• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.671-674
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• 2004

This paper presents design and analysis of multi-layered ring-dot type piezoelectric transformer. These transformers are useful for step up and step down. The transformers consist of disk type multi-layered piezoelectric ceramic plates. The finite element method(FEM) was used for analysis transformer. Vibration mode, electric field and equivalent elastic strain of piezoelectric transformer were simulated by changing frequency. As results, the strain was distributed in isolation part entirely. We can get the operated in step up transformer when the inner side electrode using by input parts. Also we can get the step down transformers using by input Part as outer side electrode. The step up ratio and step down ratio was increased by decreasing inner side electrode. The resonance frequency was increased by increasing inner side electrode when the transformer was operated in step down transformer. But the step up one was decreased. From these results, we can expect to multi-layered ring-dot type piezo transformers as step up and step down transformers.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.177-180
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• 2003

We investigated transmittance, surface characteristics, and resistivity according to bending of ITO(indium tin oxide) film with four other multi-barrier film. Transmission data of ITO film with four ITO films showed there was about large 90% transmission above 550nm wavelength at three multi-barrier structures. But, both-side hard coated structure showed relatively low 75% transmission above 550nm wavelength. And, surface images measured from SEM(scanning electron microscope) showed both-side hard coated structure have a tendency of more roughness. Also, resistivity change of four other multi-barrier film showed there was the lowest change at one-side hardcoated structure. Subsequently, with result of resistivity change according to position, we knew the resistivity change of the center increased rapidly than that of the edge.

• Journal of Fashion Business
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• v.13 no.2
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• pp.123-135
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• 2009

To cope with the threats posed by climate change actively, this study tries to examine multi-functional fashion design with the moral awareness of environment, which could be a direct cause of climate change. Literature and patents on multi-functional fashion design following climate change at home and abroad are examined to find the trend of multi-functional fashion designs. And fashion design that can protect human body to cope with climate change is analyzed. This study found that first, it is necessary to recognize the environment problems in the design process so that material is used to the minimum to minimize pollution and enable welfare and continuation of human society; second, environmentally friendly production and rational consumption such as manual production without waste of energy and material need to be favored to minimize the destruction of environment; third, to cope with environment and climate changes, design that allows an item to have diverse functions is needed so that it can have varied lengths, widths, and thicknesses, and it can be put on and taken off.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.427-430
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• 2003

The properties of digital X-ray detectors depend on the absorption extent of X-rays, the generated signal of each X-ray photon and the distribution of the generated signal between pixels. In digital X-ray detector with single layer, signal is generated by X-ray photon captured in photoconductor. In X-ray detector with multi structure that scintillator formed above the top of photoconductor, signal is generated both by X-ray photon captured each in scintillator and photoconductor. X-ray detector with multi structure is generated more signal than single layer detector. In this paper, we simulated absorption fraction of X-ray detector with multi-layer using Monte Carlo program. The results compared with single-layer detector to be formed scinillator or photoconductor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.1179-1182
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• 2004

This paper describes the information for quantitative simulation of weakly ionized plasma. In previous paper, we calculated the electron transport coefficients in $CF_4+Ar$ gas mixture by using two-term approximation of Boltzmann equation. but there is difference between the result of the two-term and the multi-term approximation of the Boltzmann equation in $CF_4$ gas. Therefore, in this paper, we calculated the electron drift velocity (W) in $CF_4+Ar$ gas mixture for range of E/N values from $0.01\sim500[Td}$ at the temperature was 300[K] and pressure was 1[Torr] by multi-term approximation of the Boltzmann equation by Robson and Ness. The results of two-term and multi-term approximation of the Boltzmann equation has been compared with each other for a range of E/N.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.38-44
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• 2021

