• The Journal of Sustainable Design and Educational Environment Research
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• v.14 no.3
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• pp.9-17
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• 2015

In this paper, there are several analysis on G-SEED, Building Energy Efficiency Rating System, Energy Performance Index, Energy Saving Plan about how they are applied by classification and planning standard. The analysis result found out that G-SEED has low select percentage by having difficulties to managing and additional cost when the each class is selected. And also, Building Energy Efficiency Rating System in school is planed in comparably simple design and similar size and also mostly uses high efficient machines, which was in high lever comparing to the system in facilities in other uses. In the case of EPI, there are differences on acquiring grades by each region. Especially, Gyung-gi region has a low grade on architecture part comparing to other parts, which seems to acquire more grades by strengthen insulation performance. By the result from the three standards, many facilities has only formal plan to pass the required standard without considering specialities of each buildings, which has a tendency to have a pattern to have a minimum criteria. However, School has a symbolic building which has a obligation to be the base of the aim for growing green energy buildings and green education for students. Therefore, planning with understanding of specialities of the facility, having various and rational evaluation standards from the planning of the building is necessary.

• 전기의세계
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• v.2
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• pp.6-14
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• 1949

Telemetering may be described as the art of metering at a considerable distance those quantities which are ordinarily encountered in industry, and in the generation of electric power. It is in the production of electric power that telemetering is particularly important, for it permits the system operator, or load dispatcher, to have before him at all times a continuous graphic record of the power output of each individual generating station together with an automatically made continuous graphic record of the total system output. There desired individual graphic records may be obtained showing power flow in or out, on important tie lines, etc. Such arrangements have the very great advantage that loads may be assigned to each generating station so that the best over-all system economy may be obtained and the system operator at all times may see with his own eyes that loads scheduled are actually held at the various stations. Moreover, with such equipment, in the event of system or station trouble the load dispatcher can see exactly what station, or stations, are affected and to what extent, without having to get in touch with anyone by telephone. Decisions can, therefore, be quickly reached for rescheduling the load. One of the most accurate and reliable telemetering systems is based on the use of potentiometric circuits, the fundamentals of which are discussed below. A member of such telemetering systems have been installed for the Boston Edicon Co., Boston, Massachusetts, the Consolidated Edison Co. of New York City. The Public Service Gas & Electric Co. of Newark, new Jersey. The Philadelphia Electric Co. for Philadelphia, Pennsylvania, and the Pennsylvania Railroad Co. for their electrified zone between New York and Washington a distance of over 200 miles. The scale of the totalizing recorder for the New York area is 3,000,00 KW. That of the totalizing recorder for the Philadelphia area is 2,000,000 KW. The initial installation using this type of equipment described was placed in service for the Philadelphia Electric Co. in 1923. All of the original recording instruments are still in service, later instruments have been added to take care of additions to the power system and naturally these later recorders have incorporated in those refinements in design made since the earlier ones were manufactured. Many other installations of similar equipment have been made in the United States in various locations such as at St. Louis, on the West Coast, at Baltimore and in Washington, D.C. While the use of these basic potentiometric circuits involves the use of continuous metallic circuits of good insulation resistance and free of grounds, nevertheless, intermediate transmission links, involving and impulse method suitable for use on telephone Morse carrier channels is available. This same method may be employed on power line carrier systems and is also suitable for use on beam type microwave transmission. Many impulse type units are also used as a link in these potantiometric methods. For the sake of brevity a description is given only of these basic potentiometric circuits. If there is sufficient interest in Korea, a further paper can be given covering those impulse circuits also.

• Transactions on Electrical and Electronic Materials
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• v.11 no.6
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• pp.261-265
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• 2010

