• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.1073-1077
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• 2005

In this study, wave pressure is calculated by using irregular waves in front of a breakwater. In the numerical model, the Reynolds equations are solved by a finite difference method and $k-{\varepsilon}$ model is employed for the turbulence analysis. To track the free surface displacement, the volume of fluid method is employed. The results of two cases present that wave pressure change due to irregular wave similar to wave height of irregular wave. It is observed that wave pressure of Case 2 more bigger than wave pressure of Case 1 at the same position.

• 천문학회보
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• 제38권2호
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• pp.47.1-47.1
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• 2013

We present structural parameters of galaxies in the Extended Viro Cluster Catalog (EVCC), new catalog of galaxies in the Viro cluster using homogeneous Sloan Digital Sky Survey (SDSS) Date Release 7 (DR7) data. The EVCC covers more extended region of the Viro cluster than of the Virgo Cluster Catalog (VCC) and presents updated morphologies of galaxies using multi-band images and spectral features. We obtain the surface brightness profiles of galaxies using ellipse task in IRAF. Based on the analysis of surface brightness profile we construct a catalog of various structural parameters of galaxies, i.e. central surface brightness, effective radius, sersic index, effective surface brightness, and mean effective surface brightness. Taking advantage of these structural parameters in various parameter spaces, we refine criteria of dividing giant elliptical and dwarf elliptical galaxies. In addition, we found that bulge dominated galaxies have larger sersic index and brighter central surface brightness than disk dominated galaxies. At fixed magnitude, dwarf elliptical galaxies dwarf lenticular galaxies, and dwarf irregular low surface brightness (LSB) galaxies show larger effective radii than giant elliptical galaxies, giant lenticular galaxies, and irregular high surface brightness (HSB) galaxies, respectively. Dwarf elliptical galaxies and dwarf irregular LSB galaxies occupy the similar structural parameter spaces. We suggest that giant elliptical galaxies and dwarf elliptical galaxies may have different origin.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.373-376
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• 2006

In general, a method for generating irregular wave by combination of component waves obtained from linear wave theory is widely used. In these method, however, mean water surface elevation is rising from time to time because of nonlinear effect of wave. In this study, for the rising problem of mean water surface elevation and stabilization of calculation from time to time, mass transport velocity for horizontal velocity at wave source position is considered. The rising problem of mean water surface elevation is checked by comparing calculated wave profile from numerical technique proposed in this study with target wave profile at wave source position in numerical wave tank by using CADMAS-SURF code. And, by generating irregular wave, the validity of wave overtopping rate estimated from this numerical analysis is discussed by comparing computed results with measured results in hydraulic model experiments for vertical seawall located on a sloping sea bottom. As a results, the computations are validated against the previously experimental results by hydraulic model test and numerical results of this study and a good agreement is observed. Therefore, numerical technique of this study is a powerful tool for estimating wave overtopping rate over the crest of coastal structure.

• 대한조선학회 특별논문집
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• 대한조선학회 2005년도 특별논문집
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• pp.38-43
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• 2005

The present study is concerned with the numerical analysis of the sloshing impact pressure of the Liquefied Natural Gas (LNG) carriers in rough sea. The reliable predictions of the both random tank motions in irregular waves and violent fluid flow in the LNG tanks are required for practical sloshing analysis procedure of LNG carriers. The three-dimensional numerical model adopting SOLA-VOF scheme is used to predict violent free surface movements of LNG tank in irregular motions. For accurate input motion of tank, a three-dimensional panel method program called SSMP (Samsung Ship Motion Program) is applied for seakeeping analysis. Comparison studies of sloshing analysis are carried out for No.2 tank of 138K and 205K LNG carriers to verify the safety of the LNG containment system of the proposed 205K large LNG carrier.

• 대한공간정보학회지
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• 제6권2호
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• pp.133-141
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• 1998

지형 모델링은 사각그리드에 의한 방법과 불규칙 삼각망을 이용한 방법으로 나눌 수 있다. 특히 불규칙 삼각망에 의한 방법은 적은 지형 데이터로써 지형의 특징을 잘 표현할 수 있고 렌더링시간을 단축시킬 수 있어 널리 사용되고 있다. 이러한 불규칙 삼각망을 만들기 위해서는 의미점 추출과정과 삼각형화 과정이 필요하다. 본 논문은 이러한 전처리 작업 중 의미점 추출과정의 개선에 중점을 두었다. 의미점을 추출하는 방법에는 8방향 이웃점 검사 방법과 이를 변형한 방법들이 많이 사용되고 있다. 또한 다각형 감소 기법을 응용하여 불필요한 점들을 제거하는 방법도 제안되고 있다. 그중 기본적으로 사용하는 8방향 이웃점 검사 방법을 이용한 의미점 추출 방법은 필요 없는 점들을 추출한다는 문제점을 가지고 있다. 이러한 문제점을 해결하기 위해서 지형 단면을 이용한 의미점 추출방법을 제안한다. 이 방법은 기존의 방법보다 의미점 추출 시간이 빠르고 적은 지형 자료로 보다 정확한 특징점을 추출할 수 없다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.409-421
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• 2019

