• Industrial Engineering and Management Systems
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• 제8권4호
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• pp.247-256
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• 2009

In mass production industries such as steel making that have large equipment, sudden stops of production process due to machine failure can cause severe problems. To prevent such situations, machine diagnosis techniques play important roles. Many methods have been developed focusing on this subject. In this paper, we propose a method for the early detection of the failure on rotating machine, which is the most common theme in the machine failure detection field. A simplified method of calculating autocorrelation function is introduced and is utilized for ARMA model identification. Furthermore, an absolute deterioration factor such as Bicoherence is introduced. Machine diagnosis can be executed by this simplified calculation method of system parameter distance with weight. Proposed method proved to be a practical index for machine diagnosis by numerical examples.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.409-416
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• 2003

We consider the problem of grouping orders into lots. The problem is modelled by a graph G = (V, E). where each node $\nu\;\in\;V$ denotes order specification and its weight $\omega(\nu)$ the orders on hand for the specification. We ran construct a lot simply from orders or single specification For a set of nodes (specifications) $\theta\;\subseteq\;V$, if the distance or any two nodes in $\theta$ is at most d, it is also possible to make a lot using orders on the nodes. The objective is to maximize the number of lots with size exactly $\lambda$. In this paper, we prove that our problem is NP-Complete when d = 2, $\lambda\;=\;3$ and each weight is 0 or 1. Moreover, it is also shown to be NP-Complete when d = 1, $\lambda\;=\;3$ and each weight is 1, 2 or 3

• 대한산업공학회지
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• 제29권4호
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• pp.253-258
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• 2003

We consider the problem of grouping orders into lots. The problem is modelled by a graph G=(V,E), where each node ${\nu}{\in}V$ denotes order specification and its weight ${\omega}(\nu)$ the orders on hand for the specification. We can construct a lot simply from orders of single specification. For a set of nodes (specifications) ${\theta}{\subseteq}V$, if the distance of any two nodes in $\theta$ is at most d, it is also possible to make a lot using orders on the nodes. The objective is to maximize the number of lots with size exactly $\lambda$. In this paper, we prove that our problem is NP-Complete when $d=2,{\lambda}=3$ and each weight is 0 or 1. Moreover, it is also shown to be NP-Complete when $d=1,{\lambda}=3$ and each weight is 1,2 or 3.

• Tuberculosis and Respiratory Diseases
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• 제76권6호
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• pp.269-275
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• 2014

Background: The six-minute walk test has been widely used in people with chronic cardiopulmonary disorders as an outcome assessment with regards to therapeutic or prognostic determinants. This study was undertaken to determine the six-minute walk distance (6MWD) in a sample of healthy Koreans and to create a reference equation. We also compared the 6MWD of our cohort with previously published equations. Methods: Two hundred fifty-nine healthy subjects (95 males) aged 22-59 years performed two walking tests using a standardized protocol. 6MWD was defined as the greatest distance achieved from the two tests. The effect of anthropometrics on the 6MWD was also investigated. Results: The average 6MWD was $598.5{\pm}57.92m$, with significantly longer distances by males ($628.9{\pm}59.51m$) than females ($580.9{\pm}47.80m$) (p<0.001). Age, height, weight, and body mass index were significantly correlated with 6MWD in univariate analysis. Stepwise multiple regression showed height to be single independent predictor of 6MWD ($r^2$=0.205, p<0.001). The reference equations derived in Caucasian and North African populations tend to overestimate the distance walked by Korean subjects, while Asian equations underestimate it. Conclusion: The average 6MWD in these Korean populations was 600 m. The regression equation revealed that individual's height was the most significant predictor of distance, explaining 20.5% of the distance variance.

• 대한디지털의료영상학회논문지
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• 제15권2호
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• pp.7-11
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• 2013

Purpose: This study was to evaluate effectiveness of the modified position in scapular AP (anteriopo-sterior) projection. Materials and Methods: From June 2012 to July 2013, scapular AP projection was examined in 108 patients by use of conventional method and in 40 patients by use of modified method. We compared between conventional method and modified method following variables including sex, age, height, weight, and BMI. We measured and compared distance between lateral border of the scapular and the rib to confirm the separation of the scapular from the lung fields including the ribs. Results: The scapular AP projection was technically successful in all patients. There was no significant difference in patient characteristics including sex, age, height, weight, and BMI between conventional method and modified method. The mean distance between lateral border of the scapular and rib in conventional method and modified method was 15.09 mm and 26.33 mm, respectively. Modified method was significantly increased the distance between lateral border of the scapular and rib compared with conventional method (P < .01). Conclusion: The modified position in scapular AP projection was effective method to separate between the scapular and lung fields including the ribs compared with conventional position of scapular AP projection.

• 한국조경학회지
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• 제26권1호
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• pp.96-112
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• 1998

This study aims to evaluate the potential of pro-environmental application(PEP) in streams conceptualized ecological conservation and recreational use to be in harmony with. The main content of research are to clarify the PEP, to establish the evaluation model, and to evaluate 3 streams(Dongchon, Seokhyunchon, Okchon) in Sunchon city. Researchers introduced 12 evaluation items(water quality, water quantity, vegetation-water area, vegetation conservation, streamscape, neighborhood landscape, stream width, optimum area, nearby landuse, facility in stream, distance from user, obstacle to acces) by 5 scales to evaluate the characteristics of natural and artificial factors in stream area and nearby area. Also to decide the weight of items, researchers surveyed the opinion of 22 landscape architects experienced stream-plan through delphi method. Lastly the pro-environmental potential on streams were calculated by the ecological potential and recreational potential indices to be standardized and indicidual sections in streams were divided 5 grades on the basis of PEP. The result of this study are as follows; 1) The evaluation model of PEP was constructed by 4 steps, such as the decision of weight, the measurement of scale, the calculation of potential indices, the gradation of individual sections in streams. 2) The ecological potential were highly influenced by natural factor such as water quality, vegetation conservation, vegetation-water area, but on the other hand the recreational potential were influenced by optimum area, distance from user, water quantity, obstacle to access. 3) The factors such as vegetation conservation, optimum area, nearby landuse, distance from user were function as discernment factors to evaluate relatively ecological and recreational potential. and water quality, water quantity, vegetation -water area, neighborhood landscape were acted as important items to decide PEP.

