• Journal of Advanced Marine Engineering and Technology
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• v.28 no.2
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• pp.192-199
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• 2004

Navigation simulators have been used in many marine schools and manne training centers since the early 1960's. But these simulators were very expens~ve and were almost limited only in one engine system. In this paper, a catamaran with twin engine system. controlled by two remote control levers and its economic simulator based on a personal computer shall be introduced. One of the main features of catamaran is to control variously its progressing direction. In the static state, a catamaran can move into all the directions and in the dynamic state, ship can change immediately the heading and speed. Although a good navigator can skillfully operate one engine system, it is difficult to control smoothly the catamaran of twin engine system without any threat for the safety of passengers. Thus. in order to bring up the expert navigators. the development of a simulator which makes the training effective is necessary, Therefore, in this paper, a Fuzzy Inference Technique based Maneuvering Simulator for catamaran with twin engine system was developed. In general. in order to develop a catamaran simulator for effective training, first of all. its mathematical model must be acquired. According to the acquired system modeling. the dynamics of simulator is determined, But the proposed technique can omit a complex and tedious mathematical modeling procedures by using the fuzzy inference, which dependent upon only experiences of an expert and can design an efficient training program for unskillful navigators. This developed simulator was consisted of two fuzzy inference routines and two remote control levers, and was focused on effective training of navigators for the safe maneuvering to avoid a collision in a harbor.

• Journal of the Korean Institute of Navigation
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• v.13 no.2
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• pp.23-36
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• 1989

Marine casualities in the high sea are mainly classified into the breakage of hull and capsize , of which the latter occurs frequently to a small craft and container vessels by extreme rolling. The aim of this study is to develop shiphandling techniques for the prevention of ship's large rolling by way of evaluating dangerous degree of rolling in heavy weather. In this study, rolling motion is analized by using statistical method as follow : (1) 8 sample ships is presented for calculation. (2) Analized sea state are Beaufort scale 7 and 10 (wind velocity 30kts and 50kts respectively) and significant wave height is put as 5.2m and 11.2m. (3) The formula recommended by International Towing Tank Conference (ITTC) is used to calculated the wave spectrum. The results of this study are as follow : The results of this study are as follow : (1) Most of the vessels with beam of 20 meters or less was found to be capized in the waves abeam under the sea condition of Bearfort scale7(30kts). (2) For the vessels range 20m to 30m was found safe under the sea conditions of Bearfort scale 7(30kts) and imminent danger under the sea condition of Beaufort scale 11(50kts). (3) It is proved that any vessel could be capsized by heavy rolling regardless of vessel's size whenever the motion is synchronized with waves abeam. This study concludes that the navigator, especially at night , must anticipate the exact wave direction, referring to the wether report and coastaline, not to lay the vessel in the serial wave abeam.

• KIISE Transactions on Computing Practices
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• v.22 no.9
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• pp.419-425
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• 2016

In navigator systems, keeping map data up-to-date is an important task. Manual update involves a substantial cost and it is difficult to achieve immediate reflection of changes with manual updates. In this paper, we present a method for trajectory-center extraction, which is essential for automatic road map generation with GPS data. Though clustered trajectories are necessary to extract the center road, real trajectories are not clustered. To address this problem, this paper proposes a new method using the maximum overlapping interval and trajectory clustering. Finally, we apply the Virtual Running method to extract the center road from the clustered trajectories. We conducted experiments on real massive taxi GPS data sets collected throughout Gang-Nam-Gu, Sung-Nam city and all parts of Seoul city. Experimental results showed that our method is stable and efficient for extracting the center trajectory of real roads.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.4
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• pp.289-295
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• 2005

This study is intended to provide navigator with specific information necessary to assist in the avoidance of collision and in operation of ships to evaluate the manoeuvrability of own ship. The actual manoeuvering characteristics of ship can be adequately judged from the results of typical ship trials manoeuvres. Author carried out sea trials based full scale for turning test, zig-zag test, spiral tests and crash-stop test at actual sea going condition. The turning circle manoeuvres were performed on starboard and port sides with $35^{\circ}$ rudder angle at the service speed, and Zig-zag procedures were performed on both sides with $10^{\circ}$ and $20^{\circ}$ rudder angle respectively. Spiral tests were carried out on the both sides and crash stop test was also carried out. The results from tests could be compared directly with the standards of manoeuverability of IMO and consequently the manoeuvring qualities of the ship is fully satisfied with its.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.4
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• pp.260-271
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• 1993

Due to depletion of fish resources as time goes on, the trawl fishing industries which have caught the demersal fish is confronting with financial difficulties. For the purpose of breaking these difficulties, trawlers are expanding the fishing targets to the midwater from bottom stock. The trawlers become to be able to detect the fish schools not only vertical but also horizontal direction by equipping the sonar system on board. Even though the operator locates the fish school by sonar, it is not easy to make a desirable catch of the fish school which is detected, for the reason of the maneuverring characteristics of trawler. For the purpose of enhancing the efficiency of a fish catch, the auther performed a series of on board experiments to investigate the maneuverablilites of midwater trawaler. The obtained results are summerized as follows: 1. The higher the RPM of main engine, the smaller the magnitude of turning circle. And it is smaller in the right than in the left turning 2. Towing speed varies irregularly under turning novenment. When the RPM of main engine being 560, 680 the angular velocities are 11.3deg/min, 22.5deg/min respectively. 3. The difference of new course distance between calculated by maneuverring indices and measured by experimental ship is high when altering course being large and towing speed low. 4. The faster the towing speed is, the shorter the new course distance becomes. When towing speed is same in right and left turning movement, the now course distance is shorter in case of right turning movement than in left. 5. It is considered to be convenient for a navigator to utilize the curves for altering course in order to steer the ship rapidly and accurately.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.3
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• pp.191-198
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• 2007

