• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2240-2242
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• 1998

Image coding based on fractal theory presents highly compressed image. In this paper, we discuss about compression of Image using HV partition method. HV partition scheme devides the image adaptively in horizontal and vertical axis. And for reducing the enconding time for the domain-range comparison, we use classification scheme, which uses the order of brightness of the rectangular portion of the image. This paper focused on the technique to reduce coding time which is a problem in traditional fractal compression by adaptive selection of image and its classification method.

• Transactions on Electrical and Electronic Materials
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• v.12 no.1
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• pp.7-10
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• 2011

High voltage (HV) integrated circuits are viable alternatives to discrete circuits in a wide variety of applications. A HV device generally used in these circuits is a lateral double diffused metal oxide semiconductor (LDMOS) transistor. Attempts to model LDMOS devices are complicated by the existence of the lightly doped drain and by the extension of the poly-silicon and the gate oxide. Several physically based investigations of the bias-dependent drift resistance of HV devices have been conducted, but a complete physical model has not been reported. We propose a new technique to model HV devices using both the BSIM3 SPICE model and a bias dependent resistor model (sub-circuit macro model).

• Steel and Composite Structures
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• v.24 no.6
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• pp.643-658
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• 2017

High strength preloadable bolt assemblies are commonly adopted in beam-to-column bolted connections. Nowadays, two systems of high strength preloadable grade 10.9 bolt assembly are recommended in Europe for structural applications, namely HR and HV, which are characterized by different failure modes. Recently, experimental tests performed on HR and HV bolt assemblies highlighted that the type of bolt assembly may significantly influence the joint response. Therefore, the accuracy of numerical modelling of bolt assemblies is crucial to simulate effectively the non-linear behaviour of bolted joints with either failure mode 2 or mode 3 of the bolt rows. In light of these considerations, this present paper describes and discusses some modelling criteria for both HR and HV bolts to be implemented in 3D finite element models by finite element analysis and structural designers. The comparison between the calibrated models and experimental results shows the accuracy of the proposed assumptions in simulating all stages of assembly tensile response.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1058-1062
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• 2011

After the design and production of cold rolling to make titanium-alloyed(Gr.9) eyerim, the function of the roller was evaluated. The surface roughness values of the roller of Ra was $0.05{\sim}0.156{\mu}m$ and of Rz was $0.23{\sim}067{\mu}m$. The values showed a satisfactory result compared with the surface roughness values Ra was $0.04{\mu}m$ and Rz was $0.3{\mu}m$ which was measured after barrel polishing for the titanium eyeglasses frame PVD (Physical Vapor Deposition) gilding. As a result of cold rolling of Ti-3Al-2.5V (Half Titanium), the degree of hardness increased to 221Hv, 247Hv(1st), 270Hv(2nd), etc. Therefore, it was found that proper heat treatment and multi-stand rolling process are necessary.

• Journal of Technologic Dentistry
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• v.36 no.3
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• pp.171-177
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• 2014

Purpose: The dental medicine has been preparing the custom-made service to meet the requirements of the aged society, while the average span of human life is growing more and more, and the full denture is a representative of them. It is causing great concern in these atmosphere of society, and demands for it are expected to increase. The full denture is a uniform combination of denture base and artificial teeth using polymerization, and is most influenced by change of physical properties of denture base and bonding strength with artificial teeth. Methods: In this study, the samples were made of composite resin combined with occlusion surface of artificial teeth undergone mechanically surface treatment to evaluate the bonding strength of composite resin for repairing artificial teeth. The resin teeth used in this study are 3 types artificial teeth. And 3 types of composite resins are used that are various polymerization resin. The shear strength of composite resins made in various polymerization ways to resin teeth was measured to evaluate bonding strength of artificial teeth to each composite resins. Results: Surface hardness's results on Trubyte Biotone(74.58Hv), Biotone IPN(70.06Hv), Endura Posterio (64.48Hv). Results of bonding strength of artificial teeth to composite resins on ES samples(8.73Mpa), IF(4.37Mpa) and IZ(3.84Mpa). Conclusion: 1. The Trubyte Biotone(74.58Hv) was first, followed by Biotone IPN(70.06Hv), and Endura Posterio(64.48Hv) in surface hardness's results of worn sides using hardness test. 2. The ES samples(8.73Mpa) showed significant differences with IF(4.37Mpa) and IZ(3.84Mpa) (p<0.05), but not other samples(p>0.05) in results of bonding strength of artificial teeth to composite resins.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.12 s.103
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• pp.1246-1254
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• 2005

