• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.374-375
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• 2011

This paper presents a method to determine parameters of BTB (back-to-back) converters in terms of the enhancement of interface flow margins. Interface flow margin is by definition a measure of how much active power can be transferred from the external areas to the study area with the fixed load demand, and it is mainly constrained by system voltage stability. BTB converters are controllable equipments with the active power flow through them, and its DC link in fact can divide the AC systems at the location and hence can reduce the fault current level. This paper first cals margin sensitivities at the nose point of F-V curves and formulates an optimization problem to update the BTB parameters to improve the margins. This procedure is repeated performed until the required margin enhancement is achieved.

• IE interfaces
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• v.12 no.3
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• pp.458-467
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• 1999

In this paper, we analyze the calendaring operation in the process of paper manufacturing. Controllable parameters involved in the calendaring operation are the calendar material, temperature and pressure. Main objective of this paper is to find the robust design of these parameters which would provide consistent quality of paper in terms of the thickness, brightness, and roughness. We first use a split-plot design in the context of a central composit design for a preliminary analysis to find the proper calendar material. Next, response surfaces for the mean and variance of each quality attribute are fitted as functions of calender temperature and pressure. Bootstrap resampling approach is used to find the robust parameter design.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.105.1-105.1
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• 2011

To enhance the performance of photovoltaic a-Si:H solar cells with a hybrid-type light absorbing structure of single crystal silicon nanoparticles (Si NPs) in a-Si:H matrix, single crystal Si NPs were produced by laser pyrolysis. The Si NPs were synthesized by $SiH_4$ gas decomposition using a $CO_2$ laser. The properties of Si NPs were controlled by process parameters such as $CO_2$ laser power, reactive gas pressure, and $H_2/SiH_4$ gas flows. The crystalline properties and sizes of Si NPs were analyzed by High Resolution Transmission Electron Microscopy (HRTEM). The sizes of Si NPs were controllable in the range of 5-15 nm in diameter and the effects of process parameters of laser pyrolysis were systematically investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.725-728
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• 2001

We have fabricated thin films using the DC/RF magnetron sputtering of 74wt%Ni-l8wt%Cr-4wt%Al-4wt%Cu alloy target and studied the effect of the process parameters on the electrical properties for low TCR(Temperature Coefficient of Resistance) films. In sputtering process, pressure, power and substrate temperature, are varied as controllable parameter. The films are annealed to 400$^{\circ}C$ in air and nitrogen atmosphere. The sheet resistance, TCR of the films increases with increasing annealing temperature. It abruptly increased as annealing temperature increased over 300$^{\circ}C$ in air atmosphere. From XRD, it is found that these results are due to the existence of NiO on film surface formed by annealing. As a results of them, TCR can be controlled by variation of sputter process parameter and annealing of thin film.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1928-1937
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• 2003

Effect of elastic modulus mismatch on the contact crack initiation is investigated to find major parameters in designing desirable surface-coated system. Silicon nitride coated soft materials with various elastic modulus mismatch, E$\_$c//E$\_$s/＝1.06∼356 are prepared for the analysis. Hertzian contact test is conducted for producing contact cracks and the acoustic emission detecting technique for measuring the critical load of crack initiation. The implication is that coating thickness and material strength are controllable parameters to prevent the initiation of contact cracks resulted from the elastic modulus mismatch in the hard ceramic coating layer on the soft materials.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.351-352
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• 2015

Thyristor-controlled series capacitor (TCSC) is a power electronic-based device that provides a fast and controllable series compensation of transmission line reactance. To match with laboratory facilities and for further research initiatives, a practical laboratory scale TCSC was designed and fabricated in this paper. The TCSC parameters were designed based on the terminologies such as percentage of compensation, boost factor and resonance factor. According to the design parameters, a prototype laboratory scale TCSC with a constant reactance controller was fabricated and tested. The measured results from the laboratory scale TCSC demonstrate the ability of the TCSC to provide rapid control of series reactance of a transmission line.

• Structural Engineering and Mechanics
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• v.34 no.6
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• pp.739-753
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• 2010

Pointing to the design requirement of prestressed space grid structure being the target cable force, the pretension scheme decision analysis method is studied when there's great difference between structural actual state and the analytical model. Based on recursive formulation of cable forces, the simulative recursive system for pretension process is established from the systematic viewpoint, including four kinds of parameters, i.e., system initial value (structural initial state), system input value (tensioning control force scheme), system state parameters (influence matrix of cable forces), system output value (pretension accomplishment). The system controllability depends on the system state parameters. Based on cable force observation values, the influence matrix for system state parameters can be calculated, making the system controllable. Next, the pretension scheme decision method based on cable force observation values can be formed on the basis of iterative calculation for recursive system. In this way, the tensioning control force scheme that can meet the design requirement when next cyclic supplemental tension finished is obtained. Engineering example analysis results show that the proposed method in this paper can reduce a lot of cyclic tensioning work and meanwhile the design requirement can be met.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.860-864
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• 2008

In modern society, people tend to spend their time on various types of chairs. However, it is not easy for a designer to design a comfortable chair, because satisfaction with the chair depends not only on the quantitative elements such as size, but also on the qualitative element such as the user's feeling. To deal with these problems, there have been many studies on designing an ergonomics chair. In this paper, the hapticaided design (HAD) system was adopted to design the ergonomics chair. Based on the HAD system, the designer can experience whether the chair is comfortable or not through the haptic device, and also can modify the design parameters instantaneously. The haptic chair capable of controlling the design parameters in real time was proposed as a haptic simulator. The controllable parameters such as the seat height, reclining angle, stiffness of the backrest, and so on were selected based on the previous researches related to ergonomics chairs. It will reduce the development cost and time by replacing the process of making the real mock-up and prototype with the haptic chair.

• The Journal of Korea Robotics Society
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• v.4 no.3
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• pp.243-249
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• 2009

In modern society, people spend most of their time on various types of chairs. However, it is not easy for a designer to design a comfortable chair because satisfaction with the chair depends not only on the quantitative elements such as size, but also on the qualitative element such as the user's feeling. To deal with these problems, there have been many studies on designing ergonomic chairs. This paper proposes the haptic-aided design (HAD) system to design an ergonomic chair. Based on the HAD system, the designer can experience whether the chair is comfortable or not through the haptic device, and also can modify the design parameters instantaneously. The haptic chair capable of controlling the design parameters in real time was proposed as a haptic simulator. The controllable parameters, such as seat height, reclining angle, stiffness of the backrest, and so on were selected based on the previous research related to ergonomic chairs. The proposed methodology will help reduce the development cost and time by replacing the process of making the real mock-ups and prototypes with the haptic chair.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.56-60
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• 2003

In this work, we have fabricated thin film resistors using the DC/RF magnetron sputter of 51wt%Ni-41wt%Cr-8wt%Si alloy target and studied the effect of the process parameters on the electrical properties. In fabrication process, sputtering power, substrate temperature and annealing temperature have been varied as controllable parameters. TCR decreases with increasing the substrate temperature, but TCR increases over 300 [$^{\circ}C$]. The films are annealed to 400 [$^{\circ}C$] in air atmosphere, TCR increases with increasing the annealing temperature. The resistivity was 172 [${\mu}{\Omega}{\cdot}cm$] and 209 [${\mu}{\Omega}{\cdot}cm$] for the RF and DC as a sputtering power sources, respectively. Also, TCR was -52 [$ppm/^{\circ}C$] and -25 [$ppm/^{\circ}C$]. As a results of them, it is suggested that the sheet resistance and TCR of thin films can be controlled by variation of sputter process parameter and annealing of thin film.