• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.3
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• pp.284-291
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• 2016

In order to provide a diagnostic basis for predicting the possibility of the self-correction of ectopic first permanent molars, differences among normal eruption, reversible and irreversible ectopic eruption of maxillary first permanent molars were retrospectively analyzed. The angles of the long axes and the occlusal lines between the maxillary first permanent molar and the adjacent tooth were measured by panoramic radiographs. The occlusal relationship of second primary molars was also investigated. There is a statistically significant difference between the ectopic eruption group and normal group (p < 0.05), but not between the reversible and irreversible ectopic eruption groups (p > 0.05). The angles between the second primary molar and the first permanent molar, the second primary molar and the second permanent molar in ectopic groups showed a smaller degree than those of the control group. Mesial step was found more frequently in the ectopic eruption group than the normal group. In conclusion, the angulation of the first permanent molar and tooth germ of the maxillary second permanent molar showed close relation with ectopic eruption of the maxillary first permanent molar and ectopic first permanent molar is likely to occur in class III patients with maxillary deficiency.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.35 no.6
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• pp.462-466
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• 2009

Purpose: Dentigerous cyst is the most common intra-osseous lesion of the jaw. Dentigerous cysts can cause delays in eruption of the affected permanent tooth in mixed dentition. It has been suggested that the affected permanent tooth could be erupted spontaneously after the dentigerous cyst was enucleated. But in some cases, orthodontic treatment or autotransplantation technique is known to be required. This study reviews previously performed prognoses of affected permanent teeth, which will lead to a more efficient treatment plan. Patients and Methods: With 28 patients who have undergone cyst enucleation and 10 patients who have undergone autotransplantation, the prognosis of permanent teeth was observed. Results: After cyst enucleation, spontaneous eruption of a permanent tooth was observed in 56.3% patients, orthodontic treatment was performed in 25% patients. The success rate of autotransplantation was 60.0%. Discussion: The first choice for treatment of dentigerous cyst in mixed dentition is to guide spontaneous eruption of permanent teeth. For cases without enough eruption space, the orthodontic treatment should be considered. Autotransplantation should be considered when the spontaneous eruption is not expected. It should be considered that the rate of successful autotransplantation is decreased on maxilla anterior area.

• International Journal of Highway Engineering
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• v.13 no.4
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• pp.41-50
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• 2011

It is well-known that pavement is easily damaged by several factors including permanent deformation and fatigue crack, causing service life of the pavement to be shorter than expected. It is very important to predict amount of permanent deformation for designing pavement and developing design method of pavement. A new model of permanent deformation of pavement materials based on concept of shear stress ratio has been proposed because the lower pavement materials are highly affected by shear strength of the material. In this study a large repetitive triaxial load test has been adapted for performing test of permanent deformation of crushed subbase materials. The test procedure which includes concept of shear stress ratio has been newly developed. Several important model parameters can be obtained from the test that can be used for making correct permanent deformation model of the material.

• Progress in Superconductivity
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• v.12 no.2
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• pp.93-98
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• 2011

Pinning force is the mechanism between a superconductor and a permanent magnet and it provides a stable levitation. However, when external force greater than the pinning force such as the earthquake exerts, the levitated object may lose the levitating characteristic. In order to achieve more stabilized levitation, the copper plate was inserted in between a superconductor and permanent magnets. And by applying the eddy current effect caused from the relationship between a copper plate and permanent magnets, more stabilized levitation can be established. In this study, an optimized design was found based on various configurations of permanent magnet's polarity, thickness and area of copper plate, and the gap distance between copper plate and permanent magnet. As results, higher eddy current value was obtained at where the change of polarity exists in permanent magnet configuration, and the highest eddy current value was observed at the copper plate thickness of 5 mm and the area of 80 mm ${\times}$ 80 mm. From the resulted optimized conditions above, which are 7 mm gap distance between a superconductor and permanent magnets and 80 mm ${\times}$ 80 mm ${\times}$ 5 mm dimension of a copper plate, the stiffness value was 65 % increased comparing to without any copper plate insertion.

