• 한국측량학회지
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• 제16권2호
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• pp.177-185
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• 1998

도시계획이나 설계에 있어서 건물에 대한 3차원자료와 건물 경계선에 대한 요구가 증가되고 있으며 본 연구에서는 DSM과 입체 항공사진영상을 이용하여 건물을 추출하는 방법을 제시하였다. DSM은 DEM과 같이 지형에 대한 정보를 갖고 있을 뿐만 아니라 주변 지형보다 높은 지상 시설물, 즉 건물이나 나무에 대한 정보도 갖고 있다. 따라서 본 연구에서는 두 단계 처리과정을 제시하였으며, 첫 번째 과정은 최우추정과 동적 프로그래밍을 이용한 매칭기법에 의해 DSM을 생성하는 것이다. 제시된 영상정합기법은 입체영상간의 시차차를 찾기 위해 비용함수를 이용하였으며, 영상정합문제 해결을 위해 동적 프로그래밍을 이용하였다. 두 번째 과정은 Sobel 연산자에 의해 항공사진영상으로부터 추출된 경계선정보와 DSM을 이용하여 건물 경계를 검출하는 것이다. DSM과 Sobel 연산자에 의한 경계선 정보를 중첩분석 한 결과 건물 경계를 효과적으로 추출 할 수 있었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.197-200
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• 2002

In this paper, roll damping coefficients for a non-conventional cross section, which is herein named as 'step' model, are investigated numerically and experimentally. Experiments are extensively carried out to estimate the roll damping coefficients. Numerical estimations are also made with the help of numerical codes. For convenience, the roll damping is divided into wave-making component and viscous component. The wave-making component is determined using a potential code and the viscous component using a viscous flow code, in which the fluid domain is taken as unbounded. In order to validate the present approach, a typical cross section with bilge is considered and our results are compared with published data. The comparison shows a good agreement qualitatively. For the step model, numerical results are compared well with experimental data besides some quantitative discrepancies at a certain range of frequency. It is thought that the discrepancy might be caused by the ignorance of the free surface in viscous computations. It is found in the case of the step model that not only the viscous component but also the wave component increases considerably compared to the section with bilge.

• 경영과학
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• 제18권2호
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• pp.125-134
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• 2001

This paper is concerned with the development of a GIS-based distribution system with service consideration. The proposed model could be used for a wide range of logistics applications in planning, engineering and operational purpose for logistics system. This research addresses the formulation of those complex prob1ems of two-echelon logistics system to plan the incorporating supply center locations and distribution problems based on GIS. We propose an integrated logistics model for determining the optimal patterns of supply centers and inventory allocations (customers) with a three-step sequential approach. 1) First step, Developing GIS-distance model and stochastic set-covering program to determine Optimel pattern of supply center location. 2) Second step, Optimal sector-clustering to support customers. 3) Third step, Optimal vehicle rouse scheduling based on GIS, GIS-VRP In this research we developed GUI-tree program, the GIS-VRP provide the vehicle to users and freight information in real time. We applied a set of sample examples to this model and demonstrated samp1e results. It has been found that the proposed model is potentially efficient and useful in solving multi-depot problem through examples. However the proposed model can provide logistics decision makers to get the best supply schedule.

• Journal of Advanced Marine Engineering and Technology
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• 제23권1호
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• pp.9-18
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• 1999

The present study is aimed to investigate flow characteristics of two-dimensional backward-fac-ing step by numerical approach. A convection conservation difference scheme based upon SOLA algorithm is used for the solution of the two-dimensional incompressible Navier-Stokes equations to simulate the laminar transitional and trubulent flow conditions at which the experimental data can be available for the backlward-facing step. The twenty kinds of reynolds number are used for the calculations. In an effort to demonstrate that the reported solutions are dependent on the mesh refinement computations are performed on seven different meshes of uniformly increasing refinement. also to investigate the result of inflow dependence two kinds of the inflow profile are chosen for the laminar flow. Irregular grid is adopted to minimize the errors on the satis-faction fo the discretized continuity. As criterion of benchmarking the result of numerical simula-tion reattachment lengthis used for the selected Reynolds numbers. The results of the present study prove the fact that the numerical predictions agree well with the experimental data and the flow characteristics are shown at the backward-facing step.

• 산업경영시스템학회지
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• 제30권2호
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• pp.67-74
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• 2007

The objective of this research is to select the most effective technique among task related techniques(motion & time study, job redesign, physical environment improvement) for improving work efficiency in shipbuilding enterprise. This study consists of several principal steps. The first step is to design critical criteria in evaluating work efficiency in ship-building enterprises. The second step is to develop sub-criteria of the critical criteria. The third step is to develop a four level AHP(Analytic Hierarchy Process) structure using the critical criteria, sub-criteria and techniques among task related techniques. The fourth step is to develop the pairwise comparison matrix at each level of AHP structure, which was based on survey data collected at the H heavy industry. And the last step is to select the most effective technique among task related techniques using AHP analysis. The result of AHP analysis has shown clear difference in priority among task related techniques in terms of work efficiency of the shipbuilding enterprise: The reduction of normal time is more important than the reduction of allowance time in improving of the work efficiency. Motion & time study is the most important technique for the reduction of normal time, and physical environment improvement is the most important technique for the reduction of allowance time as well.

