정광호 교수

Strong spin-orbit interaction and time-reversal symmetry in topological insulators generate novel quantum states called topological surface states. Their study provides unique opportunities to explore exotic phenomena such as spin Hall effects and topological phase transitions, relevant to the development of quantum devices for spintronics and quantum computation. Although ultrahigh-vacuum surface probes can identify individual topological surface states, standard electrical and optical experime

In a three-dimensional topological insulator Bi2Se3, a stress control for band gap manipulation was predicted but no systematic investigation has been performed yet due to the requirement of large external stress. We report herein on the strain-dependent results for Bi2Se3 films of various thicknesses that are grown via a self-organized ordering process. Using small angle X-ray scattering and Raman spectroscopy, the changes of d-spacings in the crystal structure and phonon vibration shifts resul

OBJECTIVE: To identify genetic and environmental factors contributing to hypodontia and microdontia by using Korean twin family data. MATERIALS AND METHODS: A total of 1267 individuals (525 men and 742 women; 180 monozygotic twins [MZ] and 43 dizygotic twins [DZ] from 282 families) underwent an oral examination as part of the Healthy Twin Study in Korea. Dental anomalies classified as hypodontia or microdontia were diagnosed using radiographs and clinical examinations. In order to estimate genet

Tocochromanols are potent lipid-soluble antioxidants and essential nutrients for human health. Genetic engineering techniques were used to develop soybeans with enhanced vitamin E levels, including tocotrienols, which are not found in soybean. The gene encoding rice homogentisate geranylgeranyl transferase (HGGT) was overexpressed in soybeans using seed-specific and constitutive promoters. The association between abundance of vitamin E isomers and antioxidant activity was investigated during see

Multilayer films composed of alternating layers of Bi and Se—[Bi(4.55 Å)/Se(6.82 Å)] n (Bi4Se6), [Bi(6.13 Å)/Se(12.26) Å] n (Bi6Se12), and [Bi(4.86 Å)/Se(18.46 Å)] n (Bi4Se18)—were fabricated by controlling the layer thickness at the atomic scale using thermal evaporation techniques. After annealing treatment, the Bi4Se18 alternately layered film shows a single phase of Bi 2 Se 3 rhombohedral crystalline structure with the characteristic density of single crystal Bi 2 Se 3, whereas the Bi6Se12 a

Topological insulators, a new quantum state of matter, have created exciting opportunities for studies in topological quantum physics and for exploring spintronics applications due to their gapless helical metallic surface states. In this study, thin films composed of alternate layers of Bi and Se (Te) ({Bi(3 Å)Te(9 Å)}n/{Bi(3 Å)Se(9 Å)}n) were fabricated by controlling the layer thickness within the atomic scale using thermal evaporation techniques. The high-purity growth of uniform Bi2Se2Te1 t

Graphene/MnO2 nano-composite was electrochemically synthesized for application to an electrode material for electrochemical supercapacitors. The nanosized needle-like MnO2 was obtained by use of a graphene substrate. The prepared composite exhibited an ideal supercapacitive behavior. A capacitance retention of 94% was achieved with a 4 h deposition time (an initial capacitance of 574 mF/cm2 at a scan rate of 20 mV/s) and the retention declined with further deposition time. The results demonstrat

Multilayer films composed of individual layers of [Sb(8.84 Å)/Se(12.6 Å)](Sb4Se6), [Sb(8.84 Å)/Se(7.2 Å)](Sb4Se4), and [Sb(15.4 Å)/Se(7.2 Å)](Sb6Se4) were synthesized using effusion cells controlled at the subatomic scale. After an annealing process, the Sb4Se6 multilayered film with an Sb 2 Se 3 orthorhombic structure had a high resistance and a clean valence band edge similar to that for a band shape of a semiconductor, whereas the Sb6Se4 film with an Sb rhombohedral structure and an Sb 2 Se 3

Thin films of Al-substituted cobalt ferrite layers on thermally oxidized silicon wafers were fabricated via the sol-gel method with various annealing temperatures. Structural and magnetic properties of the films were investigated with thermogravimetric and differential thermal analysis (TG-DTA), an x-ray diffractometer, vibrating sample magnetometer (VSM), and atomic force microscopy (AFM). TG-DTA measurements showed exothermic reaction peak at 285/spl deg/C. CoAl/sub 0.2/Fe/sub 1.8/O/sub 4/ thi

In this work, we prepared multilayered films with repeated Sb and Te layers by a thermal evaporation method. The film structure was controlled by the layer thickness ratio of Sb to Te, resulting in the formation of self-ordered superlattice structured Sb2Te2/Te films and self-ordered Sb2Te3 films. The thermoelectrical properties and the thermoelectric figure of merit (ZT) closely correlated with the structural characteristics, i.e., the superlattice structure with semiconductor–semimetal layers

Joon Seol Lee1*, Mi Nam Chung1, Young Sup Ahn2, Hag Sin Kim3, Yeon Sang Song1, Hyeong Kwon Shim3, Seon Kyeong Han1, Jae Myeong Kim1, Sae Jung Suh4, Jeong Ju Kim3, Kwang Ho Jeong5, and Jae-Sung Choi3. Korean J. Breed. Sci. 2013;45:440-4. https://doi.org/10.9787/KJBS.2013.45.4.440