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MIMO MC-CDMA시스템에서MMSE 수신기 출력의 점근적 양상
김경연,이충용,심세준,함재상 대한전자공학회 2007 電子工學會論文誌-TC (Telecommunications) Vol.44 No.4
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. 본 논문은 MMSE 수신기를 가지는 MIMO MC-CDMA시스템에서의 출력 SINR을 분석한다. 단일 안테나에서의 분석을 위한 가정들이 다중안테나에 바로 확장 적용되지 않기 때문에 단일 안테나를 가지는 MC-CDMA시스템에 대한 기존의 성능 분석은 MIMO MC-CDMA 시스템에 바로 적용하지 못한다. 그러므로 본 논문에서는 Marcenko Pastur law와 확장된 Haar 유니터리 행렬의 특성을 이용하여 MIMO system에 대한 성능 분석을 시도한다. 분석을 통해 확산 코드 길이가 무한대로 갈 때 출력 SINR이 특정값으로 접근함을 보이고 그 값을 freeness가정을 통해 구하여 비트 오차확률을 구하고 실험과 비교한다.
피크노제놀을 함유한 화장품이 40~50대 한국 여성의 피부에 미치는 영향 - 피부임상학적 접근
김경연,구정은,Kim, Kyung-Yun,Ku, Jung-Eun 한국융합학회 2021 한국융합학회논문지 Vol.12 No.8
Pycnogenol extracted from pine bark is a component with great antibacterial activity and antioxidant effect. It is applied as a natural anti-inflammatory agent with various medical effects including anti-inflammatory effects, regulation of blood pressure, regulation of the immune system, and inhibition of cancer cell growth. However, research related to cosmetics is limited. Therefore, in this study, the effect of Pycnogenol on the skin was studied through a clinical approach. Changes in skin condition were observed after using cosmetics with Pycnogenol and without Pycnogenol for 6 weeks for 10 clinicians in each group. We observed the effect of pore reduction, wrinkle reduction around eyes, a decrease of the number and angle of loose pores, and reduction of pigmentation. Therefore, cosmetics containing Pycnogenol have the effect of improving skin problems of aging skin. 소나무 수피에서 추출한 Pycnogenol은 항균활성과 항산화 효과가 뛰어난 성분으로 항염, 혈압조절기능, 면역조절, 암세포 성장억제 등 다양한 의학적 효능과 함께 천연 소염제로 응용되고 있지만 화장품 관련 연구는 미비한 상황이므로 본 연구는 Pycnogenol 성분이 피부에 미치는 효과를 임상학적 접근한 연구이다. Pycnogenol 성분 첨가, 무첨가한 화장품을 각 각 10명의 임상자가 6주간 사용하게 한 후 피부 상태 변화를 살펴보았으며 모공의 감소, 눈가주름의 감소, 처진모공의 개수와 각도의 감소, 색소침착이 감소하는 효과가 있었다. 그러므로 Pycnogenol 성분을 함유한 화장품은 노화피부에서 나타나는 피부 문제를 개선하는 효과가 있다.
일부 지역 주민들의 모발 수은 농도와 혈중 수은 농도와의 상관성
김경연,서정욱,김병권,김유미,김록범,김대선,김정만,김춘진,홍영습,Kim, Gyeong-Yeon,Seo, Jeong-Wook,Kim, Byoung-Gwon,Kim, Yu-Mi,Kim, Rock-Bum,Kim, Dae-Seon,Kim, Jung-Man,Kim, Choon-Jin,Hong, Young-Seoub 한국환경보건학회 2013 한국환경보건학회지 Vol.39 No.2
Background: This study was carried out for the purpose of comprehensively evaluating the mercury exposure level of residents in several areas and the correlation between hair mercury concentration and blood mercury concentration. Method: One thousand one hundred ninety seven subjects were sampled from 30 sites using random assignment sampling. We performed a questionnaire survey and measured the level of total mercury in hair and blood samples from all subjects. Results: The geometric mean concentrations of hair and blood mercury in all subjects were 1.27 mg/kg [95% confidence interval (CI): 1.23-1.32 mg/kg] and 5.24 ${\mu}g/L$ [95% CI: 5.07-5.41 ${\mu}g/L$], respectively. Male (1.56 mg/kg in hair, 6.00 ${\mu}g/L$ in blood) was significantly higher than that of female (1.03 mg/kg in hair, 4.56 ${\mu}g/L$ in blood), and the concentrations were elevated as age increased up to the 50s. Education, smoking, alcohol drinking, and using of pesticides were also shown to influence mercury concentrations in hair and blood. The ratio of hair/ blood mercury concentration was 261.3. The total mercury concentration in hair was identified to be significantly related with total mercury concentration in blood (r=0.814, p<0.001). Conclusion: The geometric mean concentrations of hair and blood mercury were higher than the levels provided in international recommendations. The total mercury concentration in hair was positively correlated with the concentration in blood. The results of this study suggest that hair mercury be considered as a useful tool for the evaluation of mercury exposure.