• 대한전기학회논문지:시스템및제어부문D
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• 제51권11호
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• pp.483-493
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• 2002

The damping ratio ${\xi}$ of the unit-step response of a second-order discrete system is a function of only the location of the closed-loop poles and is not directly related to the location of the system zero. However, the peak overshoot of the response is the function of both the damping ratio ${\xi}$ and an angle ${\alpha}$, which is the phasor angle of the damped sinusoidal response and is determined by the relative location of the zero with respect to the closed-loop poles. Therefore, if the zero and the open-loop poles are relatively adjusted, through pole-zero cancellation, to maintain the desired (or designed) closed-loop poles, the damping ratio ${\xi}$ will also be maintained, while the angle ${\alpha}$ changes. Accordingly, when the closed-loop system poles are fixed, the peak overshoot is considered as a function of the angle ${\alpha}$ or the system zero location. In this paper the effects of the relative location of the zero on the system performance of a second-order discrete system is studied, and a design method of digital compensator which achieves a minimum peak overshoot while maintaining the desired system mode and the damping ratio of the unit step response is presented.

• 한국의류학회지
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• 제22권6호
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• pp.737-748
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• 1998

This study was carried out on 132 obese women who satisfied both of conditions for obesity: equal to or over 1.6 in Rohrer index and 90 in bust girth. The purpose of the study was to set up a sizing system using the loss function which would be a guide for obese women to select ready-to-wear of suitable size. The results were as follows. 1) In the sizing system for large size apparel industry, each company has 4 to 7 sizes that differ in their content and number. Producing only 5 sizes was trying to minimize the producti on expenses. 2) The sizing system according to the loss function was the follwings. The height was 3: 149, 154.5 and 161 cm. The bust girth was 5:96.5, 100.5, 104, 107.5, 112 cm. The hip girth was 5: 95, 99, 102.5, 105.5, 110 cm. 3) In comparing the cover ratio of the newly suggested sizing system for obese women's garment with that of the Korea Sizing system for women's garment, the former was founded to have the greater cover ratio.

• Physical Therapy Rehabilitation Science
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• 제12권2호
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• pp.201-205
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• 2023

Objective: Resistance exercise is a necessary element to improve quality of life, and measurement and evaluation of muscle strength provide important information for prescription and management of rehabilitation and exercise programs. This study analyzed the correlation between direct and indirect 1RM for isokinetic maximum torque of the knee joint in order to provide useful information in the field of exercise programs. In addition, the flexion-extension ratio and the difference in left-right deviation were verified. Design: A cross-sectional study Methods: The subjects of this study were 33 healthy adult men and women without medical problems who participated in the health exercise class program at S University in Seoul. The correlation between isokinetic maximum torque and direct and indirect 1RM was analyzed, and a dependent t-test was performed to analyze the flexion-extension ratio and left-right deviation. Results: There was a high correlation between the isokinetic maximum torque and direct and indirect 1RM, and no statistically significant difference was shown between the test methods in the analysis of the flexion-extension ratio and left-right deviation. Conclusions: Isokinetic muscle function measuring equipment is expensive, so it is difficult to use it in local exercise rehabilitation and training sites. Through this study, it was found that direct and indirect 1RM isokinetic maximum torque showed a high correlation, and there was no difference in evaluating muscle function such as flexion-extension ratio and left-right deviation. Therefore, it is considered that the muscle function evaluation using 1RM in general field can be usefully utilized.

• Journal of Chest Surgery
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• 제25권11호
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• pp.1169-1179
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• 1992

To determine the period and degree of full recovery of postoperative pulmonary function, the author performed seiral pulmonry function test with spirometry at preoperative period and 1st, 2nd, 3rd, 4th, 6th and 8th postoperative week in 64 patients who underwent chest surgery form 1990. 1. to 1990. 8. at Dep. of Thoracic & Cardiovascular surgery, Pusan National University Hospitcal, Pusan, Korea 28 patients underwent lung resection[Group A], 14 patients mediastinal and other thoracic surgery[Group B], and 22 patients heart surgery with cardiopulmonary bypass[Group C]. Al of them recovered normally and discharged without any complications. Their serial changes of pulmonary function test were compaired and its results was as follows; l. Over all mean recovery time of restrictive ventilatory function tests[ie, VC, ERV, IC, FEF1, FVC, FEF200-1200, MVV] were 4th & 6th postoperative week, and that of obstructive ventilatory function tests[ie., EFE25-75%, Vmax50] were 2nd postoperative week. 2. In patient who underwent lung resection surgery[Group A], FEF1 recovered in 4th~6th postoperative week and its ratio to preoperative value was 70% in pneumonectomy, and 75% in lobectomy. FVC recovered in 4th~6th postoperative week and its ratio to preoperative value was 65% in pneumonectomy, and 80% in lobectomy. MVV was recovered in 4th~8th postoperative week and recovery ratio was 80%, FEF200-1200 was recovered at 4th~6th postoperative week and its recovery ratio was 70%, FEF25-75% and Vmax50 was recovered in 2nd~4th postoperative week and recovered nearly to preoperative level. 3. In patient who underwent mediastinal and other thoracic surgery[Group B], FEV1 and FVC and recovered in 4th~6th postoperative week and the recovery ratio of FVC in blebectomy was 90%. MVV reached preoperative level in 4th~8th postoperative week. FEF200-1200, FEF25-75% and Vmax50 were recovered in 2nd~4th postoperative week and the recovery of FEF25-75% and Vmax50 in blebectomy was prominant. 4. In patient who underwent heart surgery[Group C], FEV1 and FVC were recovered in 4th~6th postoperative week. The recover ratio of FEF25-75% and Vmax50 was delaied to 6th~8th postoperative week From the above results we concluded that the recovery time of posoperative restrictive ventilatory disorder was 4th postoperative week and pulmonary complication would possibly occure during that period. So more intensive observations will be needed.

