전기 · 자기 재료 : 고온 초전도체의 특성

이성익 ( Sung Ik Lee ),( Jin Woo Chung ) 대한금속재료학회 ( 구 대한금속학회 ) 1988 재료.물성 심포지엄 Vol.- No.-

담배 니코틴에 의한 사람 태아 성상세포에서 종양괴사인자(TNF-α)의 발현 억제작용

손일홍,이성익,양현덕,한선정,석승한,이재규,김재현,박주영,문형인,이성수,Son, Il-Hong,Lee, Sung-Ik,Yang, Hyun-Duk,Han, Sun-Jung,Suk, Seung-Han,Lee, Jai-Kyoo,Kim, Jae-Hyun,Park, Joo-Young,Moon, Hyung-In,Lee, Sung-Soo 대한화학회 2007 대한화학회지 Vol.51 No.3

니코틴은 사람 대식세포에서 interleukin 2 (IL-2)와 종양괴사인자 (tumor necrosis factor-alpha; TNF-α) 가 생성되는 것을 억제하는데, 이러한 억제작용은 cytokine 유전자 발현 중 전사단계에서 전사인자의 활성을 억제함으로써 일어난다. 이러한 니코틴의 면역반응 억제작용은 아프타성궤양 및 궤양성대장염, 알레르기성폐 포염, 건초열 등에서도 보고되고 있다. 만일 중추신경계에서도 위와 같은 니코틴의 면역억제 작용이 일어난 다면 다발성경화증과 같은 면역반응 매개질환의 치료에 새로운 전기가 마련될 수 있을 것이다. 본 연구에서 는 중추신경계의 여러 면역반응 매개질환의 병태생리에 대한 이해를 넓히고자, 이미 알려진 니코틴의 cytokine 생성억제가 사람 중추신경계의 성상세포에서도 일어남을 확인하고 그 억제기전을 밝히고자 하였다. 이를 위 하여 사람 태아 성상세포에 다양한 농도의 니코틴과 IL-1β를 처리한 다음 TNF-α mRNA의 발현 정도와 NF- κB의 활성을 비교, 분석하여 다음과 같은 결과를 얻었다. 1. 사람 태아 성상세포를 0.1-20 μg/ml의 니코틴으로 처리해 본 결과 10 μg/ml 이상의 농도에서 세포독성능이 나타나기 시작하였다. 2. 사람 태아 성상세포에 IL- 1β를 처리하면 2시간만에 TNF-α mRNA가 최대로 발현되었으며 그 이후로는 점진적으로 감소하였다. 3. 사 람 태아 성상세포를 1 및 0.1 μg/ml의 니코틴으로 전처리한 후 IL-1β로 자극한 군에서는 IL-1β 단독 처리군에 비해 TNF-α mRNA의 발현이 감소하는 양상을 보였다. 1 μg/ml의 니코틴을 처리한 경우에는 8시간 이후부터 TNF-α mRNA의 발현이 현저하게 감소하여 12시간에 최대로 감소하였다. 또한 0.1 μg/ml의 니코틴을 처리한 군에서는 24시간에 가장 현저하게 감소하였다. 4. 성상세포에 IL-1β로 처리한 군에서는 강력한 NF-κB의 활성 을 확인할 수 있었으며, 니코틴을 전처리하고 IL-1β 자극한 군에서는 NF-B의 활성이 감소하였다. 결론적으로 일정농도 이상의 니코틴은 세포독성효과를 나타내나 적정한 농도와 시간 경과후 니코틴은 사람 태아 성상세포에서 IL-1β에 의해 유도되는 TNF-α의 발현 감소를 유도하며, 이는 NF-κB의 활성을 감소시킴으로써 나타난다고 생각된다. The Tumor necrosis factor-α, (TNF-α), is involved in the pathogenesis of multiple sclerosis and contributes to the degeneration of oligodendrocytes as well as neurons. Nicotine has been found to have immunosuppressive and inflammation-suppressing effects. Astrocytes, the major glial cells in the CNS, are capable of producing TNF-α at both the mRNA and protein levels in response to interleukin-1 (IL-1) or TNF-α. Nicotine has been shown to influence glial cell functions. To order to explore the role of astrocytes in the production of TNF-α, astrocytes were pretreated with nicotine and are stimulated with IL-1β to determine their effects on TNF-α production. The results are as follows. Cytotoxic effects of nicotine on human fetal astrocytes were noted above 10 μg/ml of nicotine. The effect of IL-1β on TNF-α mRNA expression in primary cultured human fetal astrocytes was maximal at 2 h after IL- 1β(100 pg/ml) treatment. Human fetal astrocytes were pretreated with 0.1, 1, and 10 μg/ml of nicotine and then stimulated with IL-1β (100 pg/ml) for 2 h. The inhibitory effect of nicotine on expressions of TNF-α mRNA in human fetal astrocytes with pretreated 0.1 μg/ml of nicotine is first noted at 8 hr, and the inhibitory effect is maximal at 12 h. The inhibitory effect at 1 μg/ml of nicotine is inhibited maximal at 24 h. Nicotine at 0.1, 1 and 10 μg/ml concentrations significantly inhibits IL-1β-induced NF-κB activation. Collectively, this study indicates that nicotine might inhibit the expression of TNF-α in activated human fetal astrocytes.

