• Journal of Aquaculture
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• v.5 no.1
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• pp.29-67
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• 1992

Life cycle and seed production of the freshwater prawn, Macrobrachium nipponense, were studied and the results are as follows : 1. Larval development : Embryos hatched out as zoea larvae of 2.06 mm in mean body length. The larvae passed through 9 zoea stages in $15{\~}20$ days and then metamorphosed into postlarvae measuring 5.68 mm in mean body length. Each zoea stage can be identified based on the shapes of the first and second antennae, exo- and endopodites of the first and second pereiopods, telson and maxillae. 2. Environmental requirements of zoea larvae : Zoea larvae grew healthy when fed with Artemia nauplii. Metamorphosing rate was $65{\~}72{\%}$ at $26{\~}28\%$ and $7.85{\~}8.28\%_{\circ}Cl.$. The relationship between the zoeal period (Y in days) and water temperature (X in $^{\circ}C$) is expressed as Y=46.0900-0.9673X. Zoeas showed best survival in a water temperature range of $26{\~}32^{\circ}C$ (optimum temperature $28^{\circ}C$), at which the metamorphosing rate into postlarvae was $54{\~}72\%$ The zoeas survived more successfully in chlorinity range of $4.12{\~}14.08{\%_{\circ}}Cl.$, (optimum chlorinity $7.6{\~}11.6\;{\%_{\circ}}Cl.$.), at which the metamorphosing rate was $42{\~}76{\%}$. The whole zoeal stages tended to be longer in proportion as the chlorinity deviated from the optimum range and particularly toward high chlorinity. Zoeas at all stages could not tolerate in the freshwater. 3. Environmental requirements of postlarvae and juveniles : Postlarvae showed normal growth at water temperatures between $24{\~}32^{\circ}C$ (optimun temperature $26{\~}28^{\circ}$. The survival rate up to the juvenile stage was $41{\~}63{\%}$. Water temperatures below $24^{\circ}C$ and above $32^{\circ}$ resulted in lower growth, and postlarvae scarcely grew at below $17^{\circ}C$. Cannibalism tended to occur more frequently under optimum range of temperatures. The range of chlorinity for normal growth of postlarvae and juveniles was from 0.00 (freshwater) to $11.24{\%_{\circ}}Cl.$, at which the survival rate was $32{\~}35\%$. The postlarvae grew more successfully in low chlorinities, and the best growth was found at $0.00\~2.21{\%_{\circ}}Cl.$. The postlarvae and juveniles showed better growth in freshwater but did not survive in normal sea water. 4. Feeding effect of diet on zoea Ilarvae : Zoea larvae were successfully survived and metamorposed into postlarvae when fed commercial artificial plankton, rotifers, and Artemia nauplii in the aquaria. However, the zoea larvae that were fed Artemia nauplii and reared in Chlorella mixed green water showed better results. The rate of metamorphosis was $68\~{\%}75$. The larvae fed cow live powder, egg powder, and Chlorella alone did not survive. 5. Diets of postlarvae, juveniles and adults : Artemia nauplii and/or copepods were good food for postlarvae. Juveniles and adults were successfully fed fish or shellfish flesh, annelids, corn grain, pelleted feed along with viscera of domestic animals or fruits. 6. Growth of postlarvae, juveniles and adults : Under favorable conditions, postlarvae molted every five or six days and attained to the juvenile stage within two months and they reached 1.78 cm in body length and 0.17 g in body weight. The juveniles grew to 3.52 cm in body length and 1.07 g in body weight in about four months. Their sexes became determinable based on the appearance of male's rudimental processes (a secondary sex character) on the endopodites of second pereiopods of males. The males commonly reached sexual maturity in seven months after attaining the postlarvae stage and they grew to 5.65 cm in body length and 3.41 g in body weight. Whereas the females attained sexual maturity within six to seven months, when they measured 4.93 cm in body length and 2.43 g in body weight. Nine or ten months after hatching, the males grew $6.62{\~}7.14$ cm in body length and $6.68{\~}8.36$ g in body weight, while females became $5.58{\~}6.08$ cm and $4.04{\~}5.54$ g. 7. Stocking density : The maximum stocking density in aquaria for successful survival and growth was $60{\~}100$ individuals/$\ell$ for zoeas in 30-days rearing (survival rate to postlarvae, $73{\~}80{\%}$) ; $100{\~}300$ individuals/$m^2$ for postlarvae of 0.57 cm in body length (survival rate for 120 days, $78{\~}85{\%}$) ; $40{\~}60$ individuals/$m^2$ for juveniles of 2.72 cm in body length (survival rate for 120 days, $63{\~}90{\%}$) : $20{\~}40$ individuals/$m^2$ for young prawns of 5.2 cm in body length (survival rate for 120 days, $62\~90{\%}$) ; and $10\~30$ individuals/$m^2$ for adults of 6.1 cm in body length (survival rate for 60 days, $73\~100{\%}$). The stocking density of juveniles, youngs and adults could be increased up to twice by providing shelters.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.4
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• pp.281-291
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• 2010

