• 방송공학회논문지
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• 제21권2호
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• pp.219-236
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• 2016

본 논문에서는 High Efficiency Video Coding(HEVC)의 확장 표준인 Scalable HEVC(SHVC)와 3D-HEVC을 통합하여 구성되는 3차원 스케일러블 비디오 코덱을 제안한다. 제안하는 3차원 스케일러블 비디오 코덱은 다시점 영상을 부호화함과 동시에 공간해상도 스케일러빌리티 기능을 지원할 수 있도록 설계하였다. 이를 위해서, 다양 종류의 스케일러빌리티를 지원할 수 있는 High Level Syntax를 사용하였고, DPB 및 참조영상 리스트 구성 방법에 대한 알고리즘을 제안하였다. 본 논문의 컴퓨터 시뮬레이션 장에서는 제안하는 3차원 스케일러블 코덱의 정합성을 확인하였고, 또한, 제안 코덱의 부호화 성능을 분석하였다.

• 전력전자학회논문지
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• 제22권5호
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• pp.423-430
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• 2017

This paper proposes a control methodology for a high efficiency operation of an inductive power transfer (IPT) converter by combining full bridge (FB) and half bridge (HB) controls. To apply the proposed control to the IPT converter, the characteristics of each control method are analyzed. By examining the output voltages of the IPT converter and a theoretical loss analysis, the control shifting points between FB and HB controls are evaluated in accordance with the coupling coefficients and the load. Based on the control shifting points, the FB-HB control algorithm is implemented. By applying FB-HB control, high efficiency operation at the light load condition can be achieved.

• Structural Engineering and Mechanics
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• 제83권3호
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• pp.293-304
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• 2022

In this work, a novel reliability approach for combined high and low cycle fatigue (CCF) estimation is developed by combining active learning strategy with least squares support vector machines (LS-SVM) (named as ALS-SVM) surrogate model to address the multi-resources uncertainties, including working loads, material properties and model itself. Initially, a new active learner function combining LS-SVM approach with Monte Carlo simulation (MCS) is presented to improve computational efficiency with fewer calls to the performance function. To consider the uncertainty of surrogate model at candidate sample points, the learning function employs k-fold cross validation method and introduces the predicted variance to sequentially select sampling. Following that, low cycle fatigue (LCF) loads and high cycle fatigue (HCF) loads are firstly estimated based on the training samples extracted from finite element (FE) simulations, and their simulated responses together with the sample points of model parameters in Coffin-Manson formula are selected as the MC samples to establish ALS-SVM model. In this analysis, the MC samples are substituted to predict the CCF reliability of turbine blades by using the built ALS-SVM model. Through the comparison of the two approaches, it is indicated that the reliability model by linear cumulative damage rule provides a non-conservative result compared with that by the proposed one. In addition, the results demonstrate that ALS-SVM is an effective analysis method holding high computational efficiency with small training samples to gain accurate fatigue reliability.

• 대한전자공학회논문지TC
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• 제49권2호
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• pp.72-75
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• 2012

본 논문에서는 무선전력전송을 위한 고효율 DC-AC 변환 회로를 구현하였다. DC-AC 변환 회로는 발진기와 전력증폭기를 결합시켜 구현하였다. 전력증폭기의 전력 효율은 무선전력전송 송신 시스템의 효율에 크게 영향을 주기 때문에 Class-E 증폭구조를 이용하여 고효율 전력증폭기를 구현하였다. 또한, 전력증폭기의 입력 단에 연결되는 발진기의 출력 전력이 작기 때문에 높은 출력의 DC-AC 변환 회로를 구현하기 위하여 구동 증폭기를 이용한 고이득 이단 전력증폭기를 구현하였다. 고이득 고효율 이단 Class-E 전력증폭기의 입력 단에 발진기를 연결하여 고효율 DC-AC 변환 회로를 구현하였다. 13.56MHz의 2차, 3차 고조파 성분을 억제하기 위해 이중대역 저지 필터를 설계하여 결합하였다. DC-AC 변환 회로의 출력 전력과 변환 효율은 13.56 MHz에서 40 dBm과 80.2 %이다.

• Asia pacific journal of information systems
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• 제1권1호
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• pp.117-145
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• 1991

IS changeback is regarded as an offective way to control the usage of computers and communication systems which are very much limited resources and whose costs are very high, In this paper, the problem of combining the optimal chargeback system which guarantees the efficiency with the Rawls'(1971) concept of fairness. Primary conclusion of this paper is that if the value function which represents the contributions of IS user to the firm's profit is evidit and there is no uncertainty about this contribution information, optimality can be achived without any loss of fairness using full cost allocation pricing. But if there is no significant differences among contribution of each user and there is no significant differences among users because of the managerial arbitrariness, From this point of view contingent chargeback system with which manager can find the golden middle between optimality and fairness by adjusting the 'efficiency coefficient' according to his/her organizational characterisics and environments is proposed. A heuristic of finding the appropriate efficiency coefficient is also suggested.

