• 산업공학
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• 제15권1호
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• pp.1-9
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• 2002

Tandem AGV system is obtained by partitioning all workstations into multiple zones assigning a single vehicle to each zone. In this paper, we propose an analytical model to design a tandem AGV system with multi-load AGVs. Using simulation, the performance of the proposed model is shown by comparing a conventional multi-load AGV system.

• Journal of Mechanical Science and Technology
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• 제19권12호
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• pp.2270-2280
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• 2005

An experimental study is performed for turbulent swirling flow behind a circular cylinder using 2-D PIV technique. The Reynolds number investigated are 10,000, 15,000, 20,000 and 25,000. The mean velocity vector, time mean axial velocity, turbulence intensity, kinetic energy and Reynolds shear stress behind the cylinder are measured before and behind the round cylinder along the test tube. A comparison is included with non swirl flow behind a circular and square cylinder. The recirculation zones are showed asymmetric profiles.

• 호남수학학술지
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• 제46권2호
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• pp.209-223
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• 2024

In this paper, we investigate the spatial quaternionic expressions of the ruled surfaces whose base curves are formed by the Smarandache curve. Moreover, we formulate the striction curves and dralls of these surfaces. If the quaternionic Smarandache ruled surfaces are closed, the pitches and angle of pitches are interpreted. Finally, we calculate the integral invariants of these surfaces using quaternionic formulas.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.110-113
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• 2002

Statistical- based, principal component analysis (PCA) was applied to chemical data from two underground storage systems containing LPG to assess the usefulness of such technique at the initial stage (Pyeongtaek) or middle stage (Ulsan) of hydrochemical studies. For the first case, both natural and anthropogenic contamination characterize regional groundwater. Saline water buffered by Namyang lake affects as a natural factor, whereas cement grouting influence as an artificial factor. For the second study area, contaminations due to operation of LPG caverns, such as disinfection activity and cement grouting effect, deteriorate groundwater quality. This study indicates that principal component analysis would be particularly useful for summarizing large data set for the purpose of subsurface characterization, assessing their vulnerability to contamination and protecting recharge zones.

• Wind and Structures
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• 제31권3호
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• pp.197-207
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• 2020

Knowledge on the design value of extreme wind pressure coefficients (EWPC) of a specific zone of buildings is essential for the wind-resistant capacity of claddings. This paper presents a method to estimate the representative EWPC introducing the multivariate extreme value model. The spatial correlations of the extreme wind pressures at different locations can be consider through the multivariate extreme value. The moving average method is also adopted in this method, so that the measured point pressure can be converted to wind pressure of an area. The proposed method is applied to wind tunnel test results of a large flat roof building. Comparison with existing methods shows that it can give a good estimation for all target zones with different sizes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권5호
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• pp.2218-2244
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• 2016

In this paper, we propose a hybrid routing scheme that utilizes location information to support reliable data transmission in mobile ad hoc networks. The proposed scheme determines and maintains routing path by considering the directionality and connectivity of nodes using grid zones and information on neighbor nodes. In addition, it generates alternative paths with consideration for node distance and reliability. To show the superiority of the proposed routing scheme, a performance evaluation was conducted using simulations. The performance evaluation results show that the proposed scheme offers faster and more reliable data transmission than the existing routing schemes, and the number of messages decreases by approximately 31% compared to the existing schemes on average.

• Journal of Electrical Engineering and Technology
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• 제9권4호
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• pp.1188-1195
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• 2014

This paper presents an analytical technique for reliability evaluation of electrical distribution network (EDN) containing distributed generation (DG). Based on hierarchical levels of circuit breaker controlling zones and feeder sections, a directed-relation-graph (DRG) for an END is formed to describe the hierarchical structure of the EDN. The reliability indices of EDN and load points can be evaluated directly using the formed DRG, and the reliability evaluation of an EDN containing DGs can also be done without re-forming the DRG. The proposed technique incorporates multi-state models of photovoltaic and diesel generations, as well as weather factors. The IEEE-RBTS Bus 6 EDN is used to validate the proposed technique; and a practical campus EDN containing DG was also analyzed using the proposed technique.

