• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.7
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• pp.571-583
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• 2006

To secure high yield and good quality of rice, plant growth and nitrogen (N) nutrition status should be taken into account for managing panicle N topdressing (PN). This research aimed at investigating the rice yield response to PN under different plant growth and N nutrition status that was conditioned by different rates of basal and tillering N fertilizer (BTN). Stepwise multiple regression (SMR) was used for the analysis of yield response to (i) BTN and PN, and (ii) shoot N content at PIS (BTNup) and shoot N uptake from PIS to harvest (PNup). Rice yield increased significantly as BTN and PN Increased, but there was no significant interaction between BTN and PN. Yield increased almost linearly with the increasing BTN and PN up to $10{\sim}12$ and $6{\sim}7\;kgN/10a$, and with the increasing BTNup and PNup up to $6{\sim}7$ and $5{\sim}6\;kgN/10a$, respectively. But yield increment tended to decrease above those levels. These declines resulted from the decreased ripened grain ratio and 1000 grain weight even though spikelet number per unit area increased more at above those N levels. Spikelet number per unit area had the linear relationships with the shoot N uptake until heading, and with yield. Like most yield response curves, yield response in this experiment followed the diminishing return function with BTNup, PNup, and plant N uptake from seeding to harvest. Regardless of the degree of BTNup and PNup, yield had a quadratic relationship ($R^{2}$>0.88) with whole shoot N accumulation until harvest, suggesting that the yield determination was closely related with the whole shoot N uptake until harvest regardless of the differences in seasonal shoot N uptake.

• Journal of the Korean Magnetics Society
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• v.13 no.1
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• pp.1-5
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• 2003

Magnetic and structural properties of $(CoFe_2O_4)_{1-x}(Y_3Fe_5O_{12})_x$ powders (0 $\leq$ x $\leq$ 1) grown by a conventional ceramic method were investigated using X-ray diffractormeter (XRD), scanning electron microscopy (SEM), Mossbauer spectroscopy and vibrating sample magnetometer (VSM). The XRD results for the powders annealed at 120$0^{\circ}C$ indicated that no other peak was observed except for the ones from cobalt ferrite and the garnet powder. SEM micrographs indicated that cobalt ferrite and garnet powders were aggregated and completely formed together. It was hard to identify which part of the powders was the garnet or the cobalt ferrite. Mossbauer spectra for powders grown separately and mixed mechanically consisted of sub-spectra of cobalt ferrite and garnet, however, powders annealed together had an extra sub-spectrum, which was related with the interaction between iron ions at the grain surfaces of cobalt ferrite and the garnet: cobalt ferrite and garnet particles were located very closely. The value of the saturation magnetization measured by a VSM as a function of composition ratio agreed very well with the ones based on the theoretical calculation.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.10
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• pp.1443-1450
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• 2003

Crossbred (Bos taurus${\times}$Bos indicus) calves were used from birth till 14 weeks of age to evaluate three sources of protein that differed in ruminal degradability viz. groundnut cake alone (HD) or in combination with cottonseed meal (MD) and meat and bone meal (LD), when fed along with two sources of non-structural carbohydrates viz. raw (R) and thermally processed (P) maize. Twenty four new born calves were arranged in six groups in a $3{\times}2$ factorial design and fed on whole milk up to 56 d of age. All the different calves received calf startes along with green oats (Avena sativa) from 14 d of age onwards free-choice. A metabolism trial of 6d starters duration, conducted after 90 d of experimental feeding, revealed greater (p<0.05) digestibility of DM, OM, total carbohydrates, NDF and ADF in calves fed on the P diets than on the R diets promoting greater (p<0.05) metabolizable energy intake. The digestibility of NDF was higher (p<0.01) on LD diets where as calves on MD diets exhibited significantly lower digestibility of ADF (p<0.01). The retention of nitrogen per unit metabolic body size was significantly (p<0.05) higher on the LD-P diet than on the diet HD-P which, in turn, was higher (p<0.05) than that of HD-R. Nitrogen retention as percentage of intake was significantly greater (p<0.05) on LD-P than on LD-R diets (52.2 vs. 36.4%). Also, P fed calves utilized nitrogen more efficiently than the R fed as shown by retention of significantly greater proportions of intake (47.4 vs. 40.9%) and absorbed (65.8 vs. 59.5%) nitrogen. Calorimetric evaluation of the diets through open-circuit respiration chamber revealed that the dietary treatments had no impact on methane production by calves. The intake of DE and ME was improved (p<0.01) because of maize processing resulting in greater (p<0.01) retention of energy. The protein degradability exerted no influence on the partitioning or retention of energy. A significant interaction between cereal and protein types was evident with respect to retention of both nitrogen (p<0.01) and energy (p<0.05). In conclusion, no discernible trend in the influence of cereal processing was apparent on the dietary protein degradability, but the positive effect of cereal processing on energy retention diminished with the increase in dietary undegradability.

