• Steel and Composite Structures
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• 제7권5호
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• pp.391-404
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• 2007

This paper presents push-out tests of stud shear connectors to examine their fatigue behavior for developing a new composite bridge deck system. The fifteen push-out specimens of D16 mm stud welded on 9 mm steel plate were fabricated according to Eurocode-4, and a series of fatigue endurance test and residual strength test were performed. Additionally, the stiffness and strength variations by cyclic loading were compared. The push-out test, when the stiffness reduction ratio of the specimens was 0.95 under cyclic load, resulted in the failure of the studs. The stiffness variation of the push-out specimens additionally showed that the application of cyclic loads reduced the residual strength. The fatigue strength of the shear connectors were compared with the design values specified in the Eurocode-4, ASSHTO LRFD and JSSC codes. The comparison result showed that the fatigue endurance of the specimens satisfies the design values of these codes.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2002년도 춘계학술발표논문집 (하)
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• pp.1085-1088
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• 2002

제7차 교육 개혁 후 초등학생들에게도 컴퓨터를 접할 수 있는 기회가 더 많이 주어졌다. 환경의 변화에 따라 초등학생들을 위한 컴퓨터 교육의 필요성이 대두되고, 개인 수준별 컴퓨터 수업이 필요하게 되었다. 현재 초등학생들을 위한 교육용 프로그램과 인터넷을 활용한 수업이 진행중이나 개인의 수준을 고려한 수업과는 거리가 멀기 때문에 본 논문에서는 초등학교 컴퓨터 수업의 활발한 진행과 개인별 수준을 고려한 수업을 위해 Push 기반 단계별 교육시스템을 제안하였다. 제안한 시스템은 Push 기술을 사용함으로써 능동적 학습참여와 개인별 수준을 고려한 수업이 가능하다는 면에서 7차 교육과정의 교육 목표에 맞는 시스템이라 할 수 있다.

• Steel and Composite Structures
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• 제43권4호
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• pp.511-522
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• 2022

An experimental investigation to study the behaviour of connections between cold-formed steel (CFS) joist and plywood structural panel is presented in this paper. Material testing on CFS and plywood was carried out to assess their mechanical properties and behaviour. Push-out tests were conducted to determine the slip modulus and failure modes of three different shear connection types. The employed shear connectors in the study were; size 14 (6mm diameter) self-drilling screw, M12 coach screw, and M12 nut and bolt. The effective bending stiffness of composite cold-formed steel and plywood T-beam assembly is calculated based on the slip modulus values computed from push-out tests. The effective bending stiffness was increased by 25.5%, 18% and 30.2% for self-drilling screw, coach screw, nut and bolt, respectively, over the stiffness of cold-formed steel joist alone. This finding suggests the potential to enhance the structural performance of composite cold-formed steel and timber flooring system by mobilisation of composite action present between timber sheathing and CFS joist.

• Industrial Engineering and Management Systems
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• 제14권4호
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• pp.401-412
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• 2015

In this paper, we present a modeling approach to production planning for an actual production line and a heuristic method. We also illustrate the successful implementation of the proposed method on the production line. A heuristic algorithm called the push-back algorithm was designed for a single machine earliness/tardiness production planning with distinct due date. It was developed by combining a minimum slack time rule and shortest processing time rule with a push-back procedure. The results of a numerical experiment on the heuristic's performance are presented in comparison with the results of IBM ILOG CPLEX. The proposed algorithm was applied to an actual case of production planning at Woongjin Chemical, a leading manufacturer of filter products in South Korea. The seven-month execution of our algorithm led to a 24.5% decrease in the company's inventory level, thus demonstrating its practicality and effectiveness.

• 소성∙가공
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• 제12권8호
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• pp.724-729
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• 2003

In order to study the shearing characteristic of anti-vibration sheet metal which is used to reduce vibration noise, a blanking die was manufactured to blank a workpiece. The variables employed in this study were clearance, type of stripper plate, position of the rubber layer and type of the die design. These variables were used to study the effects on burr height, blank diameter and camber height. In the case of burr height from experimental investigation, the push-back die, combined with a movable stripper plate, showed greater burr height. The rubber-top position of a workpiece resulted in better qualities regardless of working variables. In the comparison of diameter measurement, the use of the push-back die with a fixed stripper plate, with a 4.5% clearance, showed better accuracy. For comparing camber height, the push-back die resulted in less cambering than the drop-through die. Also, the larger the clearance, the greater was the camber height. Considering experimental results, the shearing of anti-vibrational sheet metal is best achieved when the rubber layer is laying on the top, blanked with a fixed stripper plate in a push-back die, with a 4.5％ clearance.

