• KIEAE Journal
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• v.8 no.1
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• pp.81-86
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• 2008

Due to the recent environmental problems, lots of studies on the solutions to reduce the environmental pollutions are on the way. In the field of construction, concrete that we are currently consuming approximately 1 ton each year is the most common and cheap building material. We must cut down on this preoccupied use of this material and develop an alternative material as recommended by the late environmental standards. In this regard, this study propose the 'yellow soil' as the main substance that composes the final state, 'yellow soil concrete'. This study also aims to analyze the physical and chemical performances of this concrete mixed with the yellow soil by comparing it with the cement and assesses the possibility of its application to the cement. The results of the experiment shows that, assuming the solidity of the cement concrete to be around $210kg/cm^2$ (20.58MPa), the solidity of the yellow soil combined material may be around 45%~55% in terms of the range of W/B use, 200 to 400 in the per unit fission amount and less than 2% in the addition proportion of admixing agents. But the scope of the optimal concoction amount of the yellow soil concrete should better be limited as following. 40% to 50% in W/B, 300 to 400 in the per unit fission amount and less than 2% in the addition of admixing agents.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.227-232
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• 2000

A natural air in-bin grain dryer with a grain circulator was developed for on farm use. Natural air drying test for rough rice was carried out to evaluate drying rate, uniformity of moisture content distribution in grain bed and energy consumption. It took 10 days to dry 8 ton of paddy rice from 21.9%(w.b) of moisture contents to 16.7%(w.b), by prototype dryer and the average drying rate was 0.52%/day. The uniformity of moisture content after drying was superior to a conventional natural air dryer in which grains were not mixed during drying periods. The dryer performance evaluation index was 738.3kJ/(kg.water), which was more effective than that of grain circulation type hot air dryer(3,500∼5,000 kJ/kg.water)

• Journal of Korean Society for Atmospheric Environment
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• v.7 no.3
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• pp.203-207
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• 1991

Scientists in the National Institute of Environmental Research had carried out air and precipitation sampling. According to the data analysed, the acidity (pH) measured was in the range of 3.7 $\sim$ 5.5. Detailed analysis indicated that observed acid rain was associated with westerlies generally coming out of the mainland of China and with a cyclone formed therein. Emission of air pollution from Korea and Japan also appeared to contribute in the observed high acidity in some cases. The one of chief reasons for the occurrence of acid rain in the west coast of Korea was due to the increase in the total emission of air pollution in China. In 1990, China was the world's top producer of coal amounting in 1.05 B tons with an annual increase of 10%, and the produced 100 M tons of crude oil. $SO_2$ emission from all energy usage in China was estimated at 25 $\sim$ 50 M ton per year.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.12
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• pp.109-119
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• 1995

A driveline incorporating universal joints when driving through an angle can excite various components in a vehicle with second order excitation of torsional and bending vibrations, being transmitted either audibly(noise), or physically(vibration). For a certain range of vehicle dpeed noises can be radiated from the cab wall, in which resonances occur by the excitations transmitted from the driveline as a vibration source. In this paper, the excitation mechanism of cab noises is studied especially for the vehicle speed range of 65 .approx. 75 km/h through the simulation for torsional vibrations of the driveline and for bending vibrations of the cab of an 11 Ton grade Cargo Truck, and verified additionally by vibration and noise measurements. As a result, it is found that the uncomfortable noises in the cab are caused mainly by the abrupt increase of the joint angle of driveline near the axle differential resulted from the excessive clearance alignment of the leaf spring gate.

• Bulletin of the Korean Mathematical Society
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• v.57 no.3
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• pp.691-707
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• 2020

In this paper, we introduce and study the notions of weakly ⊕-supplemented modules, weakly D2 modules and weakly D2-covers. A right R-module M is called weakly ⊕-supplemented if every non-small submodule of M has a supplement that is not essential in M, and module M_R is called weakly D2 if it satisfies the condition: for every s ∈ S and s ≠ 0, if there exists n ∈ ℕ such that sⁿ ≠ 0 and Im(sⁿ) is a direct summand of M, then Ker(sⁿ) is a direct summand of M. The class of weakly ⊕-supplemented-modules and weakly D2 modules contains ⊕-supplemented modules and D2 modules, respectively, and they are equivalent in case M is uniform, and projective, respectively.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.10a
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• pp.65-67
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• 2008

Kyoto Protocol against global warming came into effect in Feb 2005. This paper presents a calculation $CO_2$ emission of D power plant for combusting LNG and heavy oil using the a, b, c coefficients obtained by the performance test. The authors also calculate the breakeven point of the fuel transfer from LNG to Oil considering recent $CO_2$ emission cost.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.84-90
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• 2010

Korean army currently considers the development of the new generation MLRS(Multiple Launcher Rocket System) as a new alternative, which responses on the renovation of the artillery and future battlefield environment. This study suggests that it presents cost-effectiveness of MLRS based on the Analytic Hierarchy Process and Parametric Estimating(PRICE H). According to this study, the cost-effectiveness of new generation MLRS presented that alternative A is 2.30 times and alternative B is 1.70 times, which are better than currently operating M270A1. Therefore, The best acquisition is alternative A that launcher is carried on currently operating 10ton standard truck but final acquisition alternative should be politically decided to consider viability of operator, performance and the latest of equipment.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.11 no.1
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• pp.41-46
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• 2005

For both economic and ecological reasons corrugated box manufacturers are seeking to produce acceptably strong boxes while using more recycled paper. This study was to develop hydrophilic coating agents in order to improve overall physical properties of recycled corrugated fiberboard liners. Two coating agents were developed and applied to 'S' corrugating medium. The results showed that compression strength of new liners, named 'S-A' and 'S-B', were increased significantly both standard humidity and high humidity environment and it was as much as 'SK' liner. New developed liners were also economically advantageous since new liners were estimated about one hundred fifty dollars per ton cheaper than SK liner. The study indicated that further work is needed on the coating technology and machine development.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.263-266
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• 2008

We apply a closed die forging technology to a large crankshaft of which forging weight amounts to 850kg. 40ton counter-blow hammer forging machine is used. The forging process is optimized to reduce the forming load using finite element simulation. AFDEX 3D is used for forging simulation. The experiment is compared with finite element prediction and a good agreement is observed. The successful development of a large crankshaft by the closed die forging technology will contribute to opening a new area of closed-die forging application and to enhancing competitiveness of national machinery industries especially including ship part and power generation industries.

• Bulletin of the Korean Mathematical Society
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• v.56 no.2
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• pp.419-437
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• 2019

This paper investigates skew ${\Theta}-{\lambda}$-constacyclic codes over $R=F_0{\oplus}F_1{\oplus}{\cdots}{\oplus}F_{k-1}$, where $F{_i}^{\prime}s$ are finite fields. The structures of skew ${\lambda}$-constacyclic codes over finite commutative semi-simple rings and their duals are provided. Moreover, skew ${\lambda}$-constacyclic codes of arbitrary length are studied under a new definition. We also show that a skew cyclic code of arbitrary length over finite commutative semi-simple rings is equivalent to either a cyclic code over R or a quasi-cyclic code over R.