• Journal of Ocean Engineering and Technology
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• v.22 no.6
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• pp.20-26
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• 2008

In this paper, in order to set up the management system of water quality environment in Gwangyang Bay, the cluster analysis of water quality environment, the estimation of inflowing pollutant loads and residence time of pollutants in this bay was carried out. The Gwangyang Bay was divided into eight sea areas by cluster analysis and spatio-temporal change of water quality. The river discharges in the Bay were calculated about $11,681{\times}103m^3/day$ from the numerical simulation by Tank model. In addition, inflowing pollutant loads of COD, SS, TN, TP, DIN and DIP in Gwangyang Bay were estimated at 398 ton-COD/day, 2,846 ton-SS/day, 195 ton-TN/day, 5 ton-TP/day, 126 ton-DIN/day and 3 ton-DIP/day, respectively. Moreover, residence times of COD, TN and TP in the Bay was estimated at 6 days-COD, 20 days-TN and 195 days-TP, respectively in the dry season, and 3 days-COD, 6 days-TN and 21 days- TP, respectively, in the flood season. The central part of Gwangyang Bay (Region IV) has the longest residence time of overall pollutants.

• Journal of The Korean Society of Grassland and Forage Science
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• v.8 no.2
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• pp.68-76
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• 1988

The variation of rumination response in steers fed a same amount of orcharograss hay was investigated. With three steers (6, 12, 24 months) of the Japanese Black Breed, rumination behaviour was measured continuously during a 5 days period by masseter EMG telemetry system. The results are summarized as follows: 1. The average daily ruminatio time of respective animals were 438,447 and 433 min. with small daily variation both within and among animal. But the rumination time per DM kg of hay consumed varied from 66 to 138 min., and calf spent longer than older calf. 2. Actural chewing time showed small variation, and percentage of actural chewing time spent in rumination time was from 88 to 93% on individual average. 3. The daily number of chewing in rumination was approximately 25,000 to 30,000 with large individual differences. The chews per DM kg intake varied from 3,800 to 9,600, and calf chewed more than older calf. 4. The average rate of chewing per 100 sec. (chewing speed), there was a large difference between animals I.e. 104, 114, 131 respectively, but very little variance between days in individual. 5. No relation between day to day variations in eating time and rumination behavior, but significantly positive correlation was observed in the relation among rumination time, chewing time, No. of boluses and No. of chews. 6. Active time of day in rumination altered considerably day to day, but variation in the amount of rumination per day as expressed by the rumination time was relatively small.

• Journal of Labour Economics
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• v.37 no.2
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• pp.49-78
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• 2014

This paper examines the impacts of introducing Five-day school week in South Korean on adolescents' time use. Exploiting the exogenous variation in the adolescents' time at school on Saturday, I estimate the causal effect of change of adolescents' discretion time on their time use. The main findings are as follows. The introduction of the five day school week increased the adolescents' discretion time and their time spent on sleeping, passive leisure(mainly watching television). A one-minute decrease in the adolescents' time at school increase their sleeping time by 0.46 minute and passive leisure time by 0.26 minute.

• Korean Journal of Veterinary Research
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• v.37 no.4
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• pp.899-909
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• 1997

