• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.565-569
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• 2003

One-year-long groundwater-level data have been collected from 18 wells in Cheon-an area. The result of barometric efficiency, autocorrelation, cross-correlation and statistical distribution evaluated from the measurement data shows that groundwater-level measurements from observation wells are the principal source of information about aquifer characteristics. Data from WA-2 has high barometric efficiency as well as steady decreasing auto-correlation coefficient, which means nonleaky confined aquifer, Most aquifers in this study show the unconfined properties so that barometric efficiencies are mostly low and the coefficients of cross-correlation between groundwater-level and precipitation are commonly high. This study showed that the long-term groundwater-level monitoring data without artificial stress such as pumping would give accurate information about aquifer characteristics.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.10a
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• pp.39-40
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• 2011

The 62nd session of the MARINE Environment Protection Committee was held in London from 11 to 15 July 2011. Mandatory measures to reduce emissions of greenhouse gases (GHGs) from international shipping were adopted at the Committee. The amendment to MARPOL Annex VI includes a new chapter 4 to make mandatory the Energy Efficiency Design Index (EEDI) for new ships and the Ship Energy Efficiency Management Plan (SEEMP) for all ships. This first mandatory measures on energy efficiency will enter into force on 1 January 2013. This amendment to MARPOL Annex VI will significantly influences the vast majority of the international maritime community. This paper mainly discusses the main results of MEPC 62nd session including the recent Emission Control Area.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.05a
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• pp.123-127
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• 1999

This paper suggests the establishment of high-accuracy and high-efficiency machining method of scroll shape workpiece by using the feed control method. The cutting paths for machining the inside and outside surfaces of the scroll-shape workpiece are calculated, and the calculation method of the cutting chip areas based on the coordinate of the base circle is shown. A feed control method is proposed for a constant cutting area and cutting force. By machining test of scroll shape workpiece, The machined accuracy of wrap, tool wear, and surface roughness are evaluated. By this method, Reduction of the machining time and large increase of the efficiency can be expected.

• Journal of KIEE
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• v.11 no.1
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• pp.46-50
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• 2001

In order to improve the luminous efficiency in ac PDP(Plasma Display Panel), we have suggested the new structures of sustain electrodes with waffle-type barrier ribs and the discharge current for a given pulse voltage has been decreased by eliminating the electrode area which has nothing to do with visible light emission area compared with conventional structure. As a result, the luminous efficiency was improved about 30% compared with the conventional structure.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.305-308
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• 2007

The field of dye-sensitized solar cell (DSC) is being researched actively at present. Because DSC has several advantages to pass the limits of Si solar cells such as a low manufacturing expense, a simple manufacturing process and its transparency. A lot of researches are underway about materials and processes in the field of dye-sensitized solar cell but its structure has been fixed up as the sandwich structure that both edges are used as positive and negative terminals. But the structure as of present is a factor of decreasing efficiency because the more electrons are recombined the further distance from terminal, considering about the characteristic of dye-sensitized solar cell that electrons generated inside cell are moved by diffusion. In this study, we made experiment on expanding the terminal to shorten internal moving distance of electron and compared the results according to the variation of active area to find out the effect of this trial. As a result, we achieved about 15.5% improvement of maximum power and 0.5% improvement of efficiency from terminal-expanded dye-sensitized solar cell of $2cm^{2}$ active area and concluded that the increasing rate of efficiency is raised as the active area becomes wider.

• Korean Institute of Interior Design Journal
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• v.20 no.4
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• pp.183-190
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• 2011

Lately majority of churches have preferred to enlarge their worship area to both horizontal and vertical axis. According to expand their area which brings more devotees to the limited service area. Transform from a small church into a large church is no longer unprecedented issue in South Korea. As the size of church getting bigger, many unexpected issues become matters. One of the significant problem is that the number of people have experienced either fall a sleep or feel a doziness during their service period. Due to the limited condition for the specific building type such as religion facility(church), IAQ improvements is seriously concerned. Therefore, we are going to examine by using simulation tool, CF, a difference of ventilation efficiency about the location and number of windows, and find the best way of the ventilation efficiency in a multi-stories type church by changing the exhaust pipes location and size. Furthermore, in this thesis, by changing a ceiling height from the existing building to confirm that $CO_2$ have been satisfied for both the ventilation efficiency and IAQ.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.171-177
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• 2004

Voltage step-down characteristics in Ring/Dot type piezoelectric transformer were examined as a function of the area of input electrode when the area of output electrode is fixed. The effects of driving frequency and load resistance on the voltage step-down characteristics were also examined. Voltage gain was greatly dependent on the driving frequency and load resistance, and showed a maximum gain at resonance frequency of the step-down transformer. The frequency where the maximum cutout voltage appears increased about 0.2％ as the load resistance increased from 10 to 150 Ω. As the area of input electrode increased, the voltage gain and the efficiency of the transformer increased. Frequency dependence of efficiency of the step-down transformer revealed a similar tendency with the voltage gain curves. The maximum efficiency remarked 94% when the input voltage and the load resistance were 20 Vpp and 120 Ω, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.11
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• pp.1151-1158
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• 2014

In this paper, a concatenated frame algorighm for improving transmission efficiency in WiMedia protocol is studied. And an efficient transmission scheme to reduce the degradation of network performance by the loss of mini-frame is proposed in this paper. The proposed scheme can reduce total energy consumption and improve the transmission efficiency since it only retransmits mini-frame in which error is occurred. The simulation results show that proposed protocol can enhance the throughput performance and improve energy efficiency by minimizing the retransmission of mini-frame.

• Journal of Power Electronics
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• v.11 no.3
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• pp.335-341
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• 2011

This paper presents an improved orientation strategy for energy-efficiency in photovoltaic (PV) panels. Conventionally, PV panels are tilted with the site's latitude angle or the difference between the latitude angle and the solar declination angle. A monthly-based orientation strategy has been proposed and analyzed in this study. The proposed strategy implies that the PV panels are tilted with the monthly-based angle that achieves the maximum incident radiation. Furthermore, the impact of using the proposed orientation strategy and three conventional strategies on the produced power and on the PV system design features has been investigated in detail. A Japanese city (Fukuoka) and an Egyptian city (Al-Kharijah) have been considered as locations for the PV power system installation. The results showed that the proposed strategy achieved an increase in the power produced from the PV power systems at the two different sites, and consequently the required solar cells area can be saved. Therefore, the cost of the PV power system components can be reduced including the solar cells area and the land area.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.722-725
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• 2004

Voltage step-down characteristics in Ring/Dot type piezoelectric transformer were examined as a function of the area of input electrode when the area of output electrode is fixed. The effects of driving frequency and load resistance on the voltage step-down characteristics were also examined. Voltage gain was greatly dependent on the driving frequency and load resistance, and showed a maximum gain at resonance frequency of the step-down transformer. The frequency where the maximum output voltage appears increased about 0.2% as the load resistance increased from 10 to $150\Omega$. As the area of input electrode increased, the voltage gain and the efficiency of the transformer increased. Frequency dependence of efficiency of the step-down transformer revealed a similar tendency with the voltage gain curves. The maximum efficiency remarked 94% when the input voltage and the load resistance were 20 $V_{PP}$ and $120\Omega$, respectively.