• Title/Summary/Keyword: Ship information system

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A Study of Control for 3 Phase BLDC Motor using Control Methodology of DC Motor (직류전동기 제어기법을 적용한 3상 BLDC 모터 제어에 관한 연구)

  • Jin-Man Kim;Taek-Kun Nam
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.6
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    • pp.704-711
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    • 2023
  • This paper discusses the control method of BLDC(Brushless Direct Current) motor that has similar electrical characteristics with DC motor but has improved its lifespan and reliability. The BLDC motor can improve durability and speed stability by using rotor position information to eliminate commutators that require mechanical contact with DC motors. In this study, a controller for a DC motor was designed based on the fact that the current in the windings of a BLDC motor is a square-wave current like the current flowing in the armature of a DC motor. Next, the designed controller was applied to a 3-phase BLDC motor to confirm the effectiveness of the controller. In detail, a single-phase DC motor with electrical parameter values of a three-phase BLDC motor was modeled and a PI controller for motor speed control was designed by applying the root locus method to the derived system. The speed control simulation of the DC motor was performed to confirm the validity of the controller, and the same controller was applied to the speed control of the 3-phase BLDC motor implemented in MATLAB. From the simulation, similar results of the DC motor were obtained in the 3 phase BLDC motor and confirmed the usefulness of the proposed control scheme.

Analysis of the Effects of Behavioral Factors on the Seafarers' Career Path (해기직업 경로상의 행동요인 영향 분석)

  • Kim, Young-Mo;Jun, Sang-Yup;Hwang, Byeong-Ho;Kang, In-Chul;Jeong, Hae-Jong
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.15 no.4
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    • pp.369-374
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    • 2009
  • It is difficult to improve maritime safety in the aspect of human elements without seafarers' job satisfaction. Therefore, through the career development for seafarers from their entries into the job to their retirements, longer and more stable seafarers' life on board ship could be achieved together with maritime safety. This study aims at the establishment of seafarers' career path model and the verification of six hypotheses by using the questionnaire data of 2,830 respondents of students, slip officers and shore-based ex-seafarers. The results of analyses of behavior factors on the career path are as follows; first, it is important to improve educational environment and to provide seafarers with detailed information on seafarer's life; second, economic factors such as income-level and etc. do not play a role in promoting motivation of going to sea; third, the guidance to shore jobs at proper time increases seafarers' job satisfaction and induces longer stay at sea; last, it is necessary to simplify the licence system for seafarers, to allow seafarers to acquire higher class certificates, and to work at higher rank on board ships as early as possible.

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An Empirical Study on the Improvment of VTS in Korea (우리나라 선박교통제제도의 개선방안에 관한 실증연구 - 포항항을 중심으로 -)

  • 임을빈;문성혁
    • Journal of the Korean Institute of Navigation
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    • v.21 no.2
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    • pp.47-58
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    • 1997
  • The purpose of this study is to find out the impacts of VTS on the marine safety and users' opinion on the VTS which have been being operated in the port of Pohang for the last 3 years and is to suggest a guideline to the successful operation of VTS in the future. This study is based upon the questionnaire survey and the respondents include 236 masters/mates of merchant vessels who have visited the port of Pohang and 6 pilots who have been working in the port. From the questionnaire results, this study notes the following conclusions related to the VTS operations. (1) A few of the respondents (mainly foreigners) do not understand the entering procedure of the port and the fundamental concept of VTS. Accordingly, the more active VTS services have to be provided for the mariners. (2) It was found that themost dangerous factors in tehvicinity of the port were the floating materials, fishing nets, andillegal fishing activities inthe fairway. Therefore, the proper surveillance, stricter enforcement of Acts and the instructive education for the fishermen are required to avoid the risks. (3) A majority of the respondents agreed the VTS has contributed to the safety of vessel traffic, and they pointed out ' the assiatances in reduced visibililty conditions' is the most important task of VTS. The amount of 75.6% of the respondents answered that they have experienced the assistance from VTS more than 1 time since the system was established in the port of Pohang . Also 44.2% of the respondents considered they were able to avoid marine casualties such as collision, ramming or agrounding with the VTS assistances. (4) 49.2% of the respondents preferred the passive information services , while, 38.8% of them preferred the positive control advices in the case of encountering any potential risks. VTS iperators have to consider seriously when they provide the positive control advices of ship's course and speed. (5) A majority of the respondents confirmed that the prot and its approaches is suitable for the VTS coverge . To extend the service areas of the VTS and to improve radar detecting ability, the use of radar transponders are seen as the ideal method. (6) A minority of the respondents pointed out 'the improper orders or recommendatinos caused by the poor decision making' firstly, ' the language problem(sea-speaking in English)' secondly, as the deficiency of personal qualification. It seems, therefore, theat the personal efforts of the operators and systematic training programmes for them are necessary to solve the problems.

