• Title/Summary/Keyword: Combination ratio

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Optimization of a Wire-Spacer Fuel Assembly of Liquid Metal reactor

  • Ahmad, Imteyaz;Kim, Kwang-Yong
    • 유체기계공업학회:학술대회논문집
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    • 2005.12a
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    • pp.240-243
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    • 2005
  • This study deals with the shape optimization of a wire spacer fuel assembly of Liquid Metal Reactors (LMRs). The Response Surface based optimization Method is used as an optimization technique with the Reynolds-averaged Navier-Stokes analysis of fluid flow and heat transfer using Shear Stress Transport (SST) turbulence model as a turbulence closure. Two design variables namely, pitch to fuel rod diameter ratio and lead length to fuel rod diameter ratio are selected. The objective function is defined as a combination of the heat transfer rate and the inverse of friction loss with a weighting factor. Three level full-factorial method is used to determine the training points. In total, nine experiments have been performed numerically and the resulting datas have been analysed for optimization study. Also, a comparison has been made between the optimized surface and the reference one in this study.

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A Study of Workload Change at Varying Working Posture, Work/Pest Ration and Task Type in an Automobile Assembly Task (자동차 조립작업 시 작업자세, 작업/휴식비율, 작업형태에 따른 작업부하의 변화에 관한 연구)

  • 이준엽;김철홍
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.24 no.69
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    • pp.51-64
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    • 2001
  • A laboratory experiment was conducted to investigate the effects of working posture. work/rest ration, and task type on the physical workload in automobile assembly jobs. Ten healthy male university students participated as subjects in the experiment. East subject performed 18 experimental session with combination of 3 working posture 3 work/rest ratio and 2 task types. To examine the effect of various working conditions on workload, DMG analysis was performed on 4 different muscles in the neck an arm area, Also RPE scale and heart rate were taken as response variables. The result showed that all working conditions considered in the experiment had significant effects on the workload concluding that labor intensity in auto assembly jobs should be adjusted with respect to different levels of working posture, work/rest ratio, and task type. Detailed analysis are presented in the paper.

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Partial Transmit Sequence Optimization Using Improved Harmony Search Algorithm for PAPR Reduction in OFDM

  • Singh, Mangal;Patra, Sarat Kumar
    • ETRI Journal
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    • v.39 no.6
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    • pp.782-793
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    • 2017
  • This paper considers the use of the Partial Transmit Sequence (PTS) technique to reduce the Peak-to-Average Power Ratio (PAPR) of an Orthogonal Frequency Division Multiplexing signal in wireless communication systems. Search complexity is very high in the traditional PTS scheme because it involves an extensive random search over all combinations of allowed phase vectors, and it increases exponentially with the number of phase vectors. In this paper, a suboptimal metaheuristic algorithm for phase optimization based on an improved harmony search (IHS) is applied to explore the optimal combination of phase vectors that provides improved performance compared with existing evolutionary algorithms such as the harmony search algorithm and firefly algorithm. IHS enhances the accuracy and convergence rate of the conventional algorithms with very few parameters to adjust. Simulation results show that an improved harmony search-based PTS algorithm can achieve a significant reduction in PAPR using a simple network structure compared with conventional algorithms.

Quasi-Static Tests for seismic performance of RC bridge piers (철근콘크리트 교각의 내진성능에 관한 준정적 실험)

  • 이강균;한기훈;정영수;이대형;황의승
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10b
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    • pp.615-620
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    • 1998
  • The objective of this experimental study is to investigate the hysteretic behavior of reinforced concrete piers subjected to quasi-static cyclic loads, which have been used in large numbers for railway and urban transportation facilities. Important test parameters are hoop ratio, axial load, loading type, and the behaviors f members have been evaluated through limit states of crack occurrence, yielding and ultimate state of member, ductility and load-deflection loop can be secured by considering the influence of hoop reinforcement ratio and axial load, and that plastic hinge length and ductility ar determined by the combination of the quantities of hoop reinforcement and axial load.

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An Behavior of RC Columns Using High Performance Fiber Reinforced Cement Composites under Axial Loads (일정축력을 받는 고인성 섬유보강 시멘트 복합체 기둥의 거동)

  • Hwang Sun-Kyoung;Yun Hyun-Do;Han Byung-Chan;Park Wan-Shin;Yang Il-Seung;Cheon Esther
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.05a
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    • pp.87-90
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    • 2005
  • An experimental investigation on the strength and behaviour of reinforced concrete columns using high performance fiber reinforced cement composites has been carried out. The columns were subjected to monotonic axial compression until failure. The variables in this study are the combination ratio of steel cord(SC) and Polyethylene (PE), and the volumetric ratio of transverse reinforcement Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber reinforced cement composites.