Theoretical investigation is made on the electromagnetic fields generated by an impulsive point current source, fur the VV, HV, and VH problems at the interface between an isotropic upper half-space medium and a normally uniaxial lower half-space medium. The electric fields of these problems are associated only with the extraordinary-wave components in the Fourier-Laplace domain. Applying the Cagniard-de Hoop method to each problem, the time-domain solutions of the wave fields are obtained. The fields of the VV case can be expressed in explicit(integral-free) forms. The fields of the HV and VH cases are not integral-free, but the major singularities implicit in the integral solutions can be analytically extracted. The interfacial far fields in the frequency domain are determined by the singularities in the time domain.

• Physical Therapy Korea
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• v.27 no.4
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• pp.227-232
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• 2020

Background: Hallux valgus (HV) is a foot deformity developed by mediolateral deviation of the first metatarsophalangeal joint. Although various foot-toe orthoses were used to correct the HV angle, verification of the effects of kinetics variables such as ground reaction force (GRF) through three-dimensional (3D) gait analysis according to the various type of orthoses for HV is insufficient. Objects: This study aimed to investigate the effect of soft and hard types of foot and toe orthoses to correct HV deformity on the GRF in individuals with HV using 3D motion analysis system during walking. Methods: Twenty-six subjects participated in the experiment. Participants had HV angle of more than 15° in both feet. Two force platforms were used to obtain 3D GRF data for both feet and a 3D motion capture system with six infrared cameras was used to measure exact stance phase point such as heel strike or toe off period. Total walk trials of each participant were 8 to 10, the walkway length was 6 m. Two-way repeated measures ANOVA was used to determine the effects of each orthosis condition on the various GRF values. Results: The late anteroposterior maximal force and a first vertical peak force of the GRF showed that the hard type orthosis condition significantly increased GRF compared to the other orthosis conditions (p < 0.05). Conclusion: There were significant effects in GRF values when wearing the hard type foot orthosis. However, the hard type foot orthosis was uncomfortable to wear during walking. Therefore, it is necessary to develop a new foot-toe orthosis that can compensate for these disadvantages.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.7
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• pp.39-46
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• 2009

A fast-switching current-pulse driver for light emitting diode (LED) backlight is proposed. It uses a regulated drain current mirror (RD-CM) [1] and a high-voltage NMOS transistor (HV-NMOS). It achieves the fast-response current-pulse switching by using a dynamic gain-boosting amplifier (DGB-AMP). The DGB-AMP does not discharge the large HV-NMOS gate capacitance of the RD-CM when the output current switch turns off. Therefore, it does not need to charge the HV-NMOS gate capacitance when the switch turns on. The proposed current-pulse driver achieves the fast current switching by removing the repetitive gate discharging and charging. Simulation results were verified with measurements performed on a fabricated chip using a 5V/40V 0.5um BCD process. It reduces the switching delay to 360ns from 700ns of the conventional current-pulse driver.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.238-238
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• 2012

