• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.04a
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• pp.54-55
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• 2006

Organic light-emitting diodes(OLEOs) are attractive because of possible application in display with low operating voltage, low power consumption, self-emission and capability of multicolor emission by the selection of emissive material. We investigated the effects of deposition rate on the electrical characteristics, physical characteristics and optical characteristics of OLEOs in the ITO(indium-tin-oxide)/N.N'-diphenyl-N,N'-bis(3-methyphenyl)-1,1'-biphenyl-4,4'-diamine(TPD)/tris(8-hydroxyquinoline)aluminum($Alq_3$)/Al device. We measured current density, luminous flux and luminance characteristics of devices with varying deposition rates of TPD and $Alq_3$. It has been found that optimal deposition rate of TPD and $Alq_3$ were respectively $1.5{\AA}/s$ from the device structure. An AFM measurement results, surface roughness of the deposited film was the lowest when deposition rate was $1.5{\AA}/s$.

• Journal of Environmental Health Sciences
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• v.26 no.4
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• pp.9-14
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• 2000

In this study, the removal efficiencies of organics, nitrogens and phosphorus from municipal wastewater using $A^2$/O process were investigated. BO $D_{5}$ removal efficiencies were indicated 95% and 94% with HRT of 12 hr and 10 hr, respectively. CO $D_{Cr}$ average removal efficiency and concentration of effluent were indicated 87% and 34mg/$\ell$. SS average removal efficiency and concentration of effluent were indicated 93% and 4~17mg/$\ell$. T-N removal efficiency and concentration of effluent were shown as 60~80% and below 15mg/$\ell$. In aerobic basin, removal efficiency of N $H_4$-N was shown over 97% with N $H_4$-N volume load 0.16kg N $H_4$-N/㎥.d and in anoxic basin, denitrification efficiency was indicated over 80% with return sludge rate 0.5Q and internal recirculation rate 2.5Q. Removal efficiency and effluent concentration of phosphorus were shown over 80% and below 2 mg/$\ell$ with return sludge rate 0.5Q.Q.

• Journal of Biosystems Engineering
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• v.28 no.4
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• pp.361-368
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• 2003

This study was intended to investigate the temporal and spatial variabilities of dry matter, nitrogen content, chlorophyll of paddy rice and yield caused by different rates of nitrogen application. An experimental field was divided into 45 plots of 3.48 ${\times}$ 12 m in size and application rate of nitrogen varied from 0 to 235% with an increment of 25% based on the standard rate of N-P$_2$O$_{5}$-K$_2$O=12-8-8 kg/10a. The measurements were made 8 times every 9-10 days after the transplanting. About 60 days after the transplanting, there exhibited little variabilities in the dry matter caused by different rates of nitrogen application. After that. however, there showed large variabilities and the dry matter increased with the application rate. The nitrogen content of paddy also increased with the application rate but it was inconsistent. After the tillering period, the nitrogen content remained constant. In the early stage of the tillering period the nitrogen content decreased in spite of increase in the dry matter. However. after a certain period of time it increased with the dry matter. There were little variabilities of chlorophyll after the transplanting. However, the SPAD increased with application rate of nitrogen as the paddy grew. After the tillering period SPAD was not affected by the different rates. More yield was obtained at the plots where larger nitrogen content was measured.d.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.2
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• pp.71-76
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• 2003

In order to determine the influence of nitrogen on agronomic characters, forage yield and quality, Jeju Italian millet(Setaria italica Beauvis) was grown on the volcanic ash soil at the Experimental Farm of Cheju national university under the six levels of nitrogen rates (0, 50, 100, 150, 200, 250kg/ha) from May 1, 2000 to August 25, 2000. Days to heading was delayed 92∼98 days as nitrogen rate increased. Plant height was 96cm at 0kg N/ha. as N rate increased, grew gradually, was 134cm at 200kg N/ha, 135cm at 250kg N/ha, and was not significantly affected between the two plots. Fresh forage, dry matter, crude protein and TDN yield increased 18.88∼42.82MT/ha, 8.45 ∼12.25MT/ha, 0.76∼1.59MT/ha and 4.32∼6.79MT/ha, respectively, as the increasing of N rate, but were not significant between 200kg N/ha and 250kg N/ha. As N rate increased, crude protein, crude fat, NFE and TDN content increased 9.0∼13.0%, 1.4∼1.7%, 9% and 51.1∼55.5%, respectively, but crude ash and crude fiber content decreased 8.7∼8.2% and 34.9∼30.2%, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.4
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• pp.247-255
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• 2005

ice yield and plant growth response to nitrogen (N) fertilizer may vary within a field, probably due to spatially variable soil conditions. An experiment designed for studying the response of rice yield to different rates of N in combination with variable soil conditions was carried out at a field where spatial variation in soil properties, plant growth, and yield across the field was documented from our previous studies for two years. The field with area of 6,600 m2 was divided into six strips running east-west so that variable soil conditions could be included in each strip. Each strip was subjected to different N application level (six levels from 0 to 165kg/ha), and schematically divided into 12 grids $(10m \times10m\;for\;each\;grid)$ for sampling and measurement of plant growth and rice grain yield. Most of plant growth parameters and rice yield showed high variations even at the same N fertilizer level due to the spatially variable soil condition. However, the maximum plant growth and yield response to N fertilizer rate that was analyzed using boundary line analysis followed the Mitcherlich equation (negative exponential function), approaching a maximum value with increasing N fertilizer rate. Assuming the obtainable maximum rice yield is constrained by a limiting soil property, the following model to predict rice grain yield was obtained: $Y=10765{1-0.4704^*EXP(-0.0117^*FN)}^*MIN(I-{clay},\;I_{om},\;I_{cec},\;I_{TN},\; I_{Si})$ where FN is N fertilizer rate (kg/ha), I is index for subscripted soil properties, and MIN is an operator for selecting the minimum value. The observed and predicted yield was well fitted to 1:1 line (Y=X) with determination coefficient of 0.564. As this result was obtained in a very limited condition and did not explain the yield variability so high, this result may not be applied to practical N management. However, this approach has potential for quantifying the grain yield response to N fertilizer rate under variable soil conditions and formulating the site-specific N prescription for the management of spatial yield variability in a field if sufficient data set is acquired for boundary line analysis.

