• 반도체디스플레이기술학회지
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• 제4권1호
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• pp.1-8
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• 2005

Linear motor can be directly applied to the system needed linear motions without rotary motions. To control high-speed and high-resolution, the development of the linear motors is recently required in the high-integrated and speed process industry This paper presents thermal and vibration analyses as well as measurement standards of the newly developed linear motors through analyzing the thermal behaviors and vibration characteristics of the advanced products. The thermal measurements are conducted for comparing the developed linear motor with the advanced linear motor and the Finite Volume Method(FVM) is used to identify the measurement results. And then the vibration measurement are carried out in the developed and advanced linear motors with respect to the speed. To identify the measurement results, the Finite Element Method is utilized in the developed and advanced linear motors, respectively. The FVM, FEM, and experiments make it possible to understand these characteristics. The improvement is suggested through their results conducted experiment and analyses.

• Bulletin of the Korean Chemical Society
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• 제28권7호
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• pp.1175-1182
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• 2007

A series of new organic semiconductors hexyl end-capped thiophene-anthracene oligomers containing the anthracene moiety in the center of the oligomers are synthesized. The target oligomers have been obtained by Stille coupling reactions as key step reactions. The synthesized thiophene-anthracene oligomers were characterized by 1H-NMR, 13C-NMR and high-resolution mass spectroscopy, respectively. All of the oligomers are soluble in chlorinated solvents. Their optical, thermal and electrochemical properties were measured. The hexyl end-capped oligomers and their unsubstituted oligomers exhibit the same absorption behavior in dilute toluene solution. Hexyl end-capped bis-terthienylanthracene oligomer is observed to show liquid crystalline mesophase at 166 oC in heating process. The thermal analyses as well as the electrochemical measurement data indicate that the designed materials show better thermal and oxidation stability than the corresponding oligothiophenes without anthracene core. Fluorescence lifetimes and fluorescence quantum yields of the thiophene-anthracene oligomers are measured to be 10-14 ps and 3.4-9.9 × 10?3 which are much shorter and lower than those of oligothiophenes respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.301-301
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• 2008

Ion beam (IB)-induced alignment of inorganic materials has been investigated intensively as it provides controllability in a nonstop process for producing high-resolution displays[1][2]. LC orientation via ion-beam (IB) irradiation on the nitrogen doped diamond like carbon (NDLC) thin film deposited by physical deposition method-sputtering was embodied. The NDLC thin film that was deposited by sputter showed uniform LC alignment at the 1200eV of the ion beam intensity. The pretilt angle of LC on NDLC thin films was measured with various IB exposure time and angle. The maximum pretilt angle were showed with IB irradiation angle of $45^{\circ}$ and exposure time of 62.5 sec, respectively. To show NDLC thin film stability in high temperature, thermal stability test was proceeded. The uppermost of the thermal stability of NDLC thin film was $200^{\circ}C$. In this investigation, the electro-optical (EO) characteristics of LC on NDLC thin film were measured.

• 한국공작기계학회논문집
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• 제15권4호
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• pp.44-48
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• 2006

Recently, demand the ultra precision product which is increasing rapidly is used extensively frontier industry field such as semi-conductor, computer, aerospace, precision machine. Ultra precision processing is the portion that is very needed to NT in the field of mechanical engineering. The latest date, together with radical advancement of electronic and photonics industry, necessity of ultra precision processing is on the increase for the manufacture of various kernel parts those are connected with these industrial fields. Specially, require motion accuracy of high resolution of nm order in stroke of hundreds millimeters according as diameter of processing object great and processing accuracy rises. In this case ,the response speed absolute delay because inertial mass of moving part is very large. Therefore, real time motion error compensation becomes very hardly. In this paper, we used ultra precision cutting unit(UPCU) to cope such problem. a UPCU is designed and tested to obtain sub-micrometer from accuracy in diamond turning of flat surfaces. The thermal growth spindle error is compensated for real time using a UPCU driven by piezoelectric actuator along with a laser encoder displacement sensor.

• Progress in Superconductivity
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• 제12권1호
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• pp.41-45
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• 2010

Low temperature micro-calorimeters have been employed in the field of high resolution alpha spectrometers. These alpha detectors typically consist of a superconducting or metal absorber and a temperature sensor. The temperature sensor can be a transition edge sensor (TES), a metallic magnetic calorimeter (MMC) or other low temperature detectors for an accurate measurement of temperature change due to an alpha particle absorption. We report a recent study of the heat flow between a replaceable absorber and a temperature sensor. A piece of gold foil in $2.4{\times}2.7{\times}0.03\;mm^3$ is used as an absorber. A $40\;{\mu}m$ diameter Au:Er paramagnetic sensor is attached to another small piece of gold foil in $400{\times}200{\times}30\;{\mu}m^3$ to serve as the temperature sensor. This sensor assembly, Au:Er and gold foil, is placed on a miniature SQUID susceptometer in a gradiometric configuration. The thermal connection between the absorber and the sensor was made with three gold bonding wires. The measured thermal conductance shows a linear dependence to the temperature. The values are in a good agreement with Wiedemann-Franz type thermal conductance of the gold wires.

