• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.129-138
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• 2011

Construction methods for underground structure are classified as bottom-up, up-up, and top-down methods depending on the procedure of construction related to a superstructure. In top-down construction methods, building's main structure is built from the ground level downwards by sequentially alternating ground excavation and structure construction. In the mean time, the main structure is also used as supporting structure for earth-retaining wall, which results in the increased stability of the earth-retaining wall due to the minimized deformation in adjacent structures and surrounding grounds. In addition, the method makes it easy to secure a field for construction work in the downtown area by using each floor slabs as working spaces. However top-down construction method is often avoided since an excavation under the slab has low efficiency and difficult environment for work, and high cost compared with earth anchor method. This paper proposes a combined construction method where semi-open cut is selected as excavation work, slurry as earth -retaining wall and CWS as top-down construction method. In the case study targeted for an actual construction project, the proposed method is compared with existing top-down construction method in terms of economic feasibility, construction period and work efficiency. The proposed construction method results in increased work efficiency in the transportation of earth and sand, and steel frame erection, better quality management in PHD construction, and reduced construction period.

• Journal of Acupuncture Research
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• v.18 no.6
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• pp.171-187
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• 2001

Objective : Moxibustion has been proved efficacious for many diseases, but isn't widespread in the clinics due to a danger of skin burning, the smoke produced while burning a moxa combustion and so on. Therefore, another type of moxa that can be resolved these troubles is required. To improve the effect of moxibustion and develop the new thermal stimulating treatment, the performance of commercial moxibustion widely used are studied systematically and found out quantitatively. Methods : We have selected two types (small-size moxa A(sMA), small-size moxa B (sMB)) among small-size moxaes used widely in the clinic. We examined combustion time, various temperatures, temperature gradient in each period during a combustion of moxa. Results : 1. The combustion time in the preheating period appeared somewhat longer in sMA than in sMB. 2, The combustion time in the heating period appeared longer in sMA by 26% than in sMB. 3. The average temperature in the heating period was $37.6{\sim}37.8^{\circ}C\;in\;sMA\;and\;36.2{\sim}36.8^{\circ}C$ in sMB and the maximum temperature measured at a center of contact surface in sMA was $48.6^{\circ}C$, higher by over $2.8^{\circ}C$ than that of sMB moxibustion. 4. The average ascending temperature gradient in the heating period was $0.08{\sim}0.1^{\circ}C/sec$ in both moxaes, and the average ascending temperature gradient of heating period in sMB appeared larger. The maximum ascending temperature gradient appeared higher in sMB, and the time reaching maximum ascending temperature gradient appeared much earlier in sMA than in sMB. 5. The combustion time in the retaining period was around 100 sec in sMA and around 275 sec in sMB. 6. The average temperature in the retaining period was $42.2{\sim}46.0^{\circ}C\;in\;sMA\;and\;39.3{\sim}41.4^{\circ}C/sec$ in sMB. The minimum temperature in the retaining period was over $38.80^{\circ}C$ in sMA but just $34.7^{\circ}C$ in sMB. 7. The average descending temperature gradient in sMA was $-0.050{\sim}0.067^{\circ}C/sec$ and in sMB was $-0.030{\sim}0.037^{\circ}C/sec$ 8. The combustion time in the cooling period appeared longer over two times in sMA than in sMB, and the time which the cooling period (minimum temperature) finished at appeared later in sMB by 55 sec. 9. We classified the combustion process that the measured temperature rose over body heat($37^{\circ}C$) into the effective combustion period. The effective combustion time was 233.3 sec in sMA and 300.4 sec in sMB respectively, and was longer by about 29% in sMB. The average temperature and maximum temperature in the effective combustion time appeared higher in sMA. The time taken until the maximum temperature was reached was 225.1 sec in sMA and 244.5 sec in sMB, faster by about 20 sec in sMA. The maximum ascending temperature gradient during the effective combustion period appeared larger about 1.4 times in sMB, but the time when the maximum ascending temperature gradient happened was faster in sMA. Conclusion : It appears that sMB, compared with sMA, is proper if necessary to apply the long time and weak stimulus, because of the gentle stimulus during the relatively longer time. In contrast, sMA that the symmetrical combustion happened is proper if necessary to apply the short time and strong stimulus.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.597-600
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• 2001

In this paper, we evaluated the effect of accumulated charges on hydrophobicity of room temperature vulcanized(RTV) silicone rubber, which could improve the contamination performance of porcelain insulators, with uv radiation time. Outdoor insulating material could be charged by the corona discharge on field intensified area of insulator and discharge between the water drops. In addition, we performed the accelerated uv radiation on samples and investigated the change of charging decay with time. In this results, it is found that silica-like structure on the surface of RTV silicone rubber was formed by uv treatments and this layer have the characteristic of retaining the charges on surface for a long time. These charges have effects on its hydrophobicity and so adversely effects on contamination performance. Based on our results, we discussed the other degradation mechanism with well known ones.

