• 동의신경정신과학회지
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• 제29권3호
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• pp.121-134
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• 2018

Objectives: The purpose of this in vivo study is to observe anti-amnesic effects of Yeongkyekamjotanggayonggolmoryo (YGYM), a novel mixed herbal prescription, Ossis Mastodi and Ostreae Testa added Yeongkyekamjo-tang, on scopolamine induced amnesia in C57BL/6 mice through acetylcholine (ACh) and acetylcholinesterase (AChE) activity, Choline acetyltransferase (ChAT) mRNA expression, and antioxidant effects. Methods: Six groups, total 20 intact or 100 Sco treated mice were used in this study after one week of acclimatization period. Half the animals were used for passive avoidance task tests and hippocampus ACh content, AChE activity, and ChAT mRNA expression were measured. The other half was subjected to an underwater maze test and then the cerebral cortex antioxidant defense system was measured. Results: In the passive avoidance experiment, there was significant decrease in residence time in the bright room and in the underwater maze test, escape latency to escape from the esophagus significantly increased compared with the normal control group. At the final sacrifice, ACh content and ChAT mRNA expression decreased, AChE activity increased, and cerebral cortical MDA increased GSH content, SOD and CAT activity in Sco control mice, as compared to intact vehicle control mice. However, these Sco treatment-related memory loss through AChE activation destroyed the cerebral cortex antioxidant defense system, and was inhibited dose-dependently by 28 days consecutive oral pretreatments of YGYM extracts 500, 250, 125 mg/kg. Conclusions: In the above results, YGYM extract that oral administration of YGYM extracts alleviates the antioxidant defense system, through preservation of ACh mediated by upregulation of ChAT mRNA expression, and increase of AChE inhibition and brain antioxidant defense systems.

• 전기학회논문지
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• 제58권11호
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• pp.2149-2154
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• 2009

Electric power quality in power transmission/distribution systems has considerably been deteriorated with the increase in the capacity of distributed generators (DGs). It is because inverters, connecting DGs to conventional power grids, tend to generate harmonic current and voltage. For harmonic mitigation, a large amount of research has been done on passive and active filters, which have been operating successfully in many countries. This paper, therefore, presents how to adopt the filters to an inverter-based DG, with considering a system consisting of both inverter-based DG and harmonic filters. In particular, this paper describes the simulation results using the PSCAD/EMTDC: firstly, the relationship between total harmonic distortion(THD) of current and output power of DG: secondly, the harmonic mitigation ability of passive and active filters. The system, furthermore, is obliged to satisfy the regulations made by Korean Electric Power Corporation(KEPCO). In the regulations, power factor should be maintained between 0.9 and 1 in a grid-connected mode. Thus, this paper suggests two methods for the system to control its power factor. First, the inverter of DG should control power factor rather than an active filter because it brings dramatic decrease in the capacity of the active filter. Second, DG should absorb reactive power only in the range of low output power in order to prevent useless capacity increase of the inverter. This method is expected to result in the variable power factor of the system according to its output power.

• 한국정보통신학회논문지
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• 제11권1호
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• pp.124-130
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• 2007

RFID는 항만 물류의 효율성을 높일 수 있는 기술로 주목을 받고 있다. 특히 컨테이너 용 e-Seal 등 능동형 RFID 기술에 대한 관심이 높다. 그런데 능동형 RFID 뿐 아니라 수동형 RFID나 전통적인 바코드 시스템을 복합사용하면 전체 항만 물류 처리과정의 효율을 증대시킬 수 있다. 그러나 각 RFID 리더 및 인식 장치에 종속적인 다양한 제어 인터페이스로 인해 복합사용 환경 구축에 많은 어려움을 겪고 있다. 본 논문은 Smart Reader Interface라는 장치 독립적인 공통의 인터페이스를 통해 다양한 RFID 리더 및 인식 장치를 제어 할 수 있는 RFID 미들웨어를 설계하였다. 우리는 관련 표준, 처리의 효율성, 새로운 리더 추가에 대한 확장성 등을 주요 고려 사항으로 설계에 반영하였다. 설계 결과를 바탕으로 실제 다양한 상용 RFID 리더를 지원하도록 시스템을 구현하였다. 실험실 환경 뿐 아니라 실제 광양항 컨테이너 부두에서 실시한 실험을 통해 개발한 시스템의 실용성을 검증하였다.

