• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.1
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• pp.58-61
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• 2003

A loop power system has a nonlinear characteristics. Also it is very hard to analyse through a equation if a discontinuous characteristic of the ULTC is added to a system. However, the problem which is hard to analyse by equations can acquire the useful result with what use the genetic algorithm (GA) which is a multi-point search program. In this paper, we proved through a simulation that the proposed method can reduce an operation frequency of tap changers and improving the quality of voltage of the buses by decreasing the deviation between the actual voltage and the reference voltage through the coordinated control of the ULTC that use GA in the loop power system.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.92-101
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• 2000

The objective of this paper is to design the controller for longitudinal vehicle following which makes the vehicle follow the lead vehicle and keeps a safety distance without human driver operation. This paper presents a sliding mode control algorithm for the ACC system. The controller is based on three sliding surfaces. Each surface plays an individual control-deviation control, throttle control and brake control. In addition to sliding mode control, we propose some additional schemes to enhance controller performance. The first one is a gear shift-down controller which makes tractive force increase with a change of gear ratio. The other is a predictive correction method which reduces slinky effect.

• International Journal of Quality Innovation
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• v.4 no.2
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• pp.50-64
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• 2003

During IC inspection, which includes the two parts of Mark and Lead, the deviation of IC on the tape occurring in high speed movements usually generates light reflection effect, which in turn causes errors in IC recognition as measured by machine vision system. This research filters the light reflection effect by developing standard components, identifies the correct position of IC Lead, hence fixes the measurement errors or non-measurability caused by light reflection, avoids the resulting discontinued operation of measuring system, and improves the productivity.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.3
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• pp.279-287
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• 2005

In this study, I suggest an effective operation of waterwork facilities in large cities and a scientific method for utilizing water in water distribution systems. To achieve this goal, my simulation were carried out on data from Kwangju City using Pipenet '98, a pipe-network program. From this simulation, I examine the possibilities of application the system in large cities, comparing data measured at 33 hydraulic pressure monitoring places from waterwork enterprises. The result is coincident with that of waterwork enterprises, with about a 12.5% average error rate and $0.32kg/cm^2$ average deviation. The method and program I use here can be helpful in cities where there is a need to extend the waterwork facilities, or where there is a need to suspend the water supply, and/or there is an accident. The simulation shows how to expand waterwork facilities effectively, how to prevent accidents, and how to estimate the hydraulic pressure even in the areas without monitoring places.

• Nuclear Engineering and Technology
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• v.53 no.8
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• pp.2610-2615
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• 2021

The prediction of irradiation-induced transition temperature shift for RPV steels is an important method for long term operation of nuclear power plant. Based on the irradiation embrittlement data, an irradiation-induced transition temperature shift prediction model is developed with machine learning method XGBoost. Then the residual, standard deviation and predicted value vs. measured value analysis are conducted to analyze the accuracy of this model. At last, Cu content threshold and saturation values analysis, temperature dependence, Ni/Cu dependence and flux effect are given to verify the reliability. Those results show that the prediction model developed with XGBoost has high accuracy for predicting the irradiation embrittlement trend of RPV steel. The prediction results are consistent with the current understanding of RPV embrittlement mechanism.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.38-43
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• 1996

Windowing routines have as their purpose the reduction of the sidelobes of a spectral output of the FFT or DFT routines. Windowing routines accomplish this by forcing the beginning and end of any sequence to approach each other in value. Since they must work with any sequence they force the beginning and ending samples near zero. To make up for this reduction in power, windowing routines give extra weight to the values near the middle of the sequence. The difference between windows is the way in which they transition from the low weights near the edges to the higher weights neqr the middle of the sequence. Signal-to-noise ratio(SNR) can be determined by the ratio of the output noisy signal variance to the input noisy signal variance of a window. Standard deviation of noise is reduced by windowing. Thus, the windowing operation improved the SNR of the noisy signal. This paper shows a performance estimation of windowing on a single tone with added Gaussian noise and uniform noise.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.32 no.2
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• pp.1-10
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• 2024

