• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.4
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• pp.389-397
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• 1998

A loop duct system is often found in a VAV-HVAC(variable air volume heating, ventilating and air conditioning) design. It is known that the simple T-method is not be applicable to the loop duct system and cannot be used to calculate the flow rate and the pressure drop at each duct section of the loop duct system. In this paper, the extended T-method has been developed and it is found to be applicable to the loop duct system to which the simple T-method cannot be applied. The validity of the extended T-method has been verified by using to solve for a simple, ideal loop duct system for which there exists analytical solution. In addition, the extended T-method is employed to compute the loop duct system of a real building with an area of 380$m^2$. The results show that the computed flow rate at the exit differs from the designed flow rate by a range of -13.6~43.5 %. Consequently, three design factors must be adjusted in order that the flow rate may be balanced. These include the duct sizes, in terms of their lengths and diameters, the sub-duct locations and the positioning of damper which is found upstream of the exit duct.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.579-587
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• 1999

The flow distribution characteristics in a complex duct system have been investigated in this paper by three means, namely experimental measurement, numerical simulation and the Extended T-method analysis. While the exit flow rates predicted by the three-dimensional CFD calculation and those given by the experiment show a close agreement, the results from the one-dimensional Extended T-method are found to differ from the experiment by -22.2% to 26.3% for the various exits. These discrepancies may be attributed to the underlying limitation concerning the fitting loss coefficients, which assume that the flow in front of the fittings is fully developed. It is proposed that, in order to analyse the three-dimensional flow distributions in a complex duct system by one-dimensional analysis such as the Extended T-method, further Improvements to the fitting loss coefficients should be made.

• Steel and Composite Structures
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• v.6 no.1
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• pp.33-53
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• 2006

The rotational behaviour of bolted extended end plate beam-to-column connections is evaluated in the context of the component method. The full moment-rotation response is characterized from the force-deformation curve of the individual joint components. The deformability of end plate connections is mostly governed by the bending of the column flange and/or end plate and tension elongation of the bolts. These components form the tension zone of the joint that can be modelled by means of "equivalent T-stubs". A systematic analytical procedure for characterization of the monotonic force-deformation behaviour of individual T-stub connections is proposed. In the framework of the component method, the T-stub is then inserted in the joint spring model to generate the moment-rotation response of the joint. The procedures are validated with the results from an experimental investigation of eight statically loaded extended end plate bolted moment connections carried out at the Delft University of Technology. Because ductility is such an important property in terms of joint performance, particularly in the partial strength joint scenario, special attention is given to this issue.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.287-297
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• 2018

To improve the performance of sensorless induction motor (IM) drives, a novel speed estimation method based on the real-time adaptive extended Kalman filter (RAEKF) is proposed in this paper. In this algorithm, the fuzzy factor is introduced to tune the measurement covariance matrix online by the degree of mismatch between the actual innovation and the theoretical. Simultaneously, the fuzzy factor can be continuously self-tuned tuned by the fuzzy logic reasoning system based on Takagi-Sugeno (T-S) model. Therefore, the proposed method improves the model adaptability to the actual systems and the environmental variations, and reduces the speed estimation error. Furthermore, a simple exponential function based on the fuzzy theory is used to reduce the computational burden, and the real-time performance of the system is improved. The correctness and the effectiveness of the proposed method are verified by the simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.12
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• pp.575-580
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• 2000

Switching of the transmission lines(T/L) is one of the ways for suppressing the short circuit capacity. This paper presents the extended optimal power flow(OPF) to the problem of selecting the T/Ls to be open. The constraints of the short circuit currents within limits are added to the inequalities of OPF. Also, the overload on the other lines due to switching of T/Ls is avoided by the linearized inequalities. The number of the open lines can be minimized by incorporating into the objective function of OPF in order to maintain reliability. The method of an effective calculation of the extended OPF is also proposed in this paper, which makes the two parts decoupled. The one concerning the generation dispatch is solved in the first place by the conventional method. Secondly, the other concerning the line-switching is optimized by the proposed formulation.

