• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.271-278
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• 2021

In this paper, a tropospheric delay error was calculated by using meteorological data collect from weather station and Saastamoinen model, and an empirical variogram of the tropospheric delay in the Korean peninsula was estimated. In order to estimate the empirical variogram of the tropospheric delay according to weather condition, sunny day, rainy day, and typhoon day were selected as analysis days. Analysis results show that a maximum correlation range of the empirical variogram on sunny day was about 560 km because there is overall trend of the tropospheric delay. On the other hand, the maximum correlation range of the empirical variogram on rainy was about 150 km because the regional variation was large. Although there is regional variation when the typhoon exists, there is a trend of the tropospheric delay due to a movement of the typhoon. Therefore, the maximum correlation range of the empirical variogram on typhoon day was about 280 km which is between sunny and rainy day.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2013년도 추계학술대회
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• pp.427-428
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• 2013

등대와 등표는 연안항로표지시설중 대표적인 건조물이다. 인천지역은 근대 초기에 등대 등표가 가장 활발하게 건설된 지역이다. 본 연구는 인천지방해양항만청이 관리하는 등대와 등표를 대상으로 한다. 이들을 현장조사하여 얻은 자료들을 근거로 현황을 정리하고 문화적 역사적 가치가 있는 대상들에 대한 장기적 보존을 위한 보존관리방안을 본 연구를 통해 제시하고자 한다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2006년도 International Symposium on GPS/GNSS Vol.1
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• pp.417-421
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• 2006

ICAO defines performance requirements of navigation system such as accuracy, integrity, continuity and availability. The integrity is most significant performance requirement in aviation where safety of life is crucial. Many researches on this topic anticipate that GPS with SBAS or Galileo can meet APV requirements and GPS with GBAS or Galileo with GBAS will meet CAT II and III requirements. These performance expectations are based on global analysis. In this paper regional integrity analysis in Korea using various combinations of modernized GPS, Galileo and SBAS is given. The simulation results show that CAT I requirement can be met using modernized GPS and Galileo alone, however, CAT II and III are not met even augmenting SBAS because of VPL. A more efficient augmentation such as GBAS which can reduce VPL dramatically is required to meet CAT II and III in Korean region.

• Journal of Positioning, Navigation, and Timing
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• 제13권2호
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• pp.159-165
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• 2024

The Global Navigation Satellite System (GNSS) has been used as a tool to accurately extract the Total Electron Content (TEC) in the ionosphere. The multi-GNSS (GPS, GLONASS, BeiDou, Galileo, and QZSS) constellations bring new opportunities for ionospheric research. In this study, we develop a regional ionospheric TEC model using GPS, Galileo, and QZSS measurements. To develop an ionospheric model covering the Asia-Oceania region, we select 13 International GNSS Service (IGS) stations. The ionospheric model applies the spherical harmonic expansion method and has a spatial resolution of 2.5°×2.5° and a temporal resolution of one hour. GPS TEC, Galileo TEC, and QZSS TEC are investigated from January 1 to January 31, 2024. Different TEC values are in good agreement with each other. In addition, we compare the QZSS(J07) TEC and the Center for Orbit Determination in Europe (CODE) Global Ionosphere Map (GIM) TEC. The results show that the QZSS TEC estimated in the study coincides closely with the CODE GIM TEC.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2013년도 추계학술대회
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• pp.204-205
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• 2013

인간의 모든 행위가 그러하듯 VTS 관제 역시 관제사의 마음에서 시작된다. 관제의 시작이 되는 심리적 동기(마음)는 집단무의식, 공포, 책임감, 인간애로 대별되며 이들은 관제사를 각성시키고 관제 전반을 지배한다. 그 중 상위요소(책임감, 인간애)는 기반요소에 비해 보다 긍정적으로 관제 행위에 적용되므로 VTS 운영 목적인 해상교통안전 달성을 위한 효과적인 수단이 될 수 있다. 관제사가 이러한 덕성을 함양할 수 있도록 교육 과정의 개선이 필요하다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 International Workshop for AIS / ECDIS / VTS Interface
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• pp.173-181
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• 2000

Lockheed Martin has integrated and installed numerous AIS systems around the world as part of several VTS installation contracts and technology demonstrations for customers. Each of these systems incorporates specific customer requirements addressing differing objectives. This paper describes the capabilities and features of Lockheed Martin's current implementation of the Universal AIS system, and the experiences Lockheed Martin has had with earlier AIS and ADS (automated dependent surveillance) system installations. Specific examples are provided for an amphibious landing exercise with the US Army; installations at a Middle-East Oil port; technology demonstrations in New York Harbor, USA; river systems in New Orleans, Louisiana, USA; and coastal applications in the Gulf of Suez. The paper closes a brief overview of the most recent activity, the Turkish Straits VTMIS project that requires Universal AIS installations. The evolution of the technology and lessons learned will be discussed in the context of these examples. The perspective will be on Lockheed Martin's experience working with different customers to integrate AIS technology into a larger VTS or Port Information System. It will also discuss, from the practical side, how AIS information is used by a variety of maritime organizations with differing needs and information objectives.

