• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.1
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• pp.148-156
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• 2014

The objective of this study is to compare NOx emissions from light duty diesel vehicles measured from on-road tests that conducted under various driving routes and seasonal conditions. We measured real-driving NOx emissions using PEMS, portable emissions measurement system, under the urban, rural and motorway road traffic conditions. On-road tests were repeated at summer, fall and winter season. The accumulated driving distance is more than 1,200 km per each vehicle. Route average NOx emission factors were compared among nine route-season combinations. The emission characteristics of each combinations were investigated using time series mass emission rates and vehicle operation-based emission rates and activities, which is based on U.S. EPA's MOVES model. Most concerned route-season combination is "urban road condition at summer", which shows two to eleven times higher NOx emissions than other combinations. The emission rates and activities under low speed operating conditions should be managed in order to reduce urban-summer NOx. From a NOx control strategy perspective, the exhaust gas recirculation, EGR, is observed to be properly operated under wide range of vehicle driving conditions in Euro-5 vehicles, even if the air conditioner turns on. In high power demanding conditions, the effect of overspeeding could be more critical than that of air conditioner activation.

• Journal of the Korean Solar Energy Society
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• v.29 no.1
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• pp.18-23
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• 2009

We intend to describe a 12kW building-integrated photovoltaic system which was applied into the south wall of a new building. This study showed the results that were appeared from describing the PV module manufacture and installation process, and performing generation performance analysis of BIPV system. From the result we confirmed that the generation performance of the BIPV system was changed by season. The performance ratio(PR) was about 83.6% in winter and it means that performance of this BIPV system was so good in that season. On the other hand, the PR in summer was about 75.0% dropped about 8%. It was believed that the change was influenced by the reduction of solar radiation irradiated into the PV modules by installation position and rainy spell in summer. And we also confirmed that low irradiation condition is cause of the additional loss in the total PV system. In this case, the efficiency ratio of PCS drops significantly at low input loads and the average conversion efficiency of PCS in summer was 76.4% decreased about 10% from 86% in winter.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.431-433
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• 2000

The hydroelectric Power plant of the KOWACO have been establishing and operating a full scale electric power facility, doing the largest generation during the flood period of the summer season. When the huge capacity generator is run like the Chung-Ju's hydroelectric Power plant, the generator current per generator flows a great current estimated at 5,900 A. The bus bar of a great current flows in cubicle, owing to the bus bar current Eddy current is created around magnetic substance and a local heating phenomenon occurs due to Joule heat finally. a local heating phenomenon still exists the danger of safety accident due to contact and accompanies losses enough to healing capacity inevitably. this study applies and examines related theory and numerical formula about the heating cause of a great current & enforces technical verification about the method of heating reduction previous managed at the site.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.4
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• pp.227-233
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• 2014

Information presented in this study is intended to inform candidates as they prepare to design and structure the floatovoltaics solar power system. A developed floatovoltaics solar power generation results from the combination of PV plant technology and PV floating technology. This floating-based PV system is a new concept for PV development. The PV floating technology opens new opportunities to give value to unused areas so far while preserving valuable land for more adapted activities. Therefore the land-use conflicts are avoided and the environmental impact is minimized. Therefore the technology offers an interesting opportunity to regions facing on drought during summer time without any negative impact to the eco-system. This study describe the basic components of a floatovoltaics solar power system. A typical system consist of floating system and solar modules, a control device, rechargeable batteries, a load or device and the associated electrical connections. The floating system is specifically designed to keep all metallic components above water leaving only 100% recyclable, closed cell foam filled HDPE plastic floats in contact with the water. As the first case that can maximize the power generation efficiency of PV internationally, it is expected that this study will be utilized as a primary guide for future development of floating type PV system.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2637-2641
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• 2008

The ever increasing demand for power and the shortages encountered during summer calls for the implementation of strategies for power saving in industry. Inlet fogging of gas turbine engines is quite popular due to the ease of installation and the relatively low initial cost compared to other inlet cooling methods. In the present investigation, a detailed analysis is carried out on the basis of coincident wet bulb and dry bulb temperature data of a compressed air plant from April to October, 2007 to determine the evaporative cooling potential for the period. The power gain that can be obtained by employing inlet fogging of the air compressors is analyzed based on the real climatic data at several sites in Korea. An experimental set-up was constructed and tests were carried out with the standard impaction pin nozzle. The experimental results were found to match with the theoretical calculations.

• Journal of Digital Convergence
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• v.14 no.6
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• pp.457-466
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• 2016

To achieve eco-friendly hospitals it is necessary to empirically verify the effect of meteorological factors on the power consumption of the hospital. Using daily meteorological big data from 2009 to 2013, we studied the weather conditions impact to power consumption and analyzed the patterns of power consumption of two hospitals. R analysis revealed that temperature among the meteorological factors had the greatest impact on the hospital power consumption, and was a significant factor regardless of hospital size. The pattern of hospital power consumption differed considerably depending on the hospital size. The larger hospital had a linear pattern of power consumption and the smaller hospital had a quadratic nonlinear pattern. A typical pattern of increasing power consumption during a hot summer and a cold winter was evident for both hospitals. The results of this study suggest that a hospital's functional specificity and meteorological factors should be considered to improve energy savings and eco-friendly building.

