• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.569-574
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• 2008

In the device structure of ITO/tris(8-hydroxyquinoline) aluminum ($Alq_3$)/Al device, we investigated the efficiency improvement of organic light-emitting diodes (OLEDs) depending on the hole-size of crucible boat. The device was manufactured using a thermal evaporation under the base pressure of $5{\times}10^{-6}\;Torr$. The $Alq_3$ organics were evaporated to be 100 nm thick at a deposition rate of $1.5\AA/s$, and in order to investigate the optimal surface roughness of $Alq_3$, the $Alq_3$ was thermally evaporated to be 0.8 mm, 1.0 mm, and 1.5 mm as a hole-size of the boat, respectively. We found that luminance and external quantum efficiency are superior when the hole-size of the boat is 1.0 mm. The external quantum efficiency of the device made with the hole-size of 1.0 mm boat were improved by a factor of ten compared to the devices made with the hole-size of non boat.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.55-58
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• 2018

Low-cost and large-scale fabrication method of nanohole array, which comprises nanoscale voids separated by a few tens to a few hundreds of nanometers, has opened up new possibilities in biomolecular sensing as well as novel frontier optical devices. One of the key aspects of the nanohole array research is how to control the hole size following each specific needs of the hole structure. Here, we report the extensive study on the fine control of the hole size within the range of 500-2500 nm via surface-catalyzed chemical deposition. The initial hole structures were prepared via conventional photo-lithography, and the hole size was decreased to a designed value through the surface-catalyzed chemical reduction of the gold ion on the predefined hole surfaces, by simple dipping of the hole array device into the aqueous solution of gold chloride and hydroxylamine. The final hole size was controlled by adjusting reaction time, and the optimal experimental condition was obtained by doing a series of characterization experiments. The characterization of size-controlled hole array was systematically examined on the image results of optical microscopy, field emission scanning electron microscopy(FESEM), atomic-force microscopy(AFM), and total internal reflection microscopy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.278-285
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• 1988

The Critical size of artificially induced micro-holes in 0.17%, 0.36% Carbon steel Specimens with Spheroidized Cementite and in 0.17% carbon steel specimens with martensite structure is compared with annealed pre-crack in order to discuss the physical meaning of the fatigue limit and evaluation of the tolerant micro flaw size at the stress level of the fatigue limit. Results obtained were summarized as follows; (1) In this study, non-propagating crack length of Smooth specimen and critical pre-crack length (lc) is coincide. (2) In the carbon steels with spheroidized cementite structure, critical pre-crack length (lc) and allowable micro-hole size (dc) is coincide each other at the fatigue limit level. (3) It has been published that there exists a particular size of micro-hole which has no effect on the fatigue limit. In this study, the micro-hole of critical size can be regarded as equivalent to a tolerant micro flaw which would not reduce the fatigue limit.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.6
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• pp.285-289
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• 2015

With the miniaturization with both high functionality and high integrity of the probe cards, the highly precise laser punching on the zero-shrinkage high strength substrate has attracted more attention recently. Taper occurrence during laser-punching on green sheets appears as a problem in process. The size (diameter) difference between the entrance hole and the exit hole in tapered holes appeared to be inversely proportional to the hole size itself. To suppress taper occurrence, two-stage punching was adopted as the size of second hole was varied from $70{\mu}m$ to $79{\mu}m$ when punching $80{\mu}m$ via holes on the substrate with thickness of $380{\mu}m$. The minimal taper ratio of 11.9 % appeared with second hole size between 70 to $79{\mu}m$ before sintering. Taper ratio reduced to 7 % after zero-shrinkage sintering. The size difference between first hole and second hole appeared minimal when the size of second hole was 95~97 % to that of first hole.

• Transactions on Electrical and Electronic Materials
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• v.9 no.3
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• pp.105-109
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• 2008

Electrical characteristics of organic light-emitting diodes were investigated by varying a hole-size in evaporation boat in the device structure of ITO/tris(8-hydroxyquinoline) aluminum$(Alq_3)$/Al. The device was manufactured using a thermal evaporation under a base pressure of $5{\times}10^{-6}$ Torr. The $Alq_3$ emitting organics were evaporated to be a thickness of 100 nm at a deposition rate of $1.5{\AA}/s$. A cylindrical-shaped evaporation boat was made out of stainless steel with a small size of hole on top of the boat. Several evaporation boats were made having a different hole size on top; 0.8 mm, 1.0 mm, 1.5 mm, and 3.0 mm. We found that when the hole size on top of the evaporation boat is 1.0 mm, the average roughness is rather smoother compared to the other ones. Also, luminance and external quantum efficiency are superior to the others. Compared to the ones from the devices made with the hole-size of 0.8 mm boat. The luminance and external quantum efficiency of the device made with the hole-size of 1.0 mm boat were improved by a factor of seventy and thirty three, respectively. Also operating voltage is reduced to 2 V.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.10
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• pp.80-86
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• 1999

Since the quality of the coated wires is in various applications dependant on the coating depth, accuracy of hole size of dies used for coating wires must be maintained precisely, in general within one micron. This paper proposes a new vision system which measures automatically the size and shape of small holes having diameters less than 1mm within an error limit of 1 micron. To quickly obtain the focused image, this paper proposes an estimation method of the camera position using only a couple of defocused hole images. It measures the distributions of light intensity around the image boundary and decides the direction and distance of a camera motion. The proposed system measures the size, shape distortion, inclination of the hole against the axis of the dies structure, to decides the acceptability of the dies for use. The proposed algorithm has been implemented using a cheap 640${\times}$480 image system and has shown an average size error of 1micron when measuring the dieses having 0.1mm to 1.0mm diameters. It can be applied to the inspection of the size and position of holes in PCB, too.

