• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1996년도 제6회 학술강연회논문집
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• pp.3-8
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• 1996

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.767-770
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• 2000

A novel process is newly developed for building RP(Rapid Prototyping) parts using a sheet lamination technique. The build process of existing sheet lamination type RP machines consists of the following steps : feeding, lamination and cutting. In this process, the laminated part of an object is often scratched by a cutter or damaged by a laser beam due to the cutting operation preceded by lamination, In addition, decubing of the unused portion from the laminated block is difficult. In the new process, cutting operation is performed before lamination. The cutting operation takes place while a paper sheet is firmly attached on the plate using electrostatic force. Then liquid glue is applied to the calculated region of the given contour for lamination. The process aims to manufacture a $2k RP machine, what we call the Freeform Mater I, that can use A4 or latter-size used papers. A prototype machine that demonstrates the design concept is built and further research issues are discussed.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.152-157
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• 2009

The structure of the prism sheet and the reflective polarizer sheet in the direct - illumination liquid crystal display (LCD) backlight is optimized and fabricated. The apex angle of the prism sheet was changed from 90 degree to 96.5 and 101.5 degree and the angular spread of the diffuser films attached on the reflective polarizer sheet was changed from 7 to 1.5 degrees. The measured view angle, the normal luminance, and the contrast ratio from the optimized backlight unit showed improved optical performances.

• 대한환경공학회지
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• 제35권10호
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• pp.743-748
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• 2013

본 연구의 목적은 수분이 함유된 한지의 수분을 에탄올, 메탄올, 펜탄 등과 같은 비극성물질로 치환하여 한지 여과지를 만드는데 있다. 실험은 적정 비극성물질의 선택 및 적정 건조방법 그리고 제조된 한지여과지의 물리화학적 특성을 알아보기 위하여 수행되었다. 한지 종이필터를 제조하기 위하여 한지에 함유된 수분을 치환하기 위한 최적 물질은 에탄올이었으며 적정한 건조방법은 냉동 후 진공에 의해 수분을 건조하는 냉동건조방법이었다. 냉동건조에 의해 제조된 필터의 겉보기 밀도는 0.11-0.13 g/mL 으로 자연건조방법의 절반 이었으며 공극율은 약 90%로서 다공성을 나타내었다. 전자현미경 관찰결과 자연건조 및 열건조에 의해 제조된 여과지의 섬유는 섬유끼리 매우 가깝게 밀착되어 있었으나 냉동건조에 의해 제조된 섬유는 섬유간에 간격이 이격되어 있었다. 제조된 여과지의 압력손실은 자연건조 및 열건조 여과지보다 냉동건조에 의해 제조된 한지가 매우 낮았으며 BTEX제거효율은 한지의 수분을 비극성 물질에 의해 치환한 것보다 자연건조시킨 한지가 우수하였다.

• 한국분무공학회지
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• 제4권1호
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• pp.19-26
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• 1999

An experimental study of twin-fluid atomization for powder metallurgy has been conducted using a specially designed atomizer in which liquid is first spread into a thin sheet and then exposed on both sides to high-velocity air. Inner air jet worked for supplying liquid and outer air jets disintegrated liquid sheet. The first result of this study were confined to the effect of atomizing quality through experiments with water. The experimental data will be extend to include the influence of atomizing air velocities on mean particle size through experiments with molten material. An experimental equation on the relationship between SMD and the related parameters was taken out; $$SMD=0.00302\frac{{(\sigma_L\;\rho_L\;D_L)}^{0.5}}{\rho_A(V_1+1.155\;V_2)/2}(1+\frac{W_L}{(W_{A1}/3.33)+W_{A2}})+0.0148(\frac{{\mu_L}^2}{\sigma_L\;\rho_L})^{0.425} \;{D_L}^{0.575}(1+\frac{W_L}{(W_{A1}/3.33)+W_{A2}})^2$$.

