• Journal of Navigation and Port Research
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• v.39 no.6
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• pp.439-450
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• 2015

This study objects to find characteristics in chemical tanker markets and to determine optimal chemical tanker size using a total shipping cost in main trading route of asia chemical tankers .Precedent studies of determination of the optimal ship size and case studies about chemical tankers was carried out and tried to introduce a cost model which is applicable to chemical tanker. This study is dependant on numerical analysis and involves scenario analysis to minimize sensitivity of results. This analysis shows as follows. First, 12,000DWT tanker is an optimal size on the 'Far East-Middle East' services, 9,000DWT tanker is a most competitive on the 'Far East-South East Asia' services and 3,000DWT tanker is a most economic size on the 'Inner Far East' services at average market situation. Second, the bigger size of chemical tanker, the more competitive advantage the tanker will obtain when bunker fuel prices rise. Small size ship gets more competitive during bunker prices down. Third, market fluctuation of time charter rate for chemical tanker is less than 20% against its average time charter hire which means less volatile. And tanker's competitiveness per each size is remained mostly same when time charterer rates rise at same proportion. Fourth, bigger size chemical tankers have cost advantages when tanker's quantity of each part cargo increase. And small-sized tanks are more competitive when part cargo scales decrease. For the last, ship's port stay strongly influences on the determination of the optical tanker size. When vessel has shorter port stay, bigger-sized tanker will be more competitive and even can be competitive if applies in short voyage as well.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.225-231
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• 2013

Liquefied gas carriers generally transport cargoes of flammable or toxic nature. Since these cargoes may cause an explosion, fire or human casualty, the accommodation spaces, service spaces and control stations of liquefied gas carriers should be so located as to avoid ingress of gas. For this reason, the paragraph 8.2.9 of IGC Code in IMO requires that the height of vent exits should be not less than B/3 or 6 m whichever is greater, above the weather deck and 6 m above the working area and the fore and aft gangway to prevent any concentration of cargo vapor or gas at such spaces. Besides as known, the LNG market has been growing continually, which has led to LNG carriers becoming larger in size. Under this trend, the height of a vent will have to be raised considerably since the height of a vent pipe is generally decided by a breadth of a corresponding vessel. Accordingly, we have initiated an examination to find an alternative method which can be used to determine the safe height of vent masts, instead of the current rule requirement. This paper describes the dispersion characteristics of boil-off gas spouted from a vent mast under cargo tank cool-down conditions in the membrane type LNG carriers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.2
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• pp.171-178
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• 2013

This paper presents the Part 1 of the Questionnaire Survey on Marine Safety and VTS in the Philippine Coastal Waters. This part deals with respondents profiles; experiences onboard and ashore; familiar areas; and their subjective perception of marine risks- by factors and by areas. The subjects are chosen from different regions nationwide with connection and/or with maritime background. There are 202 responses returned and these are put into a database for analysis made through Excel programs and statistics references. The result of the nationwide responses show that 97 % of respondents have shipboard experiences onboard of different ships' types and sizes; and 88 % are directly involved in the navigation of ships. Risk Perception levels - by factors and by familiar areas - show a higher risk degree in the 3rd level ('Sometimes Increases Risks') and 4th level ('Often Increases Risk') in each respondents' response indices. The study finds that the most risky factor is the "Violation of Rules and Regulations" which has a high risk at 5th level (Very Often Increases Risk), and for the over-all familiar areas, the Manila Bay area (NCR region) garners the most risky perception, also, at the 5th level. It is, therefore, recommended by this paper to conduct a comprehensive review of the rules and regulations viable in each locality; strengthening the maritime traffic systems, structures and educating the stake-holders specifically in Manila Bay area and other busy waterways of the country. The ultimate goal of this paper is to gather information, analyze these data and develop a set of tools and techniques to be utilized as a guide in the improvement and development of maritime traffic safety in the country.

• Korean Journal of Cognitive Science
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• v.19 no.4
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• pp.419-441
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• 2008

As the Web and digital libraries have become a commodity, they are used for a variety of purposes and tasks that may require a great deal of cognitive efforts. However, most search engines in the Web and digital libraries support users with only searching and browsing capabilities, leaving all the cognitive burdens of manipulating information objects to the users. We propose a two-level model for human-Web interactions, consisting of knowledge and information spaces, and a tool that provides knowledge space and inter-space operations in addition to searching and browsing at the information level. Knowledge space is an explication of user's conceptual view of the information objects being explored through interactions with the Web or a digital library. Topics are created and related with associations at the knowledge level and connected to information objects in information space. The tool implemented using the Topic Maps framework has been tested for efficacy as an aid to reducing cognitive burden under exploratory search task.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.109-111
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• 2006

