• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.3
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• pp.21-30
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• 1989

In this study, the dynamic behavior of a continuous bridge under moving load is studied considering roughness of the road surface. Vehicle model includes the spring effects of axes, and due to these effects, equations of motions for the vehicle and bridge are derived in coupled form. And then iteration method is used to solve the equations. In experimental study a bridge model is constructed considering the similarity rule in order that the model exhibits dynamic behavior similar to that of prototype. Three types of roughness such as uneven random roughness, uplift on the approach and piece-wise constant roughness are used to describe road roughness. Through the numerical analysis and experiments, the effects of surface roughness, sprung mass, and velocity on the dynamic behavior of the bridge are examined.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.592-596
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• 2007

본 연구에서는 구조물 전면에서 발생하는 권파와 그 이후 발생하는 처오름과 월파의 유속장을 계측하기 위하여 수리모형실험을 실시하였으며, 실험결과를 이용하여 월파의 유속분포를 나타내는 경험식을 제안하였다. 구조물 전면에서 내습파랑이 쇄파된 이후, 구조물을 월파하는 동안에 유체의 흐름은 넓은 연행기포의 지역을 형성하며 다위상(multiphase)상태가 된다. 쇄파에 의한 구조물 주위에서의 유체흐름 중 연행기포가 없는 영역의 유속 측정에는 입자화상유속계(particle image velocimetry, PIV)기법을, 연행기포 영역에서의 유속 측정에는 기포화상유속계(particle image velocimetry, BIV)기법을 적용하였다. 두 기법을 이용하여 측정된 유속장으로부터 구조물 주위에서의 쇄파, 처오름 및 월파시의 최대유속을 계측하였다. 구조물 위로 월파된 유체 흐름 분포는 비선형적인 특성을 보여주며, 시간별 최대유속은 주로 유체의 전면부에서 발생하는 것으로 나타났다. 또한 무차원화된 유속분포로부터 구조물 위에서의 월파시 유속분포가 자기상사성(self-similarity)을 갖는다는 것을 알 수 있었으며, 이를 이용하여 월파의 유속분포를 위한 실험적 경험식을 제시하였다.

• The Journal of the Korea Contents Association
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• v.8 no.8
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• pp.223-234
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• 2008

This study aims to understand the relation between the perceived social exchange of employees in service industry, which is focused on food service industry, and the organizational citizenship behavior, and to consider the efficiency of human resources management in service industry. To achieve the purpose of this study, a documentary study and an empirical study based on a structural equation model analysis were carried out. In this study, the social exchange consist of perceived leader support, perceived coworker support, and perceived organization support. Also the organizational citizenship behavior consist of organizational citizenship behavior for individual and organizational citizenship behavior for organization. And then, the relation between the variables was found out. Finally, based upon the results of analysis, this study was suggested for human resources management in service industry.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.1
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• pp.8-15
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• 2014

In this study, flow characteristics around the hull form of KLNG are investigated by numerical simulations. The numerical simulations of the turbulent flows with the free surface around KLNG have been carried out at Froude number 0.1964 using the FLUENT 6.3 solver with Reynolds stress turbulence model. Several GEOSIM models are adopted to consider the scale effect attendant on Reynolds number. Furthermore, a full scale ship is calculated and the result is compared with the numerical results of GEOSIM models. The calculated results of GEOSIM models and the full scale ship are compared with the experiment data of MOERI towing tank test and Inha university towing tank test. Moreover, wake distribution on the propeller plane of the full scale ship is estimated using the numerical results of GEOSIM models. The prediction result is directly compared with the simulation result in full scale.

