• 한국태양에너지학회:학술대회논문집
• /
• 2011.11a
• /
• pp.40-44
• /
• 2011

Recent studies in crystalline silicon solar cell fabrication have been focused on high efficiency and low cost. However, the rising of the cost results in additional processes to approach high efficiency. The fabrication process also becomes complicated with additional technologies. In this paper, we studied the selective emitter formation with phosphorous paste to improve the conversion efficiency. Selective emitter formations like two-step diffusion or etch-back method require at least one more step compared in the conventional line since heavily and lightly doped area was needed to form separately.However,one-step diffusion process is the method diffusing heavily and lightly doped area at the same time only with additional screen-printing step. This study lays the foundation for the simple way to form the selective emitter.

• Proceedings of the KIEE Conference
• /
• 2006.11a
• /
• pp.192-194
• /
• 2006

In this paper, the situation of energy efficiency standards for motors and diffusion states are analyzed and a new methodology is proposed using diffusion models and learning curves. The existing diffusion models could not explain affects from new appliances' penetration during the diffusion. But a mixed diffusion model with learning curves or learning ratio is studied to explain this penetration.

• Nuclear Engineering and Technology
• /
• v.49 no.6
• /
• pp.1125-1134
• /
• 2017

In this paper, we present a new multilevel in space and energy diffusion (MSED) method for solving multigroup diffusion eigenvalue problems. The MSED method can be described as a PI scheme with three additional features: (1) a grey (one-group) diffusion equation used to efficiently converge the fission source and eigenvalue, (2) a space-dependent Wielandt shift technique used to reduce the number of PIs required, and (3) a multigrid-in-space linear solver for the linear solves required by each PI step. In MSED, the convergence of the solution of the multigroup diffusion eigenvalue problem is accelerated by performing work on lower-order equations with only one group and/or coarser spatial grids. Results from several Fourier analyses and a one-dimensional test code are provided to verify the efficiency of the MSED method and to justify the incorporation of the grey diffusion equation and the multigrid linear solver. These results highlight the potential efficiency of the MSED method as a solver for multidimensional multigroup diffusion eigenvalue problems, and they serve as a proof of principle for future work. Our ultimate goal is to implement the MSED method as an efficient solver for the two-dimensional/three-dimensional coarse mesh finite difference diffusion system in the Michigan parallel characteristics transport code. The work in this paper represents a necessary step towards that goal.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.5
• /
• pp.476-480
• /
• 1984

This paper deals with nitrogen diffusion velocity and activation energy in diffusion layer and compound layer in ion-nitriding, and presents observations on the effect of deformation according to nitriding methods. During the experiment the activation energy and diffusion velocity of nitrogen have been examined in S45C steel samples. It is found that the results of an investigation correspond with the theoretical data and the ion-nitriding method offers less deformation than conventional salt-bath method of nitriding.

• Proceedings of the KIEE Conference
• /
• 2005.10c
• /
• pp.320-322
• /
• 2005

Nowadays the concern about development and diffusion strategics of new & renewable energy and its technologies is getting higher globally as Kyoto Protocol has taken effect this year and oil has been rising in price tremendously. Developed countries have already commenced the study and research for this problem and are looking for various solutions. In this paper, environment of new & renewable energy in Korea is analyzed and estimated using diffusion model as a pre-study for proposing appropriate strategies and feasible methods.

• Nuclear Engineering and Technology
• /
• v.54 no.4
• /
• pp.1195-1205
• /
• 2022

Recent developments on spectral diffusion algorithms, i.e., algorithms which exploit the projection of the solution on the eigenfunctions of the Laplacian operator, demonstrated their effective applicability in fast transient conditions. Nevertheless, the numerical error introduced by these algorithms, together with the uncertainties associated with model parameters, may impact the reliability of the predictions on short-lived volatile fission product release from nuclear fuel. In this work, we provide an upper bound on the numerical error introduced by the presented spectral diffusion algorithm, in both constant and time-varying conditions, depending on the number of modes and on the time discretization. The definition of this upper bound allows introducing a methodology to a priori bound the numerical error on short-lived volatile fission product retention.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.57 no.11
• /
• pp.1938-1945
• /
• 2008

Due to rapid economic growth, the usage of residential cooling electrical appliances such as air conditioners and refrigerators has increased dramatically for the last decades. In other to reduce its energy consumption, the authorities have applied energy efficiency standards for principal appliances, including refrigerator. This paper estimates the distribution of refrigerators using the Bass Diffusion Model and then performs economic analysis corresponding to enhancement of energy efficiency more correctly than existing methods.

• Journal of KIISE:Information Networking
• /
• v.35 no.1
• /
• pp.34-45
• /
• 2008

In dynamic wireless sensor networks where sources and sinks are moving or are created/died, control overheads for route establishment are increased and thus become one of the major factors for energy consumption. This study introduces prefetching and pruning for Directed Diffusion to remove redundant control messages. Prefetching collects path information for each event with "AnyEvent" in advance and gives quick responses without further flooding of requests. Pruning accumulates history information from previous requests and replies, and then stops forwarding a request towards where the event does not exist. Simulation results with ns show that it is possible to build implicit and soft infrastructures within a Directed Diffusion system through these active collection and passive accumulation and they improve energy consumption more as control overhead goes higher.

• Journal of IKEEE
• /
• v.23 no.3
• /
• pp.793-799
• /
• 2019

In this study, the diffusion process and the thermal energy distribution gradient of the sensor were confirmed by using the finite element analysis program (COMSOL) of the mesh method to analyze the thermal diffusion in the wearable fabric (Nylon) + MWCNT gas sensor. To analyze the diffusion process of thermal energy, the structure of the gas sensor was modeled in a two dimension plane. The proposed modeling was presented with the characteristic value for the component of the sensor, and the gas sensor designed using the mesh finite element method (FEM) was proposed and analyzed by suggesting the one-way partial differential equation in the governing equation to know the degree of thermal energy diffusion and the thermal energy gradient. In addition, the temperature gradient 10[K/mm] of the anode-cathode electrode layer and the gas detection unit was investigated by suggesting the heat velocity transfer equation.

• Solar Energy
• /
• v.5 no.2
• /
• pp.54-59
• /
• 1985

Due to the grainboundary recombination and the poor diffusion length, the polycrystalline cell efficiency is lower than the singlecrystalline cell. In order to define the effect of grains and grain-boundaries, 2 - dimensional differential diffusion equations of minority carrier are modelled. To solve them, two theoretical formulas are derived, which can be evaluated the grainboundary recombination velocity and the grain diffusion length. Also computer-aided numerical analysis is given.