• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.105-111
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• 2000

If a saturate sand is subjected to ground vibrations it tends to compact and decrease in volume. if drainage is unable to occur the tendency to decrease in volume results in an increase in pore water pressure and if the pore water pressure build up to the point at which it is equal to the overburden pressure the effective stress becomes zero the sand loses its strength completely. This phenomenon is called "Liquefaction" It is associated primarily but not exclusively with saturated cohesion soils. The attention and study on liquefaction have been growing since the earthquake in Niigita Japan in 1964. Many researchers on liquefaction effect have been carried out in many countries under the potential influence of earthquake including Japan. However little research on liquefaction has been reported in Korea because Korea has been considered to be safe from earthquake. The term "liquefaction" is only known among geotechnical engineers,. In this paper overview of liquefaction and the evaluation on the applicability of vibrated crushed-stone pile as a liquefaction prevention method are presented.ethod are presented.

• 한국해양공학회지
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• 제12권1호
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• pp.3-9
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• 1998

According to the developement of cities, electric wires and commuinication lines which are currently above the ground effect on the bad. Nowadays, it is necessary to build up underground facilities because the construction is increasing. Excavation work has been dominant even though the inconvenient things occurred, for example a civil appeal, a traffic obstacle, safety and spoiling the fine view because of the cost or period of the construction work. But the congestion of cities are more and more serious. Therefore shield-method is the way to escape from congestion. I considered all the construction fields which are in progress or finished.

• 수산경영론집
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• 제48권3호
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• pp.47-59
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• 2017

Fish mortality is the most important success factor in aquaculture management. To order fingerlings considering the effect of mortality is a important problem in aquaculture farm. This study is aimed to decision the number and size of fry in aquaculture farm. This study build the mathematical model that finds the value of decision variable to minimize total cost that sums up the fingerling purchasing cost, aquaculture farm operating cost and feeding cost under mortality constraint. The proposed mathematical model involve biological and economical variables: (1) number of fingerlings (2) fish growth rate (3) mortality (4) price of a fry (5) feeding cost, and (6) possible order period. Numerical simulation model presented here in. The objective of numerical simulation is to provide for decision makers to analyse and comprehend the proposed model. When extensive biological and cost data become available, the proposed model can be widely applied to yield more accurate results.

• 공학교육연구
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• 제18권2호
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• pp.3-7
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• 2015

Entrepreneurship has been considered as an engine to lead economy, which has been resulting in a focus on entrepreneurship education to promote entrepreneurship. This paper focuses on science and engineering students, and analyzes the relationship between entrepreneurship education and entrepreneurship level. The response results of 950 students (34 universities) were as follows. First, the entrepreneurship level of science and engineering students are a little high but not as significant more than non-science and engineering. Second, science and engineering students have an impact on the level of entrepreneurship about entrepreneurship courses. Third, entrepreneurship courses and clubs have an effect on entrepreneurship level. As a conclusion, we have to improve the quality of entrepreneurship education, recognize startup as a credit, and build up entrepreneurship education ecosystem through the local area network.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.35-43
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• 2001

As the demands for lightweight construction and precision grow, there is an increasing interest on hydroforming technology. This paper deals with designing automobile subframe for applying welded blanks hydroforming. In applying welded blanks hydroforming to automobile subframe, it is a serious problem that blanks wrinkle in deformed shape. To suppress wrinklings in blanks, the sections of the die where blanks wrinkled is modified. In addition to this, it is intended that the sum of thickness variation about wrinkling regions be minimized. For this purpose, parameters for influencing formability are selected and evaluated using orthogonal array. Among these parameters, parameters having a major effect on formability are selected again. Using CCD(central composite design) with the selected parameters, response surface is build up and optimal design is performed.

