• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.121-123
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• 2000

Changes in breathing pattern and apnea both can be !he result of sleep disorders. The focus of this paper is to develop methodologies to monitor the breathing pattern and to detect apnea. An accurate recording of the respiratory phase can be carried out with different methods. One of these methods is the use of a thermocouple, which reacts to the variation in air temperature, placed in the nose and mouth of the patient. The K-type thermocouple was used because it has high reliability, thermo-stability, and good corrosion resistance. And also, it has a considerable long time constant that gives a low cut-off frequency, well below the respiratory frequency and thereby causing a large phase difference. The result showed that timing of respiration was accurately obtained with the AD595, amplifier for K-type thermocouple.

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.726-739
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• 2003

A multi-dimensioanl model is being increasingly used to predict the thermo-flow field in the gas turbine combustor. This article addresses an integrated survey of modeling of the liquid spray formation and fuel distribution in gas turbine with high-shear nozzle/swirler assembly. The processes of concern include breakup of a liquid jet injected through a hole type orifice into air stream, spray-wall interaction and spray-film interaction, breakup of liquid sheet into ligaments and droplet,5, and secondary droplet breakup. Atomization of liquid through hole nozzle is described using a liquid blobs model and hybrid model of Kelvin-Helmholtz wave and Rayleigh-Taylor wave. The high-speed viscous liquid sheet atomization on the pre-filmer is modeled by a linear stability analysis. Spray-wall interaction model and liquid film model over the wall surface are also considered.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.873-876
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• 1999

Aspergillus sp. CX-l strain grown on microcrystalline cellulose resulted in the accumulation of high levels of cellulase and xylanase activities that were higher by two to four folds than those from the conventional commercial producer, Trichoderma reesei QM9414. Aspergillus sp. CX-1 demonstrated greater thermo stability and better catalytic characteristics of total cellulase activity (FPase) as compared to T. reesei and Aspergillus niger F-2039.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.73-77
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• 2005

In this paper, a new silicon nitride cantilever integrated with silicon heater and piezoelectric sensor has been firstly developed to improve the uniformity of the initial bending and the mechanical stability of the cantilever array for thermo-piezoelectric SPM(scanning probe microscopy) -based data storages. This nitride cantilever shows thickness uniformity less than $2\%$. Data bits of 40 nm in diameter were recorded on PMMA film. The sensitivity of the piezoelectric sensor was 0.615 fC/nm after poling the PZT layer. For high speed operation, 128${\times}$128 probe array was developed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.938-945
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• 2012

This research proposes FEM analysis for Tandem welding process used in wind tower and predicts optimal welding process to improve the stability of welded structures. Three dimensional elasto-plastic analyses are employed to evaluate thermo-mechanical behavior of residual stress and deformation during Tandem welding for different distance between two touches. To confirm the thermal distribution, Goldak's ellipse heat source model and the real size wind tower pipe model are utilized. Four different analyses are being performed, where in each case the distance between two electrode torches is being changed and residual stress and welding deformation are predicted. Depending on base material state, each case is divided into: Liquid (100mm), Austenite+Liquid (200mm), Austenite+Cementite (400mm), Pearlite+Cementite (800mm).

• Journal of the Korean Ceramic Society
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• v.40 no.10
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• pp.985-990
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• 2003

By heat treating coal tar pitch between 450∼500$^{\circ}C$, mesophase pitch could be obtained. Subsequently, this pitch was oxi-stabilized between 160∼240$^{\circ}C$ in air for the purpose of reducing swelling and distortion. The mechanism of stabilization was analysed using the thermo-gravity and FT-IR. To investigate the effect of oxi-stabilization, the shore hardness and bending stress were measured with carbonized green body which was made from oxi-stabilized coal tar pitch.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.196-203
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• 2012

Energy foundations and other thermo-active ground structure, energy wells, energy-slab, and pavement heating and cooling represent an innovative technology that contributes to environmental protection and provides substantial long-term cost savings and minimized maintenance. This paper focuses on earth-contact concrete elements that are already required for structural reasons, but which simultaneously work as heat exchangers. Pipes, energy slabs, filled with a heat carrier fluid are installed under conventional structural elements, forming the primary circuit of a geothermal energy system. The natural ground temperature is used as a heat source in winter and a heat sink in summer. The geothermal heat pump system with energy-slab represented very high heating and cooling performance due to the stability of EWT from energy slab. However, the performance of it seemed to be affected by the atmospheric air temperature.

• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.61-72
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• 2014

The aim of this study is to define the condition of optimal pre-treatment for preferable activated carbon fibers (ACFs), which are based on rayon fibers. This paper shows the ideal path of ACFs preparation process; implies that rayon fibers are pre-treated by various solvents with different times before the heating process. The pre-treated rayon fibers finally turned into desirable rayon fiber-based ACFs through optimal pre-treatment condition by heating processes. The thermal analysis method of pre-treated rayon fibers by thermo-gravimetry analyser (TGA) is an idealized tool, which analyzes the best thermal condition of pre-treatment process. Surface morphologies of resulting rayon fibers based ACFs were examined by scanning electron microscope(SEM). The results of TGA and SEM analyses show that the optimal pre-treatment condition for preparing ACFs was clearly defined, in terms of thermal stability and surface morphology.

• Journal of Radiation Industry
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• v.3 no.1
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• pp.31-37
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• 2009

This paper describes the preparation of manufacturing a new nanocomposite material, which involves adding a multi walled carbon nanotube (MWCNT) to improve thermal characteristics of poly (ethylene-co-vinyl acetate) (EVA). We irradiated the prepared nanocomposites with doses of 50 kGy, 100 kGy and 200 kGy at a dose rate of $5kGy\;hr^{-1}$ and examined their thermal stability, activation energy and crosslink level by using a thermogravimetric analyzer (TGA) and gel fraction experiments. TGA results indicated that the samples with a MWCNT had higher Derivative Thermo Gravimetry (DTG) 2nd peak temperatures than those without a MWCNT. And activation energy of the samples reduced as the absorption dose and the MWCNT content increased. Finally, the gel fraction increased rapidly up to 100 kGy as total absorption dose increased, and then the growth rate of all samples was slowly increased from 100 kGy.

• Journal of the Optical Society of Korea
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• v.7 no.2
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• pp.84-88
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• 2003

A new method for temperature compensation of fiber Bragg grating (FBG) using hi-metal is proposed and experimentally demonstrated. Bi-metal bends toward the metal of low temperature expansion coefficient as the temperature increases, and this property is utilized to cancel the thermo-optic effect of the fiber. The optimum thickness of the high coefficient metal was empirically found by the trial-and-error method. The temperature sensitivities were 8.1 pm/$^{\circ}C$ and -0.018 pm/$^{\circ}C$ for the uncompensated and compensated FBGs, respectively, which indicates a reduction to a mere 0.22 % of the original sensitivity. No appreciable change in the spectral shape was observed. The packaging technique described in this paper is simple and compact, and it can be used for FBGs in WDM and DWDM communication systems that have stringent requirements on the temperature stability of the components.