• Development and Reproduction
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• v.24 no.4
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• pp.307-316
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• 2020

The purpose of this study is to observe the early life history of Korean Lefua costata and use the result as basic taxonomic research data for balitorid fish. The fertilized eggs were light green color with completely circle shape and mean size was 1.21±0.06 mm (n=30). Immediately after hatching, the size of the larvae was 2.81±0.11 mm (n=5) in mean length, with egg yolk. On the 3rd day after hatching, the preflexion larvae had a mean length of 4.64±0.09 mm (n=5), and their mouth was opened to start feeding. On the 8th day after hatching, a mean length of the postflexion larvae was 9.43±0.46 mm (n=5), the distal part of the notochord was bent to 45°, and 16 fin rays were developed on the caudal fin. On the 31st day after hatching, a mean length of juveniles was 22.3±0.85 mm (n=5), and the number of fin rays was the same as that of adult fish with (iv8) dorsal fins and (iii8) anal fins.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.4
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• pp.323-335
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• 2019

Rice is sensitive to day-length and short-day plants. It has a characteristic that the photosensitivity response required for flower bud differentiation decreases under long-day conditions. To identify critical photoperiod required for flower bud differentiation of major cultivation rice varieties, the average temperature was fixed at 28 ℃, and the day length was set at 12 hours and 10 minutes intervals from 13 hours to 14 hours 30 minutes. The critical photoperiod for each cultivar was set to day-length, where the daily cumulative response [(X_{(Critical Photoperiod)}-Y_{(Set day-length)})/(X_{(Critical Photoperiod)}-12:00_{(Optimal Day-length)}) × (28.0_{(Set Temperature)}-10_{(Minimum Temperature)})/(29.2_{(Maximum Temperature)}-10_{(Minimum Temperature)})] was the same for each day-length conditions. The flower bud differentiation time of all varieties was 32 days before heading at the average temperature of 28 ℃ conditions. The critical photoperiod of the early maturing type, such as Woonkwang, Odae, Koshihikari, Jopyeong, were 19:20, 18:14, 18:58, 17:30, respectively. Medium maturing type, such as Daebo, Haiami, Samdeok, were 16:08, 16:15, 16:55, respectively. Mid-late maturing type, such as Saenuri, Sindongjin, Chucheong, Samkwang, Ilpum, Saeilmi, Hwangkeumnuri, Dongjinchal, Ilmi, Hopum, Yeonghojinmi, were 15:58, 15:56, 16:36, 16:44, 15:35, 16:26, 15:33, 16:20, 16:29, 16:13, 15:41.

• Journal of Veterinary Clinics
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• v.25 no.6
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• pp.501-505
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• 2008

Serial ultrasonographic examinations were performed on 9 Miniature Schnauzer bitches from day 15 of gestation until parturition to determine the ultrasonographic measurement of gestational structures. Ovulation was designated the day that plasma progesterone concentration exceeded 4.0 ng/ml (day 0). Extra-fetal structures were measured from day 17 or 18 to 60. Outer uterine diameter (OUD) increased from $6.50{\pm}1.06mm$ ($Mean{\pm}SD$) to $50.89{\pm}5.62mm$, inner chorionic cavity diameter (ICCD) increased from $2.10{\pm}0.15mm$ to $37.15{\pm}4.36mm$, and length of placenta (PL) increased from $7.50 {\pm}1.41mm$ to $40.62{\pm}3.27mm$. OUD and ICCD were significantly and linearly relative to gestational age especially through day 37, whereas PL was not significantly relative to gestational age. Of the extra-fetal structures, ICCD was the most accurate for estimation of gestational age before day 38 of gestation. Fetal structures increased at a linear rate to parturition. Fetal crown-rump length (CRL) increased from $2.55{\pm}0.07mm$ on day 22 to $85.25{\pm}9.89mm$ on day 48. Fetal head diameter (HD) increased from $3.43{\pm}0.64mm$ on day 27 to $25.06{\pm}0.41mm$ on day 63. Fetal body diameter (BD) increased from $ 5.96{\pm}0.84mm$ on day 30 to $43.76{\pm}3.36mm$ on day 63. Of the fetal structures, HD was the most accurate for estimation of gestational age after day 38 to parturition.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.3
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• pp.315-320
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• 2002