• Korean Business Review
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• v.13
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• pp.31-47
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• 2000

Trust has been viewed from many perspectives according to their domains. This article reviewed some of many formerly suggested studies and models. And antecedents of trust, such as trustworthiness(ability, benevolence, integrity) and individual trust propensity as well as their interactions, were respectively and empirically tested in the context of Korean workplaces. Through the factor analysis of field survey(N=243), proposed conceptual independence in trustworthiness was only partially supported. Of the relationships between antecedents and trust, all components of trustworthiness were significantly sustained. While effects of individual trust propensity and its interactions with trustworthiness on trust were not found.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2006.03a
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• pp.545-552
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• 2006

Small-scale models have been frequently used for seismic performance tests because of limited testing facilities and economic reasons. However, there are not also enough studies on similitude law for analogizing prototype structures accurately with small-scale models, although conventional similitude law based on geometry similitude is not well consistent in their inelastic seismic behaviors. When fabricating prototype and small-scale model of reinforced concrete structures by using the same material, added mass is demanded from a volumetric change and scale factor could be limited due to aggregate size. Therefore, it is desirable to use different materials for small-scale model. In our recent study, a modified similitude law was derived depending on geometric scale factor, equivalent modulus ratio and ultimate strain ratio. And quasi-static and pseudo-dynamic tests on the specimens are carried out using constant and variable modulus ratios, and correlation between prototype and small-scale model is investigated based on their test results. In this study, tests on scaled model of different concrete compressive strength aye carried out. In shaking table tests, added mass can not be varied. Thus, constant added mass on expected maximum displacement was applied and the validity was verified in shaking table tests. And shaking table tests on non-artificial mass model is carried out to settle a limitation of acceleration and the validity was verified in shanking table tests.

• Journal of the Korean GEO-environmental Society
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• v.10 no.5
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• pp.19-26
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• 2009

Rammed Aggregate Pier (RAP) method is intermediate foundation between deep and shallow foundation, and it has been built in world wide. RAP represents a relatively new method that has grown steadily over 19 years since Geopier of USA developed this revolutionary method in 1989. The investigation and research in domestic is not accomplished. In this paper, the examined details of different spacing of piles, bearing capacities, respectively, conclude with recommendations on how RAP can be used in future needs. This documentation further provides comparisons of the laboratory test results which were obtained from changing the spacing of piles, namely installed rammed aggregate pier. Laboratory model test was administered in a sand box. Strain control test was conducted to determine the bearing capacities of the piers; 20 mm, 30 mm and 40 mm RAP in diameter using drilling equipment to make holes were installed in sand at initial relative densities of 40%. By comparing different spacing of piles, in this experiment, piles are spaced structually span, form a ring shape, narrowing the distance of each other, to the center. the result shows that as diameter of pier is bigger in diameter, bearing capacity also dramatically increased due to raised stiffness. Also, as the space between each piers was closed, the settlement rate of soil was decreased significantly. From the test results, as the space between each piles were getting closer, it allows greater chances to have more resistance to deformation, and shows more improved stability of structures. After from the verification work which is continuous leads the accumulation of the site measuring data which is various, and bearing capacity and the settlement is a plan where the research will be advanced for optimum installed RAP.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.74-74
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• 2015

