• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.291-298
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• 2001

It is very difficult to accomplish load tests of piles with large diameter constructed on the offshore area, because of requirement for large scaled loading equipment and bad testing conditions. Therefore, so far in many cases pile driving dynamic formulas have applied to quality control, and recently dynamic load test method is widely used for confirming bearing capacities of such piles. However, in cases of piles with very large diameter about 2,500mm, it is nearly impossible for regular type load test methods of piles such as static and dynamic to apply owing to very large design load. This is case studies of load tests such as modified static and dynamic load tests of piles and point load tests of rock samples for estimating rational allowable bearing capacity of very large diameter piles constructed on the marine area.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.495-505
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• 2008

This paper describes modeling Voltage Sourced Inverter (VSI) type Flexible AC Transmission System (FACTS) controllers and control methods for power system dynamic stability studies. The considered FACTS controllers are the Static Compensator (STATCOM), the Static Synchronous Series Compensator (SSSC), and the Unified Power Flow Controller (UPFC). In this paper, these FACTS controllers are derived in the current injection model, and it is applied to the linear and nonlinear analysis algorithm for power system dynamics studies. The parameters of the FACTS controllers are set to damp the inter-area oscillations, and the supplementary damping controllers and its control schemes are proposed to increase damping abilities of the FACTS controllers. For these works, the linear analysis for each FACTS controller with or without damping controller is executed, and the dynamic characteristics of each FACTS controller are analyzed. The results are verified by the nonlinear analysis using the time-domain simulation.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1979.05a
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• pp.4.2-4
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• 1979

Since Metz had employed the impedance audiometry in 1946, scholars have carried out many investigation. Brook, Jeger, Cooper reported and evaluated the clinical studies of impedance audiometry and its screening test. Recently, in Korea, a studies of impedance audiometry have been reported. We analysed 100 children aged between 7-16 years old who visited OPD of E.N.T. department with the complaints of the nasal obstruction and hard of hearing from Nov. 77-Feb. 79. Through the use of otoscope and impedance audiometry, we evaluated the types of tympanogram, static compliance and the acoustic reflex. This paper is dealing with the statistical study of impedance audiometric result and its literature.

• Korean Journal of Child Studies
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• v.16 no.2
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• pp.113-124
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• 1995

The objective of this study was to clarify the relations among mothers' self-esteem and facilitative communication, to children's self-esteem, and facilitative communication and then to inquire into how these relationships relatively contribute to children's self-esteem. Subjects were 206 elementary school children and their mothers in Anjang. Two types of instruments were used in this study. To measure the children's and mothers' self-esteem, SEI(Self-Esteem Inventory) was to used. To measure mothers' facilitative communication levels, "Mothers' Facilitative Communication Scales" was constructed by the researcher. The statistical procedures used for collected data analyses were correlation, one-way ANOVA, multiful regression. The findings are as following: 1. A significant static correlation was found between mothers' self-esteem and children's self-esteem. 2. Also, a significant static correlation was revealed between mothers' facilitative communication level and children's self-esteem. 3. The level of mothers' facilitative communication discloses a significant difference depending upon the mothers' self-esteem. 4. Mothers' level of facilitative communication affected children's self-esteem rather than the mothers' self-esteem.

• Safety and Health at Work
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• v.2 no.3
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• pp.236-242
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• 2011

Objectives: To determine the feasibility of predicting static and dynamic peak back-compressive forces based on (1) static back compressive force values at the lift origin and destination and (2) lifting speed. Methods: Ten male subjects performed symmetric mid-sagittal floor-to-shoulder, floor-to-waist, and waist-to-shoulder lifts at three different speeds (slow, medium, and fast), and with two different loads (light and heavy). Two-dimensional kinematics and kinetics were captured. Linear regression analyses were used to develop prediction equations, the amount of predictability, and significance for static and dynamic peak back-compressive forces based on a static origin and destination average (SODA) backcompressive force. Results: Static and dynamic peak back-compressive forces were highly predicted by the SODA, with R2 values ranging from 0.830 to 0.947. Slopes were significantly different between slow and fast lifting speeds (p < 0.05) for the dynamic peak prediction equations. The slope of the regression line for static prediction was significantly greater than one with a significant positive intercept value. Conclusion: SODA under-predict both static and dynamic peak back-compressive force values. Peak values are highly predictable and could be readily determined using back-compressive force assessments at the origin and destination of a lifting task. This could be valuable for enhancing job design and analysis in the workplace and for large-scale studies where a full analysis of each lifting task is not feasible.