Test-day records (n=13677) sampled from 896 ewes in 5-9 (${\mu}$=7.5) monthly test-days were used to estimate genetic and phenotypic parameters of test-day yields, lactation milk yield (TMY), length of the milking period (DAYS) and three measures of persistency of milk yield in Boutsico dairy sheep. Τhe measures of persistency were the slope of the regression line (${\beta}$), the coefficient of variation (CV) of the test-day milk yields and the maximum to average daily milk yield ratio (MA). The estimates of variance components were obtained under a linear mixed model by restricted maximum likelihood. The heritability of test-day yields ranged from 0.15 to 0.24. DAYS were found to be heritable ($h^2$=0.11). Heritability estimates of ${\beta}$, CV and MA were 0.15, 0.13, 0.10, respectively. Selection for maximum lactation yields is expected to result in prolonged milking periods, high rates of decline of yields after peak production, variable test-day yields and higher litter sizes. Selection for flatter lactation curves would reduce lactation yields, increase slightly the length of the milking period and decrease yield variation as well as litter size. The most accurate prediction of TMY was obtained with a linear regression model with the first five test-day records.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.8 no.1
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• pp.111-115
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• 1970

1. Eight Varieties of Nicotiana tabacum, "Yellow special A", "Gold leaf", "Oxford, " "Awha", "Yungzung", "Samsun", "Maruha" and "Hatano" were compared on the photoperiodic responses. 2. Experiments were conducted both under high temp. condition(green-house, average temp $25^{\circ}C$-$35^{\circ}C$) and low temp. condition (out-door; average temp $10^{\circ}C$-$25^{\circ}C$) in four plots of 8.10.12 and 14 hours in day length. 3. The results obtained are summarized as follows; i) In the short day condition, the flowering was accelerated in the low temp. than high. On the contrary, in the high temp, it was accelerated in the long day. ii) Generally speaking, the flowering was responsed more in low temp. and short day length than high temp.-long day. iii) But the above trend was found great difference among varieties..-long day. iii) But the above trend was found great difference among varieties.

• Journal of Plant Biology
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• v.26 no.4
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• pp.181-190
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• 1983

Seasonal occurrence of benthic algae and changes of subtidal vegetation were studied for their species composition, diversity and biomass during 1982 and 1983 at several selected sites at Juckdo Island (38$^{\circ}$12'N, 128$^{\circ}$32'E), eastern coast of Korea. Three large brown algae which played a role in change of algal vegetation through their great biomass were investigated with regard to their seasonal growth. Large brown algae such as Undaria pinnatifida, Costaria costata, Laminaria japonica, Agarum cribrosum, Sargassum confusum and S. hornerii constitute the major portion of vegetation in this area throughout the year. Algal vegetation in spring time is characterized by dominance of species U. pinnatifida and C. costata, whereas the summer vegetation by S. confusum and S. hornerii. In autumn large brown algae are shedded and only small algae, such as Chondrus ocellatus and Grateloupia filicina, remain. The vegetation in winter is dominated by the growth of U. pinnatifida and C. costata. Monthly changes in mean length and weight of randomly collected U. pinnatifida, C. costata and S. confusum are as follows; U. pinnatifida occurs from December to June and shows their maximum growth during March (120 cm in length, 201 g/individual in wet weight), its maximum growth rate is 1.4 cm/day, 3.3 g/day in this month. The growth season of C. costata is very similar to U.pinnatifida, but their average maximum length(110 cm) and weight (106 g/ind.) are lower than U. pinnatifida. The greatest growth rate is during March (1.8 cm/day, 2.0g/day). S. confusum is present throughout the year and reaches the maximum growth (102 cm, 63g/ind.) in July. Maximum growth rate (1.5 cm/day, 1.2 g/day) occurs also during this month. U. pinnatifida and C. costata show different months of maximum growth evidently during the two year. This seems to be caused by a considerable damage to the local vegetation followed by heavy storm in February 1983.

• The korean journal of orthodontics
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• v.53 no.3
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• pp.205-216
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• 2023

Objective: To investigate changes in the immature teeth of Sprague-Dawley rats during orthodontic treatment and to explore the changes in the peri-radicular alveolar bone through micro-computed tomography (CT). Methods: Twenty-five 26-day-old male Sprague-Dawley rats were included. The maxillary left first molar was moved mesially under a continuous force of 30 cN, and the right first molar served as the control. After orthodontic treatment for 7, 14, 21, 28, and 42 days, the root length, tooth volume, and alveolar bone mineral density (BMD) around the mesial root were measured through micro-CT. Results: The immature teeth continued to elongate after application of orthodontic force. The root length on the force side was significantly smaller than that on the control side, whereas the differences in the volume change between both sides were not statistically significant. Alveolar bone in the coronal part of the compression and tension sides showed no difference in BMD between the experimental and control groups. The BMD of the experimental group decreased from day 14 to day 42 in the apical part of the compression side and increased from day 7 to day 42 in the apical part of the tension side. The BMD of the experimental group decreased in the root apex part on day 7. Conclusions: The root length and volume of immature teeth showed continued development under orthodontic forces. Alveolar bone resorption was observed on the compression side, and bone formation was observed on the tension side.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.344-355
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• 2012