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Investigations of the Potential Fisheries Resources in the Southern Waters of Korea - Hydroacoustic Investigations of Abundance and Distributing of Fish - (한국 남해안의 잠재어업자원 조사연구 - 어업생물자원의 음향학적 조사 -)

  • Lee, Dae-Jae;Kim, Jin-Geon;Sin, Hyeong-Ho
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.34 no.3
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    • pp.259-273
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    • 1998
  • The hydroacoustic surveys to provide the essential information for the assessment, management and utilization of fishery resources in the southern waters of Korea were carried out during five research cruises between October 1996 and October 1997 by the training ship KAYA of Pukyong National University. These hydroacoustic investigations were designed to obtain more precise estimates of the geographic distribution, absolute abundance and biological characteristics of the fishery resources, and the vertically integrated densities of fish in terms of volume backscattering strength(SV) by survey region and depth bins, such as the entire water column and the 0~ 10 m from bottom fraction, were measured separately. Hydroacoustic data were collected by using a Simrad EK 500 Scientific echo sounder operating at two frequencies of 38kHz and 120kHz and the data stored in field were later processed on a HP PC using a Simrad EP 500 echo integration and target strength analysis system. The biological compositions of echo signal were identified and sampled using a demersal trawl during daylight hours. The mean target strength to scale the echo integration data for hydroacoustic surveys was derived from the relationship between the SV and the weight of trawl catch per unit volume of the water column sampled by demersal trawls. The results obtained can be summarized as follow : 1. The mean volume backscattering strength for the entire water column in the southern waters of Korea between 1996 and 1997 were -67.2 dB and -70.9 dB at two frequencies of 38 kHz and 120 kHz , respectively, and for the bottom layer of the 0-10 m from bottom friction were -68.8 dB, -70.2 dB, respectively. That is, the volume backscattering strength for the entire water column at low frequency was higher than that at high frequency. 2. The relationship between the mean backscattering strength (〈SV〉, dB) for the depth strata of trawl hauls and the weight (C, kg/m3) per cubic meter of the catch sampled by bottom trawling in the southern waters of Korea in January and July 1997 were expressed by the following equations: 38 kHz : 〈SV〉= -28.2 + 10 log(C), 120 kHz : 〈SV〉= -32.4 + 10 log(C). The mean weight -normalized target strengths derived from these equitions were -28.2 dB/ kg, -32.4 dB/ kg at 38 kHz and 120 kHz , respectively. That is, the mean weight -normalized target strength at 38 kHz was 4.2 dB higher than that at 120 kHz. 3. The distribution density of fish in terms of biomass per unit volume in the southern waters of Korea were estimated to be 125.9 $\times$ 10-6 kg/m3 and 141.3 $\times$ 10-6 kg/m3 at 38 kHz and 120 kHz , respectively.

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Development of unified communication for marine VoIP service (해상 VoIP 서비스를 위한 통합 커뮤니케이션 기술 개발)

  • Kang, Nam-seon;Yim, Geun-wan;Lee, Seong-haeng;Kim, Sang-yong
    • Journal of Advanced Marine Engineering and Technology
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    • v.39 no.7
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    • pp.744-753
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    • 2015
  • This paper presents the results of research on developing marine unified communications to provide VoIP service based on marine satellites. With the recent popularity of smart-phones and other mobile devices, the demand for Internet-based wired and wireless unified technology has been growing in marine environments, and increasing interest is being directed to VoIP products and service models with high price competitiveness and the ability to deliver a variety of services. In this regard, this research designed three instruments, developed their unit modules, and verified their performances. These three instruments included the following: (1) a marine VoIP module equipped with an analogue gateway that can be linked to the existing devices used in vessels, which is more than 80% smaller than that of a land system; (2) a text/voice/video engine for marine satellite communications that runs on technology that minimizes communication data usage, which is a core technology for a marine VoIP service; and (3) a unified communication service that can support multilateral cloud-based message conversations, telephone number-based call functions, and voice/video calling between a private space in a ship and shore.

