• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.379-386
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• 2009

This paper investigates the operation of ITER(International Thermonuclear Experimental Reactor) Vertical Stabilization(VS) converter with circulating current. The VS converter has two subunits in parallel. The subunit is composed two back-to-back 12 pulse thyristor converter in series. The circulating current free technique can not always maintain the closed path for the load current because of a dead time zone of the converter operation at the region of the load current inversion. The complex circulation current technique for the load current inversion with VS converter can achieve the fast response and always maintain the closed path for the load curret. The paper proposes the new circulating current algorithm for the load current inversion of ITER VS converter and proves the performance of the circulating current technique with PSIM simulation study.

• Journal of Power Electronics
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• v.13 no.6
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• pp.964-974
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• 2013

A modified direct torque control (DTC) method based on torque angle is proposed for interior permanent-magnet synchronous motor (IPMSM) drivers used in electric vehicles (EVs). Given the close relationship between torque and torque angle, proper voltage vectors are selected by the proposed DTC method to change the torque angle rapidly and regulate the torque quickly. The amplitude and angle of the voltage vectors are determined by the torque loop and stator flux-linkage loop, respectively, with the help of the position of the stator flux linkage. Furthermore, to satisfy the torque performance request of EVs, the nonlinear dead-time of the invertor caused by parasitic capacitances is considered and compensated to improve steady torque performance. The stable operation region of the IPMSM DTC driver for voltage and current limits is investigated for reliability. The experimental results prove that the proposed DTC has good torque performance with a brief control structure.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.3
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• pp.85-92
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• 2005

Due to the friction characteristic of pump, cylinder, and between passenger car and the rail, there exist dead zone in the hydraulic system actuated with inverter, which can not be controlled by a PID controller. In this paper, the friction characteristic of a cylinder is considered first, which may cause the uncontrolled speed in the zero-crossing speed region. And then, the zooming fuzzy logic controller is designed to overcome the drawback by the existing PID speed controller. Finally, The proposed hybrid fuzzy controller is applied to the PID controller in the normal speed region and to the fuzzy controller in the zero-crossing speed region. The reason is that the problem of the uncontrolled speed in the zero-crossing speed region caused by the friction characteristic of the cylinder in hydraulic elevator can be solved, and the effectiveness of the controlling system not only in the zero-crossing speed region but also the overall controlling region including steady-state can be simulated and performed.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.3
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• pp.218-226
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• 2003

Due to the friction characteristics of pump, cylinder packing and passenger car, in the elevation system actuated with hydraulic inverter, there exist dead zones. which cannot be controlled by a PID controller. To overcome the drawbacks, in this paper, we propose a new hybrid fuzzy-sliding mode control scheme, which controls the controller output between a sliding mode control output and a PID control output by fuzzy control method. The proposed hybrid control scheme achieves an improved control performance by using both controllers. We first propose a design method of the hybrid controller far a hydraulic system controlled by inverters, then propose a design method of a hybrid fuzzy-sliding mode centre] scheme. The effectiveness of the proposed control scheme is shown by simulation results, in which the proposed hybrid control method yields better control performance then the PID controlled scheme, not only in the zero-crossing speed region but also in the overall control region including steady-state region.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.83-90
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• 2009

Natural disasters, such as the recent floods in the Midwest, Hurricane Ike in the Gulf coast region (U.S.), and the earthquake in Sichuan (China), cause severe damage to the infrastructure as well as the associated industries and communities that rely on the infrastructure. The estimated damages due to Hurricane Ike in 2008 were a staggering $27 billion, the third worst in U.S. history. In addition, the worst earthquake in three decades in Sichuan resulted in about 90,000 people dead or missing and $20 billion of the estimated loss. A common observation in the analyses of these natural disaster events is the inadequacy of critical infrastructure to withstand the forces of natural calamities and the lack of mitigation strategies when they occur on the part of emergency-related organizations, industries, and communities. If the emergency-related agencies could identify and fortify the vulnerable critical infrastructure in the preparedness stage, the damage and impacts can be significantly reduced. Therefore, it is important to develop a decision support system (DSS) for identifying region-specific mitigation strategies based on the inter-relationships between the infrastructure and associated industries and communities in the affected region. To establish effective mitigation strategies, relevant data were collected from the affected areas with respect to the technical, social, and economic impact levels. The data analysis facilitated identifying the major factors, such as vulnerability, criticality, and severity, for developing a DSS. Customized mitigation strategies that will help agencies prepare, respond, and recover according to the disaster response were suggested.

