• Proceedings of the KIEE Conference
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• 2005.11b
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• pp.145-147
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• 2005

This paper presents a methodology for satisfying the thermal comfort of Indoor environment and reducing the summer peak demand power by minimizing the power consumption for an Air-conditioner within a space. KEPCO(Korea Electric Power Corporation) use the fixed duty cycle control method regardless of the indoor thermal environment. This method has disadvantages that energy saying depends on the set-point value of the Air-Conditioner and DLC has no net effects on Air-conditioners if the appliance has a lower operating cycle than the fixed duty cycle. A variable duty cycle estimates the PMV(Predict Mean Vote) at the next step with a predicted temperature and humidity coming from the back propagation neural network model. It is possible to reduce the energy consumption by maintaining the Air-conditioner's OFF state when the PMV lies in the thermal comfort range. The proposed methodology uses the historical real data of Sep. 7th, 2001 from a classroom in seoul to verify the effectiveness of the variable duty cycle method comparing with fixed duty cycle. The result shows that the variable duty cycle reduces the peak demand to 2.6times more than fixed duty cycle and increases the load control ratio by 8% more. Based on the variable duty cycle control algorithm, the effectiveness of DLC is much more improved as compared with the fixed duty cycle.

• Smart Structures and Systems
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• v.14 no.3
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• pp.327-345
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• 2014

This paper presents a composite control strategy for the active suppression of vibration due to the unknown disturbances, such as external excitation, harmonic effects and control spillover, as well as high-frequency accelerometer measurement noise in the all-clamped stiffened plate. The proposed composite control action based on the modal approach, consists of two contributions including feedback part and feedforward part. The feedback part is the well-known PID controller, which is widely used to increase the structure damping and improve its dynamic performance close to the resonance frequencies. In order to get better performance for vibration suppression, the weight matrixes is optimized by chaos sequence. Then an improved disturbance observer (IDOB) as the feedforward compensation part is developed to enhance the vibration suppression performance of PID under various disturbances and uncertainties. The proposed IDOB can simultaneously estimate the various disturbances dynamically as well as measurement noise acting on the system and suppress them by feedforward compensation design. A rigorous analysis is also given to show why the IDOB can effectively suppress the unknown disturbances and measurement noise. In order to verify the proposed composite control algorithm (IDOB-PID), the dSPACE real-time simulation platform is used and an experimental platform for the all-clamped stiffened plate active vibration control system is set up. The experimental results demonstrate the effectiveness, practicality and strong anti-disturbances ability of the proposed control strategy.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.6
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• pp.328-336
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• 2015

Currently, 22% of the total energy consumption of buildings in Korea is used for lighting. Light-shelves have garnered attention as a way to reduce consumption, but there are few studies on the types of curve and curvature, which limits the improvement of light-shelf performance and its design. This study constructed a test bed of actual residential types to evaluate the performance. Outcomes of light usage, according to variables of light-shelves, were used as indicators of performance evaluation. The results are as follows:1) Performance evaluation was conducted on flat-type light-shelves to verify performance of curvature-shelves, which are movable with a width of 200 mm, and the most ideal angle and specification per solar term are calculated. 2) The (-) shaped curvature contributed to a reduction in energy consumption and an improvement of evenness. 3) In case of light-shelves with (-) shaped curvature, an increased angle not exceeding $80^{\circ}$ of the arc contributed to an improvement of light penetration. 4) Appropriate specifications of curved light-shelves include movable types with widths of 200 mm, and angle ranges of $20^{\circ}{\sim}60^{\circ}$. 5) Light energy consumption of a movable light-shelf with curvature and width of 200 mm were reduced by 17% and 7.8% compared to a $0^{\circ}$ fixed and a movable light-shelf, respectively.

• Journal of the Korean Geographical Society
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• v.45 no.1
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• pp.1-10
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• 2010

Low-carbon green waterfront cities for overseas cases were reviewed to propose the direction for Korea. The implications suggested include energy saving by resource circulation, compact land use planning, transit oriented development, and utilization of renewable energy. These in turn suggest the following implementations; (1) Energy saving according to compact city, complex land use, and transit oriented development, (2) Renewable energy use in buildings and daily lives, (3) Expansion of green space for carbon mitigation and improved quality of life, and (4) Water and resource circulation system. We finally discussed that development of the green waterfront cities in Korea requires the fundamentals of low-carbon green waterfront cities achieved by overseas cases study and technical investigation.

• Journal of Hydrogen and New Energy
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• v.22 no.2
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• pp.249-256
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• 2011

In this study, the Ni-based catalysts for the production of synthetic natural gas were prepared by various preparation methods such as the co-precipitation, precipitation, impregnation and physical mixing methods. The ranges of the reaction conditions were the temperatures of 250~$350^{\circ}C$, $H_2$/CO mole ratio of 3.0, the pressures of 1 atm and the space velocity of 20000 $ml/g_{-cat{\cdot}}{\cdot}h$. It was found that the catalyst prepared by precipitation method had higher CO conversion than the catalyst prepared by co-precipitation method. While the catalyst prepared by precipitation method had the formation of NiO structure, the catalyst prepared by co-precipitation method had the formation of $NiAl_2O_4$ structure. It was confirmed that Ni-based catalyst prepared by the physical mixing method had the lowest CO conversion because it was deactivated by the production of $Ni_3C$ during the methanation. As a result, it was shown clearly that Ni-based catalysts prepared by impregnation method expressed the highest catalytic activity in CO methanation.

