• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.4
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• pp.389-396
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• 2012

As the demand on the precise positioning for the moving objects has been increased in the various industry field, many studies have been conducted to analyze real time kinematic technique and its practical usage. The main purpose of this study is to analyze the possibility of Network-RTK(VRS) in real-time kinematic positioning. So, the accuracy analysis has been conducted by comparing the Network-RTK(VRS) position with respect to the RTK position. As a result, Network-RTK(VRS) based on kinematic positioning has centimeter level of RMS in the ideal environment compared to RTK positioning. However, when the integer ambiguities was lost, the accuracy of Network-RTK was meter level. At that time, the quality value has been changed dramatically and shows big correlation with accuracy. When the position and height quality values are within 0.1m, the RMS of the horizontal and vertical position appears better than 10cm and 20cm, respectively. However, if the quality value is over 0.1m, the RMS increases to larger than a meter. Therefore, it is recommended to check the quality value when conducting Network-RTK(VRS) kinematic positioning to get the centimeter level accuracy.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.692-698
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• 2020

This paper examines the effects of a multi-stage pilot split injection strategy on combustion and exhaust emission factors in a single-cylinder diesel engine. One analysis noted that in the single-injection condition, the maximum in-cylinder pressure and rate of heat release were highest. The pilot injection quantity was evenly divided, showing a tendency to decrease as the number of injections increased. In another injection condition, when the multi-stage pilot split injection strategy was applied, IMEP, engine torque, and combustion increased. The COV_IMEP was greatest with the lowest combustion efficiency. The combustion ability was poor. In a single injection condition, the O₂ concentration in the exhaust gas was the lowest and the CO₂ was the highest. When the multi-stage split injection strategy was applied, the low temperature combustion process proceeded, and the oxidation rate of CO₂ decreased while the emission level increased. In a single injection condition in which a locally rich mixture was formed, the HC emission level showed the highest results. A 55.6% reduction of NOx emission occurred under a three-stage pilot injection condition while conducting a multi-stage pilot split injection strategy.

• Proceedings of KOSOMES biannual meeting
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• 2003.05a
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• pp.59-67
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• 2003

The prevention of marine accidents has been a major 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 and those 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 propose risk control countermeasures of ship's collision. 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.

• Journal of Intelligence and Information Systems
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• v.24 no.3
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• pp.119-134
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• 2018

A knowledge map as the taxonomy used in a knowledge repository should be structured to support and supplement knowledge activities of users who sequentially inquire and select knowledge for problem solving. The conventional knowledge map with a hierarchical structure has the advantage of systematically sorting out types and status of the knowledge to be managed, however it is not only irrelevant to knowledge user's process of cognition and utilization, but also incapable of supporting user's activity of querying and extracting knowledge. This study suggests a methodology for constructing a networked knowledge map that can support and reinforce the referential navigation, searching and selecting related and chained knowledge in term of contents, between knowledge. Regarding a keyword as the semantic information between knowledge, this research's networked knowledge map can be constructed by aggregating each set of knowledge links in an automated manner. Since a keyword has the meaning of representing contents of a document, documents with common keywords have a similarity in content, and therefore the keyword-based document networks plays the role of a map expressing interactions between related knowledge. In order to examine the feasibility of the proposed methodology, 50 research papers were randomly selected, and an exemplified networked knowledge map between them with content relevance was implemented using common keywords.

• Journal of Astronomy and Space Sciences
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• v.25 no.1
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• pp.53-60
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• 2008

A RF environmental field test for the proposed Galileo Sensor Station site was done by Alcatel Alenia technical team contracted by European Space Agency (ESA) and the Space Geodesy division of Korea Astronomy and Space Science Institute at the Korean VLBI Hetwork (KVN) site in Tamla University Campus, Jeju from June 21, 2007 to June 24, 2007. Full band and in-band 24 hour observation for radio frequency interference, precise positioning, and multipath on three proposed antenna locations for Galileo signal were executed. The main purpose of this survey is to verify the results of previous test on 2006 by KASI. The preliminary analysis of the results and a full investigation also had been done by ESA under the permission of KASI until the end of July, 2007.

• Journal of Korean Port Research
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• v.11 no.1
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• pp.85-99
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• 1997

The improvements of berth productivity is closely related to berth/port systems and its relationship extends to the overall pattern of port development/logistics, transport and trade. Since ports in general and berths in specific function as a bridge transferring seaborne cargoes from seaside to landside and vice versa, berth productivity improvements should be considered in terms of the total system in which the cargoes are transported from origin to destination via berths/ports. In that respect, the objective of this study is to improve berth productivity which is a vital factor in the strategic planning in port development and operation and logistics. According to a literature survey on the subject, the contents of the studies have been limited to either a macro-perspective or a micro-perspective which is only a partial solution to the problem. Hence, this limitation requires an integrated approach to find and ultimate solution, which should be considered not separately, but as a whole. The contents and scope of this study cover the improvements of berth productivity in conjunction with strategic planning in port development. efficient operation and logistics from two different viewpoints, macro- and micro-perspective. After that, a combination of these two perspectives is applied to the integrated approach due to lacking a comprehensive perspective from either macro-approach or micro-approach. In reality, a port itself is a complex and dynamic organization. Therefore, a comprehensive insight needs an integrated approach for the long-term national economic development. In this approach, the utmost importance is how to find the bottlenecks and to solve the problems effectively from the beginning stage in port development. In conclusion, derived from the macro- and micro-perspective. the attempt to establish an integrated approach is the merit of this study, which is required as a comprehensive measure since none of the two can be a solution independently. In terms of reinforcing this study, it needs further empirical research due to the restriction of the theoretical method of this paper. Consequently, the reinforced research will be able to enhance the integrated approach on the basis of the conceptual perspective.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.4
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• pp.336-345
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• 2020

