• Smart Structures and Systems
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• v.15 no.1
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• pp.1-13
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• 2015

This paper proposes an analytical mode decomposition (AMD) and Hilbert transform method for structural nonlinearity quantification and damage detection under earthquake loads. The measured structural response is first decomposed into several intrinsic mode functions (IMF) using the proposed AMD method. Each IMF is an amplitude modulated-frequency modulated signal with narrow frequency bandwidth. Then, the instantaneous frequencies of the decomposed IMF can be defined with Hilbert transform. However, for a nonlinear structure, the defined instantaneous frequencies from the decomposed IMF are not equal to the instantaneous frequencies of the structure itself. The theoretical derivation in this paper indicates that the instantaneous frequency of the decomposed measured response includes a slowly-varying part which represents the instantaneous frequency of the structure and rapidly-varying part for a nonlinear structure subjected to earthquake excitations. To eliminate the rapidly-varying part effects, the instantaneous frequency is integrated over time duration. Then the degree of nonlinearity index, which represents the damage severity of structure, is defined based on the integrated instantaneous frequency in this paper. A one-story hysteretic nonlinear structure with various earthquake excitations are simulated as numerical examples and the degree of nonlinearity index is obtained. Finally, the degree of nonlinearity index is estimated from the experimental data of a seven-story building under four earthquake excitations. The index values for the building subjected to a low intensity earthquake excitation, two medium intensity earthquake excitations, and a large intensity earthquake excitation are calculated as 12.8%, 23.0%, 23.2%, and 39.5%, respectively.

• Korea Trade Review
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• v.47 no.4
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• pp.137-159
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• 2022

This study aims to analyze international trade papers published in Korea during the past 2002-2022 years. Through this study, it is possible to understand the main subject and direction of research in Korea's international trade field. As the research mythologies, this study uses the big data analysis such as the text mining and Social Network Analysis such as frequency analysis, several centrality analysis, and topic analysis. After analyzing the empirical results, the frequency of key word is very high in trade, export, tariff, market, industry, and the performance of firm. However, there has been a tendency to include logistics, e-business, value and chain, and innovation over the time. The degree and closeness centrality analyses also show that the higher frequency key words also have been higher in the degree and closeness centrality. In contrast, the order of eigenvector centrality seems to be different from those of the degree and closeness centrality. The ego network shows the density of business, sale, exchange, and integration appears to be high in order unlike the frequency analysis. The topic analysis shows that the export, trade, tariff, logstics, innovation, industry, value, and chain seem to have high the probabilities of included in several topics.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.72-83
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• 2009

The purpose of this study is to examine the effects of a degree of discretization in the direction of longitudinal dam axis on the results of three dimensional fill dam dynamic analysis. In this study, the three dimensional dynamic analyses of the existing 'H' dam which is modeled with a different degree of discretization were carried out. From these results, the fundamental frequency of the dam and the responses at the dam crest such as acceleration and settlement were compared and analyzed. It was concluded that the size of finite element discretized in the direction of the longitudinal axis mush be smaller than 1/8 of dam length in order to obtain the reasonable fundamental frequency and response of acceleration and mush be smaller than 1/10 in order to obtain the reasonable settlement behaviors from the three dimensional dynamic analysis of the fill dam.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.621-626
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• 2002

Two problems in the measurement of 6-DOF head vibration in very low frequency range were investigated in this study. One is how much error was involved in the estimation of three rotational and three translational motion at any specified point from measured 6 translational accelerations. The other is quantitative and qualitative influence of gravity on DC and AC component of the estimated accelerations in 6 degree of freedom, which were derived from pick-ups fixed on a helmet. In the study the effect of nonlinear terms on the estimation of 6 degree of freedom accelerations was negligible but gravity effect must be considered carefully.

• Journal of Korean Biological Nursing Science
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• v.3 no.2
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• pp.35-50
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• 2001

This study was conducted for the evaluation of the effects of singing program combined with physical exercise on the physiologic changes, perception function and degree of depression. The subjects were the members of elderly women's glee club in D care center for the elderly, who have been singing for more than 6 months. 30 members were allocated to study group and 30 to control group. The singing program designed for both physical therapy and music therapy was consisted of initial physical exercise, singing art songs and classical song and the finishing physical exercise. This program was performed twice a week and about forth minutes was consumed for one session. We checked the heart rate, peripheral arterial oxygen saturation, perception function and degree of depression before and after the program. We used a pulse oxymeter to check the heart rate to oxygen saturation and a questionnaire for the evaluation of perception function and degree of depression. We need SPSS program for data analysis. The results of the investigated personnel complying with general characteristics were analyzed by frequency, two groups by t-test, data before and after the program by paired t-test, respectively. The results were as follows. 1) Heart rate after the program was significantly lower than that before program in test group(p<0.05). 2) Peripheral oxygen saturation after the program was significantly higher than that before the program(p<0.05). 3) Ability to match the right sign with a certain predetermined number was improved after the program. The frequency of wrong matching the sign with number before program was 30. But the frequency was decreased to 8 after the program. 4) Ability to calculate was improved after the program. The frequency of wrong calculation before the program was $1.10{\pm}1.94$. But the frequency after the program was decreased to $0.97{\pm}1.84$. 5) The degree of depression after the program($2.07{\pm}0.49$) was significantly lower than that before program(p<0.001). These results show that singing program combined with physical exercise improves the oxygen delivery to peripheral circulation, stability of heart function, the perception function(calculating and matching ability) and decreases the degree of depression. In conclusion, singing program combined with physical exercise can be used for the effective measure to improve the health of elderly and prevent dementia.

