• 한국지진공학회논문집
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• 제11권4호
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• pp.25-31
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• 2007

For areas such as the Korean Peninsula, which have moderate seismic activity but no available records of strong ground motion, synthetic seismograms can be used to evaluate ground motion without waiting for a strong earthquake. Such seismograms represent the estimated ground motions expected from a set of possible earthquake scenarios. Local site effects are especially important in assessing the seismic hazard and possible ground motion scenarios for a specific fault. The earthquake source and rupture dynamics can be described as a two-step process of rupture initiation and front propagation controlled by a frictional sliding mechanism. The seismic wavefield propagates through heterogeneous geological media and finally undergoes near-surface modulations such as amplification or deamplification. This is a complex system in which various scales of physical phenomena are integrated. A unified approach incorporates multi-scale problems of dynamic rupture, radiated wave propagation, and site effects into an all-in-one model using a three-dimensional, fourth-order, staggered-grid, finite-difference method. The method explains strong ground motions as products of complex systems that can be modified according to a variety of fine-scale rupture scenarios and friction models. A series of such deterministic earthquake scenarios can shed light on the kind of damage that would result and where it would be located.

• 한국추진공학회지
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• 제11권1호
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• pp.1-10
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• 2007

반응 진행 변수 보존 방정식 및 1단계 비가역 반응과 연계된 고해상도 전산유체 코드를 이용하여 관 내부를 전파하는 데토네이션 파의 삼차원 구조를 관찰하였다. 코드는 영역 분할에 기초하여 MPI 라이브러리를 이용하여 병렬화하였으며, AMD 프로세서로 구성된 Windows 클러스터를 이용하여 실행하였다. 삼차원 비정상 해석으로부터 데토네이션 파의 불안정성으로 유발된 그을음 막 기록(smoked-foil record)을 얻을 수 있었으며, 이로부터 초기 교란 조건에 따라 직사각 모드나 대각 모드의 셀 구조와 함께 작은 반응 상수 조건에서는 회전 데토네이션 파를 관찰할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.354-356
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• 2006

This paper presents a new one-terminal numerical algorithm for fault location estimation and for faults recognition. The proposed algorithm are derived for the case of most frequent single-phase line to ground fault in the time domain. The arc voltage wave shape is modeled numerically on the basis of a great number of arc voltage records obtained by transient recorder. From the calculated arc voltage amplitude it can make a decision whether the fault is permanent of transient. In this paper the algorithm uses a very short data window and enables fast fault detection and classification for real-time transmission line protection. To test the validity of the proposed algorithm the Electro-Magnetic Transient Program(EMTP/ATP) is used.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.283-285
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• 2005

This paper presents a new two-terminal numerical algorithm for fault location estimation and for faults recognition using the synchronized phasor in time-domain. The proposed algorithm is also based on the synchronized voltage and current phasor measured from the PMUs(Phasor Measurement Units) installed at both ends of the transmission lines. Also the arc voltage wave shape is modeled numerically on the basis of a great number of arc voltage records obtained by transient recorder. From the calculated arc voltage amplitude it can make a decision whether the fault is permanent or transient. In this paper the algorithm is given and estimated using DFT(Discrete Fourier Transform) and the LES(Least Error Squares Method). The algorithm uses a very short data window and enables fast fault detection and classification for real-time transmission line protection. To test the validity of the proposed algorithm, the Electro-Magnetic Transient Program(EMTP/ATP) and MATLAB is used.

• 대한토목학회논문집
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• 제13권5호
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• pp.223-234
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• 1993

일반 PC 말뚝과는 달리 제작시 실리카(silica) 재료를 사용하고 증기양생후 고온, 고압의 추가양생(autoclave curing) 실시함으로써 말뚝자체의 강성을 높인 PHC 말뚝의 항타시공성과 지지력 특성을 파동이론에 근거한 수치해석과 실재현장에서의 항타기록 및 재하시험을 통하여 파악하였다. 임의의 지반조건에 대하여 항타장비에 따른 수치해석과 현장시험의 결과는 PHC 말뚝이 PC 말뚝에 비해 말뚝의 재질강도가 60% 정도 크므로 항타장비에 의해서 발휘되는 타격에너지에 대해 보다 큰 저항력을 가지기 때문에 설계지지력을 보다 크게 얻을 수 있으며 항타장비의 선정에 있어서도 보다 큰 효율을 지닌 장비의 선정이 가능하여 경제적인 항타작업을 수행하는데 유리함을 보였다.