The Situation Awareness Analysis of VTSOs in the Close Quarters Situation (선박 근접상황에 대한 VTSO의 상황 인식 분석에 관한 연구)

  • Lee, Jin-Suk;Song, Chae-Uk
    • Journal of Navigation and Port Research
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    • v.42 no.1
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    • pp.25-30
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    • 2018
  • This study was carried out to analyze the risk attitude based on situation awareness of the Vessel Traffic Service Operator (VTSO) on the risk of collision between vessels during the monitoring of vessel traffic through the use of the VTS system. In general, when two vessels are in the close quarters situation, we analyzed the degree of risk of collision from the subjective viewpoint of the VTSOs through an administered survey. Chiefly, we analyzed the risk attitudes of each VTSO in the close quarters situation, by comparing it with the calculated value by the CoRi, which is the ship collision risk model from the VTSO's viewpoint. As a result, it was confirmed that more than 40% of the total VTSO was noted as being in a weak risk aversion type of category. Through a review of the results of analyzing the risk attitude of VTSO according to gender, age, VTS career, VTS center position, accident experience, and boarded career, it was found that there was a significant difference in the VTS career, VTS center position and accident experience. In addition, a regression model that is able to further explain the risk attitude of VTSO was derived as a factor that confirmed the significant difference and applied to CoRi to predict the collision risk according to the individual VTSO to be used as a fundamental information gathering tool for providing more accurate and safe VTS service at sea.

Development of Design Space Exploration for Warship using the Concept of Negative Design (네거티브 설계 개념을 이용한 함정 설계영역탐색법 개발)

  • Park, Jin-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.9
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    • pp.412-419
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    • 2019
  • Negative space in the discipline of art defines the space around and between the subject of an image. The use of negative space is an element of artistic composition, since it is occasionally used to artistic effect as the "real" subject of an image. In painting, it is a technique that negatively touches the background of an object to be expressed, so that it gives a feeling of unique texture and silhouette by touching unnecessary parts while leaving necessary parts. As in art, negative space in a design can also be useful to identify an image of infeasible design ranges with a straightforward view. Similarity between two disciplines leads to the introduction of the negative space concept for design space exploration. A rough design space exploration using statistics and visual analytics may support more efficient decision-making, and can provide meaningful insights into the direction of early-phase system design. For this, the approach guarantees dynamic interactions between visualized information and human cognitive systems. Visual analytics is useful to summarize complex and large-scale data. It is useful for identifying feasible design spaces, as well as for avoiding infeasible spaces or highly risky spaces. This paper investigates the possible use of the negative space concept by using an application example.

The Simulation for the Organization of Fishing Vessel Control System in Fishing Ground (어장에 있어서의 어선관제시스템 구축을 위한 모의실험)

  • 배문기;신형일
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.36 no.3
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    • pp.175-185
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    • 2000
  • This paper described on a basic study to organize fishing vessel control system in order to control efficiently fishing vessel in Korean offshore. It was digitalized ARPA image on the fishing processing of a fleet of purse seiner in conducting fishing operation at Cheju offshore in Korea as a digital camera and then simulated by used VTMS. Futhermore, it was investigated on the application of FVTMS which can control efficiently fishing vessels in fishing ground. The results obtained were as follows ; (1) It was taken 16 minutes and 35 minutes to casting and hauling net in fishing processing respectively. The length of rope pulled by scout boat was 200m, tactical diameter in casting net was 340.8m, turning speed was 6kts as well. (2) The processing of casting and hauling net was moved to SW, NE as results of simulation when the current direction and speed set into NE, 2kts and SW, 2kts respectively. Such as these results suggest that can predict to control the fishing vessel previously with information of fishing ground, fishery and ship's maneuvering, etc. (3) The control range of VTMS radar used in simulation was about 16 miles. Although converting from a radar of the control vessel to another one, it was continuously acquired for the vector and the target data. The optimum control position could be determined by measuring and analyzing to distance and direction between the control vessel and the fleet of fishing vessel. (4) The FVTMS(fishing vessel traffic management services) model was suggested that fishing vessels received fishing conditions and safety navigation information can operate safely and efficiently.

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E-Commerce in the Historical Approach to Usage and Practice of International Trade ("무역상무(貿易商務)에의 역사적(歷史的) 어프로치와 무역취인(貿易取引)의 전자화(電子化)")