• The Journal of Information Technology
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• v.10 no.2
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• pp.37-45
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• 2007

The multiple-ability which the structure and the physical properties which the carbon or scull tube are unique show the applicability is superior in the plane indication element which is an indispensability of information communications apparatus, the stubbornness memory element, 2nd change of air and the rough copy dosage [khay] plaque seater, the hydrogen store material and the chemical sensor back and it has the possibility which will pass over the limit which the element of existing has. from the present paper it compared in the steel and only 10 the boat it did and it analyzed against an energy storage space voluntary application and developmental apply the carbon or scull tube trend in order about under researching the effective energy storage element it could be appeared, the technique of the strong carbon nano tube. 1. The hazard which embodies the energy storage element which uses the carbon or scull tube it follows in the function which stands and CNT of the structure which is various is necessary. 2. CNT fabrications of each one must precede possible not only must be each Cabinet conference circumstances quality gain and loss. 3. The structural control of syntheses, length controls, diameter controls and the metal - CNT junction control backs of quality CNT must precede. Applies the hereafter carbon or the scull tube in the various element with the primary preceding base technique for the structural plan technique of the carbon or scull tube to be certainly established, it does, secondarily the various element functional control technique which uses the carbon or scull tube is researched and will do.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.2
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• pp.137-143
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• 2015

During the past 30 years, DRAM has been used for the reasons of economic efficiency of the production. Recently, PRAM has been emerged to overcome the shortcomings of DRAM. In this paper, we propose a technique that can reduce energy consumption by use of a narrow values to the write operation of PRAM. For this purpose, we describe the data compression method using a narrow value and the architecture of PRAM, We also experiment under the Simplescalar 3.0e simulator and SPEC CPU2000 benchmark environments. According to the experiments, the data hit rate of PRAM was increased by 39.4% to 67.7% and energy consumption was reduced by 9.2%. In order to use the proposed technique, it requires 3.12% of space overhead per word, and some additional hardware modules.

• Geophysics and Geophysical Exploration
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• v.20 no.3
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• pp.121-128
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• 2017

Interpretation of time-domain electromagnetic (TEM) data has been made mostly based on one-dimensional (1-D) inversion scheme in Korea. A proper interpretation of TEM data should employ 3-D TEM forward and inverse modeling algorithms. This study developed a 3-D TEM modeling algorithm using a finite difference time-domain (FDTD) method with staggered grid. In numerically solving Maxwell equations, fictitious displacement current is included based on an explicit FDTD method using a central difference approximation scheme. The developed modeling algorithm simulated a small-coil source configuration to be verified against analytic solutions for homogeneous half-space models. Further, TEM responses for a 3-D anomaly are modeled and analyzed. We expect that it will contribute greatly to the precise interpretation of TEM data.

• Tunnel and Underground Space
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• v.22 no.5
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• pp.339-345
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• 2012

Information on the deformation behavior and fracture strength of rocks subjected to dynamic loadings is important to stability analyses of underground openings underground vibration due to rock blasts, earthquakes and rock bursts. In this study, Split Hopkinson Pressure Bar (SHPB) system was applied to estimate dynamic compressive and tensile fracture strengths of limestone and also examine deformation behavior of limestones under dynamic loadings. A micro-focus X-ray CT scanner was used to observe non-destructively inside the impacted limestone specimens. From the dynamic tests, it was revealed that the limestone have over 140MPa dynamic compressive strength and the strain-rate dependency of the strength. Dynamic Brazilian tensile strength of the limestone exceeds 21MPa and shows over 3 times static Brazilian tensile strength.

• Journal of the Korean housing association
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• v.28 no.1
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• pp.37-44
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• 2017

This study focuses on the university dormitory remodeled toward energy efficiency. The study has its purpose on deriving the aspects to be concerned for later green remodeling and enhancing the effects of green remodeling, by analyzing the changes of physical environment, changes of energy consumption amount, and needs of the residents. For this purpose, the study went through the review of project report from government office for green remodeling, field investigation of remodeling elements, and the occupancy evaluation by Focus Group Interview. FGI means interviewing small group of the residents who lived in the subjected dormitories both before and after the remodeling. As results, the elements of green remodeling in targeted dormitories were inner wall insulation, top-floor ceiling insulation, replacement of windows, installment of automatic entrance door and making transfer space connected the entrance door. As the parts of equipment system, EHP high-efficiency cooler, highly efficient radiator, upgraded LED lightings with covers, and automatic control system (only one building) were installed. Energy consumption was declined, and the satisfaction of residents was increased after the green remodeling. However, the aspects which were not improved or unsatisfying also have been detected. Therefore, the study states the suggestions each for the administrators, designers and planners, and residents to concern for enhancing the effects of green remodeling or construction of new dormitories.