Furfural synthesis from xylose under biphasic system

VO THI HOANG ANH University of Science and Technology 2017 국내석사

As an attempt to replacing petroleum-based chemicals with bio-based ones, synthesis of furfural from biomass-derived xylose attracts much attention in recent days. Conventionally, furfural from xylose has been produced via the utilization of highly corrosive, toxic, and environmentally unfriendly mineral acids such as sulfuric acid or hydrochloric acid. In this study, microwave-assisted biphasic reaction process in the presence of novel bio-based heterogeneous acid catalysts was developed for the eco-benign and effective synthesis of furfural from xylose. The microwave was irradiated for reaction acceleration and a biphasic system consisting of H2O:MIBK (1:2) was designed for continuous extraction of furfural into the organic phase in order to reduce the undesired side products formed by decomposition/condensation/oligomerization in the acidic aqueous phase. Moreover, sulfonated amorphous carbonaceous materials were prepared from wood powder, the most abundant lignocellulosic biomass. The prepared catalysts were characterized by FT-IR, XPS, BET, elemental analysis and they were used as bio-based heterogeneous acid catalysts for the dehydration of xylose into furfural more effectively. For further optimization, the effect of temperature, reaction time, water/organic solvent ratio, and substrate/catalyst ratio on the xylose conversion and furfural yield were investigated and 100% conversion of xylose and 74% yield of furfural was achieved within 5 h at 180 ºC. The bio-based heterogeneous acid catalysts could be used three times without any significant loss of activity. This greener protocol provides highly selective conversion of xylose to furfural as well as facile isolation of product and bio-based heterogeneous acid catalysts can alternate the environmentally-burdened mineral acids.

계획된 행동이론을 활용한 베트남 식당 예약 애플리케이션에 관한 연구

NGUYEN HOANG ANH 세종대학교 대학원 2024 국내석사

Abstract A Study on Vietnamese Restaurant Reservation Application Using Theory of Planned Behavior Nguyen Hoang Anh Department of Culinary and food service management The Graduate School Sejong University When the covid-19 epidemic occurred, it caused many crises in all aspects of society globally. The recovery of the economy in general and the hotel, restaurant and tourism service industry in particular is a big challenge. Changing the way of operating is necessary to create newness to attract customers' return and is considered one of the marketing strategies. Booking a table at a restaurant is not a new thing, but the method needs to be improved. Since then, restaurant table booking applications in Vietnam have been born and brought into the market. However, the use of restaurant reservation applications is only really popular in big cities. This study was conducted to evaluate user awareness of restaurant table reservation applications in Vietnam. The study was conducted on people currently living in Vietnam for 1 month and a total of 630 copies were obtained. Research results were performed using SPSS software. The results show that perceived usefulness, perceived ease of use and information quality of the restaurant reservation application have a positive impact on users' usage attitude. In addition, usage attitudes, subjective norms, and perceived behavioral control have a positive impact on users' intention to use. This study will be a premise for future studies aimed at more in-depth evaluation of other aspects of a mobile application or social influences on users' intention to use. user. Keywords: restaurant reservation application, perceived usefulness, perceived ease of use, information quality, theory of planned behavior (TPB).

FACTORS AFFECTING THE PASSENGER BEHAVIOR INTENTION TOWARDS THE AIRPORT SELF-SERVICE TECHNOLOGY

TRAN MINH ANH 한국항공대학교 일반대학원 2023 국내석사

Factors affecting the passenger behavior intention towards the airport self-service technology Tran Minh Anh Aviation Management Program The Graduate School Korea Aerospace University (Advisor: Professor Jin Ki Kim, Ph.D.) Airport self-service technology (ASST) have received considerable attention over the last few years as they offer potential savings and efficiency gains for airports and airlines alike; however, little is known about factors affecting to passenger’s behavior intention toward self-service technologies. This study proposes a model to find out what and how much do factors affect to the passenger’s behavior intention toward self-service technologies (SST). In the model, there are five independent constructs: Perceived Ease of Use, Perceived Usefulness, Perceived Enjoyment, Social Influence, Perceived Risk; and one Dependent construct: Behavior Intention. Based on 190 observations from airport users, the study identifies that Perceived Ease of Use, Perceived Usefulness, Social Influence, Perceived Risk have impact on Behavior Intention; amongst them, Social Influence has the greatest effect. Keyword: Airport self-service technology; SST; Behavior Intention.

