• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.1
• /
• pp.7-11
• /
• 2006

Through SCM modeling, we found that the depletion layer in silicon was of a form of a spherical capacitor with the SCM tip biased. Two-dimensional (2D) finite differential method code with a successive over relaxation (SOR) solver has been developed to model the measurements by SCM of a semiconductor wafer that contains an ion-implanted impurity region. Then, we theoretically analyzed the spherical capacitor and determined the total depleted-volume charge Q, capacitance C, and the rate of capacitance change with bias dC/dV. It is very important to observe the depleted carriers' movement in the silicon layer by applying the bias to the tip. So, we calculated the depleted-volume charge, considering different factors such as tip size, oxide thickness, and applied bias (dc+ac), which have an influence on potential and depletion charges.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1990.06a
• /
• pp.58-72
• /
• 1990

유체 윤활 이론에 의한 저어널 베어링의 해석은 그 적용 버위가 넓기 때문에 다양하게 연구되어왔다. 근래에는 열적 효과의 중요성 때문에, 윤활유의 점도와 온도와의 관계, 윤활유 주입홈에서의 윤활유 혼합현상, Cavitation현상, 고속에서 윤활유의 난류현상, 윤활유 주입구의 위치 그리고 경사진 베어링 축이 유막에 미치는 영향 등 다양한 연구가 활발히 진행되고 있다. 본 연구에서는 반원주형 윤활홈을 갖는 저어널 베어링의 주입 윤활유의 열효과가 베어링 부하량과 마찰에 미치는 영향 등을 고찰하였고, 본 연구를 수행하기 위해, 베어링 Bush와 Shfft벽에서 여러가지 열전달 겅계 조건을 가정한 가운데 Reynolds 방정식을 Energy 방정식과 동시에 수치해석적으로 풀었다. 수치해석 방법은 FDM(Finite Difference Method) 중 SOR(Successive Over-Relaxation)Technigue을 이용하였다. 또한 윤활유 점도와 온도의 관계는 지수함수(Exponential Function) 형태로 취했다. 주입 윤활유 온도와 압력 그리고 윤활홈의 형태 등을 변화시켜가며 베어링 성능에 미치는 영향을 조사하였다.

• Electrical & Electronic Materials
• /
• v.10 no.10
• /
• pp.1000-1004
• /
• 1997

In this paper the current-voltage characteristics of a submicron GaAs MESFET is simulated by using the self-consistent ensemble Monte Carlo method. The numerical algorithm employed in solving the two-dimensional Poisson equation is the successive over-relaxation(SOR) method. The total number of employed superparticles is about 1000 and the field adjusting time is 10fs. To obtain the steady-state results the simulation is performed for 10ps at each bias condition. The simulation results show the average electron velocity is modified by the gate voltage.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.6
• /
• pp.17-26
• /
• 1984

A computer program (DIFSIM: Diffusion SIMulator) was written to calculate the impurity profile, specifically boron and phosphorus, due to three different diffusion processes-predeposition, drive-in in inert ambient, and drive-in in oxidizing ambient. The vacancy mechanism including Fair and Tsai's theory for phosphDrus diffusion was widely incorporated for modeling various diffusion processes. The concentrationtependent oxidation rate was also explained using the vacancy model, while the oxidation - enhanced diffusion was mo dolled using catkins replacement mochanlsm . The simulation results using DIFSIM showed a fairly good agreement with the experimental data by adjusting some of the empirical parameters in the program. The results obtained using DIFSIM were compared with the results from SUPREM II.

• Journal of KIISE:Computer Systems and Theory
• /
• v.37 no.3
• /
• pp.172-183
• /
• 2010

Virtual memory systems (VM) reduce disk I/Os caused by page faults using page prefetching, which reads pages together with a desired page at a page fault in a single disk I/O. Operating systems including 4.4BSD attempt to prefetch as many pages as possible at a page fault regardless of page access patterns of applications. However, such an approach increases a disk access time taken to service a page fault when a high portion of the prefetched pages is not referenced. More seriously, the approach can cause the memory pollution, a problem that prefetched pages not to be accessed evict another pages that will be referenced soon. To solve these problems, we propose an adaptive page prefetching control scheme (APC), which periodically monitors access patterns of prefetched pages in a process unit. Such a pattern is represented as the ratio of referenced pages among prefetched ones before they are evicted from memory. Then APC uses the ratio to adjust the number of pages that 4.4BSD VM intends to prefetch at a page fault. Thus APC allows 4.4BSD VM to prefetch a proper number of pages to have a better effect on reducing disk I/Os, though page access patterns of an application vary in runtime. The experiment of our technique implemented in FreeBSD 6.2 shows that APC improves the execution times of SOR, SMM, and FFT benchmarks over 4.4BSD VM by up to 57%.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.5 no.2
• /
• pp.100-108
• /
• 1995

