• Asian-Australasian Journal of Animal Sciences
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• v.7 no.2
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• pp.273-277
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• 1994

A $3{\times}3$ latin square design experiment was conducted to study eating and rumination behavior in sheep fed rice straw (RS) supplemented with soybean meal (SBM) and barley at three different levels of crude protein: low (40 g CP/d, LCP), medium (67 g/d, MCP) and high (94 g/d, HCP). In addition, all the supplements were formulated to contain the same amount of total digestible nutrients (TDN; 275 g). Daily time spent eating and eating rate of RS were not affected by any supplementation. However, time spent ruminating in sheep fed HCP diet was markedly shorter (p<0.05) than in those fed LCP and MCP diets. Rumination index (ruminating time/100 g DM intake) was also significantly reduced (p<0.05) by increasing level of protein supplementation. Although no significant differences were observed, the daily number of rumination periods tended to be lower, while daily number of boli regurgitated was considerably higher in sheep fed HCP diet than in those fed LCP and MCP diets. Increasing level of protein supplementation did not affect the number of chews per bolus, bolus time and rate of chewing during rumination. It is suggested that increasing level of protein supplementation was associated with more effective microbial reduction of rumen digesta particle size and consequently reduced the time spent ruminating.

• Journal of Biosystems Engineering
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• v.16 no.1
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• pp.37-48
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• 1991

Rice plants are subjected to various forces such as natural force of wind and mechanical force of cultivating machines. Rheological behavior of the rice stem can be expressed in terms of three variables : stress, relaxation and time. The objectives of this study are to examine stress relaxation, creep and recovery characteristics on the rice stem in case of axial and radial loading. Stress relaxation with time was studied on three levels of loading rate and on four levels of applied stress. The results were summarized as follows : 1. The hysterisis losses of the rice stem distinctly observed at the radial compression in comparison with axial compression. The hysterisis loss implied that the stem to absorbed energy without being deformed beyond the yield point. 2. Ageneralized Maxwell model consisting of three elements gave a good description of the relaxation behavior of the rice stem. Rate of loading was more significant on the observed relaxation behavior within the short relaxation time, but there were little influences of rate of loading on the relaxation time. 3. The stress relaxation intensity and the residual stress increased in magnitude as the applied stress increased, but the relaxation time was little affected by the applied stress. 4. The coefficients of the stress relaxation model showed much differences in the radial compression and the axial compression, especially the higher relaxation stress of the third element was observed in the radial compression. 5. The behaviors of rice stem in creep and recovery test also might be represented by a four element Burger's model. But the coefficients of the creep model were different from those of the recovery model. 6. The steady-state phenomena of creep appeared at the stress larger than 20 MPa in Samkang and 1.8 MPa in Whajin. 7. The elastic modulus of the stem showed the range from 40 to 60 MPa. It could be considered, as a result, the rice stems had viscoelastic properties.

• Journal of the Society of Naval Architects of Korea
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• v.38 no.4
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• pp.39-47
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• 2001

In this paper, the hydroelastic behavior of a mat-type large floating structure is analyzed in time domain by using mode superposition method. The time-memory function is estimated by Fourier transforming the wave damping coefficients, which are computed by a higher-order boundary element method based on potential theory. Meanwhile, the structural response is obtained by time integrating the eigenmodes of the structure. Numerical examples are made for three test cases on the scaled model of a mat-type large floating structure ; weight pull-up case, weight drop case and weight moving case. In all three cases, the numerical results coincide well with experimental data.

• Journal of Korean Biological Nursing Science
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• v.19 no.4
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• pp.276-283
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• 2017

Purpose: The aim of this study was to identify the effects of environmental factors on depressive-like behavior and memory function during adolescence. We performed behavior tests in adolescent rats exposed to environmental enrichment, handling, and social deprivation for eight weeks. Methods: Wistar rats were randomly assigned to control, environmental enrichment, handling, and social deprivation groups at the age of four weeks. Results: In the forced swim test, the immobility time in the environmental enrichment group was decreased than that in the control group (p=.038), while the immobility time in the social deprivation group was increased than that in the control group (p=.035), the environmental enrichment group (p<.001), and the handling group (p=.001). In the Morris water maze test, the social deprivation group had an increased latency time than the control group (p=.013) and the environmental enrichment group (p=.001). In the passive avoidance test, the environmental enrichment group had an increased latency time than the control group (p=.005). However, the social deprivation group had reduced latency time than the socially housed groups (control: p=.030; environmental enrichment: p<.001; handling: p<.001). Conclusion: These findings suggest that environmental factors play an important role in emotion and memory function during adolescence.

