• Journal of Energy Engineering
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• v.23 no.2
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• pp.175-182
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• 2014

The use of solar energy among renewable energy tends to increase because of 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 make the system of performance test for solar collector and to investigate thermal efficiency for solar collector with thermosyphon tube-type. As a result, in case of indoors measurement using halogen lamp, thermal efficiency for solar collector with thermosyphon tube-type was increased about 15~22% after 120 minutes compared with that of solar collector with double evacuated tube-type. In addition, in case of outdoors measurement, thermal efficiency of thermosyphon tube-type was showed maximum about 46% higher than double evacuated tube-type.

• Analytical Science and Technology
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• v.26 no.3
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• pp.190-198
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• 2013

Ambers have been used mostly as beads, jewelry and ornaments from ancient times and excavated as a buried artifact. When excavated, they are severely weathered to be cracked, exfoliated and disintegrated. Monitoring of changes in composition of amber according to weathering is very important for diagnosing the condition of amber and applying conservation materials and techniques. In this study, we tried to find the components of amber by analyzing amber with pyrolysis/GC/MS. The changes in the composition of pyrolzates after artificial ageing for 60 days under heat and oxygen were also observed. Abietic acid was detected as a main component of fresh amber and monoterpene, alkene, aromatic hydrocarbon were detected as major pyrolyzates. Changes with artificial ageing was estimated by comparing the peak area ratio of 23 components, and it was found that abietic acid abruptly decreased in the presence of heat and oxygen together, revealing that oxygen is a key factor to the deterioration of amber. It was also tried to understand the weathered surface of original amber gemstone based on the result of this ageing experiment.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.36-43
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• 2018

A great deal of difficulty is encountered in the thermo-mechanical analyses of nozzle assemblies for solid propellant rocket motors. The main issue in this paper is the modeling of the boundary conditions and the connections between the various components-gaps, relative movements of the components, contacts, friction, etc. This paper evaluates the complex phenomena of nozzle assemblies during burning time with co-simulations that include fluid, thermal surface reaction/ablation, and structural analysis. The validity of this approach is verified via comparison of analysis results with measured strains.

• Journal of Broadcast Engineering
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• v.27 no.6
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• pp.872-884
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• 2022

With the development of the IoT industry, different types of time series data are being generated in various industries, and it is evolving into research that reproduces and utilizes it through re-integration. In addition, due to data processing speed and issues of the utilization system in the actual industry, there is a growing tendency to compress the size of data when using time series data and integrate it. However, since the guidelines for integrating time series data are not clear and each characteristic such as data description time interval and time section is different, it is difficult to use it after batch integration. In this paper, two integration methods are proposed based on the integration criteria setting method and the problems that arise during integration of time series data. Based on this, integration framework of a heterogeneous time series data was constructed that is considered the characteristics of time series data, and it was confirmed that different heterogeneous time series data compressed can be used for integration and various machine learning.

• Applied Chemistry for Engineering
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• v.27 no.5
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• pp.543-545
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• 2016

Four different hydroxyapatites (HAP) were prepared by a solvothermal method under different pHs and solvent species. The synthesized hydroxyapatites were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Four HAPs exhibited similar XRD patterns regardless of synthetic conditions. However, the morphology of hydroxyapatites was dependent of pH and solvent species under synthetic condition. The HAP prepared in pH 12 showed an elongated shape along the [001] direction compared to that prepared in pH 8. Also, the morphology of the HAPs synthesized in the presence of methanol and ethanol exhibited the more elongated hexagonal rod shape along the [001] direction with the high aspect ratio.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.4
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• pp.9-16
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• 2002

Content based Image retrieval methods in the multimedia information retrievals use primary visual features such as color, texture and shape. Color and texture generally are used as features of the image retrieval systems. But these systems may produce errors in similar image retrieval because two images with different shapes can represent very different contents. Therefore, the use of shape describing features is essential in an efficient content based image retrieval system. In this paper, after the global features filtering process by the boundary of objects, we have created a better shape similarity image retrieval system by a histogram of shape information.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2381-2391
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• 2013

In general, ground's thermal properties, types of heat exchanger, operational method, thermal interference between piles can be considered as key factors which affect the thermal performance of energy pile. This study focused on the effect of these factors on the performance by a numerical model reflecting a real ground condition. Depending on the degree of saturation of ground, pile's heat transfer rate showed a maximum difference of three times, and the thermal resistance of pile made a maximum difference of 8.7%. As for the type of heat exchanger effects on thermal performance, thermal efficiency of 3U type energy pile had a higher value than those of W and U types. The periodic operation (8 hours operation, 16 hours pause) can preserve about 20% of heat efficiency compared to continuous operation, and hence it has an advantage of preventing the thermal accumulation phenomenon. Thermal interference effect in group piles may vary depending on the ground condition because the extent decreases as the ground condition varies from saturated to dry. The optimal separation distance that maintains the decreasing rate of heat efficiency less than 1% was suggested as 3.2D in U type, 3.6D in W type, and 3.7D in 3U type in a general ground condition.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.8
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• pp.39-48
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• 2016

In this paper, we propose thermal resistance compact model of FinFET structure that has hexagon shaped source/drain. The heating effect and thermal properties were increased by reduced size of the device, and thermal resistance is an important factor to analyze the effect and the properties. The heat source and each contact that is moved heat out were set up in transistor, and domain is divided by the heat source and the four parts of contacts : source, drain, gate, substrate. Each contact thermal resistance model is subdivided as a easily interpretable structure by analyzing the temperature and heat flow of the TCAD simulation results. The domains are modeled based on an integration or conformal mapping method through the structure parameters according to its structure. First modeled by analyzing the thermal resistance to a single fin, and applying the change in the parameter of the channel increases to improve the accuracy of the thermal resistance model of the multi-fin/ finger. The proposed thermal resistance model was compared to the thermal resistance by analyzing results of the 3D Technology CAD simulations, and the proposed total thermal resistance model has an error of 3 % less in single and multi-finl. The proposed thermal resistance model can predict the thermal resistance due to the increase of the fin / finger, and the circuit characteristics can be improved by calculating the self-heating effect and thermal characterization.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.4
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• pp.479-485
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• 2014

Purpose: This study relates to the development of the prism dot-sight combined with the thermal imaging camera. Methods: We have placed a reflector designed to the doublet type in the front of a BS (beam splitting) prism, have placed an OLED panel and a dot reticle generator to the top and bottom of the reflecting surface of the BS prism, and have placed a detachable magnifier between the BS prism and the observer by which the observer can see the magnified image of the OLED panel. By doing this, we were able to configure the new type prism dot-sight combined with the thermal imaging camera. Results: By placing the removable magnifier designed with a new type between the BS prism and the observer, we could design the new type prism dot-sight which performs the role of the dot sight by removing the magnifier during the day-time, and performs the role of the night scope during the night-time by which we can observe the enlarged image of the thermal imaging camera through the BS prism by attaching the removable magnifier. Conclusions: In this study, we have developed the prism dot-sight combined with the thermal imaging camera which is able to play the role of the day or night scope selectively, by disposing the designed magnifier characterized by the focal length of 44 mm, the viewing angle of ${\pm}7.0^{\circ}$, and the MTF value of 0.5 or more at the criterion of 50 lp/mm and the 0.7 field between the BS prism and the observer. By doing so, we could design and fabricate the new type prism dot-sight combined with the thermal imaging camera which can further increase the rapidity of firing and provide more convenience in the mounting of a firearm than the detachable combination of an existing dot sight and an existing night scope.

• 한국문화재보존과학회:학술대회논문집
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• 2003.09a
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• pp.89-93
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• 2003