• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.675-678
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• 2003

Experimental results for variation of concrete strength according to vibration time control for fresh concrete were given. Vibration velocity, time before vibration and vibrating time were used as experimental parameters. Compressive strength, split tensile strength, ana bond strength were investigated and then fracture surfaces of split tensile strength specimen were observed. From the experimental results, it could be concluded that there may be no decrease in concrete strengths if time before vibration will be sustained at least for more than 3 hours.

• Journal of Korean Medicine Rehabilitation
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• v.33 no.4
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• pp.167-184
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• 2023

Objectives This study was designed to assess the effectiveness of ultrasound therapy at the ST11 for regulation of sympathetic hyperactivity. Methods Forty healthy adult subjects were assigned to experimental group and control group. After taking mental stress, ultrasound therapy was applied at the ST11 in experimental group and sham-ultrasound therapy was applied in control group. The evaluation of sympathetic activity was measured by blood pressure, pulse rate, and heart rate variability at 3 times (Time 1: before the stress stimulation, Time 2: after the stress stimulation, Time 3: after the intervention). The primary end point was consisted of normalized (norm) low frequency (LF)/high frequency (HF) ratio, LF (norm), HF (norm). The secondary end point was consisted of systolic blood pressure, diastolic blood pressure, pulse rate, mean heart rate, standard deviation of NN intervals, root mean square of the successive differences, total power (log). Results After the stress stimulation, all subjects showed sympathetic hyperactivity. After the intervention, the experimental group showed lower sympathetic activity than the control group. Comparing the Time 3 and Time 1, the experimental group showed no significantly differences in sympathetic activity while the control group showed higher sympathetic activity in Time 3 than Time 1. Comparing the Time 3 and Time 2, the experimental group showed lower sympathetic activity in Time 3 than Time 2 while the control group showed higher sympathetic activity in Time 3 than Time 2. Conclusions We suggest that the ultrasound therapy at ST11 can decrease sympathetic activity in sympathetic hyperactivity condition.

• The Journal of Korean Physical Therapy
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• v.22 no.6
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• pp.1-6
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• 2010

Purpose: This study investigated the effects of visual feedback during abdominal hollowing (AH) in four point kneeling position, using real-time ultrasound imaging through measurement of the changes in the thickness of transversus abdominis (TrA), internal abdominal oblique (IO), and external abdominal oblique (EO). Methods: The subjects of this study were 32 healthy males who were divided intothe experimental group of 16 subjects and the control group of 16 subjects. The real-time ultrasound feedback was applied to the experimental group while they were educated on the AH exercise in four point kneeling whereas only general education and training were given to the control group. After the training, the changes in the thickness of abdominal muscles during AH in four point kneeling were compared between the experimental group and the control group. Results: The differences of the changes in the thickness of TrA and EO between the two groups were statistically significant. Conclusion: The experimental group experienced a higher increase in the thickness of TrA than the control group while the thickness of IO and EO of the experimental.

• Journal of Ocean Engineering and Technology
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• v.33 no.4
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• pp.358-363
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• 2019

The acoustic power is used as a primary index characterizing underwater sound sources and could be defined by its source level. The source level has been assessed using various experimental techniques such as the reverberation time method and reverberant tank plot method. While the reverberation time method requires reverberation time data extracted in a preliminary experiment in a reverberant water tank, the reverberant tank plot method only needs acoustic pressure data directly obtained at the reverberation water tank. In this research, these experimental techniques were studied in comparative experiments to estimate the source levels of underwater sources in a reverberant water tank. This paper summarizes the basic theories and procedures of these experimental techniques and presents the experimental results for an underwater source in a long cuboid water tank using each technique, along with a discussion.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.430-433
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• 2002

Fieldbus traffic consists of periodic, time-critical and time-available data. A bandwidth allocation scheme allocates periodic, time-critical and time-available data traffic to the bandwidth-limited network resource. This paper presents an implementation method of the bandwidth allocation scheme in the user layer of Foundation fieldbus. In this study, an experimental model of a Foundation Fieldbus network system is developed. Using the experimental model, validity of the bandwidth allocation scheme is examined. The results obtained from the experimental model show that the proposed scheme restricts the delay of both periodic and time-critical data to a pre-specified bound. The bandwidth allocation scheme also fully utilized the bandwidth resource of the network system.

