Sn-Ag-Cu-In-(Mn, Pd) 무연솔더의 솔더링성과 BGA 접합부 신뢰성

장재원,유아미,이종현,이창우,김준기,Jang, Jae-Won,Yu, A-Mi,Lee, Jong-Hyun,Lee, Chang-Woo,Kim, Jun-Ki 한국마이크로전자및패키징학회 2013 마이크로전자 및 패키징학회지 Vol.20 No.3

Sn-3.0Ag-0.5Cu 무연솔더에서 Ag 함량의 감소는 기계적 충격 신뢰성 향상에 도움이 되는 반면 솔더링성을 저하시키는 것으로 알려져 있다. 본 연구에서는 저 Ag함유 무연솔더의 솔더링성 향상을 위해 In을 첨가한 Sn-1.2Ag-0.7Cu-0.4In 4원계 조성과 여기에 미량의 Mn 및 Pd을 첨가한 무연솔더 조성에 대하여 솔더 젖음성을 평가하고, 보드 레벨 BGA 패키지의 열싸이클링 및 기계적 충격 신뢰성을 평가하였다. Sn-1.2Ag-0.7Cu 조성에 0.4 wt% In을 첨가한 합금의 젖음성은 Sn-3.0Ag-0.5Cu에 근접한 수준으로 향상되었으나, 패키지의 열싸이클링 신뢰성은 Sn-3.0Ag-0.5Cu에 미치지 못하는 것으로 나타났다. Sn-1.2Ag-0.7Cu-0.4In 조성에 0.03 wt% Pd의 첨가는 솔더 젖음성 및 패키지 신뢰성을 저하시킨 반면에 0.1 wt% Mn을 첨가한 합금은 특히 기계적 충격 신뢰성이 Sn-3.0Ag-0.5Cu는 물론 Sn-1.0Ag-0.5Cu보다도 우수한 수준으로 향상되었는데, 이는 Mn 첨가가 합금의 모듈러스를 감소시킨 데에 기인하는 것으로 생각된다. Although the lowering of Ag content in Sn-3.0Ag-0.5Cu is known to improve the mechanical shock reliability of the solder joint, it is also known to be detrimental to the solderbility. In this study, the quaternary alloying effect of In and the minor alloying effects of Mn and Pd on the solderability, thermal cycling and mechanical shock reliabilities of the low Ag content Sn-1.2Ag-0.7Cu solder were investigated using board-level BGA packages. The solderability of Sn-1.2Ag-0.7Cu-0.4In was proved to be comparable to that of Sn-3.0Ag-0.5Cu but its thermal cycling reliability was inferior to that of Sn-3.0Ag-0.5Cu. While the 0.03 wt% Pd addition to the Sn-1.2Ag-0.7Cu-0.4In decreased the solderability and reliabilities of solder joint, the 0.1 wt% Mn addition was proved to be beneficial especially for the mechanical shock reliability compared to those of Sn-3.0Ag-0.5Cu and Sn-1.0Ag-0.5Cu compositions. It was considered to be due that the Mn addition decreased the Young's modulus of low Ag content Pb-free solders.

다중 안테나를 이용한 전자 공격 신호 전송 시스템

장재원,류정호,박주래,Chang, Jaewon,Ryu, Jeong Ho,Park, Joo Rae 한국군사과학기술학회 2021 한국군사과학기술학회지 Vol.24 No.1

In electronic warfare, beamforming using multiple antennas is applied for effective transmission of electronic attack signals. In order to perform an electronic attack against multiple threats using the same frequency resource, it is necessary to apply a multi-beam transmission algorithm that has been studied in wireless communication systems. For electronic attacks against multiple threats, this paper presents an MMSE(Minimum Mean-Squared Error) beam-forming technique based on the prior location information of threats and an optimization method for power allocation. In addition, the performance of the proposed method is evaluated and received signals of multiple threats are compared and analyzed.

SOI 웨이퍼를 이용한 Top emission 방식 AMOLEDs의 스위칭 소자용 단결정 실리콘 트랜지스터

장재원,김훈,신경식,김재경,주병권,Chang, Jae-Won,Kim, Hoon,Shin, Kyeong-Sik,Kim, Jai-Kyeong,Ju, Byeong-Kwon 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.4

