• Journal of the Korean Institute of Telematics and Electronics
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• v.25 no.4
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• pp.402-406
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• 1988

The MgGa2Se4 single crystal for study of optical properties is for the first time grown by Bridgmna method. The crystal structure of grown MgGa2Se4 single crystal has the Rhomobohedral structure (R3m) and its lattice constant are a=3.950\ulcorner c=38.893\ulcornerin Hexagonal structure. The energy band structure of grown MgGa2Se4 single crystal structure has direct band gap and the optical energy gap measured from optical absorption in this crystal is 2.20eV at 290K. The temperature dependence of energy gap was given Eg(T)=Eg(O)-aT\ulcorner)B+T), from varshni equation, where Eg(O)=2.34eV, a=8.79x10**-4eV/and b=250K.

• Fire Science and Engineering
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• v.10 no.1
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• pp.3-9
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• 1996

Electrostatic charge is generated in large scale or high speed processes dealing with materials with large resistance, or under complicated condition. Fire and explosion often occur due to electrostatic charge accumulated in flammable gases, vapor, liquids and powder. It is usually very difficult to verify the cause of accidents as well as the prevention. In this study, it is shown that the needle electrode needs the electrode gap from 1.8mm to 3.8mm, sphere electrode and plate electrodes need the electrode gap of 1.9mmfor the minimum ignition energy. The sphere electrode and the plate electrode requires 12.8mJ and 3.2mJ of minimum ignition energy respectively with the electrode gap of 1.1mm. The ignition voltage rises to very large value as the ground resistance increases.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.87-90
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• 2009

A dual-cell-gap transflective liquid crystal display (TR-LCD) with identical response time in the transmissive and reflective regions is demonstrated. In the transmissive region, strong anchoring energy condition is used to decrease the response time, while in the reflective region weak anchoring energy condition is used to increase the response time. The simulated dual-cell-gap TR-LCD has good performances.

• Journal of the Korean Vacuum Society
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• v.4 no.3
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• pp.334-341
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• 1995

IB-AI-VIB2 및 IB-AI-VIB2 :Co2+ 결정을 고순도 원소를 출발 물질로 하고 iodine을 수송 매체로 사용하여 chemical transport reaction method로 성장시켰다. 성장된 결정의 결정구조는 chalcopyrite 구조였으며, energy gap은 direct band gap으로 3.514~1.814 eV 정도로 주어졌으며, cobalt를 불순물로 첨가할 때 energy gap은 감소하였다. IB-AI-VIB2 :Co2+ 결정에서 첨가된 cobalt가 모체결정의 Td symmetry site에 Co2+ ion으로 위치하여, Co2+ ion의 energy 준위 사이의 전자전이에 기인하는 불순물 광흡수 peaks가 나타났다. 이 불순물 광흡수 peaks에 결정장 이론을 적용하여 구산 1st-order spin-orbit coupling parameter(λ)는 -183~ -189cm-1정도였고, 2nd-order spin-orbit coupling parameter(P)는 225~239 cm-1정도였으며, crystal field parameter(Dq)는 328~395cm-1, Racah parameter(B)는 531~552cm-1정도였다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.799-812
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• 2017

Backfill grouting and realistic convergence distribution were not properly considered in previous studies on 2D numerical analysis of a shield TBM tunnel. In this study, a modeling method was suggested to cope with this problem by considering a realistic convergence distribution and proper properties of backfill grouting. To this end, the influence of gap parameter and depth of rock cover on volume loss and composed of ground volume loss around tunnel excavation and surface volume loss were analyzed with a single layer of weathered soil. As a result, most of surface settlements were occurred immediately after excavation. Additional, as depth of rock cover and gap parameter increased, the influence range of surface settlement curves obtained from 2D numerical analyses became broader than a suggested theoretical equation. Therefore, it is inferred that gap parameter should be applied based on load distribution ratio and the property of backfill grouting properly considered for the estimation of the precise behavior of a shield TBM tunnel in 2D numerical analysis.

• Steel and Composite Structures
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• v.26 no.2
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• pp.139-150
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• 2018

In this paper, two kinds of buckling restrained braces (BRBs) are designed to improve the mechanical properties and fatigue life, the reserved gap and viscoelastic filler with high energy dissipation capacity are employed as the sliding element, respectively. The fatigue life of BRBs considering the effect of sliding element is predicted based on Manson-Coffin model. The property tests under different displacement amplitudes are carried out to evaluate the mechanical properties and fatigue life of BRBs. At last, the finite element analysis is performed to study the effects of the gap and viscoelastic filler on mechanical properties BRBs. Experimental and simulation results indicate that BRB employed with viscoelastic filler has a higher fatigue life and more stable mechanical property compared to BRB employed with gap, and the smaller reserved gap can more effectively improve the energy dissipation capacity of BRB.

