• Title/Summary/Keyword: 표준점도계

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Uncertainty Evaluation of Viscosity Measurement Standards (점도 측정표준 불확도 평가)

  • Choi, H.M.;Yoon, B.R.;Lee, Y.B.;Choi, Y.M.;Lee, S.H.
    • 유체기계공업학회:학술대회논문집
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    • 2005.12a
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    • pp.295-301
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    • 2005
  • Viscosity measurement standards were evaluated according to ISO/IEC 17025. The step-up procedure was employed to calibrate a series of capillary type master viscometers. Uncertainty was calculated with evaluation of various uncertainty factors affected in viscosity measurement. The maximum expanded uncertainty(U) of the master viscometer was $3.0{\times}10^{-3}$(at the confidence level of 95 %). This evaluation example will be useful in viscosity measurement uncertainty determination of other standard measurement.

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Thermal Conductivity Measurement of Saturated Clayey Mixtures using Oedometer Consolidation and Constant Rate of Strain Consolidation Tests (표준압밀시험 및 일정변형율 압밀시험 결과를 이용한 포화된 혼합 점성토의 열전도계수 측정에 관한 실험적 연구)

  • Kim, HakSeung;Kwon, HyungSeok;Lee, Jangguen;Cho, Nam Jun;Kim, Hyun-Ki
    • The Journal of Engineering Geology
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    • v.22 no.3
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    • pp.275-281
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    • 2012
  • Thermal distribution in soils must be considered in engineering designs and constructions, including estimates of frost heave and thaw settlement, infrastructure in cold regions, and geothermal systems. Because thermal conductivity is a key parameter for evaluation of thermal distribution in soils, it must be accurately estimated. The thermal conductivity of fine-grained soils has been widely studied in recent years; however, few studies have reported a reliable method for experimental measurement. The present study presents the results of an experimental investigation of the thermal conductivity of a saturated kaolinite-silica mixture with respect to the variation of dry density. Thermal conductivities were measured in Constant Rate of Strain (CRS) consolidation tests, and the experimental data were analyzed to evaluate the accuracy of the new measurement system. In addition, we present an evaluation method for predicting thermal conductivity in fine-grained soils.

Study on the Copper-Arsenic Green Pigments used on Shamanic Paintings in the 19~20th century (19~20세기 무신도 등에 사용된 구리-비소 녹색 안료에 대한 연구)

  • Oh, Joon Suk;Choi, Jung Eun;Choi, Yoon Hee
    • Journal of Conservation Science
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    • v.31 no.3
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    • pp.193-214
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    • 2015
  • The green pigments of shamanic paintings (83 items) in the 19~20th century were analyzed with X-ray fluorescent spectrometer(XRF), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (ATR-FTIR). In 60 items, copper and arsenic were detected in green pigments of the paintings by XRF spectra. Cu $K{\alpha}$/As $K{\beta}$ (peak intensity ratio of copper and arsenic) of shamanic paintings of Bokgaedang (shrine), solemn paintings (romance of three kingdoms) of Donggwanwangmyo and unknown enshrined place were 5.93~12.04 and higher compared to 5.67-6.26 of standard emerald greens and 4.01~7.89 of remaining shamanic paintings. The SEM images of crystal forms of copper-arsenic green pigments were various. Crystal forms were divided into oval and round spherulite with intersecting plate crystals and spherulite with agglomerate plate crystals. The crystals of the latter were found in shamanic paintings of Bokgaedang (shrine), solemn paintings (romance of three kingdoms) of Donggwanwangmyo and unknown enshrined place and the former were found in the rest of shamanic paintings. Copper-arsenic green pigments of shamanic paintings were identified as Scheele's green from shamanic paintings of Bokgaedang (shrine) and romance of three kingdoms. Emerald green from the rest of shamanic paintings by ATR-FTIR. From analytical results, it is confirmed that Scheele's green of shamanic paintings of Bokgaedang and romance of three kingdoms was used in the 1850s~1870s and emerald green had been widely used from late 19th century to 1970 in the rest of shamanic paintings.

Using Air-coupled Sensors (ASC) for Non-contact Non-destructive Evaluation of Concrete in Structures (Air-coupled 센서를 이용한 비접촉 콘크리트 비파괴 검사법)

  • Kee, Seong Hoon
    • Magazine of the Korea Institute for Structural Maintenance and Inspection
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    • v.17 no.1
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    • pp.48-59
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    • 2013
  • 응력파의 기반한 비파괴 검사법은 비교적 실험 절차 및 실험에 필요한 장비가 단순하고, 인체에 해가 없으며, 비용이 저렴한 특성을 갖고있다. 따라서 건축/토목 구조물의 비파괴 검사에 매우 효과적인 방법으로 알려져 있다. 하지만 기존의 가속도계, 변위계, 지오폰과 같은 부착 센서를 사용할 경우 표면 처리, 센서의 부착 및 이동에 따른 추가적인 시간이 소요되고, 센서와 구조물의 불완전한 커플링으로 인한 측정 결과의 신뢰성 및 일관성을 유지하지 어렵다는 문제를 발생시킨다. 최근 이러한 문제의 해결책으로 Air-coupled sensor (ACS)의 사용이 각광받고 있으며, 여러 연구자들에 의해 ACS의 가능성 및 실용성이 증명되고 있다. 기존의 접촉센서와 비교하여 ACS를 사용했을 때 얻을 수 있는 가장 큰 장점은 센서의 커플링 문제를 근본적으로 해결하여 신뢰도가 높고 일관적인 측정이 가능하고, 대형 건축/토목 구조물의 표면을 음향스캔하여 결과를 신속하게 처리하여 실시간으로 시각화 할 수 있다는 점이다. 이론적으로 ACS를 이용하여 측정하는 물리값은 콘크리트 내부에서 발생된 응력파의 일부가 공기중으로 전파된 누설파 (Leaky wave)이다. 콘크리트 비파괴 검사에 주로 사용하는 100 kHz이하의 저주파를 측정할 경우 일반적으로 콘텐서마이크가 ACS로 사용될 수 있다. 기존 연구자들은 실험 및 이론적 연구를 통하여 응력파에 기반한 비파괴 방법에서 ACS가 기존의 접촉 센서를 대체할 수 있다는 점을 보여주고 있다. 현재 미국에서는 연방 도로청 (FHWA) 및 국가표준기술연구소 (NIST)의 연구비 지원으로 ACS의 실용성을 높이기 위하여 최적화된 음향반사판의 설계를 통한 ACS 의 민감도를 높이기 위한 연구, 다채널 센서 배열 및 데이터 통합을 위한 새로운 알로리즘 개발, 자동화 및 로봇 기술과 융합과 같은 연구가 활발히 진행되고 있다. 멀지 않은 미래에는 ACS를 장착한 무인 로봇이 다양한 종류의 건축/토목 구조물의 건전도를 평가하기 위하여 종횡무진 활약하는 모습을 현실 속에서 볼 수 있을 것이라 기대한다.

