• Journal of Energy Engineering
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• v.20 no.3
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• pp.236-241
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• 2011

In this study, considering a degree of proliferation resistance and sustainability, development status of perspective recycling systems for spent nuclear fuels (SNF) is comprehensively reviewed on the basis of the urgent needs of sustainable management measures for high level radioactive wastes such as spent nuclear fuels (SNF).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.535-540
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• 2019

The coupling between different models for MDO (Multi-disciplinary Optimization) greatly increases the complexity of the computational framework, while at the same time increasing CPU time and memory usage. To overcome these difficulties, POD (Proper Orthogonal Decomposition) and RBF (Radial Basis Function) are used to solve the optimization problem of determining the thickness of composites and sandwich cores when composite sandwich structures are used as aircraft wing skin materials. POD and RBF are used to construct surrogate models for the wing shape and the load data. Optimization is performed using the objective function and constraint function values which are obtained from the surrogate models.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.77-82
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• 2022

During etching process of PCB, the electroplated copper line and seed layer copper have different etching rates and it caused the over etching of copper line as well as undercut of lines. In this research, the effects of etchants composition on copper etching characteristics were investigated. The optimum concentration of hydrogen peroxide and sulfuric acid of etchants were obtained using polarization and OCV (open circuit voltage) analysis for both rolled copper and electroplated copper. The inhibiting effects of different inhibitors were investigated using OCV and ZRA (zero resistance ammeter) analysis. The galvanic current between electroplated copper and seed layer copper were measured using ZRA method. Inhibitors for least galvanic current could be chosen based on galvanic coupling in ZRA analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.272-275
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• 1999

In this paper, a wavelet transform-based adaptive interference excision scheme using the adaptive algorithm which suppresses narrow band interference in the wavelet transform domain for the direct spread modulation system application, is introduced. Using the Monte-Carlo simulation, the bit error probabilities of the direct spread communication systems with the excision systems of two kinds of Daubechies wavelets (db2, db8) in the transform domain, are analysed. With these results, it is shown that the performance of a system depends on the characteristics of wavelet being used. And with this scheme, we expect effective improvements in the direct spread communication system performance.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.52-57
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• 1997

국제 열 핵융합로 (International Thermonuclear Experimental Reactor) 의 중앙 솔레노이드(solenoid) 초전도 전자석의 피복관 (conduit) 으로서 가장 유력한 후보 재료인 니켈-철 기저 초합금에 대한 개선된 파괴역학적 거동 예측 모형을 개발하기 위하여 피로균열 성장과 파괴 인성 치의 측정이 사용되었다. 유한 요소법을 사용하는 상용 구조해석 코드인 ANSYS 제 5.2판에 의해 초전도 전자석 피복관 재료에 대한 탄소성 파괴역학적 거동을 살펴보았다. 정확한 파괴 기준을 개발하기 위하여 삼차원 J 적분 인자에 의한 결과를 사용하였다. 얇은 피복관재의 경우에 절대온도 4도에서의 적합한 파괴 인성치는 실제 단면효과를 고려한 표면균열 인장시험 결과를 토대로 J 적분으로 도출한 150 MPaㆍm$^{1}$2/ 로 제시되었다.

• Korean Journal of Ichthyology
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• v.29 no.4
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• pp.244-251
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• 2017

A total of 15 larvae [3.53~19.49 mm standard length (SL)] belonging to the family Bothidae collected from the southern sea of Korea in 2016 were identified as Psettina tosana based on 434 base-pair sequences of mitochondrial DNA cytochrome c oxidase subunit I. Larvae of Psettina tosana have anterior-most two elongated dorsal fin rays. Uniserial melanophores present on the dorsal and anal fin base, whereas melanophores on the body absent. An inflection point in the relative growth of head length and head depth against SL was shown between 9.93 mm and 10.73 mm SL. The examined larvae of Psettina tosana are clearly distinguished from the most similar species, Psettina iijimae in having no melanophore patches in the proximity of dorsal and anal fin base.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.3
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• pp.217-223
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• 2013

A digital retrodirective antenna system is easy to modify and upgrade because it can control the phase information of the output signal toward opposite direction to input signal without a priori knowledge of the arrival direction. Due to this advantage, it is possible to perform fast beam tracking. In this paper, a design digital retrosirective array antenna system according to the number of antenna array by using only one digital PLL which finds angle of delayed phase and we test BER performance of this system. When we transmit data at actual communication system, the data modulated onto carrier frequency in order to shift spectrum from base band to another band. So we simulate system considering carrier frequency according to the number of antenna array. As a result, carrier frequency has no impact on the performance.

• Journal of the Institute of Convergence Signal Processing
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• v.6 no.4
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• pp.206-211
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• 2005

We describe the design for a correlator and an access code generator in bluetooth system. These are used for a connection setting, a packet decision and a clock synchronization between Bluetooth units. The correlator consists of two blocks; carry save adder based on Wallace tree and threshold-value decision block. It determines on an useful packet and clock-synchronization for input signal of 1.0Mbps through the sliding-window correlating. The access-code generator also consists of two blocks; BCH(Bose-Chadhuri-Hocquenghem) cyclic encoder and control block. It generates the access-codes according to four steps' generation process based on Bluetooth standard. In order to solve synchronization problem, we make use of any memory as a pseudo random sequence. The proposed correlator and access-code generator were coded with VHDL. An FPGA Implementation of these modules and the simulation results are proved by Xilinx chip. The critical delay and correlative margin based on synthesis show the 4.689ns and the allowable correlation-error up to 7-bit.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.2
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• pp.377-386
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• 2021

The A60 class deck penetration piece is a fire-resistant system installed on a horizontal compartment to prevent flame spreading and protect lives in fire accidents in ships and offshore plants. This study deals with approximate optimization using discrete variables for the fire resistance design of an A60 class deck penetration piece using different surrogate models and a genetic algorithm. Transient heat transfer analysis was performed to evaluate the fire resistance design of the A60 class deck penetration piece. For the approximate optimization of the piece, the length, diameter, material type, and insulation density were applied to discrete design variables, and temperature, productivity, and cost constraints were considered. The approximate optimum design problem based on the surrogate models was formulated such that the discrete design variables were determined by minimizing the weight of the piece subjected to the constraints. The surrogate models used in the approximate optimization were the response surface model, Kriging model, and radial basis function-based neural network. The approximate optimization results were compared with the actual analysis results in terms of approximate accuracy. The radial basis function-based neural network showed the most accurate optimum design results for the fire resistance design of the A60 class deck penetration piece.

• Korean Journal of Plant Tissue Culture
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• v.25 no.2
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• pp.125-129
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• 1998

Cucumber (Cucumis sativus L.) plants were regenerated through organogenesis and somatic embryogenesis in cotyledon and hypocotyl cultures. The shoots were efficiently formed on the basal region of cotyledons cultured on MS medium containing 1.0㎎/L zeatin and 0.1㎎/L IAA in all cultivars used. Embryogenic calli were formed on hypocotyl segments cultured on MS medium containing 1.0㎎/L 2,4-D in cv. group 'Nakhab' and maintained by consecutive subculture on the same medium every 2-3 weeks without loss of embryogenic ability. Upon transfer to MS basal medium, high frequency somatic embryogenesis was achieved easily from embryogenic callus. Regenerated plantlets through organogenesis and somatic embryogenesis were transplanted to pots and gradually acclimatized to greenhouse condition where they subsequently produced fruits.