삼지닥과 Edgeworoside A의 항골다공증 및 천남성의 미백 효과에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 농업생명과학대학 농생명공학부, 2018. 2. 서진호.Natural products have been considered a rich source of new drugs, nutraceuticals and cosmeceuticals for decades. Efforts on discovering new bioactive ingredients with drug-like benefits from natural products have been aided greatly by the availability of natural product-derived libraries (collection of crude mixtures, fractions, and purified compounds). In this thesis, a library of extracts derived from 4,200 plants native to Korea was exploited to identify candidates for anti-osteoporosis agents and anti-melanogenic agents. The approach to discover candidates for anti-osteoporosis agents involves a series of assays that utilize biomarkers for osteoclast and osteoblast differentiation: the library was screened for the ability to inhibit RANKL-induced NF-κB (nuclear factor–kappa B) expression in RAW 264.7 osteoclatic cells, to modulate the activity of alkaline phosphatase in MC3T3-E1 osteoblastic cells, and to enhance the deposition of extracellular calcium in osteoblasts in vitro. These efforts in conjunction with a dereplcation technology led to identification of Edgeworthia papyrifera and edgeworoside A which exhibited a desired bioactivity profile in vitro. In an animal model of post-menopousal osteoporosis, E. papyrifera was demonstrated to improve all of the osteoporosis relevant parameters, suggesting that E. papyrifera and edgeworoside A may be used as functional ingredients in health supplements to increase bone strength and as therapeutics to treat osteoporosis. Identification of candidates for anti-melanogenic agents involves a series of tests that utilize α-MSH-stimulated melanogenesis in vitro and quantification of tyrosinase and TRP1 expression in B16F1 cells. The efforts led to identification of Rhizoma arisaematis that inhibited biosynthesis of melanin and expression of tyrosinase and TRP1 in α-MSH-treated B16F1 cells. The anti-melanogenic effect of R. arisaematis was mediated through activation of autophagy in B16F1 cells, and pharmacological inhibition of autophagy reduced the anti-melanogenic activity of R. arisaematis in α-MSH-treated B16F1 cells. Further analyses of R. arisaematis using three-dimensional skin substitutes and in a human clinical trial revealed that it significantly suppressed pigmentation and exerted whitening effects on human skin. These observations serve as a basis for further elaboration of R. arisaematis for the development of functional skin care products.Chapter 1. Literature review 1 1.1. Overview of natural products from plants 2 1.1.1. Natural products from plants 2 1.1.2. Natural products as drug and ingredients for health food and cosmetic 5 1.2 Osteoporosis and plant natural products 9 1.2.1. The nature of osteoporosis 9 1.2.2. Drugs and osteoporosis 14 1.2.3. Mechanism of Osteoporosis 24 1.2.4. Natural products for treatment of osteoporosis 35 1.3. Natural products from plants for whitening 66 1.3.1. Plant natural products for cosmetic ingredients 66 1.3.2. Melanogenesis and whitening 69 1.3.3. Autophagy and whitening 76 1.4. Objectives of the dissertation 82 Chapter2. Effects of Edgeworthia papyrifera and Edgeworoside A on osteoporosis as potent preventive and therapeutic agents 83 2.1. Summary 84 2.2. Introduction 86 2.3. Materials and methods 90 2.4. Results 106 2.4.1. Development of HTS-compatible assays 106 2.4.2. Screening for potent anti-osteoclastic plant extracts 107 2.4.3. Screening for potent osteogenic plant extracts 109 2.4.4. Selection of anti-osteoporotic plant extracts 110 2.4.5. Preventive effect of Edgeworthia papyrifera and D. genkwa extracts on ovariectomized mice 111 2.4.6. Therapeutic effect of E. papyrifera extract on ovariectomized rats 113 2.4.7. Identification of phytochemicals in E. papyrifera 119 2.4.8. Effect of phytochemicals on the activity of osteoclast and osteoblast 121 2.4.9. Identification and activity of purified Edgeworoside A 121 2.5. Discussion 124 Chapter 3. Whitening effect of Rhizoma arisaematis as functional cosmetic material 166 3.1. Summary 167 3.2. Introduction 168 3.3. Materials and methods 171 3.4. Results 178 3.4.1. Screening of potent anti-melanogenic plant extracts 178 3.4.2. Effect of R. Arisaematis on pigmentation in normal human epidermal melanocytes and human skin 178 3.4.3. Confirmation of anti-melanogenic effects in B16F1 cells 179 3.4.4. Role of R. Arisaematis in activation of autophagy in B16F1 cells 180 3.4.5. Effect of autophagy inhibition in R. Arisaematis-mediated anti-melanogenic activity in B16F1 cell 181 3.5. Discussion 183 Chapter 4. Conclusions and future directions 194 4.1. Conclusion of anti-osteoporotic natural products 195 4.2. Conclusion of whitening natural product 197 4.3. Future directions 198 References 199 국문 초록 218Docto

