• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.49-52
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• 1996

The control of diamond turning is usually achieved through a laser-interferometer feedback of slide position. The limitation of this control scheme is that the feedback signal does not account for additional dynamics of the tool post and the material removal process. If the tool post is rigid and the material removal process is relatively static, then such a non-collocated position feedback control scheme may surfice. However, as the accuracy requirement gets tighter and desired surface contours become more complex, the need for a direct tool-tip sensing becomes inevitable. The physical constraints of the machining processprohibit any reasonable implementation of a tool-tip motion measurement. It is proposed that the measured force normalto the face of the workpice can be filterd through an appropriate admittance transfer function to result in the estimated depth of cut. This can be compared to the desired depth of cut to generate the adjustment cotnrol action in addition to position feedback control. In this work, the design methodology on the admittance model-based control with a conventional controller is presented. Based on the empirical data of the cutting dynamics, simulation results are shown.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.951-959
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• 2013

In order to improve the speed performance of the direct drive mechanical systems, a comprehensive analysis of the velocity ripples of blushless DC motors should be required. Every motor has a certain level of torque ripples when it generates power, and the generated torque ripple also makes the velocity ripples in the final output stage in speed control system. In this paper, a novel algorithm for reducing velocity ripples is proposed based on the modeling of torque ripples for BLDC motors. Various algorithms have been made for torque ripples, but usually they should be installed inside the amplifier logic, result in the difficulties of flexibility for various kinds of torque ripples. The proposed algorithm was developed for being ported in the controller not the amplifier, and it has the capability of the automatic compensation adjustment. The performance of the proposed algorithm was verified by effective simulations and experiments.

• The Journal of the Acoustical Society of Korea
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• v.16 no.6
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• pp.12-18
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• 1997

Beamforming method has a limited spatial resolution because of finite aperture size, so that the estimated source distributions are smoothed within the resolution. Especially for low frequency noise such as mechanical noise, this limitation often diminishes the direct use of beamforming method. In this study, the relation between smoothed beamforming and radiation power distribution of plate has been addressed. By adjustment of aperture size of array, the smoothed beamforming power shows radiation power distribution of plate. Numerical simulations are carried for simply supported plate.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.5
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• pp.19-26
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• 1972

A newly developed quartz frequency modulator utili3ing a V. V. C. diode is briefly described. Its electrical characteristics-including modulation linearity, modulation distortion, and carrier frequency stability depending upon the variation of the environmental temperature and the applied power voltage, etc.-are suitable for the modulator of a mobile or a portable F.M. transmitter according to the experimental results. The excellent over-all electrical characteristics were proved from the experimental development of the two kinds of transceivers. One is the single channal transceiver which contains a direct frequency modulator at the carrier frequency of 52.750 MHg. The other is the dual channel transceiver (the frequencies are selected from about 40 channels without tuning adjustment) whose operational frequency is composed of a modulated frequency of 10.7 MHz and the frequency generated at a channel control oscillator, As mentioned above, it is realized that the electrical characteristics of this modulation method are suitable for portable F. M. transceivers.

• Journal of Korean Society of Rural Planning
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• v.3 no.2
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• pp.90-101
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• 1997

The objectives of the study are to identify the issues and problems encountered in Korea's current integrated rural regional development(IRRD) program and to suggest policy remedies to cope with them. Secondary data and materials ate mainly used for the study. Since the mid-1980s, rural settlement planning has been carried out in the Republic of Korea, In the planning process,'scale of economy'perspectives and settlement policy have been emphasized for increasing the efficiency of investment. During the 1990s, rural settlement and major village development projects have been implemented under the rural structure transformation programs. Agricultural structure adjustment projects for land consolidation and sizable farming have been separated from the rural settlement and mojor village development projects. Based on the evaluative analysis for the rural structure transformation policy and program, some problematic issues were raised as follows: (a) lack of integrative control function in the program'(b) weak linkage between living environment improvement and agricultural development projects: and (c) lack of comprehensive village development planning and implementation system. The policy issues to solve the problems were suggested as follows: (a) adoption of bottom-up approach in new IRRD planning and project system : (b) projection of comprehensive development planning and project at the village level; and (c) introduction of new regional agriculture development projects such as direct payment system for farming in less favorable areas and organic farming.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.117-120
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• 2005

