• International Journal of CAD/CAM
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• v.11 no.1
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• pp.11-17
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• 2011

A new method has been developed in this paper for automatic quadrilateral mesh generation for a two-dimensional domain. The method is named 'centering method' because it centers a point at the domain and then divides it into sub-domains using cutting lines from the center point. Each of the cutting lines is selected based on the criterion using the angles between the boundary of the domain and the cutting line. The decomposition of the domain into sub-domains is repeated until every subdomain has four or six nodes. Pre-defined splitters are used to divide six-node domains into quadrilateral elements depending on their configuration and presence on the boundary of the initial domain. Arbitrary domains are meshed as examples to verify the robustness of the new method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.1-10
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• 1990

RILEM proposed three point bend test to determine the fracture energy of concrete, but there is discrepancy between the theoritical and the experimental fracture energy of concrete by the influence of self-weight of concrete. This paper presents four point bend test using proving ring in order to take into account the influence of self-weight of concrete. The initial notch to beam depth ratio was varied from 0.2 to 0.6 in order to investigate the variation of fracture energy of concrete according to the variation of initial notch depth. The proposed four point bend test using proving ring was verified to be superior to three point bend test.

• Korean Journal of Oriental Medicine
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• v.18 no.2
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• pp.25-38
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• 2012

Objective : This study was conducted to underpin the theory of Taegeuk Acupuncture systematically and increase the utility of clinical trial and a range of application. Method : This study analysed ByungHaeng Lee's theory, who is the originator of Taegeuk Acupuncture, by focusing on "Young Chu GuChimSibYiWon" Result & Conclusion : 1. ByungHaeng Lee's thought about Viscera and Bowels is following medicine of Internal Classic. Even though JeMa Lee's thought about Viscera and Bowels has same name with ByungHaeng Lee's, but the functional meaning and related part is totally different. So, four constitution types in Taegeuk Acupuncture are different from four constitution types in Four-Constitution Medicine. Therefore, Taegeuk Acupuncture isn't related with Four-Constitution Medicine 2. On the authority of "Young Chu GuChimSibYiWon", we can extend 4 therapeutic acupuncture point combinations of Taegeuk Acupuncture to ten therapeutic acupuncture point combinations which tentatively named 'Five Viscera Source Point Acupuncture'. 3. To consider an example of eight constitutional acupuncture, Taegeuk Acupuncture thoroughly says constitutional acupuncture. Especially, JaeGyuKim's Taegeuk Acupuncture has specific diagnosis standard that after treating a patient with acupuncture, he checks an oppressive pain at the precordial region and a voiced sound at liver and then he makes sure constitution of patient. So we can consider JaeGyuKim's Taegeuk Acupuncture as constitutional acupuncture. However, it has to change the name of four constitution types to taegeuk greater yang person, taegeuk lesser yang person, taegeuk greater yin person, taegeuk lesser yin person so as to avoid confusion. 4. Taegeuk Acupuncture is markedly simple in comparison with other acupuncture, so it needs to extend the utility of clinics by enlarging treatment acupuncture points.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.2982-2989
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• 2021

One of the consequences of the 475 ℃ embrittlement of duplex stainless steels is the reduction of the resistance to localized corrosion. Therefore, the detection of this type of embrittlement before the material exhibits significant loss in toughness, and corrosion resistance is important to ensure the structural integrity of critical components under corrosion threats. In this research, conductivity measurements are performed using the alternating current potential drop (ACPD) technique with using a portable four-point probe as a nondestructive evaluation (NDE) method for detecting the embrittlement in a 2507 (UNS S32750) super duplex stainless steel (SDSS) aged at 475 ℃ from as-received condition to 300 h. The electric conductivity results were compared against two electrochemical tests namely double loop electrochemical potentiokinetic reactivation (DL-EPR) and critical pitting temperature (CPT). Mechanical tests and the microstructure characterized using scanning electron microscopy (SEM) imaging are conducted to track the progress of embrittlement. It is shown that the electric conductivity correlates with the changes in impact energy, microhardness, and CPT corrosion tests result demonstrating the feasibility of the four-point probe as a possible field-deployable method for evaluating the 475 ℃ embrittlement of 2507 SDSS.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.12
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• pp.3357-3368
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• 1994

