Investigation of Solvent Effect on the Electrical Properties of Triisopropylsilylethynyl(TIPS) Pentacene Organic Thin-film Transistors

김경석,김영훈,한정인,최광남,곽성관,김동식,정관수,Kim, K.S.,Kim, Y.H.,Han, J.-In,Choi, K.N.,Kwak, S.K.,Kim, D.S.,Chung, K.S. The Korean Vacuum Society 2008 Applied Science and Convergence Technology Vol.17 No.5

본 논문은 TIPS Pentacene을 유기반도체로 사용한 유기박막 트랜지스터의 용제에 따른 전기적 특성에 대한 연구로서, 용제로는 chlorobenzene, p-xylene, chloroform, toluene을 사용하였으며, 회전 도포 방법을 사용하여 TIPS pentacene을 혼합하여 적층하였다. chlorobenzene을 사용하여 만들어진 유기박막 트랜지스터는 $1.0{\times}10^{-2}cm^2/V{\cdot}s$의 전계효과 이동도, $4.3{\times}10^3$의 on/off 비율, 5.5 V의 문턱전압의 특성을 보였다. 반대로, chloroform을 사용하여 만들어진 유기박막 트랜지스터는 $5.8{\times}10^{-7}cm^2/V{\cdot}s$의 전계효과 이동도, $1.1{\times}10^2$의 on/off 비율, 1.7 V의 문턱전압의 특성을 보였다. 또한 각 용제에 따른 TIPS pentacene 결정크기를 AFM을 통하여 측정하였다. 이와 같은 결과들을 통하여, 더 높은 끊는점을 가진 용제는 TIPS Pentacene의 더 큰 결정 크기와 높은 결정화 성향으로 인하여 더 좋은 전기적 특성을 가지는 것을 확인할 수 있었으며, 본 실험에서는 끓는점이 가장 높은 chlorobenzene을 사용한 TIPS Pentacene 유기박막 트랜지스터가 가장 좋은 전기적 특성을 나타내는 것을 확인하였다. In this paper, we investigated the electrical properties of triisopropylsilyl (TIPS) pentacene organic thin-film transistor (OTFT) depending on solvent type. We spin coated TIPS pentacene by using chlorobenzene, p-xylene, chloroform, and toluene as solvents. Fabricated OTFT with chlorobenzene shows field-effect mobility of $1.0{\times}10^{-2}cm^2/V{\cdot}s$, on/off ratio of $4.3{\times}10^3$ and threshold voltage of 5.5 V. In contrast, with chloroform, the mobility is $5.8{\times}10^{-7}cm^2/V{\cdot}s$, on/off ratio of $1.1{\times}10^2$ and threshold voltage of 1.7 V. Moreover we measured the grain size of each TIPS pentacene solvent by atomic force microscopy (AFM). From these results, it can be concluded that a solvent with higher boiling point results in better electrical characteristics due to large grain size and high crystallinity of TIPS pentacene layer. In this paper TIPS pentacene with chlorobenzene shows the best electrical properties.

내반슬로 인한 대퇴경골각의 변화가 골반경사각에 미치는 영향

김경석,류지미,김고운,김귀현,정원석,이종수,Kim, Kyoung-Seok,Ryu, Ji-Mi,Kim, Koh-Woon,Kim, Gwi-Hyun,Jeong, Won-Seok,Lee, Jong-Soo 척추신경추나의학회 2009 척추신경추나의학회지 Vol.4 No.2

Objectives : The purpose of this study was to investigate the Correlation between Pelvic angle and the Tibiofemoral angle in the Genu varum. Method : Age of All subjects were 20-37 years. 33(male 10, female 23) subjects were assessed by whole spine x-ray and orthogram. The collected data consisted of items on general characteristics, Pelvic Incidence(PI), Pelvic Tilt(PT), Sacral Slope(SS) and Tibiofemoral Angle(TFA) of the subjects. Results : The PI, PT and TFA had a relationship significantly. However, there was no relationship between SS and TFA. Conclusion : The results suggest that TFA is related to PI, PT. Internal rotation due to genu varum of femoral at hip influence that PI and PT increase.