• 한국항행학회논문지
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• 제12권5호
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• pp.494-501
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• 2008

본 논문에서는 구조화된 격자 패턴 발생기를 이용하여 카메라 시야로부터 가려진 인체의 완전한 3차원 정보를 정합하기 위하여 턴테이블 위에 놓인 인체를 4방향에서 영상을 획득한 후 각 영상을 정합하는 새로운 알고리즘을 소개한다. 다각형 망으로 표시된 정합될 두 영상은 3차원 좌표 값의 급격한 변화가 없고 주사 방향이 한 방향이기 때문에 좌표축에 따라 가중치가 다른 최소 거리 기반 가중치 이분 분할 매칭 법을 사용하여 정합한다. 완전한 3차원 체형 정보를 획득하기 위하여, 획득한 영상이 4개이기 때문에 이런 과정들을 3번 반복한다. 제안된 방법은 기존의 분지 한정법, 동적 계획법, 헝가리언 법에 비해 매칭 정확도는 조금 낮지만 탐색 시간을 200 - 300% 줄일 수 있는 장점이 있다.

• 한국GIS학회:학술대회논문집
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• 한국GIS학회 2008년도 공동추계학술대회
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• pp.270-271
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• 2008

The positioning technology for a moving object is an important and essential component of ubiquitous communication computing environment and applications, for which Radio Frequency IDentification Identification(RFID) is has been considered as also a core technology for ubiquitous wireless communication. RFID-based positioning system calculates the position of moving object based on k-nearest neighbor(k-nn) algorithm using detected k-tags which have known coordinates and k can be determined according to the detection range of RFID system. In this paper, RFID-based positioning system determines the position of moving object not using weight factor which depends on received signal strength but assuming that tags within the detection range always operate and have same weight value. Because the latter system is much more economical than the former one. The geometries of tags were determined with considerations in huge buildings like office buildings, shopping malls and warehouses, so they were determined as the line in 1-Dimensional space, the square in 2-Dimensional space and the cubic in 3-Dimensional space. In 1-Dimensional space, the optimal detection range is determined as 125% of the tag spacing distance through the analytical and numerical approach. Here, the analytical approach means a mathematical proof and the numerical approach means a simulation using matlab. But the analytical approach is very difficult in 2- and 3-Dimensional space, so through the numerical approach, the optimal detection range is determined as 134% of the tag spacing distance in 2-Dimensional space and 143% of the tag spacing distance in 3-Dimensional space. This result can be used as a fundamental study for designing RFID-based positioning system.

• 한국통신학회논문지
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• 제37권6A호
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• pp.438-449
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• 2012

본 논문에서는 다양한 CRC 코드의 성능분석을 기반으로 새로운 VHF 대역 해양 무선통신용 최적 CRC-p 코드를 제안한다. 이를 위해, 먼저 CRC 코드의 부호어 길이의 변화에 따른 미검출 오류확률과 최소해밍거리를 구하는 방법을 기술한다. 즉 순회 해밍코드나 원시 BCH 코드의 쌍대코드가 최대장 코드가 되는 것을 이용해서 천이 레지스터에 의한 간단한 회로구성으로 무게분포와 미검출 오류확률을 계산하는 방법과 MacWilliam의 항등식에 의한 최소해밍거리를 계산하는 방법을 제시한다. 다음으로 VHF 대역 해양 무선통신 시스템의 전송 프레임의 구성과 주요 통신 파라미터의 규격을 제시하고, 기존의 연구된 다양한 CRC 코드의 생성다항식을 대상으로 미검출 오류확률과 최소해밍거리의 결과를 기반으로 새로운 CRC-p 코드를 선정하고, 라이시안 해양 채널모델과 ${\pi}$/4-DQPSK 변복조기에 의한 비트오류율(BER)의 모의실험 결과를 통해 성능을 검증한다.

• 한국전산구조공학회논문집
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• 제21권3호
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• pp.295-304
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• 2008

본 연구는 두 가지 주요 목적을 갖고 있다. 첫째는, 실험적 베리오그램을 작성하는데 필수적인 분리거리 허용한계를 얼마로 하느냐에 따라 변화되는 베리오그램 모델링에 기초를 둔 정규크리깅 보간법을 유한요소법에 적용이 가능한 가를 시험하는 것이다. 둘째는, 다항식모델, 가우스모델 및 구형모델의 선택에 따른 정확성을 조사하는 것이다. 이 목적을 위해 가우스 적분점에서 취득된 응력값 데이터로터 새로운 응력장을 예측하기 위해 가중-최소제곱법이 적용되었다. 여기서 가중치는 동일한 값을 사용하는 기존의 방식과 달리 응력값들의 보간을 위해 사용되는 실험적 및 이론적 베리오그램에 의해 결정된다. 제안된 접근방식의 타당성을 보이기 위해 2개의 수치예제를 테스트하였다. 이 논문에서 사용된 수치예제의 경우 25% 분리거리 허용한계를 사용한 가우스모델이 참고문헌의 이론 해들과 가장 잘 일치하는 것을 알 수 있었다.