• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.97-103
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• 2006

A modified one-sided measurement technique is proposed for Rayleigh wave (R-wave) velocity measurement in concrete. The scattering from heterogeneity may affect the waveforms of R-waves in concrete, which may make the R-waves dispersive. Conventional one-sided techniques do not consider the scattering dispersion of R-waves in concrete. In this study, the maximum energy arrival concept is adopted to determine the wave velocity by employing its continuous wavelet transform. Experimental study was performed to show the effectiveness of the proposed method. The present method is applied to monitor the strength development of early-age concrete. A series of experiments were performed on early-age concrete specimens with various curing conditions. Results reveal that the proposed method can be effectively used to measure the R-wave velocity in concrete structures and to monitor the strength development of early-age concrete.

• Wind and Structures
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• v.21 no.3
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• pp.289-309
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• 2015

Vertical profiles of mean and fluctuating wind velocities over water waves were studied, by performing Large-Eddy Simulations (LES) on a fully developed turbulent boundary layer over simplified water waves. The water waves were simplified to two-dimensional, periodic and non-evolving. Different wave steepness defined by $a/{\lambda}$ (a : wave amplitude; ${\lambda}$ : wavelength) and wave age defined by $c/U_b$ (c: phase velocity of the wave; $U_b$ : bulk velocity of the air) were considered, in order to elaborate the characteristics of mean and fluctuating wind profiles. Results shows that, compared to a static wave, a moving wave plays a lesser aerodynamic role as roughness as it moves downstream slower or a little faster than air, and plays more aerodynamic roles when it moves downstream much faster than air or moves in the opposite direction to air. The changes of gradient height, power law index, roughness length and friction velocity with wave age and wave amplitude are presented, which shed light on the wind characteristics over real sea surfaces for wind engineering applications.

• The Journal of Internal Korean Medicine
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• v.33 no.3
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• pp.257-271
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• 2012

Objectives : The purpose of this study was to confirm that the pulse analyzer is useful for analyzing characteristics of variables of pulse waves in age categories, evaluating pulse waves of the metabolic syndrome group, compared with those of the non-metabolic syndrome group in Korean adults. Methods : The pulse wave variables were measured in Guan of all 1,056 subjects by the pulse analyzer, using a pen-type piezoresistive sensor. The physical measurement, blood test and survey were also performed by each subject. Results : In the age categories, height of pre-incisura (h2), height of tidal wave (h3), area of percussion wave (Aw), and width of percussion wave (w) increased in accordance with increase in age. While ratio of systolic period area (As) went up according to the increase of age, ratio of diastolic period area (Ad) went down. Radial augmentation index (R-AI), h2/h1, h3/h1, w/t and angle of percussion wave went up by aging, generally. Aw rate (Aw/At) also increased. Among the metabolic syndrome group, in the ages of 19 and 44, ratio of systolic period area (As) was higher and ratio of diastolic period area (Ad) was lower than in the non-metabolic group. w/t, Aw/At, and angle of percussion wave were higher than in the non-metabolic syndrome group. Among the metabolic syndrome group over the age of 60, height of pre-incisura (h2), height of tidal wave (h3), total area (At), area of percussion wave (Aw), radial augmentation index (R-AI), h2/h1 and h3/h1 were higher than in the non-metabolic syndrome group. Conclusions : The pulse analyzer is useful to analyze arterial stiffness in the age categories and in the metabolic syndrome group by some measures.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.3
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• pp.551-557
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• 2011

The purpose of this study is to investigate the relation between brachial-ankle pulse wave velocity and the features of metabolic syndrome, and differences according to sex in patients diagnosed cerebral infarction. The study group comprised 61 patients over age 30 who were diagnosed cerebral infarction, accompanied with metabolic syndrome. The brachial-ankle pulse wave velocity, blood pressure, lipid profiles, fasting blood glucose, body mass index were measured. Also we checked past history of patients. Then we analyzed the association between brachial-ankle pulse wave velocity and the features of metabolic syndrome. Pearson correlation analysis reflected the variables affecting the brachial-ankle pulse wave velocity as follows : Age, SBP(systolic blood pressure), DBP(diastolic blood pressure), FBS(fasting blood glucose) were positively correlated. As a result of regression analysis, in patients with cerebral infarction accompanied with metabolic syndrome, the brachial-ankle pulse wave velocity is affected by age to men, SBP, FBS, DBP to women. The brachial-ankle pulse wave velocity is not affected by the components of metabolic syndrome, except blood pressure, FBS, in patients with ischemic stroke.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.2
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• pp.31-38
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• 2020

Controlled Low Strength Material (CLSM) has high fluidity and self-compaction characteristics. CLSM is mainly used for backfilling the excavated road. Early-age properties of CLSM should be characterized for fast restoration of the road. In this study, shear wave monitoring and Vicat needle test are performed to investigate the early-age properties of CLSM depending on the setting time. CLSM consists of CSA cement, fly ash, silt and sand, accelerator, and water. Five fly ashes with different chemical properties are used for CLSM samples. The penetration of CLSM along setting time is obtained through the Vicat needle test. A pair of bender elements are placed in a mold for shear wave measurement, and the change in shear waves with the setting time is monitored. The experimental results show that, regardless of the type of fly ash, the penetration depth decreases and the shear wave velocity increases with the setting time. Depending on the type of fly ash, initial and final times and shear wave velocity change. After testing, the correlation between penetration and shear wave velocity is obtained with high coefficient of determination. The shear wave measurement technique using the bender element can be used to identify early-age properties.

