• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.67-75
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• 2008

This research is to develop the steel-concrete composite lining board using section shape steel. This lining board adopts section shape steel, rectangular pipe and H-beam, instead of roll-formed steel member commonly used in other composite lining board. Consequently, it reduces fabrication effort. Efficient section which can reduce the weight of steel of the lining board is made by placing the neutral axis of the section near the lower surface of concrete. Behavior of composite section is improved by adding bolts as shear connector. Static and fatigue tests were conducted to verify the performance of the composite lining board developed. The test results indicate that serviceability as well as safety of the lining board developed is secured with good margin and reduction of steel weight can be made about 27% compared with other composite lining boards.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.3
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• pp.218-224
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• 2007

Although piezoelectric materials such as PZT have been widely used as actuators in the field of active vibration suppression, the use of bare PZT as an actuator may cause some drawbacks such as critical breaks in the installation process, short circuits in the host material and low fatigue performance. The LIPCA-C2 (lightweight piezocomposite actuator) was developed to alleviate these problems. We implemented the LIPCA as an actuator to suppress the vibration of an aluminum cantilever beam with a tip mass. In our test, we used positive position feedback control algorithm. The filter frequency for this type of feedback should be tuned to the natural frequency of the target mode. The first three experimental natural frequencies of the aluminum cantilever beam agree well with the results of finite element analysis. The effectiveness of using the LIPCA as an actuator in active vibration suppression was investigated with respect to the time and frequency domains, and the experimental results show that LIPCAs with PPF control can significantly reduce the amplitude of forced vibrations and the settling time of free vibrations. For a case study, the forced vibration control of several beams with different thicknesses were performed.

• Journal of Digital Convergence
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• v.14 no.6
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• pp.431-438
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• 2016

This study will be targeting 21-24 years old college students majoring in physical education. This study covers the effect of kinesiology taping and icing treatment on the recovery rate of blood lactate concentration, and cardiovascular function so that it can provide the basic data for improving physical performance. As a result of this study, Kinesio taping and icing aid the recovery rate of the maximum load of lactic acid recovery rate and 30 minutes after exercise heart rate after exercise, but increased, after 15 minutes, immediately after exercise heart rate, exercise lactate and heart rate, and 30 minutes after exercise lactate showed no difference. In conclusion, Kinesio taping and icing treatment, reduce pain and fatigue but it is not satisfactory. Further study, applying a more accurate and technical form of exercise programs needs to continuously research the effects of Kinesio taping and icing treatment

• Journal of Korea Multimedia Society
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• v.16 no.1
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• pp.42-49
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• 2013

The camera motion is accompanied with the translation and/or the rotation of objects in frames of a video sequence. An unnecessary rotation of objects declines the quality of the moving pictures and in addition is a primary cause of the viewers' fatigue. In this paper, a novel method for correcting rotated frames in video sequences is presented, where the modified Mojette transform is applied to the motion-compensated area in each frame. The Mojette transform is one of discrete Radon transforms, and is modified for correcting the rotated frames as follows. First, the bin values in the Mojette transform are determined by using pixels on the projection line and the interpolation of pixels adjacent to the line. Second, the bin values are calculated only at some area determined by the motion estimation between current and reference frames. Finally, only one bin at each projection is computed for reducing the amount of the calculation in the Mojette transform. Through the simulation carried out on various test video sequences, it is shown that the proposed scheme has good performance for correcting the rotation of frames in moving pictures.

• Korean Journal of Agricultural Science
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• v.51 no.3
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• pp.295-305
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• 2024

Due to the environment of irregular soil characteristic for agricultural fields, dynamic characteristic occurs in the tractor cabin during agricultural operations. Operator's fatigue is increased, and operation performance is decreased by these irregular environment conditions. This study was conducted to measure and analyze the dynamic characteristic of a tractor cabin, a major agriculture machinery, during agricultural operations. The specification of tractor used in the study was a 95 kW class tractor. To analyze the dynamic characteristics of the tractor cabin, the main agricultural operations, plow tillage and rotary tillage, were selected. To measure data of dynamic characteristic of the cabin, which continuously changes during operations, an Ellipse Series INS (inertia navigation system) with a built-in IMU (inertia measurement unit) was attached to the center of gravity of the cabin. During field test, the gear stages of plow tillage were B4 (4.3 km·h^-1) and B5 (5.6 km·h^-1), and the gear stages of rotary tillage were A3 (3.3 km·h^-1) and A4 (4.2 km·h^-1), which are the most commonly used. To analyze dynamic characteristic such as roll and pitch during operations according to the gear stages. As a result, the dynamic characteristics of pitch increased more than the dynamic characteristics of roll as the travel speed increased, and the dynamic characteristics of both agricultural operations were in the range of 2 to 5°.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.430-437
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• 2001

Recently, there have been increased much concerns about repair and rehabilitation works for aged concrete structures. It is in particular known that due to repeated overburden vehicles, there are significantly increasing number of aged concrete bridge slabs, which are strongly needed to construct and rehabilitate by innovative construction method. The objective of this research is to develop the new construction method of concrete slab in bridge superstructure, which can contribute to minimize a traffic congestion during repair and rehabilitation works of aged concrete slab, and can sufficiently assure the quality through the minimization of in-situ works at the site. I-beams with punch holes, which are substituted instead of main reinforcing steels in concrete slabs, can be manufactured in accordance with the specification in the factory, and be preassembled into the panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate mechanical properties of I-beam with punch holes itself, and then to investigate structural properties of assembled I-beam panels through static test, of which result can be utilized for the development of the new constructional method for concrete slab in bridge superstructure.

