• Analytical Science and Technology
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• v.13 no.2
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• pp.222-228
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• 2000

A detector for monitoring carbon monoxide (CO) in ambient air by nondispersive infrared (NDIR) spectroscopy has been developed and investigated its sensitivity and stability. The essential parts of the absorption cell are three spherical concave mirrors so as to improve the sensitivity by increasing the light path length in the cell. The radius and center of curvature of mirrors and position in the cell was calculated by computer simulation in order that the light path length may be 16m into the 50cm cell. The number of traversals and optical path properties were confirmed by laser beam alignment in transparent absorption cell. The photoconductive type lead selenide (PbSe) was used as CO sensing material, which was cooled to increase the responsibility by thermoelectric cooling method. The detection limit and span drift of the developed CO detector was 0.24ppm and 0.03ppm(v/v) respectively.

• Analytical Science and Technology
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• v.15 no.2
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• pp.120-126
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• 2002

The analytical performance of four commercially-available pneumatic nebulizers(Meinhard, Cross-flow, Babington, ESI PFA) was evaluated using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and ICP-mass spectrometry (ICP-MS) instruments. The performance of an inert concentric nebulizer and a modified conespray nebulizer, made in Korea Research Institute of Standards and Science (KRISS), is compared with that of the four commercial nebulizers. Variation of sample introduction efficiency was investigated as carrier argon pressure and sample uptake rate were changed. Variation of sensitivity, signal stability, blank intensity and oxide/hydride ratios were also studied when the nebulizers were connected to the ICP-MS and ICP-AES instruments. It was found that good analytical result such as high sensitivity, low blank, stable signal and so on can be obtained with judicious selection of the nebulizer depending on the type of sample, sample amount, type of analytical instrument and analyte.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.659-660
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• 2016

This paper presents an improved evaluation method, based on National Competency Standards (NCS), of National Technical Qualification (NTQ) examination in Electronics Fields such as Craftsman Computer, Industrial Engineer Computer Maintenance Control, Engineer Computer System Application, Engineer Computer, Engineer Embedded) to reflect practical vocational abilities and raise values of NTQ certificates. To evaluate each NTQ examination, we carefully chose corresponding NCS competency units for practical performance test, written subjective test, and mixed test through the advisory committee with industry, education, and qualification experts. In addition, we verified useful effects of the NCS-based evaluation method by performing and analyzing the simulated tests. We used both single and mixed problems in practical performance test and new problems about system design and implementation based on various working scenarios in written subjective test.

• Journal of the Korean Chemical Society
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• v.47 no.1
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• pp.31-37
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• 2003

The expanded uncertainties calculated by the application of GUM -approximation and Monte-Carlo simulation were compared about the model equation of one-point calibration which is widely used for the measurements and chemical analysis. For the comparisons, we assumed a set of artificial data at the various level of concentration and dispersion of t or normal distribution. Mistakes of more then 50 % was revealed at the values calculated by GUM-approximation in comparison with those of Monte-Carlo simulation because of the excess dispersion from t-distribution and non-linearity by division in the equation. In contrary, the mistake of calculation due to non-linearity of the equation was not observed in the level of detection limits with the equation of one-point calibration, because of the relatively large values of uncertainty in response.

• Analytical Science and Technology
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• v.16 no.3
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• pp.185-190
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• 2003

We applied modified least square method (MLS) and ordinary least square method (OLS) to 1st order equation for the comparison of the uncertainties calculated by these methods. The uncertainty calculated by OLS covered statistically safe interval because it was over-estimated in many cases of measurement and concentration level. But, if the uncertainty of the concentration as a reference value was comparably large (about 5% of the relative standard deviation of random scattering from the regression line and about 7% of relative standard uncertainty of reference values), then uncertainty calculated by OLS was seriously under-estimated at high concentration level. It was revealed that the calculated uncertainty didn't cover statistically safe interval at the stated confidence level. It was found that the method, MLS, described in the previously article would be valid for this calculation of uncertainty.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.4
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• pp.313-320
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• 2007

Recently, a new class of single-crystal piezoelectric materials such as lead metanibobate doped with lead titanate (PMN-PT) has been synthesized and were found to further enhance the electro-mechanical coupling factor compared to piezo-ceramic materials. This paper describes fabrication and evaluation of PMN-PT single crystal ultrasonic transducers for contact measurement of stainless steel that is one of the highly attenuative materials. The design conditions for ultrasonic transducer such as front matching layer between test materials and piezo-material and backing materials were investigated based on the simulation results by KLM model. The PMN-PT single crystal ultrasonic transducers with centre frequencies at 1 and 2.25 MHz were fabricated and their performances were evaluated.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.445-449
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• 1999

