• Tunnel and Underground Space
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• v.16 no.2 s.61
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• pp.146-155
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• 2006

The target slope of this study, formed during the construction of highway, is the very high infinite slope where sliding began along the discontinuity. Although an attempt was made to stabilize the upper part of the slope by installing the rock anchors, large scale failure was occurred at the lower part if the reinforced area. Afterwards, subsequent failures were observed two times. To investigate the cause of the failure, residual shear strength was measured by performing the direct shear test of rock specimen of the site. The anchor design was based on the pull-out test. Considering the slope surface where the undulation was severe and the variation of strength was very large, buttressing was used to obtain the required anchoring capacity.

• Journal of Preventive Medicine and Public Health
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• v.20 no.1 s.21
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• pp.158-164
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• 1987

The purpose of this study is to analyze occupational history of coal miners with pneumoconiosis. In this study, occupational characteristics of 49 coal miners with pneumoconiosis were compared with those of 45 coal miners without pneumoconiosis but in similar age category($43{\sim}52$ years of age) based on interview survey. Various indices on occupational characteristics were developed for the following areas: duration of employment, perception of working condition, working density, dust concentration, temperature, humidity, and experience of respirator wearings. Perception of working condition were measured in 5 points scales but experiences of respirator wearing was measured in 3 points scale. Each index was multiplied by duration of employment. From the analysis, only the experience of respirator wearing showed statistically significant difference between the two groups. Therefore, respirator wearing seemed to be effective in reducing occurrence of pneumoconiosis.

• Journal of Preventive Medicine and Public Health
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• v.20 no.2 s.22
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• pp.247-254
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• 1987

Serum immunoglobulin(Ig)A, IgG, IgM, levels were measured in 99 coal workers' pneumoconiosis (CWP) patients and 12 healthy coal workers and 9 non-miners to compare with each group by the radiological categories, its complications and working period in coal mine. Serum were measured by nephelometry, The findings were as follows: 1) Serum IgA levels were significantly different between three groups of CWP patient, healthy coal worker and non-miner ($mean{\pm}standard$ deviation: $226.4{\pm}87.7,\;221.3{\pm}45.1,\;170.1{\pm}65.7$ respectively). 2) There were no significant differences of Ig levels among radiological categories of CWP. 3) There were no significant differences of Ig levels among simple pneumoconiosis and its complicated disorders. 4) The three Ig levels were slightly increased in the group of mining years less than 20 years (IgA: r=0.1869, p<0.10 IgG: r=0.2902, p<0.05 IgM: r=0.2889, p<0.05).

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.784-785
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• 2008

In general, in most case of high temperature superconducting (HTS) rotating machinery, HTS field coil is rotated. HTS homopolar motor field coil is nat necessary to be rotated and the torque of motor is not strongly related with the field coil. Therefore, HTS homopolar motor has a superior mechanical stability comparing with other HTS rotating machines. These advantages can make the design of HTS field coil and cryostat much more simple. In this paper, HTS field coil was fabricated and tested. Before test, authors habe estimated the critical current of HTS field coil at 77K by simulation using FEA (Finite Element Analysis) software and power law equation. The experiment details and results are presented in this paper, and discussed. The field windings are made with HTS Bi-2223 wire which operates at 77K.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.792-793
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• 2008

This paper deals with the temperature calculation using equivalent thermal network for surface mounted permanent magnet synchronous motor(SPMSM) under the steady-state condition. In the equivalent thermal network, heat sources are generated from copper loss and iron loss. Heat transfer consists of conduction, convection and radiation. However, radiation is neglected in this paper because its effect is much smaller than others. Although the heat transfer coefficient in conduction use material property, heat transfer coefficient in convection is difficult to measure due to the atmosphere and ambient condition. Temperatures of each region in SPMSM are measured by thermocouple in operating condition and the thermal resistances of convection are calculated by kirchhoff's current law(KCL) and experimental result. In order to verify the validation and reliability of the proposed equivalent thermal network, temperature which is calculated other load condition is compared with experimental results. Accordingly, temperatures of each region in other SPMSMs will be easily predicted by the proposed equivalent thermal network.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.756-757
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• 2008

Interior permanent magnet synchronous motor (IPMSM) which has high power density is usually applied to traction motor for hybrid electric vehicle. In order to analyze characteristics of IPMSM, d- and q-axis equivalent circuit analysis is generally used. However, the line current of IPMSM calculated by d- and q-axis equivalent circuit analysis differ from measured value. This error is mainly appeared under the flux weakening control. In order to reduce the error between calculated and measured line current, no-load linkage flux which is calculated with considering saturation of magnetic core and armature reaction is applied to characteristic analysis. The result of line current calculated by the method dealt with in this paper is verified by comparison with experimental results.

• Journal of Korean Library and Information Science Society
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• v.39 no.1
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• pp.119-138
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• 2008

This study is to analyze factors affecting the quantitative size of interlibrary loan service in 22 national and public university libraries of Korea in 1992-2006. The results of this study are summarized as follows: The factors related to interlibrary loan service showed a positive effect on the number of lending and borrowing cases, in addition to showing a highly positive correlation with them on the whole. And the most influential factors of them on the number of lending and borrowing cases showed as follows: On the number of lending cases, 'number of graduate students'; on the number of borrowing cases, 'volumes loaned' and 'number of undergraduate students'.

• Journal of Korean Library and Information Science Society
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• v.6
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• pp.105-140
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• 1979

This study is an attempt to present a model of the effective service area for branch library system planning in Dae Gu city as one of large urban public libraries in Korea. This model is built up through the analysis of the distribution of population and characteristics of community structure, based on the standard for the branch library system of a public library. The results are summarized as follows: 1. Under the circumstances of this country, each radius of the effective service area for branch libraries are as follows; $1{\sim}1.5km$. is adequate for the central library and major branches; 1km. for neighborhood branches; $0.5{\sim}0.8km$. for sub-branches. 2. Population within the radius of the effective service area of a given branch may range from 80,000 to 100,000 for major branches, from 50,000 to 60,000 for neighborhood branches, and from 20,000 to 30,000 for sub-branches. 3. The radius of the outer boundary for the effective service area may be between 4km. and 5km. from the heart of the city, and the inner boundary, 13.km. 4. Areas with the radius between 2km. and 3km. from the heart of the city may be selected as the most effective locations for branch libraries, and between 3km. and 4km. as the next priority. 5. The number of service areas may be 14, that is, 7 major branches(Sinam, Sinchun, Susung, Daemyung, Naedang, Dalsung, Rowon), 2 neighborhood branches (Pyungri, Nambu), and 5 sub-branches(Chimsan, Sangiuk, Bongduk, Hyomok, Dongchon)

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.171-176
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• 2000

As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the aging evaluation technique by the BI method. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.447-450
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• 2002

A study on control of BLDC Is studying In progress, because of radical increase of survo motor at industrial machine and home machine. Nowaday, we study on control of BLDC, because of radical increase of survo motor at Industry and home. Although control ratio and output of the unit volume are good than the others , BLDC motor demands high cost. Therefor, the study on low cost BLDC have square wave back-emf is studing in progress. Therefor, BLDC Motor was studied to reduce high cost that have square wave back-emf at recently. This paper shows that BLDC Motor, developed highly responsility by using Genetic Algorithm(GA) that the advantages of learning ability, Also, this paper shows experiment and simulation at 200W BLDC that have squarewave back-emf by using Genetic Algorithm. At the result of this methods, the study prove experiment's right.