• The Journal of the Korean dental association
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• v.22 no.7 s.182
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• pp.621-633
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• 1984

The possibility of expanding the linear range of the Kinesiograph was studied using a nonferromagnetic mechanical positioning device. The magnet was moved in linear steps of 5 mm through three planes parallel to the frame work carrying the sensors within working range of a 3 cm wide by 4 cm deep by 5 cm high three dimensional lattice and a matrix of 693 data points was achieved. For each data point, the three Kinesiograph outputs were associated with the values of actual position. Once three coordinates of observed values were known, actual values could be determined. A computer program was specially written in Fortran to deal with this work. Because each dat point was 5 mm apart from each other, there would be 480 cubes with 8 data points Further refinement of the system is possible using a smaller interval between each data point. In conclusion, a theoretical model was presented which, by means of computer support, would allow the absolute measurement of jaw position over the entire range of functional jaw movements.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.2
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• pp.69-74
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• 2015

Recently, energy harvesting technology is increasing due to the fossil fuel shortages. Energy harvesting is generating electrical energy from wasted energies as sunlight, wind, waves, pressure, and vibration etc. Energy harvesting is one of the alternatives of fossil fuel. One of the energy harvesting technologies, the piezoelectric energy harvesting has been actively studied. Piezoelectric generating uses a positive piezoelectric effect which produces electrical energy when mechanical vibration is applied to the piezoelectric device. Piezoelectric energy harvesting has an advantage in that it is relatively not affected by weather, area and place. Also, stable and sustainable energy generation is possible. However, the output power is relatively low, so in this paper, newly designed honeycomb shaped piezoelectric energy harvesting device for increasing a generating efficiency. The output characteristics of the piezoelectric harvesting device were analyzed according to the change of parameters by using the finite element method analysis program. One model which has high output voltage was selected and a prototype of the honeycomb shaped piezoelectric harvesting device was fabricated. Experimental results from the fabricated device were compared to the analyzed results. After the AC-DC converting, the power of one honeycomb shaped piezoelectric energy harvesting device was measured 2.3[mW] at road resistance 5.1[$K{\Omega}$]. And output power was increased the number of harvesting device when piezoelectric energy harvesting device were connected in series and parallel.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.12-14
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• 2004

We investigated current limiting characteristics of the flux-lock type high-Tc superconcting fault current limiter(HTSC-FCL) according to fault angles. The Flux-lock type HTSC-FCL consists of primary and the secondary copper coils that are wound in parallel each other through the iron core and YBCO thin flim. In this paper, the current limiting characteristics of the flux-lock type HTSC-FCL according to fault angles in case of the subtractive and additive polarity windings were compared and analyzed. From the results, the flux-lock type HTSC-FCL could limit more quickly fault current as the fault angles increased irrespective of the fault angles. On the other hand, the initial power burden of HTSC element after a fault happened increased as the fault angles increased. In addition, it was confirmed that the resistance of flux-lock type HTSC-FCL in case of subtractive polarity winding was more increased than that of additive polarity winding and that the peak current of fault current in case of subtractive polarity winding was larger than that of the additive polarity winding case.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.3
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• pp.318-323
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• 2005

In this paper, we propose a systematic method of a fuzzy-model-based controller for continuous-time nonlinear dynamical systems which may contain uncertainties. The continuous-time uncertain TS fuzzy model is first constructed to represent the uncertain nonlinear system. A parallel distributed compensation (PDC) technique is then used to design a fuzzy model based controller for both stabilization and tracking. Finally, the designed continuous-time controller is converted to an equivalent discrete-time controller by using an intelligent digital redesign method. This new design technique provides a systematic and effective framework for integration of the fuzzy model based control theory and the advanced digital redesign technique for nonlinear dynamical systems with uncertainties. Finally, the single link flexible-joint robot arm is used as an illustrative example to show the effectiveness and the feasibility of the developed design method.

• Smart Structures and Systems
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• v.18 no.1
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• pp.75-92
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• 2016

The design of a semi-active (SA) control system addressed to mitigate wind induced structural demand to high wind turbine towers is discussed herein. Actually, the remarkable growth in height of wind turbines in the last decades, for a higher production of electricity, makes this issue pressing than ever. The main objective is limiting bending moment demand by relaxing the base restraint, without increasing the top displacement, so reducing the incidence of harmful "p-delta" effects. A variable restraint at the base, able to modify in real time its mechanical properties according to the instantaneous response of the tower, is proposed. It is made of a smooth hinge with additional elastic stiffness and variable damping respectively given by springs and SA magnetorheological (MR) dampers installed in parallel. The idea has been physically realized at the Denmark Technical University where a 1/20 scale model of a real, one hundred meters tall wind turbine has been assumed as case study for shaking table tests. A special control algorithm has been purposely designed to drive MR dampers. Starting from the results of preliminary laboratory tests, a finite element model of such structure has been calibrated so as to develop several numerical simulations addressed to calibrate the controller, i.e., to achieve as much as possible different, even conflicting, structural goals. The results are definitely encouraging, since the best configuration of the controller leaded to about 80% of reduction of base stress, as well as to about 30% of reduction of top displacement in respect to the fixed base case.

