• Journal of information and communication convergence engineering
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• 제4권3호
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• pp.114-117
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• 2006

In this paper, we fabricated the EM wave absorber for 94 GHz radar sensors using Permalloy of magnetic material with chlorinated polyethylene (CPE), and S-parameter was measured. The complex relative permittivity and permeability are calculated by the measured data. Absorption abilities are simulated according to different thickness of the EM wave absorbers, and the EM wave absorber was manufactured based on the simulated design. Simulated and measured results agree very well. As a result, we developed the EM wave absorber with the thickness of 1.15 mm which has an absorption ability of 18 dB at 94 GHz.

• 전기학회논문지
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• 제56권8호
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• pp.1412-1417
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• 2007

Magnetic anomaly generated around a ship is mainly due to the permanent magnetization(PM) and induced magnetization (IM) remaining on the hull. It is very difficult to predict the direction and its magnitude of the permanent magnetization distributed over the hull, that is caused by mechanical or thermal stress. In this paper, an effective method is proposed to separate two components, the one produced by PM and the other by IM, from the underwater earth field signal distorted by the ferromagnetic material of the ship. The method can easily provide the two kinds of magnetic anomaly through exploiting experimental results and 3D electromagnetic field analyses even though the PM distribution on the hull is not known. To validate the proposed method, a model ship is manufactured and tested. The results would be of much help to basis research for securing safe navigation of a ship against dangerous factors in underwater.

• 한국항만학회지
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• 제10권2호
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• pp.61-68
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• 1996

The main problems in structural analysis by Finite Eelement Method are difficulty in making data file and error estimation. For decreasing these problems' pays. have been suggesting the adaptive mesh refinement and error estimation method. Posteriory error estimation methods suggested by Jang[1], Babuska[2,3], Ohtsubo[8,9], and this paper. Comparing these methods and examine their properties. According this paper, In the problem supposed having singularity, the method suggested by this paper is good, But the problem supposed having no singularity, the method suggested by Jang[1] is good. For decreasing the effect of initial mesh in p-refinement, make application h-refinement at first and apply p-refinement, and confine polynomial's degree to two, for making program simply by plural mesh models are not needed.

• 한국항만학회지
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• 제10권1호
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• pp.53-61
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• 1996

This paper describes the effect of wave control using submerged flat plate by the numerical calculation and the hydraulic model test. The boundary element method is used to develop a numerical solution for the flow field caused by monochromatic oblique waves incident upon an infinitely long, sumerged flat plate situated in arbitrary water depth. The effect of wave blocking is examined according to the change of length, submerged depth of flat plate and incident angles. Numerical results show that longer length, shallower submergence of flat plate and larger incident angles enhance the effect of wave blocking. To validate numerical analysis method, hydraulic model test was conducted in 2-D wave flume with 60 cm metal sheet. Reflected waves are extracted from water surface elevation in front of the location of a submerged plate by least square method with 3 wave gages. From comparing experimental results with numerical results, efficiency of numerical analysis method by this study could be confirmed well within wide ranges of wave frequencies.

• 한국항만학회지
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• 제5권2호
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• pp.3-10
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• 1991

Although Korea has had a proud maritime history of thousands of years marked by outstanding leaders such as Chang Bogo and Yi Soon-shin there has not been a unified 'Ocean Day' like the one in Japan. Extensive historical survey revealed eight candidate days for ocean day designation. Historical significance, seasonal consideration and other factors were examined with respect to each candidate date. Of the eight events the establishment of Chunghaejin maritime base on the island of Wando on the southern coast of Korea by Admiral Changbogo in the lunar month of April in the year of 828 is judged to have the greatest desirability Institution of 'Ocean Day' is recommended with the date to celebrate as May 20(a convenient date of May as translated into solar month). A weeklong celebration throughout the country is also recommended with colorful events to be had over the Ocean Week following the Ocean Day.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2020년도 추계학술대회
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• pp.361-363
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• 2020