퍼지논리를 사용한 로봇 매니퓰래이터 제어기의 적응식 PID 게인 조율 방법에 대한 연구

Tran Anh Dung 한국산업기술대학교 일반대학원 2019 국내석사

ABSTRACT Adaptive PID Gain Tuning Using Fuzzy Logic For Robot Manipulator. by Tran Anh Dung Advisor Prof. Shin Hyeong-ceol, Ph.D Department of Mechanical Engineering. General Graduate School, Korea Polytechnic University The most popularly used form of industrial controllers is Proportional-Integral-Derivative (PID) controller. Nowadays, more than 90% of controllers used in industries are PID or type of PID controller. Because PID controller has simple structure and powerful performance. Though, fixed PID gain do not work well for nonlinear processes or are unable to compensate for disturbances. To address this weakness, many methods for tuning PID gain have been suggested. There is much to gain, if these methods are carried forward to fuzzy logic. In this thesis, a fuzzy adaptive PID gain is proposed for robot manipulators. This method may dynamically adjust proportional coefficient Kp, integral coefficient Ki and derivative coefficient Kd of PID controller by using fuzzy algorithm. The proposed controller has been successfully applied to control SCARA manipulator using Matlab. In this simulation, the external disturbance is addressed. The simulation results have shown that the tracking performance of the fuzzy adaptive PID gain is quite good and more robust and adaptable than traditional PID controller 국문요약 퍼지논리를 사용한 로봇 매니퓰래이터 제어기의 적응식 PID 게인 조율 방법에 대한 연구 한국산업기술대학교 일반대학원 기계공학과: 짠아잉쭝 지도교수: 신 형 철 산업용 컨트롤러 중 가장 보편적으로 사용되는 형태는 PID (Proportional-Integral-Derivative) 컨트롤러입니다. 요즘, 산업계에서 사용되는 컨트롤러의 90 % 이상이 PID 또는 PID 컨트롤러 유형입니다. PID 컨트롤러는 간단한 구조와 강력한 성능을 제공하기 때문에 그러나 고정 PID 게인은 비선형 프로세스에서 잘 작동하지 않거나 장애를 보상 할 수 없습니다. 이러한 약점을 해결하기 위해 PID 이득을 조정하는 많은 방법이 제안되었습니다. 이러한 방법이 퍼지 논리로 이어진다면 얻을 수있는 것이 많습니다. 본 논문에서는 로봇 매니퓰레이터에 대해 퍼지 적응 형 PID 이득을 제안한다. 이 방법은 퍼지 알고리즘을 사용하여 PID 제어기의 비례 계수 Kp, 적분 계수 Ki 및 미분 계수 Kd를 동적으로 조정할 수 있습니다. 제안 된 컨트롤러는 Matlab을 사용하여 SCARA 조작기를 제어하는 데 성공적으로 적용되었습니다. 이 시뮬레이션에서 외란이 해결되었습니다. 시뮬레이션 결과는 퍼지 적응 형 PID 이득의 추적 성능이 기존의 PID 제어기보다 상당히 좋고 견고하고 적응력이 있음을 보여주었습니다.

Collision-free Formation Control of Multiple Nano-quadrotors

Nguyen Anh Tung 세종대학교 대학원 2021 국내석사

Multi-agent systems have gained massive popularity among recent fascinating research topics with a view to performing large-scale interconnected systems in a colossal number of real-world applications. This thesis presents the development and implementation of formation control utilized to manage multiple nano-quadrotor systems. The aim of this work is to develop a theoretical framework for the time-varying formation flight of the multi-quadrotor system with consideration to anti-collisions. In order to achieve this goal, finite cut-off potential functions are devoted to avoiding the occurrence of collisions among agents in the group as well as between an agent and an obstacle/adversary. Then, in light of Lyapunov's direct method, the control algorithm navigates the group of quadrotors to asymptotically reach an anticipated time-varying formation. The validity and effectiveness of the proposed approach are demonstrated via numerical results and several experimental scenarios. Two case studies corresponding to available laboratory equipment are employed to show powerful demonstrations of the proposed algorithm. With hopes of performing actual tests, this thesis provides the implementation of techniques utilized to operate Crazyflies nano-quadrotors, one of the most popular indoor practical platforms.

