• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1403-1406
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• 2002

Environmental impact of human activities has become a great concern in most of the countries world-wide, and for years. It has recently focused on potential climate changes due to the increase of green house gases content in the atmosphere. One of these gases is $SF_6$, which is an essential material in electrical applications having excellent dielectric and arc-quenching properties. Though the actual contribution of $SF_6$ to global warming is negligible at present, the control of $SF_6$ emissions seems to be nevertheless imperative. Actually, it is listed in the Kyoto protocol that emissions should not only be duly reported but also the electrical industry which is now the major user of this gas must be able to show that it is possible to use this gas and at the same time preserve the environment. For the development of environmentally-benign electric power equipment and systems, novel gases or gas mixtures are strongly required as the alternatives of $SF_6$ gas. Until now, most research work is focused on the $SF_6/N_2$ mixed gas which is suitable for application in the electrical apparatus with slightly non-uniform fields. Recently, $SF_6/CO_2$ mixed gas also is expected to be promising as a $SF_6$ alternative, especially in highly non-uniform fields and in a gas-impregnated film insulation system. Including these results, the author reviews the research trend or reducing the environmental impact of $SF_6$ gas in this paper.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.20 no.2
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• pp.232-237
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• 2008

A method to generate electric power from small scale water tank. For this purpose, manufacturing tank is investigated, measuring water level change at any time, and finally comparing experimental and theoretical value, are performed. Inner and outer tank are made to simulate flood and ebb generation. Two sets of pipe are connected between tanks, and experiments are performed under varying flowrate. Coefficients of flowrate are calculated comparing water level change data and theoretical value. Measured and theoretical water levels are highly correlated, and this ascertains that analytical equation simulates real water level changes well. Flowrate change depending on the existence of propeller and valve, on flood and ebb generation, shows the necessity of experiments in the process of manufacturing electric power system. Moreover, total energy calculated from experimental data agrees well with that of theoretical equation. In spite of small tidal power output, this generating system with optimum water tank can be applied to any place where high water level change occurs, and can make a contribution to producing new and renewable energy consequently.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.5
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• pp.499-506
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• 2015

Recently the Korean government announced its decision to select the $3^{rd}$ proposal, which targets reducing $CO_2$ by 37% of the BAU level by 2030, for the Intended Nationally Determined Contribution (INDC). According to this proposal, natural gas (or equivalent gas) combined cycle (NGCC) are suggested as alternatives for conventional pulverized coal (PC). In this study, we analyzed the environmental, economic, and energy mixing aspects of synthetic natural gas combined cycle(SNGCC) using NETL material (2011~2012 version) and other domestic materials (2014 version). We found the following conclusions: 1) Considering carbon capture and storage (CCS) integration, $CO_2$ emission factors of SNGCC and supercritical PC are the same. However, 60% of $CO_2$ from SNGCC is produced as high pressure and high purity (99%) gas, making it highly suitable for CCS, which is now strongly supported by the government. 2) Based on the economic analysis for SNGCC using domestic materials and comparison with NGCC, it was found that the settlement price of SNGCC was 30% lower than that of NGCC.

• Journal of Radiation Protection and Research
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• v.17 no.2
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• pp.61-70
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• 1992

Photon, neutron and beta radiation fields were measured at PWR plants which are the representative types of nuclear power plant operated in Korea. The photon energy spectra were measured at locations in the auxiliary building during operation period and in the containment vessel(C/V) during shutdown period using a portable gamma spectrometer with a HPGe detector. The distribution of average energy was found to range from 440 to 780 keV in the C/V and from 280 keV to 760 keV in the auxiliary building, respectively. The average neutron energy measured at the five locations around the operation deck in the C/V in operation using a BMSS (Bonner Multi-Sphere Spectrometer) ranged from 20 keV to 210 keV. A computer code, BUNKI was used to unfold the spectrum. The beta energy spectra in the C/V and in the auxiliary building in annual outage were determined using 14 smear samples taken from the highly contaminated areas. The analysis showed that the representative corrosion product, $^{60}Co$ made main contribution to the beta energy field.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.175-180
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• 2009

Today, the amount of energy consumption at the university campuses is huge. The effort for the energy consumption reduction in university campuses is certainly needed by the following reason; first, contribution for the reduction request about green house gas emission. Second, energy cost reduction in university campus. Third, emotional spreading influence consideration as the maximum higher educational institutions. For the energy consumption reduction in university campus, the energy consumption analysis of current situation has to be executed. The energy reduction possibility in which it exists in university campus can be understood through the energy consumption analysis. And the application is possible as fundamental data of the policy establishment for the effective energy reduction in university campuses. This research analyzed the energy consumption present state of the major university campus of the Korea as the fundamental research for the energy consumption reduction plan preparation of the university campus. Moreover, surveys were performed and analyzed for the energy manager in charge of the university campus.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.1-8
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• 2005

