Organic Solar Cells: Solution‐Processable Reduced Graphene Oxide as a Novel Alternative to PEDOT:PSS Hole Transport Layers for Highly Efficient and Stable Polymer Solar Cells (Adv. Mater. 42/2011)

Yun, Jin‐,Mun,Yeo, Jun‐,Seok,Kim, Juhwan,Jeong, Hyung‐,Gu,Kim, Dong‐,Yu,Noh, Yong‐,Jin,Kim, Seok‐,Soon,Ku, Bon‐,Cheol,Na, Seok‐,In WILEY‐VCH Verlag 2011 Advanced Materials Vol.23 No.42

<P>Solution‐processable reduced graphene oxide as a hole‐transporting layer for highly efficient and stable organic solar cells is reported on page 4923 by Dong‐Yu Kim, Seok‐In Na, and co‐workers. Introduction of a newly reduced graphene oxide by simple solution processing into solar cells dramatically raises the cell efficiency and cell life‐time. The results will allow full use of chemically reduced graphene and will advance the realization of carbon‐based printable optoelectronic devices. </P>

고식적 검사로 간외 전이를 진단하지 못한 원발성 간암 환자에서 간이식 전에 시행한 전신 FDG-PET의 역할

이원우,류진숙,양유정,김재승,여정석,문대혁,이승규 대한핵의학회 2002 핵의학 분자영상 Vol.36 No.6

목적: 원발성 간암의 치료를 위해 간이식이 시행되고 있으나, 8-54%의 환자에서는 이식 후 원격 전이로 인한 재발이 보고 되고 있다. 이 연구는 간이식 예정인 원발성 간암 환자들에서 고식적인 검사로 진단하지 못한 간의 전이 진단에 있어서 FDG-PET의 유용성을 평가하고자 시행되었다. 대상 및 방법: 2001년 8월 이후 본원에서 간이식을 계획하고 전신 FDG-PET을 시행한 환자 중, FDG-PET 검사 이전에 복부 초음파와 CT, 흉부 x선 검사와 CT, 골스캔 등의 고식적인 검사를 시행하여 전이의 증거가 없거나(n=22), 애매한 이상 소견이 있었던(n=4) 원발성 간암 환자 26명(남:여=23:3), 평균 나이 55.7세)을 조사하였다. FDG-PET에서 양성을 보인 결과는 조직 검사나 임상적인 추적 검사로 전이 여부를 확인하였다. 결과: 고식적 검사에서 애매한 이상 소견이 있었던 환자 4명 중 3명의 6개 병변이 FDG-PET에서 국소 대사 항진을 보였고, 전이로 확인되어 간이식을 시행하지 않았다. 이 중 5 병변들은 의심되지 않았던 부위에서 새로 발견된 것이었다. 다른 1명은 PET에서 음성 소견으로 간이식을 시행하였다. 고식적인 검사에서 전이를 의심할 만한 소견이 없었던 22명 중에서는 5명의 환자에서 7개의 간의 국소 대사항진 병변들이 FDG-PET에서 발견되었는데, 이들 줄 1명은 2 개의 전이 병변이 확인되어 간이식을 시행하지 않았다. 다른 4명의 환자들에서 보인 5개의 국소 대사항진 병변들은 양성병변으로 확인되었고 이 중 3명은 간이식을 시행하였다. 요약하면, FDG-PET으로 4명의 환자에서 고식적인 검사로 찾지 못하던 전이 병변을 찾아 불필요한 간이식을 피할 수 있었다. 모두 17명에서 간이식이 시행되었다. 간의 조직 검사 소견과 비교하였을 때 생존 원발성 간암을 진단하는 FDG-PET의 민감도는 55.6% (5/9)이었고, 특이도는 87.5% (7/8)이었다. 결론: FDG-PET 전신 스캔은 간이식 예정인 원발성 간암 환자들에서 이전에 시행한 고식적인 검사들로 진단하지 못한 전이 병소들을 추가로 진단하여 불필요한 간이식 수술을 줄이는데 기여할 수 있었다. Purpose: Liver transplantation (LT), one of the therapeutic options of primary liver cancer has been suffering from recurrence caused by metastasis in 8-54% of patients. This study was performed to investigate whether FDG-PET is useful for detecting hidden metastasis in LT candidates. Materials and Methods: Twenty-six patients (male:female=23:3, mean age 55.7 year) underwent FDG-PET. Their previous conventional diagnostic studies (CDS) like a abdomen US and CT, chest x-ray and CT, and bone scan were negative (n=22) or equivocal (n=4) for metastasis. Positive FDG-PET findings were confirmed by biopsy or clinical follow-up. Results: Among 4 patients with equivocal metastatic lesions on CDS, 3 had 6 hypermetabolic lesions on FDG-PET, which were confirmed as metastasis and subsequently LTs were cancelled. Of these, 5 lesions were initially negative on CDS. Remained 1 patient underwent LT with a negative FDG-PET result. Among 22 patients without metastasis on CDS, 5 had 7 hypermetabolic lesions on FDG-PET. One of these patients proved to have 2 metastatic lesions, and LT was cancelled. The other 4patients had 5 hypermetabolic lesions on FDG-PET, which were confirmed as benign lesions, and 3 patients of them underwent LT. In summary, FDG-PET was useful in avoiding 4 unwarranted LT by detecting unsuspected metastatic lesions on CDS. A total of 17 patients underwent LT. In comparison with pathology, the sensitivity and specificity of FDG-PET for detecting viable primary liver cancer were 55.6% (5/9) and 87.5% (7/8), respectively. Conclusion: FDG-PET can detect additional hidden metastasis and contribute to reducing unwarranted LT in the patients with primary liver cancer. (Korean J Nucl Med 2002;36;368-80)

