• International Journal of Naval Architecture and Ocean Engineering
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• 제8권5호
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• pp.423-433
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• 2016

In this paper, we consider the cybersecurity issue of ship information system (SIS) from a new perspective which is called opacity. For a SIS, its confidential information (named as "secret") may be leaked through the working behaviors of each Distributed Control Unit (DCU) from an outside observer called an "intruder" which is able to determine ship's mission state by detecting the source of each data flow from the corresponding DCUs in SIS. Therefore we proposed a dual layer mechanism to enforce opacity by activating non-essential DCU during secret mission. This mechanism is calculated by two types of insertion functions: Safety-assured insertion function ($f_{IS}$) and Admissibility-assured insertion function ($f_{IA}$). Due to different objectives, $f_{IS}$ is designed to confuse intruder by constructing a non-secret behaviors from a unsafe one, and the division of $f_{IA}$ is to polish the modified output behaviors back to normal. We define the property of "$I_2$-Enforceability" that dual layer insertion functions has the ability to enforce opacity. By a given mission map of SIS and the marked secret missions, we propose an algorithm to select $f_{IS}$ and compute its matchable $f_{IA}$ and then the DCUs which should be activated to release non-essential data flow in each step is calculable.

• 유통과학연구
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• 제13권7호
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• pp.11-18
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• 2015

Purpose - This paper reviews the changes in the ship export and import structure between Korea and China. It utilizes the comparative advantage trade theory to analyze time-series statistical data from the market share index, revealed comparative advantage index (RCA), and trade specialization index(TSI). Research design, data, and methodology - Based on their economic phases, both Korea and China have similar country characteristics. The purpose of this research is to understand the two country's trade structures to fortify the Korea-Sino economic relationship including verifying what is working and what is not. Results - Based on the analysis, bilateral economic activity to achieve a plus trade stimulus environment should be realized in the long run. Both countries should establish guarantee-free trade negotiations and boundaries instead of various non-tariff barriers. Conclusion - Reviewing the research, a sound competitive relationship can be grown for mutual benefit including export market diversification in the near future. The review of the Korea-Sino ship industry is keenly important and investigative research about it is timely because it is a major industry in each country.

• 수산해양기술연구
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• 제48권2호
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• pp.147-154
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• 2012

In head sea, a ship has mainly the longitudinal motion such as vertical acceleration and pitch. In that case, the motion characteristics of a ship will have changed as the location different from each of place vertically and horizontally on board. The author carried out an experiment about the ship's vertical acceleration and pitch according to the location for the head sea, and analyzed the data with the aid of the statistical and spectral analyzing method to get the motion characteristics of the vessels. The response of vertical acceleration and pitch not deeply depend on the decks vertically, but displayed the relative big different value horizontally even if same deck. The biggest response of vertical acceleration and pitch among the accommodations was shown at scientist room, but the value of it not reached to the minimum requirement of ISO 2631-1 for working on board.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2014년도 추계학술대회
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• pp.167-168
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• 2014

연안여객선은 도서민의 감소로 인한 경영수지악화로 신규선 투입과 운항 횟수 증가와 같은 서비스 개선을 기대하기 어렵다. 또한 안전관리의 미흡과 낮은 임금 및 근로 환경의 문제로 우수 선원의 수급이 어려워 선박 운항의 안전성 또한 문제가 되고 있다. 공공성과 안전성 확보를 위해 공영제를 도입한 운영체계 개선이 필요하다. 여러 현실적 제약이 있지만 보조항로부터 시행하면서 안전관리 강화 등을 통해 부실한 업체의 면허를 회수해 공영항로를 확보해 간다면 공영제를 통한 운영체계 개선이 가능할 것이다.

• 대한조선학회논문집
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• 제52권2호
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• pp.135-142
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• 2015

The Anti-Rolling Tank(ART) has an advantage over the other roll stabilizing devices, when ship is staying and working at one site of sea. An important design point of ART is the tank tuning, that is, matching the tank natural period to the ship's roll natural period. Since the load condition and consequently the roll natural period of ship is to be changed widely, the natural period of ART also has to be changed widely. In case of the existing U-tube type ART with a single layer duct, the tank natural period can be changed in a relatively narrow range. This paper suggests a new U-tube type ART system using a double layer duct to enable wide change of ART natural period. Through the roll experiments performed in regular beam waves for a box-type model ship, it is shown that the double layer duct ART has about two times wider period range and a better reducing effect of roll magnitude than the single layer duct ART.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 춘계학술대회 논문집
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• pp.91-96
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• 2011

The ship working environment of combat service support boat is very inferior to the ground working environment. For this reason, the crew of a combat service support boat suffer from an occupational disease such as hardness of hearing. Owing to its small size and low status, the improvement of its working and residential environment is occasionally ignored and its indoor noise was not fully investigated. In this study, for improving its residential environment indoor, the indoor noise of its shipboard compartments was analysed.

