Won-Jae Yang

Development of Collision Scenario-Based Evaluation System for the Cognitive Performance of Marine Officers

Reduced crew performance is frequently cited as a major causal factor in maritime accident causation. Although considerable research has been conducted on the hours of work undertaken by seafarers through interviews and the analysis of records, experimental studies to observe the effects of factors such as high workload, shift patterns, stress, sleep deprivation and disturbance on the cognitive performance of mariners have been limited. Other safety-critical transport industries, such as aviation and rail, have developed fatigue management tools to help manage the work patterns of their operators. Such a tool for mariners would assist shipboard crew, marine pilots and shore management in planning and improving work schedules. The overall aim of this paper is to determine a fatigue factor, which can be applied to human performance data, as part of a software program that calculates total cognitive performance. This program enables us to establish the levels of cognitive performance of a group of marine pilots to test a decision-making task based on radar information. This paper addresses one of the factors that may contribute to the determination of various fatigue factors: the effect of different work patterns on the cognitive performance of a marine pilot.

Estimating Cumulative Distribution Functions with Maximum Likelihood to Sample Data Sets of a Sea Floater Model

This paper describes evaluation procedures and experimental results for the estimation of Cumulative Distribution Functions (CDF) giving best-fit to the sample data in the Probability based risk Evaluation Techniques (PET) which is to assess the risks of a small-sized sea floater. The CDF in the PET is to provide the reference values of risk acceptance criteria which are to evaluate the risk level of the floater and, it can be estimated from sample data sets of motion response functions such as Roll, Pitch and Heave in the floater model. Using Maximum Likelihood Estimates and with the eight kinds of regulated distribution functions, the evaluation tests for the CDF having maximum likelihood to the sample data are carried out in this work. Throughout goodness-of-fit tests to the distribution functions, it is shown that the Beta distribution is best-fit to the Roll and Pitch sample data with smallest averaged probability errors of 0.024 and 0.022, respectively and, Gamma distribution is best-fit to the Heave sample data with smallest of 0.027. The proposed method in this paper can be expected to adopt in various application areas estimating best-fit distributions to the sample data.

Structure Analysis of Ship′s Collision Causes using Fuzzy Structural Modeling

The prevention of marine accidents has been a important topic in marine society for long time, and various safety policies and countermeasures have been developed and applied to prevent those accidents. In spite of these efforts, however, significant marine accidents have taken place intermittently. Ship is being operated under a highly dynamic environments, and many factors are related with ship`s collision, whose factors are interacting. So, the analysis on ship`s collision causes are very important to prepare countermeasures which will ensure the safe navigation. This study analysed the ship`s collision data over the past 10 years(1991-2000), which is compiled by Korea Marine Accidents Inquiry Agency. The analysis confirmed that‘ship`s collision’is occurred most frequently and the cause is closely related with human factor. The main purpose of this study is to analyse human factor. For this, the structure of human factor is analysed by the questionnaire methodology. Marine experts were surveyed based on major elements that were extracted from the human factor affecting to ship`s collision. FSM has been widely adopted in modeling a dynamic system which is composed of human factors. Then, the structure analysis on the causes of ship`s collision using FSM are performed. This structure model could be used in understanding and verifying the procedure of real ship`s collision. Furthermore it could be used as the model to prevent ship`s collision and reduce marine accidents.

Research on Robustness of 2D DWT-Based Watermarking in Intermediate Viewpoint by 3D Warping

This paper investigates the robustness of watermarking techniques for stereo or multi-view images generated from texture and depth images. A three-dimensional (3D) warping technique is applied to texture and depth images to generate stereo or multiview images for a 3D display. By using the 3D warping technique, in this paper, we developed watermarking techniques and evaluated the robustness of these techniques that can extract watermarks from texture images even when the viewpoints are moved. A depth image is used to generate a stereo image with the largest viewpoint difference to the left and right. The overlapping region in the stereo image that does not disappear after warping is then obtained, and DWT is applied to this region to embed a watermark in the LL sub-band. The proposed watermarking techniques were found to yield bit error rates of about 3%–16% when they were applied to stereo images generated from texture and depth images. Furthermore, the results showed that the copyright could be seen when the extracted watermark was visually confirmed.

Evaluation of the Navigational Safety in Coastal Waterway using Fuzzy measures and Choquet Integral

The prevention of marine accidents has been a major topic in marine society and various policies and countermeasures have been developed, applied to the industries. The coastal VTS and navigational aids are considered as one of the effective methods to promote marine safety but they need relatively huge amount of budgets to build Thus prior to establishing these coastal VTS and navigational aids, it should be evaluated the navigational safety level in the coastal waterways from the Environmental Stress. So far as human beings are concerned, there are many types of fuzziness in the evaluation of navigational safety level. In order to reflect these fuzziness on this evaluation, this paper introduces the fuzzy integral suggested by Choquet to represent the fuzziness in the evaluation process. This paper aims to develop the method for this evaluation from the viewpoint of mariner`s operational stress using the fuzzy measure and Choquet integral. In this paper, Korean coastal area is divided into 8 sectors and evaluated the priority for the needs of coastal VTS and navigational aids.

Classification of Human Errors in Ship′s Collision using GEMS Model

Maritime safety and marine environmental protection are the most important topic in marine society. But, so many marine accidents have been occurred with the development of marine transportation industry. On the other side, ship is being operated under a highly dynamic environment and many factors are related with ship`s collision Nowadays, the increasing tendency to the human errors of ship`s collision is remarkable, and the investigation of the human errors has been heavily concentrated. This study analysed on the human errors of ship`s collision related to the negligence of lookout and classified basic error type using GEMS(Generic Error Modeling System) dynamic model.

One-way Through Port from the Viewpoint of Reduction of Ship′s Maneuvering Stress

.Ports are usually designed as a dead en port. With an increasing tendency of ship size, the problems such as maneuvering difficulty, turning basin, tugboat fee, etc. are getting to be pointed out. For solving such problem, the conversion of the idea fro dead end port to one-way through port is encourage. To examine the advantage of one-way through port, a quantitative and systematic analyzing procedure is needed. For this, this paper evaluated the preference on the three way of departture using the fuzzy measure and integral model.