• The Journal of Korea Robotics Society
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• v.6 no.2
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• pp.108-117
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• 2011

This paper proposes an optimal ARS control of a two-wheel mobile inverted pendulum robot. Conventional researches are highly concentrated on the robust control of a mobile inverted pendulum on the flat ground, $i.e.$, mostly focus on the compensation of gyroscope signals. This newly proposed algorithm deals with a climbing control of a slanted surface based on the dynamic modeling using the conventional structure. During the climbing control of the robot, unexpected disturbance forces are essentially caused by the irregular contact force which comes from the irregular contact angle between the wheel and the terrain. The disturbances have effects on the optimal posture of the mobile robot to compensate the slanted angle. Therefore the dynamics equations through physical interpretation are derived for the selection of optimum climbing posture through ARS. Also using the ultrasonic sensor the slope information is obtained to compensate for the force of gravity. The control inputs are dynamically adjusted to climb up the slanted surface effectively. The proposed algorithm is demonstrated through the real experiments.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.216-224
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• 2013

This paper describes dual inverter drive for a fractional-slot concentrated winding permanent magnet synchronous machine (PMSM). PMSMs are widely used in many applications from small servo motors to few megawatts generators thanks to its high efficiency and torque density. Especially, fractional-slot concentrated winding PMSM is very popular in the applications where wide operation range is required because it shows very wide constant power speed ratios. High speed operation, however, requires lots of negative daxis current for reducing back-EMF regardless of output torque. Field weakening current does not contribute to the torque generation in surface mounted PMSM case and causes inverter and copper loss. To reduce the losses from field weakening current, this paper proposes PMSM with split stator and parallel dual inverter drive. Proposed parallel dual inverter drive reduces back-EMF and enables efficient drive at high speed and light load situation. Control strategy of proposed dual inverter system is established through loss analysis and simulation. Proposed concept is verified with practical experiment.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2001.02a
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• pp.163-166
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• 2001

KEPCO has a plan to construct TRF (tritium removal facility) in wolsong nuclear power plant site by 2005. In advance of WTRF construction, the pilot plant was installed at KEPRI in order to show process reliability of WTRF. The main processes of this pilot plant are LPCE(liquid phase catalytic exchange) and CD (cryogenic distillation). Deuterium is separated from heavy water in LPCE process and concentrated in CD process. CD process consists of cold box, where are a distillation column and heat exchangers, vacuum system, cryogenic refrigerant supply system and instrument & control system. The experience of the pilot plant will be used in WTRF design review, operating procedure revision and fundamental education for the operators.

• Journal of Drive and Control
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• v.18 no.3
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• pp.23-29
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• 2021

Hydrogen energy is the clean energy source of the future. Ultra-high-pressure hydrogen is used in hydrogen stations, with its parts being developed. On the other hand, ultra-high-pressure ball valve, which is one of its parts, depends on overseas, with the level of domestic research on this being only about 10% of advanced technology research on this abroad. In this study, the shape of an ultra-high-pressure ball valve for a hydrogen station was designed to improve its structural strength. The valve body was designed according to distance between both processed body holes along inlet and outlet ports. The designed vale body was then analyzed using ANSYS to check whether points with stress were concentrated. In addition, the valve with improved body was analyzed to confirm that the valve satisfied the design condition.

• Proceedings of the Korea Water Resources Association Conference
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• 1993.07a
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• pp.3-26
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• 1993

I have briefly described some of the important advances in hydrosystems and to remark on the important scientific research priorities in hydrological sciences. We have concentrated on data collection systems, real-time control of hydrosystems, global climate change and decision support systems and GIS. In summary, I would like to stress the following points: - the advances in data collection systems, advanced methodologies for interfacion hydrologic, hydraulic, and optimization models through optimal control approaches; and the advances in decision support systems and GIS will allow the interfacing of all these technologies into some sophisticated and much needed tools for operating hydrosystems; - the ability to better understand the hydrologic processes and their relationships to other earth processes is important to understanding and modelling of the hydrologic cycle and its interactions with the ocean-atmosphere system; - and the solution to a better understanding of hydrologic sciences needs to be an international effort such as the GEWEX program briefly discussed above. I would like to thamk each of you for listening to my lecture and to once again thank those responsible for me being here today. Thank you.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2074-2079
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• 2018

