• The Journal of Korean Academy of Prosthodontics
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• v.33 no.1
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• pp.48-74
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• 1995

Since heat curing acrylic resins undergo unavoidable dimensional changes following polymerization, adaptation can be altered. Until recently, although numerous studies on the dimensional changes of denture base were based on a microscopic technic that measures the relative displacement of a limited reference points on the denture base, but there have been few studies on the distortions of resins using holographic interferometry. Purpose of this study was to determine and compare the dimensional changes and fringe patterns of 4 heat curing acrylic resins, and observe the distortions of acrylic resin denture base by temperature change with the aid of the holographic interferometry. Holographic interferograms were taken on the resin specimens and acrylic resin denture base with the 10mW He-Ne laser and double exposure method. Comparison and analysis of fringe pattern on the recorded object surface was performed. The following results were obtained. 1. The dimensional changes for the high impact resin Lucitone 199 were statistically the greatest of all resins, and the rapid heat curing resin Premium super 20 were the least. 2. The most polymerization shrinkage of all materials occured in initial period of measurements, at this time the difference of polymerization shrinkage properties between resins was founded. 3. The stress distribution of specimens was seen by various type of fringe pattern which had directionality. 4. The polymerization shrinkage of resins was greatly influenced by temperature change. 5. The partial deformations of resin denture base were observed in 70 C and 90 C water.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.2
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• pp.31-38
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• 2013

This research analyzed the acoustic emission signals collected from the pin loading tests and investigated the effect of hygrothermal exposure on the fracture behavior of the pin-jointed carbon fiber/epoxy composites. The composite specimens include: the Base specimen that has not been exposed to any environments, the RT specimen that has been immersed in room temperature water, and the HT specimen that has been immersed in high temperature water. According to the pin loading test, the RT and the HT specimens showed 2.2% and 13% decreases in the bearing strength compared to the Base specimen, respectively. The analysis of the acoustic emission signals showed different fracture acceleration points for three types of the specimens. Furthermore, for the RT and the HT specimens, the event from the matrix crack signals in the composites decreased. This shows the effect of the hygrothermal conditions on the acoustic emission signals. Additionally, upon investigating the fracture behaviors of the pin-jointed composites, the exposing specimens to hygrothermal environments decreases the interfacial characteristics of the composites.

• Journal of Biosystems Engineering
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• v.10 no.1
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• pp.76-82
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• 1985

To investigate the influence of annealing heat treatment on the mechanical properties at the various weld zone, an experimental study was performed for the structural alloy steel. The results obtained from the experimental works are as follows: 1. Hardness and tensile strength showed the highest value at the heat affected zone, which was 5mm apart from bond zone. With increasing of annealing temperature, hardness and tensile strength were decreased at every weld zone, and bound in heat affected zone was increased. 2. Impact strength was the highest at the filler metal, and increased with increment of annealing temperature at filler metal and base metal. However, both at bond and heat affected zones, impact strength was increased from $700^{\circ}C$ of annealing temperature, and was decreased again over $900^{\circ}C$. 3. Mutual relationship between the mechanical properties at filler and base metals showed a similar linearty to that the common structural steel did. However, it varied unsteadly both at bond and heat affected zones. 4. It may be concluded that proper annealing temperature is $700^{\circ}C$ from the viewpoint of hardness, tensile and impact strength.

• Korean Journal of Materials Research
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• v.12 no.8
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• pp.608-612
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• 2002

The sliding wear behavior of an iron-base NOREM 02 hardfacing alloy was investigated in the temperature range of $25～250^{\circ}C$ under a contact stress of 103MPa (15ksi). With increasing temperature, the wear loss of Norem 02 in water increased slightly up to $180^{\circ}C$ at which Norem 02 showed the wear loss of 2.1mg. The wear resistance of Norem 02 resulted from the surface hardening due to the strain-induced phase transformation from austenite to $\alpha$'martensite during sliding wear. The wear loss of Norem 02 was smaller in water compared to air at same temperature because the water could be served as a sort of lubricant. The wear mode of NOREM 02 changed abruptly to severe adhesive wear at $190^{\circ}C$ and galling occurred above $200^{\circ}C$. It was caused that the strain- induced phase transformation took place below $180^{\circ}C$ while not above $190^{\circ}C$. Therefore, Norem 02 was considered to be inadequate at high temperature service area.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.264-269
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• 2007

