• Journal of Biosystems Engineering
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• v.23 no.4
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• pp.319-326
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• 1998

A herbicide applicator attached to a rice transplanter was developed to perform herbicide application and transplanting simultaneously. The prototype machine was composed of herbicide tank, discharge device, spinner, scattering plate and power drive. The application rate of the machine could be adjusted from 10 to 30 kg/㏊ and the application swath was 1.8m. According to the field test, application uniformity showed the range of 13.6~43.9％ in terms of CV(coefficient of variation) depending on the spinner speed, application height and shape of diffuser. The best uniformity could be achieved with the spinner speed of 30.8m/s and application height of 20cm. Field efficiency of the prototype was 4.7hr/㏊. Transplanting machine has field efficiency of 4.6hr/㏊ in Korea. By attaching the herbicide applicator, field efficiency became lowed only by 0.1hr/㏊, which was counted for filling time of herbicide. Simultaneous operation of transplanting and herbicide application had a of labor saying. The weed control efficacy was measured to be 96% in field when AC140 + Stomp and Londax + YRC was applied at the 65th day after transplanting. Nonanmae was treated by manual application to be compared to.

• Tunnel and Underground Space
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• v.13 no.2
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• pp.117-124
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• 2003

The fracture processes under static tensile loading were simulated using a proposed numerical simulation method, based on finite element method and fracture mechanism, and analyzed to verify an influence of rock inhomogeneity on static tensile strength. Static tensile strengths for the specimen models with different spatial microscopic tensile strength when m=5 and m=50 were estimated. These analyses revealed that the static tensile strength becomes closer to the mean microscopic tensile strength at a higher uniformity coefficient and the scatter of the strength data decreases in increasing the uniformity coefficients. Therefore, it could be concluded that rock inhomogeneity has an effect on static tensile strength.

• Plant Biotechnology Reports
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• v.2 no.1
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• pp.33-39
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• 2008

In this paper, we would like to show unexpected morphogenic potential of cell suspensions derived from seedling explants of Gentiana kurroo (Royle). Suspension cultures were established with the use of embryogenic callus derived from seedling explants (root, hypocotyl and cotyledons). Proembryogenic mass proliferated in liquid MS medium supplemented with $0.5mg\;l^{-1}$ 2,4-D and $1.0mg\;l^{-1}$ Kin. The highest growth coefficient was achieved for root derived cell suspensions. The microscopic analysis showed differences in aggregate structure depending on their size. To assess the embryogenic capability of the particular culture, 100 mg of cell aggregates was implanted on MS agar medium supplemented with Kin ($0.0-2.0mg\;l^{-1}$), $GA_3$ ($0.0-2.0mg\;l^{-1}$) and AS ($80.0mg\;l^{-1}$). The highest number of somatic embryos was obtained for cotyledon-derived cell suspension on $GA_3$-free medium, but the best morphological quality of embryos was observed in the presence of $0.5-1.0mg\;l^{-1}$ Kin, $0.5mg\;l^{-1}$ $GA_3$ and $80.0mg\;l^{-1}$ AS. The morphogenic competence of cultures also depended on the size of the aggregate fraction and was lower when size of aggregates decreased. Flow cytometry analysis reveled luck of uniformity of regenerants derived from hypocotyl suspension and 100% of uniformity for cotyledon suspension.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.420-425
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• 2018

Purpose: Chemical fertilizers contribute to agricultural productivity. Annually, 450,000 tons of chemical fertilizers are used in Korea, which is 268 kg per hectare (MAFRA, 2016). However, excessive use causes problems such as environmental pollution and soil acidification. This study proposes use conditions for a fertilizer distributor that can reduce excessive fertilization by analyzing distribution patterns. Methods: This study analyzed fertilizer application uniformity according to the number of blades on a centrifugal fertilizer distributor (three or four blades), orifice gate open ratio (50 or 100%), and blade rotation speed (400, 500, or 600 rpm). Results: When using four blades, the coefficient of variation (CV) was lower than when using three by 11-13% points, and the CV using the 50% open ratio was 10-30% points lower than using the 100% open ratio. The CV at 500 rpm blade rotating speed was 9-12% points lower than that for 400 and 600 rpm. Conclusions: The CV with four blades, 50% orifice gate open ratio, and 500 rpm of blade rotating speed was 18.4%, which provided the most uniform fertilization.

• Journal of the Semiconductor & Display Technology
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• v.21 no.4
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• pp.39-44
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• 2022

Using a CFD (computational fluid dynamics) simulation tool, we have offered a design guideline of a slot-die head having a simple T-shaped cavity through an analysis of the fluid dynamics in terms of cavity pressure and outlet velocity, which affect the uniformity of coated thin films. We have visualized the fluid flow with a transparent slot-die head where poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is injected. We have shown that the fluid dynamics inside the slot-die head depends sensitively on the cavity depth, cavity length, land length, and channel gap (i.e., shim thickness). Of those, the channel gap is the most critical parameter that determines the uniformity of the pressure and velocity distributions. A pressure drop inside the cavity is shown to be reduced with decreasing shim thickness. To quantify it, we have also calculated the coefficient of variation (CV). In accordance with Hagen-Poiseuille's laws and electron-hydraulic analogy, the CV value is decreased with increasing cavity depth, cavity length, and land length.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.280-287
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• 2001

