• Title/Summary/Keyword: System-level Simulation

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Energy Efficient Electric Vehicle Driving Optimization Method Satisfying Driving Time Constraint (제한 주행시간을 만족하는 에너지 효율적인 전기자동차 주행 최적화 기법)

  • Baek, Donkyu
    • Journal of Korea Society of Industrial Information Systems
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    • v.25 no.2
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    • pp.39-47
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    • 2020
  • This paper introduces a novel system-level framework that derives energy efficient electric vehicle (EV) driving speed profile to extend EV driving range without additional cost. This paper first implements an EV power train model considering forces acting on a driving vehicle and motor efficiency. Then, it derivate the minimum-energy driving speed profile for a given driving mission defined by the route. This framework first formulates an optimization problem and uses the dynamic programming algorithm with a weighting factor to derive a speed profile minimizing both of energy consumption and driving time. This paper introduces various weighting factor tracking methods to satisfy the driving time constraint. Simulation results show that runtime of the proposed scaling algorithm is 34% and 50% smaller than those of the binary search algorithm and greedy algorithm, respectively.

An Energy-Efficient Self-organizing Hierarchical Sensor Network Model for Vehicle Approach Warning Systems (VAWS) (차량 접근 경고 시스템을 위한 에너지 효율적 자가 구성 센서 네트워크 모델)

  • Shin, Hong-Hyul;Lee, Hyuk-Joon
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.7 no.4
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    • pp.118-129
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    • 2008
  • This paper describes an IEEE 802.15.4-based hierarchical sensor network model for a VAWS(Vehicle Approach Warning System) which provides the drivers of vehicles approaching a sharp turn with the information about vehicles approaching the same turn from the opposite end. In the proposed network model, a tree-structured topology, that can prolong the lifetime of network is formed in a self-organizing manner by a topology control protocol. A simple but efficient routing protocol, that creates and maintains routing tables based on the network topology organized by the topology control protocol, transports data packets generated from the sensor nodes to the base station which then forwards it to a display processor. These protocols are designed as a network layer extension to the IEEE 802.15.4 MAC. In the simulation, which models a scenario with a sharp turn, it is shown that the proposed network model achieves a high-level performance in terms of both energy efficiency and throughput simultaneously.

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Nonlinear optimal control for reducing vibrations in civil structures using smart devices

  • Contreras-Lopez, Joaquin;Ornelas-Tellez, Fernando;Espinosa-Juarez, Elisa
    • Smart Structures and Systems
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    • v.23 no.3
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    • pp.307-318
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    • 2019
  • The frequently excessive vibrations presented in civil structures during seismic events or service conditions may result in users' discomfort, or worst, in structures failure, producing economic and even human casualties. This work contributes in proposing the synthesis of a nonlinear optimal control strategy for semiactive structural control, with the main characteristic that the synthesis considers both the structure model and the semiactive actuator nonlinear dynamics, which produces a nonlinear system that requires a nonlinear controller design. The aim is to reduce the unwanted vibrations in the response of civil structures, by means of intelligent fluid semiactive actuator such as the Magnetorheological Damper (MRD), which is a device with a low level of power consumption. The civil structures for which the proposed control methodology can be applied are those admitting a state-dependent coefficient factorized representation model, such as buildings, bridges, among others. A scaled model of a three storey building is analyzed as a case study, whose dynamical response involves displacement, velocity and acceleration of each one of the storeys, subjected to the North-South component of the September 19th., 2017, Puebla-Morelos (7.1M), Mexico earthquake. The investigation rests on comparing the structural response over time for two different conditions: with no control device installed and with one MRD installed between the first floor and the ground, where a nonlinear optimal signal for the MRD input voltage is determined. Simulation results are presented to show the effectiveness of the proposed controller for reducing the building's dynamical response.

