• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.331-336
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• 2011

The three-dimensional complex curvature of the airfoil complicates the manufacture and repair of gas-turbine components. As a result of the developments in computer technology since the early 1990s, CNC-based technologies for machine tools and related programs have been increasingly applied in the gas turbine industry. In particular, fiveaxis simultaneous machines with adaptive functions have proven its excellent flexibility and productivity due to the capability in determining the 3D data from the unknown curvature. A well-organized robot system with eight-axis simultaneous control can lead to powerful standardization and high productivity. We summarize and review CNC technologies and their applications in the gas turbine industry, with a discussion of the manufacture and repair of gas turbine parts.

• Journal of the Korean Society of Hazard Mitigation
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• v.2 no.3 s.6
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• pp.109-117
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• 2002

An analysis to allocate storage space for sediment accumulation during the economic life of the reservoir is required in the planning or design of a reservoir. This analysis has been the most difficult and tedious aspect to deal with reservoir sedimentation because of the interaction between the various parameters related to the hydraulics of flow, reservoir operating policy, inflowing sediment load. The approach to analyzing spatial distribution of deposits has relied on empirical methods, all of which required a great deal of simplification from the actual physical phenomena. For the purpose of this study, reservoir sedimentation rate computed by Empirical Area Reduction Method is compared with measuring rate along the Soyang-gang Dam. As a conclusion, reservoir sedimentation rate can be estimated exactly by Empirical Area Reduction Method.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1344-1348
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• 2008

HMS(Hydrological Modelling system)는 유역의 지형자료와 강우와 같은 기상관련 시계열 자료 등 수문 유출과 관련되는 많은 매개변수를 포함하고 있으며, 모형의 구동을 위해서는 다양한 공간 비공간 자료 및 시계열 자료가 요구된다. 특히 다양한 비공간 정보의 경우 이를 모형에 적용하기 위해서는 비공간 정보에 대한 열람, 선택, 편집, 적용 시나리오의 설정, 입력변수의 적절성 평가, 모형 구동결과의 검 보정 등 복잡한 절차가 필요하다. 최근 들어 공간자료의 효율적 처리를 위해서 지리정보시스템과 수리 수문모델들 간의 연계를 통한 자료 생성과 입력 및 분석과정을 일괄적으로 처리하고자 하는 연구들이 발표되고 있다. 본 연구에서는 한국형 수자원지리정보시스템인 HyGIS와 HMS 모형의 연계 시스템인 HyGIS-HMS의 개t선과 적용성 평가를 목표로 하고 있다. 이를 위하여 HyGIS-HMS 데이터 모델을 기반으로 하는 시스템의 운영 프로세스를 재정립하였다. HyGIS에서 구축된 공간 DB를 이용하여 HMS 모형의 입력 지형인자를 계산하고 있으며, 수문시계열 자료는 HyGIS의 시계열 DB를 이용하고 있다. HMS에서는 공간 자료와 시계열 자료 외에도 다양한 비공간 자료를 이용하고 있다. 이러한 비공간 정보를 DB기반 시스템에 맞추어 효과적으로 관리 및 사용하기 위하여 HyGIS-HMS에서는 Static DB를 이용하고 있으며, Static DB에서 모형의 입력자료로 직접 이용되는 자료와 모형의 수행결과는 Dynamic DB를 이용하고 있다. 또한 개발된 시스템을 경안천 유역에 적용하여 2006년과 2007년의 유출특성을 분석하였다. 이러한 개발환경의 적용을 통해 HyGIS 데이터모델과 HyGIS-Model의 운영환경이 HyGIS-HMS개발에 효과적으로 이용될 수 있는 것으로 나타났다.

• Korean Journal of Construction Engineering and Management
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• v.7 no.1 s.29
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• pp.80-88
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• 2006

Construction graphical simulations usually do not reflect physical properties of construction equipment and material because there are restricted to the geometric model. The complete description of construction operations is difficult for graphical simulation without a physical modeling. The object of this research is to enhance the functionality of restricted simulation system to geometric model. And research is conducted to overcome the limitation of current construction graphical simulation system through the connection geometric model and physical model with the physical properties of construction equipment and material such as crane's cable oscillation. The motion equations for the oscillation of crane cable as a result of the trolley's movement and the boom's rotation were derived. The equations were solved through numerical analysis and the results were simulated visually. The realistic description with physical modeling of construction operations will contribute for ensuring preliminary against risks and improving constructability as well as the application of various fields.