본 논문은 애니메이터로 하여금 얼굴 표정들의 공간으로부터 일련의 표정을 선택하게 함으로써 3차원 아바타의 표정을 실시간적으로 제어할 수 있도록 하기 위한 표정공간의 생성방법에 관하여 기술한다. 본 시스템에서는 약 2400여개의 얼굴 표정 프레임을 이용하여 표정공간을 구성하였다. 본 기법에서는 한 표정을 표시하는 상태표현으로 얼굴특징 점들 간의 상호거리를 표시하는 거리행렬을 사용한다. 이 거리행렬의 집합을 표정공간으로 한다. 그러나 이 표정공간은 한 표정이 다른 표정까지 이동할 때 두 표정간의 직선경로를 통해 이동할 수 있는 그런 공간이 아니다. 본 기법에서는 한 표정에서 다른 표정까지 거쳐 갈 수 있는 경로를 캡쳐된 표정 데이터로부터 근사적으로 유추한다. 우선, 각 표정상태를 표현하는 거리행렬간의 거리가 일정 값 이하인 경우 두 표정을 인접해 있다고 간주한다. 임의의 두 표정 상태가 일련의 인접표정들의 집합으로 연결되어 있으면 두 표정간에 경로가 존재한다고 간주한다. 한 표정에서 다른 표정으로 변화할 때 두 표정간의 최단경로를 통해 이동한다고 가정한다. 두 표정간의 최단거리를 구하기 위해 다이내믹 프로그래밍 기법을 이용한다. 이 거리행렬의 집합인 표정공간은 다차원 공간이다. 3차원 아바타의 얼굴 표정 제어는 애니메이터들이 표정공간을 항해할 때 실시간적으로 수행된다. 이를 도와주기 위해 표정공간을 차원 스케일링 기법을 이용하여 2차원 공간으로 가시화하였고, 애니메이터들로 하여금 본 시스템을 사용하여 실시간 표정 제어를 수행하게 했는데, 본 논문은 그 결과를 평가한다.참여하는 빈들 간의 관계를 분석하여 워크플로우에 대한 성능 측정이 가능하도록 한다. 또한 제안된 메트릭을 통하여 EJB 어플리케이션의 성능 향상을 도모할 수 있도록 한다.로 표면 위로 자라났고, 부종은 창상 밑 조직까지 감소하였으며, 육아조직은 교원질 섬유로 대체되었다. 창상 유발 21일 후, 다른 창상에 비해, HG 처치창은 유의적으로 창상 표면이 거의 재생성 상피로 덮였으며, 육아조직은 창상 유발 14일 후와 비교해서 유의적으로 교원질 섬유로 대체되었다. 위의 모든 결과에서 보듯이, 개에서 전층피부 창상의 처치 시 HG의 사용은 HC와 생리 식염수에 비해 창상치유 복구기의 치유 속도를 촉진하는 것으로 사료된다.시범학교의 자녀를 들 부모들은 환경관련문제에 대한 의식 및 환경관련 제품에 대한 구매행동의 변화가 두드러지게 나타났다.EX>$d^{2+}$ + SA처리구는 두 화합물의 이중 효과에 의해 전반적인 생리 활성을 억제하여, 결국에는 식물의 고사를 유도하는 것으로 사료된다.목에 대한 보안'이 가장 중요한 것으로 나타났다. 본 연구에서는 솔루션 선정요인에 관한 중요도를 e-마켓플레이스의 유형과 산업 별로 평가해보았는데, 여기에서 밝혀진 중요도를 통해 e 마켓플레이스를 구축하고 자 하는 기업은 솔루션을 자체 개발하거나 구입할 때 올바른 의사결정을 할 수 있다. 그리고 솔루션을 제공하려는 기업측면에서는 e-마켓플레이스를 구축하고자 하는 기업에게 유형과 산업별로 적절한 솔루션을 제공할 수 있다.순환이 뇌대사 및 수술 후 신경학적 결과에 보다 유익한 효과를 제공해 줄 수 있음

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.1
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• pp.49-57
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• 2016

Recently, marine accidents such as the sinking accident Mongol freighter ship and the sinking accident of Sewol ferry in Jindo continuously happen. In order to decrease the number of these marine accidents, Korean ships are obliged to follow the AIS(Automatic Identification System) system. The AIS protocol includes all information for sailing ships. However, the standard AIS protocol does not provide any security function, In addition, it is possible to hijack the standard AIS protocol in case of using a satellite communication device called FUNcuve Dongle Pro+. Therefore, this paper analyzes weak points of the security in the standard AIS protocol. Furthermore, this paper ensures reliability by marking the MAC Address of sender and receiver for secure communication and suggests the protocol that can securely send data, using the VPN Tunnelling method. Therefore, the suggested AIS protocol provides the secure communication to the AIS protocol and protect the messages in the AIS protocol, which can serve safe voyages by decreasing the marine accidents.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2331-2338
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• 2014