• The Research Journal of the Costume Culture
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• v.10 no.2
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• pp.186-199
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• 2002

This study is carried out to examine the purpose of utilization and the degree of satisfaction on the information collected from the Internet site for the understanding of the reality of clothing information for college students. The results are as fellows; 1 . Three primary factors have been abstracted for the satisfaction of information. 2. The difference in the purpose of utilizing information, depending on the individual characteristic of students and the features related to computer, was shown in the difference of major and school year, number of the internet connection per day, capability of using computer, period of using computer, and frequency of information searching. The more the number of internet connection per day, the less the capability of using computer, and searching for information when required, internet can be utilized for study and work. 3. The difference in the degree of information satisfaction, depending on the individual characteristic of students and the features related to computer, was shown in the difference of major, school year, opportunity to take computer-related course, frequency of searching information, and etc. More positive and satisfactory response was derived from these not majoring in clothing rather than those majoring, those taking computer course related to clothing, and those searching for clothing information periodically. 4. The primary factors affecting the satisfaction on the overall information of clothing show difference in terms of sex and frequency of searching information. Female students show lower degree of satisfaction than male students and more satisfaction on the information searched as the frequency of searching becomes less.

• Journal of the Korean institute of surface engineering
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• v.36 no.3
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• pp.242-250
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• 2003

Electrodeposition of Ni was carried out on copper substrate from Ni Sulfamate bath by DC and high frequency pulse current. During the electroplating, bath temperature was steady $60^{\circ}C$ , agitation was applied. Morphology and surface roughness of electrodeposits was investigated with the AFM. Crystalline structure of electrodeposits was investigated with XRD. Also, surface electric resistivity was investigated with 4-point probe. The result of crystalline structure by X-ray diffractometer, in the case of DC, <200> direction was dominant growing direction. But in the case of PC, the ratio of <200> direction vs. other direction decreased. As the pulse frequency increased, the enhanced properties of deposits were shown. With increasing frequency, the degree of surface properties increased DC more than that of PC, eg surface morphology, roughness and the degree of compactness of grains. With increasing duty cycle, the surface properties such as the degree of the morphology, roughness and electroconductivity was deteriorated.

• Journal of the Korean Graphic Arts Communication Society
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• v.30 no.1
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• pp.47-58
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• 2012

The inorganic powder EL lamp was made by screen printing technique with a phosphor ink and a dielectric ink. Value of color coordinates X and Y increased under the condition of supplying driving power to the inorganic powder EL lamp and changing voltage with constant frequency. When frequency was changed under the constant voltage, value of color coordinates X and Y were decreased with increasing frequency. However, level of change of color coordinates X was different from color coordinates Y. When voltage was increased under constant frequency, changing degree of color coordinates X and Y shows similarity. But under the constant voltage with changing frequency, color coordinates X and Y were differently changed that degree of change of color coordinates Y showed five times more than that of color coordinates X. As increasing thickness of phosphor ink and dielectric ink, level of voltage and frequency, color coordinates X and Y were slightly changed. According to the thickness of phosphor ink and dielectric ink, and level of voltage and frequency, color coordinate of color light was changed. Frequency was most important element influencing on the change of color coordinate.

• Journal of muscle and joint health
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• v.23 no.3
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• pp.152-158
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• 2016

Purpose:The purpose of this study was to examine the degree of joint pain, limitation of daily activities, and frequency of outpatient visits. Methods: This secondary analysis study used the data from the fifth Korean National Health and Nutrition Examination Survey (KNHNES). The data about general characteristics, prevalence and treatment of osteoarthritis, limitation of activities of daily living (ADL) and frequency of outpatient visits and hospitalization in 424 osteoarthritis patients over 50 years old were derived from the database. Data were analyzed with complex samples in SPSS ver. 20.0. Results: Among people with knee joint pain, 79.3% reported they had more than 4 out of 10 points of the degree of pain. Meanwhile, 97.3% of people with hip joint pain reported that they had more than 4 out of 10 points of the degree of pain. People reporting 10 out of 10 point of pain were 21.4% of those with knee joint pain and 25% of those with hip joint pain. The mean of the degree of knee joint pain was 6.35, and the mean of the degree of hip joint pain was 6.89 out of 10 points. About 50% of people with osteoarthritis visited an outpatient clinic within the last 2 weeks, and 27% had limitation of ADL. Conclusion: It is necessary to develop an integrated intervention program to improve quality of life in patients with osteoarthritis.

• Journal of Fashion Business
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• v.8 no.2
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• pp.1-14
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• 2004

The purpose of study is to analyze the consumer attitude toward original brand and imitation goods. To carry out this purpose, the study examined consumers' purchase frequency, degree of concern, future purchase, intention, other people's evaluation and self-satisfaction. The results of experiment can be summarized as follows: First, the consumers didn't show high degree of purchase frequency, of concern, of future purchase but they showed positive attitude in other people's evaluation and self-satisfaction. Second, they showed high degree of the purchase of imitation goods but they didn't show high degree of their degree of satisfaction. Third, with regard of their purchase intention, they purchased imitation goods because they were cheap, regardless of image, quality and design which original brand name goods had. Finally, to figure out the correlation between original brand name goods and imitation goods, their purchase intention of original brand name goods was surveyed according to their satisfaction with imitation goods after they purchased them. According to the result, they answered that they would purchase original brand name goods when they satisfied with imitation goods.