Design and Analysis of Technical Management System of Personal Information Security using Web Crawer (웹 크롤러를 이용한 개인정보보호의 기술적 관리 체계 설계와 해석)

  • Park, In-pyo;Jeon, Sang-june;Kim, Jeong-ho
    • Journal of Platform Technology
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    • v.6 no.4
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    • pp.69-77
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    • 2018
  • In the case of personal information files containing personal information, there is insufficient awareness of personal information protection in end-point areas such as personal computers, smart terminals, and personal storage devices. In this study, we use Diffie-Hellman method to securely retrieve personal information files generated by web crawler. We designed SEED and ARIA using hybrid slicing to protect against attack on personal information file. The encryption performance of the personal information file collected by the Web crawling method is compared with the encryption decryption rate according to the key generation and the encryption decryption sharing according to the user key level. The simulation was performed on the personal information file delivered to the external agency transmission process. As a result, we compared the performance of existing methods and found that the detection rate is improved by 4.64 times and the information protection rate is improved by 18.3%.

The Status and Prospect of Decommissioning Technology Development at KAERI (한국원자력연구원의 해체기술 개발 현황 및 향후 전망)

  • Moon, Jeikwon;Kim, Seonbyung;Choi, Wangkyu;Choi, Byungseon;Chung, Dongyong;Seo, Bumkyoung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.17 no.2
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    • pp.139-165
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    • 2019
  • The current status and prospect of decommissioning technology development at KAERI are reviewed here. Specifically, this review focuses on four key technologies: decontamination, remote dismantling, decommissioning waste treatments, and site remediation. The decontamination technologies described are component decontamination and system decontamination. A cutting method and a remote handling method together with a decommissioning simulation are described as remote dismantling technologies. Although there are various types of radioactive waste generated by decommissioning activities, this review focuses on the major types of waste, such as metal waste, concrete waste, and soil waste together with certain special types, such as high-level and high-salt liquid waste, organic mixed waste, and uranium complex waste, which are known to be difficult to treat. Finally, in a site remediation technology review, a measurement and safety evaluation related to site reuse and a site remediation technique are described.

Design of SECE Energy Harvest Interface Circuit with High Voltage Comparator for Smart Sensor (고전압 비교기를 적용한 스마트 센서용 SECE 에너지 하베스트 인터페이스 회로 설계)

  • Seok, In-Cheol;Lee, Kyoung-Ho;Han, Seok-Bung
    • The Journal of the Korea institute of electronic communication sciences
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    • v.14 no.3
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    • pp.529-536
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    • 2019
  • In order to apply a piezoelectric energy harvester to a smart sensor system, an energy harvest interface circuit including an AC-DC rectifier is required. In this paper, we compared the performance of full bridge rectifier, which is a typical energy harvester interface circuit, and synchronous piezoelectric energy harvest interface circuit by using board-level simulation. As a result, the output power of a synchronous electric charge extraction(: SECE) circuit is about four times larger than that of the full bridge rectifier, and there is little load variation. And a high voltage comparator, which is essential for the SECE circuit for the piezoelectric energy harvester with an output voltage of 40V or more, was designed using 0.35 um BCD process. The SECE circuit using the designed high-voltage comparator proved that the output power is 427 % higher than the FBR circuit.

A CMOS Interface Circuit for Vibrational Energy Harvesting (진동에너지 수확을 위한 CMOS 인터페이스 회로)

  • Yang, Min-jae;Yoon, Eun-jung;Yu, Chong-gun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2014.10a
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    • pp.267-270
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    • 2014
  • This paper presents a CMOS interface circuit for vibration energy harvesting. The proposed circuit consists of an AC-DC converter and a DC-DC boost converter. The AC-DC converter rectifies the AC signals from vibration devices(PZT), and the DC-DC boost converter generates a boosted and regulated output at a predefined level. A full-wave rectifier using active diodes is used as the AC-DC converter for high efficiency, and a schottky diode type DC-DC boost converter is used for a simple control circuitry. A MPPT(Maximum Power Point Tracking) control is also employed to harvest the maximum power from the PZT. The proposed circuit has been designed in a 0.35um CMOS process. The chip area is $530um{\times}325um$. Simulation results shows that the maximum efficiencies of the AC-DC converter and DC-DC boost converter are 97.7% and 89.2%, respectively. The maximum efficiency of the entire system is 87.2%.