• Physical Therapy Korea
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• v.26 no.4
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• pp.63-69
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• 2019

Background: Both the rapid concentric and eccentric contractions during exercise repeatedly impose excessive stress on muscle tissue. The hamstring muscles are very susceptible to injury due to the tensile stress. Various interventions are currently being undertaken to prevent strain injury before exercise. Stretching is the most common method and is known to have a positive effect on flexibility and muscle performance. However, relatively few studies have investigated the potential negative factors of stretching. Objects: The purpose of this study was to examine changes in pain following the different intensity of the stretching and types of physical stress. Methods: The subjects were divided into three groups based on the intensity of stretching: 100% (S100), 75% (S75), and 50% (S50) of the measured force at the point of discomfort in static stretching and 100% (P100), 75% (P75), and 50% (P50) of the maximum voluntary isometric contraction in Proprioceptive Neuromuscular Facilitation (PNF) stretching. The pain individual subjects perceived after stretching was measured via a Visual Analog Scale (VAS) and compared between the groups Results: Despite the decrease in the intensity of static stretching, no decrease in VAS value was observed. In PNF stretching, a significant decrease was observed at P50 compared to P100. S100 was significantly higher than P75 and P50. Conclusion: Previous studies have shown that PNF has a superior or the same effect on flexibility in comparison with static stretching. This effect was maintained even in moderate intensity. PNF stretching performed under moderate rather than high intensive static stretching, which causes pain and discomfort, might be recommended in clinical settings.

• Transactions of The Korea Fluid Power Systems Society
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• v.8 no.4
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• pp.9-16
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• 2011

Because of the increasing demand on the high precision and high response of a machinery, proportional control valves are widely adopted at various application fields. This paper studies on the static and dynamic characteristics of a pilot proportional pressure control valve. An experimental apparatus including hydraulic pump, variable speed inverter, pressure and flow sensors and data aquisition system was set up. And various experiments such as P-Q-V curves, step responses due to input voltage and flow rate, hysteresis, frequency response of the proportional valve was carried out and the results are discussed.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.604-609
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• 2001

In the sheet metal forming process, the drawbead is used to control the flow of material during the forming process. The drawbead provides proper restraining force to the material and prevents defects such as wrinkling or breakage. For these reasons, many studies for designing the effective drawbead have been conducted. For the analysis, the numerical method called the static-explicit finite element method was used. The finite element analysis code for this method has been developed and applied to the drawbead process problems. In result, convergence problem and computation time due to large non-linearity in the existing numerical analysis methods were no longer a critical problem. Futhermore, this approach could treat the contact friction problem easily by applying very small time intervals. It is expected that various results from the numerical analysis will give very useful information for the design of tools in sheet metal forming process.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.193-200
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• 2000

In the sheet metal forming process, the drawbead is used to control the flow of material during the forming process. The drawbead provides proper restraining force to the material and prevents defects such as wrinkling or breakage. For these reasons, many studies for designing the effective drawbead have been conducted. In this paper, the influence of the number of drawbead during the blank forming process will be introduced. For the analysis, the numerical method called the static-explicit finite element method was used. The finite element analysis code for this method has been developed and applied to the drawbead process problems. It is expected that this static-explicit finite element method could overcome heavy computation time and convergence problem due to the increase of drawbeads.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.4
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• pp.149-158
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• 2018

With the propagation and spread of the new regeneration energy and increase in electricity demand, power systems tend to be decentralized, and accordingly, the use of a power system stabilizer tends to expand for the stabilization of the distribution system. Thus, typical power system stabilizer, Static Var Compensator (SVC) is developed on a variety of topologies. In addition, the trend of technology leads from SVC to Static Synchronous Compensator(STATCOM) technology development. Recently, to overcome STATCOM's conversion losses and economic disadvantages, studies of a hybrid method using STATCOM and SVC in parallel have actively been conducted. This study proposes a new Soft-Step Switching method to limit inrush current problematic in Thyristor Controlled Capacitor (TCC) method in SVC function. In addition, to reduce Statcom's capacity, groups of reactive power compensation reactor and condenser for SVC were designed.