• Journal of the Korean Ceramic Society
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• v.44 no.8
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• pp.430-436
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• 2007

Rheological properties of cement paste containing ultrafine blastfurnace slag (UBS, $9600cm^2/g$) were investigated by mini-slump test, pH meter, conduction calorimeter and coaxial cylinder viscometer. In order to improve rheological properties of the cement paste, granulated blastfurnace slag (GBS, $3500cm^2/g$) and polycarboxylate type superplasticizer (PC) were also used in this experiment. The fluidity of cement paste containing UBS was decreased. The yield stress and plastic viscosity of cement paste was increased with increasing UBS. But the rheological properties were improved when GBS and PC were added to UBS blended cement paste. In the relationship between the yield stress and the plastic viscosity or the mini-slump value, the yield stress of the cement paste was proportional to the plastic viscosity of it. However the cement paste mini-slump value was in inverse proportional to the yield stress.

• Journal of the Korean Ceramic Society
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• v.54 no.4
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• pp.331-339
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• 2017

Porous alumina-based ceramics are of special interest due to their outstanding mechanical properties and their thermal and chemical stability. Nevertheless, the high electrical resistance of alumina-based ceramics, due to the generation of static electricity, leads to difficulty in applying a vacuum chuck in the semi-conductor process. Therefore, development of alumina-based ceramics for applications with vacuum chucks aims to have primary properties of low electrical resistance and high air permeability. In this study, we tailored the electrical resistance of porous alumina-based ceramics by adjusting the amount of $MnO_2$ (with $TiO_2$ fixed at an amount of 2 wt%) and by using coarse alumina powder for high air permeability. The characteristics of the specimens were studied using scanning electron microscopy, mercury porosimeter, capillary flow porosimetry, universal testing machine, X-ray diffraction and high-resistance meter.

• Journal of IKEEE
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• v.13 no.3
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• pp.95-102
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• 2009

TETRA(TErrestrial Trunked RAdio) is wireless communication system generally adopted to public network and backbone network, as the technology of Trunked Radio System specified by ETSI(European Telecommunications Standards Institute) and currently adopted to the Electric Power IT Backbone Network in Korea. DLMS(Device Language Message Specification) is used in order to meter an electric measuring instrument value. In this paper, DLMS Server and Client simulator are used based on Window operating system. The multi-functional gateway, which transforms the communications based on RS-232C between DLMS Server Simulator and Client Simulator to the one based on TETRA PEI(Peripheral Equipment Interface), is developed such that DLMS SCADA(Supervisory Control And Data Acquisition) system is constructed based on TETRA.

• Journal of ILASS-Korea
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• v.9 no.3
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• pp.22-28
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• 2004

This study is concerned about the characteristics of ultrasonic-energy-added W/O type emulsified fuel. The distilled water was mixed with diesel oil by using ultrasonic energy fuel feeding system and then the SMD of sprayed droplets was measured to find out atomization characteristics of emulsified fuel by using the Malvern 2600 system. The capacitance value was measured to verify stability of the same specimen by using the digital LCR meter, EDC1630 additionally. The main results are as follows; 1) The more measuring distance increases between one hole nozzle tip and analyser bearm, the more SMD increases. 2) The more water content increases, the more capacitance value increases depending on the time. Main Parameters of the study are the amount of water content $0{\sim}30%$ by 5% in emulsified fuel, and the measurement distance, $20{\sim}140mm$ by 10mm or 20mm between nozzle tip and analyser beam.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.270-272
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• 1997

In order to a study on the electrical properties of silicone gel due to the curing condition, the volume resistivity test is researched. For experiment, we have made up several samples of different curing temperature and time such as 1[H], 2[H] at 125[$^{\circ}C$], 150[$^{\circ}C$], 160[$^{\circ}C$], 170[$^{\circ}C$], 180[$^{\circ}C$]. A measurement of volume resistivity using the VMG-1000 highmegohm meter is recorded after 10 minutes when the each voltage, and DC 500[V] and 1000[V] is applied. A coaxial cylindrical liquid electrode to measure volume resistivity of specimen is used, and its geometric capacitance is 2[pF]. As a result of the experiment, the electrical properties of specimen cured at 170[$^{\circ}C$] for 2[H] is superior.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.3
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• pp.1-7
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• 2006

