• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2008년도 추계학술대회
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• pp.275-285
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• 2008

National technical qualification does not recognised degree of working-career in labor market and an industrial field situation. National qualification is supply to nurture expert manpower and accomplish of self-development and a duty accomplishment ability improvement at a side of personal. So, This study is purposed to find that a method for recognition of working-career on the national technical qualification system. According to, this study is designed to questionnaire with BSC(Balaced ScoreCard), SEM(Structure Equation Model) with the delphi method, and is analysed using the AMOS 7.0 program package. Finally, This study is suggested growing to qualification standard for an examination a degree of master craftsman only under the change of national qualification systematization as a standard to operation and control.

• 대한한의학방제학회지
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• 제16권2호
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• pp.171-182
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• 2008

The aqueous extract of Schisandra chinensis, Evodia rutaecarpa and meal (SEM-Ex) has been traditionally used in the Oriental countries as an astringent. However, little is known about the effects of aqueous extract of SEM-Ex on dextran-sulfate sodium (DSS)-induced colitis in mice. In this study, we investigated the protective effects of SEM-Ex on DSS-induced colitis in mice. An experimental colitis was induced by daily treatment with 5% DSS. SEM-Ex was orally administered from day 2 of DSS treatment in the different dose (10-50 mg/kg body weight). SEM-Ex reduced significantly clinical sign of DSS-induced colitis, including body weight loss, shorten colon length, increased disease activity index (DAI), and histological colon injury. Moreover, SEM-Ex suppressed significantly not only the serum haptoglobin levels and the activities of myeloperoxidase (MPO), but also the colon tissue expression levels of monocyte chemoattractant protein-1 (MCP-1) in DSS-induced mice. In contrast, SEM-Ex increased significantly the colon tissue expression levels of granular colony stimulating factor (G-CSF) well known as anti-inflammatory cytokine. These results suggest that SEM-Ex administration could reduce significantly the clinical signs and regulate of chemokine and anti-inflammatory cytokine in DSS-induced model mice. Therefore, these properties may contribute to the strong anti-ulcerative colitis (UC) response effect of SEM-Ex.

• Structural Engineering and Mechanics
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• 제65권3호
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• pp.263-274
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• 2018

In this study, we propose a frequency domain spectral element method (SEM) for the vibration analysis of a multi-span beam subjected to a moving point force. This study is an extension of the authors' previous study for a single-span beam subjected to a moving point force, where the two-element model-based SEM was applied. In this study, each span of a multi-span beam is represented by the Timoshenko beam model and the moving point force is transformed into the frequency domain as a series of each stationary point force distributed on the multi-span beam. The span at which a stationary point force is located is represented by two-element model, but all other spans are represented by one-element models. The vibration responses to a moving point force are obtained by superposing all individual vibration responses generated by each stationary point force. The high accuracy and computational efficiency of the proposed SEM are verified by comparing the solutions by SEM with exact analytical solutions by the integral transform method (ITM) as well as the solutions by the finite element method (FEM).

• 한국도로학회논문집
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• 제14권6호
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• pp.121-129
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• 2012

PURPOSES : Traffic accidents at intersections have been increased annually so that it is required to examine the causations to reduce the accidents. However, the current existing accident models were developed mainly with non-linear regression models such as Poisson methods. These non-linear regression methods lack to reveal complicated causations for traffic accidents, though they are right choices to study randomness and non-linearity of accidents. Therefore, to reveal the complicated causations of traffic accidents, this study used structural equation methods(SEM). METHODS : SEM used in this study is a statistical technique for estimating causal relations using a combination of statistical data and qualitative causal assumptions. SEM allow exploratory modeling, meaning they are suited to theory development. The method is tested against the obtained measurement data to determine how well the model fits the data. Among the strengths of SEM is the ability to construct latent variables: variables which are not measured directly, but are estimated in the model from several measured variables. This allows the modeler to explicitly capture the unreliability of measurement in the model, which allows the structural relations between latent variables to be accurately estimated. RESULTS : The study results showed that causal factors could be grouped into 3. Factor 1 includes traffic variables, and Factor 2 contains turning traffic variables. Factor 3 consists of other road element variables such as speed limits or signal cycles. CONCLUSIONS : Non-linear regression models can be used to develop accident predictions models. However, they lack to estimate causal factors, because they select only few significant variables to raise the accuracy of the model performance. Compared to the regressions, SEM has merits to estimate causal factors affecting accidents, because it allows the structural relations between latent variables. Therefore, this study used SEM to estimate causal factors affecting accident at urban signalized intersections.

