Synthesis of carbon nanowalls on silicon by microwave plasma enhanced chemical vapor deposition

Chunyuan Lu(육춘원),Qi Dong(동기),T.G. Kim(김태규) 한국기계가공학회 2014 한국기계가공학회 춘추계학술대회 논문집 Vol.2014 No.4

Transition under Ambiguity: Koryǒ-Mongol Relations around 1260

Chunyuan Li(李春圓) 고려대학교 한국사연구소 2020 International Journal of Korean History Vol.25 No.1

1259년 몽골을 방문했던 고려 왕전(王倎) 사절단은 화북(華北)지역을 지나갔을 때 친 쿠빌라이 세력, 특히 그중의 유학자들과 긴밀하게 접촉했기 때문에 그 이후 정치적 혼란 속에서 쿠빌라이를 지지했다. 쿠빌라이 측근 유학자를 매개로 1260년 고려 왕희(王僖) 사절단은 쿠빌리이 정권으로부터 “출륙”(出陸)의 연기를 받아내는 데 성공하였다. 1260년 쿠빌라이 정권은 한 조서에서 한자 “藩”으로 고려를 지칭하고 조공 체계의 문화배경 속에서 고려의 지위를 확정하였다. 그러나 쿠빌라이 본인은 여전히 몽골 전통에 따라 고려의 역할을 설정하였다. 고려 사절단과 몽골 정권의 유학자들은 정치개념의 애매모호함을 활용해서 조공체제의 요소를 여몽관계에 주입시키면서 몽골제국의 외교전통을 크게 전환시켰다. A Koryǒ mission led by Wang Chǒn visited the Mongol in 1259 and had intense contacts with pro-Qubilai forces. Especially the Confucian scholars in North China, and therefore turned to Qubilai in the political turmoil. With the mediation of the scholar-ministers in Qubilai’s court, another Koryǒ mission led by Wang Hǔi in 1260 succeeded in seeking an allowance for postponement of the Koryǒ court’s return to the mainland (出陸). An edict composed by some scholar-minister of the Mongols in 1260 used the word fan (藩) to refer to the Koryǒ and defined it as a vassal under the tributary system. But Qubilai himself still regarded the Koryǒ as submitted following the tradition of the Mongols. Under a kind of ambiguity, the Koryǒ missions and the scholar-ministers of the Mongol together had brought new elements into the Koryǒ-Mongol relationship and altered the mongol tradition.

PERTURBATION ANALYSIS OF THE MOORE-PENROSE INVERSE FOR A CLASS OF BOUNDED OPERATORS IN HILBERT SPACES

Chunyuan Deng,Yimin Wei 대한수학회 2010 대한수학회지 Vol.47 No.4

Let H and K be Hilbert spaces and let T,T = T+δTbe bounded operators from H into K. In this article, two facts related to the perturbation bounds are studied. The first one is to find the upper bound of ∥T+T − T+T∥, which extends the results obtained by the second author and enriches the perturbation theory for the Moore-Penrose inverse. The other one is to develop explicit representations of projectors ∥T+T − T+T∥and ∥T+T − T+T∥. In addition, some spectral cases related to these results are analyzed.

Molecular Engineering of Carbazole based Hole-transporting Materials with Substitution Position Manipulation for Perovskite Solar Cell

Chunyuan Lu,In Taek Choi,Hwan Kyu Kim 한국고분자학회 2016 한국고분자학회 학술대회 연구논문 초록집 Vol.41 No.2

Law, Courts and Power Dynamics in the Context of HIV/AIDS - A Case Study of Taiwan

Chunyuan Lin 이화여자대학교 생명의료법연구소 2018 Asia Pacific Journal of Health Law & Ethics Vol.12 No.1

HIV/AIDS related stigma sometimes generates discrimination and social violence against people living with HIV/AIDS (PLWHA); therefore, whether the law shields them from an unreasonable invasion of their rights is a critical indication of the law’s function in rendering social justice. In Taiwan, despite the fact that the HIV/AIDS Regulatory Act has made progress in protecting the rights of PLWHA since the 1990s, discrimination remains. It is important to inquire how law evolves when social discrimination has prevailed, and whether the progress of legislation eliminates social discrimination and empowers PLWHAs in HIV-related disputes in the courts. This article explores the dynamics between social powers, law and courts, with a focus on the legal progress, court rulings, and the suffering of PLWHA in Taiwan. This article puts forward the following arguments: firstly, that the legal progress on HIV law is a product of elite-led social movement rather than a social consensus; and secondly, that courts reproduce social stigma and reinforce the social exclusion of PLWHA.

