• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.1031-1032
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• 2009

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.927-929
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• 2003

Using received northeast region in China of Terra/MODIS data at Tokyo University of information Sciences. Make monthly division Land Surface Temperature maximum composite image. Using monthly division Land Surface Temperature maximum composite image, considered characteristic of monthly variation of Land surface temperature and relation with land covering and NDVI at the northeast region in China.

• Journal of the Korean Ceramic Society
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• v.26 no.5
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• pp.645-654
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• 1989

Specimens of WC-Co were indented to measure the resulting crack size and unindented samples were fractured in 3-point flexure to obtain the strength and to measure characteristic features on the fracture surface. Fracture toughness was determined using fractography and compared to those determined using identation techniques. We show that principles of fracture mechanics can be applied WC-Co composites and can be used to analyze the fracture process. The fracture surfaces were examined by scanning electron microscopy and optical microscopy. Characteristic feature observed in glasses, single crystals and polycrystalline materials known as mirror, mist, hackle, and crack branching were identified for these composites. We discuss the importance of fracture surface analysis in determining the failure-initiating sources and the failure behaviorof WC-Co composites.

• Journal of the korean Society of Automotive Engineers
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• v.15 no.3
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• pp.120-125
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• 1993

The surface roughness of workpiece is reduced during spark-out. The reduction of roughness is a benefit of spark-out, but spark-out lowers productivity. The characteristics of spark-out are different to those of plunge grinding to which feed is applied. This difference is due to overlapping cutting during spark-out. Effect of spark-out is in proportion to volume of grain wear. This phenomenon is due to different overlapping area. Dressing interval can be enlarged by spark-out, when volume of grain wear is large. In this study, the characteristic of spark-out was studied by spark-out obserbation in various grinding conditions. For this purpose thrust force, spark-out time and surface roughness of workpiece were experimentally investigated in various grinding conditions.

• Korean Journal of Materials Research
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• v.15 no.2
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• pp.139-142
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• 2005

[ $ZrO_2$ ] gate dielectric thin films were deposited by radio frequency (rf)-magnetron sputtering and its structure, surface morphology and electrical peoperties were studied. As the oxygen flow rate increases, the surface becomes smoother. The experimental results indicate that a high temperature annealing is desirable since it improves the electrical properties of the $ZrO_2$ gate dielectric thin films by decreasing the number of interfacial traps at the $ZrO_2/Si$ interface. The carrier transport mechanism is dominated by the thermionic emission.

• Communications of the Korean Mathematical Society
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• v.35 no.4
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• pp.1299-1307
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• 2020

We show that the Liechti-Strenner's example for the closed nonorientable surface in [13] minimizes the dilatation within the class of pseudo-Anosov homeomorphisms with an orientable invariant foliation and all but the first coefficient of the characteristic polynomial of the action induced on the first cohomology nonpositive. We also show that the Liechti-Strenner's example of orientation-reversing homeomorphism for the closed orientable surface in [13] minimizes the dilatation within the class of pseudo-Anosov homeomorphisms with an orientable invariant foliation and all but the first coefficient of the characteristic polynomial p(x) of the action induced on the first cohomology nonpositive or all but the first coefficient of p(x)(x ± 1)², p(x)(x² ± 1), or p(x)(x² ± x + 1) nonpositive.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1991-1993
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• 2002

This paper presents the PDMS surface characteristic change after the plasma process and the electroosmotic flow control technique for the two-dimensional focusing in the micro channels made of PDMS and glass. The channels are fabricated by plastic molding and micromachining technique. To observe the surface characteristic change as time elapses, we measure the contact angle of water on the surface and the velocity of the electroosmotic flow in a channel. The electric field adequate for focusing of a core flow in a confluence channel is obtained by the experiment. The computer simulation is performed to obtain the width and the depth of the core flow for several junction angles of the confluence channel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.4
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• pp.439-442
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• 2004

In this study, we investigated about electrooptics characteristic of three kinds of TN cell on the polyimide surface. Monodomain alignments of thermal stressed TN cell over temperature of liquid crystal isotropic phase were almost the same as that of no thermal stressed TN cells. However, the thermal stressed TN cells have many defects. Also, threshold voltage and response time of thermal stressed TN cells show the same performances as no thermal stressed TN cells. There were little changes of value in these TN cells. However, transmittances of TN cells on the polyimide surface decrease with increasing thermal stress time. Finally, the residual DC voltage of the thermal stressed TN cell on the polyimide surface shows decrease of characteristics as increasing thermal stress time. Therefore, the thermal stability of TN cell was decreased by high thermal stress for the long times.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.147-150
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• 1995

High speed machining one of the most effectiv to improve machining accuracy and product in dies and mould. But a study on this is limited to Alumium, light metal etc. This paper presents machining characteristic of gray cast iron in high speed machining with tungsten carbide endmill. It is suggested to measure sutting force, tool wear, surface roughness, surface shape and select of cptimal cutting condition in the high speed machining of gray cast iron. Performance of high speed machine tool was estimated and the relationship between cutting phenomenon and machinabillity was described.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.2
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• pp.105-111
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• 2005

In sheet metal forming, drawbeads are often used to control uneven material flow, which may cause defects such as wrinkles, fractures, surface distortion and springback. Appropriate setting and adjusting of the drawbead force is one of the most important parameters in sheet forming process control. Therefore in this study, drawbead test was performed at various bead surface treatment conditions to clarify the frictional characteristics between sheet and drawbead. Furthermore, the differences in drawing force between circular and rectangular shape beads have also been measured to estimate the effectiveness of bead shape on the material flow control. The results show that drawing and friction characteristic were strongly influenced by surface treatments of bead and bead shapes.