• Journal of the Korean Society for Precision Engineering
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• v.15 no.8
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• pp.60-70
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• 1998

A harmonic drive is compact torque transmission device with no backlash which is widely applied in industrial field to transmit torque precisely. However, one of the disadvantages of harmonic drives is the existence of mechanical flexibility caused by its structural properties, which imposes great limitation on designing precise controller This paper proposes a nonlinear controller for synchronous operation of DC servo-motors with harmonic drive, using Integrator Backstepping method. Furthermore, an alternative algorithm for serial type synchronous operation of multiple DC servo-motors is proposed. Simulation results by SIMULINK for proposed controller shows considerably small error and rapid approach to reference input, which can be adapted to industrial applications.

• The Korean Journal of Nuclear Medicine
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• v.38 no.4
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• pp.275-281
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• 2004

Compared with the earlier technique of dual photon absorptiometry (DPA) using $^{153}Gd$ radionuclide source, dual energy X-ray absorptiometry (DXA) has advantages of higher precision, accuracy and shorter scanning time. Despite the change from DPA to DPX, the nuclear medicine physicians has remained one of major suplier of this service due to long-standing use of DPA. Among many kinds of bone densitometries, DXA is the "gold standard" for the noninvasive diagnosis of osteoporosis. Especially there is no role for peripheral devices in the monitoring of patients on therapy. But, there are some areas of controversy related to the application of DXA, such as proper site of measurement, accurate interpritation, appropriate use of T-score, and the reference population young database. And the accuracy, precision, and quality control issues relating to bone density measurement are important subjects. To address these issues, the International Society for Clinical Densitometry (ISCD) has convened two Position Development Conferences and addressed official positions. This review deals the key elements of ISCD position paper and other important issues on the management of bone densitometry.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.492-492
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• 2009

Nowadays in Republic of Korea, there is no distinct reference for the related design technology of rotor blade of wind turbine. Therefore the optimum design and evaluation of performance is carried out with foreign commercial code softwares. This paper shows in-house code software that evaluates the aerodynamic design of wind turbine rotor blade using blade element-momentum theory (BEMT) and processes that is applied through various aerodynamics theories such as momentum theory, blade element theory, prandtl's tip loss theory and strip theory. This paper presents the results of the numerical analysis such as distribution of aerodynamic properties and performance curves using in-house code POSEIDON.

• Journal of Mechanical Science and Technology
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• v.20 no.11
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• pp.1834-1847
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• 2006

A robust minimum-time control (RMTC) strategy is addressed and it is extended to the dual-stage servo design. Rather than conventional switching type sub-optimal controls, it is a reference following control approach where the predetermined minimum-time trajectory (MTT) is tracked by the perturbation compensator based feedback controller. First, the minimum-time trajectory for a mass-damper system is derived. Then, the perturbation compensator to achieve robust tracking performance in spite of model uncertainty and external disturbance is suggested. The RMTC is also applied to the dual-stage positioner which consists of coarse actuator and fine one. To best utilize the actuation redundancy of the dual-stage mechanism, a null-motion controller to actively regulate the relative motion between the two stages is formulated. The performance of RMTC is validated through simulation and experiment.

• Asia pacific journal of information systems
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• v.10 no.1
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• pp.19-35
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• 2000

Data Envelopment Analysis(DEA), a non-parametric productivity analysis tool, has become an accepted approach for assessing efficiency in a wide range of fields. Despite of its extensive applications, some features of DEA remain bothersome. DEA offers no guidelines to where relatively inefficient DMU(Decision Making Unit) improve since a reference set of an inefficient DMU consists of several efficient DMUs and it doesn't provide a stepwise path for improving the efficiency of each inefficient DMU considering the difference of efficiency. We aim to show that DEA can be used to evaluate the efficiency of System Integration Projects and suggest the methodology which overcomes the limitation of DEA through hybrid analysis utilizing DEA along with machine learning.

