• 한국전자통신학회논문지
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• 제12권6호
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• pp.997-1002
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• 2017

무선전파를 사용하는 지상통신과는 달리 1500[m/s] 속도의 음향채널이 사용되는 수중통신은 수중온도, 염도를 비롯한 통신환경에 민감할 뿐 아니라 3D 공간의 영향을 받는다. 3D 수중통신은 통신공간의 복잡성과 더불어 음파의 전파손실, 해저환경에서 발생되는 음향잡음 등에 민감하다. 본 연구에서는 이와 같은 3D 수중통신환경의 특성을 고려하여 3D 수중통신환경에서 운용되는 MANET을 대상으로 전송성능을 측정 분석하고 이를 토대로 수중 MANET 운용조건을 제시한다. 본 연구는 NS-2를 기반으로 구축한 수중통신 시뮬레이터를 사용하여 수행하며, 성능파라미터로는 처리율, 전송지연, 패킷손실율 및 소비에너지를 사용한다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제32권2호
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• pp.75-84
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• 2005

연속패턴은 다양한 분야에서 사용되는 데이타 마이닝 기법의 한 종류이다. 하지만 현재의 연속 패턴 방법은 한개의 속성내에서의 패턴만을 감지할 수 있으며 속성간의 패턴을 생성할 수 없다. 다차원의 연속패턴은 일차원에 비하여 훤씬 유용한 정보를 제공할 수 있다. 본 연구에서는 Hellinger 엔트로피 함수를 사용하여 다차원의 연속패턴을 생성하는 방법을 게시한다 기존의 연속패턴방법과 달리 본 방법에서는 각 연속패턴의 중요도를 자동으로 계산할 수 있다. 또한 계산의 복잡도를 감소시키기 위한 다수의 법칙이 개발되었으며 다수의 실험 결과를 제시하였다.

• 대한원격탐사학회지
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• 제20권1호
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• pp.57-64
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• 2004

In GIS-based network analysis, topological measure of network structure can be considered as one of important factors in the urban transportation analysis. Related to this measure, it is known that the connectivity indices such as alpha index and gamma index, which mean degree of network connectivity and complexity on a graph or a circuit, provide fundamental information. On the other hand, shimbel index is one of GIS-based spatial metrics to characterize degree of network concentration. However, the approach using these quantitative indices has not been widely used in practical level yet. In this study, an application program, in complied as extension, running on ArcView- GIS is implemented and demonstrated case examples using basic layers such as road centerline and administrative boundary. In this approach, geo-spatial imagery can be effectively used to actual applications to determine the analysis zone, which is composed of networks to extract these indices. As the results of the implementation and the case examples, it is notified that alpha and gamma indices as well as shimbel index can be used as referential data or auxiliary information for urban planning and transportation planning.

• 지역연구
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• 제37권3호
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• pp.3-18
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• 2021

4차 산업혁명이 지역의 산업구조를 변화시키면서, 지역의 특성을 반영한 새로운 산업과 기술의 발전이 요구되고 있다. 본 연구의 목적은 부산, 울산, 경남을 대상으로 지식 간 연관성과 기술의 복합성을 측정하고 지역의 산업 차별화 전략의 가능성이 있는 기술을 파악하는 것이다. 2015~2019년의 특허 자료를 이용하여 652개의 IPC 코드에서 동시출현행렬을 도출하고 지식 간 연관성과 기술의 복합성 지수를 계산하였다. 지식 간 연관성을 이용하여 네트워크 분석을 시행하였다. 분석 결과 동남권의 중심지식은 기계 부문이 큰 비중을 차지하였으며 화학과 전기 부문이 뒤를 이었다. 지역 산업의 차별화 가능성이 있는 기술을 도출하기 위해 위험-편익 프레임워크를 적용한 결과 저위험-고편익의 기술 역량은 상이하게 나타났다. 부산은 기계공학 중 엔진, 기계조작, 운송 등의 기술이 울산은 화학의 환경기술과 재료, 기계공학의 열처리 기술이 저위험-고편익의 역량을 가진 기술로 나타났다. 경남은 김해, 양산, 창원 등에서 기계공학, 화학, 전기공학 일부 기술 등에서 역량이 나타났다. 본 연구의 결과는 지역 내 잠재된 지식을 기반으로 하여 지역성장을 위한 전략 산업의 선정과 도출에 가능성이 있는 기술을 파악하였다는데 의의가 있다.

