Easy Preparation of Readily Self-Assembled High-Performance Graphene Oxide Fibers

Kim, Yern Seung,Kang, Jong Hun,Kim, Taehoon,Jung, Yeonsu,Lee, Kunsil,Oh, Jun Young,Park, Jisoo,Park, Chong Rae American Chemical Society 2014 Chemistry of materials Vol.26 No.19

<P>Graphene oxide (GO) was recently reported to assemble into one-dimensional fiber precursors that can be used to produce next-generation multifunctional graphene-based materials. This study describes the facile fabrication of GO fibers with excellent mechanical properties, utilizing a diamine cross-linker that forms ion bridges between the GO layers. Organic co-coagulants and postdrawing processes, which are usually employed in typical GO spinning processes, were not used here. The GO layers readily aligned along the spinning axis, and the GO formed closely packed structures in the fibers. The fibers displayed a Young’s modulus of 26.6 GPa and a maximal tensile strength of 384.3 MPa. The interlayer microstructure of the GO sheets could be tuned by modifying the structures of the cross-linking diamine groups, yielding a range of mechanical properties. These observations suggested that our newly developed GO fiber synthesis method could allow applications of graphene-based fibrous materials through GO surface chemistry modification approaches.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2014/cmatex.2014.26.issue-19/cm502614w/production/images/medium/cm-2014-02614w_0008.gif'></P>

탄소나노튜브 캐소드의 전계방출 및 열화특성에 미치는 페이스트의 조성과 분위기 가스의 영향

김동희,김태식,정원섭,김광호,손영국,조영래 대한금속ᆞ재료학회 2006 대한금속·재료학회지 Vol.44 No.3

서울의 Penicillinase Producing Neisseria gonorrhoeae 발생빈도(1998)

김재홍,김준호,반재용,이정우,황성주,정준규,정성태,강진문,조흔정,홍창의,정혜신,이한승,김이선,이봉길,이종호,선영우,한기덕,윤성필,이성훈,안종성,박석범,문승현,조항래,김형섭,류지호,황재영,박준홍,손상욱 한양대학교 의과대학 2001 한양의대 학술지 Vol.21 No.1

In recent years, gonorrhea has been pandemic and remains one of the most common STDs in the world, especially in developing countries. For the detection of a more effective therapeutic regimen and assessing the prevalence of Penicillinase Producing Neisseria gonorrhoeae(PPNG), we have been trying to study the patients who have visited the Venereal Disease Clinic of Choong-Ku Public Health Center in Seoul since 1980 by menas of the chromogenic cephalosporin method. In 1998, 93 strians of N. genorrhoeae were isolated, among which 60(64.5%) were PPNG. The prevalence of PPNG in Seoul, which had been decreased to 39% in 1996 after a peak of 74.3% in 1993, is increased to 64.5% in 1998.

Crucial Role of Oxidation Debris of Carbon Nanotubes in Subsequent End-Use Applications of Carbon Nanotubes

Kim, Yern Seung,Oh, Jun Young,Kim, Jae Ho,Shin, Min Ho,Jeong, Yo Chan,Sung, Sae Jin,Park, Jisoo,Yang, Seung Jae,Park, Chong Rae American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.20

<P>A facile purification method for oxidized carbon nanotubes (CNTs) is developed to preserve acidic carbon compounds (ACCs) for achieving high-quality dispersion of CNTs. The remaining ACCs, which originated from the surface destruction of CNTs during the oxidation process, are considered to play a crucial role in the dispersion of CNTs in water and various polar protic solvents. To elucidate the concrete role of ACCs, a direct titration method is applied to quantitatively investigate the degree of ionization of both CNTs and ACCs in their aqueous dispersion. While ACCs with strong carboxylic groups (pK(a) of around 2.9) are easily removed by the neutral or base washing of oxidized CNTs, which is common in the purification process, ACC-selective purification using acid washing preserves the ACCs attached to CNTs, thereby effectively stabilizing CNT dispersions in aqueous solutions. Additionally, the Hansen solubility parameters of ACC-preserved and ACC-removed CNTs were determined by the inverse gas chromatography method to estimate their miscibility in various solvents. The preserved ACCs significantly influenced the dispersibility of CNTs in polar protic solvents, which may widen the possible application of CNTs. Specifically, the ACC-preserved high-quality CNT dispersion produces high-performance CNT buckypaper with densely packed nanostructures. The Young's modulus and tensile strength of these buckypapers reach up to 12.0 and 91.0 MPa, respectively, which exceed those of ACC-removed CNTs in previous reports.</P>