Global state space's optimal policy is used for offline controller in the form of table by using Dynamic Programming. If an optimal policy table has a large amount of control data, it is difficult to use the system in a low capacity system. To resolve these problem, controller using the compressed optimal policy table is proposed in this paper. A DCT is used for compression method and the cosine function is used as a basis. The size of cosine function decreased as the frequency increased. In other words, an essential information which is used for restoration is concentrated in the low frequency band and a value of small size that belong to a high frequency band could be discarded by quantization because high frequency's information doesn't have a big effect on restoration. Therefore, memory could be largely reduced by removing the information. The compressed output is stored in memory of embedded system in offline and optimal control input which correspond to state of plant is computed by interpolation with Inverse DCT in online. To verify the performance of the proposed controller, computer simulation was accomplished with a one link inverted pendulum.

• Korean System Dynamics Review
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• v.17 no.1
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• pp.5-24
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• 2016

This study structurally analyzes major inefficiency of Korea's healthcare delivery system by utilizing the systems thinking. In particular, the phenomenon of patient's concentrated visits to large hospitals, waste of resource due to competitions between clinics and large hopitals, and the structure of oversupply were visualized using the causal loop diagram. The inefficient structure of healthcare delivery system can be understood more clearly by utilizing the major system archetypes of 'success to the successful', 'tragedy of commons', 'escalation' and 'limits to growth'. This study also finds solution from archetypal structure suggested by Wolstenholme. The inefficient status of healthcare delivery system might be explained by the 'out of control' archetype. In conclusion, the public resources such as the national health insurance need to be acknowledged as the entire achievement. All the participants should cooperate with each other in order to improve the inefficiency of the healthcare delivery system. In addition, the arrangement of incentive system for cooperation, acceleration of health information technology, and development of innovative business models make the sustainable healthcare delivery system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2236-2245
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• 1997

The DBS system is being highlighted as actual area for the information societics. Specially, the DBS have been proposed very useful system to access the broading service in more widely sea. But the antenna tracking system for maritime DBS receiving is requried complicated control system because of the those complex motion represented pitching, rolling and yowing etc. Our resesrch target is a development of tracking system to the KOREASEA(MUGUNGWHA-1,2) for the applicated small size shipping. So our development focus was concentrated the two development direction. The first focus was represented low-cost system for popularization of small-size shipping around sea of the Korea peninsula. The second focus was an adaptive possibilities with domestic eqdupiment which was developed satellite receiving for KOREASAT. The anntenna mount is designed a compact size and easy operation use to the Az/El 2-axis type which is operated by step motor. And this mount type is very useful on a ship in the near sea of Korea peninsula. Basic tracking method is used th step-tracking algorithm, and the ship's moving compensation is adapted to the closed loop control method by ship's moving detection of gyro sensor. Control part is consists of converter, countertime, VCO, micro-computer and it's software. Testing the operation by the ship's moving simulator, and algorithm is designed tracking and moving compensation by receiving state.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.5
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• pp.60-66
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• 2002

The military services have sought to improve the overall quality, management, and delivery of military technical information in all of its aspects. The efforts concentrated on developing IETM(Interactive Electronic Technical Manual) by using the application of computer technology for the storage, control, and presentation of maintenance, system-operation, training, and other forms of logistic-support technical information. In this paper, the methodologies are presented to evaluate the operational effectiveness of IETM which consists of confirmity and performance. Confirmity is evaluated by the check-sheet based on the standard of CALS, and performance by the comparison of the technician performance between IETM and paper-TM.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.954-957
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• 1987

This paper proposes a kind of function-concentrated signaling service equipment structure, in which various kind of signaling service are efficiently made for call processing control. Based upon the typical switching system models, a philosophical study on the capacity, features of structure in world systems, and interfaces with peripheral equipments has been performed in order to provide the rationale on the merits or efficiency of the proposed digital signaling service equipment.