• ETRI Journal
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• 제42권1호
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• pp.101-107
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• 2020

For Korean language processing, morphological analysis is a critical component that requires extensive work. This morphological analysis can be conducted in an end-to-end manner without requiring a complicated feature design using a sequence-to-sequence model. However, the sequence-to-sequence model has a time complexity of O(n²) for an input length n when using the attention mechanism technique for high performance. In this study, we propose a linear-time Korean morphological analysis model using a local monotonic attention mechanism relying on monotonic alignment, which is a characteristic of Korean morphological analysis. The proposed model indicates an extreme improvement in a single threaded environment and a high morphometric F1-measure even for a hard attention model with the elimination of the attention mechanism formula.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2701-2706
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• 2003

This paper describes weld seam tracking and error compensation methods of automatic plasma arc welding system designed for the corrugation panel that consists of a linear section and a curved section with various curvatures. Realizing automatic welding system, we are faced with two problems. One is a precise seam tracking and the other is an arc length control. Due to the complexity of the panel shape, it is difficult to find a seam and operate a torch manually in the welding process. So, laser vision sensor for seam tracking is equipped for sensing the seam position and controlling the height of a torch automatically. To attain more precise measurement of an arc length, we measure the 3D shape of the panel and analyze error factors according to the various panel states and caused errors are predicted through the welding process. Using that result, compensation algorithm is added to that of arc length control and real time error compensation is achieved. The result shows that these two methods work effectively.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.607-610
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• 2002

Even though digital video coding techniques have been developed very rapidly, rate controlling is still an unsolved problem. This paper presents a new scene adaptive video encoding scheme for MPEG-1 and MPEG-2 video encoders. Degradation of picture quality at scene changes due to poor prediction of global complexity measure is addressed. The proposed scheme determines the picture types adaptively based on scene contents of each video frame. The effective placement of reference and inter-reference frames is studied at sudden scene changes and gradual scene changes respectively. Results show that the proposed scheme demonstrates a significant improvement in performance compared to TM5〔1〕.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권6호
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• pp.2669-2688
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• 2016

An efficient and effective unsupervised single moving object detection framework is presented in this paper. Given the sparsely labelled trajectory points, we adopt a coarse-to-fine strategy to detect and segment the foreground from the background. The superpixel level coarse segmentation reduces the complexity of subsequent processing, and the pixel level refinement improves the segmentation accuracy. A distance measurement is devised in the coarse segmentation stage to measure the similarities between generated superpixels, which can then be used for clustering. Moreover, a Quadmap is introduced to facilitate the refinement in the fine segmentation stage. According to the experiments, our algorithm is effective and efficient, and favorable results can be achieved compared with state-of-the-art methods.

• 대한기계학회논문집
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• 제19권6호
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• pp.1539-1544
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• 1995

Copper blow test to measure the forging capability of 35 ton counterblow hammer and upset of plasticine on the model hammer to investigate the change of the blow efficiency during the forging process have been performed together with finite element analyses of these experiments. The blow efficiency of the hammer has been found to be dependent on the friction and on the contact area between the die and the workpiece. The effects of the volume and the aspect ratio of the billet have not been found. Inferring from the experimental results and Schey's empirical formula on the forging load, we expect that the efficiency also varies with the flow stress of the workpiece material and with the shape complexity of the forging product.

• Korea-Australia Rheology Journal
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• 제21권2호
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• pp.83-89
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• 2009

Coating process plays an important role in information technology such as display, battery, chip manufacturing and so on. However, due to complexity of coating material and fast deformation of the coating flow, the process is hard to control and it is difficult to maintain the desired quality of the products. Moreover, it is hard to measure the coating process because of severe processing conditions such as high drying temperature, high deformation coating flow, and sensitivity to the processing variables etc. In this article, the coating process is to be re-illuminated from the rheological perspectives. The practical approach to analyze and quantify the coating process is discussed with respect to coating materials, coating flow and drying process. The ideas on the rheology control of coating materials, pressure and wet thickness control in patch coating process, and stress measurement during drying process will be discussed.