• Journal of Agricultural Extension & Community Development
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• v.3 no.2
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• pp.211-218
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• 1996

The soil revitalization movement is the important approach to intensify the agricultural production and sustainable agriculture for the future. The soil have been polluted by abusing chemical fertilizer and inflow foul water from factories and houses during the last three decades. That`s not only farmer`s responsibility but all of us. The cooperative efforts are needed to preserve soil and environment.

• Journal of the Korea Society for Simulation
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• v.6 no.1
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• pp.1-13
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• 1997

In this paper, we present a partitioning algorithm for distributed simulation of DEVS (Discrete Event System Specification) models. To preserve concurrency inherent in models, the proposed algorithm utilizes the structural information of models. Through benchmark simulation experiments, we show that the proposed algorithm can generate good partitions.

• Kyungpook Mathematical Journal
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• v.46 no.1
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• pp.89-96
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• 2006

For a rank-1 matrix A, there is a factorization as $A=ab^t$, the product of two vectors a and b. We characterize the linear operators that preserve rank and some equivalent condition of rank-1 matrices over a chain semiring. We also obtain a linear operator T preserves the rank of rank-1 matrices if and only if it is a form (P, Q, B)-operator with appropriate permutation matrices P and Q, and a matrix B with all nonzero entries.

• Kyungpook Mathematical Journal
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• v.53 no.2
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• pp.273-283
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• 2013

In this paper, we consider the row rank inequalities derived from comparisons of the row ranks of the additions and multiplications of nonnegative integer matrices and construct the sets of nonnegative integer matrix pairs which is occurred at the extreme cases for the row rank inequalities. We characterize the linear operators that preserve these extreme sets of nonnegative integer matrix pairs.

• Journal of Environmental Health Sciences
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• v.19 no.3
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• pp.36-40
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• 1993

The objective of this research was to retrofit an on-site sewage treatment system suitable to current situation of Korea to reduce the pollution loading and preserve the invaluable water resources. Operation at the F/M ratio of 0.1 kg. BOD/kg MLSS day showed 87.1% BOD removal efficiency and 84.5% COD removal efficiency, and its effluent concentration was 6.4 mg/l as BOD and 21.7 mg/l as COD. Average removal of total nitrogen showed high removal efficiency of 80%.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.510-512
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• 1993

The weighted median hybrid filters are proposed. These filters take weighting factors in calculating the output of subfilters of median hybrid filters. The properties of weighted median hybrid filters are analysed and compared to the conventional median filter. The results indicate that these filters preserve details of edge better than and are computationally much more efficient than conventional median filter.

• Proceedings of the KIEE Conference
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• 1993.07a
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• pp.319-322
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• 1993

This paper presents model reduction method of multivariable systems using orthogonal transformation based on aggregation method in time domain. Reduced model which is desisted by presented method preserve stability as relative dominant eigenvalues are selected in original system and obtained computational advantages using orthogonal functions.

• Journal of the Korean Professional Engineers Association
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• v.43 no.5
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• pp.35-40
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• 2010

The world economy is threatened by rising oil prices due to the depletion of resources, and climatic changes are intensified due to rapid increase of greenhouse gases emission. Global warming is recognized as a worldwide problem not only as national level one, collaborative efforts are in progress actively. The fact is that the development of new & renewable energy which can replace fossil fuel and preserve the environment is the key of the attention in accordance with "low carbon, green growth" policy of our government. Biogas is an energy source. And the best part of using biogas is that wastes are treated in its production process.

• Journal of the Korean Mathematical Society
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• v.43 no.3
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• pp.539-552
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• 2006

For an $n{\times}n$ Boolean matrix A, A is called nilpotent if $A^m=O$ for some positive integer m. We consider the set of $n{\times}n$ nilpotent Boolean matrices and we characterize linear operators that strongly preserve nilpotent matrices over Boolean algebras.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.3
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• pp.401-405
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• 2008

We investigate the properties of fuzzy relations and $\odot$-equivalence relation on a stsc quantale lattice L and a commutative cqm-lattice. In particular, fuzzy relations preserve(*, \otimes$)-equivalence relations where $\otimes$ are compositions, $\Rightarrow$ and $\Leftarrow$.