• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1125-1129
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• 2015

Increasing peak load is one of the major concerns about operation of urban railroad systems. Since ESSs (Energy Storage Systems) have a great potential for shaving the peak load, there has been a growing interest in the use of ESS for peak load reduction. Also, ESS can be optimally scheduled to minimize the electricity purchasing cost under a given ToU (Time-of-Use) tariff by taking advantage of electricity price difference between peak and off-peak time. This paper presents a Mixed Integer Programming (MIP)-based ESS scheduling method to minimize the electricity purchasing cost under a ToU tariff for an urban railroad system.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.1
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• pp.38-48
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• 2007

this paper analyses how much acceleration and deceleration of urban rail vehicle should be applied and how to choose an operation mode to minimize energy consumption when train runs between stations within the fixed operation time. The decided operation pattern satisfying the minimum energy consumption becomes a target trajectory and a basis for the controller design criteria. To make this goal it grasps the characteristics of urban rail vehicle, realize operation energy model of urban rail vehicle and verity the accuracy of embodied model the Matlab simulation with the same operation result of real route. It searches for operation pattern to minimize operation energy by changing the acceleration and deceleration on the imaginative route and proposes operation pattern minimizing energy consumption by applying real operation data between stations of Seoul Metropolitan Subway Line 6.

• Korean Journal of Human Ecology
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• v.21 no.3
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• pp.611-628
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• 2012

The purpose of this study was to examine influence of home energy cost on housing cost burden of Korean and U.S. monthly renter households in urban areas and to explore influences of household and housing characteristics on their home energy cost burden. Microdata for this research was extracted from the 2011 Korean Household Budget Survey and 2009 American Housing Survey. Monthly renter households in urban areas were initially grouped based on household income, followed by a detailed analysis of housing and home energy cost. Findings are as follows: (1) The maximum ratio of home energy cost to household house hold income in Korea was 49% compared to 83% in the US; (2) Energy cost to income ratio were found to have significant influences on housing cost burden and lower income households' housing cost burden was found more vulnerable to their energy cost; (3) In general, the energy cost burden of low-income renter households in Korea tended to be influenced by household size, the number of household members staying at home during daytime hours and housing unit size. The energy cost burden of low-income renter households in the U.S. tended to be influenced by home structure type, size and age, the householder's age, race, educational attainment, the household size, number of wage earners per household, income, and the number of household members between 7 and 17 years of age.

• Wind and Structures
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• v.7 no.3
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• pp.159-172
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• 2004

The study of how buildings affect wind flow is an important part of the research being conducted on urban climate and urban air quality. NJU-UCFM, a standard $k-{\varepsilon}$ turbulence closure model, is presented and is used to simulate how the following affect wind flow characteristics: (1) an isolated building, (2) urban canyons, (3) an irregular shaped building cluster, and (4) a real urban neighborhood. The numerical results are compared with previous researchers' results and with wind tunnel experiment results. It is demonstrated that the geometries and the distribution of urban buildings affect airflow greatly, and some examples of this include a changing of the vortices behind buildings and a "channeling effect". Although the mean air flows are well simulated by the standard $k-{\varepsilon}$ models, it is important to pay attention to certain discrepancies when results from the standard $k-{\varepsilon}$ models are used in design or policy decisions: The standard $k-{\varepsilon}$ model may overestimate the turbulence energy near the frontal side of buildings, may underestimate the range of high turbulence energy in urban areas, and may omit some important information (such as the reverse air flows above the building roofs). In ideal inflow conditions, the effects of the heights of buildings may be underestimated, when compared with field observations.

• Journal of the Korean Dietetic Association
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• v.10 no.4
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• pp.417-427
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• 2004

