• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3115-3123
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• 1993

This paper presents a real-time correction method of the movemont errors of a translatory precision machine axis. This method is a null-balances technique in which two plane mirrors are used to generate an interferometric fringe pattern utilizing the optical principles of TwymanGreen interferometry. One mirror is fixed on a reference frame, while the other is placed on the machine axis being supported by three piezoelectric actuators. From the fringe pattern, one translatory and two rotational error components of the machine axis are simultaneously detected by using CCD camera vision and image processing techniques. These errors are then independently suppressed by activating the peizoelectric actuators by real-time feedback control while the machine axis is moving. Experimental results demonstrate that a machine axis can be controlled with movement errors less than 10 nm in vertical straightness, 0.1 arcsec in pitch, and 0.06 arcsec in roll for 50mm travel by adopting the real-time correction method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.390-396
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• 2010

An 80MHz surface acoustic wave (SAW)-based gyroscope utilizing a progressive wave was developed on a piezoelectric substrate. The developed sensor consists of two SAW oscillators in which one is used for sensing element and has metallic dots in the cavity between input and output IDTs. The other is used for a reference element. Coupling of mode (COM) modeling was conducted to determine the optimal device parameters prior to fabrication. According to the simulation results, the device was fabricated and then measured on a rate table. When the device was subjected to an angular rotation, oscillation frequency differences between the two oscillators were observed because of the Coriolis force acting on the metallic dots. Depending on the angular rate, the difference of the oscillation frequency was modulated. The obtained sensitivity was approximately 52.35 Hz/deg.s within the angular rate range of 0~1000 deg/s. The performances of devices with three IDT structures for two kinds of piezoelectric substrates were characterized. Good thermal stability was also observed during the evaluation process.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.846-848
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• 1995

Recently, direct drive AC servo motor and DSP is widely used in the factory automation and related field due to the enhanced control and digital technology. In this paper, position control of direct drive AC servo motor and numerical interpolation algorithms are studied using DSP for the future applications. In the direct drived motor control, encoder pulse is divided into the quadruple pulse for the higher resolution and high speed pulse(10MHz) is used as reference for the slower speed motor control (M/T method). As for the general position control, PI controller is adapted for position control. In the trajectory tracking numerical algorithm, interpolation of straight line and curve algorithms are studied for the realization of path following capabilities of XY table. As for the DSP, ADSP 2105 is selected for the economy and performance points of view.

• Journal of the Korean Solar Energy Society
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• v.38 no.2
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• pp.1-13
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• 2018

This paper deals with the NREL (National Renewable Energy Laboratory) 5-MW reference wind turbine. The controller which include MPPT (Maximum power point tracking) control algorithm and tower load reduction control algorithm was designed by MATLAB Simulink. This paper propose a tower damper algorithm to improve the existing tower damper algorithm. To improve the existing tower damper algorithm, proposed tower damper algorithm were applied the thrust sensitivity scheduling and PI control method. The thrust sensitivity scheduling was calculated by thrust force formula which include thrust coefficient table. Power and Tower root moment DEL (Damage Equivalent Load) was set as a performance index to verify the load reduction algorithm. The simulation were performed 600 seconds under the wind conditions of the NTM (Normal Turbulence Model), TI (Turbulence Intensity)16% and 12~25m/s average wind speed. The effect of the proposed tower damper algorithm is confirmed through PSD (Power Spectral Density). The proposed tower damper algorithm reduces the fore-aft moment DEL of the tower up to 6% than the existing tower damper algorithm.

• Korean Journal of Crystallography
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• v.6 no.2
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• pp.88-92
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• 1995

Higly pure silicon crystals with an almost perfect lattice structure constityte a powerful metrological tool. The streographic standard prohection for the (111) orientation of diamond structure found by the Laue method shows angles between net planes of 60°. This value is known to be certain to some 10-8 rad. We have made a six-faced silicon polygon, and the (220) lattice planes of the polygon act as a reference angular standard. The information of angles between lattice planes could be taken by the X-ray diffraction. The angle of the rotary encoder have been calibrated using the silicon angle standard. The X-ray optics was double crystal arrangement.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.51 no.1
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• pp.18-27
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• 2002

This paper presents an implementation of digital high-performance speed sensorless control system of an induction motor drives with Direct Torque Control(DTC). The system consists of closed loop stator flux and torque observer, speed and torque estimators, two hysteresis controllers, an optimal switching look-up table, IGBT voltage source inverter, and TMS320C31 DSP controller board. The stator flux observer is based on the combined current and voltage model with stator flux feedback adaptive control for wide speed range. The speed estimator is using the model reference adaptive system(MRAS) with rotor flux linkages for speed turning signal estimation. In order to prove the suggested speed sensorless control algorithm, and to obtain a high-dynamic robust adaptive performance, we have some simulations and actual experiments at low(20rpm) and high(1000rpm) speed areas. The developed speed sensorless system are shown a good speed control response characteristic, and high performance features using 2.2[kW] general purposed induction motor.

