• 한국소음진동공학회논문집
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• 제24권5호
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• pp.407-413
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• 2014

The diesel engine and reduction gear combination is one of the common propulsion system in a naval vessel. Since the diesel engine has torsional vibration caused by reciprocating motion of the mass and gas pressure force of the cylinder, high cycle torsional fatigue can be occurred. Therefore, ROK navy restricts the maximum stress of the propulsion shaft according to MIL G 17859D. In this paper, the root cause for the failure of the diesel engine and reduction gear connecting shaft occurred in typical naval vessel is investigated based on the measured bending and torsional moment according to MIL G 17859D procedure.

• 한국자원식물학회지
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• 제11권3호
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• pp.319-325
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• 1998

The developmental changes occuring in the secondary xylem of Aristolochia manshuriensis Komarov have been studied in different ages of vine stems. A. manshuriensis possesses typical storeyed cambium comprising both vertically elongated fusiform initials and almost isodiametric ray cell initials. Stems of A. manshuriensis have wide rays that make the secondary xylem appear dissected as other vine types. The length of vessel member and fiber remained relatively constant throughout the secondary growth. However, vessel diameter increases with the increasing age of stem till the cell reaches their maximum limit and later more or less stabilize in diameter while number of vessel per $\textrm{mm}^2$ is vice versa. Width and relative proportion of ray to axial elements gradually increased with the increasing age of stem and later remained relatively constant.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 1995년도 춘계학술발표회 논문집
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• pp.59-64
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• 1995

The impediment in enhancing the ship safety and combating vessel-source marine pollution depends on the combination of the immediate and mediate factors. The former is mainly caused by human errors and failure in compliance with the international convention standards in operation of compliance with the international convention standards in operation of vessel. The latter by the attitudes and activities of some of the flay states taking little responsibilities with appropriate seriousness in policing their fleets due to the lack of implementing capability of adminstrations. So long as there exists a large size of variation in implementing capability of administration between flag states a globally remarked progress cannot expect to be made in assuring the ship safety and preventing the vessel-source pollution Therefore a new regulatory regime is suggested to be adopted by IMO to maintain high standard flag state adminstrations by recommending standard paradigm to member states so that the development of a implementing culture is encouraged and supported.

• 한국해안해양공학회지
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• 제10권2호
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• pp.64-72
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• 1998

해저자원개발에 사용되는 riser나 TLP의 인장각과 같은 세장해양구조물의 파랑 및 상단부유체의 운동에 대한 동적거동해석을 수행하였다. 구조부재의 유한요소모델을 사용한 수치해석기법을 개발하고 규칙파에 대한 시간영역해석을 수행하였다. 본 연구는 상단부유체의 수평 및 수직운동이 구조물의 횡방향거동에 미치는 영향을 분석하였으며, 특히 부유체 수직운동의 영향을 주로하여 패러미터연구를 수행하였다. 수심, 파랑조건 그리고 부유체운동 등 여러경우에 대한 구조물의 변의, 휨응력을 비교검토하였고, 이 해석을 통하여 부유체의 수직운동에 의한 시간변화 인장력으로 야기되는 불안정조건을 검토하였다. 예제해석결과, 부유체의 수평 및 수직운동의 상호작용으로 riser의 동적응답이 증폭되었다. TLP 인장각의 경우 부유체의 수직운동효과가 구조물의 거동에 상당히 크게 작용하는 것으로 나타났다.

• Journal of Plant Biology
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• 제34권3호
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• pp.191-199
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• 1991

This study has been conducted to investigate the developmental changes of cambial initials and their derivatives in relation to the growing girth of tree in Diosypros kaki and Firmiana simplex. In D. Kaki and F. simplex with typical storeyed cambium, increase in the girth of camium occurred by radial anticlinal division in general, however occasionally the increase was companied by pseudotransverse division. The length of fusiform initials, vessel member, and sieve tube member remained relatively constant throughout the secondary growth but that of fiber showed general tendancy to increase with growing girth of tree. During the girth increase of tree, height and number of ray remained constant in D. kaki, however in F. simplex, height of ray markedly decreased while the number of ray per unit area more or less increased. The secondary ray was originated from the segmentation or division of the side or end of fusiform initials.

