• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.467-467
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• 2000

In this paper, a structural design method of robust motion controllers for high-accuracy positioning systems, which makes it possible to predict the performance of the whole closed-loop system, is proposed. First, a stabilizing control input is designed based on robust internal-loop compensate.(RTC) for the system in the presence of uncertainty and disturbance. Next, using the structural characteristics of the RIC, disturbance attenuation properties and the performance of the closed-loop system determined by the variation of controller gains are analyzed. Through this analysis, in some specific applications, it is shown that if the control gain of RIC is increased by N times, the magnitude of error is reduced to its 1/N. Finally, the proposed method is verified through experiments using a high-accuracy positioning system used in the semiconductor chip mounting devices.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.168-186
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• 2016

In this paper, we investigate the degrees of freedom (DoF) of a two-cluster multiple-input multiple-output (MIMO) multiway relay interference channel (mRIC), where there are two relays and two users per cluster. In this channel, users within the same cluster exchange messages among themselves with the help of two relays.We first obtain the DoF upper bound of the considered MIMO mRIC based on cut-set bound. Then, we propose a novel transmission strategy, blind interference neutralization (BIN), to approach the DoF upper bound. This new method utilizes the overheard information at two relays and focuses on the beamforming matrix designs at two relays so that the channel state information (CSI) at users is not required. Through theoretical analysis and numerical simulations, we show that the DoF upper bound can be obtained by using the BIN scheme. From simulation results, we show that the proposed BIN scheme can provide significant performance gain over the conventional time division multiple access (TDMA) scheme in terms of DoF. In addition, we show that the BIN scheme is a superior approach to the existing signal space alignment (SSA) schemes for the considered mRIC.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.580-585
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• 2005

A QRT(Quad-Rotor Type) hovering robot system is developed for quick detection and observation of the circumstances under calamity environment such as indoor fire spots. The UAV(Unmanned Aerial Vehicle) is equipped with four propellers driven by each electric motor, an embedded controller using a DSP, INS(Inertial Navigation System) using 3-axis rate gyros, a CCD camera with wireless communication transmitter for observation, and an ultrasonic range sensor for height control. The developed hovering robot shows stable flying performances under the adoption of RIC(Robust Internal-loop Compensator) based disturbance compensation and the vision based localization method. The UAV can also avoid obstacles using eight IR and four ultrasonic range sensors. The VTOL(Vertical Take-Off and Landing) flying object flies into indoor fire spots and sends the images captured by the CCD camera to the operator. This kind of small-sized UAV can be widely used in various calamity observation fields without danger of human beings under harmful environment.

• Journal of applied mathematics & informatics
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• v.7 no.2
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• pp.653-664
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• 2000

The problem of inference about the unknown change-point with a change in mean is considered. We suggest a nonparametric change-point estimator using window and prove its consistency when the errors are from the distribution with the mean zero and the common variance. a comparison study is done by simulation on the mean, the variance, and the proportion of matching the true change-points.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1493-1498
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• 2007

In this work, alkyl methacrylate-based microgels were synthesized by an experimental design method, and their sebum absorption characteristics were investigated. The results of fractional factorial experimentation indicated that the cross-linking agent content, solvent content, and stirring speed were the main parameters in the synthesis of the microgels. The suitable synthesis conditions were determined by the response surface design method. Through a study of the monomer and solvent effects, it was confirmed that the microgel shows the highest sebum absorption ratio when t-butyl methacrylate is used as a monomer or when acetone is used as a solvent. The optimal microgel synthesis conditions for cosmetic application were determined, and the resulting microgel had a mean particle size of 4.7 μm and a sebum absorption ratio of 435%.

• Nutrition Research and Practice
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• v.7 no.2
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• pp.96-102
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• 2013