• Journal of Korean Institute of Industrial Engineers
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• v.25 no.2
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• pp.226-232
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• 1999

Graph Coloring Problem(GCP) is a problem of assigning different colors to nodes which are connected by an edge. An extended form of GCP is TCP (T-coloring problem) and, in TCP, edge weights are added to GCP and it is possible to extend GCP's applications. To solve TCP, in this paper, we propose an improved Simulated Annealing(SA) method with search space smoothing. It has been observed that the improved SA method obtains better results than SA does.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.490-493
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• 2002

In this paper, the old Fourier-Motzkin method (abbreviated as the old FH method from now on) is first modified to the form which can derive all minimal vectors as well as all minimal support vectors of nonnegative integer homogeneous solutions (i.e., T-invariants) for a matrix equation $Ax=b=0^{m{\times}1}$, $A\epsilonZ^{m{\times}n}$ and $b\epsilonZ^{m{\times}1}$, of a given Petri net, where the old FM method is a well-known and direct method that can obtain at least all minimal support solutions for $Ax=0^{m{\times}1}$ from the incidence matrix . $A\epsilonZ^{m{\times}n}$, Secondly, for $Ax=b\ne0^{m{\times}n}$ a new extended FM method is given; i.e., all nonnegative integer minimal vectors which contain all minimal support vectors of not only homogeneous but also inhomogeneous solutions are systematically obtained by applying the above modified FH method to the augmented incidence matrix $\tilde{A}$ =〔A,-b〕$\epsilon$ $Z^{m{\times}(n＋1)}$ s.t. $\tilde{A}\tilde{x}$ = 0^{m{\times}1}$ However, note that for this extended FM method we need some criteria to obtain a minimal vector as well as a minimal support vector from both of nonnegative integer homogeneous and inhomogeneous solutions for Ax=b. Then those criteria are also discussed and given in this paper.

• Korean Journal of Computational Design and Engineering
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• v.10 no.1
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• pp.27-39
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• 2005

Implicit surfaces are geometric shapes which are defined by implicit functions and exist in three-dimensional space. Recently, implicit surfaces have received much attention in solid modeling applications because they are easy to represent the location of points and to use boolean operations. However, it is difficult to chart points on implicit surfaces for rendering. As efficient rendering method of implicit surfaces, the original Adaptively Sampled Distance Fields (ADFs) $method^{[1]}$ is to use sampled distance fields which subdivide the three dimensional space of implicit surfaces into many cells with high sampling rates in regions where the distance field contains fine detail and low sampling rates where the field varies smoothly. In this paper, in order to maintain the sharp features efficiently with small number of cells, an extended ADFs method is proposed, applying the Dual/Primal mesh optimization $method^{[2]}$ to the original ADFs method. The Dual/Primal mesh optimization method maintains sharp features, moving the vertices to tangent plane of implicit surfaces and reconstructing the vertices by applying a curvature-weighted factor. The proposed extended ADFs method is applied to several examples of implicit surfaces to evaluate the efficiency of the rendering performance.

• The Journal of Korean Association of Computer Education
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• v.8 no.1
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• pp.93-103
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• 2005

Since the most program execution time is consumed in a loop structure, extracting parallelism from sequential loop programs is critical for the faster program execution. Conventional studies for extracting the parallelism are focused mostly on a uniform data dependence distance. In this paper, we proposed data dependency elimination method for a nested loop and extended data dependency elimination method to extract parallelism from the loop with procedure calls. The data dependency elimination method and the extended data dependency elimination method can be applied to uniform and non-uniform data dependency distance. We compared our method with conventional methods using CRAY-T3E for the performance evaluation. The results show that the proposed algorithms are very effective.

• Communications for Statistical Applications and Methods
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• v.21 no.1
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• pp.81-91
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• 2014

This study derives the characteristic functions of (multivariate/generalized) t distributions without contour integration. We extended Hursts method (1995) to (multivariate/generalized) t distributions based on the principle of randomization and mixtures. The derivation methods are relatively straightforward and are appropriate for graduate level statistics theory courses.