• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.113.2-113.2
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• 2014

Heat is a familiar form of energy transported from a hot side to a colder side of an object, but not a notion associated with microscopic measurements of electronic properties. A temperature difference within a material causes charge carriers, electrons or holes, to diffuse along the temperature gradient inducing a thermoelectric voltage. Here we show that local thermoelectric measurements can yield high sensitivity imaging of structural disorder on the atomic and nanometre scales. Using this imaging technique, we discovered a defect-mediated dimensional evolution of strain-response patterns in epitaxial graphene with increasing thickness.

• E2M - 전기 전자와 첨단 소재
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• 제11권11호
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• pp.17-21
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• 1998

The surface potential distribution on insulating polymers was measured by scanning of the probe of an electrostatic voltmeter. The measurements were done for two measured by scanning of the probe of an electrostatis voltmeter. The measurements were done for two cases. In the first case, it was measured on the free surface of insulating films which had been inserted between plane electodes after the removal of the upper brass disk electrode. In the second case, we measured the charging region between a circular and its opposing concentric ring electrodes after the removal of dc ramp voltage in air and nitrogen gas.

• 마이크로전자및패키징학회지
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• 제18권3호
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• pp.39-43
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• 2011

마이크로파 유전체의 Q 값 측정에 널리 사용되고 있는 유전체 공진기 방법에서 캐비티의 재질변화가 유전체의 Q 값 측정에 미치는 오차요인에 대해 HFSS 시뮬레이션과 실측평가를 병행하여 조사하였다. HFSS의 전자계 벡터 형상으로부터 $TE_{01\delta}$ 모드의 공진주파수를 결정하고 $S_{21}$ 파라메터의 3dB 대역폭으로부터 Q 값을 계산하였다. 캐비티 금속이 Cu, SUS, Au 등으로 변화할 경우 유전체 공진기의 Q 값 측정에 큰 오차는 발생하지 않았으나, 금속이 산화하여 전도도가 수 천 정도로 떨어질 경우 Q 값이 매우 낮게 측정되는 오차가 발생함을 확인하였다. 이러한 시뮬레이션 결과는 실제로 다양한 재질의 금속 캐비티를 가지고 유전체 공진기의 Q 값을 측정해 본 결과 서로 일치되는 관련성을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.36-39
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• 2000

A small electrical potential difference which appears on any solid body when subjected to illumination by a modulated light beam generated by laser is called photocharge voltage(PCV)[1,2]. This voltage is proportional to the induced change in the surface electrical charge and is capacitatively measured on various materials such as conductors, semiconductors, ceramics, dielectrics and biological objects. The amplitude of the detected signal depends on the type of material under investigation, and on the surface properties of the sample. In photocharge voltage spectroscopy measurements[3], the sample is illuminated by both a steady state monochromatic bias light and the pulsed laser. The monochromatic light is used to created a variation in the steady state population of trap levels in the surface and space charge region of semiconductor samples which does result in a change in the measured voltage. Using this technique the spatial variation of PCV can be utilized to evaluate the surface conditions of the sample and the variation of the PCV due to the monochromatic bias light are utilized to characterize the surface states. A qualitative analysis of the proposed measurement is present along with experimental results performed on amorphous silicon samples. The deposition temperature was varied in order to obtain samples with different structural, optical and electronic properties and measurements are related to the defect density in amorphous thin film.

• Tribology and Lubricants
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• 제25권1호
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• pp.20-24
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• 2009

TiC-derived carbon coatings have been synthesized at $600^{\circ}C$ temperature treatment with $H_2/Cl_2$ mixture gases. From Raman spectroscopy measurements, the modified layer was covered with carbon and the thick-ness of the layer was increased with increasing reaction time. And $I_D/I_G$ ratio was decreased with increasing reaction time. The superior tribological property was obtained from TiC reacted with $Cl_2$ gas for 2 hrs. And the tribological property measurements indicate that TiC-derived carbon layer has $0.9{\times}10_{-6}mm^3/Nm$ in wear coefficient and 0.13 in friction coefficient.

• 한국가시화정보학회지
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• 제19권3호
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• pp.54-62
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• 2021

This study has investigated the 3-D deflection characteristics of a flexible plate levitated by non-contact grippers using SPIV method. The measuring instrument consisted of a flexible plate located under four non-contact grippers and two cameras at the bottom of a transparent acrylic plate. Measurements were made on two materials (PVC and PC) for the plate with 50×50 cm2 area and 1 mm thickness. The deflection characteristics and flatness vary depending on the plate material, the gripper position and the air flow supplied to the gripper. For the material of PVC, the overall defection is convex. As the gripper position goes outward from the plate center, the upmost bending point also moves to the outside of the plate with the flatness increasing. However, the air flow rate does not affect the deflection pattern except for the small increase of flatness. For the material of PC, the shape of deflection changes from convex to concave as the gripper position goes out. The flatness is the highest at the point of transition from convex to concave, but the air flowrate has little effect on the flatness.

