Young-Geun Kim

The Bigdata Processing Environment Building for the Learning System

In order to create an environment for Apache Hadoop for parallel distributed processing system of Bigdata, by connecting a plurality of computers, or to configure the node, using the configuration of the virtual nodes on a single computer it is necessary to build a cloud fading environment. However, be constructed in practice for education in these systems, there are many constraints in terms of cost and complex system configuration. Therefore, it is possible to be used as training for educational institutions and beginners in the field of Bigdata processing, development of learning systems and inexpensive practical is urgent. Based on the Raspberry Pi board, training and analysis of Big data processin g, such as Hadoop and NoSQL is now the design and implementation of a learning system of parallel distributed processing of possible Bigdata in this study. It is expected that Bigdata parallel distributed processing system that has been implemented, and be a useful system for beginners who want to start a Bigdata and education.

The Design of Method for Efficient Processing of Small Files in the Distributed System based on Hadoop Framework

Hadoop framework was designed to be suitable for processing very large files. On the other hand, when processing the Small Files, it waste the resource of a distributed system, and occur performance degradation. It is shown noticeable the more the Small Files. This problem is caused by the Small Files, it can be solved through the merging of associated Small Files. But a way of merging of Small Files has some limited point. in this paper, examines existing limit of merging method, design merging method Small Files for effective process.

Intelligent Self Learning System for Keyboard Instrument using a Smartphone

This intelligent keyboard instrument self learning system developed in this study consists of smartphone based learning application and keyboard-instrument auxiliary module. The keyboard instrument auxiliary module receives playing information of the instrument through smartphone application and bluetooth communication. Then the module shows it through LED display so that the relationship between the keyboard and scale could be easily recognized even for beginners. Also, this system provides saving function and analyzing function of users performance data, making learning more effective.

Learning System for Big Data Analysis based on the Raspberry Pi Board

In order to construct a system for big data processing, one needs to configure the node by using network equipments to connect multiple computers or establish cloud environments through virtual hosts on a single computer. However, there are many restrictions on constructing the big data analysis system including complex system configuration and cost. These constraints are becoming a major obstacle to professional manpower training for big data areas which is emerging as one of the most important national competitiveness. As a result, for professional manpower training of big data areas, this paper proposes a Raspberry Pi Board based educational big data processing system which is capable of practical training at an affordable price.

Analysis and experimental study for current break systems in a load break switch of RMU

Ring Main Unit(RMU) with a load break switch is designed to meet the growing requirements for oil - free, maintenance free, long life, maximum safety and future feeder automation application. SF6 gases as insulating and arc-quenching medium ensure the positive breaking of small current, main active load current, cable charging current, magnetizing current etc. The closing and opening motion of the switch is completed by a rotating shaft within several tens of milliseconds. Therefore, it is very difficult for product developer to observe the arc phenomena caused by the magnetic forces between two contacts. In this paper, to determine the characteristics of magnetic forces applied in the system of load break switch, electromagnetic analysis is performed on the load break switch contained permanent magnet. Experimental verification of arc phenomena using high speed camera is carried out as well.

Study on back to back capacitive current switching of 36kV vacuum circuit breaker

Back-to-back capacitive bank switching is the most severe duty among capacitive current switching duties because the amplitude of the inrush current with high frequency is very large. In this paper, 36kV back-to-back capacitive current switching tests of test duty 2(BC2) were carried out with vacuum circuit breaker. And the tests were performed with a series of separate making tests of 120 operations followed by a series of CO tests of 120 operations due to limitations of the test plant according to IEC standards 62271-100. The two types of VCB were tested with single phase and the test results were compared in terms of pre-arcing time, break down voltage distribution, contact surface after tests, contacting area, and field enhancement factor.

A study on electrical lifespan of VI by means of calculation of arc energy during arcing time in synthetic tests

This study focused on the evaluation of electrical lifespan of vacuum interrupter by means of calculation of arc energy during arcing time. The repetitive short circuit current breaking tests with synthetic test devices were conducted until the contact could not break the short circuit current to identify the limit of electrical life. As a result, the accumulative arc energy was calculated after tests. Moreover, arc energy in short circuit current breaking tests were calculated and compared with the results of synthetic tests.

A comparative study on electrical and thermal stress distribution across fundamental components of conventional and superconducting hybrid type HVDC circuit breakers

Super grids are considered to be the technology of the future that will allow transmission and trade of huge volumes of electricity over long distances. HVDC is the preferred choice for developing super grids as HVAC transmission of bulk power over long distances is less efficient. However, the key obstacle in developing HVDC super grids is the absence of HVDC circuit breakers (DCCB) which can quickly detect and isolate the fault. The huge electrical and thermal stresses subjected to DCCB during DC current interruption are one of the primary challenges in developing DCCB. Especially, IGBT valves in hybrid DCCB are the most expensive and sensitive part and their cost drastically increase with their maximum rating. This research paper presents a comparative study on the electrical and thermal stress distribution across IGBT valves of conventional hybrid DCCB (CDCCB) and Superconducting hybrid DCCB (SDCCB) during fault conditions. Realistic CDCCB and SDCCB models were developed by considering the characteristic values of commercially available IGBT module. To create the electrical and thermal stress profiles, CDCCB and SDCCB were placed in HVDC test bed model and transient simulations were performed. The voltage distribution, current distribution and energy dissipation profiles across IGBT valves were developed for CDCCB and SDCCB. Comparative analysis of the profiles showed that the SDCCB components were subjected to relatively lower electrical and thermal stresses.

Study on the low voltage DC short-circuit test and DC test equipment

Recently power plant using renewable energy such as photovoltaic power, fuel cell and wind power is being increased. Accordingly research and development of DC distribution system and power equipment has been actively performed. Specially the study for test method and test equipment which can verify the performance of protection device breaking the short-circuit direct current is required. This paper describes the method of DC testing and the construction of test system which can be satisfied with the relevant standards.

A study on compact shunt release device of MCCB using a voltage detecting circuit with hysteresis

MCCB (Molded Case Circuit Breaker) is widely used in power distribution systems for protecting an electrical circuit from damage caused by overload or short circuit. The shunt release device, an internal accessory of MCCB, opens the mechanism in response to an externally applied voltage signal. The shunt release device consists of an actuator and a control circuit. The conventional shunt release device has two bodies for each part. In order to make it one, the compact actuator and a voltage detecting circuit with hysteresis are developed. To minimize the size and improve performance, the electromagnetic force of compact Actuator has been analyzed by means of Maxwell. This analytic model is validated by comparing the simulation results and the experimental results. The voltage detecting circuit with hysteresis consists of input, hysteresis, output, reference, signal circuit and transistors. It estimates the level of input voltage without additional power source. In this paper, compact shunt release device with voltage detecting circuit with hysteresis is introduced. The compact shunt release device makes it possible for installing maximum quantity of MCCB in a panel. We found that performance and operation reliability was improved compared to the conventional shunt release device.