• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.2
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• pp.89-94
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• 2014

Tidal generation has become one of environmentally friendly new and renewable future sources of energy. The Sihwa Tidal Power Plant in South Korea, which was imported from abroad by turnkey type in 2011, connected to the power system in 2012, and is currently under commercial operation. However, leading companies are reluctant to disclose their technologies associated with the control systems and are not cooperative in technology transfers, making it a high priority to develop core technologies in South Korea. In order to develop a start stop control system for tidal generation, this paper presents the optimal algorithm for decision making and prototype of hardware design. First, control systems in tidal power, such as plant operation control, data interfaces between systems, monitoring and control points of the control system, are analyzed. The software development and PC based emulator processes for optimization algorithm processing are described. Finally, verification of the algorithm implementation, hardware platform for start stop control device, and implementation of prototype control system were discussed.

• Journal of Ocean Engineering and Technology
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• v.32 no.6
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• pp.518-526
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• 2018

As a new technical approach, this paper introduces a method for improving an electrically propelled outboard motor in consideration of the driving system applied to an electric-propulsion boat with solar cell energy. The most efficient model for a drive shaft, propeller shaft, and bevel gear was suggested and examined with respect to the results of test operation in prototype mode. Furthermore, this research included a performance evaluation of the manufactured prototype to acquire the purposed quantity value and the development items. After manufacturing the desired prototype of an electrically propelled outboard motor, the maximum sail time, thrust force, noise, and weight were evaluated in a performance test. An additional test in relation to the maximum sail speed (knots) of the completed prototype was conducted using a sea trial evaluation to acquire the optimum quantity.

• IEMEK Journal of Embedded Systems and Applications
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• v.11 no.2
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• pp.87-95
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• 2016

Nonvolatile memory (NVM) is being considered as an alternative of traditional memory devices such as SRAM and DRAM, which suffer from various limitations due to the technology scaling of modern integrated circuits. Although NVMs have advantages including nonvolatility, low leakage current, and high density, their inferior write performance in terms of energy and endurance becomes a major challenge to the successful design of NVM-based memory systems. In order to overcome the aforementioned drawback of the NVM, extensive research is required to develop energy- and endurance-aware optimization techniques for NVM-based memory systems. However, researchers have experienced difficulty in finding a suitable simulation tool to prototype and evaluate new NVM optimization schemes because existing simulation tools do not consider the feature of NVM devices. In this article, we introduce a NVM-based cache simulator to support rapid prototyping and evaluation of NVM-based caches, as well as energy- and endurance-aware NVM cache optimization schemes. We demonstrate that the proposed NVM cache simulator can easily prototype PRAM cache and PRAM+STT-RAM hybrid cache as well as evaluate various write traffic reduction schemes and wear leveling schemes.

• Progress in Superconductivity and Cryogenics
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• v.15 no.4
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• pp.44-47
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• 2013

We had proposed a winding method so called "Wind-and-Flip", which enables a persistent current operation of an HTS pancake coil without any electrical joint. In order to improve the magnetic field drift characteristics, a prototype HTS coil with the technique was fabricated, and tested under various temperatures. Because the coil doesn't have any electric terminals for current leads, an HTS background magnet was used to induce the persistent current in the coil by field cooling process. A conduction cooling system with a GM cryocooler was prepared to keep the operating temperatures of the prototype coil much below the 77 K. We investigated the magnetic field drift characteristics under the various operating temperatures by measuring the center magnetic field with a cryogenic Hall sensor. The persistent current mode operation at 20 ~ 50K showed a strong possibility of the winding technique for the application such as MRI or NMR.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.184-190
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• 2014

Fuel cell power system, unlike conventional energy sources, converts chemical energy into electrical energy through electrochemical reaction of hydrogen and oxygen. In recent years, railway field as well as mobile fuel cell power system is being studying actively with development of hydrogen storage technologies. This paper presents the feasibility study on small-scale prototype electric railway vehicle application using fuel cell generation system. it is confirmed that proposed fuelcell-battery hybrid system shows good response characteristic about speed and torque based on design of parameter on system. Also as results of response for proposed system modeling, it show that powering mode and braking mode of system is controlled by switching devices of converters.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.10a
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• pp.259-260
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• 2012

With increasing interest in alternative energy source for green growth, this document shows that the study of kite flight control is based on the concept of autonomous flight of kite can exploit the energy. Currently, prototype kite was designed and the purpose of its flight test, by manual flight control with Remote Controller, was performed for the feasibility of the full automatic flight control. For the future research, the test data should be collected through the many flight test under various environment.

