• KIEAE Journal
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• v.15 no.6
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• pp.57-62
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• 2015

Purpose: This study, which is based on the investment payback periods, aims to suggest the proper insulation level which can be adapted to the Defense Military Facility Criteria regarding the military residential condominiums. For the energy performance simulation, it is required to collect the residential data regarding the military condominiums and climatic data concerning the regions they belongs to. The estimates through energy performance simulation are the regional heating loads and the heating transmission coefficients of building components. Method: With the heating loads, the annual heating cost saving per square meters is assessed. With the heating transmission coefficients of building components, the additional insulation installment cost per square meters is evaluated. With two outcomes, one as an annual value and the other as a present value, the investment payback period is calculated. Result: In result, it could be concluded that 55~70% insulation ratio can lead a superior residental environments as well as be contributed to the national policy associated with zero-energy buildings because the estimated investment payback period is shorter than the life span of the military residental condominiums. This upshot can be used as a foundation to enactment the Defense Military Facility Criteria associated with military residential condominiums.

• Journal of Sensor Science and Technology
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• v.27 no.5
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• pp.311-316
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• 2018

An antenna-coupled bolometer-type terahertz sensor was designed, fabricated, evaluated, and utilized to obtain terahertz transmission images. The sensor consists of a thin film bowtie antenna that resonates accordingly in response to an incident terahertz beam, a heater that converts the applied current in the antenna into heat, and a microbolometer that converts the rise in temperature into a change in resistance. The device is fabricated by a bulk micromachining process on a 4-inch silicon wafer. The fabricated sensor chip has a size of $2{\times}2mm$ and an active area of $0.1{\times}0.1mm^2$. The temperature coefficient of resistance (TCR) of the bolometer film (VOx) is 2.0%, which is acceptable for bolometer applications. The output sensor signal is proportional to the power of the incident terahertz beam. Transmission images were obtained with a 2-axis scanning imaging system that contained the sensor. The small active area of the sensor will enable the development of highly sensitive focal plane array sensors in terahertz imaging cameras in the future.

• KIEAE Journal
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• v.4 no.3
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• pp.65-70
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• 2004

The purpose of this study is to analysis the thermal performance of the clayed hollow block wall. Its thermal performance was evaluated comparison with the cement block wall, it was generally used in building envelope. To that end, we conducted a insulation performance experiment and heating and cooling load simulation for a respective wall. In addition, we calculated a construction cost for each other's wall. The results of this study can be summarized as follows. (1) According to experiment of a insulation performance, coefficient of overall heat transmission of the cement block wall and clayed hollow block wall was calculated respectively $2.72W/^2K$ and $1.42W/^2K$. (2) The annular load saving of the clayed hollow block wall was evaluated 1.5% larger than its of the cement block wall. (3) The construction cost of the clayed hollow block wall was calculated 73% more expensive than its of the cement block wall. (4) The construction cost of the clayed hollow block composite wall was calculated 13.7% more expensive than its of the cement block composite wall.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.7
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• pp.73-81
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• 1992

We have investigated the thermal reaction property and the oxygen behavior of TiN/Ti/Si structure after different hear treatments using x-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy measurements. During the heat treatment in N$_2$ amibient, the considerable amount of oxygen atoms incorporates into TiN/Ti/Si Structures. It is found that oxygen atoms pile up at the top surface of TiN and TiN/Ti interface, forming a compound of TiO$_2$ above $600^{\circ}C$. Inside the TiN film, the oxygen content increases as the annealing temperature increases, mostly TiO and Ti$_2$O$_3$ rather than thermodynamically stable TiO$_2$. Above the annealing temperature of 55$0^{\circ}C$, the TiSi$_2$ formation has initiated. One thing to note is that a severe blistering is observed in the sample annealed at $600^{\circ}C$, due to (1) the difference of thermal expansion coefficient between TiN and Si` (2) the compressive stress induced by the volume reduction caused by the Ti-Silicide grain while elevating temperatures.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.219-220
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• 2023

The thermal conductivity of the insulation material has a great influence on the heat transmission coefficient, which is currently used for energy evaluation of buildings. The thermal conductivity of insulation changes with changes in the environment, such as humidity and ultraviolet rays, and can be expected to with the passage of time. But there is a lack of data on this, so this study measured the thermal conductivity of organic insulation according to environmental conditions and time, As a result, in the case of XPS, the thermal conductivity value increased over time, which is estimated to be due to the decrease in insulation performance as the foaming gas escapes to the outside, and in the case of PIR class2 No.2 and PIR noncombustible, the increased thermal conductivity value is similar, but in the case of PIR class2 No.2, a relatively moderate increase can be seen, and in the case of PIR noncombustible, a large increase is seen at the beginning, which is judged to be due to the decrease in insulation performance as the internal foaming gas is substituted with air from the outside.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1819-1824
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• 2014

The vacuum-glazing panel is a panel that keeps two glasses completely sealed in a vacuum condition. It is the high function insulation material of having the wall level minimizing the heat loss by the conduction and convection heat transmission coefficient. The edge sealing is a very important process of vacuum glass on the strength, thickness and air tightness. In this study, by using the hydrogen mixture gas torch, two sheets of glass was sealing in the furnace. The thickness and strength of the glass according to the process parameters is measurement and analysis, and predicting the edge sealing strength of glass by using taguchi method of experiment. We verified the validity of the experiment by checking the error rate through additional experiment.

