• Journal of the Korea Society of Computer and Information
• /
• v.25 no.3
• /
• pp.89-96
• /
• 2020

Solar lamp systems may not operate normally in the event of some system or controller failure due to internal or external factors, in which case secondary problems occur, which may cost the system recovery. Thus, when these errors occur, a technology is needed to recover to the state it was in before the failure occurred and to enable re-execution. This paper designs and implements a system that can recover the state of the system to the state prior to the time of the error by using the Watchdog Timer within the controller if a software error has occurred inside the system, and it also proposes a technology to reset and re-execution the system through a separate reset circuit in the event of hardware failure. The proposed system provides stable operation, maintenance cost reduction and reliability of the solar lamp system by enabling the system to operate semi-permanently without external support by utilizing the automatic recovery and automatic reset function for errors that occur in the operation of the solar lamp system. In addition, it can be applied to maintain the system's constancy by utilizing the self-operation, diagnosis and recovery functions required in various high reliability applications.

• Journal of Digital Contents Society
• /
• v.18 no.6
• /
• pp.1165-1173
• /
• 2017

Deep learning method, which is one of the most famous machine learning algorithms, has proven its applicability in various applications and is widely used in digital signal processing. However, it is difficult to apply deep learning technology to IoT devices with limited CPU performance and memory capacity, because a large number of training samples requires a lot of memory and computation time. In particular, if the Arduino with a very small memory capacity of 2K to 8K, is used, there are many limitations in implementing the algorithm. In this paper, we propose a method to optimize the ELM algorithm, which is proved to be accurate and efficient in various fields, on Arduino board. Experiments have shown that multi-class learning is possible up to 15-dimensional data on Arduino UNO with memory capacity of 2KB and possible up to 42-dimensional data on Arduino MEGA with memory capacity of 8KB. To evaluate the experiment, we proved the effectiveness of the proposed algorithm using the data sets generated using gaussian mixture modeling and the public UCI data sets.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.15 no.1
• /
• pp.237-243
• /
• 2015

In this paper, we consider a cascaded type of control architecture for a multi motor-based feedback control system and propose an ADC (Analog to Digital Converter) resource allocation method to efficiently utilize the limited ADC resources. The purpose of the resource allocation method is to minimize both the motor position measurement error and the d-q current measurement error. The cascaded type of control architecture is applied in parallel to each motor to independently control the speed of a motor in the multi motor control system. All the control algorithms are implemented by software using a single microcontroller without using additional microcontrollers. It is illustrated by experiments that the speed and the torque of each motor are controlled precisely by the proposed control architecture with the efficient ADC allocation method.

• KIPS Transactions on Software and Data Engineering
• /
• v.4 no.9
• /
• pp.347-356
• /
• 2015

Due to the rapid development of IoT(Internet of Things) technology, traditional taxis are connected through dispatchers and location systems. Typically, modern taxis have embedded with GPS(Global Positioning System), which aims for obtaining the route information. By analyzing the frequency of taxi trip events, we can find the frequent route for a given query time. However, a scalability problem would occur when we convert the raw location data of taxi trip events into the analyzed frequency information due to the volume of location data. For this problem, we propose a NoSQL based top-K query system for taxi trip events. First, we analyze raw taxi trip events and extract frequencies of all routes. Then, we store the frequency information into hash-based index structure of MongoDB which is a document-oriented NoSQL database. Efficient top-K query processing for frequent route is done with the top of the MongoDB. We validate the efficiency of our algorithms by using real taxi trip events of New York City.

• Journal of KIISE:Computer Systems and Theory
• /
• v.29 no.8
• /
• pp.431-439
• /
• 2002

Due to the recent development of graphics hardware, real-time rendering of complex scenes is still a challenging task. As results of researches on image based rendering, the rendering schemes based on post-rendering 3D warping have been proposed. In general, these methods produce good rendering results. However, they are not appropriate for real-time rendering since it is not easy to accelerate the time-consuming algorithms within graphics subsystem. As an attempt to resolve this problem of the post-rendering 3D warping technique, we present a new real-time scheme based on projective texture. In our method, two reference images obtained by rendering complicated objects at two consecutive points of time are used. Rendering images of high quality for intermediate points of time are obtained by projecting the reference images onto a simplified object, and then blending the resulting images. Our technique will be effectively used in developing real-time graphics applications such as 3D games and virtual reality software and so on.

