• Journal of Navigation and Port Research
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• v.40 no.6
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• pp.441-450
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• 2016

A pilot scale biostimulation experiment was performed under field conditions to degrade organic pollutants and PAHs (Polycyclic Aromatic Compounds) in contaminated coastal sediment. During the experiment, the seawater temperature around the sediment varied from $16.5^{\circ}C$ to $21^{\circ}C$, while the sediment pH was stable at 8.4-8.5. The experiment was conducted over a one year period with a control group and a sample group with a applied biostimulant composed of acetate, sulfate, and nitrate. Chemical oxygen demand decreased 39% in the control group and 79% in the sample group. Volatile solids were reduced from 15 to 7 g/kg in the control group and 2.5 g/kg in the sample group. Out of the 2-, 3- ,4- ,5-, and 6-rings of the 16 vital PAHs, the compound including naphthalene (2-ring), took 2 months to degrade completely, while the degradation efficiency was 55.6% in the control group during the same period. In the case of the 3-ring and 4-ring PAHs, complete degradation in the sample and 46% - 100% degradation in control was observed after one year of the experiment. The 5-ring and 6-ring PAHs were degraded to about 77%-100% in the sample group and 26%-87% in the control group during the one year of the experiment. The study results show that biostimulation is a very effective method to improve the degradation rate of organic pollutants and PAHs (Polycyclic Aromatic Compounds) in contaminated coastal sediment.

• Honam Mathematical Journal
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• v.28 no.4
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• pp.499-511
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• 2006

It is well-known that every finitely generated torsion-free module over a principal ideal domain is free. This will be generalized. We deal with ideals of the finite, external direct product of certain rings. Finally, if M is a torsion-free, finitely generated module over a reduced, Noetherian ring A, then we prove that Ms is a projective module over As, where $S=A{\setminus}(A)$.

• Bulletin of the Korean Mathematical Society
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• v.47 no.3
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• pp.653-661
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• 2010

Let R be a ring, and let $\Psi$(R) be the ideal generated by the set {x $\in$R | 1 + sxt $\in$ R is unit-regular for all s, t $\in$ R}. We show that $\Psi$(R) has "radical-like" property. It is proven that $\Psi$(R) has stable range one. Thus, diagonal reduction of matrices over such ideal is reduced.

• Kyungpook Mathematical Journal
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• v.51 no.3
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• pp.283-291
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• 2011

In this paper, a generalization of the class of semicommutative rings is investigated. A ring R is called central semicommutative if for any a, b ${\in}$ R, ab = 0 implies arb is a central element of R for each r ${\in}$ R. We prove that some results on semicommutative rings can be extended to central semicommutative rings for this general settings.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.204-209
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• 1997

This paper reports on the theoretical study of the vane motions in a positive displacement vane pump. Vane detachment cause the pressure fluctuation, noise, wear in cam ring, and decrease the volumetric efficiency. Dynamic equation of vane motion and flow continuity equation have been modeled and solved simultaneously using 4th order Runge-Kutta method. As results of analysis, vane detachment occurs due to pressure overshoot by excess compression in the pumping chamber. Amount of vane detachment has been reduced by decreasing the pressure overshoot.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.1998-2004
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• 2008

Two synthetic pathways to substituted hexahydroimidazo[1,2-a]pyridines, which may serve as precursors of aza-alkaloids, were investigated. The first involves the condensation of a bisnucleophilic enediaminoester and a biselectrophile. The second involves attachment to nitrogen of the carbon chain skeleton required to form the six-memberd ring, before formation of the enediaminoester. Several substituted hexahydroimidazo[1,2- a]pyridines were synthesized via these two approaches.

• Bulletin of the Korean Chemical Society
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• v.4 no.1
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• pp.41-44
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• 1983

The chlorine addition and Diels-Alder cycloaddition of cyclopentadiene to 1, 4-benzoquinone-4-(O-methyloxime) have been studied MO theoretically. It has been shown that the reactions occur predominantly to the quinone ring double bond which is oriented anti to the nitrogen lone pair due to an n-${\sigma}^*$ interaction between the nitrogen lone pair, n, and the app. vicinal bond, causing the ${\pi}$ bond to be weakened and destabilized due to the less conjugation from reduced delocalization.

• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.657-662
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• 1999

The variation of Jahn-Teller(J-T) distortion imposed on various metallo- tetraphenylporphyrins(MTPPS;M=ZnⅡ,PdⅡ,PtⅡ,and RhⅢ) has been investigated by time-resolved resonance Raman spectroscopy. B1g and B2g modes of the triplet(π,π*) states for the heavy-metal porphyrins exhibit the enhancement of their intensities compared with those of 3ZnⅢTPP, while the enhancement of phenyl internal mode is reduced. These results suggest that the J-T distortion becomes manifest as the metal size increases, and consequently the porphyrin-to-phenyl ring charge transfer in the excited triplet state is inhibited.

• Bulletin of the Korean Chemical Society
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• v.19 no.6
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• pp.667-671
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• 1998

A series of 1-aryl-lH-pyrazolo[4,3-c]quinolines and 2-aryl-2H-pyrazolo[4,3-c]quinolines are prepared by reacting 3-acyl-4-chloroquinolines in ethanol or 3-acyl-4(lH)-quinolone in acetic acid with appropriate hydrazines as possible anti-ulcer agents. A regiospecific synthesis of 1-aryl-lH-pyrazolo[4,3-c]quinolines is also achieved. The central pyridine ring could be easily reduced by catalytic hydrogenation.

• Journal of Korea Multimedia Society
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• v.22 no.2
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• pp.225-230
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• 2019

There are several methods which efficiencies of database are uprise. One of the well-known methods is that segments of database satisfying a query was rapidly accessed and processed. So if it is possible to search completely parallel multiple database segment types which satisfy a query, the response time of the query will be reduced. The matter of obtaining CPS(Completely Parallel Searchable) distribution without redundancy can be viewed as graph theoretic problem, and the operation of ring sum on the graph is used for CPS. In this paper, the parallel algorithm is proposed.