Investigation of hydroelastic responses of high-speed vessels in irregular sea state is of major interest in naval applications. A three dimensional nonlinear time-domain hydroelastic method in oblique irregular waves is developed, in which the nonlinear hydrostatic restoring force caused by instantaneous wetted surface and slamming force are considered. In order to solve the two technical problems caused by irregular sea state, the time-domain retardation function and Proportional, Integral and Derivative (PID) autopilot model are applied respectively. Besides, segmented model tests of a high-speed trimaran in oblique waves are performed. An oblique wave testing system for trimarans is designed and assembled. The measured results of main hull and cross-decks are analyzed, and the differences in distribution of load responses between trimarans and monohull ships are discussed. Finally, from the comparisons, it is confirmed that the present concept for dealing with nonlinear hydroelastic responses of ships in oblique irregular waves is reliable and accurate.

• 한국도서관정보학회지
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• 제45권2호
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• pp.205-234
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• 2014

이 연구는 우리나라 학교도서관 비정규직 인력 문제에 대해 구조적인 관점으로 살펴보고 정리하였다. 비정규적 인력이 확대된 배경과 계기를 살펴보고 비정규직 인력의 직무상 주요 문제점들을 검토하였다. 그리고 비정규직 인력 문제의 표면과 이면의 내용과 구조를 체계적으로 탐구하여 문제의 성격과 내적 갈등 양상을 확인하였다. 이를 바탕으로 현재 제안되거나 진행되고 있는 비정규직 인력 문제의 해결 방안에 대해 점검하고 문제 해결을 위해 요청되는 기본적인 자세를 제안하였다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
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• pp.216-218
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• 2000

In case of hardfaced wrapping roll, beadmark shape appear at wrapping roll surface due to irregular wear between weld bead. Irregular wear of this is caused by difference of hardness between weld bead. This study aims at investigating which matrix is good for removing of beadmark at wrapping roll surface. So, we make specimen with martensitic matrix and austenitic matrix. The hardfacing alloys were deposited 4 times on a SS41 steel plate using self-shielding flux cored arc welding method. Difference of hardness between weld bead of specimen with matrix of martensite was higher than specimen with matrix of austenite both as-welded and after heat treatment. Therefore, austenitic matrix is better than martensitic matrix for removing of beadmark of wrapping roll surface.

• Journal of Welding and Joining
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• 제18권6호
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• pp.68-73
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• 2000

In case of overalyered wrapping roll, beadmark shape appear at wrapping roll surface due to irregular wear between weld bead. Irregular wear of this is caused by difference of hardness between weld bead. This study aims at investigating which matrix is good for removing of beadmark at wrapping roll surface. So, we make specimen with martensitic matrix and austenitic matrix. The overlayered alloys were deposited 4 times on a SS41 steel plate using self-shielding flux cored arc welding method. Difference of hardness between weld bead of specimen with matrix of martensite was higher than specimen with matrix of austenite both as-welded and after heat treatment. Therefore, austenitic matrix is between than martensitic matrix for removing of beadmark of wrapping roll surface.

• Restorative Dentistry and Endodontics
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• 제12권2호
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• pp.91-98
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• 1987

This study was designed to investigate the changing depositional pattern of inorganic enamel substances during enamel formation and maturation. For this purpose, white rat incisors which continuously grow and develop during the life, were chosen as specimens. And after treated with 20% KOH solution, outer surface of forming inorganic enamel were observed with the scanning electron microscope, dividing into 6 types according to the forming pattern from apical to cuspal direction. The observations lead to the following conclusions: 1. During the initial enamel forming stage, inorganic enamel substances were deposited with very irregular pyramidal shape on the root dentin surface. 2. During the enamel forming stage, inorganic enamel substances were deposited with relatively regular hexagonal, honey-comb appearance. 3. During the later enamel forming stage, inorganic enamel substances were deposited with very irregular and roughly amorphous appearance. 4. During the later enamel maturating stage, very small and round inorganic enamel substances were deposited densely, and made a flat enamel surface.