• 한국통신학회논문지
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• 제32권3C호
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• pp.216-225
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• 2007

본 논문에서는 대표적인 반복 부호 알고리즘인 터보 부호, LDPC부호 TPC 등 세 가지 알고리즘에 대해 8PSK 이상의 다치 변조 방식 적용을 위해 수신단에서 비트 분리 방법을 제시한다. 수신된 I, Q 심볼만을 이용하여 세 비트 이상의 비트를 분리하기 위한 LLR 방식에 기초를 하여 LLR 방식의 단점인 복잡도를 개선하기 위해 Euclidean, MAX, Sector 방식을 제시하였으며, 세 가지 반복 부호에 대해 최적의 비트 분리 방법을 제시하였다.

• 전자공학회논문지A
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• 제33A권4호
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• pp.37-46
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• 1996

In this paper, we analyzed the performance improvement of the DS-CDMA/dPSK cellular mobile communication system with CCI canceller and RAKE receiver techniques in mobile radio channel which is characterized by AWGN, Multi-user interference (mUI) and frequency-selective rayleigh fading. System capacity i.e., number of user per cell has been derived and the evaluated results are shown in figuraes as a function of PN code sequence length, number of RAKE receiver tap, BER and E$_{b}$/N$_{o}$. The voice activity factor is assumed to be 3/8 the number of sectors in a cell 3 and MUI is modeled as gaussian process. From the results, the capacity of the DS-CDMA/DPSK cellular mobile communication system is improved by adopting CCI canceller. When we adopt the RAKE receiver to mitigate the multipath fading, the error performance is improved and the amount of improvement is proportional ot the number of taps L in the case that each tap contains a signal component and the better of improvement can be obtained, the smaller of the SNR difference in each tap. The system capacity is more increased when the CCI canceller and the RAKE receiver is used in cascade.

• 천문학회보
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• 제37권2호
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• pp.157.2-157.2
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• 2012

Direct-conversion receivers often suffer from a DC-offset that is a by-product of the direct conversion process to baseband. In general, a basic approach to reduce the DC-offset is to do simple average of the baseband signal and remove the DC by subtracting the average. However, this gives rise to a residual DC offset which degrades the performance when the receiver adopts the coding schemes with high coding rates such as 8-PSK. Therefore, more advanced methods should be additionally required for better performance. While the training sequences are basically designed to have good auto-correlation properties to facilitate the channel estimation, they may be not good for the simultaneous estimation of the channel response and the DC-offset. Also the DC offset compensation under a bad condition does not give good results due to the estimation error. Correspondingly, the proposed scheme employs the two important points. First, the training sequence codes are divided into two groups by MSE(Mean Squared Errors) for estimating the channel taps and then SNR calculated from each group is compared to predefined threshold to do fine DC-offset estimation. Next, ON/OFF module is applied for preventing performance degradation by large estimation error under severe channel conditions. The simulation results of the proposed scheme shows good performances compared to the existing algorithm. As a result, this scheme is surely applicable to the receiver design in many communications systems.

• Journal of Communications and Networks
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• 제8권3호
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• pp.290-296
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• 2006

In this paper, a generalized blind adaptive algorithm is introduced for multi-user detection of direct sequence code division multiple access (OS-COMA) wireless communication systems. The main property of the proposed algorithm is its ability to resolve the multipath fading channel resulting in inter symbol interference (ISI) as well as multiple access interference (MAI). Other remarkable properties are its low complexity and mitigation to the near-far problem as well as its insensitivity to asynchronous transmission. The proposed system is based on the minimization of the output energy and convergence to the minimum mean square error (MMSE) detector. It is blind in the sense that it needs no knowledge of the other users' signatures, only the intended user signature and timing are required. Furthermore, the convergence of the minimum output energy (MOE) detector to the MMSE detector is analytically proven in case of M-ary PSK. Depicted results show that the performance of the generalized system dominates those previously considered. Further improvements are obtained when multiple input multiple output (MIMO) technique is employed.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.383.1-383.1
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• 2002

In connection with our studies on the isolation of hepatoprotective constituents from natural products. we have recently reported hepatoprotective compounds including phenolic bakuchiol. diarylheptanoids. furocoumarins. In the course of continuing efforts. the aqueous extract of the roots of Agrimonia pilosa Ledeb. (Rosaceae) was found to exhibit promising hepatoprotective activity. A. pilosa is a perennial herb distributed throughout South Korea. and its roots have been used as the hemostatic. antimalarial. and antidysenteric agent in oriental medicine. Chemical investigation of the aqueous extract of the roots of this plant. as guided by hepatoprotective active catechin (2). Compound 1 showed hepatoprotective effects on both tacrine-induced cytotoxicity in human level derived Hep G2 cells and tert-hydroperoxide-induced cytotoxicity in rat primary hepatocyles with $EC_{50}$ values of 66.2 $\pm$ 2.8 and 22.9 $\pm$ 2.6 $\mu\textrm{M}$ respectively.

• 대한약학회:학술대회논문집
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• 대한약학회 2003년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2-2
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• pp.222.1-222.1
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• 2003

This study was carried out to investigate the quality control of domestic and imported Puerariae Radix. It was analyzed by HPLC using ${\mu}$-Bondapak C$\sub$18/ column with 35% MeOH containing 1% CH$_3$3CO$_2$H system as the mobile phase at UV 254nm. Good linearity showed over the range of 10 to 200$\mu\textrm{g}$/$m\ell$(r$^2$=1) for Puerarin, and 0.5 to 10$\mu\textrm{g}$/mg(r$^2$=0.9999) for Daidzein. The average contents of Puerarin and Daidzein were 5.5${\pm}$1.2%(Domestic), 5.3${\pm}$0.7%(Imported), and 0.05${\pm}$0.02%(Domestic), 0.08${\pm}$0.02%(Imported).The average recovery rates of Puerarin and Daidzein were 101.8${\pm}$1.9% and 97.2${\pm}$0.7%, respectively.