• Geomechanics and Engineering
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• v.27 no.5
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• pp.433-445
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• 2021

Artificial ground freezing (AGF) is a commonly used geotechnical support technique that can be applied in any soil type and has low environmental impact. Experimental and numerical investigations have been conducted to optimize AGF for application in diverse scenarios. Precise simulation of groundwater flow is crucial to improving the reliability these investigations' results. Previous experimental research has mostly considered horizontal seepage flow, which does not allow accurate calculation of the groundwater flow velocity due to spatial variation of the piezometric head. This study adopted vertical seepage flow-which can maintain a constant cross-sectional area-to eliminate the limitations of using horizontal seepage flow. The closure time is a measure of the time taken for an impermeable layer to begin to form, this being the time for a frozen soil-ice wall to start forming adjacent to the freeze pipes; this is of great importance to applied AGF. This study reports verification of the reliability of our experimental apparatus and measurement system using only water, because temperature data could be measured while freezing was observed visually. Subsequent experimental AFG tests with saturated sandy soil were also performed. From the experimental results, a method of estimating closure time is proposed using the inflection point in the thermal conductivity difference between pore water and pore ice. It is expected that this estimation method will be highly applicable in the field. A further parametric study assessed factors influencing the closure time using a two-dimensional coupled thermo-hydraulic numerical analysis model that can simulate the AGF of saturated sandy soil considering groundwater flow. It shows that the closure time is affected by factors such as hydraulic gradient, unfrozen permeability, particle thermal conductivity, and freezing temperature. Among these factors, changes in the unfrozen permeability and particle thermal conductivity have less effect on the formation of frozen soil-ice walls when the freezing temperature is sufficiently low.

• Smart Structures and Systems
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• v.32 no.6
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• pp.349-358
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• 2023

Real-Time Hybrid Testing (RTHT) requires the numerical substructure calculations to be completed within the defined integration time interval due to its real-time loading demands. For solving the problem, A Real-Time Hybrid Testing based on Restart-Loading Technology (RTHT-RLT) is proposed in this paper. In the proposed method, in case of the numerical substructure calculations cannot be completed within the defined integration time interval, the experimental substructure was returned back to the initial state statically. When the newest loading commands were calculated by the numerical substructure, the experimental substructure was restarted loading from the initial state to the newest loading commands so as to precisely disclosing the dynamic performance of the experimental substructure. Firstly, the methodology of the RTHT-RLT is proposed. Furthermore, the numerical simulations and experimental tests on one frame structure with a viscous damper are conducted for evaluating the feasibility and effectiveness of the proposed RTHT-RLT. It is shown that the proposed RTHT-RLT innovatively renders the nonreal-time refined calculation of the numerical substructure feasible for the RTHT. The numerical and experimental results show that the proposed RTHT-RLT exhibits excellent performance in terms of stability and accuracy. The proposed RTHT-RLT may have broad application prospects for precisely investigating the dynamic behavior of large and complex engineering structures with specific experimental substructure where a restarting procedure does not affect the relevant hysteretic response.

• Journal of Veterinary Clinics
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• v.15 no.2
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• pp.235-241
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• 1998

In order to investigate the histological and immunohistochemical changes of thyroid glands, and serum osteocalcini estradiol, pmgesterone, follicular-stimulating hormone (FSH), and calcium levels in the osteoporotic rats induced by ovariectomy, normal(sham-operated group) and experimental groups(ovariectomized group) were divided. The experimental groups were subdivide6 to 5, 10, 15, and 20 weeks after ovariectomized groups. The histological structure of the thyroid gland were observed in normal structure throughout all experimental periods but the calcitonin-immunoreartive cells in the experimental groups were significantly decreased compared with normal groups and degranulations of calcitonin-immunoreactive cells were observed. Theses numbers were decreased with time after ovariectomy. However, the serum osteocalcin and FSH levels of experimental groups were significantly increased compared with normal groups and these levels were increased along with time after ovariectomy, but serum estradiol, progestemn and calcium levels of experimental group were significantly decreased compared with normal groups and these levels were decreased with time after ovariectomy.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.111-113
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• 2006

FOUNDATION fieldbus provides scheduling and token-passing services for cyclic and sporadic data respectively. In this paper, we evaluate the delay performance of token-passing mechanism in FOUNDATION fieldbus network system using an experimental model. This paper introduces a method of developing an experimental model which consists of 10 nodes of FOUNDATION fieldbus communication device. Using the experimental model, we evaluate the delay performance of time-critical and time-available data with respect to change of TTRT parameter.

• Journal of Korean Academy of Nursing
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• v.34 no.7
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• pp.1164-1171
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• 2004

Purpose: The purpose of this study was to compare differences in the time when bowel sounds were heard and gas was passed in women who had an abdominal hysterectomy and were treated for 5 minutes (experimental group A) or 10 minutes (experimental group B) with San-Yin-Jiao (SP-6) acupressure. Method: The design of this study was a nonequivalent control group non-synchronized post test only design. The participants included 142 women, 39 in experimental group A, 30 in experimental group B, and 73 in the control group. Data was collected using a structured questionnaire which included items on general characteristics and a self report of time when gas was passed. Differences for the three groups as to time when bowel sounds were heard and gas was passed were analyzed using ANOVA. Result: The time when bowel sounds were heard was statistically significantly shorter in both experimental groups compared to the control group(F=10.29, p=.000). The time when gas was passed was statistically significantly shorter in experimental group B(10 min) compared to the control group(F=4.68, p=.011). Conclusion: It could be concluded that SP-6 acupressure of 10 minutes was effective in shortening the time until bowel sounds were heard and gas was passed for women who had had an abdominal hysterectomy. Replication of the study with a larger number of participants is necessary in order to be able to generalize the results.