Characteristic Study of Boron Doped Carbon Nanowalls Films Deposited by Microwave Plasma Enhanced Chemical Vapor Deposition

Lu, Chunyuan,Dong, Qi,Tulugan, Kelimu,Park, Yeong Min,More, Mahendra A.,Kim, Jaeho,Kim, Tae Gyu American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.2

<P>In this research, catalyst-free vertically aligned boron doped carbon nanowalls films were fabricated on silicon (100) substrates by MPECVD using feeding gases CH4, H-2 and B2H6 (diluted with H-2 to 5% vol) as precursors. The substrates were pre-seeded with nanodiamond colloid. The fabricated CNWs films were characterized by Scanning Electron Microscopy (SEM) and Raman Spectroscopy. The data obtained from SEM confirms that the CNWs films have different density and wall thickness. From Raman spectrum, a G peak around 1588 cm(-1) and a D band peak at 1362 cm(-1) were observed, which indicates a successful fabrication of CNWs films. The EDX spectrum of boron doped CNWs film shows the existence of boron and carbon. Furthermore, field emission properties of boron doped carbon nanowalls films were measured and field enhancement factor was calculated using Fowler-Nordheim plot. The result indicates that boron doped CNWs films could be potential electron emitting materials.</P>

Phenothiazine Functionalized Multifunctional A−π-D−π-D−π-A-Type Hole-Transporting Materials via Sequential C-H Arylation Approach for Efficient and Stable Perovskite Solar Cells

Lu, Chunyuan,Paramasivam, Mahalingavelar,Park, Kyutai,Kim, Chul Hoon,Kim, Hwan Kyu American Chemical Society 2019 ACS APPLIED MATERIALS & INTERFACES Vol.11 No.15

<P>Three phenothiazine-based A−π-D−π-D−π-A-type small molecules containing various terminal acceptor units, which act as Lewis base blocks, have been synthesized via an efficient and step-economical, direct C-H arylation strategy in the aim toward the development of hole-transporting materials (HTMs) with multifunctional features (such as efficient hole extraction layer, trap passivation layer, and hydrophobic protective layer) for perovskite solar cells (PrSCs). Optical-electrochemical correlation and density functional theory studies reveal that dicyanovinylene acceptor in <B>SGT-421</B> downshifted the highest occupied molecular orbital (HOMO) level (−5.41 eV), which is more proximal to the valence band (−5.43 eV) of the perovskite, whereas <I>N</I>-methyl rhodanine in <B>SGT-420</B> and 1,3-indanedione (IND) in <B>SGT-422</B> destabilized the HOMO, leading to an increased interfacial energy-level offset. <B>SGT-421</B> exhibits superior properties in terms of a sufficiently low-lying HOMO level and favorable energy-level alignment, intrinsic hole mobility, interfacial hole transfer, hydrophobicity, and trap passivation ability over <I>spiro</I>-<B>OMeTAD</B> as a benchmark small-molecule HTM. As envisaged in the design concept, <B>SGT-421</B>-based PrSC not only yields a comparable efficiency of 17.3% to the state-of-art of <I>spiro</I>-<B>OMeTAD</B> (18%), but also demonstrates the enhanced long-term stability compared to the <I>spiro</I>-<B>OMeTAD</B> because of its multifunctional features. More importantly, the synthetic cost of <B>SGT-421</B> is estimated to be 2.15 times lower than that of <I>spiro</I>-<B>OMeTAD</B>. The proposed design strategy and the study of acceptor-property relationship of HTMs would provide valuable insights into and guidelines for the development of new low-cost and efficient multifunctional HTMs toward the realization of efficient and long-term stable PrSCs.</P> [FIG OMISSION]</BR>