• 대한약학회:학술대회논문집
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• 대한약학회 2002년도 Proceedings of the Convention of the Pharmaceutical Society of Korea Vol.2
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• pp.306.1-306.1
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• 2002

Cefodizime has originally been developed for treating infections as antibiotics. However. according to some of recent studies. cefodizime. a third generation cephalosporin. may potentially have the capability of stimulating chemotactic activity of neutrophils and monocytes as well as the strong immuno-modulator. In this study. we studied to learn about the expressive effect of dentritic cells and macrophage. With this background. We have studied to see if cefodizime can be a potential substance inducing an immunological function in dendritic cells and peritoneal macrophages. IL-12 activates NK cell and macrophage, and shows antiviral effect by excreting INF-${\gamma}$. In vitro. total RNAs were extracted from murine dentritic cell at 4, 8, 12, 24hr after the application of 10, 50, 100${\gamma}g$/ml of cefodizime wighout other stimulators. And we analyzed IL-12 mRNA using RT-PCR method. In conclusion. IL-12 mRNA was increased. and the results suggest that cefodizime activate TH1 cell induction, CTL differentiation as well as accelerating the increase of NK. LAK cell.

• 한국통신학회논문지
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• 제36권5B호
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• pp.517-529
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• 2011

본 논문에서는 차세대 해상 통신 시스템인 SANET (Ship Ad-hoc NETwork)의 우선 전송 규격 파라미터를 설정하고, VHF 대역의 실측 해상 채널을 분석하여 SANET 채널 모델링을 수행한다. 또한, 프리앰블, guard time, 파일롯을 포함한 단일 및 다중 반송파 시스템을 위한 프레임 구조를 제안하며, 제안된 프레임 구조 하에서 채널 보상과 채널 부호화 기법에 의한 SANET 시스템의 BER (Bit Error Rate) 성능을 평가 및 분석한다. 결과로 ${\pi}$/4-DQPSK와 ${\pi}$/8-D8PSK를 적용한 단일 반송파 SANET의 경우, differential 변조방식 채택에 의하여 별도의 채널 보상을 하지 않으며, 부호화 이득을 얻을 수 있는 컨볼루션 부호화를 적용하기로 한다. 다중 반송파 SANET의 경우에는 해상환경, 파도에 의한 선박의 움직임 등에 의한 K값의 변화를 고려하여 시스템의 성능을 최대화 하도록 채널 보상 기법과 컨볼루션 부호화를 적용한다.

• 약학회지
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• 제59권3호
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• pp.92-97
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• 2015

KIOM-MA128 is a novel Korean herbal medicine with anti-atopic, anti-inflammatory and anti-asthmatic effects. This article presents the first pharmacokinetic study on KIOM-MA128. The purpose of this study was to characterize a pharmacokinetic characteristic of matrine, a potential marker of KIOM-MA128, in rats using population pharmacokinetic model. 1, 2 and 8 g/kg of KIOM-MA128 were administered to rats orally and plasma concentrations of matrine was determined by HPLC-MS/MS. Non-compartmental analysis (NCA) was performed using Phoenix$^{(R)}$ and pharmacokinetic model was built using NONMEM$^{(R)}$. This model was validated with internal validation which is visual predictive check (VPC) and bootstrap. The NCA result of matrine showed that $C_{max}$ was 294.24, 552.22 and 868.65 ng/ml, $AUC_{inf}$ was 1273.05, 2724.76 and $9743.25ng{\cdot}hr/ml$ and $T_{max}$ was 1, 1.3 and 2.3 hr for the doses of 1, 2, and 8 g/kg, respectively. The rat plasma concentrations were described very well with one-compartment model. Pharmacokinetic model for matrine was successfully developed and evaluated. Finally, our model is helpful to understand pharmacokinetic characteristic of KIOM-MA128.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권8호
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• pp.2900-2922
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• 2021

In this paper, the power spectral density(PSD) for Multilevel Minimum Shift Keyed signal with modulation index h = 1/2 (M-ary MSK) are derived using the mathematical method of the Markov Chain model. At first, according to an essential requirement of the phase continuity characteristics of MSK signals, a complete model of the whole process of signal generation is built. Then, the derivations for autocorrelation functions are carried out precisely. After that, we verified the correctness and accuracy of the theoretical derivation by comparing the derived results with numerical simulations using MATLAB. We also divided the spectrum into four components according to the derivation. By analyzing these figures in the graphic, each component determines the characteristics of the spectrum. It is vital for enhanced spectral characteristics. To more visually represent the energy concentration of the main flap and the roll-down speed of the side flap, the specific out-of-band power of M-ary MSK is given. OMLCD(Optimum Maximum Likelihood Coherent Detection) of M-ary MSK is adopted to compare the signal received with prepared in advance in a code element T to go for the best. And M-ary MSK BER(Bit Error Rate) is compared with the same ary PSK (Phase Shift Keying) with M=2,4,6,8. The results show the detection method could improve performance by increasing the length of L(memory inherent) in the phase continuity.