This study was conducted to analyze on the operational time and productivities of logging operations in whole-tree logging operation system by tower-yarder and swing-yarder, and in cut-to-length logging operation system by excavator with grapple in order to establish the efficient logging operation system and to spread logging operation technique. In the analysis of operational time, in case of whole-tree logging operation system, the felling time was 46.6 sec/cycle by chain saw, the yarding time was 480.6 sec/cycle by tower-yarder, the yarding time was 287.4 sec/cycle by swing-yarder and the bucking time was 155.14 sec/cycle by chain saw. In case of the cut-to-length logging operation system, the felling and bucking time was 225.65 sec/cycle by chain saw, the cut-to-length extraction time was 4,972 sec/cycle by excavator with grapple, the branches and leaves extraction time was 3,143 sec/cycle by excavator with grapple. The forwarding time was 4,688 sec/cycle by wheel type mini-forwarder, the forwarding time was 2,118 sec/cycle by excavator with grapple and small forwarding vehicle. In the analysis of operational productivities, in case of whole-tree logging operation system, the average felling performance was $57.89m^3/day$ by chain saw, the average yarding performance was $20.3m^3/day$ by tower-yarder, $31.55m^3/day$ by swing-yarder respectively, the average bucking performance was $20.3m^3/day$ by chain saw. In case of the cut-to-length logging operation system, the average felling and bucking performance was $11.96m^3/day$ by chain saw, the average cut-to-length extraction performance was $34.75m^3/day$ by excavator with grapple, the average branches and leaves extraction performance was $37.66m^3/day$ by excavator with grapple, the average length of operation road construction was 73.8 m/day by excavator with grapple. The average forwarding performance by wheel type mini-forwarder and the average forwarding performance by excavator with grapple and small forwarding vehicle was $15.73m^3/day$ and $65.03m^3/day$, respectively.

• Development and Reproduction
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• v.22 no.1
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• pp.9-18
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• 2018

This study was conducted to investigate the skeletal development of bullhead torrent catfish, Liobagrus obesus larvae and to utilize them as basic data for the taxonomic study of Liobagrus larvae. Skeletal development was observed by being divided into cranium, visceral skeleton, shoulder girdle bone, pelvic girdle bone and vertebra. On the first day after hatching, the pre-larvae had an average total length of 7.92 mm, and a line-shaped parasphenoid ossified in the cranium. In the jaw bone, the dentary supporting the lower jaw and the maxillary supporting the upper jaw were ossified. In the anterior abdominal vertebrae of the vertebra, seven centrums began to ossify and five neural spines ossified simultaneously. On the 3 day after hatching, pre-larvae had an average total length of 8.95 mm, and the prefrontal ossified in cranium. The number of abdominal vertebrae was increased to 14, and three parapophysis developed from the front side. On the 24th day after hatching, post-larvae had an average total length of 15.2 mm and the epural bone ossified in coccyx. The parhypural bone was ossified, and ossification of coccyx and pelvic girdle bone was completed. On the 30th day after hatching, the average total length of the juvenile was 17.8 mm, and the ossification of cranium and visceral skeleton was all completed while the preorbital and three suborbitals were ossified in the orbital region of the cranium.

• Korean journal of applied entomology
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• v.60 no.2
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• pp.175-183
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• 2021

As a baseline study of (common name) Locusta migratoria (Orthoptera: Acrididae) to utilize as a food source, we investigated the developmental characteristics of ovaries and eggs. Locusta migratoria had a pair of ovaries and more than 90-104 panoistic ovarioles. The ovary length in the adult stage was longer than it is in the 5th nymph stage. The length on the first day of the adult stage was 2.5-fold longer than the first day of 5^th instar. The ovary length showed a tendency to increase until the 30th day of the adult phase, but decreased from the 35^th day. Ovarioles length was about half of the ovary length, showing a similar tendency to the variation of ovary length. The lengths of the ovaries and the ovarioles increased proportionally to body weight. The matured eggs were identifiable from the 15^th day of the adult stage, and the number was the highest on the 30^th day at 50.6 individuals. Spermatheca size was also affected by the ovary development. The ovaries of L. migratoria were highly matured until the 30th day of adult stage. Weight and size of eggs increased sharply from the 4th day after egg oviposition and remained from the 7th day after spawning. Based on the above results, we found that the ovary of L. migratoria was most developed on the 30th day of adult phase, and 1st nymph is being hatched on the 10th day of the oviposition.