• Journal of Life Science
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• v.19 no.11
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• pp.1547-1552
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• 2009

This study was carried out to evaluate the supplementation effect of dietary natural plant extracts (NP: $Coxynil^{(R)}$, $Growell^{(R)}$ and $Respowell^{(R)}$) on broiler chickens. Forty thousand male broilers with 7 days adaptation after hatching were fed experiment diets for 34 days. The supplementation effects of NP on growth performance, blood parameters and biopsy were examined with twenty thousand broilers as the treatment group. Twenty thousand broilers for the control group (CON) were fed the diet with salinomycin-6, clopidol-25, enramycin-1, and BMD-2.5. In the diet of the treatment group, the antibiotics were replaced with 0.03%, 0.035% and 0.03% of $Coxynil^{(R)}$, $Growell^{(R)}$ and $Respowell^{(R)}$, respectively. The weight gain of the treatment group was increased but the feed intake was decreased, indicating that feed efficiency was increased compared to the CON. The mortality of the NP group was also lower compared to the CON group (1,008 birds to 1,693 birds), showing positive dietary effects from natural plant extracts. In the activity of infectious bursal disease virus (IBDV) and new cattle disease virus (NDV) antibodies, the NP showed lower antibody titer levels for both of IBDV and NDV compared to the CON. The levels of total cholesterol, HDL-cholesterol, globulin, and IgG in blood did not show significant differences between the groups. In the microscopic tissue analysis, no significant differences were detected. These results may suggest that a complex of three natural plant extracts can be used as alternative antibiotics in broilers.

• Journal of Aquaculture
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• v.20 no.4
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• pp.219-225
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• 2007

This study investigated the correlationship between artificial maturation season and reproduction coefficient of cultured eel Anguilla japonica from May (spring) to next January (winter). The brood stock, female eels ($400{\sim}600\;g$) were artificially matured by weekly intramuscular injections of salmon pituitary extracts (SPE, 20 mg/fish) to induce a completion of vitellogenesis. After completion of vitellogenesis, final oocyte maturation and ovulation was induced by injection of $17{\alpha}$, $20{\beta}-dihydroxyprogesterone$ (DHP) at about $2\;{\mu}g/g$ body weight. Most fish ovulated $15{\sim}18\;h$ following the DHP injection. The ovulated fish were induced to natural spawning or artificial fertilization by the dry method. Males ($200{\sim}350\;g$) were received weekly intramuscular injections of human chorionic gonadotropin (HCG) at a dosage of 1 IU/g body weight to induce testicular maturation and spermiation. Seasonal reproduction coefficient which includes the rate of ovulation, buoyancy, fertilization and hatching of eggs in the artificially matured eel during spring to summer ($May{\sim}July$) were significantly higher than the other season, while there were no significant difference among spring and summer (P<0.05). Furthermore, the number of eggs spawned and larvae hatched in the artificially maturated eel during spring to summer ($May{\sim}July$) were significantly higher than the other season, while there were no significant difference in spring and summer (P<0.05). These results indicate that artificial maturation by hormone treatment of A. japonica was successful only during spring to summer, which is the maturation period in the wild stock in nature. Consequently, it is possible to determine the period of artificially induced sexual maturity by the reproduction coefficient which includes the rate of ovulation, buoyancy, fertilization and hatching of eggs in the cultured eel A. japonica.

• Korean Journal of Weed Science
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• v.30 no.3
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• pp.282-290
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• 2010

The objective of this research was to discover the best method for weed management in environment-friendly rice paddy fields through the study on the effect of weed control and injury levels of rice plants as affected by size, input time, and input amount of golden apple snail (GAS). The efficacy of weed control as affected by GAS when applied at 5, 10, and 15 days after transplanting (DAT) was 98, 89, and 58%, respectively. The efficacy of weed control had declined as late the input time of GAS. On the other hand, the efficacy of weed control as affected by rice bran followed by GAS treatment was higher than by GAS treatment alone. Weed species such as Persicaria hydropiper, Echinochloa crus-galli, Scirpus juncoides, and Monochoria vaginalis were not completely controlled by GAS when applied late. Input amount and time of adult GAS (70 days after hatching) for effective weed control were 3 kg $10a^{-1}$ at 5 DAT, 6-7 kg $10a^{-1}$ at 10 DAT, and 7 kg $10a^{-1}$ at 15 DAT. Input time and amount of young GAS (35 days after hatching) for effective weed control were 0 day after harrow (DAH) and 1 kg $10a^{-1}$, respectively. The young GAS when applied 0 DAH at 1 kg $10a^{-1}$ provided 100% control of P. hydropiper, E. crus-galli, S. juncoides, M. vaginalis, Ludwigia prostrata, Eleocharis kuroguwai, Sagittaria trifolia and Cyperus difformis. The rice foliar injury caused by adult (3 kg $10a^{-1}$) and young (1 kg $10a^{-1}$) GAS were 5-7% and 1% respectively. There was no significant difference in rice injury by size and input amount of GAS on plant height and number of tiller. These data indicate that the young GAS when applied 1 kg $10a^{-1}$ at 0 day after harrow was the best method for weed management in environment-friendly rice paddy fields.