Highly efficient and stable planar perovskite solar cells with reduced graphene oxide nanosheets as electrode interlayer

Yeo, Jun-Seok,Kang, Rira,Lee, Sehyun,Jeon, Ye-Jin,Myoung, NoSoung,Lee, Chang-Lyoul,Kim, Dong-Yu,Yun, Jin-Mun,Seo, You-Hyun,Kim, Seok-Soon,Na, Seok-In Elsevier 2015 Nano energy Vol.12 No.-

<P><B>Abstract</B></P> <P>We demonstrate a simple solution and room-temperature processed reduced graphene oxide (RGO) as a novel hole-transporting material (HTM) to guarantee highly efficient and highly stable CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB> perovskite solar cells (PeSCs). The effects of RGO HTM are systemically investigated in terms of PeSC efficiency, PeSC stability, morphology of perovskite film, recombination dynamics, and charge-transport through CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB>/HTM interface. The resultant PeSC with a planar configuration of glass/ITO/RGO/CH<SUB>3</SUB>NH<SUB>3</SUB>PbI<SUB>3</SUB>/PC<SUB>61</SUB>BM/bathocuproine (BCP)/Ag exhibits improved device efficiency (maximum PCE of 10.8%) with high reproducibility than those of the reference devices using conventional PEDOT:PSS and GO HTMs. Also, the RGO-based PeSCs show highly desirable device stability in comparison to the PEDOT:PSS PeSCs.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly efficient and stable perovskite solar cells are developed using solution and room-temperature processed RGO. </LI> <LI> The resultant PeSC with planar architecture depicts a superior device efficiency (10.8%) to PEDOT:PSS- and GO-based solar cells. </LI> <LI> The use of RGO HTMs with the inherent passivation ability greatly extended the cell-operation time compared to PeSCs with PEDOT:PSS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Significant Vertical Phase Separation in Solvent-Vapor-Annealed Poly(3,4-ethylenedioxythiophene):Poly(styrene sulfonate) Composite Films Leading to Better Conductivity and Work Function for High-Performance Indium Tin Oxide-Free Optoelectronics

Yeo, Jun-Seok,Yun, Jin-Mun,Kim, Dong-Yu,Park, Sungjun,Kim, Seok-Soon,Yoon, Myung-Han,Kim, Tae-Wook,Na, Seok-In American Chemical Society 2012 ACS APPLIED MATERIALS & INTERFACES Vol.4 No.5

