• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.21 no.1
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• pp.175-182
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• 2023

APro, a modularized process-based total system performance assessment framework, was developed at the Korea Atomic Energy Research Institute (KAERI) to simulate radionuclide transport considering coupled thermal-hydraulic-mechanical-chemical processes occurring in a geological disposal system. For reactive transport simulation considering geochemical reactions, COMSOL and PHREEQC are coupled with MATLAB in APro using an operator splitting scheme. Conventionally, coupling is performed within a MATLAB interface so that COMSOL stops the calculation to deliver the solution to PHREEQC and restarts to continue the simulation after receiving the solution from PHREEQC at every time step. This is inefficient when the solution is frequently interchanged because restarting the simulation in COMSOL requires an unnecessary setup process. To overcome this issue, a coupling scheme that calls PHREEQC inside COMSOL was developed. In this technique, PHREEQC is called through the "MATLAB function" feature, and PHREEQC results are updated using the COMSOL "Pointwise Constraint" feature. For the one-dimensional advection-reaction-dispersion problem, the proposed coupling technique was verified by comparison with the conventional coupling technique, and it improved the computation time for all test cases. Specifically, the more frequent the link between COMSOL and PHREEQC, the more pronounced was the performance improvement using the proposed technique.

• Journal of Mechanical Science and Technology
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• v.17 no.4
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• pp.571-580
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• 2003

Tomography has been investigated to observe bubble behaviors in two-phase flows. A bubbly flow and an annular flow have been reconstructed by tomography methods such as an algebraic reconstruction technique (ART) and a multiplicative algebraic reconstruction technique (MART) . Computer synthesized phantom fields have been used to calculate asymmetric density distributions for limited cases of 3, 5, and 7 projection angles. As a result of comparison of two tomography methods, the MART method has shown a significant improvement in the reconstruction accuracy for analysis of the two-phase flows.

• Transactions on Electrical and Electronic Materials
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• v.17 no.3
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• pp.134-138
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• 2016

The fullerene solar cells are becoming a feasible choice due to the advanced developments in donor materials and improved fabrication techniques of devices. Recently, sufficient optimization and improvements in the processing techniques like incorporation of solvent vapor annealing (SVA) with additives in solvents has become a major cause of prominent improvements in the performance of organic solar cell-based devices . On the other hand, the challenge of reduced open circuit voltage (V_oc) remains. This study presents an approach for significant performance improvement of overall device based on organic small molecular solar cells (SMSCs) by following a two step technique that comprises thermal annealing (TA) and SVA (abbreviated as SVA+TA). In case of exclusive use of SVA, reduction in V_oc can be eliminated in an effective way. The characteristics of charge carriers can be determined by the measurement of transient photo-voltage (TPV) and transient photo-current (TPC) that determines the scope for improvement in the performance of device by two step annealing. The recovery of reduced V_oc is linked with the necessary change in the dynamics of charge that lead to increased overall performance of device. Moreover, SVA and TA complement each other; therefore, two step annealing technique is an appropriate way to simultaneously improve the parameters such as V_oc, fill factor (FF), short circuit current density (J_sc) and PCE of small molecular solar cells.

• ETRI Journal
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• v.36 no.2
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• pp.188-196
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• 2014

This paper describes a simple delay diversity technique for terrestrial digital multimedia broadcasting (T-DMB) and digital audio broadcasting in a single-frequency network (SFN). For the diversity technique, a delay diversity scheme is adopted. In the delay diversity scheme, a non-delayed signal is transmitted in the first antenna, and delayed versions of the signal are transmitted in each additional antenna. For an SFN environment with multiple transmitters, delay diversity can be executed by controlling the emission times of the transmitters. This SFN delay diversity scheme does not require any hardware changes in either the transmitter or receiver, and perfect backward compatibility can be acquired. To evaluate the performance improvement, laboratory tests are executed with various types of commercial T-DMB receivers as well as a measurement receiver. The improvement in the bit error rate performance is evaluated using a measurement receiver, and an improvement of the threshold of visibility value is evaluated for commercial receivers. Test results show that the T-DMB system can obtain diversity gain using the described technique.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.11a
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• pp.31-37
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• 2006