피로균열성장에 의해 파단된 CT시험편의 표면조도와 모멘트의 관계에 관한 연구

김경석,정현철,김경수,박찬주,장호섭,Kim, Kyun-Suk,Jung, Hyun-Chul,Kim, Kyung-Su,Park, Chan-Joo,Jang, Hos-Seob 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.6

Fatigue crack growth caused by surface defects is one of the most important subjects for the evaluation and the assurance of safety in pressure vessels, piping systems, LPG/LNG fuel tank and other various structures. So, this paper aims to investigate the relationship between the surface roughness of fracture CT specimens and the moments on the specimen when doing fatigue test for the evaluation and the assurance of safety of structures from fatigue crack deconstruction. In this experiment, the CT specimens were loaded by a fatigue testing machine with changing loads until they are broken. The surface roughness of the fracture CT specimens was measured using 3D precise shape measuring equipment and digital holography. As a result of this study, It was identified that the average roughnesses are similar at the positions that has a same moments by comparing the results with the moments on the specimen according to the position.

도로축별 안전개선사업의 현황과 발전방안

김경석,Kim, Gyeong-Seok 한국도로학회 2005 한국도로학회지 Vol.7 No.4

압전 Ceramics 평판의 비대칭열부하와 대칭열부하에 의한 과도 압전열탄성 해석에 관한 연구

김경석,최정석,양승필,김용욱,Kim, Gyeong-Seok,Choe, Jeong-Seok,Yang, Seung-Pil,Kim, Yong-Uk 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.1

Piezoelastic materials have recently attracted considerable attention because of their potential use in intelligent structural systems. In this paper, we treat a transient piezothermoelastic problem in a hexagonal plate of crystal class 6mm subjected to antisymmetric heating temperature. We analyze this problem by use of the potential function method. Numerical calculations are carried out for a cadmium selenide solid, and the results are presented graphically in comparison with those derived from the similar problem in a cadmium selenide plate subjected to symmetric heating temperature for a symmetry transient problem.

시멘트 바이패스 더스트 내 염화칼륨 수득을 위한 이산화탄소 적용 연구

김경석,추용식,Kim, Kyoungseok,Chu, Yongsik 한국자원리싸이클링학회 2017 資源 리싸이클링 Vol.26 No.6

시멘트 제조 공정에서 발생하는 바이패스 더스트는 지정폐기물로서 고가의 처리비용이 요구되고 있다. 바이패스 더스트의 주성분은 KCl이며, KCl은 주로 비료에 사용되고 있다. 비료에 사용하기 위해서는 pH 수준이 중성 혹은 약산성 이어야 한다. 그러나 바이패스 더스트의 pH는 12.0~12.5 수준으로, 또다른 전처리 없이 비료로 사용될 수 없다. 본 연구에서는 시멘트 바이패스 더스트에서 KCl을 수득하는 과정 중, 이산화탄소를 사용하여 산화칼슘을 제거하고, 동시에 pH 변화량을 제어하고자 하였다. 탄산화시험기 내부 분위기를 $25^{\circ}C$-50RH%로 고정한 후, 이산화탄소 20 vol% 조건에서 0~7시간으로 유지하고, 각 시간별 산화칼슘 함량 및 pH 값을 분석하였다. 이산화탄소 유지시간 증가에 따라 산화칼슘 함량 및 pH 값은 감소하였으며, 6시간 경과 후 pH 값은 7에 근접하였다. As by-pass dust (BPD) made from cement manufactured process is designated waste, it is required to bury as high cost. The main component of BPD is potassium chloride (KCl), and used for the fertilizer. For using KCl to the fertilizer, the pH value of KCl is required as neutral or weak acid. However, it is not suitable to apply BPD into the fertilizer directly without any other treatment because BPD's pH value is shown 12.0~12.5; a high base. In this study, the carbon dioxide ($CO_2$) was used for removing calcium oxide (CaO) and reducing pH value during manufacturing process of KCl. We fixed inner condition of the carbon test chamber as $25^{\circ}C$-50RH%, and retained 0~7 hours under the 20 vol% of $CO_2$ atmosphere. After experiment, we analyzed the content of CaO and pH value from each samples. The more time exposed to $CO_2$, the content of CaO and pH value are shown. Furthermore, pH value exposed in 6 hours nearly reached 7.

