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간편 결제 서비스 수용의도에 영향을 미치는 요인에 관한 연구
하준석,강문식,이동만 한국인터넷전자상거래학회 2017 인터넷전자상거래연구 Vol.17 No.6
With the explosive growth in the FinTech industry, and the remarkable growth of e-commerce, many companies in the financial and non-financial sectors are launching competitive simple mobile payment services. This study examines key factors influencing the acceptance intention of mobile payment services, and its purpose is to define what the leading factors of the acceptance of mobile payment services are. The model suggested in this study was based on the Technology Acceptance Model(TAM). This study was conducted through a survey which collected data from 351 users of the mobile payment services. The results of this study will provide a theoretical foundation on the research of identifying factors affecting users' intention to adopt the mobile payment services. We expect that the crucial information about main factors influencing the intention to adopt, such as, self-efficacy, familiarity, simplicity, stability, ubiquity, and personalization, will be offered to working-level officials of the company.
플립칩 공정시 반응생성물이 계면반응 및 접합특성에 미치는 영향
하준석,정재필,오태성,Ha, Jun-Seok,Jung, Jae-Pil,Oh, Tae-Sung 한국마이크로전자및패키징학회 2012 마이크로전자 및 패키징학회지 Vol.19 No.2
플립칩 접합시 발생하는 계면반응 거동과 접합특성을 계면에 생성되는 금속간화합물의 관점에서 접근하였다. 이를 위하여 Al/Cu와 Al/Ni의 under bump metallization(UBM) 층과 Sn-Cu계 솔더(Sn-3Cu, Sn-0.7Cu)와의 반응에 의한 금속간화합물의 형성거동 및 계면접합성을 분석하였다. Al/Cu UBM 상에서 Sn-0.7Cu 솔더를 리플로우한 경우에는 솔더/UBM 계면에서 금속간화합물이 형성되지 않았으며, Sn-3Cu를 리플로우한 경우에는 계면에서 생성된 $Cu_6Sn_5$ 금속간화합물이 spalling 되어 접합면이 분리되었다. 반면에 Al/Ni UBM 상에서 Sn-Cu계 솔더를 리플로우한 경우에는 0.7 wt% 및 3 wt%의 Cu 함량에 관계없이 $(Cu,Ni)_6Sn_5$ 금속간화합물이 계면에 형성되어 있었으며, 계면접합이 안정적으로 유지되었다. We studied interfacial reaction and bonding characteristics of a flip chip bonding with the viewpoint of formation behavior of intermetallic compounds. For this purpose, Sn-0.7Cu and Sn-3Cu solders were reflowed on the Al/Cu and Al/Ni UBMs. When Sn-0.7Cu was reflowed on the Al/Cu UBM, no intermetallic compounds were formed at the solder/UBM interface. The $Cu_6Sn_5$ intermetallic compounds formed by reflowing Sn-3Cu solder on the Al/Cu UBM were spalled from the interface, resulting in delamination of the solder/UBM interface. On the other hand, the $(Cu,Ni)_6Sn_5$ intermetallic compounds were formed by reflowing of Sn-0.7Cu and Sn-3Cu on the Al/Ni UBM and the interfacial bonding between the Sn-Cu solders and the Al/Ni UBM was kept stable.
HF 크리닝 처리한 코발트실리사이드 버퍼층 위에 PA-MBE로 성장시킨 GaN의 에피택시
하준석(Ha, Jun-Seok),장지호(Chang, Ji-Ho),송오성(Song Ohsung) 한국산학기술학회 2010 한국산학기술학회논문지 Vol.11 No.2
실리콘 기판에 GaN 에피성장을 확인하기 위해, P형 Si(100) 기판 전면에 버퍼층으로 10 ㎚ 두께의 코발트실 리사이드를 형성시켰다. 형성된 코발트실리사이드 층을 HF로 크리닝하고, PA-MBE (plasma assisted-molecular beam epitaxy)를 써서 저온에서 500 ㎚의 GaN를 성막하였다. 완성된 GaN은 광학현미경, 주사탐침현미경, TEM, HR-XRD를 활용하여 특성을 확인하였다. HF 크리닝을 하지 않은 경우에는 GaN 에피택시 성장이 진행되지 않았다. HF 크리닝을 실시한 경우에는 실리사이드 표면의 국부적인 에칭에 의해 GaN성장이 유리하여 모두 GaN 4 ㎛ 정도의 두께를 가진 에피택시 성장이 진행되었다. XRD로 GaN의 <0002> 방향의 결정성 (crsytallinity)을 ω-scan으로 판단한 결과 Si(100) 기판의 경우 2.7도를 보여 기존의 사파이어 기판 정도로 우수할 가능성이 있었다. 나노급 코발트실리사이드를 버퍼로 채용하여 GaN의 에피성장이 가능할 수 있었다. We fabricated 10 ㎚-thick cobalt silicide(CoSi2) as a buffer layer on a p-type Si(100) substrate to investigate the possibility of GaN epitaxial growth on CoSi2/Si(100) substrates. We deposited 500 ㎚-GaN on the cobalt silicide buffer layer at low temperature with a PA-MBE (plasma assisted-molecular beam epitaxy) after the CoSi2/Si substrates were cleaned by HF solution. An optical microscopy, AFM, TEM, and HR-XRD (high resolution X-ray diffractometer) were employed to determine the GaN epitaxy. For the GaN samples without HF cleaning, they showed no GaN epitaxial growth. For the GaN samples with HF cleaning, they showed 4㎛-thick GaN epitaxial growth due to surface etching of the silicide layers. Through XRD ω-scan of GaN <0002> direction, we confirmed the cyrstallinity of GaN epitaxy is 2.7° which is comparable with that of sapphire substrate. Our result implied that CoSi2/Si(100) substrate would be a good buffer and substrate for GaN epitaxial growth.