• Progress in Superconductivity
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• 제9권2호
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• pp.162-166
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• 2008

We are developing a sensitive gamma ray spectrometer based on superconducting transition edge sensors. The detector consists of a small piece of high purity Sn as an absorber and a Ti/Au bilayer as a temperature sensor. It is designed to measure the thermal signal caused by absorption of gamma rays. The mechanical support and the thermal contact between the absorber and the thermometer were made with Stycast epoxy. The bilayer was formed by e-beam evaporation and patterned by wet etching on top of a $SiN_X$ membrane. A sharp superconducting transition of the film was measured near 100 mK. When the film was biased to the edge of the transition, signals were observed due to single photon absorption emitted from an $^{241}Am$ source. The measured spectrum showed several characteristic peaks of the source including 59.5 keV gamma line. The full with at half maximum was about 900 eV for the 59.5 keV gamma line. The background was low enough to resolve low energy lines. Considerations to improve the energy resolution of the gamma ray spectrometer are also discussed.

• 한국자동차공학회논문집
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• 제21권1호
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• pp.23-29
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• 2013

In recent years, development of energy conversion systems using hydrogen as an energy source has been accelerated globally. Even though hydrogen is an environment-friendly energy source, safety and effectiveness issues in storage, transportation, and usage of hydrogen should be clearly resolved in every application. Therefore, sensors for detecting hydrogen leakage, especially for fuel cell electric vehicles, should be designed to have much higher resolution and accuracy in comparison with conventional gas sensors. In this study, we conducted to determine the design parameters for the semiconductor hydrogen sensor with optimized sensing conditions under the thermal distribution characteristic and thermal transfer characteristic. The heat generation study on power supply voltage was studied for correlation analysis of thermal energy according to the power supply voltage variation from 1.0 voltage to 10.0 voltage every 0.5 voltage. And we studied for the temperature coefficient of resistance with hydrogen sensor.

• 한국광학회지
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• 제13권6호
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• pp.530-536
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• 2002

열팽창계수의 정확한 측정은 재료과학이나 공업기술 분야에서 가장 중요한 요구량 중의 하나이다. 음향광변조기(AOM)를 이용한 고분해능 간섭식 열팽창계를 제작하여 성능검사를 하였다. 이 계는 이중광로 헤테로다인 간섭계와 복사열 전기로로 구성되어, 정밀한 변위의 측정과 시료의 신속한 가열 및 냉각이 가능토록 하였다. 또한 레이저의 주파수 안정화를 위하여 2차 맥놀이 주파수를 이용한 3종모드 안정화 He-Ne 레이저를 제작하였으며, 이때의 주파수 안정도는 5$\times$$10^{-9}$이었다. 제작된 계의 길이 측정은 실온에서 1100k온도영역에서 나노미터 정도의 정밀도를 주었다.

• 한국광학회지
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• 제16권6호
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• pp.547-552
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• 2005

광간섭 단층촬영(OCT)용으로 원통형 압전소자(PZT)와 단일모드 광섬유를 이용한 광경로 지연기를 제작하여 그 특성을 분석하였다. 광경로 지연기에서 발생하는 편광모드 분산은 편광조절기로 조절하였고, 열요동을 2중 광경로 지연기를 구성하여 최소화하였다. 이중 광경로 지연기는 단일 광경로 지연기에 비해 2배의 측정 깊이와 속도를 구현하여 $18.6\pm0.5{\mu}m$의 해상도. 측정 깊이 1.68 mm, 측정 녹도 360.4 mm/s를 각각 얻었다.

• 한국분말재료학회지
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• 제25권1호
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• pp.48-53
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• 2018

One-dimensional rutile $TiO_2$ is an important inorganic compound with applicability in sensors, solar cells, and Li-based batteries. However, conventional synthesis methods for $TiO_2$ nanowires are complicated and entail risks of environmental contamination. In this work, we report the growth of $TiO_2$ nanowires on a Ti alloy powder (Ti-6wt%Al-4wt%V, Ti64) using simple thermal oxidation under a limited supply of $O_2$. The optimum condition for $TiO_2$ nanowire synthesis is studied for variables including temperature, time, and pressure. $TiO_2$ nanowires of ${\sim}5{\mu}m$ in length and 100 nm in thickness are richly synthesized under the optimum condition with single-crystalline rutile phases. The formation of $TiO_2$ nanowires is greatly influenced by synthesis temperature and pressure. The synthesized $TiO_2$ nanowires are characterized using field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HR-TEM).