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Reed-Solomon부호의 복호를 위한 수정 유클리드 알고리즘의 효율적인 반복 셀 구조
김우현,이상설,송문규,Kim, Woo-Hyun,Lee, Sang-Seol,Song, Moon-Kyou 대한전자공학회 1999 電子工學會論文誌, C Vol.c36 No.1
Reed-Solomon(RS) 부호는 CD-ROM, HDTV, ATM 그리고 디지털 VCR 등 여러 분야에서 연집(burst) 오류를 정정하기 위해 적용되어 왔다. RS 부호를 복호하기 위해서는 Berlekamp-Massey 알고리즘, 유클리드 알고리즘 그리고 수정 유클리드 알고리즘(MEA)이 개발되었다. 최근에는 이들 중에서도 MEA가 가장 자주 사용되었다. 본 논문은 부호의 복호에 사용되는 MEA을 위한 효율적인 반복 셀 구조를 제안한다. 제안된 구조의 두 가지 주된 특징은 다음과 같다. 첫째, MEA의 수행에 있어 기존의 방법[1] 보다 약 25% 적은 수의 클럭 사이클을 이용한다. 둘째, MEA 수행에 소비되는 클럭 사이클의 수가 부호의 길이 n보다 큰 경우 MEA 셀의 개수를 줄일 수 있었으며, 수신된 워드를 위한 버퍼 요구량 또한 줄일 수 있었다. 예로써 (128,124) RS 부호에 대한 MEA 회로가 VHDL을 통하여 기술되고 검증된다. Reed-Solomon(RS) codes have been employed to correct burst errors in applications such as CD-ROM, HDTV, ATM and digital VCRs. For the decoding RS codes, the Berlekamp-Massey algorithm, Euclidean algorithm and modified Euclidean algorithm(MEA) have been developed among which the MEA becomes the most popular decoding scheme. We propose an efficient recursive cell architecture suitable for the MEA. The advantages of the proposed scheme are twofold. First, The proposed architecture uses about 25% less clock cycles required in the MEA operation than[1]. Second, the number of recursive MEA cells can be reduced, when the number of clock cycles spent in the MEA operation is larger than code word length n. thereby buffer requirement for the received words can be reduced. For demonstration, the MEA circurity for (128,124) RS code have been described and the MEA operation is verified through VHDL.
SAF: 디스크 탐색 시간 향상을 위한 파일 시스템 내 스왑 공간 할당 기법
안우현,김보곤,김병규,오재원,Ahn, Woo-Hyun,Kim, Bo-Gon,Kim, Byung-Gyu,Oh, Jae-Won 한국정보통신학회 2011 한국정보통신학회논문지 Vol.15 No.6
최근 고성능 컴퓨터에서 메모리 사용량이 매우 큰 프로그램과 파일 접근을 많이 하는 프로그램을 동시에 실행하고 있다. 많은 메모리의 사용은 디스크의 스왑 공간에 대해 디스크 접근을 빈번히 발생시키고, 파일 접근은 디스크의 파일 시스템 파티션으로 디스크 접근을 야기한다. 이런 두 종류의 프로그램을 동시에 실행하면 스왑 공간과 파일 시스템 파티션 간에 디스크 탐색이 빈번히 발생할 수 있다. 이런 문제를 해결하기 위해 본 논문은 SAF 기법을 제안한다. 이 기법은 파일 시스템 파티션에 새롭게 여러 개의 스왑 공간을 배치하고, 이들 공간에 페이지-아웃되는 페이지들을 저장한다. 즉, 페이지들은 가장 최근에 접근한 파일의 디스크 위치에 근접한 스왑 공간에 저장된다. 이 스왑 공간이 기존의 스왑 공간에 비해 최근 접근된 파일의 위치로부터 가까운 거리에 있기 때문에 파일 접근 후 발생하는 디스크 탐색의 시간을 크게 줄일 수 있다. 성능 검증을 위해 BSD기반의 FreeBSD 6.2 운영체제에 SAF를 구현하였고, 5개의 벤치마크를 실행하여 성능을 측정하였다. 성능 측정 결과 SAF는 FreeBSD에 비해 벤치마크의 실행 시간을 약 14%∼42% 감소시켰다. In recent computer systems with high-performance, users execute programs needing large memory and programs intensively accessing files simultaneously. Such a large memory requirement makes virtual memory systems access swap spaces in disk, and intensive file accesses require file systems to access file system partitions in disk. Executing the two kinds of programs at once incurs large disk seeks between swap spaces and file system partitions frequently. To solve the problem, this paper proposes a new scheme called SAF to create several swap spaces in a file system partition, where pages to be paged out are stored. When a page is paged out, the scheme stores the page to one of the swap spaces close to a disk location where the most recently accessed file is located. The chosen swap space in the file system partition is closer to the disk location than the traditional swap space, so that our scheme can reduce the large disk seek time spent to move to the traditional swap space in paging out a page. The experiment of our scheme implemented in FreeBSD 6.2 shows that SAF reduces the execution time of several benchmarks over FreeBSD ranging from 14% to 42%.
