• Toxicological Research
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• v.19 no.2
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• pp.123-131
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• 2003

This study was carried out to assess the combined repeated dose, reproduction and developmental toxicities of benzoyl peroxide for OECD SIDS (Screening Information Data Set) program. Male and female Sprague-Dawley rats were exposed to benzoyl peroxide at dose levels of 0, 250, 500 and 1,000 mg/kg/day for 29 days for males and for 41-51 days for females. No deaths were found in all animals including control group during exposure period. No hematological effects attributable to benzoyl peroxide were observed in all treated groups. Significant decrease in the weight of testes and epididymis were observed in males at 1,000 mg/kg/day. In females at 1,000 mg/kg/day, slight histopathological effects in uterus such as epithelial vacuolation or hyperplasia were observed. No treatment-related changes in precoital time and rate of copulation, fertility and gestation period were noted in all treated groups. There was no evidence of teratogenic effect of benzoyl peroxide, but body weight of pups at 1,000 mg/kg/day was significantly decreased. NOAEL for combined repeated dose and reproduction/developmental toxicity was 500 mg/kg/day.

• Journal of the Korean Home Economics Association
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• v.49 no.5
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• pp.11-22
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• 2011

This study aimed to suggest more appropriate and accurate festival costumes based on a comparative analysis on various reproduced costumes and a period review of traditional festival costumes. In particular, the comparative analysis examined festival costumes which appeared in Korean and Japanese festival parades during the Baekje Period. The Baekje Cultural and Sacheonwangsawasso Festivals were examined. A literature review as well as field research and digital restorative techniques were used in the study. The reproduction patterns of Baekje costumes from both festivals were compared with original Baekje costumes, demonstrating several differences in the configuration, material, color, and shape of the costumes in addition to the way they were worn. Based on the comparative analysis, Baekje costumes used in Festivals were grouped into three categories: King's Costume, Queen's Costume, and Government Official's Costume. Dress sketches and 3D illustrations also have been presented.

• Physical Therapy Korea
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• v.14 no.3
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• pp.16-22
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• 2007

The purpose of this study was to determine the influence of muscle fatigue in elbow flexors on the sense of force reproduction. Fifteen healthy subjects were recruited for this study. Maximum voluntary force (MVF) of elbow flexor muscles was measured by a digital tensiometer. Force errors were measured to test accuracy of the sense of force reproduction in elbow flexors. The subject was required to flex the elbow joint, to maintain and concentrate on about 20% of the MVF target force under visual feedback for 3 seconds. After a 5 second period rest, the subject was asked to duplicate the target force actively. Muscle fatigue was evoked with isometric contraction of the elbow flexors. Isometric contraction was continued until a 50% drop in MVF. The difference, in kilogram between the target force and the reproduced force was calculated for measuring force error. Force errors were compared between the non-fatigued condition and the fatigued condition by the paired t-test. Force errors were significantly increased in the fatigued condition compare to non-fatigued condition. This result suggests that the sense of force reproduction can be disturbed by localized muscle fatigue.

• Journal of agricultural medicine and community health
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• v.47 no.2
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• pp.61-66
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• 2022

Objectives: In the epidemiology of communicable diseases, the term epidemic period, also referred to as "wave" is often used in the general and academic milieu. A wave refers to a natural pattern of increase in the number of sick individuals, a defined peak, and then a decline in the number of cases. It implies a pattern of peaks and valleys after a particular peak is taken. The idea of epidemic waves is a useful tool for predicting the course as well as helping to accurately describe an epidemic. However, in many domestic and foreign news as well as in various research results in Korea, most of the reports either had no standard, were inaccurate, had a questionable classification of the period of the epidemic, or the basis for classification of a given wave was not presented. Methods: The author reviewed and organized related literature with epidemic wave. The author made several suggestions of an epidemic wave as follows. Results: To start with, it should be based on the number of incident cases in consideration of the size of the outbreak, then the period from the bottom to the peak and then reaching the next bottom; also, the period over a certain scale based on the number of incident cases; and the period according to the change in the major infection type (mutation-dominant species). In addition, according to the period of change in the vaccination rate (formation of herd immunity), as well as the content and duration of the intervention, that is, classification according to the applied quarantine stage. Furthermore, the classification of epidemic periods by the time-dependent reproduction number or time-varying reproduction number (Rt), and lastly the application of mathematical methodology. Conclusions: Therefore, classifying the epidemic period into generally known and accepted time frames is considered to be a very important task for future research analysis and development of intervention strategies.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.186-194
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• 2000

In this study, the oceanic responses to given atmospheric boundary conditions are investigated using a mesoscale ocean circulation model. The numerical experiments are divided into two parts: One is, so called, spin-up experiment and the other is reproduction experiment. The spin-up experiment simulates climatic state of ocean by integrating the ocean model with upper boundary conditions of the monthly mean atmospheric climate data. In the reproduction experiment, for the reproduction of major oceanic changes around Korean Peninsula during the period of 1980-1998 (19 years), the model has been integrated under the boundary condition of the 19year monthly mean atmosphere data. The spined-up state of ocean generated from the spin-up experiment is assigned to the initial boundary condition of the reproduction experiment. In the spin-up experiment, the model properly simulates the major features of circulation structure around Korean Peninsula; such as separation of East Korean Warm Current (EKWC), formation of the polar front, cold water band associated with the small scale eddies in the East Sea, the formation of front along west coast, and the seasonal variation of circulation pattern caused by changing upwind current in the West Sea. In the reproduction experiment, the model has shown the interannual sea surface temperature variations and a warming trend of about 0.5$^{\circ}$C during the period around Korean Peninsula, as in the case of the observation. Therefore, it is concluded that the model is capable of simulating not only the mean states but also the variabilities of ocean under the given atmosphere boundary conditions.

