• 한국토양비료학회지
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• 제38권4호
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• pp.202-210
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• 2005

정밀 농업 시행에 있어서 포장 변이성에 대한 이해가 필수적이므로, 직파 재배 논에서 포장 변이성 조사와 토양 검정 결과에 다른 질소 변량 시비에 대한 현장 시험이 전북 김제의 직파 재배 논 시험 포장과 농가 시범 포장에서 이루어졌다. $35m{\times}112m$ 단위 포장에서 10 m 간격의 방격형으로 표토의 토양 시료를 채취하여 분석하였다. 토양 유기물, 유효 인산 및 규산, 그리고 치환성 칼륨 등에 대한 분석이 이루어졌다. 시험 포장에 대한 토양 검정 결과에 의해 다수확과 저투입 농업을 위한 질소 시비 추천량을 계산하여 그 분포도를 작성하였다. 2001년과 2002년의 시험 포장에서의 질소 변량 시험을 토대로, 2003년에는 농가 포장 3개를 선정하여 저투입 질소 시비량을 기준으로 질소 변량 시비에 대한 농가 실증 시험을 하였고, 경제성을 분석하였다. 변량 시비에 의해 수량 중가 및 수량 변이 감소 효과를 알 수 있었다. 변량 시비에 의한 수량 증가와 시비량 절감에도 불구하고, 토양 검정에 소요되는 비용이 절감 비용을 초과하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2817-2822
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• 2007

The purpose of this paper is to study the influence of operating condition and ejector geometries on the hydrodynamics and on the mass transfer characteristic of ejector. The CFD results were validated with available experimental data. Flow field analyses and predictions of ejector performance were also carried out. Variation on the operating conditions was made by varying the gas-liquid flow rate ratio in the range of 0.2 to 1.2. The ejector configuration was also varied on the length to diameter ratio of mixing tube ($L_M/D_M$) in the range of 4 to 10. CFD studies show that at $L_M/D_M$ 5.5, the volumetric mass transfer coefficient increases with respect to gas flow rates. Meanwhile, at $L_M/D_M$ 4, the plot of volumetric mass transfer coefficient to gas-liquid flow rates ratio reach maximum at gas-liquid flow rates ratio of 0.6. This study also shows that volumetric mass transfer coefficient decrease with respect to the increase of mixing tube length.

• Weed & Turfgrass Science
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• 제3권4호
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• pp.354-361
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• 2014

This study was conducted to investigate whether several composted liquid manures (CLMs) are useful for biological control of large patch on zoysiagrass and investigate the chemical and biological factors to suppress large patch in soil treated with CLMs. The CLMs were produced at 4 different facilities for livestock excretion treatments located in Korea. Field experiments were carried out at 5 golf courses located near each facility. CLM and Chemical fertilizer (CF: water soluble fertilizer, 20-20-20) were applied four and three times with N at $12g\;m^{-2}$ per year, respectively. There was significant increase of concentration of K, Na, and Cu of soil treated with CLM compared to CF treatment. Among experimental plots, CN and GG2 plot sites were shown significant higher effect of biological control 80% and 50% respectively against large patch disease. The number of bacteria, Actinomycetes, and fungi in soil at these sites significantly increased and fluorescein diacetate hydrolytic activity was enhanced, while the soil was treated with CLM. The results of this study demonstrated that CLM application has effect on soil to suppress large patch and reduce the use of fungicide in environment-friendly turf management.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.758-761
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• 2004

This paper proposes a design and implementation of multiplierless digital PID (Proportional-Integral-Derivative) controller using FPGA (Field Programmable Gate Array) for controlling the speed of DC motor in digital system. The multiplierless PID structure is based on Distributed Arithmetic (DA). The DA is an efficient way to compute an inner product using partial products, each can be obtained by using look-up table. The PID controller is designed using MATLAB program to generate a set of coefficients associated with a desired controller characteristics. The controller coefficients are then included in VHDL (Very high speed integrated circuit Hardware Description Language) that implements the PID controller onto FPGA. MATLAB program is used to activate the PID controller, calculate and plot the time response of the control system. In addition, the hardware implementation uses VHDL and synthesis using FLEX10K Altera FPGA as target technology and use MAX+plusII program for overall development. Results in design are shown the speed performance and used area of FPGA. Finally, the experimental results can be shown when compared with the simulation results from MATLAB.

