• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.226-228
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• 2006

This paper presents the two lossless auxiliary inducors-assisted voltage source type half bridge(single ended push pull:SEPP) series resonant high frequency inverter for induction heated fixing roller in copy and printing machines. The simple high-frequency inverter treated here can completely achieve stable zero current soft switching (ZCS) commutation forwide its output power regulation ranges and load variations under constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operatprinciple is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZCS operation commutation, together with its output effective power regulation charactertics-based on the high frequency PDM strategy. The experimenoperating performances of this voltage source SEPP ZCS-PDM series resonant high frequency inverter using IGBTs are illustrated as compared with computer simulation results and experimenones. Its power losses analysis and actual efficiency are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliimplemented here is proved from the practical point of view.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1081-1086
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• 2007

It is strongly requested to reduce fuel consumption because of high oil price and exhaust gases of road vehicles for environmental preservation. To solve these problems, several types of hybrid vehicles have been developed. Among them, flywheel hybrid vehicle using variable displacement pump/motor was already proposed as one of the feasible hybrid systems in place of hybrid vehicle by the conventional storage battery. The proposed flywheel hybrid vehicle is to keep constant pressure of high pressure line by the control of swash plate angle of flywheel pump/motor as pressure compensator. The efficiency of the overall system depends severely on the efficiency of hydraulic pump/motor in the energy saving hydraulic control system by simulation. According to the control methods of swash plate angle of piston pump/motor, there remain several problems to be solved. In this paper, experimental setup for energy saving is fabricated and the efficiency of energy saving is investigated by experiments with respect to various experimental conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.6
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• pp.392-397
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• 2010

Energy loss from windows accounts for large scores of heating and cooling loads also in energy saving apartments that is reduced over 30% of total energy consumption. Movable reflective insulations, insulation shutters, blinds, insulated shades are used to reduce energy loads from windows. In this study, energy saving performance of insulated shades was simulated by control methods. According to installation of insulated shades, heating loads were decreased about 10.5~11.3%, and cooling loads are decreased about 29.1~38.3% on an energy saving apartment. The heating peak load was reduced about 9.5% by insulated shades and the cooling peak load was reduced about 25.7~31.5%. In the case of insulated shades with automatic control system, simple time schedule control system would be more efficient than outdoor detection control system that should use several sensors.

• Journal of Navigation and Port Research
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• v.39 no.2
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• pp.107-113
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• 2015

This paper analyzes and evaluates the importance of energy saving measures based on qualitative survey. Through literature review and group interviews with specialists, 4 factors, 13 measures for energy savings, and 4 evaluation criteria were selected to carry out an Analytic Hierarchy Process (AHP) analysis. At the first stage of AHP analysis, the importance of factors was derived, and then the importance of 13 measures. Lastly, the cross examination of 4 factors was carried out in order to evaluate the best possible qualitative considerations. The result revealed that 'choosing the best course weather', is the most important factor with the highest value on applicability and operational complexity criteria. These results may imply that operational considerations are regarded as a main factor to be taken into account when considering appropriate energy saving measures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.8A
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• pp.790-797
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• 2006

IEEE 802.16e specifies two different power saving modes(PSM). One is sleep mode and the other is idle mode. These modes are different in that whether a mobile node maintains its state information with the serving base station or not. This difference results in different efficiency in consuming battery power of a mobile terminal. Therefore, it becomes important to analyze the performance of each power saving mode considering the parameters affecting the power consumption. In this paper, we propose a performance modeling framework of sleep mode and idle mode in terms of power saving efficiency. The analytical results are verified by computer simulations that idle mode is superior to sleep mode in power consumption of mobile node.

• KIEAE Journal
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• v.13 no.4
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• pp.69-74
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• 2013

It is difficult to apply a design standard uniformly to university buildings because various education courses are conducted. However, a design guideline for saving energy is necessary in order to prepare for low-energy days. A library in any university is one of the buildings that a lot of people use and most of the energy is spent. Therefore, the investigation on the energy savings of library facilities is very important and urgent. This study finally presents the design guideline of those facilities for low-energy. In this paper, the trend of space layout, utilization schedule and performance of materials are investigated, and the impact on energy savings and effective energy saving strategies are analyzed and illustrated by energy simulation. As a result of energy analysis from the case of 'H' university, it is confirmed that the utilization schedule effects mostly to energy consumption and the layout and orientation of the rooms in the library are the major parameters. Among the investigated saving strategies, green roofs are found as the most effective part for heating energy savings, and outdoor air cooling is known as the most effective method for cooling energy savings.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.465-470
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• 2009

This study investigated the water saving technology for the toilet stool system in a water closet. Since in 21st century water would be the prospected factor to measure the wealth of a country instead of the oil, water saving technologies in the toilet stool in a closet system is getting more important than the cleaning stool and the reducing noise performances. According to the statistics in Korea the percentage of using water in toilet is about 27% to the total amount of water used. Therefore, this study theoretically approached the possible amount of water saving and suggested the new variable position straight trap device in the toilet stool system.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.33-38
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• 2009

Energy loss from windows accounts for large scores of heating and cooling loads also in energy saving apartments that is reduced over 30% of total energy consumption. Movable reflective insulations, insulation shutters, blinds, insulated shades are used to reduce energy loads from windows. In this study, energy saving performance of insulated shades was simulated by control methods. According to installation of insulated shades, heating loads were decreased about $10.5{\sim}11.3%$, and cooling loads are decreased about $11.0{\sim}15.5%$ on an energy saving apartment. The heating peak load was reduced about 9.5% by insulated shades, but the cooling peak load is hardly ever decreased. Because in the condition of cooling peak load, latent cooling loads accounts for large score of cooling loads. Difference of the energy loads by a schedule control method and an outdoor detection control was no more than 5% for a base model. In the case of insulated shades with automatic control system, simple time schedule control system would be more efficient than outdoor detection control system that should use several sensors.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.141-144
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• 2003

The mobile radio networks can be divided into networks that has the base station or the infrastructures like AP(Access Point) and Ad Hoc network that hasn't any infrastructures. As there aren't any fixed infrastructures in Ad Hoc Networks, mobile nodes should transmit the data only among mobile nodes themselves. To supplement these weakpoints of the two networks, many studies about Ad Hocs based on the 802.11 are in progress. In this thesis, we try to propose the efficiency of the suggested protocols by comparing and analyzing power saving protocols according to the Beacon intervals in multi hop Ad Hoc Networks based on IEEE 802.11.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.200-202
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• 2006

In this paper, a novel type of auxiliary active snubbing circuit assisted quasi-resonant soft-switching pulse width modulation inverter is proposed for consumer induction heating equipments. The operation principle of this high frequency inverter is described using switching modes and equivalent circuits. This newly developed series resonant high frequency inverter can regulate its high frequency output AC power under a principle of constant frequency active edge resonant soft-switching commutation by asymmetrical PWM control system. The high frequency power regulation and actual power conversion efficiency characteristics of consumer induction heating (IH) products using the proposed soft-switching pulse width modulation (PWM) series load resonant high frequency inverter evaluated. The practical effectiveness and operating performance of high frequency inverter are discussion on the basis of simulation and experimental results as compared with the conventional soft-switching high frequency inverter.