• Journal of Biosystems Engineering
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• v.12 no.3
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• pp.1-6
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• 1987

The objective of this study is to develop a soil hardness tester which can estimate tillage resistance with tae travelling cone-penetrometer. For the study, a series of tests was performed using the cone penetrating in the horizontal direction. Based on the tests above, soil hardness was represented by travelling cone-index vs depth of cone penetration, travelling speed and moisture contents of the soil Resistance characteristics obtained from the experiments were compared with those by a vertical cone-penetrometer and the Yamanaka's soil hardness tester. Following conclusions were made from the study. 1. 8 to 9 peaks per one meter were detected in the resistance curve of cone penetration regardless of the travelling speed of cone-penetrometer when it penetrated the soil in the horizontal direction. This phenomenon seemed to be a similar one noticed in shearing pitch of plowing. 2. Cone index increased as travelling speed increased from 0.08m/sec to 0.5m/sec. 3. Linear relationship was found between the cone indices measured by the travelling coe-penetrometer and Yamanaka's hardness tester. 4. Increasing rate of the cone indices measured by vertical cone-penetrometer decreased as the depth of soil increased while the cone indices by the travelling cone-pentrometer increased linearly.

• Journal of the Korean Institute of Telematics and Electronics
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• v.21 no.5
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• pp.33-40
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• 1984

In the conventional pulsed doppler system, gated CW is used to excite a ultrasonic transducer so that a group of linear RF amplifiers are required to excite a ultrasonic array transducer in the scanning pulsed doppler system. A pulsed doppler system without linear high voltage RF amplifiers, which excites the transducer impulsively, is studied theoretically and experimentally. In this paper, an experimental 8-channel pulsed doppler system is implemented, which uses quadrature defection to detect the direction of motion and can compensate the attenuation effect. The designed pulsed doppler system shows the possibility of real time multichannel doppler flow meter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.26-32
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• 2011

In this study, a standard illuminant A type LED that has similar emission spectrum as the standard illuminant A was developed using LED chip(emission peak: 405[nm]) and four types of phosphors(blue, green orangered and red). Using the design of experiment for spectrum control, the trend of the change of spectrum shape influenced by the change of interaction among phosphors and their density could be examined. Computer simulation through the optimization of the design of experiment revealed that, among four phosphors, the most influential one on the shape of the spectrum was green phosphor. Using the obtained optimal combination ratio of the four phosphors, an alternative LED illuminant to the actual standard illuminant A was developed and the spectrums of these two were confirmed identical. Using this standard illuminant A type LED, a portable transmittance meter with the range of measurement error of ${\pm}1.0$[%] was developed.

• Journal of the Korean Geotechnical Society
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• v.31 no.4
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• pp.13-18
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• 2015

Considering dredged ground is consolidated more than one meter, Compression index prediction is very important. But, UD-sampling and consolidation test are impossible because of high moisture content and weak shear strength. This paper demonstrates the compression index relation, $C_{c(d)}=F(e_d,C_c)$, between in-situ and dredged clay using N. Keith Tovey's Omega point and soil physical properties. Good relationship is confirmed between proposed formula and measured primary consolidation result on dredged ground in The Republic of Korea.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.10
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• pp.837-843
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• 2012

Compared to conventional pure-tone audiometer(PTA), the computerized one has several advantages such as relatively lower price, better flexibility, and easy operation. In addition, the computerized PTA can be easily extended to support automatic calibration. In this study, the support of automatic calibration in the computerized PTA has been addressed using the Linux realtime spectrum analyzer and network. In terms of accuracy, the new automatic calibration machine was compared to the existing manually operated one. According to the comparison, normal operation and high accuracy were observed within the scope of the international standard.

• Geomechanics and Engineering
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• v.19 no.4
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• pp.353-360
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• 2019

The elastic modulus is an important parameter to characterize the property of rock. It is common knowledge that the strengths of rocks are significantly different under tension and compression. However, little attention has been paid to the bi-modularity of rock. To validate whether the rock elastic moduli in tension and compression are the same, Brazilian disc, direct tension and compression tests were conducted. A horizontal laser displacement meter and a pair of vertical and transverse strain gauges were applied. Four types of materials were tested, including three types of rock materials and one type of steel material. A comprehensive comparison of the elastic moduli based on different experimental results was presented, and a tension-compression anisotropy model was proposed to explain the experimental results. The results from this study indicate that the rock elastic modulus is different under tension and compression. The ratio of the rock elastic moduli under compression and tension ranges from 2 to 4. The rock tensile moduli from the strain data and displacement data are approximate. The elastic moduli from the Brazilian disc test are consistent with those from the uniaxial tension and compression tests. The Brazilian disc test is a convenient method for estimating the tensile and compressive moduli of rock materials.

