• The Korean Journal of Applied Statistics
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• v.8 no.2
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• pp.55-64
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• 1995

Three-level Skip-lot sampling plan split by two stages (Split2-SkSP0 is proposed by modifying multi-level skip-lot sampling plan proposed by Choi(1993), which has normal and terrace inspections on the first and the second stages, respectively. The plan is designed to work more higher level inspections when the quality of the submitted products are good, otherwise, return to the normal or the terrace inspection as fast as possible. Also, the formula of the operating characteristic function for the split skip-lot sampling plan is derived using the Markov chain approach. Also, operating characteristic properties of the proposed plans are studied and graphically compared with those of the multi-level skip-lot sampling plans.

• Journal of the Korean Society of Physical Medicine
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• v.9 no.3
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• pp.301-305
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• 2014

PURPOSE: The purpose of this study was to determine the optimal thresholds of serum lipid level related to hypertension according to age in Korean adults. METHODS: In total, 564 adults who visited the health examine center in general hospital were included. The blood pressure and lipid profiles of low density lipoprotein cholesterol(LDL), high density lipoprotein cholesterol (HDL), triglyceride(TG) were measured. Receiver operating characteristic (ROC) curve were used to establish optimal thresholds between blood pressure and lipid profiles. RESULTS: The optimal TG cutoff value were 110.50(mg/dl) in the 18-39 and 81.50(mg/dl) in the 40-59 age group, and optimal cutoff value of LDL were 126.50(mg/dl) in the 40-59 age group and 111.00(mg/dl) in the 60 and over age group. There was a negative correlation between HDL and hypertension, a higher HDL decreased hypertension. The optimal cutoff value of HDL was 49.50(mg/dl) in the 18-39 age group. CONCLUSION: The thresholds of hypertension were lower in LDL and TG with aging. This result indicated that elderly people needs to concern more about their lipid profiles to maintain healthy cardiovascular function.

• The Korean Journal of Applied Statistics
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• v.33 no.5
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• pp.541-553
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• 2020

The receiver operating characteristic (ROC) curve is expressed as both sensitivity and specificity; in addition, some optimal thresholds using the ROC curve are also represented with both sensitivity and specificity. In addition to the sensitivity and specificity, the expected usefulness function is considered as disease prevalence and usefulness. In particular, partial the area under the ROC curve (AUC) on a certain range should be compared when the AUCs of the crossing ROC curves have similar values. In this study, partial AUCs representing high sensitivity and specificity are proposed by using sensitivity and specificity lines, respectively. Assume various distribution functions with ROC curves that are crossing and AUCs that have the same value. We propose a method to improve the discriminant power of the classification models while comparing the partial AUCs obtained using sensitivity and specificity lines.

• Journal of Integrative Natural Science
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• v.11 no.2
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• pp.76-81
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• 2018

Robust design is an approach to reducing performance variation of quality characteristic values in quality engineering. Product array approach which is used in the Taguchi parameter design has a number of advantages by considering the noise factor. Taguchi has an idea that mean and variation are handled simultaneously to reduce the expected loss in products and processes. Taguchi has used the signal-to-noise ratio (SN) to achieve the appropriate set of operating conditions where variability around target is low in the Taguchi parameter design. Many Statisticians criticize the Taguchi techniques of analysis, particularly those based on the SN. In this paper we propose a substantially simpler optimization procedure for robust design using desirability function without resorting to SN.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.433-440
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• 2007

In this paper a new dynamoelectric winch system is introduced which is widely applied in shipping. building, architecture and so on. Generally in the winch system the squirrel cage induction motor is used as prime mover and line voltage is directly applied to the induction motor during operation. So it is difficult to obtain the smoothing revolution. because of variation of the weight of cargo and system operating method. Based on above reasons, the switched reluctance motor (SRM) is proposed to replace the induction motor because of more reliable mechanical structure, better traction characteristic and higher efficiency compared to induction motor. And in order to solve smoothing revolution problem, instantaneous torque control method based on torque sharing function (TSF) is used. Finally the validity of the proposed method is verified through the simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.4
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• pp.179-187
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• 2001

In recent years, the switching source devices have the advantage of small, light and high reliability with the high-frequency. But, high-frequency switching has disclosed disadvantage of result from stress and turn-on and turn-off peak losses at the switching instant. Accordingly, in this paper propose ZVS-HB type high-frequency resonant DC/DC converter using soft switching technique (Zero-Voltage-Switching, Zero-Current-Switching) with safety operating of circuit at diving on inductive zone, through the circuit design example using the capacitor $C_3,\;C_4$ with soft switching function and division characteristic of resonant Capacitor C, $C_1,\;C_2$, and, the characteristic analysis of circuit is generally described using normalized parameters. Also, this paper certified a rightfulness of characteristic analysis in comparison with a theoretical values and a experimental values obtain from experiment using MOSFET.

• Proceedings of the KIEE Conference
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• 1987.11a
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• pp.343-346
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• 1987

This paper proposes a novel high-frequency resonant DC/DC converter having PWM(Pulse Width Modulation) inverter control function. The operating characteristics of this converter circuit are discussed from a thereotical point of view and compared with experimental results. The results of operating characteristic analysis are given leading to complete designing data.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.934-943
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• 1990

There are no turn-on losses in the series Resonant Converter which operates above the resonance frequency, and the commutation stress on the switched component is low. For a given Series Resonant Converter with specified load resistance, the output voltage is a function of the operation frequency. This paper describes the static and dynamic characteristic analysis of the Series Resonant DC to DC Converter, which is operating above the resonant frequency, with frequency control. For the analysis method, state plane technique is adopted, and the circuit operation is defined from normalized switching frequency, Fsn. Under this condition, circuit performance is analyzed ideally. The validity of the proposed analysis is verified by comparing with experimental results, the stability of the converter is confirmed against small variations around the operating point by conventional frequency domain analysis, and the stress quantity added to switch component is shown.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.82-84
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• 2003

This paper presented a method to develop a relay model by the user-written model function of PSS/E. As for the voltage instability, although generator current limiters, transformer's tap-changers and dynamic loads have been considered as the dominant components, the protection system is also very important because it may influence the system's dynamic behaviour. Hence a distance relay model implemented with the suggested method was added, and then the operating characteristics of the distance relay under the voltage instability condition were investigated.

• Physical Therapy Korea
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• v.23 no.4
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• pp.63-70
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• 2016

Background: The Pediatric Balance Scale (PBS) and the Fullerton Advanced Balance (FAB) scale were used to assess balance function in patients with balance problem. These multidimensional clinical balance scales provide information about potential risk factors for falls. Objects: The purpose of this study was to investigate and compare the predictive properties of the PBS and FAB scales relative to fall risk in children with cerebral palsy (CP) using a receiver operating characteristic analysis. Methods: In total, 49 children with CP (boy=21, girl=28) who were diagnosed with level 1 or 2 according to the Gross Motor Function Classification System participated in this study. The PBS and FAB were performed, and verified cut-off score, sensitivity, specificity, and the area of under the curve (AUC). Results: In this study, the PBS scale was as a predictive measure of fall risk, but the FAB was not significant in children with CP. A cut-off score of 45.5 points provided optimal sensitivity of .90 and specificity of .69 on the PBS, and a cut-off score of 21.5 points provided optimal sensitivity of .90 and specificity of .62 on the FAB. Both scales showed moderately accurate of AUC with .79 and .76, respectively. Conclusion: The PBS is a useful screening tool for predicting fall risk in children with cerebral palsy, and those who score 45.5 or lower indicate a high risk for falls and are in need of balance intervention.