  • Tsubaki, Koji
    • THE INTERNATIONAL COMMERCE & LAW REVIEW
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    • v.19
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    • pp.224-242
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    • 2003
  • The author believes that the main task of study in international trade usage and practice is the management of transactional risks involved in international sale of goods. They are foreign exchange risks, transportation risks, credit risk, risk of miscommunication, etc. In most cases, these risks are more serious and enormous than those involved in domestic sales. Historically, the merchant adventurers organized the voyage abroad, secured trade finance, and went around the ocean with their own or consigned cargo until around the $mid-19^{th}$ century. They did business faceto-face at the trade fair or the open port where they maintained the local offices, so-called "Trading House"(商館). Thererfore, the transactional risks might have been one-sided either with the seller or the buyer. The bottomry seemed a typical arrangement for risk sharing among the interested parties to the adventure. In this way, such organizational arrangements coped with or bore the transactional risks. With the advent of ocean liner services and wireless communication across the national border in the $19^{th}$ century, the business of merchant adventurers developed toward the clear division of labor; sales by mercantile agents, and ocean transportation by the steam ship companies. The international banking helped the process to be accelerated. Then, bills of lading backed up by the statute made it possible to conduct documentary sales with a foreign partner in different country. Thus, FOB terms including ocean freight and CIF terms emerged gradually as standard trade terms in which transactional risks were allocated through negotiation between the seller and the buyer located in different countries. Both of them did not have to go abroad with their cargo. Instead, documentation in compliance with the terms of the contract(plus an L/C in some cases) must by 'strictly' fulfilled. In other words, the set of contractual documents must be tendered in advance of the arrival of the goods at port of discharge. Trust or reliance is placed on such contractual paper documents. However, the container transport services introduced as international intermodal transport since the late 1960s frequently caused the earlier arrival of the goods at the destination before the presentation of the set of paper documents, which may take 5 to 10% of the amount of transaction. In addition, the size of the container vessel required the speedy transport documentation before sailing from the port of loading. In these circumstances, computerized processing of transport related documents became essential for inexpensive transaction cost and uninterrupted distribution of the goods. Such computerization does not stop at the phase of transportation but extends to cover the whole process of international trade, transforming the documentary sales into less-paper trade and further into paperless trade, i.e., EDI or E-Commerce. Now we face the other side of the coin, which is data security and paperless transfer of legal rights and obligations. Unfortunately, these issues are not effectively covered by a set of contracts only. Obviously, EDI or E-Commerce is based on the common business process and harmonized system of various data codes as well as the standard message formats. This essential feature of E-Commerce needs effective coordination of different divisions of business and tight control over credit arrangements in addition to the standard contract of sales. In a few word, information does not alway invite "trust". Credit flows from people, or close organizational tie-ups. It is our common understanding that, without well-orchestrated organizational arrangements made by leading companies, E-Commerce does not work well for paperless trade. With such arrangements well in place, participating E-business members do not need to seriously care for credit risk. Finally, it is also clear that E-International Commerce must be linked up with a set of government EDIs such as NACCS, Port EDI, JETRAS, etc, in Japan. Therefore, there is still a long way before us to go for E-Commerce in practice, not on the top of information manager's desk.

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A Study on the Liability for Third Party's Damage on the Time Charter-parties (정기용선계약에서 제3자 화물손해 책임에 관한 연구)

  • Shin, Hak-Sung
    • International Commerce and Information Review
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    • v.15 no.2
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    • pp.285-313
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    • 2013
  • By the revision of the Commercial Code of Korea in 1991 and 2007, some provisions for the regulation of Time Charterparty have been introduced into our own maritime law system. But, those provisions are in their nature mainly the reproduction of the provisions prescribed in the standard forms of time charterparty which are widely used, such as BALTIME Charter and NYPE Form, and the subject matters of their regulation are restrictive, so that the applicability of the provisions is not desirable. The cargo is lost or damaged, the cargo owner should seek compensation form, or sue, the carrier as, traditionally, under the COGSA, the cargo carrier is responsible for loss of damage of cargo. However, it is difficult to determine who is the responsible carrier under charters. There is no test to determine the carrier, but the courts in every country generally consider the bill of lading. Although the master has general authority to sign bills of lading on behalf of the shipowner, he can also sign bills of lading for, and on behalf of, the charterer. In this case, the charter is considered the carrier. Furthermore, the charterer is authorized to contract with third parties on behalf of the shipowner and, as such, the responsible carrier is the shipowner. Therefore, when determining the carrier we should examine carefully the all factors and the circumstances surrounding the case. Also, negligence of a captain of a time-chartered ship causing damages to a third party. It will analyze the legal character of a time-charter contract, review judicial precedents on time-charter. The Inter-Club Agreement was drawn up and is intended to be a somewhat easier way of allocating liability for cargo claims between owners and charterers and, although there is still scope for disputes to arise, the Inter-Club Agreement does in fact to some extent make the allocation of liabilities for cargo claims easier. Finally, it will also make legislative suggestions to resolve complex issues involving maritime transportation contracts under the current Commercial Code.

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