• Korean Journal of Ecology and Environment
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• v.56 no.1
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• pp.1-13
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• 2023

Targeting Microcystin (MC), which is most abundantly detected in the North-Han River water area, we analyzed the relationship between the MC biosynthesis gene (mcyA gene), cyanobacteria cell density, and MC concentration, derived an RNA-MC conversion formula, and derived the cyanobacteria. The concentration of MC present in cells was predicted. In the North-Han River waters, the mcyA gene was found mainly at downstream sites of the North-Han River after Muk-Hyeon Stream junction, and higher copy numbers were found on average than other sites. In the Uiam Lake waters upstream of the North-Han River, the mcyA gene copy number increased at the Kong-Ji Stream point, and after September, the mcyA gene copy number decreased throughout the North-Han River waters. The expression of the mcyA gene was concentrated in the short period of summer due to the spatio-temporal difference between upstream and downstream water bodies. The mcyA gene expression level was not only highly correlated with MC concentration, but also correlated with the cell density of Microcystis aeruginosa and Dolichospermum circinale, which are known to biosynthesize MC. Six conversion formulas derived based on the RNA-MC relationship showed statistical significance (p<0.05) and exhibited high correlation coefficients (r) of 0.9 or higher. The expression level of MC biosynthesis gene present in eRNA determines the synthesis of cyanotoxin substances in water, quickly quantifies gene activity, and can be fully utilized for early warning of MC development.

• Journal of the Korean Mathematical Society
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• v.50 no.5
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• pp.959-972
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• 2013

Rege-Chhawchharia, and Nielsen introduced the concept of right McCoy ring, based on the McCoy's theorem in 1942 for the annihilators in polynomial rings over commutative rings. In the present note we concentrate on a natural generalization of a right McCoy ring that is called a right nilpotent coefficient McCoy ring (simply, a right NC-McCoy ring). The structure and several kinds of extensions of right NC-McCoy rings are investigated, and the structure of minimal right NC-McCoy rings is also examined.

• ETRI Journal
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• v.26 no.5
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• pp.405-412
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• 2004

MC-CDMA, a multicarrier (MC) modulation scheme based on code division multiple access (CDMA), is the most likely candidate for the next generation of mobile radio communications. The rate compatible punctured turbo (RCPT) coded hybrid automatic repeat request (HARQ) has been found to give improved throughput performance in a direct sequence (DS) CDMA system. However, the extent to which the RCPT HARQ improves the throughput performance of an MC-CDMA system has not been fully understood. In this paper, we apply the RCPT HARQ to MC-CDMA and evaluate by computer simulations its performance in a frequency selective Rayleigh fading channel. We found that the performance of RCPT HARQ MC-CDMA is almost insensitive to channel characteristics. The performance can be drastically improved with receive diversity combined with space-time transmit diversity. In addition, the comparison of RCPT HARQ MC-CDMA, orthogonal frequency division multiplexing, and DS-CDMA shows that under similar conditions the throughput of MC-CDMA is the best in a frequency selective fading channel.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.3C
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• pp.228-236
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• 2006

A Multicarrier code division multiple access(MC-CDMA) is a scheme that combines multicarrier modulation with CDMA. It offers robustness to frequency selective fading effect and can support higher rate data transmission with higher spectral efficiency. The objective of this article is proposed and analyzed a new asynchronous MC-CDMA system with various kinds of data rates which employs a multiple access interference (MAI) canceller. The proposed multirate MC-CDMA system can be accomplished by changing the number of Parallel branch(P) according to their data rate and hybrid interference canceller(HIC) are used for MAI cancellation. We compare the performance of proposed system in terms of average bit error rate(BER) with that of a single rate MC-CDMA system. The results show the large improvement in performance that can be attained by the cancellation scheme under multipath environments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.693-697
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• 2005

In this paper, it was estimated the BER performance of the individual system type by applying the SFH type and the FFH type to the FH MC-DS CDMA system that combined the strong points of MC DS/CDMA and that of Frequency Mewing under the Nakagami fading channel with Multi-tone Jamming. An increase in the number of hoppings means that it can improve theBER performance by reducing the receiving burden of the FH MC DS/CDMA by achieving a frequency diversity effect. Therefore, I verified that the performances of the FH MC DS/CBMA system could be impoved by increasing the number of hoppings.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11C
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• pp.851-859
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• 2008

This paper investigates the effect a guard period (GP) in the form of a cyclic prefix for asynchronous multicarrier-code division multiple access (MC-CDMA) systems. At first, we analyze the performance of asynchronous MC-CDMA systems with a GP, which results in closed-form bit error rate (BER) performance. Furthermore, it confirms that the frequency diversity of MC-CDMA systems is identical to the path diversity. The analytical approach proposed here is extended to the case without a GP. The derived analytical results show that a GP is required for MC-CDMA systems in order to mitigate not only the effect of intersymbol interference (ISI) and intercarrier interference (ICI) but also the desired signal power degradation. In addition, the accuracy of the proposed analysis is verified by simulations.