• Korea-Australia Rheology Journal
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• 제15권1호
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• pp.27-33
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• 2003

Associating polymers are hydrophilic long-chain molecules to which a small amount of hydrophobic groups (hydrophobes) is incorporated. In aqueous solution, the association interactions result in the formation of three-dimensional network through flowerlike micelles at high concentrations. In colloidal suspensions, the associating polymers act as flocculated by bridging mechanism. The rheological properties of suspensions flocculated by associating polymers end-capped with hydrophobes are studied in relation to the bridging conformation. At low polymer concentrations, the polymer chains effectively form bridges between particles by multichain association. The suspensions are highly flocculated and show typical viscoelastic responses. When the polymer concentration is increased above the absorbance at saturation, the excess polymer chains remaining in the solution phase build up three-dimensional network by associating interactions. Since the presence of particles does not significantly influence the network structures in the medium, the relative viscosity, which gives a measure of the degree of flocculation is decreased with increasing polymer concentration. The bridging conformation and flocculation level vary strongly depending on the polymer concentrations.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제4권2호
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• pp.79-84
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• 2000

The photodegradation of benzene was studied in an aqueous solution using a medium pressure Hg-lamp. In this study, persulfate, nitrate, nitrite, chloride, and sulfate ions were all tested as sensitizers. The persulfate, nitrate, and nitrite ions exhibited a sensitizing effect in the photodegradation of benzene, whereas no detectable effects were observed with the sulfate and chloride ions. When nitrite ions were used as the sensitizer, the photodegradation of benzene ran through a maximum value and thereafter decreased with an increasing nitrite concentration. The resulting build-up of nitrite ions seemed to scavenge the hydroxyl radicals. When nitrite ions were present along with persulfate ions, the photodegradation of benzene was inhibited.

• 품질경영학회지
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• 제41권4호
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• pp.693-708
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• 2013

Purpose: This study is to develop an evaluation model for analysis of CMMS Implementation status and provide CMMS advancement methods to maximize implementation effect through the evaluation model. Methods: After extracting common modules from CMMS packages and establishing evaluation standard for each module, then the evaluation standard is applied to 33 Korean companies for evaluating their own current implementation status. Results: Preventive maintenance and analysis information modules were considered the most vulnerable in Korean companies which have introduced CMMS packages. And the reason why preventive maintenance is vulnerable is that there is poor build-up of their own preventive maintenance standards. Conclusion: Korean companies which will introduce CMMS need to make preventive maintenance standards, and data of the materials and the equipment to improve the effectiveness in advance.

• 한국자동차공학회논문집
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• 제6권1호
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• pp.122-133
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• 1998

This paper presents the static analysis, the modal analysis and the forced vibration analysis on engine structures to find out the structure-borne noise sources by finite element method. The deformation of engine structures under the maximum combu- stion gas force was calculated through the static analysis, and the resonance possibilities were predicted by the modal analysis which ascertains mode shapes and the corresponding frequencies of engine global and its major noise sources in engine surfaces were investigated with the forced vibration analysis by means of finding the transfer mobilities on engine surfaces due to the piston impact and the velocity levels due to the combustion in consideration of oil film stiffness and damping coefficients. Finally, the direction of engine structure-borne noise reduction can be estabilished by the above-mentioned analysis procedure and the reduction effect of cost on proto-type engine build-up is expected.

• 무역상무연구
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• 제54권
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• pp.285-307
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• 2012

This study analyses the transformation of Asian steel trade and the change of corporate strategy. The purpose of this paper is to examine the circumstances of Asian steel industrial policies, and considering the feature of each nation's steel industrial policies, and the effect of the corporate strategy. In China, mighty steel productive capacity had already formed under original planned economy and industrial policy. In 2003, crude steel production have exceeded 220 million ton in China and that is 23.2% of the steel production share in the world. On the other hand, not only the amount but also the quality becomes an important point in the steel industry in the future. I consider, on researching Asian steel industry, it is important to build up partnership in Korea and Japan for achieve strategic alliance in the steel industry policies and understanding the change of corporate strategy.