• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.182-184
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• 2004

This paper presents a PI controller tuning method for high performance permanent magnet synchronous motor (PMSM) drives under load variations using clustering fuzzy algorithm. In many speed tracking control systems PI controller has been used due to its simple structure and easy of design. PI controller, however, suffers from the electrical machine parameter variations and disturbances. In order to improve the tracking control performance under load variations, the PI controller parameters are modified during operation by clustering fuzzy method. This method based on optimal fuzzy logic system has simple structure and computational simplicity. It needs only sample data which is obtained by optimal controller off-line. As the sample data implemented in the adaptive fuzzy system can be modified or extended, a flexible control system can be obtained Simulation results show the usefulness of the proposed controller.

• The Korean Journal of Applied Statistics
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• v.7 no.2
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• pp.313-321
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• 1994

When a single identified outlier in a small sample is presented, the samll sample properties of the MLE's and its jackknife estimators of the location and scale parameters in an assumed exponential model will be considered by the method of permanent theory.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2006.11a
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• pp.503-508
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• 2006

In recent, the concept of management is emphasizing the aspects of social welfare, especially in permanent public rental housing that most of the residents are very low income households. Although the quality of service for the residents of permanent public rental housing was improved comparatively, it still needs to continually change in response to the needs of residents. To figure out the better way of supporting the service for the residents of permanent public rental housing, this study examined the role and function of management office and the residents' perception. Two types of survey questionnaire (residents/staffs of management office) were developed for the research purpose. A sample of 89 management office staffs and 111 residents were used for the data analysis. The result showed that both of residents and management office staffs recognized the need for the participation of residents in management process.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.824-827
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• 2003

Recently, Development of Rare Earth Permanent magnet with the high remanence, high coercivity allow the design of brushless motors with very high efficiency over a wide speed range. Cogging torque is produced in a permanent magnet by magnetic attraction between the rotor mounted permanent magnet and the stator teeth. It is an undesired effect that contributes to the machines output ripple, vibration, and noise. This cogging torque can be reduced by variation of magnet arc length, airgap length, magnet thickness, shifting the magnetic pole and varying the radial shoe depth and etc. In this paper, Some airgap length and magnet arc that reduce cogging torque are found by FEM(Finite element method). The SPM type of high-capacity BLDC motor is optimized as a sample model.

• Transactions of Materials Processing
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• v.10 no.1
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• pp.30-34
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• 2001

The magnetic and metallurgical characteristics of Mischmetal(MM) -Ferroboron (FeB) Permanent magnets have been investigated by X-ray diffractometer, scanning and transmission electron microscope and vibrating sample magnetometer under hot-pressing and die-upsetting process. The best magnetic properties obtained in these studies were $H_c$=5.8 kOe, $B_r$=5.0 kG with $(BH)_{max}=7.6 MGOe for melt-spun ribbons, $H_c$=3.0 kOe, $B_r$=4.6 kG with $(BH)_{max}$=2.9 MGOe for hot-pressed magnets and $H_c$=1.8 kOe, $B_r$=5.5 kG with $(BH)_{max}$=4.1 MGOe for die-upset magnets. The higher magnetic properties in die-upset magnets were resulted from alignment of the c-axis along the die-upsetting direction.

• The Journal of the Korea Contents Association
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• v.14 no.7
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• pp.217-225
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• 2014

This study was carried out to find out the factors influencing the depression of residents in perment-rental apartments. The sample consisted of 446 residents in the ages of over 19 but under 60 years old living in permanent-rental apartments in G cities. 74.4% among the permanent-rental apartment residents were found to be in the state of depression with 33.9% in severe depression. From Enter multiple regression analysis, it is revealed that self-esteem, health condition, age, life satisfaction, and problem drinking are the critical factors influencing the depression of perment-rental apartment residents. It is recommended that depression prevention programs for the residents in perment-rental apartments be developed in consideration of the critical factors identified from this study.

