• Journal of Power Electronics
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• v.11 no.5
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• pp.719-725
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• 2011

This paper describes a novel Direct Torque Control (DTC) method for adjustable speed Doubly-Fed Induction Machine (DFIM) drives which is supplied by a two-level Space Vector Modulation (SVM) voltage source inverter (DTC-SVM) in the rotor circuit. The inverter reference voltage vector is obtained by using input-output feedback linearization control and a DFIM model in the stator a-b axes reference frame with stator currents and rotor fluxes as state variables. Moreover, to make this nonlinear controller stable and robust to most varying electrical parameter uncertainties, a two layer recurrent Artificial Neural Network (ANN) is used to estimate a certain function which shows the machine lumped uncertainty. The overall system stability is proved by the Lyapunov theorem. It is shown that the torque and flux tracking errors as well as the updated weights of the ANN are uniformly ultimately bounded. Finally, effectiveness of the proposed control approach is shown by computer simulation results.

• The Journal of Korea Robotics Society
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• v.12 no.1
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• pp.42-54
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• 2017

Using an inverse of the geometric Jacobian matrix is one of the most popular ways to control robot manipulators, because the Jacobian matrix contains the relationship between joint space velocities and operational space velocities. However, the control algorithm based on Jacobian matrix has algorithmic singularities: The robot manipulator becomes unstable when the Jacobian matrix loses rank. To solve this problem, various methods such as damped and filtered inverse have been proposed, but comparative studies to evaluate the performance of these algorithms are insufficient. Thus, this paper deals with a comparative analysis of six representative singularity avoidance algorithms: Damped Pseudo Inverse, Error Damped Pseudo Inverse, Scaled Jacobian Transpose, Selectively Damped Inverse, Filtered Inverse, and Task Transition Method. Especially, these algorithms are verified through computer simulations with a virtual model of a humanoid robot, THORMANG, in order to evaluate tracking error, computational time, and multiple task performance. With the experimental results, this paper contains a deep discussion about the effectiveness and limitations of each algorithm.

• Journal of the Korean Society for information Management
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• v.27 no.4
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• pp.109-130
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• 2010

The purpose of this study is to identify th patterns in the news reporters' information seeking behaviors by observing their web activities. For this purpose, transaction logs collected from 23 news reporters were analyzed. Web tracking software was installed to collect the data from their PCs, and a total of 39,860 web logs were collected in two weeks. Start and end pattern of sessions, transitional pattern by step, sequence rule model was analyzed and the pattern of Internet use was compared with the general public. the analysis of pattern derived a web information seeking behavior modes that consists of four types of behaviors: fact-checking browsing, fact-checking search, investigative browsing and investigative search.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.93-104
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• 2011

The purpose of this study was to investigate lower-limb joint torque of the two groups as it changed by somatosensory stimulation during the descent down three stairs of different heights and to describe the difference between the two groups, which are young people group and elderly people group. Subjects of each groups climbed down a stair at four stimulation conditions, which are non-stimulation, tibialis anterior tendon stimulation, achilles tendon stimulation, tibialis anterior - achilles tendon stimulation. Motion capture data were collected using 3D optoelectric motion tracking system that utilizes active infrared LEDs, near infrared sensor and force plate. The obtained motion capture data was used to build 3D computer simulation model. The results show that lower-limb joint torque of the two groups changed with somatosensory stimulation as they descended the stairs and the joint torque of the two groups differed from each other.

• Nutrition Research and Practice
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• v.12 no.3
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• pp.208-214
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• 2018

BACKGROUND/OBJECTIVES: The aim of this study was to evaluate the biological and sleep-promoting effects of combined ${\gamma}$-aminobutyric acid (GABA) and 5-hydroxytryptophan (5-HTP) using caffeine-induced sleepless fruit flies, ICR mice, and Sprague-Dawley rats. MATERIALS/METHODS: Video-tracking analysis was applied to investigate behavioral changes of Drosophila melanogaster. Pentobarbital-induced sleep test and electroencephalogram (EEG) patterns were used for analysis of sleep latency, duration, and quantity and quality of sleep in vertebrate models. RESULTS: Administration of combined GABA/5-HTP could significantly reverse the caffeine induced total distance of flies (P < 0.001). Also, individually administered and combined GABA/5-HTP significantly increased the total sleeping time in the caffeine-induced sleepless ICR mice (P < 0.001). In the caffeine-induced sleepless SD-rats, combined GABA/5-HTP showed significant differences in sleep quality between individual amino acid administrations (P < 0.05). CONCLUSIONS: Taken together, we identified inhibitory effects of combined GABA/5-HTP in locomotor activity, sleep quantity and quality in caffeine-induced sleepless models, indicating that combined GABA/5-HTP may be effective in patients with insomnia by providing sufficient sleep.