• Journal of the Korean Regional Science Association
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• v.14 no.2
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• pp.107-126
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• 1998

Since the election of governors and mayors by vote, many local governments in Korea establish long-range plans for their regional development. The major purposes of the plans are to set up development path for their communities and to devise economic development strategies. But most of the plans established thus formulated by the same method utilized in centralized political regime. This method is considered no longer appropriate to devise the long-range development plans for local government especially in the era of globalization and localization, where local governments behave independently, where local governments behave independently competition. We suggest an alternative way to establish such plans, based on the method employed in business sector. The plans, formulated in this way, are called strategy oriented long-range development plans. The underlying logic for the plans is non-linear one. The plans are issue oriented and focus more on process than outcome. Given that these features are properly incorporated in the plans, we expect that the strategy oriented long-range development plans can be genuine guidelines for local economic development in the years to come.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.160-161
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• 2005

Using a Shack-Hartmann sensor, we construct an optical testing system measuring the wavefront error of small optical components. The systematic error of the sensor is compensated with a reference plane-wave system that produces almost perfect plane waves. Several types of lenses are tested using a point source that generates spherical waves emitted from a pinhole. The results of the optical testing obtained with the Shack- Hartman sensor are compared with those measured with Zygo interferometer.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.70-75
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• 2015

Fasciclin 1 (FAS1) is an extracellular protein whose aggregation in cornea leads to visual impairment. While a number of FAS1 mutants have been studied that exhibit enhanced/decreased aggregation propensity, no structural information has been provided so far that is associated with distinct aggregation potential. In this study, we have investigated the structural and thermodynamic characteristics of the wild-type FAS1 and its two mutants, R555Q and R555W, by using molecular dynamics simulations and three-dimensional reference interaction site model (3D-RISM) theory. We find that the hydrophobic solvent accessible surface area increases due to hydrophobic core repacking in the C-terminus caused by the mutation. We also find that the solvation free energy of the mutants increases due to the enhanced non-native H-bonding. These structural and thermodynamic changes upon mutation contribute to understand the aggregation of these mutants.

• Herbal Formula Science
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• v.5 no.1
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• pp.85-98
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• 1997

Samhwaja-hyangyakbang has been known as the book of herbalogy published by the man, Samhwaja. But there are no records about the additor, and the absence of the document, it is so difficult to be informed about the time when it published and other details. But in this document and Hyangyakgugeubbang, there are similar prescriptions to Sublingual Inflammation, Aphtose, Anthrax, Furoncle, Ulcer, Dysentery, etc. So the time it published is estimated to Goryo-dynasty Gojong epoch(1232-1251) when the Hyangyakgugeubbang was published. In addition, this document seems to be basis of Hyangyakjipseongbang, Because, Hyangyakjipseongbang quoted more than 140 provisions from this document. Prescriptions that are different from other books in dosage or taking method, took those of Biyebaekyobang. In explanation or classification of disease, this document almost copied those of Biyebaekyobang, so this document take Biyebaekyobang for origin and take Sikeuisimkam, Taepyungseonghyebang, etc, for reference.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.482-489
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• 2006

This paper presents the generalized dynamic modeling of self-excited induction generator (SEIG) using state-space approach. The proposed dynamic model consists of induction generator; self-excitation capacitance and load model are expressed in stationary d-q reference frame with the actual saturation curve of the machine. An artificial neural network model is implemented to estimate the machine magnetizing inductance based on the knowledge of magnetizing current. The dynamic performance of SEIG is investigated under no load, with the load, perturbation of load, short circuit at stator terminals, and variation of prime mover speed, variation of capacitance value by considering the effect of main and cross-flux saturation. During voltage buildup the variation in magnetizing inductance is taken into consideration. The performance of SEIG system under various conditions as mentioned above is simulated using MATLAB/SIMULINK and the simulation results demonstrates the feasibility of the proposed system.