Multi-Collector Control for Workload Balancing in Wireless Sensor and Actuator Networks

한야민,변희정 대한임베디드공학회 2021 대한임베디드공학회논문지 Vol.16 No.3

The data gathering delay and the network lifetime are important indicators to measure the service quality of wireless sensor and actuator networks (WSANs). This study proposes a dynamically cluster head (CH) selection strategy and automatic scheduling scheme of collectors for prolonging the network lifetime and shorting data gathering delay in WSAN. First the monitoring region is equally divided into several subregions and each subregion dynamically selects a sensor node as CH. These can balance the energy consumption of sensor node thereby prolonging the network lifetime. Then a task allocation method based on genetic algorithm is proposed to uniformly assign tasks to actuators. Finally the trajectory of each actuator is optimized by ant colony optimization algorithm. Simulations are conducted to evaluate the effectiveness of the proposed method and the results show that the method performs better to extend network lifetime while also reducing data delay.

빅데이터 분석을 통한 운전자 맞춤형 엔진 제어 장치 시스템의 개발

김식,김정환,Kim, Shik,Kim, Junghwan 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

Since 2016 when the regulations related to vehicle structure and device modification were drastically revised, the car tuning market has been growing rapidly. Particularly, many drivers are showing interest in changing the interior and exterior according to their preference, or improving the specifications of their cars by changing the engine and powertrain, among others. Also, as the initial engine settings such as horse power and torque of the vehicle are made for stable driving of the vehicle, it is possible to change the engine performance, via Engine Control Unit (ECU) mapping, to the driver's preference. However, traditionally, ECU mapping could be only performed by professional car engineers and the settings were also decided by them. Therefore, this study proposed a system that collects data related to the driver's driving habits for a certain period and sends them to a cloud server in order to analyze them and recommend ECU mapping values. The traditional mapping method only aimed to improve the car's performance and, therefore, if the changes were not compatible with the driver's driving habits, could cause problems such as incomplete combustion or low fuel efficiency. However, the proposed system allows drivers to set legally permitted ECU mapping based on analysis of their driving habits, and, therefore, different drivers can set it differently according to the vehicle specifications and driving habits. As a result, the system can optimize the car performance by improving output, fuel efficiency, etc. within the range that is legally permitted.

CDR을 사용한 FPGA 기반 분산 임베디드 시스템의 클록 동기화 구현

송재민,정용배,박영석,Song, Jae-Min,Jung, Yong-Bae,Park, Young-Seak 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

Time synchronization between distributed embedded systems in the Real Time Locating System (RTLS) based on Time Difference of Arrival (TDOA) is one of the most important factors to consider in system design. Clock jitter error between each system causes many difficulties in maintaining such a time synchronization. In this paper, we implemented a system to synchronize clocks between FPGA based distributed embedded systems using the recovery clock of CDR (clock data recovery) used in high speed serial communication to solve the clock jitter error problem. It is experimentally confirmed that the cumulative time error that occurs when the synchronization is not performed through the synchronization logic using the CDR recovery clock can be completely eliminated.

하이브리드 메모리 큐브 (HMC) 시스템의 고속 직렬 링크 (SerDes)를 위한 모델링 및 성능 분석

전동익,정기석,Jeon, Dong-Ik,Chung, Ki-Seok 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

Various 3D-stacked DRAMs have been proposed to overcome the memory wall problem. Hybrid Memory Cube (HMC) is a true 3D-stacked DRAM with stacked DRAM layers on top of a logic layer. The logic die is mainly used to implement a memory controller for HMC, and it is connected through a high speed serial link called SerDes with a host that is either a processor or another HMC. In HMC, the serial link is crucial for both performance and power consumption. Therefore, it is important that the link is configured properly so that the required performance should be satisfied while the power consumption is minimized. In this paper, we propose a HMC system model included the high speed serial link to estimate performance accurately. Since the link modeling strictly follows the link flow control mechanism defined in the HMC spec, the actual HMC performance can be estimated accurately with respect to each link configuration. Various simulations are conducted in order to deduce the correlation between the HMC performance and the link configuration with regard to memory utilization. It is confirmed that there is a strong correlation between the achievable maximum performance of HMC and the link configuration in terms of both bandwidth and latency. Therefore, it is possible to find the best link configuration when the required HMC performance is known in advance, and finding the best configuration will lead to significant power saving while the performance requirement is satisfied.

스케일 불변적인 연산량 감소를 위한 경량 실시간 소형 적외선 표적 검출 알고리즘

반종희,유준혁,Ban, Jong-Hee,Yoo, Joonhyuk 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

Detecting small infrared targets from the low-SCR images at a long distance is very hard. The previous Local Contrast Method (LCM) algorithm based on the human visual system shows a superior performance of detecting small targets by a background suppression technique through local contrast measure. However, its slow processing speed due to the heavy multi-scale processing overhead is not suitable to a variety of real-time applications. This paper presents a lightweight real-time small target detection algorithm, called by the Improved Selective Local Contrast Method (ISLCM), to reduce the scale-invariant computational overhead. The proposed ISLCM applies the improved local contrast measure to the predicted selective region so that it may have a comparable detection performance as the previous LCM while guaranteeing low scale-invariant computational load by exploiting both adaptive scale estimation and small target feature feasibility. Experimental results show that the proposed algorithm can reduce its computational overhead considerably while maintaining its detection performance compared with the previous LCM.