기존의 지도 또는 길 찾기 기능을 사용 할 때 방향 정보를 직관적으로 제시해주는 네비게이션 구현을 목표로, 사용 지역을 캠퍼스 내로 국한시켜 증강현실을 이용한 네비게이션을 구현하였다. 본 애플리케이션 개발에는 Mapbox maps API, ARCore, Unity 3D Engine, Android studio를 사용하였다. 사용지역을 확대시켜 Mobile device 뿐만 아니라 자동차 앞 유리 디스플레이에 접목하여 보다 다양한 서비스 제공을 기대할 수 있다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2020년도 추계학술발표대회
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• pp.992-995
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• 2020

시각-언어 이동 작업은 에이전트가 주어진 지시를 따라 특정 실내 공간 내에서 목적 위치로 이동하는 작업이다. 시각-언어 이동 작업의 특성상 자연어 지시 속에 등장하는 랜드마크인 장소 정보를 인지하는 것은 작업을 수행하는 데 큰 도움이 된다. 본 논문에서는 환경을 구성하는 주요 장소 정보를 저장하기 위한 장소 미리보기 메모리를 제안한다. 에이전트는 장소 미리보기 메모리에 저장된 장소 정보를 고려하여 작업을 수행하게 된다. 본 논문에서는 Matterport3D 시뮬레이션 환경에서의 실험을 통해 R2R 벤치마크 데이터 집합에서 가장 높은 성능을 보였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2020년도 춘계학술발표대회
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• pp.559-562
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• 2020

시각-언어 이동 문제는 시각 이해와 언어 이해 능력을 함께 요구하는 복합 지능 문제이다. 본 논문에서는 시각-언어 이동 에이전트를 위한 새로운 학습 모델을 제안한다. 이 모델은 데모 데이터에 기초한 모방 학습과 행동 보상에 기초한 강화 학습을 함께 결합한 복합 학습을 채택하고 있다. 따라서 이 모델은 데모 데이타에 편향될 수 있는 모방 학습의 문제와 상대적으로 낮은 데이터 효율성을 갖는 강화 학습의 문제를 상호 보완적으로 해소할 수 있다. 또한, 제안 모델은 서로 다른 두 학습 간에 발생 가능한 학습 불균형도 고려하여 손실 정규화를 포함하고 있다. 또, 제안 모델에서는 기존 연구들에서 사용되어온 목적지 기반 보상 함수의 문제점을 발견하고, 이를 해결하기 위해 설계된 새로은 최적 경로 기반 보상 함수를 이용한다. 본 논문에서는 Matterport3D 시뮬레이션 환경과 R2R 벤치마크 데이터 집합을 이용한 다양한 실들을 통해, 제안 모델의 높은 성능을 입증하였다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2023년도 추계학술발표대회
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• pp.848-849
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• 2023

본 논문은 로봇의 실내 환경에서의 자율성을 높이기 위한 SLAM과 내비게이션 방법을 제시한다. 2D LiDAR와 카메라를 이용하여 위치를 인식하고 사람과 장애물을 의미론적으로 검출하며, ICP와 RTAB-map, YOLOv3를 통합하여 Semantic Map을 생성하고 실내 환경에서 자율성을 유지한다. 이 연구를 통해 로봇이 복잡한 환경에서도 높은 수준의 자율성을 유지할 수 있는지 확인하고자 한다.

• 한국해양공학회지
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• 제38권3호
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• pp.115-123
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• 2024

USBL systems are essential for providing accurate positions of autonomous underwater vehicles (AUVs). On the other hand, the accuracy can be degraded by outliers because of the environmental conditions. A failure to address these outliers can significantly impact the reliability of underwater localization and navigation systems. This paper proposes a novel outlier rejection algorithm for AUV localization using Voronoi diagrams and query point calculation. The Voronoi diagram divides data space into Voronoi cells that center on ultra-short baseline (USBL) data, and the calculated query point determines if the corresponding USBL data is an inlier. This study conducted experiments acquiring GPS and USBL data simultaneously and optimized the algorithm empirically based on the acquired data. In addition, the proposed method was applied to a sensor fusion algorithm to verify its effectiveness, resulting in improved pose estimations. The proposed method can be applied to various sensor fusion algorithms as a preprocess and could be used for outlier rejection for other 2D-based location sensors.