• Journal of the Korean Society for Nondestructive Testing
• /
• v.15 no.1
• /
• pp.299-309
• /
• 1995

A geometrical inverse heat conduction problem is solved for the development of Infrared Computerized-Axial-Tomography (IR CAT) Scan by using a boundary element method in conjunction with regularization procedure. In this problem, an overspecified temperature condition by infrared scanning is provided on the surface, and is used together with other conditions to solve the position of an unknown boundary (cavity). An auxiliary problem is introduced in the solution of this problem. By defining a hypothetical inner boundary for the auxiliary problem domain, the cavity is located interior to the domain and its position is determined by solving a potential problem. Boundary element method with regularization procedure is used to solve this problem, and the effects of regularization on the inverse solution method are investigated by means of numerical analysis.

• Journal of Sericultural and Entomological Science
• /
• v.36 no.1
• /
• pp.37-43
• /
• 1994

The effects of some sodium phosphates as auxiliary agents were studied on the blockade of hardness for silk degumming. In this work, four kinds of sodium phosphates were tested and the results were obtained through masking effects of metallic ions, difference of pH value and boil-off ratio. The degumming of calcium ingredient was analyzed by means of atomic absorption spectrophotometer and degumming test of cocoon shell was performed in the presence of calcium ingredient and sodium phosphates added to soap solution. In the view of the effects of sodium phosphates on calcium hardness, tetrasodium pyrophosphate(TSPP) and sodium phosphate dibasic(SPD) masked calcium ions more than sodium phosphate monobasic(SPM) and sodium hexametaphosphate(SHP). SHP and TSPP have excellent abilities of masking ferrous ions. The pH values of TSPP solution is higher than others, but lower than soap solution. The pH values were differently measured one another among the sodium phosphates but the boil-off ratio was increased in case of sodium phosphate with high pH value.

• Geophysics and Geophysical Exploration
• /
• v.11 no.2
• /
• pp.85-92
• /
• 2008

Magnetotelluric (MT) methods are widely applied as an effective exploration technique to geothermal surveys. Two-dimensional (2-D) analysis is frequently used to investigate a complicated subsurface structure in a geothermal region. A 2-D finite-element method (FEM) is usually applied to the MT analysis, but we must pay attention to the accuracy of so-called auxiliary fields. Rodi (1976) proposed an algorithm of improving the accuracy of auxiliary fields, and named it as the MOM method. Because it introduces zeros into the diagonal elements of coefficient matrix of the FEM total equation, a pivoting procedure applied to the symmetrical band matrix makes the numerical solution far less efficient. The MOM method was devised mainly for the inversion analysis, in which partial derivatives of both electric and magnetic fields with respect to model parameters are required. In the case of forward modeling, however, we do not have to resort to the MOM method; there is no need of modifying the coefficient matrix, and the auxiliary fields can be elicited from the regular FEM solution. The computational efficiency of the MOM method, however, can be greatly improved through a sophisticated rearrangement of the total equation.

• Tunnel and Underground Space
• /
• v.29 no.6
• /
• pp.480-507
• /
• 2019

This paper aims at optimizing the auxiliary ventilation system in large-opening limestone mines with unducted fans. An extensive CFD and also site study were carried out for optimization at the blind entries. The fan location, operating mode, and layout are the parameters for optimization. Since the jet stream discharged from the auxiliary fan is flowing faster than 15 m/s in most of the cases, the stream collides with floor, sides or roof and even with the jet stream generated from the other fan placed upstream. Then, it is likely to lose a large portion of its inertial force and then its ventilation efficiency drops considerably. Therefore, the optimal fan installation interval is defined in this study as an interval that maximizes the uninterrupted flowing distance of the jet stream, while the cross-sectional installation location can be optimized to minimize the energy loss due to possible collision with the entry sides. Consequently, the optimization of the fan location will improve ventilation efficiency and subsequently the energy cost. A number of different three-dimensional computational domains representing a full-scale underground space were developed for the CFD study. The velocity profiles and the CO concentrations were studied to design and optimize the auxiliary ventilation system without duct and at the same time mine site experiments were carried out for comparison purposes. The ultimate goal is to optimize the auxiliary ventilation system without tubing to provide a reliable, low-cost and efficient solution to maintain the clean and safe work environment in local large-opening underground limestone mines.

