• Steel and Composite Structures
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• 제17권3호
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• pp.237-252
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• 2014

The use of composite structures is increasingly present in civil building works. Composite Box Girder Bridges (CBGB), particularly, are study of effect of shear connector's numbers and distribution on the behavior of CBGBs is submitted. A Predicti structures consisting of two materials, both connected by metal devices known as shear connectors. The main functions of these connectors are to allow for the joint behavior of the girder-deck, to restrict longitudinal slipping and uplifting at the element's interface and to take shear forces. This paper presents 3D numerical models of CBGBs to simulate their actual structural behavior, with emphasis on the girder-deck interface. Additionally, a Prediction of several FE models is assessed against the results acquired from a field test. A number of factors are considered, and confirmed through experiments, especially full shear connections, which are obviously essential in composite box girder. A good representation for shear connectors by suitable element type is considered. Numerical predictions of vertical displacements at critical sections fit fairly well with those evaluated experimentally. The agreement between the FE models and the experimental models show that the FE model can aid engineers in design practices of box girder bridges. Preliminary results indicate that number of shear studs can be significantly reduced to facilitate adoption of a new arrangement in modeling CBGBs with full composition. However, a further feasibility study to investigate the practical and economic aspects of such a remedy is recommended, and it may represent partial composition in such modeling.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.329-336
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• 2007

For scaling of the gradient of misfit function, we develop a new pseudo-Hessian matrix constructed by combining amplitude field and pseudo-Hessian matrix. Since pseudo- Hessian matrix neglects the calculation of the zero-lag auto-correlation of impulse responses in the approximate Hessian matrix, the pseudo-Hessian matrix has a limitation to scale the gradient of misfit function compared to the approximate Hessian matrix. To validate the new pseudo- Hessian matrix, we perform frequency-domain elastic full waveform inversion using this Hessian matrix. By synthetic experiments, we show that the new pseudo-Hessian matrix can give better convergence to the true model than the old one does. Furthermore, since the amplitude fields are intrinsically obtained in forward modeling procedure, we do not have to pay any extra cost to compute the new pseudo-Hessian. We think that the new pseudo-Hessian matrix can be used as an alternative of the approximate Hessian matrix of the Gauss-Newton method.

• 한국융합학회논문지
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• 제9권3호
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• pp.131-135
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• 2018

본 연구의 목적은 완전몰입 가상현실이 자율신경계에 미치는 영향을 알아보는데 있다. 본 연구의 대상자는 가상현실 장비를 접하지 않은 17명의 20대 남성으로 하였다. 대상자에게 완전몰입 가상현실 콘텐츠를 제공받았고, 적용 전과 후에 5분 동안의 심전도 신호를 측정하였다. 획득한 심전도 신호는 교감신경계의 활성을 반영하는 LF, 부교감신경계의 활성을 반영하는 HF, 자율신경계의 전반적인 활성을 반영하는 TP, 그리고 자율신경계의 활성 균형을 반영하는 LF/HF로 분석하여 자율신경계를 평가하였다. 그 결과, 완전몰입 가상현실을 적용한 후 대상자의 HF와 TP는 적용 전에 비해 유의하게 감소하였고, LF/HF는 유의하게 증가하였다. 본 연구의 결과에 따르면 완전몰입 가상현실은 자율신경계에 스트레스를 제공하지만, 그 변화는 건강한 성인의 정상범위 내에 있다는 것을 확인할 수 있었다. 따라서 완전몰입 가상현실은 건강한 성인에게 안전하게 적용될 수 있다.

• 한국추진공학회지
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• 제11권4호
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• pp.26-37
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• 2007

통합 가상 엔진의 "Numerical Test Cell" 시험은 다분야 연계 해석을 통하여 하드웨어의 개발에 필요한 시간과 비용을 줄일 수 있다. 본 논문에서는 미국과 유럽에서의 전체 엔진 시뮬레이션 프로그램의 개발 활동과 NPSS를 바탕으로 관련 기술(공학 모델, 시뮬레이션 환경, 고성능 컴퓨팅)을 소개한다. 미국의 NASA Glenn 연구소는 기존의 코드들을 결합하고 기능을 개선하여 NPSS 개발 연구를 이끌고 있으며, 유럽에서는 대학, 연구소, 기업체로 구성된 VIVACE 컨소시움이 각 기관의 프로그램을 통합하여 PROOSIS를 개발하고 있다. 아울러 현재의 상황에 대한 고찰을 통하여 국내 개발의 가능성을 살펴보았다.