Vessel Traf ic Services (VTS) is a system for ship safety and accident prevention. The International Maritime Organization (IMO), the International Association of Marine Aids to Navigation and the Lighthouse Authorities (IALA) established regulations related to VTS from an early stage. On December 3, 2019, South Korea enacted a special act called the "Act on Vessel Traffic Services (VTS Act)," which will take ef ect on June 4, 2020. In this paper, the background of this act's enactment is examined and its provisions are critically reviewed. In particular, the study intensively examines the reasons the immunity provisions for the VTS operator were removed and the current direction of improvements to the VTS Act is presented in terms of its feasibility. Most countries that do not have an Act related to VTS and its operator, refer to that of Korea. Therefore, it is necessary to reinforce the structures and definition of the VTS Act, as well as the immunity provisions for the VTS operator. The latter were removed during the National Assembly's legislation process, but were included in the initial bill, and should be reflected in subsequent revisions of the VTS Act.

• Geophysics and Geophysical Exploration
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• v.2 no.2
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• pp.77-85
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• 1999

The 3-D seismic research vessel, Tamhae II, was built to raise up the probability of the hydrocarbon discovery in the Korean continental shelf and the first test survey was completed in the East Sea. During the survey, the 240 channel 2-D marine seismic data were acquired by the Korean flag vessel for the first time. Tamhae II has been equipped with source, receiver, recording equipment, and navigation equipment as well as an onboard processing system. The source is composed of four subarrays and each subarray has six airguns. Total airgun volume is 4578 $in^3$. The receiver consists of two sets of 3 km long 240 channel streamer. In the first survey, the successful acquisition of 2-D seismic data was accomplished. From the result of the data processing, we confirmed that the high quality seismic data were acquired. For the high quality data acquisition, technology of survey design and planning, operation of vessel and equipments and systematic quality control should be developed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.548-549
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• 2015

무인 잠수정은 자율 무인잠수정(이하 'AUV' 또는 '자율무인잠수정'을 혼용)과 원격조정잠수정(이하 'ROV'로 지칭)으로 분류를 할 수 있다. ROV는 테더 게이블로 인한 작업 범위의 한계와 운동성능 효율이 떨어지는 단점을 지니고 있어, 테더 케이블이 필요 없는 AUV에 대한 필요성이 증대되고 있다. 추측 항법 시스템인 관성 항법 시스템(inertial navigation system, 이하 'INS'로 지칭)은 외부 도움없이 관성측정 장치(inertial measurement unit, 이하 'IMU'로 지칭)를 활용하여 구성된 시스템을 말한다. IMU는 자이로 스코프(gyroscope), 가속도계(accelerometer), 지자기(magnetic)센서로 구성된 측정 장치로 3개의 센서를 사용하여 상호 보정을 통한 기동 체의 위치, 속도 및 자세 정보를 제공한다. 복합항법시스템은 추측항법시스템이 가지는 누적오차와 측위 항법시스템이 가지는 외부환경에 대한 단점을 상호 보완하는 방법으로 연구가 진행 중이다. 하지만 심해서 또는 해양의 특성에 따라 측위 시스템이 사용되지 못하기 때문에 추측 항법시스템의 다양한 관성 센서를 활용한 상로 보완과 신호처리 방법을 통한 연구 개발이 진행 중이다. 다양한 센서 정보를 통합하는 목적으로 칼만 필터와 같은 최적 필터기법이 보편적으로 사용되고 있다. 칼만 필터는 확률 선형 시스템에 대하여 공정잡음 및 측정 잡음이 가우시안 확률 분포를 따를 때 최적의 추정자가 된다. 또한 가우시안 조건을 만족하지 않는 경우에도 선형 추정자 중에 추정 오차의 분산이 가장 작은 추정자이다. 칼만 필터가 최상의 성능을 발휘 하려면 공정잡음과 측정 잡음의 실제 값을 정확히 알아내는 것이 중요하다. 잡음 수준에 대한 정보가 부정확 할 경우 칼만 필터는 발산 할 수 있기 때문에 시스템에서 잡음 수준의 공산은 칼만 필터의 최적 이득을 결정하는 중요한 요소로 추정치에 큰 영향을 준다. 따라서 칼만 필터를 추측항법시스템에 적용 시킬 경우 실제 모텔의 잡음 공분산을 정확히 추정할 수 있는 기법이 요구된다. 추측항법시스템은 다양한 센서를 활용하기 때문에 움직이는 기동 표적에 적용시 잡음공분상이 변하기 때문에 항법시스템이 저하 될 수 있다. 본 연구에서는 다양한 센서를 융합하여 해양 생체 로봇의 정밀 자세 제어가 가능한 시스템을 제안하고자 한다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.9 no.1
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• pp.51-56
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• 2003

The prevention of marine accidents has been a major 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 and those factors are interacting. So, the analysis on ship's collision rouses 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 if this study is to propose risk control countermeasures of ship's collision. 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 rouses 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 to reduce marine accidents.