• Journal of The Korean Society of Grassland and Forage Science
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• v.17 no.4
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• pp.407-414
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• 1997

In this study, the optimum cutting 6equency and level of mineral nitrogen fertilization were investigated for the production of Reed canarygrass in uncultivated rice paddy. The results are summarized as follows; 1. Higher relative dry matter yields were recorded in 2nd cut of plots with 3 and 5 cutting frequencies, and 3rd cut of plot with 4 cutting kquency, respectively. 2. With no nitrogen fertilization, mean dry matter yields per year were 6.2~7.6 tonsha and the highest yield appeared in plot with 4 cutting 6equency. 3. The increased fertilization of mineral nitrogen resulted in the increased dry matter yield. Significantly higher dry matter yields than that of no nitrogen fertilization were recorded in fertilization of 90 kg nitrogen per year in 3 cutting fequency, 240 kg in 4 cutting frequency and 150 kg in 5 cutting 6equency respectively. 4. Efficiency of dry matter production with nitrogen fertilization(kg DMkg N) was higher in 30kg Nhalcut in 3 and 5 cutting eequency, 60kg Nhalcut in 4 cutting 6equency respectively. In each cutting kequency, the higher efficiency of dry matter production appeared in 1st cut in 3 cutting kequency, and 2nd cut in 4 and 5 cutting 6equency respectively. 5. Economic N level(kg/ha) was 179.5~242.3kg/ha in 3 cutting 6equency, and 189.6-241.6kg/ha and 167.0 ~253.2kg/ha in 4 and 5 cutting 6equency respectively, and marginal dry matter yields were 11.4~ 12.3 tons/ ha, 11.2 ~ 11.8 tons/ha and 8.3 ~9.1 tons/ha in 3, 4 and 5 cutting 6equency respectively. 6. The limiting N fertilization level to the highest dry matter were estimated to be 569.9kg/ha, 492.4kg/ha and 654.lkg/ha in 3, 4 and 5 cutting kequency respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.5
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• pp.295-299
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• 2018

In this work, we conducted a study on cell strings of high efficiency and high power solar cell modules via simulation. In contrast to the conventional module manufacturing method, the simulation was performed by connecting cutting cells divided into four parts from 6-in size using the electrically conductive adhesive (ECA). The resistance of the ECA added in series connection was extracted using an experimental method. This resistance was found to be $3m{\Omega}$. Based on this simulation, we verified the change in efficiency of the string as a function of the number of cutting cell connections. Consequently, the cutting cell efficiency of the first 20.08% was significantly increased to 20.63% until the fifth connection; however, for further connections, it was confirmed that the efficiency was saturated to 20.8%. Connecting cutting cells using ECA improves the efficiency of the string; therefore, it is expected that it will be possible to fabricate modules with high efficiency and high power.

• Applied Science and Convergence Technology
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• v.23 no.5
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• pp.221-239
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• 2014

The global demand for energy has been increasing since past decades. Various technologies have been working to find a suitable alternative for the generation of sustainable energy. Photovoltaic technologies for solar energy conversion represent one of the significant routes for the green and renewable energy production. Despite of remarkable improvement in solar cell technologies, the generation of power is still suffering with lower energy conversion efficiency, high production cost, etc. The major problem in improving the PV efficiency is spectral mismatch between the incident solar spectrum and bandgap of a semiconductor material used in solar cell. Luminescent materials such as rare-earth doped phosphor materials having the quantum efficiency higher than unity can be helpful for photovoltaic applications. Quantum cutting phosphors are the most suitable candidates for the generation of two or more low-energy photons for the absorption of every incident high-energy photons. The phosphors which are capable of converting UV photon to visible and near-IR (NIR) photon are studied primarily for photovoltaic applications. In this review, we will survey various near IR quantum cutting phosphors with respective to their synthesis method, energy transfer mechanism, nature of activator, sensitizer and dopant materials incorporation and energy conversion efficiency considering their applications in photovoltaics.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1830-1837
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• 2023

The thermal cutting of contaminated or activated metals during decommissioning nuclear power plants inevitably results in the release of radioactive aerosol. Since radioactive aerosols are pernicious particles that contribute to the internal dose of workers, air conditioning units with a HEPA filter are used to remove radioactive aerosols. However, a HEPA filter cannot be used permanently. This study evaluates the efficiency and lifetime of filters in actual metal cutting condition using a plasma arc cutter and a high-resolution aerosol detector. The number concentration and size distribution of aerosols from 6 nm to 10 ㎛ were measured on both the upstream and downstream sides of the filter. The total aerosol removal efficiency of HEPA filter satisfies the standard of removing at least 99.97% of 0.3 ㎛ airborne particles, even if the pressure drop increases due to dust feeding load. The pressure drop and particle size removal efficiency at 0.3 ㎛ of the HEPA filter were found to increase with repeated cutting experiments. By contrast, the efficiency of used HEPA filter reduced in removing nano-sized aerosols by up to 79.26%. Altogether, these results can be used to determine the performance guidance and replacement frequency of HEPA filters used in nuclear power plants.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.04a
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• pp.585-591
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• 1997

