• Journal of the Korean Society for Precision Engineering
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• v.11 no.5
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• pp.98-109
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• 1994

This paper is studied on the junction stress of the large tank and the cylindrical outlet such as a pressure vessel attached to a pope or nozzle theoretically. It is assumed that the diameter of tank is much larger than that of the nozzle cylinder, so it can be approximated that nozzle cylinder is attached to plate. As the current nozzle shape is manufactured as "Through Type" to reduce the stress concentration around the nozzle junction part of pressure vessel, a theoretical analysis on the cylinder with finite length should be performed to accomodate this fact. Each theoretical optimal values were obtained through the analysis of stress concentration caused by the variation of cylinder length and thickness, and these results were estimated by performing FEM Analysis. Analysis.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.164-169
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• 2008

The effects of the antisite related defects on the electronic structure of silica and the gate leakage current have been investigated using first-principles calculations. Energy levels related to the antisite defects in silicon dioxide have been introduced into the bandgap, which are nearly 2.0 eV from the top of the valence band. Combining with the electronic structures calculated from first-principles simulations, tunneling currents through the silica layer with antisite defects have been calculated. The tunneling current calculations show that the hole tunneling currents assisted by the antisite defects will be dominant at low oxide field whereas the electron direct tunneling current will be dominant at high oxide field. With increased thickness of the defect layer, the threshold point where the hole tunneling current assisted by antisite defects in silica is equal to the electron direct tunneling current extends to higher oxide field.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.102-105
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• 2001

The bending process for the curved tube can be developed by the hot metal extrusion machine with the multiple punches moving in the different velocity. The bending phenomenon has been studied to be occurred by the different of velocity at the die extrusion. The difference of velocity at the die exit section can be obtained by the different velocity of billets through the multi-hole container and by the welding of billets inside the porthole die chamber. The multiple billets are moving differently by the multiple extrusion punches controlled by PLC with the servo mechanism units. The results of the experiments show that the curved tube can be bended by the extrusion process and that the defects such as the distortion of section and the thickness change of thick tube, tile folding and wrinkling of thin tube can not be shown after the bending processing by the extrusion bending machine.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.2
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• pp.30-36
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• 2020

We demonstrated a successful fabrication of 4" Gallium Nitride (GaN)/Diamond High Electron Mobility Transistors (HEMTs) incorporated with Inner Slot Via Hole process. We made in manufacturing technology of 4" GaN/Diamond HEMT wafers in a compound semiconductor foundry since reported [1]. Wafer thickness uniformity and wafer flatness of starting GaN/Diamond wafers have improved greatly, which contributed to improved processing yield. By optimizing Laser drilling techniques, we successfully demonstrated a through-substrate-via process, which is last hurdle in GaN/Diamond manufacturing technology. To fully exploit Diamond's superior thermal property for GaN HEMT devices, we include Aluminum Nitride (AlN) barrier in epitaxial layer structure, in addition to conventional Aluminum Gallium Nitride (AlGaN) barrier layer. The current collapse revealed very stable up to Vds = 90 V. The trapping behaviors were measured Emission Microscope (EMMI). The traps are located in interface between Silicon Nitride (SiN) passivation layer and GaN cap layer.

• Korean Journal of Acupuncture
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• v.28 no.3
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• pp.53-62
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• 2011

Objectives : Burn is most common adverse events of moxibustion. Various kinds of components influence on the heat stimulation of commercial indirect moxa, but there are not enough investigation about the status. The purpose of this study is to investigate the 6 components to build a base data that is currently available to build a standard of an indirect moxibustion. Methods : The length and weight, density, thickness of the paper disk, diameter of the paper disk, and diameter in the paper disk hole were measured against 6 kinds of commercial indirect cautery. Results : 1. 'Seoam', 'Kihwang' and 'Taegeuk' shows uniform length than the other brands. 2. 'Dongbang', 'Kihwang' and 'Taegeuk' shows uniform weight than the other brands. 3. 'Dongbang', 'Kihwang' and 'Taegeuk' shows uniform density than the other brands. 4. 'Dongbang' and 'Kihwang' shows uniform thickness than the other brands. 5. 'Seoam', 'Dongbang' and 'Taegeuk' shows uniform diameter of disc hole than the other brands. Conclusions : As a result of investigation, 'Dongbang' and 'Kiwhang' indirect moxibustion was identified as a uniform product. This results are considered as an important base materials of the KS through commercial indirect moxibustion.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.346-352
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• 2002

This paper is the experimental study to estimate the influence of various design parameters on the performance of mufflers with perforated tubes and through-flow partitions. Muffler types considered in the present work include through-flow chamber, through-flow chamber with partition, and cross-flow chamber. The influences of the design parameters on the performance of the mufflers can be outlined as follows. In the case of the through-f]ow type mufflers, increasing the tube thickness and the hole diameter of the perforated tubes does not change the maximum value of the transmission loss but decrease the cutoff frequency. In the case of the through-flow with partitions type mufflers, it is shown that combining a fe w short chambers and long chambers can modify the frequency locations of the resonance frequencies to optimize the performance of the mufflers. For the case of the cross-flow type mufflers, it is shown that the transmission loss of the mufflers is mainly affected by the lower porosity when the porosities are different in both sides of the plug. Overall, it is shown that performance of the through-flow type with partition type mufflers is excellent in the lower frequency region, where the cross-flow type mufflers have better performance in the higher frequency region.

