• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.6
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• pp.53-58
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• 2004

A novel UV sensor was manufactured and characterized using evanescent field coupling between photochromic dye dispersed polymer waveguide and side polished fiber. The spiroxazine (photochromic dye) dispersed polymer was used as planar waveguides. The resonant wavelength was shifted owing to refractive index variation of planar waveguide on exposed UV because of its photo-functional properties. The sensitivities are $1.21{\mu}W/mw$ and $2.75{\mu}W/mw$ when UV intensities increased after exposure times were fixed at 3 seconds and 5 seconds, respectively. Output optical power according to UV intensity increases and saturation time decreases as the intensity of UV radiations increases.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.63-67
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• 2015

White light-emitting diode (WLED) is growing interest in using both illumination and communications. This paper reports visible light communication (VLC) composed of a super bright white light-emitting diode, low cost commercial photo-diode and a Fresnel lens. LED driver is consisted of the power MOSFET and MOSFET driver that switches the LED on and off. The modulation bandwidth of the LED used was determined to be 8 MHz. However, it was possible to communicate up to 1 Mbps under illumination of 500 lx because of the weak signal power and a low spectral sensitivity of the SHF213 as a PIN photodiode. In order to enhance the system bandwidth, the LED light was focused on the PIN photodiode by use of the Fresnel lens. As a result of that, visible light link was operated up to modulation bandwidth of the LED. The signal to noise ratio can be improved by 40 dB using an optical concentration at the receiver.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1555-1558
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• 2002

This paper presents deposition and characterizations of microcrystalline silicon(${\mu}c$-Si:H) films prepared by hot wire chemical vapor deposition at substrate temperature below $300^{\circ}C$. The $SiH_4$ Concentration$[F(SiH_4)/F(SiH_4)+F(H_2)]$ is critical parameter for the formation of Si films with microcrystalline phase. At 6% of silane concentration, deposited intrinsic ${\mu}c$-Si:H films shows sufficiently low dark conductivity and high photo sensitivity for solar cell applications. P-type ${\mu}c$-S:H films deposited by Hot-Wire CVD also shows good electrical properties by varying the rate of $B_2H_6$ to $SiH_4$ gas. The solar cells with structure of Al/nip ${\mu}c$-Si:H/TCO/glass was fabricated with sing1e chamber Hot-Wire CVD. About 3% solar efficiency was obtained and applicability of HWCVD for thin film solar cells was proven in this research.

• Journal of Sensor Science and Technology
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• v.12 no.4
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• pp.149-155
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• 2003

A PMOSFET photodetector for highly-sensitive active pixel sensor(APS) is presented. This sensor uses 5V power supply and has been designed and fabricated using I-poly and 2-metal $1.5{\mu}m$ CMOS technology. The feature of a PMOSFET photodetector is that the polysilicon gate of the PMOSFET was connected to n-well, in order to increase the photo sensitivity. The designed MOS photodetector has similar $I_{DS}-V_{DS}$ characteristics with a standard MOSFET. One dimensional image sensor with 16 pixels based on the PMOSFET photodetector has also been designed and fabricated. Unit pixel of the designed sensor consists of a PMOSFET photodetector and 4 NMOSFETs. Unit pixel area is $86{\mu}m{\times}90.5{\mu}m$ and its fill factor is about 12%.

• Journal of Sensor Science and Technology
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• v.4 no.3
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• pp.9-14
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• 1995

For the development of liquid density measuring sensor using the natural frequency of a pipe, its principle and construction method were described. The stainless steel pipe, which has length of 32 cm, inside diameter of 2.3 cm and outside diameter of 2.5 cm, was used for the sensor. The exciting coil and the photo sensor were used to excite and to pick-up it, and the feedback circuit was designed to continue its vibrating. The natural frequency was consistent with the result of the spectrum analysis. It had a linearity of 0.0027 % and a sensitivity of 0.032 % in liquid density range from $0.8\;g/cm^{3}$ to $1.4\;g/cm^{3}$ and its frequency variation ratio was 0.024 $%/^{\circ}C$ in temperature range from $10^{\circ}C$ to $35^{\circ}C$.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.1
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• pp.33-38
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• 2016

