• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.109-109
• /
• 2011

1T-1C로 구성되는 기존의 DRAM(Dynamic Random Access Memory)은 데이터를 저장하기 위한 적절한 capacitance를 확보해야 한다. 따라서 캐패시터 면적으로 인한 집적도에 한계에 직면해있다. 따라서 이를 대체하기 위한 새로운 DRAM인 1T (Transistor) DRAM이 각광받고 있다. 기존의 DRAM과 달리 SOI (Silicon On Insulator)기술을 이용한 1T-DRAM은 데이터 저장을 위한 캐패시터가 필요없다. Impact Ionization 또는 GIDL을 이용해 발생한 정공을 채널영역에 가둠으로 서 발생하는 포텐셜 변화를 이용한다. 이로서 드레인 전류가 변화하며, 이를 이용해 '0'과 '1'을 구분한다. 기존의 1T-DRAM은 단결정 실리콘을 이용하여 개발되었으나 좀더 광범위한 디바이스로의 적용을 위해서는 다결정 실리콘 박막의 형태로 제작이 필수적이다. 단결정 실리콘을 이용할 경우 3차원 집적이나 기판재료선택에 제한적이지만 다결정 실리콘을 이용할 경우, 기판결정이 자유로우며 실리콘 박막이나 매몰 산화층의 형성 및 두께 조절이 용이하다. 때문에 3차원 적층에 유리하여 다결정 실리콘 박막 형태의 1T-DRAM 제작이 요구되고 있다. 따라서 이번연구에서는 엑시머 레이저 어닐링 및 고상결정화 방법을 이용하여 결정화 시킨 다결정 실리콘을 이용하여 1T-DRAM을 제작하였으며 메모리 특성을 확인하였다. 기판은 상부실리콘 100 nm, buried oxide 200 nm로 구성된 SOI구조의 기판을 사용하였다. 엑시머 레이저 어닐링의 경우 400 mJ/cm2의 에너지를 가지는 KrF 248 nm 엑시머 레이저 이용하여 결정화시켰으며, 고상결정화 방법은 $400^{\circ}C$ 질소 분위기에서 24시간 열처리하여 결정화 시켰다. 두가지 결정화 방법을 사용하여 제작되어진 박막트랜지스터 1T-DRAM 모두 kink 현상을 확인할 수 있었으며 메모리 특성 역시 확인할 수 있었다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.385-385
• /
• 2011

Si 또는 반도체 화합물을 기반으로 한 태양전지의 높은 원재료 가격과 복잡한 공정 등의 문제점들을 해결하기 위한 방안으로 반도체성 고분자인 Poly(3-hexylthiophene)(P3HT)과 C60 유도체인 PCBM을 광활성 층으로 이용하여 유기 태양전지(Organic Solar Cell, OSC)를 제작하였다. 하지만 상대적으로 낮은 효율을 갖는 OSC의 단점을 해결하기 위해서 유기물 자체가 갖고 있는 광 안정성, 낮은 전하 이동도 및 광 에너지 흡수대 등의 문제점들의 해결 방안들이 제시되고 있다. 본 연구에서는 광활성 층을 사용한 유기 태양전지의 특성에서 후열처리에 따른 유기 태양전지의 전기적 및 구조적, 광학적인 특성들이 소자의 효율에 끼치는 영향에 대해 분석하였다. 후열 처리 온도에 따른 광활성 층의 구조적인 특성을 분석하기 위해 EFM 이미지와 XRD패턴을 측정하였는데 열처리 후 박막의 전기적인 포텐셜과 결정성 향상의 유기 태양전지의 효율향상에 기여함을 알 수 있었다. 또한 임피던스 분석 장치를 이용해 후열 처리에 따른 소자의 Resistance, Capacitance, I-V 곡선들을 분석한 결과 최적의 조건에서 열처리된 광활성 층은 전하들의 이동을 조절하여 소자 내에서 Capacitance를 증가시키는 것 뿐만 아니라 전극과 유기물 층 사이의 계면 특성을 향상시킴으로써, 소자의 효율을 증가시키는 원인으로 작용함을 확인 하였다.

• Transactions of the Korean Society of Pressure Vessels and Piping
• /
• v.13 no.2
• /
• pp.51-59
• /
• 2017

Steam jets ejected from a rupture zone of high energy pipes may cause damage to adjacent structures. This event could lead to more serious accidents in nuclear power plants. Therefore, to prevent serious accidents, high energy pipes of nuclear power plants are designed according to the ANSI / ANS 58.2 technical standard. However, the US Nuclear Regulatory Commission (USNRC) has recently pointed out non-conservatism in existing high energy pipe fracture evaluation methods, and required the assessment of the unsteady load of the jet caused by a potential feedback mechanism as well as the impact range of steam jet, the jet impact loads and the blast wave effects at the initial breakage stage. The potential feedback mechanism refers to a phenomenon in which a vortex formed by impingement jets amplifies vortex itself and induces jet vibration in a shear layer. In this study, CFD methodology using the LES turbulence model is established and numerical analysis is carried out to evaluate the dynamic behavior of impingement jets and the potential feedback mechanism during jet impingement. Obtained results have been compared with an empirical correlation and experiment.

