• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.478-481
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• 1995

This paper presents the system demonstrator for an optical fiber sensor system developed as a technological evaluator suitable for generic sensric sensing applications. The new type of fiber-optic sensor employed a diaphragm displacement transforms pressure into optical intensity. Form this sensing technique, we can know the variation of source intensity, the loss of a optical fiber, and the reflectivity of the diaphragm surface. Experimental results are applied to the low-pressure transducer suitable for measuring miniature pressure.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.91.3-91
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• 2001

A sensor fusion scheme for mobile robot environment recognition that incorporates range data and contour data is proposed. Ultrasonic sensor provides coarse spatial description but guarantees open space with no obstacle within sonic cone with relatively high belief. Laser structured light system provides detailed contour description of environment but prone to light noise and is easily affected by surface reflectivity. Overall fusion process is composed of two stages: Noise elimination and belief updates. Dempster Shafer´s evidential reasoning is applied at each stage. Open space estimation from sonar range measurements brings elimination of noisy lines from laser sensor. Comparing actual sonar data to the simulated sonar data enables ...

• Fibers and Polymers
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• v.2 no.4
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• pp.171-177
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• 2001

Change of tensile properties, electrical conductivity and microwave shielding of electrochemically synthesized polypyrrole films with time are presented. Highly doped films had good electrical stability, retaining high microwave reflectivity throughout the aging period. Lightly doped films were less stable and partially reflective and absorptive of microwaves. FT-IR spectral observations revealed a progressive increase in intensity of an unsaturated conjugated carbonyl peak, which was not observed in the highly doped films, suggesting that the concentration of the dopant had an influence on mechanism of degradation of conductivity.

• Proceedings of the Optical Society of Korea Conference
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• 2007.07a
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• pp.187-188
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• 2007

Four kinds of mirror substrates with same surface roughness were fabricated. On those substrates, a dielectric multi-layer coating with high reflectivity was deposited by ion beam sputtering technique. Most of the fused silica mirrors showed lower scattering than the ZERODUR mirrors one, which deposited on substrates similar in surface roughness. The ZERODUR mirrors scattering strongly depend on the micro-structure of $Ta_2O_5/SiO_2$ thin films wear deposited on ZERODUR substrates.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.982-985
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• 2007

The authors report methods of fabrication singlelayer color cholesteric liquid crystal displays (CLCDs). A single-layer CLCD has been prepared from a polymerstabilized cholesteric liquid crystal. The unique feature of the polymer stabilization is in that the electrically switched colors preserve high reflectivity. A bistable single-layer CLCD has been prepared by the formation of polymer barrier walls and light-tuned cholesteric pitches to reflect blue, green and red color sub-pixels.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.5
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• pp.567-574
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• 2007

Aluminum and aluminum alloys have high rate of lightness, recycling property and excellent specific strength. Fields using them have been widening because they ould satisfy both energy reduction and high efficiency in manufactures production. But they have many problems on welding due to high thermal conductivity and reflectivity, so the study to solve these problems ate proceeding actively around the world. This study was purposed to improve weldability and spread application range for aluminium alloys by using the unique property of aluminium which absorb high energy around $800{\mu}m$ wavelength and the higher temperature, the mote absorbtion of laser beam on preheating by multi-wavelength laser beam(pulsed Nd:YAG laser + diode laser with $808{\mu}m$ wavelength). The favorable mechanical properties were acquired by the test results of strength, hardness and leak of weld metal which had reduced its defect like crack and so on.

• Atmosphere
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• v.26 no.4
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• pp.509-522
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• 2016

Heavy snowfall events have occurred frequently in the Yeongdong region but understanding of these events have trouble in lack of snowfall observation in this region because it is composed of complex topography like the "Taebaek mountains" and the "East sea". These problems can be solved by quantitative precipitation estimation technique using remote sensing such as radar, satellite, etc. Two radars which are able to cover over Yeondong region were installed at Gangneung (GNG) and Gwangdeoksan (GDK). This study uses radar and water equivalent of snow cover to investigate the characteristics of radar echoes and the $Z_e-R$ relations associated with the 10 Yeongdong heavy snowfall events during the last 5 years (2010~2014). It was found that the heights which the probability of detection (POD) of snow detection by GNG radar is more than 80% are 3,000 m and 1,500 m in convective cloud and stratiform cloud, respectively. The vertical gradient of radar reflectivity is less decreased in convective cloud than stratiform cloud. However, POD by GDK radar are lower than 80% at all layers because the majority of Yeondong observational stations are more than 100 km away from GDK radar site. Furthermore, we examined $Z_e-R$ relation from the 10 events using GNG radar and compared the "a" and "b" obtained from these examinations at Sokcho (SC) and Daegwallyeong (DG). These "a" and "b" are estimated from radar echo at 500 m (SC) and 1,500 m (DG). The values of "a" differ in their stations such as SC and DG are 30~116 and 6~39, respectively. But "b" is 0.4~1.7 irrespective of stations. Moreover, the value of "a" increased with surface air temperature. Therefore, quantitative precipitation estimation in heavy snowfall events by radar echo using fixed "a" and "b" is difficult because these values changed according to those precipitation characteristics.

• Journal of the Korean Society of Radiology
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• v.3 no.4
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• pp.23-28
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• 2009

Monochromatic X-ray can make a medical image of high contrast under a low radiation dose and can be easily generated by combining an X-ray tube and a multilayer mirror. A W/C multilayer mirror was optimally designed for a characteristic X-ray generated from a X-ray tube with Mo target. The d-spacing and the thickness ratio in design parameters were determined under the maximum-reflectivity condition. Tolerances for deposition and alignment of the W/C multilayer mirror were calculated. Within a deposition tolerance of 0.2nm and a alignment tolerance of ${\pm}0.01^{\circ}$, 85% of the theoretical peak reflectivity could be achieved. A multilayer mirror can be widely used for making medical images because of generating high fluence monochromatic X-ray.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.69-72
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• 2007

Cellulose is a beneficial material that has low cost, lightweight, high compatibility and biodegradability. Recently electroactive paper (EAPap) on cellulose base was discovered as a smart material and actuator through ion migration and piezoelectric effect. Furthermore cellulose has a potentiality to apply the display material, because of its high reflectivity, flexibility and high transmittance. The various shapes and height patterns of the Cellulose acetate (CA) solution, such as circle and honeycomb patterns, were fabricated and observed by field emission scanning electron microscope (FESEM, S4300 Hitachi). The resulting pattern showed uniform size in the large area without defect. After stretching the CA film with saponification process in the sodium methoxide in methanol solution, Most of the compositions become one directional ordered nanofibers below 50nm.

• Applied Science and Convergence Technology
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• v.24 no.2
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• pp.41-46
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• 2015

Transparent conductive oxides (TCOs) are essential material in optoelectronics such as solar cells, touch screens and light emitting diodes. Particularly TCOs are attractive material for infrared cut off film due to their high transparency in the visible wavelength range and high infrared reflectivity. Among the TCO, Indium tin oxide has been widely used because of the high electrical conductivity and transparency in the visible wavelength region. But ITO has several limitations; expensive and low environmental stability. On the other hands, fluorine doped tin oxide (FTO) is well known for low cost, weather ability and stable in acidic and hydrogen. In this study, two different magnetron sputtering techniques with RF and DC modes at room temperature deposition of FTO thin film was conducted. The change of oxygen content is influence on the topography, transmittance and refractive index.