• 대한조선학회논문집
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• 제47권3호
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• pp.359-368
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• 2010

This paper describes the generation and propagation of internal solitary wave in a two-layer fluid system by numerical analysis. Characteristics of interfacial soliton such as wave type, wave height, wave celerity are investigated numerically with respect to an extent of initial disturbance, fluid thicknesses of the two fluids and etc. The difference between the internal wave propagation on sloping beach and flat bottom was also examined. Laboratory experiments were conducted in the wave flume and compared with the results of numerical computation for verification.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.318-326
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• 2008

Recently, a new seismic probe, called "MudFork", has been developed and can be utilized for accurate and easy measurements of shear wave velocities of soft soils. To expand its use to estimate undrained shear strength and density, correlations between those and shear wave velocity were being attempted. Cone penetration tests and a seismic test, using MudFork, were performed at a soft ground site near Incheon, Korea. Also, undisturbed samples were obtained and shear wave velocities of the samples were measured as well as undrained shear strength, using triaxial compression test and bender elements. A simple linear relationship between shear strength and shear wave velocity was obtained, and a tentative relationship between density and shear wave velocity was also defined.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2011년도 학술발표회
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• pp.45-49
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• 2011

본 연구에서는 일본 전력중앙연구소에서 수행된 wave fission 수리모형실험 자료를 토대로 일차원 FUNWAVE 수치모형을 이용하여 wave fission 현상을 재현하는 수치모의를 수행하였다. FUNWAVE 수치모형은 Boussinesq 방정식을 지배방정식으로 사용하고 있으며 파의 분산효과와 비선형 효과를 고려할 수 있는 수치모형이다. 따라서 wave fission의 주된 발생원인인 분산효과와 비선형효과에 대한 고려를 통해 수치모의 결과는 수리모형실험의 관측치와 상당히 잘 일치함을 확인할 수 있었다. 또한, 본 연구에서는 추가적으로 해수의 흐름이 존재하는 경우를 가정하고 수로 내 일정한 유량의 흐름을 추가하여 wave fission 일차원 수치모의를 수행하였다. 수치모의 결과 파의 진행방향과 반대방향으로 흐름이 존재하는 경우 wave fission으로 인한 수면변위의 크기가 상대적으로 증가함을 확인할 수 있었으며 반대로 파의 진행방향과 동일한 방향으로 흐름이 존재하는 경우 wave fission으로 인한 수면변위의 크기가 상대적으로 감소함을 확인할 수 있었다.

• International Journal of Reliability and Applications
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• 제5권1호
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• pp.37-46
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• 2004

Coil spring of automobile suspension system is very important to safety and dynamics of passenger car and requires a highly advanced quality control during manufacturing processes. Surface cracks on the coil spring rod produced by mechanical machining and heat treatment may cause a severe accident and large cost to the manufacturer. In order to detect surface cracks of the rod, guided wave technique is applied for a fast total volumetric inspection. Pochhammer equation is studied to investigate the dispersion characteristics of the guided wave in the spring rod and optimal wave modes sensitive to the surface crack are selected experimentally to design the experimental arrangement for the generation of guided wave. Rod samples with different size of artificial axial EDM notch on the surface ranging from 50${\mu}{\textrm}{m}$ to 1 mm are examined by guided wave and inspection results discussed.

• 대한조선학회지
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• 제16권3호
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• pp.35-47
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• 1979

Wave resistance of a parabolic thin ship, with its boundary layer and wake taken into account, was calculated up to second order. In addition to the double-model source distribution on the centerplane, image sources of the wave potential were calculated to keep the body introduced boundary condition undisturbed. Boundary layer and wake effects on the wave-making resistance were included by generating an irrotational flow which matches that exterior to the boundary layer and wake. For this purpose, the boundary layer and wake were calculated. The wave resistance refined with second-order corrections are found to be very important for wave resistance calculations even at moderate Froude numbers($Fr=0.2{\sim}0.3$). Wave-potential corrections are dominate around the bow. On the other hand, Viscosity plays and important role at the stern with its boundary layer and wake development.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1997년도 봄 학술발표회 논문집
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• pp.544-550
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• 1997

In this study, the advanced on-sided stress wave velocity measurement method was applied to investigate the effects of composition, age and moisture content in concrete. Two concrete specimens that have different composition were used to figure out the change of the Longitudinal and Surface wave velocity due to different composition. The other concrete specimen was cast and the Longitudinal and Surface wave velocity was monitored during curing process. After 28-day old, the effect of moisture content in the concrete specimen to the stress wave velocity is presented in this paper during the time period 43-74 days after casting. For drying process. an aggregate drying oven was used. A conventional ultrasonic through transmission method was used to compare with the results determined by the one-sided method.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2015년도 추계학술발표대회
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• pp.594-597
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• 2015

IoT(Internet of Thing) 환경이 도래하면서 다양한 무선 통신 기술들이 사용되고 있다. 그 중에서 가장 많이 쓰이는 무선 통신 기술은 Z-WAVE이다. Z-WAVE는 저전력, 양방향 RF 등의 장점을 가지며, 세계 스마트 홈 시장에서 가장 폭 넓게 사용되는 기술이다. 이 기술을 채택한 연합을 Z-WAVE 연합이라고 하는데, 이 연합은 수백 개 이상의 제조사들과 1000개 이상의 활성화된 제품을 가지고 있다. 하지만 Z-WAVE는 중간자 공격 등과 같은 보안성의 취약점을 가지고 있으며 아직까지 연구가 부족한 실정이다. 따라서 본 논문에서는 IoT 환경에서 Z-WAVE 기반의 향상된 키 교환 프로토콜 기법을 제안한다.

• 한국해양공학회지
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• 제22권1호
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• pp.1-5
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• 2008

A 2-D Fluent-based numerical wave tank(FBNWT) capable of simulating wave propagating and overtopping is presented. The FBNWT model is based on the Reynolds averaged Naiver-Stokes equations and VOF free surface tracking method. The piston wave maker system is realized by dynamic mesh technology(DMT) and user defined function(UDF). The non-iteration time advancement(NITA) PISO algorithm is employed for the velocity and pressure coupling. The FBNWT numerical solutions of linear wave propagation have been validated by analytical solutions. Several overtopping problems are simulated and the prediction results show good agreements with the experimental data, which demonstrates that the present model can be utilized in the corresponding analysis.

• 대한원격탐사학회지
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• 제19권1호
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• pp.31-36
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• 2003

We extracted significant wave height (SWH) using several altimeter missions from 1987-1995 over the Northwest Pacific ocean and compared with ECMWF (European Center for Medium- Range Forecast) reanalysis (ERA) products. For large wave heights the ERA wave heights are smaller than the altimetric ones, while for small wave heights the ERA wave heights are larger Comparison in SWH between altimetric derivations and ERA model products shows the discrepancy of 0.46-0.21$\times$SWH (m). Methods for propagating this differences into ERA wind error are presented.

• 한국해양환경ㆍ에너지학회지
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• 제7권1호
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• pp.47-55
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• 2004

본 논문은 1998년부터 2002년까지 대한민국 홍도 해역에 설치된 파향파고계에서 계측된 파랑자료를 이용하여 홍도 해역 파랑의 통계적 특성을 살펴보았다. 파랑관측율과 평균파고, 평균주기, 파향을 하였다. 그리고 파고-주기결합분포표를 작성하였고, n년 반복주기 파고와 최대 파고의 주기를 추정하였다. 2000년과 2002년에 발생한 태풍 "프라피룬"과 "루사"에 의한 파랑의 특성을 파악하였다.