• Journal of Information Technology Applications and Management
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• 제22권4호
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• pp.105-126
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• 2015

In this study, we investigated the impact of the information richness and reachness on the mobile purchasing and the moderating effect of individual characteristics. We examined the information richness and reachness through SNS information and Push notification of smartphone, respectively. As the moderating variables, we adopted customer's value orientation and innovativeness. In the main-effect model with no moderating variable, both of information richness and reachness showed significant effects on the perceived value of products and purchasing channel. Especially, the impact of information richness was more significant on product awareness, while the impact of information reachness was more significant on channel awareness. In the interaction-effect model with moderating variables, customer's value orientation showed significant moderating effect on the impact of perceived product value. However, customer's innovativeness did not show the significant moderating effect on the impact of perceived channel value. It implies that the impact of information reachness applies to the majority of customers, regardless of her [his] innovativeness. Therefore the organizations might be able to use Push notification to activate the customer's mobile purchasing.

• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.1029-1036
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• 2012

Push-pull-type copolymers - low-band-gap copolymers of electron-rich fused-ring units (such as cyclopentadithiophene; CPDT) and electron-deficient units (such as benzothiadiazole; BT) - are promising donor materials for organic solar cells. Following a design principles proposed in our previous study, we investigate the electronic structure of a series of new CPDTBT derivatives with various electron-withdrawing groups using the time-dependent density functional theory and predict their power conversion efficiency from a newlydeveloped protocol using the Scharber diagram. Significantly improved efficiencies are expected for derivatives with carbonyl [C=O], carbonothioyl [C=S], dicyano [$C(CN)_2$] and dicyanomethylene [C=$C(CN)_2$] groups, but these polymers with no long alkyl side chain attached to them are likely to be insoluble in most organic solvents and inapplicable to low-cost solution processes. We thus devise several approaches to attach alkyl side chains to these polymers while keeping their high efficiencies.

• Journal of Power Electronics
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• 제17권1호
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• pp.20-30
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• 2017

A novel zero-voltage-switching (ZVS) push-pull forward converter with a parallel resonant network is presented in this paper. The novel topology can provide a releasing loop for the energy storage in a leakage inductor for the duration of the power switching by the resonant capacitors paralleled with the primary windings of the transformer. Then the transformer leakage inductor is utilized to be resonant with the parallel capacitor, and the ZVS operation is achieved. This converter exhibits many advantages such as lower duty-cycle losses, limited peak voltage across the rectifier diodes and a higher efficiency. Furthermore, the operating principles and key problems of the converter design are analyzed in detail, and the ZVS conditions are derived. A 500W experimental converter prototype has been built to verify the effectiveness of the proposed converter, and its maximum efficiency reaches 94.8%.

• 한국산림과학회지
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• 제100권3호
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• pp.327-333
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• 2011

본 연구는 등산객의 건강과 관련된 동기요인과 산림환경이 갖는 유인요인을 도출하고 이들 요인 간의 분석을 통하여 산림휴양공간에 대한 효율적인 관리방안을 제시하는 데 그 목적이 있다. 도봉산, 북한산, 관악산, 청계산을 찾은 등산객 440명에 대해 건강과 관련된 15개의 동기항목 및 11개의 유인항목을 설문조사한 결과, 등산동기요인으로 '질병치료 치유', '정신 사회적 건강', '신체적 건강' 등 3개 요인을, 등산유인요인으로는 '인문환경', '사회경제적 환경', '자연환경' 등 3개 요인을 도출하였다. 요인 간 영향관계 분석결과, 질병치료 치유요인과 신체적 건강요인에 가장 큰 영향을 미치는 유인요인은 자연환경요인으로 나타났으며, 정신 사회적 건강요인에 가장 큰 영향을 미치는 유인요인은 사회경제적 환경요인으로 나타났다.

• 대한방사선기술학회지:방사선기술과학
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• 제45권5호
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• pp.391-396
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• 2022

The purpose of this study was to investigate the effect of cross arms and palms facing forward on spinopelvic parameters during the whole spine lateral radiography. In addition, we would like to present the usefulness of a posture with the palm facing forward during whole spine lateral radiography of the spine using EOS. The subjects of this study were images of a total of 50 patients (18 males, 32 females) who whole spine lateral radiography using the conventional method and the EOS method from October 2020 to March 2021. The posture used in this study was set as 'CAP' for cross arms and 'PUSH' for posture with palms facing forward. In this study, among the spinal stability factors, thoracic kyphosis (thoracic vertebrae 4 to 12), lumbar lordosis (lumbar vertebrae 1 to sacrum 1), sagittal vertical axis, sacral slope, and shoulder flexion angle were compared on average. The mean thoracic kyphosis was 34.52±12.46° for CAP and 28.46±10.81° for PUSH (p<0.01). The lumbar lordosis of CAP was 42.45±17.45°and that of PUSH was 40.56±16.14°(p>0.57). The sagittal vertical axis was 26.59±34.34 mm in CAP and 21.21±35.41 mm in PUSH (p>0.44). In CAP, the sacral slope was 30.96±10.29°, and in PUSH, it was 31.01±10.19° (p>0.98). shoulder flexion angle was 38.31±8.24° for CAP and 26,08±6.71° for PUSH(p<0.01). As a result of this study, the PUSH posture is considered to be a posture that can minimize the shoulder flexion angle and can perform a stable examination while minimizing changes in spino-pelvic parameter.