• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.10a
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• pp.73-77
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• 1996

정보는 의사결정자들의 수주에 있을 때 기업에 있어 강력한 경쟁무기가 된다. 의사결정자들의 정보에 대한 이러한 필요성을 충족시키기 위해서 데이타는 운영시스템(Operational System)에서 추출되어 데이타웨어하우스에 저장된다. 데이타웨어하우스는 핵심 비지니스영역(key business dimension)에 의해 정리된 historical data를 저장한다. 이러한 의사결정자들을 위한 데이타웨어하우스 정보의 전달은 기존의 클라이언트/서버 시스템 하에서는 많은 지원을 요구한다. 즉 기존 클라이언트/서버 시스템 하에서는 사용자들의 접근을 위해 데이타가 추출되고 조직화되어지고 나면, 반드시 분석 소프트웨어가 각 사용자의 컴퓨터에 설치되어야 하고 외부의 사용자를 위한 새로운 운영자가 고용되어야 한다. 사용자의 다양한 요구 그리고 계속적 사용자의 교체는 사용자 지원에 있어 심각한 기업부담으로 작용한다. 또한 클라이언트/서버 시스템에서는 기업외부의 정보 이용자들에게 정보를 제공하는데 있어 장소적 한계점을 가지고 잇다. 인트라넷과 인터넷은 이러한 클라이언트/서버 시스템 환경의 문제에 대해 해답을 제시한다. 인트라넷은 데이타웨어하우스로의 접근을 간단히 할뿐만 아니라 의사결정자들의 정보의 공유와 상호분석의 새로운 단계를 제공한다. 그리고 인터넷은 기업 외부 어디에서나 기업이 제공하는 정보를 이용하고자 하는 사람들에게 접근의 편의성을 제공한다. 즉 데이타웨어하우스의 목표와 인트라넷, 인터넷의 목표는 데이타로의 손쉬운 접근이라는 점에서 동일하다. 이러한 점에 착안하여 인트라넷과 인터넷하에서 운용되는 데이타웨어하우스 시스템 구축을 위한 방안을 제시하고자 한다.다(학생군:8.16kg 작업자군:12.9kg). 심박수를 이용한 생리학적 연구에서는 평균 심박수가 거의 100 이하를 유지하므로써 피실험자들이 8시간 작업기준으로 보아 무리가 없는 최대허용 하중을 결정하였음을 보였다. 또한 각 운반작업에 대한 최대허용 하중을 예측하는 회귀모형을 제시하였다.아직 정립되어 있지 않은 분산 환경하에서의 관계형 데이타베이스의 데이타관리의 분류체계를 나름대로 정립하였다는데 그 의의가 있다. 또한 이것의 응용은 현재 분산데이타베이스 구축에 있어 나타나는 기술적인 문제점들을 어느정도 보완할 수 있다는 점에서 그 중요성이 있다.ence of a small(IxEpc),hot(Tex> SOK) core which contains two tempegatlue peaks at -15" east and north of MDS. The column density of HCaN is (1-3):n1014cm-2. Column density at distant position from MD5 is larger than that in the (:entral region. We have deduced that this hot-core has a mass of 10sR1 which i:s about an order of magnitude larger those obtained by previous studies.previous studies.업순서들의 상관관계를 고려하여 보다 개선된 해를 구하기 위한 연구가 요구된다. 또한, 준비작업비용을 발생시키는 작업장의 작업순서결정에 대해서도 연구를 행하여, 보완작업비용과 준비비용을 고려한 GMMAL 작업순서문제를 해

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.21-28
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• 2017

Electro-hydraulic sliding deck systems have been developed to reduce the weight for the loading of an agricultural machine. The extension length of the sliding deck was calculated according to the bed's dump angle. The optimum thickness and material were determined using a large and heavy load at acceptable angles. In addition, the degrees of freedom were calculated to obtain the input/output relationship of the system. An equation was derived using a simplified model formula for the extended length of the sliding deck according to the bed's dump angle. Also, the advance length at the maximum and minimum angles of the system was determined using numerical analysis. A down-scaled model of the system was constructed and verified by experiments. The deck was simplified to determine the material and thickness of the sliding deck and for the selection of the two representative materials. The simplified model was tested in deformation tests and stress tests with different thicknesses and materials using a structure analysis program. The analysis results show that ATOS80 is the best among the two materials for reducing the weight of the system.

