• Journal of Positioning, Navigation, and Timing
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• v.4 no.4
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• pp.161-171
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• 2015

Alternative binary offset carrier (AltBOC) signals can be approximated by four synchronized direct sequence spread spectrum (DSSS) signals, each pair of which is a quadrature phase shift keyed (QPSK) signal at a different frequency. Therefore, depending on the strength of an incoming AltBOC signal, an acquisition technique can reduce the mean acquisition time (MAT) by searching the four DSSS signals asynchronously; the search for each of the four DSSS signals can start at one of the evenly separated hypotheses on the two-dimensional hypothesis space. And detection sensitivity can be improved by multiple levels when different numbers of search results for the same hypothesis are combined. In this paper, we propose a fast AltBOC acquisition technique that has an asynchronous search strategy and efficiently utilizes the output of the four search results to increase the sensitivity level when sensitivity improvement is needed. We provide a complete theoretical analysis and demonstrate with numerous Monte Carlo simulations that the MAT of the proposed technique is much smaller than conventional AltBOC acquisition techniques.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.636-642
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• 2015

This paper presents an application of heuristic harmony search (HS) optimization algorithm for the identification of linear continuous time-delay system from step response. Identification model is first-order plus dead time (FOPDT), which describes a linear monotonic process quite well in most chemical processes and HAVC process and is often sufficient for PID controller tuning. This recently developed HS algorithm is conceptualized using the musical process of searching for a perfect state of harmony. It uses a stochastic random search instead of a gradient search so that derivative information is unnecessary. The effectiveness of the identification method has been demonstrated through a number of simulation examples.

• Journal of the Korean Institute of Navigation
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• v.11 no.1
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• pp.93-106
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• 1987

Nowadays natural resources on shore have been almost exhausted all over the world and mankind is beginning searching for unexploited resources on the bed of deep-sea floor. In exploring mineral resources and etc. in the ground of sea-bed, a sumbersible craft is one of the most important tools. These days, the stage of the technique of building and operating an exploring submersible craft is almost alike that of building and operating an airplane in the first years of the nineteen-twenties. At the present time, the problems arising in building and operating a submersible craft can be divided into four parts as follows; 1. How to build a hull that can bear high pressure under deep sea level. 2. How to decide the necessary facilities to be put on it. 3. How to decide the scope of stabilities and maneuvering characteristics of it. 4. On what sea conditions, the devices of launching and recovering it should be designed on the mother-ship. In this paper treating one of the third problems the author made a mathematic formula that can be useful in deciding the scope of dynamic course stability on the vertical plane and actually calculated the onset speed of pitch instability of an exploring craft. With the above mentioned calculations the author demonstrated that the value of $Z_g$ and the speed of a submerged craft are the most important factors in decideing the scope of dynamic stability on the vertical plane.

• Journal of Advanced Navigation Technology
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• v.13 no.5
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• pp.705-713
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• 2009

This paper proposes CORBA-based visual servoing system of humanoid robot. To effectively control the humanoid robot which is connected to network, it needs to define necessary services for visual servoing as distribution object, and realize them in the middleware. For realizing it following services should be addressed. Naming service for searching a necessary service with unique name assigned to each object, image service for supplying image obtained from stereo camera. In the experiment, we show the result of balloon tracking and bursting that the robot tracks balloons as target objects in the real time, and if a balloon stop for a certain time, then the robot bursts the balloon.

• Journal of the Korean Society for information Management
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• v.19 no.4
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• pp.163-183
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• 2002

The purposes of this study were to examine the features of web fashion magazines and to suggest an effective website model for them. Seven web fashion magazines were analyzed. The evaluating criteria included: contents, design, navigation, and services. In addition, online-questionnaires were sent to 40 end users to obtain the information regarding user behaviors on the elected web fashion magazines. The results show that a suggested model should include various aspects: 1) providing currents information. 2) consistency in design, 3) easy in navigation, and 4) searching function etc.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.673-678
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• 2012

Traditional culture's researcher has attempting to public use as a various method. Example is design of digital archive and digital contents. However, in spite of this effort, traditional culture's researcher has difficulty to public use. Because traditional culture is hard to understand, and less interest than the other area. Especially, traditional culture has not environment that user can searching and using the culture's information due to difficult to search the data and layers. We propose a design to make an ontology using information profile for digital contents of traditional culture. Also, we use topic-map for the factors of ontology's relation, and specify their relation using topic vector.

