• Journal of Sericultural and Entomological Science
• /
• v.29 no.1
• /
• pp.7-11
• /
• 1987

The influence of planting density, on the mulberry yield, had been studied for 5 years period since 1982. For this purpose, a hilly land (15$^{\circ}$) was selected and 5 planting density level (926, 1,667, 2,780 and 3,444 tree/10a) were used. Following results were obtained. 1. Vinyl mulching promoted 2 days earlier of green tip sprouting stage and 3 days earlier of shallow-bill stage, compared with the non-mulching. 2. It was shown that increase of the length of the branch with vinyl mulching and decrease of the mulching effect with the higher density of plants from, 2,780 tree/10a. 3. When the planting density was higher, length and width of leaf was decreased sharply, and chlorosis of the lower part of the branch was occured heavily. 4. With the higher planting density, number of branches per tree and average length of the branch was decreased. Number of shorter branch-normal branch ratio were increased. However, number of branches and total length of branch per area were shown opposite. 5. Yield of mulberry was increased for the peroid of 3 years after planting with the all the levels of planting density after that, yield increase was dully in 926 tree plot, and more dully in 1,677 trees plot, while decrease of the yield were showen with density of 2,780 and 3,444 trees plots. 6. The highest average yield for the 5 years were obtained from 2,780 trees plot, 46.6% higher than in 926 trees plot, followed 40% higher in 3,444 trees plot, and 29.9% higher in 1,667 trees plot. 7. Soil pH, organic matter, Ca and Mg decreased with cultivation, especially P2O5, pH, Ca and Mg in the density of more than 926 trees plot.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.28 no.4
• /
• pp.240-249
• /
• 2016

In this study, we investigated wave force distribution at points on a vertical structure of semi-infinite breakwater considering diffraction. Wave forces of monochromatic and random waves on a vertical structure are studied considering diffractions in front and lee side of the breakwater for non-breaking wave condition. We selected width of breakwater are 0 for reference condition. In monochromatic wave case, relative wave force becomes 0 on the head of the breakwater by acting incident wave force and diffracting wave force simultaneously and oscillating patterns of relative wave force occurs based on 1.0 as distance from the head increases. Relative wave force of monochromatic waves decreases as incident wave angle increases. Relative wave force of random waves is defined by using ratio of root mean square and wave force spectrum in this study. The case considering random phase of each wave components are compared to the case which don't consider random phase and both results are almost similar. Relative wave force of random waves is also 0 near the head of the breakwater likewise monochromatic wave. Oscillating pattern of relative wave force of random waves becomes relatively weaker for composition of each wave components as distance from the head increases.

• Progress in Superconductivity and Cryogenics
• /
• v.21 no.1
• /
• pp.18-24
• /
• 2019

This study was carried out to investigate the effect of milling of boron (B), which is one of raw materials of $MgB_2$, on the critical current density ($J_c$) of $MgB_2$. B powder used in this study is semi-amorphous B (Pavezyum, Turkey, 97% purity, 1 micron). The size of B powder was reduced by planetary milling using $ZrO_2$ balls (a diameter of 2 mm). The B powder and balls with a ratio of 1:20 were charged in a ceramic jar and then the jar was filled with toluene. The milling time was varied from 0 to 8 h. The milled B powders were mixed with Mg powder in the composition of (Mg+2B), and the powder mixtures were uniaxially pressed at 3 tons. The powder compacts were heat-treated at $700^{\circ}C$ for 1 h in flowing argon gas. Powder X-ray diffraction and FWHM (Full width at half maximum) were used to analyze the phase formation and crystallinity of $MgB_2$. The superconducting transition temperature ($T_c$) and $J_c$ of $MgB_2$ were measured using a magnetic property measurement system (MPMS). It was found that $B_2O_3$ was formed by B milling and the subsequent drying process, and the volume fraction of $B_2O_3$ increased as milling time increased. The $T_c$ of $MgB_2$ decreased with increasing milling time, which was explained in terms of the decreased volume fraction of $MgB_2$, the line broadening of $MgB_2$ peaks and the formation of $B_2O_3$. The $J_c$ at 5 K increased with increasing milling time. The $J_c$ increase is more remarkable at the magnetic field higher than 3 T. The $J_c$ at 5 K and 4 T was the highest as $4.37{\times}10^4A/cm^2$ when milling time was 2 h. The $J_c$ at 20 K also increased with increasing milling time. However, The $J_c$ of the samples with the prolonged milling for 6 and 8 h were lower than that of the non-milled sample.