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Study on the contents of nutrients and gelation substances in the Korean persimmons (감(枾)의 영양적성분(營養的成分) 및 gel화(化) 요소함량(要素含量) 조사연구(調査硏究))

  • Kim, Youn-Soon
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.4 no.1
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    • pp.19-23
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    • 1975
  • From a study of the nutrient and gelation substances in Korean persimmon such as Jangdongsi, Pasi, Teabongsi, Kurigam, Nabjackgam, Gamsi and Hucks: The results obtained are summerized as follows: 1. According as persimmon changes into mellowed persimmon in the same kind the ammounts of sugar was increased, while the ammounts of fiber was decreased, but there was little difference in the other nutrient contents. 2. The ratio of 'Ca' and 'P' in persimmons in generally balanced at 1 : 2.5 3. Compared to the standard combination ratio of gelation substance, pectin in the persimmons was over but acid and sugars were very low.

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Joint Beamforming and Jamming for Physical Layer Security

  • Myung, Jungho;Heo, Hwanjo;Park, Jongdae
    • ETRI Journal
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    • v.37 no.5
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    • pp.898-905
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    • 2015
  • In this paper, we consider a joint beamforming and jamming design to enhance physical layer security against potential multiple eavesdroppers in a multiple-input and single-output cellular broadcast channel. With perfect channel state information at the base station, we propose various design approaches to improve the secrecy of the target user. Among the proposed approaches, the combined beamforming of maximum ratio transmission and zero-forcing transmission with a combination of maximum ratio jamming and zero-forcing jamming (MRT + ZFT with MRJ + ZFJ) shows the best security performance because it utilizes the full transmit antenna dimensions for beamforming and jamming with an efficient power allocation. The simulation results show that the secrecy rate of this particular proposed approach is better than the rates of the considered conventional approaches with quality-of-service and outage probability constraints.

A Study on the Flexible Disk Deburring Process Arc Zone Parameter Prediction Using Neural Network (신경망을 이용한 유연디스크 디버링가공 아크형상구간 인자예측에 관한 연구)

  • Yoo, Song-Min
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.6
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    • pp.681-689
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    • 2009
  • Disk grinding was often applied to deburring process in order to enhance the final product quality. Inherent chamfering capability of the flexible disk grinding process in the early stage was analyzed with respect to various process parameters including workpiece length, wheel speed, depth of cut and feed. Initial chamfered edge defined as arc zone was characterized with local radius of curvature. Averaged radius and arc zone ratio was well evaluated using neural network system. Additional neural network analysis adding workpiece length showed enhance performance in predicting arc zone ratio and curvature radius with reduced error rate. A process condition design parameter was estimated using remaining input and output parameters with the prediction error rate lower than 2.0% depending on the relevant input parameter combination and neural network structure composition.

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Design of an Ammonia/water Bubble Absorber with Binary Nanofluids (이성분 나노유체를 이용한 암모니아/물 기포 흡수기 설계)

  • Kim Jin-Kyeong;Kim Sung-Soo;Kang Yong-Tae
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.7
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    • pp.556-562
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    • 2006
  • The objectives of this paper are to analyze simultaneous heat and mass transfer performance for a plate type bubble absorber with binary nanofluids numerically and to investigate the effects of binary nanofluids and surfactants on the size of the bubble absorber. The effective absorption ratio represents the effect of binary nanofluids and surfactants on the absorption performance. The kinds and concentrations of nano-particles and surfactants are considered as the key parameters. The results show that the addition of surfactants can reduce the size of absorber up to 74.4%, the application of binary nanofluids does the size up to 63.6%. Combination of binary nanofluids and surfactants can reduce the size of absorber up to 77.4%.

An Experimental Study on RC Columns Using High Performance Fiber Reinforced Cement Composites (고인성 섬유보강 시멘트 복합체를 사용한 콘크리트 기둥의 실험적 연구)

  • Hwang Sun-Kyoung;Yun Hyun-Do;Han Byung-Chan;Park Wan-Shin;Jeon Esther;Yang Il-Seung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.631-634
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    • 2004
  • An experimental investigation on the strength and behaviour of reinforced concrete columns using high performance fiber reinforced cement composites has been carried out. The columns were subjected to monotonic axial compression until failure. The variables in this study are the combination ratio of steel cord(SCI) and polypropylene(PP), and the volumetric ratio of transverse reinforcement Test results showed that the fibers, when used in a hybrid form, could result in superior composite performance compared to their individual fiber reinforced cement composites.

  • PDF