We fabricated a single crystal silicon thin film transistor for active matrix organic light emitting displays(AMOLEDs) using silicon on insulator wafer (SOI wafer). Poly crystal silicon thin film transistor(poly-Si TFT) Is actively researched and developed nowsdays for a pixel switching devices of AMOLEDs. However, poly-Si TFT has some disadvantages such as high off-state leakage currents and low field-effect mobility due to a trap of grain boundary in active channel. While single crystal silicon TFT has many advantages such as high field effect mobility, low off-state leakage currents, low power consumption because of the low threshold voltage and simultaneous integration of driving ICs on a substrate. In our experiment, we compared the property of poly-Si TFT with that of SOI TFT. Poly-Si TFT exhibited a field effect mobility of 34 $\textrm{cm}^2$/Vs, an off-state leakage current of about l${\times}$10$\^$-9/ A at the gate voltage of 10 V, a subthreshold slope of 0.5 V/dec and on/off ratio of 10$\^$-4/, a threshold voltage of 7.8 V. Otherwise, single crystal silicon TFT on SOI wafer exhibited a field effect mobility of 750 $\textrm{cm}^2$/Vs, an off-state leakage current of about 1${\times}$10$\^$-10/ A at the gate voltage of 10 V, a subthreshold slope of 0.59 V/dec and on/off ratio of 10$\^$7/, a threshold voltage of 6.75 V. So, we observed that the properties of single crystal silicon TFT using SOI wafer are better than those of Poly Si TFT. For the pixel driver in AMOLEDs, the best suitable pixel driver is single crystal silicon TFT using SOI wafer.

통신 신호 방향 탐지를 위한 광대역 다중 채널 수신기 개발

장재원,안준일,주증민,이동원,Chang, Jaewon,Ahn, Junil,Joo, Jeungmin,Lee, Dongweon 한국군사과학기술학회 2021 한국군사과학기술학회지 Vol.24 No.5

In wireless environments, wideband receivers are used in a communication intelligent system to detect unknown signals and obtain azimuth information. To design a wideband receiver that performs multiple signal detection and direction finding simultaneously, it is necessary to consider a reception structure composed of multiple channels. In this paper, we propose a wideband multi-channel receiver for direction finding of unknown wideband communication signals including frequency hopping signals. A signal processing method for detecting received signals and estimating azimuth information is presented, and components of the manufactured wideband receiver are described. In addition, test results of the signal detection performance by mounting the proposed wideband multi-channel receiver on the flight system are included.

부갑상선호르몬 분비가 저하된 혈액투석 환자에서 저칼슘투석액 사용시 칼슘감지수용체의 유전자 다형성에 따른 호르몬 분비의 변화

박태진 ( Tae Jin Park ),서장원 ( Jang Won Seo ),백관미 ( Kwan Mi Pack ),장재원 ( Jai Won Chang ),양원석 ( Won Seok Yang ),김순배 ( Soon Bae Kim ),이상구 ( Sang Koo Lee ),박수길 ( Su Kil Park ),박정식 ( Jung Sik Park ) 대한신장학회 2007 Kidney Research and Clinical Practice Vol.26 No.4

Purpose : Low level of parathyroid hormone (PTH) is a risk factor that might cause hip fracture in dialysis patients. Low calcium dialysate (LCD) has been suggested as an approach to increase PTH level. The calcium- sensing receptor (CaSR) polymorphism is known to be associated with the sensitivity to extracellular calcium. Methods : We prospectively investigated the role of genetic polymorphism of CaSR codon 990 as one cause of the different parathyroid responses to LCD in maintenance hemodialysis (HD) patients. 48 patients, using 3.5 mEq/L calcium dialysate, with intact PTH below 100 pg/ml for the last one year underwent HD sessions on 2.5 mEq/L calcium dialysate for 12 weeks. Serum intact PTH, total calcium, phosphorus, alkaline phosphatase (ALP) and bone-specific ALP (BAP) were measured monthly. The CaSR gene from peripheral lymphocytes was amplified to confirm the genotype by polymerase chain reaction. Results : According to the CaSR genetic polymorphism, subjects were divided into 3 groups, A/A (14.6%), A/G (45.8%) and G/G (39.6%). Twelve weeks later, intact PTH (48.5±25.4 to 89.0±49.4 pg/mL, p<0.01), and ALP (78.7±25.7 to 87.4±27.2 IU/L, p<0.01) increased significantly in G/G group, but not in non-G/G groups. However, BAP significantly increased in both G/G group (24.3±11.9 to 29.5±10.6 U/L, p<0.01) and in non-G/G groups (21.4±4.5 to 26.1±9.1 U/L, p<0.01). During the study period, levels of corrected total calcium and phosphorus were not significantly changed. Conclusion : The CaSR polymorphism, G/G genotype, strongly influenced the responsiveness of parathyroid gland to LCD, compared with non-G/G genotypes. However, bone formation may occur actively on LCD, irrespective of CaSR genetic polymorphism.

성대용종 환자의 후두미세수술 전후 공기역학 변수 변화

강영애(Kang, Young Ae),장재원(Chang, Jae Won),구본석(Koo, Bon Seok) 한국음성학회 2016 말소리와 음성과학 Vol.8 No.3

The present study examined the change of aerodynamic features after laryngomicrosurgery in patients with vocal polyps. Aerodynamic evaluation was performed in thirty-nine patients (15 males and 24 females) one week before surgery and four weeks after surgery. Evaluation protocols of vital capacity, maximum sustained phonation(MXPH), and voicing efficiency(VOFT) were used to collect 29 phonatory aerodynamic measures, requiring voice with a comfortable pitch and loudness. Statistically significant changes were found for phonation time and airflow values in the MXPH protocol, while changes were also found for airflow values, subglottal pressure values and acoustic resistance values in the VOFT protocol. Although phonation time was increased in both male and female patients, gender-dependent changes were found in airflow measurements. Men’s phonation time increased with no difference in airflow rate, but women’s phonation time increased with decreased airflow rate and lower subglottal pressure. The changes of aerodynamic features may be affected by women"s self-perceived change for vocal attitude, which was reducing sense of vocal effort after surgery.