• 대한예방한의학회지
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• 제14권2호
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• pp.105-120
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• 2010

Objectives : This study aims to evaluate the effects of expiration-to-inspiration time ratio (E/I-ratio) on heart rate, which represents cardiac autonomic function, and cold-heat in the healthy people. Methods : 49 healthy young volunteers(male : female = 32 : 17) were recruited in the study. The participants completed the questionnaire for yin-yang pattern identification and then we measured the chest plethysmogram for respiration signal and the electrocardiogram for NN intervals during different E/I-ratio from 1 to 2. We compared heart rate variability including RMS-SD, VLF, LF and HF, and the trend-cycle factors decomposed from NN interval data by time series analysis among the respective E/I-ratio. We also confirmed the difference on the trend-cycle factors according to the score of the questionnaire for cold and heat pattern identification. Results : There were differences on the trend-cycle factors from NN interval data, but no significant difference on heart rate variability, among the respective E/I-ratio. We also found significant relationship between the trend-cycle factors and the heat pattern identification scores. Conclusions : The results indicate that cardiac autonomic function can be modulated by the E/I-ratio and the modulation will be slower and more tendencious than respiratory sinus arrhythmia.

• Communications for Statistical Applications and Methods
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• 제31권1호
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• pp.65-85
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• 2024

The tail probability of a function of a multivariate random variable is not easy to estimate by the crude Monte Carlo simulation. When the occurrence of the function value over a threshold is rare, the accurate estimation of the corresponding probability requires a huge number of samples. When the explicit form of the cumulative distribution function of each component of the variable is known, the inverse transform likelihood ratio method is directly applicable scheme to estimate the tail probability efficiently. The method is a type of the importance sampling and its efficiency depends on the selection of the importance sampling distribution. When the cumulative distribution of the multivariate random variable is represented by a copula and its marginal distributions, we develop an iterative algorithm to find the optimal importance sampling distribution, and show the convergence of the algorithm. The performance of the proposed scheme is compared with the crude Monte Carlo simulation numerically.

• 대한가정학회지
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• 제40권3호
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• pp.83-97
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• 2002

This study estimates the consumption needs of preretired households through target replacement ratio approach. Based on the Life Cycle Model, this study used the household expenditure function to derive the target replacement ratio appropriate for each household. The target replacement ratio is estimated using the 1996 National Survey of family Income and Expenditure by National Statistical Office. The estimated target replacement ratio was 82.4% for married couple households, and 85.1% for single households. Total retirement consumption needs during entire retirement period was 161,620,000 won for married couple households, and 50,532,039 won for single households.

• 보건의료산업학회지
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• 제4권1호
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• pp.87-97
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• 2010

The study analyzed the cash flow and external funding in focusing on the relationship of the two factors in Korean hospitals and some changes in the relationship. The results analyzing this study were summarized as follows: First, the discriminant function of new external funds was generally the ratio of cash flow from operating activities to sales, the ratio of cash flow from investment activities to sales, the ratio of cash flow from financing activities to sales in order. The prediction rate of total discriminant function was more than 92%. Second, in case of Korean hospitals, it was known that the ratio of cash flow from operating activities to sales, particularly the net income to sales was the biggest influencing factor on the decision to external funding.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.735-740
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• 2003

In this study, a numerical optimization to find the optimal shape of streamwise periodic ribs mounted on both of the principal walls is performed to enhance turbulent heat transfer in a rectangular channel. The optimization is based on Navier-Stokes analysis of flow and heat transfer with $k-{\varepsilon}$ turbulence model and is implemented using response surface method. The width-to-height ratio of a rib, rib height-to-channel height ratio, rib pitch to rib height ratio and distance between opposite ribs to rib height ratio are chosen as design variables. The object function is defined as a function of heat transfer coefficient and friction drag coefficient with weighting factor. Optimum shapes of the rib have been investigated for the range of 0.0 to 0.1 of weighting factor.

• 한국전산구조공학회논문집
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• 제23권6호
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• pp.727-737
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• 2010

Together with the Young's modulus the Poisson's ratio is another independent material parameter that governs the behavior of a structural system. Therefore, it is meaningful to evaluate separately the influence of the parameter on the random response of the structural system. To this end, a formulation dealing with the spatial randomness in the Poisson's ratio in laminated composite plates is proposed. The main idea of the paper is to transform the fraction form of the constitutive coefficients into the expanded form in an ascending order of the stochastic field function. To validate the adequacy of the formulation, a square plate is chosen and the computation results are compared with those obtained using conventional Monte Carlo simulation. It is observed that the results show good agreement with those by the Monte Carlo simulation(MCS).