The present study investigates convective heat/mass transfer and flow characteristics inside the rib-roughened cooling passage of the gas turbine blades. A square duct with rectangular ribs is used and $\wedge-$ and V-shape ribs with $60^{\circ}$ attack angle are installed on the test plate surfaces. Naphthalene sublimation technique is employed to determine the detailed local heat transfer coefficients using the heat and mass transfer analogy. The ribs disturb the main flow resulting in the recirculation and secondary flows near the ribbed wall and the vortices near the side-wall. The local heat transfer and the secondary flow in the duct are changed largely according to the rib orientation. A square duct with $\wedge$ and V-shape ribs has two pairs of secondary flow because of the rib arrangement. So, the duct has complex heat/mass transfer distribution. The average heat/mass transfer coefficient and pressure drop of $\wedge-$ and V-shape ribs are higher than those with $90^{\circ}$ and $60^{\circ}$ attack angles. The average heat/mass transfer coefficient on the $\wedge-shape$ ribs is higher than that on the V-shape ribs. Also, the uniformity of heat/mass transfer coefficient on discrete ribs is higher than that on continuous rib.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.397-404
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• 2012

In this research, a numerical study was carried out on the mixing and flow characteristics of a vane-type static mixer for the reduction of $NO_x$ in the SCR systems from the diesel exhaust environments. The mixer was located at a distance of 57 times the pipe diameter away from the inlet. The analyses were performed by changing various parameters such as vane angles, blockage ratio, and location of the vane. Flow characteristics through the mixer were characterized by the uniformity index, swirl number, and pressure drop. The results show that uniformity index, pressure coefficient and swirl number are substantially influenced by the vane angle, blockage ratio and position of the vane of the mixer. In particular, the swirl number was increased when the vane was located near the pipe wall, or the vane angle was increased or scale was extended.

• Tunnel and Underground Space
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• v.13 no.3
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• pp.180-186
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• 2003

The fracture processes under dynamic loading in tension were simulated using a proposed numerical approach and analyzed to determine dynamic tensile strength. The dynamic tensile strength and the scatter of the strength data decreased with increasing uniformity coefficients. The differences of static and dynamic tensile strength were due to the stress concentrations and redistribution mechanisms in the rock specimen. Although there were different mechanisms for the static and dynamic fracture processes, the static and dynamic tensile strengths were close to the mean microscopic tensile strength at high values of the uniformity coefficient. This paper shows that the rock inhomogeneity has an effect on dynamic tensile strength and is a factor that contributes to the different specimen strengths under dynamic and static loading conditions.

• KIEAE Journal
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• v.12 no.6
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• pp.23-28
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• 2012

Pressure distribution in the water supply system of an apartment complex consisting of 12 buildings and 635 units in total have been investigated numerically. The complex incorporates two zone booster pump system, and around a half of units have pressure reducing valves (PRVs) in them. Calculated hydrostatic pressure without the water flow were compared with their designed and measured counterparts, and they agreed quite well with each other. Then, the pressure and volumetric water flow rate at all units were analyzed, indicating that there are noticeable differences in pressure and flow rate in one unit to another, although the aforementioned minimization technologies of pressure deviation were employed. In order to further reduce the difference in the water flow rate, it is suggested that all the units in the complex have PRVs installed in their water supply system. The effect of setting pressure of the PRVs on the non-uniformity of the flow in each unit and on the reduction of total water supply for the apartment complex have been studied. With the same PRV setting pressure of 3.952 bar (or the gauge pressure of $3.0kg_f/cm^2$), it has been estimated that the suggested system improves the non-uniformity (the coefficient of variation) of the flow rate of apartment complex over the current system, from 8.02% to 6.66%, and reduces the total water supply, from $0.02804m^3/s$ to $0.02766m^3/s$.

• Journal of Korean Society of Forest Science
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• v.84 no.2
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• pp.166-177
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• 1995

This study was carried out to discuss how soils in the area planned for a forest road construction can be mechanically tested and practically applied. For this, 16 soil test samples from 8 plots(2 samples per plot) were used. The major tests are focused on unit weight before and after cut, water content, liquid and plastic limits, sieve and hydrometer analysis etc. The total unit weight(${\rho}_t$) before and after cut are $1.69g/cm^3$ and $1.19g/cm^3$, respectively. Their water contents are 21.0% and 20.5%. The coefficient of uniformity U and coefficient of curvature C obtained from sieve and hydrometer analysis are 125 and 0.42, which mean generally not well graded. On the soil classification by USCS, SM(silty sand or silt-sand mixed soil)is a Key soil, but it seems to be not good for fill material. From the standard proctor test are resulted $1.40{\pm}0.065g/cm^3$ for the unit weight(${\rho}$) in the nature and $1.88{\pm}0.049g/cm^3$ for the optimum proctor unit weight(${\rho}pr$) each. With this to say, it is necessary more powerful compaction work at earth filling, with which this soil reachs enough the ${\rho}pr$, and more earth.