• 한국정밀공학회지
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• 제17권3호
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• pp.158-164
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• 2000

In recent year, desire and request fer micro automation are growing rapidly covering the whole range of the industry. This has been caused mainly by request of more accurate manufacturing process due to a higher density of integrated circuits in semiconductor industry. This paper presents a six d.o.f fine motion stage using magnetic levitation technique, which is one of actuating techniques that have the potential for achieving such a micro motion. There is no limit in motion resolution theoretically that the magnetically levitated part over a fixed stator can realize. In addition, it Is possible to manipulate the position and the force of the moving part at the same time. Then, the magnetic levitation technique is chosen into the actuating method. However, we discuss issues of design, kinematics, dynamics, and control of the proposed system. And a few experimental results fur step input are given.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2005년도 추계학술대회 및 정기총회
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• pp.409-413
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• 2005

The logical analysis of data(LAD) is an effective Boolean-logic based data mining tool. A critical step in analyzing data by LAD is the pattern generation stage where useful knowledge and hidden structural information in data is discovered in the form of patterns. A conventional method for pattern generation in LAD is based on term enumeration that renders the generation of higher degree patterns practically impossible. In this paper, we present a new optimization-based pattern generation methodology and propose two mathematical programming medels, a mixed 0-1 integer and linear programming(MILP) formulation and a well-studied set covering problem(SCP) formulation for the generation of optimal and heuristic patterns, respectively. With benchmark datasets, we demonstrate the effectiveness of our models by automatically generating with much ease patterns of high complexity that cannot be generated with the conventional approach.

• 한국산림과학회지
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• 제94권2호통권159호
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• pp.82-89
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• 2005

The purpose of this paper is to investigate index numbers by conducting various comparisons among the widely used index formulas. The comparison is considered in three ways; 1) divergences in the magnitudes of index numbers due to the use of different formulas (Laspeyres, Paasche, Fisher, and Tornqvist); 2) the effect of selection of base year (fixed-year base vs. chain-type); 3) the degree of approximation of indirect to direct quantity index. The empirical application is to sawmills and planing mills industry of U.S. using a national time series data covering years of 1948-2000. The results show that the differences between Laspeyres and Paasche index can be substantial in some cases while the difference between Fisher and Tornqvist index is minimal. We also confirm that the selection of base year can cause significant divergences, especially when the variables undergo rapid price or quantity changes over time. We find that indirect quantity index approximates direct quantity index reasonably well in U.S. sawmill industry.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회 논문집(I)
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• pp.237-242
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• 1998

Covering mortar as a filter for permeable polymer concrete is necessary for good permeability from filtration continuously. Therefore, this paper is intended as an evaluation of the mechanical properties and permeability of permeable polymer concrete covered with polymer mortar as a filter. An optimum permeable polymer concrete is selected in various mix proportions, and three different polymer mortars were cast immediately following on the casting of the base permeable polymer concrete. And they are tested for compressive and flexural strengths, adhesion in tension, hardening shrinkage and permeability . From the test results, binder and filler contents in mix proportions had a great influence on the permeability of polymer concretes. The mechanical properties of permeable polymer concretes covered with polymer mortars using crushed stone are superior to other filters, and hardening shrinkage is the smallest in filters. It is apparent that adhesion between the base permeable polymer concrete and polymer mortar is affected by the degree of hardening shrinkage. From this study, proper mix proportions can be recommended in the consideration of properties of the permeable polymer concrete.

• 한국응용과학기술학회지
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• 제37권5호
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• pp.1248-1256
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• 2020

In this study, the polyurethane resin was synthesized by applying PTMG and DMBA of different composition ratios for the synthesis of water-dispersible polyurethane used in wound coating resin. The varying properties of the synthesized water-dispersible polyurethane were measured through tensile strength, elongation, and abrasion resistance analysis. As for the tensile strength measurement result according to the PTMG content, the sample with the highest reaction molar ratio was measured as 1.08 kgf/mm2 and the elongation was measured as 520%. As for the tensile strength result according to the DMBA content, the sample with the highest reaction molar ratio was measured as 0.51 kgf/mm2, and the elongation was measured as 435%. The degree of surface destruction by the abrasion resistance measurement was visually confirmed through SEM.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.974-979
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• 2008

The purpose of this study was to evaluate the effect of vegetation on the cutting slope applied by vegetation system in the whole land. The engineering characteristics of slopes were investigated using the face mapping and physical tests. From the statistical methods, a relationship between a geologic stratum and degree of covering was independent. Therefore, the afforestation of slope was affected more by condition of vegetation as direction and opening of joints, and a topsoil state than by conventional classification of layer. It was concluded that the adjustable vegetation on the slope considering condition of geometric shape of slope, joint data and spontaneous type could make useful early afforestation.

