• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.4
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• pp.10-16
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• 2007

This paper analyzes the output signal-to-interference-plus-noise ratio (SINR) for a multiple-input-multiple-output (MIMO) multicarrier code division multiple access (MC-CDMA) system with minium mean square error receivers. A previous work of a single antenna MC-CDMA system cannot directly applied to a MIMO MC-CDMA system because some assumptions for single antenna do not match the case of multiple antenna. Therefore this paper expands the concept of freeness to MIMO system by using the Marcenko Pastur law. The analysis shows that the output SINR asymptotically converges to a deterministic value and finds the value on the assumption of freeness. From the analysis, it is easy to calculate bit error rate and the calculation is verified by simulations.

• Journal of IKEEE
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• v.3 no.2 s.5
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• pp.196-203
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• 1999

In this paper, the DS(direct sequence)-CDMA and MC(multi-carrier)-CDMA, which are being researched recently as a synchronous IMT-2000 scheme for next-generation mobile multimedia communications, are studied in terms of BER(bit error rate) performance. The BER performance of MC-CDMA with EGB, MRC, and improved MMSEC detection scheme are analyzed and compared to that of conventional DS-CDMA adopting RAKE receiver through the computer simulations under the environments of synchronous IMT-2000 transmission channel. Not only single user case but also multiuser case is considered in the given system. As a result, it is shown that MC-CDMA with MMSEC detection outperforms all other schemes improved the $E_b/N_o$ by about 5 [dB] and 6 [dB] when the BER is $2{\times}10^{-3}$, for the indoor/outdoor fading channel and synchronous IMT-2000 transmission channel, respectively. Also in the multiuser case, MC-CDMA with MMSEC detection scheme exhibits better performance than all the other schemes.

• Nuclear Engineering and Technology
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• v.48 no.3
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• pp.765-772
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• 2016

In analyzing residual radiation, researchers generally use a two-step Monte Carlo (MC) simulation. The first step (MC1) simulates neutron transport, and the second step (MC2) transports the decay photons emitted from the activated materials. In this process, the stochastic uncertainty estimated by the MC2 appears only as a final result, but it is underestimated because the stochastic error generated in MC1 cannot be directly included in MC2. Hence, estimating the true stochastic uncertainty requires quantifying the propagation degree of the stochastic error in MC1. The brute force technique is a straightforward method to estimate the true uncertainty. However, it is a costly method to obtain reliable results. Another method, called the adjoint-based method, can reduce the computational time needed to evaluate the true uncertainty; however, there are limitations. To address those limitations, we propose a new strategy to estimate uncertainty propagation without any additional calculations in two-step MC simulations. To verify the proposed method, we applied it to activation benchmark problems and compared the results with those of previous methods. The results show that the proposed method increases the applicability and user-friendliness preserving accuracy in quantifying uncertainty propagation. We expect that the proposed strategy will contribute to efficient and accurate two-step MC calculations.

• Journal of Educational Research in Mathematics
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• v.15 no.4
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• pp.375-399
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• 2005

In this article, I identified many points of commonness and differences at)feared in the fraction units of three conspicuous textbooks -McLellan, MiC and Korea. After that, 1 evaluated these results with reference to more general didactics on which each text-book is based. A background theory of Mc-Lellan's textbook was Dewey's experientialism, and that of MiC was Freudenthal's realistic mathematics education. Through this study, I have reached the fact that these three textbooks could not exhibit the phenomenological wholeness of fraction. Driven by measuring number model which is very abstractive, McLellan's text-book is disregarding the lower level context. MiC textbook, driven by real context, is ignoring higher level model which is close to rational number concept. From an excess of formulation and practice of algorithm, Korea's textbook is overlooking the real context. It is necessary that a textbook which would display the phenomenological wholeness of fraction is developed.

• Tunnel and Underground Space
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• v.11 no.2
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• pp.167-173
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• 2001

The joint model has influence on the results of discontinuum analysis. In this study the results of discontinuum analysis with Barton-Bandis joint model(BB model) and with Mohr-Coulomb joint model(MC model) are compared. The results of continuum analysis under the same condition are compared with the results of discontinuum analysis to investigate the behavior of rockmass around tunnel. The result of continuum analysis and that of discontinuum analysis with BB model show similar distribution of displacement and stress. On the other hand, the discontinuum analysis with MC model shows different displacement distribution and stress distribution. Moreover, the displacement and minor principal stress of the discontinuum analysis with MC model are smaller than those of continuum analysis, although the joints are explicitly considered in the discontinuum analysis. These results are originated from the limitation of MC model in simulating joint deformation behavior, especially the assumption of constant dilation jingle independent of it)int 7hear displacement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.5
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• pp.902-907
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• 2001