• Korean Journal of Community Nutrition
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• v.23 no.3
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• pp.193-201
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• 2018

Objectives: This study was conducted to measure the intake rate of SSBs (sugar sweetened beverages) and examine the relationship between health behavior factors and SSBs intake by adolescents. Methods: This study used data from the 2016 Korea Youth Risk Behavior Web-based Survey, which included 65,528 study participants. SSBs intake frequency was measured by asking respondents if they consumed soda, high-caffeinated beverages, and sugary drinks during the previous week. Type of intake was categorized into three groups according to the number of consumed drinks [SSBs (0): None; SSBs (1-2): 1 or 2 consumed; SSBs (3): 3 consumed]. Multinomial logistic regression analysis was used to examine health behaviors that affected SSBs consumption. Results: Increased SSBs intake was significantly correlated with current smoking (OR=2.4, 95% CI=1.82-3.17), current drinking (OR=2.13, 95% CI=1.82-2.51), sedentary time increase (OR=1.31, 95% CI=1.15-1.49), three days or more physical activity per week (OR=1.12, 95% CI=1.02-1.24), <8 hours sleep (OR=1.6, 95% CI=1.43-1.78), increased internet usage time (OR=1.44, 95% CI=1.25-1.65). Conclusions: Sugar-sweetened beverages intake by Korean adolescents was associated with health behaviors such as smoking, drinking, sedentary time increase, more physical activity, poor sleeping time, and increased internet use time. Based on these results, it is necessary to recognize the influence of SSBs intake and to intervene to reduce consumption of SSBs.

• Korean Journal of Community Nutrition
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• v.28 no.5
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• pp.363-375
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• 2023

Objectives: The objective of this study was to identify factors associated with adolescent obesity, as well as any new factors that correlated with a change in the rate of obesity over time. Methods: The study used 5-yearly data collected by the Korea Youth Risk Behavior Survey starting from the year 2006 up until 2021 (data from 2nd, 7th, 11th, and 17th surveys were analyzed). Factors such as demographics, dietary factors, health behavioral factors, and mental health factors were studied. All data were analyzed using IBM SPSS 27.0, employing chi-square tests and multiple logistic regression analysis. Results: This study included data from a total of 255,200 participants. Factors contributing to obesity varied with time. Over the survey duration of 15 years, low academic achievement, parents with low levels of education, low frequency of fruit consumption, low frequency of fast food intake, long periods of being seated, and high levels of stress were significantly associated with a high rate of obesity. Factors that showed a new correlation with an increase in obesity rates included living with single parents, low frequency of muscle strengthening exercises, and experiencing intense sadness and despair in the past year. Factors that were correlated with a change in obesity rates over time included household economic status, frequency of carbonated beverage consumption, frequency of intense physical activity, and frequency of alcohol consumption. Breakfast intake and smoking were not significantly associated with obesity rates in the 15-year period. Conclusions: While several factors associated with obesity remained consistent over time, several new factors have emerged in response to social, economic, and environmental changes contributed to a change in obesity rate over time. Therefore, to prevent and manage adolescent obesity, continuous research into the new emergent factors contributing to obesity is needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4621-4631
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• 2015

The purpose of this study is to find the grounds for nursing students and teaching professors to confirm the importance of planning and preparing academic careers according to proper time management by determining the learning style exactly for themselves. For this purpose we investigated the learning style and time management behavior of the nursing student in university. The data was collected for 1 months from Nov. 1 to Dec. 2, 2013 in four universities which located in D city and C province. The research tool were used to measure of the learning style, time management behavior and self-directed learning. The participants were 246 nursing students at university who understand the purpose of study and agree to answer it. The data was analyzed by descriptive statistics, t-test, ANOVA, Pearson's correlation, stepwise regression using the IBMSPSS/WIN 19.0 program. The result of this study was that the predicting factors for self-directed learning were time management behavior(${\beta}=.629$, p<.001) and adjustment to university life(${\beta}=.153$, p<.001). The variables explained the self-directed learning by 51.4%. This study shows that professors have to encourage students to realize the importance of effective time management for planning, performing and evaluating the academic career for themselves and take into account the related programs about self-directed learning.

