Apoptotic effect of compound K in HCT116 cells via caspase 3 and p53 dependent LGR5 inhibition

박지나 Kyung Hee University 2019 국내석사

Abstract Apoptotic effect of compound K in HCT116 cells via caspase3 and p53 dependent LGR5 inhibition By Ji-Na Pak Department of East-West Medical Science Graduate School of East-West Medical Science, Kyung Hee University Supervised by Prof. Sung-Hoon Kim, K.M.D, Ph.D. Though compound K was known to have antitumor effect in lung, liver, brain, breast and colon cancers, the underlying apoptotic mechanism of ginsenoside metabolite compound K was not fully understood so far. Thus, in the present study, apoptotic mechanism of compound k was explored in HCT116p53+/+ and HCT116p53-/- colorectal cancer cells(CRCs) in association with LGR5 signaling pathway. Here compound K significantly reduced viability of HCT116p53+/+ cells better than that of HCT116p53-/-cells by MTT assay and crystal violet staining. Consistently, compound K increased sub G1 population and attenuated the expression of leucine rich repeat containing G protein-coupled receptor 5 (LGR5), c-Myc, procaspase3, Pin1 in HCT116p53+/+ cells more than in HCT116p53-/- cells. Conversely, caspase 3 inhibitor Z-DEVD-FMK reversed inhibitory effect of compound K on LGR5, c-Myc and procaspase3 in HCT116p53+/+ and HCT116p53-/- cells. Consistently, inhibition of LGR5 using transfection method enhanced suppression of pro-PARP, Bcl-xL c-Myc and Pin1 in compound K treated HCT116p53-/- cells. Furthermore, compound K synergistically potentiated antitumor effect of 5-fluorouracil (5-FU) or Doxorubicin to reduce survival genes and cytotoxicity in HCT116p53-/- cells. Overall, our findings provide scientific insight that compound K induces apoptosis in colon cancer cells via caspase and p53 dependent LGR5 inhibition with potential of combination therapy with 5-FU or doxorubicin. 요 약 HCT116대장암세포에서 카스파제 3과 p53의존성 LGR5저해를 통한 Compound K의 자사멸 효과 박지나 경희대학교 동서의학대학원 지도교수 김성훈 인삼대사체인 compound K는 폐, 간, 뇌, 유방 및 대장암에서 항암효과를 보이는 것이 알려져 있으나, 숨겨진 항암효과기전은 아직도 잘 알려져 있지 않다. 따라서 본 연구에서는 compound K 항암효과 기전을 HCT116p53+/+와 HCT116p53-/- 의 대장암세포에서 규명되었다. 여기서 compound K는 유의한 세포독성억제, sub G1 세포군 증가와 LGR5, c-Myc, procaspase3, Pin1의 발현을 HCT116p53-/- 보다 HCT116p53+/+ 세포에서 억제하였다. 역으로 caspase 3저해제인 Z-DEVD-FMK는 compound K의 LGR5, c-Myc 및 procaspase3 등 억제효과를 감소시켰다. 비슷하게, LGR5저해는 compound K 처리된 HCT116p53-/- 세포에서 pro-PARP, Bcl-xL c-Myc 및 Pin1 등 억제를 촉진시켰다. 더 나아가, compound K는 상승적으로 5-FU나 Doxorubicin의 항암효과를 증가시켰다. 이상의 결과로 보아 compound K 는 대장암에서 카스파제와 p53 의존적으로 LGR5 저해함으로써 자사멸을 유도하고, 5-FU나 doxorubicin과 병용 처리시 상승적 항암효과를 유도할 가능성을 제시한다.

