• Textile Coloration and Finishing
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• v.34 no.1
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• pp.68-75
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• 2022

The breathable film refers to a high-functional film that allows gas and water vapor to pass through very fine and sophisticated pores but not liquid. In this research, the breathable film was prepared based on linear low-density polyethylene (LLDPE) and CaCO₃ particles by extrude method. The LLDPE composite film containing CaCO₃ particles had excellent mechanical properties and functionalties. The drawing is a technologically simple and excellent method for improving the mechanical properties of composite films. In this work, the effects of draw ratio on morphology, crystallinity, pore size distribution, mechanical properties, and water vapor permeability of the films were examined. The results revealed that both surface morphology and breathability were affected by the influence of chain orientation and crystal growth with increasing the draw ratio. The mechanical properties were improved with increasing the draw ratio.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.232.2-232.2
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• 2014

Since its discovery in 2004, graphene, a sp2-hybridized 2-Dimension carbon material, has drawn enormous attention. A variety of approaches have been attempted, such as epitaxial growth from silicon carbide, chemical reduction of graphene oxide and CVD. Among these approaches, the CVD process takes great attention due to its guarantee of high quality and large scale with high yield on various transition metals. After synthesis of graphene on metal substrate, the subsequent transfer process is needed to transfer graphene onto various target substrates, such as bubbling transfer, renewable epoxy transfer and wet etching transfer. However, those transfer processes are hard to control and inevitably induce defects to graphene film. Especially for wet etching transfer, the metal substrate is totally etched away, which is horrendous resources wasting, time consuming, and unsuitable for industry production. Thus, our group develops one-step process to directly grow graphene on glass substrate in plasma enhanced chemical vapor deposition (PECVD). Copper foil is used as catalyst to enhance the growth of graphene, as well as a temperature shield to provide relatively low temperature to glass substrate. The effect of growth time is reported that longer growth time will provide lower sheet resistance and higher VSG flakes. The VSG with conductivity of $800{\Omega}/sq$ and thickness of 270 nm grown on glass substrate can be obtained under 12 min growing time. The morphology is clearly showed by SEM image and Raman spectra that VSG film is composed of base layer of amorphous carbon and vertically arranged graphene flakes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.02a
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• pp.136-143
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• 2002

Warm draw die technique which is one of the new forming technologies to improve formability of sheet metal is applied to the cylindrical and square cup drawing of stainless-aluminum clad sheets. In experiments the temperature of die and blank holder is varied from room temperature to $180^{\circ}C$, while the punch is cooled by circulation of coolant to increase the fracture strength of workpiece on the punch comer area. Test materials chosen for experiments are STS304-A1050-STS304 clad sheets. Teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ratio and relative drawing depth as well as quality of drawn cups(distribution of thickness)are investigated and validity of warm drawing process is also discussed. No separation between each laminated material after drawing occurred through inspection by microscope as well as application of penetrant remover and bond strength test. Therefore, warm forming technique was confirmed to give better results in deep drawing of stainless clad sheet metal.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.87-93
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• 2000

Warm, forming technique which is one of the new forming technologies to improve formability of sheet metal is applied to the cylindrical cup drawing of stainless-aluminum. clad sheets. In experiments the temperature of die and blank holder is varied from room temperature to 18$0^{\circ}C$, while the punch is cooled by circulation of coolant to increase the fracture strength of workpiece on the punch corner area. Test materials chosen for experiments are STS304-A1050-STS304, STS304-A1050-STS430 clad sheets and A1050-0 aluminum sheet. Teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ratio as well as quality of drawn cups(distribution of thickness and hardness)are investigated and validity of warm drawing process is also discussed.

• The Journal of the Korea Contents Association
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• v.13 no.12
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• pp.638-649
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• 2013

This study focuses on analyzing the trend of Korean movies and the issues caused by industrialization and the alternatives. The results are as follows: first, there does not exist distinctive genre movie as most of the movie producers concentrate on thoughtless genre fusion of movie, simply hoping for box office success. Second, Giant companies that has large amounts of money and distributors tend to monopolize production, distribution, and running of movie. Consequently, the development of diversity and artistry is absolutely impeded. Third, the structure of Korean movie industry make some well-known movie stars survive the film world and staff members and actors except them face economic difficulty. The solution plans for the problems mentioned above can be drawn like this; first, genre film with distinctive features should be developed. Second, the monopolistic structure of the screen should be changed. Legal organizations are required to redesign the system of unfair Korean film industry. Third, it is suggested that quantitative expansion of special theaters of diversity film be urgently needed. Fourth, appearance fees given to popular movie stars, actors, and staff members have to be provided in a balanced way. Fifth, the way for revitalization of film production should be found through the legal examination of fund for film development. Last but not least, the profit from the additional film market ought to be made.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.16.1-16.1
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• 2009