By the reason of increased demand of high productivity, the researches on manufacturing process and equipments for reducing cycle time have been made in many directions of a machine tool industries. Especially high productivity is very important to machining center with high-speed spindle. This paper proposed method of reducing T-T(tool to tool) time which results in shorter unclamping time. T-T time varies as factors such as a hydraulic system, a drawbar mass, a flow meter, a disc spring, piston and pipe diameters. In this paper We could find design factors has much influence on decreasing the unclamping time using DOE(Design of Experiment) and optimized the level of the factors using AMESim $4.0^{(R)}$ and visualNastran $4D^{(R)}$ Finally, we have verified improved result of the optimized factors with initial design.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.215-216
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• 2012

Emissions of CO₂ occur during the production of cement manufacturing process. During the production of clinker, limestone is mainly calcium carbonate, is heated to produce lime and CO₂ as a by-product. It has a major problem, CO₂ uptake is not considered in concrete carbonation, just focus in CO₂ emission. This study is to develop a simulation model for CO₂ uptakes in concrete structures based on carbonation reduction coefficient considering finishing materials. CO₂ uptakes unit of concrete cubic meter is calculated by CO₂ emissions unit of concrete materials and usage of concrete materials in mix proportion. From the simulation result, CO₂ uptake ratios is 2.04 percent in carbonation models of concrete structure during 40 years.

• 한국정보디스플레이학회:학술대회논문집
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• 2002.08a
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• pp.419-422
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• 2002

We have studied dielectric properties in the smectic phases of 4-(6-ethoxy-1-trifluoromethyl-hexyloxycarbonyl)-phenyl-4-Nonyloxybiphenyl-4-carboxylat ( TFMEOHPNBC ) having fluorine attached to one of its benzene rings. Homogeneous and homeotropic 1.5 and 5${\mu}m$ thick test cells were prepared to analyze molecular dynamic property. We measured capacitance as a function of temperature in the frequency range between 20 Hz and 100 kHz by using HP4284A LCR meter. We observed that the homogeneous cell has high dielectric constant causing dipole moment in smectic $C^{\ast}$ phase, but we can see the dipole moments are canceled out in antiferroelectric phase. It is found that there are two kind of the relaxation director fluctuation below 100 kHz. The first is ionic or space charge contribution below 10 Hz, and the second is Goldstone mode near 1-2 kHz. We will discuss molecular dynamics in smectic phase from extra information such as x-ray and electrooptic data.

• Journal of Sensor Science and Technology
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• v.16 no.4
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• pp.286-293
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• 2007

For safe walking of the people who are blind, walking assistance robot which can detecting and avoiding the obstacle was investigated. The implemented prototype walking assistance robot consists of a obstacle detecting module, a user interface using acoustic signal and a driving module. The obstacle detecting module uses 6 ultrasonic sensors those located at the front part of the robot can perceive the obstacle which is in 3 meter distances and $180^{\circ}$ degrees. It calculates the distance and degree from the obstacle using TOF (time of flight) method and decides the 3-dimensional location of the obstacle. The obstacle information is delivered to the user using acoustic alarm and guide sound. The robot is designed to avoid by itself when the obstacle is detecting and the user only follows it to safe walking. After the designed robot was implemented, driving and obstacle detecting experiments were carried out. The result showed that the designed walking assistance robot will help the people who are blind to walk around safe.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.548-551
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• 2007

Among components of digital topographic maps used officially in Korea, only contours have 3D values except buildings and trees that are demanded in landscape planning. This study presented a series of processes for 3Dreconstructing landscape features such as terrain, buildings and standing trees using LiDAR (Light Detection And Ranging) data and aerial digital photo graphs. The 3D reconstructing processes contain 1) building terrain model, 2) delineating outline of landscape features, 3) extracting height values, and 4) shaping and coloring landscape features using aerial photograph and 3-D virtual data base. LiDAR data and aerial photograph was taken in November 2006 for $50km^{2}$ area in Sorak National Park located in eastern part of Korea. The average scanning density of LiDAR pulse was 1.32 points per square meter, and the aerial photograph with RGB bands has $0.35m{\times}0.35m$ spatial resolution. Using reconstructed 3D landscape features, visibility with the growing trees with time and at different viewpoints was analyzed. Visible area from viewpoint could be effectively estimated considering 3D information of landscape features. This process could be applied for landscape planning like building scale with the consideration of surrounding landscape features.