To estimate the mesh selectivity of monofilament and multifilament gill net for Marbled sole, Pleuronectes yokohamae, the field testes were carried out 12 times with five different mesh sizes (86.6, 101.0, 121.2, 137.7, 151.5mm) in the western sea of Korea, 2007-2009. The master curve of selectivity was estimated by the extended Kitahara's method. In the field testes, the total number of species and catch were 26 and 987, respectively. The catch number of marbled sole was 728 and occupied 73.8% in total catch. The optimum values of l/m for 1.0 of retention probability in monofilament and multifilament gill net were estimated 0.288 and 0.307, respectively and l/m was estimated to be 0.189, 0.203, 0.213, 0.222 and 0.230 in case of monofilament gill net and 0.171, 0.191, 0.205, 0.216 and 0.227 in case of multifilament gill net when the retention probability were 0.1, 0.2, 0.3, 0.4 and 0.5, respectively. The 0.5 selection range of multifilament gill net was wider about 1.5 times than that of monofilament gill net according as multifilament gill net was 0.216 and monofilament gill net was 0.148. So the multifilament gill net has a low selectivity than that of the monofilament gill net. To estimate the optimum mesh size on first maturity length 19.5cm of marbled sole, the retention probability value of 0.1 was adopted in consideration of using the gill net for marbled sole at present. The optimum mesh size were estimated to be 103.2mm and 114.0mm in monofilament gill net and multifilament gill net, respectively, on first maturity length 19.5cm of marbled sole.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2000.05a
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• pp.38-44
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• 2000

To determine the optimum sowing date and nursery period in Alisma piantago in the southern area of Korea, Alisma plantago local cultivar was grown under three different sowing dates and nursery periods. The plant height, leaf width and leaf length at the area sown on the seedbed in June 30 and conducted the growing seedling in 30 days is 12.1cm, 2.5cm and 3.1cm respectively and it shows tess decrease than that of plant height, leaf width and leaf length with 12.3cm, 2.6cm and 3.2cm respectively which was sown on the seedbed in June 20 and carried out the growing seedling in 30 days, and it also shows less decrease than that of plant height, leaf width and leaf length with 15.2cm, 3.1cm and 5.2cm respectively at the area sown on the seedbed in July 10 and condected the growing seedling in the same date. The stem length, number of stems and diameter of root at the area sown on the seedbed in June 30 and conducted the growing seedling in 30 days is 31cm, 11 and 3.7cm respectively and it shows more increase than that of stem length, number of stem and diameter of and on the other hand shows tess decrease than that of stem length, number of stems and diameter of root with 30cm, 10cm, 35cm respectively which was sown on the seedbed in 30 days, and on the other hand shows less decrease than that of stem length, number of stems and diameter of root with 32cm,13cm,3.9cm respectively at the area sown on the seedbed in July 10 and conducted the growing seedling in the same date, The fresh yield of roots at the area sown on the seedbed in June 30 and conducted the growing seedling in 30 days is 431.4Kg/10a and it shows more increase of 26.9Kg than that of fresh yield of root with 410.59g110a which was sown on the seedbed in lune 20an4 carried out the growing seedling in 30 days, and it also shows more increase of 7Kg than that of fresh yield of root with 430.4Kg/10a at the area sown on the seedbed in July 10 and conducted the growing seedling in the same date. The dry yield of roots at the area on the seedbed in June 30 and conducted the growing seedling in 30 days is 351.9Kg110a which was sown on the seedbed in June 20 and carried out the growing seedling in 30 days, and it also shows more increase of 16.4Kg than that of dry yield of root with 335.4Kg110a at the area sown on the seedbed in July 10 and conducted the growing seedling in the same date. Therefore, the seedling period of proper seedbed for high yield bumper crop of Alisma plantago for exporting to Japan is June 30 and the number of days for seedling is 30 days.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.69 no.1
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• pp.61-69
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• 2024