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Hybrid Rocket Thrust Control in an Environment With Decreasing Oxidizer Supply Pressure (산화제 공급압력이 감소하는 환경에서 하이브리드 로켓 추력제어)

  • Chae, Donghoon;Chae, Heesang;Lee, Changjin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.5
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    • pp.325-332
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    • 2022
  • The vertical take-off and vertical landing (VTVL) function is essential to carry out exploration missions on the moon or Mars. For this, the engine of the exploration vehicle must have appropriate thrust control accuracy and response time. The hybrid rocket engine (HRE) is known to have a high level of thrust control capability that can satisfy these conditions. This study aims to first verify whether the thrust control performance of the developed HRE is suitable for VTVL. To this end, an oxidizer supply system that does not use a pressurization device was adopted, aiming for a mission time of about 10 seconds. In this study, the thrust control characteristics appearing under various supply pressure decreasing conditions were identified through experiments. Appropriate tank and charging conditions were set from the experimental results. In addition, the results of previous studies and current study's test were compared to confirm whether the developed HRE had adequate control performance for VTVL, and finally, the thrust control performance was verified through altitude control simulation.

1D Kinetics Model of NH3-Fed Solid Oxide Fuel Cell (암모니아 공급 고체산화물 연료전지의 1D 반응 모델)

  • VAN-TIEN GIAP;THAI-QUYEN QUACH;KOOK YOUNG AHN;YONGGYUN BAE;SUNYOUP LEE;YOUNG SANG KIM
    • Transactions of the Korean hydrogen and new energy society
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    • v.33 no.6
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    • pp.723-732
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    • 2022
  • Cracking ammonia inside solid oxide fuel cell (SOFC) stack is a compact and simple way. To prevent sharp temperature fluctuation and increase cell efficiency, the decomposition reaction should be spread on whole cell area. This leading to a question that, how does anode thickness affect the conversion rate of ammonia and the cell voltage? Since the 0D model of SOFC is useful for system level simulation, how accurate is it to use equilibrium solver for internal ammonia cracking reaction? The 1D model of ammonia fed SOFC was used to simulate the diffusion and reaction of ammonia inside the anode electrode, then the partial pressure of hydrogen and steam at triple phase boundary was used for cell voltage calculation. The result shows that, the ammonia conversion rate increases and reaches saturated value as anode thickness increase, and the saturated thickness is bigger for lower operating temperature. The similar cell voltage between 1D and 0D models can be reached with NH3 conversion rate above 90%. The 0D model and 1D model of SOFC showed similar conversion rate at temperature over 750℃.

Derivation of Assessment Scenario Elements for Automated Vehicles in the Expressway Mainline Section (자율주행차 평가 시나리오 구성요소 도출: 고속도로 본선구간을 중심으로)

  • Ko, Woori;Yun, Ilsoo;Park, Sangmin;Jeong, Harim;Park, Sungho
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.21 no.1
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    • pp.221-239
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    • 2022
  • Various elements such as geometry, traffic safety facilities, congestion level, weather, etc., need to be appropriately reflected in the assessment scenario evaluating the driving safety of automated vehicles. Therefore, this study first established a scenario structure and defined the layer of elements, to derive the elements to be reflected in the automated driving safety evaluation. After that, all elemental candidates that can be reflected in each layer were derived by reviewing the relevant literature. Finally, as a result of an expert survey, 77 items were selected to be reflected in the automated driving safety evaluation. The selected elements are expected to be actively utilized in developing scenarios for the driving safety evaluation of automated vehicles in simulation, proving ground, and real road assessments.