극단 저체중 신생아에서의 동맥관 개존증 결찰술을 위한 진정맥 마취 경험 2례

최영균,고명진,이상은,조광래,김영환,임세훈,이정한,이근무,정순호,김영재,신치만 仁濟大學校 白病院 2010 仁濟醫學 Vol.31 No.-

Running title: Cases of anesthesia for extremely low birth weight infant. Extremely low birth weight infants (birth weight < 1000 g) are prone to various morbidities such as respiratory distress syndrome, intraventricular hemorrhage, periventricular leukomalacia, patent ductus arteriosus, necrotizing enterocolitis and retinopathy. To accomplish successful anesthetic management, many precautions must be continuously taken during the operation. First, inspired oxygen concentration should be adjusted to avoid oxygen toxicity. Second, body temperature must be maintained adequately. Third, hemodynamic parameters should be kept stable. We report 2 cases of successful anesthetic management for extremely low birth weight infant who underwent ligation of patent ductus arteriosus at the neonatal intensive care unit.

조세회피와 발생액에 의한 이익조정이 회사채 신용등급에 미치는 영향

조영래(Cho, Young-Rae),김용(Kim, Yong) 한국산업비즈니스학회 2021 한국비즈니스연구 (비즈니스연구) Vol.5 No.1

본 연구에서는 2011년부터 2015년까지 유가증권시장에 상장된 기업들을 대상으로 신용등급이 상승하거나 또는 하락할 경우에 조세회피 및 발생액에 의한 이익조정이 회사채 신용등급에 어떠한 영향을 미치는 지를 분석하였다. 추가로 조세회피 및 이익조정의 지속성이 신용등급에 어떤 영향을 미치는지에 대해서도 분석하였다. 분석결과는 신용등급이 상승하는 경우에 조세회피가 1% 수준에서 유의적인 음(-)의 관계를 나타내었으며, 조세회피와 신용등급 상승의 상호작용변수는 유의적인 양(+)의 관계를 나타내었다. 이는 조세회피가 직전년도와 비교하여 신용등급이 상승하였을 때는 조세회피를 하려는 경향이 감소하기 때문이며, 또한 신용평가기관에서 신용등급이 상승할 때 조세회피는 감소할 것이라고 예측하여 보고된 이익을 그대로 반영하였기 때문이라고 판단된다. 그러나 신용등급이 하락하는 경우에는 이와 정반대의 결과를 도출하였다. 그러나 발생액에 의한 이익조정은 신용등급과 유의적인 관계를 나타내지 못하였다. 추가로 지속성이 회사채 신용등급에 영향을 미치는지를 검증하였는데, OLS회귀분석과 순서형 로짓회귀분석 모두 일부 이익조정(수정 Jones모형)의 경우 5% 수준에서 유의적인 음(-)의 관계를 나타내었다. 따라서 이익조정의 지속성은 신용등급에 부정적인 영향을 미친다고 볼 수 있다. 다만, 이들 관계는 측정치에 따라 차이가 나타나고 있다. 이러한 분석결과는 신용평가기관이 조세회피를 제대로 포착하지 못함으로써 신용위험을 왜곡시키고 나아가 신용등급에 대한 신뢰성을 떨어뜨릴 수 있다는 점을 시사하는 것으로 판단된다. This study empirically analyzed how tax avoidance affects bond credit ratings of listed companies on the korea exchange from 2011 to 2015. The results of this study are summarized as follows. First, the relationship between tax avoidance, earnings management and bond credit ratings was not statistically significant in all models. But In the case of a rise in bond credit rating, the relationship between the five years of accumulated cash effective tax rate(cashETR) were showed a significant negative(-) relationship at a 1% level. Also, if the bond credit rating declines, the results is the opposite of the case where the bond credit rating rises. Second, in determining whether continuous tax avoidance affects bond credit rating ratings, either the OLS analysis, or ordered logistics regression analysis, showed a significant negative(-) relationships only in the Jones Model at a 5% level. Third, The interaction effect of the decline in credit rating and persistence showed a significant negative(-) relationship at 1% level in all three models. Thus, the persistence of the tax avoidance can be seen to affect bond credit rating when combined with other factors that can interact. The results of this study suggest that many companies still avoid tax, but credit rating agencies are not able to capture them properly, thus distorting credit risk and decreasing credibility of credit rating.

