• Korean Journal of Environmental Agriculture
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• v.20 no.2
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• pp.86-92
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• 2001

The current study was conducted to elucidate the optimum density of free-ranging ducks in a rice-duck farming system in terms of effects on duck behavior, and growth and yield of rice plants. Four paddy fields were used for this experiment, with 6, 9, 12 and 15 birds per plot, respectively. Ducklings at eight days of age were free ranged in experimental paddy plots (4.0 a each) on the 9th day after the transplantation of rice plants. Ducks were kept in the plot for seventy days, at which point rice plants reached the earing stage. Foraging, moving, working, resting, diving and pecking behaviors of the ducks were observed two times during the experimental period. Also, rice plant growth and yield according to the density of ducks per plot were examined. The foraging and moving behavior of free-ranging ducks in paddy fields for 12 hours during the daytime tended to be longer in the 12-bird plot, and working behavior was significantly (P<0.01) longer in the 12-bird plot than in the other three plots. The resting behavior was significantly (P<0.01) higher in the 9- and 15-bird plots than in the 12-bird plot. The frequency of moving behavior for 6 hours during the daytime in the 15-bird plot tended to be lower than that in the other three plots, but this difference was not significant. The amount of diving and pecking behavior in the 9-bird plot was significantly (P<0.05) higher than that in the other three plots, and the number of hills pecked tended to be higher with increasing of duck density. From thirty days after ducks were introduced to the paddy fields, the length of rice plants tended to be significantly (P<0.05) shorter in high free-ranging density plots as compared to low free-ranging density plots. The number of tillers per hill was not affected by the free-ranging density. The culm length of rice plants was significantly (P<0.05) shorter in the 12- and 15-bird plots than in the other two plots, however, the duck free-ranging density did not affect panicle length. The dry weight of the root of rice plants was increased with high free-ranging density, but there was no such increase in the top parts of the rice plants. The percent of rice plants badly damaged by free-ranging density tended to be lower in the order of 12-, 9-, 6- and 15-bird plots. The number of ears, ripening grains and crop yield per hill of rice plants in the 12-bird plot were significantly (P<0.05) higher than those of the other three plots. Therefore, the yield of each rice plant per 10 a was significantly increased in the 12-bird plot.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.157-167
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• 2010

Density is the most important congestion indicator among the three fundamental flow variables, flow, speed and density. Measuring density in the field has two different ways, direct and indirect. Taking photos with wide views is one of direct ways, which is not widely used because of its cost and lacking of proper positions. Another direct density measuring method using two point detectors has been introduced with the concept of instantaneous density, average density and measurement interval. The relationship between accuracy and measurement interval has been investigated using the SIMULATION data produced by Paramics Application Programming Interface function. We analyze the affect of segment density accuracy by sensing gap each road condition such as sensing segment length, lane and LOS after gathering data by Paramics Application Programming Interface.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.271-271
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• 2012

Many studies have been investigated on high density plasma source (Electron Cyclotron Resonance, Inductively Coupled Plasma, Helicon plasma) for large area source after It is announced that productivity of plasma process depends on plasma density. In this presentation, we will propose the new concept of the multiple source, which consists of a parallel connection of ICP sources and helicon plasma sources. For plasma uniformity, equivalent power (especially, equivalent current in ICP & Helicon) should distribute on each source. We design power feeding line as coaxial transmission line with same length of ground line in each source for equivalent power distribution. And we confirm the equivalent power distribution with simulation and experimental result. Based on basic study, we develop the plasma source for oxidation in semiconductor process. we will discuss the relationship between the processing parameters (With or WithOut magnet, operating pressure, input power ). In ICP, plasma density uniformity is uniform. In ICP with magnet (or Helicon) plasma density is not uniform. As a result, new design (magnet arrangement and gas distributor and etc..) are needed for uniform plasma density in ICP with magnet and Helicon.

• Plant Resources
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• v.3 no.3
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• pp.194-199
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• 2000

The result of this experiment which are conducted, to improve the cultivation technology of Alisma plantago, to increase its quantity and to contribute for stable production with Yongiun local group by examining the optimal planting density and transplanting period of double cropping of Alisma plantago in the southern region. The characters of plant height, leaf width and length tend to be reduced as the seeding period is later by the order of the 10th, 20th and 30th of July. The period required for flowering is reduced as the transplanting period is later and dense planting is applied. Plant height, the number of leaves and yield of dry root have much quantity at the dense planting density of 20$\times$ 15cm as they are transplanted later in the 30th of August or the 10th of September, but they are rather less in sparse planting density of 20$\times$25cm or 20$\times$35cm.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.435-437
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• 1995

It is important to understand tile behaviours of tile high pressure DC glow discharge with a micro gap inside a pixel of the plasmas display panel. We prepared a narrow gap discharge system and have measured electron temperature and density by means of double probe methods in high pressure which was between 100torr and 200torr. And the electrode gap was 7mm. When the pressure varied from 100torr to 200torr, the negative glow was created at a distance less than 1mm from the cathode. And the length of the faraday dark space decreased from 8mm to 5mm. Hence probe measurements was mainly, performed in the region of the Faraday dark space. The dependence of electron temperature and density on the pressure and current density was same with that of the general flow discharge, i.e. as the pressure increased the electron temperature decreased and the density increased. But the spatial electron density distribution in the Faraday dark space was highly distorted because of the effect of high pressure.

• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.319-328
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• 2014

Dorang - the Korean term for headwater streams - occupy a large portion of the total stream length in a basin, and contribute significantly towards the quantitative and qualitative characteristics, and the ecosystem, of the main river. The Ministry of Environment of South Korea has supported the investigation of the status of Dorang in the nation's four major basins, since 2007. Without a widely accepted academic or legal definition of Dorang, however, there are limits to understand the distribution of Dorang at the national scale and to systematically compile a Dorang database. This paper, through a review of the stream classification system and Korean legal system delineating streams, defines Dorang as 1st and 2nd order streams according to the Strahler ordering method, in a 1:25,000 geographical scale. Analysis of the Geum River basin, with this definition, reveals that the total length of Dorang is 20,622.4 km (73.6% of total stream length), and the number of Dorang catchments is 23,639 (71.3% of the basin area). Further analysis of the geomorphological characteristics of Dorang catchments shows that the average total stream length is 1.1 km, average catchment length is 1.2 km, average drainage area is $0.4km^2$, and average drainage density is 3.08/km.

• Current Optics and Photonics
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• v.7 no.1
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• pp.47-53
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• 2023

We propose a centralized passive-optical-network monitoring scheme using the resonance-spectrum properties of a Fabry-Perot cavity based on fiber Bragg gratings. Each cavity consists of two identical uniform fiber Bragg gratings and a varying cavity length or grating length, which can produce a unique single-mode resonance spectrum for the drop-fiber link. The output spectral properties of each cavity can be easily adjusted by the cavity length or the grating length. The resonance spectrum for each cavity is calculated by the transfer-matrix method. To obtain the peak wavelength of the resonance spectrum more accurately, the effective cavity length is introduced. Each drop fiber with a specific resonance spectrum distinguishes between the peak wavelength or linewidth. We also investigate parameters such as reflectivity and bandwidth, which determine the basic performance of the fiber Bragg grating used, and thus the output-spectrum properties of the Fabry-Perot cavity. The feasibility of the proposed scheme is verified using the Optisystem software for a simplified 1 × 8 passive optical network. The proposed scheme provides a simple, effective solution for passive-optical-network monitoring, especially for a high-density network with small end-user distance difference.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.406-416
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• 1994

In this study the reactor design procedure and method of solid-solid-gas chemical heat pump system using STELF technology were investigated. For manufacturing IMPEX block which is the kernel of reactor, proper salt pair should be selected, and equilibrium temperature drop and COP should be examined for selected salt pair. Moreover, apparent density, residual porosity, and graphite ratio should be calculated to give minimum block volume and mass, and maximum energy density without causing heat and mass transfer problems. Since heat exchange area can be changed with operating condition, reactor diameter, length, and stainless steel thickness should be decided for desired specifications. These procedure and method were applied to the case study of 6kW cold production and 8 hours storage capacity reactor.

• Journal of The Korean Society of Grassland and Forage Science
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• v.9 no.2
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• pp.108-112
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• 1989

To determine optimal plant density of forage rape in southern areas of Korea, Velox, the highest yielding variety among seventeen introduced varieties of forage rape, was grown under five different plant densities. The results obtained are summarized as follows: 1. Yield components such as stem diameter, number of main stem,leaves, number of branches and number of branch leaves and fresh yield were highest at the plots with 50cm row spacing and 30cm plant spacing. 2. Dry matter yield, content of crude protein, IVDMD and digestible dry matter yield were highest at the plots of broadcasting. 3. Since plants under high density were high in plant length and small in stem diameter, contents of crude fiber such as NDF, ADF, cellulose and lignin were lowest at the plots of broadcasting.

• Geomechanics and Engineering
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• v.11 no.3
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• pp.385-400
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• 2016

Bearing capacity of open-ended piles depends largely on inner frictional resistance, which is influenced by the degree of soil plugging. While a fully-plugged open-ended pile produces a bearing capacity similar to a closed-ended pile, fully coring (or unplugged) pile produces a much smaller bearing capacity. In general, open-ended piles are driven under partially-plugged mode. The formation of soil plug may depend on many factors, including wall thickness at the pile tip (or inner pile diameter), sleeve height of the thickened wall at the pile tip and relative density. In this paper, we studied the effects of wall thickness at the pile base and sleeve height of the thickened wall at the pile tip on bearing capacity using laboratory model tests. The tests were conducted on a medium dense sandy ground. The model piles with different tip thicknesses and sleeve heights of thickened wall at the pile tip were tested. The results were also discussed using the incremental filling ratio and plug length ratio, which are generally used to describe the degree of soil plugging. The results showed that the bearing capacity increases with tip thickness. The bearing capacity of piles of smaller sleeve length (e.g., ${\leq}1D$; D is pile outer diameter) was found to be dependent on the sleeve length, while it is independent on the sleeve length of greater than a 1D length. We also found that the soil plug height is dependent on wall thickness at the pile base. The results on the incremental filling ratio revealed that the thinner walled piles produce higher degree of soil plugging at greater penetration depths. The results also revealed that the soil plug height is dependent on sleeve length of up to 2D length and independent beyond a 2D length. The piles of a smaller sleeve length (e.g., ${\leq}1D$) produce higher degree of soil plugging at shallow penetration depths while the piles of a larger sleeve length (e.g., ${\geq}2D$) produce higher degree of soil plugging at greater penetration depths.