The purpose of this study was to investigate children's nutrient intakes by school lunch. Evaluation of nutrient intakes by school lunch for three days was conducted with 86 children in urban and 64 children in rural of Jeonbuk area. The results of this study were as follows. 1) With respect to amounts of provided nutrients in school lunch, CPF (carbohydrate : protein : fat) energy ratio was 48.6 : 19.7 : 31.6 in urban and was 46.7 : 20.5 : 32.7 in rural. Compared to 1/3 RDA (RDA) of children for 10-12 years, folic acid and zinc were provided below 50 % of RDA. Protein, fat, phosphorus, vitamin $B_1$, vitamin $B_2$, niacin, vitamin C and vitamin E were provided above 125 % of RDA. There were no differences in amounts of provided nutrients-except calcium, vitamin A, vitamin $B_6$, folic acid and zinc-between urban and rural. 2) With respect to amounts of nutrient intakes, CPF energy ratio was 51.1 : 17.4 : 31.5 in urban and 47.5 : 19.7 : 32.7 in rural. Compared to RDA, folic and zinc were below 50 % of RDA. Iron and vitamin $B_6$ were below 75 % of RDA. Protein, fat, phosphorus and vitamin E were above 125 % of RDA. There were significant differences in nutrient intakes between urban and rural. The children in rural showed higher levels of nutrient intakes-energy, carbohydrate, protein, fat, calcium, phosphorus, iron, zinc, vitamins and folic acid-compared to those of children in urban. These results suggest that programs are needed for providing adequate nutrient intakes for children in school lunch and for improving nutrient intakes of children in urban.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.107-112
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• 2005

When it comes to automatic operation control of urban rail vehicle, a PID control makes it run between stations within the fixed time and stop exactly at the stop sign on the platform, satisfying jerk limit. An optimal control is applied to automatic operation performance control to minimize energy consumption while the urban rail vehicle satisfies automatic operation condition on this paper. The control performance in terms of energy minimization along with the constraint on precision stops is compared between the optimal control and PID control.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.4
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• pp.267-283
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• 2022

In these day, the environmental issues of climate change have been continuously highlighted and there is an active discussion on the transition from fossil fuel-based energy to eco-friendly energy use. This study considered psychological attitudes as a major influencing factors for successful implementation of a hydrogen society totally based on the use of hydrogen energy, which is regarded as an alternative energy for future. Accordingly, familiarity, risk perception, and acceptability of psychological factors were investigated. In addition, this study identified whether there are differences in psychological factors according to the general characteristics of gender, age, occupation, and housing type. The results showed that awareness of hydrogen cars and fuels is below the average level, and we also have obtained the implication that social knowledge sharing should precede the implementation of hydrogen policy. Although we found that the degree of urban acceptance of hydrogen energy was high, it was also confirmed that the charging infrastructure was generally perceived as having a high risk. Our findings implicate that it is necessary to figure out policy strategies for suitable locating charging infrastructure in order to promote the use of hydrogen energy more.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.697-700
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• 2007

Six thousands of vehicles are operated on Korean urban transit system. 95% of them have regeneration system. Especially, the VVVF-Inverter vehicle has a merit of the highest regeneration rate. Therefore, the energy storage system is needed to be developed to use regeneration energy when the vehicle is braking. Therefore, Measuring regeneration energy in the substation need to know how much regeneration energy occurs, how much capacity of energy storage system is needed. After measuring regeneration energy, we design the capacity of energy storage system.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.177-182
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• 2009

The purpose of this study is to investigate planning of urban energy supply systems configuration and operating conditions for the district heating and cooling system using combined heat and power system. Generally the district heating and cooling system has been known to one of the effective way for energy saving, cost reduction and demand side management of energy. Economical analyses were carried out and operating characteristics for some systems were examined in terms of GER factor which represents to the ratio of gas and electricity costs. Rates of the energy consumption and the $CO_2$ emission were compared from the system configuration of the energy supply system with new district cooling system with the conventional one.

• Journal of Environmental Science International
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• v.20 no.7
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• pp.839-843
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• 2011

We have established a wind map of Singapore, a city-state characterized its land cover by urban buildings to confirm a possibility of wind farm development. As a simple but useful approximation of urban canopy, a zero-plane displacement concept was employed. The territory is divided into 15 sectors having similar urban building layouts, and zero-plane displacement, equivalent roughness height at each sector was calculated to setup a terrain boundary condition. Annual mean wind speed and mean wind power density map were drawn by a CFD micrositing model, WindSim where Changi International Airport wind data was used as an in-situ measurement. Unfortunately, predicted wind power density does not exceed 80 $W/m^2$ at 50 m above ground level which would not sufficient for wind power generation. However, the established Singapore wind map is expected to be applied for wind environment assessment and urban planning purpose.