OFDM 전송기술을 이용하는 무선 LAN용 동기 알고리즘

김장욱,유기희,오창헌,조성준 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.2A

IEEE 802.11a WLAN(Wireless Local Area Network)의 동기 알고리즘은 짧은 훈련심볼, 긴 훈련 심볼 그리고 파일롯을 이용하는 세가지 단계를 거쳐야 되는데 실제구현상에서는 두 가지의 문제점을 가지고 있다. 첫째는 긴 훈련 심볼 및 파일롯을 이용하는 동기 과정이 복잡하다. 둘째로 긴 훈련 심볼 영역에서는 짧은 훈련 심볼에서 구해진 오프셋 정정 계수만을 이용한 보상이 이루어지기 때문에 긴 훈련 심볼 영역에서 구한 등화기 계수를 완전히 신뢰 할 수가 없고 이러한 불안정한 영역에서 등화기 계수를 구하게 된다면 성능에 악영향을 미치게 된다. 특히, 시스템의 데이터 영역이 54 Mbps 전송이 가능한 구조로 이루어져 있고 데이터 길이가 최대인 경우에 시스템의 성능열화가 가장 심하게 나타난다. 본 논문에서는 이러한 동기단에서의 구현상의 복잡성과 구조적인 오류의 문제점을 해결할 수 있는 새로운 알고리즘을 제안하고 컴퓨터 시뮬레이션을 통해 이를 확인 한다. The synchronization algorithm of IEEE 802.11a WLAN(Wireless Local Area Network) has three consecutive processes, which use a short code training symbol, a long code training symbol and a pilot symbol respectively. But in using this synchronization processes, the actual embodiment has two problems. First, the synchronization process has the complex structure using a long code training symbol and a pilot symbol. Second, since the long training symbol is only compensated with the offset correction coefficient, it can not be trusted perfectly. If the equalizer coefficient is obtained in this unstable period, the system performance is degraded. In particular, the system performance becomes worst in case of the 54 Mbps transmission system using the maximum length of data. In this paper, the new algorithm is proposed which can resolve the embodiment complexity of synchronization processes and structural defect, and also it is confirmed by simulation.

비선형정수계획의 새로운 발견적해법의 개발과 고성능 다중프로세서를 이용한 안전관리 시스템의 신뢰도 중복설계의 최적화

김장욱,김재환,황승옥,박춘일,금상호 해양환경안전학회 1995 海洋環境安全學會誌 Vol.1 No.2

This study is concerned with developing a heuristic algorithm for solving a class of ninlinear integer programs(NLIP). Exact algrithm for solving a NLIP either may not exist, or may take an unrealistically large amount of computing time. This study develops a new heuristic, the Excursion Algorithm(EA), for solving a class of NLIP's. It turns out that excursions over a bounded feasible and/or infeasible region is effective in alleviation the risks of being trapped at a lical optimum. The developed EA is applied to the redundancy optimization problems for improving the system safety, and is compared with other existing heuristic methods. We also include simulated annealing(SA) method in the comparision experiment due to ist populatrity for solving complex combinatorial problems. Computational results indicate that the proposed EA performs consistently better than the other in terms of solution quality, with moderate increase in computing time. Therefore, the proposed EA is believed to be an attractive alternative to other heuristic methods.

고속도로의 주행속도예측 및 주행환경만족도 모형 개발에 관한 연구

김장욱,김정현,이수범,장일준 대한교통학회 2009 대한교통학회지 Vol.27 No.2

When most drivers take to the freeway, they don’t necessarily pay attention to the geometric design. They expect proper design by depending on their own senses and recognition. When they evaluate the features of traveling on the freeway, they can think differently than engineers. The design needs to predict the exact speed of the driver to satisfy the driver's expectation, safety, pleasure and so on. This study categorized the factors influencing the speed of six freeways considering geometric and operational features to make a prediction model of speed. The model used multiple regression with these factors and produced statically appropriate results. This study utilized the principle component analysis and the quantification Ⅱ analysis based on the image data of the satisfaction of the traveling environment collected through individual interviews. As a result, this study found the factors of satisfaction in a traveling environment. It made a satisfaction model of the traveling environment on freeways considering the change of driver's actual recognition and societal recognition using structural equations and the quantification Ⅱ theory. Through the model made in this study, This model can present not only qualitative factors like satisfaction of traveling environment on freeways, but also the quantitative elements like speed. What is important is the evaluation of features of traveling on freeways reflected in the recognition and traffic environment felt by drivers. 고속도로이용자가 주행할 때 도로기하구조를 정확하게 파악하지 못하면, 도로이용자는 자신의 감각과 인식에 의존해 판단을 내리게 되기 때문에 고속도로의 주행성을 평가할 때 설계자와는 다른 판단을 내리게 될 수도 있다. 따라서 도로이용자의 기대심리를 만족시키면서 안전성, 쾌적성 등을 확보하기 위해서는 정확한 주행속도를 예측할 필요가 있다. 또한, 고속도로의 기하구조적인 주행성뿐만 아니라 도로이용자가 이러한 구성요소의 조화에 의해 느끼는 감성적 측면에서의 주행환경만족도에 대한 인식의 변화를 파악할 필요가 있다. 이에 본 연구에서는 주행속도 예측모형 구축하기 위해 6개 고속도로(경부, 서해안, 영동, 남해, 중앙, 호남)를 대상으로 주행속도에 영향을 미치는 요인을 크게 선형요소, 교통운영특성 요소로 분류하였다. 주행속도에 영향을 미치는 요인을 대상으로 다중회귀를 이용한 주행속도예측모형 구축 및 검증 결과, 통계적으로 모두 적합한 것으로 나타났다. 또한, 본 연구에서는 고속도로 이용자를 대상으로 개별면접 설문조사를 통해 수집된 주행환경만족도 이미지 데이터를 바탕으로 수량화 제Ⅱ류 및 주성분분석을 실시하여 고속도로 주행환경만족도에 대한 영향 요인을 규명하였다. 또한 수량화 제Ⅰ류 및 구조방정식을 이용하여 사회인식 및 고속도로 이용자의 실제인식의 변화가 고려된 고속도로의 주행환경만족도 모형을 구축하였다. 본 연구에서 구축된 모형을 통해 주행속도와 같은 정량적인 요인뿐만 아니라 도로이용자가 느끼는 고속도로의 주행환경만족도와 같은 정성적인 요인에 대한 결과도 제시할 수 있어서 도로이용자가 느끼는 변화된 교통 환경과 인식여부가 반영된 고속도로의 주행성을 평가할 수 있다는 데에 그 의의가 있다.