• Journal of Sensor Science and Technology
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• v.28 no.4
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• pp.205-215
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• 2019

A flexible polyvinylidene fluoride (PVDF)/polydimethylsiloxane (PDMS) composite prototype with high piezoelectricity and force sensitivity was constructed, and its huge potential for applications such as biomechanical energy harvesting, self-powered health monitoring system, and pressure sensors was proved. The crystallization, piezoelectric, and electrical properties of the composites were characterized using an X-ray diffraction (XRD) experiment and customized experimental setups. The composite can sustain up to 100% strain, which is a huge improvement over monolithic PVDF fibers and other PVDF-based composites in the literature. The Young's modulus is 1.64 MPa, which is closely matched with the flexibility of the human skin, and shows the possibility for integrating PVDF/PDMS composites into wearable devices and implantable medical devices. The $300{\mu}m$ thick composite has a 14% volume fraction of PVDF fibers and produces high piezoelectricity with piezoelectric charge constants $d_{31}=19pC/N$ and $d_{33}=34pC/N$, and piezoelectric voltage constants $g_{31}=33.9mV/N$ and $g_{33}=61.2mV/N$. Under a 10 Hz actuation, the output voltage was measured at 190 mVpp, which is the largest output signal generated from a PVDF fiber-based prototype.

• Journal of Sensor Science and Technology
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• v.23 no.3
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• pp.197-201
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• 2014

TEPC (Tissue Equivalent Proportional Counter) was usually used for high LET radiation dosimetry. We developed a prototype TEPC for micro-dosimetry in the range of $0.2{\sim}300 keV/{\mu}m$. And, the simulated site diameter of the TEPC is $2{\mu}m$, of similar size to a cell nucleus. For purposes of characterization the response for high LET radiation of the TEPC has been investigated under 135MeV/u Carbon ions in HIMAC (Heavy Ion Medical Accelerator). We determined the gas multiplication factor and measured the lineal energy spectrum [yd(y)] of 135 MeV/u Carbon ions. The value of the gas multiplication factor was 315 at 700 V bias voltage. As a result of the experiment, we could more understand the performance of the TEPC for high LET (Linear Energy Transfer) radiation. And the procedure of high LET radiation dosimetry using TEPC is established.

• Nuclear Engineering and Technology
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• v.49 no.4
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• pp.855-864
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• 2017

The control rod assembly controls reactor power by adjusting its position during normal operation and shuts down chain reactions by its free drop under scram conditions. Therefore, the drop performance of the control rod assembly is important for the safety of a nuclear reactor. In this study, the drop performance of the conceptually designed control rod assembly for the prototype generation IV sodium-cooled fast reactor that is being developed at the Korea Atomic Energy Research Institute as a next-generation nuclear reactor was experimentally investigated. For the performance test, the test facility and test procedure were established first, and several free drop performance tests of the control rod assembly under different flow rate conditions were then carried out. Moreover, performance tests under several types and magnitudes of seismic loading conditions were also conducted to investigate the effects of seismic loading on the drop performance of the control rod assembly. The drop time of the conceptually designed control rod assembly for 0% of the tentatively designed flow rate was measured to be 1.527 seconds, and this agrees well with the analytically calculated drop time. It was also observed that the effect of seismic loading on the drop time was not significant.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.111-115
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• 2012

In this paper, a solar energy powered bicycle linked to a wireless sensor network (WSN) which monitors the transfer of solar energy to an electrical energy storage unit and an analysis of its effectiveness is proposed. In order to achieve this goal, a solar-powered bicycle with an attached ZigBee and a far-end wireless network supervisory system is setup. Experimental results prove that our prototype, solar energy powered bicycle, can achieve enough solar energy for charging a two lead-acid battery pack. As a result, the user, through use of a wireless network in the parking period can be kept aware of the data on the amount of immediate solar radiation, the degree of illumination, the ambient temperature, and electrical energy storage capacity information of the bicycle through an internet interface.