• Journal of the Korean GEO-environmental Society
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• v.19 no.10
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• pp.35-41
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• 2018

Dynamic interaction of the ground-foundation-structure must be considered for safety of earthquake resistant design for piles supported structures. The p-y curve, which is proposed in the static load and cyclic load cases, is used for the earthquake resistant design of piles. The p-y curve does not consider dynamic interaction of the ground-foundation-structure on dynamic load cases such as earthquake. Therefore, it is difficult to apply the p-y curve to earthquake resistant design. The dynamic p-y curve by considering dynamic interaction of the ground-foundation-structure has been studied, and researches had same conditions that pile caps were on the ground surface and superstructures were added on pile caps for the simple weight. However, group piles are normally embedded into the ground except for marine structures, so it seems that the embedding the pile cap influences on the dynamic p-y curve of group piles. In this study, the shaking table model test was conducted to confirm dynamic behavior of group piles by the embedded pile cap in the ground. The result showed that dynamic behavior was different between two cases by embedding the pile cap or not.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.3
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• pp.189-198
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• 2017

Purpose: This study aims to analyze the stress distribution of mandibular molar restoration supported by the implants with external hex and internal taper abutment connection design. Materials and Methods: Models of external connection (EXHEX) and internal connection (INCON) implants, corresponding abutment/crowns, and screws were developed. Supporting edentulous mandibular bony structures were designed. All the components were assembled and a finite element analysis was performed to predict the magnitude and pattern of stresses generated by occlusal loading. A total of 120 N static force was applied both by axial (L1) and oblique (L2) direction. Results: Peak von Mises stresses produced in the implants by L2 load produced 6 - 15 times greater than those by L1 load. The INCON model showed 2.2 times greater total amount of crown cusp deflection than the EXHEX model. Fastening screw in EXHEX model and upside margin of implant fixture in INCON model generated the peak von Mises stresses by oblique occlusal force. EXHEX model and INCON model showed the similar opening gap between abutment and fixture, but intimate sealing inside the contact interface was maintained in INCON model. Conclusion: Oblique force produced grater magnitudes of deflection and stress than those by axial force. The maximum stress area at the implant was different between the INCON and EXHEX models.

• KEPCO Journal on Electric Power and Energy
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• v.3 no.2
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• pp.79-88
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• 2017

In this paper, the wind tunnel test for the measurement of aerodynamic characteristics of transmission conductors with asymmetric sections is described. A single conductor model and bundled conductor models with ice accreted shapes are tested both in steady and turbulent flow, and the aerodynamic coefficients are acquired. Transmission conductor galloping is a kind of wind-induced vibration which is characterized by primarily vertical oscillation with a very low frequency and a high amplitude. It is well known that transmission conductor galloping is generally caused by moderately strong, steady winds when a transmission conductor has an asymmetric cross-section shaped by accreted ice. Galloping should be considered from the design stage of overhead lines because it can cause severe wear and fatigue damage to attachments as well as transmission conductors. It is reported that there have been normally 20 events of galloping per year in Korea, which may be followed by serious consequences in the electric power system. Therefore, this research is performed to measure aerodynamic characteristics of ice accreted transmission conductors to understand and control transmission conductor galloping so that it would help to prevent unexpected failures and reduce the maintenance costs caused by galloping.

• Journal of the Korean Geotechnical Society
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• v.20 no.7
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• pp.57-68
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• 2004

When an embankment is constructed on soft clay ground, the lateral displacement generally called as lateral flow is generated in the foundation ground. It strongly affects stabilities of structures, such as foundation piles and underground pipes, in and on the foundation ground. The lateral earth pressure induced by the lateral flow is influenced by the magnitude and construction speed of embankment, the geometric conditions and geotechnical characteristics of the embankment, and the foundation ground, and so on. Accurate methods for estimating the lateral earth pressure have not ever been established because the lateral flow of a foundation ground shows very complicated behavior, which is caused by the interaction of shear deformation and volumetric deformation. In this paper, a series of model tests were carried out in order to clarify effects of construction speed of an embankment on the lateral earth pressure in a foundation ground were design. It was found that the magnitude and the distribution of the lateral earth pressure and its change with time are dependent on the construction speed of the embankment. It was found that a mechanism for the lateral earth pressure was generated by excess pore water pressure due to negative dilatancy induced by shear deformation under the different conditions of construction speeds of embankments.