The business market of architecture has got a system that controls a deposit according to the price function. This system is written on a law of contract about countries. So the main body of construction has to make a reasonable contract. This study is written about a rate of numerical index on controling a deposit. We tried to fine problems and solutions of labor expenses, instrument costs and material costs which is so big and changable on the construction market Labor expenses are expressed according to the rate of construction scale between direct and indirect cost that applies ability of works. Instrument costs are expressed according to an output method of a unit price annually and a weight allowance of local instrument conditions and use frequence. The last material costs expressed according to a local weight allowance make a decision of the material cost index. They applies locally relative index more than absolute one on what uses the price rate of producers and importations. This solutions are not enough to apply to the real market, so it needs to exam and to be on the market after a feasibility study.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.83-89
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• 2017

Due to the time-dependent properties of materials, structures, and loads, accurate time-dependent effects analysis and precise construction controls are very significant for rational analysis and design and saving project cost. Elevation control is an important part of the time-dependent construction control in supertall structures. Since supertall structures have numerous floors, heavy loads, long construction times, demanding processes, and are typically located in the soft coastal soil areas, both the time-dependent features of superstructure and settlement are very obvious. By using the time-dependent coupling effect analysis method, this paper compares Shanghai Tower's vertical deformation calculation and elevation control scheme, considering foundation differential settlement. The results show that the foundation differential settlement cannot be ignored in vertical deformation calculations and elevation control for supertall structures. The impact of foundation differential settlement for elevation compensation and pre-adjustment length can be divided into direct and indirect effects. Meanwhile, in the engineering practice of elevation control for supertall structures, it is recommended to adopt the multi-level elevation control method with relative elevation control and design elevation control, without considering the overall settlement in the construction process.

• Korean Journal of Acupuncture
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• v.22 no.4
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• pp.169-174
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• 2005

Objectives : Functional Cerebrospinal Therapy (FCST) is a new physiologic therapeutics developed in Korea as a meridian yinyang balance approach. The theory of yinyang balance has been at the core of health enhancement approach of meridian and acupuncture medicine ever since its start. Methods : Introductory overview of FCST is presented in relation with meridian yinynag balance theory. Results : As the temporomandibular joint (TMJ) and related tissues have direct interconnection with brainstem proprioceptive or motor systems and the face is where all the meridians converge, FCST applies a fine adjustment of the posture of TMJ as a treatment tool for neurologic conditions or meridian imbalances. Conclusions : Highly sophisticated diagnostic and therapeutic techniques to adjust various subset aspects of yinyang balance are developed within FCST, which is supposed to be one of major contributions to natural healing.

• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.156-161
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• 2015

In this paper, we present simulation results obtained using SILVACO TCAD tools for a 3-D silicon on insulator (SOI) n-FinFET structure with a gate length of 8 nm at 300K. The effects of variations of the device’s key electrical parameters, such as threshold voltage, subthreshold slope, transconductance, drain induced barrier lowering, oncurrent, leakage current and on/off current ratio are presented and analyzed. We will also describe some simulation results related to the influence of the gate work function variations on the considered structure. These variations have a direct impact on the electrical device characteristics. The results show that the threshold voltage decreases when we reduce the gate metal work function Φ_m. As a consequence, the behavior of the leakage current improves with increased Φ_m. Therefore, the short channel effects in real 3-D FinFET structures can reasonably be controlled and improved by proper adjustment of the gate metal work function.

• Korean Journal of Agricultural Science
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• v.28 no.1
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• pp.48-58
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• 2001

This study was conducted to investigate the effects of environmental sound rice farming method on the productivity of rice industry which may result in impacts on the staple food securities. Recently fanners have been concerned about adopting new rice cultivation method such as organic and low input farming system in which fertilizer and pesticide can be substantially reduced so as to alleviate the burden of agro-ecosystem. However, It has been argued about whether or not there are negative impacts on the self sufficiency rate of food, income of farm household and technological adaptability. Therefore this study examined the productivity trend of environmental rice farming system and predicted the long term rice self-sufficiency rate when environmental rice farming system are adopted by assuming various scenarios. It was estimated that rice self-sufficiency rate can be decreased up to 52.2% by 2010. Based on the analysis of results, policy recommendations for environmentally sound rice farming were suggested as follows: 1) gradual adopting and transferring of environmental rice cultivation method, 2) increasing profitability of rice growing fanners 3) developing the farm level technology specific to Korean farming condition, 4) institutionalization of direct payments for encouraging environmental rice fanning.