• Asian-Australasian Journal of Animal Sciences
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• v.13 no.8
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• pp.1109-1112
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• 2000

A field experiment was carried out to determine the effects of mechanical and chemical conditioning at mowing on field drying rate and quality of grass hay in 1996. Mower conditioner and/or chemical drying agent $(K_2CO_3)$ were used at different harvest stages (late boot, heading and bloom stages) for hastening hay-making. After field drying, square bales were made by hay baler, and the visual estimation and nutritive value of hay were evaluated after storing two months. In mower conditioning, the duration of field drying was shortened by 0.5 to 1 day compared with drying agent, and by 1 to 2 days compared with control. The drying matter loss of hay was reduced by late harvest and mechanical conditioning. The visual score (leafiness, green color, odor and softness), and acid detergent fiber (ADF), neutral detergent fiber (NDF), in vitro dry matter digestibllity (IVDMD), and relative feed value (RFV) of hay were improved with mechanical conditioning, but chemical alone had little effect on quality. The quality of hay harvested at bloom stage was much lower than that of hay harvested at late boot and heading stage. In conclusion, mower conditioning can enhance the field drying rate of grass hay, however the drying efficiency of chemical drying agent is very low. Also the effects of chemical/mechanical combined conditioning are very similar compared with mechanical conditioning alone. Harvesting at late boot to heading stage is recommended for the production of high quality hay.

• The Korean Journal of Ecology
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• v.9 no.3
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• pp.161-184
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• 1986

An experiment was made in order to analyze the growth characteristics and productivity of Zoysia japonica under control, mowing and TIBA treatment conditions at the experimental farm of Kyung Hee univ. from May 26 to Oct. 1 in 1985. The field was planned by the randomized block design method and each treatment was given to three plots (2${\times}$2, 4${\times}$4 and 10${\times}$10 cm) and was replicated three times. Each plot was 1$m^2$ for Zoysia japonica. The sampling of each plot was taken once a week after sowing. In order to know the dry matter of total standing crops, kept 9$0^{\circ}C$ and weighted each organ of the plants. Total leaf area of a plant was measured by drawing method. The author adopted the growth analysis of English School. The increasing rates of numbers of leaf and stem were remarkably high in each plot between 10th and 12th weak after sowing and it was highest in TIBA treated plot. The increasin rate of leaf area in each plot was remarkably high beween 10th and 12th week and the maximum value of leaf area was 274.00c$m^2$ in TIBA treated plot of 100 plants/$m^2$. The increasing rate of standing crop was remarkably high between 10th and 12th week and the high increasing tendency in TIBA plot resulted from TIBA. The positive correlationship was founded between standing crop and leaf area. The evaporation rather than temperature acted as a main factor of negative correlation with standing crop during the experiment period. Solar radiation had a high positive correlation in the lower density of plot. C/F ratio was low, during the growth period, from 10th to 12th week after sowing and was low in the higher density under each treated plot. T/R ratio was not constant during the sampling period but was high in the lower density. The increasing rates of RGR and NAR were high between 11th and 12th week after sowing. Leaf area ratio was high in higher density in each plot and not constant in all treated plot.

• Korean Journal of Agricultural Science
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• v.19 no.2
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• pp.238-268
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• 1992

Since rural people migrated to urban area as a result of rapid industrialization in Korea, a significant proportion on agricultural labor farces has consistently reduced and therefore incurred labor shortage in rural area which might aggravate the farm household's economy. This sutdy suggests a long run plan of supplying agricultural machines for forage cultivation based on the survery of 102 livestock farm housecholds conducted in 1987, aimed at curtailing the labor costs which would contribute to improving the livestock farming management. The results of this study are as follows: 1. Among the 102 livestock farm household surveyed, 50 farm housecholds were found to cultivate 398a of grassland on average while other 52 farm households produced the forage on the 169a of land under cultivation averagely. 2. Over 50 percent of farm houseolds were reported to have their own agricultural machine for harvesting and cutting, however rates of mechanization in other operations such as mowing and sowing were less than 20 percent. 3. There were more than 50 percent of livestock farm households who have shown their intention to buy and operate their own farming machines when proprer opportunities are given. 4. In order to estimate the long-run demand for agricultural machines for livestock farm household considering current mechanization procedure, data for the machine's optimal capacty, growth of arable acreage for feed stuffs was collected and analyzed. 5. Based on the estimated demand, long range supply plan of livestock farming machines for the period of 1990-2010 was suggested. 6. Finally, measures for technological developement and finanacial support were suggested to implement so as to encourage the farmers' adoption of agricultural machines, and to achieve the goal of mechanization planning for the livestock farm household.

