• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.2
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• pp.65-71
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• 1984

As a primary step in studying the relationship between the arrangement of netting and the section shape of the bag net in the four-seam trawling net, a series of experiments were performed with the simplified model of the bag net made of vinyl film. This model was suspended horizontally in circularly flowing water, with two pairs of suspending threads to four points of symetry at the border of the bag mouth in place of both wing nets. And then, the area distribution of each panel in the bag net was arranged by the portion of the length of the side panel, q to that of the lower or upper panel, p at the border of bag mouth. In the experiments, the section shape of the bag mouth photographed and the tensions on both pairs of suspending threads were measured with two loadcells in circularly flowing water. From the results that the section shape of the bag mouth in circularly flowing water is controlled by the area distribution of panels in the bag net, the author estimated an experimental equation. h/w=k sub(1) e super(k) 2 super(q/p)+C, where h is the central height of the bag mouth, and w is the lateral width of that.

• Journal of the Korea Organic Resources Recycling Association
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• v.6 no.1
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• pp.75-85
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• 1998

Algal meal (cell) was produced from the solution of dairy cow wastes by fermentation of ulothrix. sp. and chlorella sp. Raw wastes mainly feces were diluted with ground water to give dry matter concentration of 0.5 w/v of wastes in 20 l amounts of ten plastic containers. Each containers were covered with plastic nets and vinyl films to protect from the insects and rain. Algea cells were harvested every 3 to 5 days and dried by sunlight and artifitial heat. Dried cells were ground by a feed meal, and analyzed and tested for the chemical composition of dry cell, in vitro DM and protein digestibility and the safty of algae. Protein contents in algae meals, ulothrix (29.37%) and chlorella (29.24%) were similar. However, chlorella contained lower Neutral detergent fiber (5.92%) than ulothrix(20,76%), and higher ash (32.86%) and calcium (12.62%) than ulothrix (28.66% and 6.09%) (P<.01). Ulothrix protein had higher for essential amino acids; valine, isoleucine and phenylalanine, than chlorella (P<.05). Algal fats contained high saturated fatty acids, C16:0 and C18:0, for ulothrix and high unsaturated fatty acids, C18:1 and C18:2, for chlorella (P<.01). In vitro digestibility of. ulothrix tended to be higher for DM, but lower for protein than chlorella. The weight gain and survival percentage were higher for pond fishes (loaches, Misgurnus sp. ) fed diet added chlorella meal than diets added ulothrix meal and control diet (P<.05).

• Korean Journal of Ichthyology
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• v.27 no.2
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• pp.95-103
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• 2015

Egg development and early life history of the Korean spine loach, Cobitis tetralineata, were investigated in the present study. Adult fish were sampled using spoon nets at the Seomjin River in Jeongsan-ri, Bokheong-myeon, Sunchang-gun, Jeollanbuk-do, Korea, July 2013. Eggs were obtained after injecting Ovarprim into females. Eggs were then artificially fertilized using the Dry method in the laboratory. Mature eggs were slightly adhesive and transparent with grey coloring, and measured $1.04{\pm}0.03mm$ ($mean{\pm}SD$) in diameter. Hatching of the embryo occurred approximately 56 hours after fertilization at $25^{\circ}C$ of water temperature, and the average size of newly hatched larvae was about $4.6{\pm}0.11mm$ in total length. At fifth day after hatching, the larval full length reached $6.8{\pm}0.28mm$ on average and their yolk sac had been completely absorbed. At 17th day after hatching, larva entered the juvenile stage and reached $9.8{\pm}0.50mm$ in total length. At 100th day after hatching, the formation of Gambetta's zone of four line was complete and juveniles were similar in general appearance to adults, and they averaged $34.7{\pm}5.77mm$ in total length.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.93-101
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• 2012

