• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.117-123
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• 2013

By calculating the spectral efficiency of symmetric balance incomplete block design(BIBD) codes satisfying BER=$10^{-9}$, it can be found that ideal BIBD code design with m=2 and various q's is effective when effective power is high($P_{sr}=-10$ dBm). But BIBD code design with q > 2 and various m's can be effective when effective power is low($P_{sr}=-25$ dBm).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.53-61
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• 2014

In this paper, we present the design, fabrication and measurement of high efficiency GaN HEMT power amplifier using harmonic matching technique. In order to achieve high efficiency, harmonic load-pull simulation is performed, that is, the optimum load impedances are determined at $2^{nd}$ and $3^{rd}$ harmonic frequencies as well as at the fundamental. Then, the output matching circuit is designed based on harmonic load-pull simulation. The measurement of the fabricated power amplifier shows the linear gain of 20 dB and $P_{1dB}$(1 dB gain compression point) of 33.7 dBm at 1.85 GHz. The maximum power added efficiency(PAE) of 80.9 % is achieved at the output power of 38.6 dBm, which belongs to best efficiency performance among the reported high efficiency power amplifiers. For W-CDMA input signal, the power amplifier shows a PAE of 27.8 % at the average output power of 28.4 dBm, where an ACLR (Adjacent Channel Leakage Ratio) is measured to be -38.8 dBc. Digital predistortion using polynomial fitting was implemented to linearize the power amplifiers, which allowed about 6.2 dB improvement of an ACLR performance.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.31-40
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• 2017

In this paper, we compared the efficiencies of national R&D investments between NT (Nanotechnology) areas in terms of papers, patents, and commercializations, and found ways to improve the efficiencies of national R&D investments for each NT area. This is in response to huge R&D investments government has made recently in NT areas. Here, we collected data on investments, papers, patents, and commercializations for the R&D projects in NT areas through National Science & Technology Information Service. Based on the data, we analyzed the investment and performances (papers, patents, and commercializations) for each NT area, calculated the efficiency for each NT area, and compared the efficiencies between NT areas. Next, using cluster analysis, we identified several NT areas with similar characteristics in terms of paper efficiency, patent efficiency and commercialization efficiency. Finally, we derived implications for the efficiency enhancement for each grouping. The cluster analysis showed that there could be two groups, one being low in terms of technological outcome (papers and patents) efficiencies and high in terms of commercialization efficiencies, while the other being high in terms of technological outcome (papers and patents) efficiencies and low in terms of commercialization efficiencies. Therefore, the strategy for one group calls for support for technology transfer or technology introduction from other R&D performers and grant of guidance for improving R&D performers' commercialization ability to other R&D performers while the strategy for the other group calls for R&D support for transfer of technology to other R&D performers, activation of technology transfer and support for commercialization of R&D performers.

• Journal of IKEEE
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• v.25 no.1
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• pp.133-138
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• 2021

We propose a Ku-band three-stack CMOS power amplifier to enhance the output power and efficiency. To minimize the dc power consumption, the driver stage is designed using common-source structure. To obtain high output power and utilize a voltage combining method, the power stage is designed using stack structure. To verify the proposed power amplifier structure, we design a Ku-band power amplifier using 65-nm RFCMOS process which provide nine metal layers. The P1dB, power-added efficiency, and gain are higher than 20 dBm, 23 dB, and 25%, respectively, while the operating frequency is 14 GHz-16 GHz.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.147-152
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• 1998

2-D flow fields are studied by using a shared memory parallel computer with a parallel flow analysis program which uses domain decomposition method and MPI library for data exchange at overlapped interface. Especially, effects of directional domain decomposition on parallel efficiency are studied for 2-D Lid-Driven cavity flow and flow through square cavity. It is known from the present study that domain decomposition along the main flow direction gives better parallel efficiency in 1-D partitioning than along the other direction. 2-D partitioning, however, is less sensitive to flow directions and gives good parallel efficiency for most of the cases considered.

• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.47-54
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• 2003

New efficiency enhancement techniques have been devised and implemented to InGaP/GaAs HBT MMIC power amplifiers for W-CDMA mobile terminals applications. Two different types of bias current control circuits that select the efficient quiescent currents in accordance with the required output power levels are proposed for overall power efficiency improvement. A dual chain power amplifier with single matching network composed of two different parallel-connected power amplifier is also introduced. With these efficiency enhancement techniques, the implemented MMIC power amplifiers presents power added efficiency (PAE) more than 14.8 % and adjacent channel leakage ratio(ACLR) lower than -39 dBc at 20 dBm output power and PAE more than 39.4% and ACLR lower than -33 dBc at 28 dBm output power. The average power usage efficiency of the power amplifier is improved by a factor of more than 1.415 with the bias current control circuits and even up to a factor of 3 with the dual chain power amplifier.

• Health Policy and Management
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• v.25 no.2
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• pp.97-106
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• 2015

Background & Methods: The purpose of this research is to estimate the efficiency of the pharmaceutical firms and the determinants of their efficiency. Stochastic frontier analysis(SFA) and panel study are applied to the data of 60 domestic pharmaceutical firms from 2006 to 2012. Results & Conclusion: First, the result of the stochastic frontier analysis shows that overall efficiency of the pharmaceutical firms is increasing as time goes by. However, if firms are classified by the scale, the larger firms show more efficiency and if classified by the degree of innovativeness, the innovative firms show more efficiency compared to the non-innovative firms. This evidences show that the scale and R&D investment have significant relationships with the efficiency of the pharmaceutical firms. Therefore, it is necessary to increase the national level of investment for the fundamental researches to vitalize R&D of the new drugs. Second, the result of estimation of the determinants of efficiency shows that the firms with larger sales promotion expenses and entertainment expenses have less efficiency compared to the other firms. This can be explained by the structural characteristics of the small generic pharmaceutical firms. Therefore, the government had better make the pharmaceutical firms to reduce sales promotion and entertainment expenses and increase R&D expenses by introducing systems such as global budgeting system on medicine or reference pricing system.

• Korean Management Science Review
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• v.34 no.2
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• pp.67-83
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• 2017

This paper proposes a R&D project performance measurement model for private firms combining balanced scorecard (BSC) and data envelopment analysis (DEA). The efficiency of R&D projects is measured in terms of each of the three perspectives of BSC by using DEA : the internal process perspective (DEA-P), the customer perspective (DEA-C), and the financial perspective (DEA-F). The performance indicators of the three perspectives of BSC are considered as outputs of the corresponding DEA models. To provide strategic implications for R&D planning, we also propose the R&D project performance matrices composed of two different types of efficiency dimensions. The proposed model is expected to be fruitfully utilized for R&D performance measurement of private firms.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.42-50
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• 2014

Korean government has been investing more than 400 billion KRW in R&D on renewable energy. This paper aims to measure the R&D efficiency of national R&D program in the field of renewable energy, and to identify the sources of inefficiency. 4,213 R&D projects supported by Korean government during 2009-2011 are analyzed by using Data Envelopment Analysis and statistical tests. Results implies as follows. First, hydrogen, bio, fuel cell, photovoltaic have higher R&D efficiency than other renewable energies. Second, universities conducted national R&D program more efficiently than firms did, and small and medium sized enterprises are more efficient than large sized enterprises. Third, R&D inefficiency is mainly caused by the lacks of patent performance rather than excessive R&D investment or academic paper performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.4
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• pp.1837-1860
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• 2020

We propose a general framework for studying resource allocation problem and the tradeoff between spectral efficiency (SE) and energy efficiency (EE) for downlink traffic in power domain-non-orthogonal multiple access (PD-NOMA) and device to device (D2D) based heterogeneous cloud radio access networks (H-CRANs) under imperfect channel state information (CSI). The aim is jointly optimize radio remote head (RRH) selection, spectrum allocation and power control, which is formulated as a multi-objective optimization (MOO) problem that can be solved with weighted Tchebycheff method. We propose a low-complexity algorithm to solve user association, spectrum allocation and power coordination separately. We first compute the CSI for RRHs. Then we study allocating the cell users (CUs) and D2D groups to different subchannels by constructing a bipartite graph and Hungrarian algorithm. To solve the power control and EE-SE tradeoff problems, we decompose the target function into two subproblems. Then, we utilize successive convex program approach to lower the computational complexity. Moreover, we use Lagrangian method and KKT conditions to find the global optimum with low complexity, and get a fast convergence by subgradient method. Numerical simulation results demonstrate that by using PD-NOMA technique and H-CRAN with D2D communications, the system gets good EE-SE tradeoff performance.