Heat transfer plays a critical role in determining interface location and shape in ZMR process, which is used for the fabrication of silicon - on - insulator structure. In this work, the two - dimensional pseudo - steady - state ZMR model has been developed that can simulate the heat transfer process during ZMR process. It contains the radiation, convection and conduction heat transfer and determines the interface shapes. Numerical solutions from the model include flow field in the molten zone, temperature field in the full SOl structure and the location of solid/liquid interface in the silicon thin film and silicon substrate. We examined the effects of the various system parameters on the temperature profiles and the interface shape.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.14 no.5
• /
• pp.1145-1158
• /
• 1994

A three-dimensional, finite difference, numerical model with free surface was developed on ${\sigma}$-coordinate. A semi-implicit numerical scheme in time has been adopted for computational efficiency. The scheme is essentially independent of the stringent stability criteria (CFL condition) for explicit schemes of external surface gravity wave. Implicit algorithm was applied for vertical shear stress, Coriolis force and pressure gradient terms. The reliability of the model with vertically variable grid system was checked by the comparison of simulation results with analytic solution of wind-driven currents in a one-dimensional channel. Sensitivity analysis of differencing parameters was carried out by applying the model to the calculation of wind-driven currents in a square lake.

• The Transactions of the Korea Information Processing Society
• /
• v.3 no.4
• /
• pp.992-1001
• /
• 1996

Radix sort scans the data twice in a pass, to search bit 0s of the items being sorted and store them into the lowest address, and to search bit 1s and st ore them into the following addresses. This doubles the sorting time. In this paper, we introduce Reverse Radix Sort Algorithm, in which the data being sorted are sacnned just once and write upward from the lowest address if it is 0 and downward from the highest address if it is 1. The algorithm is simple and the hardware sorter implemented by this method shows very high sorting sped. Hardware implementation requires two separate pocket memories, register, an upward increasing address counter, a downward decreasing address counter, and comparator. The software simulation of Reverse Radix Sor Algorithm performs sorting in the speed of 54.9ms per 10 thousand of 8 bit digit data, but the hardware sorter spends 5.3ms to sort the same number of data.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.21 no.5
• /
• pp.90-99
• /
• 1984

A onetimensional distribution of the temperature and the heat source in the SOI (silicon-on-insulator) multi-layer structure illuminated by tungsten lamps from both sides was obtained by solving the heat equation in steady state on a finite difference grid using successive over-relaxation method. The heat source distribution was obtained by considering such features as spectral components of the light source, multiple reflection at the internal interfaces, temperature and frequency dependence of the light absorption coefficient, etc. The front and back surface temperatures, which are boundary conditions for the heat equation, were derived from a requirement that they satisfy the radiation conditions. The radiation flux as well as the conduction flux was considered in modelling the thermal behaviour at the internal interfaces. Since the temperature and the heat source profiles are strongly dependent upon each other, the calculation of each profile was iterated using the updated profile of the other until they are consistent with each other. The experimental temperature at the front surface of the wafer as measured by Pyrometer was about 1200$^{\circ}$K, while the simulated temperature was 1120$^{\circ}$K.

• Journal of the Korean Ceramic Society
• /
• v.33 no.4
• /
• pp.391-398
• /
• 1996

In order to understand the electrostrictive behavior of Pb(Mg1/3Nb2/3)O3-PbTiO3(PMN-PT) solid solutions the dielectric constants and the electric-field-induced strains in (1-x)PMN-xPT (x=0.0-0.4) were investigated in the temperature range -5$0^{\circ}C$-20$0^{\circ}C$. Powder of (1-x)Pb(Mg2/3Nb2/3)O3-xPbTiO3 (x=0.0, 0.1, 0.2, 0.3, 0.35, and 0.4) were prepared from the oxide forms of Pb, Mg, Nb and Ti via a columbite precursor method As the amount of PbTiO3 increases the temperature of maximum dielectric constant(T$\varepsilon$max) increases and the phase transition become less diffusive. The strain maximum occurs only when the diffuse phase transition occurs from rhombohedral to cubic or rhombohedral to tetragonal as in x=0.1-0.35 The strains monotonically decrease with temperature in the materials in which phase transition occurs from tetragonal to cubic as in x=0.4.