• Journal of Internet Computing and Services
• /
• v.18 no.6
• /
• pp.1-6
• /
• 2017

For the algorithm of cross-information potential with delta functions (CIPD) which has superior performance in impulsive noise environments, a new method of employing the information of power variations of magnitude controlled input (MCI) in the weight update equation of the CIPD is proposed in this paper where the input of CIPD is modified by the Gaussian kernel of error. To prove its effectiveness compared to the conventionalCIPD algorithm, the distance between the current weight vector and its previous one is analyzed and compared under impulsive noise. In the simulation results the proposed method shows a two-fold improvement in steady state stability, faster convergence speed by 1.8 times, and 2 dB - lower minimum MSE in the impulsive noise situation.

• Journal of the Korean Chemical Society
• /
• v.28 no.3
• /
• pp.170-175
• /
• 1984

The transport rates of $H^+$ ion by DBC and DCC as carrier molecules through organic liquid membranes were determined at 25$^{\circ}$C. The transport rates depend highly on the dielectric constants of membrane solvents and these results were discussed in terms of Born's potential energy barrier methods. The sizes of anions also affect the transport rates and these results were well explained theoreticlly by extended Born's equation.

• Journal of the Korean Chemical Society
• /
• v.57 no.5
• /
• pp.554-559
• /
• 2013

In this study, we have investigated potential energy of ${\beta}$-D-glucopyranose in vacuum and implicit water condition. By Comparing two conditions we find that how solvation energy influence ${\beta}$-D-glucopyranose structure. We use AMBER package program and GLYCAM_06 force field. Solvation model was used for the generalized Born model with Hawkins, Cramer, Truhlar has been proposed. We conclude that difference of contour map of two conditions is caused by solvation effect by reducing hydrogen bonding interaction.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.5
• /
• pp.955-960
• /
• 2007

In this paper, the deviation of tunneling current for gate voltage has been investigated in double gate MOSFET developed to decrease the short channel effects. In device scaled to nano units, the tunneling current is very important current factor and rapidly increases,compared with thermionic emission current according to device size scaled down. We consider the change of tunneling current according to gate voltage in this study. The potential distribution is derived to observe the change of tunneling current according to gate voltage, and the deviation of off-current is derived from the relation of potential distribution and tunneling probability. The derived current is compared with the termionic emission current, and the relation of effective gate voltage to decrease tunneling current is obtained.

• Journal of the Society of Naval Architects of Korea
• /
• v.56 no.4
• /
• pp.352-360
• /
• 2019

International Maritime Organization (IMO) regulates an emission of greenhouse gases by creating an Energy Efficiency Design Index (EEDI) to reduce environmental pollution. In propulsion system field, studies are under way on Energy Saving Device (ESD), which can improve propulsion efficiency with the propeller, to reduce the EEDI. Among the studies, the study of Pre-Swirl Stator (PSS) has been actively conducted from long time ago. Recently the variable pith angle type pre-swirl stator has been studied to improve the propulsion efficiency in non-uniform flow fields of the Stern. However, for traditional design methods, no specific design method has been established on the blade or location of radius. In this study, proper design method is proposed for each blade or location for radius according to hydrodynamic pitch angle.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.3
• /
• pp.309-316
• /
• 2015

A state-based peridynamic model is able to describe a general constitutive model from the standard continuum theory. The response of a material at a point is dependent on the deformation of all bonds connected to the point within the nonlocal horizon region. Therefore, the state-based peridynamic model permits both the volume and shear changes of the material which is promising to reproduce the complicated dynamic brittle fracture phenomena, such as crack branching, secondary cracks, cascade cracks, crack coalescence, etc. In this paper, the two-dimensional state-based peridynamic model for a linear elastic plane stress solid is employed. The damage model incorporates the energy release rate and the peridynamic energy potential. For brittle glass materials, the impact of the crack-parallel compressive stress waves on the crack branching pattern is investigated. The peridynamic solution for this problem captures the main features, observed experimentally, of dynamic crack propagation and branching. Cascade cracks under strong tensile loading and secondary cracks are also well reproduced with the state-based peridynamic simulations.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.13 no.2
• /
• pp.83-90
• /
• 2010

The hydrodynamic interaction of two floating bodies in waves freely floating or connected by a rigid link is studied by using a boundary element method in the frequency-domain. The exact two-body hydrodynamic coefficients of added mass, wave damping and exciting force are calculated from the radiation-diffraction potential solution of the improved Green integral equation associated with the free surface Green function. The irregular frequencies in the conventional Green integral equation make it difficult to predict the physical resonance of the fluid in the gap between two bodies floating side by side. However, the improved Green integral equation employed in this study is free of irregular frequencies and always yields the exact solution of the multi-body radiation-diffraction potential boundary value problem. The 6 degree-of-freedom motions of two bodies freely floating side by side or connected parallel by a rigid link have been calculated for the incident wave frequencies ranging from 0.1 to 5 radians per second in head, left and right bow quartering seas. The 6-component load of the rigid link have also been presented.