Anti-tumorigenic microorganisms : Anticancer effect on human non-small cell lung cancer A549 cells

Hee-Ju Lee Kyung Hee University Graduate School 2022 국내석사

Abstract Anti-tumorigenic microorganism Kyung Hee University Department of Oriental Medicine Biotechnology Hee-Ju Lee Cancer is a serious disease that is a major threat to human health worldwide. Lung cancer is one of the main causes of cancer-related death, accounting for approximately 25% of cancer mortalities. Lung cancer is divided into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) according to histopathological criteria. NSCLC accounts for approximately 85% of all lung cancers. Chemotherapy for NSCLC varies from patient to patient and generally causes serious side effects including organ damage. Therefore, effective therapy for patients with advanced NSCLC remains lacking. The issues with the current anticancer drugs include high toxicity to normal cells, incapacity to treat deep tumor tissues, and drug resistance of tumor cells. Therefore, the development of new therapeutic agents is required. Microorganisms can produce structurally diverse secondary metabolites, which can be applied to many compounds with high therapeutic potential. We identified Enterococcus faecium LCM001, a microorganism that showed the highest cytotoxicity to A549 cells and low toxicity to human lung fibroblast WI-38 cells among 37 microorganisms, and its active ingredient, Cyclo(L-Pro-L-Tyr) was isolated. Cyclo(L-Pro-L-Tyr) induced cell proliferation inhibition, apoptosis and G2/M cell cycle arrest in A549 cells. Cyclo(L-Pro-L-Tyr) induced apoptosis, as demonstrated by cleavage of PARP and increase of phosphorylated p53. Cyclo(L-Pro-L-Tyr) blocks the PI3K/Akt pathway by inhibiting phosphorylation of epidermal growth factor receptor (EGFR), which is overexpressed and highly mutated in human non-small cell lung cancer. Additionally, inhibition of phosphorylation of human fibroblast growth factor receptor 4 (FGFR4), which is overexpressed in tumors, blocks the PI3K/Akt pathway, suggesting a correlation between the anti-tumor activity. These findings suggest the potential of Cyclo(L-Pro-L-Tyr) as an anti-tumor therapeutic agent for NSCLC by targeting EGFR and FGFR4 and inhibiting PI3K/Akt. Keywords: Anti-tumor, NSCLC, microorganisms, Enterococcus faecium, Cyclo(L-Pro-L-Tyr), EGFR, FGFR4, PI3K, apoptosis, G2/M arrest

A study on hybrid supercapacitors based on binder-free hierarchical nanostructured electrodes with multi-metal oxides/hydroxides

ANKIREDDYMULE Kyung Hee University Graduate School 2023 국내박사

Abstract A study on hybrid supercapacitors based on binder-free hierarchical nanostructured electrodes with multi-metal oxides/hydroxides Mule Anki Reddy Student ID: 2017315488 Department of Electronics and Information Convergence Engineering The Graduate School, Kyung Hee University Advised by Professor Jae Su Yu Emerging new trends in modern consumer electronics have stimulated the researchers to develop alternative, sustainable, economically-viable, and preeminent energy storage techniques to mitigate the reliance on conventional energy resources. Particularly, rechargeable batteries and supercapacitors (SCs) have been garnered a substantial attraction among the developed energy storage technologies. The rechargeable batteries demonstrate high capacity and energy density properties on the point of the Faradaic charge storage technique. Whereas, the SCs exhibit high power density, prolonged lifetime, and prompt energy storage ability due to the surface-controlled reaction mechanism. Though the charge storage mechanism is different in these two energy technologies, some common factors such as electrode material and its contact with the current collector, chemical composition, morphology, and preparation methods perform an active function in their energy storage performance. Especially electrode materials are the main and common factors in attaining the high energy storage performance. Accordingly, the investigation unity has been focusing on the development of versatile electrode materials, including deepened redox performance, high electrochemical conductive nature, great valence states, and good structural stability. Besides the electrode materials, their preparation methods affect the large-scale production and cost of the device fabrication. Therefore, simple and cost-effective preparation methods -need to be developed to ease the abovementioned issues. Employing such simple and economically-viable methods, designing the nanoarchitectures with benefit-enriched characteristics of high surface area, porosity, hierarchical connection, and multi-component configuration would be a promising approach. Considering all the above factors, chapter 3 describes we developed the hierarchical high surface and redox-active amorphous NiMn NSs on crystalline and conductive 1D NiMo NRs using a simple hydrothermal technique. The fabrication and charge storage properties of hybrid supercapacitors are deliberated in brief. To demonstrate the practical applicability, the hybrid HC was built with NiMoNRs@NiMnNSs as positive and activated carbon layered NF (AC@NF) as negative electrodes, respectively. The fabricated hybrid HC device also exhibited more enormous energy storage performance along with well-meaning cycling permanence. Besides, the stable performance of HSC was investigated even under different flexed conditions. Chapter 4 introduces a novel the multi-component like CoFe hydroxides (CFH) nanowire array@ CoNiMn hydroxides (CNMH) nanosheet (NSTs) array on redox-active and conductive Ag-coated NF and CC substrates were developed and employed in SCs. The formation mechanism and effect of each component on electrochemical performance are systematically discussed. Moreover, both fabricated HCs demonstrated excellent electrochemical performance, and their real-time applications were verified by powering different electronic devices with stored solar energy in HCs. Furthermore, practical applications are also demonstrated by harvesting solar energy, thereby switching the electronic components In the process of developing novel materials, Chapter 5 of this thesis introduces the multilayered active materials films coated Nickel foam as a low-cost and highly performance electrode. The hierarchical multilayered (ZNHC@NHC@PEDOT) architectures with versatile morphological structures are developed on NF as binder electrodes. The prepared high electrochemical active (ZNHC@NHC@PEDOT) architectured electrode showed superior energy storage performance and was employed in the fabrication of hybrid HC. The assembled device demonstrated excellent charge storage with high rate capability performance, and practical applicability was verified through its energy storage capabilities. Key words Binder-free, multi-metals, Transition metal oxides/hydroxides, Hybrid supercapacitors

