• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.26 no.10
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• pp.474-480
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• 2014

This study investigated the total energy consumption and the energy consumption by type of 31 apartment complexes in Daejeon. The energy is supplied to the apartments from district heating, and can be divided into hot water, electricity, and gas. Hot water is used in for space heating and for domestic hot water (DHW), and electricity is used for plugs, cooling, ventilation, and public utilities (street lights, pumps, elevators, etc.). All gas supplied from district heating is used for cooking. As a result, the consumption unit of each energy source of independent dwelling areas was calculated to be $103.7kWh/m^2{\cdot}a$ ($15,692kWh/H{\cdot}a$) for thermal energy, $48.0kWh/m^2{\cdot}a$ ($4,646kWh/H{\cdot}a$) for electricity, and $10.5kWh/m^2a$ ($1,015kWh/H{\cdot}a$) for gas, so the entire consumption was calculated to be $162.3kWh/m^2{\cdot}a$ ($15,692kWh/H{\cdot}a$).

• Plant Journal
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• v.15 no.3
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• pp.23-28
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• 2019

In this study, ammonia consumption by gas turbine output was adjusted to find out the amount of ammonia consumption that complies with the enhanced Air Quality Preservation Act and internal regulation emission standards in SCR type DeNOx System for a 580 MW Sejong Combined Cycle Power Plant. For measurements, the gas turbine output was varied to 50, 99, 149, 198 MW and ammonia consumption was adjusted with the combustion gas and ammonia supply conditions fixed at each stage. When the emission limit were change from 10 ppm to 8 ppm, ammonia consumption was increased from 78, 93, 105, 133 kg/h to 89, 113, 132, 176 kg/h. The increase rate of ammonia consumption was 14, 22, 26, 32% per output category compared to the 10 ppm emission limit, which was shown to increase as output increased.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.2
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• pp.128-135
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• 2008

EGR(exhaust gas recirculation) is considered as a most effective method to reduce the NOx emissions. But high EGR tolerance is always pursued not only for its advantages of the pumping loss reduction and fuel economy benefit in Gasoline-Hybrid engine. However, the occurrence of excessive cyclic variation with high EGR normally prevents substantial fuel economy improvements from being achieved in practice. Therefore, the optimum EGR rate should be carefully determined in order to achieve low fuel consumption and low exhaust emission. In this study, 2 liters gasoline engine with E-EGR system was used to investigate the effects of EGR on fuel efficiency, combustion stability, engine performance and exhaust emissions. With optimal EGR rates, the fuel consumption was improved by 4%. This improvement was achieved while a reduction in NOx emissions of 75% was accomplished. Increase of EGR gas temperature causes the charge air temperature to affect the knock phenomenon and moreover, the EGR valve lift changes for the same control signal.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.5
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• pp.539-549
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• 2007

To establish effective and prompt measures for energy conservation in public wastewater treatment plants in Korea, energy consumption rates in 233 utilities in 9 provinces and 7 metropolitan cities are investigated and compared to the rest of the world. Mean load factor for wastewater treatment utilities is 74.9% and those for influent pumps and aeration blowers are 56.2% and 61.0%, respectively. Mean electrical energy usages as the key performance indicators are $0.243kWh/m^3$ for overall sewage treatments and 2.07 kWh per unit kg BOD removal. Digester gas as one of major byproducts in the process amounts to $382,000m^3/day$ nationwide. While major part of the digester gas is used for sludge heating, only 7.3% of the gas is utilized for electricity generation. Both efficiencies for BOD removal and digestion gas generation are considerably lower than those in USA and EU utilities due to low concentration of organic material in influent wastewater. Such low energy regeneration, in turn, results in significantly higher energy consumption in Korean plants, compared to that in USA and EU ones.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.34-39
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• 2007

Condensing gas boiler units may make a big role for the reduction of energy consumption in heating industries. In order to decrease the energy consumption of a condensing gas boiler unit, the effective operations and controls of the system are necessary. In this study, mathematical models of a condensing gas boiler system were developed and programmed in order to predict dynamic behaviors of the system. These include dynamic models for a blower, a gas valve, a pump, a burner, a boiler heat exchanger, and a hot water heat exchanger. Control algorithms for the control of a gas valve, a blower, and a pump were also assumed. Simulation results showed good predictions of the dynamic phenomena of a boiler system. Therefore, the simulation program developed for this study may be effectively used for the development of control algorithms of the boiler system.

