• 한국산업융합학회 논문집
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• 제26권5호
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• pp.813-823
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• 2023

In this study, microstructure, hardening layer hardness, and case depth were evaluated after induction hardening(IH) of base metal specimen(BM) treated with annealing and quenching-tempering specimen(QT) treated with quenching and tempering. The microstructure after IH was significantly influenced by the microstructure before IH and the induction coil heating movement speed, but the effect of the induction frequency was very small. The hardness of the hardened layer at an induction coil heating movement speed of 15 mm/s or less was more influenced by the microstructure before IH than the induction coil travel speed and induction frequency. The induction coil travel speed has the significantly effect on the case depth, the induction frequency has effect and the microstructure before IH has a small effect.

• 한국통신학회논문지
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• 제36권11B호
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• pp.1357-1362
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• 2011

아날로그 텔레비전에서 디지털 텔레비전으로 전환할 때 TVWSs (TV White Spaces)가 발생된다. TVWSs에는 일부 무선 통신 시스템이 사용가능하며, 예를 들면 면허가 필요하지 않는 WiFi (Wireless Fidelity)가 있다. 또한, TVWSs는 VHF와 UHF의 사이에 주파수로써, 현재 WiFi가 사용하고 있는 2.4 GHz 및 5 GHz주파수와 비교할 때 TVWSs는 WiFi보다 더 큰 적용범위를 제공하고 건물에 대한 더 높은 침투력을 갖고 있다. 그러므로 본 연구는 WiFi가 TVWSs 주파수 구간에서 사용 가능하다고 가정한 후, DTV에 대한 WiFi의 간섭영향을 분석하였다. SEAMCAT (Spectrum Engineering Advanced Monte-Carlo Analysis Tool)을 이용하여 DTV 수신기가 받는 간섭 확률을 분석하였다. 분석결과 20개의 WiFi 사용자가 동시에 최대 전송전력으로 작동하였고 22 MHz 가드 밴드가 요구되었으며, WiFi 사용자와 DTV 수신기간의 보호거리가 6km이상일 때 DTV 수신기의 5%이하 간섭확률 성능을 만족할 수 있는 것으로 나타났다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권2호
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• pp.301-306
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• 2015

An ultra-compact and wideband low noise amplifier (LNA) in a quad flat non-leaded (QFN) package is presented. The LNA monolithic microwave integrated circuit (MMIC) is implemented in a $0.25{\mu}m$ GaN IC technology on a Silicon Carbide (SiC) substrate provided by Triquint. A source degeneration inductor and a gate inductor are used to obtain the noise and input matching simultaneously. The resistive feedback and inductor peaking techniques are employed to achieve a wideband characteristic. The LNA chip is mounted in the $3{\times}3-mm^2$ QFN package and measured. The supply voltages for the first and second stages are 14 V and 7 V, respectively, and the total current is 70 mA. The highest gain is 13.5 dB around the mid-band, and -3 dB frequencies are observed at 0.7 and 12 GHz. Input and output return losses ($S_{11}$ and $S_{22}$) of less than -10 dB measure from 1 to 12 GHz; there is an absolute bandwidth of 11 GHz and a fractional bandwidth of 169%. Across the bandwidth, the noise figures (NFs) are between 3 and 5 dB, while the output-referred third-order intercept points (OIP3s) are between 26 and 28 dBm. The overall chip size with all bonding pads is $1.1{\times}0.9mm^2$. To the best of our knowledge, this LNA shows the best figure-of-merit (FoM) compared with other published GaN LNAs with the same gate length.

• Asian-Australasian Journal of Animal Sciences
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• 제25권11호
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• pp.1521-1528
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• 2012