• Applied Biological Chemistry
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• v.37 no.4
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• pp.277-286
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• 1994

The pot experiment using $^{15}N$ isotope dilution technique was carried out to calculate the balance of nitrogen of surface applied urea in the rice-soil system. The $^{15}N$ concentration was determined by stable isotope ratio mass spcetrometer (model: VG ISO-GAS MM622). In the pots with $^{15}N$ labeled urea application at the rates of 15 and 30 kg N/10a, the percentage of nitrogen derived from fertilizer (NDFF) in rice was higher at the rate of 30 kg N/10a (average 89%) than at the rate of 15 kg N/10a (average 64%). However, the recovery as percentage of fertilizer N by rice was higher at the rate of 15 kg N/10a (65.5%) than at the rate of 30 kg N/10a (54.2%). The percentage of the fertilizer N remained in extractable inorganic N form at the rates of 15 and 30 kg N/10a were $13.5%\;(NH_4-N\;5.53%,\;NO_3-N\;7.99%)$ and $16.5%\;(NH_4-N\;7.49%,\;NO_3-N\;8.98%)$ in unplanted soil, and $2.0%\;(NH_4-N\;0.63%,\;NO_3-N\;1.32%)$ and$2.3%\;(NH_4-N\;0.87%,\;NO_3-N\;1.40%)$ in soil planted to rice, respectively. The dominant form of inorganic-N in soil after harvest was $NO_3-N$ form rather than $NH_4-N$ form regardless of urea application rate or rice cultivation. The percentage of the fertilizer N remained in organic N form at the rates of 15 and 30 kg N/10a were 65.0 and 41.8% in unplanted soil, and 23.7 and 26.9% in soil planted to rice, respectively. In conclusion, the efficiency of surface-applied urea was greater at the rate 15 kg N/10a than at the rate of 30 kg N/10a.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1302-1306
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• 2005

This study has Performed to develop rehabilitation model for determination of optimal rehabilitation time on the Cast Iron Pipes (CIP) with diameter less than 300 mm in water pipeline network and to analysis the sensitivity on the rehabilitation times of developed model. In the result from the application of the field, the renovation time was faster about 10 years than the replacement time. Especially, as the difference between rehabilitation and replacement time on E-CIP was about from 3 to 5 years, and it was thought that the replacement was effective on E-CIP. To sensitivity analysis, the discount rate of coefficient was fixed at 0.08, and the values of initial year break rate(N($t_o$) and growth rate coefficient(A) were adjusted in values of 0.0009, 0.0018, 0.0027, and 0.05, 0.10, 0.15 respectively. When the values of N($t_o$) and A was increased, the results from the time of rehabilitation and replacement was faster It was thought that N($t_o$), 0.018 was reliable values on the applied pipeline through the result of the study. In case of A, the values of A above 0.1 was thought to be Proper.

• Korean Journal of Soil Science and Fertilizer
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• v.30 no.2
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• pp.114-121
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• 1997

Latex Coated Urea(LCU) was compared with ordinary urea under different methods of application in terms of N use efficiency and yield of rice, 1995 and 1996. The study was carried out on Jeonbug silty clay loam, in Honam Agricultural Experiment Station. The fertilizer treatments involved (1) conventional application of urea (44kg N/ha at transplanting, 33kg N/ha at five leaves stage, 33kg N/ha. (4) 55kg N/ha at transplanting and 33kg N/ha as urea at panicle initiation stage, and (5) without N. It was found that by combining LCU(as basal application) and urea(as topdressing at panicle initiation stage), at the rate of 80% of conventional rate with ordinary urea is most effective for the saving of N and increasing the use efficiency of N by rice. It was, however, observed that the efficacy of LCU was affected by the temperature during the growth of rice.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.4
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• pp.411-419
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• 1996

The experiment was aimed to determine a change of chemical component in irrigatted water based on different tillage methods and nitrogen rates under mulching of barley straw in direct seeded rice. There was no difference in water pH of no-tillaged plot but high in tillaged plot until 10 days after treatment. The electric conductivity(EC) of the water was higher in no-tillaged plot than in tillaged plot. However, the dissolved oxygen content was vice versa. The content of NH$_4$-N was high in higher application rate of N fertilizer without the tillage. Mean while, NO$_3$-N content was highly affected by no-till aged plot particularly in between application time and fertilizer rate but not in tillaged plot. There was higher in P043- content with the no-tillaged plot compared to the tillaged plot. It was big difference with higher application rate of the fertilizer. Soil cations were high in much application of fertilizer without the tillage.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.42-47
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• 2019

In this research, we try to study the change of squareness in the cutting process while changing cutting conditions such as feed rate and spindle rotational speed with chromium molybdenum steel (SCM415) material and TiCN, TiAlN coated end mill tool. The TiCN coating tool had the best straightness at 4,000 rpm at a feed rate of 200 mm/min. The TiAlN coating tool was best measured at 3,000 rpm at a feed rate of 200 mm/min. TiAlN coated tools had excellent dimensional tolerance when comparing the coating tool specifics.