• Journal of Astronomy and Space Sciences
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• v.38 no.2
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• pp.145-155
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• 2021

In this work, preliminary launch opportunities from NARO Space Center to the Sun-Earth Lagrange point are analyzed. Among five different Sun-Earth Lagrange points, L1 and L2 points are selected as suitable candidates for, respectively, solar and astrophysics missions. With high fidelity dynamics models, the L1 and L2 point targeting problem is formulated regarding the location of NARO Space Center and relevant Target Interface Point (TIP) for each different launch date is derived including launch injection energy per unit mass (C3), Right ascension of the injection orbit Apoapsis Vector (RAV) and Declination of the injection orbit Apoapsis Vector (DAV). Potential launch periods to achieve L1 and L2 transfer trajectory are also investigated regarding coasting characteristics from NARO Space Center. The magnitude of the Lagrange Orbit Insertion (LOI) burn, as well as the Orbit Maintenance (OM) maneuver to maintain more than one year of mission orbit around the Lagrange points, is also derived as an example. Even the current work has been made under many assumptions as there are no specific mission goals currently defined yet, so results from the current work could be a good starting point to extend diversities of future Korean deep-space missions.

• Journal of the Korean Solar Energy Society
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• v.32 no.3
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• pp.153-161
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• 2012

This study conducted a survey and field investigation on the application of the Public Obligation System for new & renewable energy in public buildings, as well as energy consumption of each building according to their uses. The findings are as follows: (1) Since the introduction of the Public Obligation System (until June 30, 2011), there was average 1.4 new & renewable energy facilities established at 1,433 places. Preference for solar energy facilities was the highest at 57.8%. (2) The revised act sets the obligatory supply percentage of new & renewable energy for each public building: it is 9.0% for a tax office, 4.2% for a dong office, 8.2% for a public health center, and 12.6% for a fire station. All the public buildings except for fire stations failed to meet 10% expected energy consumption, a revised standard. (3) Energy consumption of each public building was 120.6TOE for a tax office, 124.3TOE for a dong office, 166.4TOE for a public health center, and 174.6TOE for a fire station. The energy consumption was comprised of 80% electric power, 18% urban gas, and 1% oil. (4) Electric power consumption per person in the room was high at a dong office, and fuel consumption per person in the room was high at a public health center. In addition, electric power consumption per unit space was high at a public health center, and fuel consumption per unit space was high at a fire station. (5) In all the four public buildings, power load had the highest basic unit percentage at average 55%, being followed by heating load (21.2%), cooling load (15%), and water heating load (7%). A tax office and fire station had 2% load due to cooking facilities.

• Journal of the Korean Chemical Society
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• v.26 no.4
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• pp.195-204
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• 1982

Semi-empirical MO calculations, EHT, CNDO/2, MINDO/3, and MNDO met hods, were performed on various geometries of n-butane, n-alkyl radical and tetramethylene diracal (triplet) in order to compare eigenvalue and eigenvector properties with those obtained by STO-3G method. All methods predicted the same relative order of stabilities of various geometries for n-butane; geometrical preferences were found to be dominated by one-electron factor, ${\pi}$-orbital energy changes being more impotant in the semi-empirical methods. The hyperconjugative energy changes accompanying structural changes from $(n-{\sigma}{\ast})_{trans}$ to (n-{\sigma}{\ast})cis were underestimated in the EHT, CNDO/2 and MINDO/3, whereas those were overestimated in the MNDO. The net destabilizing effect of $(n-{\sigma}{\ast})_{trans}$ structure was mainly due to the large internuclear energy involved in the structure. Through-space interaction between $n_1$ and $n_2$ orbitals of diradical caused energy gap narrowing of ${\Delta}E_{sp}$ and ${\Delta}{\varepsilon}={\varepsilon}_0$-${\varepsilon}_{av}$; through-space interaction had opposing effect to that of through-bond interaction. Due to the less severe neglect of differential overlaps in the MNDO, this energy gap narrowing effect appeared amplified in the MNDO. In general orbital properties were found to be reproduced satisfactorily, but eigenvalue properties were not, in all the semi-empirical methods especially when ${\sigma}-{\sigma}{\ast}$ and n-$n-{\sigma}{\ast}$interactions were involved.

• Journal of Families and Better Life
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• v.27 no.3
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• pp.79-91
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• 2009

The purpose of this study is to understand the reduction of energy consumption and demand level for education relating to the reduction of energy consumption by middle school students. First, the perception of the reduction of energy consumption had a significant relationship with sex and grade. Second, the demand level for education relating to the reduction of energy consumption showed a significant relationship with only sex. Third, regression analysis on the influence of perception of the reduction of energy consumption showed a correlation between theperception of a reduction of energy consumption and the demand level for education relating to a reduction of energy consumption. The research suggests that students want an education that reduces energy consumption at school implemented during experience-centered and activity-centered discretionary activities, rather than duringtheory-centered curricular activities. It also suggests that overcoming limitations of space, that is, implementation of such education at various places besides school, and the application of teaching and teaming methods which use the internet and image media are more effective for education for the reduction of energy consumption.

• Journal of Energy Engineering
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• v.27 no.3
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• pp.28-35
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• 2018

Guidelines and institutional support for buildings are being promoted around the world as measures for environmental pollution and energy conservation. In Korea, standards are prepared according to the energy saving design standards of new buildings as amended in 2013.09.01 and the zero energy building for new buildings mandatory process is being prepared from the recommendations. Nevertheless, the government's binding power on smaller buildings is insufficient. Energy savings were analyzed for the recently constructed office buildings (application of external insulation technique) and propose a dual envelope techniques were proposed for energy reduction.