Al 첨가가 $MgB_2$ 단결정의 비등방성에 미치는 영향에 대한 연구

강병원,이현숙,박민석,이성익,Kang, Byeong-Won,Lee, Hyun-Sook,Park, Min-Seok,Lee, Sung-Ik 한국초전도학회 2008 Progress in superconductivity Vol.9 No.2

We have studied superconducting properties of $Mg_{1-x}Al_xB_2$ single crystals from reversible magnetization measurements. It was found that the upper critical fields $H_{c2}$ were decreased for both H // c and H // ab as Al is substituted for Mg. As a result, the large anisotropy of $H_{c2}$ observed in pure $MgB_2$, which is considered as one of the characteristics of two-gap superconductor, was decreased with Al doping. On the other hand, the irreversibility fields $H_{irr}$ were increased for x = 0.1 and were significantly decreased for x = 0.2. In contrary to the anisotropy of $H_{c2}$, the anisotropy of $H_{irr}$ was increased as Al concentration increases.

Two-band effect in superconducting parameters and their anisotropies of $MgB_2$ single crystals

강병원,김헌정,이현숙,이성익,Kang, Byeong-Won,Kim, Heon-Jung,Lee, Hyun-Sook,Lee, Sung-Ik The Korean Superconductivity Society 2007 Progress in superconductivity Vol.8 No.2

We have studied superconducting parameters of $MgB_2$ single crystals from reversible magnetization measurements with the magnetic field both parallel and perpendicular to the c-axis of the crystals. The temperature dependence of the London penetration depth, ${\lambda}_{ab}{^{-2}}(T)$, obtained from the Hao-Clem analysis on reversible magnetization, shows a clear discrepancy from single-band theories. It is also found that the anisotropies of the London penetration depth, ${\gamma}_{\lambda}$, slowly increases with temperature while the anisotropy of the upper critical field, ${\gamma}_H$, decreases with temperature. These behaviors are in sharp contrast with the behavior of superconductors with a single band. The temperature dependence of ${\lambda}_{ab}{^{-2}}$, and the opposite temperature dependences of ${\gamma}_{\lambda}\;and\;{\gamma}_H$ can be well explained with the theory of the two-band superconductivity.

불면증 환자에 대한 침치료 전후 정량화 뇌파 분석: Z Scored Absolute Power and sLORETA

이고은 ( Go Eun Lee ),문수정 ( Su Jeong Mun ),이성익 ( Sung Ik Lee ),임정화 ( Jung Hwa Lim ),위영만 ( Young Man We ),문광수 ( Kwang Su Moon ),유영수 ( Yeoung Su Lyu ),강형원 ( Hyung Won Kang ) 대한한방신경정신과학회 2016 동의신경정신과학회지 Vol.27 No.3

