• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.50-52
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• 2003

The purpose of this study is to measure the thermal conductivity of a carbon/phenolic 8-harness woven composite. An experiment apparatus and procedure developed in the previous study were used to measure the thermal conductivities. This method compares the temperature difference between a reference specimen with a known thermal conductivity and the test sample specimen in a steady-state condition.

• Journal of the Korean Data and Information Science Society
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• v.19 no.4
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• pp.1183-1189
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• 2008

The general formulas of the operating characteristic(OC) function, average sample number(ASN) and average outgoing quality(AOQ) for the modified n-level skip-lot sampling plan(MMSkSP2) were derived using Markov chain properties by Cho(2008). In this paper, the OC curve, ASN and AOQ of a reference plan, modified two-level, three-level and five-level skip-lot sampling plans are compared.

• Journal of the Korean Statistical Society
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• v.11 no.1
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• pp.12-24
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• 1982

Selection procedures are proposed for selecting the 'best' industrial process with the smallest fraction defective. For normally distributed industrial processes, this is equivalent to selecting in terms of coefficients of variation. For the case of known vairances, selection procedures by Bechhofer (1954), and Bechhofer and Turnball (1978) are appropriate. We treat this problem for the case of uknown variances with or without reference to a standard. The large sample solutions of design constants are tabulated and the performance of these approximate solutions are investigated.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.156-156
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• 2010

A detailed investigation and structure of tested samples are clearly presented. As a reference, $Ge_1Se_1Te_2$/As only sample was also investigated. We used compound of Ge-Se-Te material for phase-change cell. Actually, the performance properties have been improved surprisingly then conventional Ge-Sb-Te. However, crystallization time was as long as ever for amorphization time. We conducted this esperiment in order to solve that problem by doping-As with Ag layer.

• Analytical Science and Technology
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• v.30 no.5
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• pp.240-251
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• 2017

1,1,1,2-Tetrafluoroethane (HFC-134a), which is used as refrigerant in air conditioners, has been recently regulated as a greenhouse gas and is recommended for reuse by refining. It is very important to quantitatively analyze trace impurities present in the refrigerant to evaluate the criteria for reuse. In this study, trace impurities including C, H, Cl, and F, which are difficult to quantify because there are no reference materials, were quantitatively analyzed by a gas chromatograph-atomic emission detector (GC/AED); for this analysis, this was preceded by a qualitative analysis with a GC-mass selective detector (GC/MSD). In addition, the AED response was investigated using a hydrocarbon mixed reference material, which was proportional to the number of atoms in the component. Fifteen refrigerant components were detected as trace impurities in HFC-134a by qualitative analysis of trace impurities including C, H, Cl, and F in the samples. Based on the results of the qualitative analysis, quantitative analysis of trace impurities using AED showed that the highest mole fractions were for the $CHClF_2$ component ($45438.38{\mu}mol/mol$) in one sample and for the $C_2H_2ClF_3$ component ($1311.47{\mu}mol/mol$) in another sample. From this study, it has been shown that it is possible for this analytical method to be applied to the qualitative and quantitative analysis of trace compounds in refrigerants, which are difficult to quantify because of the absence of reference materials.

• Journal of Soil and Groundwater Environment
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• v.19 no.6
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• pp.49-58
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• 2014

This study was implemented as a part of the experiment to develop two kinds of soil-based Benzo[a]pyrene (BaP) proficiency testing materials (PTMs) for soil analysis. A test was carried out for the check of solubility of the reference material (high purity reagent) using several solvents. Another test was also conducted for the evaluation of homogeneity and stability of two kinds of candidate soil reference materials. The test analysis of BaP in terms of the candidate materials was conducted according to the Standard Soil Analytical Methods by Ministry of Environment. Dissolution of the reference material was shown to vary depending on solvent type and was higher in the order of Dichloromethane > Acetone > Acetone/MeOH (9 : 1) > N-hexane. In addition, the slope on calibration curve for BaP standard solutions was largest on BaP standard solutions prepared with dichloromethane of the tested solvents. Such tendency appeared egually in the commercial BaP standard solution. Therefore, it is thought to be reasonable to use dichloromethane as the solvent in case of the standard stock solution that is used for the measurement of BaP concentration in soil. ISO 13528 and IUPAC protocol were used for verification of homogeneity on the two kinds of soil candidate materials, Both candidate materials were sufficiently homogeneous. Stability assessment of the two candidate materials was made according to ISO Guide 35 and the result showed that both batches did not have any long-term and short term stability issues that might occur during shipping. However, monitoring results of BaP concentration in soil showed that BaP concentration of the two batches measured at 15 days after the sample preparation was reduced by about 24~37% compared with that of the samples measured on 0 day of the sample preparation. Identification was done with several treatments such as irradiation and sterilization etc. The major cause was shown to be irradiation to the samples.