Gimpo International Airport is only available for alternate airport for code F aircraft and it is difficult to operate larger aircraft capable of transporting more passengers than B747-400. This study has conducted to review the compatibility based on risk assessment to introduce the B747-8 operation procedures, excluding the A380 for practical reasons. Risk factors for main gear deviation when driving on curved sections of the taxiway was identified. The risk was analyzed as "high" level. As a risk reduction measure, the proceduralization of specific taxiing method "judgemental oversteer" was reviewed, and the result of the risk re-evaluation was lowered to a "low" level. As a result, the B747-8 was analyzed to be compatible. Additionally, It is suggested that review of pavement strength, de/anti-icing facilities, and passenger boarding bridge is necessary for actual operations.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.149-154
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• 2005

Fuel cell performance evaluation logic was developed using G-language (LabVIEW) to measure performance stability. Degree of stability and reliability of performance data were improved with averaged value and standard deviation method. Water injection system was introduced and the performance using this method was comparable to that of conventional humidification method. Water injection system has advantage of lowering operation energy consumption, reducing the number of parts needed in humidification, therefore increasing efficiency of fuel cell system. Fuel cell performance was decreased in case of low temperature operation such as sub freezing condition. Air purge method was tested to reduce the water content in cell fixture before sub freezing condition. The performance degradation due to low temperature operation was minimized by air purge method in medium size cell fixture ($25cm^2$) case.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.4
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• pp.1765-1773
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• 2013

The purpose of this study was to contribute to the medical treatment of subdural effusion through clinical sequence analysis of patients who experienced improvement of subdural drainage and had a second operation for subdural drainage or subduroperitoneal shunt. Sixteen cases of the whole patients who have been underwent subdural effusion and subdural drainage were analyzed during the period from 2006 July to 2012 June. The study gave us a result that all of patients, who was taking aspirin, have been under the second operation(p<0.001) and these group have had a subduraoperitoneal shunt(p=0.014)). According to the comparative analysis for the patients group that divided into two; one had subduroperitoneal shunt and the other had no subduroperitoneal shunt, the outcomes of this study were shown as follows. First, their median line deviation was serious in their brain CT. In addition, their subdural effusion increased or did not change with a headache, vomiting, fever and dyspnea. As a result of those symptoms. subduraoperitoneal shunt was carried out(p=0.006). The surgical method for patients who were taken asprin must be cautiously selected and the prevention of sudden disappearance of cerebrospinal fluid and excessive change of intracranial pressure is very important in operation craniectomy.

• The Korean Journal of Rehabilitation Nursing
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• v.6 no.2
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• pp.239-247
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• 2003

Purpose: The purpose of this study is to examine how well patients who had hip arthroplasty comply with medical regimens given to them after the operation. Method: The subjects of the study were patients who had arthroplasty at P Hospital between April 1, 2001 and August 30, 2002. 20 patients of the subjects experienced complications after the operation and the other 20 did not. Data from a survey using the qustionnaire were statistically analyzed in terms of real number, percentage point, mean and standard deviation by using $X^2$-test, t-test and ANOVA. Result: 1) the surveyed patients were significantly different in the compliance of medical regimen among them according to their education background as one of the subjects general characteristics. 2) It was found that the group of complication was higher in the compliance of medical regimen than that of non-complication. The two groups showed statistically significant difference with each other in the degree of compliance with therapeutic instructions than the experimental group in terms of the maintenance of abduction after the operation, training instructions on step-by-step basis, urination cotrol on bed, accurate use of crutch, compliance with medication, balance among medical treatment, training, leisure, rest and nutrition, instructions by physicians, nurses and physical therapists, use of low armchairs and toilet bowels and no bending of the body forward, and use of a non-operated leg in case of go upstairs or downstairs. Conclusion: It seems necessary to develop systematic and sessional education programs for improving the compliance of medical regimen, ultimately reducing complications following hip arthroplasty.