• 대한조선학회논문집
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• 제55권5호
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• pp.421-430
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• 2018

The shape of a yacht sail made of thin fabric materials is easily deformed by wind speed and direction and it is affected by the deformation of the standing rig such as mast, boom, shrouds, stays and spreaders. This deformed sail shape changes the air flow over the sail, it makes the deformation of the sail and the rig again. To get a sail performance accurately these interactive behavior of sail system should be studied in aspects of the aerodynamics and the fluid-structure interaction. In this study aerodynamic analysis for the sail system of a 30 feet sloop is carried out and the obtained dynamic pressure on the sail surface is applied as the loading condition of the calculation to get the deformations of the sail shape and the rig. Supporting forces by rig are applied as boundary condition of the structure deformation calculations. And the characteristics of the air flow and the dynamic pressure over the deformed sail shape is investigated repeatedly including the lift force and the location of CE.

• 항공우주산업기술동향
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• 제8권2호
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• pp.24-30
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• 2010

우주태양광 비행은 별이나 레이저에서 나오는 빛의 복사 압력을 이용하여 아주 얇은 물질을 매우 빠른 속도가 되도록 하는 위성체 추진을 위한 방법 중 하나이다. 이에 관한 연구는 미국, 일본, E.U. 그리고 러시아 등에서 기초 연구를 비롯한 우주 비행 시험을 수행하고 있다. 2010년 5월 일본의 JAXA는 세계 최초로 태양광 돛을 가진 행성간 위성체인 "IKAROS"를 금성까지 발사하는데 성공한 바 있다. 현재 태양광 추진 방법으로 태양계를 포함한 은하계에 많은 무인 우주 비행 임무를 수행하고자하는 목표를 가지고 있다. 본 논문에서는 우주 탐사 및 여행을 위한 새로운 추진 방법으로 우주 선진국들의 우주태양광 비행선의 기술 동향에 대해 기술하였다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2003년도 춘계학술발표회
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• pp.141-151
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• 2003

In this study the writer would like to study the art of navigation in the Era of Silla. For the purpose of this study, the writer studied ship's log book of Ennin's Diary, the ancient ship's structures of Korean, Chinese, Japanese, winds and ocean currents around Korean Peninsular which effect the navigation of sailing ship, and ancient reference books and materials. The result of this study. in the ship's structure in the Era of Silla. bottom structure is considered flat and V-Shaped type, and sailing ship had anchor, sail, considerable deckhouse, transverse bulkhead. And the ship's main materials of sailing ship was wood. partially used irons in the panting structures. In the art of navigation, navigators used winds, ocean current, anchor, sail, depth and color of sea water, lights, ballast. Especially navigators used astrologers and geomancers for astronomical observation, weather forecast, natural phenomena.

• 한국해양공학회지
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• 제11권3호
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• pp.144-152
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• 1997

본 논문에서는 1년생 빙맥에 의하여 해양구조물에 작용하는 하중을 추정할 수 있는 모델을 제시하였다. 1년생 빙맥을 수면하부(keel), 수면상부(sail), 경화층(consolidated layer)의 3부분으로 나누어 각 부분에 의한 하중을 추정할 수 있는 방법을 논의하였다. 수면하부는 얼음조각(ice rubble)이 층으로 쌓여져 형성된 것이므로 수면하부에 의한 하중추정을 할 때 얼음조각을 선형 Mohr-Coulomb재료로 생각하여 토질역학(soil mechanics)의 이론을 사용하였다. 수면상부에 의한 하중도 토질역학 이론을 이용하여 추정하였으며 경화층에 의한 하중은 Korzhavin식을 이용하여 추정하였다. 제시한 모델을 이용하여 빙맥하중 추정에 미치는 인자들의 영향을 검토하였다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1997년도 Proceedings of KIN-CIN Joint Symposium 97 on Safety of Shipping and History of Maritime Communication between Korea and China around 9th Century
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• pp.185-202
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• 1997

Hull forms of ancient ships in Korea and China have been changed according to their voyages and routes. Therefore it is necessary for shipbuilding engineers to reestablish the ancient shipbuilding history, and to presume, restore and revive the lost cultural inheritances. We, however, do not have many historical documents or credible materials that can our ancestors' great shipbuilding techniques : at the same time we do not have paid much attention to the research on such documents and materials. This paper aims not only to study and compare shifting process of ancient ship's hull forms in Korea and China by making use of verifiable materials obtained in the process of excavating and restoring Shinan ancient ship. The results of comparing structural characteristics and hull forms of ancient ships in Korea and China and as follwing : (1) Korean ancient ships have transverse beam instead of frame . Judged from the bottomform, Korean ancient ships are grooved clinker type ships of flat bottom type, in which bottom planking is fixed by wooden bar. (2) Chinese ancient ships have transverse bulkhead structure instead of frame, Judged from the bottom form , Chinese ancient ships are rabetted clinker type ships of V-bottom type with a bar keel. The form , the position, and the size of a sail are closely related with the wind force. It is not only quite difficult to presume forms and sizes of ancient ships' sails precisely, but also impossible to come to an accurate conclusion wihtout much experience. Current 10-year-statistics of the wind force are used to obtain presumed routes of ancient ships in Korea and China. Conclusions obtained from the hull form , sail form and size , and mast height of Shinan ancient ship will provide credible data for sea trade routes and transformation capability, and wil be used for effective materials on the study of the shifting process of ancient ships in Korea and China.

