• Architectural research
• /
• v.18 no.2
• /
• pp.59-64
• /
• 2016

Since the massive power outages that hit across the nation in September 2011, a growing imbalance between energy supply and demand has led to a severe backup power shortage. To overcome the energy crisis which is annually repeated, a policy change for deriving energy supply from renewable energy sources and a demand reduction strategy has become essential. Buildings account for 18% of total energy consumption and have great potential for energy efficiency improvements; it is an area considered to be a highly effective target for reducing energy demand by improving buildings' energy efficiency. In this regard, retrofitting buildings to promoting environmental conservation and energy reduction through the reuse of existing buildings can be very effective and essential for reducing maintenance costs and increasing economic output through energy savings. In this study, we compared the energy reduction efficiency of national power energy consumption by unit production volume based on thermal power generation, renewable energy power generation, and initial and operating costs for a building retrofit. The unit production was found to be 13,181GWh/trillion won for bituminous coal-fired power generation, and 5,395GWh/trillion won for LNG power generation, implying that LNG power generation seemed to be disadvantageous in terms of unit production compared to bituminous coal-fired power generation, which was attributable to a difference in unit production price. The unit production from green retrofitting increased to 38,121GWh/trillion won due to the reduced energy consumption and benefits of greenhouse gas reduction costs. Renewable energy producing no greenhouse gas emissions during power generation and showed the highest unit production of 75,638GWh/trillion won, about 5.74 times more effective than bituminous coal-fired power generation.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.60 no.4
• /
• pp.123-132
• /
• 2018

The purpose of this study was to evaluate the reduction effect of non point source (NPS) pollution in Haean highland agricultural catchment ($62.8km^2$) for 13 BMP scenarios under RCP (Representative Concentration Pathway) 4.5 and 8.5 scenarios. Under the present climate condition, the BMP (best management practices) reduction efficiency of SS (suspended solid), T-N (total nitrogen), and T-P (total phosphorus) showed +25.7%, +4.2%, and +16.1% for VFS (vegetative filter strip), +0.1%, +15.6%, and +5.7% for FC (fertilizer control), and +6.3%, -2.9%, and +3.9% for RSM (rice straw mulching) respectively. In general, effective was the best for SS and T-P reductions, and the FC was the best for T-N reduction. The negative effect of T-N on RSM was induced by increase in infiltration and solute transport to baseflow. Under the future climate change scenarios, the SS, T-N, and T-P reduction efficiency showed the range of +1.9~+11.6%, -1.9~+0.2%, and +5.3~+11.9% respectively. The 3 BMPs (VFS, FC, and RSM) application in the future showed negative and little differences (-0.5~+1.6%) for SS and T-N reduction efficiencies while T-P reduction efficiency showed +0.3~+7.6% comparing with the baseline period. To achieve an increase in the reduction efficiency of future SS and T-N by +2~+10%, the combined application of more than two BMPs is necessary.

• Proceedings of the KSR Conference
• /
• 1999.11a
• /
• pp.463-470
• /
• 1999

In this paper, a numerical method for evaluating the efficiency of vibration reduction of substructure under slab track is developed for optimal design of floating slab track. The equation of motion for train and track interaction system is derived by applying compatibility condition at the contact points between wheels and rails. The train is modelled by 3-masses system and the track by continuous support beam system. Numerical analyses are carried out to investigate the effect of train speed, stiffness and damping of slab-pad, and track irregularity upon vibration reduction in substructure under the track.

• Journal of Korean Society of Water and Wastewater
• /
• v.24 no.4
• /
• pp.395-406
• /
• 2010

In this study, anaerobic digestion, electro-oxidation and electro-fenton oxidation processes were investigated to reduce oily refinery sludge. Anaerobic digestion process was not suitable for oily activated sludge reduction because of characteristics itself and, as experimental results revealed, reduction efficiency was low for electro-oxidation process. However, 40% total suspended solid reduction of oily activated sludge was obtained by electro-fenton oxidation process, operating at pH=1, 0.5 A and $Fe^{2+}$:$H_2O_2$ ratio = 1:30. In addition, higher reduction efficiency was obtained as reaction time was increased (30, 60, 90, 120 min) despite of low $H_2O_2$ concentration. From the results, it has been investigated that electro-fenton oxidation is efficient process for oily activated sludge reduction.

• Journal of Climate Change Research
• /
• v.7 no.1
• /
• pp.85-93
• /
• 2016

This study the efficiency of greenhouse gas reduction of 'low carbon car collaboration fund' and its alternative 'control of average fuel efficiency and greenhouse gas', and 'improving driving behavior' were analyzed by using LEAP, long term energy analysis model. Total 4 scenarios were set, baseline scenario, without energy-saving activity, 'low carbon car collaboration fund' scenario, 'fuel efficiency improving scenario', and 'improving driving behavior' scenario. The contents of analysis were forecast of energy demand by scenario and application as well as reduction of greenhouse gas emission volume, and the period taken for analysis was every 1 year during 2015~2030. Baseline scenario, greenhouse gas emission volume in 2015 would be 7,935,697 M/T and 13,081,986 M/T in 2030, increased 64.8%. The analysis result was average annual increase rate of 3.4%. The expected average annual increase rate of other scenarios was, 'low carbon car collaboration fund' scenario 1.7%, 'fuel efficiency improving' scenario 3.0%. and 'improving driving behavior' scenario 3.4%. and these were each 1.7%, 0.3%. 0.3% reduce from baseline scenario. The largest reduction was 'low carbon car collaboration fund' scenario, and there after were 'fuel efficiency improving scenario', and 'improving driving behavior' scenario.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.9 no.4
• /
• pp.216-224
• /
• 2009

