• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1083-1095
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• 2023

Recently, the demand for low-voltage, high-capacity ESS is rapidly increasing due to the revitalization of the e-mobility industry, which is mainly powered by electricity. In addition, the demand for portable power banks is rapidly increasing due to the revitalization of leisure industries such as camping and fishing. The ESS with this structure consists of a small number of series cells and many parallel cells, resulting in a system with a large rated current. Therefore, the number of power devices for cell balancing configured in series is small, but a balancing device with a large current capacity is required. Construction of a constant temperature device in such a low-voltage, high-current ESS is difficult due to economic issues. The demand for an active balancing system that can solve the passive balancing heating problem is rapidly increasing. In this paper, propose a power feedback fly-back topology that can solve the balancing heating problem. The characteristic of the proposed topology is that a series-connected voltage sharing voltage is used as the input of the flyback converter, and the converter output is connected to one transformer. In this structure, the converter output for cell voltage balancing shares magnetic flux through one high-frequency transformer, so the cell voltage connected to the converter automatically converges to the same voltage.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.67-75
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• 2011

The development of electric vehicle power electronics system control, composed of DC-AC inverters and DC-DC converters, attract much research interest in the modern industry. A DC-AC inverter supplies the high-power motor torques of the propulsion system and utility loads of electric vehicles, whereas a DC-DC converter supplies the conventional low-power and low-voltage loads. However, the need for high-power bidirectional DC-DC converters in future electric vehicles has led to the development of many new topologies of DC-DC converters. The nonlinear control of power converters is an active research area in the field of power electronics. This paper focuses on the use of the fuzzy sliding mode strategy as a control strategy for buck-boost DC-DC converter power supplies in electric vehicles. The proposed fuzzy controller specifies changes in control signals based on the surface and knowledge on surface changes to satisfy the sliding mode stability and attraction conditions. The performance of the proposed fuzzy sliding controller is compared to that of the classical sliding mode controller. The satisfactory simulation results show the efficiency of the proposed control law, which reduces the chattering phenomenon. Moreover, the obtained results prove the robustness of the proposed control law against variations in load resistance and input voltage in the studied converter.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.171-179
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• 2010

Effective monitoring and maintenance operation of towers, power lines and other defects to ensure high quality and reliability of electric power supplied to customers is becoming one of the most important tasks of today's power industry. One specific technology that has the potential to automate the entire surveillance process is unmanned aerial vehicles. In this paper, we propose a new power line extraction method using the directivity of a power line and Hough transform to detect efficiently power lines from thermal aerial images. In simulation results for several aerial images, the proposed method shows good performance in extracting power line detection.

• Journal of Korea Trade
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• v.27 no.1
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• pp.79-100
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• 2023

Purpose - The purpose of this study is to analyze the market power of the Korea Container Shipping Market (Intra Asia, Korea-Europe, and Korea-U.S.) to verify the existence of collusion empirically, and to answer whether the joint actions of liner market participants in Korea have formed market dominance for each route. Precisely, it will be verified through the Lerner index as to whether the regional market of Asia is a monopoly, oligopoly, or perfect competition. Design/methodology - This study used a Lerner index adjusted with elasticity presented in the New Imperial Organization (NEIO) studies. NEIO refers to a series of empirical studies that estimate parameters to judge market power from industrial data. This study uses B-L empirical models by Bresnahan (1982) and Lau (1982). In addition, NEIO research data statistically contain self-regression and stability problems as price and time series data. A dynamic model following Steen and Salvanes' Error Correction Model was used to solve this problem. Findings - The empirical results are as follows. First, λ, representing market power, is nearly zero in all three markets. Second, the Korean shipping market shows low demand elasticity on average. Nevertheless, the markup is low, a characteristic that is difficult to see in other industries. Third, the Korean shipping market generally remains close to perfect competition from 2014 to 2022, but extreme market power appears in a specific period, such as COVID-19. Fourth, there was no market power in the Intra Asia market from 2008 to 2014. Originality/value - Doubts about perfect competition in the liner market continued, but there were few empirical cases. This paper confirmed that the Korea liner market is a perfect competition market. This paper is the first to implement dynamics using ECM and recursive regression to demonstrate market power in the Korean liner market by dividing the shipping market into Deep Sea and Intra Asia separately. It is also the first to prove the most controversial problems in the current shipping industry numerically and academically.

