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쌍정 경계가 고온 초전도체 Y₁Ba₂Cu₃O단결정의 자기적특성에 미치는 영향
이보화,박정수,김채옥,김의훈,정규채 漢陽大學校 自然科學硏究所 1997 自然科學論文集 Vol.16 No.-
일반적으로 쌍정 경계(twin boundary)는 고온초전도체Y₁Ba₂Cu₃O??? 단결정 내에서 핀 고정점(pinning center)로 작용하여 단결정 시료의 자화에 영향을 미칠 것으로 알려져 왔다. 그러나 이에 대한 체계적인 실험적 연구가 수행되지 않고 있다. 본 실험에서는 Y₁Ba₂Cu₃O??? 단결정 시료를 성장시킨 후, 재 후열처리 과정 중에 단축 가압 방법(uniaxial stress method)을 이용하여 단결정 시료를 detwinning 하였다. 편광효과가 관측된 micro-Raman spectra와 X-ray 회절 패턴으로부터 관측된 (001)면의 주 피크의 2Θ 값을 통해서 단결정이 잘 성장되었음을 확인하였다. 그리고, 반자성 차폐 효과, 마이스너 효과 및 자기이력 측정 결과로부터 detwinning시간이 길어져서 쌍정 경계의 비율이 감소할수록 자화폭이 감소함을 관측하였다. 이로부터 자속 고정(flux pinning)이 줄어듦을 알 수 있었다. 그러므로 쌍정 경계가 고온초전도체 Y₁Ba₂Cu₃O??? 단결정의 핀 고정점으로 작용한다는 것을 알 수 있었다. Generally it is suggested that twin boundaries play the major role of the pinning center in high-Tc superconductor Y₁Ba₂Cu₃???? single crystal and influences the magnetization. However, any systematic experiment related with this expectation has not been performed yet. In this experiment, after growing Y₁Ba₂Cu₃??? single crystals, we detwinned them in oxygen atmosphere using uniaxial stress method while annealing them again. It was verified that single crystals had been grown well from micro-Raman spectra that showed the polarization effect and 2Θ values of (001) plain peaks in X-ray diffraction pattern. We observed that values of magnetization of samples decreased from antimagnetic shield effects, Meissner effect and magnetic hysteresis as detwinning time was increased and this result means that flux pinning decreases. As a result we confirmed that twin boundaries act as a pinning center in high-Tc superconductor Y₁Ba₂Cu₃??? single crystal.
Magnetic and electric properties of stoichiometric BiMnO <sub>3</sub> thin films
Lee, Bo Wha,Yoo, Pil Sun,Nam, Vu Binh,Toreh, Kirstie Raquel Natalia,Jung, Chang Uk Springer US 2015 NANOSCALE RESEARCH LETTERS Vol.10 No.1
<P>It has been suggested that BiMnO<SUB>3</SUB> is a material exhibiting both ferromagnetism and ferroelectricity. Stoichiometry is rather easily achieved in a polycrystalline sample, and ferromagnetic properties have been well documented for bulk samples. Stoichiometry in thin films has been difficult to obtain, and many physical properties have exhibit wide distributions mainly due to the stoichiometry problem. Thin film studies on BiMnO<SUB>3</SUB> have not shown clear evidence of ferroelectricity, while other physical properties measured for the BiMnO<SUB>3</SUB> films showed wide spectra, which has been attributed to cation and/or oxygen vacancies. We fabricated BiMnO<SUB>3</SUB> thin films with good stoichiometry and with ferromagnetic properties comparable to those reported for stoichiometric BiMnO<SUB>3</SUB>: <I>Tc</I> ~ 105 K and <I>M</I><SUB>sat</SUB> ~ 3.6 μ<SUB>B</SUB>/Mn. The charge-electric field (Q-E) curve measured at 5 K was fairly linear and free from hysteresis and showed no ferroelectric order. This finding is consistent with the centrosymmetric crystal structure recently suggested by theoretical calculations and structural studies on ceramic samples of stoichiometric BiMnO<SUB>3</SUB>.</P>
Fabrication of MgO Thin Layers for PDP Devices by Sol-Gel Process
Lee, Bo Wha,Chae, Hee K 한국외국어대학교 외국학종합연구센터 부설 기초과학연구소 1999 기초과학연구 Vol.7 No.-
Sol-gel derived magnesium oxide thin layers have been used for protective layers of plasma display panel(PDP) devices. The precursor has been prepared from the reaction between 2-methoxyethanol and magnesium graules, and characterized by spectroscopy. The MgO films reproducibly present outstanding electric properties and surface morphology.
이일화(Lee Il-Wha),황선근(Hwang Seon-Keun),박태순(Park Tae-Soon),이보형(Lee Bo-Hyoung),고학송(Ko Hak-Song) 한국철도학회 2004 한국철도학회 학술발표대회논문집 Vol.- No.-
Recently, the development of paved track is required as a Low-maintenance of conventional line. The most important factor of paved track is stability and applicability. In this method, the ballast is grouted with mortar so that the ballast can tum into a structure like slab. This method can be subdivided into the followings. One is the method with switching the ballast, and the other is without switching the ballast. The ordinary and actual states of the ballast and roadbed were investigated to evaluate the applicability of the paved track structure in this study, and various In-situ tests were applied. Non-destructive tests such as GPR, SASW, FWD were used, and bearing capacity of roadbed, depth of the ballast, and deterioration, penetration, and contamination of the ballast were focused. The result of this investigation was utilized in the selection of optimal paved track structure and data for preliminary design.