• Journal of Plant Biology
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• 제36권3호
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• pp.251-257
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• 1993

The size variation of the cambial initials and their derivatives, in relation to the increase of girth, in the intact and decapitated stem of Populus euramericana was anatomically studied. In the typical nonstoried cambium of P. euramericana, the cell size of fusiform initials, vessel member, and sieve tube member were gradually increased and thus it reached a maximal state. In the intact plants, the size of the cambial initials and their derivatives was larger then in the decapitated ones. On the other hand, the frequency of anticlinal division of the cambial cells, the rate of the elongation and loss of the daughter initials in the intact plants was higher than in the decapitated ones. The cambium of the intact plants had higher ray compared with that of the decapitated ones. It was interpreted that these results were caused by the decapitation, which could block the supply of certain substances for cell growth such as hormones and metabolites.

• 수산해양교육연구
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• 제16권2호
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• pp.238-256
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• 2004

As the UN Fish Stocks Agreement has come into effect since 2001, the actual enforceable management on fish stocks in high seas has started. The Regioanl Fisheries Organizations (RFOs) have emerged as management bodies with a real responsible right to manage fish stocks. RFOs establish a strong and strict management rules providing a fishing right only to member countries and preventing all fishing activities from fishing vessels of non-member countries. In addition, RFOs have an own allocation way of fishing opportunity in their waters so that they can prevent the depletion of fish stocks. It is investigated that deep-sea fisheries have a negative impact from strengthening of RFOs' management right. As the amount of catch is reduced by the control of fishing vessel's activities, the level of fishing revenue becomes low. Moreover, as fishing costs such as oil, fishing fees, labor cost increase significantly, the condition of fishing business is getting worse as a result. In order to gain a fishing right for deep-sea fishing vessels in RFOs waters, there is no other alternative way but become a member of RFOs which are relevant to our fisheries but not joined.

• 대한기계학회논문집A
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• 제28권12호
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• pp.1877-1885
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• 2004

The purpose of this study is to show pressure distribution of the bearing girder in large vessel engine and to consider finite elements analysis using the pressure distribution. Various kinds of the exciting forces act on a bearing girder. And at the same time, it is necessary to consider the contact between a crankshaft and a bearing girder because a bearing girder supports a crankshaft. However it is to need the computer resource with much time if we apply the contact element to a complex solid model and perform a repeated analysis. Thus we have accomplished a contact analysis in the simplistic finite element model of the bearing girder. After that we take a pressure distribution, and apply this to actual finite element model and accomplish finite element analysis. The result of stresses and strains has been produced using superposition method. The concept of superposition method is to find the resultant deflection of several loads acting on a member as the sum of contributions of individual loads. The results were compared with measured results and were verified to be accurate. Resulting analyzed strain favorably coincides with measured strain. The experiment result justifies this paper method.

• 해양환경안전학회지
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• 제2권S1호
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• pp.53-73
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• 1996

Almost of all the impediments to enchancing ship safety and preventing vessel-source marine pollution arise from the interaction between direct and indirect factors. The direct factors come from human errores and failure in complince with the international convention standards for the operation of vessels. The indirect factors derive from the will and attitudes of the countries taking little responsibilities with appropriate seriousness for policing their fleets. By focusing in these aspects, this paper intends to propose a new international regime to improve the implementation capability of national maritime administration of each member government of IMO(International Maritime Organization).

• Journal of Advanced Research in Ocean Engineering
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• 제1권4호
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• pp.239-251
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• 2015

In this study, a spectral fatigue analysis was performed for the topside structure of an offshore floating vessel. The topside structure was idealized using beam elements in the SACS program. The fatigue analysis was carried out considering the wave and wind loads separately. For the wave-induced fatigue damage calculation, motion RAOs calculated from a direct wave load analysis and regular waves with different periods and unit wave heights were utilized. Then, the member end force transfer functions were generated covering all the loading conditions. Stress response transfer functions at each joint were produced using the specified SCFs and member end force transfer functions. fatigue damages were calculated using the obtained stress ranges, S-N curve, wave spectrum, heading probability of each loading condition, and their corresponding occurrences in the wave scatter diagrams. For the wind induced fatigue damage calculation, a dynamic wind spectral fatigue analysis was performed. First, a dynamic natural frequency analysis was performed to generate the structural dynamic characteristics, including the eigenvalues (natural frequencies), eigenvectors (mode shapes), and mass matrix. To adequately represent the dynamic characteristic of the structure, the number of modes was appropriately determined in the lateral direction. Second, a wind spectral fatigue analysis was performed using the mode shapes and mass data obtained from the previous results. In this analysis, the Weibull distribution of the wind speed occurrence, occurrence probability in each direction, damping coefficient, S-N curves, and SCF of each joint were defined and used. In particular, the wind fatigue damages were calculated under the assumption that the stress ranges followed a Rayleigh distribution. The total fatigue damages were calculated from the combination with wind and wave fatigue damages according to the DNV rule.