to manage an extra building containing a Gudul. Gas was the fuel generally used for heating and cooking in Uzbekistan. 4) Guduls were used in the Korean compatriot's houses in all three areas, even though they have changed in structure to adapt to the Russian life style. However, Guduls have still been functioning to maintain a traditional life style in Korean compatriot's houses for the gathering of family members.

• Journal of the Korean GEO-environmental Society
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• v.24 no.4
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• pp.23-29
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• 2023

Ground subsidence shows a mechanism in which the upper ground collapses due to the formation of a cavity due to the movement of soil particles in the ground due to the formation of a waterway because of damage to the water supply/sewer pipes. As a result, cavity is created in the ground and the upper ground is collapsing. Therefore, ground subsidence frequently occurs mainly in downtown areas where a large amount of underground facilities are buried. Accordingly, research to predict the risk of ground subsidence is continuously being conducted. This study tried to present a ground subsidence risk prediction model for two districts of ○○ city. After constructing a data set and performing preprocessing, using the property data of underground facilities in the target area (year of service, pipe diameter), density of underground facilities, and ground subsidence history data. By applying the dataset to the machine learning model, it is evaluated the reliability of the selected model and the importance of the influencing factors used in predicting the ground subsidence risk derived from the model is presented.

• Journal of the Korean GEO-environmental Society
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• v.23 no.4
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• pp.5-10
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• 2022

Recently, ground subsidence has been continuously occurring in downtown areas, threatening the safety of citizens. Various underground facilities such as water and sewage pipelines and communication pipelines are buried under the road. It is reported that the cause of ground subsidence is the deterioration of various facilities and the reckless development of the underground. In particular, it is known that the biggest cause of ground subsidence is the aging of sewage pipelines. As an existing study related to this, several representative factors of sewage pipelines were selected and a study to predict the risk of ground subsidence through statistical analysis has been conducted. In this study, a data SET was constructed using the characteristics of OO city's sewage pipe characteristics and ground subsidence data, The data set constructed from the characteristics of the sewage pipe of OO city and the location of the ground subsidence was used. The goal of this study was to present a classification model for the occurrence of ground subsidence according to the characteristics of sewage pipes through machine learning. In addition, the importance of each sewage pipe characteristic affecting the ground subsidence was calculated.