• The Journal of Korean Physical Therapy
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• v.32 no.6
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• pp.394-399
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• 2020

Purpose: The aim of this study was to determine the effects of lower rib cage lateral expansion limitation on the maximal inspiratory and expiratory pressures and on abdominal muscle activity during maximal respiratory breathing in healthy subjects. Methods: Fifteen healthy male subjects voluntarily participated in this cross-sectional study. During maximal breathing, maximal inspiratory and expiratory pressures were measured, and abdominal muscle activity was determined with using surface electromyography. Also, the measurement was repeated with using a non-elastic belt to the lower rib cage for limiting of lateral expansion. A Wilcoxon signed-rank test was performed for obtaining the statistical difference with a significance level of 0.05. Results: The findings of this study are as follows: 1) There were no significant differences in maximal inspiratory and expiratory pressure with and without lower rib cage lateral expansion (p>0.05), 2) There was no significant difference in abdominal muscle activity during the maximal inspiratory phase (p>0.05). However, right external oblique muscle activity decreased significantly during maximum exhalation with lower rib expansion limitation (p<0.05). Conclusion: The results of the current study indicate that a non-elastic belt was effective in decreasing right external oblique muscle activity during forced expiratory breathing in healthy subjects.

• The Korean Journal of Food & Health Convergence
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• v.7 no.4
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• pp.23-29
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• 2021

This study analyzes the physiological changes that occur after free diving and studies peroxidants and antioxidants according to the recovery method. Accordingly, the purpose of this study is to provide proper rest methods after free diving and provide basic data for free diving research. Eight male college students recovered for 30 minutes after 20 free injections at a 5-meter diving site, 20 free injections after a week's car wash, and recovered for 30 minutes after collecting blood during recovery to analyze the effects of peroxidants and antioxidants. Comparison of changes in peroxidants and antioxidants in recovery methods after free-diving iterations showed that SOD tended to decrease immediately after free-diving, increasing MDA to 10 minutes after recovery, but no significant difference was found. The purpose of this study is to observe physiological changes according to the recovery method after free diving and to propose an appropriate recovery method after free diving. However, there was no significant difference in all the restoration methods, and 20 freediving was not high kinetic intensity for the subjects, which is believed to have resulted in the following results. Therefore, it was discussed that the repetitive diving strength should be higher to confirm a significant difference in the recovery method after free diving.

• PNF and Movement
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• v.21 no.1
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• pp.11-18
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• 2023

Purpose: This study aims to compare the effects of obstacle walking training combined with cognitive tasks on balance, gait, and activities of daily living in patients with stroke. Methods: A single-subject design was used, where one stroke patient participated. Obstacle walking training combined with cognitive tasks was performed for 1 hour per day for a total of 10 times during the intervention phase. The subjects were measured five times in the baseline phase, 10 times in the intervention phase, and five times in the follow-up phase. The outcome measurements included the Berg balance scale (BBS), the 10-meter walk test (10 MWT), and the Korean modified Barthel index (K-MBI). Results: In this study, the results showed that the 10 MWT scores during the intervention period improved and that this improvement remained, even during the post-period. In addition, BBS and K-MBI values for stroke patients increased significantly after training. Conclusion: The results of this study revealed that obstacle walking training combined with cognitive task training may be helpful to improve balance, gait, and activities of daily living in stroke patients. Therefore, obstacle walking training combined with cognitive tasks is recommended for stroke patients.

• Current Optics and Photonics
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• v.7 no.5
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• pp.545-556
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• 2023

This paper introduces volume-sharing multi-aperture imaging (VMAI), a potential approach proposed for volume reduction in space-borne imagers, with the aim of achieving high-resolution ground spatial imagery using deep learning methods, with reduced volume compared to conventional approaches. As an intermediate step in the VMAI payload development, we present a phase-1 design targeting a 1-meter ground sampling distance (GSD) at 500 km altitude. Although its optical imaging capability does not surpass conventional approaches, it remains attractive for specific applications on small satellite platforms, particularly surveillance missions. The design integrates one wide-field and three narrow-field cameras with volume sharing and no optical interference. Capturing independent images from the four cameras, the payload emulates a large circular aperture to address diffraction and synthesizes high-resolution images using deep learning. Computational simulations validated the VMAI approach, while addressing challenges like lower signal-to-noise (SNR) values resulting from aperture segmentation. Future work will focus on further reducing the volume and refining SNR management.