김우현(Kim Woo Hyun),김경남(Kim Kyoung Nam) 대한치과의사협회 2010 대한치과의사협회지 Vol.48 No.2
Titanium and titanium alloys are the most common materials used for dental and biomedical implants, owing to their biocompatibility and favourable mechanical properties. However infection of the region surrounding a dental implant by pathogenic microorganisms is a significant factor in implant failure. Prevention and control of microbial colonization of implant surfaces is considerable interest to the biomedical community. One important strategy is to render the implant surface antibacterial by impeding the formation of biofilm. A number of approaches have been proposed for this purpose. Therefore, we reviewed the researches of antibacterial coatings on titanium implants in this articles.
임우현(Woo Hyun Lim),민병열(Byung Yeol Min),최문식(Mun Shik Choi),김규석(Kyu Suk Kim) 한국강구조학회 1996 韓國鋼構造學會誌 Vol.8 No.2
The problem of large concentrated forces acting over limited areas of concrete is one of frequent occurence in civil engineering design. Steel base plates of stanchions over concrete footing, anchorages in post-tensioned concrete beams, shear keys in composite structures, concrete beams at bearing, bridge bearings over piers, concrete hinges and bearing blocks, beams over walls and concrete columns and pile heads, etc., are a few instances of bearing problems. The experimental studies for bearing strength of concrete were reported so far by previous investigators, and the formulars were recommended in codes of practice of various countries. In this study, the obtained results of the test are presented. The results show that the major testing parameters are the ratio of bearing area to the concrete area and the size of specimen.
기하학적 모델 및 색상 모델에 기반한 이동물체 추적에 관한 연구
김우현(Woo-hyun Kim),기창두(Chang-doo Kee) 한국자동차공학회 2003 한국자동차공학회 지부 학술대회 논문집 Vol.2003 No.5
As there have been many interests about a real-time detection in a face recognition field, the research of face detection is being progressed lively through skin-color model for quick processing. However, if the color of background and skin-color is almost alike, unexpected recognition will happen. Also, face recognition which is a important field of pattern-recognition includes complex difficulty like size, shape, and position of target object, background, and lighting, but the faces give us wide information like inherent face-color, head movement, face shape, eyes, a nose, a lip.<br/> Using this much information, we present face-tracking method in this paper by combining skin-color chaser and ellipse chaser in given conditions.<br/> We use ellipse chaser as the first algorithm, and skin-color chaser which has human's skin-color. By experiment using two chasers, this algorithm shows robustness in face-tracking<br/> <br/>
김우현 ( Woo-hyun Kim ),박동웅 ( Dong-wung Park ) 한국고등직업교육학회 1999 한국고등직업교육학회 학술대회 논문집 Vol.1999 No.11
This paper describes algorithm to extract license plates in vehicles. Neural networks have been trained to perform complex functions in various fields of application including pattern recognition, identification, classfication, speech, vision and control systems. Today, neural networks can be trained to solve problems that are difficult for conventional computers or humanbeing. The recognition methods using neural networks have two ones. In this paper, First, we input the normalized self-image and learned the real image. Second, we extracted charastic vector and learned it. But, the former is ideal method that is required many units according to resolution. Also, in increasing interconnection number, it takes many time to recognize an image. The latter has a decreasing problem of recognition and merits to reduce units and interconnection number in a few input. Simulation shows that the proposed algorithm having character recognition system using multi-layer neural networks improves the recognition rate in various learning data.
김우현,길경석,김성욱,Kim, Woo-Hyun,Kil, Gyung-Suk,Kim, Sung-Wook 한국전기전자재료학회 2019 전기전자재료학회논문지 Vol.32 No.4
Induction motors connected with a three-phase AC system may malfunction due to reverse phase or open phase faults. Conventional overcurrent relays and overheating relays are used to prevent such accidents; however, their drawbacks include a low response speed and false operation. Therefore, in this study, a digital relay for the reverse-open phase was designed and fabricated. This relay can detect the reverse phase and open phase faults and send a trigger signal to the control circuit. The proposed relay was developed based on a microcontroller. The detection times of the reverse phase and open phase were verified as 320ms and 80ms, respectively. Compared with conventional relays that only protect the motor from one type of fault, the proposed relay can detect both, reverse phase and open phase faults. In addition, the fault detection, identification criterion, and trigger signal patterns can be modified by programming according to the requirements of users.