• Korean Journal of Agricultural Science
• /
• v.50 no.3
• /
• pp.383-394
• /
• 2023

In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m²), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10^-4, 2.01×10^-4, and 6.85×10^-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10^-2, 1.63, and 2.59×10^-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.37 no.2
• /
• pp.32-45
• /
• 2000

This paper presents the analytic derivation of the SINR, when a linear array antenna is accommodated into the cellular CDMA basestation receiver, in relation to the two major performance effecting factors in beamforming(BF) applications, i. e., the direction selectivity, which refers to the narrowness of the mainbeam width, and the direction-of-arrival(DOA) estimation accuracy. The analytically derived results are compared with the operation simulation of the receiver realized with the several BF algorithms and their agreements are confirmed, consequently verifying the correctness of the analysis and the operation simulation. In order to investigate separately the effects of the errors occurring in the direction estimation and in the interference suppression, which are the two major functional components of general BF algorithms, both the algorithms of steering BF and the minimum- variance- distortionless-response(MVDR) BF are applied to the analysis. A signal model to reflect the spatially scattering phenomenon of the RF waves entering into the .:nay antenna, which directly affects on the accuracy of the BF algorithm's direction estimation, is also suggested in this paper and applied to the analysis and the operation simulation. It is confirmed from the results that the enhancement of the direction selectivity of the away antenna is not desirable in view of both the implementation economy and the BF algorithm's robustness to the erroneous factors. Such a trade-off characteristics is significant in the sense that it can be capitalized to obtain an economic means of BF implementation that does not severely deteriorate its performance while ensuring the robustness to the erroneous effects, consequently manifesting the significance of the analysis results of this paper that can be used as a design reference in developing BF algorithms to the cellular CDMA system.

• Asian-Australasian Journal of Animal Sciences
• /
• v.17 no.2
• /
• pp.250-258
• /
• 2004

An experiment was conducted to examine the effect of a high environmental temperature on the performance, conformation, and carcass characteristics of pigs and the influence of diet. Thirty-six three-way crossed castrated male pigs with average initial body weight of 50.4 kg were used in the experiment. The pig were allocated to the following treatments: two environmental temperatures (20 and $30^{\circ}C$)${\times}$three dietary energy levels (2,980, 3,300 and 3,600 kcal/kg)${\times}$three protein levels (12.8, 15.2 and 17.2%). Daily weight gain was lighter (p<0.01) and feed: gain ratio lower (p<0.05) in pigs at $30^{\circ}C$ than for pigs at $20^{\circ}C$ The pigs at $30^{\circ}C$ were significantly taller with deeper bodies (p<0.05) and significantly longer (p<0.05) both vertically horizontally in the planum nasal when kept at $30^{\circ}C$. The width of body and the circumference of the neck were greater (p<0.05) at $20^{\circ}C$. The lean meat of the loin, middle section, ham, and hind section were significantly greater (p<0.05) in pigs kept at $30^{\circ}C$ and the belly was significantly heavier. The total unsaturated free fatty acids were significantly higher (p<0.05) in the body fat of pigs kept at $20^{\circ}C$ than in that of pigs at $30^{\circ}C$. The results indicated that when pigs are given very restricted same amounts of feed, they may need less energy to maintain their body temperature under moderately high environmental temperature ($30^{\circ}C$); consequently, their performance is better than that of pigs under optimum environmental temperature. The results showed very clearly that weight gain of pigs increased with increasing of dietary protein and energy content. The increasing of dietary protein content seemed more significant when content increasing to 17.2% compared with the 12.8 and 15.2% protein content treatments. The increasing of dietary energy content was more significant when content increasing to 3,600 compared with the other low energy content treatments.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.19 no.1
• /
• pp.17-24
• /
• 1983

