• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.1
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• pp.46-51
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• 1996

원자로는 압력용기 및 내부 구조물로 구분되어 있다. 내부 구조물들의 경련 열화 현상에 따라 결함이 많이 발생하여 이에 대한 초음파검사가 요구되고 있다. 따라서 원자로 내부 구조물에 대한 초음파검사 현황 및 각각 구조물들의 검사 원리를 기술하였다. 특히 원자로 내부 구조물 중 CRDM, core baffle bolt, core barrel bolt, CRGT-support pin 및 fuel alignment pin에 대한 유럽 및 독일을 중심으로 한 검사 현황 및 검사방법을 간략하게 기술하였다. 이 기술에 대한 지침안(guideline)이 독일, 프랑스, 일본을 중심으로 하여 마련되고 있다.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.392-395
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• 1995

This paper presents a time efficient method for determining a sequence of locations of a mobile manipulator that facilitates tracking of continuous path in cluttered environment. Given the task trajectory in the form of octree data structure, the algorithm performs characterization of task space and subsequent multistage optimization process to determine task feasible locations of the robot. Firstly, the collision free portion of the trajectory is determined and classified according to uniqueness domains of the inverse kinematics solutions. Then by implementing the extent of task feasible subspace into an optimization criteria, a multistage optimization problem is formulated to determines the task feasible locations of the mobile manipulator. The effectiveness of the proposed method is shown through a simulation study performed for a 3-d.o.f. manipulator with generic kinematic structure.

• Journal of Magnetics
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• v.4 no.4
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• pp.115-118
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• 1999

$MgFe_2O_4$ has been studied with X-ray diffraction, M ssbauer spectroscopy and vibration sample magnetometer (VSM). The crystal structure of the sample is found to have a cubic spinel structure with a lattice constant of $a_0=8.390$\pm$0.005$\AA$.$ The iron ions at both A (tetrahedral) and B (octahedral)sites are found to be in ferric high-spin states. Its Neel temperature TN is found to be 710$\pm$3 K. The Debye temperature for the A and B sites found to be 417$\pm$5 K and 331$\pm$5 K., respectively. Atomic migation from the A to the B sites starts near 425 K and increases rapidly with increasing temperature to such a degree that 31% of the ferric ions at the A sites have moved over to the B sites by 600 K.

• Electrical & Electronic Materials
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• v.10 no.7
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• pp.700-705
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• 1997

Transparent conducting indium tin oxide (TC-ITO) thin films are deposited on soda lime glass by a dc magnetron sputtering technique having the unbalanced-magnet structure in order to improve the electrical/material characteristics and to avoid the surface damages. The material properties are measured by the x-ray diffractometer (XRD) and atomic force microscope (AFM). The (400) peak as the preferred orientation of <100> direction for ITO thin films is stabilized with the increase of substrate temperature. The surface roughness estimated by AFM 3D image at the substrate temperature of 40$0^{\circ}C$ is extremely uniform. The best resistivity of ITO films (5500 $\AA$ thick) at 40$0^{\circ}C$ is about 1.3$\times$10$^{-4}$ $\Omega$cm on the position of 4 cm from substrate center.

• Nano
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• v.13 no.12
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• pp.1850138.1-1850138.6
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• 2018

Two-dimensional (2D) or layered materials have a great potential for applications in energy storage, catalysis, optoelectronics and gas separation. Fabricating novel 2D or quasi-2D layered materials composed of relatively abundant and inexpensive atomic species is an important issue for practical usage in industry. Here, we suggest the layer-structured AlOOH (Boehmite) as a promising candidate for such applications. Boehmite is a well-known layer-structured material and a single-layer can be exfoliated from the bulk boehmite by breaking the interlayer hydrogen bonding. We study atomic and electronic band structures of both bulk and single-layer boehmite, and also obtain the single-layer exfoliation energy using first-principles calculations.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.1
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• pp.29-35
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• 2019

The remedial junction is found in the network of single walled carbon nanotubes after the irradiation of protons not only for the better mechanical strength but also for the higher property of electrical conductivity. The irradiated proton formed a beam transferred sufficient energy to change the sp2 structure of atomic carbon as much as damage of crystalline formation, however it is shown the cross bonding while recovery of structure. This improved network in 2-D atomic chain of carbon is expected to use in a critical part in space energy harvesting system related with the solar radiation.

• Proceeding of EDISON Challenge
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• 2014.03a
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• pp.412-414
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• 2014

In this study, we investigate atomic and electronic structure of graphene with substitutional impurities such as boron or nitrogen atom using density functional theory (DFT) calculations. To investigate the effects of substitutional impurities in graphene, we consider a ($6{\times}6$) supercell of graphene in our calculations. For detailed electronic properties of graphene, we compare the energy band structure of B- or N-doped graphene with that of pristine graphene.

• Korean Journal of Crystallography
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• v.11 no.3
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• pp.173-175
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• 2000

Computational technique, based on the minimization of the crystal energy with respect to atomic coordinates, are shown to reproduce successfully complex crystal structure, in this case, strontium hexaaluminate magnetoplumbite, SrAl/sub 12/O/sub 19/. The experimental crystal structure and symmetry of the complex material is well reproduced with our potential models and some crystal physical properties are calculated.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1506-1511
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• 2018

Spectral behaviors of lasing from semiconductor square ring microcavities with structures for unidirectional laser oscillation were investigated. When a tapered structure was introduced, the lasing envelope shifted to a shorter wavelength region. Statistical estimate of the additional loss caused by the tapered structure was carried out by analyzing spectral data from many sets of cavities with various sizes. When a saw-edged structure was introduced, the unidirectional lasing functioned well but no apparent spectral shift was observed due to negligible additional loss.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.401-406
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• 1999

In relation to a non-destructive evaluation of irradiation damages of micro-structure interstitial, void and dislocation, the changes in the hysteresis loop, Barkhausen noise amplitude and the harmonics frequency due to a neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of RPV was irradiated to a neutron fluence of $2.3\times10^{19}\;n/cm^2\;(E\geq1\;MeV)\;at\;288^{\circ}C$. The saturation magnetization of neutron irradiated metal did not change. The neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by a neutron irradiation. The spectrum of Barkhausen noise is analysed with an applied frequency of 4 Hz and 8 Hz, sampling time of $50\;{\mu}sec\;and\;20\;{\mu}sec$. The harmonic frequency shows 4 Hz, 8 Hz, 12 Hz; and 16 Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared on the irradiated specimen.