• 품질경영학회지
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• 제18권2호
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• pp.25-32
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• 1990

This paper presents an approximate algorithm for computing Fault-tree probabilities. The method is essentially composed of three steps. In the first step, a Fault-tree is converted into a network form. In the second step, We change the network into a parallelized diagram. In the third step, the approximate fault-tree probability is calculated from the parallelized diagram. In this paper, in order to verify the method two hypothetical Fault-tree is used by examples. The results show that the method is very useful, even though it is an approximate technique, since it needs not to search the minimal cut sets and has the simple computing rontines.

• 천문학회지
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• 제34권4호
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• pp.237-241
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• 2001

Our goal is to present a simple volume-of-fluid type interface-tracking algorithm to compressible two-phase flow in two space dimensions. The algorithm uses a uniform underlying Cartesian grid with some cells cut by the tracked interfaces into two subcells. A volume-moving procedure that consists of two basic steps: (1) the update of volume fractions in each grid cell at the end of the time step, and (2) the reconstruction of interfaces from discrete set of volume fractions, is employed to follow the dynamical behavior of the interface motion. As in the previous work with a surface-tracking procedure for general front tracking (LeVeque & Shyue 1995, 1996), a high resolution finite volume method is then applied on the resulting slightly nonuniform grid to update all the cell values, while the stability of the method is maintained by using a large time step wave propagation approach even in the presence of small cells and the use of a time step with respect to the uniform grid cells. A sample preliminary numerical result for an underwater explosion problem is shown to demonstrate the feasibility of the algorithm for practical problems.

• International Journal of Reliability and Applications
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• 제2권4호
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• pp.269-280
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• 2001

The objective of this paper is to provide a model for effective implementation of costing RAM management in the design and procurement of production facility considering the system cost-performance trade-off. This research proposes a two-step approach of costing RAM design and test of system RAM for production facility. In Step 1, a static model is proposed to find an initial system configuration to meet the required performance based on system RAM and LCC and analyzes the trade-off relationships between various factors of RAM and LCC. In the second Step, we developed time and failure truncated models for system reliability test and analysis. For the computational purpose, we developed computer programs and have shown the sample results. By the sample test run, the proposed model has shown the possibilities to provide a good method to analyze system performance evaluation for both design and operational phase, This model can be applied to a wide variety of systems not only for costing RAM of the production facilities but also for the other kinds of equipment.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• 제11B권2호
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• pp.28-33
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• 2001

The subject of this study is to improve the position performance of the linear motion for hybrid type Linear Pulse Motor (HLPM). Generally, there are two applicable methods to ensure precise position control ; a good processing method. This paper is suggested an electrical 125 microstep driving method so as to achieves the excellent control performance, besides the small mechanical manufacture of teeth pitch. The compensation method of digital PI control is apply to step response of stable position control, step error, vibration suppression and the approach to high stability, and the Ziegler-Nichols tuning method is applied to the proper design of control parameter. The proposed control method has been verified by simulation results of the suitable gain and phase margin of bode plot, and from experiment result of step response.

• 대한족부족관절학회지
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• 제13권1호
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• pp.60-67
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• 2009

Purpose: This study was designed to investigate the usefulness of extensile lateral approach for accurate reduction and rigid internal fixation in comminuted intraarticular fractures of calcaneus. Materials and Methods: From October 2002 to May 2007, we managed 55 patients (62 cases) with open reduction and internal fixation using extensile lateral approach. Among these, 38 patients (43 cases) who underwent preoperative and postoperative CT scan were enrolled. All patients were evaluated over 24 months after surgery. Bohler angle and Gissane angle on plain X-ray, displacement and step-off of articular surface of calcaneus on CT scan were measured and we compared the difference between preoperative and postoperative value of them. Clinical results were assessed by using AOFAS Ankle-Hindfoot Scale. Results: The average Bohler angle was restored from $6.8^{\circ}$ to $23.5^{\circ}$ and Gissane angle was improved from $116.4^{\circ}$ to $113.5^{\circ}$ after operation. The average distance of displacement was restored from 4.2 mm to 1.4 mm and step-off of articular surface was recovered from 5.1 mm to 1.3 mm. Clinical results were excellent in 17 cases, good in 18 cases, fair in 3 cases, and poor in 5 cases. 10 cases developed postoperative complications such as skin necrosis, heel pain, limitation of motion of ankle and subtalar arthritis. Conclusion: The extensile lateral approach is valuable for the comminuted intraarticular fractures of calcaneus that enables accurate anatomical reduction and rigid internal fixation by providing direct exposure of subtalar joint.