Marine accidents are increasing as time goes on, in spite of lots of efforts are given. Marine accidents can be classified 3 categories those are ship's condition, navigator's condition and weather condition. In this paper, statistical analysis were carried using marine accidents data from 1997 to 2006. In order to analyze accident rate by time zone, ship's speed and finding distant, SPSS variance analysis was carried out. Results are followed. There was significant difference between time zone 20${\sim}$04 hours and other time zones. The accident rate in daytime was bigger than that at night. In case of the speed at collision, the speed of 5${\sim}$10 knot has significant difference to other speed cases. In finding distant cases, the case of less than 1 mile has significant difference to other distant cases.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.2
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• pp.137-142
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• 2011

Navigational charts in Korea have been increasingly published in line with the development of harbour for 60 years without a detailed planning. Recently, charts cause inconvenience to use and make navigator confused because they have not been adjoined to adjacent chart effectively and have been to overlap with other charts of the same scale. In this paper, we propose new chart system through adjusting area of the chart and rearranging its scale. This newly proposed scheme was first designed by researchers who have on-board career, then has been verified and revised by questionnaire and pilots' opinion. As a result, total number of Korean chart could be changed from 309 to 334.

• Journal of the Ergonomics Society of Korea
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• v.30 no.1
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• pp.251-257
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• 2011

When designing a ship, ergonomic considerations are crucial when minimizing a navigator's fatigue due to the burden of work, and to appropriately operate the navigational equipment for each given situation by helping the operator to understand the surroundings as well as the physical functions of the ship. However, insufficient consideration of ergonomic elements in the actual design of ship Bridges is lowering the performance of safe navigation and allows for the possibility of operation or readout errors. Consequently, these errors lead to an increase in maritime accidents. Therefore, this study conducted a usability evaluation on the importance of and the usage frequency of navigational equipment, their influence on actual navigation, and the possibility of error upon operation or readout between training ship officers, to derive an optimized layout that includes the consideration of ergonomic factors for on-Bridge navigational equipment, which are currently arranged differently according to their type or size. The optimized layout of on-Bridge navigational equipment was carried out based on the evaluation results, using the Lingo program. Through the process of optimization, revised layouts of on-Bridge navigational equipments(control and display device) were suggested, considering emergency situations(ship collision, stranding, fire and explosion, sinking, etc.) during navigation.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.26 no.2
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• pp.201-210
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• 1996

There is increasing attention about radiology teaching files on the Internet in the field of diagnostic radiology. The purpose of this study was to aid in the creation of new radiology teaching file by analysing the present radiology teaching file sites on the Internet with many aspects and evaluating images on those sites, using Macintosh IIci computer, 28.8kbps TelePort Fax/Modem, Netscape Navigator 2.0 software The results were as follow : 1. Analysis of radiology teaching file sites (l) Country distribution was the highest in USA(57.5％). (2) Average number of cases was 186 cases and radiology teaching file sites with search engine were 9 sites (22.5％). (3) At the method of case arrangement, anatomic area type and diagnosis type were found at the 10 sites(25％) each, question & answer type was found at the 9 sites(22.5％). (4) Radiology teaching file sites with oro-maxillofacial disorder were 9 sites(22.5％). (5) At the image format, GIF format was found at the 14 sites(35％). and ]pEG format found at the 14 sites(35％). (6) Created year was the highest in 1995(43.7％). (7) Continuing case upload was found at the 35 sites(87.5％). 2. Evaluation of images on the radiology teaching files (l) Average file size of GIF format (71 Kbyte) was greater than that of JPEG format(24 Kbyte). (p<0.001) (2) Image quality of GIF format was better than that of JPEG format. (p<0.001).

• Journal of IKEEE
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• v.16 no.2
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• pp.69-75
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• 2012

In this paper, microstrip array antenna is proposed for the wireless communication of DSRC(dedicated short range communication) scheme at 5.8GHz, which works as a part of the Navigation terminal. The microstrip patches minimized from a rectangular microstrip antenna with a half wavelength are arrayed to be mounted on the narrow and long area in the top side of the navigation terminal. Besides, the array antenna can limit its own beamwidth to the driving lane and has better directivity. It is simulated to verify the validity of the proposed application. The prototype fabricated has a volume of $18{\times}40{\times}0.8mm^3$. From the measurement, it has circular polarization performance of 4dB axial ratio over 40MHz frequency band. In addition, antenna gain of 6.2dBi and 3dB beamwidth of $70^{\circ}$ at cross section of driving lane have been achieved.