• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.97-100
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• 2003

The quasi-complementary turbo codes (QCTC) proposed by Kim [1] is used for a fast hybrid ARQ scheme with incremental redundancy and adaptive modulation coding in the cdma2000 1xEV-DV [2]. The QCTC provides various code rates with good performance, a very simple encoder structure, and an inherent channel interleaving. It is shown that the QCTC is a unified scheme of channel coding and channel interleaving. In this paper, we introduce the properties of QCTC and various hybrid ARQ-QCTC schemes for the system.

• Korean Journal of Materials Research
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• v.11 no.2
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• pp.88-93
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• 2001

The thermal behavior and the crystallographic characteristics of an epitaxial $C49-TiSi_2$ island formed in a Si (001) substrate by $N_2$, treatment were investigated by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). It was found from the analyzed results that the epitaxial $C49-TiSi_2$ was thermally stable even at high temperature of $1000^{\circ}C$ therefore did not transform into the C54-stable phase and did not deform morphologically. HRTEM results clearly showed that the epitaxial $TiSi_2$ phase and Si have the orientation relationship of (060)[001]$TiSi_2$//(002)[110]Si, and the lattice strain energy at the interface was mostly relaxed by the formation of misfit dislocations. Furthermore, the mechanism on the formation of the epitaxial $_C49-TiSi2$ in Si and stacking faults lying on the (020) plane of the C49 Phase were discussed through the analysis of the HRTEM image and the atomic modeling.

• Journal of Ginseng Research
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• v.36 no.2
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• pp.205-210
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• 2012

For quality control of components in Korean red ginseng powder and extract, a new method for simultaneous quantification of 12 ginsenosides ($Rg_1$, Re, Rf, $Rh_1$, $Rg_2$[S], $Rg_2$[R], $Rb_1$, Rc, $Rb_2$, Rd, $Rg_3$[S], and $Rg_3$[R]) was studied. Compared to the official method for quantification of marker substances (ginsenosides $Rg_1$ and $Rb_1$), the proposed methods were guaranteed by in-house method validation. Several criteria such as linearity, specificity, precision and accuracy were evaluated. For red ginseng powder, recovery (averaging 95% to 105%) was calculated, and analysis of variance was carried out to estimate the relative standard deviation (0.20% to 2.12%). For red ginseng extract, the average recovery rate was 90% to 99% and the relative standard deviation was 0.39% to 2.40%. These results indicate that the proposed method could be used in the laboratory for determination of 12 ginsenosides in red ginseng powder and extract. In addition, this method was found to be suitable for quality control of ginseng products and potentially offer time and cost benefits.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.908-909
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• 2011

전기 자동차용 전동기는 고출력, 소형화, 제어의 용이성 등으로 인해 영구자석형 전동기를 많이 채택하고 있는 추세이다. 이 중 IPM 전동기는 출력 특성 및 제어의 용이성으로 인해 많이 사용되고 있다. 특히 IPMSM을 EV용으로 적합하게 사용할 수 있도록 학계 및 산업계에서 전동기의 출력 개선, 열적 문제 해결, 구조 강도 문제 해결 등의 노력을 진행해왔다. 이 논문에서는 항복 강도를 고려하여 영구자석 센터 포스트 간격을 변화시키면서 전동기의 출력 특성을 살펴보았다.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.3
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• pp.69-73
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• 2010

The melt grafting of unsaturated silanes onto polypropylene (PP) in a twin-screw extruder and crosslinking in hot water were studied to enhance impact strength of polypropylene. The influence of grafting formulations on the melt flow rates of grafted PP and the gel percentages of crosslinked PP was investigated. 3-methacryloylpropyltrimethoxysilane (VMMS) unsaturated silane monomer was used. Benzoyl peroxide, (BPO) and Dicumyl peroxide (DCP) were used as an initiator. When benzoyl peroxide (BPO) was used as an initiator, higher gel percentage and impact strength than those of DCP has been observed. The maximum impact strength was obtained with 0.7 phr of BPO and 2phr of VMMS. The value is 8.7 kgf-cm/cm and it is on a parity with the value of with 20 phr of EOR mixed to PP.

