• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.457-463
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• 2005

In the present work, the design of fuel system for Smart UAV focused on the main components such as fuel feed system, fuel tank vent system, and refueling system was conducted. Based on the previous conceptual design results, the size of the component was calculated with refined airframe structure data and accurate engine data. It was verified that the design requirements for the feed system, vent system, and refueling system were satisfied.

• Asian Journal of Turfgrass Science
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• v.21 no.1
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• pp.1-7
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• 2007

This study was initiated to evaluate the qualitative characteristics of creeping bentgrass(Agrostis palustris Huds.) cultivars for the climate In Korea through the NTEP(Nat'l Turfgrass Evaluation Program) data. 'L-93' showed the highest rating in overall mean visual quality. It was also the most prominent cultivar in seedling vigors, ground cover, and genetic color especially in summer. In case of turf texture, 'Penn A-1' and 'A-2' were the finest group, but the poorest group in cold tolerance. Leaf density and thatch accumulation were lower with 'Penncross', 'Pennlinks', 'Crenshaw', and 'L-93' as compared with 'Penn A'-type and 'G'-type cultivars. Resistance to moss invasion was greater with 'Penn A'-type and 'G'-type cultivars, but 'Penncross' was the least. These observations indicated that leaf density was considered to associate with the characters of turf quality, thatch accumulation and resistance to moss invasion. 'Penn A'-type cultivars were highly resistant to snow mold. Greater resistance to brown patch was associated with 'Penn A' and 'Penncross'. Higher resistance to pythium blight was found with 'Penncross' and 'Pennlinks'. 'L-93' showed higher resistance to dollar spot, but not to pythium. Therefore, these results demonstrated that turf maintenance program for the new bentgrass cultivars should be different from a conventional management for the cultivar of 'Penncross'.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.58-64
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• 2015

The black cutworm, Agrotis ipsilon (Hufnagel) is a major insect pest of economic crops including turfgrasses on golf courses. The entomopathogenic nematode, Steinernema carpocapsae GSN1 strain (ScG), a Korean isolate, is an effective biological control agent for soil dwelling and greenhouse insect pests in Korea. In addition, ScG is commercially produced in Korea. We conducted laboratory, greenhouse, and field trials to evaluate efficacy of ScG against black cutworms in turfgrasses. A rate of 63 infective juveniles (Ijs) per larva killed >90% of $3^{rd}$ instars feeding in cups of artificial diet within 3 days. In greenhouse trials against cutworms feeding in pots of turfgrass, efficacy of ScG was higher against $4^{th}$ instars than against $2^{nd}$ instars (90.0 vs 81.2% mortality, respectively, at $2,000Ijs\;pot^{-1}$) in perennial ryegrass, and higher against $3^{rd}$ instars in creeping bentgrass, Agrostis palustris than in zoysiagrass, Zoysia japonica (96.7 vs 52.5% mortality at $100,000Ijs\;m^{-2}$) in pot. The corrected mortality of $4^{th}$ instar was 79.9% at the rate of $100,000Ijs\;m^{-2}$ in the creeping bentgrass in the field. So ScG could be used as biological control agent against black cutworm in turfgrass of golf courses.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.76-81
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• 2014

Military helicopter is exposed to the enemy gun firing due to the low altitude flight of contour flight, hovering & nap of the Earth flight, therefore it has the high possibility to be exploded by the gun firing. Recently the Anti-ballistic requirement is required to get the high level of safety from gun firing in required operational capability. The first military utility helicopter of SURION has the Anti-ballistic requirement and explosion proof. In order to meet the requirement, OBIGGS is adopted for the first time in KUH. It is proven that Anti-Explosion capability is satisfied to requirement for improving vent system which was insufficiently designed in development period and related to Anti-explosion.

• Asian Journal of Turfgrass Science
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• v.22 no.2
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• pp.161-170
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• 2008

Recently irregular dark-colored patches were found on the Kentucky teeing ground in a golf course in Gyunggi providence. Interestingly, blue-green algae from the leaf tissue sample containing black spot-stained symptoms were largely observed through microscopic study. In general, algae present on the upper soil surface or in the upper layer of root zone form dark brown layers of scum or crust, which invoked harmful effects to turf growth such as poor drainage, inhibition of new root development. In this observation, unlike the algae were sometime found in senescing leaves on contacted soil in July and August, the blue-green algae were detected within black spot-stained Kentucky bluegrass leaf tissues including leaf blade, ligule, auriclea as well as leaf sheath. The blue-green algae were also detected on the leaf and stem tissue adjacent to the symptomatic leaf tissues. Two species of blue-green algae, Phomidium and Oscillatoria, were greatly observed. Oscillatoria species was more commonly notified in all samples. In addition, the two species were found on a putting green showing yellow spot disease at another golf course in Gyunggi providence. The data from chemical control assay revealed that chemicals such as propiconazole, iprodione, and azoxystrobin decreased blue-green algae population and leaf spots, which finally resulted in enhanced leaf quality. All taken together, we strongly suggested that the disease-like phenomenon by blue-green algae might be very closely mediated with infection/translocation process in relation with turfgrass. It indicates that blue-green algae in turf management may play an adverse role as a secondary barrier as well as a pathogenic agent. This report may be helpful for superintendents to recognize and understand the fact that algae control should be provided more cautiously and seriously than we did previously in upcoming golf course management.