• The Journal of the Korea Contents Association
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• v.10 no.4
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• pp.292-297
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• 2010

The Economic region, the strategy for regional development, is a global trend and has become the blue ocean. Korea has also moved forward with the concept of economic region as the strategy for regional development. So, The main purpose of this study is to find the strategies to improve the regional R&D competitive power and making regional R&D support system. As a goal of regional innovation and regional economic development, the business adds new jobs and new products, resulting in growth of the community.

• Korean Chemical Engineering Research
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• v.49 no.4
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• pp.432-437
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• 2011

Recently, industry needs a new design of Czochralski(Cz) process for higher productivity with reasonable energy consumption. In this study, we carried out computational simulations for finding out a new optimal design of Cz process with variables which can be applied in real industry such as location of heater, shape of shield and crucible size. Objective process was Cz process which can be produced 8 inch diameter Si ingot for solar cell and we acquired an optimal design for higher productivity, low power consumption with stable production condition. For higher productivity we also change the crucible diameter from 22 inches to 24 inches with changing insulation thickness only because the process housing size could not be changed in industry.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.1
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• pp.55-60
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• 2022

This study conducted the measurements of air flow rate for blower systems with experiment and numerical. A new airflow rate test method is suggested, with which it is possible to accurate measurements and calculate the air flow rate for blower systems. The blower(axial fan) is an industrial fluid machine device that supplies a large amount of air by driving an impeller with an electric motor, and it is widely used throughout the industry such as steel, power plant, chemical, semiconductor, LC D, food, and cement. The airflow from the blower is for exchanging the heat in the cooling unit or heat exchanger. The temperature of coolants and hydraulic oil primarily depends on the amount of airflow rate through the cooling package so its accurate estimation is very important. Moreover, it required a larger investment in time and cost since it could not be executed until the system is actually made. Therefore, this research is intended to examine the phenomenon of air flow pattern when testing air flow rate, suggested new test method, and show the result of the validation test.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.5
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• pp.106-116
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• 2008

21 century is as time of infinite competition the knowledge base society where the creation knowledge and information become source of competitive power (Knowledge-based society) and the world-wide various nations leads and knowledge intensification of voice and existing industry of knowledge industry leadership grasp of competitive power high position security and world economy it concentrates a hazard national ability from new economic environment inside. Also, world economy the economic border collapsed with opening anger liberalization and the integration of world economy was accelerated and the restraint of advanced nation, pursuit of the late start developing country and competition from the enterprise for strategy helping each other back international market more were aggravating and information and knowledge with production element or the goods were wide in the economic whole and information knowledge revolution which circulates was developed and it followed hereupon and with the vitality where the knowledge base industry growth is new it rose to the surface.

• New & Renewable Energy
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• v.18 no.3
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• pp.1-9
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• 2022

This study analyzed the anticipated supply-and-demand of forest biomass energy (through wood pellets) until 2050, in South Korea. Comparing the utilization rates of forest resources of five countries (United Kingdom, Germany, Finland, Japan, and S. Korea), it was found that S. Korea does not nearly utilize its forest resources for energy purposes. The total demand for wood pellets in S. Korea (based on a power generation efficiency of 38%) was predicted to be 3,629 and 4,371 thousand tons in 2034 and 2050, respectively. The anticipated total wood pellet power generation ratio to target power consumption is 1.13% (5,745 GWh), 1.17% (6,336 GWh), and 1.25% (7,631 GWh) in 2020, 2030, and 2050, respectively. Low value-added forest residues left unattended in forests are called "Unused Forest Biomass" in S. Korea. From the analysis, the total annual potential amount of raw material, sustainably collectible amount, and available amount of wood pellet in 2050 were estimated to be 6,877, 4,814, and 3,370 thousand tons, respectively. The rate of contribution to Nationally Determined Contributions was up to 0.64%. Through this study, the authors found that forest biomass energy will contribute to a carbon neutral society in the near future at the national level.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.515_516
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• 2009

최근 배전계통에 연계되고 있는 신에너지전원의 용량은 점차 증가하고 있는 상황이지만, 설치자(신에너지전원 소유자)의 보호방식은 기존 방식을 고수하고 있는 실정으로 분산전원의 역 조류에 의해 설치자의 보호기기(자동화기기 포함)의 오 부 동작 발생 가능성이 커지고 있다. 본 논문에서는 신에너지전원이 배전계통에 연계되어 운전되는 경우에 발생 가능한 보호협조의 문제점을 분석한다.