Considering the threats of climate change, this study was conducted to investigate the influence of temperature and day-length on soybean growth and yield when sown late in comparison to the optimal sowing time in the southern region of the Korean Peninsula. Sowing was executed in 10-day intervals, including on July 1, 10, 20 and 30 and August 10, considering that the optimum sowing time of the three soybean varieties with different ecotypes is June 20. Emergence rates did not differ significantly between late-sowing and optimal sowing in all ecotypes; however, the number of days to emergence, flowering, and maturity was smaller after late sowing. A multiple-regression approach was used to test the effect of temperature and day length on the number of growing days after late sowing compared to the optimal sowing time. This analysis revealed that the number of days required from sowing to flowering was positively correlated with both day length and temperature, and the number of days from flowering to harvest was positively correlated with day length and negatively with temperature. A multiple regression equation can be calculated as follows: the number of days required from sowing to flowering (Y) = 3.177 + (0.030 × (sum of day length + sum of temperature)), and the number of days required from flowering to maturity (Y) = 20.945 + (0.021 × (sum of day length + sum of temperature)). Multiple growth parameters were significantly correlated with yield components, depending on growing days. Optimal sowing resulted in the best yield, while later sowing decreased yield compared to optimal sowing. To avoid a significant decrease in yield, early-maturing species should be sown by July 20, while late-maturing species should be sown by July 10.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.4
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• pp.330-336
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• 2016

In this paper, we studied for modified bartlett method to estimate desired information signal. Constrained length of bartlett method is assigned as one, and estimate desired information signal to compensate for delay time. Modified bartlett method is an optimum direction-of-arrival (DoA) estimation algorithm to apply delay time compensation to update optimum weight. The optimum weight is used linear constrained minimum variance method(LCMV). Through simulation, we are comparative analysis proposed algorithm and general Bartlett and MUSIC method. In desired signal estimation, condition simulation is an array antenna element numbers 6 or 9 and desired information signals number 3. We show the superior performance of the proposed algorithm relative to the existing method in estimation of desired information signal.

• Journal of Bio-Environment Control
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• v.13 no.4
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• pp.266-270
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• 2004

A rose factory type is a system that enables year-round, planned and mass production of high quality cut-rose. Conversion of a conventional system to a rose factory is essential to increase cut-rose export. Controlling root Bone in culled rose production factory is very important for economic and efficient production of rose. This study was conducted to determine optimum root zone temperature of nutrient solution in single-stemmed rose production system. The optimum temperature of the nutrient solution for growth, photosynthetic and transpiration rates for 'Red Velvet' was $15\~20^{\circ}C$. Whereas the optimum temperature for 'Vital' was $10\~15^{\circ}C$. However, growth was almost sloped at $30^{\circ}C$, resulting in concluding the adaptation of 'Vital' to high temperature was poor as compared with 'Red Velvet'.