• Journal of Power Electronics
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• v.17 no.3
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• pp.704-715
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• 2017

For three-phase synchronization applications, the synchronous reference frame phase-locked loop (SRF-PLL) is probably the most widely used technique due to its ease of implementation and satisfactory phase tracking performance under ideal grid conditions. However, under unbalanced and distorted grid conditions, its performance tends to worsen. To deal with this problem, a variety of filtering stages have been proposed and used in SRF-PLLs for the rejection of disturbance components at the cost of degrading the dynamic performance. In this paper, to improve dynamic performance without compromising the filtering capability, an effective hybrid filtering stage is proposed and incorporated into the inner loop of a quasi-type-1 PLL (QT1-PLL). The proposed filtering stage is a combination of a moving average filter (MAF) and a modified delay signal cancellation (DSC) operator in cascade. The time delay caused by the proposed filtering stage is smaller than that in the conventional MAF-based and DSC-based PLLs. A small-signal model of the proposed PLL is derived. The stability is analyzed and parameters design guidelines are given. The effectiveness of the proposed PLL is confirmed through experimental results.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.75-86
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• 2013

PURPOSES: The purpose of asphalt pavement reducing surface temperature by using Pipe cooling system is to make pleasant city life environment. METHODS: We considered building condition to lay the pipes under asphalt pavement and figured out that temperature reducing effect with pipe cooling system. In addition, we guessed rutting through wheel tracking test with a laid the pipes under asphalt mixture and performed fatigue cracking through a flexural fatigue test for performance evaluation of pipe cooling system. RESULTS: When pipe cooling system worked, the temperature of pavement model reduced quickly in test. The system can turn down the degree by 4 or 5 quickly as well. It didn't affect rutting to lay the pipes under the pavement, but it can get damaged to asphalt pavement in early stage by the result of performance evaluation. CONCLUSIONS: We figured out that pipe cooling system can turn down the temperature of aspalt pavement surface through tests. We suggest that pipe cooling system should be considered one of the effective way to solve urban heat island problem.

• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.878-881
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• 2003

To acquire an appointed speaker's clear voice signal from inspect-camera, picture-conference or hands free microphone eliminating interference noises needs to be preceded speaker's position automatically. Presumption of sound source position's basic algorithm is about measuring TDOA(Time Difference Of Arrival) from reaching same signals between two microphones. This main project uses ADF(Adaptive Delay Filter) [4] and CPS(Cross Power Spectrum) [5] which are one of the most important analysis of TDOA. From these analysis this project proposes presumption of real time sound source position and improved model NI-ADF which makes possible to presume both directions of sound source position. NI-ADF noticed that if auditory sense of humankind reaches above to some specified level in specified frequency, it will accept sound through activated nerve. NI-ADF also proposes practicable algorithm, the presumption of real time sound source position including both directions, that when microphone loads to some specified system, it will use sounds level difference from external system related to sounds of diffraction phenomenon. In accordance with the project, when existing both direction adaptation filter's algorithm measures sound source, it increases more than twice number by measuring one way. Preserving this weak point, this project proposes improved algorithm to presume real time in both directions.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.2
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• pp.47-55
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• 2008

The purpose of this paper is to develop an analytical methodology of or릴 documents by the application of. Information Technologies. This system consists of the key word search, contents summary, clustering, classification & topic tracing of the contents. The integrated model of the five levels of retrieval technologies can be exhaustively used in the analysis of oral documents, which were collected as oral history of five men and women in the area of North Jeolla. Of the five methods topic tracing is the most pioneering accomplishment both home and abroad. In final this research will shed light on the methodological and theoretical studies of oral history and culture.

• Annual Conference of KIPS
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• 2015.10a
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• pp.980-982
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• 2015

성공적인 시스템 개발을 위해서 SW의 품질을 향상시켜야 한다. 하지만 국내 SW 산업환경은 코드 중심 개발로써, 개발 문서 부재 및 SW개발과 문서화가 동시에 수행되지 않는다. 이러한 문제의 해결을 위해서 SW개발 시, 발생 문서는 코드와 문서의 동시 개발 및 시스템화가 필요하다. 본 논문은 체계적인 요구사항 관리를 위한 요구사항 추적 모델을 제안한다. 제안한 모델은 기존의 SW Visualization을 통한 역공학 기법에 적용하여 품질 개선 및 코드와 문서의 불일치 문제를 해결하고자 한다.