• 복식문화연구
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• 제13권4호
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• pp.526-539
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• 2005

Recently in the apparel industry, early adolescent girls are emerging as a new consumer group. In response to this, companies are developing clothes, cosmetics, underwear, etc. This study proposed a new size range and size interval for early adolescent girls and presented reference measurements for body parts necessary in designing clothes. For this purpose, a total of 529 girls aged between 10 and 14 were measured and data were collected from 42 anthropometric measurements and 41 photographic measurements per a person. SAS 8.1 was used in data analysis including means, standard deviations, frequency analysis. Based on the results, this study proposed: for Type A - 7 sizes (140A-67, 145A-65, 145A-69, 150A-69, 150A-73, 155A-73, 155A-76): for Type X - 7 sizes (150x-72, 155x-72, 155x-77, 160x-77, 160x-80, 165x-77, 165x-80); and for Type H - 8 sizes (145H-74, 145H-82, 150H-78, 150H-82, 155H-82, 155H-86, 160H-86, 160H-88). Reference measurements suggested for upper garments were 9 items. The outcome of this study may be used as a basic material for adolescent apparel manufacturers to set their apparel sizing system and to supply their consumers, namely, adolescent girls with products fitting their somatotype.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.53-53
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• 2011

This paper describes results for surface and bulk characterization of the most promising thin film solar cell material for high performance devices, (Ag,Cu) (In,Ga) Se2 (ACIGS). This material in particular exhibits a range of exotic behaviors. The surface and general materials science of the material also has direct implications for the operation of solar cells based upon it. Some of the techniques and results described will include scanning probe (AFM, STM, KPFM) measurements of epitaxial films of different surface orientations, photoelectron spectroscopy and inverse photoemission, Auger electron spectroscopy, and more. Bulk measurements are included as support for the surface measurements such as cathodoluminescence imaging around grain boundaries and showing surface recombination effects, and transmission electron microscopy to verify the surface growth behaviors to be equilibrium rather than kinetic phenomena. The results show that the polar close packed surface of CIGS is the lowest energy surface by far. This surface is expected to be reconstructed to eliminate the surface charge. However, the AgInSe2 compound has yielded excellent atomic-resolution images of the surface with no evidence of surface reconstruction. Similar imaging of CuInSe2 has proven more difficult and no atomic resolution images have been obtained, although current imaging tunneling spectroscopy images show electronic structure variations on the atomic scale. A discussion of the reasons why this may be the case is given. The surface composition and grain boundary compositions match the bulk chemistry exactly in as-grow films. However, the deposition of the heterojunction forming the device alters this chemistry, leading to a strongly n-type surface. This also directly explains unpinning of the Fermi level and the operation of the resulting devices when heterojunctions are formed with the CIGS. These results are linked to device performance through simulation of the characteristic operating behaviors of the cells using models developed in my laboratory.

• 보존과학회지
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• 제25권3호
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• pp.233-244
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• 2009

이 연구에서는 석조문화재의 초음파 측정에 적합한 탐촉자 및 접촉매질을 선정하였으며, 과학적이며 정량적인 평가기술을 개발하기 위해 암종별 직접 및 간접전달방법의 상관관계를 분석하였다. 이 결과, 석조문화재에서 초음파 측정은 유형 3의 탐촉자(UTREXTX(RX)54kHz)와 접촉매질(고무찰흙)을 사용하는 것이 가장 적합한 것으로 나타났다. 또한 이 유형 3의 직접 및 간접전달방법의 보정계수는 화강암 1.50, 반려암 1.38, 석영섬록암 1.58로 산출되었다. 이 결과는 초음파탐사의 신뢰도를 높이기 위한 최초의 연구로서 석조문화재의 초음파탐사 방법을 확립하는데 크게 기여할 것으로 판단된다. 또한 암석의 표면요철도와 다양한 접촉매질을 고려한 보완연구가 수행되어야 할 것이며, 암종별 직접-간접전달방법의 상관관계에 대한 데이터베이스도 구축되어야 할 것이다.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.167-171
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• 2016

Background: TlBr is of considerable technological importance for radiation detection applications where detecting high-energy photons such as X-rays and ${\gamma}$-rays are of prime importance. However, there were few reports on investigating optical properties of TlBr itself for deeper understandings of this material and for making better radiation detection devices. Thus, in this paper, we report on the optical characterizations of TlBr single crystals. Spectroscopic ellipsometry (SE) and photoluminescence (PL) measurements at RT were performed for this work. Materials and Methods: A 2-inch TlBr single crystalline ingot was grown by using the vertical Bridgman furnace. SE measurements were performed at RT within the photon energy range from 1.1 to 6.5 eV. PL measurements were performed at RT by using a home-made PL system equipped with a 266 nm-laser and a spectrometer. Results and Discussion: Dielectric responses from SE analysis were shown to be slightly different among the different samples possibly due to the different structural/optical properties. Also from the PL measurements, it was observed that the peak intensities of the middle samples were significantly higher than those of the other two samples. With the given values for permittivity of free space (${\varepsilon}_0=8.854{\times}10^{-12}F{\cdot}m^{-1}$), thickness (d = 1 mm), and area ($A=10{\times}10mm^2$) of the TlBr sample, capacitances of TlBr were 6.9 pF (at $h{\nu}=3eV$) and 4.4 pF (at $h{\nu}=6eV$), respectively. Conclusion: SE and PL measurement and analysis were performed to characterize TlBr samples from the optical perspective. It was observed that dielectric responses of different TlBr samples were slightly different due to the different material properties. PL measurements showed that the middle sample exhibited much stronger PL emission peaks due to the better material quality. From the SE analysis, optical, dielectric constants were extracted, and calculated capacitances were in the few pF range.