• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.292-298
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• 2022

Femtocell networks can be a potential method for increasing the capacity of LTE networks, especially in indoor areas. However, unplanned deployment of femtocells results in co-tier interference and cross-tier interference problems. The interference reduces the advantages of implementing femtocell networks to a certain extent. The notion of Fractional Frequency Reuse (FFR) is proposed in order to reduce the impact of interference on the system's performance. In this paper, a dynamic approach for efficiently partitioning the spectrum is suggested. The goal is to enhance the capacity of femtocells, which will improve the performance of the system. The suggested strategy allocates less resources to the macrocell portion of the network, which has a greater number of femtocells deployed to maximize the utilization of available resources for femtocell users. The spectrum division would be dynamic. The proposed strategy is evaluated through a simulation using MATLAB tool. In conclusion, the results showed that the proposed scheme has the potential to boost the system's capacity.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.762-767
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• 2016

High thermal efficiency and the ability to use various types of fuel are a few of the many advantages of diesel engines. However, a major disadvantage is that their exhaust emissions are more harmful to humans and the environment than that of conventional engine. Consequently, the provisions of the international emissions standards for diesel engine equipped passenger cars, commercial vehicles, and ships have become more stringent. These standards include the EU Euro 6, the IMO MEPC Tier 3, and the US EPA Tier 4. Ryu et al. published a study that applied fuel additives to two-stroke diesel engines. In this study, a four-stroke diesel engine using diesel oil for a generator is utilized as the test subject, and an experiment is performed to verify whether fuel additive can be used to improve performance and exhaust emissions. In addition, this experimental study presents research results for the application of fuel additives in both two-stroke and four-stroke diesel engines. The experimental results were compared and analyzed by placing an oil-soluble calcium-based organometallic compound in diesel oil. The results confirmed that the addition of fuel additive improved the performance (fuel consumption rate, exhaust gas temperature) and exhaust emissions (NOx, CO) of the diesel engine.

• Journal of Bio-Environment Control
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• v.28 no.1
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• pp.28-37
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• 2019

We designed a system that can automatically collect, convey, and control cool air of $15^{\circ}C-20^{\circ}C$ containing carbon dioxide from a mushroom cultivation house to a strawberry plastic house. We recorded the temperature at various positions from July to August 2017. The average temperature of the green house during day and at night was maintained at $33^{\circ}C$ and $26^{\circ}C$, respectively. In the moveable three-tier cylindrical bed, the average temperature around root was maintained at $26^{\circ}C$ and $21^{\circ}C$ during day and at night, respectively. On the high-bench in the green house, the temperature was maintained at $32^{\circ}C$ and $30^{\circ}C$ during day and at night, respectively. The carbon dioxide concentration was maintained around 800-1,600 ppm in the mushroom cultivation system and 400-800 ppm in the strawberry plastic house. The growth characteristics of the strawberry treated with moveable three-tier cylindrical bed were significantly different from those of the untreated high-bench bed. In addition, during the summer season, moveable three-tier cylindrical bed showed more tendency to increase in normal fruit number (NFN) and to decrease in defective fruit number (DFN) compare to the high-bench bed. Therefore, the moveable three-tier cylindrical bed showed a tendency to be more than 2 times higher yields than that of the high-bench bed. It was confirmed that ever-bearing strawberry cultivars could be cultivated in green house due to the cool air supply from the mushroom cultivation system in the summer season.

• Korean Journal of Agricultural Science
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• v.50 no.3
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• pp.383-394
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• 2023

In Korea, the U.S. Tier-4 Final emission standards have been applied to agricultural machinery since 2015. This study was conducted to analyze the emission characteristics of agricultural tractors during plow tillage operations using PEMS (portable emissions measurement systems). The tractor working speed was set as M2 (5.95 km/h) and M3 (7.60 km/h), which was the most used gear stage during plow tillage operation. An engine idling test was conducted before the plow tillage operation was conducted because the level of emissions differed depending on the temperature of the engine (cold and hot states). The estimated level of emissions for the regular area (660 m²), which was the typical area of cultivation, was based on an implement width of 2.15 m and distance from the work area of 2.2 m. As a result, average emission of CO (carbon monoxide), THC (total hydrocarbons), NOx (nitric oxides), and PM (particulate matter) were approximately 6.17×10-2, 3.36×10^-4, 2.01×10^-4, and 6.85×10^-6 g/s, respectively. Based on the regular area, the total emission of CO, THC, NOx, and PM was 2.62, 3.76×10^-2, 1.63, and 2.59×10^-4 g, respectively. The results of total emission during plow tillage were compared to Tier 4 emission regulation limits. Tier 4 emission regulation limits means maximum value of the emission per consumption power (g/kWh), calculated as ratio of the emission and consumption power. Therefore, the total emission was converted to the emission per power using the rated power of the tractor. The emission per power was found to be satisfied below Tier 4 emission regulation limits for each emission gas. It is necessary to measure data by applying various test modes in the future and utilize them to calculate emission because the emission depends on various variables such as measurement environment and test mode.

