• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2003.11a
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• pp.289-290
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• 2003

This paper gives a method for the minimization of the fuel cost by optimal generation. Derivation of the sensitivity of system loss by optimization technique is introduced and the loss sensitivities are substituted into the optimality conditions to obtain the minimized fuel cost.

• Journal of Korean Institute of Industrial Engineers
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• v.24 no.2
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• pp.175-183
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• 1998

When a product is designed, tolerances must be given to the product so that required functions are guaranteed and production costs are minimized. In this research, a model is suggested which allocates tolerances to components optimally according to the STA(Statistical Tolerance Allocation) method. Taking into account the concept that dimensional errors have characteristics of statistical distributions, this model presents the discrete pseudo-boolean approach for the tolerance optimization by minimizing the tolerance cost and the quality loss cost. In this approach, two methods are proposed for the reduction of the problem scale; 1) a method for converting the minimization model for casts into the maximization model for cost savings, and 2) procedures to reduce the number of constraints and variables.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.555-560
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• 2022

In this study, the insertion loss and phase delay according to the multi-layer structure radome parameters were analyzed using the boundary value solution approach, and the multi-layer structure and hexa mesh structures with low-loss electrical characteristics for the Ku-band transmission/reception frequency of 10.7 ~ 14.5 GHz were designed and manufactured. A hexa mesh was applied to minimize radio wave transmission and scattering, which lowered the transmittance refractive index according to the radio incident angle and minimized dielectric loss through high-density foam. Similar to the simulation result, the transmission loss obtained the gain in a specific receiving frequency band, and in the transmission frequency band, an excellent low loss characteristic was obtained with an insertion loss of 0.8dB or less. The results of this study can be used in radio transmission radomes of low-weight, low-cost end-system protection devices.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1015-1024
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• 2015

This paper introduces a low cost, high efficiency, high performance three-phase unified power quality conditioner (UPQC) by using four-switch three-phase inverters (FSTPIs) and an extra capacitor in the shunt active power filter (APF) side of the UPQC. In the proposed UPQC, both shunt and series APFs are developed by using FSTPIs so that the number of switching devices is reduced from twelve to eight devices. In addition, by inserting an additional capacitor in series with the shunt APF, the DC-link voltage in the proposed UPQC can also be greatly reduced. As a result, the system cost and power loss of the proposed UPQC is significantly minimized thanks to the use of a smaller number of power switches with a lower rating voltage without degrading the compensation performance of the UPQC. Design of passive components for the proposed UPQC to achieve a good performance is presented in detail. In addition, comparisons on power loss, overall system efficiency, compensation performance between the proposed UPQC and the traditional one are also determined in this paper. Simulation and experimental studies are performed to verify the validity of the proposed topology.

• Journal of the Korea Institute of Building Construction
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• v.3 no.2
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• pp.95-102
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• 2003

Financial difficulties and claims frequently stop construction works and cause subsequent contract cancellations. However, as the criteria to assess costs have not been established, many cases of legal disputes over the assessment of cancellation costs are taking place and the concerned parties are suffering the loss of time and money. Therefore, the present research aimed at developing a rational and systematic model of cancellation cost assessment following the cancellation of contracts. The research was carried out in the following methods and scopes. 1 ) The research was focused on the assessment of fair cancellation costs from constructors' side for contracts cancelled by any causes for which the owners have liability. 2) To obtain basic materials about cancellation cost assessment methods, contracts, claims, contract cancellations and construction-related laws at home and abroad were examined. 3) A cost assessment model was developed for systematization and efficient operation of cancellation cost assessment, and the reliability and efficiency of the proposed model was verified through a case study. The conclusions drawn from the research are as follows. The importance of the cancellation cost assessment model was confirmed as, using the cancellation cost assessment model, direct cancellation cost and indirect cancellation cost could be assessed systematically, the number of disputable items could be reduced because reasonable evidences of actual spending were presented, and the loss of constructors could be minimized because systematic and rational cost assessment became possible for many disputable cases of indirect cancellation cost, which the constructors had been unable to prove so far though having spent.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.193-194
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• 2011

This paper describes a control method to minimize the filter capacitor of a PFC AC/DC converter for LED driver. The rectified secondary voltage of the transformer has 120Hz ripple unlike the conventional converter for the LED drive. Therefore, the filter capacitor can be minimized and this provides reduced cost, low switching loss, and long life of the converter.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.9-10
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• 2011

This paper describes a control method to minimize the filter capacitor of a AC/DC converter for LED driver. The rectified secondary voltage of the transformer has 120Hz ripple unlike the conventional converter for the LED drive. Therefore, the filter capacitor can be minimized and this provides reduced cost, low switching loss, and long life of the converter.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.93-102
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• 2013

This paper proposes an algorithm designed to obtain the optimal solution for transportation problem. The transportation problem could be classified into balanced transportation where supply meets demand, and unbalanced transportation where supply and demand do not converge. The archetypal TSM (Transportation Simplex Method) for this optimal solution firstly converts the unbalanced problem into the balanced problem by adding dummy columns or rows. Then it obtains an initial solution through employment of various methods, including NCM, LCM, VAM, etc. Lastly, it verifies whether or not the initial solution is optimal by employing MODI. The abovementioned algorithm therefore carries out a handful of complicated steps to acquire the optimal solution. The proposed algorithm, on the other hand, skips the conversion stage for unbalanced transportation problem. It does not verify initial solution, either. The suggested algorithm firstly allocates resources so that supply meets demand, in the descending order of its loss cost. Secondly, it optimizes any surplus quantity (the amount by which the initially allocated quantity exceeds demand) in such a way that the loss cost could be minimized Once the above reallocation is terminated, an additional arrangement is carried out by transferring the allocated quantity in columns with the maximum cost to the rows with the minimum transportation cost. Upon application to 2 unbalanced transportation data and 13 balanced transportation data, the proposed algorithm has successfully obtained the optimal solution. Additionally, it generated the optimal solution for 4 data, whose solution the existing methods have failed to obtain. Consequently, the suggested algorithm could be universally applied to the transportation problem.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.11 no.17
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• pp.39-46
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• 1988

This Paper is concerned with a man-multi machine assignment problem to minimize idle time. Assuming different types of semi-automatic machines with deterministic service-processing time, the problem approaches by sequential dependent one operator can handle several machines, where determine optimal range the cost of idle labor and machine time is to be minimized in preparing a work schedule. The Procedure, to establish man-machine assignment model, and it's results are: (1) Objective function to minimize opportunity loss cost, which is happened by idle time, is verified recursive process through heuristic method. (2) The algorithm, is programmed by BASIC language for personal computer, and a numerical example is given to illustrate the heuristic algorithm. This study will be helpful to enhance productivity of Shopflooras a result of increasing the efficiencies of both operator and machine.

• Journal of Power Electronics
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• v.14 no.4
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• pp.621-631
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• 2014

To invigorate the tapped-inductor boost (TIB) topology in emerging high step-up applications for off-grid products, a lossless snubber consisting of two capacitors and three diodes is proposed. Since the switch voltage stress is minimized in the proposed circuit, it is allowed to use a device with a lower cost, higher efficiency, and higher availability. Moreover, since the leakage inductance is fully utilized, no effort to minimize it is required. This allows for a highly productive and cost-effective design of the tapped-inductor. The proposed circuit also shows a high step-up ratio and provides relaxation of the switching loss and diode reverse-recovery. In this paper, the operation is analyzed in detail, the steady-state equation is derived, and the design considerations are discussed. Some experimental results are provided to confirm the validity of the proposed circuit.