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Spectrophotometric Determination of Soil Chemical Properties Using Soiltek® KA-P Spectrophotometer (Soiltek KA-P 분광광도계률 사용한 토양 화학적 성질의 분광학적 분석)

  • Hyun, Hae-Nam;Oh, Sang-Sil;Koo, Bon-Jun;Kang, Ho-Jun
    • Korean Journal of Soil Science and Fertilizer
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    • v.33 no.2
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    • pp.127-138
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    • 2000
  • To enable rapid and convenient soil test, new soil analytical methods, which require only one instrument, UV/Vis spectrophotometer, were developed and named "Soiltek KA-P spectrophotometric methods". The Soiltek$^{(R)}$ KA-P spectrophotometric method was compared with standard method of RDA in analytical capability for soil chemical properties. Using the 78 soils collected from upland, paddy, orchard, and vinyl house soils, soil organic matter, exchangeable K, Ca, and Mg. CEC, available $SiO_2$, and nitrate were analyzed by the two methods. The color stability(ratio of the absorbance at elapsed time t to the absorbance at time t=0) of organic matter. Ca, Mg, and available $SiO_2$ decreased to about 2% within one hour. However, that of exchangeable K, CEC, and nitrate remained constant. The results obtained with Soiltek$^{(R)}$ KA-P spectrophotometric method showed highly significant correlation with those measured by the standard method of RDA($R^2$ >0.9501), in which the slopes were near unity of $1.0{\pm}0.05$. The standard deviation values of organic matter, exchangeable K, Ca, and Mg, CEC, available $SiO_2$, and nitrate were apparently lower than ${\pm}1.8gkg^{-1}$, ${\pm}0.05cmol^+kg^{-1}$, ${\pm}0.18cmol^+kg^{-1}$, and ${\pm}0.13cmol^+kg^{-1}$, ${\pm}1.0cmol^+kg^{-1}$, ${\pm}5.0mgkg^{-1}$, and ${\pm}10.0mgkg^{-1}$, respectively. All the measurements showed coefficients of variation of less than 7~17% and were within the confidence level of 95%, which means both the methods are precise. Considering the relative simplicity, low cost, precision and accuracy, the proposed Soiltek$^{(R)}$ KA-P spectrophotometric methods could be recommended as an alternative to standard method.

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Physicochemical Properties of Korean Raw Noodle Flours (우리나라 생면용 밀가루의 성질)

  • Shin, Soong-Nyong;Kim, Sung-Kon
    • Korean Journal of Food Science and Technology
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    • v.37 no.3
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    • pp.418-424
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    • 2005
  • The physicochemical properties of raw noodle flours (n = 11) commercially produced from Australian Standard White (ASW) (Group 1, n = 8) and blonds (Group 2, n = 3) of ASW and Australian hard, western white or hard red winter were investigated. Protein and ash contents were lower in Group 1. The tristimulus color values, mean particle size, flour swelling volume (FSV) and rheological parameters of farinograph and extensigraph were not different between two flour groups. Peak viscosity measured with Rapid Visco Analyzer was higher in Group 1. The protein content was positively correlated with mean particle size, dough stability and dough extensibility, and negatively correlated with FSV and peak viscosity. The FSV wag positively correlated with the peak viscosity. The rheological parameters of dough did not show any correlations with FSV and peak viscosity.

Development of AAS and Determination of metals in airborne particles (원자흡수분광광도계의 제작 및 분진 중 금속성분 분석 비교)

  • Choi, Bae-Jin;Bang, Myung-Sik;Yeo, In-Hyeong
    • Analytical Science and Technology
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    • v.16 no.3
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    • pp.226-231
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    • 2003
  • We analyzed the concentrations of heavy metals associated airbone particles by using AAS made by both a domestic manufacturer and one of the foreign manufacturer. One model developed by a domestic manufacture showed excellent results in the selected wavelength with an excellent performance of a monochromator. It abandons a big drop except a fine drop to improve reproduction in atomizer, so that no remains should leave. Using the low pass filter we were able to reduce a noise of detection signal. The performance of our equipment was found to be highly compatible with that of a foreign company as we achieved the detection limit of about $0.015{\mu}g/L$ using a standard solution of Au. The PM samples had been collected from by main observation points in 7 areas of Seoul city from 2001 to the spring in 2002. with these PM sample we analyzed the concentrations of Pb, Cu, Mn, Cd, Ni, Fe, Cr, Co, Mg and Al.