• International Journal of Naval Architecture and Ocean Engineering
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• 제4권3호
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• pp.281-290
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• 2012

Hydrodynamic analysis of a surface-piercing body with an open chamber was performed with incident regular waves and forced-heaving body motions. The floating body was simulated in the time domain using a 2D fully nonlinear numerical wave tank (NWT) technique based on potential theory. This paper focuses on the hydrodynamic behavior of the free surfaces inside the chamber for various input conditions, including a two-input system: both incident wave profiles and forced body velocities were implemented in order to calculate the maximum surface elevations for the respective inputs and evaluate their interactions. An appropriate equivalent linear or quadratic viscous damping coefficient, which was selected from experimental data, was employed on the free surface boundary inside the chamber to account for the viscous energy loss on the system. Then a comprehensive parametric study was performed to investigate the nonlinear behavior of the wave-body interaction.

• 물과 미래
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• 제20권1호
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• pp.49-54
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• 1987

일정수심에 해역에 주기적인 파장의 사련이 있는 겨우 파의 반사특성을 경계요소법의 선형요소에 의해 해석하였다. 파랑은 2차원 선형파 이론으로부터 해석하였으며, 입사파 방향은 사련상에 임의방향 (직각입사 또는 경사입사)으로 진행한다고 가정하였다. 본 계산의 신뢰도를 검증하기 위하여 기존의 실험적, 이론적 결과 및 수치결과와 각각비교하였다. 직각입사파에 대한 본 수치계산 결과, 사련의 파장이 수면파장의 1/2인 경우에 발생하는 Bragg공진반사가 잘 예측되었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.726-730
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• 2000

In this article, the scattering effect around a microphone is studied by using boundary element method, because it is hard to find the scattering experimentally. The scattering problem is defined by impinging an obstacle, i.e. a solid cylinder, with an incident plane wave. From this analysis, the scattering is numerically calculated by varying the microphone shape, the incident angle and the distance between microphones. It is found that the scattering effect of a microphone increases as the frequency increases and is not considerable in the low frequency region. However, it is noted that there might be the pressure distortion above 4 kHz due to the scattering in microphone measurement.

• 한국해양공학회지
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• 제36권4호
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• pp.270-279
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• 2022

In this study, numerical analysis and experiments were performed to analyze the viscous damping effect according to the shape of the chamber skirt of the breakwater-linked inclined oscillating water column wave energy converter. Experiments were conducted using a two-dimensional mini wave tank and verified by comparing the results of a computational fluid dynamics numerical analysis. Pointed and rounded skirts were modeled to compare the effect of viscous damping when incident waves enter the chamber, and the difference in the displacement of the water surface in the chamber was compared according to the wave period for the two skirt shapes. The wave elevation in the chamber in the rounded-skirt condition was larger than the pointed-skirt condition in all wave periods, which was approximately 47% greater at 0.9 s of the incident wave period. Therefore, extracting the maximum energy through the optimal orifice is possible while minimizing the energy attenuation in the rounded-skirt condition.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2000년도 추계학술대회 논문집
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• pp.119-124
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• 2000

• 한국광학회:학술대회논문집
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• 한국광학회 2008년도 동계학술발표회 논문집
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• pp.165-166
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• 2008

• Structural Engineering and Mechanics
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• 제42권6호
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• pp.815-829
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• 2012

This paper proposes a nonlinear computational modeling approach for the behaviors of structural systems subjected to fire. The proposed modeling approach consists of fire dynamics analysis, nonlinear transient-heat transfer analysis for predicting thermal distributions, and thermomechanical analysis for structural behaviors. For concretes, transient heat formulations are written considering temperature dependent heat conduction and specific heat capacity and included within the thermomechanical analyses. Also, temperature dependent stress-strain behaviors including compression hardening and tension softening effects are implemented within the analyses. The proposed modeling technique for transient heat and thermomechanical analyses is first validated with experimental data of reinforced concrete (RC) beams subjected to high temperatures, and then applied to a bridge model. The bridge model is generated to simulate the fire incident occurred by a gas truck on April 29, 2007 in Oakland California, USA. From the simulation, not only temperature distributions and deformations of the bridge can be found, but critical locations and time frame where collapse occurs can be predicted. The analytical results from the simulation are qualitatively compared with the real incident and show good agreements.

