• Journal of Power Electronics
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• 제17권1호
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• pp.136-148
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• 2017

In recent years, voltage source multilevel converters are very popular in medium/high-voltage industrial applications, among which the NPC/H-Bridge converter is a popular solution to the medium/high-voltage drive systems. The conventional finite control set model predictive control (FCS-MPC) strategy is not practical for multilevel converters due to their substantial calculation requirements, especially under high number of voltage levels. To solve this problem, a hierarchical model predictive voltage control (HMPVC) strategy with referring to the implementation of g-h coordinate space vector modulation (SVM) is proposed. By the hierarchical structure of different cost functions, load currents can be controlled well and common mode voltage can be maintained at low values. The proposed strategy could be easily expanded to the systems with high number of voltage levels while the amount of required calculation is significantly reduced and the advantages of the conventional FCS-MPC strategy are reserved. In addition, a HMPVC-based field oriented control scheme is applied to a drive system with the NPC/H-Bridge converter. Both steady-state and transient performances are evaluated by simulations and experiments with a down-scaled NPC/H-Bridge converter prototype under various conditions, which validate the proposed HMPVC strategy.

• 환경생물
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• 제31권4호
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• pp.233-242
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• 2013

Cyanobacteria (blue-green algae) are not only the first oxygenic organisms on earth but also the foremost primary producers in aquatic environment. Massive growth of cyanobacteria, in eutrophic waters, usually changes the water colour to green and is called as algal (cyanobacterial) bloom or green tide. Cyanobacterial blooms are a result of high levels of primary production by certain species such as Microcystis sp., Anabaena sp., Oscillatoria sp., Aphanizomenon sp. and Phormidium sp. These cyanobacterial species can produce hepatotoxins or neurotoxins as well as malodorous compounds like geosmin and 2-methylisoborneol (MIB). In order to solve the nationwide problem of hazardous cyanobacterial blooms in Korea, the following technically and strategically sound approaches need to be developed. 1) As a long-term strategy, reduction of the nutrients such as phosphorus and nitrogen in our water bodies to below permitted levels. 2) As a short term strategy, field application of combination of already established bloom remediation techniques. 3) Development of emerging convergence technologies based on information and communication technology (ICT), environmental technology (ET) and biotechnology (BT). 4) Finally, strengthening education and creating awareness among students, public and industry for effective reduction of pollution discharge. Considering their ecological roles, a complete elimination of cyanobacteria is not desirable. Hence a holistic approach mentioned above in combination to addressing the issue from a social perspective with cooperation from public, government, industry, academic and research institutions is more pragmatic and desirable management strategy.

• Journal of Power Electronics
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• 제9권5호
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• pp.736-747
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• 2009

A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.

• 무역상무연구
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• 제67권
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• pp.187-208
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• 2015

The Korea China FTA was signed on June 1 2015. It includes some concessions regarding major export items in the manufacturing sector for the protection of primary industries and preferential tariffs for a number of products produced in the Kaesong Industrial Complex. Primary industries are what the Korean government paid the greatest attention to. Rice was excluded from the negotiations from the get go, and was joined by 548 other food items including pork, apples, pears, beef, chili, garlic etc. These foodstuffs account for about one-third of the agricultural and livestock products that Korea produces, and are not going to be subject to tariff elimination. The results of the study are as follows: Korean government policy is to maintain of agri-food export support system, eliminate of agri-food non-tariff barriers, foster of agri-food export SMEs and expand of investment of foreign agri-food company. Korean firms strategy is to establish of regional marketing strategy, ensure of high quality agri-food and develop of food packaging technologies, establish of agri-food export logistics center and take advantage of the FTA preferential tariff.

• Journal of Power Electronics
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• 제18권2호
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• pp.445-455
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• 2018

A novel algorithm is proposed to regulate the neutral point potential in neutral point clamped three-level inverters. Oscillations of the neutral point potential and an unbalanced dc-link voltage cause distortions of the output voltage. Large capacitors, which make the application costly and bulky, are needed to eliminate oscillations. Thus, the algorithm proposed in this paper utilizes the finite-control-set model predictive control and the multistage medium vector to solve these issues. The proposed strategy consists of a two-step prediction and a cost function to evaluate the selected multistage medium vector. Unlike the virtual vector method, the multistage medium vector is a mixture of the virtual vector and the original vector. In addition, its amplitude is variable. The neutral point current generated by it can be used to adjust the neutral point potential. When compared with the virtual vector method, the multistage medium vector contributes to decreasing the regulation time when the modulation index is high. The vectors are rearranged to cope with the variable switching frequency of the model predictive control. Simulation and experimental results verify the validity of the proposed strategy.