• Journal of Radiation Protection and Research
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• v.32 no.2
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• pp.79-88
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• 2007

When an accident occurs at nuclear power plant and radionuclide material is released to the area around the plant, public evacuation is considered as a measure to protect the safety of the residents nearby. This study draws factors required to estimate evacuation time and make estimation of the time to evacuate all residents from the EPZ of Wolsong site in consideration of traffic condition in the neighborhood and on the basis of field data around the site for each factor. The traffic capacity and the traffic volume by season were investigated for the traffic analysis and simulation within EPZ of Wolsong site. As a result, the background traffic volume by season were established. To estimate TGT(Trip Generation Time), the questionnaire surveys were carried out for resident and transient. The TSIS code was applied to traffic analysis in the events of daytime/night and normal/adverse weather under normal day/summer peak traffic condition. The results showed that the evacuation time required for total vehicles to move out from EPZ took generally from 118 to 150 minutes. The evacuation time took longer maximum 17 minutes at night than daytime during summer peak traffic.

• Smart Media Journal
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• v.4 no.2
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• pp.55-61
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• 2015

A bandwidth-enhanced ultra-wide band (UWB) CMOS balun-LNA is implemented as a part of a software defined radio (SDR) receiver which supports multi-band and multi-standard. The proposed balun-LNA is composed of a single-to-differential converter, a differential-to-single voltage summer with inductive shunt peaking, a negative feedback network, and a differential output buffer with composite common-drain (CD) and common-source (CS) amplifiers. By feeding the single-ended output of the voltage summer to the input of the LNA through a feedback network, a wideband balun-LNA exploiting negative feedback is implemented. By adopting a source follower-based inductive shunt peaking, the proposed balun-LNA achieves a wider gain bandwidth. Two LNA design examples are presented to demonstrate the usefulness of the proposed approach. The LNA I adopts the CS amplifier with a common gate common source (CGCS) balun load as the S-to-D converter for high gain and low noise figure (NF) and the LNA II uses the differential amplifier with the ac-grounded second input terminal as the S-to-D converter for high second-order input-referred intercept point (IIP2). The 3 dB gain bandwidth of the proposed balun-LNA (LNA I) is above 5 GHz and the NF is below 4 dB from 100 MHz to 5 GHz. An average power gain of 18 dB and an IIP3 of -8 ~ -2 dBm are obtained. In simulation, IIP2 of the LNA II is at least 5 dB higher than that of the LNA I with same power consumption.

• Asian Journal of Atmospheric Environment
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• v.5 no.2
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• pp.134-143
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• 2011

The present study aimed to investigate the diurnal variations in air concentrations and exchange fluxes of ammoniacal nitrogen ($NH_x$: ammonia ($NH_3$) and particulate ammonium) in a subalpine deciduous forest in central Japan during a week in summer. The $NH_3$ concentrations ($0.50\;{\mu}g\;N\;m^{-3}$ on average) showed a clear circadian variation, i.e., high and low in the daytime and nighttime, respectively. The concentration of particulate ammonium in the coarse fractions was extremely low, whereas that for the PM2.5 fraction was relatively high $0.55\;{\mu}g\;N\;m^{-3}$ on average). The main inorganic ion components of PM2.5 at the study site were ammonium and sulfate. The exchange fluxes of $NH_x$ were bidirectional. Both the maximum and minimum values occurred in the daytime, i.e., $0.39\;mg\;N\;m^{-2}\;hr^{-1}$ of downward flux and $0.11\;mg\;N\;m^{-2}\;hr^{-1}$ of upward flux for $NH_3$ and $0.25\;mg\;N\;m^{-2}\;hr^{-1}$ of downward flux and $0.13\;mg\;N\;m^{-2}\;hr^{-1}$ of upward flux for PM2.5 ammonium. The exchange fluxes of $NH_x$ at night could be considered as zero. The mean deposition velocity during the research period was almost zero for both $NH_3$ and PM2.5 ammonium. The atmosphere-forest exchange of $NH_x$ in the forest during the study period was balanced. The remarkably large deposition of $NH_x$ was attributable to meteorological events such as showers the night before that thoroughly washed the forest canopy and subsequent clear skies in the morning, which enhanced convection. The cleaning effect of rainfall and the rapid change in convection in the early morning should be monitored to evaluate and generalize the gas and particle exchange in a forest.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.148-155
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• 2002

A study on the installation angle of solar panels is conducted as a conceptual study on solar-RFC(regenerative fuel cell) system for stratospheric airships. The airship heads for the west in winter days and the east in summer days according to wind directions. Considering this, it is found that when the solar panel is installed with the center angle of 30 degree the energy output of solar panels is maximized on winter solstice and satisfies the required energy of summer days as well. Although with the optimized solar panel installation angle, efficiency of the regenerative power system needs be improved to 47% to provide required energy of a 170m-long airship. And the required amount of efficiency improvement decreases as the airship size increases.