• IEMEK Journal of Embedded Systems and Applications
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• v.19 no.5
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• pp.259-265
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• 2024

In this paper, we propose an automatic display defect detection system using image processing. The existing inspection by operators has the disadvantage that human errors may occur due to the operator's skill level, fatigue, etc., and that standardization and quantification are difficult. It also has disadvantages such as the limited inspection speed and the cost of the operator's education. The proposed system automatically detects various display defects through image processing algorithms. It was developed based on the Jetson Nano, one of the most popular SBCs (Single Board Computers), and it has a conveyor belt to automatically moves the display to the inspection position. By providing a human machine interface (HMI), the operator can check the inspection information in real time, and control the inspection flow. By storing the inspection results as a log file, the operator can check the inspection results at any time, such as the time taken to perform each algorithm and the location of the detected defects. In addition, a multi-threaded structure was adopted. The camera's operations and inspection algorithms are executed in parallel in different threads, which can shorten the inspection time compared to the system based on a single-threaded structure. The experimental results prove the defect detection capability of the system and the efficiency of the inspection time.

• Journal of Power Electronics
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• v.5 no.2
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• pp.99-103
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• 2005

In this paper, a novel circuit topology of a three-winding coupling inductor-assisting a high-frequency PWM boost chopper type DC-DC power converter with a high boost voltage conversion ratio and low switch voltage stress is proposed for the new energy interfaced DC power conditioner in solar photovoltaic and fuel cell generation systems. The operating principle in a steady state is described by using its equivalent circuits under the practical condition of energy processing of a lossless capacitive snubber. The newly-proposed power MOSFET boost chopper type DC-DC power converter with the three-winding coupled inductor type transformer and a single lossless capacitor snubber is built and tested for an output power of 500W. Utilizing the lower voltage and internal resistance power MOSFET switch in the proposed PWM boost chopper type DC-DC power converter can reduce the conduction losses of the active power switch compared to the conventional model. Therefore, the total actual power conversion efficiency under a condition of the nominal rated output power is estimated to be 81.1 ％, which is 3.7％ higher than the conventional PWM boost chopper DC power conversion circuit topology.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.7
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• pp.585-590
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• 2014

Recently, monitoring systems, such as POP, take a core role in scheduling or planning of manufacturing facilities for production, maintenance, and so on. Such monitoring systems require functionalities for real-time parameter monitoring and controlling to maximize efficiency of facilities. However, vendors usually do not provide internal communication protocols or interface to access the machine controller. Therefore, the values of parameters related to machine operations and controls cannot be easily accessed from external devices. In this paper, we propose an interface methodology for a real-time monitoring and controlling of injection molding machine parameters such as user input parameters, embedded sensor data and injection molding status information.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1178-1182
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• 2004

This paper presents web-based virtual laboratory system for electronic and digital circuit experiments. Through our virtual laboratory, the learners will be capable of learning the concepts and theories related to circuit experiments and how to operate virtual experimental equipments such as multimeters, function generators, digital oscilloscopes, DC power suppliers and bread board etc. The proposed virtual laboratory system is composed of important components: Principle Classroom to explain the concepts and theories of electronic and digital circuit operations, Simulation Classroom to provide a web-based simulator to the learners, Virtual Experiment Classroom to provide interactive multimedia contents about the syllabus of off-line laboratory class, Assessment Classroom, and Management System. With the aid of the management System every classroom is organically tied together collaboration to achieve maximum learning efficiency. We have obtained several affirmative effects such as high learning standard, reducing the total experimental hours and the damage rate for experimental equipments.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.11
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• pp.11-19
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• 1994

Turnaround time of a job performing frequent disk I/O operations is greatly affected by I/O bottleneck which incurs due to the large gap in the speeds of I/O devices and the CPU. This paper proposes to employ a Write Dedicated Buffer(WDB) in disk arrays to improve the response time for read requests and analyzes the scheduling policies and the efficiency of the WDB. Through a series of simulations we show that, among the three policies examined, the partial stripe join(PSJ) policy is the most effective in terms of response time for both read and write requests and that, especially when using a WDB on declustered arrays, improvement of response time for read requests becomes greater as the request rate increases.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.74-81
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• 2017