• Journal of the Korean Solar Energy Society
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• v.30 no.6
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• pp.44-49
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• 2010

The purpose of this study is to analyze the situation of energy consumption and its characteristics in large scale store. The related survey is carried out in large scale store to investigate the energy consumption and energy use trend of heating, cooling, hot water, lighting, ventilation, equipments and others. The area of large scale discount store is about $65000m^2$, located in Daejeon. For Annual Energy Analysis of building, We surveyed used energy for 1 year and simulated using a building energy simulation(TRNSYS 16). The results of this study are as follows. 1)The amount of annual total energy consumption are 18615.244MWh/yr(286.4KWh/$m^2yr$), The rate of heating, cooling and base energy(for hot water, lighting, ventilation, equipments, cooking and others) is 3054MWh/yr(47kWh/$m^2yr$), 5660.09MWh/yr(87.08kWh/$m^2yr$), 9900.47MWh/yr(152.31KWh/$m^2yr$) respectively. The total used energy is higher than others building in Korea. Especially, The energy consumption of large scale store is very depends on operating period and pattern such as space temperature, occupancy, lighting system, equipments operating schedule and etc.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.369-374
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• 2015

This study analyzed analyzes the energy performance of six houses in Daejeon completed which were built in 2011. Observed The observed houses, which were all designed and constructed inof the same size and structure, are were highly insulated with triple Low-E coating windows; the insulation level of the walls is was $0.13W/m^2K$ and that of the roof is was $0.10W/m^2K$. As electric houses, all of the energy supplied to the houses, including for cooking, is was supplied by electricity. A and 3~4 kWp of photovoltaic system and a 3~5 kW of ground source heat pump (GSHP) were installed in each house tofor providing provide space heating/and cooling and hot water are installed. We constructed a Web-based remote monitoring system in order to understand energy consumption and the dynamic behavior of the energy system. T, and the results of our metering data analysis of 2013 are as follows. First, the annual residential energy consumption is was 4,400 kWh (${\sigma}=1,209$) and GSHP energy consumption is was 5,182 kWh (${\sigma}=1,164$). Second, residential energy consumption ranked highest in average energy usage, with at 45% of the total, followed by heating with at 30%, hot water supply with at 17% and cooling with at 6%. Third, the average energy independence rate is was 51.8%, the GFA (Gross gross floor area) criteria average energy consumption unit is was $48.7kWh/m^2yr$ (${\sigma}=10.1$), and the net energy consumption unit (except the energy yield of the PV systems) is was $24.7kWh/m^2yr$ (${\sigma}=8.8$).

• Journal of Energy Engineering
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• v.19 no.3
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• pp.195-202
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• 2010

A third of primary energy is lost as a waste heat. To improve this inefficient use of energy, systems using chemical reaction have been suggested and studied. In this study, methanol decomposition/synthesis reaction as a chemical reaction was selected for long time heat storage and long distance heat transport system because of safe, cheap and gaseous product. The purpose of this study is to find the optimal conditions in the methanol decomposition and synthesis reactions for long distance heat transport. Several parameters such as reaction temperature, pressure, $H_2$/CO ratio, space velocity, catalyst particle size were tested to find the effects on the reaction rates for the methanol synthesis. And the reaction temperature, space velocity, catalyst particle size were tested to find the effects on the production concentration for the methanol decomposition.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.10
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• pp.927-934
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• 2011

Design parameter analysis is performed for a solar-powered UAV, storing potential energy by climb flight. Parameters related to the flight for saving potential energy, i.e. minimum & maximum altitudes for level flight, gliding & climbing angle, design point speed & altitude, gliding & climbing start time are investigated as design parameters. Weight and size of the UAV are determined using a weight model for the components of the solar-powered UAVs. Produced energy and consumed energy are calculated using these weight and size, yielding the required weight of the battery for a given mission. Relationship between the total weight of the UAV and each parameter is investigated. For the parameters listed above, there exist their ranges only where the design is possible. And there exist optimal values of these parameters minimizing the total weight.

• Journal of Astronomy and Space Sciences
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• v.27 no.3
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• pp.253-262
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• 2010

The electrical power system (EPS) of Korean satellites in low-earth-orbit is designed to achieve energy balance based on a one-orbit mission scenario. This means that the battery has to be fully charged at the end of a one-orbit mission. To provide the maximum solar array (SA) power generation, the peak power tracking (PPT) method has been developed for a spacecraft power system. The PPT is operated by a software algorithm, which tracks the peak power of the SA and ensures the battery is fully charged in one orbit. The EPS should be designed to avoid the stress of electronics in order to handle the main bus power from the SA power. This paper summarizes the results of energy balance to achieve optimal power sizing and the actual trend analysis of EPS performance in orbit. It describes the results of required power for the satellite operation in the worst power conditions at the end-of-life, the methods and input data used in the energy balance, and the case study of energy balance analyses for the normal operation in orbit. Both 10:35 AM and 10:50 AM crossing times are considered, so the power performance in each case is analyzed with the satellite roll maneuver according to the payload operation concept. In addition, the data transmission to the Korea Ground Station during eclipse is investigated at the local-time-ascending-node of 11:00 AM to assess the greatest battery depth-of-discharge in normal operation.