Previously identified QTL regions on BTA1 and BTA5 were investigated to validate the QTL regions and to identify candidate genes for growth and carcass traits in commercial cattle populations from the USA and Korea. Initially, a total of 8 polymorphic microsatellite (MS) markers in the BTA1 and 5 QTL regions were used for Chi-square tests to compare the frequencies of individual alleles between high and low phenotypic groups for the US (Michigan Cattleman's Association/Michigan State University; MCA/MSU) cattle. For a subsequent study, 24 candidate genes containing missense mutations and located within the QTL regions based on bovine genome sequence data were analyzed for genotyping in the two commercial cattle populations. Re-sequencing analyses confirmed 18 public missense SNPs and identified 9 new SNPs. Seventeen of these SNPs were used for genotyping of the MCA/MSU cattle (n = 98) and Korean native cattle (n = 323). On BTA1, UPK1B, HRG, and MAGEF1 polymorphisms residing between BM1312 and BMS4048 were significantly associated with growth and carcass traits in one or both of the MCA/MSU and Korean populations. On BTA5, ABCD2, IL22 and SNRPF polymorphisms residing between BL4 and BR2936 were associated with marbling and backfat traits in one or both of the MCA/MSU and Korean cattle populations. These results suggested that BTA 1 and 5 QTL regions may be segregating in both Korean Hanwoo and USA commercial cattle populations and DNA markers tested in this study may contribute to the identification of positional candidate genes for marker-assisted selection programs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.245.2-245.2
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• 2013

Solution processed organic photovoltaic devices have relatively less attention compared to polymer photovoltaic devices even though they have high possibility to be developed because they have both advantages of polymer and organic, such as solution processable, no synthetic batch dependence of photovoltaic performance, high purity and high charge carrier mobility as well as relatively high efficiency (~7%). In addition, solution processed organic photovoltaic devices have an advantage of easiness to study the relationship between the molecular structure and photovoltaic performance due to its simple structure. In this work, five isoindigo based low band gap donor-acceptor-donor (D-A-D) small molecules with different electron donating strength were synthesized for investigating the relationship between the molecular structure and photovoltaic performance, especially, investigating the effects of different electron donating effect of donor group in isoindigo backbone to photovoltaic device performance. The variation of electron donating strength of donor group strongly affected the optical, thermal, electrochemical and photovoltaic device performances of isoindigo organic materials. The highest power conversion efficiency of ~3.2% was realized in bulk heterojuction photovoltaic device consisted of the ID3T as donor and PC70BM as acceptor. This work demonstrates the great potential of isoindigo moieties as electron deficient units as well as guideline for synthesis of donor-acceptor-donor (D-A-D) small molecules for realizing highly efficient solution processed organic photovoltaic devices.

• Asian-Australasian Journal of Animal Sciences
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• 제23권3호
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• pp.287-291
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• 2010

The purpose of this study was to detect quantitative trait loci (QTL) for growth and carcass quality traits on BTA6 in a population of Hanwoo cattle. Three hundred and sixty one steers were produced from 39 sires that were sired by 17 grandsires in the two Hanwoo farming branches of the National Livestock Research Institute of Korea, between Spring 2000 and Fall 2002. DNA samples were collected for all of the steers, sires and grandsires, and the phenotypes for six growth and carcass quality traits were measured at 24 months of age. Twelve microsatellite markers were chosen on BTA6 and a linkage map was constructed by using seven of the twelve markers. Then, a chromosome-wide QTL scan was performed by applying an Animal Model, in which effects of QTL alleles within the grand sires were fitted as a random term. Three QTL were detected at the 5% chromosome-wise level for backfat thickness, average daily gain, and final weight. The most likely positions for the QTL were in the proximal region, i.e. 0 cM, 35 cM, and 63 cM, respectively. Also, another QTL for longissimus dorsi muscle area was detected at the 10% chromosome-wise level at 67 cM. These results were, in general, consistent with our previous report, in which candidate gene analyses showed that a SNP near ILSTS035 flanked by BM4621 (62.5 cM) and BMS2460 (81.3 cM) was associated with final weight, carcass weight, average daily gain, and longissimus dorsi muscle area in the same Hanwoo population.

• 스마트미디어저널
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• 제4권2호
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• pp.55-61
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• 2015