박진섭,하준석,홍순구,Seog Woo Lee,Meoung Whan Cho,Takafumi Yao,이해우,이상화,이성근,이효종 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.2
We investigated the nucleation and growth behavior of GaN on various powders by hydride vapor phase epitaxy. In relative comparison, the nucleation tendency of GaN on each powder can be summarized as AlN >LaN, TiN, NbN > ZrN > ZrB2 > VN, BeO, indicating that the number of nucleation sites increased from right to left. LaN and NbN have not yet been reported as buffer materials for GaN growth. Of these, NbN is expected to be a good buffer material because the interatomic distance on the NbN (111) plane has only 2% difference from that on the GaN (0001) plane.
이현재,하준석,Hyo-Jong Lee,Seogwoo Lee,Meoungwhan Cho,T. Yao,김진교,홍순구,장지호 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.6
The effect of refined nitridation of sapphire substrates on the characteristics of GaN layers subsequently grown by using hydride vapor phase epitaxy (HVPE) was investigated. When low-temperature-grown (LTG) GaN buffer layers were grown on nitridated sapphire substrates in a refined way, the structural characteristics of the LTG GaN layers were found to be transferred to the subsequent high-temperature-grown (HTG) GaN layers. This result implies that well-controlled nitridation of sapphire substrates plays an important role and that the quality of the HTG GaN layer can be rationally controlled by monitoring the characteristics of a LTG GaN buffer layer when it is grown on a properly nitridated sapphire substrate.
Reduction of Leakage Current in InGaN-based LEDs with V-pit Embedded Structures
박진섭,하준석 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.9
We investigated the effects of V-pit structures embedded in the active region of n-GaN on leakage current and emission efficiency in InGaN/GaN light-emitting diodes (LEDs). Size-controlled V-pits were used for dislocation filtering. The V-shaped pit size was controlled by manipulating the growth temperature and pressure. The highest reverse voltage values were achieved with 150-nm-sized V-pit-embedded LEDs, which can be attributed to the effective blocking of the threading dislocations acting as a leakage current source.
저온수열합성방법에 의해 성장한 ZnO 나노로드의 전구체 몰농도 변화에 따른 특성 연구
문대화,하준석,Mun, D.H.,Ha, J.S. 한국마이크로전자및패키징학회 2013 마이크로전자 및 패키징학회지 Vol.20 No.1
In this research, we investigated the effect of mole concentration of precursor on morphological, structural and optical properties of ZnO nanorods. ZnO nanorods were hydrothermally grown on c-plane sapphire substrates in aqueous solution which contains zinc nitrate hexahydrate and hexamethylenetetramine at 90oC in the precursor range of 0.01 M to 0.025 M. With the increase of mole concentration, length and diameter of ZnO nanorods increased. In all the conditions, the growth direction of rods was longitudinally c-axis direction. From the strong emission peak at 380 nm of PL spectra at room temperature, we could confirm that the crystal quality of ZnO nanorods is good to emit radiative recombination spectra. 전구체의 농도가 ZnO 나노로드의 성장에 미치는 영향에 대하여 알아보았다. ZnO 나노로드는 수열합성법에 의하여 c-plane 사파이어 상에서 성장되었으며, 전구체 농도가 0.01M에서 0.025M로 증가할 때의 형태적, 구조적, 광학적 성질의 변화에 대하여 주사전자현미경, X-선 회절분석기, 그리고 Photoluminescence(PL) 분석을 통하여 알아보았다. 전구체의 몰 분율이 증가함에 따라서 나노로드의 두께와 길이가 모두 증가하는 경향을 보였으며, 성장 방향은 모두 c-axis 방향임을 알 수 있었다. PL 측정에서의 380 nm파장의 강한 emission으로부터, 수열합성법에 의하여 성장된 ZnO 나노로드는 결함의 영향이 적고 양호하게 성장되어 있음을 확인할 수 있었다.