• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.253-255
• /
• 2002

The necessity of compact high temperature super conducting cables is more keenly felt in densely populated metropolitan areas. As the compact high temperature superconducting cables that can be installed in ducts and tunnels can reduce construction cost and make the use of underground space more effective, the effect of introducing it to power system will be huge. For this study, Seoul, Korea is selected as a review model, the loads are estimated by scenario based on a survey and analysis of 345kV and 154kV power supply networks in this area. Based on this, the following items on urban transmission system are examined. (1) A method of constructing a model system to introduce high temperature superconducting cables to metropolitan areas is presented. (2) A case study through the analysis of power demand is conducted, and the amount of high temperature superconducting cable to be introduced by scenario is examined. (3) The economy involved in expanding existing cables and introducing high temperature superconducting cables(ducts or tunnels) following load increase in urban areas is examined and compared. (4) The maximum external diameter of HTS cable to accommodate exiting ducts based on the design standards for current cable ducts is calculated. (5) The voltage level that can be accommodated by existing ducts is examined.

• Journal of Korea Water Resources Association
• /
• v.42 no.5
• /
• pp.425-432
• /
• 2009

Gongneung Weir 2 was built in 1970s to supply water for irrigation. For a long time, the weir was left uncared because of the land use change of the nearby area. The weir is 1.5 m high, and the stream in which the weir was installed has bed materials of fine sands to fine gravels. In 2006, the local government and residents agreed on uninstalling the weir, and the weir was removed completely on April 14. This paper reports the results of three field investigations for the study of the stream morphology change after the weir removal. Changes in grain size distribution, bed elevation, and cross section before and after the weir removal are provided and discussed. Net amount of sediment deposits within 1 km reach of the stream is estimated, and the results illustrates that the sediment process, leading to an equilibrium of the bed, progressed very swiftly, namely within 45 days.

• KIEAE Journal
• /
• v.16 no.5
• /
• pp.103-109
• /
• 2016

Purpose: In Korea, to reduce greenhouse gas emissions, energy performance standard of buildings is being reinforced with goals of Passive House until 2017 and Zero Energy House until 2025 in order to reduce emissions from buildings which constitute a quarter of greenhouse gas emissions. In order to achieve the target of Zero Energy House, it is certainly necessary to develop renewable energy that can replace cooling and heating energy occupying a significant amount of building energy consumption after increasing the energy performance firstly. Method: In this study, effects of heat in greenhouse heated by solar heating on indoor heating were analyzed by constructing a greenhouse in front of the Low Energy Building. Result: As a result, indoor temperature was increased by peak average $27.8^{\circ}C$, peak average $6.8^{\circ}C$ was increased from when heat in greenhouse has not been used for heating and indoor surface temperature was increased by average $5.1^{\circ}C$. It shows it can be possible to use heat in greenhouse for heating, if the heating effects can be same as this experimental result because Energy Saving-Type buildings such as Low Energy House or Passive House keep from 18 to $20^{\circ}C$ in winter. Therefore, even if energy supply is cut off by disasters and other reasons, cooling and heating can be possible for some time.

• Journal of Biosystems Engineering
• /
• v.25 no.6
• /
• pp.481-488
• /
• 2000

This study was initiated in order to find alternative fuel substituting for light oil the most common fuel for heating greenhouse. The tire oil used in this research was produced by pyrolysis process, one of the final products besides steel string and carbon black in which waste tires as a form of chopped pieces broken by shredding machine are heated up to 200~30$0^{\circ}C$ with maximum restraining of oxygen supply. In order to justify light oil equivalent qualities in tire oil combustion characteristics were defined in the way of comparing kinetic viscosities in the wide range of temperature flame sizes and exhaust gas components in the various combustion conditions. We found that kinetic viscosity of tire oil was lower than light oil by 1 to 2 cSt in the temperature range showing better flowing mobility in the fuel line of the burner and no significant difference in flame size between the two oils in the all combustion treatments. However much more NO and SO$_2$ were detected from the exhaust gases of tire oil than light oil combustions. In fact tire oil contains more nitrogen and total sulfur, by 25 times and 40 times respectively than light oil according to the composition analysis. Tolerable limit for SO$_2$discharge amount defined by the national air pollution standards is under 540ppm so tire oil combustion satisfies the requirement though. It is desirable if sulfur and nitrogen filtering process shall be added in the tire oil production line. Except the exhaust gas components all greenhouse heating qualities of tire oil including hot air temperature are very identical to those of light oil.