제주지역 온도구배하우스 온도조건별 2년생 인삼 연풍의 생육특성 비교

김장욱,김영창,이정우,김동휘,손인창,정우석,김기홍 한국약용작물학회 2015 한국약용작물학술대회 발표집 Vol.2015 No.05

여객철도 이용객 통행행태 조사.분석 연구

김장욱,신미화,배영규,왕연대,Kim, Jang-Uk,Sin, Mi-Hwa,Bae, Yeong-Gyu,Wang, Yeon-Dae 대한교통학회 2013 교통 기술과 정책 Vol.10 No.1

철도 종사자의 인적오류 분석·평가·예방 기술개발

김장욱 대한산업공학회 2023 대한산업공학회 춘계학술대회논문집 Vol.2023 No.5

3년생 인삼 품종의 작물학적 특성

김장욱,김영창,이정우,조익현,김동휘,성봉재,안영남,김기홍 한국약용작물학회 2015 한국약용작물학술대회 발표집 Vol.2015 No.05

인삼 고온저항성․다수성 품종 ‘진원’

김장욱,김영창,김동휘,이정우,조익현,박기춘,방경환,현동윤,최진국,성봉재,안영남,윤예지 한국약용작물학회 2018 한국약용작물학술대회 발표집 Vol.2018 No.05

Background : Recently, there is a urgent demand for development of new varieties with enhanced resistance to various biotic/abiotic stresses. In order to develop ginseng varieties with such traits, systematic breeding program and comprehensive field studies are prerequisite. Methods and Results : ‘Jinwon' seeds were collected in 2003 from the farmer field of Pocheon. Physiological investigation and propagation were conducted from 2008 to 2010. It was given the name 'Eumseong No. 11 through the observed yield trial from 2011 to 2013 and local adaptability was carried out from 2014 to 2017. All phenotypes including agronomic characteristics, seed yield, and physiological response to biotic/abiotic stresses were investigated according to the ginseng GAP and UPOV guidelines. Red leaf and red berry at maturing stage were observed. The time of emergence, flowering and berry maturity of the ‘Jinwon’ were faster than those of ‘Chunpoong’. Stem length of ‘Jinwon’ was longer than that of ‘Chunpoong’, whereas stem diameter was thicker than that of ‘Chunpoong’. Main root length was similar but main root diameter is thicker than that of ‘Chunpoong’. The yield performance of this variety was 576 ㎏/10 a in local adaptability test for two years, which is 9% higher than that of ‘Chunpoong’. ‘Jinwon’ showed strong resistance at high temperatures. Conclusion : Our study demonstrated that ‘Jinwon’ is an ideal variety with heavier root weight and enhanced stress resistance and contribute will enhance biotic/abiotic stress resistance and increase the farmers' income.

고려인삼 주요 재배 지역별 품종의 지상부 생육특성

김장욱,김영창,방경환,김동휘,최진국,정햇님,김동원,김기홍 한국약용작물학회 2013 한국약용작물학술대회 발표집 Vol.2013 No.10

樂燒技法에 對한 硏究

김장욱 기전여자대학 1995 論文集 Vol.15 No.-

Raku as a style of pottery originated in kyoto in the late sixteenth century with the potter chojiro,a korean immigrant. Raku was prized by japanese tea masters because it is unpretentious but aesthetically pleasing and embodies the ideals of Zen Buddhism and wabi. Raku was first brought to the attention of the western world by Bernard Leach. warren Gilbertson was probably the first potter to introduce raku to the united states directly. The beginning of raku in America beyond Gilbertson's introdution of the technique are difficult to ascertain. The potter who is responsible for establishing raku as a popular,creative method of pottery making is paul soldner. soldner spontaneously put a piece in some leaves to hum. Thus was born today's contempory incarnation of the raku process - postfiring reduction. Soldner has been at the fore front of raku from those earlist days,As his influence spread, so did the popularity of raku. Koreans are used to high temperature technique blue celadon and white celadon. At first,the raku technique wasn't popular and refused for a new. However,the raku technique will have a short firing time and fast result,even in a picnic setting. If you try this technique,you can exprience a exitement and pleasant suprise of irregular changes. For beginner and young ceramists,this can be very useful and use for developement of creation,due to it's low cost of firing and kiln production. But it needs to find a substitute materials for Gerstley Borate or Colemite. For professional ceramist,this technique fits very well to. modern arts theory of deformation and it gives a veriety of colors from low temperature firing. I think this goes well with modern taste and can contribute to open a new field of korea modern ceramis.