The HEMP threat may have acquired new, and urgent, relevance as the proliferation of nuclear weapons and missile technology accelerates of the North Korea, for example, is assessed as already having developed few atomic weapons, and is on the verge of North Korea already has missiles capable of delivering a nuclear warhead against South Korea. ITU K.78, K81 and IEC recommended its counter-measuring for the industrial facilities with navigation and sailing facilities in order to obviate the all of processor equipped system malfunctions from the EMP/HEMP but its simulation must only be done by the computer simulation which had studied on the 1960-1990 years USA/AFWL papers. This result has a significant activities to the South Korea being under the North Korea threat because all of HEMP related products was strongly limited for export. The HEMP cord which was developed newly by the KTI including the HEMP generation & propagation analysis, optimal shelter design tool, essential EM energy attenuation in multi-layered various soils and rocks and HEMP filter design tool. Especially, the least square fitting method was adopted to analysis for the EM energy attenuation in the soils and rocks because it has a various characteristics based on the many times field test reports.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1930-1936
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• 2007

Electronic Navigational Charts(ENCs) are official nautical charts which are equivalent to paper charts with supplementary information. Although their main purpose is to be used for the safe navigation of ships, they also contain much information on coasts and seas which may be interesting to ordinary people. However, there is no easy way to access them because of their specialized data format, access method and visualization. This paper proposes m implementation of SVG for the access and services of ENCs. SVG(Scalable Vector Graphic) makes it possible to make use of Vector graphics for map services in basic internet browsing environment. Implementation of SVG for ENC applications by this research is free of special server side GIS mapping system and client side extra technology. The Implementation of SVG for ENC Applications can be summarized as follows: Firstly, SVG provides spatial information to possess searching engine to embody SVG map. Secondly SVG can provide high-quality vector map graphics and interactive facility without special Internet GIS system. It makes it possible to use services with very low cost. Thirdly, SVG information service targeting on maritime transportation can be used as template, so it can be used dynamically any other purpose such as traffic management and vessel monitoring. Many good characteristics of SVG in mapping at computer screen and reusability of SVG document provide new era of visualization of marine geographic information.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.574-583
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• 2021

Predicting shipping markets is an important issue. Such predictions form the basis for decisions on investment methods, fleet formation methods, freight rates, etc., which greatly affect the profits and survival of a company. To this end, in this study, we propose a shipping freight rate prediction model for container ships using gated recurrent units (GRUs) and long short-term memory structure. The target of our freight rate prediction is the China Container Freight Index (CCFI), and CCFI data from March 2003 to May 2020 were used for training. The CCFI after June 2020 was first predicted according to each model and then compared and analyzed with the actual CCFI. For the experimental model, a total of six models were designed according to the hyperparameter settings. Additionally, the ARIMA model was included in the experiment for performance comparison with the traditional analysis method. The optimal model was selected based on two evaluation methods. The first evaluation method selects the model with the smallest average value of the root mean square error (RMSE) obtained by repeating each model 10 times. The second method selects the model with the lowest RMSE in all experiments. The experimental results revealed not only the improved accuracy of the deep learning model compared to the traditional time series prediction model, ARIMA, but also the contribution in enhancing the risk management ability of freight fluctuations through deep learning models. On the contrary, in the event of sudden changes in freight owing to the effects of external factors such as the Covid-19 pandemic, the accuracy of the forecasting model reduced. The GRU1 model recorded the lowest RMSE (69.55, 49.35) in both evaluation methods, and it was selected as the optimal model.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.858-862
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• 2018

The purpose of this study is to improve the current vessel departure control regulations to prevent traffic congestion after the lifting of vessel departure controls due to restricted visibility. AIS data was collected to analyze the traffic volume of normal traffic flow and after departure control. A statistical test was conducted to confirm the difference in traffic volume at peak hours according to whether or not departure control was used. The results of the t-test showed that there was a significant difference in traffic volume among groups of less than 10,000 tons in gross tonnage. However, the Mann-Whitney test showed no difference in traffic volume regardless of vessel control. Small and medium-sized vessels of less than 10,000 tons after departure control increased in traffic volume by 142% over normal traffic, and it was concluded that traffic congestion resulted as these small and medium-sized vessels were departing at the same time as large vessels of more than 10,000 tons. In order to prevent vessel collision accidents due to traffic congestion, it is suggested that the navigability of vessels less than 160 m or less than 10,000 tons should be improved.