• Journal of Positioning, Navigation, and Timing
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• 제13권1호
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• pp.63-73
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• 2024

NeQuick G is the ionosphere model utilized by Galileo single-frequency users to estimate the ionospheric delay on each user-satellite link. The model is characterized by the effective ionization level (Az) index, determined by a modified dip latitude (MODIP) and broadcast coefficients derived from daily global space weather observations. However, globally fitted Az coefficients may not accurately represent ionosphere within local area. This study introduces a method for regional ionospheric modeling that searches for locally optimized Az coefficients. This approach involves fitting TEC output from NeQuick G to TEC data collected from GNSS stations around Korea under various ionospheric conditions including different seasons and both low and high solar activity phases. The optimized Az coefficients enable calculation of the Az index at any position within a region of interest, accounting for the spatial variability of the Az index in a polynomial function of MODIP. The results reveal reduced TEC estimation errors, particularly during high solar activity, with a maximum reduction in the RMS error by 85.95%. This indicates that the proposed method for NeQuick G can effectively model various ionospheric conditions in local areas, offering potential applications in GNSS performance analyses for local areas by generating various ionospheric scenarios.

• 산업경영시스템학회지
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• 제39권3호
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• pp.1-9
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• 2016

NSS (Navigation satellite system) provides the information for determining the position, velocity and time of users in real time using satellite-networking, and is classified into GNSS (Global NSS) and RNSS (Regional NSS). Although GNSS services for global users, the exactitude of provided information is dissatisfied with the degree required in modern systems such as unmanned system, autonomous navigation system for aircraft, ship and others, air-traffic control system. Especially, due to concern about the monopoly status of the countries operating it, some other countries have already considered establishing RNSS. The RNSS services for users within a specific area, however, it not only gives more precise information than those from GNSS, but also can be operated independently from the NSS of other countries. Thus, for Korean RNSS, this paper suggests the methodology to design the satellite constellation considering the regional features of Korean Peninsula. It intends to determine the orbits and the arrangement of navigation satellites for minimizing PDOP (Position dilution of precision). PGA (Parallel Genetic Algorithm) geared to solve this nonlinear optimization problem is proposed and STK (System tool kit) software is used for simulating their space flight. The PGA is composed of several GAs and iterates the process that they search the solution for a problem during the pre-specified generations, and then mutually exchange the superior solutions investigated by each GA. Numerical experiments were performed with increasing from four to seven satellites for Korean RNSS. When the RNSS was established by seven satellites, the time ratio that PDOP was measured to less than 5 (i.e. better than 'Good' level on the meaning of the PDOP value) was found to 94.3% and PDOP was always kept at 10 or less (i.e. better than 'Moderate' level).

• 한국항해항만학회지
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• 제32권1호
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• pp.73-80
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• 2008

본 연구의 목적은 DEA를 사용하여 지방해양수산청의 생산효율성과 경쟁력을 측정하고자 하는 것이다. 선형문제 분석기 EMS를 사용하여 기술적 효율성 프론티어로 부터 한 방향 또는 다른 방향의 거리를 측정한다. 투입지향 측정은 산출 요소를 유지한 상태에서 효율성을 위한 투입요소의 감소치를 측정한다. 이와 같이 산출지향 측정은 입력 요소를 유지한 상태에서 효율성에 필요한 산출수치를 측정하고 무지향 측정은 효율성 개선을 위하여 투입과 산출에 대해 양방향으로 필요한 수치를 측정한다. DEA를 사용한 분석결과에 따라 비효율적 지방해양수산청은 항만행정과 공공기관의 생산 효율성을 강화하기 위하여 상대적으로 효율적인 지방해양수산청을 벤치마킹할 것이 권고된다. 생산효율성에 관한 자료는 모든 활용영역에서 정책 입안자에게 방법론을 제공하고 다양한 체제에서 운용할 수 있는 기초가 될 것이다.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2009년도 공동학술대회
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• pp.397-401
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• 2009

세계적인 경제위기 시기를 맞아 최근 정부는 경제위기 극복은 물론 저탄소 녹색성장을 통하여 경제의 성장동력을 찾고자 노력하고 있다. 그리고 2008년 초에 불어닥친 초고유가 사태는 해양교통시설업무를 추진함에 있어 관련 운영시설의 비효율적인 에너지 낭비 요소를 적극 발굴하고 친환경적인 대체에너지 체계를 적극 도입하는 계기가 되었다. 이에 따라 예산절감 등 정부의 '초 고유가 대응 에너지절약대책'에 부응하기 위하여 추진되었던 태양광발전시스템 확충 등의 자체 개선사례 분석을 통하여 해양교통시설의 친환경 에너지시스템 적용가능성에 관하여 논하고자 한다.