• Journal of Mushroom
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• v.12 no.3
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• pp.145-153
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• 2014

Pleurotus has increased rapidly production and consumption because of highly nutritional value, natural healthy food and so on. The basic studies for Pleurotus need for development of mushroom industry. This study was to investigate the cultural characteristics among 15 strains of 6 species and to analyze their phylogenetic relationships. The cultural characteristics were investigated by mycelial growth activity at different media, temperature and pH. The optimum media for mycelial growth were YM and MCM in most species. The optimum temperature for mycelial growth were $25^{\circ}C$ and $30^{\circ}C$. The optimum pH for mycelial growth were widly range from pH 5.1 to 7.4. Through the RFLP (restriction fragment length polymorphism) of IGS (intergenic spacer) I region in ribosomal DNA, it was analyzed phylogeny of interspecies and intraspecies. Each species was discriminated well as isolates within each species formed clade to be distinguished other species. P. florida was highly similar to P. floridanus, and P. flabellatus was P. cornucopiae. P. fuscus var. ferulae was highly similar to P. eryngii but discriminated different species in analysis of RFLP of IGS I region and showed different characteristics in mycelial culture. RFLP of IGS I region was useful of studying phylogenetic relationships of species and population.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.5
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• pp.343-345
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• 2008

This study determined the optimum feeding frequency for the growth of juvenile cherry salmon (Oncorhynchus masou). Triplicate groups of fish (initial mean weight 19.1 g) were fed extruded pellets at four feeding frequencies for 50 days: once every 2 days, once a day, twice a day, and three times a day. The mean water temperature during the feeding trial was $17.9{\pm}1.59^{\circ}C$. The survival of all groups was 100%. The final fork length of fish fed twice a day was significantly greater than that of the other groups (P<0.05). The weight gain of fish fed two and three times daily was significantly greater than that of fish fed once a day or every 2 days (P<0.05). The daily feed intake increased significantly with feeding frequency (P<0.05), but there was no significant difference in the weight gain of fish fed two or three times a day. The feed efficiency of fish fed once every 2 days was highest (P<0.05), and the feed efficiency of fish fed two or three times a day was significantly higher than that of fish fed once a day (P<0.05). The results of this study indicated that the optimum feeding frequency for the growth of juvenile cherry salmon is twice a day, while the feeding efficiency of fish fed once every 2 days was best.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.670-678
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• 2018

In coastal waters where the traffic volume of the ship is high, there is a high possibility of a collision accident because complicated encounter situations frequently occurs between ships. To reduce the collision accidents at sea, a quantitative collision risk assessment is required in addition to the navigator's compliance with COLREG. In this study, a new collision risk assessment system was developed to evaluate the collision risk on ship's planned sailing routes. The appropriate collision risk assessment method was proposed on the basis of reviewing existing collision risk assessment models. The system was developed using MATLAB and it consists of three parts: Map, Bumper and Assessment. The developed system was applied to the test sea area with simple computational conditions for testing and to actual sea areas with real computational conditions for validation. The results show the length of own ship, ship's sailing time and sailing routes affect collision risks. The developed system is expected to be helpful for navigators to choose the optimum safe route before sailing.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.19
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• pp.7-13
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• 1975

In other to determine the optimum condition for the alkali digestibility test, the milling degree of samples,the concentrations of potassium hydroxide,the temperature and the length of time for soaking were discussed.The results obtained from these experiment are summarized as follows; 1.Over 90 minute-milled samples in a new test tube miller showes the stable alkali digestibility values. 2.The optimum conditions for the alkali digestibility test were shown as 1.8 percent for the simultaneous treatment of Indica and Japonica varieties,1.4 percent or below for only Japonica and/or soft group varieties,and 2.2 percent of KOH for only Indoca and/ot hard group varieties provided the temperature and soaking time were fixed at \;30^{\circ} and 18 hours respectively.