• International Journal of Precision Engineering and Manufacturing
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• 제2권3호
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• pp.41-46
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• 2001

This paper discusses the feasibility of improving micro-machining accuracy by using two-dimensional(2-D) vibration cutting. Vibration cutting is generated by two piezo actuators arranged orthogonally : one is actuated by a sine curve voltage input, and the other is actuated by a phase-shifted sine curve voltage. A tool attached to the vibrator oscillates in a 2-D elliptical motion, depending on the frequencies, amplitudes, and the phase shifts of two input signals and the workpiece feedrate. Along the elliptical tool locus, cutting is done in the lower part, and non-cutting is done in the upper part. By this way a unique feature of 2-D vibration cutting, that is, air lubrication between a tool and chips, is caused. Another unique feature of 2-D vibration cutting was experimentally verified, that is, some negative thrust force occurs as the direction of chip movement on a tool rake face is reversed. Those features not only help chips flow smoothly and continuously but also reduce cutting force, which results in a higher quality machined surface. Through tool path simulations and experiments under several micro-machining conditions, the 2-D vibration cutting, compared to conventional cutting, was found to result in a great decrease in the cutting force, a much smoother surface, and much less burr.

• 한국의상디자인학회지
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• 제7권2호
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• pp.121-135
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• 2005

From a social psychological perspective, Make-up is an tool for run a lot smoother and perform communication efficiently. Many people give a turn to hair color through dyeing form due to yearning to change individual image through the image which the color is having. This paper study how make-up behavior, hair color and self-consciousness will affect the Level of Expected social-psychological effect of College Girl Students. In the sense of make-up behavior, according to result, a group of make-up behavior of self-satisfaction-oriented the level of expected social-psychological effect higher than a group of make-up behavior of tradition-oriented. Hair colors doesn't seem to be having much effect on the level of expected social- psychological effect, but have been shown to influence make-up behavior and self-consciousness. On the self-consciousness, a group of high self-consciousness the level of expected social-psychological effect higher than a group of low or fair self-consciousness. They doesn't have much effect passive expected effect as 'complement of self insufficiency' or 'a person consciousness' But they are affect active expected effect as 'the pleasure of change' and 'positive ascent'.

• 한국전기전자재료학회논문지
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• 제23권11호
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• pp.859-863
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• 2010

Evolution of surface morphology of ${\alpha}-Al_2O_3$ substrate was investigated as a function of annealing temperature and time. Commercial (0001) ${\alpha}-Al_2O_3$ single crystal substrates were annealed in the range of $600-1000^{\circ}C$ in air. At $600^{\circ}C$, step-terrace structure started to be formed on the substrate. However, the surface roughness on the terrace was still considerable and a number of islands were observed on the step edges as well as the terraces. As the annealing temperature increased, the islands were absorbed into the step edges. Thus the terraces were smoother and the step edges were more straightened. Well-defined surface with a step height of 0.2 nm was formed above $900^{\circ}C$. On the other hand, when the substrate was annealed at a fixed temperature of $1000^{\circ}C$, the change of surface morphology was observed for the substrate annealed for 10 min. After the annealing for 30 min, the surface on which any islands could not survive was observed.

• 한국환경과학회지
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• 제10권5호
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• pp.337-342
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• 2001

The Rondonia Boundary Layer Experiment (RBLE-II) was conceived to collect data the atmospheric boundary layer over two representative surface in the Amazon region of Brazil; tropical forest and a deforested, pasture area. The present study deals with the observations of atmospheric boundary layer growth and decay. Although the atmospheric boundary layer measurements made in RBLE-II were not made simultaneously over the two different surface types, some insights can be gained from analysing and comparing with their structure. The greater depth of the nocturnal boundary layer at the forest site may be due to influence of mechanical turbulence. The pasture site is aerodynamically smoother and so the downward turbulent diffusion will be much pasture than over the forest. The development of the convective boundary layer is stronger over the pasture than over the forest. The influence of the sensible heat flux is important but may be not enough to explain the difference completely. It seems that energy advection may occur from the wet and colder(forest) to the dry and warmer area(pasture), rapidly breaking up the nocturnal inversion. Such advection can explain the abrupt growth of the convective boundary layer at the pasture site during the early morning.

• Transactions on Electrical and Electronic Materials
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• 제14권4호
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• pp.165-171
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• 2013

Nanostructured pure a-C and nitrogen doped a-C: N thin films with small particle size of, ~50 nm were obtained by Aerosol-assisted CVD method from the natural precursor camphor oil. Five samples were prepared for the a-C and a-C: N respectively, with the deposition temperatures ranging from $400^{\circ}C$ to $600^{\circ}C$. At high temperature, the AFM clarifies an even smoother image, due to the increase of the energetic carbon ion bombardment at the surface of the thin film. An ohmic contact was acquired from the current-voltage solar simulator characterization. The higher conductivity of a-C: N, of ${\sim}{\times}10^{-2}Scm^{-1}$ is due to the decrease in defects since the spin density gap decrease with the nitrogen addition. Pure a-C exhibit absorption coefficient, ${\alpha}$ of $10^4cm^{-1}$, whereas for a-C:N, ${\alpha}$ is of $10^5cm^{-1}$. The high ${\sigma}$ value of a-C:N is due to the presence of more graphitic component ($sp^2$ carbon bonding) in the carbon films.