• 융합보안논문지
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• 제6권4호
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• pp.161-169
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• 2006

최근 정보시스템의 발달에 따라, 다양한 정보시스템과 응용 소프트웨어의 개발이 이루어지고 있다. 하지만 정보시스템의 발달에 따른 역기능으로 많은 침해사고와 사이버해킹이 증가하는 추세이다. 이러한 정보화의 역기능을 차단하기 위해, 많은 기관에서는 정보시스템과 이를 보호하는 정보보호시스템의 운영과 관리를 위하여 많은 정보시스템 운영인력을 투입하고 있으나, 체계적 관리와 각 역할의 특성에 대한 분석부족으로 효율적인 운영에 많은 어려움을 겪고 있다. 본 논문에서는 정보시스템과 정보보호시스템 보안 및 관리 운영과 수행업무의 특성에 따라 정형화 된 Cause-Effect Model을 제시하도록 한다. 이 모델에서는 정보시스템과 정보시스템 운영자를 하나의 information Component로 간주한다. 본 논문에서 제시된 Cause-Effect Model의 각 단계에서 영향을 미치는 Human Factor의 세부 요소에 대한 영향도 분석을 통하여, 주어진 역할에 따라 최적의 human Resource의 관리와 배치가 가능할 것이다. 이러한 분석 및 접근 방법은 각 기관의 제한된 Resource 에 대한 효율적 운영이 가능하도록 하여, 기관의 정보시스템 운영과 악의적 침입에 대한 효율적인 방어를 가능하게 할 수 있다.

• 한국안전학회지
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• 제36권5호
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• pp.43-51
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• 2021

Incident investigation is one of the most important processes among various other safety management methods to prevent industrial accidents. Finding the root causes of accidents, eliminating hazards, and improving safety are the most important purposes of investigating accidents. During the investigation process, root cause analysis (RCA) techniques are used to effectively identify RCA. Over the past few decades, over 30 RCA methods have been developed. These techniques are being widely used in some industries, such as the nuclear and aircraft industries; however, most of the RCA techniques require professional knowledge and special training, making it difficult for safety managers in their respective fields to understand and apply them. Therefore, managers of general industrial sites are rarely present at the scene of actual accident investigations, and they cannot contribute much to the purpose and effectiveness of these investigations. In this study, to address these issues, we developed an RCA technique to facilitate root cause investigation of accidents in real-world industrial sites. To develop new techniques, Systematic Cause Analysis Technique (SCAT), one of the RCA techniques, was used to investigate incidents in the enterprise over three years. We also utilized feature analysis and other papers from existing RCA techniques. To verify its effectiveness, the technique proposed was also applied to the accident case. The technique developed can easily identify and analyze the root cause of an accident and help industrial managers. It can also identify the root cause category where accidents are concentrated and use this data to establish guidelines for preventing future accidents and, thus, focus on prioritizing improvement initiatives.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.229-234
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• 2004

A Typhoon wave is generated by wind fields during the Passage of Typhoon. Transporting wind field makes wind wave and swell in the open sea, and then, those wave components are transported in the shallow water. Typhoon waves in the shallow water is generated by Typhoon wind field and incident wave. Bisides, Incident waves to the shallow water are deformated by topographic conditions. This paper estimated the analysis of the Typhoon waves by wind fields and incident waves according to wave action balance equation model. As the result of wave numerical experiment, wave field during the passage of Typhoon 'Memi' in the shallow water is strongly effect by wind fields. Wave action balance equaion can be partially used for Typhoon wave simulations.