• Journal of the Society of Naval Architects of Korea
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• v.50 no.3
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• pp.145-152
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• 2013

Recently, with oil price jumping and environmental issues, Green ship is paid deep attention to by ship owner, operator, builder, class and government. Fuel efficiency and reduction of $CO_2$ emissions are expected to have a strong influence on the design and operation of merchant ships. Many ship owners and operators are seeking the more economic method by the best operating route and the application of reliable and effective energy saving devices. With the Energy Efficiency Design Index (EEDI) in 2013 attention will more than ever be focused at achieving maximum fuel economy in the hydrodynamic design of hull forms, their appendages and propellers. IMO requirements for $CO_2$ emission for ships will now be implemented for vessels ordered from 1st January 2013. So far, a lot of new idea and patents have been proposed, tested, claimed and applied for various kinds of ship type. This paper shows numerical and experimental work related to a study on a energy saving devices particularly for fuller ship such as merchant vessel of Tanker and Bulker. From the bare hull wake measurements, typical upper/lower asymmetry of hull wake at the propeller disk was found. The pre-swirl duct have been designed and reviewed to recover the loss of propeller running in that condition. The general function of the pre-swirl duct was set to work against this asymmetry of wake and generate pre-swirled flow into the propeller against the propeller rotating direction.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.1-7
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• 2015

The environmental regulations for CO2 emissions from the ship have been established recently, and fuel oil price has been increased continuously. In order to overcome these circumstances, Energy Saving Devices (ESDs) have been developed continuously to reduce the fuel oil consumption and improve the propulsive efficiency. This paper describes the trial performance of PBCF (Propeller Boss Cap Fins), SCHNEEKLUTH duct, Asymmetric rudder bulb and Mewis duct applied to handy-size bulk carriers. As a result, SCHNEEKLUTH duct is more effective than other energy saving devices at the reducing the fuel oil consumption and the improvement of the propulsive efficiency. In addition, it is confirmed that SCHNEEKLUTH duct is really effective in the vibration of the deck house. And the fuel oil consumption can also be reduced through main engine de-rating.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.774-777
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• 2005

In this paper, a constant frequency phase shifting PWM controlled voltage source full bridge-type series load resonant high-frequency inverter using the IGBT power modules is presented for innovative consumer electromagnetic induction heating applications such as a hot water producer, steamer and super heated steamer. The full bridge arm side link passive quasi-resonant capacitor snubbers in parallel with the each power semiconductor device and high frequency AC load side linked active edge inductive snubber-assisted series load resonant tank soft switching inverter with a constant frequency phase shifted PWM control scheme is discussed and evaluated on the basis of the simulation and experimental results. It is proved from a practical point of view that the series load resonant and edge resonant hybrid high-frequency soft switching PWM inverter topology, what is called class DE type. including the variable-power variable-frequency(VPVF) regulation function can expand zero voltage soft switching commutation range even under low output power setting ranges, which is more suitable and acceptable for induction heated dual packs fluid heater developed newly for consumer power utilizations. Furthermore, even in the lower output power regulation mode of this high-frequency load resonant tank high frequency inverter circuit it is verified that this inverter can achieve ZVS with the aid of the single auxiliary inductor snubber.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1959-1961
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• 2002

Requirements for high-efficiency equipment for energy saving are rapidly increasing recently keeping pace with development of digital and semiconductor technology. Accordingly, there are many changes and development in ballast. Ballast currently in use are Magnetic ballast (Coiled Type) and Electronic ballast. Electronic ballast produces incredible energy saving effect, but falls short of confidence instead. In addition, use at higher frequency through switching device creates Electromagnetic Interference (EMI) and high frequency. EMI creates low quality of equipment, damage in facilities and low productivity by leading miss operation of equipment, and interferes with surrounding machines. In this analysis I am going to examine characteristics of EMI on the Electronic ballast of FLR32SS one type pursuant to annex 3 of Electric Goods Technology Standard, and counter technology.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2388-2390
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• 2002

Small type electric energy saving system is proposed in this paper. The system improves power factor fastly according to load variation of each customer. Phases of voltage and current are detected as 1[ms] unit. Phase coincident algorithm is applied for power factor improvement. Capacitance is controlled for optimal power factor correction. Series reactor is controlled for harmonics reduction. Non-contact device is used for fast response and long life. Test result shows the effect of this system. Power factor of 40[W] electric fan is improved from 95[%] to 100[%]. In the case of electric light, power factor is improved from 82[%] to 100[%]. Response time for load variation is less than 1[ms].

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.535-537
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• 2009

As a kind of high Tc superconductor application technique, a study on the development of energy storage device system using BiPbSrCaCuO superconductor was performed. Chemical melt process was developed to gabricate the high magnetization superconductor which is needed to develop the energy saving system and the effect of various process variable on the superconducting properties of the specimens were tested and analyzed. Magnetochemical interactions between superconductor and permanent magnet was also experimented.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.110-110
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• 2017

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.3
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• pp.205-211
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• 2014

Interests on energy saving devices (ESDs) have been increased with the concern of the energy efficiency design index (EEDI) developed by the international maritime organization (IMO). To study the influence of ESDs, KVLCC2 with energy saving pre-swirl stator (PSS) was selected. To validate the computations, computed nominal wake of the model scale ship was compared with the experimental data, and the numerical uncertainty assessment was done for the full scale ship computations. The PSS changed rotational flow, which was assistant to the propeller thrust for the model and full scale ships. Performances of the full scale ships were predicted by ITTC methods, and new prediction method was proposed.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.946-951
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• 2009

The research aims to study a new, optimum and renewable energy application method that can cover the minimum energy and operation costs within a range of school budgets. By deriving the optimum application method, it is expected to maximize the cooling/heating and water heating energy saving efficiencies for educational facilities. Therefore, this research carried out a study on the new/renewable energy utilization technique diffusion expansion method and the optimum method. As a result, the first optimum plan was introduced with the multi-type geothermal heat pump 174kW + solar heat collector $94\;m^2$ + highly efficient electronic cooling/heating device (EHP) 249.4kW. On the other hand, the second optimum plan was induced as the multi-type geothermal heat pump 255.2kW + highly efficient electronic cooling/heating device (EHP) 168.2kW.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2218-2229
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• 2015

Recently Wi-Fi Alliance defined Wi-Fi direct, which can communicate through a direct connection between the mobile device anytime, anywhere. In Wi-Fi direct, all devices are categorized by group of owner (GO) and client. Since portability is emphasized in Wi-Fi direct devices, it is essential to control the energy consumption of a device very efficiently. In order to avoid unnecessary power consumed by GO, Wi-Fi direct standard defines two power management schemes: Opportunistic power saving scheme and Notice Of Absence (NOA) scheme. But, these two schemes do not consider the traffic pattern, so we cannot expect high energy efficiency. In this paper, we suggest an algorithm to enhance the energy efficiency of Wi-Fi direct power saving, considering the characteristics of multimedia video traffic. Proposed algorithm utilizes the statistical distribution for the size of video frames and adjusts the length of awake interval dynamically. Also, considering the inter-dependency among video frames, the proposed algorithm assigns priorities to video frames and ensures that a video frame with high priority is transmitted with higher probability than other frames with low priority. Simulation results shows that the proposed method outperforms the traditional NOA in terms with average delay and energy efficiency.