• The Korean journal of internal medicine
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• v.33 no.6
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• pp.1150-1159
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• 2018

Background/Aims: The aim of this study was to assess the association between the number of existing permanent teeth and chronic kidney disease (CKD) in a representative sample of the elderly Korean population. Methods: A total of 2,519 subjects who participated in the Korean National Health and Nutrition Examination Survey were cross-sectionally examined. The number of existing permanent teeth was evaluated by clinical oral examination. CKD was defined based on definition and classification by Kidney Disease: Improving Global Outcomes (KDIGO) 2012 guidelines. Multivariable logistic regression analyses were performed controlling for age, gender, income, education, tooth-brushing frequency, periodontitis, state of dentition, smoking, alcohol consumption, hypertension, obesity, diabetes mellitus, and hypercholesterolemia. Subgroup analyses by age and gender were also performed. Results: The number of teeth was significantly associated with CKD after controlling for all potential confounders (adjusted odds ratio [AOR], 1.67; 95% confidence interval [CI], 1.04 to 2.70 for lower number of teeth; AOR, 1.59; 95% CI, 1.14 to 2.23 for moderate number of teeth). In the subgroup analyses, the association was highlighted in females aged 75 years over (AOR, 2.55; 95% CI, 1.05 to 6.20 for lower number of teeth; AOR, 1.95; 95% CI, 1.01 to 3.80 for moderate number of teeth). Conclusions: Our findings suggest that the number of existing permanent teeth may be associated with CKD among Korean elderly.

• Geomechanics and Engineering
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• v.2 no.3
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• pp.161-176
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• 2010

Discrete Element Method (DEM) simulations were developed to investigate the effectiveness of geosynthetic reinforcement and the effectiveness of maintenance techniques performed on a simulated ballast bed subjected to dynamic loading. The results from four samples subjected each one to a total of 425 load cycles are presented: one unreinforced and unmaintained sample, one unmaintained but reinforced sample, one unreinforced sample subjected to maintenance in the form of stoneblowing after 200 load cycles, and one unreinforced sample subjected to maintenance in the form of tamping after 200 load cycles. The obtained values of permanent deformation as a function of the applied number of load cycles for the four cases are presented together allowing a comparison of the effectiveness of each technique. Moreover, snapshots of the simulated track sections are presented at different moments of the simulations. The simulations indicated that the geosynthetic reinforcement may not be beneficial for the analyzed case while stoneblowing was the most effective maintenance technique.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.563-580
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• 1991

The purpose of this study was to investigate and compare the biomechanical properties of orthodontic rubber elastic materials. Latex bands, nylon-covered elastic threads and polyurethane-based elastic modules, delivering $205{\pm}10$ grams force at 30mm stretching state were selected and stored separately in 3 environments-air ($22{\pm}3^{\circ}C$), distilled water ($37{\pm}1^{\circ}C$), or natural saliva ($37{\pm}1^{\circ}C$). And, the amount of remaining force and permanent elongation of each sample were measured on Instron at interval of 1 hour, 6 hours, 12 hours, 24 hours, 1 week, and 2 weeks. So the data derived were analyzed statistically. The results were as follows: 1. Force decay and permanent elongation of all materials increased with time lapsed; elastic module, latex band and nylon-covered elastic thread in that order of the amount of force decay; elastic module, elastic thread, latex band in that order of the amount of permanent elongation. 2. Among environmental conditions, force decay and permanent elongation in natural saliva, most increased, and those in air, least increased. 3. There was a negative correlation between force decay and permanent elongation. 4. Force decay and permanent elongation were most affected by the material itself, time and environments in that order. 5. After 24 hours in saliva, the percentage of remaining force in elastic module was 51.9% (107.37grams); in latex band, 83.2%(172.62grams); in elastic thread, 85.0%(179.25grams). After 2 weeks in saliva, the percentage of remaining force in elastic module was 42.9%(88.75grams); in latex band, 74.5%(154.50grams); in elastic thread, 77.6%(163.75grams).

• Journal of Korean Society of Forest Science
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• v.99 no.5
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• pp.720-725
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• 2010

On the basis of vegetation data in the 9.12 ha (380 m ${\times}$ 240 m) permanent sample plot of the spruce-fir valley forest in Liangshui National Reserve of Xiaoxing'an Mountains, the study was conducted to evaluate spatial distribution pattern and spatial association by using point pattern analysis for living and dead trees of Larix gmelini by DBH size class. The number of L. gmelini were counted as 59 living stems/ha (6.42 $m^2$/ha of basal area) and 34 dead stems/ha (2.86 $m^2$/ha of basal area). The distributional curve of diameter class exhibited bimodal shape. The analysis of spatial distribution patterns of all living larch stems noted the clumped distribution on the whole. The size of larch aggregates of dead stems was decreased as diameter class was increased. The distribution of dead stems became gradually randomized with decreased clumped size as the scale increased. Living stems and dead stems of the larch had positive spatial association at most of scales, illustrating that the occurrence of mortality of the larch tree was closely related to the distribution pattern of living larch trees.