<P>In the present study, a novel polar-solvent vapor annealing (PSVA) was used to induce a significant structural rearrangement in poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films in order to improve their electrical conductivity and work function. The effects of polar-solvent vapor annealing on PEDOT:PSS were systematically compared with those of a conventional solvent additive method (SAM) and investigated in detail by analyzing the changes in conductivity, morphology, top and bottom surface composition, conformational PEDOT chains, and work function. The results confirmed that PSVA induces significant phase separation between excess PSS and PEDOT chains and a spontaneous formation of a highly enriched PSS layer on the top surface of the PEDOT:PSS polymer blend, which in turn leads to better 3-dimensional connections between the conducting PEDOT chains and higher work function. The resultant PSVA-treated PEDOT:PSS anode films exhibited a significantly enhanced conductivity of up to 1057 S cm<SUP>–1</SUP> and a tunable high work function of up to 5.35 eV. The PSVA-treated PEDOT:PSS films were employed as transparent anodes in polymer light-emitting diodes (PLEDs) and polymer solar cells (PSCs). The cell performances of organic optoelectronic devices with the PSVA-treated PEDOT:PSS anodes were further improved due to the significant vertical phase separation and the self-organized PSS top surface in PSVA-treated PEDOT:PSS films, which can increase the anode conductivity and work function and allow the direct formation of a functional buffer layer between the active layer and the polymeric electrode. The results of the present study will allow better use and understanding of polymeric-blend materials and will further advance the realization of high-performance indium tin oxide (ITO)-free organic electronics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2012/aamick.2012.4.issue-5/am300231v/production/images/medium/am-2012-00231v_0009.gif'></P>

In-depth considerations for better polyelectrolytes as interfacial materials in polymer solar cells

Yeo, Jun-Seok,Kang, Minji,Jung, Yen-Sook,Kang, Rira,Lee, Seung-Hoon,Heo, Youn-Jung,Jin, Sung-Ho,Kim, Dong-Yu,Na, Seok-In Elsevier 2016 Nano energy Vol.21 No.-

<P><B>Abstract</B></P> <P>We perform a comprehensive study to achieve better polyelectrolytes (PEs) as electron-transport layers (ETLs) in polymer solar cells (PSCs). Three well-known PEs – PFN, PEIE, and WPF – are chosen as model systems and investigated with variations in their backbone structures and the state of the amine functionalities on their side chains. Respectively optimized PSCs using the three PEs exhibit different cell-performances, mainly owing to the diode characteristics of built-in potential and recombination strength. To identify how such deviated device-performances correlate with the structural features of PEs, the modulated interfaces of ITO/PEs and PEs/active layer are studied in detail. It is found that conjugated backbones and larger counter-anions on side chains can promote the modulation of ITO work functions (WFs) and that a large amount of protonated amines on PEs is beneficial for junction properties with a subsequent active layer. Additionally, our results indicate that interfacial dipole and electrical doping between the PE and active layer, in addition to WF modulation of the ITO cathode, are important for device efficiency. Accordingly, with the aid of the molecular features of PEIE, PEIE-PSCs exhibit excellent device efficiency and stability compared with PFN- and WPF-PSCs. In the PTB7-th:PC<SUB>71</SUB>BM system, a remarkable power-conversion efficiency of 9.97% is achieved with a single PEIE ETL.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Chemical structure and performance of polyelectrolytes (PEs) in PSCs are correlated. </LI> <LI> Interfacial dipole and doping between PEs and active layer lead to efficient PSCs. </LI> <LI> PEIE-based PSCs have excellent device efficiency and high stability. </LI> <LI> Especially, in the PTB7-th system, encouraging efficiency of 9.97% is achieved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

개별 난방방식에서의 배관내 적정 유량 및 압력 유지 방안에 관한 연구

홍석진(Seok-Jin Hong),류성룡(Seong-Ryong Ryu),석호태(Ho-Tae Seok),여명석(Myoung-Souk Yeo),김광우(Kwang-Woo Kim) 대한설비공학회 2005 대한설비공학회 학술발표대회논문집 Vol.2005 No.6

Solution‐Processable Reduced Graphene Oxide as a Novel Alternative to PEDOT:PSS Hole Transport Layers for Highly Efficient and Stable Polymer Solar Cells

Yun, Jin‐,Mun,Yeo, Jun‐,Seok,Kim, Juhwan,Jeong, Hyung‐,Gu,Kim, Dong‐,Yu,Noh, Yong‐,Jin,Kim, Seok‐,Soon,Ku, Bon‐,Cheol,Na, Seok‐,In WILEY‐VCH Verlag 2011 Advanced Materials Vol.23 No.42

