• Journal of Korean Association for Spatial Structures
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• v.18 no.1
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• pp.77-84
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• 2018

The identification of damping ratios in buildings is a well-known problem and appears to be of important and crucial interest in the safety and serviceability design. When compared to an estimation of the stiffness, i.e. natural frequency, and mass, the damping ratio is the most difficult quantity to determine. Many previous studies have examined the characteristics of damping ratios from ambient vibration, but the measurement time is roughly within 2 hours. In this paper, characteristics of damping ratios and natural frequencies of 4 story RC building were investigated using long-term ambient vibration. Free vibrations were obtained using random decrement technique, and damping ratios were evaluated by the envelop function, continuous wavelet transform, and logarithmic decrement. It was found that although the natural frequencies show little variations with time, the damping ratios show some variations with time and the largest variations found in the damping ratios obtained from the continuous wavelet transform. The damping ratios from the envelop function showed the smallest mean and standard deviation. And the probability distribution of damping ratios seems to follow the logarithmic normal distribution.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.469-471
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• 2010

Supercavitating vehicles which cruise under water undergo high longitudinal force caused by thrust and drag. These combination may cause structural buckling. Static and dynamic buckling analysis method by using FEM can be used to predict this structural failure behavior. In this paper, some principles which include method for solution eigenvalue problem for buckling analysis are introduced. And before buckling analysis, we predicted some mode shape and natural frequency of cylindrical shell by using DIAMOND/IPSAP eigen-solver.

• Earthquakes and Structures
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• v.8 no.4
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• pp.843-857
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• 2015

System identification is regarded as the most basic technique for structural health monitoring to evaluate structural integrity. Although many system identification techniques extracting mode information (e.g., mode frequency and mode shape) have been proposed so far, it is also desired to identify physical parameters (e.g., stiffness and damping). As for high-rise buildings subjected to long-period ground motions, system identification for evaluating only the shear stiffness based on a shear model does not seem to be an appropriate solution to the system identification problem due to the influence of overall bending response. In this paper, a system identification algorithm using a shear-bending model developed in the previous paper is revised to identify both shear and bending stiffnesses. In this algorithm, an ARX (Auto-Regressive eXogenous) model corresponding to the transfer function for interstory accelerations is applied for identifying physical parameters. For the experimental verification of the proposed system identification framework, vibration tests for a 3-story steel mini-structure are conducted. The test structure is specifically designed to measure horizontal accelerations including both shear and bending responses. In order to obtain reliable results, system identification theories for two different inputs are investigated; (a) base input motion by a modal shaker, (b) unknown forced input on the top floor.

• Journal of Korea Water Resources Association
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• v.36 no.2
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• pp.153-159
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• 2003

When available rainfall data is not sufficient, a rough tendency of I-D-F relationship appeared frequently. In fact, rainfall intensity on the curve shows abnormally higher value the longer rainfall duration is applied that gives rise to great confusion to apply a rainfall I-D-F relationships curve to a practical work, however, the research work will present a way to solve above mentioned problem by the use of the Box-Cox transformation formula for a given rainfall data. The study came to a conclusion that the Box-Cox transformation formula is satisfied to utilize in a practical work on the ground of analysis for rainfall data of Sancheong and Yeongcheon.

• Journal of muscle and joint health
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• v.23 no.1
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• pp.28-38
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• 2016

Purpose: The purpose of this study was to investigate post-burn itching relevant characteristics in the rehabilitation phase. Methods: Ninety four burn patients who were hospitalized in the rehabilitation phase participated in the study. Self-reported Leuven itch scale-Korean was used to evaluate itching related characteristics. Data were analyzed with descriptive analysis, $x^2$ test, and Kruskal-Wallis test. Results: All subjects except two had the itching. Itching frequency revealed that 68.1% of subjects experienced itching one or more episodes a day or always, and 18.7% had episode durations lasting more than 2 hours per incidence. Mean severity and distress of itching was $5.3{\pm}2.4$ and $5.2{\pm}2.5$, respectively. Itching sensation dimension of tickling was 56.4%. More than 25% of subjects "often" or "always" affected reduced quality of life, loss of concentration, bad mood, and difficulty in falling asleep. Satisfaction with itching treatment was intermediate level. Conclusion: Post-burn itching in the rehabilitation phase was a significant problem despite pruritus treatment. Based on the finding of this study, development of comprehensive and tailored nursing intervention programs for itching could be suggested.

