Performance Analysis of Visible Light Communication System and Visible Light Positioning Technique

Do, Trong Hop Graduate School of Soongsil University 2015 국내박사

Visible light communication (VLC) is a communication technique using visible light radiated from light emitting diode (LED) for data transmission. There are many advantages of VLC in terms of capacity, efficiency, security, and safety. Due to these advantages, VLC has been considered to be the next generation of wireless communication technology. Along with VLC, positioning based on VLC have been received a considerable attentions in recent years. In this dissertation, multiple aspects of VLC and VLC based positioning were studied. Firstly, the effect of LED direction on the system performance was analyzed. The link quality and power consumption of VLC system were optimized using multi-objective optimization (MOO). A new TDOA positioning system using VLC was proposed. VLC는 데이터를 전송하기 위해 발광 다이오드(LED)를 이용한 가시광무선통신 기술입니다. VLC는 많은 대역폭 능률, 보안, 안전성에 많은 장점이 있다. 이러한 장점들로 인해 VLC는 차세대 무선통신기술로 고려되고 있습니다. VLC와 함께, 위치 기반 가시광무선통신은 최근 몇년간 주목을 받고 받고 있습니다. 이 논문에서 VLC의 여러 분야와 위치기반 VLC를 연구 하였습니다. 첫번째, 시스탬의 LED 방면의 효과를 분석하였습니다. VLC 시스탬은 링크 품질과 소비전력은 다목적 최적화를 사용하여 최적화 되었습니다. VLC를 이용하여 새로운 TDOA 위치 시스탬이 제안되었습니다.

Efficient Broadcasting Scheme in Mobile Ad-Hoc Network

Trong Duc Le 성균관대학교 일반대학원 2009 국내석사

Broadcasting (or flooding) is an indispensable operation for providing control or routing functionalities to mobile ad-hoc networks (MANETs). Previously, many broadcasting schemes have been studied with the intention of curtailing the problems of severe redundancies, contention, and collisions in traditional implementations. A recent approach with relatively high efficiency is 1HI by Liu et al., which uses only 1-hop neighbor information. The scheme achieves local optimality in terms of the number of retransmission nodes with time complexity O(n log n), where n is the number of neighbors of a node; however, this method tends to make many redundant transmissions. In this thesis, I present a novel broadcasting algorithm, 2HBI (2-hop backward information), that efficiently reduces the number of retransmission nodes and solves the broadcast storm problem in ad-hoc networks using my proposed concept, “2-hop backward information.” The most significant feature of the proposed algorithm is that it does not require any extra communication overhead other than the exchange of 1-hop HELLO messages but maintains high deliverability. Comprehensive computer simulations show that the proposed scheme significantly reduces redundant transmissions in 1HI and in pure flooding, up to 38% and 91%, respectively; accordingly it alleviates contention and collisions in networks.

Control of a Mobile Picking Robot for Path Tracking and Object Grasping Using a Kinect Stereo Camera : Kinect 스테레오 카메라를 사용한 경로 추적과 목적물 파지용 이동 로봇의 제어

Trong Hai Nguyen 부경대학교 대학원 2017 국내박사

Motion planning such as mobile manipulation must be able not only to move in safety through their environments but also to manipulate objects in their environments. This dissertation presents experimental validation on control of a mobile picking robot (MPR) for path tracking and object grasping using a Kinect stereo camera. To do this task, the followings are done. Firstly, the system configuration of the mobile picking robot is described. The mobile picking robot is considered as two subsystems such as a manipulator and a mobile platform. The Kinect stereo camera is mounted on the front side of the mobile platform to capture both RGB and depth (RGBD) images at the speed of 30 frames/sec. Secondly, modeling of BLDC motor is introduced. Mathematical kinematic and dynamic modelings of the mobile platform and the manipulator are presented. The Denavit-Hartenberg (DH) convention is adopted to define the modeling parameters which allow the construction of the forward kinematics function by composing the individual coordinate transformations. Thirdly, the RGBD image from the Kinect stereo camera sensor is utilized to recognize objects for obstacle avoidance, path planning and picking objects. To ensure robust and correct object identification, two algorithms to be effective for object detection are employed: Speeded Up Robust Features (SURF) algorithm first for detecting object’s features and Fast Library for Approximate Nearest Neighbors (FLANN) algorithm for matching object’s features. For object grasping, a rectangle representation algorithm based on depth map data from the Kinect stereo camera sensor is proposed. By converting RGBD image into 3D point clouds, an algorithm for localizing handle-like grasp affordances is proposed. The main idea is to search the point cloud for neighborhoods that satisfy handle-like grasp affordances and can be grasped by the end-effector of the manipulator. Fourthly, a SLAM algorithm based on EKF is adopted to solve the global localization problem. The positions of the landmarks are obtained using a Kinect stereo camera sensor. The position of the mobile platform is predicted using EKF prediction step based on data of encoder and laser sensor. D* Lite algorithm is used to generate a path for the mobile platform to go from a start point to a goal point with avoiding unknown obstacles using information obtained from the Kinect stereo camera sensor. Fifthly, a robust servo controller design based on a polynomial differential operator method is applied for the mobile platform to track the path generated by the D* algorithm. This robust servo controller is also applied for BLDC motor for speed control of the BLDC motor with a step type of disturbance and 3 types of the references such as step, ramp and parabola. The differential kinematics algorithm is applied for the end-effector of the manipulator to approach the desired grasing position. Finally, the effectiveness of the proposed algorithms and controller is verified by using simulation and experiment.

