• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.361-369
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• 2004

Galaxy clusters as the densest and most prominent regions within the large-scale structure can be used as well characterizable laboratories to study astrophysical processes on the largest scales. X-ray observations provide currently the best way to determine the physical properties of galaxy clusters and the environmental parameters that describe them as laboratories. We illustrate this use of galaxy clusters and the precision of our understanding of them as laboratory environments with several examples. Their application to determine the matter composition of the Universe shows good agreement with results from other methods and is therefore a good test of our understanding. We test the reliability of mass measurements and illustrate the use of X-ray diagnostics to study the dynamical state of clusters. We discuss further studies on turbulence in the cluster ICM, the interaction of central AGN with the radiatively cooling plasma in cluster cooling cores and the lessons learned from the ICM enrichment by heavy elements.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.381-394
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• 2016

The several noise level estimation algorithms that have been developed for use in image processing and computer graphics generally exhibit good performance. However, there are certain special types of noisy images that such algorithms are not suitable for. It is particularly still a challenge to use the algorithms to estimate the noise levels of complex textured photographic images because of the inhomogeneity of the original scenes. Similarly, it is difficult to apply most conventional noise level estimation algorithms to images rendered by the Monte Carlo (MC) method owing to the spatial variation of the noise in such images. This paper proposes a novel noise level estimation method based on histogram modification, and which can be used for more accurate estimation of the noise levels in both complex textured images and MC-rendered images. The proposed method has good performance, is simple to implement, and can be efficiently used in various image-based and graphic applications ranging from smartphone camera noise removal to game background rendition.

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.2
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• pp.132-139
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• 2001

This study deals with coal-mine waste (CMW) for use in concrete as a replacement of normal aggregates. The CMW was collected from Sabuk region. Ganwon-do. Fine and coarse aggregates from CMW were prepared by using a crusher and separating debris with #4 sieve. CMW aggregates showed good physical and mechanical properties with having specific gravity over 2.65, absorption less than 1%, and abrasion ratio below 20%. However, particle shape of CMW was poor because of non-isotropic nature of matrix which cause particles to be long or flat. Since irregular particles caused a poor workability, to make workability better, a 1/4 of coarse aggregate was replaced with normal aggregate together with a superplasticizer. Compressive strength and other mechanical properties of CMW concrete were very good. Color of the concrete was darker than normal concrete due to black color of CMW. In conclusion, characteristics of CMW concrete was acceptable for use as a structural concrete material.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.138-143
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• 2000

In this paper, we carried out experiment to use crushed waste glass as a fine aggregate. This study delt with the comparative analysis on the construction works and engineering properties of concrete containing crushed waste glass through physical experiment. The experimental variables are crushed waste glass substitution ratio and W/C(38, 53%). When the W/C was 38%, we could know that concrete containing crushed waste glass was good as general concrete on the construction works and engineering properties but the concrete containing crushed waste glass applied W/C 53% was not good as general concrete on those. Therefore, concrete containing crushed waste glass applied W/C 53% should use admixture on the site.

• Journal of Environmental Science International
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• v.9 no.2
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• pp.177-183
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• 2000

This study is focused on the incustrial symbiosis based on industrial ecosystem theory. At first, the concept of industrial ecosystem was introduced. Industrial symbiosis is a good tool in order to make a harmony between industry and natural ecosystem. The good example of industrial symbiosis is the case of Kalundborg in Denmark, where 11 networks are working in four enterprises and one community nearby. It was proved that savings of natural resources and economic benefit are achieved by use of industrial symbiosis. Moreover, the control of pollutant emission was also done by use of advanced technology and investments. Based on this case. It was shown that industrial symbiosis through eco-industrial complex in Korea was confronted with many difficulties. First of all., loose emmision criteria, recycling system on wastes, and the absence of will for industrial symbiosis should be solved in Korea.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.41-46
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• 2003

Until now, the quantity to recycle wasted concrete as the great supplementary value was very little. But considering a insufficiency of the present state of aggregates, the recycling of wasted aggregates is indispensable. This study will offer the basic application data of the recycled aggregates to make by the new attempt and offer the basic data of the great supplementary value of recycled aggregate to make good use of precast process. The result of compressive strength, tensile strength, flexural strength and drying shrinkage test of concrete by recycled aggregates were similar to the property of normal aggregate concrete, and the contrary effect of recycled aggregate by high temperature steam curing do not have been found out. Therefore the great supplementary value of recycled aggregate to make good use of precast process is possible way to be helpful to a insufficiency of the present state of aggregates.

• Journal of the Korean Home Economics Association
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• v.42 no.12 s.202
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• pp.107-122
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• 2004

The purposes of this study were to investigate the actual conditions of leisure life of the retired elderly in Korea and to analyze the difference of their leisure activity types by socio-demographic characteristics, the factors which have an effect on their satisfaction of leisure life. This study was secondary analysis of the national data; from The Social Statistics Survey; collected by the Korea National Statistical Office in 2000. The major findings are as follows. 1) The types of leisure activity of the retired elderly included watching television and doing nothing. 2) There were significant differences in the types of leisure activity by sex, age, education degree, having spouse or not, having house or not, and residential area. 3) Results of logistic regression analysis indicated that the most effective factors of the leisure life satisfaction were sex, age, having spouse or not, having house or not, residential area and the types of leisure activity.

• The Korean Journal of Applied Statistics
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• v.16 no.1
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• pp.169-179
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• 2003

We suggest two types of misuses to analyze the same survey data. One is related with the fact that people nay use the wrong bounds of error when they compare two proportions. And the other is related with that some non-statisticians are apt to use wrong methods when there is a neutral answer in a question. We suggest these methods and compare them with the statistically good method. It will be a good results in educational purpose.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2006.06b
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• pp.251-256
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• 2006

The purpose of this study was to confirm multiple retention system of C-PAM, A-PAM and Inorganic micro particles vs. traditional micro particle system and dual polymer system by measuring retention, drainage and formation using RDA HSF and Techpap 2D -F Sensor The benefits of dual polymer system were easy to use, low chemical consumption and good retention property but defect was worse drainage property than inorganic microparticle systems. On the other hand, Inorganic microparticle system had benefit of good drainage effect but defects were difficult to use, high chemical consumption. Therefore, we tried to find optimal morphology of polyacrylamide and applied to multiple retention system of C-PAM, A-PAM and inorganic microparticles to compensate defects of both of retention systems. As a result, we found the performance of branched C-PAM, branched A-PAM and inorganic micro particle triple system was more appropriate than traditional inorganic mircoparticle systems or dual polymer systems by comparing retention, drainage and formation.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.561-566
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• 2009

Alluvium is sedimentary stratum and composed of gravel, sand, silt, clay. Permeability of alluvium is the higher. If alluvium have lots of aquifer, will be of great use heat source and heat sink of heat pump. Alluvium aquifer contain the thermal energy of surrounding ground. Also geothermal heat pump using alluvium aquifer reduce expenses than general geothermal heat pump, because geothermal heat pump using alluvium aquifer make use of single well. In this study geothermal heat pump using alluvium aquifer was installed and tested for a building. The heat pump capacity is 30USRT. Temperature of ground water is in $12{\sim}17^{\circ}C$ annually and the quality of the water is as good as living water. The heat pump cooling COP is 4.4 ~ 4.7. The system cooling COP is 3.25 ~ 3.6. This performance is as good as BHE type ground source heat pump.