• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.1-9
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• 2014

Structural loading on a wind turbine is due to cyclic loads acting on the blades under turbulence and periodic wind field. The structural loading generates fatigue damage and fatigue failure of the wind turbine. The individual pitch control(IPC) is an efficient control method for reducing structural loading. In this paper, we present an IPC design method using Decentralized LQR(DLQR) and Disturbance accommodating control(DAC). DLQR is used for regulating rotor speed and DAC is used for canceling out disturbances. The performance of the proposed IPC is compared with CPC, which was designed with a gain-scheduled PI controller. We confirm the effect of fatigue load reduction with the use of damage equivalent load(DEL).

• Asian Journal for Public Opinion Research
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• v.9 no.4
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• pp.331-351
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• 2021

The unprecedented situation of COVID-19 caused the government of India to instruct educational institutions to switch to an online mode to mitigate the losses for students due to the pandemic. The present study attempts to explore the impact of online learning introduced as a stop-gap arrangement during the pandemic in India. A survey was conducted (N=289), via Facebook and WhatsApp, June 1-15, 2020 to understand the accessibility and effectiveness of online learning and constraints that students of higher education across the country faced during the peak times of the pandemic. The analysis and interpretation of the data revealed that the students acclimatized in a short span of time to online learning, with only 33.21% saying they were not satisfied with the online learning mode. However, the sudden shift to online education has presented more challenges for the socially and economically marginalized groups, including Scheduled Caste (SC), Scheduled Tribes (ST), Other Backward Class (OBC), females, and students in rural areas, due to factors like the price of high-speed Internet (78.20% identified it as a barrier to online learning), insufficient infrastructure (23.52% needed to share their device frequently or very frequently), poor Internet connectivity, etc. According to 76.47% of respondents, the future of learning will be in "blended mode." A total of 88.92% of the respondents suggested that the government should provide high-quality video conferencing facilities free to students to mitigate the division created by online education in an already divided society.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.5
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• pp.218-225
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• 2001

This paper analyses the performance of network system using the CAN(Controller Area Network) protocol. Given messages are assumed to be scheduled by the DMS(Deadline Monotonic Scheduling) algorithm. The mathematical models for time-delay that can be occurred between CAN nodes are defined. The effectiveness of modeling is shown by comparing the difference of time-delay between simulations and practical experiments. We analyse the results according to the variation of factors, such as the number of nodes, the transmission speed, the message size and the number of aperiodic messages through simulation and confirm the real-time performance of lower priority messages. We also investigate the real-time performance of periodic messages when aperiodic message generates.

• Proceedings of the Korean Society for Language and Information Conference
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• 2002.02a
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• pp.465-474
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• 2002

Korean government has adopted the French TGV as a high-speed transportation system and the first service is scheduled at the end of 2003. TGV-relevant documents are consisted of huge volumes, of which over than 76% has been translated in English. A large part of the English version is, however, incomprehensible without referring to the original French version. The goal of this paper is to demonstrate how DiET 2.5, a lexicon builder, makes it possible to build with ease domain-specific terminology lexicon that may contain multimedia and multilingual data with multi-layered logical information. We believe our wok shows an important step in enlarging the language scope and the development of electronic lexica, and in providing the flexibility of defining any type of the DTD and the interconnectivity among collaborators. As an application of DiET 2.5, we would like to build a TGV-relevant lexicon in the near future.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.39 no.4
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• pp.350-354
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• 2002

In this paper, we designed an autopilot of the unmanned piloted vehicle to guide to the specific position, and analyzed robustness of the designed autopilot. We divide an aircraft velocity into the three case which are low, cruising and high speed, and designed autopilot gains are gain scheduled. We generated the turbulence for the operational altitudes and proved robustness of the designed autopilot for the turbulence using simulation.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.766-771
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• 2006

Railway stations are important facilities for transport of passengers and freights. The location of station have an effect on the efficiency of railway transport and operation. In this study, an inspection of the primary factors for station spacing in urban railway has been performed and a review for the propriety of the present states and further improvement has been carried. It may be helpful for proper decisions on the route planning in urban railway. Primary factors for station spacing are 1)train capacity, 2)competitiveness with other transportation, 3)accessibility and 4)construction cost, which is out of consideration in the inspection. From the result of this study, the proper station spacing is about 600m for the accessibility, more over 1.03km for the train capacity and more over 1.4km for the competitiveness with other transportation.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.95-100
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• 1996

This paper presents the experimental study on hardening process of high-strength and high-flowable concrete. The experiments were performed to investigate any unfavorable construction situations since the actual concrete placement has been scheduled in cold weather period, so that the high quality concrete construction is convinced to be successfully carried out. The tests were conducted using 600nm and 1000nm height of steel tube to simulate the practical concrete filled steel tube columns according to the following variables as: the categories of chemical admixtures, curing temperatures and curing schemes. The test results were analyzed in terms of hardening speed, internal heat of hydration and history of strength gain. This paper emphasizes the importance of curing schemes on durability and the use of hardening accelerators on strength gain.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.6
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• pp.995-1000
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• 2016

Minimum Energy Performance Standard(MEPS) has been adapted in Korea since 2008. For at least 37 kW, IE3 efficiency class motors are now mandatory in Korea. IE4 level regulation is expected in a few years. Foreign companies are already selling IE4 class motors in the market, and the discussions on IE5 have already started. The efficiency standard of variable speed motors is scheduled for publication shortly. Recently, discussions are now beginning to prepare for IE5 in Korea. In this paper, author reviews the policies associated with a high efficent electric motors by reference to both domestic and international standards, and reviews the research direction to prepare for IE5.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.406-406
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• 2000

In this study, as a part developing an unmanned container terminal (UCT), Ive designed and implemented an Autonomous Ground Vehicle (AGV) that can deliver containers in the port fast and safely as they are scheduled. It is preferable to research the intelligent UCT/AGV for delivering containers all day long without causing any trouble. For the sake of safe and fast AGV driving, we implemented a multiple-sensor system with vision, ultrasonic, and IR sensors and we adapted the hight-speed wireless LAN that satisfies the IEEE 802.11 Standard for hi-directional communication between the main processor in AGV and a host computer. The Pentium-III processor board mounted on the bottom frame in AGV combines and computes the information from sensors and controls the AGV driving. There are also the 80C196KC micro-controllers to control the actuating and steering motors. In addition, a steering function that is defined newly in this paper is heavily concerned in the mechanical design, and it plays an important role when AGV moves along a curve. Experimental results show the fast and safe delivery operations are possible with this UCT/AGV

• Journal of Communications and Networks
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• v.11 no.5
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• pp.464-472
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• 2009

In this paper, we propose a packet scheduling algorithm for cellular relay networks by considering relay selection, variation of channel quality, and packet delay. In the networks, mobile users are equipped with not only cellular but also user relaying radio interfaces, where base station exploits adaptive high speed downlink channel. Our proposed algorithm selects a user with good cellular channel condition as a relay station for other users with bad cellular channel condition but can get access to relay link with good quality. This can achieve flexible packet scheduling by adjusting transmission rates of cellular link. Packets are scheduled for transmission depending on scheduling indexes which are calculated based on user's achieved transmission rate, packet utility, and proportional fairness of their throughput. The performance results obtained by using computer simulation show that the proposed scheduling algorithm is able to achieve high network capacity, low packet loss, and good fairness in terms of received throughput of mobile users.