Objectives: To investigate the neurophysiological effect of acupuncture treatment on insomnia patients using quantitative electroencephalography (QEEG) and standardized Low Resolution Brain Electromagnetic Tomography method (sLORETA). Background: Insomnia is one of the commonly encountered symptoms in primary medical care. Recent studies of acupuncture for insomnia reported that the acupuncture groups showed significant improvements compared with the control groups. However, the neurophysiological mechanism of acupuncture in the treatment of insomnia has not been revealed and a few studies have measured the effect of acupuncture treatment using QEEG. Methods: Participants who had some problems in initiating or maintaining sleep, or had non-restorative sleep for more than 3 days a week and ISI scores above 8 and below 21 were treated by acupuncture for 2 weeks (3 times a week, total 6 times). We assessed the effectiveness of acupuncture for insomnia by the PSQI (Pittsburgh Sleep Quality Index) at baseline and at 2 weeks after the end of treatment (4th week). Also, we performed EEG and analysed the EEG data at baseline and at the end of treatment (2nd week) on the linked ears montage using the Neuroguide software program and sLORETA. Results: Thirty-two participants were enrolled and 2 participants dropped out because of personal reasons. Among the 30 participants, EEGs of 12 participants were included in the analysis of QEEG and sLORETA. Total score on the ISI and PSQI was significantly decreased after acupuncture treatment. The number of electrodes exceeding the range of 90% (±1.65) or 95% (±1.96) in the z scored absolute power of beta was significantly decreased after acupuncture treatment. There was no significant change in brain activation between pre- and post-acupuncture using sLORETA. Conclusions: The deviation of absolute power compared to the normative database was significantly decreased after acupuncture treatment in the alpha and beta ranges. Therefore, we suggest that acupuncture treatment for insomnia might be effective through the central nervous system especially in the brain. There are many limitations to drawing any conclusion. Further studies are needed in the future to overcome these limitations.

전동차 냉·난방 시험에 의한 실내온도분포에 대한 연구

윤교열(Kyo Teoul Yoon),이성익(Sung Ik Lee),이재호(Jae Ho Lee),문인철(In Chul Moon),서수호(Soo Ho Seo) 한국철도학회 2012 한국철도학회 학술발표대회논문집 Vol.2012 No.5

경제의 발달과 더불어 인간의 삶에 대한 질이 크게 향상 되면서 건축물에 이어 철도차량에 이르기까지 냉난방 시스템이 기본적으로 적용되고 있다. 이는 철도차량의 쾌적성을 향상시켜 이용객의 편의성을 충족시키기 위한 것이다. 그러나 철도차량 내부에서는 위치에 따라 온도의 편차가 부분적으로 발생되고 있으며, 이러한 문제는 앞으로도 계속 연구해야 할 과제로 남아있다. 서울시 7호선 연장구간 전동차에는 유지보수성 및 점검의 편리함을 고려하여 기존 차량과 동일한 Roof 탑재형 Air-con 및 의자 하부 취부형 전기 Heater를 적용하였다. 냉난방 시험을 통해 실내온도분포 실태를 파악하고, 냉난방기의 설치 수량 및 설치 위치를 결정하는 것뿐만 아니라, Door 작동으로 인한 온도 손실을 분석하는 것은 효율적인 냉난방 시스템 구축을 위해 매우 중시 되어야 한다. 본 연구에서는 시험조건에 따른 온도분포 결과의 차이 및 실내 온도분포에 미치는 영향에 대해 고찰하였다. With economic development and improvement of quality for human life, most structures and vehicles are being equipped with air conditioner and heater, and also rolling stock are being applied to air conditioner and heater as basic specification. This is to meet customer convenience by improving comfort of vehicle. But temperature anomaly is occurred in the vehicle, and this problem remains to research project. The air conditioning and heating system applied in Seoul #7, EMU is equipped with roof mounted air conditioning system and under seat mounted electric heater which are equivalent to existing vehicle in consideration of maintainability and serviceability of inspection. We figured out interior temperature distribution by conditioning and heating test, and analyzed the difference of temperature distribution according to quantity and position of heating system, door open. We tried to consider difference of temperature distribution result and effect on interior temperature distribution according to test condition this study.

Effect of $Y_2O_3$ Nanoparticles on Critical Current Density of $YBa_2Cu_3O_{7-x}$ Thin Films

위창환,강병원,오상준,이성익,Tran, H.D.,Reddy, D.Sreekantha,Wie, C.H.,Kang, B.,Oh, Sang-Jun,Lee, Sung-Ik 한국초전도학회 2009 Progress in superconductivity Vol.11 No.1