• Journal of Korean Society of Transportation
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• v.28 no.6
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• pp.33-42
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• 2010

Recently, the reduction of greenhouse gases(GHG) for climate change is the most important international issue. In order to control efficiency GHG emission rate reduction, it is essential to establish GHG emission inventory preferentially. The emission of ships that are emitting its $CO_2$ in international waters is becoming chief among the issues which country is put under an obligation. In the IMO reports, shipping is estimate to emit 1,046million tonnes of $CO_2$, which corresponds to 3.3% of global emission during 2007. International shipping is estimated to have emitted 870 million tonnes, about 2.7% of global emission of $CO_2$ in 2007. In this study, the general information of GHG emission, based on fuel consumption statistic, Tier 1, and the emission inventory is calculated to break down in to domestic and international emission. The GHG emission from ships in Korea was total 31,646 Gg $CO_2$-eq in 2009, which is included fishing, Korea flag coastal ship, Korea flag ocean going ship and foreign flag ships. And domestic emission and international emission was 5,398Gg $CO_2$-eq, 7,630Gg $CO_2$-eq and foreign flag ship was 18,618Gg $CO_2$-eq respectively.

• Journal of the Korean Association of Geographic Information Studies
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• v.14 no.2
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• pp.40-52
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• 2011

In this study, $CO_2$ emission quantities by spatial characteristics using GIS were investigated for building a $CO_2$ emission inventory. Eventually, this study provides the guidelines to build the urban spatial structure for reducing greenhouse gas and contributes to the transition to environmental friendly green city. The attribute data for GIS were energy (electricity and gas) usage in the city of Daegu for 2009 and used for Tier 1 as suggested by the IPCC guideline to estimate amount of $CO_2$ emission. The spatial data were built based on land use types categorized by building purposes with connecting building registers to cadastral maps for Daegu city. Spatial $CO_2$ emission quantities could be calculated by combining $CO_2$ emission inventory for energy and GIS. Also, $CO_2$ emission characteristics were different by land use types.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2B
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• pp.170-177
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• 2009

In this paper, we propose the structures of the NBTC (Narrow-Beam Trisector Cell) and the WBTC(Wide-Beam Trisector Cell) in which directional antennas both at the base station and at the relay station are used. We analyze and compare total capacity of the both systems taking the co-channel interference into consideration for two channel models. Through analysis, we find the effect of LOS (Lind of Sight) path to the total capacity of NBTC structure and that of WBTC structure. Our work may be useful as a guideline to control the interference for the next generation mobile communication and WiBro systems using multi-hop relays.

• Journal of Climate Change Research
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• v.1 no.3
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• pp.211-217
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• 2010

Off-road transportation sector including construction equipment, ground support equipment in airport, cargo handling equipment and agroforestry machinery have not calculated as emission source classification in 1A3e2. In this study, the statistics of oil consumption for construction, aviation, shipping and agroforestry are separated for this sector by oil type. And the greenhouse gas emission by off-road transportation emission factor in 1996 & 2006 IPCC Guidelines are calculated and compared with each other. As a result, the nationwide $CO_2$ equivalent emission from off-road transportations by the emission factor of 1996 & 2006 IPCC Guidelines are calculated as 4,919 kton/yr and 5,530 kton/yr in 2007. The contribution ratio of off-road transportation emission by this study is estimated as 5.5% to the subtotal emission from on-road transport sector.

• Journal of the Society of Disaster Information
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• v.19 no.1
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• pp.231-240
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• 2023

Purpose: The purpose of this study is to analyze air quality and carbon emissions in developing countries, particularly Myanmar, and explore the impact of transportation on CO2 emissions during peak hours relative to free-flow conditions. Method: This study conducted a traffic survey in two major cities in Myanmar to quantify carbon dioxide emissions from the transportation sector, using IPCC's tier 1 and tier 2 approaches, with statistical analysis performed using Python 3 and Microsoft Excel for comparative analysis of critical factors in CO2 emissions. Result: The result of this study is an estimate of the vehicle kilometers traveled (VKT) and fuel consumption in Yangon city for the year 2019, based on data from various sources including the Myanmar Statistical data base, YUTRA project survey, and Ministry of Electric and Energy. The study also analyzes the average travel time index (TTI) for the four roads in Yangon, which indicates the impact of congestion on vehicle travel time and CO2 emissions. Overall, the study provides important insights into the transport sector in Yangon city and can be used to inform policies aimed at reducing greenhouse gas emissions and improving traffic conditions. Conclusion: The study concludes that congestion plays a significant role in increasing fuel use and emission levels in the road transport sector in Myanmar. The analysis provides valuable insights into the impact of the sector on the environment and emphasizes the importance of addressing congestion to reduce fuel use and emissions. However, the study's scope is limited to Yangon city and Mandalay city, and some mean values may not accurately represent the entire country and other developing countries.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.1
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• pp.47-58
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• 2018

The heterogeneous cellular network (HCN) is most significant as a key technology for future fifth generation (5G) wireless networks. The heterogeneous network considered consists of randomly macrocell base stations (MBSs) overlaid with femtocell base stations (BSs). The stochastic geometry has been shown to be a very powerful tool to model, analyze, and design networks with random topologies such as wireless ad hoc, sensor networks, and multi- tier cellular networks. The HCNs can be energy-efficiently designed by deploying various BSs belonging to different networks, which has drawn significant attention to one of the technologies for future 5G wireless networks. In this paper, we propose switching off/on systems enabling the BSs in the cellular networks to efficiently consume the power by introducing active/sleep modes, which is able to reduce the interference and power consumption in the MBSs and FBSs on an individual basis as well as improve the energy efficiency of the cellular networks. We formulate the minimization of the power onsumption for the MBSs and FBSs as well as an optimization problem to maximize the energy efficiency subject to throughput outage constraints, which can be solved the Karush Kuhn Tucker (KKT) conditions according to the femto tier BS density. We also formulate and compare the coverage probability and the energy efficiency in HCNs scenarios with and without coordinated multi-point (CoMP) to avoid coverage holes.