• Structural Engineering and Mechanics
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• 제64권3호
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• pp.301-310
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• 2017

For further development of passive control systems to dissipate larger seismic energy and prevent the structures from earthquake losses, this paper proposes an innovative two-level control system to improve behavior of chevron braced steel frames. Combining two Knee Braces, KB, and a Vertical Link Beam, VLB, in a chevron braced frame, this system can reliably sustain main shock and aftershocks in steel structures. The performance of this two-level system is examined through a finite element analysis and quasi-static cyclic loading test. The cyclic performances of VLB and KBs alone in chevron braced frames are compared with that of the presented two-level control system. The results show appropriate performance of the proposed system in terms of ductility and energy dissipation in two different excitation levels. The maximum load capacity of the presented system is about 30% and 17% higher than those of the chevron braced frames with KB and VLB alone, respectively. In addition, the maximum energy dissipation of the proposed system is about 78% and 150% higher than those of chevron braced frames with VLB and KB respectively under two separate levels of lateral forces caused by different probable seismic excitations. Finally, high performance under different earthquake levels with competitive cost and quick installation work for the control system can be found as main advantages of the presented system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1606-1611
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• 2005

The goal of this paper is to develop a self localization of mobile robot using UHF RFID landmark. We present landmark, a location sensing archetype system that uses UHF Radio Frequency Identification (UHF RFID) technology for locating objects inside buildings. The major advantage of landmark is that it improves the overall accuracy of locating objects by utilizing the concept of reference tags. Based on experimental analysis, we demonstrate that passive UHF RFID is a viable and cost-effective candidate for indoor location sensing. We conduct a series of experiments to evaluate performance of the positioning of the landmark System. In the standard setup, we place RF Reader which has two antennas and 25 tags in our lab. This research uses the assumption-based coordinates (ABC) algorithm[3] for determining the localization of robot. Also, we show how Radio Frequency Identification (UHF RFID) can be used in robot-assisted indoor navigation for the visually impaired. The experiments illustrate that passive UHF RFID tags can act as reliable landmark that trigger local navigation behaviors to achieve global navigation objectives.

• 전자공학회논문지SC
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• 제43권4호
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• pp.60-66
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• 2006

장비를 사용해서 해양자원을 탐사하고 개발하기 위해서 수중초음파 통신은 유용한 수단이 된다. 이러한 응용을 위해서는 정보전달 및 원격제어가 필수적인데, 해양환경에서 다양한 형태의 노이즈가 발생하여 제어의 효율성과 수중통신의 신뢰성이 저하 되고 있다. 그래서 기존의 방법은 하드웨어적인 방법으로 제어정보를 수신하고 이를 반복적으로 기준 정보와 비교하는 방법을 사용하고 있어 제어신뢰성이 중요시되는 시스템에서는 효율성이 떨어지고 있다. 따라서 본 연구에서는 해양환경 변화에 따른 영향이 없이 초음파 신호를 인식할 수 있는 수중 초음파신호 검출성능 향상 알고리듬을 제안하려 한다. 제안하는 알고리듬의 적합성을 시뮬레이션을 통하여 확인하였다.

• Smart Structures and Systems
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• 제17권5호
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• pp.773-793
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• 2016

This work presents a methodology to distribute piezoelectric material for structural vibration active control. The objective is to design controlled structures with actuators which maximizes the system controllability. A topology optimization was formulated in order to distribute two material phases in the domain: a passive linear elastic material and an active linear piezoelectric material. The objective is the maximization of the smallest eigenvalue of the system controllability Gramian. Analytical sensitivities for the finite element model are derived for the objective functions and constraints. Results and comparisons with previous works are presented for the vibration control of a two-dimensional short beam.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2004년도 전력전자학술대회 논문집(2)
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• pp.787-790
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• 2004

In this paper, a novel control scheme compensating for source voltage unbalance and current harmonics and power factor correction in unified active power filter systems combined with shunt passive filters is proposed, where no low/high-pass filter are used in deriving the reference voltage for compensation. Using digital all-pass filters, the phase angle and the reference voltages compensating for harmonic current and unbalanced voltage are derived from the positive sequence component of the unbalanced voltage. The amplitude of d-axis current in a series filter is controlled as zero for power factor correction. The validity of the proposed control scheme has been verified by experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.245-248
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• 1996

This paper suggests a new concept for missile guidance control, called linearized common curvature guidance law that enhances the probability to kill a target. The proposed guidance system is composed of two switching modes; one for the midcourse guidance and the other for the terminal guidance, which is switched by a specified critical value (.epsilon.). And the system and the commands are formulated and its simulations are provided in comparison with the conventional commanded line of sight guidance algorithm. Miss distance and angle of attack are denoted as performance of parameters. This new concept, common curvature guidance algorithm, revises the navigation guidance and accompanies, various considerations.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.233-236
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• 2005

Phase noise in a phase-locked-loop (PLL) is unwanted and unavoidable. It is a main concern in oscillation system especially PLL. The phase noise is derived in term of power spectrum density by using a reliable phase noise model. There are four noise sources being considered in this paper, which are generated by reference oscillator, voltage controlled oscillator, filter, and main divider. The major concern for this paper is the noise from the filter. Two types of second order low pass filter are used in the PLL system. Applying the mathematical phase noise model, the output noises are compared. The total noise from the passive filter is lower than the active filter at the offset frequency range between 1 Hz to 33 kHz.