• Journal of the Microelectronics and Packaging Society
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• v.18 no.2
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• pp.35-41
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• 2011

Recently, board level solder joint reliability performance of IC packages during drop impact becomes a great concern to semiconductor and electronic product manufacturers. The handheld electronic products are prone to being dropped during their useful service life because of their size and weight. The IC packages are susceptible to solder joint failures, induced by a combination of printed circuit board (PCB) bending and mechanical shock during impact. The board level drop testing is an effective method to characterize the solder joint reliability performance of miniature handheld products. In this paper, applying the JEDEC (JESD22-B111) standard present a finite element modeling of the FBGA. The simulation results revealed that maximum stress was located at the outermost solder ball in the PCB or IC package side, which consisted well with the location of crack initiation observed in the failure analysis after drop reliability tests.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.328-329
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• 2010

STATCOM은 전력전자 기반의 전압형 인버터를 이용한 무효 전력 보상장치로써 우수한 전압 제어 능력과 빠른 동작 특성, 그리고 운용 및 유지/관리의 유연성으로 인해 기존에 사용되던 무효 전력 보상장치들을 빠르게 대체하고 있다. 효성중공업에서는 국내 최초로 100MVA STATCOM을 개발하여 한전 실 계통에 설치/운용한 바 있고 이 경험을 바탕으로 최근 논의되고 있는 제주 50MVA STATCOM의 개발에 착수하였다. 본 논문에서는 이 프로젝트와 관련된 배경을 설명하고 연구 과정 중에 수행된 제주 전력 계통의 STATCOM 설치 효과 모의 결과에 대해서 소개하고자 한다.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1051-1053
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• 1999

In this work, thermal phenomena and temperature rise due to thermal source in electric switchboard were investigated using analytical measures. Electric switchboards are assemblies of panels on which are mounted switches, circuit breakers, high current busbars, meter, fuses and terminals essential to the operation of electric equipment. It is very difficult to predict the temperature rise in switchboard due to the existence of several heat sources. To overcome this situations, we focused on the eddy current distribution on the panel of switchboard caused by high current busbars as a fundamental basis. And thermal sources including busbar and switchgear have been considered. Furthermore, thermal transfer phenomena in switchboard was considered theoretically. Finally, three-dimensional thermal model for eddy current analysis has been adopted and FEM analysis was conducted. As a result, three-dimensional numerical analysis found to be applicable to the analysis of thermal phenomena in switchboard.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.5
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• pp.299-304
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• 2004

Influence of Ca addition on microstructure and room temperature mechanical properties has been studied for AZ31(Mg-3%Al-1%Zn-0.2%Mn)-(0~0.5)%Ca wrought alloys, based on experimental results from metallography, X-ray diffractometry and mechanical tests. Yield strength, ultimate tensile strength and hardness of the alloys increased remarkably with increasing Ca content, whereas elongation was deteriorated continuously. Microstructural examination revealed that Ca addition efficiently refined grains of ${\alpha}$(Mg) phase and that some of the Ca dissolved in ${\beta}(Mg_{17}Al_{12})$ precipitates. The former and the latter facts are thought to be responsible for improved strength and loss of ductility of the AZ31+Ca wrought alloys, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.19-20
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• 2000

We have developed the 12.1" SVGA reflective type color TFT-LCD(Thin Film Transistor - Liquid Crystal Display) with the high aperture ratio and well designed reflector for the applications such as mini note PC, Note PC and electronic book. The panel shows the high reflectance(30%) and contrast ratio(20:1) resulted from optimizing the optical films and designing the embossing shaped reflector. By improving the chromacity, the color reproducibility was increased up to 20%. As removing the backlight unit, we reduced the power consumption, thickness and weight of the panel to 0.8W, 2.2mm, and 250gram, respectively. According to the above performances, we have obtained fabrication process for mass production, and furthermore, could have access to fast market launching.