• 대한기계학회논문집B
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• 제21권1호
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• pp.99-112
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• 1997

Mixing process of impinging jets of liquid oxidizer and liquid fuel is simulated by using water and sodium carbonate (Na$_{2}$CO$_{3}$) solution. The shapes of liquid sheets are visualized and flowrate distributions are measured by collecting droplets using measuring cells. Mixing charateristics are studied by using acid-base titration. Stable liquid sheets are formed and two liquid jets are well mixed for symmetric impinging jets. Similarity in flowrate distribution for various measuring heights is observed. For asymmetric impinging jets, liquid sheets become unstable as the difference in the velocities of jets increases. In some extreme cases, liquid sheets are not formed and the jets are separated. Dimensionless variables are adopted demonstrating similarly in flowrate distribution. Mixing characteristics vary significantly with experiment conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1798-1802
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• 2007

Adhesion strength of single layer ceramic capacitor sheet was measured using a peel testing system developed in this study. The peel test specimens with various dimensions were prepared from the ceramic sheet cast on the PET film. In peel test, the sheet specimen was adhered on the glass jig floating on the liquid media, which was designed to minimize the friction, and the specimen was then pulled up by micro-actuator. During the separation of the sheet from the PET film, peel force was measured. To normalize the testing condition, 3 different widths of the specimen were selected: 5, 10 and 20 mm. was used Furthermore, testing speed effect was investigated in this study. From the resullts using various testing conditions, the standard method for the peel strength testing may be suggested. Based on the testing condition, effect of peel angle on the strength was experimentally examined. It was found that the adhesive strength for the ceramic sheet is nearly identical, irrespective of the specimen width ranged from 5 to 20 mm, while the adhesive strength was increased with increasing testing speed. Furthermore, the strength was shown to be dependent on the peel angle.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.233-233
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• 2010

It is important to form the n+ emitter layer for generating electric potential collecting EHP(Electron-Hole Pair). In this paper the formation on the n+ emitter layer of silicon wafer has been made with respect to uniformity of shallow diffusion from a liquid source. The starting material was crystalline silicon wafers of resistivity $0.5{\sim}3\{Omega}{\cdot}cm$, p-type, thickness $200{\mu}m$, direction[100]. The formation of n+ emitter layer from the liquid $POCl_3$ source was carried out for $890^{\circ}C$ in an ambient of $N_2:O_2$::10:1 by volume. And than each conditions are pre-deposition and drive-in time. It has been made uniformity of at least. so, the average of sheet resistance was about 0.12%. In this study, sheet resistance was measured by 4-point prove.

• 한국표면공학회지
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• 제41권1호
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• pp.6-11
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• 2008

An Indium Zinc Oxide(IZO) transparent conductive layer was deposited on a large size glass substrate by using magnetron dc sputtering method with varying a deposition temperature. As the deposition temperature decreased to a room temperature, the sheet resistance of IZO film increased. But this deposition temperature range is included in an applicable to a device. From a standpoint of the sheet resistance, the differences of the sheet resistance were not great and the uniformity of the layer was uniformed around 10%. Crystallization particles were shown on the surface of the layer as deposition temperature increased, but these particles were not shown on the surface of the layer as deposition temperature decreased to the room temperature. It didn't make a scrap of difference in a transmittance of varying deposition temperature. Therefore, it is concluded that IZO thin film manufactured by the room temperature deposition condition can be used as a large size transparent conductive layer of a liquid crystal display device.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1757-1760
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• 2005

This paper is concerned with spring back after sheet forming of bulk amorphous alloys in the super cooled liquid state. The temperature-dependence and strain-rate dependence of Newtonian/non-Newtonian viscosities as well as the stress overshoot/undershoot behavior of amorphous alloys are reflected in the thermo-mechanical Finite Element simulations. Hemispherical deep drawing operations are simulated for various forming conditions such as punch velocity, die corner radius, friction, blank holder force, clearance and initial forming temperature. Here, spring back by an instantaneous elastic unloading was followed by thermal deformation during cooling and two modes of spring backs are examined in detail. It could be concluded that the superior sheet formability of an amorphous alloy can be obtained by taking the proper forming conditions for loading/unloading.