• Korean Journal of Weed Science
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• v.2 no.1
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• pp.13-19
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• 1982

The effect of metolachlor [2-chloro-N-(2-ethyl 1-6-methylphenyl)-N-(2-methoxy-l-methylethyl)-acetamide] on starch, sugar and protein content in relation with ${\alpha}$-amylase activity, and its interaction with GA in the germinating stage of rice were determined. The distinctive phytotoxic symptom was the failure of the primary leaf of rice to break the coleoptile. An inhibitory effect of metolachlor was nullified by the external application of GA $10^{-3}$M. A significantly slower starch degradation accompanying the lower content of sugars was observed in the gain of the metolachlor treated seedlings. Further, the total ${\alpha}$-amylase activity was significantly lower in the grain of rice seedlings treated with metolachlor than that of the untreated one, and the lower total ${\alpha}$-amylase activity could be due to an inhibition of ${\alpha}$-amylase formation.

• Korean Journal of Poultry Science
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• v.33 no.3
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• pp.239-248
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• 2006

Improvements in understanding the effects of dietary fermentable carbohydrates and their interaction with supplemental feed enzymes and the feed manufacturing process may lead to reductions in volatile organic compound (VOC) emissions from poultry manure. Starch digestibility has been improved by replacing ground wheat or barley with whole wheat or barley, but there was no consistent effect of cereal species or feed form on the pH value of the gizzard contents. Pelleting results in improvements in feed conversion from 0 to 12%. Starch digestibility has been reported to account for up to 35 % of the improvement in available metabolic energy as a result of xylase supplementation. Factors which affect starch utilization and non-starch polysaccharide (NSP) absorption include the presence of anti-nutrient facto. (ANF) in grains, the nature of grain starch, NSP and the digestive capacity of animals. Improvements in feed production technology have been made in enzyme stabilization, allowing some dry enzyme products to be pelleted after conditioning at up to $87.69^{\circ}C$ and liquid enzymes to be stored in the feed mill for up to low months prior to use. The soluble NSP, arabinokylans and beta-glucans are partially degraded into smaller fragments by enzymes. With fragmentation, the water holding capacity is decreased, which leads to a reduction in digesta moisture, wet feces, and dirty eggs from hens fed diets containing viscosity-inducing ingredients.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.214-227
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• 2018

An object oriented crop model was developed to perform crop growth simulation taking into account complex interaction between biotic and abiotic factors in an agricultural ecosystem. A set of classes including Atmosphere class, Plant class, Soil class, and Grower class were designed to represent weather, crop, soil, and crop management, respectively. Objects, which are instance of class, were linked to construct an integrated system for crop growth simulation. In a case study, yield of corn and soybean, which was obtained at an experiment farm in Rural Development Administration from 1984 to 1986, were compared with yield simulated using the integrated system. The integrated system had relatively low error rate of corn yield, e.g., <4%, under sole and intercropping conditions. In contrast, the system had a relatively large underestimation error for above ground biomass except for grain compared with those observed for corn and soybean. For example, estimates of biomass of corn leaf and stem was 31% lower than those of observed values. Although the integrated system consisted of simple models, the system was capable of simulating crop yield under an intercropping condition. This result suggested that an existing process-based model would be used to have more realistic simulation of crop growth once it is reengineered to be compatible to the integration system, which merits further studies for crop model improvement and implementation in object oriented paradigm.

• Molecules and Cells
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• v.25 no.3
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• pp.417-427
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• 2008

Comparison of maps and QTLs between populations may provide us with a better understanding of molecular maps and the inheritance of traits. We developed and used two reciprocal $BC_1F_1$ populations, IP/DS//IP and IP/DS//DS, for QTL analysis. DS (Dasanbyeo) is a Korean tongil-type cultivar (derived from an indica x japonica cross and similar to indica in its genetic make-up) and IP (Ilpumbyeo) is a Korean japonica cultivar. We constructed two molecular linkage maps corresponding to each backcross population using 196 markers for each map. The length of each chromosome was longer in the IP/DS//IP population than in the IP/DS//DS population, indicating that more recombinants were produced in the IP/DS//IP population. Distorted segregation was observed for 44 and 19 marker loci for the IP/DS//IP and IP/DS//DS populations, respectively; these were mostly skewed in favor of the indica alleles. A total of 36 main effect QTLs (M-QTLs) and 15 digenic epistatic interactions (E-QTLs) were detected for the seven traits investigated. The phenotypic variation explained (PVE) by M-QTLs ranged from 3.4% to 88.2%. Total PVE of the M-QTLs for each trait was significantly higher than that of the E-QTLs. The total number of M-QTLs identified in the IP/DS//IP population was higher than in the IP/DS//DS population. However, the total PVE by the M-QTLs and E-QTLs together for each trait was similar in the two populations, suggesting that the two $BC_1F_1$ populations are equally useful for QTL analysis. Maps and QTLs in the two populations were compared. Eleven new QTLs were identified for SN, SF, GL, and GW in this study, and they will be valuable in marker-assisted selection, particularly for improving grain traits in tongil-type varieties.