현재 국내 주얼리(gold alloy) 제품을 생산함에 있어 주조 방법은 크게 대기 중 주조(흡입주조) 방법과 진공주조 방법으로 나누어진다. 국내 주얼리 제조업체의 약 90%이상이 대기 중에서 주조하는 흡입주조방법을 통해 제품을 제작하고 있고, 국외의 경우, 대다수 진공주조방법을 통해 제품을 제작하고 있다. 본 연구에서는 주얼리 제품을 생산할 때 사용되는 합금재료(master alloy)가 동일한 조건에서 주조방법을 달리하여 각각 24개씩 총 48개의 14K yellow gold alloy 제품을 제작한 후 열처리를 통해 각각의 기계적, 물리적 특성분석을 비교 분석하였다. EPMA (Electron Probe Micro Analysis)분석을 통해 합금재료 및 제품의 구성성분을 조사하였고, ICP-MS (Inductively Coupled Plasma Mass Spectroscopy)를 사용하여 성분에 대한 정량분석을 실시하였다. 용체화처리(solid solution treatment)는 $700^{\circ}C$, 30분의 조건으로 실시하였고, 시효경화처리(age-hardening)는 $200{\sim}300^{\circ}C$의 온도범위에서 $50^{\circ}C$ 간격으로 실시하였다. 열처리 전과 후 시료의 grain 들의 배열 및 size 변화를 관찰하기 위해 식각 후 OM (optical microscope) 및 SEM (Scanning Electron Microscope)를 통해 분석하였다. 열처리 전 제품의 경도측정결과 대기 중 흡입주조방법 및 진공 주조방법을 통해 제작된 제품이 각각 119 Hv, 126 Hv로 나타났고, 용체화 처리 후 98 Hv, 92 Hv로 감소하였다. 시효경화 처리 후의 경도변화는 대기 중 흡입주조 및 진공주조방법을 통해 제작된 제품 모두 $270^{\circ}C$에서 각각 154 HV, 166 HV로 가장 높은 경도 값을 나타내었고, $270^{\circ}C$ 이상에서는 과시효(over aging)현상으로 인해 경도 값이 다시 감소하는 경향을 나타내었다. EPMA mapping 분석을 통해 주조방법에 따라 각각 제품의 구성성분분포도를 확인하였다. 이를 통해 열처리 전 다소 불균일하게 분포되었던 성분들이 열처리 후 균일해짐을 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.322-322
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• 2011

White gold는 아름다운 광택과 손쉬운 가공성의 장점 때문에 장신구를 비롯한 다양한 분야에서 그 활용 가치가 매우 높다. 본 연구에서 우리는 열처리를 통한 white gold의 hardness강화 및 품질향상을 위하여 다양한 열처리 조건별 기계적 특성변화를 비교 관찰 하였다. 열처리 전 white gold alloy의 구성성분을 조사하기 위하여 EPMA와 ICP-MS를 사용하여 분석 후 그 값을 수치화 하였다. 14K, 18K White gold alloy 총 32개의 시료를 사용하여 $750^{\circ}C$, 30 min의 조건에서 solid treatment 및 quenching 후 $200^{\circ}C{\sim}350^{\circ}C$ 온도 범위에서 $50^{\circ}C$ 간격으로 age-hardening을 실시하였다. 열처리 전과 후 각 조건별 hardness 변화는 Vicker's hardness tester를 사용하여 측정하였다. 또한 age-hardening 후 모든 시료는 optical microscope (OM)을 사용하여 각 열처리 조건 별 grain 들의 배열 및 size의 변화를 관찰하였다. 열처리 전 14K, 18K white gold alloy의 hardness의 평균값은 각각 162 Hv와 196 Hv를 나타내었다. solid treatment 후 그 수치가 146 Hv, 172 Hv로 감소하였고, age-hardening 후에는 hardness 값이 점차 증가하여 14K는 $260^{\circ}C$에서 226 Hv, 18K는 $270^{\circ}C$에서 268 Hv의 가장 높은 수치를 나타내었다. 또한 14K 및 18K는 각각 $260^{\circ}C$, $270^{\circ}C$ 이상에서는 over-aging 현상을 나타내었다. OM 분석 결과 열처리 전 불균일했던 grain들의 배열이 solid treatment 및 quenching 후 다소 균일해짐을 확인할 수 있었고, grain size 또한 열처리 전에 비해 증가함을 알 수 있었다. Solid treatment 후 모든 시료의 hardness값이 전반적으로 감소하였다가 age-hardening을 통해 grain들의 배열이 점차 안정화 되면서 hardness가 증가 하였고, over-aging 구간에서는 급격히 감소하는 경향을 나타내었다. 이 결과들로부터 우리는 14K, 18K white gold alloy 에 대한 age-hardening 최적조건을 도출하였고, 각 열처리 조건별 grain 배열 상태의 변화를 관찰 할 수 있었다.