• The Journal of the Acoustical Society of Korea
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• 제25권1E호
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• pp.32-35
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• 2006

The screech tone of underexpanded jet is numerically calculated without any specific modeling for the screech tone itself. Fourth-order optimized compact scheme and fourth-order Runge-Kutta method are used to solve the 2D axisymmetric Euler equation. Adaptive nonlinear artificial dissipation model and generalized characteristic boundary condition are also used. The screech tone, generated by a closed loop between instability waves and quasi-periodic shock cells at the near field, is reasonably analyzed with present numerical methods for the underexpanded jet having Mach number 1.13. First of all, the centerline mean pressure distribution is calculated and compared with experimental and other numerical results. The instantaneous density contour plot shows Mach waves due to mixing layer convecting supersonically, which propagate downstream. The pressure signal and its Fourier transform at upstream and downstream shows the directivity pattern of screech tone very clearly. Most of all, we can simulate the axisymmetric mode change of screech tone very precisely with present method. It can be concluded that the basic phenomenon of screech tone including the frequency can be calculated by using high-order and high-resolution schemes without any specific numerical modeling for screech tone feedback loop.

• Journal of Forest and Environmental Science
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• 제36권3호
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• pp.255-258
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• 2020

Pine wilt disease (PWD) caused by pine wood nematode (PWN), Bursaphelenchus xylophilus, which is transmitted by Monochamus alternatus and M. saltuarius, is a serious threat to coniferous forests in the Northern Hemisphere, including Korea. The efficacy of abamectin and emamectin benzoate for preventing the PWD in the field and its effect on the vectors Monochamus alternatus and M. saltuarius (Coleoptera: Cerambycidae) were evaluated. An experimental plot was delimited, of which consists of Japanese red pine (Pinus densiflora) forest in South Korea, and trunk injection trials were made with abamectin and emamectin benzoate. Branches of each tree were collected, and are subsequently subjected to the analysis of residues for both nematicides. Results obtained in this study showed that abamectin and emamectin benzoate showed over 90% mortality at the recommended concentration after 6 days and 8 days, respectively. Consequently, it was found that both insecticides have a higher effect on the susceptibility and persistence of two vectors of PWD, M. alternatus and M. saltuarius feeding on branches of the trees, and its application by trunk injection is confirmed as an option for pine wilt disease management programs in Korea.

• 대한기계학회논문집B
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• 제28권9호
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• pp.1005-1014
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• 2004

Experiments were done for the three dimensional unsteady flow in a counter-rotating axial flow fan under peak efficiency operating condition. Flow fields in a counter rotating axial flow fan were measured at cross-sectional planes of the upstream and downstream of each rotor. Cross sectional flow patterns were investigated through the acquired data by the 45$^{\circ}$ inclined hot-wire. Flow characteristics such as tip vortex, secondary flow and tip leakage flow were confirmed through axial, radial and tangential velocity vector plot. It has been found that the radial and tangential velocity components disappeared, while the axial velocity component highly increased as soon as the tip vortex was generated. It has been observed that secondary flow and turbulence intensity which were increased by the front rotor were dissipated passing through the rear rotor. As the result the energy loss of the counter rotating axial flow fan decreased at the downstream of rear rotor. Also, it has been verified that tip vortex pattern of the rear rotor was dampened because the tip vortex generated by front rotor was mixed with that of the rear rotor.