• 대한영양사협회학술지
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• 제3권1호
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• pp.63-73
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• 1997

This study was conducted to evaluate the industry foodservice management practices and to suggest guidelines for the effective foodservice management. The survey for the analysis was conducted through the questionnaires to dietitians. They were divided into two groups : the site color worker and the blue color worker. The questionnaires were received for a response rate of 73.2%. Statistical data analysis was completed using the SAS programs for descriptive analysis, $x^2$ test, T-test, F-test, and Fisher's LSD. The results of the study can be summarized as follows : 1) The level of education of dietitians and food cost in the employee feeding operations for the blue color worker was lower than the employee feeding operations for the white color worker. 2) The labor productivity indices were not significantly different according to types of workers. But in the employee feeding operations for the blue color worker, full-time foodservice employees worked more than 10.7 hour per week than their counterpart. This indicates the full-time foodservice employees in the employee feeding operations for the blue color worker performed more loaded work compared to the employee feeding operations for the white color worker. 3) Equipped rate of facilities in the employee feeding operations for the blue color worker was low especially in the food preparation and cooking processes.

• 한국산학기술학회논문지
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• 제10권7호
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• pp.1725-1728
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• 2009

본 연구개발에서는 정해진 환경에서 최대의 불량검출 능력을 발휘할 수 있도록 공정을 개선하기 위하여 전게이트 시각검사에 필수적인 FGV 패턴발생 장치와 공정제어 장치를 개발하였다. 본 연구개발을 통하여 접촉손실(Tact Loss)을 0에 근접 한 수준으로 유지할 뿐만 아니라 손실 및 에러 발생시 신속한 대처가 가능하여 모듈의 수율을 향상시킬 수 있을 것으로 기대된다. 또한 세부 동작 시퀀스를 제어하기 위한 H/W와 S/W 시스템을 생산라인에 실장하고 성능점검 및 인증을 수행한 결과 Tact에 의한 Pixel 불량의 경우는 98.1%, Line 불량의 경우는 99.1%의 검출율을 나타내었으며, Gate 및 Visual 레벨 테스트를 포함한 모듈공정 전체의 수율이 98.3%까지 증가하였다.

• 환경생물
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• 제36권4호
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• pp.456-462
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• 2018

The purpose of this study was to assess cross-generational effects of bisphenol A exposure in benthic copepods, Tigriopus west. Nauplii (<24 hours old) were exposed to graded concentrations of bisphenol A, and toxicity end-points such as survival, development, sex ratio, and fecundity were measured. $F_1$ generations were grown under innoxious conditions, and similarly assessed. Significant differences were observed in development of nauplii and copepodites, between exposed and non-exposed copepods; however, there were no differences in survival of nauplii or copepodites, sex ratio, or brooding rate in parental generation. In contrast, in the $F_1$ generation, there were significant differences between the control group and exposed group in survival and development of nauplii. Length, width, and biomass of parental and $F_1$ generations were reduced in the exposed group compared to the control group. In addition, some deformities, such as swelling of the prosome, abnormally shaped egg sac, and dwarfism were observed after exposure to bisphenol A. So, our study demonstrates that a cross-generation toxicity test and monitoring of morphological deformities in harpacticoid copepods, can be useful for development of potential bioindicators for environmental monitoring, and assessment of chemical impact.

• 한국정밀공학회지
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• 제17권5호
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• pp.100-107
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• 2000

The hydraulic couplings have been widely used in industries, automobile, and power-station drives including ships. A mathematical analysis by which the design and application of hydraulic couplings are made is used in conventional design formulae and general roto-dynamic theories. The fluid flow of hydraulic couplings can be considered to have two component, one circumferentially about the coupling axis, and the other passing fluid from the pump to the turbine in the plane of the coupling axis. Tests have been carried out on the full-scale production coupling. The performance test consists of taking measurement of torque of the fluid coupling for three different amount of working fluid inside with various loads to the output shaft. The purpose of this research is to construct the experimental test equipments and to establish a series of performance test for the domestically developed hydraulic couplings, and to obtain experimental results which can be used to improve the performance of the hydraulic coupling and to solve the practical problems confronted in operation.

• 품질경영학회지
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• 제27권4호
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• pp.256-265
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• 1999

In this paper, we Present the implementation of statistical process control software by using XLISP-STAT which is a kind of object oriented language under Windows environment. This software can be used to generate the graphic objects for various control charts, histogram and plots using the full-down menu system. This software can also be used to calculate control limits, process capability indices and test procedures for normality.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.279-282
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• 2002

Here we introduce so called Reference code-weighted sum of all PN codes used in the system-. We do inner product operation between received PN code and Reference code rather than locally generated PN code in the receiver. Acquisition process can be accomplished by only one inner product during full period of PN code. It's essential innovation against present method which can be viewed successive hypothesis test by inner product for entire candidate PH codes set. Well -defined decision region makes it possible. We suggest the. criterion fur designing the decision region and find a condition for weight (coefficient) of Reference code.