• 한국철도학회:학술대회논문집
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• 한국철도학회 2006년도 추계학술대회 논문집
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• pp.1354-1363
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• 2006

Until now, NATM(New Austrian Tunneling Method) has been increasingly developed based on concept of making use of ground as support. Also, NATM in its essence is a method of risk based on monitoring behaviour of tunnel. This Monitoring is irreplaceable for the quality construction of tunnel, and safety of tunnel itself. Pre-reinforcement ahead of a tunnel face using long steel pipes in NATM, known as the RPUM(Reinforced Protective Umbrella Method), is the auxiliary method to sustain the stability of a tunnel face and reduce the ground settlements. Since design of RPUM has been dependent on the empirical design, it is necessary to develop the improved design methods. In this study, to understand behaviour of steel pipes, it is monitored displacement of tunnel crown, axial force of rock bolt, displacement and axial stress of steel pipes. Also, in order to clarify the mechanical behaviour and RPUM effects, 3-Dimensional numerical analysis is performed that various cases of different parameter combinations including original length and repeated length of steel pipes, installation width and angle, repeated length of steel. In the results of comparison monitoring with analysis, it is suggested more economical and efficient design technique than empirical design methods.

• 한국철도학회논문집
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• 제11권5호
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• pp.433-440
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• 2008

가상건설기법은 공사대상 시설물을 설계부터 시공까지 3차원 가상공간에서 시행하여, 가상건설과정에서 실제 공사의 문제점을 해결할 수 있는 기법이다. 본 연구에서는 철도연사 시설물을 가상건설기법으로 시공하는 방법론을 구축하였으며, 구축된 방법론에 근거하여 실제 시스템을 개발하여 호남고속철도의 역사 시공과정에 적용하여 실무 활용성을 검증하였다. 연구에서는 시퀀스다이어그램을 이용한 방법론을 통해 레이아웃 리뷰, 레이어 시뮬레이션 기능을 구축하였다. 이러한 기능은 건설프로젝트 정의의 이해를 돕고 3D 시뮬레이션의 효과를 증진시킬 수 있다. 이러한 가상건설기법은 철도역사 시설물의 시공단계 검증 도구로서 공정관리 시각화와 시공 적정성 판단 등의 도구로 활용될 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.737-740
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• 2004

The interior noise reduction of construction equipment is concerned for improving the driver comfort in this study. From the baseline test, the exhaust noise gives a big contribution to the interior noise of construction equipment. And the detail noise contribution analysis of the exhaust system, the tail pipe, which is for ventilation an engine room hot air to outside, amplify the exhaust noise around operating engine RPM associated with tail pipe structural and cavity resonances. To remove the noise amplifying effects, the tail pipe has to be shorted its length. Even the noise can be attenuated the ventilation flux when using the redesigned tail pipe is reduced than the original one. Thus, a shape change of the tail pipe is additionally needed for increasing the ventilation flux and attenuating the exhaust noise using CFD technique. The CFD results of the tail pipe give a meaning full information what obstructs the ventilation flex in the current design and how changes the tail pipe.

• Geomechanics and Engineering
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• 제28권1호
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• pp.65-75
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• 2022

Time and cost of construction are key factors in decision-making during a tunnel project's planning and design phase. Estimations of time and cost of tunnel construction projects are subject to significant uncertainties caused by uncertain geotechnical and geological conditions. The Gaussian Process Regression (GPR) technique for predicting ground condition and construction time and cost of mountain tunnel projects is used in this work. The GPR model is trained with data from past mountain tunnel projects. The model is applied to a case study in which the predicted time and cost of tunnel construction using the GPR model are compared with the actual construction time and cost for model validation and reducing the uncertainty for the future projects. In addition, the results obtained from the GPR have been compared with to other models of artificial neural network (ANN) and support vector regression (SVR) that the GPR model provides more accurate results.

• 한국공간구조학회논문집
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• 제14권2호
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• pp.41-50
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• 2014

The stone pagoda of Mireuk temple site is currently restoring through the repairing process. This stone pagoda has the various construction types in the inner and outer space. Therefore, the stress concentration and structural behavior need to be considered through the analysis of various construction patterns. To this end, this study presents the structural modelling and analysis considering the discrete element analysis technique to solve the discontinuum behavior between the stone elements. Also, this study performs the structural performance evaluation through the various design variables for the safety of stone pagoda. Through the analysis results, we can find out the small stress concentration in the several members. But, because the stresses and displacements are relatively small, we can secure the safety of the whole structure.