비직교 다중접속 기반 위성통신시스템에 강인한 동기 기술에 관한 연구

학위논문(박사) - 한국과학기술원 : 정보통신공학과, 2024.2,[vii, 77 p. :]This dissertation is about robust synchronization techniques in NOMA-based satellite communication systems. Recently, satellite communication has played an important role in constructing a three-dimensional spatial network that provides a wireless access network to areas where terrestrial networks cannot reach. Efficiency in data transmission can be increased by distributing and connecting large amounts of data through geostationary and nongeostationary orbit satellite communication networks. In these satellite communication transmission technologies, various transmission techniques have been proposed depending on the service type, and this paper also proposes various synchronization technologies depending on each satellite communication frequency, protocol, and channel environment. First, synchronization technologies that are robust to LDM technology to improve data rates in the same band in geostationary satellite broadcasting and communication environments, are proposed. In the case of LDM technology, robust synchronization technology is required because performance degradation occurs when removing interference due to co-channel interference problems due to the use of the same RF and non-linear amplifiers and phase noise. Second, when FTN technology is applied to improve transmission efficiency per bandwidth in a satellite communication environment, inter-symbol interference occurs. Therefore, a symbol synchronization technology that is robust to inter-symbol interference is needed, and this paper proposes a technique close to the maximum likelihood algorithm. Lastly, robust synchronization technology is proposed that is robust to non-geostationary satellite or high-speed mobile terminals in short packet transmissions such as random access channel environments. In particular, the proposed scheme is suitable for timing synchronization in a large Doppler error environment, and its performance evaluation is carried out. In summary, the proposed synchronization techniques presented in this dissertation play a vital role in improving the overall transmission efficiency of satellite communication systems, addressing specific challenges associated with LDM, FTN, and high Doppler effect conditions.한국과학기술원 :정보통신공학과

Lattice Reduction Aided MIMO Detectors with Quantization Error Correction

Lattice reduction (LR) 검파기는 다중 입출력 (multi-input multi-output, MIMO) 시스템에서 성능을 향상시키기 위해 제안되었다. ZF (zero-forcing) 과 MMSE (minimum mean square error) 와 같은 선형 검파기를 LR 과 결합한 방식을 LR 검파기라 부르고, 이러한 방식은 최대 diversity 를 얻는다. LR 검파기는 신호를 검파하기 위해 양자화 (quantization) 과정이 필요하다. 양자화 과정에서 발생하는 오류는 성능을 열화시킨다. 본 논문은 성능의 향상을 위해 양자화 오류를 정정하는 알고리즘을 제안하고, 모의 실험을 통해 제안된 알고리즘의 성능을 검증한다

Carrier Phase Recovery Algorithm for LDPC Coded System

In this paper, we present a carrier phase estimation algorithm for LDPC coded systems. LDPC coded system can not achieve the ideal performance if phase offset is introduced by channel. However, the estimation of phase offset is very hard since the operating point of LDPC is very low SNR. To solve this problem, the algorithm using the tentative soft decision value and based on Maximum Likelihood (ML), was proposed in [2]. But this algorithm has problem which works only under constant phase offset. If phase offset is time variant, it has a severe degradation in performance. To solve this problem, we propose two types of estimators, symbol by symbol estimator: Unidirectional estimator (UDE) and bi-directional estimator (BDE), and sub-block estimator (SBE)

Phase Synchronization Algorithms for High-speed Satellite Communications

본 논문에서는 고속 위성 통신 시스템에 적합한 위상 동기 알고리즘을 제시하고, 추적 성능을 평가하였다. 낮은 SNR 에서 작동하고 신속한 초기 포착 특성이 우수한 알고리즘을 사용해야 하는 위성 통신에 있어 채널 코딩은 필수적이다. 따라서 코딩에 적합한 위상 동기 방식이 필요하다. 그러나 기존의 Decision Directed (DD)나 Non-Data-Aided (NDA) 방식은 Cyclic Slipping 과 Hang up 현상에 민감하기 때문에 낮은 SNR에서 코딩 이득을 얻을 수 없다. 이러한 현상을 보안 하기 위해 Tentative Decision (TD) 방식이나 Per Survivor Processing (PSP) 방식이 제안 되었다. 본 논문에서는 DD-Costas 루프, TD 그리고 PSP 방식의 동기 획득 시간과 Mean Time to Slip (MTS)을 측정하여 PSP 방법이 다른 두 방법에 비해 Cyclic Slipping 과 Hang up 현상에 강하다는 것을 보였다