The purpose of this experiment is to verify and efficiency of repair for cutting area. The result of this experiment is the fact thar the strength of compression and bending in declined by width and depth of cutting area. Deterioration of strength depends on depth to be repair area the strength of compression decreased up 50% when the repairing area is the fact that it is emerged by the increased of depth size rather than width size.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.2
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• pp.4096-4104
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• 1976

This experiment was carried out to investigate the efficient turning method which will be able to use every cutting methods, to calculate the width of the center field which must transpose from rotary cutting method to return cutting method, to investigate the effects of L/W and unit field on the operation efficiency. The results are summarized as follows: 1. In case of cutting in the outer field, the efficient turning method is the "$\alpha$" type turning method (half U-shaped turning method) at the first rotation, is the "$\beta$" type turning method (T-shaped turning method) at the second to fourth rotation. 2. In case of cutting in the inner field, the efficient turning method which takes the least turning time is the "a" type turning method ($\Delta$-shaped turning method). 3. The width of the center field (W') changes by the length-width ratio (L/W) and width (W), W' is 9.0m in case that L/W is 2.5 and W is 30m. 4. The larger L/W and area of unit field (A) become, the more operation efficiency (E) increases, and the limits that E is affected signicantly by L/W is 2 to 3.5 and A is within 5,000$m^2$. within 5,000$m^2$.

• Journal of the Korea Organic Resources Recycling Association
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• v.4 no.1
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• pp.33-42
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• 1996

In this study, the adequate cutting frequency and level of cattle slurry nitrogen application were investigated for the production of Reed canarygrass. Higher relative dry matter yields were recorded in 2nd cut in 3 cutting frequency, 3rd cut in 4 cutting frequency and 4th cut in 5 cutting frequency respectively. With no fertilization, mean dry matter yields per year were 6.4~7.5 tons/ha and the highest yield appeared in 3 cutting frequency. The increased application of cattle slurry nitrogen resulted in the increased dry matter yield. Significantly higher dry matter yields than that of no fertilization were recorded in fertilization of 180 kg cattle slurry-N per year in 3 cutting frequency, 120 kg in 4 cutting frequency and 300 kg in 5 cutting frequency respectively. Efficiency of dry matter production with cattle slurry nitrogen application (kg DM/kg N) was higher in 120 kg N, 30 kg N and 90 kg N/ha/cut in 3, 4 and 5 cutting frequency respectively. In each cutting frequency, the higher efficiency of dry matter production appeared in 1st cut in 3 cutting frequency, and 2nd cut in 4 and 5 cutting frequency respectively. Economic slurry N level (kg/ha) was 462.7~525.3 kg/ha in 3 cutting frequency, and 353.1~423.2 kg/ha and 380.1~424.4 kg/ha in 4 and 5 cutting frequency respectively.

• Tunnel and Underground Space
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• v.21 no.6
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• pp.508-517
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• 2011

The linear cutting test is the most reliable and accurate approach to measuring cutting forces and cutting efficiency using full-size disc cutter in various rock types. The result of linear cutting tests can be used to obtain the key parameters of cutter-head design (i.e. optimum cutter spacing, cutter forces). In Korea, LCM (Linear Cutting Machine) tests have been performed for typical Korean rock types, but these studies focused on the isotropic rocktypes. For prediction of TBM (Tunnel Boring Machine) performances in complex geological conditions including a bedded and schistose rockmass, it is important to consider the effects of anisotropy of rockmass on cutting performances and cutting efficiency. This study discusses a series of LCM tests that were performed for Asan Gneiss having two types of anisotropy angles to assess the effect of the anisotropy angle on rock-cutting performances of TBM. The result shows that the rock-cutting performances and optimum cutting conditions are affected by anisotropy angle and the effect of anisotropy on rock strength should be considered in a prediction of the cutting performances and efficiency of TBM.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1555-1562
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• 1995

This study represents the non-dimensional cutting force model. With the non-dimensional cutting force model it is possible to estimate efficiently the maximum cutting force during one revolution of cutter. Using the non-dimensional cutting force model, the feed rate and spindle speed are adjusted so as to satisfy the maximum cutting force and maximum machining error. To verify the accuracy and efficiency of the non-dimensional cutting force model, a series of experiments were conducted, and experimental results proved and verified the non-dimensional cutting force model. The NC toolpath verification system developed in this paper uses the non-dimensional cutting force model, so that it is effective for calculating the cutting force and adjusting the cutting conditions.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.419-424
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• 2004

In order to increase the efficiency of the sawdust machine, the helical type drums with an oblique cutting condition (3D) were developed. The preexisting drums have an orthogonal cutting condition (2D) considering of a saw cutter and a wood cutting pattern. Unfortunately, the disadvantages of this type drum are the big cutting resistance, the high cost of a cutting power and the extreme occurrence of a vibration. To improve this shortcoming, the helical type drum with an oblique cutting condition was developed. Therefore, this type drum decreased the vibration and the cutting resistance of the sawdust machine, and also improved the productivity of 30% or more and the porosity of the sawdust.