We have fabricated solution processed oxide semiconductor active layer for thin film transistors (TFTs). The oxide semiconductor layers were prepared by ink-jet printing the sol-gel precursor solution based on doped-ZnO. Inorganic ZnO-based thin films have drawn significant attention as an active channel layer for TFTs applications alternative to conventional Si-based materials and organic semiconducting materials, due to their wide energy band gap, optical transparency, high mobility, and better stability. However, in spite of such excellent device performances, the fabrication methods of ZnO related oxide active layer involve high cost vacuum processes such as sputtering and pulsed laser deposition. Herein we introduced the ink-jet printing technology to prepare the active layers of oxide semiconductor. Stable sol-gel precursor solutions were obtained by controlling the composition of precursor as well as solvents and stabilizers, and their influences on electrical performance of the transistors were demonstrated by measuring electrical parameters such as off-current, on-current, mobility, and threshold voltage. Microstructure and thermal behavior of the doped ZnO films were investigated by SEM, XRD, and TG/DTA. Furthermore, we studied the influence of the ink-jet printing conditions such as substrate temperature and surface treatment on the microstructure of the ink-jet printed active layers and electrical performance. The mobility value of the device with optimized condition was about 0.1-1.0 $cm^2/Vs$ and the on/off current ratio was about $10^6$. Our investigations demonstrate the feasibility of the ink-jet printed oxide TFTs toward successful application to cost-effective and mass-producible displays.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.209-214
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• 1995

This paper describes that the effects of punch speed and temperatures of the die and the blank holder on the drawability are examined. Up to now, multi-stage of dies sets have been used generally at room temperature in deep drawing of rectangular shaped components. But using local heating, it is shown that one stage of die set was capable of deep drawing and the drawability was increased and sheet thickness of component was drawn somewhat uniformly. Rectangular deep drawing experiments on two kinds of stainless steel STS316L, STS430 of 1.0 mm thickness have been conducted using local heating. The limiting drawing height can be increased by heating the die and the blank holder up to 100 .deg. C at STS316L. Commercial lubricants hadn't an effect on drawability in rectangular deep drawing, but vinyl and teflon film had an effect on it.

• The KSFM Journal of Fluid Machinery
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• v.11 no.5
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• pp.50-56
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• 2008

Metal cutting operations involve generation of heat due to friction between the tool and the pieces. This heat needs to be carried away otherwise it creates white spots. To reduce this abnormal heat cutting fluid is used. Cutting fluid also has an important role in the lubrication of the cutting edges of machine tools and the pieces they are shaping, and in sluicing away the resulting swarf. As a cutting fluid, water is a great conductor of heat but is not stable at high temperatures, so to improve stability an emulsion type mixed fluid with water and oil is often used. It is pumped over the cutting site of cutting machines as a state of atomized water droplet coated with oil by using jet. In this paper, to develop cutting fluid supplying nozzle to obtain ultra thin oil film for coating water droplet, a numerical analysis of three dimensional mixed fluid Jet through multi-stage nozzle was carried out by using a finite volume method. Jet flow characteristics such as nozzle exit velocity, development of mixing region, re-entrance and jet intensity were analyzed. Detailed mixing process of fluids such as air, water and oil in the nozzle were also investigated. It is easy to understand complex flow pattern in multi-stage nozzle. Important flow Information for advance design of cutting fluid supplying nozzle was drawn.

• Transactions on Electrical and Electronic Materials
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• v.16 no.5
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• pp.234-240
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• 2015

Amorphous oxide-based thin-film transistors (TFTs) have drawn a lot of attention recently for the next-generation high-resolution display industry. The required field-effect mobility of oxide-based TFTs has been increasing rapidly to meet the demands of the high-resolution, large panel size and 3D displays in the market. In this regard, the current status and major trends in the high mobility oxide-based TFTs are briefly reviewed. The various approaches, including the use of semiconductor, dielectric, electrode materials and the corresponding device structures for realizing high mobility oxide-based TFT devices are discussed.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.117-120
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• 2003

Warm deep drawing which is one of the new forming technologies to improve formability of sheet metal is applied to the cylindrical cup drawing of Mg-alloy sheet metal. In experiments the temperature of die and blank holder is varied from room temperature to $300^{\circ}C$, while the punch is cooled by circulation of coolant to increase the fracture strength of workpiece on the punch corner area. Test material chosen for experiments is AZ31 magnesium sheet metal. Teflon film as a lubricant is used on both sides of a workpiece. The limit drawing ratio as well as thickness distributions of drawn cups are investigated and validity of warm deep drawing process is also discussed.