• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2311-2313
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• 1999

웨이블렛 기법은 비주기적 신호의 해석에 있어 새롭게 적용되고 있는 방법이다. 이 방법은 Fourier Transform(FT), the Fast Fourier Transform(FFT), Least Square Method 방법과는 달리 시간 -주파수 분석을 통해 비주기적 과도 신호의 감지와 특징 추출이 용이하다. 이에 본 연구에서는 이러한 통계적 기법과는 달리 부분 방전 발생 신호를 시간-주파수 영역에서 연속적으로 분석 가능한 웨이블렛 기법을 이용하여 시간에 따른 절연체의 열화를 해석 및 진단하기로 한다. 부분 방전 현상을 나타내는 데이터는 방대하므로 진단을 위해 해석 정보에서 특정한 특징을 추출하며 이를 바탕으로 체계화된 데이터 베이스를 구성하는 기반을 마련한다. 해석에 필요한 신호는 복합감지 시스템(부분방전 시스템, 음향방출 시스템)을 이용하여 수집하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.5
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• pp.1020-1025
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• 2007

EMS(energy management system) and SCADA(supervisory control and data acquisition) systems are used for reliable and efficient operation of electrical power systems. Various functions in EMS such as power flow, contingency analysis, security analysis essentially need accurate data set for reliable operation. State estimation can be a tool for providing these data. In this paper, programs for observability analysis and bad data processing are developed. Fundamental algorithms are introduced and validity of the proposed techniques is inspected with test cases.

• Nuclear Engineering and Technology
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• v.15 no.2
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• pp.123-134
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• 1983

Estimates of the rate of heat removal from the containment atmosphere following a loss of colant accident (LOCA) are important to the prediction of containment peak pressure and temperature which are essential parameters in designing the containment building. An overall survey and discussion of mechanisms, experimental results, empirical correlations and analytical models that are relevant to the heat transfer inside the containment have been made. As a result of this review, the current state of the knowledge about tile containment heat transfer can be understood and it is known that more investigations are needed to avoid the misuse of various correlations.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.211-220
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• 2012

The numerical modeling and simulation have been used increasingly as tools for examining and interpreting the bulk structure and properties of materials. The use of molecular dynamics (MD) simulations to model the structure of materials is now both widespread and reasonably well understood. In this research, we introduced the numerical method to calculate the physico-chemical properties such as a diffusion coefficient and a viscosity of clay mineral. In this research, a series of MD calculations were performed for clay mineral and clay-water systems, appropriate to a saturated deep geological setting. Then, by using homogenization analysis (HA), the diffusion coefficients are calculated for conditions of the spatial distribution of the water viscosity associated with some configuration of clay minerals. This result of numerical analysis is quite similar to the previous experimental results. It means that the introduced numerical method is very useful to calculate the physico-chemical properties of clay minerals under various environmental conditions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.4
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• pp.409-415
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• 2010

A finite element model for punching shear of flat plate structures is presented. A parametric study also has been conducted to verification of influence of several parameters in terms of the flexural reinforcement ratio, slab thickness. Reisnner-Mindlin assumptions are adopted to consider of shear deformation. Layered shell element is considered for the material non-linearities. The finite element model of this study was verified comparing with existing experimental results. The model is able to predict the capacity of the flat plate structures. The punching shear of flat plate structures varied depending on the flexural reinforcement ratio, slab thickness.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.225-225
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• 2022