• Journal of the Korean Home Economics Association
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• v.45 no.1
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• pp.111-125
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• 2007

By examining the existing Galot products in the market, we aimed to discover areas for new development and lay out the foundational system for establishing a database(DB) of their pattern grading. For the analysis, the team focused mainly on Galot in forms of casual korean traditional clothes, since they have the largest market share. The main accomplishments from this research are as follows. First, because adult females are the largest segment to consider in deciding the size system for grading, we selected three sizes that have to be compatible with the KS Clothing Standardized Sizing. Second, for basic pattern grading, we applied the reference size indicated in KS Clothing Standardized Size, and also used half dart sloper and dartless sloper. Third, we categorized designs according to the presence or absence of a dart, the structure of closure, and the shape of the sleeve and neck. We indicated the grading points with numbers and body area in Korean to make it easier for the users to understand when using the computer system and doing manual work. To further increase the user convenience, we provided diagrams for categorized designs, pattern grading layout, and a table for calculated grading points variation.

• Korean Institute of Interior Design Journal
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• v.17 no.3
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• pp.77-85
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• 2008

The purpose of this study is to examine how the floor heating system is affecting to users in childeren's libraries. This study included the method that extracts the affordance of the floor heating system, after surveyed using behavior in children's libraries and referred to J. J. Gibson's affordance and surface concepts. As the positive affordance, it was grasped that the floor heating system promotes social relationships and affords various surfaces for library using, but also as the negative affordance, that hinders users in the public usings and the behaviors for reference and using. The behaviors of these various characters can be regarded as life behaviors resulted from the sitting life style and the natural using behavior can give to children emotional rest and autonomous reading experience. For the function as the children's library, the learning of sociality in the public building and the various reading space, the space planning of children's library should be done after the positive and negative affordances extracted from this study are reflected. The guidelines for space planning are summarized as the followings: the layout of book furniture, the shoe chest and the space around that, the furniture hight and children's eye level, and the practical using of the table for sitting life style.

• Journal of the Korean Society of Food Culture
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• v.11 no.1
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• pp.13-21
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• 1996

To find out the reference data of the school food service system, I serveyed four primary schools in Seoul, Korea and Nara, Japan respectively. The school children and their parents of whom arbitrary selected two classes among each primary school, were taken the questionaire about the present school food service system and their favorate food. The results were as follows; 1) 74.8% of Korean and Japanese children, and 92.5% of their parents were in favor of school food service. 2) Korean childrin wanted more amount of food and less salty taste. 3) Korean and Japanese children and their parents believed that the school food service system correct children's unbalanced diet. 4) Korean children wished more kinds of foods, western-styled cooking and that the food would be served in warm state. 5) Korean parents wanted that school food service system should be natural and better quality food material, and teacher should educate good eating habit. 6) Korean school children prefer yogurt, cuttle-fish, chicken, bean-curd, tomato, orange, dried laver, sweet potato, pine-mushroom in each food group. In conclusion, school food service system should be enough to meet children's good nutrition status, and the menu would be selected with consideration of children's preference and Korean traditional diet habit. Good table manner and eating all kinds of foods should be targht by school food service system as well as preparing good quality of food.

• Journal of Fashion Business
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• v.13 no.4
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• pp.21-36
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• 2009

The objective of the study is to create color plan for company D based on color images of the Bloomsbury Group paintings, which is an art institute based in Bloomsbury, London, a hometown of the company, to renew the traditional brand image of the company by blending fashion and art. This study analyzed 'D's previous F/W Color planning from 2003 to 2007 through NCS to understand characteristics of company D's color planning. It considered company D's color renewal concept by looking into Bloomsbury Group's backgrounds and pieces. Based on 2008-2009 F/W color trend and the analysis result, the study suggests a color plan with reference to a case study of the company D, for which I work as a colorist. The color renewal of the company D for 2008-2009 F/W season was categorized into theme I. Bloomsbury and theme II. Charleston for planning. The following table summarizes the result of 2008-2009 F/W season color plan with focus on development of new check and print patterns. The significance of the study can be found in that it advanced beyond the color planning stage to be applied to the actual renewal. Through a renewal of an existing brand, a fashion brand can be revitalized to have distinguished competitiveness.