• Journal of the Korean Society of Costume
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• v.66 no.6
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• pp.67-78
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• 2016

Research on ancient Indonesian 'sacred cloths' is essential since it shows a different perspective into Indonesian identity. Based on its function, the 'sacred cloths' are either made as a medium for religious ceremonies or as a medium for the living and the dead. The consuetude of preparing and creating the 'sacred cloths' are done to achieve the finest 'sacred cloths' worthy to be presented to God. The research aims to analyze the characteristics of ancient Indonesian textiles and to focus on the 'sacred cloths.' The research is divided into two parts, and this paper is the first part. The paper analyzes the characteristics of ancient Indonesian textiles by focusing on the period, religion, region, and color of the 'sacred cloths.' The subsequent research analyzes the characteristics of ancient Indonesian textiles by focusing on the techniques and the patterns of the 'sacred cloths.' In this first part of the main research, the analysis reveals that animism developed in various ways in Indonesia from 500 BC to AD 1800. It was also as kingdoms of Buddhist, Hinduism, and Islam. The changes of religion may differ according to its region. Indonesian regions are divided into six big regions that produce textiles. These islands are Sumatra, Borneo, Java, Celebes, Nusa Tenggara, and Bali. By space and time, the colors of Indonesian textiles represent the ideology of one religion. Indonesia produces primary colors of red, yellow, and blue(RYB). The colors are produced by extracting leaves of Indigo, Indian Mulberry root shell, Sappanwood's branches, Candlenut fruit, Turmeric root, and Mangosteen rind. Indonesia is a religious country, therefore the meaning of creating each 'sacred cloth' shows piety of the maker and the wearer.

• The Transactions of the Korean Institute of Power Electronics
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• v.7 no.1
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• pp.55-64
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• 2002

Due to the friction characteristics of cylinders and the rail of a passenger car, in the system actuated with hydraulic systems, there exist dead zones, which can not be controlled by a PID controller. In this paper, the friction characteristics of a cylinder is examined, which may cause the abrupt increase of the acceleration in the zero-crossing speed region. To overcome the drawbacks of a PID controlled hydraulic system, a zooming fuzzy logic controller is designed and finally an improved hybrid controller is Proposed. The proposed controller is composed of the PID controller and the zooming fuzzy controller. The effectiveness of the proposed control scheme is shown by simulation and experimental results, In which the proposed hybrid control method yields good control performance not only in the zero-crossing speed region but also In the overall control region including steady-state region.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2352-2360
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• 2007

Due to the friction characteristics of cylinders and the rail of a passenger car, in the elevator actuated with hydraulic systems, there exist dead zones, which can not be controlled by a PID controller. In this paper, the friction characteristics of a cylinder is examined, which may cause the abrupt increase of the acceleration in the zero-costing speed region. To overcome the drawbacks of a PID controlled hydraulic elevator system, a zooming fuzzy logic controller is designed and finally an improved hybrid fuzzy controller is proposed. The effectiveness of the proposed control scheme are shown by simulation and experimental results, which the proposed fuzzy hybrid control method yields good control performance not only in the zero-crossing speed region but also in the overall control region including steady-state region.

• Journal of the Korean Society of Safety
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• v.15 no.2
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• pp.63-69
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• 2000

The constraint conditions are the stator voltage and the stator current to operate the motor in the flux weakening region. The maximum current is limited by the inverter current rating and the machine thermal rating. Given DC link voltage to control the motor in the flux weakening the maximum voltage is determined by considering PWM strategy, dead time, voltage drop of the inverter switching device, and the margin of the voltage for current forcing. In this paper, the new method to determine the available maximum voltage is derived by the quantitative method and by considering the factors of the voltage drop. The proposed method to determine the maximum voltage is very useful to improve the stability of the motor system and to enlarge the speed operation region in the flux weakening operation. Therefore the utility of the maximum voltage is increased.

• Journal of The Geomorphological Association of Korea
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• v.27 no.3
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• pp.75-85
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• 2020

Few studies have dealt with the question of when Mt. Baekdusan became known as a volcano. Attention has been focused rather on the issue of establishing the boundary between the Joseon Dynasty and the Qing Dynasty than the scientific nature of Baekdusan as a volcano. It is only in the late Joseon Dynasty that Park Jong (1764), who was the scholar of the Gwanbuk region, authored the first travel journal on Mt. Baekdu and described poseok. Due to the scientific curiosity of Westerners on the existence of mysterious snow peak on the border, it was first introduced to the Royal Geographical Society by a British man, H.E.M. James in 1887, who revealed for the first time that Mt. Baekdu is a dead volcano, and that the white color on the top is due to wide-spread pumice. Russian expedition teams including Strel'bitskii (Стрельбицкий, 1894, and Garin (Гарин-Михайловский, 1898), also explored this mountain seeking natural resources and territory of East Asia and the Manchurian region in pursuit of Russian Imperial interests explored and described Baekdusan as a volcano.