The quantity of light available for a space can be translated in term of the amount of energy savings through a process of a building energy simulation. To get significant energy savings in general illumination, the electric lighting system must be incorporated with a daylight - activated dimmer control. A prototype configuration of an once interior has been established and the integration between the building envelope and lighting and HVAC systems is evaluated based on computer modeling of a lighting control facility. First of all, an energy-efficient luminaire system is designed and the lighting analysis program, Lumen-Micro 2000 predicts the optimal layout of a conventional fluorescent lighting future to meet the designed lighting level and calculates unit power density, which translates the demanded met of electric lighting energy. A dimming control system integrated with the contribution of daylighting has been applied to the operating of the artificial lighting. Annual cooling load due to lighting and the projecting saving amount of cooling load due to daylighting under overcast diffuse sky m evaluated by computer software ENER-Win. In brief, the results from building energy simulation with measured daylight illumination levels and the performance of lighting control system indicate that daylighting can save over 70 percent of the required energy for general illumination in the perimeter zones through the year A 25[%] of electric energy for cooling and almost all off heating energy may be saved by dimming and turning off the luminaires in the perimeter zones.

• Smart Structures and Systems
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• v.24 no.3
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• pp.333-343
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• 2019

The possibility of adopting vibration-powered wireless nodes has been largely investigated in the last years. Among the available technologies based on the piezoelectric effect, the most common ones consist of a vibrating beam covered by electroactive layers. Another energy harvesting strategy is based on the use of piezoelectric strips attached to a hosting structure subjected to dynamic loads. The hosting structure, for example, can be the system to be equipped with wireless nodes. Such strategy has received few attentions so far and no analytical studies have been presented yet. Hence, the original contribution of the present paper is concerned with the development of analytical solutions for the electrodynamic analysis and design of piezoelectric polymeric strips attached to relatively large linear elastic structural systems subjected to random vibrations at the base. Specifically, it is assumed that the dynamics of the hosting structure is dominated by the fundamental vibration mode only, and thus it is reduced to a linear elastic single-degree-of-freedom system. On the other hand, the random excitation at the base of the hosting structure is simulated by filtering a white Gaussian noise through a linear second-order filter. The electromechanical force exerted by the polymeric strip is negligible compared with other forces generated by the large hosting structure to which it is attached. By assuming a simplified electrical interface, useful new exact analytical expressions are derived to assess the generated electric power and the integrity of the harvester as well as to facilitate its optimum design.

• Asian Journal of Atmospheric Environment
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• v.4 no.3
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• pp.150-156
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• 2010

Inter-comparison of chemical transport models (CTMs) was conducted among four modeling research groups. Model performance of the ensemble approach to $O_3$ and $PM_{2.5}$ simulation was evaluated by using observational data with a time resolution of 1 or 6 hours at four sites in the Kanto area, Japan, in summer 2007. All groups applied the Community Multiscale Air Quality model. The ensemble average of the four CTMs reproduced well the temporal variation of $O_3$ (r=0.65-0.85) and the daily maximum $O_3$ concentration within a factor of 1.3. By contrast, it underestimated $PM_{2.5}$ concentrations by a factor of 1.4-2, and did not reproduce the $PM_{2.5}$ temporal variation at two suburban sites (r=~0.2). The ensemble average improved the simulation of ${SO_4}^{2-}$, ${NO_3}^-$, and ${NH_4}^+$, whose production pathways are well known. In particular, the ensemble approach effectively simulated ${NO_3}^-$, despite the large variability among CTMs (up to a factor of 10). However, the ensemble average did not improve the simulation of organic aerosols (OAs), underestimating their concentrations by a factor of 5. The contribution of OAs to $PM_{2.5}$ (36-39%) was large, so improvement of the OA simulation model is essential to improve the $PM_{2.5}$ simulation.

• Membrane Journal
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• v.23 no.3
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• pp.189-203
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• 2013

F-gases, gases containing fluorine such as perfluorocarbons (PFCs), sulfurhexafluoride ($SF_6$), nitrogen trifluoride ($NF_3$) are known to have green house effects. Although the net emission rates of gases containing fluorine are much lower than those of $CO_2$, their contribution to global warming cannot be ignored because of their extremely high global warming potential (GWP). F-gases mainly have been used for a variaty of applications in the semiconductor/LCD processes and in the electric power distribution industry of the national key industry. One of practical solutions of controlling the emission rates of F-gases is to reuse by separation and recovery of F-gases of low concentration from the gases mixtures with nitrogen or air. This work investigates some methods for F-gases recovery and separation around the membrane-based process.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.497-502
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• 2014

The conversion reaction of methane and carbon dioxide at an atmospheric pressure plasma reactor filled with Ni-$Al_2O_3$ and Ni-$MgAl_2O_4$ catalyst was performed. Effects of various process parameters such as the applied electric power, reaction gas flow rate, reactor temperature, mixing ratio of reactants and the presence of the catalyst on the reaction between methane and carbon dioxide were analyzed. From the analysis of the contribution of the catalyst in the reaction step, even if the temperature raised to $400^{\circ}C$, there was no spontaneous catalytic conversion of methane and carbon dioxide without plasma discharges. When the catalysts for the conversion of methane and carbon dioxide would be adopted to the plasma reactor, the careful selection of suitable catalysts and process parameters should be essential.