• Journal of the Korean Society of Food Science and Nutrition
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• v.7 no.1
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• pp.19-23
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• 1978

The influence of low temperature treatment on Raphanus sativus L, stimulating the conversion of sexual reproduction period over vegetative reproduction period. was verified by the research of many scholars, and the low temperature limit and the time period to obtain the desired results were reported by Miller and Yamamoto et al. This paper will report the results of an experiments as to determine the proper temperature regulation period by determining the sensitivity stimulation period during the growing period of plants. Since the results of this paper alone are inconclusive. further research will be carried out and reported in the future by this author.

• Korean Journal of Animal Reproduction
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• v.22 no.4
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• pp.303-306
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• 1998

This study was carried out to investigate the effect of time of feeding to pregnant holstein cows on calving time during a day. The investigation revealed that feeding at 18:00∼04:30 resulted in 87.8%(9＋15h) and 80.7% (12＋12h) of the cows calving, whereas the traditional 08:00 and 18:00 feeding resulted in 57.9%(9＋15h) and 51.8%(12＋12h) of them calving during the day period(p＜0.001). Especially, between 06:00∼11:00 and 16:00∼17:00, 38.5% and 19.6% of cows calving during the day period were investigated.

• Korean Journal of Animal Reproduction
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• v.17 no.3
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• pp.209-220
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• 1993

This study was attempted to investigate the processes of regression of the corpus luteum and uterus after parturition in 2∼3 multiparous Korean native goats. The concentrations of LH, prolactin and progesterone in blood plasma of native goats were measured at 5 day intervals from 10 days prepartum to 35 days postpartum. The pregnancy corpus luteum from goats at Days(D) 1, 10, 20 and 30 days of postpartum were examined by light microscopy. Changes in the uterus fo goats were studies by macroscopic and light microscopic observations during the postpartum period. Mean concentrations of plasma LH were low after parturition and the levels of plasma LH were similar during late gestation and throughout the postpartum period. Mean plasma concentrations of prolactin were 0.30 0.06 and 0.38 0.13ng/ml at Day 5 and Day 10 prepartum, respectively, but PRL levels remained slightly high for 5 weeks after kidding. Mean levels of progesterone in plasma were 0.33 0.05ng/ml on Day 1 postpartum(P<0.01). Through light microscopic survey, pregnancy corpora lutea were quite degeneration by day 10 pospartum. Microscopic changes of CL regression consisted of cytoplasmic eosinophilia and vacuolation, and pyknosis and karyorrhexis of the nucleus of luteal cells. Vascular changes were distended at the periphery ofthe CL. From macroscopic measurements of the uterus, the uteri were returned to their initial non-pregnant stage within a period of 21 dyas after parturition. Following partuition the intercaruncular epithelium was reparied by 20 days. The uterine epithelium was partially recovered in the carucle by 30 days postpartum.

• Development and Reproduction
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• v.25 no.4
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• pp.299-303
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• 2021

The ascidian Halocynthia aurantium (sea peach), a marine invertebrate, belongs to the same genus of the phylum Chordata along with the ascidian Halocynthia roretzi (sea pineapple), which is one of the model animals in the field of developmental biology. The characteristics of development and reproduction of H. aurantium are not yet known in detail. In order to find out the spawning period of H. aurantium, we investigated development of the gonads during the annual reproductive cycle. Testis and ovary were both in the bisexual gonads (ovotestes) of H. aurantium, which is a hermaphrodite like H. roretzi. In H. aurantium, the right gonad was longer and slightly larger than the left gonad throughout the year. In each gonad, the number of the testis gonoducts was slightly higher than that of the ovary gonoducts. These features were similarly observed in H. roretzi. However, the number of the testis gonoducts and the ovary gonoducts in each gonad of H. aurantium was about half that of H. roretzi. The gonads of H. aurantium contracted during the winter and summer seasons. The gonads decreased to the smallest size around February, and then started to increase again in March. The gonads were most developed in September of the year. Therefore, it is estimated that the spawning of H. aurantium begins around this period.

• Journal of Preventive Medicine and Public Health
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• v.53 no.6
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• pp.405-408
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• 2020

In epidemiology, the basic reproduction number (R₀) is a term that describes the expected number of infections generated by 1 case in a susceptible population. At the beginning of the coronavirus disease 2019 (COVID-19) pandemic, R₀ was frequently referenced by the public health community and the wider public. However, this metric is often misused or misinterpreted. Moreover, the complexity of the process of estimating R₀ has caused difficulties for a substantial number of researchers. In this article, in order to increase the accessibility of this concept, we address several misconceptions related to the threshold characteristics of R₀ and the effective reproduction number (R_t). Moreover, the appropriate interpretation of the metrics is discussed. R₀ should be considered as a population-averaged value that pools the contact structure according to a stochastic transmission process. Furthermore, it is necessary to understand the unavoidable time lag for R_t due to the incubation period of the disease.