The collisions at sea among marine casualties are not reduced as the tonnage and speed of ship's increase as well as the traffic quantity increase at sea, in spite of the improvement of nautical equipment, enforcement of crew's education and training as well as improvement of quality standard according to the implementation of ISM code. The measures to prevent the collisions at sea are simple, and are composed of six stage.: The first stage is that the officer on duty detect the target from his eye or radar information. The second stage is determining the type and kind of target-ship. The third stage is target tracking; calculation of target speed, course, CPA and TCPA from radar information or visual check. The fourth stage is determination of vessel in danger after calculation of third stage. The fifth stage is the judgement of situation if own ship is stand-on or give way vessel according to the 1972 COLREG. The last stage is to carry out proper action according to 1972 COLREG, under the circumstances. But by the case, the situations are so different under the different external conditions; for example, natural/navigational conditions, crew's human factors, ship's particular, rule or regulation, management system on board, the condition of watch keeping. Therefore the reasons and casualties are so complicated. This study aims to investigate the collision casualty at sea which needs to clarity all these causal factors of afore-mentioned, and to analyze the causes of problems so as to utilize them to establish the measures of preventing marine accidents. This study, described the concepts of causal factors into three groups; environmental factor, and company/on board management system and navigator's act. Also described how to investigate and analyzes the casual factors. Even though it was described in this paper how to detect the causal factors and reasons of collisions, and how to analyze the inter-relation of each causal factors, it is necessary to do further study how to analyze between the liability of concerned parties and the casual factors involved.

The ships over the certain navigation area or her length are required to carry charts under the relevant laws. Charts are indispensible to the ships and fishing vessel, because their crew should know the water depth and location of obstacle in order to avoid danger in the navigation and fishing area. But it was found that many ships do not carry proper charts onboard according to the research marine accidents files of marine accident inquiry agency, and questionnaire survey. Consequently, many ships run aground on the coast and port. This study examined the present status of the coastal ship and the fishing vessels, and explained some problems in the aspect of the covering area, the place, the number of the selling agent and adjoining chart, as well as the geographical and traffic density, the crew on board the ship's characteristics, and so on. In this study we propose the way to solve the problem. firstly, the category of the fishing vessel which should carry the chart on bard under the related laws are required to be lowered to 10 gross tons. Besides a ship inspector should examine if the charts covering the area where to navigate even when the temporary inspection is done are carried on board property. Secondly, the inspection body or the controlling office of ship's entry and departure should check throughly whether the ships concerned carry the chart on board. Thirdly the fishing vessels should used the fishing charts, and the body concerned should train the offices about how to use chart, especiany the difference between Tokyo datum and WGS-84 datum. Fourthly the customized chart such as an atlas like a map, a calenda-type chart, a small chart, as a coated chart needs to be publish for the safety of small ship and fishing vessel. Fifthly, it is advisable to draw a recommended course in the route where the coastal navigate mainly and in the narrow channel, The adjoining area should be improved, as well as the qualify of the chart paper. Sixthly, publication of additional new chart in the southern part of East Sea, the eastern part of South Sea, the western part of South Sea and middle part of Yellow Sea near Incheon port should be thought over. Seventhly, the number of chart selling agent should be increased for the sake of purchaser in proportion to the number of port, and small correction of charts in selling agent must be carried out completely.

To ensure ship's safety and preserve the marine environment from ship, IMO(International Maritime Organization) has been making much efforts. Nevertheless there are still many possibilities threatening ship's safety and the marine environment. Many vessels navigate at sea in lack of standard required by the International Convention relevant to ship's safety and the protection of marine environment. Even though the administration is responsible for perfect and continuous control for safety of ship, it cannot has jurisdiction over ships hoist its flag reasonably at all times. So the Port State has strengthened the Port State Control(PSC) activity as one step of eliminating sub-standard vessels. In the light of the fact that mentioned above, this study deals with PSC activity in Korea and port of Pusan. Total 582 ships, inspected in port of Pusan from 1st January 1998 to 30th September 1999, were analyzed in various aspect and extracted results as follows : \circled1 The inspection rate in Korea was much lower than the other states taking part in Tokyo MOU, \circled2 For flag state, the ships belong to flag of convenience(FOC) had much more deficiencies than non-convenience flag ships, \circled3 For ship type, 39 number of general dry cargo ship were detained at Pusan with serious deficiencies, \circled4 For deficiency item, the items such as life saving appliances, safety in general, navigation, load lines and fire-fighting appliances were occupied over 71.7% of total number of deficiencies, \circled5 In Asia-Pacific region, Korea was one of flags with detention percentages exceeding 3-year(1996~1998) rolling average detention percentage. Average detention rate of Korean vessels was 6.73% which was over 0.24% of average detention rate(6.49%) in Asia-Pacific region. These results may reflect to improve the performance of PSC inspection for foreign vessels and are useful for preparing PSC inspection for ocean-going ships registered in Korea.

Traffic density has increased recently in Korean waters due to an expansion of the sea trade and the development of coastal fisheries. The enlargement of the coastal industrial belts and the development of coastal inslands further increases marine traffic. The rapid increase of marine traffic has often resulted in marine casualties with the attendant loss of life, damage to property, and marine pollution. Especially, tanker casualties may destroyed the food web and an untold amount of ocean resources. Un regard to the potential of tanker spills in Korean waters, systematic research in this field is lacking. In this paper, the data relating to a total of 261 tanker casualties in Korean waters has been compiled and statistically anlaysed. The result of this study describes the general trend of marine casualties in Korean waters, and describes the casualtiy database, from which their causes and consequences are derived and this results in the determination of the causal relationships connected to tanker casualties, and quantifies the effective level of causal factorsin Korean waters.