• Journal of Power Electronics
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• 제13권6호
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• pp.919-927
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• 2013

This paper proposes a Boundary Current Mode (BCM) control scheme to realize soft switching on a conventional single phase full bridge DC/AC inverter. This technique with the advantages of no auxiliary components, low cost, high efficiency, and simple in control, is attractive for micro-inverter applications. The operation principle and characteristic waveforms of the proposed soft switching technique are analyzed in theory. A digital controller is provided based on that theory. To balance the requirements of efficiency, switching frequency, and inductor size, the design considerations are discussed in detail to guide in BCM inverter construction. A 150W prototype is built under these guidelines to implement the BCM control scheme. Simulation and experiment results demonstrate the feasibilities of the proposed soft switching technique.

• Journal of Construction Engineering and Project Management
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• 제8권1호
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• pp.10-21
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• 2018

Many construction projects involve a plethora of safety-related problems that can cause loss of productivity, diminished revenue, time overruns, and legal challenges. Incorporating data collection and analytics methods can help overcome the root causes of many such problems. However, in a dynamic construction workplace collecting data from a large number of resources is not a trivial task and can be costly, while many contractors lack the motivation to incorporate technology in their activities. In this research, an Android-based mobile application, Preemptive Construction Site Safety (PCS2) is developed and tested for real-time location tracking, trajectory prediction, and prevention of potential collisions between workers and site hazards. PCS2 uses ubiquitous mobile technology (smartphones) for positional data collection, and a robust trajectory prediction technique that couples hidden Markov model (HMM) with risk-taking behavior modeling. The effectiveness of PCS2 is evaluated in field experiments where impending collisions are predicted and safety alerts are generated with enough lead time for the user. With further improvement in interface design and underlying mathematical models, PCS2 will have practical benefits in large scale multi-agent construction worksites by significantly reducing the likelihood of proximity-related accidents between workers and equipment.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2009년도 춘계학술대회
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• pp.439-444
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• 2009

Recently ubiquitous sensor network(USN) technique has been applied into various industrial fields such as construction of u-city, civil and architectural engineering, medical areas. The main objective of this paper is to design a u-health system based on USN. Compared to the previous researches, the proposed system in this paper was designed to activate with collected information about health in outdoor environment.

• 한국건설관리학회논문집
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• 제17권4호
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• pp.40-48
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• 2016

건설산업은 수요층의 질적 성장에 따른 건축물 설계의 다양화가 이루어져 왔다. 하지만 이러한 시도는 중 장기적으로 발생할 수 있는 하자에 대한 인식이 부족하여 오히려 건축물의 가치가 하락하는 문제를 야기하였다. 때문에 건축물의 특성과 하자에 대한 관계를 명확히 할 필요가 있다. 본 연구는 이러한 개념을 건축물 외부에 적용하여 건축물 입면 요소와 하자에 대한 관계를 정량화하는 기법을 제안하였다. 이는 기존에 정성적, 경험적으로 인지했던 입면 요소와 하자의 관계를 정량적으로 제시하여 명확한 관계를 파악할 수 있는 특징이 있다. 본 연구는 이를 픽셀화기법이라 지칭하였으며, 이는 건축물의 입면을 단위구획으로 구분하여 단위구획의 특성에 따른 코드를 부여함으로써 데이터화하는 기법이다. 본 연구에서 제안한 픽셀화기법을 통해 건축물 입면 요소와 하자에 대한 관계를 정량화하고, 이에 대한 능동적 대처 방안의 기틀을 구축하는데 일조하고자 한다.

• 소성∙가공
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• 제12권4호
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• pp.340-347
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• 2003

In the rigid-plastic finite element simulation of hot forging processes using hexahedral mesh, remeshing of a flash is important for design and control of the process to obtain desirable defect-free products. The mesh compression method is a remeshing technique which enables the construction of an effective hexahedral mesh in the flash. However, because the mesh is distorted during the compression procedure of the mesh compression method, when it is used in resuming the analysis, it causes discretization error and decreases the conversance rate. Therefore, mesh smoothing is necessary to improve the mesh quality. In this study, several geometric mesh smoothing techniques and optimization techniques are introduced and modified to improve mesh quality. Then, the most adaptive technique is recommended for the mesh compression method.