• 한국지진공학회논문집
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• 제17권5호
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• pp.209-217
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• 2013

In order to verify the reliability of numerical site response analysis program, both soil free-field and base rock input motions should be provided. Beside the field earthquake motion records, the most effective testing method for obtaining the above motions is the dynamic geotechnical centrifuge test. However, need is to verify if the motion recorded at the base of the soil model container in the centrifuge facility is the true base rock input motion or not. In this paper, the appropriate input motion measurement method for the verification of seismic response analysis is examined by dynamic geotechnical centrifuge test and using three-dimensional finite difference analysis results. From the results, it appears that the ESB (equivalent shear beam) model container distorts downward the propagating wave with larger magnitude of centrifugal acceleration and base rock input motion. Thus, the distortion makes the measurement of the base rock outcrop motion difficult which is essential for extracting the base rock incident motion. However, the base rock outcrop motion generated by using deconvolution method is free from the distortion effect of centrifugal acceleration.

• 대한조선학회논문집
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• 제51권2호
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• pp.99-106
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• 2014

Weather routing of a ship provides an optimal route to the destination by using minimal time or fuel in a given sea condition. These days, weather routing came into a spotlight with soaring fuel price and the environmental regulations of IMO and several countries. This study presents three scenarios of voyaging strategies for a ship and compared them in terms of the fuel consumption. The first strategy fixes the speed of a ship as a constant value for entire sailing course, the second fixes the RPM of the ship as constant for entire course, and the third determines the RPMs of the ship for each segment of the course. For each strategy, a ship route is optimized by using the $A^*$ search method. Wind, ocean current and wave are considered as ocean environment factors when seeking the optimal routes. Based on 7000 TEU container ship's sea trial records, simulation has been conducted for three scenarios, and the most efficient routing scenario is determined in the view of fuel consumption.

• 한국경영과학회지
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• 제26권3호
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• pp.21-37
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• 2001

Riding on the wave of the information technology revolution, a slow of internet venture businesses (IVB) came into being. Hence, one of the recent developments in Korean capital market has been the proliferation of IVB, which is in accordance with the worldwide trend of ‘new economy’. Although the fair valuation is crucial for the nourishment of IVB, it is difficult to apply traditional valuation methods to these firms without reservation. It is due to the facts that most venture firms have little records of performance, grow unprecedently fast, and have highly uncertain future. The main purpose of this study is to suggest performance evaluation system of IVB and to develop KPE (Key Performance Indicators). Our empirical study is based upon Kaplan & Norton’s Balance Scorecard (BSC) approach. Specifically, our research has been conducted by the following two subsequent procedures: Firstly, seven internet venture firms have been selected and their executives have been interviewed by FGI(Focus Group Interview) method. Based upon these results, performance indicators have been developed. Secondly, by using the above mentioned BSC items (i.e., financial perspective, customer perspective, internal perspective and innovation & learning perspective), questionnaires have been constructed and sent to IVB through e-mail as well as over the Fax. Among the collected 110 samples, reliable 106 samples have been used to build BSC model and to draw our conclusion. In the future study, it would be much better to consider the role of strategy in IVB and the causal relationship among Key Performance Indicators of BSC.

• 지구물리와물리탐사
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• 제2권4호
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• pp.209-214
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• 1999

트렌치를 이용하여 다성분 탄성파 탐사에 필요한 횡파를 발생시키는 현장 실험을 2개소에서 실시하였다. 실험결과 1개소에서는 트렌치 연장 방향에 직각 방향으로 양호하게 분극된 횡파를 얻을 수 있었으며 다른 한 곳에서는 횡파 생성에 실패하였다. 시추공 내에 설치한 3성분 지오폰 기록을 필터링, 에너지 balancing, 수평 및 수직 성분 자료의 가$\cdot$감산 등 전처리 과정을 거쳐 P파와 S파를 분리하였고, S파의 직접파 이벤트를 분석하여 매질의 이방성을 관측할 수 있었다. 분석결과에 의하면 $SH_{max}$ 방향이 남북 방향이었으며 이는 시추코어에서 관찰된 파쇄대 절리 방향과 같다는 사실을 확인하였다.

• 대한안전경영과학회지
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• 제8권4호
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• pp.151-166
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• 2006

One of The standard issue in riding on the wave of the information system(IS) is records of performance, grow unprecedently fast, and has highly uncertain future. Within the framework of IS Evaluation, The main purpose of this study is to suggest performance quality evaluation system as follows, The Integrated Quality Evaluation Model Design(IQEMD) of Information System helps corporations to improve productivity, customer service and corporate competitive power. To respond flexibly this trend, we have to realize that the information system has to keep the most effective optimal information network at the proper time. The existing evaluation method has been concentrated on the evaluation of a degree of the information system maturity focused on static viewpoints. The evaluation of potential factors to affect the future-oriented performance, that can analyze both unit business being able to apply an information system base was used efficiently well and what performance evaluation item was obtained actually, was insufficient relatively. In this paper, An integrated quality evaluation method will analyze a degree of information system maturity in dynamic evaluation viewpoints rather than in static evaluation viewpoints. finally we estimated the relative degree of importance of each determinant using the AHP methodology The validity of the proposed model was also partially proved using two different methods, holistic and historical approach.