• Environmental and Resource Economics Review
• /
• v.26 no.3
• /
• pp.451-472
• /
• 2017

An OPEC production announcement is a major source of supply disruption that has a significant impact on the international crude oil market. In this study, the effects of OPEC's announcements are analyzed using event study methodology. Considering the oil price volatility and structural changes in the oil price, we divide the entire period into three periods and analyze the impact of OPEC's production quota announcements, including 'cut', 'hike', and 'maintain'. As a result of the analysis, we observe that the degree and direction of abnormal returns differ according to the announcements in each period. In addition, by subdividing oil price surge and plunge period into two sections, we analyze the effect of OPEC's 'maintain' announcements. During the oil price plunge period, the amount of abnormal returns was significant. This study provides policy implications for oil trading strategies and for the impact of OPEC announcements during periods of oil price fluctuation.

• Journal of Environmental Science International
• /
• v.19 no.7
• /
• pp.917-929
• /
• 2010

This paper aims to find out the statistical characteristics of the weather related railroad accidents and incidents. Data from Korea Railroad Operation Information System(KROIS) and Korea Railroad Accidents reports during 1996-2008 were used to investigate the occurrence frequency of railroad accidents and operation obstacles and their association with weather phenomena. The results are as follows; The occurrence frequency of railroad accidents and operation obstacles decrease gradually, and most of railroad accidents is a railroad traffic accidents. The amount of damages by a railroad weather-related accidents is higher than those of the railroad accidents and operation obstacles. It was also found that weather events influencing the railroad weather-related accidents and incidents are rainfall, snowfall, lightning, winds. And they caused a railroad weather-related accidents and incidents, such as railway obstruction, signal failure, and power supply failure. Therefore we need research about threshold review and a quantitative and qualitative analysis of a railroad weather-related accidents and incidents according to climate change.

• Journal of Digital Convergence
• /
• v.12 no.4
• /
• pp.145-155
• /
• 2014

POSCO has been chosen as the most competitive steelmaker in the world, for the 4th year in a row. It's potentials and key success points lay at technology innovation as well as effective partnerships with suppliers and customers. Partnership with suppliers is based upon the effective supply chain management. While ERP system supports the standard business work flows, the biggest impact on business performance is created by exceptions and variability. A SCM Advanced Planning System reduces the amount of exceptional situations, helping to keep business in a standard mode of operation. A case summary on SCM Advanced Planning System of POSCO as well as its impact on firm performances is presented. As a supplement to this case study, we also investigate the employees' perceived level of SCM-related factors, including information sharing, collaboration, incentive system for suppliers and their impacts on SCM performances. As a conclusion, the practical implications of these findings are discussed.

• Journal of Korea Water Resources Association
• /
• v.39 no.7 s.168
• /
• pp.563-574
• /
• 2006

Economic theory tell us, consumers always make a choice to maximize their utility. In the market system, consumers' choices are revealed and policy maker taking into account the aggregated consumers choice such as price, supply and demand. However, water resources as a public goods, therefore typically there is no market and does no aggregated information for residential water use. This study explore the consumers' willingness to pay for higher quality for residential water. Over 1,000 households responded for this survey and willingness to pay has been estimated. Furthermore, consumers' behaviors of residential water are examined. Consumers are willing to reduce the amount of water use with more than 50% of increasing water price, but stay almost constant with less than 25% of increasing which mean that current price level is not high enough to derive water saving. If consumers can have better quality of water, they willing to pay additional 16%, $153\;won/m^3/month$, more than their current price. Based on the derived information, we suggested policy direction for residential water policy.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.18 no.2
• /
• pp.197-207
• /
• 2018

SMEs manufacturing Factory, which are small-scale production systems of various types, mass-produce and sell products in order to meet customer needs. This means that the company has an excessive amount of material supply to reduce the loss due to lack of inventory and high inventory maintenance cost. And the products that fail to respond to the demand are piled up in the management warehouse, which is the reality that the storage cost is incurred. To overcome this problem, this paper uses ARIMA model, a time series analysis technique, to predict demand in terms of seasonal factors. In this way, demand forecasting model based on economic order quantity model was developed to prevent stock shortage risk. Simulation is carried out to evaluate the effectiveness of the development model and to demonstrate the effectiveness of the development model as applied to SMEs in the future.

• Journal of the Korea Society of Computer and Information
• /
• v.16 no.2
• /
• pp.201-206
• /
• 2011

With the development and supply of digital displayers, there has been a heightened interest of late in digital photo frames, eclipsing the existing print frames. This digital photo frame was developed into a new LCD digital photo frame that can be used not only for data display but also as a surveillance monitoring equipment when combined with a CCD camera. The developed photo frame uses a one-way communication encryption method that replaces the existing two-way communication encryption method to ensure the security of the surveillance image data. This method uses the chaotic signal's one-way synchronization phenomenon, where synchronization is made for a certain amount of time, after which the synchronized data can be encrypted and decoded at any point. It can yield the same results as the two-way communication encryption method. Moreover, if the proposed method is applied to the close-range communication methods of ubiquitous devices, it will be able to obtain more efficient results.