• Mass Spectrometry Letters
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• 제7권3호
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• pp.64-68
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• 2016

Scanning electron microscopy combined with thermal ionization mass spectrometry (SEM-TIMS) was used to determine the precise isotope ratios of ultra-trace levels of uranium contained in individual microparticles. An advanced multiple ion counter system consisting of three secondary ion multipliers and two compact discrete dynodes was used for complete simultaneous ion detection. For verification purposes, using TIMS with complete simultaneous measurement, isotopes were analyzed in 5 pg of uranium of a certified reference material. A microprobe in the SEM was used to transfer individual particles from a NUSIMEP-7 sample to TIMS filaments, which were then subjected to SEM-TIMS and complete simultaneous measurement. The excellent agreement in the resulting uranium isotope ratios with the certified NUSIMEP-7 values shows the validity of SEM-TIMS with complete simultaneous measurement for the analysis of uranium isotopes in individual particles. Further experimental study required for investigation of simultaneous measurement using the advanced multiple ion counter system is presented.

• 대한인간공학회지
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• 제22권2호
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• pp.45-56
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• 2003

The purpose of this study is to develop the model including multiple causal relationship between factors to evaluate overall user satisfaction and develop an objective method to quantify the impacts and scores of each qualitative factors on overall user satisfaction using Structural Equation Model(SEM) and also test the feasibility to construct a comprehensive website evaluation model including qualitative and quantitative factors. The SEM model used 2 qualitative factors of usability and esthetic factors for the evaluation factors of user satisfaction and select 4 attributes of each factors using factor analysis. 3 shopping mall sites were evaluated to construct the SEM model, and 155 subjects participated the website evaluation using the walk-through and face-to-face survey method. Analysis results showed that the SEM model was statistically significant for all the 3 websites evaluated. Both the usability and esthetic factors showed significant effects to user satisfaction of websites and have positive correlation. The user satisfaction was more effected by the usability factor than esthetic factors, and the simplification and harmonization were the most critical attributes of the usability and esthetic factors.

• 산경연구논집
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• 제10권5호
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• pp.7-20
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• 2019

Purpose - This study provides appropriate procedures for EFA to help researchers conduct empirical studies by using PLS-SEM. Research design, data, and methodology - This study addresses the absolute and relative sample size criteria, sampling adequacy, factor extraction models, factor rotation methods, the criterion for the number of factors to retain, interpretation of results, and reporting information. Results - The factor analysis procedure for PLS-SEM consists of the following five stages. First, it is important to look at whether both the Bartlett test of sphericity and the KMO MSA meet the qualitative criteria. Second, PAF is a better choice of methodology. Third, an oblique technique is a suitable method for PLS-SEM. Fourth, a combined approach is strongly recommended to factor retention. PA should be used at the onset. Next, it is recommended using the K1 criterion. In addition, it is necessary to extract factors that increase the total variance explanatory power through the PVA-FS. Finally, it is appropriate to select an item with a factor loading into 0.5 or higher and a communality of 0.5. Conclusions - It is expected that the accurate factor analysis processed for PLS-SEM as previously presented will help us extract more precise factors of the structural model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.604-607
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• 2003

This study investigates the micro-cutting of cemented carbides using PCD(polycrystalline diamond) and PCBN(polycrystalline cubic boron nitride) cutting tools are performed with SEM direct observation method. The purpose of this study is to make clear the cutting mechanism of cemented carbides and the fracture of WC particles at the plastic deformation zone in orthogonal micro-cutting. And also to achieve systematic understanding, the effect of machining parameter on chip formation and machined surface was investigated, including cutting speed. depth of cut and various tool rake angle.

• 한국정밀공학회지
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• 제20권10호
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• pp.74-81
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• 2003

This paper describes that the micro-cutting of WC-Co using PCD (Polycrystalline Diamond) and PcBN (Polycrystalline Cubic Boron Nitride) cutting tools are performed with SEM(Scanning Electron Microscope) direct observation method. The purpose of this study is to present reasonable cutting conditions to obtain precise finished surface and machining efficiency. Summary of the results are shown below: (1) The thrust cutting forces tend to increase more than the principal forces as the depth of cut and the cuttlllg speed are increased preferably on orthogonal microcutting. (2) The tool wear in the flank face was formed larger than that in the rake face on orthogonal micro cutting. (3) The wear appearance for PCD tools is abraded by hard WC particles of the work materials, which lead diamond grain to be detached from the bond.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2015년도 학술발표회
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• pp.180-180
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• 2015

Weather radar has been widely used in measuring precipitation and discharge and predicting flood risks. The radar rainfall estimate has one of the essential problems in terms of uncertainty and accuracy. Previous study analyzed radar errors to reduce its uncertainty or to improve its accuracy. Furthermore, a recent analyzed the effect of radar error on rainfall-runoff using spatial error model (SEM). SEM appropriately reproduced radar error including spatial correlation. Since the SEM does not take the time dependence into account, its time variability was not properly investigated. Therefore, in the current study, we extend the SEM including time dependence as well as spatial dependence, named after Spatial-Temporal Error Model (STEM). Radar rainfall events generated with STEM were tested so that the peak runoff from the response of a basin could be investigated according to dependent error. The Nam River basin, South Korea, was employed to illustrate the effects of STEM on runoff peak flow.