• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.163-167
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• 2001

A two-dimensional progressive failure analysis method is presented for the strength characterization of the composite joints under pin loading. The eight-nodes laminated she]1 element is utilized based on the updated Lagrangian formulation. The criteria by Yamada-Sun, Tsai-Wu, and the maximum stress are used for the failure estimation. The stiffness of failed layer is degraded by the complete unloading method. No factor depending on test is included in the finite element analysis except for the material strength and stiffness. Total 20 plate specimens with and without hole are tested to validate the finite element prediction. The Tsai-Wu failure criterion most conservatively estimates the strength of laminate, and the maximum stress criterion yields the highest strength because it does not consider the coupling of the failure modes. The strength by Yamada-Sun method neglecting the matrix failure effect are located between other two methods and shows best agreement with test result for laminate with hole.

• Journal of Astronomy and Space Sciences
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• v.23 no.3
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• pp.289-302
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• 2006

For a reconstruct draft of the Gyupyo (Gnomon) in King Sejong Era, we collected a lot of documents of the Chosen Dynasty. With the result we made a reduced model by 1/10 and drawing set for the Gnomon in Sejong Era. It is composed of the Gyu, Yongpyo, Hoengryang (a beam), Yeongbu and granitic prop. You can read the scale where the shadow of vertically-standing stick touches the horizontal Gyu. A Shadow-Define. (Yeongbu) was used to focus the shadow cast by the sun's center, measuring the (gnomon) shadow length precisely. A Yeongbu is made of a leaf of copper in the middle of which is pierced a pin-hole for the tiny optical image of the sun which tilted to face the incident sunlight, used the principle of the a pin-hole camera and Scheimplug principle.

• Journal of the Korean Society of Radiology
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• v.10 no.1
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• pp.1-6
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• 2016

Recently, the various digital X-ray imaging devices using CCD and TFT LCD-based flat panel digital X-ray sensor are being used. In particular, a number of studies on photon counting sensor technique have been reported. In this study, the incident X-rays fluence on the photon counting sensor material was measured to estimate photon detection efficiency which is the quantitative performance evaluation factor of photon counting sensor. The result of measuring the photon fluence by using RQA-M2 Radiation beam quality of IEC 61223-1-2 recommendations, the incident photon fluence could be defined as about $4 photons/(0.01mm)^2{\cdot}{\mu}Gy$ within $10{\mu}m$ pin-hole area, and about $50photons/(0.03mm)^2{\cdot}{\mu}Gy$ within $30{\mu}m$ pin-hole area, and about $698photons/(0.1mm)^2{\cdot}{\mu}Gy$ within $100{\mu}m$ pin-hole area. Consequently, with the previously setup of the incident fluence, the measuring of actual photon counting efficiency by observing the output waveform of the photon counting sensor material was considered possible.

• Korean Journal of Optics and Photonics
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• v.25 no.1
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• pp.21-28
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• 2014

In this paper a Super Multi-view display method using a pinhole array with full parallax was proposed. The proposed method was simulated and its parameters analyzed. Also, the distribution and irradiance of light through each pinhole on the retina receiver, according to the change of crystalline lens focal length, were found by simulation. As a result, an image free of blurring was obtained while the crystalline lens focused on the depth plane of the three-dimensional image created by the imaging lens.

• Composites Research
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• v.23 no.3
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• pp.1-6
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• 2010

Recently, CFRP composite is more and more used in the various fields because of a higher specific modulus, chemical property and so on. Most products using CFRP composite are manufactured by construction of components. Various components are joined with those by bolts and pins. Holes for bolts and pins decrease strength and fatigue life of components, because those act as notch in structures. In this paper, we experimentally evaluated the fatigue life of hole-notched and unnotched weave CFRP plate. Then, we compared the two results and proposed an equation for prediction of fatigue life.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.217-222
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• 1998

Coating films of $SiO_2-TiO_2-AgO$ have been prepared on soda-lime-silica slide glasses and single crystal silicon wafer by the sol-gel method using a spin-coating technique. Commercially available tetraethyl orthosilicate, titanium trichloride, and silver-nitrates were used as starting materials. The heat treatment temperature of this coating films was $500^{\circ}C$ properly, obtained from TG-DTA result. The films with thickness of 310 nm were prepared by 5 times coating. In the case of l0 mol% AgO, the film showed a crack-free and smooth surface, but the higher Ago content exhibited the more pin hole and the segregated cluster of AgO. The IR absorbance of the films decreased in the range of 400 nm to 700 nm with the increase of annealing temperature. And the reflectance of the coating films decreased and the color was changed light yellow to white yellow with the increase of Ago content.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.1
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• pp.7-14
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• 2021

In jewelry industry, the proportion of labor costs is high. Also, the production time and quality of products are highly varied depending on the workers' capabilities. Therefore, there is a demand from the jewelry industry for automation. The ear pin insertion automation system is the robot automatically inserts the ear pins into the silicone mold, and this automated system require accurate and fast hole detection method. In this paper, we propose optimal binarization method and a template matching method that can be applied in the ear pin insertion automation system. Through the performance test, it was shown that the applied method has an accuracy of 98.5% and 0.5 seconds faster processing speed than the Otsu binarization method. So, this automation system can contribute to cost reduction, work time reduction, and productivity improvement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.782-787
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• 2000

The monolithic single-pole three-throw(SP3T) GaAs PIN diode switch circuit for the broadband and high power application was designed, fabricated and characterized. To improve the power handling capability, buffer layers of the diode employ both low temperature buffer and superlattice buffer. The diode show the breakdown voltage of 65V and turn-on voltage of 1.3V. The monolithic integrated switch employed microstrip lines and backside via holes for low-inductance signal grounding. The vertical epitaxial PIN structure demonstrated better microwave performance than planar type structures due to lower parasitics and higher quality intrinsic region. As the large signal characteristics of the fabricated SP3T MMIC switch, the insertion loss was measured less than 0.6dB and the isolation better than 50dB when the input power was increased from 8dBM to 32dBm at 14.5GHz.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.8
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• pp.669-681
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• 2016

Mechanical designers often make mistakes that result in unwanted over-constraints, causing difficulty in assembly operations and residual stress due to interference among parts. This study is concerned with detection and elimination of over-constraints. Screw theory is a general method that is used for constraint analysis of an assembly and motion analysis of a mechanism. Mechanical assemblies with plane-plane, pin-hole, and pin-slot constraint pairs are analyzed using screw theory to illustrate its utility. As a real-world problem, a ball valve design is analyzed using the same method, and several unwanted over-constraints are detected. Elimination measures are proposed. Nominal dimensions of some parts are adjusted, and dimensions and tolerances of the pins and holes are modified using the virtual condition boundary concept. The revised design is free of over-constraints. General procedure for applying screw theory to constraint analysis is established and demonstrated; it will contribute to improving quality of assembly designs.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.101-109
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• 2016

The purpose of this research was to develop a flat panel display device's glass etchant which can replace hydrofluoric acid. The glass etchant was composed of 18~19% wt% of ammonium hydrogen fluoride, 24~25 wt% of sulfuric acid, 45~46 wt% of water, 4~5 wt% of sulfate and 7~8 wt% of fluoro-silicate. By replenishing the etchant which has the amount of 5% of initial solution's mass, it was possible to reuse the etchant continuously. The developed etchant showed $5{\mu}m/min$ of etching rate at $30^{\circ}C$. The reusable etchant, with replenishing 5% of initial etchant mass showed the stable etching rate, which has the deviation of less than $0.1{\mu}m/min$ etching rate. The glass surface of flat panel display device created from our etching process was in good condition with any defects such as pin hole and dimple.