• 대한교통학회지
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• 제34권6호
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• pp.489-498
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• 2016

이 연구는 어린이 보호구역과 인근지역의 교통사고를 다루고 있다. 이 연구의 목적은 공간적 특성을 고려한 어린이 교통사고모형을 개발하는데 있다. 이를 위해 이 연구는 2012-2014년 동안 청주시 초등학교 60개소에서 발생한 어린이 교통사고 자료를 수집하였다. 연구의 주요 결과는 다음과 같다. 첫째, 통계적으로 유의한 두 개의 어린이 교통사고(사고건수 및 EPDO) 모형이 개발된다. 가산자료 모형 중 포아송 모형이 선택되며, 모형의 우도비는 0.533 및 0.273로 분석 된다. 둘째, 모형의 공통변수로는 4차로 이상의 도로 비율, 진출입구 수, 어린이 보호구역내 신호 횡단보도 수, 어린이 보호구역 표지판 수, 어린이 보호구역 노면표지 수 및 속도제한 표지 수인 것으로 분석된다. 특정변수는 대상지 내 도로 연장, 도로 반사경 및 어린이 보호구역 외 신호 횡단보도 수로 평가된다. 마지막으로 이 연구는 어린이가 많은 도로에서는 운전자의 주의 및 인지를 향상시킬 수 있는 시설이 필요하다는 것을 보여준다.

• 대한지리학회지
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• 제49권1호
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• pp.91-105
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• 2014

이 연구의 목적은 광양만권경제자유구역(GFEZ) 제1단계(2004-2010) 사업의 개발과정과 성과를 고찰하는 것이다. 제1단계 사업대상은 전체 22개 사업 중에서 11개이며, 3개 사업은 종료된 반면, 8개 사업은 종료되지 못하고 현재 진행 중이다. 제1단계 개발사업은 기업유치를 위한 기반시설 개발과 공급, 사회간접시설 확충에 중점을 두기 때문에 사업성과는 그렇게 많지 않았다. 제1단계 개발사업 주요 성과는 산업용지와 주택용지개발과 공급, 도로와 철도 확충, 광양 컨테이너부두 8선석 준공, 102개 기업유치와 신규고용 창출 등이다. 유치된 기업들은 광양항 배후단지와 율촌1산단에 주로 입지하였고, 물류 및 관련서비스, 철강, 기계, 조선, 정밀화학 등의 업종이 많았다. 제1단계 사업의 문제와 한계는 저조한 외국인투자기업 유치실적, 재원조달능력이 우수한 개발사업자 유치 부족, 중소기업 중심의 입주기업, 하동지구 개발사업 지연 등으로 나타났다.

• Archives of Plastic Surgery
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• 제44권4호
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• pp.332-336
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• 2017

Background Little is known concerning hair diameter variation within the safe donor area for hair transplantation surgery. Thicker or thinner hair may be needed, depending on the recipient area, hairline design, and the purpose of surgery. Methods Twenty-seven patients (7 men and 20 women; mean age, 28 years; range, 20-47 years) were included in this study. The midoccipital point was used as the reference point on the horizontal plane at the upper border of the helical rim. The target area width was 15 cm (7.5 cm to the right and left of the reference point) and the height was 8 cm (2 cm above and 6 cm below the reference point). The study area was divided horizontally into 3 5-cm sections (A, B, C) and vertically into 4 2-cm sections (1-4), creating a total of 12 zones. Ten anagen hairs were randomly obtained from each zone and their diameters were measured. Results Hair diameter in the 4 vertical sections varied significantly, gradually decreasing from sections 1 (superior) to 4 (inferior) in all 3 horizontal sections (A, B, and C). Conclusions Our results suggest that sections 1 and 2 of the occipital safe donor area would be useful for obtaining thicker hair, such as in procedures to treat male- and female-pattern hair loss, whereas hair from zones 3 and 4 could be useful for transplantation surgery requiring thinner hair, such as eyebrows, eyelashes, and female hairline correction. Our results may be clinically valuable for planning hair transplant surgery and choosing the optimal donor region.