• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.47-54
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• 2016

In the underwater environment, high resolution can be achieved in the range direction by transmitting and receiving a signal of a particular band and/or waveform. The design of a transmit signal used in the active sonar is very important in order to detect a cylindrical object within a short distance less than 1 km, which is the detection distance of this paper. Designing a transmit signal optimal to a sonar requires appropriate selection of its center frequency and bandwidth, which allows the maximum detection distance of a sonar. In this paper, in terms of maximizing echo excess and signal to noise ratio (SNR), optimum frequency analysis is carried out under various conditions of diverse parameters. In addition, the investigation focused on the determinating a bandwidth is also performed for the purpose of satisfying the performance requirement of range resolution and azimuth resolution.

• Journal of Korean Society for Geospatial Information Science
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• v.8 no.2 s.16
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• pp.89-99
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• 2000

The Quality and Accuracy of digital image is important factor for decision of accuracy in digital photogrammetry because all the inside works in digital photogrammetry are based on digital image. But it is still difficult to ensure quality assurance and appication of data because there is no distinct criterion about quality and accuracy of digital image when the works in digital photogrammetry is accomplished. This study presents optimal resolution of aerial photo through error analysis of image coordinate using auto inner orientation in digital photograrnrnetry workstation. In second step, we are valified to optimum resolution of aerial photo image with orientation analysis. Finally, we are established to validity optimal resolution of aerial photo image with production of ortho image and mosaic image using optimal resolution aerial photo image.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.658-665
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• 2019

Among the renewable energy resources, wind power is growing rapidly in terms of technological development and market share. Recently, onshore wind farm have been affected by limitations of terrestrial space and environmental problems. Consequently, installation sites have been moved to the sea, and the development of floating offshore wind farms that are installed at deep waters with more abundant wind conditions is actively underway. In the context of maritime traffic, the optimal site of offshore wind farms is required to minimize the interference between ships and wind turbines and to reduce the probability of accidents. In this study, genetic algorithm based AIS(Automatic Indentification System) data composed of genes and chromosomes has been used. The optimal site of floating offshore wind farm was selected by using 80 genes and by evaluating the fitness of genetic algorithm. Further, the final site was selected by aggregating the seasonal optimal site. During analysis, 11 optimal site were found, and it was verified that the final site selected usng the genetic algorithm was viable from the perspective of maritime traffic.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.100-102
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• 2017

선박운항의 안전과 연료 소비의 최소화 운항를 위하여 국내외적으로 최적 항로 서비스에 대한 연구와 상업적인 서비스가 진행되고 있다. 특히, 국내에서는 국제해사기구(IMO)의 "e-Navigation" 정책 추진 이후, 한국정부도 "한국형 e-Navigation 개발 사업"을 진행 중이며, 해당 연구의 일부분으로 안전에 중점을 둔 최적화 항로 서비스를 연구 개발 중이다. 일반적인 항로 추론 방업은 기상, 해상, 해양환경 등의 예측 데이터를 이용하여 선박운항에 영향을 미치는 저항 요소가 적은 위치를 찾아 항로를 추론한다. 이때 사용되는 예측데이터의 해상도에 따라 연산수행 속도와 정확도가 달라진다. 본 연구에서는 항로 추론 연산 속도와 정확도를 고려하여 최적항로를 계산하는 방법에 관한 연구이다. 이를 통해 최적항로의 실시간 최적항로 서비스와 신뢰성을 향상 시킬 수 있을 것으로 판단한다.

