• 한국해양공학회지
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• 제37권2호
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• pp.68-79
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• 2023

Even though submerged breakwater reduces incident wave energy, it redistributes the coastal area's wave-induced current, sediment transport, and morphological change. This study examines the coastal hydrodynamics and the morphological response of a wave-dominated beach with submerged breakwaters installed through field observation and quasi-3D numerical modeling. The pre-and post-storm bathymetry, water level, and offshore wave under storm forcing were collected in Bongpo Beach on the East coast of Korea and used to analyze the coastal hydrodynamic response. Four vertically equidistant layers were used in the numerical simulation, and the wave-induced current was examined using quasi-3D numerical modeling. The shore normal incident wave (east-northeast) generated strong cross-shore and longshore currents toward the hinterland of the submerged breakwater. However, the oblique incident wave (east-southeast) induced the southeastward longshore current and the sedimentation in the northeast area of the beach. The results suggested that the incident wave direction is a significant factor in determining the current and sediment transport patterns in the presence of the submerged breakwaters. Moreover, the quasi-3D numerical modeling is more appropriate for estimating the wave transformation, current, and sediment transport pattern in the coastal area with the submerged breakwater.

• Structural Engineering and Mechanics
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• 제58권5호
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• pp.887-903
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• 2016

This study analyses the seismic response of a three-dimensional (3-D) rigid massless square foundation resting or embedded in a viscoelastic soil limited by rigid bedrock. The foundation is subjected to harmonic oblique seismic waves P, SV, SH and R. The key step is the characterization of the soil-foundation interaction by computing the impedance matrix and the input motion matrix. A 3-D frequency boundary element method (BEM) in conjunction with the thin layer method (TLM) is adapted for the seismic analysis of the foundation. The dynamic response of the rigid foundation is solved from the wave equations by taking into account the soil-foundation interaction. The solution is formulated using the frequency BEM with the Green's function obtained from the TLM. This approach has been applied to analyze the effect of soilstructure interaction on the seismic response of the foundation as a function of the kind of incident waves, the angles of incident waves, the wave's frequencies and the embedding of foundation. The parametric results show that the non-vertical incident waves, the embedment of foundation, and the wave's frequencies have important impact on the dynamic response of rigid foundations.

• 산업경영시스템학회지
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• 제22권49호
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• pp.125-133
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• 1999

Nonrecurring congestions are generally caused by random or less predictable events, such as accidents, spilled loads stalled or broken-down vehicles that, temporarily reduce the capacity of the freeway. The purpose of this paper is to present the effect of incidents on the traffic congestion on the urban freeway by simulation method. The simulation scenario is composed of two level traffic conditions, two level incident severities, and eight level incident durations. After incident, the recovering duration to the normal traffic flow, increased by linear of incident duration. Total vehicles travel time increased and average travel speed decreased by squares curve of incident duration. Considering incident impacts, incident management system is evaluated the major function of the urban freeway traffic management system. Also, necessary the related research to detect, verify, and develop effective response strategies for traffic incidents.

• 정보보호학회논문지
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• 제24권3호
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• pp.523-533
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• 2014

컴퓨터 침해사고 대응 시 침입경로를 파악하는데 많은 시간을 소비하므로 피해 범위가 확대되거나 침해사고 발생의 원인을 밝힐 주요 증거를 유실하게 된다. 이로 인해 동일한 원인의 침해사고가 재발하고 있다. 이 논문에서는 침입자를 신속하고 정확하게 찾아낼 수 있도록 침해사고 발생 전, 디지털증거지도 작성을 제안한다. 디지털증거지도는 다양한 IT장비와 소프트웨어가 만들어 내는 머신 데이터간의 연결 고리가 그물 형태로 만들어진다. 연결 고리는 다양한 외부요인에 민감하기 때문에 지속적인 관리가 필요하다. 침해사고 발생 전, 유효한 디지털증거지도를 숙지함으로써 침해사고 발생 시 신속히 대응하여 피해 범위를 축소하며 침입경로를 제거하여 침해사고 재발을 방지한다. 디지털증거지도는 로그뿐만 아니라 컴퓨터에서 발생하는 다양한 아티팩트들을 채용함으로써 고도화된 APT 공격과 안티-포렌식 기법에 효과적으로 대응한다.

