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Near-field exciton imaging of chemically treated MoS<sub>2</sub> monolayers
Kim, Youngbum,Lee, Yongjun,Kim, Hyun,Roy, Shrawan,Kim, Jeongyong The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.18
<P>The exciton-dominated light emission of two-dimensional (2D) semiconductors is determined largely by the doping state and the formation of defects. Extensive studies have shown that chemical treatment critically modifies the doping state and defect state of chemical vapor deposition (CVD)-grown or exfoliated monolayer MoS2 (1L-MoS2), suggesting a promising possibility for engineering the optoelectronic properties of 2D semiconductors. However, chemical treatment inevitably modifies both the doping state and defect states, and their independent roles in the exciton emission of 1L-MoS2 have been difficult to study, significantly limiting the practical and reliable uses of chemical treatment to improve the optical properties of 1L-TMDs. Herein, we used near-field imaging and spectroscopy to investigate the effects of chemical treatment on the exciton emission of 1L-MoS2. CVD-grown 1L-MoS2 was treated with bis(trifluoromethane)-sulfonimide (TFSI) or 7,7,8,8-tetracyanoquinodimethane (TCNQ), and nanoscale maps of neutral exciton and trion emission before and after chemical treatment were obtained with 80 nm spatial resolution. A comparison of the local spatial and spectral compositions of neutral excitons and trions suggested that the p-doping effect of TFSI was especially strong around local defects, whereas electron depletion by TCNQ was spatially uniform. The specific reaction of TFSI to defect locations observed in our study provides the clue for the reason that TFSI is notably effective at improving the light emission of 1L-MoS2.</P>
김영범(Youngbum Kim),조한철(Hancheul Jo),김명관(Myungkwan Kim),김유현(Youhyun Kim) 고려대학교 보건과학연구소 2004 보건과학논집 Vol.30 No.1
Quality Assurance in the radiation therapeutic field is very important for the maintenance of the radiation therapy equipment as well as the safety of patient and therapist.<BR> Currently daily Quality Assurance study follows 26 daily Quality Assurance items according to recommendation in KFDA. But the daily Quality Assurance was hard to check various items by a restriction in time on a characteristic. In order to solve this problem, we prepared the new QA sheet for new QA equipment.<BR> We examined check time on 26 items by a conventional method over a week and measured check time which used new Quality Assurance equipment. When new equipment was used, check time was shortened, and we can include Output check measured in weekly Quality Assurance in new daily Quality Assurance sheet.<BR> If new daily Quality Assurance sheet be used, a check can do conventional daily QA including output check in 20 minutes.
Youngbum Kim,이은지,Shrawan Roy,Anir S. Sharbirin,Lars-Gunnar Ranz,Thomas Dieing,Jeongyong Kim 한국물리학회 2020 Current Applied Physics Vol.20 No.1
A confocal Raman microscope (CRM) facilitates visualization of the spatial distribution of molecular bonds or phonon modes at the submicron level and has been extensively used in the characterization of nanomaterials and devices. The lateral and axial resolution is a key specification that defines the performance of CRM, however, the interpretation of spatial resolution in the literature is often ambiguous, making it often difficult to directly compare Raman images obtained under different conditions. In this report, a convenient and reliable measurement protocol using dispersed carbon nanotubes and suspended graphene as test specimens is proposed to facilitate the determination of the lateral and axial resolutions of a CRM. Spatial resolution values comparable to the results based on Rayleigh criterion calculations were obtained using Raman mapping images of test specimens. This was achieved without the need for complex deconvolution processes or the consideration of an asymmetric dielectric environment.
PLIB 파트 42의 데이터 사전 방법론을 이용한 자동차 부품의 분류체계
김영범(Youngbum Kim),한순홍(Soonhung Han) 한국자동차공학회 2001 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2001 No.5_2
For the B2B e-Commerce, standardization of electronic catalog which contains product and business data is important. Among many components of e-Catalog contents, item codes are defined by classification structure of items. Because of differences among item codes used in different manufacturing companies, exchange of product data for the e-Commerce is difficult. This paper studies the classification system of data dictionary type of PLIB (ISO 13584) part 42 which can establish the standard of product data and experiments the method to develop the data dictionary of automotive parts.<br/>
액셀러레이팅과 기업가정신이 스타트업의 스케일업에 미치는 영향에 관한 실증 연구
김영범(Kim, YoungBum),양동우(Yang, DongWoo) 한국창업학회 2021 한국창업학회지 Vol.16 No.6
액셀러레이터가 새롭게 등장한지 상당한 기간이 지났으나 스타트업의 성과에 미치는 영향에 대한 실증연구는 많지 않으며 특히 스케일업과 연계한 연구는 아직 찾아보기 어려운 실정이다. 본 연구는 액셀러레이팅과 기업가정신이 스타트업의 스케일업을 위한 혁신역량, 경영성과, 고용확대에 실제로 기여하는지 검증하는데 목적이 있다. 분석결과 첫째 액셀러레이터의 교육및멘토링이 스타트업의 스케일업을 위한 혁신역량에 정(+)의 영향을 미쳤으며 나머지 요인들은 영향을 미치지 않았고, 자금지원만이 경영성과에 정(+)의 영향을 미쳤다. 둘째 기업가정신의 혁신성, 진취성, 위험감수성 모두 혁신역량에 정(+)의 영향을 미쳤으며, 반면에 경영성과에는 위험감수성만 정(+)의 영향을 미쳤다. 셋째 액셀러레이팅과 기업가정신 모두 고용확대에 유의미한 영향을 미치지 않았다. 이러한 연구 결과는 아직까지 우리나라 액셀러레이팅의 교육및멘토링 등이 자금지원을 제외하고는 스타트업의 경영성과 및 고용확대에 직접적으로 영향을 미치기 보다는 혁신역량을 통해 간접적으로 영향을 미치고 있음을 알 수 있다. 따라서 스타트업의 스케일업을 위해서는 액셀러레이터의 초기투자 등 자금지원이 필수적이고, 액셀러레이팅의 내실화와 스타트업과의 장기지속적인 관계유지의 필요성을 시사하고 있다. It has been a while since accelerators were newly introduced, but there are not many empirical studies on the effect of accelerators regarding the performance of startups, and in particular, there is a lack of studies related to scale-up. The purpose of this study is to verify whether accelerating and entrepreneurship actually contribute to the innovation capacity, business performance, and employment expansion for the scale-up of startups. The analysis reveals that first, accelerator education and mentoring had positive(+) effects on the innovation capability for scale-up of startups, and the rest of the factors had no effect. except for financial support which had positive(+) effect on the business performance. Second, innovativeness, proactiveness, and risk taking of entrepreneurship all had positive(+) effects on innovation capability, while on business performance only risk taking had a positive(+) effect. Third, neither accelerating nor entrepreneurship had significant effect on employment expansion. These research findings show that Korea s accelerating education and mentoring are indirectly influencing through innovation capabilities, rather than directly affecting the business performance and employment expansion of startups, except for financial support. Therefore, for the scale-up of startups, financial support such as initial investment from accelerators is essential, suggesting the necessity to improve the effectiveness of accelerating and maintain long-lasting relationships with startups.