• Journal of Fashion Business
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• v.19 no.5
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• pp.188-198
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• 2015

This study analyzed the qualifications necessary and manpower required in the Jeju nail art and make-up industry. We aimed to investigate the relationship between NCS education and national technical qualifications. For this study, 164 participants were given a questionnaire, and the collected data were analyzed via frequency analysis and multiple regression analysis using SPSS Ver. 18.0. The results of this study are as follows: 1. Matching job seekers with available positions was more difficult in nail art businesses than in makeup businesses. The main routes by which practitioners found jobs were Internet job sites and acquaintances. In addition, experience was the first consideration in hiring employees. 2. Those in high positions had less intention of employing students who had received NCS education, than those in lower positions. Intention to employ NCS graduates was high in businesses that found their employees through Internet job sites, vocational training institutes, acquaintances, or colleagues. Nail art workers prioritized NCS educational units in the following order: nail care, nail shop hygiene, gel nails, cosmetic nail removal, and tips/wraps. Makeup workers had the following priorities: basic makeup, wedding makeup, makeup shop safety, and hygiene management. They also mentioned basic occupational skills such as communication skills, interpersonal skills, and problem solving skills. Moreover, the new national licensing system was found to reflect competency in the most important skill sets.

• Research in Community and Public Health Nursing
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• v.6 no.2
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• pp.212-233
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• 1995

Cerebrovascular diseases in Korea is an important health problem since mortality and mobidity have been increasing rapidly. Cerebrovascular diseases marked the 2nd rank of cause specific death rate in 1993. The ploblem of emotion after a stroke has received very little attention from the nursing profession until recently. Even the frequency of the emotional disorder after stroke is uncertain, and there has been very little research. Emotional disorder after stroke was related to limited social function, guilty conscience, helplessness, hopelessness, powerlessness, alienation, and damage of self-image. In the stroke patient, hope may be related to a rehabilitation or enhancing physical condition. Inspiring hope is necessary when stroke patients are unable to mobilize energy on their own behalf and perceive limited or no person choices available. Inspiring hope is an intervention that can be used with many nursing diagnoses, especially when feelings of helplessness, hopelessness, powerlessness, and depression are present. The nurse can inspire hope by understanding the hoping process. On the basis of this literature review, the following suggestions are prosed. 1) Qualitative studies on hope have been done to indentify variables that affect maintenance of hope in the chronically ill patients. 2) In the development of an instrument to measure hope, the validity, reliability, and cultural property of the hope have been estabilished.

• KIEAE Journal
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• v.10 no.1
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• pp.19-24
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• 2010

Modern people are spending most of time in interior area. Indoor air environmental problem is one of the most effective factors influenceable to human health. Furthermore, saving energy and making ventilation system for pleasant indoor environment are necessary when it is faced shortage of energy over the world. In our country's case, it is already imposed that required quantity of air ventilation in buildings is 0.7 times per hour on "The regulation on building engineering system". As on the rise of the interests about Indoor air environment, Heat and Carbon dioxide emissions from User's metabolism, activity, furniture, and construction materials etc. could be the causes of Indoor air pollution. If these materials stays in Indoor air for so long, it could directly influence the user's health condition with a disease. As of building's sterilization improved that raised more mechanical ventilation. It also leads much energy waste in a period of high price of fossil fuel. Therefore, the way that saves energy and effective control of indoor ventilation is urgently needed. So, this study places the purpose on validating volume of indoor ventilation and user's comfortable degree by comparison CO2 emission rate through changing floor temperature.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.4
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• pp.310-317
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• 2013

In this paper an ESPRIT-based super-resolution time delay estimation algorithm is developed for real-time locating system (RTLS) and its performance is analyzed in various multipath environments. The performance of the existing correlation method for time delay estimation seriously degrades in multipath environments where the relative time delays of multipath signals are less than a PN chip. To solve the problem we shall develop a frequency domain super-resolution time delay estimation algorithm using the ESPRIT, the most representative super-resolution direction-of-arrival (DOA) estimation algorithm, and analyze its performance in various multipath environments.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.12
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• pp.691-700
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• 1999

This paper proposes a novel switching strategy of 1Mvar STATCON using cascade multilevel H-bridge inverter(HBI) for FACTS application. To control the reactive power instantaneously, the d-q dynamic system model is described and analyzed. A single pulse pattern based on the SHEM(Selective Harmonic Elimination Method) technique is determined from the look-up table to reduce the line current harmonics and a rotating fundamental frequency switching scheme is presented to adjust the DC voltage of each inverter capacitor at the same value. So the voltage unbalance problem between separately DC bus voltage is improved by using the proposed switching scheme. As a result, the presented inverter configuration not only reduces the system complexity by eliminating the isolation at the AC input side transformer but also improves the dynamic response to the step change of reactive power.