• Journal of the military operations research society of Korea
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• v.26 no.1
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• pp.34-46
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• 2000

The object of this study is to construct a model for an optimal allocation of short surface to air missile defending our targets most efficiently from hostile aircraft´s attack. For the purpose of this, we analyze and establish facility allocation concept of existing models, apply set covering theory appropriate to problem´s properties, present the process of calculating the probability of target being protected, apply Sherali-Kim´s branching variable selection strategy, and then construct the model. As constructed model apply the reducing problem with application, we confirm that we can apply the large scale, real problem.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.05a
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• pp.37-40
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• 2005

High Performance Concrete(HPC) has been widely used in high-rise building. The HPC has several benefits including high strength, high fluidity and high durability. However. spatting is susceptible to occur in HPC and HPC also tends to be deteriorated in the side of fire resistance performance at fire. This paper focuses on the analysis of the temperature history and residual compressive strength with finishing material, in order to protect HPC from sudden-high-temperature, which is one of the main reason spatting occurs. Test results show that spalling occurs in all specimens. The most serious spalling took placed in HPC covering fire enduring spray-on material, whose covering thickness is 20mm but temperature history indicates that fire enduring spray effectively protected HPC from fire for more than 2hours. In addition, residual compressive strength ratio of HPC using fire enduring paint was more than $90\%$ of original strength, thus minimizing spatting and indicating significant fire resistance performance.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.781-788
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• 2011

A sphere-packing problem is to find an arrangement of the spheres to fill as large area of the given space as possible, and covering problems are optimization problems which are dual problems to the packing problems. We generalize the concepts of the weight and the Hamming distance for a binary code to those of Boolean algebra. In this paper, we define a weight and a distance on a Boolean algebra and research some properties of the weight and the distance. Also, we prove the notions of the sphere-packing bound and the Gilbert-Varshamov bound on Boolean algebra.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1416-1418
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• 2002

In order to examine the thermal properties of the wire materials, we analyzed the shrinkage, the expansion and the form transformation, the surface structure according to the thermal deterioration temperature through the testing method for a heating shrinkage of Korean Industrial Standard(KS C 3004). For IV(600V grade polyvinyl chloride insulated wires), we measured the shrinkage and the expansion rate, analyzed the surface structure using SEM(Scanning Electron Microscope). In the result of this experiment, the shrinkage rate of IV 2.0mm covering was high in comparison with other wires. As the deterioration temperature rises gradually, the covering is molten and harden.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.3
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• pp.106-115
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• 2009

Knowledge about how to stabilize soil structure is essential to conserve soil systems and maintain various biogeochemical processes through soil. In urban area, soil structural systems are degraded with inappropriate management and land use and become vulnerable to erosion. We analyzed the structural changes of surface soils with different land uses, i.e., forests, parks, roadside green area, riparian area, and farmlands (soybean fields), in the Anyang Stream Watershed in order to find the factors influencing the stability of soil structure and the implication for better management of surface soil. Soil organic matter contents of other land use soils were only 18~52% of that in forest soils. Soil organic matter increased the stability of soil aggregates in the order of soybean fields < roadsides < riparian < parks < forests and also reduced soil bulk density (increased porosity). The lowest stability of soybean field soils was attributed to the often disturbance like tillage and it was considered that higher stability of park soils comparing to other land use soils except forests was owing to the covering of soil surface with grass. These results suggest that supply of soil organic matter and protection of soil surface with covering materials are very important to increase porosity and stability of soil structure.

• Journal of Soil and Groundwater Environment
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• v.29 no.1
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• pp.10-17
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• 2024

In Korea, the common remedial process for reclamation of agricultural soils nearby abandoned mines involves chemical soil stabilization followed by covering with clean soil. This study investigated the chemical properties of cover soils and the validity of HCl extraction method in assessing the degree of As and heavy metal stabilization in stabilized soils collected from 14 plots where mine reclamation had been completed. The results revealed there were no major differences in contaminants extraction rate between the stabilized soils and contaminated soils, suggesting HCl extraction procedure is a less feasible method to determine the efficiency of the stabilization. Soil quality indicators including OM, SiO₂, P₂O₅, etc. of the land-covering soils were generally lower than those of stabilized soils that used to be the cultivation layer before the stabilization. Nonetheless, the value of those indicators didn't meet the regulatry limits of agricultural soil. Therefore, future strategy for mine reclamation should concentrate not only on contaminant concentration but also on soil quality parameters for agricultural use of the reclaimed soil.

• Honam Mathematical Journal
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• v.35 no.3
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• pp.515-524
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• 2013

To study product properties of digital spaces, we strongly need to formulate meaningful adjacency relations on digital products. Thus the paper [7] firstly developed a normal adjacency relation on a digital product which can play an important role in studying the multiplicative property of a digital fundamental group, and product properties of digital coverings and digitally continuous maps. The present paper mainly surveys the normal adjacency relation on a digital product, improves the assertion of Boxer and Karaca in the paper [4] and restates Theorem 6.4 of the paper [19].

• Korean Journal of Computational Design and Engineering
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• v.5 no.4
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• pp.393-402
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• 2000

Recently 5-axis NC machines are widely used in Korea. Since 5-axis machines have two more degrees of freedom than 3-axis machines, it is very important to find desirable tool positions(locations and orientations) in order to make an efficient use of expensive 5-axis NC machines. In this research an algorithm to determine “optimal” tool positions for 5-axis machining of sculptured surfaces is developed. For given CC(Cutter Contact) points, this algorithm determines the cutter axis vectors which minimize cusp heights and satisfy constraints. To solve the optimal problem, we deal with following major issues: (1) an approximation method of a cusp height as a measure of optimality (2) Identifying some properties of the optimal problem (3) a search method for the optimal points using the properties. By using a polyhedral model as a machining surface, this algorithm applies to sculptured surfaces covering: overhanged surface.

• Elastomers and Composites
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• v.33 no.1
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• pp.17-26
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• 1998

Natural rubber was filled with 8 commercial carbon blacks covering range of rubber-grade products at different levels of filler loadings in order to investigate physical compound and vulcanizate properties. It was found that the curves of rubber property vs filler loading of both uncured compounds and vulcanizates can be superposed to one single master curve by introducing an effective volume fraction which is based on CDBP. The effective volume fraction, $V_{EFF}$ was utilized to explain the variation of the stiffness of all rubber compounds. The surface area-corrected effective volume fraction, V', was utilized to explain the formation of bound rubber, rebound and lambourn wear.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1248-1256
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• 2020

In this study, the polyurethane resin was synthesized by applying PTMG and DMBA of different composition ratios for the synthesis of water-dispersible polyurethane used in wound coating resin. The varying properties of the synthesized water-dispersible polyurethane were measured through tensile strength, elongation, and abrasion resistance analysis. As for the tensile strength measurement result according to the PTMG content, the sample with the highest reaction molar ratio was measured as 1.08 kgf/mm2 and the elongation was measured as 520%. As for the tensile strength result according to the DMBA content, the sample with the highest reaction molar ratio was measured as 0.51 kgf/mm2, and the elongation was measured as 435%. The degree of surface destruction by the abrasion resistance measurement was visually confirmed through SEM.