• Journal of the Ergonomics Society of Korea
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• v.31 no.5
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• pp.647-655
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• 2012

Objective: The purpose of this study was to confirm difference between angular foot movement time and existing foot Fitts' law predicting times, and to develop the angular foot Fitts' law in the foot tapping task. Background: Existing studies of foot Fitts' law focused on horizontal movement to predict the movement time. However, when driving a car, humans move their foot from the accelerator to the brake with a fixed heel. Therefore, we examined the experiment to measure angular foot movement time in reciprocal foot tapping task and compared to conventional foot Fitts' law predicting time. And, we developed the angular foot Fitts' law. Method: In this study, we compared the angular foot movement time in foot tapping task and the predicted time of four conventional linear foot Fitts' law models - Drury's foot Fitts' law, Drury's ballistic, Hoffmann's ballistic, Hoffmann's visually-controlled. 11 subjects participated in this experiment to get a movement time and three target degrees of 20, 40, and 60 were used. And, conventional models were calculated for the prediction time. To analyze the movement time, linear and arc distance between targets were used for variables of model. Finally, the angular foot Fitts' law was developed from experimental data. Results: The average movement times for each experiment were 412.2ms, 474.9ms, and 526.6ms for the 89mm, 172mm, and 253mm linear distance conditions. The results also showed significant differences in performance time between different angle level. However, all of conventional linear foot Fitts' laws ranged 135.6ms to 401.2ms. On the other hand, the angular foot Fitts' law predicted the angular movement time well. Conclusion: Conventional linear foot Fitts' laws were underestimated and have a limitation to predict the foot movement time in the real task related angular foot movement. Application: This study is useful when considering the human behavior of angular foot movement such as driving or foot input device.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.4
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• pp.563-576
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• 2011

The purpose of this study was to investigate night-time eating habits, and dietary habit and nutrient intake of university students in a particular area of Chungnam. We surveyed night-time eating status, frequency, and preference for eating foods at night in 458 university students. We divided the subjects into two groups according to their night-time eating habits and gender and compared dietary behavior, lifestyle, and nutrient intake between the groups. In total, 77.1% of the students ate a night-time snack. The major reason why they ate a night-time snack was hunger. The cost of the night-time snacks was 3,000~10,000 won and they ate mostly with their friends. The order of frequent night-time eating foods was beverage, milk and its products, snacks, flour foods, and fruits. The subjects with a night-time eating habit skipped breakfast, went to bed late, and drank alcohol more than subjects without a night-time eating habit. Total and animal fat intake of subjects with a night-time eating habit in both men and women were significantly higher than subjects without a night-time eating habit. In conclusion, night-time eating by university students may be a bad habit from the viewpoint of skipping breakfast, drinking alcohol, and eating a high fat diet. Therefore, in support of proper dietary management, it is necessary to form positive dietary habits, including night-time eating.

• Korea journal of population studies
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• v.34 no.2
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• pp.65-90
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• 2011

This study aims to investigate how labour time pressure is associated with leisure selection and managing leisure hours, especially focusing on health related behavior issues. I have employed Time Diary data of 9,891 Korean respondents who were married and living in the cities and metropolitan area (female 51.8%, age range 20-69, average age=45.7). Leisure activities, as dependent variable, which were introduced in time diary data and the amount of time spent for such leisure were estimated. Results show that in time pressing situations(having long labour hours), leisure activities, and the hours spent for leisure tend to suffer. Especially, solitary leisure, like exercise or walking was very likely to sacrifice under time pressure. Moreover, in terms of sports or exercise, results suggest that not only time resource but also social and economic resources seemed to required for actually initiating the activity. Therefore, simply having more time (less tiome for work) may not be enough for promoting exercise for this population. Strategies and social policies that are aiming for promoting healthy behavior needs more closer look on leisure situation and people's desire for optimizing their time.