• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.482-487
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• 2001

This paper introduces a Lorentz force type four-pole self-bearing motor, where the new pole arrangement of a stator is intended to function both as a synchronous PM motor and as a magnetic bearing. The Lorentz force type has some good points such as linearity of control force, freedom from flux saturation, and high efficiency unlike conventional self-bearing motors. Mathematical expressions of torque and radial force are derived to show that they can be separately controlled regardless of rotational speed and time. To verify the proposed theory, a prototype is made, where a ring-shape outer is actively controlled in two radial directions while the other motions are passively stable supposing the radial stability. Through some experiments, it is shown that the proposed scheme can provide high capability and feasibility for a small high-speed self-bearing motor.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.286-291
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• 2000

The finite element analyses of mechanical rubber components are executed to predict the behavior of deformation and stress distribution in destgn step. The non-linear properties of rubber which are described as strain energy functions are important parameters to design and evaluate rubber components. These are determined by material tests which are tension, compression and shear test. The behaviors of loads-displacements of rubber components such as a roll tubber spring and resilient ring and additional spring for railway suspension system are evaluated by using commercial FEA code. It is shown that the results by FEA simulations are in close agreement with the test results.

• Clean Technology
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• v.26 no.2
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• pp.102-108
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• 2020

In recent years, packed column has been widely used in separation processes, such as absorption, desorption, distillation, and extraction, in the petrochemical, fine chemistry, and environmental industries. Packed column is used as a contacting facility for gas-liquid and liquid-liquid systems filled with random packed materials in the column. Packed column has various advantages such as low pressure drop, economical efficiency, thermally sensitive liquids, easy repairing restoration, and noxious gas treatment. The performance of a packed column is highly dependent on the maintenance of good gas and liquid distribution throughout a packed bed; thus, this is an important consideration in a design of packed column. In this study, hydraulic pressure drop, hold-up as a function of liquid load, and mass transfer in the air, air/water, and air-NH₃/water systems were studied to find the geometrical characteristic for raschig super-ring experiment dry pressure drop. Based on the results, design factors and operating conditions to handle noxious gases were obtained. The dry pressure drop of the random packing raschig super-ring was linearly increased as a function of gas capacity factor with various liquid loads in the Air/Water system. This result is lower than that of 35 mm Pall-ring, which is most commonly used in the industrial field. Also, it can be found that the hydraulic pressure drop of raschig super-ring is consistently increased by gas capacity factor with various liquid loads. When gas capacity factor with various liquid loads is increased from 1.855 to 2.323 kg^-1/2 m^-1/2 S^-1, hydraulic pressure drop increases around 17%. Finally, the liquid hold-up related to packing volume, which is a parameter of specific liquid load depending on gas capacity factor, shows consistent increase by around 3.84 kg^-1/2 m^-1/2 S^-1 of the gas capacity factor. However, liquid hold-up significantly increases above it.

• Journal of the Korean Geographical Society
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• v.31 no.1
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• pp.49-67
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• 1996

On of Revolutionary changes of the commercial facilities is appearance of supermarket since the 1970's. It means modernization of retail establishment size. Simultaneously, and then path of distribution resulted in change. Namely, function of wholesale and retail is mixed, path of distribution is shortened, and then distribution function become more influential. By these changes, producer, manager and consumer can be benefit. That is, a change of commercial part is accurance to change of society and economy of region. The aim of the study is to examine commercial properties of supermarket in Kwangju city, and then, it is concerned with life of residents. Factor analysis is applied to the study. The results are as follows: Four factors are abstracted. The first factor of large explanation on properties of supermarket is accounted for years of management, land lent, number of establishments of wholesale${\cdot>$retail${\cdot>$service, age of manager, distance of neighbour residence, and so on. Namely, these may be regarded as commercial environmental feature. Moreover, regional distribution on the ground of factor score is concentrated on CBD and it's neighbour area, which are the areas of highest land lent in Kwangju city. The second factor is accounted for number of supermarket and number of population in each 'dong' (smallest factor-scored area is new housing complex in an outer ring of Kwangju. The third factor is accounted for number of workers, and size of establishment. Regional distribution is concentrated on neighbour of CBD and the outer ring area. These are scattered in contrast to the first and second factors which are continuous. The fourth factor is noted on a sale price of non-foodstuffs, that is, a feature of formation of goods. The highest factor score areas are the CBD, neighbour area of the CBD and a part of an outer ring area. On the other hand, the property of supermarket is preferred to 'the near distance' according to consumer's viewpoint. Furthermore, the location of supermarket, which is actually used by residents, is almost near residental area. It means that condition of location of supermarket is important in the distance of neighbour residence. Besides, supermarkets in Kwangju city are actually situated at residental area, that is, those locations in Kwangju city correspond to preference of consumer's viewpoint. Moreover, this result corresponds to the first factor of the analysis. Namely, the distance of property of supermarket from neighbour residence has very important effect on both of consumer and manager. In the end, supermarket is strongly related to life of residents. It means that supermarket is also responsible to quality of life. On the other hand, commercial facilities have been changed according to consumer's needs and social environments. For these reasons, commercial properties of supermarket must be reexamined in according to diverse commercial facilities and change of commercial environments.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.3
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• pp.13-24
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• 2000

In urban area, urban forests work as an ecological center that mitigates the environmental pollution of the area. In order to maintain the ecological function of a forest, the management method should be established based on ht through investigation of the vegetation structure of the forest. In this study, the vegetation structure of Namsan in Kyungju area was investigated in order to study the ecological value of Namsan and to suggest a desirable management alternative. 21 plots were selected as survey areas. Using the TWINSPAN technique, the forest of Namsan was classified into four communities: Quercus serrata community(I), Castanea crenata-Q. serrata-Q. mongolica community(II), Pinus densiflora community(III) and P. densiflora-P. rigida-Robinia pseudoacacia community(IV). The survey results were summarized by five: 1) the distribution of vegetation showed 2) P. densiflora was the absolutely dominant species in Namsan, 3) number of the average species was 12.6$^{\circ}$$\pm$3.1, 4) number of individual was 131.1$^{\circ}$$\pm$47.8 per a plot(100$m^2$), 5) the results of annual ring analysis revealed that the age of P. densiflora in Namsan was about 3 0$^{\circ}$~60$^{\circ}$years old. From the above results, it was found out that the forest has two problems. One thing is maintenance of P.densiflora against succession, another is artificial forest dispersion. The problems of Namsan forest management will be solved with further studies related.

• Clinical and Experimental Reproductive Medicine
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• v.18 no.2
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• pp.209-214
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• 1991

Endosalpingiosis is defined as the ectopic location of tubal epithelium. The term is purely descriptive and does not necessarily imply either the direct origin from tubal mucosa or the similarity of function. This study was performed to evaluate the clinical and pathologic characteristics of endosalpingiosis in the patients with endosalpingiosis proven by pathologic investigation. The medical histories and pathologic reports of 22 endosalpingiosis patients who received the laparotomy at Seoul National University Hospital from August, 1982 to December, 1990 were reviewed. The results were as follows: 1. Age distribution was from 26 to 46 years with the mean age of 34.0 years. 2. Twelve(54.6%) patients were nulligravida and the chief complaint of these patients was infertility(45.5%). 3. Six (27.3%) patients had the previous laparoscopic tubal sterilization by electrocautery or ring application. 4. Four (18.2%) patients had previous history of tubal pregnancy. 5. The most prevalent location of endosalpingiosis was the proximal segment of the salpinx, and the length of the proximal stump from the lesion was less than 1cm in 16(72.7%) patients.