• 한국산학기술학회논문지
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• 제10권7호
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• pp.1489-1496
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• 2009

비정질 인듐-갈륨-아연 산화물 박막트랜지스터를 모델링 하여서, 능동층의 구조, 두께, 평형상태의 전자밀도에 대응하는 박막트랜지스터의 특성을 연구하였다. 단일 능동층 박막트랜지스터의 경우, 능동층이 얇을 때 높은 전계효과이동도를 보였다. 문턱전압의 절대값은 능동층의 두께가 20 nm일 때 최저치를 보였으며, 문턱전압이하 기울기는 두께에 대한 의존성을 보이지 않았다. 복층구조 능동층의 경우, 하부의 능동층이 높은 평형상태 전자밀도를 가질 때보다 우수한 스위칭 특성을 보였다. 이 경우에도 능동층의 두께가 얇을 때에 높은 전계효과 이동도를 보였다. 높은 평형상태 전자밀도의 능동층의 두께를 증가시키면 문턱전압은 음의 방향으로 이동하였다. 문턱전압이하 기울기는 능동층의 구조에 대하여 특별한 의존성을 보이지 않았다. 이상과 같은 데이터는 산화물반도체 박막트랜지스터 능동층의 구조, 두께, 도핑비율을 최적화함에 효과적으로 사용될 것으로 기대된다.

• Journal of the Korean Wood Science and Technology
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• 제49권5호
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• pp.504-513
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• 2021

In this study, cross-laminated wood panels were manufactured with four softwoods and three hardwoods with the goal of efficiently predicting the static strength performance using dynamic modulus of elasticity (MOE) and simultaneously revealing the dynamic performance of cross-laminated wood panels. The effect of the density of the species on the dynamic MOE of the laminated wood panels was investigated. Moreover, the static bending strength performance was predicted nondestructively through the correlation regression between the dynamic MOE and static bending strength performance. For the dynamic MOE, the parallel- and cross-laminated wood panels composed of oriental oak showed the highest value, whereas the laminated wood panels composed of Japanese cedar showed the lowest value. In all types of parallel- and cross-laminated wood panels, the density dependence was confirmed, and the extent of the density dependence was found to be greater in the P_⊥ and C_⊥ types with perpendicular-direction laminae in the faces than in the P_∥ and C_∥ types with longitudinal-direction laminae in the faces. Our findings confirmed that a high correlation exists at a significance level of 1% between the dynamic modulus and static bending modulus or bending strength in all types of laminated wood panels, and that the static bending strength performance can be predicted through the dynamic MOE.

• 한국광학회지
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• 제6권4호
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• pp.302-309
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• 1995

상온에서 $1.55{\mu}m$ 를 발진하는 격자 정합된 InGaAs/InGaAsP 양자우물 레이저를 설계하여 주입 운반자 밀도와 온도의 함수로 이득 곡선을 계산하였다. 밴드 구조와 운동량 행력 요소의 계산에는 블록대각화된 8*8 이차 k.p 해밀토니안에 근거한 변환행렬법을 사용하였다. 이 격자정합된 양자우물은 TE 모우드로 발진하였다. 온도가 증가함에 따라 발진파장이 길어졌고, 투명 운반자 밀도는 증가하였으며 미분이득은 감소하였다. 이득 곡선의 온도의존도는 밴드 구조의 온도의존성과 페르미 함수의 온도의존성에 기인하는데 이중 후자의 효과가 주도적인 것이었다.

• Progress in Superconductivity
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• 제2권1호
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• pp.11-14
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• 2000

The notion of the finite pairing interaction energy range Td is shown to result in a linear temperature dependence of the London magnetic penetration depth length, ${\Delta}{\lambda}{/\lambda}(0)=(T/Td)2/\pi)ln2$ at low T in the case of the s-wave pairing state, accounting for data of high Tc superconductor by Hardy et al.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.355-356
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• 2016

It is shown that the maximum value of exchange current is obtained where hydrogen adsorption energy is near 0. This enables to estimate catalytic efficiency of a material with hydrogen adsorption energy, which is relatively easier to calculate with density fuctional theory (DFT) method. Strain dependence of the adsorption energy was studied with DFT method and adsorption energy of 0.04 eV per hydrogen atom is obtained at 30% strain.