• Environmental and Resource Economics Review
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• v.30 no.3
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• pp.503-533
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• 2021

This paper analyzes the relationships among the energy consumption, renewable energy production, real gross regional domestic product(GRDP), and greenhouse gas(GHG) emissions. It uses the metropolitan city and province level data for Korea from 2010 to 2018, employing a panal vector autoregressive(VAR) model. We find that an increase in energy consumption has a limited impact on boosting renewable energy production or gross regional domestic product, while it leads to an increase in greenhouse gas emissions. A rise in renewable energy production can increase gross regional domestic product, but it has no meaningful effects on energy consumption and the reduction of green house gas emissions. Our finding indicates that it is crucial to expand the supply of renewable energy as well as to decrease energy consumption in order to achieve the goal of reducing greenhouse gas emissions and reaching economic growth.

• Tribology and Lubricants
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• v.22 no.3
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• pp.155-163
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• 2006

Ring, groove and cylinder bore wear may not be a problem in most current automotive engines. However, a small change in ring face, groove geometry and cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blowby and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each part's wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of rings, grooves and cylinder bore are obtained from three engines before and after engine durability test. The calculated wear data of each part are turn out to be around the band of averaged test values or a little below.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.732-733
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• 2015

Currently, since the total energy amount has been increased continuously, the effort for energy efficiency of apartment building is necessary. Although the previous studies have been focused on the issue. Almost studies are about the simulation by applying the energy analysis tools and a lack of studies have been conducted the data analysis about real city gas amount of apartment building. Therefore, the objective of this study is to analyze the city gas consumption difference according to the exclusive dwelling in apartment building. To address this issue, the descriptive, correlation, analysis of variance (ANOVA) statistics are used in this study. As a result, in the case of annual total amount, the city gas is increased as the size of the exclusive dwelling area is increased. In the future, the findings of this study can be used as a basic material to develop the prediction model of city gas in apartment building.

• Tribology and Lubricants
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• v.22 no.3
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• pp.131-136
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• 2006

Cylinder bore wear may not be a problem in most current automotive engines. However, a small change in cylinder bore diameter can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each pare0s wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of cylinder bore diameter are obtained from three engines before and after engine durability test. The calculated wear data of cylinder bore diameter are turn out to be twice of the lower bound of averaged test values at TDC and the lower bound at BDC.

• Tribology and Lubricants
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• v.22 no.4
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• pp.211-217
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• 2006

Ring and groove wear may not be a problem in most current automotive engines. However, a small change in ring face and groove geometry can significantly affect the lubrication characteristics and ring axial motion. This in turn can cause to change inter-ring pressure, blow-by and oil consumption in an engine. Therefore, by predicting the wear of piston ring face, ring groove and cylinder bore altogether, the changed ring end gap and the changed volume of gas reservoir can be calculated. Then the excessive oil consumption can be predicted. Being based on the calculation of gas flow amount by the theory of piston ring dynamics and gas flow, and the calculation of oil film thickness and friction force by the analysis of piston ring lubrication, the calculation theory of oil amount through top ring gap into combustion chamber will be set. This is estimated as engine oil consumption. Furthermore, the wear theories of ring, groove and cylinder bore are included. Then the each amount of wear is to be obtained. The changed oil consumption caused by the new end gap and the new volume of oil reservoir around second land, can be calculated at some engine running interval. Meanwhile, the wear amount and oil consumption occurred during engine durability cycle are compared with the calculated values. Next, the calculated amount of oil consumption and wear are compared with the guideline of each part's wear and oil consumption. So, the timing of part repair and engine life cycle can be predicted in advance without performing engine durability test. The wear data of rings and grooves are obtained from three engines before and after engine durability test. The calculated wear data of each part are turn out to be at the lower bound of aver-aged test values or a little below.