• Smart Structures and Systems
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• 제20권2호
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• pp.127-137
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• 2017

Identification of damping characteristics is of significant importance for dynamic response analysis and condition assessment of structural systems. Damping is associated with the behavior of the energy dissipation mechanism. Identification of damping ratios based on the sensitivity of dynamic responses and the model updating technique is investigated with numerical and experimental investigations. The effectiveness and performance of using the sensitivity-based model updating method and vibration monitoring data for damping ratios identification are investigated. Numerical studies on a three-dimensional truss bridge model are conducted to verify the effectiveness of the proposed approach. Measurement noise effect and the initial finite element modelling errors are considered. The results demonstrate that the damping ratio identification with the proposed approach is not sensitive to the noise effect but could be affected significantly by the modelling errors. Experimental studies on a steel planar frame structure are conducted. The robustness and performance of the proposed damping identification approach are investigated with real measured vibration data. The results demonstrate that the proposed approach has a decent and reliable performance to identify the damping ratios.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.24-35
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• 2017

본 논문은 하천 제방의 침투방지공법으로 일본 미쓰야마 하천 국도 사무소에서 제시한 월륜 공법에 대한 효용성을 연구한 것으로, Hydraulic well의 현장 적용성과 시공성 개선, 침투압 분포 특성을 파악하기 위하여 대형 제방실험과 침투 해석을 수행하였다. 대형제방실험의 방법은 제외지 수위를 재현하여 제방을 포화시킨 후 제방의 간극수압계 변화를 감지, hydraulic well의 내부 수위를 0.1 m ~ 0.7m로 변화하고 이때 간극수압계를 통해 측정된 간극수압을 비교하여 침투압의 변화를 확인하였다. 대형 제방실험은 hydraulic well의 설치 지점에 따라 두 가지 방법으로 수행하였다. 대형 제방실험결과, hydraulic well의 내부 수위 변화에 따라 최대 37%의 침투압 저감 현상이 발생하는 것으로 평가되었다. 대형 제방실험과 침투 해석의 간극수압을 비교한 결과 거의 유사한 경향이 나타났다. hydraulic well의 내부 수위 변화와 산정된 간극수압의 변화도 비슷한 양상을 보였으나, 심도가 깊어짐에 따라 대형 제방실험결과보다 침투 해석의 간극수압이 더 크게 산정되었다.

• 대한지구과학교육학회지
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• 제8권2호
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• pp.227-239
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• 2015

The purpose of this study was to see the effects of science classes applying ARCS strategies on motivation of science class as well as scientific attitude of elementary students. For this purpose, 47 elementary students in 2 classes from 5th grade of M elementary school based in P metropolitan city were targeted. One class with 24 students was assigned as experimental group and the other class with 23 students were assigned as control group. The chapter of 'solar system and star' in the curriculum revised in 2009 was taught over 10 classes from mid-April to end of June in 2015. For verification, 10 times science classes applying ARCS strategies were performed on experimental group while 10 times of general science class were performed on control group. The results drawn from this analysis were as below. Firstly, positive relationship was found between motivation of science class and science class applying ARCS strategy among experimental group and this means that science classes applying ARCS strategy stimulate intellectual curiosity of students and improves their attitude by actively promoting research activities. Secondly, there was a positive relationship between scientific attitude and science classes applying ARCS strategy among experimental group. This presents that science classes applying ARCS strategy were effective in improving students' scientific attitude by promoting research activities. Above results show that science classes applying ARCS strategy were highly effective for elementary students.

• 근관절건강학회지
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• 제14권2호
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• pp.109-117
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• 2007

Purpose: The purpose of the study was to identify the effect of a self-exercise program on low back pain, abdominal-back muscle strength and waist flexibility in hospital nurses. Method: An experimental research design was employed. 43 subjects (20 in the experimental group and 23 in the control group) who worked in a general hospital in W city agreed to participate in this study. The intervention had 6 sessions with self-exercise program including flexion and extension demonstrated by a trained research assistant. A Visual Analog Scale was used to measure the subjective pain severity. Abdominal-back muscle strength was measured with a back strength dynamometer, while waist flexibility was gauged by the standing of the subject's upper body. Analysis included descriptive statistics, $x^2$ test, t-test and ANOVA. Result: The experimental group exhibited significantly decreased low back pain, an increase in abdominal-back muscle strength, and increased waist flexibility after 6 sessions. The experimental group were not significantly increased in abdominal-back muscle strength than the control group. Conclusion: These results suggest that further research is needed to replicate for verification of clinical validity with the methodological rigors, and to utilize the self-exercise program for care and prevention of low back pain.

• 한국컴퓨터정보학회논문지
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• 제20권8호
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• pp.121-128
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• 2015

This study aimed to investigate the effects of an unplugged robot education system capable of computerless coding education. Specifically, this study compared this education system with PicoCricket, an educational robot that can also be used with elementary students in lower grades, using assessment tools on perceived usefulness and ease. Using random sampling and randomized assignment for more objective validation, 30 participants were assigned to the unplugged robot education system group (experimental group) and 30 participants were assigned to the PicoCricket group (control group), for a total of 60 study participants. The research procedure included verification of the equivalence of the two groups by conducting a pretest after a 2-hour basic training session on algorithms and programming. The experimental and control groups learned the same content using different educational tools in accordance with software training guidelines for a total of 12 hours. Then, the difference in perceived usefulness and ease between the two groups was examined using a post-treatment test. The study results showed that scores on both dependent variables, perceived usefulness and perceived ease, were significantly higher in the experimental group than the control group. Moreover, scores on all sub-variables of the dependent variables were significantly higher in the experimental group than the control group. These results suggest that learners using the unplugged robot education system found it more useful and easier to use than learners using the existing educational robot, PicoCricket. This study's findings are significant, as according to the technology acceptance model, the perceived usefulness and ease of an educational tool are important variables that determine the acceptance of the tool (i.e., persistence of learning).