• Journal of the Korean Geotechnical Society
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• v.31 no.10
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• pp.49-60
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• 2015

Since previous studies on the 3-dimensional earth pressure have been conducted focusing on the stability of wall, it is very difficult to find a study on the load transfer to the adjacent ground induced by the 3-dimensional active displacement. Therefore, in this study, we tried to find out the load transfer to the adjacent ground induced by the 3-dimensional active displacement depending on the size of rectangular wall which was defined by the aspect ratio, that is, the ratio of the height to the width of the wall. 3-dimensional model tests were performed in order to measure the distribution and the magnitude of load transfer to surrounding grounds. The transferred load was 17.9~30.6% less than the difference between the 3-dimensional active earth pressure and earth pressure at rest. The transferred load of both vertical and horizontal was maximum at the boundary of the active wall. The load transfer range depended on the normalized height of the active wall, and it was 0.67~1.29w in horizontal direction and 1.0~3.0h in vertical direction. The transferred load in horizontal was maximum at the height of the wall. As the aspect ratio increases the location of the maximum transferred load points becomes higher. The ratio of the transferred load area of 56~79% at 0.25w in horizontal direction and 50~58% at 1.0~1.5 in vertical direction. Diagrams showing the distribution and the magnitude of the transferred load depending on the aspect ratio were suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.133-139
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• 2016

In order to obtain a reasonable value for the thermal load to use in designs, a bridge specimen of a full-size steel box girder (bridge) was manufactured. The temperature data were measured at 21 points in the bridge specimen and 19 points in the steel box bridge. The steel box bridge specimen was installed in a similar direction to a nearby real one. The maximum effective temperatures in the bridge specimen and bridge were calculated for air temperatures in the range of $24^{\circ}C{\sim}38^{\circ}C$. The maximum effective temperature of the bridge specimen and bridge showed correlations of approximately 93.2% and 87.4%, respectively, compared with the Euro code. The maximum effective temperature calculated in this study was very close to the Euro code and the maximum temperature of the Highway Bridge Design Criteria. When the effective temperature obtained in the study is combined with the highest temperature calculated from the Contour map for each region, the design criteria for the thermal load in domestic bridge design, taking into consideration the characteristics of each region, can be established.

• Tunnel and Underground Space
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• v.14 no.1
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• pp.69-77
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• 2004

Investigation of the time-dependent behavior of rock and the associated mechanisms are of key interest in long-term stability analysis of many engineering applications. In this study, creep tests were performed on Daejeon granite samples of 25.4mm diameter under uniaxial compression at varying stress levels. The effect of moisture was investigated by testing both air-dried and fully water-saturated samples. The creep behavior of Daejeon granite exhibited three distinctive stages of primary, secondary and tertiary creep. The ultimate strength of granite under a constant stress decreased considerably with time. Saturation and immersion of the test specimen in water markedly increased the total creep strain as well as the secondary creep rate. The experimental creep curves are fitted to Burger's model as well as two other empirical models suggested by previous researchers. A number of the parameters determined for each model are dependent on stress and influenced by the presence of water. Based on the experimental results, an empirical relation between the applied stress and the time-dependent strain is established separately for each air-dried and fully water-saturated Daejeon granite.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.1
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• pp.51-61
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• 2018

Foundation of tower structures such as wind turbine, pylon, and chimney have to resist considerably large overturning moment due to long distance from foundations to load point and large horizontal load. Pile foundations subjected to uplift force are needed to economically support such structure even in the case of rock layer. Therefore, this research performed the laboratory model tests with the variables, W/C ratio and sand proportion, to evaluate the effect of the mix proportion of grouting material on shaft resistance. In the case of cement paste, maximum and residual shaft resistance were distributed in uniform range irrespective of the changes of W/C ratio. However in the case of mortar, they were decreased with increasing W/C ratio, while they were increased and then decreased with increasing sand proportion. In the case of no sand, the maximum shaft resistance was about 540~560kPa regardless of the W/C ratio. When the sand proportion was 40%, it was about 770~870kPa depending on W/C ratio, which was about 40~50% higher than that without sand. The optimum proportion found in this research was around 40% of sand proportion and 80~100% of W/C ratio.