• Journal of the Korea Concrete Institute
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• v.14 no.1
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• pp.1-7
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• 2002

The purpose of this research is to obtain a practical expression for the estimation of compressive strength of concrete using non-destructive testing method such as rebound Schmidt hammer and ultrasonic pulse

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.67-74
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• 2008

In this paper we describe discharge characteristics between needle-to-plane electrodes in water in various conditions such as different impulse voltages, polarities and water resistivities. Streamer corona is initiated at the tip of needle electrode and propagates toward plane electrode, and it experiences the final jump across the test gap. The branched channels of streamer coronas for lower water resistivities are much thicker and brighter than those for higher water resistivities at the same level of applied voltage. The negative streamer coronas not only have more branches but also widely spread out compared to the positive streamer coronas. A number of pulse-like currents ranging from some hundreds mA to a few A after streamer corona onset were produced with discharge developments. The time-lags-to breakdown for the positive polarity were remarkably shorter than those for the negative polarity. The pre-breakdown energy supplied into the test gap was inversely proportional to water resistivity.

• Journal of Pharmacopuncture
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• v.7 no.1 s.12
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• pp.15-26
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• 2004

Background : This study was conducted to evaluate the effects of wild ginseng herbal acupuncture developed for the intravenous use. Healthy male and female volunteers(n=57) went through Randomized Control Trials(RCT). Methods : For those who are under a medication due to common cold or other illnesses were excluded in the primary stage and the subjects with possible abnormalities in the pre-screening process were also excluded in the secondary stage. Then the examination groups were determined by random sampling. Experiment groups were divided into Normal saline injection group(control group), cultivated wild ginseng herbal acupuncture group(experiment group 1) and natural wild ginseng herbal acupuncture group(experiment group 2) Blood tension, body temperature, pulse, and other criteria were measured and analyzed. Results : 1. Intravenous injection of cultivated wild ginseng herbal acupuncture and natural wild ginseng herbal acupuncture didn't cause significant changes in the blood tension, pulse, body temperature, and etc. 2. No significant differences were witnessed in CBC, ESR, biochemistry of blood test and UA between the experiment groups. 3. No significant changes were noted in the thermography before and after the test in the experiment groups. 4. Some of the common physical changes occurring during and after the administration were fatigue, chest distension, and headache in all of the experiment groups. 5. Comparing general condition after one week from the termination of administration, the control group showed worst condition while as the natural wild ginseng herbal acupuncture group displayed best condition. Conclusion : From the above results, we can carefully deduce that the intravenous injection of the wild ginseng herbal acupuncture didn't show significant differences compared to injection of the normal saline. We can infer it is safe on the human body and further studies and reports must be followed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.512-515
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• 2010

SIGINT(SIGnal INTelligence) includes several parameters intercepted by measurement and analysis of the RF(Radio frequency) signal from free space. One of the important parameters is frequency information. Expecially, in order to perform instantaneous frequency measurement of Radar and Missile seeker's RF signals, we use dedicated RF modules as a DFD(Digital Frequency Discriminator) to provide frequency information by measurement of the relative phase difference between signals via intended RF delay lines. It must measure and provide realtime based frequency information on short pulsed RF signal up to 100 nSec or less. This document proposes Ultra wideband DFD consisted of a RF input section of Wideband 4 channel RF delay line and correlator, a digital processing section to measure and provide frequency information from I/Q signal, and a frequency calibration section. Also, it will show design suitability based on test results measured under test condition of very short input pulse signals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.567-575
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• 2017

The direction finder is an important device for an electronic support(ES) system because it is responsible for finding the direction of an emitter. The higher the accuracy of the direction finding, the higher the vitality of the weapon system with the ES system. Recently, the direction error occurred in the operating shipboard ES system when direction finding was performed for the signal with a pulse width of 200 ns. Therefore, this paper proposes, an improved method to reduce the direction error for shipboard ES systems. The proposed method was applied to the operating shipboard ES system and a field test was performed. The results of the field test showed that the direction error was reduced significantly for the signal with a pulse width of 200 ns.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.3
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• pp.429-436
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• 2021