• 지역사회간호학회지
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• 제32권2호
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• pp.220-231
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• 2021

Purpose: This study is a pseudo-experimental study of design before and after the non-equivalent control group, which was attempted to verify that the application of the ukulele to the elderly has the effects of reducing depression, improving self-efficacy, strengthening social bonding, and improving cognitive function. Methods: 46 (23 in the experimental group and 23 in the control group) participants were selected. The experimental group was provided with three sessions of a music program using eight Ukuleles for the elderly, while the control group was provided with three sessions for the elderly. IBM SPSS 25.0 was used for data analysis, and the independent t-test, 𝑥²-test, and Fisher's exact probability test were performed to verify the homogeneity of the subject's general characteristics. The effect verification after the experimental treatment was analyzed by Fisher's exact probability test, Friedman test, and Mann-Whitney U test. Results: Depression showed a statistically significant difference between the two groups (F=39.88, p<.001), self-efficacy showed a statistically significant difference between the two groups (z=-4.96, p<.001), social bonding showed a statistically significant difference between the two groups (z=-5.19, p<.001), and cognitive function showed a statistically significant difference between the two groups (z=-3.98, p<.001). Conclusion: It was found that the 'Music Program using the Ukulele' was effective in reducing depression of the elderly, improving self-efficacy, reinforcing social bonding, and improving cognitive function. We hope that the Music Program using the Ukulele can be used in the elderly nursing curriculum in the future, and we suggest it should be applied as a nursing intervention to those who are experiencing cognitive decline.

• 대한물리의학회지
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• 제18권1호
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• pp.77-86
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• 2023

PURPOSE: This study developed an experimental algorithm, which is similar or identical to semantic linking for KCF codes, even if it converted existing semantic code linking methods to morphological code extraction methods. The purpose of this study was to verify the applicability of the system. METHODS: An experimental algorithm was developed as a morphological extraction method using code-specific words in the KCF code descriptions. The algorithm was designed in five stages that extracted KCF code using natural language paragraphs. For verification, 80 clinical natural language experimental cases were defined. Data acquisition for the study was conducted with the deliberation and approval of the bioethics committee of the relevant institution. Each case was linked by experts and was extracted through the System. The linking accuracy index model was used to compare the KCF code linking by experts with those extracted from the system. RESULTS: The accuracy was checked using the linking accuracy index model for each case. The analysis was divided into five sections using the accuracy range. The section with less than 25% was compared; the first experimental accuracy was 61.24%. In the second, the accuracy was 42.50%. The accuracy was improved to 30.59% in the section by only a weight adjustment. The accuracy can be improved by adjusting several independent variables applied to the system. CONCLUSION: This paper suggested and verified a way to easily extract and utilize KCF codes even if they are not experts. KCF requires the system for utilization, and additional study will be needed.

• Journal of information and communication convergence engineering
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• 제5권2호
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• pp.121-125
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• 2007

In this paper, a planar active retrodirective four-element array with subharmonic phase conjugation mixers based on anti-parallel diode pairs (APDPs) is designed, and its application in the auto-tracking duplex communication link is presented. As compared to previous phase conjugation mixers using twice RF frequency for LO frequency, the proposed conjugation mixers need only half RF frequency so that it can be easily applied for millimeter-wave applications. The proposed architecture, which conventionally performs the function of the transmission of an incident signal back in the direction of its source, is modified in order to include a receive function. Experimental verification of these architectures is performed at 1GHz and the results from the prototypes are compared with a theoretical model.

• 한국유체기계학회 논문집
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• 제11권5호
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• pp.7-14
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• 2008

Open channel type regenerative pump has been used in various industrial fields. It generates high pressure with low flow rate. However, it has low efficiency because of its complex flow pattern, We studied performance experiments and 3D numerical flow analysis of a regenerative pump. Through the numerical analysis, we could get the internal flow pattern and profile of a regenerative pump. Also, we examined leakage flow effects due to the gap between casing and impeller and stripper clearance. For the numerical analysis verification, we performed experiments and they had similar tendency at the design point.

• 한국태양에너지학회 논문집
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• 제25권1호
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• pp.79-86
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• 2005

The external conditions for estimating dynamic wind loads of wind turbines, such as the turbulence, the extreme wind, the mean velocity gradients and the flow angles, are simulated over GangWon Wind Energy Test Field placed in one of the most complex terrain in Korea. Reference meteorological data has been gathered at a height of 30m from 2003 to 2004 with a ultrasonic anemometer. The absolute value of the spectral energy are simulated and the verification of this prediction has been carried out with comparing to the experimental data. The most desirable place for constructing new wind turbine are resulted as Point 2 and Point 3 due to the lower value of Turbulence Intensity and the higher value of wind resource relatively.