In this paper, we attempt to improve the electrical characteristics of epoxy resin at high temperature (above $80^{\circ}C$) by adding magnesium oxide (MgO), which has high thermal conductivity. Scanning electron microscopy (SEM) of the dispersion of specimens with added MgO reveals that they are evenly dispersed without concentration. The dielectric breakdown characteristics of $SiO_2$ and MgO nanocomposites are tested by measurements at different temperatures to investigate the filler's effect on the dielectric breakdown characteristics. The dielectric breakdown strength of specimens with added $SiO_2$ decreases slowly below $80^{\circ}C$ (low temperature) but decreases rapidly above $80^{\circ}C$ (high temperature). However, the gradient of the dielectric breakdown strength of specimens with added MgO is slow at both low and high temperatures. The dielectric breakdown strength of specimens with 0.4 wt% $SiO_2$ is the best among the specimens with added $SiO_2$, and that of specimens with 3.0 wt% and 5.0 wt% MgO is the best among those with added MgO. Moreover, the dielectric strength of specimens with 3.0 wt% MgO at high temperatures is approximately 53.3% higher than that of specimens with added $SiO_2$ at $100^{\circ}C$, and that of specimens with 5.0 wt% of MgO is approximately 59.34% higher under the same conditions. The dielectric strength of MgO is believed to be superior to that of $SiO_2$ owing to enhanced thermal radiation because the thermal conductivity rate of MgO (approximately 42 $W/m{\cdot}K$) is approximately 32 times higher than that of $SiO_2$ (approximately 1.3 $W/m{\cdot}K$). We also confirmed that the allowable breakdown strength of specimens with added MgO at $100^{\circ}C$ is within the error range when the breakdown probability of all specimens is 40%. A breakdown probability of up to 40% represents a stable dielectric strength in machinery and apparatus design.

• Fire Science and Engineering
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• v.24 no.6
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• pp.7-12
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• 2010

This paper is aimed the measurement and estimation the thermal interrelation based on leakage current. The leakage models are analyzed by parameters in open and closed (Panel) states and with wood dust and rainwater, charcoal powder in leakage current occurred point. The thermal characteristic of open state that leakage current is inputted in 90 mA is higher in charcoal powder ($105^{\circ}C$) than in wood dust and rainwater ($88.8^{\circ}C$). Charcoal powder that is inputted in 110 mA shows high thermal characteristic ($238.6^{\circ}C$) and the thermal ($238.6^{\circ}C$) is caused by material strain of electrical wire insulation and Panel. The closed state in 90 mA is higher in charcoal powder ($250.6^{\circ}C$) than in wood dust and rainwater ($90.8^{\circ}C$). The open and closed state appear thermal characteristics of two times in charcoal powder than in wood dust and rainwater. The thermal data that are open and close states are used electrical fire investigation and thermal characteristic for Leakage current.

• Journal of Korean Society of Steel Construction
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• v.18 no.5
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• pp.543-551
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• 2006

Cold-formed steel studs that are being used as load-bearing members of wall panels for steel houses have a problem with their insulation due to the heat bridging of their web. Some additional thermal insulating materials should be used. To solve this problem, the new-concept hybrid stud, which consists of a galvanized steel sheet (t = 1.0 m - 12.0 m) and a GFRP panel (t = 4.0-6.0 mm), has recently been developed. An investigation on the structural behavior and the strength capacity of this new hybrid stud has been conducted so that it can be used in load-bearing wall panels of residential buildings. This paper describes the axial compression-torsion test results of the hybrid studs under both axial compression and torsion using ATTM. The main factors of the test were the stud length, the magnitude of the initial compressive force, and the loading method of the monotonic or cyclic loading. The torsion was applied increasingly while the initial compression was kept constant to the failure of the hybrid section. The advanced analysis results obtained form the finite element procedure that considered the material properties of the high-strength galvanized steel and the GFRP were compared with the test results for verification.

• Journal of the Korean Geotechnical Society
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• v.21 no.6
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• pp.41-52
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• 2005

Because the allowable current loading of buried electrical transmission cables is frequently limited by the maximum permissible temperature of the cable or of the surrounding ground, there is a need fur cable backfill materials that can maintain a low thermal resistivity even while subjected to high temperatures for prolonged periods. Temperatures greater than $50^{\circ}C\;to\;60^{\circ}C$ may lead to breakdown of cable insulation and thermal runaway if the surrounding backfill material is unable to dissipate the heat as rapidly as it is generated. This paper describes the results of studies aimed at the development of backfill material to reduce the thermal resistivity. A large number of different additive materials were tested to determine their applicability as a substitute material. Tests were carried out for Dongrim river sand, a relatively uniform sand of very high thermal resistivity, $50^{\circ}C-cm/watt\;at\;10\%$ water content, $260^{\circ}C-cnuwatt$ when dry, and Jinsan granite screenings, and D-2 (sand and granite screenings mixture), E-1 (rubble and granite screenings mixture), a well-graded materials with low thermal resistivity, about $35^{\circ}C-cm/watt$ when at 10 percent water content, $100^{\circ}C-cm/watt$ when dry. Based on this research, 3 types of backfill materials were suggested for improved materials with low thermal resistivity and the applicability was assessed through field tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.518-527
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• 2020