Introduction of proper impurity into $YBa_2Cu_3O_{7-x}$ (YBCO) thin films is an effective way to enhance its flux-pinning properties. We investigate effect of $Y_2O_3$ nanoparticles on the critical current density $J_c$ of the YBCO thin films. The $Y_2O_3$ nanoparticles were created perpendicular to the film surface (parallel with the c-axis) either between YBCO and substrate or on top of YBCO, YBCO/$Y_2O_3$/LAO or $Y_2O_3$/YBCO/STO, by pulsed laser deposition. The deposition temperature of the YBCO films were varied ($780^{\circ}C$ and $800^{\circ}C$) to modify surface morphology of the YBCO films. Surface morphology characterization revealed that the lower deposition temperature of $780^{\circ}C$ created nano-sized holes on the YBCO film surface which may behave as intrinsic pinning centers, while the higher deposition temperature produced much denser and smoother surface. $J_c$ values of the YBCO films with $Y_2O_3$ particles were either remained nearly the same or decreased for the samples in which YBCO is grown at $780^{\circ}C$. On the other hand, $J_c$ values were enhanced for the samples in which YBCO is grown at higher temperature of $800^{\circ}C$. The difference in the effect of $Y_2O_3$ can be explained by the fact that the higher deposition temperature of $800^{\circ}C$ reduces intrinsic pinning centers and $J_c$ is enhanced by introduction of artificial pinning centers in the form of $Y_2O_3$ nanoparticles.

Temperature and magnetic field dependent optical properties of superconducting $MgB_2$ thin film

정종훈,이해자,김경완,김명훈,노태원,강원남,정창욱,이성익,Jung, J. H.,Lee, H. J.,Kim, K. W.,Kim, M. W.,Noh, T. W.,Wang, Y. J.,Kang, W. N.,Jung, C. U.,Lee, Sung-Ik 한국초전도학회 2001 Progress in superconductivity Vol.3 No.1

We investigated the temperature and magnetic field dependent optical properties of a$ MgB_2$ thin film in the far-infrared region. In the superconducting state, i.e. 5 K, we obtained the values of superconducting gap $2\Delta$ ~ 5.2 meV and $2\Delta$ $_{k}$ $B/T_{c}$ ~1.8. Although the value of$ 2\Delta$</TEX$B/T_{c}$ was nearly half of the BCS value, the $2\Delta$ seemed to follow the temperature dependence of the BCS formula. Under the magnetic field (H), the superconducting state became suppressed. Interestingly, we found that the normal state area fraction abruptly increased at low field but slowly increased at high field. It did not follow the H-dependences predicted for a s-wave superconductor (i.e. a linear dependence) nor for a s-wave one (i.e. $H^{1}$2/ dependence). We discussed the complex gap nature of $MgB_2$ in comparison with two gap and anisotropic s-wave scenarios.ios.

Mixed-state Hall effect of $MgB_2$ thin films

김보연,정순길,문경희,강원남,최은미,김헌정,이성익,김형진,Kim, Bo-Yeon,Jung, Soon-Gil,Moon, Kyeong-Hee,Kang, W.N.,Choi, Eun-Mi,Kim, Heon-Jung,Lee, Sung-Ik,Kim, Hyeong-Jin The Korean Superconductivity Society 2006 Progress in superconductivity Vol.7 No.2

We have measured the Hall resistivity (${\rho}_{xy}$) and the longitudinal resistivity (${\rho}_{xy}$) on superconducting $MgB_2$ thin films in extended fields up to 18 T. We found a universal scaling behavior between the Hall resistivity and the longitudinal resistivity, which is independent of the temperature and the magnetic field. At a wide magnetic field region from 1 to 18T, a universal power law of ${\beta}=2.0{\pm}0.1$ in a scaling relation, ${\rho}_{xy}={A{\rho}_{xx}}^{\beta}$, was observed in c-axis-oriented $MgB_2$ thin films. These results can be well interpreted by using recent models.

$MgB_2$ 초전도 박막의 홀 전도도의 온도 의존성

정순길,성원경,허지영,이태경,강원남,최은미,김형진,이성익,Jung, Soon-Gil,Seong, W.K.,Huh, Ji-Young,Lee, T.G.,Kang, W.N.,Choi, Eun-Mi,Kim, Hyeong-Jin,Lee, Sung-Ik 한국초전도학회 2007 Progress in superconductivity Vol.8 No.2

We have measured the Hall conductivity (${\sigma}_{xy}$) of c-axis-oriented $MgB_2$ thin films as functions of temperatures and magnetic fields. We found that the Hall conductivity (${\sigma}_{xy}$) is expressed by the sum of two terms, ${\sigma}_{xy}=C_l/H+C_3H$, where the coefficient $C_1\;and\;C_3$ are independent of the magnetic fields and have positive values. The coefficient $C_1$ is strongly dependent on the temperature, while the $C_3$ is weakly dependent on the temperature. We have obtained that the $C_1$ is proportional to $(1- T/T_c)^n$ with n = 4.2, which is consistent with the data observed in $La_{2-x}Sr_xCuO_4$ superconductors with low anisotropy ratio.