• Journal of the Korean Society for Nondestructive Testing
• /
• v.32 no.6
• /
• pp.661-668
• /
• 2012

Wireless sensor network is one of prospective methods for railway monitoring due to the long-term operation and low-maintenance performances. How to supply power to the wireless sensor nodes has drawn much attention recently. In railway monitoring, the idea of converting ambient vibration energy from vibration of railway track induced by passing trains to electric energy has made it a potential way for powering the wireless sensor nodes. In this paper, a bimorph cantilever piezoelectric energy harvester was designed based on a single degree-of-freedom model. Experimental test was also performed to validate the design. The first natural frequency of the bimorph piezoelectric energy harvester was decreased from 117.1 Hz to 65.2 Hz by adding 4 gram tip mass to the free end of the 8.6 gram energy harvester. In addition, the power generation of the piezoelectric energy harvester with 4 gram tip mass at resonant frequency was increased from 0.14 mW to 0.74 mW from $2.06m/s^2$ base excitation compared to stand-alone piezoelectric energy harvester without tip mass.

• Journal of Power Electronics
• /
• v.19 no.5
• /
• pp.1074-1086
• /
• 2019

This paper presents the design and implementation of an improved cascaded multilevel inverter topology with asymmetric DC sources. This experimental inverter topology is a stand-alone system with simulations and experiments performed using resistance loads. The topology uses four asymmetric binary DC sources that are independent from each other and one H-bridge. The topology was simulated using PSIM software before an actual prototype circuit was tested. The proposed topology was shown to be very efficient. It was able to generate a smooth output waveform up to 31 levels with only eight switches. The obtained simulation and experimental results are almost identical. In a 1,200W ($48.3{\Omega}$) resistive load application, the THDv and efficiency of the topology were found to be 1.7% and 97%, respectively. In inductive load applications, the THDv values were 1.1% and 1.3% for an inductive load ($R=54{\Omega}$ dan L=146mH) and a 36W fluorescent lamp load with a capacitor connected at the dc bus.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.39 no.11
• /
• pp.1169-1174
• /
• 2015

Risk-Risk-based inspection (RBI) has been developed in order to identify risky equipments that can cause major accidents or damages in large-scale plants. This assessment evaluates the equipment's risk, categorizes their priorities based on risk level, and then determines the urgency of their maintenance or allocates maintenance resources. An earlier version of the risk-based assessment software is already installed within the equipment management system; however, the assessment is based on examination by an inspector, and the results can be influenced by his subjective judgment, rather than assessment being based on failure probability. Moreover, the system is housed within a server, which limits the inspector's work space and time, and such a system can be used only on site. In this paper, the development of independent risk-based assessment software is introduced; this software calculates the failure probability by an analytical method, and analyzes the field inspection results, as well as inspection effectiveness. It can also operate on site, since it can be installed on an independent platform, and has the ability to generate an I/O function for the field inspection results regarding the period for an optimum maintenance cycle. This program will provide useful information not only to the field users who are participating in maintenance, but also to the engineers who need to decide whether to extend the lifecycle of the power machinery or replace only specific components.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.14 no.1
• /
• pp.155-160
• /
• 2019

In this paper, we propose an efficient grid-independent ESS control system through the control of renewable energy and agricultural ICT by utilizing the prediction of energy production and consumption. The proposed system is an integrated management system that can perform maintenance and monitoring by visualizing the accurate phase and data of power system. It can automatically cope, collect, process, and control the data. Also, it can analyze the power generation of solar power generation, consumption pattern of installed facilities, and operation trend of facilities. Further, it can predict the consumption of energy production and present the optimal energy management method by using the OpenAPI of the Korea Meteorological Administration, thereby reducing unnecessary energy consumption and operating cost.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.23 no.2
• /
• pp.77-85
• /
• 2018

Renewable energy has been increasingly used and widely acclaimed as one of the solutions to rampant environmental problems. Among numerous kinds of renewable sources, the penetration rate of the PV system is relatively higher than that of others due to ease of installation. However, one disadvantage of the PV system is its dependence on weather condition. The PV system is especially critical when it is used for standalone systems because it cannot operate when the power generated from a PV module is not enough. Therefore, PV systems are often used with an energy storage system, such as batteries, to store backup energy when the weather condition is insufficient to supply power to the system. Blackout time can be reduced by increasing the size of the energy storage system, but it is a trade-off with system cost. In this work, optimal sizing of a standalone PV system is proposed to supply power to the system without blackout. The sizing of PV modules and batteries is performed by a simulation based on actual irradiation data collected during the past five years. The Life cycle costing of each system is evaluated to determine an optimal set of PV modules and batteries among several different combinations. The standalone PV system designed by the proposed method can supply power to the system with no interruption as long as the weather condition is similar to those of the past five years.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.3
• /
• pp.459-464
• /
• 2023

The mobile house of this article is provided with stand-alone power system that uses photovoltaic energy and enables sensing and environmental monitoring. Excess power generated is stored in lithium batteries, which enable smooth operation of the mobile house even in environment in which solar energy cannot be used. The house has been designed that its systems can be operated continuously by diesel power generation even when photovoltaic energy cannot be generated due to long rainy season or heavy snow. BMS (batter management system) has been constructed for photovoltaic and power management, and monitors the charge/discharge and usage amount of photovoltaic energy. Various sensing data are recorded and transmitted automatically, and the design allows for wireless monitoring by means of computer and smartphone app. The container house proposed in this study enables efficient energy management by performing optimal energy operation in remote areas, parks, event venues, and construction sites where there is no system power source.