• 한국초지조사료학회지
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• 제16권2호
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• pp.169-176
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• 1996

An experiment was carried out to determine the effect of cultivar and tedding frequency on changes of moisture content of oat(Avena sativa L.) hay during field drying and on quality of baled oat hay after storage. The experimental design was a split-plot with the four oat cultivm such as 'Magnum', 'Cayuse', 'West' and 'Murray' as main plots and the two tedding frequencies such as 1 or 3 times a day as subplots in three replications. Moisture content of fresh cut oat cultivar was higher in the order of 'Magnum', 'Cayuse', 'West', and 'Murray' and the moisture content difference among the cultivm was maintained to the final curing day(P< 0.05). Moisture loss from the oat hay during the last 3 curing days was greater with 3 tedding a day than I tedding a day. Temperature of baled oat hay began to rise critically from the 6th day of storage and wa5 highest in 'Magnum' oat cultivar($45.3^{\circ}C$). Total nitrogen and ADIN contents of late maturing oat hay 'Magnum' and 'Cayuse' were higher than those of early maturing 'Murray' and 'West'. Tedding frequency did not influence total nitrogen and ADIN contents. ADF and NDF contents of early maturing oat hay were higher than those of late maturing oat hay. Relative feed value (RFV) of 'Magnum' oat hay was the highest(l06) and classified as Grade 2 in forage quality standard. Quality grade difference between early and late maturing oat cultivan was only 1 or 2.

• 한국초지조사료학회지
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• 제8권3호
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• pp.147-151
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• 1988

The preference, chemical composition, intake, digestibility and chewing efficiency of collected herbage sample from sheep using esophageal fistula and fecal collection method were compared to those of offered herbage samples on the native and improved pastures at the 3rd flush stage(25 cm grass height). Experimental field was treated by one plot design and the begining of September 1987, at Chungnam National University, Daejon. The results obtained are summarized as follows: 1. Preference indices were not different among herbage species on improved pasture, while those on in native pasture were markedly different and this difference seemed to depend on diet selection. 2. Chemical compositions of collected herbage samples were different from those of offered herbage samples. Crude protein content was significantly high on native pasture, but NDF, cellulose and lignin content were significantly low on improved pasture (p < 0.01). 3. DM intake, digestibility and herbage utilization percent on improved pasture were significantly higher than those on native pasture (P < 0.01). 4. Eating rate, ruminating and chewing efficiency were influenced by the amounts of NDF intake. Therefore, eating rate, ruminating and chewing efficiency on improved pasture tended to be higher than those on native pasture (p <0.01).

• Journal of Ginseng Research
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• 제29권4호
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• pp.185-191
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• 2005

In vitro and in vivo effectiveness of fungicides were evaluated for the control of damping off caused by Rhizoctonia solani on Panax ginseng. Fludioxonil(67 mg a. i./L), flutolanil(75 mg a. i./L), thifluzamide(35 mg a. i./L), and mepronil (750 mg a. i./L) were selected from 9 fungicides, which were based on inhibition of mycelial growth of R. solani (isolate Rh 9801) and duration of fungicidal effectiveness against the pathogen in vitro. Field trials were made twice in the year of 2003 and 2004. Experimental plots $(54m{\times}0.9m)$ of 4-year-old ginseng fields were artificially infested with 5kg and 14 kg in fresh weight of inoculum in 2003 and 2004, respectively. The fungicides were drenched at a volume of 8l in $3.6m{\times}0.9m$ with 3 replications. Fludioxonil, flutolanil, thifluzamide and mepronil reduced the incidence of damping off by $73\%,\;69\%,\;69\%\;and\;43\%$, respectively. In the 2004 trial, fludioxonil, flutolanil, and thifluzamide showed similar result as reducing the incidence by $85\%,\;84\%,\;and\;82\%$, respectively, in the plot where the inoculum was applied 2.8 times more than the 2003. The disease incidences in untreated control were $12\%$ in 2003 and $47\%$ in 2004.