• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.6
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• pp.602-612
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• 2013

In this paper, a design and fabrication of miniaturized 5.3 GHz reflection type $360^{\circ}$ analog phase shifter with branch line coupler and $360^{\circ}$ variable reactance load. In order to miniaturize phase shifter, novel branch line coupler is proposed. The novel branch line coupler is miniaturized using transformation of transmission line to T and ${\pi}$ type equivalent circuit. The miniaturized branch line coupler has small size of above 50 % compared with conventional branch line coupler. For wide phase shift range, $360^{\circ}$ variable reactance load structure is adopted. Especially, the structure was improved for linear phase shift by adding transmission line which acts as an impedance transformer. The improved structure was miniaturized using the equivalent lumped-element of transmission line. The fabricated phase shifter with $15{\times}15mm^2$ shows wide phase shift of above $480^{\circ}$, the insertion loss of -4~-6 dB and the reflection loss of below -20 dB at 5.3 GHz under 0~10 V control voltage range.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.216-217
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• 2018

소형 활주선의 경우, 대형 저속선 대비 항주자세의 변화가 크기 때문에 CFD 해석시 저항성능과 운동성능 결과에 오차가 발생할 수 있다. 본 연구에서는 Warped 2 선형을 대상으로 상용 CFD 코드인 STAR-CCM+ v9.04를 사용한 CFD해석을 수행하여, 이를 모형시험 결과와 비교하여 오차를 확인하였고, 또한 오차의 원인을 분석했을 때, 선체 하부의 Numerical ventilation 현상과 Spray 영역에 문제가 있다고 판단하였다. 추후 연구에서는 오차 해결 방법으로 VOF Phase replacement 기법과 Spray 영역에 대한 격자 최적화 방법을 연구하고자 한다.

• Journal of Korea Ship Safrty Technology Authority
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• v.14
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• pp.30-43
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• 2004

국내 소형 어선은, 목선이 80% 이상, FRP선이 20%내외, 강선이 1% 이내를 차지하고 있다. 소형 목선과 FRP선은 크기가 작고 구성물질이 레이더 전자파를 반사키는 강도가 약하므로 중. 대형 선박에서 탐지하지 못하여 충돌에 의한 해난사고가 가장 큰 비율로 발생하고 있다.<중략>

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.9
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• pp.888-895
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• 2004

This paper proposes new miniaturization method of parallel coupled line filter by using capacitors and grounding. Proposed method can reduce resonator size by using only a small number of capacitor and grounding of parallel coupled line filter which is conventional in field of RF filters because of its design and fabrication simplicity. This paper applies the miniaturization method of transmission line and parallel coupled line to parallel coupled line filter, and presents that grounding can reduce the number of shut capacitors. Presented miniaturized method has merits of miniaturization of parallel coupled line, harmonic suppression, and improvement of high frequency skirt with harmonic suppression. For verification of proposed method, this paper presents a hairpin filter, which has 900 MHz center frequency and 10 % FBW, miniaturized to λ/4 by proposed method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.210-211
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• 2023

To reduce maritime accidents and improve safety for domestic ships, the government has developed and is operating the Korean e-Navigation Service. The ship collision and grounding monitoring service and the route planning service were developed based on the experience of captains and navigators who navigated large ships. However, in Korea, small ships account for a large portion of the users of these services, so there are various difficulties and additional requirements for applying services based on large ships to small ships. To improve this, a data science-based algorithm model using maritime digital traffic information is being developed for small ships, and it is important to evaluate the performance of the developed model and compare its accuracy with existing services. In this study, we propose a performance evaluation method for the developed algorithm model and study how to compare and evaluate its accuracy with existing e-navigation services.

• Journal of Korea Fishing Vessel Association
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• v.56
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• pp.50-54
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• 1993

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.1-2
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• 2011

최근 많은 분야에 무인시스템이 도입되고 있다. 초기에는 산업분야에서 인간이 하기 힘들거나 위험한 작업을 대신하는 단순 반복적인 자동화기술이 대부분이었으나, 최근에는 전자통신 기술발달에 힘입어 무인자동차, 무인항공기, 무인잠수정, 무인선박 등이 연구 개발되고 있다. 본연구에서는 자율형 소형무인선을 개발하고자 하였으며, 이와 관련하여 인터넷기반의 무선통신제어, 동력 추진 조타 냉각시스템, GPS 영상 헤딩센서 등 센싱시스템, 자율운항을 위한 제어기설계, GUI 등을 연구하였다. 아울러, 해상실험을 통해 유효성을 검증하였다.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.383-388
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• 2005

To install a radar reflector on small ships, such as a small fishing vessel, a fishery buoy, and a barge ship for fishery, it is very important to develop the optimal system which may determine a proper installation location. For this, the response characteristics how waves have an effect on the small ships should be accurately analyzed. In this paper, we analyze the dynamic behaviors of small ships, which may be caused by irregular waves. To do this, we investigate how a barge ship responses to wavelength, water depth, and directions of incoming waves. The analyzed results shall be utilized to evaluate an effect on a radar cross section when we install an radar reflector on a barge ship for fishery and a small ship.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.8-14
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• 2020

According to the statistics provided by Korean Maritime Safety Tribunal for the year 2018, the majority of marine accidents in the past four years have occurred in fishing boats and small-sized boats. Negligent behavior resulting from not looking outside and non-compliance with navigation laws are the primary reasons behind ship collisions. Although safety education and training are reinforced to prevent such accidents, they still occur frequently. Hence, technical methods are continuously being developed to reduce ship collisions caused by human cause. The objective of this study is to reduce ship collisions by employing the WAVE communication system, which has short transmitting and receiving periods that can be incorporated for high-speed small-sized vessels. In this study, the suitability of the communication range was examined, and the appropriate range and timing for avoidance motion were accordingly selected, and a control algorithm based on the same was thereby designed. Consequently normal operation of the collision avoidance system was verified by connecting and simulating the proposed WAVE communication router-controller-steering equipment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.371-378
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• 2016

We have studied on the maritime navigation with functions of navigation route search and maritime safety information for small-size fishery ships, fishing boats, yachts, and boats in coastal seas. We have designed a smart phone application which is more exact information on marine obstacles of islands, aquafarms, and rocks by using land navigation techniques. Our navigation system is relatively easy to be used for costal navigation and may be a substitute for expensive ECDIS(Electronic Chart Display and Information System). Our system consists of maritime navigation databases to manage necessary maritime data and a mobile application to support maritime navigation for operators. We believe that our research findings can improve safety navigation in coastal seas by supporting lower cost, no time-consuming installation and maintenance, and easy-to-use operations.