• The KIPS Transactions:PartD
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• v.16D no.6
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• pp.911-920
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• 2009

Airbone software must comply the DO-178B standard in order to be certified by the FAA. The standard requires the unit testing of safety-critical software to meet the coverage criterion called MC/DC(Modified Condition/Decision Coverage). Although MC/DC is known to be effective in finding errors related to safety, it is also true that generating test cases which satisfy the MC/DC criterion is not easy. This paper presents a tool named MD-SAT which generates MC/DC test cases with SAT(SATisfiability) technology. It can be employed for generating diverse test cases in tools implementing various testing techniques including decision table based test, cause-effect graphing, and state-based test.

• Journal of Korea Water Resources Association
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• v.38 no.9 s.158
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• pp.727-736
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• 2005

In this study, the upwind McCormack scheme is introduced to combine the advantage of McCormack scheme, the second order accuracy and simplicity, and the advantage of the upwind scheme, to be applied to the discontinuous flows. This scheme also has another advantage of treating the source terms effectively. This model is approved through applying to the discontinuous flow case with the analytical solution, and the natural river with very strong source terms. Applications of the upwind McCormack scheme developed in this paper show good agreements with the analytical solution without numerical oscillation in existing McCormack scheme. Futhermore, applications to the natural river, the lower Han river with strong variation of bed and width, also show good results in case of both steady flow and unsteady flow. The upwind McCormack scheme in this study will be used for the analysis of flow in natural rivers effectively.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.39.1-39.1
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• 2010

We have investigated interplanetary (IP) structures of 82 intense geomagnetic storms (Dst $\leq$ -100 nT) that occurred from 1998 to 2006. According to their interplanetary origins, we classified them as four groups: 20 sMC events (IP shock and MC), 19 SH events (sheath field), 12 SH+MC events (Sheath field and MC), and 8 nonMC events (non-MC type ICME). For each group, we examined the relationships between Dst index and solar/IP parameters, namely, direction parameter (DP), CME speed ($V_{CME}$), solar wind speed ($V_{SW}$), minimum of IMF $B_z$ component($Bz_{min}$), and maximum of $E_y$ component ($Ey_{max}$).We found that the relationships strongly depend on their IP source. Our main results can be summarized as follows: 1) The correlation between Dst and DP is the best for the SH+MC events (r = -0.61). 2) The relationship between Dst and $V_{CME}$ gives the best correlation for the sMC events (r = -0.56). 3) There is the best correlation between Dst and $V_{SW}$ for the sMC events (r = -0.61), while there is a very weak correlation (r=-0.17) for the SH events. 4) The relationship between Dst and $Bz_{min}$ gives the best correlation (r = -0.87) for the SH+MC events. 5) The correlation between Dst and $Ey_{max}$ is the best for the SH+MC events (r = -0.87). Summing up, the sMC and SH+MC events give us good correlations, but the SH events, weak correlations. From this study, we suggest that this tendency should be caused by the characteristics of IMF southward components, e.g., smooth field rotations for the MC events and highly IMF fluctuations for the SH events.

• Toxicological Research
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• v.14 no.4
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• pp.587-594
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• 1998

In order to understand the mechanism if the regulation of CYP 1A1 gene expression and ethoxyresorufin deethylase (EROD) activity in ex vivo system, we have studied the action of TCDD and 3MC in the isolated perfused female rat liver. CYP1A1 mRNA level and EROD activity were measured in rat liver that was isolated and perfused with various chemicals such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 3-methylcholanthrene (3MC), 17$\beta$-estradiol (E$_2$), morin. TCDD or 3MC alone perfusion into female rat liver resulted in increase of CYP 1A1 mRNA level and the magnitude of stimulation was six times higher with TCDD treatment than 3MC treatment. However E$_2$ perfusion into female rat liver showed inhibition of CYP 1A1 mRNA level. When 10$^{-8}$ M E$_2$ was administered concomitantly with either 10$^{-9}$ M TCDD or 10$^{-9}$ M 3MC, stimulated CYP 1A1 mRNA by either TCDD or 3MC was inhibited. Morin was examined for its effects on CYP 1A1 mRNA level and result was similar to that was observed with estrogen. EROD activity was also stimulated with either TCDD or 3MC perfusion, and the magnitude of EROD stiumlation was smaller than that of CYP 1A1 mRNA stimulation in response to TCDD or 3MC perfusion. Unlike CYP1A1 mRNA level, stimulation of EROD activity was greater with 3MC than TCDD. Concomitant perfusion either E$_2$ or morin with TCDD or 3MC inhibited 3MC perfusion or TCDD perfusion stimulated EROD activity. These data suggested that TCDD and 3MC might act diffrently in terms of regulation of CYP 1A1 gene expression in rat liver.