<P><B>The preparation of a reduced graphene oxide (pr‐Go) is with a novel p‐TosNHNH2 reductant</B> is demonstrated for use as an efficient anode interfacial layer for high‐performance and highstability organic solar cells (OSCs). The efficiency of the cells with pr‐GO is highly comparable to those of the PEDOT:PSSbased devices. Furthermore, the pr‐GO based OSCs show a much longer cell life time in air stability tests in comparison with PEDOT:PSS‐based cells.</P>

Zoster Sine Herpete는 원인을 모르는 늑간신경통의 원인인가?

여진석 ( Jin Seok Yeo ),심우석 ( Woo Seok Sim ),김용철 ( Yong Chul Kim ) 대한통증학회 2005 The Korean Journal of Pain Vol.18 No.2

증례보고 : 체외순환을 사용하지 않는 관상동맥 우회술에서 심장 전위를 위해 사용된 물주머니와 경식도 심장초음파 영상 개선

여진석 ( Jin Seok Yeo ),김태엽 ( Tae Yop Kim ),윤창룡 ( Chang Yong Yoon ),김준석 ( Jun Seok Kim ),지현근 ( Hyun Keun Chee ) 대한마취과학회 2007 Korean Journal of Anesthesiology Vol.52 No.2

During off-pump coronary artery bypass graft surgery (OPCAB), vigorous displacement and compression of the heart producing significant hemodynamic change are essential for optimal exposure of graft anastomoses. Intraoperative transesophageal echocardiography (TEE) is useful in determining hemodynamic compromise and prompting medical and mechanical support. However, in addition to the loss of contact between the heart and diaphragm during the displacement, swabs or snears underneath the heart interrupt the TEE signal transmission, resulting in a compromised transgastric (TG) TEE view. Therefore, TEE monitoring during OPCAB is usually limited to the mid-esophageal view. The authors placed a saline bag (a surgical glove filled with saline) underneath the heart to facilitate this anterior displacement of the heart, as well as avoid the signal interruption of the TG echocardiographic window. As a result, the optimal heart position with the minimal changes in LV regional wall motion, LV function and mitral regurgitation were found using the TG and other TEE views. The series of velocity-time integral of aortic valvular flow (VTI-Ao) in TG long axis view, in addition to SvO2, were then monitored as a surrogate marker of the cardiac output during a graft construction of the left circumflex artery. It was concluded that the use of a saline bag may be useful in avoiding compromise of the TG TEE view and determine the hemodynamic change using VTI-Ao during cardiac displacement for OPCAB. (Korean J Anesthesiol 2007; 52: 231~6)

Analysis of Phenolic Compounds Contents in the Kenaf Cultivars by HPLC.

Sun-Jin Kim,Eun-Hye Kim,Seok-Ju Kim,Hyun-Seok Jeon,Min-A Yeo,Yoon-Mi Jun,Jin-Hee Park,Jung-Woong Kwon,Sung-Hyun Song,Soo-Jung Yong,Mi-So Jang,Chang-Yeon Yu,Hong-Keun Song,Jong-Guk Ahn,Ill-Min Chung 한국작물학회 2010 한국작물학회 학술발표대회 논문집 Vol.2010 No.04

Phenolic compounds are naturally occurring secondary metabolites from various plants. These compounds play important roles in plant such as antioxident, antibacterial and anticancer effects. The purpose of this research was to analyze the phenolic compounds contents in Kenaf leaf and stem using High Performance Liquid Chromatograpy. Kenaf is widely distributed throughout the country and third largest fiber crop. Recently, interest in this crop is growing. But, there is little research on their functional material. The obtained results showed that phenolic compounds were significantly various among the examined cultivars of Kenaf. Especially, phenolic compounds contents of leaf were higher than those of stem. The highest concentration of phenolic compounds was in the E41 leaf(24358.99㎍/g) and the lowest concentration was in the Kenaf (in korea) stem(988.21㎍/g). The results of this experiment showed that its contents were different in leaf and stem. These results suggested that Kenaf can be used for functional plant.