The aim of this study was to assess the estimates of the time of ovulation and mating derived by plasma progesterone concentration. The 40 mature Korea Jin-do bitches were monitored to determine the plasma progesterone concentrations from proestrus to parturition. Gestation length in the 30 pregnant bitches was $63.9{\pm}2.3$ ($mean{\pm}SD$) days in multiparous bitches and $61.8{\pm}3.6$ days in primiparous bitches when Day 0 was timed from the first day of male acceptance, and $61.4{\pm}1.8$ days and $61.3{\pm}2.7$ days when Day 0 was timed from the day of first mating, respectively. Also, gestation length was $63.1{\pm}1.4$ days, $62.4{\pm}1.1$ days and $61.5{\pm}0.9$ days in multiparous bitches, and $62.6{\pm}1.4$ days, $62.4{\pm}2.0$ days and $61.6{\pm}2.3$ days in primiparous bitches when Day 0 was timed from the day that plasma progesterone concentration was first increased above 2.0, 3.0 and 4.0ng/ml, respectively, and $53.8{\pm}3.1$ days and $54.8{\pm}2.6$ days when Day 0 was timed from the last day of male acceptance, respectively. In 30 pregnant bitches, plasma progesterone concentration was $0.2{\pm}0.2ng/ml$ in multiparous bitches and $0.7{\pm}0.8ng/ml$ in primiparous bitches at the first day of vulval bleeding, $1.9{\pm}1.0$ and $3.3{\pm}2.7ng/ml$ at the first day of male acceptance, $7.0{\pm}4.0$ and $9.3{\pm}6.2ng/ml$ at the day of first mating, and $25.1{\pm}6.3$ and $22.8{\pm}10.3ng/ml$ at the last day of male acceptance, respectively. When Day 0 was timed from the day of parturition, plasma progesterone concentration at Day -62, Day -63 and Day -64 was $4.7{\pm}2.7ng/ml$, $3.5{\pm}2.2ng/ml$ and $1.7{\pm}0.9ng/ml$ in multiparous bitches, and $5.3{\pm}4.4ng/ml$, $3.2{\pm}3.7ng/ml$ and $2.0{\pm}1.9ng/ml$ in primiparous bitches, respectively. When Day 0 was timed from the day that plasma progesterone concentration was first increased above 3.0ng/ml after the first day of vulval bleeding, plasma progesterone concentration at Day 61 and Day 62 was $2.7{\pm}2.2ng/ml$ and $1.4{\pm}1.9ng/ml$ in multiparous bitches, and $3.4{\pm}5.2ng/ml$ and $3.7{\pm}5.6ng/ml$ in primiparous bitches, and $0.8{\pm}0.7ng/ml$ and $0.9{\pm}0.4ng/ml$ at Day 63, respectively. It was that bitches were mated when plasma progesterone concentraion was 1.9 to 14.2ng/ml and 3.5 to 20.0ng/ml in multiparous and primiparous bitches, which was between first day before ovulation and fourth day after ovulation. And pregnancy rate was 92% (23/25). From these data, ovulation was estimated to occur the day when plasma progesterone concentration was first increased above 3.0ng/ml after the first day of vulval bleeding. It was estimated that mating time was the day when plasma progesterone concentration was between 1.9 and 20.0ng/ml, and best time for mating was between 3.0 and 8.0ng/ml of plasma progesterone concentration.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.5
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• pp.675-690
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• 2019

Objective: This study investigated the effect of diet and roughage quality (RQ) on dry matter intake, duration and number of daytime and night-time eating bouts, idling sessions and ruminating activities in small ruminants. Methods: In Exp 1 and 2, RQ was improved by urea treatment of veld hay, while diet quality was improved by supplementing with Lucerne hay (Exp 3), sunflower meal and lespedeza (Exp 4), fish meal (Exp 5a), and sunflower meal (Exp 5b). In all experiments goats and sheep were blocked by weight and randomly allocated to experimental diets. Day-time (06:00 to 18:00 h) and night time (18:00 to 06:00 h) feeding behaviour activities were recorded. Results: RQ affected rumination index in Exp 1, but not in Exp 2, 3, and 5. Time spent eating and ruminating was affected by RQ (Exp 1, 3, and 4), period of day (all experiments) and their interaction (Exp 1). Intake rates (g/bout and g/min) were similar across diets. Period of day affected the duration of rumination sessions (Exp 1, 2, and 3); diet or RQ affected the duration of eating bouts (Exp 3) and rumination sessions (Exp 1 and 2). RQ had a significant effect on the duration of eating sessions in Exp 3 only, whilst period of day affected this same behaviour in Exp 2 and 3. Generally, goats and sheep fed on roughage alone ruminate at night and eat more during the day but those fed a roughage and supplemented with Lucerne hay spent more time ruminating than eating. Time spent eating and ruminating had positive correlations to crude protein and feed intake. Intake rates had strong positive correlations to intake. Conclusion: Chewing time, number of eating and ruminating sessions, and duration of eating bouts are physiologically controlled in small ruminants, though chewing time requires isometric scaling during modelling of intake.

• Water for future
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• v.27 no.4
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• pp.135-143
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• 1994

The purpose of this study was to improve the understanding of the characteristics of the daily urban water use. The city of Kwangju in Korea was selected as a study area. The population of Kwangju in the end of 1993 was more than one million and two hundred thousand peoples. The average of daily water use in 1993 was about three hundred and fifty thousand tons a day. The variation of the urban water demand trend with time for a day was studied. One day was devided into 12 divisions with a 2hour increment. The water use demand for the given time interval of a day was observed. The water use index was defind in percentage that indicates the ratio of the amount of water use for a time interval to the amount of water use for a day. The water use index was found to be useful to manage and to operate the water supply systems. In addition to this, the probability distribution of the water use demand for each time interval was tested using the K-S(Komogorov-Smirnov) method. The normal distribution type was found to be appropriate as the probability distribution type for the variation of water demand for the given time interval of a day.