• Journal of Biomedical Engineering Research
• /
• v.27 no.2
• /
• pp.78-82
• /
• 2006

The ventricular assist device(VAD) helps to reduce the overload against the patient's native heart(NH). The pulsatile VAD pumps out the ventricular blood to the aorta with pulsatile flow. If the VAD pulsates simultaneously with the NH, the ventricle of the NH could confronts abnormally elevated aortic pressure, and this could deteriorate the ventricle rather than assist to recover it. Thus counterpulsation algorithms to avoid copulsation have been adopted by many VADs, but these methods utilize electrocardiography or arterial pressure signals, which may have difficulties to acquire consistently for a long period. In this study, the copulsation estimation algorithm for the counterpulsation is developed using the VAD outlet pressure signal. The VAD outlet pressure signal is good to maintain for a long time and the sensor part could be integrated to the VAD as a built-in module. From the VAD outlet pressure signal and its pump rate information calculated with Fast Fourier Transform, pulse peaks by the VAD and the NH were extracted and the next copulsation time at which the VAD and the NH would pulsate simultaneously was estimated. This estimation algorithm was implemented by using PC MATLAB software and tested for various pump rate conditions with mock circulation system. For each condition, the copulsation time was estimated successfully. Consequently, the results showed the possibility to use the outlet cannula pressure signal in the copulsation estimation.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1906-1909
• /
• 2005

This paper presents the acceleration optimization of a high-speed LCD (Liquid Crystal Display) transfer system for the minimization of vibration. To reduce vibration is one of key requirements for the dynamic control of a high-speed LCD transfer system. In this paper, the concept of finite jerk (the first derivative of acceleration) has been introduced for realizing input acceleration. The profile of finite jerk has been optimized using a genetic algorithm so that vibration effect can be minimized. In order to incorporate a genetic algorithm, the dynamic model of a LCD transfer system which is realized by using the $ADAMS^{(R){$ software has been linked to the simulation system constructed by the $MATLAB^{(R)}$. The simulation results illustrated that the duration of finite jerk can be optimized so as to minimize the magnitude of vibration. It has been also shown that the acceleration optimization with finite jerk can make the high-speed motion of a LCD transfer system result in low vibration, compared with the conventional motion control with trapezoidal velocity profile.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.2 s.75
• /
• pp.67-74
• /
• 2007

Maritime and Ocean Engineering Research Institute (MOERI), a branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) named ISiMI (Integrated Submergible for Intelligent Mission Implementation). ISiMI is an AUV platform to satisfy the various needs of experimental test required for development of challenging technologies newly investigated in the field of underwater robot; control and navigational algorithms and software architectures. The main design goal of ISiMI AUV is downsizing which will reduce substantially the operating cost compared to other vehicles previously developed in KORDI such as VORAM or DUSAUV. As a result of design and manufacturing process, ISiMI is implemented to be 1.2 m in length, 0.17 m in diameter and weigh 20 kg in air. A series of tank test is conducted to verify the basic functions of ISiMI in the Ocean Engineering Basin of MOERI, which includes manual control with R/F link, auto depth, auto heading control and a final approach control for underwater docking. This paper describes the implementation of ISiMI system and the experimental results to verify the function of ISiMI as a test-bed AUV platform.

• Journal of Korea Multimedia Society
• /
• v.23 no.5
• /
• pp.710-720
• /
• 2020

Tsunami occurred by a rapid change in the ocean floor is a natural disaster that causes serious damage worldwide. South Korea seems to be out of the range of this damage, but it is quite possible that South Korea will fall within the range due to the long-distance propagation features of tsunami and many earthquakes occurred in Japan. However, the analysis and preparation for tsunami have been still insufficient. In this paper, we propose a tsunami simulation model based on cellular automata for analyzing coastal inundation. The proposed model calculates the range of inundation in coastal areas by propagating the energy of tsunami using the interaction between neighboring cells. We define interaction rules and algorithms for the energy transfer and propose a software tool to effectively utilize the model. In addition, to verify and tune the simulation model, we used the actual tsunami data in 2010 at Dichato, Chile. As a case study, the proposed model was applied to analyze the coastal inundation according to tsunami height in Gwangali Beach, a famous site in Busan. It is expected that the simulation model can be a help to prepare an effective countermeasure against tsunami and be used for a virtual evacuating training.

• Journal of KIISE:Software and Applications
• /
• v.37 no.8
• /
• pp.611-619
• /
• 2010

This paper presents an efficient modeling system of virtual pottery in which the user can deform a body of virtual clay with a haptic tool for E-learning. We propose a Circular Sector Element Method (CSEM) which represents the virtual pottery with a set of circular sector elements based on the cylindrical symmetry of pottery. Efficient algorithms for collision detection and response, interactions between adjacent elements, and GPU-based visual-haptic synchronization are designed and implemented for the CSEM. Empirical evaluation showed that the modeling system is computationally efficient with finer details and provides convincing model deformation and force feedback. The developed system, if combined with educational contents, is expected to be used as an effective E-learning platform for elementary school students.