In the present study, egg development and early life history of Korean spined loach, $Iksookimia$ $koreensis$, were observed. Adult fish were sampled using spoon nets in Okgye-ri, Hoengseong-gun, Gangwon-do, Korea in July 2010. Eggs were obtained after injecting females with Ovarprim. Eggs were then artificially fertilized in the laboratory using the dry method. Mature eggs were slightly adhesive and transparent with a light yellowish color, and measured $1.40{\pm}0.04mm$ (mean${\pm}$SD) in diameter. Hatching of the embryo occurred approximately 50 h after fertilization in the water at $23^{\circ}C$, and newly hatched larvae were averaged $4.7{\pm}0.21mm$ in total length. 5 days after hatching, the averaged total length of larvae was $7.1{\pm}0.25mm$ and their yolk sacs had been completely absorbed. 17 days after hatching, fish started to enter the juvenile stage and reached $12.2{\pm}1.10mm$ in total length. 80 days after hatching, the band patterns and external form of juvenile fish were similar to those of adults, and they averaged $31.0{\pm}3.98mm$ in total length.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.281-290
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• 2007

This study was aimed not only to develop the gill net and trap made of biodegradable monofilaments in order to prevent a ghost fishing and to protect marine ecosystem, but also to analyze their spinning process and physical properties. Results showed that the spinning speed of biodegradable polybutylene succinate(PBS) monofilament was estimated to be approximately 100m/min when spinning temperature and cooling water temperature were adjusted at $180^{\circ}C$ and $3^{\circ}C$, respectively. The breaking loads of PBS monofilaments were estimated to be $35.3kg/mm^2$ at ${\phi}0.2mm$, $46.5kg/mm^2$ at ${\phi}0.3mm$, and $49.7kg/mm^2$ at ${\phi}0.4mm$ in the dry condition, respectively. However, its breaking loads in the wet condition were reduced by 2.4-5.5%, compared to those in the dry condition. The knotted strength of PBS monofilament at ${\phi}0.2mm$ was estimated to be 98.6% of PE in the dry condition. The breaking load of PBS monofilament at ${\phi}0.3mm$ was evaluated to be 81.8% of PA, and its softness showed 3 times less than that of PA in the wet condition. The breaking load of PBS monofilament at ${\phi}0.4mm$ was 95.3% of PA, and its softness showed 1.6 times less than that of PA in the wet state. However, the load elastic elongations of two kinds of monofilaments were estimated to be 1% higher than that of PA.

• Korean Journal of Ichthyology
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• v.31 no.1
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• pp.30-38
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• 2019

Egg development and early life history of the Korean endemic sand spine loach, Cobitis nalbanti, were investigated in the present study. Adult fish were sampled using spoon nets at the Yeongsan River in Seongam-ri, Bukha-myeon, Jangseong-gun, Jeollanam-do, Korea, June 2011. Eggs were obtained after injecting Ovarprim into females. Eggs were then artificially fertilized using the dry method in the laboratory. Mature eggs were transparent and slightly adhesive with light yellowish coloring, measured $0.99{\pm}0.03mm$ ($mean{\pm}SD$) in diameter. And number of spawned eggs were $1,527{\pm}410$ per individual. Hatching (50%) of the embryo occurred 52 hours after fertilization a water temperature of $25^{\circ}C$, and the average newly hatched larvae size was about $4.2{\pm}0.22mm$ in total length. At fifth day after hatching, the larval total length reached $6.0{\pm}0.34mm$ on average and their yolk sac had been completely absorbed. At fifteen day after hatching, larva entered the juvenile stage and reached $10.8{\pm}0.45mm$ in total length. At 100th day after hatching, the formation of Gambetta's zone of four dotted line was complete and juveniles were similar in general appearance to adults, and they averaged $41.1{\pm}2.95mm$ in total length.

• Journal of Advanced Navigation Technology
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• v.26 no.3
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• pp.172-178
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• 2022

In this paper, water meter AMR(automatic meter reading), one of the core technologies of smart water grid, using LoRa IoT network is studied. The main content of the research is to develop the network system and show the test results that one PC server receives the readings of water meters from multiple households through LoRa communication and stores them in the database, and at the same time sends the data to the web server database through internet. The system also allows users to monitor the meter readings using their smartphones. The hardware and firmware of the main board of the digital water meter are developed. For a PC server program, MDMS(meter data management system) is developed using Visual C#. The app program running on the user's smartphone is also developed using Android Studio. By connecting each developed parts, the total network system is mounted on a flow test bench in the laboratory and tested. For the fields test, 5 places around the university are selected and the transmission distances are tested. The test result show that the developed system can be applied into the real field. The developed system can be expanded to various social safety nets such as monitoring the living alone or elderly with dementia.