Empowering Korean junior college students through computer-mediated written dialogues

Briggs, Neil Roger Kyung Hee University 2016 국내박사

ABSTRACT Neil Briggs Department of British & American Language and Culture Graduate School of Kyung Hee University Briggs, Neil Roger (2016). Empowering Korean Junior College Students through Computer-Mediated Written Dialogues Informed by Cultural-Historical Activity Theory (Engeström, 1987), this action research study analyzes a native English-speaking teacher’s (NEST) attempt at to engage fifteen limited English proficiency (LEP) Korean college students in an ongoing computer-mediated written dialogue (CMWD) throughout a twelve-week semester. The study seeks to challenge the hegemonic values which commonly overlook the need for teachers to involve their students in the processes of dialogue that are considered by many researchers to be vital to the development of informed and engaging language learning pedagogies (Vygotsky, 1978; Engeström, 1987; Freire, 2000). This study specifically addresses the benefits and challenges associated with working to create the appropriate conditions and social spaces which are required in order for students to become active agents in their language learning classroom. Acknowledged in this study is the fact that NESTs bring to the classroom histories, values, and identities which can be contradictory to those of the students. Accordingly, focus is drawn toward the need for negotiation through student-teacher dialogue as a means of resolving the potentially debilitating tensions that inevitably arise in the classroom (Engeström, 1987). It embraces a constructivist perspective in which the teacher is a co-participant in classroom activity who interacts with the students in order to become informed about their past learning experiences, their linguistic needs, and their individual goal-orientations. In turn, the teacher works to apply this newfound knowledge in order to develop a highly contextualized pedagogy (Lave & Wenger, 1991). The results of this study reveal that the willingness and/or ability of the students to participate in the CMWD varied. Based on their participation rates, the students are assigned to one of three groupings; Active Participation (AP), Moderate Participation (MP), and Limited Participation (LP). An analysis of these groupings reveals that student participation in the CMWD was mediated by the existence of communicative English language learning goal orientations, self-regulating skills, and a willingness to detach from historical language learning experiences which were revealed to be, in most cases, non-communicative in nature. Finally, the learning outcomes of the teacher are revealed in order to illustrate the ways in which student voice can help to inform and facilitate the processes of praxis.