• Journal of the Korean Institute of Gas
• /
• v.25 no.6
• /
• pp.7-13
• /
• 2021

Various research has been done on fires and explosions at gas stations at home and abroad. However, only studies of off-site damage in the event of fire at the gas station were conducted, and research on fire at the auxiliary facilities in the gas station was insufficient. The gas station is a place where anyone can easily access dangerous goods. As the risk of fire increases due to the recent increase of auxiliary facilities such as convenience stores and car repair shops in gas stations, it is important to detect the effects of fire on the main oil refinery in case of fire and to verify the validity of existing regulations. In this thesis, we conducted a study to find out the effect of radiation heat on the separation between fixed and fixed oil reactors in the event of fire at an auxiliary facility. Simulation was modelled using FDS 5.5.3 Version, and the size of the fire source was configured with 13 fire assessment devices and the heat emission rate per unit area was entered. Simulation shows that the separation distance of 2 m does not secure the safety of the gas pump in the event of fire at the auxiliary facilities, and radiation heat does not damage at the separation distance of at least 4 m. Accordingly, facilities that can block radiant heat in the event of fire at auxiliary facilities, and measures to limit the use of auxiliary facilities or to re-impose the separation between buildings and fixtures will be needed.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.15 no.3
• /
• pp.201-222
• /
• 2011

In the present work, the mathematical model of wire coating in a straight annular die is developed for unsteady second grade fluid in the form of partial differential equation. The Optimal Homotopy Asymptotic Method (OHAM) is applied for obtaining the solution of the model problem. This method provides us a suitable way to control the convergence of the series solution using the auxiliary constants which are optimally determined.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.1
• /
• pp.99-103
• /
• 2008

Solvent extraction using salphen as a ligand has been investigated for the selective separation and determination of trace Fe(II) and Fe(III). A salphen ligand was synthesized, and solvent extraction variables, such as solution pH, the concentration of salphen, the type of organic solvent, auxiliary agents, oxidants and the effect of interference were optimized. Salphen is stable at pH 3-4, and Fe(III)-salphen complexes can be selectively extracted into an MIBK(4-methyl-2-pentanone) phase from an aqueous solution within this pH range. For the determination of the total amount of iron in 100 mL of aqueous solution, Fe(II) ions were completely oxidized using 0.05 mL of 3.5% H2O2 without side reactions. To evaluate its applicability, the proposed method was applied to determine trace Fe(II) and Fe(III) in several kinds of water samples. Reproducible results were obtained with RSD of less than 3.0%, and the recoveries for this reliability were obtained with 91-112%.

• Journal of the Chungcheong Mathematical Society
• /
• v.7 no.1
• /
• pp.141-152
• /
• 1994

We consider a numerical scheme for solving a nonlinear boundary integral equation (BIE) obtained by reformulation the nonlinear boundary value problem (BVP). We give a simple alternative to the standard collocation method for the nonlinear BIE. This method consists of one conventional linear system and another coupled linear system resulting from an auxiliary BIE which is obtained by differentiating both side of the nonlinear interior integral equations. We obtain an analogue BIE through the perturbation of the fundamental solution of Laplace's equation. We procure the super-convergence of approximate solutions.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.21 no.46
• /
• pp.51-58
• /
• 1998

In this paper a bimatrix game with imprecise values in its matrix of payoffs is considered. We propose a method for its solution based on the establishment of a linear complementary problems for two players. To solve the problems we use the auxiliary models resulting from the methods for ranking fuzzy numbers.

• Journal of the Microelectronics and Packaging Society
• /
• v.30 no.1
• /
• pp.71-78
• /
• 2023

The possibility of improving plating thickness distribution was investigated through quantitative consideration of bipolar electrodes without external power applied. By having the cathode tilted with respect to the anode, the potential distribution in the electrolyte solution adjacent to the cathode is different due to the difference in iR drop due to the path difference to the anode in each region of the cathode. The purpose of this study is to observe the bipolar characteristics in the case of an auxiliary anode for the non-uniform potential distribution of such a Hull cell. In particular, in order to evaluate the possibility of improving the non-uniform thickness distribution of the cathode by utilizing these bipolar characteristics, it was verified through experiments and simulations, and the electric potential and current density distribution around the bipolar electrode were analyzed. The electroplating in a Hull cell was performed for 75 min at a current density of 10 mA/cm², and the average thickness is about 16 ㎛. The standard deviation of the thickness was 10 ㎛ in the normal Hull cell without using the auxiliary anode, whereas it was 3.5 ㎛ in the case of using the auxiliary cathode. Simulation calculations also showed 8.9 ㎛ and 3.3 ㎛ for each condition, and it was found that the consistency between the experimental and simulation results was relatively high, and the thickness distribution could be improved through using the auxiliary anode by the bipolar phenomenon.