• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.303-308
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• 2001

Recently, concrete structures have become larger and higher and are demanding high performance concrete with lower heat to prevent thermal cracking, far greater workability, high strength and durability, Application of low heat portland(Type IV) cement for the high performance concrete is the best solution to satisfied those requirements. Here are explained the effect on the properties of high flowing concrete using low heat portland cement by material and mixing variations. Variables for sensitivity test were selected items like finess modulus of aggregates, particle size of limestone powder, unit water, superplasticizer, viscosity agent and concrete temperature. The results of this study were be applied to slurry wall of #215 and #216 of underground LNG tank in Inchon.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.426-430
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• 2005

The fiber-optic interferometer which is a powerful application for nondestructive measurement techniques has many advantages such as capability of making portable system, easy optical arrangement, low optical loss. In spite of these advantages, this system has an environmental sensitivity of thermal drifts and vibrations. Against environmental perturbations and nonlinear characteristic of phase modulator, the accurate and fast ${\pi}/2$ phase stepping has been achieved by using zero-crossing detection. CCD camera trigger signal is generated at the 4 zero-crossing points. Our System has achieved up to 100 Hz of image capture speed and 0.6 mrad of accuracy of phase stepping, accuracy.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.46-50
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• 2007

The nuclear power plant's turbine-generator system had been suffered form some problems, such as high shaft vibration, generator casing crack, stator coil water leakage, high $H_2$ gas consumption rate. Those kinds of problems were related to high vibration. So nuclear plant decided to replace generator in order to reduce rotor high vibration and high thermal sensitivity. A series of effort to reduce turbine-generator vibration was carried out as followings, first of all, replacement of generator, analysis of turbine-generator vibration, LP B rotor shop balancing, improvement of LP B/Gen coupling run-out, improvement of Generator basement and field balancing. Finally the nuclear turbine-generator's shaft vibration was reduced below $60{\mu}m$ from over $200{\mu}m$ which is very excellent vibration in nuclear turbine-generator in Korea.

• Computers and Concrete
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• v.19 no.1
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• pp.33-39
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• 2017

In this study, two types of aggregate were used for making self-compacting concrete. Standard cubic specimens were exposed to different temperatures. Seventy-two standard cylindrical specimens ($150{\times}300mm$) and Seventy-two cubic specimens (150 mm) were tested. Compressive strengths of the manufactured specimens at $23^{\circ}C$ were about 33 MPa to 40 MPa. The variable parameters among the self-compacting concrete specimens were of sand stone type. The specimens were exposed to 23, 100, 200, 400, 600, and $800^{\circ}C$ and their mechanical specifications were controlled. The heated specimens were subjected to the unconfined compression test with a quasi-static loading rate. The corresponding stress-strain curves and modulus of elasticity were compared. The results showed that, at higher temperatures, Scoria aggregate showed less sensitivity than ordinary aggregate. The concrete made with Scoria aggregate exhibited less strain. The heated self-compacting concrete had similar slopes before and after the peak. In fact, increasing heat produced gradual symmetrical stress-strain diagram span.

• Journal of the Korean Graphic Arts Communication Society
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• v.20 no.1
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• pp.91-101
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• 2002

An acid amplifier is defined as an acid-generating agent which is decomposed autocatalytically to produce new strongly acidic molecules in a non-liner manner, The addition of the acid amplifiers to conventional chemically amplified photoresists consisting of photoacid generators and acid-sensitive polymers result in the improvement of photosensitivity due to the amplified generation of catalytic acid molecules as a result of the decomposition of acid amplifiers. We synthesized and evaluated 1-hydroxy-4-tosyloxy cyclohexane(AA-1) and 1,4-ditosyloxy cyclohexane(Ah-2) as novel acid amplifiers. The acid amplifiers(AA-1, AA-2) showed reasonable thermal stability for resist processing temperature. As estimated by the sensitivity curve, tort-butyl methacrylate homopolymer(ptBMA) film doped with AA-1 or 2 exhibited much higher photosensitivity than ptBMA film without AA-1 or 2. And AA-1 showed higher effect than AA-2 on enhancing photosensitivity of ptBMA film.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.53-54
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• 2009

The preliminary quantitative analysis of proliferation resistance for the five nuclear fuel cycles demonstrated that the thermal MOX fuel cycle is most vulnerable to proliferation due to the presence of pure $PuO_2$ in the fuel cycle, while the once-through fuel cycle has the highest proliferation resistance. The innovative next generation fuel cycles such as Pyro-SFR and Wet-SFR were found to have similar levels of proliferation resistance to that of the DUPIC fuel cycle which is believed to have proliferation resistance strong enough for commercial deployment. The sensitivity analysis also demonstrated the effectiveness of the proposed methodology in applying to existing and/or newly developing nuclear fuel cycles so as to improve the proliferation resistance characteristic of the fuel cycle systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1993.11a
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• pp.109-111
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• 1993

We reported the fabrication and thermal cross-linking of the LB files on porous substrates. The monolayers of the polymers which polyion-conplexed with PAA at the air-water interface can be transferred onto solid substrates such as porous fluorocarbon membrane filter and quartz crystal microbalance. The properties of the monolayers and the LB films investigated by $\pi$-A isothem, FT-IR, and SEM will be discussed. In addition, it was attempted to investigate the reaction of polymer LB films in the organic gas surrounding by the use of LB technique.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.150-153
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• 1997

Langmuir-Blodgett(LB) technique is one of the ways of fabricating organic ultra-thin films. It is well known that It has the advantage to control the alignment and orientation of the molecules in the films. Metallo-phthalocyanines(MPcs) are sensitive to electron affinitive toxic gaseous molecules, such as NO$_2$, NO, SO$_2$. MPcs are thermal, optical, mechanical, chemical stable. Therefore, it is interesting to prepare phthalocyanine LB films containing copper as a chemical sensor for NO$_2$ and SO$_2$ gas and test their sensitivity to these toxic gases. In this study, thin films of Octa-dodecylosy copper-phthalocyanine were prepared by LB technique. $\pi$-A isotherm, transfer ratio, UV-VIS. spectroscopy of these films were investigated. Also current-voltage(I-V) characteristics of these was auto investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.101-104
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• 1998

A new planar-type micro gas sensor was designed and fabricated on silicon substrate and the operating characteristics of the sensor were investigated. The thin sensitive film of the sensor was fabricated by spin-coating of the SnO$_2$ sol solution which was synthesized by hydrothermal method. The spin-coating method for preparation of sensing layer was adopted to improve the long-term stability of the fabricated sensing film instead of physical methods such as rf sputtering and thermal evaporation. The fabricated microsensor showed a fairly good sensing performance for CO gas in air at 250$^{\circ}C$ The sensitivity(S=Ra/Rg) was shown to be about 5 to 2000ppm CO with heating power of 50mW.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.25.2-25.2
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• 2011

The tungsten oxide wire-like nanostructure is fabricated by deposition and thermal oxidation of tungsten metal on porous single wall carbon nanotubes (SWNTs). The morphology and crystalline quality of materials are investigated by SEM, TEM, XRD and Raman analysis. The results prove that $WO_3$ wire-like nanostructure fabricated on SWNTs show highly porous structures. Exposure of the sensors to NH3 gas in the temperature range of 150~300$^{\circ}C$ resulted in the highest sensitivity at $250^{\circ}C$ with quite rapid response and recovery time. Response time as a function of test concentrations and NH3 gas sensing mechanism is reported and discussed.