Studies on Heavy Metal Contents in Natural and Civic Wild Plants of Korea

최한수 Kyung Hee University 2001 국내박사

식물에게 흡수된 중금속은 식물 자체의 생육에 큰 피해를 줄뿐만 아니라, 식물체를 소비하는 생물체 내에 축적되어 악영향을 주는 경우가 많다. 최근에 광공업의 폐기물에 의한 토양, 작물 계의 중금속 오염은 농작물의 생육이나 인축에 미치는 영향이 더욱 심각하다고 알려져 있다. 이렇듯 점차 중금속 오염이 심각해지고 있는 상태에서 우리 나라에서는 오염지역을 중심으로 한 오염도가 측정되어 보고되고 있으나, 자연적으로 식물체내에 함유하는 중금속에 관한 기초 연구는 보고된 바가 적어 중금속 오염도를 비교 분석할 자료가 드문 현실이다. 중금속 오염여부를 판단하기 위해서는 식물체의 중금속 자연함유량에 대한 조사가 기본적으로 잘 이루어져야만 그 진행정도를 파악할 수 있다. 따라서 본 연구는 인위적인 요인에 의하여 발생되는 중금속오염에 대한 연구의 일환으로서, 생태계를 순환하는 중금속의 전이 모형을 이해하기 위하여 선행되어야할 필요가 있는 자연환경 내에서의 식물 중금속 함량에 관한 조사이다. 상기한 중금속 오염의 피해와 차후 발생될 중금속 오염을 방지하기 위한 대책으로 인위적인 중금속오염이 없는 지역으로 판단되는 경기도 광덕산, 강원도 오대산, 제주도 한라산 및 강화도 동만도에 자생하고 있는 식물체를 대상으로 식물체에 함유된 8종류의 중금속 함량을 조사하고 식물체내의 중금속 전이 및 농축에 대한 기초자료를 마련하고자 하였으며, 서울시에 자생하고 있는 식물체를 대상으로 그 오염도를 파악해 비교 분석해 보았다. 청정지역에서 채집한 식물체의 중금속 함유량은 A1은 0.519-921.4ppm, Assms N.D.-4.180ppm, Cd는 N.D-0.313ppm, Cr은 0.001-3.007ppm, Cu는 N.D.-1.997ppm, Fe는 0.0363-216.700ppm, Pb는 N.D.-2.660ppm 및 Zn은 0.002-86.400ppm으로 나타났으며, 오염지역과 비교해 보면 유의한 차이를 보인다. 목본과 초본 식물의 중금속 함량을 비교해 본 결과 대체적으로 초본이 중금속을 더 많이 함유하고 있는 경향을 보였다. 초본의 경우 지상부 보다는 지하부에 더 많이 중금속을 축적하며, 목본의 경우 줄기보다는 잎에 더 많은 중금속을 축적하는 경향이 있으나, 중금속의 종류에 따라 다양한 차이를 보였다. 식물체의 종별 차이도 나타났으나 명확한 종간 차이는 나타나지 않았다. 생중량, 엽록소함량, 건중량 및 함수량과 상관관계도 종별 중금속별로 다양한 현상을 나타내고 있으며, 함수량과 밀접한 관계를 나타내는 경향이 보이며, 각 중금속간의 흡수량에 따른 상관 관계는 종마다 특이하게 나타났다. 오염지역에서 채집한 식물체는 청정지역에서 채집한 식물체에 비하여 통계적으로 유의한 차이를 보니는 정도로 중금속을 더 함유하고 있으며, 지역별 비교에서 교통량에 따른 차이에 대하여 중금속 함율양이 비례하는 경향을 보여, 주위에 특정 오염원이 없는 경우에도 도심에서는 청정지역에 비하여 더 많은 중금속을 식물체가 함유하고 있으며, 이는 자동차 운행에 따른 대기 오염 유발로 토양을 산성화 시켜 토양내의 중금속 활성을 높인 결과로 추측되어진다. The heavy metal contamination of plants has been interesting topic because plants are primary producer and food for higher animals, also the contamination can be extended into whole ecosystem through food chains. The absorbed heavy metals in plants not only damage growth of plants but also cause bad effects on organisms that consume the plants. Recently, it has been known that the heavy metal contamination of soil-crops system occurred by mine industrial waste generates more serious effects on growth of agricultural crops and poultry in Korea(Lee et al., 1994). Thus, it is apparent that heavy metal contamination in Korea is becoming serious and the contamination degree of contaminated areas has been measured and reported. However, the basic study of heavy metals in plants is rare, although Lee et al.(1994) reported the study of natural background contents of wild plants. Therefore, the data t hat compare and analyze the contamination degree has been lacked. In order to judge the presence of the heavy metal contamination, the study about t he natural amount of the metals in plants is required. Thus, in this research, heavy metal content of plants in natural environment has been studied because it is necessary to understand the metal contamination caused by artificial factors and the transfer model of heavy metals that circulating ecosystem. In this paper, I studied content of heavy metals in different plant species that habitat in several areas as one of the contributing methods to prevent above escribed damages and possible future damages, also providing basic data of transfer and accumulation of heavy metals in plants. As a part of a countermeasure to protect from the pollution damage of heavy metals which above mentioned and the damage which will be happened. We investigated contents of 8 kinds heavy metal in plants which were collected in four areas where were judged a purity area, and we also tried to prepare basis materials for the transfer and concentration in plants. We grasped the degree of pollution in plants of Seoul, then studied a comparative analysis. The contents of heavy metal which were collected in purity were 0.519~921.400ppm of Al, 0 4.180ppm of As, 00.313ppm of Cd, 0.010 3.007ppm of Cr, 0 1.997ppm of Cu, 0.036 216.700ppm of Fe, 0 2.660 ppm of Pb and 0.002 ~ 86.400ppm of Zn. It was significantly different to compare with the pollution area. In a result of compare the heavy metal content s between trees and herbs, it was showed a tendency which herbs contained more heavy metals than trees generally. In a case of herb, roots contained more contents of heavy metal than shoots. In a case of tree, leaves contained more contents of heavy metal than stems. But there were variety differences according to heavy metals. There was different contents of each species in plants, but it was not clear. Also t here was variety appearances of correlation in fresh weight , chlorophyll content, dry weight and water content each species and heavy metal. The relation with water content closed specially. The correlation of each heavy metal contents were singular each species. Plants of pollution area contained more contents of heavy metal which was significantly different in statistically than plants of purity area. In compare of each area, it indicated a tendency the metal content was proportioned wit h traffic density. Even if there were not a source of pollution, there was more contents of heavy metal in plant of the center of metropolis compare with purity area. We suppose it was a result from increasing activity of heavy metal in soil by acid reaction which from air pollution by vehicles movement. We also presented 11 kinds heavy metal accumulation plant which can study later.