폐유리와 산화 그래핀을 사용한 시멘트 모르타르의 물성 연구

김경석,추용식,Kim, Kyoungseok,Chu, Yongsik 한국자원리싸이클링학회 2019 資源 리싸이클링 Vol.28 No.6

This study investigated on the compressive strength and the length change test with using the waste glass and graphene oxide for recycling the waste glass as the aggregate. Curing on 3-day and 7-day, the compressive strength was enhanced as the usage of waste glass was increased. Especially, the huge difference in the compressive strength was observed when the amount of substituting on the waste glass was used on 10~50%. With 50% of waste glass condition, the compressive strength was portionally enhanced as the usage of graphene oxide was increased and its value was 42.6 N/㎟ with 0.2% of graphene oxide. In terms of the length change test, the use of high content of waste glass led length change value to increase, but it was dropped down as the portion of waste glass was above 50%. Furthermore, in the case of using 50% of waste glass, the use of high amount of graphene oxide tended to decrease the length change value. That is, graphene oxide may contribute on boosting the cement hydration reaction and blocking the ion's movement.

대책설계를 위한 토석류 특성값의 산정

김경석,Kim, Gyeong-Seok (사)한국토질및기초기술사회 2007 지반과 기술 Vol.4 No.3

고객의 든든한 기술동반자

김경석,Kim, Gyeong-Seok 한국제품안전협회 2006 제품안전 Vol.4 No.-

실물옵션 기법을 활용한 신재생에너지사업 경제성분석에 관한 연구

김경석,Kim, Kyeongseok 한국건설관리학회 2017 한국건설관리학회 논문집 Vol.18 No.2

기후변화의 영향으로 세계 각국은 화석연료 사용을 줄이고, 신재생에너지에 대한 투자가 활발하게 이뤄지고 있다. 세계 전력의 23.7%를 신재생에너지가 공급하고 있으며, 계속된 기술의 발전으로 화력설비와 발전원가 면에서 경쟁할 수준이 되어 투자 여건이 좋아 지고 있다. 하지만, 신재생에너지 프로젝트의 투자를 결정하는 것은 쉽지 않다. 본 연구는 신재생에너지 중에서 많은 비중을 차지하고 있는 수력, 태양광, 풍력발전 프로젝트 투자 결정에 실물옵션방법을 적용한 경제성평가에 대해 국내외 연구동향을 분석하였다. 본 연구는 (1)전통적 경제성분석방법과 실물옵션방법의 차이점, (2)적용 과정, (3)많은 연구들이 제시한 신재생에너지 프로젝트의 불확실성 요소들과 옵션종류에 대해 알아보았다. 실물옵션분석방법은 신재생에너지 프로젝트의 불확실성 요소들을 고려하고 수익을 향상시키거나 리스크를 피할 수 있는 옵션 적용이 가능하여 세밀한 투자계획수립에 적합하다. Due to climate change, countries around the world are actively investing in renewable energy, reducing fossil fuel use. 23.7% of world electricity is supplied by renewable energy. As the technology continues to develop, it is in a level to compete in terms of power generation cost, and investment conditions are improving. However, investment in renewable energy projects is not easy. This study analyzed trends of domestic and international researches on economics assessment applying real options analysis to investment decisions of hydro, solar, and wind power projects, which account for a large portion of renewable energy. This study provides (1) the difference between the traditional economic method and the real options analysis, (2) the application process, and (3) the uncertainty elements and option type of the renewable energy project presented by many studies. The real options analysis is suitable for the detailed investment strategy by considering the uncertainties of the renewable energy project and applying the option to improve the profit or to avoid the risk.