• Journal of environmental and Sanitary engineering
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• v.15 no.2
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• pp.102-111
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• 2000

As IR-sensor for detecting pollution material, the iron silicide has a fit band gap, high physicochemical stability at high temperature and good acid resistance. The growing film was formed with the Fe-Si bond and the organic compound because plasma resolved the injected precursors into various active species. In the Raman scattering spectrum, the Fe-Si vibration mode showed at 250 {TEX}$cm^{-1}${/TEX}. The FT-IR peak indicated that the various organic compounds were deposited on the films. The iron silicide was epitaxially grown to β-phase by the high energy of plasma. The lattice structure of films had [220]/[202] and [115]. The thickness of the films increased with the flow rate of silane. But rf-power increased with decreasing the thickness. The optical gap energy and the band gap were shown about 3.8 eV and 1.182∼1.194 eV. The band gap linearly increased and the formula was below: {TEX}$E_g^{dir}${/TEX}= 8.611×{TEX}$10^{-3}N_{D}${/TEX}＋1.1775

• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.56-59
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• 2000

$CdGaInS_4$ and $CdGaInS_4:Er^{3+}$ single crystals crystallized in the rhombohedral(hexagonal) structure. with lattice constants $a=3.913{\AA},\;c=37.245{\AA}$ for $CdGaInS_4$, and $a=3.899{\AA}$ and $c=36.970{\AA}$ for $CdGaInS_4:Er^{3+}$. The optical absorption measured near the fundamental band edge showed that the optical energy band structure of these compounds had a direct and indirect band gap. the direct and indirect energy gaps are found to be 2.771 and 2.503 eV for $CdGaInS_4$, and 2.665 and 2.479 eV for $CdGaInS_4:Er^{3+}$ at 10 K. The temperature dependence of the optical energy gap was well represented by the Varshni equation. In $CdGaInS_4$, the values of ${\alpha},\;{\beta}$ of the direct and the indirect energy gap were found to be $7.57{\times}10^{-4}eV/K$. $6.53{\times}10^{-4}eV/K$ and 240K. 197K. and the values of ${\alpha}$ and ${\beta}$ of the direct and the indirect energy gap in the $CdGaInS_4:Er^{3+}$ were given by $8.28{\times}10^{-4}eV/K,\;2.08{\times}10^{-4}eV/K$ and 425 K, 283 K, respectively.

• Journal of the Korean Magnetics Society
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• v.17 no.4
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• pp.152-155
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• 2007

We have studied electronic structures and magnetic properties of $YMnO_3,\;ScManO_3$ with hexagonal structure using Full Potential Linearized Augmented Plane Wave (FLAPW) method based on LSDA method. LSDA calculation results show that multiferroic $YMnO_3$ shows energy gap due to hexagonal symmetry and magnetic interaction. Because of insulating gap and small Y ion, $YMnO_3$ shows magnetic and ferroelectric state. However, $ScMnO_3$ does not show the energy gap because of strong hybridization of Mn-O for LSDA calculation. We confirmed the stability of multiferroic state for $YMnO_3\;and\;ScManO_3$ using total energy calculations. The antiferromagnetic and ferroelectric states have the lowest energy about 100 meV.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.2
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• pp.232-238
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• 2013

In this paper we describe the maximum energy transfer of CSA(Capacitive Switching Antenna). CSA which is radiated antenna system contain energy storage and switch, antenna needs to high voltage source for electrical field radiation experiment. In this experiment we employed Marx generator as a charging source. CSA can radiate electrical field more efficiently by varying antenna capacitance. The electromagnetic generation system which was using CSA has some advantages which are more simple and more effective compared to exist system. We evaluated the performance of electromagnetic wave generating system using CSA. As a result UWB gain of system is 0.47, It is higher level than exist system is 0.3. Radiated electrical field strength at 1m is 70kV/m. It is measured by D-dot sensor and gap distance is 20mm. Center frequency of CSA is approximately 25MHz. When vary the antenna gap distance from 50mm to 20mm, we can find the radiation field strength is decrease and antenna center frequency is increased. We also simulated the energy transfer efficiency to compare with experiment result. Consequentially, CSA needs to appropriate capacitance which is similar value from marx generator for maximum energy transfer, and gap is less than 1mm to increase the CSA capacitance.