추적 레이더에서 적응형 확장 칼만 필터의 성능 분석

송승언,신한섭,김대오,고석준,Song, Seungeon,Shin, Han-Seop,Kim, Dae-Oh,Ko, Seokjun 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

An angle error is a factor obstructing to track accurate position in tracking radars. And the noise incurring the angle error can be divided as follows; thermal noise and glint. In general, Extended Kalman filter used in tracking radars is designed with considering thermal noise only. The Extended Klaman filter uses a fixed measurement error covariance when updating an estimate state by using ahead state and measurement. But, a noise power varies according to the range. Therefore we purposes the adaptive Kalman filter which changes the measurement noise covariance according to the range. In this paper, we compare the performance of the Extended Kalman filter and the proposed adaptive Kalman filter by considering KSLV-I (Korean Satellite Launch Vehicles).

Beacon System과 Encoder를 이용한 Omniwheel 연마 로봇의 주행 제어

송준우,최병찬,김태언,스리지드,이장명,Song, Jun-Woo,Choi, Byeong-Chan,Kim, Tae-Eon,Sreenivasan, Sreejith Manalipadam,Lee, Jang-Myung 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

Utilizing the existing polishing robot prevents unrestricted change of direction, driving, and identification of driving pathway. To overcome this barrier, driving mechaism has been designed with Omniwheels with encoders and RSSI method of beacon system has been utilized to identify the driving path by position recognition. Due to the wheel characteristics, the Omniwheel mobile robot generates greater slip than the conventional mobile robot, which reduces its driving accuracy. Therefore, to improve the driving accuracy, the localization is conducted through the fusion of encoder and RSSI of beacon data to compensate for the errors caused by Dead Reckoning and inaccuracy of sensors. Finally, the localization accuracies of the proposed and conventional indoor localization method are compared to show effectiveness of the proposed driving control for a polishing robot.

Zephyr 커널에서 고정 시간 동기식 IPC 구현

정주영,김은영,신동하,Jung, Jooyoung,Kim, Eunyoung,Shin, Dongha 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

Linux Foundation has announced a real-time kernel, called Zephyr, for IoT applications recently. Zephyr kernel provides synchronous and asynchronous IPC for data communication between threads. Synchronous IPC is useful for programming multi-threads that need to be executed synchronously, since the sender thread is blocked until the data is delivered to the receiver thread and the completion of data transfer can be known to two threads. In general, 'IPC execution time' is defined as the time duration between the sender thread sends data and the receiver thread receives the data sent. Especially, it is important that 'IPC execution time' in the synchronous IPC should be fixed in real-time kernel like Zephyr. However, we have found that the execution time of the synchronous IPC in Zephyr kernel increases in proportion to the number of threads executing in the kernel. In this paper, we propose a method to implement a fixed time synchronous IPC in Zephyr kernel using Direct Thread Switching(DTS) technique. Using the technique, the receiver thread executes directly after the sender thread sends a data during the remaining time slice of the sender thread and we can archive a fixed IPC execution time even when the number of threads executing in the kernel increases. In this paper, we implemented synchronous IPC using DTS in the Zephyr kernel and found the IPC execution time of the IPC is always 389 cycle that is relatively small and fixed.

보안 마이크로 웹페이지 기반 전장 스마트 지도

허준,하선주,차신,은성배,Heo, Jun,Ha, Sunju,Cha, Shin,Eun, Seongbae 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.4

GPS was developed for military purposes. As a result, it is used as a military important means such as guided weapons and strategy / tactics. However, GPS depends on the communication infrastructure and is affected by interference signals. In this paper, we propose a secure micro - web page - based smart map that can enhance security without relying on communication infrastructure on the battlefield. The proposed system consists of general smartphone, security QR, central server and smart map. Only use the network when downloading the security key and SmartMap before the task starts. During operation, the smartphone transmits and receives data using a secure QR. The security QR inserts the security code to prevent forgery and falsification and confirms whether the data is authentic by checking whether the smart phone is forged or not. As a result of implementation, we solved communication security problem of existing technology by using location based service without relying on communication infrastructure.

무인수상정의 임무계획 적합성 분석을 위한 침투 표적 탐지율 산출 프로그램 설계

김민지,황근철,유찬우,김정훈,Kim, Min J.,Hwang, Kun Chul,Yu, Chan Woo,Kim, Jung Hoon 대한임베디드공학회 2017 대한임베디드공학회논문지 Vol.12 No.5

The naval unmanned surface vehicle (USV) conducts the surveillance operations, based on the mission plan set by the user. For setting the mission planning, the user needs to analyze the suitability of the operation for the mission planning. In this paper, we proposed a simulation program that estimates the probability of detecting targets of the mission planning in the analysis. In the simulation analysis, we design the USV's maneuvering characteristics, radar detection operational performance equipped on the USV, and targets infiltrating into surveillance area in the simulation experiment scenario. Based on the simulation results, we evaluated the mission planning suitability and find a mission planning solution recursively.