• Journal of Ocean Engineering and Technology
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• v.1 no.2
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• pp.74-82
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• 1987

This study has been made to investigate into the behavior of fatigue limit, of fatigue crack initiation, and of fatigue crack propagation under the condition of rotating bending stress; specifically on the independency of stress field as well as the crack behavior of surface micro hole defect, which is made artificially through the specimen. The results obtained can be summarized as followa; 1) For the single micro hole defect, initiation of fatigue crack is occurred at both tips of microhole defect simultaneosly along the slip which are produced in the range of maximum principal stress arround micro hole defect independent of the size of micro hole defect. 2) For the neighbored deuble micro hole defects with equal size, in the range ($\frac{L}{r}$)ratio $\gtrsim$ 3 defined as the size of micro hole defect(2r) to the distance between the centers of micro hole defects (2L), the crack behavior of the micro hole defects is same as single one. However, for the range of $\frac{L}{r}$<3, the interference effect becomes significant as the ratio approaches to 1.

• Journal of Environmental Health Sciences
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• v.47 no.2
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• pp.175-181
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• 2021

Objectives: The correlation between the size of a leak hole, the volume of the leakage, and the range of influence was investigated for a hydrochloric acid tank-lorry. Methods: For the case of a tank-lorry chemical accident, KORA (Korea Off-site Risk Assessment Supporting Tool) was used to predict the leak rate and the range of influence according to the size of the leak hole. The correlation was studied using R. Results: As a result of analyzing the leak rate change according to the leak hole size in a 35% hydrochloric acid tank-lorry, as the size of the leak hole increased from 1 to 100 mm, the leak rate increased from 0.008 to 83.94 kg/sec, following the power function. As a result of calculating the range of influence under conditions ranging from 1 to 100 mm in size and 10 to 60 minutes of leakage time, it was found that the range spanned from a minimum of 5.4 m to a maximum of 307.9 m. As a result of multiple regression analysis using R, the quadratic function model best explained the correlation between the size of the leak hole, the leak time, and the range of influence with an adjected coefficient of determination of 0.97 and a root mean square error of 22.33. Conclusion: If a correlation database for the size of a leak hole is accumulated for various substances and under various conditions, the amount of leakage and the range of influence can easily be calculated, facilitating field response activities.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.664-667
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• 1997

In this study, it is attempted to obtain the optimized size of holes in 15 square plate models where a hole exists on every quadrant of a plate, and to get eigenvalues and mode shapes by performing free vibration analysis for each model. For free vibration analysis and optimization of' hole sizes, the uniaxial tension is applied for the loading condition. From the results of this study, it is known that more stable structures can be designed by changing the natural frequency depending on the location and the optuiiunl size of holes. and further studies are considered to be necessary for the basic design information.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.37.1-37.1
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• 2009

최근 휘어짐이 가능한 flexible display의 개발이 활발히 진행됨에 따라 OLED(organic light emitting diode)의 발전 가능성은 커지고 있다. 하지만 cathode 재료인 Cr, Al등은 tensile 또는 bending에 취약하다. 따라서 본 연구에서는, 인장시험용 아령모형의 PET($125\;{\mu}m$) 필름에 Al, Cr, Cr+Al을 각각 코팅하고 부분적으로 hole을 patterning함으로써 인장 시 미소크랙의 발생을 감소시켜 전기저항(R) 변화를 최소화하는 패턴형상을 design하고 세 가지 금속의 전기저항 변화를 통해 좀 더 우수한 flexible display용 금속을 찾는데 그 목적이 있다. 전극에 형성된 미세패턴의 영향과 패턴 된 hole size에 따른 전기저항의 변화를 알아보기 위해 hole size는 $50\;{\mu}m$, $30\;{\mu}m$, $10\;{\mu}m$로 제작하였고 각각의 금속막에 patterning하였다. 제작된 시편을 인장시험 장치에 설치 후 2mm/min의 속도로 인장응력을 가하면서 Load의 증가에 따른 금속막의 전기저항($\bigtriangleup$R)을 동시동작으로 측정하였다. 실험결과 인장시험 시 저항변화는 Cr이 짧은 시간에 가장 급격하게 변하였으며 다음으로 Cr+Al, Al순 이였다. 또한, hole size의 크기에 따른 전기저항의 변화는 $50\;{\mu}m$ size의 hole을 pattern한 시편이 가장 안정한 저항 변화를 보였다.