• Asian Journal of Turfgrass Science
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• v.18 no.4
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• pp.201-209
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• 2004

This study was carried out to develope new zoysiagrass cultivar 'Senock' (Patent registration: 10-2003-0072018). Artificial crossing between collected lines of Z. sinica and Z. matrella (collected in South Korea) was conducted to develope F1 plant (CSM) which was cultivated at field for open self-pollination. Among the open pollinated progenies, CSM8 (Senock) showed superior performance in color and density rating. 'Senock' showed genetically dark green color, with medium leaf width ($3.1\pm0.17mm$), low plant height ($14\pm5.67cm$), and wide leaf angle ($67.3\pm11.1degree$). Height to the lowest leaf blade of this cultivar was $2.0\pm0.14cm$, which may allow low mowing height. Specific bands with primer number OPB7 by RAPD analysis can be used for cultivar identification.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.149-156
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• 2003

This paper presents an underwater hybrid navigation system for a semi-autonomous underwater vehicle (SAUV). The navigation system consists of an inertial measurement unit (IMU), an ultra-short baseline (USBL) acoustic navigation sensor and a doppler velocity log (DVL) accompanying a magnetic compass. The errors of inertial measurement units increase with time due to the bias errors of gyros and accelerometers. A navigational system model is derived to include the error model of the USBL acoustic navigation sensor and the scale effect and bias errors of the DVL, of which the state equation composed of the navigation states and sensor parameters is 25 in the order. The conventional extended Kalman filter was used to propagate the error covariance, update the measurement errors and correct the state equation when the measurements are available. Simulation was performed with the 6-d.o.f. equations of motion of SAUV in a lawn-mowing survey mode. The hybrid underwater navigation system shows good tracking performance by updating the error covariance and correcting the system's states with the measurement errors from a DVL, a magnetic compass and a depth senor. The error of the estimated position still slowly drifts in horizontal plane about 3.5m for 500 seconds, which could be eliminated with the help of additional USBL information.

• Journal of Ocean Engineering and Technology
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• v.18 no.4 s.59
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• pp.33-39
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• 2004

This paper presents a hybrid underwater navigation system for unmanned underwater vehicles, using an additional range sonar, where the navigation system is based on inertial and Doppler velocity sensors. Conventional underwater navigation systems are generally based on an inertial measurement unit (IMU) and a Doppler velocity log (DVL), accompanying a magnetic compass and a depth sensor. Although the conventional navigation systems update the bias errors of inertial sensors and the scale effects of DVL, the estimated position slowly drifts as time passes. This paper proposes a measurement model that uses the range sonar to improve the performance of the IMU-DVL navigation system, for extended operation of underwater vehicles. The proposed navigation model includes the bias errors of IMU, the scale effects of VL, and the bias error of the range sonar. An extended Kalman filter was adopted to propagate the error covariance, to update the measurement errors, and to correct the state equation, when the external measurements are available. To illustrate the effectiveness of the hybrid navigation system, simulations were conducted with the 6-d.o.f. equations of motion of an AUV in lawn-mowing survey mode.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.5
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• pp.10-18
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• 2005

The research was carried out to define the morphological and growth characteristics of Poa pratensis L.(Kentucky bluegrass) 'Sewon' in native to Korea. Poa pratensis 'Sewon' was collected at the terrace land on the river in Guiman-ri, Cheongcheon-myeon, Goesan-gun, Chungcheongbuk-do on May 5, 1995. The collected Poa pratensis 'Sewon' was grown under non-mowing naturally growing condition. The morphological characteristics of Poa pratensis 'Sewon' are as follows. : The height of plant was 21.6cm but was increased to 33cm at the flowering time. The height of first node from the base was 5.0cm and the length and width of leaf were 9.6cm and 4.1cm, respectively. The length of inflorecences was 37.8cm and the length of a spike was 7.3cm. Based on these morphological characteristics, Poa pratensis 'Sewon' was defined to dwarf~medium and coarse texture type Kennturky bluegrass. 1 to 9 scale of visual quality, visual color and visual density were measured. Poa pratensis 'Sewon' showed best turf qualities among native Kentucky bluegrasses. In spring and fall growing season, Poa pratensis 'Sewon' were measured to be excellent performances for turf qulities similar to foreign excellent quality cultivars such as Midnight, Nuglade and Brilliant Kentucky bluegrasses. But turf quality of Poa pratensis 'Sewon' decreased by plant disease according to temperature increase in summe compared to foreign excellent quality cultivars. So, Poa pratensis 'Sewon' should be improved of disease tolerent quality by incessant breeding work in order to compete foreign excellent quality cultivars.