• Smart Structures and Systems
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• v.16 no.3
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• pp.415-433
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• 2015

Tendon failures in bonded post-tensioned bridges over the last two decades have motivated ongoing investigations on various aspects of unbonded tendons and their monitoring methods. Recent research shows that change of strain distribution in anchor heads can be useful in detecting wire breakage in unbonded construction. Based on this strain variation, this paper develops a damage detection model that enables an automated tendon monitoring system to identify and locate wire breaks. The first part of this paper presents an experimental program conducted to study the strain variation in anchor heads by generating wire breaks using a mechanical device. The program comprised three sets of tests with fully populated 19-strand anchor head and evaluated the levels of strain variation with number of wire breaks in different strands. The sensitivity of strain variation with wire breaks in circumferential and radial directions of anchor head in addition to the axial direction (parallel to the strand) were investigated and the measured axial strains were found to be the most sensitive. The second part of the paper focuses on formulating the wire breakage detection framework. A finite element model of the anchorage assembly was created to demonstrate the algorithm as well as to investigate the asymmetric strain distribution observed in experimental results. In addition, as almost inevitably encountered during tendon stressing, the effects of differential wedge seating on the proposed model have been analyzed. A sensitivity analysis has been performed at the end to assess the robustness of the model with random measurement errors.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.3
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• pp.103-109
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• 2012

The purpose of this paper is to suggest the strategical lifting postures able to alleviate imbalanced EMG amplitude leading to an increase in low back muscle fatigue while lifting asymmetric load dynamically. Eleven male subjects are required to lift symmetrically an external load with 15.8kg and load center of gravity (LCG) deviated 10cm to the right from the floor to the waist height at the speed of about 25cm/sec. The EMG amplitudes on bilateral low back muscles (Longissimus, Iliocostalis, and Multifidus) are recorded during 2sec and analyzed. Independent variables are trunk postures (No bending vs. Bending to the LCG) and feet placements (Parallel vs. Right foot in front of the other vs. Right foot behind the other). Dependent variables are EMG amplitude average on six muscles and the EMG amplitude difference between right and left muscle group. Results indicate the phenomenon showing an amplitude increase in the left muscle group is equal to an decrease in the right one is observed in dynamic as well as static lifts, bending the trunk to the LCG increases amplitude discrepancy more than no trunk bending, and the amplitude discrepancy in one foot ipsilateral to LCG in front of the other foot is lowest among other foot postures. As bilateral EMG amplitude discrepancy increases total low back muscle fatigue, the strategical combination of no trunk bending and one foot close to LCG in front of the other is recommended for preventing elevated incidence of low back pain (LBP).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.32 no.2 s.57
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• pp.123-127
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• 2006

In this study, we evaluated the crow's fret of 95 Korean female by using mechanical assessments; Skin-Visiometer SV 600 and Dermascan C. Transparency profilometry (Skin Visiometer) were using a very thin skin print which allowed parallel light to pass through and was analysed immediately after production. High-frequency (20 MHz) ultrasonography (Dermascan C) enabled non-invasive evaluation in skin thickness and echodensity. We found a correlation between skin roughness and dermal density. Particularly, we showed a significant correlation between skin roughness (R2) and dermal thickness. Also, we demostrated a significant negative correlation between dermal density and dermal thickness (p < 0.05). Therefore, the ultrasonography system might be considered a very useful method in wrinkle evaluation with the transparency profilometry. Further study will be required.

• Journal of KIISE
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• v.43 no.4
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• pp.470-479
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• 2016

As the number of various types of media data such as UCC (User Created Contents) increases, research is actively being carried out in many different fields so as to provide meaningful media services. Amidst these studies, a semantic web-based media classification approach has been proposed; however, it encounters some limitations in video classification because of its underlying ontology derived from meta-information such as video tag and title. In this paper, we define recognized objects in a video and activity that is composed of video objects in a shot, and introduce a reasoning approach based on description logic. We define sequential rules for a sequence of shots in a video and describe how to classify it. For processing the large amount of increasing media data, we utilize Spark streaming, and a distributed in-memory big data processing framework, and describe how to classify media data in parallel. To evaluate the efficiency of the proposed approach, we conducted an experiment using a large amount of media ontology extracted from Youtube videos.

• Journal of Magnetics
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• v.4 no.1
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• pp.33-37
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• 1999

Unidirectional magnetic anisotropy field ($H_an$) was investigated for thin films of $CdCr{2-2x}In_{2X}Se_4 (0$\leq$x$\leq$0.2). This anisotropy originates from the microscopic anisotropic Dzyaloshinskii-Moriya (DM) interaction which arise from the spin-orbit scattering of the conduction electrons by the nonmagnetic impurities. This interaction maintains the remanent magnetization in the direction of the initial applied field. Then the single easy direction of the magnetization is parallel to the direction of the magnetic field. The anisotropy produced by field cooling is unidirectional I.e. the spins system deeps some memory of the cooling field direction. The chalcogenide spinel of$ CdCr_{2-2x}In){2X}Se_4$belongs to the class of the magnetic semiconductors. The magnetic disordered state is obtained when ferromagnetic structure is diluted by In. Then we have the mixed phase characterised by coexistence the magnetic long range ordering (IFN-infinite ferromagnetic network) and the spin glass order (Fc-finite clusters). The total magnetic anisotropy energy depends on the state of magnetic ordering. In our study we concentrated on the magnetic state with reentrant transition and spin glass state. The polycrystalline $ CdCr_{2-2x}In){2X}Se_4$ thin films were obtained by rf sputtering technique. We applied the ferromagnetic resonance (FMR) and M-H loop techniques for determining the temperature composition dependencies of Han. From the experimental data, we have found that Han decreases almost linearly when temperature is increased and in the low temperature is about three times bigger at SG state with comparison to the state with REE.