The objective of this research is to select the most effective technique from task related techniques(motion & time study, job redesign, physical environment improvement) for improving work efficiency in shipbuilding enterprise. This study consists of several principal steps. The first step is to design critical criteria in evaluating work efficiency in shipbuilding enterprises. The second step is to develop sub-criteria of the critical criteria. The third step is to develop a four level AHP(Analytic Hierarchy Process)structure using the critical criteria, sub-criteria and techniques from task related techniques. The fourth step is to develop the pairwise comparison matrix by each level of AHP structure, which was based on survey data collected at the H heavy industry. And the last step is to select the most effective technique from task related techniques using AHP analysis. The result of AHP analysis has shown clear difference in priority among task related techniques in terms of work efficiency of the shipbuilding enterprise: The reduction of normal time has more importance than the reduction of allowance time, motion & time study techniques are most important for the reduction of normal time, physical environment improvement is most important for the reduction of allowance time as well.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.792-793
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• 2005

Circuit testing process is very important in IC Manufacturing there are two ways in research for circuit testing improvement. These are ATPG Tool Design and Test simulation application. We are interested in how to use parallel technique such as one-side communication, parallel IO and dynamic Process with data partition for circuit testing improvement and we use one-side communication technique in this paper. The parallel ATPG Tool can reduce the test pattern sets of the circuit that is designed in laboratory for make sure that the fault is not occur. After that, we use result for parallel circuit test simulation to find fault between designed circuit and tested circuit. From the experiment, We use less execution time than non-parallel Process. And we can set more parameter for less test size. Previous experiment we can't do it because some parameter will affect much waste time. But in the research, if we use the best ATPG Tool can optimize to least test sets and parallel circuit testing application will not work. Because there are too little test set for circuit testing application. In this paper we use a standard sequential circuit of ISCAS89.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.2
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• pp.132-139
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• 2009

Yield is a very important measure that can expresses simply for productivity and performance of company. So, yield is used widely in many industries nowadays. With the development of the information technology and online based real-time process monitoring technology, many industries operate the production lines that are developed into automation system. In these production lines, the product structures are very complexity and variety. So, there are many multi-variate processes that need to be monitored with many quality characteristics and associated process variables at the same time. These situations have made it possible to obtain super-large manufacturing process data sets. However, there are many difficulties with finding the cause of process variation or useful information in the high capacity database. In order to solve this problem, neural networks technique is a favorite technique that predicts the yield of process for process control. This paper uses a neural networks technique for improvement and maintenance of yield in manufacturing process. The purpose of this paper is to model the prediction of a sub process that has much effect to improve yields in total manufacturing process and the prediction of adjustment values of this sub process. These informations feedback into the process and the process is adjusted. Also, we show that the proposed model is useful to the manufacturing process through the case study.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.615-619
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• 2021

This study focuses on memory systems that are optimized to increase performance and energy efficiency in many embedded systems such as IoT, cloud computing, and edge computing, and proposes a performance improvement technique. The proposed technique improves memory system performance based on machine learning algorithms that are widely used in many applications. The machine learning technique can be used for various applications through supervised learning, and can be applied to a data classification task used in improving memory system performance. Data classification based on highly accurate machine learning techniques enables data to be appropriately arranged according to data usage patterns, thereby improving overall system performance.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.1
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• pp.55-64
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• 2004

Conventional bipolar surface electromyography(EMG) technique detects only the superimposed electromyographic activity of a large number of motor units due to its low spatial resolution. For the diagnosis of neuromuscular disorder, the information of single MU is required. In this paper, 9 channel array surface electrode system was as designed and MLoG filter was proposed. Also the MCPT(modified convolution processing technique)method was proposed for the improvement of MUAP resolution. For performance evaluation, power spectrum analysis of random data and raw EMG signal comparison of MUAP shape and quantitative estimation of SNR were executed. As a result, the MUAP resolution improvement of 32％ was obtained from the standpoint of the signal-to-noise ratio(SNR).

• Journal of the korean academy of Pediatric Dentistry
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• v.21 no.2
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• pp.593-598
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• 1994

There were two cases of esthetic improvement of discolored teeth. First case was 12-year-old girl whose upper right central incisor was discolored after traumatic injury. She was treated by walking bleaching technique. Endodontic retreatment was done, and then the mixture of Superoxol and sodium perborate was applied and changed every week. After 3 weeks, esthetic result was obtained and fracture site was rcovered with light-curing composite resin. Second cases was 11-year-old girl whose teeth were discolored by fluorosis. She was treated by vital bleaching technique. A resin splint was made and then 30% and 15% carbamide peroxide was applied using this splint. After 4 weeks, a noticeable improvement in the color and the brightness of the teeth was achieved.