User motivation and expectation for asking a question in online Q&A services

Choi, Erik ProQuest LLC UMI Dissertation Publishing 2015 국내박사

Communicating social support in smartphone-based addiction support groups : seeking, giving, and receiving emotional support and their effects on alcoholism treatment

유우현 ProQuest LLC UMI Dissertation Publishing 2014 국내박사

(The) effects of status and power on leadership emergence and conflict in teams : from a structural perspective

Park, Jinsung ProQuest LLC 2018 국내박사

(The) impact of individual's beliefs on overcoming temptations

Park, Suhean ProQuest LLC 2016 국내박사

Verbs of active visual perception in English

Nazia Shah 韓國外國語大學校 大學院 2021 국내석사

본 연구의 목적은 영어의 능동적 시지각 동사를 분석하는 것이다. 구체적으로는 능동적 시지각 동사들을 서로 다른 의미-통사적 유형에 기초하여 두 그룹으로 분류하고, 영어 FrameNet에 제시된 능동적 지각 틀(PERCEPTION-ACTIVE FRAME)을 두 개의 하위 틀로 분할하는 것을 목적으로 한다. 능동적 지각 틀을 분할하는 주된 동기는 틀요소 방향성(Direction)이다. 따라서 경로 표현에 초점을 맞춰 유의어에 가까운 동사들이 왜 서로 다른 통사적 구성을 갖는지를 탐구한다. 통사적 유형 분포에서의 이러한 차이는 의미적 차이를 반영하는 것이고, look 계열의 동사들은 항상 시선의 방향을 표현하는 반면 watch 계열의 동사들은 방향성의 요소를 표현하지 않는 경향이 있다는 것을 나타낸다. 본 연구에서는 watch 계열의 동사는 look 계열의 동사들이 공기할 수 있는 경로 표현들의 일부와만 공기할 수 있음을 밝힌다. 능동적 시지각 동사의 이러한 특성에 근거하여 능동적 지각 틀을 유방향 능동적 지각(PERCEPTION-ACTIVE-DIRECTED)과 무방향 능동적 지각(PERCEPTION-ACTIVE-UNDIRECTED)의 하위틀로 분할한다.

Energy Recycling Techniques for Ultra-Low Power Dynamic Voltage Scaler Circuits

Syed Asmat Ali Shah 충북대학교 전자공학전공 2020 국내박사

Design and comparative analysis of single and multi-stack axial flux permanent magnet synchronous generator

Syed, Qurban Ali Shah 한양대학교 대학원 2012 국내석사

Design and Comparative Analysis of Single and Multi-stack Axial Flux Permanent Magnet Synchronous Generator Syed Qurban Ali Shah Advisor: Prof. Byung-il Kwon Department of Electronics, Electrical, Control and Instrumentation Engineering Graduate School of Engineering Hanyang University South Korea This paper attempts to design a direct-driven axial flux permanent magnet synchronous generator (AFPMSG) with better design accuracy considering magnetic flux leakages and fringing effect, using D²L design process. Design results of conventional and improved design process are analyzed and compared using 3-D finite element method (FEM). Improved design process shows better accuracy results than the conventional one. Improved design process is utilized to design single and multi-stack AFPMSG topologies. FEM structural analysis is utilized to decrease the intermediate rotor yoke thickness as to improve the output power to weight and output power to volume ratio of three-stack AFPMSG. Finally, characteristics of both single-stack and best model of three-stack AFPMSG topologies are analyzed and compared using 3-D FEM. Although single-stack AFPMSG has less weight and volume and higher power density, its output power depends on its outer rotor diameter. Whereas, three-stack AFPMSG has smaller outer rotor diameter and lower rotor inertia, but it is more costly due to its higher weight and volume and lower power density.