• Korean journal of applied entomology
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• v.37 no.2
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• pp.143-149
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• 1998

Development and life table statistics of indian meal moth (Plodia interpunctella, Hiibner)on brown rice (Sativa oryzae L., var 'Ilpum' ) were tested under five different temperatures (17, 20, 25,28 and 3 2 f 0.5"C). The developmental response of females to the temperature was not significantlydifferent from that of males. In the tested temperature range, developmental period and life span of adultmoth decreased as the temperature increased and ranged from 149.9f30.4 to 38.1 k5.6 days and from19.4f 5.1 to 6.9k2.0 days at 17$^{\circ}$C and 32"C, respectively. Emergence rate increased with the increaseof temperature and ranged from 13.0f 6.2% at 17$^{\circ}$C to 49.2f 25.9% at 32$^{\circ}$C. However, hatching ratecurve in relation to the temperature was dome shape with the peak of 73.8 k5.37~a t 25"C, suggesting thathatching is inhibited by high temperature above that temperature. As the temperature increased, femalesconcentrated their oviposition on the second day after emergence. In the temperature range of 17 SIM 25"C, the number of eggs laid per female were not related to the temperature and ranged from 133.4f 37.6to 154.3k57.4. But the number of eggs laid per female decreased at 32$^{\circ}$C which suggests closerelationship with hatching ability. The net reproduction rate was highest at 28$^{\circ}$C and followed by those at25$^{\circ}$C and 20$^{\circ}$C. However intrinsic rate of natural increase of the moth population on brown rice wasestimated to be highest at 32$^{\circ}$C (0.065 per day), probably due to the short developmental period, highemergence rate and the concentrated oviposition of females on earlier days of the emergence.ition of females on earlier days of the emergence.

• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.73-82
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• 2005

This study was conducted, based on the field survey and laboratory observations, to elucidate egg developmental processes and their characteristics of the Korean slender gudgeon, Squalidus gracilis majimae. For the experiments, the mature adults were collected at the Woongcheon-Cheon Stream and Boreung Reservoir located in Boreung City, Chungnam Province and eggs were obtained from the natural spawning area. Morphological characteristics of the egg and embryonic development were summarized as follows: The shape of the fertilized egg was spherical, adhesive and transparent. The fertilized egg was 2.9${\pm}$0.3 mm (n = 30) in mean diameter under water temperature of $26{\pm}1.5^{\circ}C$, light white in color and had no oil droplets. After 20 minutes from the time of fertilization, a blastodisc was formed and divided into two cells at 48 minutes after fertilization. The blastular stage occurred at 5 hours 40 minutes after fertilization and the gastrular stage was detected at 8 hours 41 minutes after fertilization. The beginning of embryo formation was observed at 12 hours 58 minutes after fertilization and optic vesicles and 9 somites were discovered at 17 hours 05 minutes after fertilization. Differentiation of brains and embryo wiggling were observed at 37 hours 27 minutes after fertilization. Heart beating and the formation of melanophores in optic vesicles were detected at 44 hours 46 minutes after fertilization. The formation of pectoral fins and melanophores in the body were discovered at 50 hours 36 minutes after fertilization. Hatching occurred at 57 hours 49 minutes after fertilization. The newly hatched larvae were 3.3${\pm}$0.2 mm (n = 120) in total length. We believe that these results may contribute the species and population conservations under the situation of accelerated water pollution and the decreases of its diversity.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.1
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• pp.76-87
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• 2019

The purpose of this study was to evaluate the performance of and to derive future maintenance-management measures of the constructed alternative habitat for the Kaloula borealis at the University of Seoul, examining the period between 2015-2017. The research was constructed in 2014 and in a $191m^2$ area. The performance evaluation was divided into maintaining the habitat of the target species, maintaining the population and reproduction rates of the target species, maintaining the habitat of the wild species, the resilience of natural ecosystems, and the harmony with the surrounding environment. In terms of maintaining the habitat of the target species, soil collected from the existing habitat of the Kaloula borealis and was the depth was increased to 30cm in the alternative habitat. An artificial water supply was required every year during the supporting the spawning and hatching of other amphibians along with the Kaloula borealis. The sources of water of the alternative habitat were both rain and tap water, as it cannot be maintained naturally. Additionally, the Kaloula borealis thrived because it inhabited the research site and the average temperature was $26.2^{\circ}C$ from April-June, which is when the Kaloula borealis spawns. In terms of maintaining the population and reproduction rates of the Kaloula borealis, they were evaluated to have stable rates of reproduction. In terms of maintaining the habitat of the wild species, studies on vegetation and the structure of the characteristics of prey or predators will be needed. Also, alien species, such as Humulus japonicus and Bidens frondosa needed to be removed to maintain the wetland ecosystem of the wild species. In the assessment of the resilience of the natural ecosystems, the mud was monitored, noting the changes in the depth of water, with steps taken to reduce the leakage of water. The mud collected from the Haneul Pond wetland, which is located around the research site was piled up. Also, partial mowing management and the inducement of a natural vegetation colony was required for vegetation management. It was also necessary to create porous spaces, such as old trees and tree branches to create a habitat with hiding places and feeding and spawning places for small organisms. In terms of the harmony with the surrounding environment, the following threat factors needed to be managed: amphibian roadkill by vehicles and pedestrians and artificial draining due to nearby user access. Based on the monitoring results, alternative habitat management measures presented the promoting various waterside structures, in which amphibians can spawn and hide in, managing the water environment consistently, managing the vegetation, focused on the habitat of the wild species, and managing the surrounding environment for the habitat. The creation of an alternative habitat should be managed through monitoring, reflecting the characteristics of the changes in the site. Also continuing efforts are also needed to improve the habitat of the target species.