• Advances in materials Research
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• 제2권3호
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• pp.155-172
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• 2013

The study of the corrosion inhibition of armatures made of steel conceived for reinforced concrete by sodium phosphate is the aim object of our experimental tests. Gravimetric and electrochemical measurements were carried in three different Mediums contaminated by chlorides (3% NaCl) with addition of increasing concentrations of sodium phosphate. Inhibitory efficiency reached 80% at an optimal concentration of $7,5{\times}10^{-3}M$, the results obtained using the gravimetric measurements are in good agreement with those obtained by electrochemical methods. However, the monitoring of the pH evolution after 24h shows in the three studied environments, that the pH decreases slightly at 24 hours from the initial pH at $t_0$, due to the presence of corrosion products which change the state of the final solution. Also, scanning electron microscopy revealed the existence of layers of apatite on the metal surface previously treated with the sodium phosphate which confirms the formation of a protective film around the surface of the metal.

• 수산해양교육연구
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• 제15권1호
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• pp.123-133
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• 2003

The present investigations were carried out for the most and fundamental elements, what is called maneuverability, stability, safety, rig, sail about the world famous race, VOLVO60 and America's cup. The results obtained are summarized as follows: First, the structure of yacht should be designed with focuse on the preparation for the preparation of collision with other yachts around, with the dumps of iceberg and also whales nearby. At the same time, the accurate calculation on the each structure and equipment of yacht should be processed for the dynamic stability in the rainstorms. Second, VOLVO60, long-distance sailing, should be emphasized on the light weight and the safety, while the boat for America's cup, short-distance sailing, should be stressed on the appropriate weight of the body and the maximum speed for fast maneuverability. Third, up-to-the minute materials should be developed for the appropriate wind power and the turning of directions.

• Advances in materials Research
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• 제2권3호
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• pp.173-180
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• 2013

Lead-free complex perovskite ceramics $NaMeO_3$ ($Me{\equiv}Nb$, Ta) were synthesized using conventional solid state reaction technique and characterized by structural, FTIR and electrical (dielectric and ac conductivity) studies. The crystal symmetry, space group and unit cell dimensions were determined from the experimental results using FullProf software. XRD analysis of the compound indicated the formation of single-phase orthorhombic structure with the space group Pmmm (47). Dielectric studies showed the diffuse phase transition at $394^{\circ}C$ for $NaNbO_3$ and $430^{\circ}C$ for $NaTaO_3$. Ac conductivity in both the compounds follows Jonscher's power law.

• 대한공업교육학회지
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• 제33권2호
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• pp.154-169
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• 2008

이 연구의 목적은 초 중등학교 학생들에게 수송 기술에 대한 흥미 및 지식, 기능, 태도를 기르고 나아가 역사 인식을 제고할 수 있는 교수-학습 자료인 학습용 모형 거북선을 개발하는 것이다. 먼저 문헌 연구를 수행하고, 모형 거북선의 구조와 구동방법 살핀 후, 모형거북선을 만들었다. 이 연구를 통하여 얻은 주요 결과를 요약하면 다음과 같다. 첫째, 학생들이 직접 제작하고 실험함으로써 설계 능력, 제작 능력, 탐구 능력 및 기술적 소양을 함양할 수 있도록 모형 거북선을 개발하였다. 둘째, 구동에너지에 따라 자연에너지를 이용한 돛, 태양에너지를 이용한 태양전지, 기계적인 에너지를 이용한 링크장치 및 스크루를 활용한 학습용 모형 거북선을 개발하였다. 셋째, 수송 영역에서 선박에 대한 관심과 흥미를 유발할 수 있도록 물 위에서 무선 조작으로 작동하는 모형 거북선을 개발하였다. 넷째, 역사적으로 의미 있는 전통 문화 유산인 거북선을 초 중등학교 기술 교과에서 실험 실습 교수-학습 자료로 활용할 수 있도록 개발하였다.

• Corrosion Science and Technology
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• 제10권4호
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• pp.136-142
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• 2011

Al alloys have been used widely for commercial and military ships in most ocean countries since mid-1950s, and the value as light metal with high mechanical strength has been proven. As the safety and fuel efficiency of Al ships have improved, she can carry more freight, sail faster and travel longer distances. Furthermore, in the shipbuilding industry, Al alloys are applied as structural materials for ships to various areas including the deck of luxurious cruises, battleships and leisure ships. In addition, Al alloys are being spotlighted as environmental-friendly material as they can be recycled even after end of lifespan. However, Al alloys for ships must be carefully selected after considering corrosion resistance, endurance, strength, and weldability in sea water environment. Al alloys to satisfy these conditions are used widely include 5000 series Al-Mg alloy and 6000 series Al-Mg-Si alloy. Thus, this study selected and evaluated the cavitation characteristics of the 5000 series Al alloys that are used in hulls that directly contact seawater and the 6000 Al alloys that are used in the upper structures of ships. Results of cavitation test with time, weightloss and cavitation rate of 5456-H116 showed the smallest damage among 5052-O, 5456-H116 and 6061-T6.