VLS growth of Ni catalyzed Si1-xGex nanowires

Shah, Aqeel Ahmed 한양대학교 대학원 2010 국내석사

One of the most attractive techniques to fabricate semiconducting nanowires is by the Vapor Liquid Solid method (VLS). By means of this Si1-xGex nanowireswere gently grown axially with change in their compositions with a SiCl4: GeCl4 ratio of 2:8, 3:7, 4:6, 5:5, 8:2, 7:3 and 6:4 respectively. The growth was carried out for different times and different temperatures including 1000 oC, 950 oC, 900 oC and 850 oC. It was found that the nanowires were grown successfully vertical on almost all temperatures except at 900 oC and 850 oC, some of the wires were observed as bearing flower like structure. The wires were characterized by high resolution scanning electron microscopy (SEM), high resolution transmission electron microscopy (FESTEM) with EDS facility. It was observed that wires can be grown successfully vertical by changing the inlet flow ratio of precursors and at different temperatures. The wires with equal ratio of precursors, high ratio of SiCl4 and low of GeCl4 and low ratio of SiCl4 and high of GeCl4, were observed under STEM with EDS facility. It was revealed that at high inlet and low input of SiCl4 and GeCl4 respectively, the wire was rich with Si and containing less amount of Ge and vice versa. At an equal ratio of precursors flow, the EDS showed that tip and neck of the wire was rich with germanium while rest of the body was rich with Si.

Poria cocos Ethanol Extract Enhances Pentobarbital- Induced Sleeping Behaviors via GABAA-ergic Systems : 복령 추출물의 GABAA-ergic 시스템을 통한 Pentobarbital 유도 수면 증가 효과

Shah Vikash Kumar 충북대학교 2014 국내석사

불면증의 효과적인 치료를 위한 다양한 약물학적 시도를 수행하고 있다. 복령은 pachymic acid (PA)를 주성분으로 수면유도 효과가 있으며 pentobarbital 유도 수면 행동을 증가시킨다. 복령 추출물 및 PA 를 경구투여하고 자발운동을 억제하는데 이는 GABA 수용체에서의 benzodiazepine 결합부위에 관한 상호작용과 관련이 있다는 것을 추정하였다. 이는 중추에서 pentobarbital 과 GABA system 을 통한 작용으로 생각된다. 또한 복령 추출물과 PA 는 1 차 배양 시상하부 신경세포에서 세포 내 연소이온을 증가시켰다. 복령추출물이나 PA 가 GABA 의 생합성을 통하여 GABA 수용체를 활성화 활 수 있다. 따라서, 복령추출물과 PA 가 GAD 의 활성을 신경세포에 8 일간 배양하여 측정한 결과 GAD 를 증가시키는 것을 확인하였다. 더 나아가, GABAA 수용체의 아형 (알파, 베타, 감마)의 과발현을 조사하였으며, 이들 알파 및 감마 아형은 아형의 단백질이 과발현하였으며, 감바는 다소 억제되었다. 이와 같은 결과를 바탕으로 복령 추출물과 PA 는 GABA 수용체 및 염소이온의 세포내 증가로 인한 억제성을 증가로 수면을 유도하는 것으로 사료된다. Poria cocos (Hoelen), a Chinese herbal medicine (CHM) has been commonly used for treating insomnia in Asian countries for centuries. However, its claimed benefits and mechanism are not fully understood. The present study aimed to investigate whether the herb ethanol extract (PCE) and its active constituent pachymic acid (PA), possesses hypnotic effects and/or enhances pentobarbital-induced sleeping behaviors. In addition, the mediation of γ-aminobutyric acid (GABA)-ergic systems were defined to understand the possible mechanism. Oral administration of PCE and PA inhibited the locomotion activity in mice. Moreover, both the samples prolonged pentobarbital-induced sleep time, and shorten sleep latency at the hypnotic (40 mg/kg) dose of pentobarbital in mice. Interestingly, it was observed that both PCE and PA increased the number of sleeping mice and total sleeping times, showing synergistic effects similar to muscimol (0.2 mg/kg) at the sub-hypnotic (28 mg/kg) dose of pentobarbital in experimental animals. Notably, the extract and PA raised intracellular chloride levels in primary cultured hypothalamic neuronal cells. PCE and PA increased glutamic acid decarboxylase (GAD65/67) protein levels by western blot. Furthermore, α-, β-, and γ-subunits of GABAA receptors were remarkably over-expressed by PCE treatment. However, the expression studies showed that α-, and β-subunits were remarkably increased by PA, but decreased γ-subunit protein levels in GABAA receptors. To sum up, the data suggest that the herb ethanol extract and its major constituent PA may be useful for the treatment of insomnia via GABAA-ergic mechanisms.

