• Geomechanics and Engineering
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• v.14 no.1
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• pp.9-17
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• 2018

Brazilian splitting tests, uniaxial compression tests and triaxial compression tests are carried out on the coal samples cored from Shanxi group $II_1$ coal seam of Jiaozuo coal mine, Henan province, China, to obtain their property parameters. Considering the bedding has notable effect on the property parameter of coal, the samples with different bedding angles are prepared. The effects of bedding on the anisotropic characteristics of the coal seam are investigated. A geological geomechanical model is built based on the geology characteristics of the Jiaozuo coal mine target reservoir to study the effects of bedding on the fracture propagations during hydraulic fracturing. The effects of injection pressure, well completion method, in-situ stress difference coefficient, and fracturing fluid displacement on the fracture propagations are investigated. Results show bedding has notable effects on the property parameters of coal, which is the key factor affecting the anisotropy of coal. The hydraulic cracks trends to bifurcate and swerve at the bedding due to its low strength. Induced fractures are produced easily at the locations around the bedding. The bedding is beneficial to form a complicated fracture network. Experimental and numerical simulations can help to understand the effects of bedding on hydraulic fracturing in coalbed methane reservoirs.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.04a
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• pp.755-758
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• 2015

LED 부품소재 분야에서 가장 높은 특허 분쟁율을 나타낸 신물질 형광체는 외부로부터 흡수된 에너지를 가시광선 영역의 빛 에너지로 변환시켜주는 무기 발광 물질로 LED에서 직접적으로 빛을 내는 역할을 하는 핵심소재로 LED 전체의 발광 특성(광 변환 효율, 휘도, 연색지수 등) 향상이 가능하므로, 고온에서도 발광강도의 안정성을 유지할 수 있는 형광체에 대한 기술이 유망할 것으로 판단된다.

• Journal of Advanced Marine Engineering and Technology
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• v.25 no.2
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• pp.338-344
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• 2001

According to the MARPOL 73/78 of Convention, all ships should have oil filtering equipment and 15 ppm bilge which satisfy Requirements of MARPOL 73/78. This study is concerned with designing and manufacturing a prototype Oil content Meter(OCM) used in machinery area of ship. The prototype OCM is composed of two parts which are oil content sensing module and data processing unit. The oil content sensing module consists of infra-red light source, photo-diode light receivers, and a glass tube for bilge water sample. The data processing unit has a micro-processor as hard core and peripheral devices. The experimental results of prototype OCM and analysis of collected data reveal linear property between transmitted light and scattered light as long as the bilge water has low level content of oil. And this linear property leads to a oil content detecting method which is programmed and loaded into the data processing unit. The performance of the prototype OCM is compared with that of the commercial OCM in the market.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2003.05a
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• pp.100-102
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• 2003

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1271-1278
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• 2000

A general curve and surface is a basic method to generate Free-form object using the fundamental properties of blending function. In typical method, there is an overhead of calculating to present Free-form object with the line segments and interpolation algorithm, In this paper, for resolving this problem efficiently, it will propose the flexible Free-form curves/surfaces using Ball curve shape-preserving property. This method includes Geometric Continuity that is needed to design Free-form Surface of high degree consisted with many curves. Also, when lots of data are reduced using Geometric Property of Free-form curves, the shape-preserving property of resulting object can be maintained, then it can represent any Free-form object with less calculating .

• Corrosion Science and Technology
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• v.2 no.1
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• pp.7-11
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• 2003

Photoelectrochemical response and electrochemical impedance behavior was investigated for passive film formed on sputter-deposited Cr alloy in $0.1kmol{\cdot}m^{-3}$. Photoelectrochemical action spectrum could be separated into two components, which were considered to be derived from $Cr_2O_3$ ($E_g\sim3.6eV$) and $ Cr(OH)_3 $ ($E_g\sim2.5eV$). The band gap energy, $E_g$, of each component was almost constant for various applied potentials. polarization periods and alloying additives. The photoelectrochemical response showed negative photo current for most potentials in the passive region. Therefore, the photo current apparently exhibited p-typesemiconductor behavior. On the other hand, Mort-Schottky plot of the capacitance showed positive slope, which means that passive film formed on Cr alloy has n-type semiconductor property. These apparently conflicting results are rationally explained assuming that the passive film on Cr alloy formed in the acid solution has n-type semiconductor property with a fairly deep donor level in the band gap and forms an accumulation layer in the most of potential region in the passive state.

• Journal of the Korea Society of Computer and Information
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• v.15 no.1
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• pp.83-90
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• 2010

The number of searched nodes and the computation time in an index should be minimized for optimizing the processing cost of the nearest neighbor query. The Measurement of search distance considered a circular location property of objects is required to accurately select the nodes which will be searched in the nearest neighbor query. In this paper, we propose the processing method of the nearest neighbor query be considered a circular location property of object where the search space consists of a circular domain and show its performance by experiments. The proposed method uses the circular minimum distance and the circular optimal distance which are the search measurements for optimizing the processing cost of the nearest neighbor query.

• Journal of Fashion Business
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• v.19 no.4
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• pp.109-119
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• 2015

A wide variety of fashion materials focus on good drape property and softness. Among the recently emerging materials, Neoprene that consists of laminated knit on both sides of foamed neoprene sheet seeks a unique appearance that is considerably deviated from the current flow. Diverse processing methods for the newly released material heighten the value in function and beauty among trends of fashion materials by enhancing the appearance, touch and material property. Laser-cutting technique is one of the processing methods that is consistently used in the textile area. This study aimed to find the basic materials for applicability of laser-cutting technique to clothing goods after consideration of the changes in material property and drape shape, and to furthermore enforce different pattern conditions to Neoprene material, one of the newly attractive materials in the fashion area. In this study, we applied laser-cutting technique to Neoprene material sample under different conditions of pattern appearance, size and distance, based on current evaluation and theoretical background of Neoprene material, fashion trend and laser-cutting technique. Drape property can improve and the drape direction could also be controlled by a wide variety of laser-cutting techniques applied to Neoprene materials that have uniquely different appearances from most other textiles. This technique could be applied to the design for diversification of Neoprene clothing goods in the future.

• Journal of the Korean Society for Heat Treatment
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• v.33 no.4
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• pp.185-192
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• 2020

In this study, materials characterization of pure copper and copper based carbon nano-tube composite prepared by powder metallurgy method were investigated. Prior to evaluate materials characterization, spark plasma sintering processing variables such as sintering temperature, pressure, thickness and diameter of compacts was optimized to ensure the microstructure and materials property of pure Cu and Cu-CNT composite. In addition, corrosion behavior of Cu-based CNT composite produced by powder sintering method was investigated. It was confirmed from this study that the corroded surfaces of the composite shows less dissolution compared with pure copper in 3.5 wt% NaCl solution. The measured corrosion current density (I_corr) indicates improved corrosion property of Cu based composite containing small additions of CNTs in chloride containing media. Micro-galvanic activity between Cu and CNT was not observed in given sintering condition.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1601-1606
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• 2007

In order for high strength aluminum alloys to be used in transportation systems and the aerospace industry, excellent mechanical and physical properties are required. In particular, excellent anti-abrasion property is indispensable for parts that require driving force. In general, surface treatment technologies such as high frequency heat treatment, gas solid carburizing, surface rolling, shot peening are used as ways of improving anti-abrasion property. Among various surface treatment technologies, this research chose shot peening processing for Al7075-T6, which is well known as representative high-strength alloy steel. Wear characteristics were compared and analyzed after shot peening processing with shot ball velocities of 40m/s and 70m/s in order to investigate the effects of shot peening processing on wear characteristics.