• Journal of Biosystems Engineering
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• v.29 no.1
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• pp.1-8
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• 2004

In order to solve the shortage of roughage supply for dairy farm in Korea, winter cereal forage production after harvesting of rice in the fallow paddy field was studied. Two parts are already reported at the previous paper - One was the model development of the mechanized production, and the other was the study of feasibility of the model and its desirable direction in Korea. In this study, the model system is applied for a winter cereal wrap silage production model to practice in Kyungbook National University farm on 3ha scale for 3 years. Results of the research are summarized as follows; It takes 2 or 3 working days to process the wrap silage in middle of May in Daegu region. Also, not much particular problem can be found during the application test of mechanized wrap silage production. Field capacity and field efficiency are estimated to be 0.6-0.85㏊/h and 50-70% in mowing, 1.1∼1.7㏊/h and 52∼80% in tedding and raking, 0.6∼1.1㏊/h and 25∼45％ in baling and 0.5∼0.57㏊/h and 75∼85% in wraping, respectively. Total production cost is estimated to be 1,257won/kg-TDN in oversowing and wrap-silage harvest in 1.6㏊ working area. As a result, large scale field is recommended to produce the wrap silage in order to maximize the field capacity.

• Weed & Turfgrass Science
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• v.2 no.2
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• pp.198-201
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• 2013

This study was carried out to develope new zoysiagrass cultivar Semil' (Registration no. 1749). Artificial crossing between the collected lines of typical Z. matrella, NM1 (collected in South Korea) and the different ecotype of Z. matrella, ASm (collected in South Korea) was made to develop a F1 hybrid plant (NM1 ${\times}$ ASm). Among the 30 progenies, (NM1 ${\times}$ ASm)-1 (Semil) showed superior performance in density rating. 'Semil' showed genetically light green color, with narrow leaf width ($2.7{\pm}0.12mm$), and low plant height ($10.3{\pm}3.7cm$), Length to lowest leaf blade of this cultivar was $1.8{\pm}0.15cm$, which may allow low mowing height upto 12 mm.

• Journal of The Korean Society of Grassland and Forage Science
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• v.18 no.2
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• pp.89-94
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• 1998

A field experiment was carried out to determine the effects of chemical drying agents at mowing on the field drying rate of alfalfa (cv. Vernal) and rye (cv. Koolgrazer) for hastening hay manuf8cture. In alfalfa; chemicals ($K_2CO_3$ 2% $K_2CO_3$ 3% $Na_2CO_3$ 2% $CaCO_3$, 2% $K_2CO_3$2% + $Na_2CO_3$, 1% only water spray and control) were treated at early bloom stage in 1995. Chemicals ($K_2CO_3$, 2%, $Na_2CO_3$, 2% $CaCO_3$, 2% and control) were applicated at different harvest stages (early heading, heading and bloom) in rye, 1996. The drying rate of alfalfa by $K_2CO_3$ treatment among chemicals was higher than control, and the duration of field dry was shortened by one day with $K_2CO_3$ application, but there was no difference in drying efficiency between $K_2CO_3$ 2% and $K_2CO_3$ 3%. In rye, however, no moisture reduction by chemicals was observed. The days required for field dry were 6, 4, and 3 days at warly heading heading and bloom stage respectively; regardless of chemical drying agents and conbol. The nutritive value of rye hay with chemicals at baling was very slightly higher than control, but there was no significant difference. Also, no difference of hay quality was found among drying agents. In conclusion, $K_2CO_3$can enhance the field drying rate of alfalfa hay, but the drying efficiency was not high, particularly in rye hay. Harvesting at early heading to heading stage was desirable for manufacture of high quality rye hay.