(A) numerical analysis on the fire characteristics after water sprinkler activation in a compartment fire

Trong, KhoatHo 중앙대학교 대학원 2020 국내석사

(The) factors affecting intention to use electronic government based on the national culture difference between Vietnam and Korea

Trong, Van Hung Soongsil University 2016 국내박사

Electrical impedimetric sensing platform for bioanalytical application : for the detection of cancer cells, pathogenic bacteria and biomolecules

Trong Binh Tran 중앙대학교 대학원 2016 국내박사

(A) study on CMOS-based high-performance optical receivers and their applications

Ngo, Trong-Hieu KAIST 2011 국내박사

Highly stable and stretchable organic electrochemical transistor for artificial synapses

Nguyen, Trong Danh Sungkyunkwan university 2020 국내석사

Synapses are essential for the transmission and processing of nervous signals. Synaptic plasticity allows changes in synaptic strength that make brains learn from experience, computing, and memory concurrently. By mimicking structure and functions of synapses, synaptic devices have been developed because some advantages of fast data processing and lower power consumption, which leads to the development of brain-like computing system. Organic electrochemical transistors (OECTs) using poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) as a channel material are the most recent addition to the application in artificial synapses. They been shown to exhibit memory functionalities like long-term plasticity, short-term plasticity, spike-timing dependent plasticity, and homeostatic plasticity. However, to mimic the synaptic function and mechanical property in terms of elongated shape of nerve fiber, the stability and stretchability of OECT devices should be considered. Herein, we report a highly stable and stretchable OECT which is formed on mogul-patterned substrate with the capability of stress absorption for stretchability by using four-components of materials, PEDOT:PSS/ (3‐glycidyloxypropyl)trimethoxysilane (GOPS) (crosslinker)/ Xylitol/CapstoneFS® 30 (surfactant), as a transistor channel. It was found that the GOPS has functions of making polymer film stable in electrolyte solution, xylitol helps increasing the mobility of charge carriers and stretchability of PEDOT:PSS, and CapstoneFS® 30 reduces the surface tension of solution for facile coating on the three-dimensional mogulpatterned substrate. The stretchable OECT presents high stability and capability of working in both depletion and accumulation-mode and shows changes in synaptic weight at different frequencies, amplitude or number of electrical pulses. Furthermore, a Nafion membrane was applied on top of OECT, the membrane was able to enhance synaptic weights of transistors up to 277%.

Morphological and DNA marker-based evaluation of genetic diversity in soybean, Glycine max (L.) merrill

Truong, Trong Ngon 서울대학교 대학원 2006 국내박사

(A) study on atomic-scale mixed-mode fracture of brittle grain boundaries of crystalline solids by using molecular dynamics simulation and conservation integrals

Mai Trong Nghia 중앙대학교 대학원 2018 국내박사

Grain boundaries of polycrystalline materials can be one of the easiest paths for crack propagations, since atoms at grain boundaries experience less ordered interatomic interactions with neighboring atoms than those in homogeneous crystalline materials. Each grain boundary of polycrystalline material has different mechanical properties and failure mechanisms under mixed-mode loadings. In view of the fact that the fracture toughness depends on the mode mixity in mixed-mode fractures, the stress intensity factors (SIFs) of modes I and II at the crack tip need to be found individually. In this study, we have developed a computational scheme based on atomic-level J-based mutual integral to extract individual SIFs from the molecular dynamics (MD) simulation of the mixed-mode fracture along grain boundaries (GBs) in crystalline materials. For the atomic-level J-based mutual integral, the anisotropic elasticity solution to a semi-infinite crack along a bimaterial interface is used as an auxiliary field. Besides, the atomic-level J and M integrals are performed to find out the energy release rate and the position of a crack tip under the applied mixed-mode loadings. The mixed-mode fracture along GBs of nickel are investigated in the present study to demonstrate that our computational scheme is very useful to study mixed-mode fracture behaviours of metals at atomic scale. Furthermore, our computational scheme is also used to quantitatively characterize the mixed-mode fracture behavior of GBs in graphene, the individual stress intensity factors of mode I and mode II were first calculated by using the atomic-level J-based mutual integrals. When a mixed-mode loading is applied to a crack running along a graphene GB, as the mode mixity increases, the fracture toughness of GBs in graphene also gradually increases. However, if the mode mixity becomes greater than 8°, interestingly, the fracture toughness gradually decreases, which can be considered a special characteristic of GBs in graphene. This abnormally-low fracture toughness of GBs in graphene for high mode mixity may be interpreted with the competition between bond-rotation and bond-breaking mechanisms of carbon atoms in conjunction with the Stone-Wales transformation and nonagon structures at the crack tip along GBs in graphene. In addition, the atomic-level field projection method (FPM) is also developed to obtain the cohesive zone law (CZL) under mixed-mode loadings for the interface cracks of nickel by using an analytical auxiliary field with anisotropic elastic theory. This augmented FPM has no convergence problems and does not need to find a numerical helper every time, depending on the given problem associated with finite elements solution. This method is developed based on an analytic auxiliary field, as well as the effective use of atomic-level J- and M-based mutual integrals.