• 한국전자파학회논문지
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• 제28권5호
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• pp.400-409
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• 2017

고주파 대역에서 삽입 손실을 최소화 하면서 고출력을 견딜 수 있는 결합기에 대해서 연구하였다. 특히, Ku 대역 이상에서는 단위소자 당 낼 수 있는 출력 전력이 저주파 대역에 비해 매우 낮기 때문에, 고출력 SSPA를 만들기 위해서는 많은 반도체 소자를 결합해야만 한다. 마이크로스트립과 같은 평면 결합기는 결합하는 소자의 개수가 증가하면 비례적으로 삽입 손실이 증가하여 전체 시스템 효율이 떨어지고 발열량도 높아지게 된다. 또한 평면 결합기는 낮은 전력 내구성에 따른 문제도 가지고 있다. 이러한 문제점들을 개선하고자 본 논문에서는 cavity radial combiner를 제안하였다. Ku 대역 16-way cavity radial combiner를 제작하여 측정한 결과, 설계 대역에서 반사손실 14 dB 이하, 94.5 % 이상의 출력결합 효율을 얻었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권10호
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• pp.4231-4245
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• 2020

Non-orthogonal multiple access (NOMA) is widely studied in both academia and industry due to its high spectral efficiency over orthogonal multiple access (OMA). To effectively improve spectrum efficiency, an amplify-and-forward (AF) cooperative NOMA system is proposed as well as a novel detection scheme is proposed, in which we first perform successive interference cancellation (SIC) twice at U1 for the two signals received from two time slots to remove interference from symbol 2, then two new signals apply max ratio combining (MRC). In addition, a closed-form upper bound approximation for the ergodic capacity of our proposed system is derived. Monte-Carlo simulations and numerical analysis illustrate that our proposed system has better ergodic capacity performance than the conventional cooperative NOMA system with decode-forward (DF) relay, the conventional cooperative NOMA system with AF relay and the proposed AF cooperative NOMA system in [16]. In addition, we can see that ergodic capacity of all NOMA cooperative systems increase with the increase of transmit SNR. Finally, simulations display that power allocation coefficients have little effect on ergodic capacity of all NOMA cooperative systems. This is due to this fact that ergodic capacity of two symbols can be complementary with changing of power allocation coefficients.

• 기술혁신연구
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• 제13권2호
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• pp.207-222
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• 2005

A prerequisite for making R&D more productive is to able to measure its productivity. Most of the previous studies on this topic have attempted to measure R&D productivity at the firm or industry levels. In this study, however, R&D productivity is measured at the national level to provide R&D policy implications, particularly for Asian countries. Contrary to the previous studies where total factor productivity was adopted, this study employs the data envelopment analysis (DEA) approach to measure R&D productivity. DEA is a multi-factor productivity analysis model for measuring the relative efficiency of each Decision Making Unit (DMU). In addition to the basic DEA model that includes all inputs and outputs, five additional models are constructed by combining single input with all outputs and single output with all inputs in order to measure specialized R&D efficiency. In this study, the twenty-seven countries are classified into four clusters based on the output-specialized R&D efficiency: inventors, merchandisers, academicians, and duds. Then, the characteristics of the Asian countries with respect to R&D efficiency are identified. It is found that Singapore ranks high in total efficiency, and Japan in patent-oriented efficiency. Meanwhile, China, Korea, and Taiwan are found to be relatively inefficient in R&D. We expect that the findings from this study will be able to provide directions for R&D policy-making of the Asian countries.

• 대한산업공학회지
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• 제40권2호
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• pp.172-183
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• 2014

This paper measures and compares the efficiency of national health technology R&D programs focused on translational research program increasing importance using data envelopment analysis (DEA). Three input variables and three output variables are selected for DEA. Inputs are funds, researchers, and project period and outputs are SCI (E) papers, applied and granted patents, and impact factor. This study uses a three-stage approach. In the first stage, output-based DEA model is applied to evaluate the efficiency of decision making unit (DMU). In the second stage, based on efficiency scores of target diseases high-efficiency group and low-efficiency group are classified. And then strategic portfolio matrix of translational research program is composed of four dimensions combining research types. Mann-Whitney U test is then run to compare average efficiency scores among four groups. In the final stage, Tobit regression model is used to estimate factors likely to influence the efficiency. The results are expected to provide policy implications for effectively establishing investment strategy and managing performance of R&D program.

• 한국기계가공학회지
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• 제17권1호
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• pp.1-7
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• 2018

We aimed to develop a high quality 3.5 ton class swing reducer by studying the efficiency improvement of the reducer through the optimum design and performance evaluation of the assembled, high efficiency, lightweight 3.5 ton swing reducer. Based on the optimal design of the worm and worm wheel, the optimal manufacturing method of the worm wheel, the optimized casing design, and the optimum design of the output pinion, Respectively. Therefore, in this paper, to improve the efficiency of the worm gear reducer system, we will develop the manufacturing technology and verify the mass production by combining the manufacturing process design, processing and assembling technology according to the optimization design. We have conducted research to realize mass production by product verification such as product efficiency, reliability and durability according to optimal design of worm gear reducer.