In this paper, we analyzed BER performance of the MC DS-CDMA system and evaluated the degree of performance improvement of the system caused by adopting turbo code recently receiving much attention due to its powerful coding capability. As a result of analysis, it was found that the MC DS-CDMA system without any powerful coding scheme can not serve voice quality $(BER : 10^{-3}$ regardless of the number of users and the value of $(BER : 10^{-3)$ in Rayleigh fading channel. On the other hand, it was found that the MC DS-CDMA system adopting turbo code for performance improvement, shows improved BER performance and can serve voice quality without regard to the number of users and the value of $(BER : 10^{-3)$ in the same channel. For example, when $(BER : 10^{-3)$ is l0dB and the number of users was 10, the MC DS-CDMA system adopting turbo code showed improved BER performance about $5\times10^{-3}$.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.4
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• pp.127-131
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• 2007

This study was designed to demonstrate the ability of Texas Eye Research and Technology Center Dry Eye Questionaire (TERTC-DEQ) to examine the distribution of self-reported dry eye symptoms and their diurnal intensity in university students and compare it with McMonnies & Ho DEQ. Two dry eye questionnaires were administered to 46 contact lens wearers and 47 nonwearers. Contact lens wearers scored higher on the TERTC-DEQ (52.2%) than McMonnies & Ho DEQ (6.5%). Non-contact lens wearers also scored higher on the TERTC-DEQ (19.1%) than McMonnies & Ho DEQ (2.1%). Ocular symptoms worsened with progression of time of day in both groups of subjects. This study suggests that TERTC-DEQ provides a first-choice diagnosis tool to obtain a comprehensive assessment of patient's symptoms, especially in comparison with McMonnies & Ho DEQ. The TERTC-DEQ is an efficient screening survey and may be use in dry eye diagnosis of contact lens-related dry eye.

• The Korean Journal of Physiology
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• v.25 no.1
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• pp.61-67
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• 1991

In order to determine possible relationships between the renin-angiotensin system and nephron heterogeneity, we compared the response of renin release and the angiotensin-converting enzyme (ACE) activity from different areas of the rat kidney. We used the renal cortical slices from the capsular surface to the juxtamedullary junction. Slices from outer one-third of the cortex were designated as outer cortical slices (OC), middle one-third as midcortical slices (MC), and inner one-third as inner cortical slices (IC). The renal renin content markedly decreased from OC and MC to IC. The basal lenin release was higher in OC than in MC or IC. On the contrary the percent change of renin release in response to L-isoproterenol was significantly higher in MC than in OC or IC. By TMB-8, the renin release in MC by $231{\pm}21%$ was higher than OC by $171{\pm}19%$ or IC by $$162{\pm}19. Angiotensin II suppressed renin release in OC and MC by $68{\pm}2,\;71{\pm}4%$ respectively, but only $40{\pm}7%$ in IC. The ACE activity was higher in IC than in OC, MC, medulla and papilla. The present data indicate that renin content and basal lenin release gradulally decreased from outer (OC) to inner (IC) cortex. The renin release in response to beta-adrenergic agonist, L-isoproterenol and intracellular calcium antagonist, TMB-8 were higher in MC than in OC and IC, but angiotensin II suppressed renin release less in IC than in OC and MC. It is suggested that juxtaglomerular cells of outer, mid-and inner cortices show a difference in renin release response to the stimuli.

• Journal of Life Science
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• v.23 no.1
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• pp.102-109
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• 2013

To isolate GABA-producing microorganisms, 1,500 strains were isolated from different Chungkookjang samples and screened. From these strains, 20 were selected for further analyses based on a protease and slime-producing activity test. The MC 31 strain showed the highest GABA concentration in Chungkookjang and was used in this study. MC 31 was identified as Bacillus subtilis by an API 50CHB kit and 16S rDNA sequences analysis and named as B. subtilis MC 31. B. subtilis MC 31 showed exponential growth up to 12 hours at $37^{\circ}C$ in LB broth, and it reached a stationary phase after 24 to 36 hours of incubation. B. subtilis MC 31 showed maximum GABA content at 72 hours after incubation at $40^{\circ}C$.

• Journal of Digital Contents Society
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• v.6 no.2
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• pp.101-106
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• 2005

In this paper, performance evaluation of mobile access layer for multiple-input multiple-output (MIMO) MultiCarrier(MC)/CDMA 16 QAM system is considered to mitigate multiple access interference and enhance system channel capacity in Rayleigh wireless fading channel. Traditionally, multi-path is viewed as an undesirable feature of wireless communications. Therefore, diversity and adaptive array schemes are proposed to mitigate its effects. Recently, to increase the spectrum efficiency and the link reliability, MIMO schemes is devised to exploit multi-path in a scattering wireless channel. In particular, the channel capacity of MIMO-MC/CDMA 16 QAM system is evaluated according to Eb/No, Mc, p. From the results, in order to improve the channel capacity, the signals at various elements must be uncorrelated. And if the paths are correlated due to inappropriate spacing or mutual coupling effects, the channel capacity of MIMO-MC/CDMA 16 QAM system becomes substantially smaller.