• Analytical Science and Technology
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• v.22 no.5
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• pp.376-385
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• 2009

In our study, the accuracy for measurement of seventeen 2,3,7,8-substituted PCDDs/PCDFs in certified reference material (CRM) which is the sample of homogeneous sediment matrix taken from an area known to have significant chemical contamination, particularly PCBs (polychlorinated biphenyls), was evaluated. Though the methodology in this study followed the official method of unintentionally produced persistent organic pollutants (UPOPs) announced by the Ministry of Environment of the Republic of Korea in 2007, there were slight changes using additional purification step by activated carbon column because the interferences of sample were not sufficiently removed when only multi-silica column and alumina column have been used for purification. The |En| number proposed by the Korea Research Institute of Standards and Science was used for a valuation basis of the accuracy. The |En| numbers of seventeen 2,3,7,8-substituted PCDDs/PCDFs have been indicated as 1 and below, they were decided "Pass" in this test, when DB-5MS column and SP-2331 column were used together. Because 1,2,3,7,8-PeCDD and #169-HxCB were not separated on DB-5MS column, the ions of 1,2,3,7,8-PeCDD were selected at M/M+2 instead of M+2/M+4 suggested by EPA 1613. It is possible to distinguish them in HRGC/HRMS analysis.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1121-1121
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• 2001

A previous study (Berzaghi et al., 2001) evaluated the performance of 3 calibration methods, modified partial least squares (MPLS), local PLS (LOCAL) and artificial neural networks (ANN) on the prediction of the chemical composition of forages, using a large NIR database. The study used forage samples (n=25,977) from Australia, Europe (Belgium, Germany, Italy and Sweden) and North America (Canada and U.S.A) with reference values for moisture, crude protein and neutral detergent fibre content. The spectra of the samples were collected using 10 different Foss NIR Systems instruments, only some of which had been standardized to one master instrument. The aim of the present study was to evaluate the behaviour of these different calibration methods when predicting the same samples measured on different instruments. Twenty-two sealed samples of different kind of forages were measured in duplicate on seven instruments (one master and six slaves). Three sets of near infrared spectra (1100 to 2500nm) were created. The first set consisted of the spectra in their original form (unstandardized); the second set was created using a single sample standardization (Clone1); the third was created using a multiple sample procedure (Clone6). WinISI software (Infrasoft International Inc., Port Mathilda, PA, USA) was used to perform both types of standardization, Clone1 is just a photometric offset between a “master” instrument and the “slave” instrument. Clone6 modifies both the X-axis through a wavelength adjustment and the Y-axis through a simple regression wavelength by wavelength. The Clone1 procedure used one sample spectrally close to the centre of the population. The six samples used in Clone 6 were selected to cover the range of spectral variation in the sample set. The remaining fifteen samples were used to evaluate the performances of the different models. The predicted values for dry matter, protein and neutral detergent fibre from the master Instrument were considered as “reference Y values” when computing the statistics RMSEP, SEPC, R, Bias, Slope, mean GH (global Mahalanobis distance) and mean NH (neighbourhood Mahalanobis distance) for the 6 slave instruments. From the results we conclude that i) all the calibration techniques gave satisfactory results after standardization. Without standardization the predicted data from the slaves would have required slope and bias correction to produce acceptable statistics. ii) Standardization reduced the errors for all calibration methods and parameters tested, reducing not only systematic biases but also random errors. iii) Standardization removed slope effects that were significantly different from 1.0 in most of the cases. iv) Clone1 and Clone6 gave similar results except for NDF where Clone6 gave better RMSEP values than Clone1. v) GH and NH were reduced by half even with very large data sets including unstandardized spectra.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.34-40
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• 2004

In this paper, we have studied the OCT(Optical Coherence Tomography) system which has been advantages of high resolution, 2-D cross-sectional images, low cost and small size configuration. The characteristics of light source determine the resolution and coherence length. The light source has a commercial SLD with a central wavelength of 1,285 ill11, 35.3 nm(FWHM). The optical delay line is necessary to make equal with the optical path length to scattered light or reflected light from a sample. In order to make equal the optical path length, the stage that is attached to a reference mirror is controled by a step motor. And the interferometer is configured with the Michelson interferometer by using a single mode fiber, and the scanner can be focused on the sample by using a reference ann Also, the 2-dimension cross-sectional images were measured with scanning the transverse direction of the sample by using a step motor. After detecting the internal signal of lateral direction, a scanner is moved to obtain the cross-sectional image of 2-dimension by using step motor. A photodiode, which has high detection sensitivity and excellent noise characteristics has been used. The detected small signal has a noise and interference. After filtering and amplifying the signal, the output signal is demodulated the waveform And then, a cross-sectional image is seen through converting this signal into a digitalized signal by using an AID converter. The resolution of the sample is about 30${\mu}{\textrm}{m}$, which corresponds to the theoretical resolution. Also, the cross-sectional images of onion cells were measured in real time scheme.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.28 no.3
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• pp.171-184
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• 2002

The present study was undertaken to develop the in vitro sunprotection factor(SPF) measurement method having good correlation with in vivo method. As in vitro method, 8% homomentyl salicylate, P3 reference standard and sunscreens on market were measured using SPF 290 analyzer and were compared the SPF with labed value. In vitro SPF of 8% HMS and P3 reference standard were 4.59 $\pm$ 0.12 and 14.94 $\pm$ 0.83. There are good correlation, correlation factor were 0.9506 and 0.9769 respectively, between the in vitro and in vivo SPF for the sunscreen creams and lotions examined. Correlation factors of makeup base & liquid goundation, lotion labled with “shake before use”, compact powder were 0.8812, 0.8632 and 0.5984. The best sample applied method of compact powder was 1:0.8 mixture with cream base. These results suggest that the in vitro test method could be used as an alternative method for SPF.