The microchannel waterblock has a good capability in the cooling of electronic devices. The object of this paper is to study on thermal performance of microchannel water block for cooling of CPU in desktop. The effects of header shape, liquid flow rate, and inlet temperature on the thermal performances of microchannel waterblock are investigated experimentally. Three types of waterblock with different header shape are manufactured from the micro milling and brazing processing. The experiments are conducted using water, over a liquid flow rate ranging from 0.7 to 2.0 LPM and inlet temperature ranging from 20 to $35^{\circ}C$. Waterblocks are attached both horizontally and vertically on the test section to anticipate a performance of waterblock under the actual state in computer. The base temperature and thermal resistance decrease with increasing of liquid flow rate. It was found that the sample #1 was appropriate for the prototype of liquid cooling system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.9
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• pp.1784-1789
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• 2009

This paper describes the measurement technology of the dissolved hydrogen gas due to partial discharge in oil using gas sensor. For higher resolution and less error in measurement of the dissolved hydrogen gas in oil, the sensor outputs with ambient temperature which affect the sensor output characteristics should be considered. The sensor output trends with ambient temperature and the properties of the dissolved hydrogen gas in oil with partial discharge characteristic were analyzed through the test results. It was indicated that the sensor peak and the base voltage with measuring time were affected by ambient temperature and the measurement errors of the sensor output by temperature were reduced by using the difference between the peak and the base voltage rather than just the peak voltage. In addition, the hydrogen gas sensor outputs were increased with the increase of partial discharge energy.

• Journal of Environmental Science International
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• v.31 no.7
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• pp.617-635
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• 2022

The effect of coupled data assimilation (DA) on the meteorological prediction in the west coastal region of Korea was evaluated using a coupled atmosphere-ocean model (e.g., COAWST) in the spring (March 17-26) of 2019. We performed two sets of simulation experiments: (1) with the coupled DA (i.e., COAWST_DA) and (2) without the coupled DA (i.e., COAWST_BASE). Overall, compared with the COAWST_BASE simulation, the COAWST_DA simulation showed good agreement in the spatial and temporal variations of meteorological variables (sea surface temperature, air temperature, wind speed, and relative humidity) with those of the observations. In particular, the effect of the coupled DA on wind speed was greatly improved. This might be primarily due to the prediction improvement of the sea surface temperature resulting from the coupled DA in the study area. In addition, the improvement of meteorological prediction in COAWST_DA simulation was also confirmed by the comparative analysis between SST and other meteorological variables (sea surface wind speed and pressure variation).

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.545-550
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• 2004

KSTAR cryostat is a 8.8 m diameter vacuum vessel that provides the necessary thermal barrier between the ambient temperature test cell and the supercritical helium cooled superconducting magnet providing the base pressure of 1 ${\times}$ $10^{-3}Pa$. The cryostat is a single walled vessel consisting of central cylindrical section and two end closures, a flat base structure with external reinforcements and a dome-shaped lid structure. The base structure has 8 equally spaced support legs anchored on the concrete base. The cryostat vessel design was executed to satisfy the performance and operation requirements. The major loads considered in the structural analysis were vacuum pressure, dead weight, electromagnetic load driven by plasma disruption, and seismic load. Based on the fabrication and inspection procedures for the vessel, cryostat vessel was fabricated and inspected. It was confirmed that the inspection results were acceptable.

• International Journal of Automotive Technology
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• v.8 no.6
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• pp.705-711
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• 2007

A rectangular fin with a fluid in the inside wall is analyzed and optimized using a two-dimensional analytical method. The influence of the fluid convection characteristic number in the inside wall and the fin base thickness on the fin base temperature is listed. For the fixed fin volumes, the maximum heat loss and the corresponding optimum fin effectiveness and dimensions as a function of the fin base thickness, convection characteristic numbers ratio, convection characteristic number over the fin, fluid convection characteristic number in the inside wall, and the fin volume are represented. One of the results shows that both the optimum heat loss and the corresponding fin effectiveness increase as the fin base thickness decreases.

• Journal of Mechanical Science and Technology
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• v.15 no.10
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• pp.1423-1433
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• 2001

A flow modeling method has been developed to analyze the flow in the annular base (rear- facing surface) of a circular engine nacelle flying at subsonic speed but with a supersonic exhaust jet. Real values of exhaust gas properties and temperature at an altitude of 30, 000 feet are employed. Potential flows of the air and gas streams are computed for the flow past a separated wake. Then a viscous jet mixing is superimposed on this inviscid solution. Conserva- tion of mass, momentum and energy for the wake flow field is achieved by multiple iterations with modest computer requirements.