• 해양환경안전학회지
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• 제29권7호
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• pp.950-957
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• 2023

선박이 부두에 안전하게 계류 및 예인하기 위해서는 관련 국제규정에 부합하는 설계를 해야 한다. 그러나 현재까지도 일부 소형 조선소 및 설계 회사에서는 그 내용을 정확히 숙지하지 못하고 있는 경우가 많다. 따라서 본 논문에서는 예인 및 계류설비에 관한 국제규정을 살펴보고, 최신 발효된 MEG4(Mooring equipment guideline 4) 기준에 만족하는 대표적인 계류 의장품인 볼라드(Bollard)와 쵸크(Chock)를 개발하고자 한다. 볼라드는 계류 밧줄을 선체에 고박하기 위한 의장품이며, 일반적으로 2개의 기둥으로, 대부분은 8자 매듭 형태로 사용하고 있다. 쵸크는 선외에서 선내로 들어오는 계류 밧줄의 방향을 전환하고, 밧줄의 손상을 방지하기 위하여 곡률을 갖는 주물방식으로 제작한다. 이 두 가지 계류 의장품은 선박의 선수와 선미, 중앙부 측면에서 많이 사용되고 있다. 최근 컨테이너선 및 LNG 운반선의 크기 증가로 인하여, 계류 밧줄 하중이 증가하고 있으며, 계류 의장품도 안전사용하중(Safe working load)이 변경되어야 한다. 본 연구에서는 유한요소해석 모델링을 통한 허용응력 평가법 결과를 정리하고, 분석하였다. 추가적으로 비선형 붕괴 거동 평가를 통하여, 안전사용하중 결정에 대한 검증을 수행하였고, 탄성영역 내 설계가 되었음을 확인하였다. 연구에서 제안하는 평가법 및 기준, 그리고 해석절차는 향후 유사 의장품 개발 시 참조가 가능하다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2006년도 추계학술발표회
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• pp.125-129
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• 2006

사람의 청각에 영향을 미치는 구역에 설치된 가전용품 및 기계에서 발생하는 소음을 저감하는 것은 중요하다. 특히 선박의 기관실에서 발생하는 소음은 저감이 불가능한 것으로 알려져 개선의 정도가 미미할 뿐 아니라 작업자의 청력손실이 발생하는 최악의 작업환경에 놓여져 있는 실정이다. 그러나 최근에 발전되고 있는 모니터링설비와 지능제어시스템을 이용하면 기관실의 주 엔진을 개방 해 둘 필요가 없어지게 되었다. 따라서 주 엔진의 주변을 흡음 및 차음벽으로 차단하여 기관실의 소음을 개선할 수 있는 계기가 되고 있다. 본 연구에서는 소음을 흡수할 수 있는 차음벽의 성능을 높이기 위해 헬름홀츠 공영기의 원리를 적용한 흡음벽에 대하여 연구하였다.

• Journal of Welding and Joining
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• 제27권2호
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• pp.32-37
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• 2009

In shipyard, plate forming is widely used to form the ship hull plate in various shapes. Line heating method by using a flame torch is one of the major shipbuilding processes carried out by skilled workers. Since the forming characteristics depend upon their experiences in manual forming, there are much variations between products and difficulties in communication between engineers and workers. Hence, it needs to develop an automatic forming system which can not only reduce the working time and rework costs but also improve the working environment and hull forming productivity. One of the final goals of plate forming automation is to form a target shape from the initial plate automatically. For automated plate forming, it is required to determine where and how to heat on the plate. To realize this procedure, the inverse problem should be first solved and the effect of curvature shape formed at the heating path should be investigated. In this study, the inverse problem was solved by geometrical approach using the relationship between bending angle and radius of curvature of the curved shape. In addition, experiments of two-dimensional plate forming were performed with the distance-based method considering the curved bending with curvature. The result of the formed shape agreed considerably well with the target shape.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.333-335
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• 2006

Position of surface objects can be fixed in many ways. The most popular radionavigational systems, including satellite systems, make possible obtaining nearly continuous and very precise ship's position. However, under the water application of radionavigational systems is impossible. Underwater navigation requires other tools and solutions then these encountered in surface and air navigation. In underwater environment vehicles and submarines, operate that have to possess alternative navigational systems. Underwater vehicles, in order to perform their tasks require accurate information about their own, current position. At present, they are equipped with inertial navigational systems (INS). Accuracy of INS is very high but in relatively short periods. Position error is directly proportional to time of working of the system. The basic feature of INS is its autonomy and passivity. This characteristic mainly decides that INS is broadly used on submarines and other underwater vehicles. However, due to previously mentioned shortcoming i.e. gradually increasing position error, periodical calibration of the system is necessary. The simplest calibration method is surface or nearly surface application of GPS system. Another solution, which does not require interruption of performed task and emergence on the surface, is application of comparative navigation technique. Information about surrounding environment of the ship, obtained e.g. by means sonic depth finder or board sonar, and comparing it with accessible pattern can be used in order to fix ship's position. The article presents a structure and a description of working of underwater vehicle navigation system simulator. The simulator works on the basis of comparative navigation methods which exploit in turn digital images of echograms and sonograms. The additional option of the simulator is ability to robust estimation of measurements. One can do it in order to increase accuracy of position fixed with comparative navigation methods application. The simulator can be a basis to build future underwater navigation system.