• Korean Journal of Animal Reproduction
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• v.16 no.3
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• pp.231-237
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• 1992

The effects to the corticosteroid dexamethasone(DEX) and(or) estradiol-benzoate(E-B) treated to induction of parturition and birth weights of the young was conducted in 48 pregnant Korean native goats. The animals were divided into 4 goats per each treatment by the time(142, 145 and 148 day of pregnancy) and dosage(DEX 15, 20mg, DEX 8mg＋E-B 10mg and DEX 13mg＋E-B 7.5mg per goat). The results obtained were summarized as follows: 1 The time for induction of parturtion after DEX(15, 20mg) treatment on day 148 of pregnancy was significantly(P<0.01) shorter than 142 and 145 days. There was no significant difference each dosage of DEX on same day of pregnancy. 2. The addition of E-B to DEX treatment compared with DEX alone group at day 142 and 145 of pregnancy were significantly(P<0.01) shorter the time for induction of parturition. However, treatment with DEX along or with E-B on 148 day of pregnancy did not affect the time to induction(about 27 hrs) of parturition between each treatment. 3. The birth weight of kids after parturition was heaviest(P<0.01) on day 148 of pregnancy. However, development and vigor of kids were not significant different between DEX alone treatment and with E-B.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.11
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• pp.1828-1832
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• 2018

Objective: Environmental change is one of the stressful events in livestock production. Change in environment disturbs cow behavior and cows require several days to regain a stable behavioral pattern. Sleeping posture (SP) and lying posture (LP) have been used as indicators for animal that are relaxed and well-acclimated to their environment. The aim of this study was to examine the time required by Japanese black cows for stabilization of SP and LP after moving into new environment. Methods: Seven pregnant Japanese black cows were used. Cows were moved into new tie-stall shed and their sleeping and lying posture measured 17 times during 35 experimental days. Both SP and LP were detected by accelerometer fixed on middle occipital and hip-cross, respectively. Daily total time, frequency, and average bout of both SP and LP were calculated. Results: Daily SP time was the shortest on day 1 and increased to the highest on day 3. It then decreased until day 9, after that stabilized about 65 min/d till the end of experiment. Daily LP time changed in same manner as daily SP time. The average SP bout was the longest on day 1, and then decreased to stable level on day 7. On the other hand, the average LP bout was the shortest on day 1, and it increased to stable level on day 7. Conclusion: These results showed that pregnant Japanese black cows needed 1 week to stabilize their SP. However, there were different change patterns between the average SP and LP bout, even though the change pattern of daily SP and LP time were similar.

• Journal of Embryo Transfer
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• v.21 no.3
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• pp.207-216
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• 2006

Vaginal cytology was examined in 12 Shih-tzu bitches to establish the accurate basic data for estimate to the optimal mating time and ovulation time. The mean duration of proestrus and estrus were $9.09{\pm}0.83\;(mean{\pm}SD)$ days and $7.36{\pm}0.47$ days in pregnant bitches. The gestational length in the 12 pregnant bitches was $65.2{\pm}0.5$ days in pregnant bitches when Day 0 was timed from the first day of male acceptance. Characteristic features of vaginal cytology during the estrous cycle were the high proportion of large intermediate cell, superficial cell, anuclear cell and erythrocyte in proestrus, superficial cell, anuclear cell and erythrocyte in estrus, and parabasal cell, small and large intermediate cell and leukocyte in diestrus, respectively. Cornification index (CI) was the high proportion in proestrus and estrus, then it decreased in diestrus and anestrus. When Day 0 was timed from the day of the first male acceptance, the CI peak was Day 2 and maintained above 80% between Day -4 and Day 6 during 11 days, and above 90% between Day -1 and Day 5 during 7 days. In relationship between CI and reproductive hormones, CI showed peak at the first day after plasma estradiol-$17{\beta}$ concentration peak and plasma progesterone concentration was first increased above 4.0 ng/ml at Day 0 which was the first day after CI peak. In conclusion, ovulation in Shih-tzu bitches occurred at the first day after CI peak. Vaginal cytology is the simple and reliable method for estimating estrous cycle, optimal breeding time and ovulation time in Shih-tzu bitches.

• Journal of Korean Biological Nursing Science
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• v.25 no.2
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• pp.123-130
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• 2023

Purpose: Sitting time, smoking, and perceived stress strongly influence physical health independent of physical activity. However, the associations among perceived stress, sedentary behavior, and smoking are poorly understood. Therefore, we examined the relationships between sitting time, smoking, and perceived stress in Korean adults aged < 65 years. Methods: We analyzed data from the seventh National Health and Nutrition Survey. In this cross-sectional study, data from 6,890 Korean adults aged < 65 years were analyzed. Complex-sample logistic regression was used to examine the relationships between sitting time, smoking, and perceived stress. Results: The group with a high sitting time (≥ 8 h/day) and those who smoked had significantly higher odds of experiencing stress than the low sitting time (< 8 h/ day) and non-smoking groups (odds ratio: 1.88, 95% confidence interval: 1.42-2.50). Conclusion: Perceived stress was positively correlated with current smoking status and increased sitting time. High sitting time (≥ 8 h/day) and current smoking were associated with a higher risk of perceived stress in Korean adults aged < 65 years.