• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.7 no.1
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• pp.10-16
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• 2011

Performance of ground-source heat pumps (GSHPs) is mainly affected by ground heat exchangers which makes up more than 40% of construction cost. Exact construction and grout as backfill are important, because it is difficult to repair after being installed. As grout materials, bentonite grout material and cement material are used In this paper, thermal conductivity according to mix proportion of cement grout has been experimentally studied. Some variables were set to evaluate thermal conductivities according to change in cement content, unit water ratio, mass per volume of fresh mortar, and aggregate types. From the experimental analysis, high performance cement grout has been proposed.

• Asia pacific journal of information systems
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• v.13 no.4
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• pp.171-189
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• 2003

The three main purposes of this paper are to (1) identify critical success factors(CSFs) for electronic commerce(EC), (2) investigate the explanatory power of these CSFs on firm performance, and (3) compare differences in evaluating CSFs and explaining impact of CSFs on performance among Korea, Japan, and U.S.A. EC firms. Through a literature review and interviews with managers in EC firms, a list of 16 CSFs consisting of 111 items was compiled. In the second stage, questionnaires were administered to managers of EC companies in Seoul, Korea, Tokyo, Japan, and Texas, U.S.A. Survey results show that CSFs have very significant explanatory power for firm performance in Korea, Japan, and U.S.A. While security, privacy, technical expertise, information about goods/services, and variety of goods/services are the most explanatory CSFs in Korea and Japan, evaluation of EC operations, technical expertise, and ease of use show most explanatory power in U.S.A. In general, respondents in Korean and Japan evaluate CSFs quite differently compared to U.S.A counterparts.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.251-256
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• 2002

Resistance performance of small size fishing vessel is experimentally investigated to find out the effect of fore-body shape and trim for the better hull form development. The tests are performed for four different cases in the high speed circulating water channel(CWC). Wave patterns are observed together to investigate the relation between the resistance performance and the wave characteristics.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.5
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• pp.781-787
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• 2011

Mine countermeasure missions(MCMs) may induce the loss of human and ship because of the covert of mine. In recent years, unmanned underwater vehicles(UUVs) have emerged as viable technical solution for conductimg underwater search, surveillance, and clearance operations in support of mine countermeasure missions because of her autonomy and long time endurance capability. This paper introduces a technical approach to mine countermeasure mission effectiveness analysis and presents some simulation-based analysis results for engineering of the UUV system definition which could be support analysis of alternatives for system definition and design.

• Structural Engineering and Mechanics
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• v.53 no.3
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• pp.589-605
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• 2015

The use of the rigid polyurethane foam (RPF) to strengthen buried structures against blast terror has great interests from engineering experts in structural retrofitting. The aim of this study is to use the RPF to strengthen the buried structures under blast load. The buried structure is considered to study the RPF as structural retrofitting. The Guowei model (Guowei et al. 2010) is considered as a case study. The finite element analysis (FEA) is also used to model the buried structure under shock wave. The buried structure performance is studied based on detonating different TNT explosive charges. There is a good agreement between the results obtained by both the Guowei model and the proposed numerical model. The RPF improves the buried structure performance under the blast wave propagation.

• Structural Engineering and Mechanics
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• v.49 no.4
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• pp.463-477
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• 2014

In this paper, seismic performance of Kozyatagi Bridge is evaluated by employing nonlinear elasto-plastic dynamic analysis and the deformation-based performance. The time-history records of the 1999 Izmit, 1971 San Fernando and 1989 Loma Prieta earthquakes are modified by adopting a probability of exceedance of 2% in 50 years corresponding to the return period of 2475 years. The analysis is carried out for three different bearing cases which are movable bearings, restrained bearings, and movable bearings with viscous fluid dampers in the radial direction. The analysis results show that the bridge can be retrofitted with viscous fluid dampers. In this case the reinforced concrete piers need not be strengthened by any jacketing techniques in order to preserve the original architectural appearance of the bridge. The retrofitting design of the bridge with viscous fluid dampers is also presented in detail.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.1
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• pp.79-88
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• 1999

The stability and performance (peel strength) of the acrylic copolymer and various modified rosin systems were investigated. The peel strength was measured over a wide range of scaling rates, and the influence of the viscoelasticity of the PSA(pressure sensitive adhesive) was considered. In the case of miscible systems, the peak of peel strength (PSA performance) over wide peel rates was changed and modified systematically with increasing glass transition temperature of the blends. The peak of the peel strength for blended systems shifts toward the lower rate side as glass transition temperature ($T_g$) of the blend increased. The influence of esterification of the rosin on performance and stability against deterioration was greatly modified by blending with rosin of glycerol ester and rosin pentaerythritol ester. The failure mode of the blend varies with the combination with acrylic copolymer and modified rosin, and cohesive failure was found at a lower peel rate while interfacial failure was found at a high peel rate. A few systems where a single Tg could be measured, despite the fact that two phases were observed microscopically, were detected.

• Journal of the Korea Society for Simulation
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• v.23 no.2
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• pp.7-15
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• 2014

System operational performance analysis for wire-guided torpedo is intended to provide technical analysis data for requirements analysis and development, which, as a consequence, supports the requirements definition activity for systems engineering. Technical approach and analysis example are presented including problem definition, formulation, modeling, simulation and analysis results that are applied to the on-going Next Generation Torpedo project.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.89-93
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• 2002

Resistance performance of 6.67 G/T class fishing vessel is experimentally investigated in low and middle speed ranges to find out the effect of a new chine. The tests are performed for four different cases in the circulating water channel(CWC). Wave patterns are observed together to make clear the relation between the resistance performance and the wave characteristics. The results show that the new chine can be one of the effective device to reduce the resistance.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.33-40
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• 2000

The effectiveness of silica-based microgels prepared through the reaction of sulfuric acid and sodium silicate as a component of Compozil system has been evaluated . Silica based microgels with better performance in retention and drainage than a commercial colloidal silica sol have been successfully prepared. Silica gels with the highest charge density were obtained when product pH was controlled to 9. And highly charged silica-based microgels showed greater retention and freeness performance than a commerical product. In particular the difference in retention, turbidity , and freeness between these microgels and a commercial product was eminent at low addition rate. The effects of reaction conditions including reaction temperature, process water quality and feeing rate on product efficiency in improving retention and drainage were also investigated and discussed.