The turbocharger is an essential component to realize the engine down-sizing. The moment of inertia of turbocharger rotor is an important parameter with respect to acceleration performance of the vehicle. It can be calculated from the CAD software based the geometry data and the material properties. But the accurate value of the inertia of turbocharger rotor must be measured through the experimental method. In this study, the measurement of moment of inertia of turbocharger rotor for 2.0 L spark-ignition engine was carried out. First, an experimental equipment using a trifilar method was designed and fabricated. Some optical devices, that is, photo sensor, counter, convex lens, etc, were used to increase the accuracy of the measurement. Second, error sensitivity for the equipment was analyzed. The error of period time and the radius can give big affects to the accuracy of the moment of inertia. When the amount of error of these two were each 1.0 %, maximum error of the moment of inertia was under 3.0 %. Third, the calibration for the equipment was performed using a calibration rotor which has similar shape to turbine rotor but simple. Calculated value from CAD software and measured one for the calibration rotor were compared. The total error of the equipment and the measurement is about 1.3 %. This result shows that the equipment can give the good result with resonable accuracy. Finally the moment of inertia of the turbine rotor and compressor wheel were measured. The coefficient of variations, the ratio of standard deviation to mean value, were reasonably small at 0.57 % and 0.73 % respectively. Therefore this equipment is suitable for the measurement of the moment of inertia of the turbine rotor and compressor wheel.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.400-400
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• 2010

우리는 기본 진공 $10^{-11}\;Torr$의 UHV surface magneto-optical Kerr effect (SMOKE) 시스템을 quarter-wave plate를 사용하였던 기존의 방식에서 PEM (photo elastic modulator)를 사용하는 방식으로 장비의 기능을 향상시켰다. 기존 quarter-wave plate를 사용하는 방식의 경우 Kerr signal을 구하기 위해 편광자와 검광자를 수직으로 두어 광량을 0으로 만들어야 한다. 그러나 금속의 경우 대부분 가시광선 영역에서 큰 반사율 때문에 측정되는 광량이 편광자와 검광자를 거치면서 넓은 각도 범위에서 최소값을 갖기 때문에 정확한 영점을 잡는 데 한계가 있다. 이러한 단점을 해결하기 위하여 우리는 PEM을 이용한 위상변조방식을 사용하였다. 위상변조 방식은 Kerr signal과 관계된 양을 PEM을 이용하여 50 kH ($1{\omega}$)와 100 kH ($2{\omega}$)의 진동 주파수에 공조시키고 이를 Lock-in-amplifier를 사용하여 탐지하기 때문에 좋은 sensitivity를 얻을 수 있을 뿐 아니라 Kerr ellipticity와 Kerr rotation을 동시에 측정할 수 있다. 자화에 필요한 전자석은 순철로 된 코어를 제작하여 챔버에 부착하였고 10 A에서 최대 7 kOe의 고자장을 얻을 수 있어 포화자화가 큰 물질에 대해서도 필요한 자성영역까지 측정이 가능하게 하였다. 또 저온 측정을 위해 SMOKE 샘플 홀더를 개조하여 액체 질소를 이용하여 100 K 근방의 영역에서 온도를 제어할 수 있도록 저온 장치를 구성하였다. 여기에서 샘플 근처에 위차한 e-beam heater가 장착된 고온 부분과 액체 질소 냉각, 온도감지를 위한 센서, cartridge heater가 장착된 저온 부분을 sapphire plate로 분리하여 저온용 cartridge heater의 파손을 최소화하였다. 이러한 SMOKE 시스템을 구성한 후에 우리는 Fe/Cr(001)시스템의 자성특성에 대해 연구하였다. Fe/Cr 시스템은 Fe/Cr/Fe의 exchange coupling이나 bulk Cr의 복잡한 자성 특성 때문에 주목을 받아왔다. 이 연구에서 우리는 저온 및 상온에서 Cr(001) 단결정 위에 증착된 Fe 박막의 자성 특성을 보고한다.