최근 홍수의 특성과 피해 양상은 과거와는 다르게 변화하고 있으며, 급격한 도시화로 인하여 기존 하천유역의 저류 능력이 감소하였으며 이러한 한계를 극복하기 위하여 이미 외국에서는 대심도 터널을 활용한 홍수재해 관리방안이 오래전부터 활용되어 왔다. 본 연구에서는 대심도 터널의 유입구, 수직갱, 감세지, 배수터널과 같은 시설물 중 대심도 터널 설계 시 수직 유입구를 통해 유입되는 유량의 에너지를 완화하고 효과적으로 배수 할 수 있도록 중요한 역할을 하는 감세지의 효율적인 깊이 산정을 위하여 수리모형실험을 실시하였으며, 모형은 Froude 상사법칙을 사용하여 원형의 1/18크기로 제작하였다. 본 연구에서 실시한 감세지 모형의 깊이는 0.278 m(원형 5.0 m), 0.417 m(원형 7.5 m)이며, 각 감세지 깊이별 수직 유입구 3개소(저지수직구1, 저지수직구2, 고지수직구) 및 5가지의 유량 CASE에 대하여 감세지 바닥면 압력을 비교?분석 하였다. 수직 유입구 3개소의 설계조건에 따른 감세지 깊이별 바닥면 압력 분포 평가를 실시한 결과 저지수직구1의 감세지 깊이 0.278 m(원형 5.0m)에서는 최대 압력이 4번 지점에서 $0.075kg/cm^2$(원형 1.30 MPa)이 측정 되었으며, 0.417 m(원형 7.5m)에서는 최대 압력이 1번지점에서 $0.089kg/cm^2$(원형 1.54MPa)이 측정되었다. 또한 저지수직구2의 감세지 깊이 0.278 m(원형 5.0 m)에서는 최대 압력이 1번 지점에서 $0.074kg/cm^2$(원형 1.28 MPa)이 측정 되었으며, 0.417 m(원형 7.5 m)에서는 최대 압력이 2번지점에서 $0.088kg/cm^2$(원형 1.52 MPa)이 측정되었다. 고지수직구의 감세지 깊이 0.278 m(원형 5.0 m)에서는 최대 압력이 3번 지점에서 $0.082kg/cm^2$(원형 1.42 MPa)이 측정 되었으며, 0.417 m(원형 7.5 m)에서는 최대 압력이 1번지점에서 $0.092kg/cm^2$(원형 1.59 MPa)이 측정되었다. 본 연구에서 실시한 수리모형실험의 결과 저유량에서 고유량으로 갈수록 최대압력지점은 반시계방향으로 움직이는 것을 알 수 있으며, 이는 수직 유입구의 설계조건에 따른 수직갱에서의 회전수차에 의하여 발생하는 것으로 분석하였다. 따라서 적절한 감세지 깊이 산정을 위해서 대심도터널의 수직 유입구(유입구형태, 수직갱)의 평가가 함께 유기적으로 이루어져야 할 것으로 판단된다.

• Journal of the Korean GEO-environmental Society
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• v.12 no.10
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• pp.83-90
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• 2011

A series of centrifugal model test was conducted to investigate the distribution of vertical earth pressure on circular ductile underground corrugated steel plate waterway culvert with considering the compaction degree of the backfill in the high landfilled embankment section. The compaction degree of backfill was varied to 80, 85, 90, and 95% at the 53g-level gravity considering the similarity of the site. As a result of this test, the load reduction factor by the arching effect of the top of corrugated steel plate showing ductile behavior nearly agreed with the load reduction factor according to the compaction degree of backfill specified in the AISI(2002) design method. The vertical earth pressure measured at the top of the corrugated steel plate was linearly decreased as the compaction degree increased. The greater the compaction degree of backfill was, the greater the reduction of surface loading on the top of the corrugated steel plate by arching effect. The load decreased by arching effect on top of the corrugated steel plate was transferred to the side backfill of the corrugated steel plate(EP 1) and the outside of backfill(EP 3).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.192-203
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• 2016

The purpose of this study is to investigate the effects of task conflict on job attitudes (organizational commitment & job satisfaction), focusing on the mediating effects of supervisory communication & co-worker communication. Recently, the importance of communication as a research topic has been increasing. According to prior research, communication satisfaction has a positive effect on job performance. However, studies which take into account the different types of communication are lacking. Therefore, this study considered two types of communication (supervisory communication and coworker communication). A research model and hypotheses were developed in order to examine the theoretical research issues and questions. The sample consisted of 280 survey data drawn from employees in firms located in Korea. The data was analyzed by the statistical packages, SPSS 21.0 & AMOS 21.0 for Windows. The findings of the analysis are as follows. Firstly, it was found that task conflict had a negative (-) effect on organizational commitment & job satisfaction. Therefore, H1a & H1b are supported. Secondly, it was found that task conflict had a negative (-) effect on supervisory communication. Therefore, H2a is supported. However, it did not have a significant effect on co-worker communication. Hence, H2b is not supported. Thirdly, as regards the mediating effect of supervisory communication, it was found that supervisory communication mediated the effect of task conflict on job attitudes (organizational commitment & job satisfaction). Therefore, H3a & H3b are supported. Finally, the mediating effect of co-worker communication was not significant. Therefore, none of the sub-hypotheses of H4 are supported. Based on these findings, this study suggested directions for future research.