• Journal of Platform Technology
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• 제11권4호
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• pp.35-49
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• 2023

최근 다양한 원인으로 실시간 사이버 위협이 지속적으로 발생하고 있다. 대부분의 기업들이 내부 중요정보를 디지털화해 중앙집중식으로 저장하고 있는 특성을 가지고 있어 침해사고 발생 시 영향도가 매우 높다고 할 수 있다. 침해사고 대응 과정에서 수집 및 분석하는 모든 전자기기의 정보들은 수시로 변경이 일어날 수 있는 특성을 가지고 있다. 향후 수사 및 법정에서 관련 증거 자료의 제출이 필요하게 되는데 이때 무결성의 원칙, 절차 연속성(Chain of Custody) 원칙 등 디지털 포렌식의 기본원칙들을 지켜 증거자료의 정당성, 정확성 등을 확보해야 한다. 또한 내부 기밀자료, 개인정보가 유출되어도 모르는 경우가 있으며 디지털 포렌식 기반의 침해사고 진단도 주기적으로 진행해 침해사고의 사전 방지 또는 사고 후에 빠른 인지가 가능하도록 해야 한다. 본 논문에서는 침해사고 발생 시 수집 및 분석한 디지털 증거자료의 정당성 및 정확성 확보, 침해사고 사전 방지 및 사고 후 빠른 인지를 목표로 하는 윈도우10 환경의 디지털 포렌식 기반 침해사고 진단 및 대응 절차를 제안한다.

• 한국광학회:학술대회논문집
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• 한국광학회 1990년도 제5회 파동 및 레이저 학술발표회 5th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.157-161
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• 1990

Self-pumped phase conjugation(SPPC) in BaTiO3 single crystal is experimentally investigated at a wavelength of 514.5nm from an Ar+ laser. The incident Gaussian beam enters the crystal as an extraordinary ray. The maximum SPPC reflectivity of 48% is obtained at incident angle 80 degree. the SPPC wave demonstrates good image reconstruction. The response time (r) of SPPC wave as a function of incident intensity is measured to be r=36$\times$I-0.79sec.

• 한국해양공학회지
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• 제20권5호
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• pp.30-35
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• 2006

In tire presence of incident waves with different frequencies, there are second order sum and difference frequency wave exciting forces due to the nonlinearity of tire incident waves. Although the magnitude of these nonlinear wave forces are small, they act on TLPs at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency waveexciting forces occurring close to tire natural frequencies of TLPs often give greater contributions to high and law frequency resonant responses. Nonlinear motion responses and tension variations in the time domain are analyzed by solving the motion equations with nonlinear wave exciting forces using tire numerical analysismethod. The numerical results of time domain analysis for the nonlinear wave exciting forces on the ISSC TLP in regular waves are compared with the numerical and experimental ones of frequency domain analysis. The results of this comparison confirmed tire validity of the proposed approach.

• 한국압력기기공학회 논문집
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• 제17권2호
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• pp.65-74
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• 2021

This study aims to assess the effect of postulated seismic loads on the structural integrity of a spent nuclear fuel dry storage facility. Firstly, three-dimensional modal and response spectrum analyses were carried out. With regard to the latter analysis, the effect of incident angles against two horizontal and one vertical response spectra was also considered. Results showed that even though two critical locations were predicted at the longitudinal axis central part of upper flow path as well as the end discontinuity part of upper and lower flow paths connector, their maximum principal stress values were less than the tensile strength. Moreover, since the influence of vertical angle was 87% higher than that of horizontal angle in particular, which should be carefully handled to demonstrate integrity of the facility.

• 한국안전학회지
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• 제23권2호
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• pp.7-13
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• 2008

In a long-span bridge which is constructed on soft soil, it is requested to make a plan considering soil-structure interaction, and soil-structure interaction is partially under consideration at the actual bridge plan. Many researches on dynamic behavior of a bridge affected by soil-structure interacting have been accomplished, but it is difficult to estimate dynamic behavior of a bridge on soft soil accurately because of many uncertainties. This paper presents the results about dynamic response of a long-span suspension bridge in the site composed of soft soil considering incident angle of input ground motion. The effect of soft soil was evaluated by the use o computer program SASSI and a long-span suspension bridge was modeled by finite element program MIDAS. The effect of incident angle of input ground motion was investigated on the dynamic response of a long-span bridge.

• 한국해양공학회지
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• 제12권2호통권28호
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• pp.33-42
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• 1998

In the presence of incident waves with different frequencies, the second order sum and difference frequency waves due to the nonlinearity of the incident waves come into existence. Although the magnitudes of the forces produced on a Tension Leg Platform(TLP) by these nonlinear waves are small, they act on the TLP at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wave loads produced close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The second order wave exciting forces and moments have been obtained by the method based on direct integration of pressure acting on the submerged surface of a TLP. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.