• Selected Papers of The Society of Naval Architects of Korea
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• 제2권1호
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• pp.47-62
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• 1994

Herein the surge-heave-pitch motion of a ship in harbor has been analyzed within the framework of linear potential theory. The ship is assumed to be slender and moored at an arbitrary position in a rectangular harbor with a constant depth. The coast line is assumed to be straight. The ship and harbor responses to incident long waves are represented in terms of Green's function, which is the solution of tole Helmholtz equation satisfying necessary boundary conditions. An integral equation is obtained from matching condition between harbor and ocean solutions, and it is replaced by an equivalent variational form. Numerical results sallow that the ship motion can be highly amplified at the frequencies, where the harbor is resonated by the incident wave. At the resonant frequencies, the added mass for vertical motions becomes negative and the damping forte changes abruptly.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 C
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• pp.1205-1207
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• 1999

All the submarine cable lines have been repaired restored and newly installed since 1970' s they were installed by the foreign technician around the islands off the southern and western coast of Korean peninsula. But April, 10th, 1998, for the first time in Korea, we Korean team of technicains succeeded in repairing and restoring the troubled cable lines from HEUGIL island to MASAG island, WANDO county, CHUN-NAM province. This job was done only by applying our newly researched and developed technology. The troubled cable lines were connected again by this technology.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2006년 창립20주년기념 정기학술대회 및 국제워크샵
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• pp.449-452
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• 2006

The main external force of the harbor in east coast is wave. So, wave is the important cause of wave induced current and sediment transport due to wave in planning harbor structures. Therefore, it must be considered not only to secure the harbor tranquility but also the sediment transport due to wave induced current in planning the harbor. In this study, we studied on the influences of construction procedure on harbor tranquility and siltation using annual coastal line data and bathymetry data near breakwater. And it suggests that the construction procedure for the harbor tranquility and the best way for the decrease of harbor siltation.

• Fisheries and Aquatic Sciences
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• 제10권2호
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• pp.68-73
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• 2007

Based on four juvenile specimens of Lutjanus collected from the southern coast of Jeju Island, three species, L. argentimaculatus, L. fulviflamma, and L. quinquelineatus, are described as the first record from Korea. The first species is easily differentiated from other lutjanid juveniles by distinct coloring of the dorsal, pelvic, and anal fins as well as two blue lines below the eye; the second species is characterized by having six yellowish brown stripes below the lateral line and a black spot on the side; the third species is identified by five longitudinal blue stripes and a black spot on the side when fresh. The new Korean names "Bul-geun-tung-dom," "Yuk-seon-jeomtung-dom," and "O-seon-tung-dom" are proposed for L. argentimaculatus, L. fulviflamma, and L. quinquelineatus, respectively.

• 한국항해항만학회지
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• 제34권9호
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• pp.687-692
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• 2010

This study is to improve the marine traffic environment along the west coast of the Korean peninsular so as to prevent the traffic accidents of the dangerous cargo carriers. The most used routes of the vessels were investigated from GICOMS database and the questionnaire survey. Gwanjanghang Sudo strait and Maenggol Sudo strait were considered to have some potential risks to the vessels. In this study, the alternative routes were developed to substitute the current routes near Gwanjanghang Sudo strait and the new boundary line of The Traffic Prohibited Area for Tanker was suggested to contain the Maenggol Sudo strait.

• 한국해양공학회지
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• 제14권1호
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• pp.29-36
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• 2000

Surface micro-crack grows along intergranular or transgranular region of crystal grains. But if it meets the barrier such as sessile dislocation and precipitates it loses straightness and deflects. Investigators had many difficulties in estimating fatigue life of smooth specimen because of the random distribution growth and coalescence of surface micro-cracks. The path of surface micro-crack has irregularity due to nonhomogeneous microstructure. Euclidian geometry can't quantify the shape of surface micro-crack but fractal geometry can. Therefore in this paper fractal dimension is measured at various stage of cycle ratio and estimated cycle ratio in 2024-T3 aluminium, alloy.