• 한국전기전자재료학회논문지
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• 제30권5호
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• pp.276-283
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• 2017

A polysilicon-based metal-semiconductor-metal (MSM) photodetector was fabricated by means of our new methods. Its photoresponse characteristics were analyzed to see if it could be applied to a sensor system. The processes on which this study focused were an alloy-annealing process to form metal-polysilicon contacts, a post-annealing process for better light absorption of as-deposited polysilicon, and a passivation process for lowering defect density in polysilicon. When the alloy annealing was achieved at about $400^{\circ}C$, metal-polysilicon Schottky contacts sustained a stable potential barrier, decreasing the dark current. For better surface morphology of polysilicon, rapid thermal annealing (RTA) or furnace annealing at around $900^{\circ}C$ was suitable as a post-annealing process, because it supplied polysilicon layers with a smoother surface and a proper grain size for photon absorption. For the passivation of defects in polysilicon, hydrogen-ion implantation was chosen, because it is easy to implant hydrogen into the polysilicon. MSM photodetectors based on the suggested processes showed a higher sensitivity for photocurrent detection and a stable Schottky contact barrier to lower the dark current and are therefore applicable to sensor systems.

• 복식
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• 제58권4호
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• pp.26-34
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• 2008

The purpose of this study was to create a database of information on the mechanical properties of two different waterproof and breathable shell fabric groups(high density woven and PTFE laminate) used for outdoor apparel and to compare and correlate data of their mechanical properties and hand values. The results of this study were as follows; There were no statistically significant differences between two fabric groups in extension, bending and shearing properties. There were statistically significant differences between two fabric groups in MMD, SMD, LC and we values. High density woven fabrics had smoother surface than PTFE laminated fabrics. PTFE laminated fabrics can be compressed easily more than high density woven fabrics but their recovery after compression was not better than high density woven fabrics. There were statistically significant differences between two fabric groups in NUMERI, FUKURAMI. There was statistically significant difference between two fabric groups in total hand value. Total hand value and mean deviation of MIU had a very high and statistically significant negative correlation coefficient.

• 한국의류산업학회지
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• 제16권1호
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• pp.153-159
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• 2014

This study evaluates the changes of the subjective hand, preference, comfort and mechanical properties of tricot based artificial suede made from sea-island type micro fibers according to raising condition. The subjective hand and the preference of raised suede for jacket were rated by the 20's and 30's women experts according to raising cycles. Comfort properties were evaluated by air permeability, water vapor transmission, and thermal transmission. Mechanical properties were measured by the KES-FB system. The subjective hand of artificial suede was categorized into three hand factors: smoothness, warmness and thickness. Smoothness, warmness and thickness perception increased with raising cycles which affected hand preference and luxuriousness perception. The thickness and wale density of suede increased with the number of raising. Suede became more compact and less pliable and less stretchable due to increased fabric thickness; in addition, the surface of suede became smoother and compressive since the surface evenness of suede improved with smaller fiber fineness and an increased amount of naps covered the base fabric. Furthermore, water vapor transmission decreased and thermal insulation increased. The best raising conditions for artificial suede was four cycles in which artificial suede was preferred without changes in physical properties.

• 한국기계가공학회지
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• 제2권1호
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• pp.15-21
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• 2003

The ultrasonic polishing machine was developed to get super finishing that consist of machine part that can rotate and travel the main shaft with power 1.5kW, ultrasonic generator with frequency 20kHz. By using this machine we were investigated the characteristics of ultrasonic polishing for three different ceramics, and so could be obtained following results. First, we could be obtained the excellent surface for hard-ta-difficult cutting materials. Second, the effect of surface roughness for the feed rate could be shown that the more the feed rate Increases, the more the value of surface roughness increases. Third, owing to the characteristics being progressed brittle fracture in $Al_2O_3$ polishing with this machine, the value of surface roughness is larger than other ceramics. Forth, because the ultrasonic polishing can be smoother than the existing grinding in discharging the chips, it could be possible to improve the surface roughness about up to 15%.

• 한국정밀공학회지
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• 제20권7호
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• pp.63-69
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• 2003

Through the previous works, it was found that the laminated grinding wheel is more efficient to generate smoother surface in short time than general grinding wheels. But, if the laminated grinding wheel is easily worn-out, it is impossible to apply this wheel in the real grinding process, because the periodic time for dressing is closely linked to the productivity of the process. So, it is required to investigate the wear of the laminated grinding wheel fer studying the periodic time for dressing. But it is difficult to analyze the dressing period quantitavely. Therefore, in this study, periodic times for dressing of the laminated grinding wheel and general grinding wheel are deduced from the relationship between the wear of grinding wheels and the surface roughness changes according to the number of traverse in cylindrical traverse grinding through experiments. This study shows that there are some differences in the wheel wear mechanisms between the general and laminated grinding wheels. As a result, it is also found that the periodic time for dressing of the laminated grinding wheel is longer than that of the general grinding wheel.