수자원의 계획 및 설계에 활용되는 홍수량 산정 방법은 홍수량 빈도해석 방법과 강우-유출 모형에 의한 방법으로 구분된다. 홍수량 빈도해석에 의한 방법은 홍수량 자료를 직접 빈도해석 하여 확률홍수량을 산정하며 이론적으로 가장 정확한 방법으로 평가된다. 기존의 홍수량 해석은 자료의 제약으로 인하여 실측유량의 직접 빈도해석은 한계가 있었으나 과거부터 국가적으로 수문조사를 수행하여 10년 이상의 실측유량 자료를 확보할 수 있는 수준에 도달하였다. 본 연구는 수위-유량 관계 곡선식을 통하여 안정적으로 확보된 실측유량 자료를 활용하여 홍수량 빈도해석을 수행하였다. 홍수량 빈도해석을 위하여 Bayesian 기법을 적용하여 매개변수를 산정하고 빈도별 홍수량의 불확실성을 정량화하였다. 확률홍수량 산정 결과는 장기간의 강우량 자료를 적용하여 강우-유출모형으로 산정된 홍수량과 근접한 것을 확인하였다. 수문조사를 통하여 장기간의 실측유량 자료를 활용하여 다각적인 관점으로 수문해석을 가능할 것으로 판단된다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.6
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• pp.1-8
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• 2004

The objective of this study is convergence acceleration of multigrid Navier-Stokes solvers. This study has been performed to enhance the performance of preconditioned multi-stage time stepping method which is a popular smoother for the multigrid Navier-Stokes solvers. Comparative study on the convergence characteristics of the ADI and DDADI preconditioners has been conducted. It is shown that the DDADI preconditioner has better performance than the ADI by numerical tests on the 2-D compressible turbulent flows past airfoils. The Spalart-Allmaras turbulent model and the Baldwin-Lomax turbulent model have been compared with the multigrid calculations.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.3
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• pp.36-46
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• 1998

Shock-wave in a supersonic diffuser flow cannot be stable even in the given pressure ratio which remains constant over time, and oscillates around a certain time-mean position. In the present study, oscillation of a normal shock-wave in a supersonic diffuser was analyzed by a small perturbation method. Upstream pressure perturbation was applied to a supersonic diffuser flow with a normal shock-wave. Stability of shock-wave was investigated by considering the diffuser pressure recovery and frequency of the pressure perturbation. The results obtained show that a stable oscillation of weak normal shock-wave is obtainable for the flow with the Mach number over 1.74. The ratio of sound pressures downstream to upstream of the shock wave increases with increase of the Mach number. The present results agree well with other analytical and experimental results.

• Journal of Korean Society of Steel Construction
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• v.25 no.5
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• pp.509-518
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• 2013

This study is aimed at developing of the sustainable interface module for structural design. It is dealt with the Midas/Gen for analysis and design and Tekla Structures for Building Information Modeling. In this research, it is improved the applicability and function of the existing interface module developed by authors. Although model information was functionally well linked by the existing module in both directions, the applicability is limited due to the difference of attributes between structural analysis model and structural detail model. In this study, we analyzed the problems that occur in existing module. We have developed the interface module to solve the problems and improved the applicability of the existing module.

• Korean Journal of Logic
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• v.7 no.1
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• pp.85-100
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• 2004

이 논문은 부사어에 의해서 수신되는 행위 문장이 어떻게 논리적으로 분석되어야 하는가에 대한 데이빗슨의 주장을 비판적으로 검토하고자 한다. 데이빗슨은 행위 문장이 부사어에 수식될 때, 그 문장은 원래의 행위 문장에 의해서 함축됨을 보일 수 있도록 해석되어야 한다는 데 착안하여 자신의 사건 존재론을 근거로 행위 문장을 사건을 양화하는 문장으로 해석되어야 한다고 주장한다. 그러나 그러한 해석은 데이빗슨 자신이 의도한 목적을 충분히 충족시키지 못하고, 또한 행위 문장이 양화하는 사건이 문장 전체가 아닌 일부가 가리킨다는 반직관적인 주장이라는 점에서 불만스럽다. 그러나 무엇보다 데이빗슨의 해석이 갖는 문제점은 행위 문장을 수신하는 부사어의 용법이 다양함에도 불구하고 그러한 사실을 간과한 것이다. 따라서 이 글은 바와이즈와 페리에 의해서 제시된 상황 존재론에 의거하여 다양한 부사어에 대한 해석의 가능성을 제시하여, 부사어에 의해서 수식되는 행위 문장을 해석하는 몇 가지 방법을 제시한다.