• 물과 미래
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• 제6권2호
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• pp.19-29
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• 1973

The progressive contamination of water resulted from man's activity and the use of fertilizers is not restricted only to surface water, but also the shallow groundwater is affected. This type of groundwater contamination is mainly restricted to areas composed of permeable, nonconsolidated sediments forming a shallow aquifer. The chloride and the sulfate resulted from man's activity and the use of fertilizers were measured to study the variations of the groundwater contamination. In general, (1) When water level rises, the rate of groundwater contamination becomes less and when water level declines, the rate of contamination is increased. (2) The highly contaminated season is the early-summer and the less contaminated season is the winter or after rainy season. (3) The groundwater in weathering zone without covering layer. (4) The degree of contamination of wells is increased with the increase of well depth and lowing the water table, because of increasing contaminated water from enlargement of the area of influence of the well.

• Journal of Chest Surgery
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• 제55권3호
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• pp.246-249
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• 2022

Recurrent pectus excavatum (PE) after a Ravitch operation is not uncommon. Extensive costal cartilage resection from the previous Ravitch procedure can lead to an irregular, unstable chest wall depressions with a varying degree of deformity. The optimal approach to cover the chest wall defect and remodel the deformity, remains unknown. We report the case of a 27-year-old woman seeking surgery for the third time for recurrent PE. The patient presented with 2-time recurrent pectus excavatum following a failed Ravitch procedure and subsequent pectus bar repair. The entire chest wall reconstruction and remodeling entailed covering the chest wall defect with 2 titanium plates across both sides of the rib cage, and lifting and fixing the depressed chest wall with 2 parallel pectus bars.

• 복식문화연구
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• 제8권3호
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• pp.460-476
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• 2000

The purpose of this study was, accordingly, to examine male college student's general body consciousness and their actual condition of wearing clothing, as it's assumed that clothing, which everyone must always wear, might be effective in making up for the physical defect. The findings of this study were as follows : 1. Male College Students'Body Consciousness : They expressed some dissatisfaction with their own body, and they were most discontented with their height, among their bodies. They thought of the western-style shape as an ideal one, as what's considered by them to be ideal was thinner a little than them, being taller with wider shoulder, longer legs, smaller and white face. 2. Male College Students'Characteristics of Clothing Purchasing Behavior : In purchasing clothing, male college students were slightly sensitive about the physical part with which they wasn't satisfied. The clothing pattern preferred by them was an abstract one, and their favorite color was white or black. The greatest number of them put most emphasis on design in buying clothing, and they purchased clothing mainly at special fashion shop. On the whole, they showed an affirmative response toward wearing Korean costume, and they also had a positive opinion about the purchase of reformed Korean dress for everyday life. 3. Male College Students'Characteristics of Wearing Clothing : They appeared not to consider making up for physical weakness. Male college students favored aloha shirt and trousers when they went out. Male college students purchase clothing in consideration of individual, manly, classical, tender, or comfortable factors. 4. Relationship of Body Consciousness to Wearing Behavior : The degree to which they considered covering up physical weakness in wearing clothing was examined, by dividing them into two groups : one was a group that thought their own shape normal, and the other was a group that didn't think of their own shape as normal. As a result, both groups appeared not to consider covering up physical weakness.

• 한국환경복원기술학회지
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• 제6권6호
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• pp.56-71
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• 2003

Waste landfills have been the center of environmental problems and they must be restored due to environmental pollution, disgusting landscape, and cost of management. It is suggested that they be recycled urban space as cities expand. Specially, nonsanitary waste landfills which have no pollution prevention facilities cause serious problems. Restoring the landfills as parks and golf courses, so on makes more benefits because of cheap use land, closeness to urban area, flat topography applicable to parks and golf courses, and high land values after restoration and the changes to local recreation sites. Restoration of waste landfills is a complex, costly, and interdisciplinary work. But, the waste landfill is a manmade ecosystem. Control, restoration and postmanagement of waste landfills are very important problems. The role of vegetation prevents soil erosion, reduces soil water storage, and obstructs leachate seepage. Early restoration makes derelict lands into man park artificially geared to soil, vegetation, landforms and hydrology. But, Ideal restoration is to make stable ecosystem nature-friendly and compatible with surrounding landscape without more management. Landscape is structured hierarchically with patches and stands as small components and forms forest as large components. Therefore, landscape formation of the waste landfills needs much restoration process. There are many ecological restoration techniques for the waste landfills. Those are divided into artificial and natural methods. The artificial method is anthropogenic plantings while the natural method is to trigger and use succession processes. The most important thing in the restoration of waste landfills is to consider the final restoration objectives of each waste landfill. According to these objectives, the depth of covering layer, planting degree, and structural design should be determined. The effective restoration methods should be selected of artificial and natural options.