The authors carried out an experiment to find the optomotor response of killifish, Orizias latipes(TEMMINCK et SCHLEGEL) and Yellowtail, Seriola quinqueradiata (TEMMINCK et SCHLEGEL) according to the colors of the netting pattern on the visual screen and the revolving velocities of the visual screen. The experimental water tank was made of 0.5 cm thick transparent acryl in the cylindrical shape (100R$\times$42H cm). The water level in the tank was maintained 30cm high from the bottom. The colors of the netting pattern (mesh size: 19.1cm, width of netting twine: 1.5cm, hanging ratio: 84%) on the three visual screens were black, red and green respectively. The revolving velocities of the visual screen were controlled by pulley, bevel gear and variable speed motor in three steps; slow (15.0cm/sec), middle (37.4cm/sec) and high (62.9cm/sec). The fish was put into the water tank before each experiment and released in it for 30 minutes in order to acclimatize itself to the tank. The visual screen was revolved for 4 minutes per each experiment, at first the fish was released for 1 minute, and then the behavior of the fish was observed for 3 minutes. In the course of clockwise and counter clockwise experiments, 10 minutes-pause was given for the rest. The behavior of the fish was observed by video system, and rounding number and swimming speed of the fish were analysed. The results obtained are as follows: (1) Optomotor response rate of Killifish and yellowtail were 95% and 94% respectively. (2) Response of the fish according to the colors of the netting pattern on the three visual screens was best in black, and second in red and third in green. (3) Response of the fish according to the revolving velocities of the visual screen was best in high speed, and second in middle speed and third in slow speed.

• Journal of the Korean Wood Science and Technology
• /
• v.4 no.1
• /
• pp.8-14
• /
• 1976

The capacity of wood to shrinkage is very important as the basis data for wood industry but there is no such data available as yet in Korea. So this article, as a study on forest biological, were made to determine the shrinkage properties of commercial hardwoods in Korea. The results of this study were as follows; 1) There are much difference of hardwoods shrinkage, generally values of heavy wood's shrinkage were larger than that of light wood's shrinkage. 2) The arithmetic; mean values of hardwoods shrinkage were respectively 9.03% on tangential, 4.09% on radial and 0.37% on longitudinal direction and its ratio of at : ar : al was appeared to be 10 : 5.5 : 0.4 3) Average shrinkage per 1% of moisture content was different due to the direction and species. 4) According to the increase of specific gravity the values of shrinkage increased. 5) It was recognized that the shrinkage of hardwoods had a tendency to decrease as increase of annual ring width of wood. 6) The shrinkage of tangential direction was in propertion to the shrinkage of radial direction.

• Korean Journal of Medicinal Crop Science
• /
• v.3 no.1
• /
• pp.35-39
• /
• 1995

Characteristics of Schizandra chinensis BAILLON collected were investigated the development of the new varieties and the results obtained are as follows: Flowering time of Schizandra chinensis varieties were varied from May 6 to 15. In petal base colors 70% were light pinked-colored, 23% were dark pinkcolored and 23% were white-colored respectively and number fruit set per node are 2 to 3 and 60% of plants were flower set and length of diameter of female flower longer than those of male flowers. Among 155 plants investigated, 125 plants showed below 40% of fruit setting and average fruit setting were 26%, 83% of plants were below 12mm, white 17% were above 12.1mm in fruit length, 100 dry fruit weight was 13.2g on average showing significant variation among plants. Average values of major characteristics of populations of collected varieties were 82.5 in number of fruit set, 68.3 in number of fruits 68.3mm in length of fruit set, 22.8mm in width of fruit set, 10.7mm in length of granule 103.1g in dry fruit weight per plants and ratio of dry fruit was 26.8% respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.121-121
• /
• 2010

ZnO is a promising material for the application of high efficiency light emitting diodes with short wavelength region for its large bandgap energy of 3.37 eV which is similar to GaN (3.39 eV) at room temperature. The large exciton binding energy of 60 meV in ZnO provide provides higher efficiency of emission for optoelectronic device applications. Several ZnO/ZnMgO multiple quantum well (MQW) structures have been grown on various substrates such as sapphire, GaN, Si, and so on. However, the achievement of high quality ZnO/ZnMgO MQW structures has been somehow limited by the use of lattice-mismatched substrates. Therefore, we propose the optical properties of ZnO/ZnMgO multiple quantum well (MQW) structures with different well widths grown on lattice-matched ZnO substrates by molecular beam epitaxy. Photoluminescence (PL) spectra show MQW emissions at 3.387 and 3.369 eV for the ZnO/ZnMgO MQW samples with well widths of 2 and 5 nm, respectively, due to the quantum confinement effect. Time-resolved PL results show an efficient photo-generated carrier transfer from the barrier to the MQWs, which leads to an increased intensity ratio of the well to barrier emissions for the ZnO/ZnMgO MQW sample with the wider width. From the power-dependent PL spectra, we observed no PL peak shift of MQW emission in both samples, indicating a negligible built-in electric field effect in the ZnO/$Zn_{0.9}Mg_{0.1}O$ MQWs grown on lattice-matched ZnO substrates.