우미경(Mee-Kyung Woo),이은화(Eun-Wha Lee),이보경(Bo-Kyung Lee),이정수(Jung-Soo Lee),이정화(Jung-Wha Lee),이종현(Jong-Hyun Lee),모수미(Su-Mi Mo) 한국식품영양과학회 1985 한국식품영양과학회지 Vol.14 No.3
A survey of 113 children, aged 4 to 6 years, of the San Cheon a day care center, located in the upland, over populated, poor area of Seoul City, was conducted from July 28 to September 6, 1982, to investigate the dietary and nutritional status, and prevalence of parasitic inpection. House size was 10.1 Pyung; number of households per house, 3.1; number of family member per household, 4.8; and number of family members living together per room, 3.7; on the average. Only 49% of households possess own houses and the others live in the rented houses. About 40% of mothers were engaged income-producing activities within or outside of the home. Mean values of height, weight, arm circumference, girth of chest, and girth of head ranged from 98.4 to 102.2% of KIST mean. However, 13% of the subjects were assessed as undernutrition for 'weight for height'. Mean value of hemoglobin was 12.9±2.9 g/dl and mean hematocrit value was 35.2±5.5%; 17.9% of the subjects were proven to be anemic according to the criteria of the WHO. The positive prevalence of parasitic inpection was 3.3%, significantly lower than that observed in any other area, probably because of community parasitic control project. Intakes of energy and nutrients except thiamin and ascorbic acid were far below RDAs. Carbohydrates for energy provided 71. 2 to 73.8% of total energy intake; protein accounted 11.3 to 12.2%; fat provided 14.5 to 16.6%. Energy intake was divided among breakfast, lunch, evening meal and snack, on the average, in a percentage of 22.0; 23.4; 24.4; 30.2. There was significant correlation between pattern of food consumption and nutrient intakes. The nutrient intakes and quality of foods were highly correlated to the maternal factors, especially mother's educational level. The study suggested that development of nutrition guides for mother and children would be needed to improve nutritional status of those young children.
Lee, Min Jae,Kim, Dong Eun,Zakrzewska, Adriana,Yoo, Young Dong,Kim, Su-Hyeon,Kim, Sung Tae,Seo, Jai Wha,Lee, Young Sook,Dorn, Gerald W,Oh, Uhtaek,Kim, Bo Yeon,Kwon, Yong Tae American Society for Biochemistry and Molecular Bi 2012 The Journal of biological chemistry Vol.287 No.28
<P>The N-end rule pathway is a proteolytic system in which destabilizing N-terminal amino acids of short lived proteins are recognized by recognition components (N-recognins) as an essential element of degrons, called N-degrons. In eukaryotes, the major way to generate N-degrons is through arginylation by ATE1 arginyl-tRNA-protein transferases, which transfer Arg from aminoacyl-tRNA to N-terminal Asp and Glu (and Cys as well in mammals). We have shown previously that ATE1-deficient mice die during embryogenesis with defects in cardiac and vascular development. Here, we characterized the arginylation-dependent N-end rule pathway in cardiomyocytes. Our results suggest that the cardiac and vascular defects in ATE1-deficient embryos are independent from each other and cell-autonomous. ATE1-deficient myocardium and cardiomyocytes therein, but not non-cardiomyocytes, showed reduced DNA synthesis and mitotic activity ~24 h before the onset of cardiac and vascular defects at embryonic day 12.5 associated with the impairment in the phospholipase C/PKC-MEK1-ERK axis of Gα(q)-mediated cardiac signaling pathways. Cardiac overexpression of Gα(q) rescued ATE1-deficient embryos from thin myocardium and ventricular septal defect but not from vascular defects, genetically dissecting vascular defects from cardiac defects. The misregulation in cardiovascular signaling can be attributed in part to the failure in hypoxia-sensitive degradation of RGS4, a GTPase-activating protein for Gα(q). This study is the first to characterize the N-end rule pathway in cardiomyocytes and reveals the role of its arginylation branch in Gα(q)-mediated signaling of cardiomyocytes in part through N-degron-based, oxygen-sensitive proteolysis of G-protein regulators.</P>
이보화,고영섭 한국외국어대학교 외국학종합연구센터 부설 기초과학연구소 1999 기초과학연구 Vol.7 No.-
기체-마이크론폰 광음향 cell을 2개의 chamber와 연결관으로 구성된 Helmholtz resonator 형태로 설계, 제작하였다. 변조 주파수에 따른 탄소 검정(carbon black)분말 시료의 광음향 신호의 진폭과 위상 변화를 측정하였다. 측정된 주파수 특성은 다중 공진 현상이 일어나는 extended Helmholtz resonator모델에 근접함을 알 수 있었다. 공진 주파수는 입사 광원의 종류와 세기에 무관하였으나, 매질 기체가 공기 대신 헬륨 가스인 경우나 마이크로폰 부피가 줄어든 경우 주파수는 높아지는 방향으로 이동함을 알 수 있었다. A gas-microphone photoacoutic cell was designed constructed in the form of a Helmholtz resonator consisting of two chambers connected by a long narrow tube. Amplitude and phase angle of the photoacoutic signal from carbon black powder were measured as a function of chopping frequency. The occurence of multiple resonances can be interpreted quantitatively by the extended Helmholtz resonator model. The acoustic resonances, which are independent of light sources, are moved to higher frequencies when the cell is filled with helium gas insted of air or when the volume of microphone chamber is decreased.