SWIPT in energy constrained relay networks

Shah, Syed Tariq Sungkyunkwan University 2018 국내박사

Wireless energy harvesting is an efficient way to prolong the lifetime of energy constrained wireless networks. Since the radio frequency signals can simultaneously carry both energy and information, they can be utilized to transfer information and power-up the energy constrained nodes in the network. In this dissertation, we propose and study the performance of energy harvesting based relay networks, where the communicating nodes concurrently transmit their information signals to a relay node. The relay node is assumed to be an energy constrained node, and therefore it first harvests energy from the received signals. Then using the harvested energy, the relay node forwards the information signals to its corresponding destination. More specifically, the performance of three different network models, namely, point-to-point, multi-point-to-multi-point, and point-to-point cognitive networks are proposed and studied. For energy harvesting at a relay node, we analyze the performance of different energy harvesting protocols, i.e., the time switching based relaying protocol (TSR), power splitting protocol (PSR), and the hybrid power-time switching based relaying protocol (HPTSR). Once the energy is harvested using one of these protocols, the relay then forwards the received information signal towards its destination. For information processing at the relay node, we have proposed and analyzed the performance of three different relays, i.e., (i) amplify-and-forward (AF) relay, (ii) multiplicative relay, and (iii) decode-and-forward (DF) relay. For AF based relay networks, we derive the analytical expressions for the outage probability and achievable throughput for the aforementioned protocols. Our numerical results verify the analytical derivation and show the effect of different system parameters on achievable throughput at the destination. It is concluded, that for the considered two-way AF relay network, at high SNR and low transmission rate, HPTSR protocol outperforms TSR and PSR protocols. On the other hand, at low SNR and high transmission rates, TSR protocol outperforms the other two protocols. Furthermore, we have also proposed and studied a novel multiplicative relaying scheme for energy harvesting based two-way relay networks. With the help of numerical results, we show that in an energy constrained two-way relay network, the proposed multiplicative relay scheme can achieve higher throughputs than AF relay scheme. In addition to point-to-point relay network, we also study a multi-point-to-multi-point relay network, where multiple source nodes communicate with their respective destination nodes via an intermediate energy constrained DF relay. Based on PSR, the relay node first harvests the energy from all received source signals which is then optimally distributed among all possible destination nodes using a geometric water-filling technique. The decision on what portion of received signal power should be used for energy harvesting is dynamically decided based on two factors: (i) the power level of the received signal at relay node and (ii) the availability of transmit power for that particular signal, in order to forward it to its corresponding destination. Based on the proposed energy harvesting and power distribution mechanisms, four different relaying strategies are designed and studied. Our numerical results provide useful insights into different system parameters of an energy harvesting-based multi-pair DF-relay network. Our results also show that, compared to equal power distribution (EPD) schemes, our proposed optimal scheme can significantly improve the overall system sum-rate. To further enlarge the scope of this dissertation, an ambient backscatter-enabled DF cognitive relay network with wireless energy harvesting capabilities is also proposed. In the proposed scheme, a source node communicates with its destination node via a radio frequency-powered DF relay. The relay node is assumed to be equipped with two different interfaces and can concurrently harvest/decode and backscatter the received source signals. A power-splitting-based approach is adopted for information processing and energy harvesting at the relay. The analytical expressions for throughput and outage probability at all receiving nodes are derived. We show that our analytical results exactly match our simulation results. Our results also show that using the ambient backscatter for secondary communications can significantly improve the overall network performance in terms of achievable throughput and energy efficiency.