Total pressure losses required to calculate the total-to-total efficiency are estimated by integrating empirical loss coefficients of four loss mechanisms along the mean-line of blades as follows; blade profile loss, secondary flow loss, end wall loss and tip clearance loss. The off-design points are obtained on the basis of Howell's off-design performance of a compressor cascade. Also, inlet-outlet air angles and camber angle are obtained from semi-empirical relations of transonic airfoils' minimum loss incidence and deviation angles. And nominal point is replaced by the design point. It is concluded that relatively simple loss models and Howell's off-design data permit us to calculate the off-design performance with satisfactory accuracy. And this method can be easily extended for off-design performance prediction of multi-stage compressors.

• Nuclear Engineering and Technology
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• v.32 no.5
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• pp.433-445
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• 2000

The interfacial area concentration (IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The IAC can be measured by a local conductivity probe method that uses the difference of conductivity between water and air/steam. The number of sensors in the conductivity probe may be differently chosen by considering the flow regime of two-phase flow. The four sensor conductivity probe method predicts the IAC without any assumptions of the bubble shape. The local IAC can be obtained by measuring the three dimensional velocity vector elements at the measuring point, and the directional cosines of the sensors. The five sensor conductivity probe method proposed in this study is based on the four sensor probe method. With the five sensor probe, the local IAC for a given referred measuring area of the probe can be predicted more exactly than the four sensor probe. In this paper, the mathematical approach of the five sensor probe method for measuring the IAC is described, and a numerical simulation is carried out for ideal cap bubbles of which the sizes and locations are determined by a random number generator.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.97-100
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• 2004

Multivariate Newton Raphson method is developed to perform the particle tracking in the three dimensional area using four objective functions. In this method, three variables are solved to compute target point and actual and real tracking time. The simulated pathlines in various types of three dimensional elements are well matched with exact pathline.

• Journal of Power Electronics
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• v.14 no.3
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• pp.572-579
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• 2014

As a non-linear time variant system, the four-quadrant line converter of an electric multiple unit (EMU) was expressed by linear time periodic functions near an operating point and modeled by a steady-state harmonic domain matrix. The components were then combined according to the circuit connection and relations of the feedback control loops to form a complete converter model. The proposed modeling method allows the study of the amplitude of harmonic impedances to explore harmonic coupling. Moreover, the proposed method helps provide a better design for the converter controllers, as well as solves the problem in coordination operation between the EMUs and the AC supply. On-site data from an actual $CRH_2$ high-speed train were used to validate the modeling principles presented in the paper.

• Journal of applied mathematics & informatics
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• v.28 no.1_2
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• pp.411-423
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• 2010

In this paper, a numerical method for singular perturbation problems arising in chemical reactor theory for general singularly perturbed two point boundary value problems with boundary layer at one end(left or right) of the underlying interval is presented. The original second order differential equation is replaced by an approximate first order differential equation with a small deviating argument. By using the trapezoidal formula we obtain a three term recurrence relation, which is solved using Thomas Algorithm. To demonstrate the applicability of the method, we have solved four linear (two left and two right end boundary layer) and one nonlinear problems. From the results, it is observed that the present method approximates the exact or the asymptotic expansion solution very well.

• Journal of applied mathematics & informatics
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• v.26 no.5_6
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• pp.1273-1287
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• 2008

In this paper, the numerical integration method for general singularly perturbed two point boundary value problems with mixed boundary conditions of both left and right end boundary layer is presented. The original second order differential equation is replaced by an approximate first order differential equation with a small deviating argument. By using the trapezoidal formula we obtain a three term recurrence relation, which is solved using Thomas Algorithm. To demonstrate the applicability of the method, we have solved four linear (two left and two right end boundary layer) and one nonlinear problems. From the results, it is observed that the present method approximates the exact or the asymptotic expansion solution very well.