• Journal of the Ergonomics Society of Korea
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• v.23 no.4
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• pp.9-21
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• 2004

As menu structure of household appliance is complicated, user's cognitive workload frequently occurs errors. In existing studies, errors didn't present that interpretation for cognitive factors and alternatives, but are only considered as statistical frequency. Therefore, error classification and analysis in tasks is inevitable in usability evaluation. This study classified human error throughout information process model and navigation behavior. Human error is defined as incorrect decision and behavior reducing performance. And navigation is defined as unrelated behavior with target item searching. We searched and analyzed human errors and its causes as a case study, using mobile phone which could control appliances in near future. In this study, semantic problems in menu structure were elicited by SAT. Scenarios were constructed by those. Error analysis tests were performed twice to search and analyze errors. In 1st prototype test, we searched errors occurred in process of each scenario. Menu structure was revised to be based on results of error analysis. Henceforth, 2nd Prototype test was performed to compare with 1st. Error analysis method could detect not only mistakes, problems occurred by semantic structure, but also slips by physical structure. These results can be applied to analyze cognitive causes of human errors and to solve their problems in menu structure of electronic products.

• 한국HCI학회:학술대회논문집
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• 2006.02b
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• pp.169-174
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• 2006

최근의 휴대전화는 음성 통화뿐만 아니라 메시지 및 이메일 송/수신, 사진/동영상 촬영 등 다양한 종류의 작업을 수행할 수 있으며, 그 기능이 점차 확장되고 있는 추세이다. 그러나 화면 공간의 제약으로 인한 메뉴 항목명의 축약, 메뉴 항목수의 증가, 메뉴 구조의 복잡화 등의 원인 때문에 많은 사용자들이 메뉴검색에 불편함을 겪고 있다. 이러한 문제점을 해결하기 위해, 본 연구에서는 기존의 메뉴 네비게이션을 통한 검색 방식, 하위 메뉴항목 제시 방식 이외에, 키워드 검색방식 및 유사 키워드 검색 방식을 개발하고 4가지 메뉴 검색방식의 사용성 평가실험을 수행하였다. 사용성 평가 실험 결과, 수행도 측면에서는 메뉴 검색 방식간의 차이가 유의하지 않았지만, 사용자 만족도 측면에서는 통계적으로 유의한 차이가 존재하였다. 4가지 메뉴 검색 방식 중 유사 키워드 방식은 사용자 만족도 측면에서 가장 선호되는 방식으로써, 추후 실제 휴대전화에 적용될 경우 사용자 만족도를 제고할 수 있을 것으로 기대된다.

• Journal of the Korean Institute of Navigation
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• v.24 no.1
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• pp.73-84
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• 2000

Shipping industry continues to face dramatic changes in its environment ranging from development in containerization, computerization and telecommunications to the emergence of global marketplace. Perhaps the most significant trend - representing both a threat and opportunity - is the increasingly competitive nature of shipping service market. In order for the shipping companies to cope with those improvements and challenges, they should analyze and clarify customer's DM(decision making) process for the purchase of container shipping service. The major research findings from the study were found as follows; 1) The degree of shipper's involvement in purchasing shipping services was found to be a discriminating variable affecting the information sources consisting of personal and non-personal information sources. 2) The positive relationship was found between the experiences on shipping services and non-personal information sources. 3) It was observed that as people had more experience searching for information, the more in depth their searches became. 4) There existed a positive relationship between knowledges on shipping services and information search. 5) According to the SEM analysis, the shipper's information search on shipping services was also found to have a great influence on the shipper's purchasing behavior. The shipper's search was resulted in positive customer satisfaction.

• The Journal of Korean Association of Computer Education
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• v.12 no.5
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• pp.95-103
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• 2009

In this paper, we propose a Web navigation guidance system which automatically provides a user with semantically related links based on an ontology. The system associates each web page to a concept in the ontology and creates new links between web pages by considering relationships of the concepts defined in the ontology. It focuses on enhancing web navigation by offering semantic links based on an ontology. We experimented the proposed system with 5th grade students who were performing tasks by searching Web pages and found that the degree of disorientation, the ratio of revisits for Web pages, and time spent for completing tasks for students in the experimental group were smaller than those for students in the control group. In addition, the task performance ratio for students in the experimental group were higher than that for students in the control group. It is expected that the proposed system can help design a navigable web site that is important in Web-based education.