• Korean Journal of Optics and Photonics
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• v.19 no.4
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• pp.249-254
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• 2008

We developed a new x-ray image sensor utilizing a reflection-mode liquid crystal panel as its sensitive element, and tested its functionality by using it to obtain an x-ray image of a printed circuit board. In the liquid crystal x-ray image sensors hitherto reported, the liquid crystal layer is in direct contact with the photoconductive film which is deposited on a glass substrate. In the fabrication of the new x-ray image sensor, a liquid crystal panel is fabricated in the first step by using a pair of glass plates of a few centimeters thicknrss. Then one of the glass substrates is ground until its thickness is reduced to about $60\;{\mu}m$. After polishing the glass plate, dielectric films for high reflectance at 630 nm, a film of amorphous selenium for photoconduction, and a transparent conductive film for electrode are deposited in sequence. The new x-ray image sensor has several merits: primarily, fabrication of a large area sensor is more easily compared with the old fashioned x-ray image sensors. Since the reflection type liquid crystal panel has a very steep response curve, the new x-ray sensor has much more sensitivity to x-rays compared with the conventional x-ray area sensor, and the radiation dosage can be reduced down to less then 20%. By combining the new x-ray sensor with CCD camera technology, real-time x-ray images can be easily captured. We report the structure, fabrication process and characteristics of the new x-ray image sensor.

• Journal of the Korea Fashion and Costume Design Association
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• v.23 no.4
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• pp.19-37
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• 2021

The purpose of this study is to apply the characteristics of David Hockney's paintings to fashion illustration and thereby, review how pure art can be harmoniously grafted onto fashion commodities and thereupon, suggest a far more developed and unique fashion illustration. For the research, this study analyzed David Hockney's late painting works, after the 1980s; the analysis was focused on photo collages, multiple perspectives, the movement of the viewpoint, and lights and colors. In order to produce an artwork, the researcher selected 4 painting works; one work for decade for the period from the 1980s to the 2010s. This study selected 'shoes' as subjects for expression in an effort to depart from the convention approach of focusing on apparel and thereby, suggest some differentiated fashion illustrations. In terms of the artwork production size, four canvases #5 were combined into a set, and thus, a total of four sets were developed. The results are as follows. First, it was very interesting to develop a fashion illustration making use of David Hockney's paintings, and it was proven that the fashion illustration applying the sensitivity of the pure art would provide a unique sense of art. Secondly, as the boundary among disciplines becomes blurred, painting provides a new source of insights and motifs to the diverse design areas to satisfy diversified human needs, and furthermore, the development and diversified application of the fashion illustrations could be confirmed. Thirdly, David Hockney's differentiated world of art, technique of expression and sensitive colors could well be applied to fashion illustrations. This study proves that we fashion artists can depart from the conventional expressions focused on the apparel to expand the fashion illustration into lady's high heels.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.207-213
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• 1997

A field effect transistor(FET) type dissolved carbon dioxide($pCO_{2}$) sensor with a double layer structure of hydrogel membrane and $CO_{2}$ gas permeable membrane was fabricated by utilizing a $H^{+}$ ion selective field effect transistor(pH-ISFET) with Ag/AgCl reference electrode as a base chip. Formation of hydrogel membrane with photo-crosslinkable PVA-SbQ or PVP-PVAc/photosensitizer system was not suitable with the photolithographic process. Furthermore, hydrogel membrane on pH-ISFET base chip could be fabricated by photolithographic method with the aid of N,N,N',N'-tetramethyl othylenediarnine(TED) as $O_{2}$ quencher without using polyester film as a $O_{2}$ blanket during UV irradiation process. Photosensitive urethane acrylate type oligomer was used as gas permeable membrane on top of hydrogel layer. The FET type $pCO_{2}$ sensor fabricated by photolithographic method showed good linearity (linear calibration curve) in the range of $10^{-3}{\sim}10^{0}\;mol/{\ell}$ of dissolved $CO_{2}$ in aqueous solution with high sensitivity.