• Journal of the Korea Convergence Society
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• v.9 no.5
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• pp.21-26
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• 2018

In this study, HRD-NET (http://hrd.go.kr), a vocational and training integrated computer network operated by the Ministry of Employment and Labor, is used to confirm whether job training information required by job seekers is being provided smoothly The question bulletin board was extracted using 'R' program which is optimized for big data technique. Therefore, the effectiveness, appropriateness, visualization, frequency analysis and association analysis of the vocational training system were conducted through this, The results of the study are as follows. First, the issue of vocational training card, video viewing, certificate issue, registration error, Second, management and processing procedures of learning cards for tomorrow 's learning cards are complicated and difficult. In addition, it was analyzed that the training cost system and the refund structure differentiated according to the training occupation, the process, and the training institution in the course of the training. Based on this paper, we will study not only the training system of the Ministry of Employment and Labor but also the improvement of the various training computer system of the government department through the analysis of big data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.813-820
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• 2010

The vertical roller mill is important for machine grinding and mixing various crude materials in the process of producing Portland cement. A vertical roller mill is subjected to cyclic bending stress because of the roller load. Because of the cyclic bending stress, only $4{\times}10^6-8{\times}10^6$ cycles are achieved instead of $4{\times}10^7$ cycles. The stress also causes fractures at the edge of grinding path of the outer roller. The expenses incurred in repairing the grinding path amounts to 30% of the total maintenance cost. Therefore, it is desirable to redesign the vertical roller mill in order to reduce the expenses incurred in repairing the roller. In this study, artificial neural networks (ANNs) were applied in order to solve the multiobjective optimization problem for vertical roller mills by using the function approximation ability of ANNs. To learn and generalize ANNs, the maximum and minimum stresses were estimated from the results of the finite-element analysis of a vertical roller mill. Thus, ANNs could be applied to solve the multiobjective optimization problem.

• Journal of KIISE:Information Networking
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• v.32 no.3
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• pp.350-358
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• 2005

Recently, VoIP technology is being accepted as are the most promising Internet telephony service, due to the substitution effect of traditional telephony service. Two standards, i.e, . H.323 and SIP. have emerged for signaling and control for Intemet telephony, of which SIP provides far lower complexity and rich extensibility. It is important to secure components of SIP in order to develop various services. Generally, open source codes provide basic functions of SIP as well as complicated structure, but are difficult to extend. In this thesis, we focused on offering interface mechanism between application and SIP User Agent to easily extend for various VoIP services. This thesis describes what function is needed for SIP User Agent, how to define the internal data structure, and how to define the internal processing procedure. The check iist derived through participating the interoperability event for stabilized SIP User Agent is also suggested.

• The KIPS Transactions:PartD
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• v.8D no.5
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• pp.581-586
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• 2001

An increasingly important facet of software development is the ability to estimated the associated coast and effort of development early in the development life cycle. In spite of the most generally sued procedures for estimation of the software development effort and cost were linear regression analysis. As a result of the software complexity and various development environments, the software effort and cost estimates that are grossly inaccurate. The application of nonlinear methods hold the greatest promise for achieving this objects. Therefore this paper presents an RBF (radial basis function) network model that is able to represent the nonlinear relation for software development effort, The research describes appropriate RBF network modeling in the context of a case study for 24 software development projects. Also, this paper compared the RBF network model with a regression analysis model. The RBF network model is the most accuracy of all.

• Journal of the Korea Society for Simulation
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• v.27 no.3
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• pp.53-63
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• 2018

Since warfare surroundings getting complex and diverse in the future, it is not simple to make appropriate structures and organizations for military groups along the phenomenon. Therefore, this study proposes a methodology of verification for army staff's structure and organization by units in the future using System Dynamics(SD). The procedure of using SD for the verification is a calculation of database(DB), the design of causal loop diagram, and the simulation and analysis. First, DB such as individuals' workload and time is calculated through observation after a real group of staff. Second, the causal loop diagram is considered by a flow of task, and it is modeled. Third, the DB is entered into the model and simulated for analyzing of appropriacy. This study used Powersim program for designing the SD model. One of the weaknesses of the methodology of this study is possibilities of a different result by the DB by observers and perspectives by analysts. As supplementation for the weakness, this study includes research analysis and surveys for the total analysis. The meaning of this study is that it suggests a methodology of warfighting experimentation to analyze structure and organization of military groups with quantifying suitability in the scientific method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5B
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• pp.268-274
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• 2008

With the advances in wireless communication technologies, mobile users require to get seamless services anywhere and anytime. To relize these demands, network interworking and vertical handover are necessary between heterogeneous wireless access technologies with multi-interface mobile station. A lot of organizations are doing research on the network integration schemes based on loosely and tightly integrated architectures, and research on vertical handover schemes mainly based on Mobile IP in loosely integrated environments. But actually, the tightly integrated scheme can support more faster vertical handover because heterogeneous access networks are combined tightly. However, vertical handover schemes in tightly integrated environments are conceptually proposed without any detail signaling procedures. Therefore, this paper defines a tightly integrated architecture between UMTS and WLAN, and proposes a soft vertical handover signaling procedure. The proposed soft vertical handover scheme is evaluated by the OPNET simulator, and we confirm the proposed scheme can support seamless services.