The endless scaling down of the semiconductor process made the impact of the power network noise on the performance of the state-of-the-art chip a serious design problem. This paper compares the performances of two popular circuit reduction approaches used to improve the efficiency of power network noise analysis: moment matching-based model order reduction (MOR) and node elimination-based MOR. As the benchmarks, we chose PRIMA and R2Power as the matching-based MOR and the node elimination-based MOR. Experimental results indicate that the accuracy, efficiency, and memory requirement of both methods very strongly depend on the structure of the given circuit, i.e., numbers of the nodes and sources, and the number of moments to preserve for PRIMA. PRIMA has higher accuracy in general, while the error of R2Power is also in the acceptable range. On the other hand, PRIMA has the higher efficiency than R2Power, only when the numbers of nodes and sources are small enough. Otherwise, R2Power clearly outperforms PRIMA in efficiency. In the memory requirement, the memory size of PRIMA increases very quickly as the numbers of nodes, sources, and preserved moments increase.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.16 no.3
• /
• pp.113-118
• /
• 2017

In this paper, a study on the performance evaluation of a cycloid reducer for remote weapons systems is presented. Reduction gears applied to remote weapons vehicles need to be compact and capable of large torque transmissions as well as require structural optimization, high load capacity, and high precision position control. To meet these requirements, a cycloid reducer with low backlash, high precision, high overload capability, high rigidity, and high efficiency is required. Thus, a cycloid reducer with a reduction ratio of 127:1, backlash of 1 arcmin (1/60 deg) or less, and reduction gear efficiency of 70% or more, which are the design requirements for a remote weapons system, was designed utilizing a design and analysis program (HEXAGON) for gear engineering. To confirm the performance of the cycloid reducer, the hardness of the main components of the manufactured cycloid reducer, reduction ratio, and efficiency were measured.

• Journal of Korean Society on Water Environment
• /
• v.36 no.5
• /
• pp.405-422
• /
• 2020

Land use change by urbanization has significantly affected the hydrological process including the runoff characteristics. Due to this situation, it has been becoming more complicated to manage non-point source pollutions caused by rainfall. In order to effectively control non-point sources, it is necessary to identify the reduction efficiency of the various management method based on land use characteristics. Thus, the purpose of this study is to analyze the reduction efficiency of non-point source pollution management practices targeting three different watersheds with the different land use characteristics using the Soil and Water Assessment Tool (SWAT). To do this, the vulnerable subwatersheds to non-point source pollution occurrence within each watershed were selected based on the streamflow and water quality simulation results. Then, considering the land use, low impact development (LID) or best management practices (BMPs) were applied to the selected subwatersheds and the efficiency of each management was analyzed. As a result of analysis of the non-point source pollution reduction efficiency, when LID was applied to urban areas, the average reduction efficiencies of SS, NO₃-N, and TP were 5.92%, 4.62%, and 10.35%, respectively. When BMPs were applied to rural areas, the average reduction efficiencies of SS, TN and TP were 35.45%, 4.37%, and 10.16%, respectively. The results of this study can be used as a reference for determining appropriate management methods for non-point source pollution in urban, rural, and complex watersheds.

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.2874-2879
• /
• 2008

The Selective catalytic reduction(SCR) system is a highly-effective device of $NO_x$ reduction for diesel engines. Generally, the ammonia($NH_3$) generated from a liquid urea-water solution is used for the reductant. The ideal ratio of $NH_3$ molecules to $NO_x$ molecules is 1:1 based on $NH_3$ consumption and having $NH_3$ available for reaction of all of the exhaust $NO_x$. However, under the too low and too high temperature condition, the $NO_x$ reduction efficiency becomes lower, due to temperature window. And space velocity also affects to $NO_x$ conversion efficiency. This paper reviews a laboratory study to evaluate the effects of $NO_x$ and $NH_3$ concentrations, gas temperature and space velocity on the $NO_x$ conversion efficiency of the SCR system. The maximum conversion efficiency of $NO_x$ was indicated when the $NH_3$ to $NO_x$ ratio was 1.2 and the space velocity was $60,000\;h^{-1}$. The results of this paper contribute to improve overall $NO_x$ reduction efficiency and $NH_3$ slip.

• Journal of Wetlands Research
• /
• v.15 no.1
• /
• pp.79-90
• /
• 2013

Stormwater wetland targeted to treat the rainfall runoff from cow feeding-lot basin has been monitored from May 2010 to November 2011. Reduction efficiency estimated based on 20 rainfall event monitoring was 88%, 54%, 70%, 31%, and 64% for TSS, BOD, $COD_{Cr}$, TN, and TP, respectively. Theoretically, as rainfall depth increases, hydraulic exchange ratio has to be increased. When the exchange ratio approaches to 1 (usually design goal), TSS reduction efficiency was estimated about 55%. Uncertainty in reduction efficiency of the stormwater wetland is normally very high due to the continuous rainfall activity, its magnitude and intensity, antecedent dry days, and other natural variables which can not be controlled by experiment conductors. In this study, predominant affecting variables was found to be hydraulics caused by consecutive rainfall events having different intensity and algal growth during dry days.