Rocuronium의 애별투여방법이 모지내전근의 이완에 미치는 영향

최영균,김승수,이원진,조광래,이상은,김영환,임세훈,이정한,이근무,정순호,김영재,신치만 인제대학교 2009 仁濟醫學 Vol.30 No.-

Objective : There are controversies in pnmmg technique of rocuronium whether it can or can't shorten the onset time. We want to compare the effects of two different priming doses and intervals of rocuronium. Materials and Methods : After giving propofol, 50 patients were randomly assigned to 5 groups. Group I received a placebo, followed 3 min later by rocuronium 0.6 mg/kg. Priming doses and intervals of Group II, Ill, N, V were 0.06 rng/kg and 2 min, 0.12 mg/kg and 2 min, 0.06 rug/kg and 3 min, 0.12 mg/kg and 3 min, respectively. Total dose of rocuronium was 0.6mg/kg. Train of four (TOF) count or ratio and 1st twitch height of TOF (T1) were monitored with 15 secondsintervals. TOF ratio of each groups just before bolus injection, duration for TOF count to reach zero and duration for Tl to reach 95% depression after bolus injection were compared. Results : Duration for TOF count to reach zero and duration for Tl to reach 95% depression after bolus injection were decreased in priming groups compared to Group 1 (P < 0.01) In group V, significant depression of TOF ratio just before bolus injection was seen (P < 0.05). Conclusion : Priming technique with rocuronium is effective method to shorten the onset of neuromuscular block. But priming dose of rocuronium itself could cause hypoxia and aspiration in awake patients and should be used carefully. Priming dose of rocuronium 0.06 mg/kg and 2 minutes interval maybe relatively safe method.

성인의 장중첩증에서 복부전산화단층촬영술의 유용성

김세웅,조영업,고영배,김원곤,김경국,김경래,우제홍,김미영 대한대장항문학회 1998 Annals of Coloproctolgy Vol.14 No.3

일 대학병원에 입원한 노년기 양극성 장애 환자의 인구학적 및 임상적 특징

조숙현(Sook Hyun Cho),정한용(Han Yong Jung),권영준(Young Jun Kwon),이소영(So Young Lee),김양래(Yang Rae Kim),김윤정(Yun Jung Kim) 대한노인정신의학회 2006 노인정신의학 Vol.10 No.2

Objectives : As the elderly population is continuing to increase, psychiatric diseases of the elderly are becoming an important social issue. This study looks into the demographical and clinical features of the elderly patients diagnosed with bipolar disorder in a University hospital. Methods : The study subjects include patients admissioned in the closed wards of Soonchunhyang Seoul hospital and Cheonan hospital from March, 2000 to February, 2005 who met the DSM-IV-TR criteria for bipolar disorder at the time of discharge. A total of 146 patients (76 men, 70 women) medical records were studied retrospectively. Subjects older than the age of 50 at time of admission were grouped as the old age group, whereas those who were younger than 50 as the young age group. Also among the old age group, those who had the first onset of episode under the age of 50 were grouped as the early onset group, whereas those who had the first onset after the age 50 were grouped as the late onset group. Results : The number of bipolar disorder patients in the young age group and old age group were 73 and 73 respectively. The number of early onset group and late onset group were 46 and 23 respectively. The old age group had a relatively higher incidence of bipolar II disorder than the young age group. Also in the old age group there was a higher incidence of hypomanic or depressive episode rather than manic episode compared to the young age group. And in the old age group psychotic symptoms were less common and the mean admission length shorter than the young age group. Additionally in the old age group treatment with Lithium monotherapy or with no mood stabilizers at all were relatively common. Among the old age group, late onset group had a higher rate of bipolar II disorder than the early onset group. Conclusion : This study shows differences in the demographical and clinical features among different age groups. But additional research would be required to determine whether the bipolar disorders in the elderly or late onset group are actually a different type of disorder from those of the young.

유한공간차분 시간영역 알고리즘을 이용한 터널 내의 전자파 해석에 관한 연구

金紀來,李永哲 慶南大學校 附設 工業技術硏究所 1997 硏究論文集 Vol.14 No.2

FVTD법은 임의의 미소 다면체 셀(cell)에 대하여 맥스웰 방정식(Maxwell's equation)을 체적적분한 것에 이산화하여 나타낸 차분 방정식으로, FVTD(finite volume time domain) 알고리즘을 이용하여 굴곡형, 십자형 및 원형곡률을 갖는 터널내의 전파 특성에 대해 해석하였다. 이 방식의 장점은 불균질 매질을 포함하는 임의 형태의 경계치 문제를 쉽게 계산할 수 있는데 있다. 본 논문에서는 FVTD법을 이용하여 실제 터널 구조와 유사한 여러 형태의 터널에 대해 전자파의 전파 현상을 수치 계산을 하고, 유효성을 검증하기 위해 실험치와 비교하였다. FVTD method is based on the volume integrations of the Maxwell's equation with respected to arbitrary shaped small polyhedron cells. This paper is concerned with a finite volume time domain(FVTD) method for the analysis of transmission efficiency of electromagnetic wave propagation in bend type, cross type and circular type tunnels. The advantages of the present method are that the algorithm is very simple since the coordinate system is restricted only to the cartesian, and so the arbitrary shaped boundaries including nonhomogeneous materials can easily be dealt with since the fields at every center point of the cells are assigned in an average fashion.