• Korean Journal of Plant Resources
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• v.9 no.2
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• pp.151-155
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• 1996

For improvement germination rate of Cirsium setidens, wet seeds were storaged for 20 to 80 days at $4^{\circ}C$ and germinated at $18^{\circ}C$ in the dark or light condition. To assess the effects of shading and plant age on the growth, fresh yield and seed yield under rain shelter in highland at altitude of 800m above sea level, seeds were sown in an open field in late september,1990. In early May the next the seedlings were transplanted for vegetatable and seed production in the plastic houses for rain shelter. They were grown from 1991 to 1993 in the houses covered with the shading nets ranging from 0 to 70% for vegetable production and 0 to 50% for seed production. Germination rate inceased as the storage period lengthened, and the rate came to $60\sim80%$ at 60days after germination. It was more effective in lighting than in darkness. For vegetable production, the shading net treatments showed more values in almost the characters checked at the third year than the non-shading treatment. No. of stem, no, of leaves, stem length and degree of softening were no different between shading net treatments, but the other characters were significantly different. Ratio of survival, density of chlorophyll and ratio of dry matter of plants were highest in the plots of 50%, 70%, and 30% of shading, respectively. The highest fresh yield was recorded from 2-year plants, 70% of shading from them showed the greatest yield. The highest seed yields were produced 2-year-old plants of non-shading plot. For seed production, the non-shading treatment is best, and the highest seed yields were obtained in both the second and third years.

• Korean Journal of Medicinal Crop Science
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• v.19 no.2
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• pp.90-96
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• 2011

This study was conducted to examine major growth responses, the production and partitioning of dry matter on different growth stages, and yields and to select the optimal shading material in both quality and productivity of ginseng. Two cultivars of ginseng, Cheonpoong and Geumpoong, were cultivated in the paddy soil with three different shading materials; three-layered blue and one-layered black polyethylene (TBP), blue polyethylene sheet (BPS), and aluminium-coated polyethylene sheet (APS). Plant heights were linearly increased until June 24 and then maintained with showing higher height in Cheonpoong than that in Geumpoong cultivar. Root lengths were gradually increased until October 16. They were longer in Cheonpoong than that in Geumpoong cultivar, showing slightly longer with APS compared to TBP and BPS. The ability of producing dry matter of leaves was much higher from April to June compared to those of other growth periods, whereas its ability of root was concentrated from the end of June to the end of August. Among the shading materials, the ability of producing dry matter of shoot was higher with TBP than those with BPS and APS, while its ability of root was not appeared certain tendency unlike the shoot. The yield of ginseng roots was the highest with TBP among three shading materials and it was higher in Cheonpoong than that of Geumpoong cultivar. The shading materials which affect the light intensity and the temperature would be considered as an important factor to get better quality and productivity of Korean ginseng.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.133-138
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• 1983

In Korea, Brassica species planted in summer remain in rosette and do not flower. Seed production of vernalized rape seedlings grown in summer was evaluated to establish method of generation shortening and genetically pure seed production without isolation of seed fields. When vernalized rape seedlings of different maturity groups were transplanted in summer, all plants bolted and flowered, and average days from sowing to bolting and flowering was 37 and 58. respectively. It took 85days for early maturity group, 88 days for medium maturity group, and 108 days for late maturity group to mature. Seed yield of vernalized plants grown in summer was 8.8 gr per plant and 53kg per l0a which was 23% of seed yield of rape planted in autumn. However, enough seeds were produced to test oil composition and cake and to plant for a next generation. If seedlings are raised, they can be transplanted in more than 1, 000 times of original seed field, indicating that genetically pure seed can be produced without caging seed fields with nets and isolation of seed fields since other Brassica species do not flower in summer.