Obesity, an intractable metabolic disease, currently has no medical treatment without side effects, so studies have been actively carried out to find natural compounds that have anti-obesity activity with minimum side effects. In this study, the anti-obesity effects of water extracts of seven Capsicum annuum L. varieties being Putgochu (Pca), Oyee gochu (Oca), Kwari putgochu (Kca), Green pepper (Gca), Yellow paprika (Yca), Red paprika (Rca) and Cheongyang gochu (Cca), were examined through the evaluation of lipoprotein lipase (LPL) mRNA expression level in 3T3-L1 cells (mouse pre-adipocytes). After capsaicin elimination by chloroform defatting, freeze-dried powder of Cca was treated to 3T3-L1 cells and anti-obesity effects were examined by determining the LPL mRNA level using the RT-PCR method. Of the primary fractions, only proven fractions underwent secondary and tertiary refractionating to determine anti-obesity effects. From seven different Capsicum annuum L., there was a significant decrease of the LPL mRNA expression level of 50.9% in Cca treatment compared to the control group. A significant decrease of the LPL mRNA expression level was shown in primary fractions (Fr) 5 (36.2% decrease) and 6 (30.5% decrease) of the Cca water extracts. Due to the impurities checked by UPLC chromatography, Fr 5 and 6 were refractionated to determine the LPL mRNA expression level. Treatment of Fr 6-6 (35.8% decrease) and Fr 5-6 (35.3% decrease) showed a significant decrease in the LPL mRNA expression level. When analyzed using UPLC, major compounds of Fr 6-6 and Fr 5-6 were very similar. Subsequently, we refractionated Fr 6-6 and Fr 5-6 to isolate the major peak for structure elucidation. Treatment of Fr 5-6-1 (26.6% decrease) and Fr 6-6-1 (29.7% decrease) showed a significant decrease in the LPL mRNA expression level. Consequently, the fractions may have a possibility to ameliorate obesity through the decrease of the LPL mRNA expression level.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.1
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• pp.19-27
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• 2014

Mg hydride has a high hydrogen capacity (7.6%), at high temperature, and is a lightweight and low cost material, thus it a promising hydrogen storage material. However, its high operation temperature and very slow reaction kinetics are obstacles to practical application. In order to overcome these disadvantages of Mg hydride, graphene powder was added to it. The addition of graphene has been shown to reduce the operating temperature of dehydrogenation. Moreover, in this report the environmental aspects of $MgH_x$-Graphene composites are investigated by means of the environmental life cycle assessment (LCA) method. $MgH_x$-Graphene mixture was prepared by hydrogen induced mechanical alloy (HIMA). The synthesized powder was characterized by XRD(X-ray Diffraction). The hydrogenation behaviors were evaluated by using a Sievert's type automatic PCT apparatus. Such evaluation of Materials also conducted in the LCA. From the result of P-C-T(Pressure-Composition-Temperature) curves, the $MgH_x$-3wt.% graphene composite was evaluated as having a 5.86wt.% maximum hydrogen storage capacity, at 523K. From absorption kinetic testing, the $MgH_x$-7wt.% graphene composite was evaluated as having a maximum 6.94wt.%/ms hydrogen absorption rate, at 573K. Environment evaluation results for the $MgH_x$-graphene composites and other materials indicated environmental impact from the electric power used and from the materials themselves.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.101-106
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• 2003

In the area of tracking control, it is important to design not only the controllers but also the trajectories to which a system has to follow. $5^{th}$ order polynomial is often used with constraints of initial and final states. Smooth ending with possible minimum time is important for many systems because of vibration or jerky motions. Examples are increased with development of technology in smaller, more accurate systems. On the base of a polynomial like trajectory generation method from a paper in ACC2002 and RIC(Robust Internal-loop Compensator) control scheme of Robotics and Bio-mechanics lab. of POSTECH, generalized and expanded polynomial like trajectory generation method is showed.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.6 no.4
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• pp.293-298
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• 2006

In this paper, a sensor fusion based robot navigation method for the autonomous control of a miniature human interaction robot is presented. The method of navigation blends the optimality of the Fuzzy Neural Network(FNN) based control algorithm with the capabilities in expressing knowledge and learning of the networked Intelligent Robotic Space(IRS). States of robot and IR space, for examples, the distance between the mobile robot and obstacles and the velocity of mobile robot, are used as the inputs of fuzzy logic controller. The navigation strategy is based on the combination of fuzzy rules tuned for both goal-approach and obstacle-avoidance. To identify the environments, a sensor fusion technique is introduced, where the sensory data of ultrasonic sensors and a vision sensor are fused into the identification process. Preliminary experiment and results are shown to demonstrate the merit of the introduced navigation control algorithm.

• Journal of Ocean Engineering and Technology
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• v.21 no.4
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• pp.8-14
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• 2007

A particle method recognized as one of gridless methods has been developed to investigate incompressible viscous flaw. The method is more feasible and effective than conventional grid methods for solving the flaw field with complicated boundary shapes or multiple bodies. The method is consists of particle interaction models representing pressure gradient, diffusion, incompressibility and the boundary conditions. In the present study, the models in case of various simulation condition were checked with the analytic solution, and applied to the two-dimensional Poiseuille flow in order to validate the developed method.