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다중셀 환경에서 MIMO-MC-CDMA시스템의 점근적 성능
김경연,이충용,함재상 대한전자공학회 2007 電子工學會論文誌-TC (Telecommunications) Vol.44 No.7
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 in multi-cell environments. A previous work in single cell environments is extended into analysis in multi-cell environments. The use of Haar unitary code matrix for asymptotic analysis causes other cell interferences expressed with a diagonal matrix having different diagonal values. This paper shows that other cell interferences converge to an identity matrix whose gain is expressed by only other cell interference power in mean square sense and finds asymptotic deterministic SINRs for a given other cell interference. Under the assumption that the sum of lognormal fading components is distributed by other lognormal function, we show the comparison between theoretical performances and simulations from the view point of bit error rate and present average throughput performance according to the cell radius. 본 논문은 다중 셀 환경에서 MMSE 수신기를 가지는 MIMO MC-CDMA시스템의 출력 SINR을 점근적으로 분석한다. 단일 셀에서의 점근적 성능 분석이 다중셀 환경으로 확장 적용된다. 점근적 분석을 위한 Haar 유니터리 코드의 사용은 다른 셀로부터의 간섭성분이 대각성분들의 값이 다른 대각행렬로 나타나게 한다. 본 논문에서는 다른 셀의 코드 간섭 성분을 mean square측면에서 간섭의 전력으로 수렴함을 보이고, 셀간 간섭 성분이 주어질 때 점근적으로 특정 SINR값을 찾는다. 다중 셀에서의 거리에 따른 느린 페이딩을 로그노말 분포를 가정하여 구한 이론적인 비트오차 확률과 실험을 비교하여 비슷함을 보이고, 점근적 성능에 의한 데이터 전송 수율의 셀 반경에 따른 성능을 보인다.
리포좀화된 이데베논 화장품 성분이 노화피부에 미치는 영향
김경연 국제보건미용학회 2022 국제보건미용학회지 Vol.16 No.3
This study attempted to examine the effects of antioxidant liposomal idebenone on skin aging against middle-aged women in their 40-50s through a clinical approach. For this, a control group used 2 different liposomal idebenone-free cosmetics over six (6) weeks while an experimental group used 2 different cosmetics containing 2% idebenone. Then, skin changes before and after using the cosmetics were analyzed. In the control group, no statistically significant change was found in the pore index, eye-wrinkle index, facial expression wrinkle index, facial wrinkle index, pigmentation index, brightness index, texture index, moisture index and flush index. In the experimental group, on the contrary, a statistically significant decrease was observed in the pore index, eye-wrinkle index, facial expression wrinkle index, facial wrinkle index and pigmentation index while the brightness index revealed a significant increase. In contrast, no statistically significant change was found in the texture index and moisture index while the flush index showed a slight increase. Among the various problems of aged skin, in other words, liposomal idebenone reduced the pore issues, pigmentation and wrinkles and increased the brightness index. Therefore, it is reasonable to conclude that liposomal idebenone is valuable as a cosmetic material for aged skin.