To cater to the transition from single-color to multicolor/multi-material printing, this paper proposes a cartridge-replacing type multi-nozzle Fused Depositon Modeling(FDM) three-dimensional (3D) printer. In the test printing run, tool change failure/wobble/layer shift occurred. It was confirmed that improper support was the cause of this tool change failure. As a solution, spline and electromagnetic cartridges were designed. Wobble was caused by machine vibration and the motor stepping out. To minimize wobble, an additional Z-axis was installed, and the four-point bed leveling method was used instead of the three-point bed leveling method. The occurrence of layer shift was ascribed to the eccentricity of the Z-axis lead screw. Therefore, slit coupler was replaced with an Oldham type. In addition to the mechanical supplementation, the control environment was integrated to prevent accidents and signal errors due to wire connections. Before the final test printing run, a rectifier circuit was added to the motor to secure precise control stability. The final test printing run confirmed that the wobble/layer shift phenomenon was minimized, and the maximum error between layers was reduced to 0.05.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.5 no.1
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• pp.11-16
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• 1972

During the period from 1966 to 1968, total catches of Spanish mackerel averaged 6,000 to 7,000M/T per annual in Korea, and approximately 70 per cent of this amount was captured by drift nets. In an effort to improve the efficiency of drift nets, some experiments were conducted in 1969 to investigate the selectivity of material and mesh sizes. Seven different mesh sizes (80,85,95,100,105,110 and 115 mm) of both multi- and mono-filament netting were used, and the following results were obtained : 1, The body weight of Spanish mackerel taken with the seven different mesh sizes ranges from 0.5kg to 2.9kg, and the mode of body weight consists of three groups, 1kg ($21%$), 1.3kg($15\%$) and 1.5kg($19\%$). 2. For multi-filament net, 80 to 105mm mesh sizes were suitable to catch those three groups, and a little smalter than these for mono-filament net. 3. For Spanish mackerel only, the mono-filament material proved to have 1.5 times better selectivity than multi-filament : however, the latter proved superior for miscellaneous fish species due to its different size and shape. 4. Multi-filament net showed better selectivity for smaller species than mono-filament. (and mono-filament in general indicated opposite phenomenon.)

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.324-328
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• 2019

There are several dedicated individual chambers for sports that are supplied and used, but none of them are multi-pressured all-in-one chambers that can provide a sport-multi environment simultaneously. In this study, we design a multi-pressure (positive / atmospheric / negative pressure) integrated chamber that can be used for the sport-multi-artificial environment system. We presented new chamber designs with enlarged space for the tall users and then carried out structural analysis with maximum stress and structural safety. Under the targeted allowable pressure conditions, maximum stresses occurred at the joint of the shell and the entrance, the structural safety of the chamber was evaluated with the allowable stress of its material. As a result of the structural analysis of the multi-pressure integrated chamber, the maximum stress for the positive pressure and negative pressure conditions was much smaller than the allowable stress of its material. And as a result of the structural safety evaluation, it was confirmed that the design of the final prototype for the chamber was structurally safe by satisfying the safety factor of 2 or more.

• Journal of Ocean Engineering and Technology
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• v.25 no.1
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• pp.67-72
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• 2011

Offshore structures, such as a platform, a buoy, or a floating vessel, are exposed to several dynamic loads, and viscoelastic damping material is used to reduce the vibration of offshore structures. It is important to know the properties of viscoelastic materials because loss factor and Young's modulus of the viscoelastic damping material are dependent on frequency and temperature. In this study, an advanced technique for obtaining accurate loss factor and Young's modulus of the viscoelastic damping material is introduced based on a multi degree of freedom curve-fitting method and the RKU (Ross-Kerwin-Ungar) equations. The technique is based on a modified experimental procedure from ASTM E 756-04. Loss factor and Young's modulus of the viscoelastic damping material are measured for different temperatures by performing the test in a temperature-controlled vibration measurement room where temperature varies from 5 to 45 degrees Celsius.

• Computers and Concrete
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• v.26 no.5
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• pp.439-450
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• 2020

In this research, bending and buckling analyses of porous functionally graded (FG) plate under mechanical load are presented. The properties of the FG plate vary gradually across the thickness according to power-law and exponential functions. The material imperfection is considered to vary depending to a logarithmic function. The plate is modeled by a refined trigonometric shear deformation theory where the use of the shear correction factor is unnecessary. The governing equations of the FG plate are derived via virtual work principle and resolved via Navier solutions. The accuracy of the present model is checked by comparing the obtained results with those found in the literature. The various effects influencing the stresses, displacements and critical buckling loads of the plate are also examined and discussed in detail.