The Influence of SNS Characteristics on Travel Decision among Chinese SNS Users

Feng Han Kyung Hee University Graduate School 2016 국내석사

There has been rapid growth in the world of social networking service (as known as “SNS”). SNS is a popular and important channel for people to communicate in an easier and more convenient way with each other. Because it’s used widely and popular, SNSs, especially Weibo and WeChat in China, have become one of the most important and efficient ways for marketers to attract individuals’ attention and have an effective marketing, particularly in tourism industry. This study involves Chinese tourists’ travel decision making influenced by SNS characteristics; its purpose to make contributions to tourism marketing and travel decision research. Information quality, system quality, timing, reciprocal communication and value are five variables for analyzing SNS characteristics. Three factors, consisting of tourists’ perceived ease of use (PEOU), perceived usefulness (PU) and satisfaction toward SNS using, are used as mediators between SNS characteristics and travel decision making. This study makes an integrated research model from TAM model, D & M IS success model and extended D & M Model to analyze the influence from SNS characteristics, PEOU, PU and satisfaction to travel decision. For the purpose of the research, 302 valid survey responses were collected online by targeting Chinese tourists using Weibo and WeChat. Frequency analysis was conducted to examine the answers’ demographic and the general characteristics. Reliability and an exploratory factor analysis (EFA) was carried out to confirm the reliability of measurement items by SPSS 22.0 and a Confirmatory Factor Analysis (CFA) was utilized to assess the construct validity by AMOS 21.0. Regression analysis was carried out to test the structure relationships among the latent constructs in order to test the hypothesis. The study results show that the new combined research model has a good model fit for analyzing SNS characteristics, PEOU, PU, satisfaction and travel decision. All eight hypotheses proposed in this study were revealed to be supported by the empirical results. SNS characteristics have positive significant influence on travel decision making. What’s more, PEOU, PU and satisfaction have positive mediating effects between SNS characteristics and travel decision, except that PEOU does not have mediated effect between reciprocal communication, value and travel decision. The most important influential factor to travel decision is satisfaction, following by PU. SNS characteristics influence satisfaction strongly, and influence more on PU than PEOU; in addition, PU has stronger influence on satisfaction than PEOU. Regression results also show that tourists consider PU more influential than PEOU. Overall, this research validated the influences of SNS characteristics to travel decision with the mediating effect of PEOU, PU and satisfaction. The findings of this research could be helpful for future researchers, educators and marketers involved in the field of tourism and SNS.