• Journal of the Korean housing association
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• v.18 no.5
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• pp.73-84
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• 2007

Permanent rental housing, the construction of which was strongly financed by the central government, is regarded as a social housing for those who fall within the lowest income bracket. Differing from "public rental housing", offered to tenants for sale after a five year rental period, this type of housing is intended for rental use on a long-tenn basis. At present, about 190,000 permanent rental housing units exist in Korea. According to a statistics, 15.6% of its residents did not pay their management fee and rental payment in 4 or more months in 2005, which places stress on the housing management. Based on the "eviction condition" stipulated in the tenancy agreement for permanent rental housing, a householder owning assets or a vehicle which is not used as his means of living, who is overdue with his management fee and rental payment for a long time, may be evicted from the house. However, there are many conflicts and problems between administrators/housing managers and residents in the process of enforcing this regulation. The purpose of this study is to explore the key issues associated with the present situation and the reasons why so many management fee and rental payment for permanent rental housing are overdue. For the purpose of research, data were collected from 10,990 permanent rental housing residents nationwide via a questionnaire survey in February 2007. One third of the respondents had an experience of more than 2 months overdue since they have moved in current residence. For further analysis, the respondents were divided into three groups, based on their working ability. The major finding showed that the group of respondents who have working ability required a more practical plan, such as employment, to have a sustainable life, while the other group of no labor force indicated a need for more housing allowance from the government. To suggest more specific alternatives for the subject of housing payment overdue, further comparison study should be performed between the residents of permanent rental housing and other low income tenants in private housing sector.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.146-153
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• 2005

In a permanent magnet brushless dc motor, cogging torque is produced by the magnetic attraction between the rotor mounted permanent magnets and the stator teeth. This always produces a pulsating torque ripple resulting in vibration and acoustic noise, which is detrimental to the motor performance. This paper deals with the analytical prediction of cogging torque and the various cogging torque minimization techniques as applied to a permanent magnet brushless dc motor.

• Journal of the Korea Institute of Building Construction
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• v.4 no.4
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• pp.135-142
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• 2004

The purpose of this study is to predict remodeling timing of Permanent Rental Housing through historic data and cash flow analysis. For this aim, the study has estimated cash flow of Permanent Rental Housing considering initial construction costs, government supporting fund, rental incomes and maintenance expenses. Based on the expected cash flow analysis, reasonable remodeling timing is predicted for Permanent Rental Housing. The results of this study are as follows: (1) it is analyzed that building a8e of about 27 years is the best time for remodeling because cumulative surplus amounts reach maximum level, (2) it is required that remodeling should be made before 34 years of age roughly because cumulative surplus amounts change into minus from this time.

• The Journal of the Korean dental association
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• v.11 no.12
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• pp.787-799
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• 1973

Surveying the calcification degree of permanent tooth crown in 719 Korean children (Male 387, female 332) from 2 to 10 years old by orthopantomograph, the author got the following results. 1. Female was earlier than male in calcification of permanent teeth. 2. The results of the complete calcification of the permanent tooth crown were as follows. 3. The completion of calcification in the mandibular crown was seen earlier than that of the maxilla. 4. The order of calcification in permanent tooth crowns was as follows : 1 st molar, central incisor, lateral incisor, canine, 1st premolar, 2nd premolar, and 2nd molar. 5. The completion of calcification of the permanent crowns in Korean children was slightly retarded comparing with the Japanese and the American children.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.4
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• pp.469-475
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• 2014

This paper deals with the characteristics evaluations of PM magnetization using stator coil in a Post-Assembly Line Start Permanent Magnet Motor (LSPMM) using a coupled Finite Element Method (FEM) and Preisach modeling, which is presented to analyze the magnetic characteristics of permanent magnets. The focus of this paper is the characteristics analysis relative to magnetizing direction and quantity of permanent magnets due to the eddy current occurring in the rotor bar during magnetization of Nd-Fe-B.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1693-1699
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• 2016

The oscillation character of permanent magnetic motor is highly related to its slot-pole match. By calculating air-gap magnet field and radial electromagnetic force of 6-phase fractional-slot concentrated-winding permanent magnetic motor with slot-pole match of 48/44, 48/46, 48/50 and 48/52 under no load and load status, oscillation character of permanent magnetic motor is analyzed. A 20kW prototype with 48 slots and 44 poles is designed. With many sensors attaching to the corresponding parts, oscillatory acceleration is measured, and spectrum of oscillation frequency is recorded as well. The experiment results give proof to the analysis method for permanent magnetic motor oscillation in this paper.