• 대한원격탐사학회지
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• 제2권2호
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• pp.95-105
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• 1986

The geomorophology of the tidal near $K\breve{u}$m river estuary on the west coast of Korea was studied using satellite images. There Landsat image of different tidal moment were geometrically corrected to be overlapped one another. Then topographic contours were extracted for the analysis with concept of 3-D. According to the morphological analysis, the tidal flats around $K\breve{u}$m river estuary area can be classified in three morphologically different groups: one is developped in a belt type along the shore; another is a delta type in the estuary; the other is developped between the shore line and islands. The morphological characteristics of the tidal flats in the study area seems to be mainly influenced by the tidal dynamics which are very storg on the weatern coastal zone of Korea. However the waves and human activities seem also to be important in some part of the area.

• 한국지역지리학회지
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• 제13권4호
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• pp.454-460
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• 2007

한국전쟁의 결과 한반도의 허리에 해당하는 DMZ 지역은 반세기 이상 인간의 관심에서 잊혀진 공간이었다. 그러나 최근 국 내외적으로 DMZ에 대한 관심이 고조되면서, 오늘날 DMZ를 대상으로 하는 연구는 점차 활발해 지고 있다. 그러나 정작 연구의 대상인 DMZ의 공간적 범위에 대한 연구는 매우 미약하다. 그마저도 선행연구를 분석한 결과 대부분의 연구에서 군사분계선과 DMZ, 한강하구 중립지역, 그리고 NLL에 대한 기술에 있어서 공간적인 오류를 범하고 있었다. 본 연구에서 조사한 결과, 동해안 고성의 명호리에서 서쪽의 임진강 하구에 이르는 군사분계선의 길이는 약 238km(148마일)이고, 군사분계선을 따라 설정되어 있는 DMZ의 면적은 약 $903.8km^2$로 측정되었다. 이는 현재 '155마일 휴전선' 등과 같이 남북을 양분하는 공간을 지칭하는 용어에 대한 재정립이 필요함을 의미하는 것이다.

• 전자공학회논문지
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• 제53권2호
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• pp.133-140
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• 2016

해안 수중 감시를 위하여 분산센서망를 해안에 설치하고, 이를 이용하여 표적을 탐지하고 표적의 위치를 추정하는 연구가 많이 이루어지고 있다. Zhou 등은 표적 탐지만 가능한 간단한 구조의 센서들로 구성된 분산센서망에서 표적을 탐지한 센서들의 위치 정보를 활용하여 표적의 위치를 추정하는 기법을 제안하였다. Zhou 등이 제안한 기법은 다른 기존의 기법에 비해 표적탐지 신호의 전파모델에 대한 파라미터들을 별도로 추정할 필요가 없고, 연산량이 적으며, 분산센서망에서 적은 량의 데이터만 송수신하여도 된다. 그러나 Zhou 기법은 표적의 위치 추정오차가 크다. Ryu는 추정오차를 줄이기 위하여 Zhou 기법을 수정하였다. 수정된 Zhou 기법은 Zhou 기법보다 추정성능이 향상되었지만, 여전히 비교적 큰 추정오차를 가지고 있다. 본 논문에서는 수정된 Zhou 기법으로 구한 표적의 방위각을 나타내는 직선과 표적을 탐지한 센서들과의 기하학적 구조를 고려한 표적위치 추정기법을 제안하였으며, 수정된 Zhou 기법에 기반을 두고 있다. 제안한 기법의 표적위치 추정성능이 Zhou 기법과 수정된 Zhou 기법 보다 향상되었음을 컴퓨터 시뮬레이션을 통하여 확인하였다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권3호
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• pp.1-13
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• 2021

Groundwater monitoring is commonly practiced with real-time sensors placed in several depth spots in aquifer. However, this method only provides monitoring data at the point where the sensors are installed. In this study, we developed a vertical line monitoring system (VLMS) that can provide continuous data of groundwater parameters along the vertical depth. The device was installed in a well located on the coast of the eastern part of Jeju island to monitor electrical conductivity, temperature, salinity, pH, dissolved oxygen, and oxidation-reduction potential over approximately 3 months from September 11 to December 3, 2020. The results indicated that the groundwater levels fluctuated with the tidal change of seawater level, and the upper and lower boundaries of the freshwater and saltwater zone in the groundwater were located at below 16 m and 36 m of mean sea level, respectively. There was a large variation in EC values during the high tide and temperature change was the greatest during flow tide. Although further investigation is needed for improvement of the device to obtain more accurate and reliable data, the device has a potential utility to provide fundamental data to understand the seawater intrusion and transport mechanisms in coastal aquifers.