Anti-inflammatory and matrix-protective effects of ergostenol compounds in cell culture models of arthritis

박유진 Kyung Hee University 2018 국내석사

Anti-inflammatory and matrix-protective effects of Ergostenol compounds in cell culture models of arthritis By Yujin Park Master of Science Department of Gerontology Graduate School of East-West Medical Science Kyung Hee University Advised by Eun Joo Hwang, Ph.D. Arthritis is inflammation of joint. Representative types of arthritis include osteoarthritis (degenerative arthritis) and rheumatoid arthritis. Both types are accompanied by an inflammatory reaction. Pro-inflammatory factors affect the cartilage and synovium that make up the joint. This leads to cartilage erosion and synovial inflammation. Fibroblast-like synoviocytes (FLS) are present in the synovial membrane and serve to maintain joint homeostasis. Activation of FLS promotes inflammation, damages cartilage, and leads to joint destruction. FLS also secretes matrix metalloproteinases (MMPs) that degrade extracellular matrix, and inflammatory molecules. Human chondrocytes (HC) are derived from the cartilage of the joints and play a role in maintaining the cartilage matrix. HC respond to inflammatory stimuli and produce MMPs. Thus, improving the inflammatory environment in joint can alleviate the symptoms of arthritis. In this study, I investigated the effects of Ergostenol compounds, which are synthetic compounds, on inflammatory mediators, MMPs and Collagen type Ⅱ (COL2A1) in cell culture models of arthritis. First, I examined cell viability to see if Ergostenol compounds are cytotoxic to FLS and HC. The highest safe concentration of both types of cells was 10 μM. After treatment of each cell with tumor necrosis factor alpha (TNF-α), I examined the effects of Ergostenol compounds on inflammation-related genes, MMPs and COL2A1 by RT-PCR and Western blot. In general, β-galactosyl ergostenol significantly inhibited the expression of TNF-α-induced pro-inflammatory genes and MMPs in each cell types. It also increased the expression of COL2A1. Thus, these data demonstrate the anti-inflammatory and matrix-protective effects of β-galactosyl ergostenol in cell culture models of arthritis.

Energy beamforming for wireless powered communication with practical energy harvesting

Cantos Sanchez, Luiggi Renato Kyung Hee University 2020 국내석사

This thesis aims to maximize the minimum rate in a Wireless Powered Communication Network system by considering practical non-linear energy harvesting (NLEH) users, where a multi-antenna hybrid access point transfers the power to the devices via energy beamforming (BF) which then send their data simultaneously to the HAP by consuming the harvested energy. For the NLEH model we based on a sigmoid function with sensitivity, we tackle our max-min optimization problem into two steps; rst and the main challenging problem, the energy optimization BF problem to then proceed to the convex time allocation problem. We propose two iterative methods to solve the non-convex energy BF problem with NLEH function and it Piece-wise linear approximation. In addition, we present an asymptotic energy BF problem for a large-antenna system being this a convex optimization problem and solved fast and at a lower complexity. Simulation results show that the optimization algorithms with a simple Piece-wise linear with sensitivity approximation provide almost the same performance compared with those where the exact NLEH function was consider. It is also observed that the sensitivity region of the NLEH should be more precisely consider than the saturation region in the max-min rate optimization problem.