• Journal of Korea Multimedia Society
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• v.23 no.7
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• pp.862-869
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• 2020

This study attempted to analyze human brain responses toward visual content through EEG signals and intended to measure brain wave reactions of different age groups to determine the sexuality level of the media. The experimental stimuli consist of three different video footage (rated ages 12, 15, and 18) to analyze how subjects react in situations where they actually watch sexual content. For measuring and analyzing brain wave reactions, EEG equipment records alpha, beta, and gamma wave responses of the subjects' left and right frontal lobes, temporal lobes, and occipital lobes. The subjects of this study were 28 total and they are divided into two groups. The experiment configures a sexual content classification scale with age or gender as a discriminating variable and brain region-specific response frequencies (left/right, frontal/temporal/occipital, alpha/beta/gamma waves) as independent variables. The experimental results showed the possibility of distinguishing gender and age differences. The apparent differences in brain wave response areas and bands among high school girls, high school boys, and college students are found. Using these brain wave response data, this study explored the potential of developing algorithm for measurement of age-specific responses to sexual content and apply it as a film rating.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.544-550
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• 1997

In this study, the advanced on-sided stress wave velocity measurement method was applied to investigate the effects of composition, age and moisture content in concrete. Two concrete specimens that have different composition were used to figure out the change of the Longitudinal and Surface wave velocity due to different composition. The other concrete specimen was cast and the Longitudinal and Surface wave velocity was monitored during curing process. After 28-day old, the effect of moisture content in the concrete specimen to the stress wave velocity is presented in this paper during the time period 43-74 days after casting. For drying process. an aggregate drying oven was used. A conventional ultrasonic through transmission method was used to compare with the results determined by the one-sided method.

• Management & Information Systems Review
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• v.36 no.2
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• pp.21-35
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• 2017

The Korea Wave has been spread out all over the world since 1990s. Therefore, it can be seen that the Korea wave phenomenon is one of determinants of international tourism demand for Korea in addition to the macro factors such as population, GDP per capita, exchange rate, distance, etc. Existing studies have focused on analyzing the impacts of the Korea wave on the international tourism demand for Korea by using the aggregated data. However, the impacts of the Korea wave inducing tourism vary in different age groups. In this study, we conduct empirical analysis in order to explore how different the effects of Korea wave on the demand of foreign tourists visiting to Korea in different age groups are. The estimation results show that the Korea Wave influences most on international tourism demand for Korea in the age group of the under-20s. Noticeable is that the estimated effects of the Korea Wave on international tourism demand for Korea in the age group of the over-50s are higher than those in the 30s and 40s. This indicates that the parent generations visit Korea together with their young children who are most affected by the Korea Wave. Through this study, it is necessary to develop strategies for tourism marketing linked to children and parents, and to develop tourism products to increase the number of foreign visitors to Korea in the 30s and 40s.

• Korean Journal of Childcare and Education
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• v.20 no.1
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• pp.39-53
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• 2024

Objective: The purpose of this study is to investigate whether emotionality at age three predicts early school-age media overdependence and to examine the potential mediating role of internalizing behavior problems in children. Methods: This study employed data from the 4th and 10th waves of the Panel Study of Korea Children, comprising a sample of 1,270 children. Assessments of emotionality (4th wave), media overdependence (10th wave), and internalizing behavior problems (10th wave) were conducted. Data analysis utilized SPSS and the Process Macro. Results: At age 3, heightened emotionality was found to directly contribute to an increased tendency for media overdependence in early school age. Internalizing behavior problems played a significant mediating role in the relationship between emotionality and media overdependence. Conclusion/Implications: This study validated a significant longitudinal connection between emotionality and the inclination to excessively rely on media, highlighting the role of internalization behavior problems in this relationship. It is essential to provide focused attention, especially to children displaying heightened emotionality in early childhood, in order to proactively prevent internalization behavior problems and the undue dependence on media.

• Journal of Preventive Medicine and Public Health
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• v.39 no.3
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• pp.221-228
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• 2006

Objectives: The purpose of this study was to shed further light on the effect of modifiable health behavior risk factors on dependence in activities of daily living, defined in a multidimensional fashion. Methods: The study participants were 10,278 middle aged Americans in a longitudinal health study, the Health and Retirement Survey (HRS). A multi-stage probability sampling design incorporating the effect of population sizes (Metropolitan and non-metropolitan), ethnicity (the non- Hispanic White, the Hispanic, and the Black), and age (age 51-61) was utilized. Basic Activities of Daily Living (ADL) were measured using five activities necessary for survival (impairment in dressing, eating, bathing, sleeping, and moving across indoor spaces). Explanatory variables were four health behavior risk factors included smoking, exercise, Body Mass Index (BMI), and alcohol consumption. Results: Most participants at baseline were ADL independent (1992). 97.8% of participants were independent in all ADL's at baseline and 78.2% were married. Approximately 27.5% were current smokers at baseline, and the subjects reported moderate or heavy exercise were 74.8%. All demographic characteristics and behavioral risk factors were significantly associated with the ADL status at Wave 4 except alcohol consumption. Risk behaviors such as current smoking, sedentary life style and high BMI at Wave 1 were associated with ADL status deterioration; however, moderate alcohol consumption tended to be more related to better ADL status than abstaining at Wave 4. ADL status at Wave 1 was the strongest factor and the next was exercise and smoking affecting ADL status at Wave 4. People who were in ADL dependent at Wave 1 were 15.17 times more likely to be ADL dependent at Wave 4 than people who were in ADL independent at Wave 1. Concerning smoking cigarettes, people who kept only light exercise or sedentary life style at Wave 1 were 1.70 times more likely to be died at Wave 4 than the people who did not smoke at Wave 1. Conclusions: All demographics and health behaviors at wave 1 had consistently similar OR trends for ADL status to each other except alcohol consumption. Smoking and exercise in health behaviors, and age and gender in demographics at Wave 1 were significant factors associated with ADL group separation at Wave 4.