• Bulletin of the Korean Chemical Society
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• 제8권2호
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• pp.105-110
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• 1987

A theory in which the Enskog hard sphere collisional dynamics complements the hydrodynamic theory is applied to the fast modulation dephasing dynamics in liquids which leads to homogeneous line broadening in the isotropic Raman spectra. The dephasing times of several molecules in pure liquids and in trace solutions in the solvent $CCl_4$ are calculated and these are compared with experimental values. The temperature dependence of the dephasing time of liquid acetonitrile and the isothermal density dependence of the dephasing time of liquid methyl iodide are also investigated.

• ETRI Journal
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• 제15권2호
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• pp.11-25
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• 1993

Interface trap densities at gate oxide/silicon substrate ($SiO_2/Si$) interfaces of metal oxide semiconductor field-effect transistors (MOSFETs) were determined from the substrate bias dependence of the subthreshold slope measurement. This method enables the characterization of interface traps residing in the energy level between the midgap and that corresponding to the strong inversion of small size MOSFET. In consequence of the high accuracy of this method, the energy dependence of the interface trap density can be accurately determined. The application of this technique to a MOSFET showed good agreement with the result obtained through the high-frequency/quasi-static capacitance-voltage (C-V) technique for a MOS capacitor. Furthermore, the effective substrate dopant concentration obtained through this technique also showed good agreement with the result obtained through the body effect measurement.

• Bulletin of the Korean Chemical Society
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• 제33권9호
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• pp.2855-2860
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• 2012

The coating N-acetyl cysteine (NAC) on gold surfaces may be used to design the distribution of either gold particle adsorbed to the $ZrO_2$ surface or vice versa by adjusting the electrostatic interactions. In this study, it was performed to find out electrostatic properties of the NAC-coated-gold surface and the $ZrO_2$ surface. The surface forces between the surfaces were measured as a function of the salt concentration and pH value using the AFM. By applying the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to the surface forces, the surface potential and charge density of the surfaces were quantitatively acquired for each salt concentration and each pH value. The dependence of the potential and charge density on the concentration was explained with the law of mass action, and the pH dependence was with the ionizable groups on the surface.

• Journal of Astronomy and Space Sciences
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• 제32권4호
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• pp.311-315
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• 2015

In this study, we estimated the topside scale height of plasma density (Hm) using the Swarm constellation and ionosondes in Korea. The Hm above Korean Peninsula is generally around 50 km. Statistical distributions of the topside scale height exhibited a complex dependence upon local time and season. The results were in general agreement with those of Tulasi Ram et al. (2009), who used the same method to calculate the topside scale height in a mid-latitude region. On the contrary, our results did not fully coincide with those obtained by Liu et al. (2007), who used electron density profiles from Arecibo Incoherent Scatter Radar (ISR) between 1966 and 2002. The disagreement may result from the limitations in our approximation method and data coverage used for estimations, as well as the inherent dependence of Hm on Geographic LONgitude (GLON).

• 천문학회지
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• 제49권6호
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• pp.239-253
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• 2016

We determined the warp parameters of 192 warped galaxies which are selected from 340 edge-on galaxies using color images as well as r-band isophotal maps. We derive the local background density (${\Sigma}_n$) to examine the dependence of the warp amplitudes on the galaxy environment. We find a clear trend that strongly warped galaxies are likely to be found in high density regions where tidal interactions are supposed to be frequent. However, the correlation between ${\alpha}_{\omega}$ and ${\Sigma}_n$ is too weak for weakly warped galaxies (${\alpha}_{\omega}$ < $4^{\circ}$) and the cumulative distributions of weakly warped galaxies are not significantly different from those of galaxies with no detectable warps. This suggests that tidal interactions do not play a decisive role in the formation of weak warps.