• Genomics & Informatics
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• 제7권4호
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• pp.181-186
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• 2009

Myotonic dystrophy type 1 (DM1), which is a dominantly inherited neurodegenerative disorder, results from a CTG trinucleotide repeat expansion in the 3'-untranslated region (3'-UTR) of the myotonic dystrophy protein kinase (DMPK) gene. Retention of mutant DMPK (mDMPK) transcripts in the nuclei of affected cells has been known to be the main cause of pathogenesis of the disease. Thus, reducing the RNA toxicity through elimination of the mutant RNA has been suggested as one therapeutic strategy against DM1. In this study, we suggested RNA replacement with a trans -splicing ribozyme as an alternate genetic therapeutic approach for amelioration of DM1. To this end, we identified the regions of mDMPK 3'-UTR RNA that were accessible to ribozymes by using an RNA mapping strategy based on a trans-splicing ribozyme library. We found that particularly accessible sites were present not only upstream but also downstream of the expanded repeat sequence. Repair or replacement of the mDMPK transcript with the specific ribozyme will be useful for DM1 treatment through reduction of toxic mutant transcripts and simultaneously restore wild-type DMPK or release nucleus-entrapped mDMPK transcripts to the cytoplasm.

• 경영과정보연구
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• 제30권2호
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• pp.211-235
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• 2011

본 연구의 목적은 R&D 혁신역량의 구성요소가 기업성과에 미치는 영향을 분석하고자 하는데 있다. 그리고 지역산업에 있어서 전략산업의 비중을 감안하여 전략산업과 비전략산업 간에 비교분석을 하고자 하였다. 주요 분석결과를 요약하면 다음과 같다. 첫째, 전략산업과 비전략산업 간의 차이분석 결과를 보면 CEO 기술혁신의지를 제외한 모든 R&D 혁신역량 부문에 있어서 전략산업이 유의적으로 높게 나타났다. 기업성과에 있어서는 비유의적이지만 전략산업의 기업성과가 높게 나타났다. 둘째, 전략산업 간 차이분석을 한 결과를 보면 기업성과에 있어서 유의적인 차이를 보였다. 총자산순이익률의 경우 메카트로닉스와 전자정보기기산업이 가장높게 나타났고, 매출액성장률에서는 전자정보기기산업이 가장 높았다. R&D투입에 있어서 연구개발투자인력은 전자정보기기산업이 그리고 석 박사연구인력은 생물산업이 가장 높았고 모두 1% 유의수준에서 전략산업 간에 유의적인 차이를 보였다. R&D과정에 있어서는 기술혁신전략을 제외한 나머지 부분에서 전략산업 간 유의적인 차이가 있는 것으로 나타났고, 대부분에서 전기정보기기산업이 가장 높게 나타났다. R&D산출인 지적재산권 보유 정도에 있어서도 전자정보기기산업이 6.75건으로 가장 높았다. 셋째, 모든 산업에 있어서 R&D 혁신역량이 기업성과에 동일하게 영향을 미치지는 않고 있다는 점이다. 그리고 일반적으로 R&D투입이 기업성과에 양(+)의 영향을 미친다는 것과는 달리 석 박사연구인력과 같이 연구개발인력의 질이 더 유의적으로 영향을 미치는 것으로 나타났다. 부분적이지만 R&D성과 보다는 R&D과정이 더 기업성과에 영향을 미칠 수 있는 R&D 혁신역량이라는 점을 함께 발견할 수 있었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.251-253
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• 2006

Speed and torque controls of permanent magnet synchronous motors are usually attained by the application of position and speed sensors. However, speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of a motor. Therefore, many studies have been performed for the elimination of speed and position sensors. This paper investigates a novel sensorless control of a permanent magnet synchronous motor. The proposed control strategy utilizes the active and reactive torque control for maximizing the active torque of a sensorless PMSM. The proposed algorithm is verified through the simulation and experimentation.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권3호
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• pp.124-130
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• 1999

Speed and position sensors require the additional mounting space, reduce the reliability in harsh environments and increase the cost of motor. Various control algorithms have been proposed for the elimination of speed senor. This paper investigates a novel speed sensorless control of induction motor. The proposed control strategy is based on MRAS(Model Reference Adaptive System) using state observer as a reference model for flux estimation. This algorithm may overcome several shortages of conventional MRAS: integrator problems, small EMF at low speed and relatively large sensitivity to resistance variation. The proposed algorithm is verified through simulation and experiment.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1996년도 창립기념 전력전자학술발표회 논문집
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• pp.103-108
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• 1996

In this paper, a novel utility connected photovoltaic power generation system with unity power factor and uninterruptable power system facility and its control strategy are proposed. The proposed photovoltaic(PV) system is connected in parallel between utility and load. The PV system provides an uninterruptable voltage to load, a maximum power tracking to solar array, and power factor correction to the utility. The proposed system has the following advantages compared with the conventional utility connected PV system. 1. Harmonic elimination Function 2. Feeding the photovoltaic energy to the utility 3. Providing the uninterruptible power source along battery to the load In case that the photovoltaic array system is on the poor power generation, the battery and capacitor of the PV system are charged by three phase utility source and the inverter in the PV system only provides the reactive current to eliminate the harmonic current exited on the utility. In the normal operation mode, the PV system supplies active power to load and reactive power to utility in order to maintain the unity power factor and to regulate ac load voltage.