The establishment of a green remodeling strategy is focused on technology, so the necessity of establishing a customized strategy considering the field situation has emerged. This paper examined the technology strategy through sensitivity analysis as a methodology for guiding strategy. For a 90-square-meter detached house, nine models of the construction standards of pre-1980s, 1984, and 2010 in Seoul, Daejeon, and Busan were assessed using the optimization method that combines the energy plus engine and the ModeFrontier. Sensitivity analysis was performed, and the remodeling strategy priority was derived. For pre-1980 models, the strategy for enhancing the roof insulation performance had a significant priority. The SHGC values of the windows were found to have the next highest priority regardless of the region and the time of completion, showing that the performance standard, including the SHGC, needs to be expanded. The possibility of remodeling while maintaining the existing geometry was confirmed because the adjustment of the window wall ratio accompanying large-scale demolition works has low priority. The priorities of technology strategies in each case showed very different patterns, suggesting the possibility of establishing a remodeling strategy by a comprehensive evaluation along with economics and constructability analysis.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.203-209
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• 2017

Research on condition monitoring and diagnosis of power facilities has been conducted to improve the safety and reliability of electric power supply. Although insulation diagnostic techniques for unit equipment such as gas-insulated switchgears and transformers have been developed rapidly, studies on monitoring of cables have only included aspects such as whether defects exist and partial discharge (PD) detection; other characteristics and features have not been discussed. Therefore, this paper dealt with PD characteristics against void sizes and positions, and with defect localization in XLPE cable. Four types of defects with different sizes and positions were simulated and PD pulses were detected using a high frequency current transformer (HFCT) with a frequency range of 150kHz~30MHz. The results showed that the apparent charge increased when the defect was adjacent to the conductor; the pulse count in the negative half of the applied voltage was about 20% higher than that in the positive half. In addition, the defect location was calculated by time-domain reflectometry (TDR) method, it was revealed that the defect could be localized with an error of less than1m in a 50m cable.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.405-411
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• 2009

Railway signaling system in a rapid transit using the ATC system the approved a speed limit to a train and a part of signaling system in a metro approved a distance which is possible to move. Referring to the way of transmitting train control information, there are the one transmitting it to the on-board system of a train using the direct track, the another transmitting it establishing an instrument, and the other transmitting an instrument by a railway track. The one is the method using the direct track as a conductor for composing the part of the track and attaining the information controlling a train by transmitting a signal to the track. It is used for the high-speed railway and the subway. The method using the track attains information by transmitting it to returned information, and the on-board system of a train attains it by magnetic coupling. Because many reinforcing bars on the concrete slab track are used, interaction between a rail and a reinforcing bar that is not produced on ballast track is made. Due to the interaction, the electric characteristic of rail is changed. In the current paper, we numerically computed the coupling coefficient between the rail and the reinforcing bar based on the concrete slab track throughout the model related to the rail and the reinforcing bar using the concrete slab track that is used in the second interval of the Gyeongbu high-speed railway, and we defined the coupling coefficient not changed in the electric characteristic of rail in the condition that there is no interaction between the rail and the reinforcing bar.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.363-370
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• 2016

Lightweight geopolymers are more readily produced and give higher fire resistant performance than foam cement concrete. Lowering the density of solid geopolymers can be achieved by inducing chemical reactions that entrain gases to foam the geopolymer structure. This paper reports on the effects of adding different concentrations of aluminum powder on the properties of cellular structured geopolymers. The apparent density of lightweight geopolymers has a range from 0.7 to $1.2g/m^3$ with 0.025, 0.05 and 0.10 wt% of a foaming agent concentration, which corresponds to about 37~60 % of the apparent density, $1.96g/cm^3$, of solid geopolymers. The compressive strength of cellular structured geopolymers decreased to 6~18 % of the compressive strength, 45 MPa of solid geopolymers. The microstructure of geopolymers gel was equivalent for both solid and cellular structured geopolymers. The workability of geopolymers with polyprophylene fibers needs to be improved as in fiber-reinforced cement concrete. The lightweight geopolymers could be used as indoor wall tile or board due to fire resistance and incombustibility of geopolymers.