A bandwidth-enhanced ultra-wide band (UWB) CMOS balun-LNA is implemented as a part of a software defined radio (SDR) receiver which supports multi-band and multi-standard. The proposed balun-LNA is composed of a single-to-differential converter, a differential-to-single voltage summer with inductive shunt peaking, a negative feedback network, and a differential output buffer with composite common-drain (CD) and common-source (CS) amplifiers. By feeding the single-ended output of the voltage summer to the input of the LNA through a feedback network, a wideband balun-LNA exploiting negative feedback is implemented. By adopting a source follower-based inductive shunt peaking, the proposed balun-LNA achieves a wider gain bandwidth. Two LNA design examples are presented to demonstrate the usefulness of the proposed approach. The LNA I adopts the CS amplifier with a common gate common source (CGCS) balun load as the S-to-D converter for high gain and low noise figure (NF) and the LNA II uses the differential amplifier with the ac-grounded second input terminal as the S-to-D converter for high second-order input-referred intercept point (IIP2). The 3 dB gain bandwidth of the proposed balun-LNA (LNA I) is above 5 GHz and the NF is below 4 dB from 100 MHz to 5 GHz. An average power gain of 18 dB and an IIP3 of -8 ~ -2 dBm are obtained. In simulation, IIP2 of the LNA II is at least 5 dB higher than that of the LNA I with same power consumption.

• 대한전자공학회논문지SD
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• 제44권3호
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• pp.20-25
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• 2007

본 논문에서는 $LiNbO_3$의 선택적 영역을 도메인 반전을 수행하였으며, 이를 대역변조기 및 SSB 광변조기 제작에 응용하였다. 인가전압에 대한 회로적인 응답전류를 분석 및 고려함으로써 도메인 벽의 이동속도를 정확히 제어할 수 있었다. 과도한 도메인의 벽 이동속도에 의한 도메인 반전 형상을 확인하였고, 또한 도메인 벽의 진행방향에 따라 그 속도의 차이가 발생함을 알 수 있었다. 제작된 대역변조기는 30.3 GHz를 중심주파수로 하여 5.1GHz의 3dB 대역폭을 보였고. SSB 광변조기의 변조 스펙트럼으로부터 19dBm의 5.8GHz RF 입력신호에 대해 USB가 LSB에 비해 33dB정도 억제됨을 확인할 수 있었다.

• 한국정보전자통신기술학회논문지
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• 제11권6호
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• pp.732-741
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• 2018

여러 배터리 셀을 직렬로 연결해서 사용하는 BMS에서 사용 가능 용량을 최대화시키기 위하여 각 셀의 전압을 같도록 맞춰주는 셀 밸런싱 기술이 필요하다. 다중 권선 변압기를 사용하는 능동 셀 밸런싱 회로에서 셀 간 직접적 (direct cell-to-cell)으로 에너지를 전달하는 밸런싱 회로는 PMOS 스위치와 NMOS 스위치를 구동하기 위한 게이트 구동 칩은 PMOS 스위치와 NMOS 스위치 개수 만큼 TLP2748 포토커플러(photocoupler)와 TLP2745 포토커플러가 필요하므로 원가가 증가하고 집적도가 떨어진다. 그래서 본 논문에서는 포토커플러를 사용하여 PMOS와 NMOS 스위칭소자를 구동하는 대신 70V BCD 공정기반의 PMOS 게이트 구동회로와 NMOS 게이트 구동회로, 스위칭 시간이 개선된 PMOS 게이트 구동회로와 NMOS 게이트 구동회로를 제안하였다. 스위칭 시간이 개선된 PMOS 게이트 구동 스위치의 ${\Delta}t$는 8.9ns이고, NMOS 게이트 구동 스위치의 ${\Delta}t$는 9.9ns로 양호한 결과를 얻었다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.59-61
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• 2021

최근 선박/해양설치선의 운항 과정에서 오염물질과 온실가스 배출을 최소화하기 위한 전기추진개발이 진행되고 있다. 이에 필요한 선박/해양설치선 내 ESS 시스템인 배터리의 사용과 효율적 관리에 대한 중요성이 높아지고 있다. 통상적으로 Battery가 적용된 ESS는 BMS에 의해 Cell Balancing 및 수명이 실시간 모니터링이 되고 있다. 선박/해양설치선에는 여러 개소의 ESS Room을 탑재하고 있으며, 최근 전기추진개발 수요로 동일 사양의 ESS 시스템이 적용된 ESS Room이 구성되고 있다. 본 논문에서는 각 Room의 BMS Data를 비교하여 Battery Pack 및 Cell Balancing의 고장을 추가적으로 예측 진단하는 알고리즘을 제안한다. 제안한 알고리즘은 선박/해양설치선의 환경변화에 따른 각 ESS Room의 BMS Data를 비교하여 정확한 상태정보를 측정하고 신뢰성있게 모니터링하여 대형사고를 미연에 방지할 수 있다.