• Composites Research
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• v.32 no.1
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• pp.65-70
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• 2019

The aircraft composites wing parts are usually integrated with adhesive or fastener. These laminated composites have weak interlaminar strength, which can lead to delamination. In order to compensate the disadvantages of laminated composites, it is possible to improve the strength, durability, shock and fatigue resistance by reinforcing the fiber in the thickness direction. In addition, using a single structure near-net-shape saves the manufacturing time and the number of fasteners, thus can reduce the overall cost of the composite parts. In this study, compression test, tensile test and open-hole tensile test are carried out for three structural architecture of 3D (three-dimensional) textile preforms: orthogonal(ORT), layer-to-layer(LTL) and through-the-thickness(TTT) patterns. Among these, the orthogonal textile composite shows the highest Young's modulus and strength in tensile and compression. The notch sensitivity of the orthogonal textile composite was the smallest as compared with UD (unidirectional) and 2D (two-dimensional) fabric laminates.

• Steel and Composite Structures
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• v.46 no.3
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• pp.353-366
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• 2023

This paper presents a finite-element analysis (FEA) of aluminum alloy rectangular hollow sections (RHSs) and square hollow sections (SHSs) with circular through-openings under three-point and four-point bending. First, a finite-element model (FEM) was developed and validated against the corresponding test results available in the literature. Next, using the validated FE models, a parametric study comprising 180 FE models was conducted. The cross-section width-to-thickness ratio (b/t) ranged from 2 to 5, the hole size ratio (d/h) ranged from 0.2 to 0.8 and the quantity of holes (n) ranged from 2 to 6, respectively. Third, results obtained from laboratory test and FEA were compared with current design strengths calculated in accordance with the North American Specifications (NAS), the modified direct strength method (DSM) and the modified Continuous strength method (CSM). The comparison shows that the modified CSM are conservative by 15% on average for aluminum alloy RHSs and SHSs with circular through-openings subject to bending. Finally, a new design equation is proposed based on the modified CSM after being validated with results obtained from laboratory test and FEA. The proposed design equation can provide accurate predictions of flexural capacities for aluminum alloy RHSs and SHSs with circular through-openings.

• Korean Journal of Materials Research
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• v.28 no.4
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• pp.235-240
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• 2018

We propose a speedy two-step deposit process to form an Au electrode on hole transport layer(HTL) without any damage using a general thermal evaporator in a perovskite solar cell(PSC). An Au electrode with a thickness of 70 nm was prepared with one-step and two-step processes using a general thermal evaporator with a 30 cm source-substrate distance and $6.0{\times}10^{-6}$ torr vacuum. The one-step process deposits the Au film with the desirable thickness through a source power of 60 and 100 W at a time. The two-step process deposits a 7 nm-thick buffer layer with source power of 60, 70, and 80 W, and then deposits the remaining film thickness at higher source power of 80, 90, and 100 W. The photovoltaic properties and microstructure of these PSC devices with a glass/FTO/$TiO_2$/perovskite/HTL/Au electrode were measured by a solar simulator and field emission scanning electron microscope. The one-step process showed a low depo-temperature of $88.5^{\circ}C$ with a long deposition time of 90 minutes at 60 W. It showed a high depo-temperature of $135.4^{\circ}C$ with a short deposition time of 8 minutes at 100 W. All the samples showed an ECE lower than 2.8 % due to damage on the HTL. The two-step process offered an ECE higher than 6.25 % without HTL damage through a deposition temperature lower than $88^{\circ}C$ and a short deposition time within 20 minutes in general. Therefore, the proposed two-step process is favorable to produce an Au electrode layer for the PSC device with a general thermal evaporator.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.251-254
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• 2009

A new type of dye-sensitized solar cells(DSCs) based on Ti-mesh electrode without using TCO layer is fabricated for high-efficient and low-cost solar cell application. The TCO-Iess DSCs sample is composed of a [glass/ dye sensitized $TiO_2$ layer/ Ti-mesh electrode/ electrolyte/ metal counter electrode]. The Ti-mesh electrode with high conductivity can collect electrons from the $TiO_2$ layer and allows the ionic diffusion of $I^-/I_3{^-}$ through the mesh hole. Thin Ti-mesh (${\sim}40{\mu}m$ in thickness) electrode material is processed using rapid prototype method. Electrical performance of as-fabricated DSCs is presented and discussed in detail.