• Proceedings of the KIPE Conference
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• 2015.07a
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• pp.465-466
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• 2015

배터리 관리시스템(BMS;battery management system)의 중요 고려요소인 SOC(state-of-charge) 및 SOH(state-of-health)의 전기적 등가회로 모델 기반 고성능 추정의 전제 조건은 배터리 단자전압의 안정된 실험데이터 확보이다. 그러나, 예상치 않은 에러로 인해 배터리 단자전압에 노이즈 성분이 포함될 경우 SOC 및 SOH 추정알고리즘의 성능저하가 우려된다. 이를 위해, 본 논문은 이산 웨이블릿 변환(DWT;discrete wavelet transform)의 다해상도 분석(MRA;multi resolution analysis) 레벨에 따른 디노이징 최적 성능을 소개하고자 한다. 하드 임계화(hard-thresholding) 및 소프트 임계화(soft-thresholding) 기법에 따른 디노이징 성능 차이를 보이고, 각 임계화 기법 적용 시 디노이징 최적 성능을 보이는 레벨을 선택한다.

• Journal of Korea Water Resources Association
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• v.52 no.2
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• pp.107-113
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• 2019

The flood forecasting model currently used in Korea calculates the runoff of basin using the lumped rainfall-runoff model and estimates the river level using the river and reservoir routing models. The lumped model assumes homogeneous drainage zones in the basin. Therefore, it can not consider various spatial characteristics in the basin. In addition, the rainfall data used in lumped model also has the same limitation because of using the point scale rainfall data. To overcome the limitations as mentioned above, many researchers have studied to apply the distributed rainfall-runoff model to flood forecasting system. In this study, to apply the Grid-based Rainfall-Runoff Model (GRM) to the Korean flood forecasting system, the optimal resolution is determined by analyzing the difference of the results of the runoff according to the various resolutions. If the grid size is to small, the computation time becomes excessive and it is not suitable for applying to the flood forecasting model. Even if the grid size is too large, it does not fit the purpose of analyzing the spatial distribution by applying the distributed model. As a result of this study, the optimal resolution which satisfies the accuracy of the bsin runoff prediction and the calculation speed suitable for the flood forecasting was proposed. The accuracy of the runoff prediction was analyzed by comparing the Nash-Sutcliffe model efficiency coefficient (NSE). The optimal resolution estimated from this study will be used as basic data for applying the distributed rainfall-runoff model to the flood forecasting system.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.176-177
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• 2017

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.329-331
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• 2012

해상 방파제공사 수행시 대상해역의 통항선박과 현장 해상공사용 장비의 해상교통 혼잡도를 사전에 조사 분석하여 원활한 공사를 위한 대책을 수립하고자 하며, 필요할 시 통항흐름을 변경하는 방안 등 최적의 선박통항안전대책 제시.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.2
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• pp.117-128
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• 2001

In order to achieve optimal retrieval, i.e., to find the best match to a query according to a certain similarity measure, the exhaustive search should be performed literally for all the images in a database. However, the straightforward exhaustive search algorithm is computationally expensive in large image databases. To reduce its heavy computational cost, this paper presents a fast exhaustive multi-resolution search algorithm based on image database clustering. Firstly, the proposed algorithm partitions the whole image data set into a pre-defined number of clusters having similar feature contents. Next, for a given query, it checks the lower bound of distances in each cluster, eliminating disqualified clusters. Then, it only examines the candidates in the remaining clusters. To alleviate unnecessary feature matching operations in the search procedure, the distance inequality property is employed based on a multi-resolution data structure. The proposed algorithm realizes a fast exhaustive multi-resolution search for either the best match or multiple best matches to the query. Using luminance histograms as a feature, we prove that the proposed algorithm guarantees optimal retrieval with high searching speed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.371-373
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• 2012

노화-구도 연도교 개설공사 사업에 따라 대상해역을 이용하여 통항하는 선박에 대하여 교량 건설을 고려한 종합적인 해상교통 안전성 향상 방안 제시를 위해 이론적 고찰 및 Full-Mission Shiphandling Simulator를 이용하여 평가하고 근거자료를 작성한 후, 최적의 교량시설을 계획하도록 기초자료를 제공하며, 인허가 과정중 도출된 해상교량안에 대한 해상교통안전진단을 해사안전법 및 동 법 시행규칙에 의거하여 실시하였다.