기준클럭 지연회로를 이용한 신호 입력 시각 측정

장재원(Jae-Won Chang),김태식(Tae-Sik Kim),현정욱(Jung-Wook Hyun),이상정(Sang-Jeong Lee) 한국산학기술학회 2014 한국산학기술학회 학술대회 Vol.- No.-

본 논문에서는 수신기에 신호가 입력된 시각을 수신기 기준 클럭의 정밀도보다 더 정밀하게 측정하는 방법에 관하여 설명한다. 본 신호 측정 방안은 기존의 Interpolation과 같은 추정 방법과 달리 물리적으로 클럭의 발생 시점을 여러 단계로 지연시키고 그 결과를 이용하여 신호 입력 시각을 정밀하게 측정한다.

셀 간 협조적 공간 다중화 및 빔포밍을 이용한 하향링크 전송 효율 증대 방안

장재원(Jaewon Chang),진귀언(Gwyun Jin),성원진(Wonjin Sung) 대한전자공학회 2008 電子工學會論文誌-TC (Telecommunications) Vol.45 No.7

주파수 재사용 기법을 사용하는 셀룰러 시스템의 경우 단말기가 셀 경계로 이동할수록 인접 셀로부터 오는 간섭 신호의 영향을 받게 되어 성능 열화를 겪게 된다. 본 논문에서는 다중 셀 시스템의 하향링크 전송 시, 지리적으로 떨어져 있는 다수의 기지국에서 상호 협력을 통해 다중 안테나 단말기에 협조적으로 신호를 전송하는 경우 기지국들과 단말기 간에 형성된 분산 MIMO (multiple-input multiple-output) 채널을 이용하여 공간 다중화 및 빔포밍 이득을 얻을 수 있는 전송 방안 및 수신 기법을 제안한다. 특히, 주파수 재사용률과 단말기의 수신 안테나 개수의 변화에 따라 제안 기법의 유효 신호 대 간섭 비와 전송효율을 분석 및 산출하고, 기존 셀룰러 시스템에서 널리 사용되는 MRC (maximal ratio combining) 수신 기법의 성능과 비교한다. 셀 경계에서의 성능 이득을 비교함으로써 인접 셀 간섭이 큰 영역에서 제안 기법을 사용할 때 단말기의 전송 효율 향상 정도를 평가한다. In typical cellular systems using frequency reuse scheme, the terminal suffers a performance degradation due to the intercell interference signals from adjacent cells as the terminal moves toward the cell boundary. In this paper, a signal transmission and reception scheme which achieve spatial multiplexing and beamforming gain from a distributed MIMO (multiple-input multiple-output) channel using mutiple-antenna terminal is proposed for the spectral efficiency enhancement in a multi-cell downlink environment, when geographically separated base stations cooperatively transmit signals. In particular, we analyze the effective signal-to-interference ratio and spectral efficiency of the proposed scheme for differenct frequency reuse patterns and for varying numbers of receive antennas, and compare with the performance of the MRC (maximal ratio combining) reception scheme in typical cellular systems. We evaluate the amount of transmission efficiency of the scheme by comparing the performance near the cell boundary where the strong intercell interference is experienced.

듀얼 안테나 단말을 활용한 셀룰러 시스템의 링크 성능 향상 방안

장재원(Jaewon Chang),진귀언(Gwyun Jin),김성민(Seongmin Kim),임빈철(Bin-Chul Ihm),성원진(Wonjin Sung) 한국통신학회 2007 한국통신학회 학술대회논문집 Vol.2007 No.7

공항용 다변측정감시시스템 비행시험을 위한 시험환경 분석

장재원(Jae-Won Chang),김태식(Tae-Sik Kim),홍교영(Hong Gyo Young),이상정(Sang-Jeong Lee) 한국산학기술학회 2015 한국산학기술학회 학술대회 Vol.2015 No.1

공항용 다변측정감시시스템(LAM, Local Area Multilateration)의 기능 및 성능을 분석하기 위하여 최종적으로는 실제 활주로에서 비행시험을 수행하여야 한다. 본 논문에서는 한서대 태안비행장을 시험공항으로 가정하고 공항용 다변측정감시시스템의 필드시험절차를 만족하는지에 대한 검토를 위해 시험 환경 분석을 수행하였다. 수신기, 송신기와 기준트랜스폰더의 배치 위치를 선정하여 이에 대한 시뮬레이션을 통해 전파 도달 영역과 다변측정감시시스템 성능 분석을 수행하였다.