• Fashion & Textile Research Journal
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• v.6 no.4
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• pp.511-514
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• 2004

We studied on the bleaching properties of silk fabric by vapor type ozone processing using ozone's strong oxidation instead of 28% $H_2O_2$ chemical treatment. When vapor type ozone processing was directly treated to fabrics retaining water to 50~70% pick up ratio, high concentration ozone was generated 14,000ppm(168 mg/h) approximately and finally its bleaching improved. The fabric's bleaching effect was improved because vapor type ozone generated the highest decomposition to oxidation of surface and inter molecules. The experiment revealed that fabric's bleaching was improved by change of the pick-up ratio of vapor type ozone processing. However, tensile strength and elongation were reduced by increase of time, and the time that was assumed as the most optimized time to minimize the reduction of fabric's tensile strength and elongation as well as maximizing the fabric's bleaching was 30 minutes.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.43-46
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• 2008

In Top-Down construction for underground structures, the placement of slab as a horizontal supporting member against lateral earth pressure is an important process in determining construction time and cost. Usually, a reinforced concrete perimeter girder distributes concentrated lateral loads from earth retaining structures such as Cast-in-place (CIP) piles. By combining the function of the R/C perimeter girder and horizontal slabs, the Opened Slab Method is efficient for reducing construction time by elimination of time-consuming formwork for traditional perimeter girders. The structural performance of the method is also discussed in this paper.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.106-109
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• 2001

In this paper, we have investigated the degradation of shed materials of outdoor insulators by UV-radiation by using corona-charging and XPS analysis. The accumulated charges on polymeric surface having intrinsic hydrophobic property have a negative impact on retaining its hydrophobicity. Therefore, shorter decay times of surface charges are preferred. The surface voltage decay on UV-treated silicone rubber and EPDM show a different decay trend with UV treated time. From the XPS analysis, the oxidized groups of silica-like structure in silicone rubber increase with UV treatment time. For EPDM, the oxidized carbon groups of C=O, O=C-O increase as elapse of UV radiation time. These oxidized surface for each material have different electrostatic characteristics, so deposited charges may be expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results is discussed.

• Fashion & Textile Research Journal
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• v.3 no.4
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• pp.362-366
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• 2001

We studied on the softness properties of polyester fabric by vapor type ozone processing using ozone's strong oxidation instead of 25% NaOH chemical treatment. When vapor type ozone processing was directly treated to fabrics retaining water to 40% pick up ratio, high concentration ozone was generated oxidation of 3~4% approximately in polyester fabrics and finally its softness improved. The fabric's softness effect was improved because vapor type ozone generated the highest decomposition to oxidation of surface and inter molecules. The experiment revealed that fabric's softness was improved by change of the time of vapor type ozone processing. However, tensile strength and elongation were reduced by increase in time, 60 minute was assumed as the most optimized time to minimize the reduction of fabric's tensile strength and elongation as well as maximizing the fabric's softness.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.85-97
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• 2005

Despite a number of advantages of reinforced earth walls over conventional concrete retaining walls, there exist concerns over long-term residual deformation when subjected to repeated and/or cyclic loads, especially when used as part of permanent structures. In view of these concerns, in this paper time-dependent deformation characteristics of geosynthetic reinforced soil under sustained and/or repeated loads were investigated using a series of plane strain compression tests on geogrid reinforced weathered granite soil specimens. The results indicate that sustained or repeated loads can yield appreciable magnitudes of residual deformations, and that the residual deformations are influenced not only by the loading characteristics but by the mechanical properties of geogrid. It is also found that the preloading technique can be effectively used in controlling residual deformations of reinforced soils subjected to sustained and/or repeated loads.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.4
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• pp.23-28
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• 2002

In this paper, we have proposed the hardware architecture which implements the algorithm for retaining the connectivity which prevents the disconnection in the gray-scale image thinning. To extract the skeleton from the image in a real time, it is necessary to examine the connectivity of the skeleton in a real time. The proposed architecture finds the connectivity number in the 4-clock period. The architecture consists of three blocks, PS(Parallel to Serial) Converter and Stare Generator and Ridge Checker. The PS Converter changes the 3$\times$3 gray level image to four sets of image pixels. The State Generator examines the connectivity of the central pixel by searching the data from the PS Converter. The Ridge Checker determines whether the central pixel is on the skeleton or not. The proposed architecture finds the connectivity of the central pixel in a 3$\times$3 gray level image in the 4-clocks. The total circuits are verified by the design tools and operate correctly.

• Journal of the Korea Computer Industry Society
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• v.2 no.12
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• pp.1557-1562
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• 2001

The echo response time has been a concern in the performance of the UNIX systems, a significant tail always appears in the distribution of echo response time, though the average echo response time is less serious. This paper addresses the issue of echo response times in the UNIX systems. We explain how the Fair Share Scheduler (FSS) works and explain why the FSS might cause excessive echo response times and show by analysis how echo response time reacts to key parameters under FSS. Finally, we present a recommended solution that should improve the echo response time drastically. This solution is a refined FSS which will overcome the echo response time problem while retaining the essence of the FSG. This will enhance the UNIX performance and productivity.