• Journal of the Korean Solar Energy Society
• /
• v.32 no.4
• /
• pp.24-33
• /
• 2012

Recently, finishing materials at spandrel area, a part of curtain-wall system, are gradually forced to improve thermal insulation performance in order to enhance the building energy efficiency. Also, Building Integrated Photovoltaics(BIPV) systems have been installed in the exterior side of the spandrel area, which is generally composed of windows. Those BIPVs aim to achieve high building energy efficiency and supply the electricity to building. However, if transparent BIPV module is combined with high insulated spandrel, it would reduce the PV efficiency for two major reasons. First, temperature in the air space, located between window layer and finishing layer of the spandrel area, can significantly increase by solar heat gain, because the space has a few air density relative to other spaces in building. Secondly, PV has a characteristics of decreased Voltage(Voc and Vmp) with the increased temperature on the PV cell. For these reasons, this research analyzed a direct interrelation between PV Cell temperature and electricity generation performance under different insulation conditions in the spandrel area. The different insulation conditions under consideration are 1) high insulated spandrel(HIS) 2) low insulated spandrel(LIS) 3) PV stand alone on the ground(SAG). As a result, in case of 1) HIS, PV temperature was increased and thus electricity generation efficiency was decreased more than other cases. To be specific, each cases' maximum temperature indicated that 1) HIS is $83.8^{\circ}C$, 2) LIS is $74.2^{\circ}C$, and 3) SAG is $66.3^{\circ}C$. Also, each cases yield electricity generation like that 1) HIS is 913.3kWh/kWp, 2) LIS is 942.8kWh/kWp, and 3) SAG is 981.3kWh/kWp. These result showed that it is needed for us to seek to the way how the PV Cell temperature would be decreased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.8
• /
• pp.1-7
• /
• 2018

A folding solar power system is a stand-alone system and is a structure with solar panels attached. It consists of supporting parts and folding parts for ease of movement. While the efficiency of solar panels is also important to produce electricity by maximizing the power efficiency of solar panels, the most important thing is structure stability. The folding solar power structure intended to be developed in this study is a collapsible structure that is easy to move and install into systems that can produce electricity from grid to independent. Since these structures are installed outdoors, wind loads, snow cover, etc. In this paper, the wind loads most affected by the folding solar power generation structure were obtained using the MeshFree Finite Element Method. MeshFree is a program that makes it easier for users to interpret by simplifying the mesh tasks required by an existing analysis. The analysis showed that the greater the angle of inclination of the wind to the ground, the greater the wind load. In addition, reliability was ensured by wind load testing.

• (The) Research of the performance art and culture
• /
• no.32
• /
• pp.489-524
• /
• 2016

This study examines the birth of a genre, the $Sekky{\bar{o}}bushi$ Misemono Opera, focusing on how it accepted and modernized Katarimono $Sekky{\bar{o}}bushi$. Unlike earlier studies, it argues that Terayama was clearly different from other first-generation Angura artists, in that he rebirthed the medieval story $Sekky{\bar{o}}bushi$ as a modern Misemono Opera. Shintokumaru (1978) was directed by Terayama $Sh{\bar{u}}ji$, a member of the first generation of Japan's 1960s Angura Theatre Movement. It takes as its subject the Katarimono $Sekky{\bar{o}}bushi$ Shintokumaru, a story set to music that can be considered an example of the modern heritage of East Asian storytelling. $Sekky{\bar{o}}$ Shintokumaru is set in Tennoji, Japan. The title character Shintoku develops leprosy as a result of his stepmother's curse and is saved through his fiancee Otohime's devoted love and the spiritual power of the Bodhisattva Avalokitesvara. In this work, Terayama combined the narrative style of $Sekky{\bar{o}}bushi$ with J.A. Caesar's shamanistic rock music and gave it the subtitle 'Misemono Opera by $Sekky{\bar{o}}bushi$'. He transforms its underlying theme, the principle of goddesses and their offspring in a medieval religious world and the modori (return) instinct, into a world of mother-son-incest. Also, the pedestrian revenge scene from $Sekky{\bar{o}}bushi$ is altered to represent Shintokumaru as a drag queen, wearing his stepmother's clothes and mask, and he unites sexually with Sensaku, his stepbrother, and ends up killing him. The play follows the cause and effect structure of $Sekky{\bar{o}}bushi$. The appearance of katarite, a storyteller, propelling the narrative throughout and Dr. Yanagida Kunio is significant as an example of the modern use of self-introduction as a narrative device and chorus. Terayama $Sh{\bar{u}}ji^{\prime}s$ memories of desperate childhood, especially the absence of his father and the Aomori air raids, are depicted and deepened in structure. However, seventeen years after Terayama's death, the version of the play directed by Ninagawa Yukio-based on a revised edition by Kishida Rio, who had been Terayama's writing partner since the play's premier-is the today the better-known version. All the theatrical elements implied by Terayama's subtitle were removed, and as a result, the Rio production misses the essence of the diverse experimental theatre of Terayama's theatre company, $Tenj{\bar{o}}$ Sajiki. Shintokumaru has the narrative structure characteristic of aphorism. That is, each part of the story can stand alone, but it is possible to combine all the parts organically.