A Decentralized Resource Allocation for Small Cells in Heterogeneous Networks

LE ANH TUAN 경희대학교 대학원 2017 국내박사

Small cell networks are envisioned as a promising solution to enhance the capacity and coverage for indoor and cell edge users with less capital expenditure and maintenance cost in the heterogeneous networks (HetNets). To reap the benefits of small cell network deployment, we target optimization-based approaches to employ the resource allocation problems for small cells with various enabling technologies in the future wireless network. Accordingly, the overall small cell network is modeled by an optimization problem. This problem integrates multiple constraints such as transmit powers, backhaul link capacities, radio resources, interference management, and the users' quality of service (QoS) demands into a unified optimization problem. To solve this problem, we exploit the frameworks of the coalitional game, matching theory, and optimization theory to find sub-optimal solutions in a decentralized manner. In this thesis, we particularly investigate two optimization problems for resource allocation in small cells with the cognitive radio and wireless virtualization technologies. These technologies are identified as some of the key emerging technologies for future wireless networks. At first, we consider a resource allocation in the uplink of the cognitive femtocell network (CFN). The goal is to maximize the uplink sum-rate under constraints of intra-tier and inter-tier interference while maintaining the average delay requirement for femtocell users and protecting the macrocell base station. In the solution section, we aim at developing distributed algorithms in which the CFN implementation is self-organized and self-optimized. To this end, we first propose an autonomous framework, in which the femtocell users self-organize into disjoint groups (DJGs). Then, we examine the coalitional game aspects of the subchannel and power allocations in each DJG. We show that the optimization problem can be formulated as a coalitional game in partition form. This game captures realistic inter-coalition effects that are formed by players who are seeking to cooperate and to form coalitions. By using the recursive core method and optimization theory, we develop a distributed algorithm for the power and channel allocations. We prove that the proposed algorithm always converges to a Nash-stable partition. Then, we study resource allocation for small cell networks with the wireless virtualization considering both the backhaul capacity of the infrastructure provider (InP) and the users' QoS requirements. The optimization problem focuses on the profit gained by a mobile virtual network operator (MVNO) which is a middleman who buys physical resource from the InP, bundling them into virtual resources called slides before selling off the service providers. To solve this problem, we propose a distributed solution framework based on Lagrangian relaxation to find a suboptimal decision about slice and transmit power allocations. Furthermore, by exploiting the concept of a matching game, we propose a low complexity solution that makes our proposal much more practical and robust in the virtualized wireless network environment. In all of these scenarios, the proposed frameworks are evaluated based on the simulation results. We show that the proposed frameworks can be implemented in a distributed manner and require a small number of iterations to converge. The experimental results show that the proposed frameworks are better than those of the other frameworks.

Inertial Navigation System의 보상알고리즘에 관한 연구

NGUYEN DUY ANH 한국해양대학교 대학원 2006 국내석사

This paper describes a method that how a relatively compensate the position errors in the using of low cost Inertial Measurement Unit (IMU) has been evaluated and compared with the well established method based on a Kalman Filter (KF). The compensation algorithm for IMU has been applied to the problem of integrating information in Inertial Navigation System (INS). The KF is used to estimate and compensate the errors of an INS by using the integrated INS velocity and position, respectively. First by using Kalman Filter, we try to reduce noise of acceleration data, where two of an acceleration, constant drift and period drift, are considered. With the constant drift, it depends on sensor and it always keeps on constant error. When using double integration for calculates distance and velocity, these kinds of drifts can make increasing velocity and position errors. So, we tried to find these errors and used constant compensation algorithm for compensation of errors in data. Second, external environment circumstance is changed ordinarily. Almost of them can be changed on periodic time. The average drift can be obtained during constant periodic time. And use this value, we consider with a factor as a periodic external disturbance which affects to the exact position. We used a repetitive method to reduce the external environment change. We verified the proposed algorithm by simulation results.