We studied the properties of the InAs epitaxial layers grown of (100)-oriented GaAs ($2^{\circ}$tilted toward[011]) by molecular beam epitaxy. From DCX (double-crystal x0ray), the better crystal quality was shown in InAs epitaxial layers on about 2500$\AA$ GaAs epitaxial layers on GaAs, we obtained the high mobility of InAs epitaxy in As/In BEP ratio (1.2~2.0) from Hall effect measurement. The electron mobility increased as electron concentration increases, until Si cell temperature $960^{\circ}C$$(N_D=2.21\times10^{-17}\textrm{cm}^{-3})$. The mobility decreases as the Si cell temperature increases, at the temperature over $960^{\circ}C$. We obtained the high mobility (1.10$\times$104cm2/V.s) at Si electron concentration of $N_D=2.21\times10^{-17}\textrm{cm}^{-3}$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.913-921
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• 2019

The government introduced the comprehensive evaluation bidding system with the goal of pursuing the best value and the global standard in 2016. However, for the evaluation criteria on the construction evaluation reflected to the comprehensive evaluation bidding system, the problems of the objectivity insufficiency, the inclusion of multiple subjective evaluation items, and the irrationality of the weight for each evaluation item are continue to be presented. The central office group, the local government, the relevant industry, and the expert group share recognition, but the solution is not derived. Hence, the major evaluation items to be improved were derived with the characteristics analyzed to secure the objectivity of the construction evaluation. For the analysis method, the standard deviation and the Fleiss Kappa analysis method were used by utilizing the characteristics that the construction evaluation criteria consist of all 4-point measures (good, average, insufficient, and poor). According to the result, the 10 evaluation items of the total 25 construction evaluation items were derived as the evaluation items to be improved. It was found in the analysis on the major characteristics of the derived evaluation items that the qualitative evaluation criteria such as 'Very Suitable' and 'Suitable' were commonly included in the detailed evaluation guidelines. Hence, as far as the future construction evaluation standards are concerned, the qualitative evaluation standards are sublated, and the improvement should be made mainly for the quantitative evaluation criteria enabling the objectivity assurance.

• Journal of The Korea Institute of Healthcare Architecture
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• v.17 no.2
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• pp.7-16
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• 2011

The death toll of the elderly by accidents in 2007 takes 6.5% of total death toll. The lost income from this is estimated to be 17 trillion and 511 billion won. According to CISS of Korea Consumer Protection Board, the number of safety related accidents of the elderly at home in 2006 was 486 cases in 2006 and has gradually increased every year. This thesis created 115 guidelines at 14 spaces as facility evaluation index evaluating the aging friendliness of the facility and safety related accidents generated at elderly resident welfare facility, examined influence variables of safety related accidents with 191 elderly including demographic variable, physical skill variable, social psychological variable and facility environmental variables, and then verified relevance between safety accidents and each influence variable. As a result, it was verified through ANOVA test of SAS Package Program and $x^2$- test that facility environmental variable would be closely related to the accident. In this regard, this study newly proposes the facility standards of aging friendly facility by supplementing them with contents and guidelines of facility evaluation table as ways to reduce safety related facility of the elderly.

• KIEAE Journal
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• v.15 no.4
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• pp.21-28
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• 2015

Purpose: Although security lights are used to secure pedestrian visibility and safety at nighttime, they can generate light trespass in the neighboring residential space. To prevent this, standards for acceptance limits on vertical illuminance and light pollution by the windows of residential buildings are presented. Method: This study thus representatively selected three types of lamps and, through an evaluation and analysis of the physical and subjective discomfort glare per lamp, proposed a discomfort glare index for each lamp. The evaluation and analysis according to the lamps were conducted through experiments. The variables were the security lights' lamps (NH 100W, MH 70W, LED 50W), installation angles ($0^{\circ}$, $20^{\circ}$), and installation distances (3m, 5m, 7m, 9m). Result: According to the results of the discomfort glare evaluation depending on the angles and distances of the security lights, the following minimum standards are proposed: for NH 100W, a discomfort glare index of 30 and an installation distance of 4m; for MH 70W, a discomfort glare index of 32 and an installation distance of 4m; and, for LED 50W, a discomfort glare index of 31 and an installation distance of 6m, respectively. In addition, this paper recommends the use of MH 70W, when the road width is 4m-6m, and LED 50W, when the road width is over 6m, respectively.