• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.13 no.8
• /
• pp.1647-1652
• /
• 2009

Generally the neural network and the fuzzy compensative algorithm are applied to forecast the time series for power demand with a characteristic of non-linear dynamic system, but it has a few prediction errors relatively. It also makes long term forecast difficult for sensitivity on the initial condition. On this paper, we evaluate the chaotic characteristic of electrical power demand with analysis methods of qualitative and quantitative and perform a forecast simulation of electrical power demand in regular sequence, attractor reconstruction, time series forecast for multi dimension using Lyapunov exponent quantitatively. We compare simulated results with the previous method and verify that the purpose one being more practice and effective than it.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.05a
• /
• pp.171-174
• /
• 2009

Generally the neural network and the fuzzy compensative algorithm are applied to forecast the time series for power demand with a characteristic of non-linear dynamic system, but it has a few prediction errors relatively. It also makes long term forecast difficult for sensitivity on the initial condition. On this paper, we evaluate the chaotic characteristic of electrical power demand with analysis methods of qualitative and quantitative and perform a forecast simulation of electrical power demand in regular sequence, attractor reconstruction, time series forecast for multi dimension using Lyapunov exponent quantitatively. We compare simulated results with the previous method and verify that the purpose one being more practice and effective than it.

• Journal of Energy Engineering
• /
• v.22 no.2
• /
• pp.112-119
• /
• 2013

The thermal performance for test system with evacuated tubular solar collector is experimentally investigated to obtain the basis data for developing new type solar collector. For this purpose, the test system was designed using CATIA and then after being manufactured, the system was tested using evacuated tubular solar collector. Numerical analysis, furthermore, was performed using ANSYS Fluent V.13 for glass evacuated tubular solar collector. The results showed that as setting temperature difference(${\Delta}T$) of system was increased, total operating(working) time was almost same in all cases, even though operating count was decreased. The results of numerical analysis showed that as temperature of solar absorber in glass evacuated tubular solar collector was high, the drop-rate of temperature of center part was increased.

• Journal of Energy Engineering
• /
• v.23 no.4
• /
• pp.189-195
• /
• 2014

The use of solar energy among renewable energy tends to increase because of its infinity and cleanness of resources. Even though the consumption rate of solar energy in our country is still low, however, in recent years, the research for solar energy have been widely conducted due to policy support of government. This study was performed to investigate the efficiency of heat collection using solar collector with single evacuated tube-type. As the results, the temperature of radiation fin for solar collector with single evacuated tube-type was lower in spite of high temperature of heat pipe compared that of double evacuated tube-type. In order to increase the efficiency of heat collection, it was confirmed that the loss of heat collection due to contact resistance as well as performance improvement for solar collector should be decreased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.10
• /
• pp.4658-4664
• /
• 2013

This paper presents the effects of the tube materials on the heat transfer performance of double-tube heat exchangers for the development of heat exchangers using deep sea water. Heat exchangers made of titanium, aluminum. stainless steel, iron, copper, and aluminum with carbon black 0.015mm and 0.15mm coating were tested. Also, the heat transfer rate of each heat exchanger was calculated by using EES program. The calculated values were compared with the experimental ones, and the deviations were less than 10%. From the above experiment and analysis, aluminum with carbon black 15 coating can be considered the most promising candidate for the replacement of titanium heat exchanger.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.43 no.2
• /
• pp.192-199
• /
• 2016

Triple tooth is rare in primary dentition; it is the abnormal fusion of three teeth. There are a few reports of double teeth, but triple teeth are rare. These multiple teeth create several clinical problems, not only esthetic problems but also a high caries susceptibility, congenital missing permanent tooth germ(s), orthodontic problems, and periodontal problems. They also make it difficult to perform pulp treatment because of the complex tooth structure. A 1-year 7-month-old male underwent a partial pulpotomy with mineral trioxide aggregate (MTA) when pulp exposure caused by deep caries occurred at a maxillary anterior triple tooth in the first case. The second case was a 1-year 9-month-old male presenting with a fracture line at a mandibular anterior triple tooth. After removing the fractured fragment, a pulpectomy was performed at the remaining primary lateral incisors. Specific complications were not observed during 24 and 6 months of follow-up, respectively.

• Journal of the Korean Institute of Gas
• /
• v.17 no.2
• /
• pp.78-84
• /
• 2013

A numerical study on the heat and fluid flow has carried out for the design of the steam reforming reactor which consists of six reforming tubes and one burner. Reforming reaction calculation is coupled with the heat and fluid flow one. The burner type in the reforming reactor is chosen through the fluid flow calculation according to different type of burner structure. It is shown that the significant temperature gradient exists in the reforming reactor, affecting the component variation along the length of reforming tube. The component ratio of reforming gas is changed by the variation of SCR and GHSV.

• Journal of Energy Engineering
• /
• v.21 no.2
• /
• pp.168-178
• /
• 2012

The objective of this study is applied to office buildings to evaluate quantitative evaluation method about performance of double-skin at design stage to establish the basis for the purpose of evaluation performance. Select the evaluation building about design plan for applying the double-skin using the dynamic heat load analysis program the annual heating and cooling load of before and after the double-skin. Using CFD to analyze wind factor and applied ventilation for realistic results. Effects of double-skin to apply, and control techniques that can be done more realistically proposed through to set and control for shade control mode of ventilator and inside cavity wall of double-skin. Apply for the building the double-skin due to interpretation of the annual heating and cooling loads applied to interpret the quantitative effect confirmed the possibility. According to the form of a double skin was confirmed cavity environmental changes.

• Journal of the Korean Vacuum Society
• /
• v.20 no.1
• /
• pp.70-76
• /
• 2011

High-quality double-walled carbon nanotubes (DWCNTs) were synthesized by catalytic decomposition method at $800^{\circ}C$ using Tetrahydrofuran. The as-synthesized DWCNTs typically have catalytic impurities and amorphous carbon, which were removed by two-step purification process, consisting of thermal oxidation and H2O2, HNO3, HCl treatment. The DWCNT suspension was prepared by dispersing the purified DWCNTs in an aqueous sodium dodecylbenzenesulfonate solution with horn-type sonication. This was then sprayed on ITO glass to fabricate CNT field emitters. The quality of purified DWCNTs was estimated with X-ray diffraction and Thermal Gravity Analysis. The field emission properties were improved by increasing the process time of HCl treatment.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2011.11a
• /
• pp.763-768
• /
• 2011

The effects of $CO_2$-dilution on combustion instability were studied in order to apply biogas in a dual lean premixed gas turbine combustor on a real-scale dual lean premixed burner head which is originally developed for Natural Gas fuel. Combustion instability is reduced by $CO_2$ dilution effect according to the result of dynamic pressure signal and phase-resolved $OH^*$ images. The reason for this is that dilution of $CO_2$ reduces heat release perturbation and increases flame volume due to reduction of the flame speed and expansion of flame surface.