Study on Bioactivities of Mahonia nepalensis DC

Nguyen, Thi Lan Anh Kangwon National University 2018 국내석사

Design, Synthesis, and SAR Studies of Novel Scaffolds for Drug Discovery

Ngoc Pham, Tuan-Anh Kangwon National Univ 2013 국내박사

SECTION 1 Design, Synthesis, and Anti-inflammatory Activity of Novel Unnatural C-S-C and C-NH-C Linked Biflavones Biflavonoids are polyphenolic molecules which belong to flavonoid family and consist of a dimer of flavonoids linked to each other by either a C?C or a C?O?C covalent bond. Many different chemical structures of biflavonoids have been isolated from plants and found to possess interesting biological properties. Ochnaflavone, a naturally occurring biflavonoid mainly found in the medicinal plant Lonicera japonica Thunb. (Caprifoliaceae), strongly exhibit anti-inflammatory activity through multiple mechanisms. Furthermore, several synthetic approaches yielded a series of C-C and C-O-C linked biflavonoids with anti-inflammatory potential. Therefore, biflavonoids might provide a basis for novel anti-inflammatory drugs. As a part of continuing structural elaboration and searching more potent anti-inflammatory agents, a series of unnatural C-S-C and C-NH-C linked biflavones were designed, synthesized and evaluated their anti-inflammatory activities. By using transition metal-catalyzed cross-coupling reactions, a series of unnatural C-S-C and C-NH-C linked biflavones including 4 analogues of ochnaflavone and 17 basic biflavones possessing a different array of flavone-flavone linkage were generated successfully. The initial anti-inflammatory activities of ochnaflavone analogues showed promising results relate to iNOS-mediated NO production inhibition. Especially, penta-O-methyl C-S-C linked ochnaflavone analogue (BFO-1) possesses a dual strong inhibitory activities against COX-2-mediated PEG2 and iNOS-mediated NO production. To date, BFO-1 is the only synthetic biflavone having a dual promising PGE2 and NO inhibitory activities. This novel scaffolds might provide a basis for further SAR studies. Keywords: unnatural biflavone, ochnaflavone, anti-inflammatory activity, C-S-C linkage, C-NH-C linkage, cross-coupling reaction. SECTION 2 Novel Scaffolds With Potent GPR119 Agonistic Activity: Design, Synthesis, and SAR Study GPR119 is a G-protein-coupled receptor predominantly express on pancreatic beta cells and intestinal enteroendocrine cells. GPR119 can be actived by lysophosphatidylcholine (LPC), oleoylethanolamine (OEA), N-oleoyldopamin (OLDA), ovalnil and OEA most probably represents the endogenous ligand. GPR119 agonist stimulates glucose-dependent insulin secretion in vitro and lowers an elevated blood glucose level in vivo. Furthermore, they have been demonstrated to stimulate the release of the incretin (GLP-1 and GIP). Therefore, GPR119 agonist has emerged as a promising target for the treatment of type 2 diabetes and obesity by improving glucose homoeostasis while concurrently slowing gastric emptying, reducing food intake and promoting weight loss. To date, several candidates have been entered clinical trials for treatment of type 2 diabetes. Diverse fused aromatic heterocycle scaffolds were found in the precedent literatures and patents of GPR119 agonists. As a congener of bicyclic heterocycle scaffolds, we were interested in quinazoline and purine heterocycle since they have emerged as promising scaffolds in medicinal chemistry and drug development. We have synthesized and characterized a series of novel 2,4-disubstituted quinazolines. We found that the analogues bearing (2-fluoro-4-methylsulfonyl)phenylamino and azabicyclic amine groups with N-Boc (12a, 12c and 12g) exhibited better EC50 values than that of OEA even though they appeared to be partial agonists. Recently, a SAR study with purine scaffold to discover more potent GPR119 agonists is under progress. A series of purine analogues possessing (2-fluoro-4-methylsulfonyl)phenylamino group and aza(bi)cyclic alcohol or aza(bi)cyclic amine groups were generated. Their human GPR119 agonistic activities will be shown in a near future. Keywords: GPR119 agonist, type 2 diabetes, quinazoline, purine, azabicyclic amine, azabicyclic alcohol

Application of Daphnia magna in toxicity assessment and detection of waterborne pathogens

Anh, Le Vu Quynh Chonbuk National University 2018 국내박사