The wind profilers operated by the Korea Meteorological Administration observe in a low mode for intensive observation of the low levels and a high mode for intensive observation of the high levels. The LAP-3000 wind profiler installed in Bukgangneung and Changwon is characterized by the same sampling frequency of the low mode and the high mode, allowing to compare winds observed in both modes at the same altitude. As a result of analyzing the wind speed of the two points for one year in 2020, the correlation between the two modes was up to 0.2 lower than the correlation with radiosonde. The T-test for the wind speed of the two modes showed a particularly significant difference in October, where the temperature and specific humidity fluctuate frequently. The difference in the development of the atmospheric boundary layer affects the accuracy of the wind speed depending on the observation mode.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.71-72
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• 2022

In this paper, the performance evaluation of the vibration damping ratio according to the polymer mixing ratio of the polymer modified mortar used as the floor finishing material of the apartment building structure was evaluated. To compare the vibration damping rate, ordinary potland cement (OPC) mortar and polymer modified mortar (PMM) were prepared. In addition, the mixed polymer was mixed with Styrene Butadiene Rubber (SBR) liquid polymer with a solid content of about 49%. Accordingly, the W/C of the test specimen was adjusted and compounded, and the experiment was conducted by mixing 5 types of the test specimen: OPC-60, PMM-5%, PMM-10%, PMM-15%, and PMM-20%. In addition, in order to adjust the W/C of the specimen, the fluidity of each specimen was set as 210 (±5) mm. The specimens measured density and flow in fresh mortar and after curing for 28 days, flexural strength, compressive strength and ultrasonic pulse were measured. The attenuation rate was shown. The experimental results showed that the density increased according to the mixing of the polymer, the flexural strength increased as the mixing rate of the polymer increased, and the compressive strength was decreased. In addition, it was shown that the vibration damping rate increases with the increase in the amount of polymer incorporated.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.89-96
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• 2012

The rubber side could be contaminated using the existing pulse echo method because the ultrasonic wave was incident on the rubber side from the interior of the steel motor case, which could lead to the critical disbond defect. To develop the test method which can be replaced the existing method, the ultrasonic wave was incident on steel face of the steel/rubber adhesive test block. Rubber resonance frequencies measured from the steel/rubber adhesive test block were in good agreement with theoretically predicted rubber resonance frequencies. This paper was described about the ultrasonic resonance method to convert the rubber resonance frequency into the rubber thickness.

• Journal of Korean Academy of Nursing
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• v.48 no.4
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• pp.465-474
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• 2018

Purpose: This study aimed to determine the effect of hand massage in patients who underwent transradial percutaneous coronary intervention. Methods: This was a quasi-experimental study with a nonequivalent control group and non-synchronized design. The study included 30 patients in the experimental group and 30 in the control group. Hand massage was performed 2 times for 5 minutes each in the experimental group and the control group only received usual nursing interventions. Pain, level of discomfort, and vital signs were defined as key outcome measures, and the data were analyzed using the chi-square test, an independent t-test, Mann-Whitney U test, repeated-measures analysis of variance, and Friedman test. Results: Significant differences were observed between the 2 groups in the pain score (F=7.91, p=.003), discomfort score (F=18.15, p<.001), pulse (F=12.92, p<.001), and respiration rate (${\times}^2=19.35$, p<.001). Conclusion: Hand massage can be a helpful nursing intervention for transradial percutaneous coronary intervention by reducing pain and discomfort to a considerable degree.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.1
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• pp.153-161
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• 2002

This paper develops a finite element model for crashworthiness analysis ova small-sized bus. The full vehicle finite element model is composed of 31,982 shell elements,599 beam elements,42 bar elements, and 34,204 nodes. The model uses four material models (such as elastic, elastic-plastic(steel), rigid. and elastic-plastic (rubber) material model) of PAM-CRASH. The model uses four contact types to define sliding interfaces in ten areas. A frontal crash test using an actual vehicle with 30mph velocity to a rigid barrier is carried out. Vehicle pulses at lower part of left and right b-pillar are measured, and deformed shapes of frame and driver seat's lower left area are photographed. A frontal crash simulation using the developed full vehicle finite element model is performed with PAM-CRASH installed in super computer SP2. The simulation is performed with the same conditions as the test. The measured vehicle pulses and photographed deformed shapes from the test are compared to ones from the simulation to validate the reliability of the developed model.