Resource Allocation for Cooperative and Wireless Powered Communication Networks

Thinh Phu Do Kyung Hee University 2016 국내박사

A new paradigm in communications referred to as Internet of Things (IoT) has emerged to connect everything including devices, humans, environments, processors, and data for autonomous transmission of sensed data and control information. Various IoT services are now being emerging to realize smart homes and cities as well as to reduce the cost in business so that the number of IoT devices are expected to increase up to 50 billions by 2030. In supporting such various IoT services, wireless communications should be reshaped and redesigned to satisfy diverse requirements such as low-latency and high reliability for critical communications, large coverage and massive connectivity for scattered sensing devices, energy efficiency for battery life extension for embedded devices. This thesis envisages cooperative communications and wireless powered communications as enabling technologies meeting such IoT requirements as high reliability at the extended coverage, energy efficiency, and battery life extension. Cooperative communications exploit neighboring nodes to create diversity channels robust to fading as well as to replace a long-distant channel by multiple short-distant channels for the significant reduction in a propagation loss. Wireless powered communications charge the devices through radio-frequency signals remotely to extend their battery lifetime before communications, which avoids frequent replacements of devices placed in the hazardous and vast areas. On the other hand, the coexistence of overwhelmingly massive devices motivates a more efficient utilization of limited wireless resources in time, power, and frequency. It is thus necessary to design efficient resource allocation algorithms to boost the overall system performance. In this thesis, we tackle several resource allocation problems for cooperative communications and wireless powered communications systems to meet the quality-of-services. We begin with optimizing a multi-hop one-way relaying network to support a long range transmission from a source node to a destination node with the help of relay nodes. For the network, we develop several optimization schemes in power allocation (PA) and relay position (RP) to minimize the outage probability in a generalized fading channel models. The analysis on the optimization schemes reveal that the optimization of PA improves only the coding gain while the optimization of RP improves not only the coding gain but also the diversity order. In addition, the joint optimization of PA and RP leads to a significant improvement in the overall outage performance. Next, resource allocation problems are studied for a two-way relaying (TWR) network which adopts physical layer network coding for efficient spectrum utilization. The TWR network allows two source nodes to exchange their information with the help of a relay node in two time slots rather than in four time slots required for conventional OWR. We attempt to optimize PA and time allocation (TA) in two time slots in a way of minimizing the outage probability in supporting asymmetric rates of the two sources. The analysis shows that the optimizing PA is beneficial for any rate configuration while the optimizing TA is beneficial for highly asymmetric rate transmission. We then introduce wireless power communication into the TWR network such that the relay not only decodes the information but also harvests the energy from the signal transmitted by the sources in the first slot. To realize both information transmission and energy harvesting at relay, we adopt two common energy harvesting architectures of power splitting (PS) and time switching (TS) in simultaneous wireless information and power transfer (SWIPT). For each architecture, we design a resource allocation of optimizing the PS ratio for the PS-SWIPT and the TS ratio for the TS-SWIPT as well as optimizing the TA of the two time phases of the TWR network. Finally, we investigate a full-duplex wireless powered communication network such that a hybrid access point charges the devices in the downlink while the devices utilize the harvested energy to transmit their signal in the uplink. For the network, we design a resource allocation of PA for the downlink wireless power transfer and TA for both the downlink wireless power transfer and the uplink information transfer to maximize the system sum throughput. Although the conventional study ignores the self-interference in full-duplex mode, we assume imperfect self-interference cancelation in resource allocation with energy causality which is a more practical scenario. The problem is highly non-convex but is approximated to a second-order cone problem for the fast and reliable computation

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Han, Kyung Hack Kyung Hee University 1982 국내석사