• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.4
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• pp.100-109
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• 1997

Parameters in the internal combustion engines are variable depending on the operating points. Therefore, it is necessary to compensate for the uncertainties. Form this point of view, this paper gives a controller design method and a robust stability condition by LMI approach for engine torque control which satisfies the gives H$\infty$ control performance in the presence of physical parameter perturbations. To the end, the robustness of the system in the presence of perturbation is guaranteed in the all engine operating regions. Its effectiveness is demonstrated by simulation.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.69-74
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• 1991

The Variable Structure System(VSS) will be of much intrest to educators and design engineers who wish to demonstrate and investigate sophisticated position control methods and their applications. This paper describes DC motor position control by means of VSS concept. The control scheme is derived, implemented and tested in the laboratory where IBM AT computer has been used as a digital controller to control a representative servo system. The control system schematic is given and sample results are shown for illustration. This experiment may serve as a basis for further application of VSS.

• IE interfaces
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• v.24 no.3
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• pp.258-266
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• 2011

In this paper, we deal with a problem improving the productivity of a discrete production line for filling a printer cartridge with toner. We develop a new technology for controlling the weight of toner which must be filled in a cartridge and reform the current line based on our new control technology to result in more than 35% improvement of productivity as well as the control accuracy. In detail, first, we find a bottleneck process, the toner-filling process which gives the current production cycle times. Second, we divide the processing time of the bottleneck into several work elements and find the rotation time of an AC servomotor to be further reduced. Third, in order to reduce the rotation time, we develop a mathematical control-time model for determining the rotation time. Finally, we reform the current line partially as required by the change of the new control method.

• Journal of Powder Materials
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• v.11 no.1
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• pp.43-49
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• 2004

The electrical and thermal conductivity of W-Cu composites were investigated as a function of the W-particle size and W-W contiguity. Powder mixtures were prepared by ball milling or mechanical alloying process, and then sintered at various temperatures. The electrical conductivity of sintered composite was increased with decreasing W grain size. Dependence of electrical conductivity on the W grain size was explained by the W-W contiguity concept. The thermal conductivity was increased with increasing the temperature up to $600^{\circ}C$ but decreased at the temperature above $600^{\circ}C$ Also, thermal conductivity value was influenced by the W particle size. Change of thermal conductivity in W-Cu composites was discussed based on the observed microstructural characteristics and theoretical considerations.

• Journal of the Korea Computer Industry Society
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• v.9 no.4
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• pp.143-148
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• 2008

The major influence factor on carbonation of concrete structures is carbon dioxide concentration. In this study, carbonation analyses with carbon dioxide concentration were carried out by the developed program. Also, the service life of concrete strucures was predicted. The carbonation depth was 50mm in case that carbon dioxide concentration wad 0.1%. It was shown that the service life of concrete structures with 40mm cover depth was 67 years even though they had been exposed at carbon dioxide concentration 0.1% during 100 years.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.754-758
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• 1996

In this paper, a new method of position synchronizing control is proposed for multi-axes driving system. The proposed synchronizing control system is constituted with speed and synchronizing controller. The structure of synchronizing control system is varied by sign of synchronizing error. When a disturbance input becomes added to one axis, this axis becomes slave axis. The other axis is master axis. Therefore, master axis is not influenced by the disturbance. The speed controller of the first axis is designed by $H_{\infty}$ control theory. The speed controller of the second axis is designed by inverse dynamics of speed control system of the first axis. The speed control system designed with $H_{\infty}$ controller guarantees low sensitivity for the disturbance as well as robustness against model uncertainties. Especially, the synchronizing controller is designed to keep position error to minimize by controlling speed of slave axis. The effectiveness of the proposed method is successfully confirmed through several experiments.

• Journal of the East Asian Society of Dietary Life
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• v.27 no.2
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• pp.194-203
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• 2017

Mealworm, a type of edible insect, is a superior food material suitable for industrial products. In this study, four different defatted mealworm powders were prepared to determine proper manufacturing conditions. Solvent extraction method reduced lipid contents of mealworms more than pressed mealworms, and lowered lipid contents caused bright colors and good physicochemical properties for powders. In comparison, differences among milling machines used for making powders were strongly related with average size of particles. Meanwhile, the predicted shelf-life of defatted mealworm powders judged by accelerated experiments was 1 year or longer. To enhance shelf-life of mealworm powders, addition of tocopherol to mealworm powders at a concentration of 0.2% could intensify oxidative stability and microbial inhibition.

• Journal of the Korea Institute of Building Construction
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• v.9 no.1
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• pp.43-47
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• 2009

The most of waste foundry sands(WFS) have been discarded. It is very urgent for our country to make a study on recycling of WFS. The one of recycling method of WFS is using them as fine aggregate for concrete. This study provided the optimum amount of WFS and flyash when WFS and flyash were used together in concrete. The concrete made with 60% WFS fine aggregate replacement showed higher compressive strength, splitting tensile strength and modulus of elasticity than normal concrete. In the case that the flyash and WFS are replaced together, the compressive strength and splitting tensile strength were improved at flyash replacement ratio $10%{\sim}20%$ and WFS replacement ratio $40%{\sim}60%$. The increase of WFS and flyash replacement led lower air content. While the increase of WFS replacement led lower slump, the increase of flyash replacement led higher slump.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.527-530
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• 2002

A lot of efforts have been focused on the optimization of PIT parameters for Bi-2223/Ag wire. In this paper, initial annealing of Bi-2223/Ag wire to transform Bi-2212 orthorhombic from Bi-2212 tetragonal Precursor was investigated. This initial annealing step at low oxygen partial pressure were to transform Bi-2212 orthorhombic structure and to reduce the formation of second phases at superconducting wire. However Bi-2223 Phases were appeared at higher annealing temperature. Critical currents(Je) of Bi-2223/Ag tapes were sintered at low oxygen Partial pressure were higher than that of the wires sintered at atmosphere condition. In order to investigate the effect of rolling reduction ratio, Bi-2223/Ag HTS tapes were rolled with different reduction ratio. There were no clear difference of Je and filaments shape with various rolling reduction ratio.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.548-550
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• 2005

본 논문에서는 지문 인식을 하는데 있어서 특징점의 정보를 이용하여 지문을 정합하는 방법을 제안 하였다. 지문에는 중심점(core point), 삼각주(delta point), 분기점(bifurcation), 단점(ending point)들이 있는데, 본 논문에서는 먼저 poincare index를 이용하여 중심점을 검출한다. 검출된 중심점을 중심으로 하여 관심영역(ROI : region of interest)을 결정하여 영역내의 특징점들을 검출하여, 각 각 특징별로 분류한 다음 중심점과 특징점들과의 관계를 계산하여 지문 정합에 이용한다. 입력 받은 지문은 개개인 각각 양손 모두 10개의 손가락에서 센서의 누르기 압력을 다르게 하여 2번 입력 받아 사용하였다. 실험 결과 기존의 특징점 기반 알고리즘 보다 더 적은 영역에서 좀 더 정확하고 신뢰할 수 있는 지문 정합을 보여줌을 확인 하였다.