• Korean journal of applied entomology
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• v.44 no.1 s.138
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• pp.61-65
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• 2005

Egg-forming and preservation methods for the indoor-rearing system of the emma field cricket, Teleogryllus emma, were investigated. The oviposition preference experiment on different mats, soil(natural oviposition mat) and $oasis^{\circledR}$(artificial oviposition mat), showed that T. emma preferred to oviposit on the $oasis^{\circledR}$. On the other hand, $oasis^{\circledR}$ had more inactive number of eggs laid per female and hatchability than another. However, the number of eggs laid per female and hatchability within 50 days after emergence were better than soil. The experiment on the hatching of the eggs showed that eggs could be stocked at $10^{\circ}C$ for 40 days with 14 day pre-period after laying, representing $62.1\%$ hatchability, when considering generation shortening. On the other hand, When it had been kept in cold storage for 90 days at $7.5^{\circ}C$ with 14 day pre-period after laying it, appeared to be the most suitable for long period-storage method by hatchability $65.1\%$.

• Development and Reproduction
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• v.10 no.2
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• pp.135-140
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• 2006

The small octopus(Octopus minor), a species in the cephalopod class spawns the fewer eggs compared with its relatives such as Octopus vulgaris and Octopus ocellatus and exerts special efforts in nursing eggs hiding in the deep cave beneath the mud flat. Correspondingly, its embryogenic process had been hardly observed. In this study, we induced the small octopus to spawn its eggs in the artificial spawning tube and to nurse the developing embryos under the periodical observation. The early embryogenic change in the fertilized eggs was appearance of blastodisc on the animal pole at 4 days after spawning. A mass of rudiments of several organs developed in the middle of the yolk sac at 28-th day and it moved gradually toward the animal pole. At 38 days after spawning, two eyes appeared on the head and the trunk with heart developed on the apical part of the yolk sac. At 45-th day of embryonic development, the trunk and head occupied a half of the egg capsule and consequently the yolk sac was reduced to a half of its original size. Two eyes became prominent at the bottom of the trunk with several spots at day 60. Embryonic development was completed at about 80 days after spawning and the arms stuffed the lower half of egg capsule. The young fry squeezed out of the egg capsules with their long and slender arms first and mantles later. Soon after hatching, it swam actively and squirted ink.

• Journal of Aquaculture
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• v.8 no.2
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• pp.141-148
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• 1995

For the mass production of all-female triploid rainbow trout during fall season, treatment of short-term daylength from 30th of August, 1994 and chromosome manipulation by heat shock were performed with 3-year-old fish. After treatment of short-term daylength to fish, we successfully obtained the fertilized eggs from all treated fishes. However, hatching rate were significantly lower than that of natural spawning season (P<0.05). Hormonal treatment using 3mg of $17\alpha-methyltestosterone$ per kg of diet for 55 days at $16.5^{\circ}C$ gave $100\%$ of sex-reversed male (masculinized female) population. When the fertilized eggs were treated with the various conditions of heat shocks survival rates and triploid incidencies were varied, and ranged from 15.0 to $88.2\%$ and 36.7 to $100\%$, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.2
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• pp.55-60
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• 1971

There are a lot of kinds of shrimps for fishing baits, but Palaemon modestus is dominant species in the Karak River. The ecology in the natural environments was reported by the author (1970) and this work is an elemental task for the larval stage in shrimp farms. Shrimps were collected from the Karak River and carried to the laboratory. Hatched larvae were reared from June 6 to June 24, 1970 for pre-experiment, and main experiment was provided from August 10 to August 24, 1970. The following is a summary of the results: 1. Hatching period in the laboratory water tank was eight hours ($20^{\circ}C\~20.9^{\circ}C$). 2. The larvae died off from the sixth day after hatch without food. 3. Feeding begins on the third day after hatch. 4. The relationship between the density of food and the consumption was not concerned when the number of Artemia nauplii was 2 to 6 per ml of water. 5. The relationship between the day (X) and the food (Y) is: $$Y=6.49824X^{1.8384}$$ 6. The carapace growth curve is: $Y=1.1608X^{0.10024}$ 7. The relationship between the food (X) and the body length (Y) is: $$Y=2.8114X^{0.12767}$$ 8. The relationship between the carapace length and the body length(Y) is : Y= 3.7564X-0.4601