• Composites Research
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• v.31 no.1
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• pp.1-7
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• 2018

In the case of a conventional composite patch repair using a heat blanket, the adhesive is pressurized using only a vacuum bag. In this study, however, a pressurization system has been developed to apply additional air pressure on the vacuum bag. In order to verify the performance of the developed system, the composite laminates were repaired with scarf patches and then tested under tensile load to be compared with the strength of the defect-free laminate. Tensile tests were also conducted on specimens with the same configuration but bonded in an autoclave. As a result of the test, the tensile strengths of the specimens repaired using the heat blanket with vacuum only without external pressure, the specimens repaired with additional pressure by the developed system, and the specimens repaired with the same external pressure in an autoclave, showed the strength recovery ratios of 74.9, 81.0, and 78.2%, respectively. The results of the tensile test after moisture saturation and the dried fatigue test also showed that the strength recovery ratios of the specimens repaired under the external pressure of 1 atm using the developed system are slightly higher than that of specimens bonded in autoclave.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.2
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• pp.61-66
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• 2020

Recently, a variety of electric anesthetics devices have been developed and used in clinical practice to reduce the fatigue of the operator during local anesthesia for dental procedures and to compensate for the disadvantages of manual anesthesia device. In this electric anesthesia injection device, the accurate and constant delivery of pressure for drug infusion is a very important performance factor. In order to evaluate the accuracy of the transfer pressure, a small pressure gauge using a load cell is often used, but since the elastic body inside the load cell may not be able to accommodate a sufficient displacement, an error may occur when evaluating pressure performance. For these reasons, in this study, we proposed and evaluated a silicon-chrome steel (Si-Cr steel) spring jig that can accommodate relatively large displacements that can be used when evaluating the performance of a pressure-controlled pressure application device using a load cell type pressure gauge. As a result of the pressure transmissibility test and repeated measurement results using a commercial dental anesthesia injection device, a more stable result was obtained when using a spring jig, and it was confirmed that the frequency of abnormally high measurement was reduced.

• The Korean Journal of Physiology
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• v.9 no.2
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• pp.7-15
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• 1975

The maximum breathing capacity (MBC) and the maximum mid-expiratory flow rate (MMF) are widely used in evaluation of the ventilatory function, among various parameters of pulmonary function. The MBC volume is the amount of gas which can be exchanged per unit time during maximal voluntary hyperventilation. Performance of this test, unlike that of single breath maneuvers, is affected by the integrity of the respiratory bellows as a whole including such factors are respiratory muscle blood supply, fatigue, and progressive trapping of air. Because of this, the MBC and its relation to ventilatory requirement correlates more closely with subjective dyspnea than does any other test. The MMF is the average flow rate during expiration of the middle 50% of the vital capacity. The MMF is a measurement of a fast vital capacity related to the time required for the maneuver and the MMF relates much better to other dynamic tests of ventilatory function and to dyspnea than total vital capacity, because the MMF reflects the effective volume, or gas per unit of time. Therefore, it is important to have a prediction formula with one can compute the normal value for the subject and the compare with the measured value. However, the formulas for prediction of both MBC and MMF of the Korean children and adolescents are not yet available in the present. Hence, present investigation was attempt to derive the formulas for prediction of both MBC and MMF of the Korean children and adolescents. MBC and MMF were measured in 1,037 healthy Korean children and adolescents (1,035 male and 1,002 female) whose ages ranged from 8 to 18 years. A spirometer (9L, Collins) was used for the measurement of MBC and MMF. Both MBC and MMF were measured 3times in a standing position and the highest values were used. For measurement, the $CO_2$ absorber and sadd valve were removed from the spirometer in order to reduce the resistance in the breathing circuit and the subject was asked to breathe as fast and deeply as possible for 12 seconds in MBC and to exhale completely as fast as possible after maximum inspiration for MMF. During the measurement, investigator stood by the subject to give a constant encouragement. All the measured values were subsequently converted to values at BTPS. The formulas for MBC and MMF were derived by a manner similar to those for Baldwin et al (1949) and Im (1965) as function of age and BSA or age and height. The prediction formulas for MBC (L/min, BTPS) and MMF (L/min, BTPS) of the Korean children and adolescents as derived in this investigation are as follows: For male, MBC=[41.70+{$2.69{\times}Age(years)$}]${\times}BSA$ $(m^{2})$ MBC=[0.083+{$0.045{\times}Age(years)$}]${\times}Ht$ (cm) For female, MBC=[45.53+{$1.55{\times}Age(years)$}]${\times}BSA$ $(m^2)$ MBC=[0.189+{$0.029{\times}Age(years)$}]${\times}Ht$ (cm) For male, MMF= [0.544+{$0.066{\times}Age(years)$}]${\times}Ht$ (cm) For female, MMF=[0.416+{$0.064{\times}Age(years)$}]${\times}Ht$ (cm)

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.5
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• pp.96-106
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• 2014

The increased vibration level of the railway bridge could make significant noise and, also, cause structural damages such as fatigue cracks. Related to these subjects, a spherical elastomeric bridge bearing, which is layered by hemispherical rubber and steel plates, was investigated in terms of its vibration performance. Several different shape factors could be considered by changing the curvature of hemispherical surface and size in rubber and steel plate thicknesses in the manufacturing stage. The performance of the spherical elastomeric bearing for the reduction in vibration was compared with that of the conventional bearing by performing vibration experiments on a scale-downed model. The rubber material characteristics and spherical shape are found to be important parameters in reducing the bridge vibration.