• Korean Journal of Agricultural Science
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• v.6 no.1
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• pp.1-14
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• 1979

Selection index methods were applied to selecting better performing rice varieties with better plant characters from rice yielding trials tested under six different cultural methods. The results obtained were summarized as follows: 1. Varieties such as NO. 3, 4, 5 and 6 were selected as best performing varieties with good plant and grain characters. 2. Selection index I computed from Hazel's method was appeared effective for selecting rice varieties grown under general optimum environmental conditions, while selection index II computed from Pesek and Baker's desired genetic gain were effective for selecting rice varieties grown under rather stressed conditions. 3. The rank of mean yield of each variety was not completely in agreement with that of index values, which indicates the importance of other characters besides yield in selecting varieties. 4. Most characters studied were high in broad sense of heritabilities. 5. No significant interaction was found between varieties and cultural methods.

• Ocean Systems Engineering
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• v.6 no.1
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• pp.23-60
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• 2016

The major objective of this study was to develop further understanding of 3D nearshore hydrodynamics under a variety of wave and tidal forcing conditions. The main tool used was a comprehensive 3D numerical model - combining the flow module of Delft3D with the WAVE solver of XBeach - of nearshore hydro- and morphodynamics that can simulate flow, sediment transport, and morphological evolution. Surf-swash zone hydrodynamics were modeled using the 3D Navier-Stokes equations, combined with various turbulence models (${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES). Sediment transport and resulting foreshore profile changes were approximated using different sediment transport relations that consider both bed- and suspended-load transport of non-cohesive sediments. The numerical set-up was tested against field data, with good agreement found. Different numerical experiments under a range of bed characteristics and incident wave and tidal conditions were run to test the model's capability to reproduce 3D flow, wave propagation, sediment transport and morphodynamics in the nearshore at the field scale. The results were interpreted according to existing understanding of surf and swash zone processes. Our numerical experiments confirm that the angle between the crest line of the approaching wave and the shoreline defines the direction and strength of the longshore current, while the longshore current velocity varies across the nearshore zone. The model simulates the undertow, hydraulic cell and rip-current patterns generated by radiation stresses and longshore variability in wave heights. Numerical results show that a non-uniform seabed is crucial for generation of rip currents in the nearshore (when bed slope is uniform, rips are not generated). Increasing the wave height increases the peaks of eddy viscosity and TKE (turbulent kinetic energy), while increasing the tidal amplitude reduces these peaks. Wave and tide interaction has most striking effects on the foreshore profile with the formation of the intertidal bar. High values of eddy viscosity, TKE and wave set-up are spread offshore for coarser grain sizes. Beach profile steepness modifies the nearshore circulation pattern, significantly enhancing the vertical component of the flow. The local recirculation within the longshore current in the inshore region causes a transient offshore shift and strengthening of the longshore current. Overall, the analysis shows that, with reasonable hypotheses, it is possible to simulate the nearshore hydrodynamics subjected to oceanic forcing, consistent with existing understanding of this area. Part II of this work presents 3D nearshore morphodynamics induced by the tides and waves.

• Korean Journal of Materials Research
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• v.8 no.10
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• pp.961-968
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• 1998

In order to investigate the effects of substrate bias voltage on the formation of$ZnS-SiO_2$ protective film in phase change optical disk by R.F. magnetron sputtering method, thin dielectric film was formed on Si wafer and Corning glass by using ZnS(80mol%)-$SiO_2$(20mol%)t arget under argon gas. In this study, the Taguchi experimental method was applied in order to obtain optimum conditions with reduced number of experiments and to control numerous variables effectively. At the same time this method can assure the reproducibility of experiments. Optimum conditions for film formation obtained by above method were target RF power of 200 W. substrate RF power of 20 W, Ar pressure of 5 mTorr. sputtering time of 20 min.. respectively. The phase of specimen was determined by using XRD and TEM. The compositional analysis of specimen was performed by XPS test. In order to measure the thermal resistivity of deposited specimen, annealing test was carried out at $300^{\circ}C$ and $600^{\circ}C$. For the account of void fraction in thin film, the Bruggeman EMA(Effective Medium Approximation) method was applied using the optical data obtained by Spectroscopic Ellipsometry. According to the results of this work, the existence of strong interaction between bias voltage and sputtering time was confirmed for refractive index value. According to XRD and TEM analysis of specimen, the film structure formed in bias voltage resulted in more refined structures than that formed without bias voltage. But excess bias voltage resulted in grain growth in thin film. It was confirmed that the application of optimum bias voltage increased film density by reduction of void fraction of about 3.7%.