• Journal of Bio-Environment Control
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• v.22 no.3
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• pp.270-278
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• 2013

The objective of the present study is to provide data needed to decide covering method to be able to increase the thermal insulation and light transmittance efficiency of commercial greenhouse. The thermal insulation effect, PPF transmittance and quantity of condensation water were estimated in experimental tomato greenhouses covered with three types of coverings of single layer, air inflated and conventional double layers covering. The overall heat flow of air inflated double layers greenhouse was similar to that of conventional double layers greenhouse, but the temperature between covering material and thermal screen in air inflated double layers greenhouse was lower than that in conventional double layers greenhouse at the same outside temperature condition due to air leakage through the gap of roof vent. The overall heat transfer coefficients acquired by experiment that was performed in single layer and conventional double layers greenhouses were close to those obtained from model experiment. Even though the PPF transmittance of air inflated double layers greenhouse was lower than that of single layer greenhouse, which was greater than that of conventional double layers greenhouse. The quantity of condensation water on covering surface of single layer greenhouse was greater than that of air inflated double layers greenhouse due to lower covering surface temperature.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.10a
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• pp.35.1-35.1
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• 2011

New photovoltaic (PV) materials and manufacturing approaches are needed for meeting the demand for lower-cost solar cells. The prototypal thin-film photovoltaic absorbers (CdTe and $Cu(In,Ga)Se_2$) can achieve solar conversion efficiencies of up to 20% and are now commercially available, but the presence of toxic (Cd,Se) and expensive elemental components (In, Te) is a real issue as the demand for photovoltaics rapidly increases. To overcome these limitations, there has been substantial interest in developing viable alternative materials, such as $Cu_2ZnSnS_4$ (CZTS) is an emerging solar absorber that is structurally similar to CIGS, but contains only earth abundant, non-toxic elements and has a near optimal direct band gap energy of 1.4~1.6 ev and a large absorption coefficient of ${\sim}10^4\;cm^{-1}$. The CZTS absorber layers are grown and investigated by various fabrication methods, such as thermal evaporation, e-beam evaporation with a post sulfurization, sputtering, non-vacuum sol-gel, pulsed laser, spray-pyrolysis method and electrodeposition technique. In the present work, we report an alternative method for large area deposition of CZTS thin films that is potentially high throughput and inexpensive when used to produce monolithically integrated solar panel modules. Specifically, we have developed an aqueous chemical approach based on chemical bath deposition (CBD) with a subsequent sulfurization heat treatment. Samples produced by our method were analyzed by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, absorbance and photoluminescence. The results show that this inexpensive and relatively benign process produces thin films of CZTS exhibiting uniform composition, kesterite crystal structure, and good optical properties. A preliminary solar cell device was fabricated to demonstrate rectifying and photovoltaic behavior.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.39-47
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• 1999

This paper describes on-line retrainable RBF network in order to control the coiling temperature for a hot coil strip at Pohang Iron & Steel Company(POSCO). The proposed neural network can be used for improving conventional rule-based lookup table, which generates a heat transmission coefficient. To cope with time-varying characteristics of hot coil process, additional synaptic weights for on-line retraining purposes are introduced to hidden-to-output weights of conventional RBF network. Those weights are locally adjusted to newly incoming test data while preserving old information trained with off-line past data. Hence the effect of catastrophic interference can be greatly alleviated with the proposed network. In addition, rejection scheme is introduced for reliability concerns. From the experimental results applied to the actual process, it is noticed that overall control performance represents about 2.2% increase compared to the conventional one.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1116-1122
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• 2009

As a result of this study, we reached the following conclusions. With appropriate setting of oil pressure and flow rate, it operated same rotation speed with existing cooler by electrical transmission. In initial operation, a temperature of a cold storage is lower rapidly. As an internal temperature of a cold storage is lower, a decreasing rate of temperature is lower. As a result of comparing the both type, the cooler of oil pressure type showed the following results. The decreasing rate of temperature was more faster and shorter operating time was more shorter than existing cooler of electric type. The actual case of a cold storage, the cooler of oil pressure type can prevent quality deterioration and decrease power consumption. As an internal temperature of a cold storage is lower, power consumption increased rapidly, the oil pressure type showed lower power consumption. COP of two of these types decreased continuously as the internal temperature of a cold storage being reach setting temperature, and that of oil pressure type showed higher amount about 25%. As a setting temperature is lower, the number of refrigerator's operating times are less and operating time is longer, so power consumption is increased in the maintenance of a cold storage's internal temperature, power consumption of hydraulic type showed lower amount about 21~25% in two of these types.