PERTURBATION ANALYSIS OF THE MOORE-PENROSE INVERSE FOR A CLASS OF BOUNDED OPERATORS IN HILBERT SPACES

Deng, Chunyuan,Wei, Yimin Korean Mathematical Society 2010 대한수학회지 Vol.47 No.4

Let $\cal{H}$ and $\cal{K}$ be Hilbert spaces and let T, $\tilde{T}$ = T + ${\delta}T$ be bounded operators from $\cal{H}$ into $\cal{K}$. In this article, two facts related to the perturbation bounds are studied. The first one is to find the upper bound of $\parallel\tilde{T}^+\;-\;T^+\parallel$ which extends the results obtained by the second author and enriches the perturbation theory for the Moore-Penrose inverse. The other one is to develop explicit representations of projectors $\parallel\tilde{T}\tilde{T}^+\;-\;TT^+\parallel$ and $\parallel\tilde{T}^+\tilde{T}\;-\;T^+T\parallel$. In addition, some spectral cases related to these results are analyzed.

Transition under Ambiguity: Koryǒ-Mongol Relations around 1260

Li Chunyuan 고려대학교 한국사연구소 2020 International Journal of Korean History Vol.25 No.1

A Koryǒ mission led by Wang Chǒn visited the Mongol in 1259 and had intense contacts with pro-Qubilai forces. Especially the Confucian scholars in North China, and therefore turned to Qubilai in the political turmoil. With the mediation of the scholar-ministers in Qubilai’s court, another Koryǒ mission led by Wang Hǔi in 1260 succeeded in seeking an allowance for postponement of the Koryǒ court’s return to the mainland (出陸). An edict composed by some scholar-minister of the Mongols in 1260 used the word fan (藩) to refer to the Koryǒ and defined it as a vas-sal under the tributary system. But Qubilai himself still regarded the Koryǒ as submitted following the tradition of the Mongols. Under a kind of ambiguity, the Koryǒ missions and the scholar-ministers of the Mongol together had brought new elements into the Koryǒ-Mongol relationship and altered the mongol tradition.

Simple synthesis and molecular engineering of low-cost and star-shaped carbazole-based hole transporting materials for highly efficient perovskite solar cells

Lu, Chunyuan,Choi, In Taek,Kim, Jeongho,Kim, Hwan Kyu Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.38

<P>Perovskite solar cells (PrSCs) have emerged as a very promising technology in the field of photovoltaics by demonstrating power conversion efficiencies (PCEs) soaring from 3.9% to above 22% within the past eight years. To date, perovskite solar cells mainly depend on spiro-OMeTADto perform a key role as a hole transporting material (HTM). However, the complicated multi-step synthetic procedures and high-cost purification process for spiro-OMeTADlimited its potential for commercial application. Herein, three new carbazole-based HTMs with a starburst structure, coded asSGT-405(3,6),SGT-410(3,6) andSGT-411(3,6)<I>via</I>tuning the substitution position from the (2,7) to the (3,6) position of the carbazole moiety, have been successfully synthesized<I>via</I>three-step synthesis from commercially available reagents and investigated for highly efficient perovskite solar cells. By adopting this strategy, among them, molecularly engineered carbazole derivativeSGT-405(3,6) exhibits significantly increased<I>T</I>g(192.7 °C), improved film forming ability, reduced hole reorganization energy and enhanced hole mobility compared to its parent moleculeSGT-405(2,7) and spiro-OMeTAD. Owing to the promising properties ofSGT-405(3,6), meso-porous type PrSCs employingSGT-405(3,6) showed a remarkable PCE of 18.87%, which is better than that of the photovoltaic device employing spiro-OMeTAD(17.71%). To the best of our knowledge, the achieved PCE (18.87%) is the highest value reported for devices with the structure of FTO/compact TiO2/meso-porous TiO2/CH3NH3PbI3−xClx/HTM/Au employing small-molecular HTMs. Meanwhile, owing to the simple synthesis ofSGT-405(3,6), compared withSGT-405(2,7) previously developed by our group, synthesis cost was much lowered, resulting in low cost compared to the spiro-OMeTADandSGT-405(3,6), by approximately three times. Furthermore, the long-term device stability of PrSCs was enhanced forSGT-405(3,6) to some extent compared to those of other HTMs studied here due to the good uniform capping layer ofSGT-405(3,6) on top of the perovskite layer and the prevention of moisture penetration into the perovskite layer. Therefore,SGT-405(3,6) is a promising low-cost and efficient non-spiro type HTM with potential to replace expensive spiro-OMeTADfor PrSCs.</P>