A crane is typically used as a means to lift and load equipment or materials. A surface vessel uses a towed object for underwater activity. Such a mechanism for dropping and lifting of equipment is necessary, and is called an overboarding unit. The present study is focused on the overboarding unit used for a crane structure. This paper deals with new overboarding mechanism design and GA-based $MATLAB^{(R)}$ optimization. By using a quadrilateral link mechanism, it is possible to set the constraint function for optimizing the GA method. The optimization with $MATLAB^{(R)}$ is followed by the $SolidWorks^{(R)}$ simulation and verification. When applying the proposed mechanism, the operator is expected to have a big advantage in safety and efficiency of operations. Furthermore, the technology developed in this study will be helpful in similar circumstances and in the proposed mechanism.

• Journal of Navigation and Port Research
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• v.34 no.4
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• pp.287-292
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• 2010

The purpose of this study was to create a cyber-training & education program in response to the needs of skippers and crews operating tug-barges within Korean coastal waters and the rapid changers in this industry. Skippers and crews are inclined to operate tug-barges on the basis of experience rather than information. It is not easy to provide useful information whenever they want or to drill them in safety management skills, because of their passive attitude toward education and the few opportunities that exist. In order to increase educational opportunities, efficiency and motivation, the authors have developed this program which consists of a 'tug bridge resource management module, risk perception training module, accident case module, operating module and navigation module', and are hoping that this program will enhance and strengthen all tug-barge operations. We are also putting all our energies into designing up to date animation programs and developing new scenarios concerning the method of evaluation and certification distribution.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1276-1282
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• 2003

The works on the existing spatial indices have been proposed the retrieval methods. However, keeping track of the terminal location of moving objects is more important than the efficiency of the query processing in the moving object database. Therefore, many pure spatial indices are not applicable to the moving objects database which should maintain the object's current location as precise as possible. This paper proposes a method for reducing the construction time of indexing moving objects. We analyze the characteristics of the method to re-index all the objects after each time period and the method to update immediately the locations on reporting their locations. We also newly propose a selective immediate update method using the properties of moving objects in order to minimize the number of database updates.

• Management Science and Financial Engineering
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• v.18 no.1
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• pp.27-37
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• 2012

This paper is motivated by a military cargo-plane routing problem which is a pickup-and-delivery problem in which load splits and node revisits are allowed (PDPLS). Although this recent evolution of a VRP-model enhances the efficiency of routing, a solution method is more of a challenge since the node revisits entail closed walks in modeling vehicle routes. For such a case, even a compact IP-formulation is not available and an effective method had been lacking until Nowak et al. (2008b) proposed a heuristic based on a tabu search. Their method provides very reasonable solu-tions as demonstrated by the experiments not only in their paper (Nowak et al., 2008b) but also in ours. However, the computation time seems intensive especially for the class of problems with dynamic transportation requests, including the military cargo-plane routing problem. This paper proposes a more scalable algorithm hybridizing a tabu search for pricing subproblem paused as a single-vehicle routing problem, with a column generation approach based on Dantzig-Wolfe decomposition. As tested on a wide variety of instances, our algorithm produces, in average, a solution of an equiva-lent quality in 10~20% of the computation time of the previous method.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5572-5595
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• 2016

Multi-server authentication enables the subscribers to enjoy an assortment of services from various service providers based on a single registration from any registration centre. Previously, a subscriber had to register from each service provider individually to avail respective services relying on single server authentication. In the past, a number of multi-server authentication techniques can be witnessed that employed lightweight and even computationally intensive cryptographic operations. In line with this, Zhu has presented a chaotic map based multi-server authentication scheme recently, which is not only vulnerable to denial-of-service attack, stolen-verifier attack, but also lacks anonymity. This research aims at improving the Zhu's protocol in terms of cost and efficiency. Moreover, the comparative study is presented for the performance of improved model against the existing scheme, and the security of proposed model is formally proved using BAN Logic.