• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.3 no.2
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• pp.194-203
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• 1993

Quality Control programs for industrial hygiene laboratory have successfully been operated since the 1st round was initiated in April 1992. Three rounds have been completed. Overall analytical performance of participants was improved through a subsquent round. The first round had a large variation among analytical results of all participants, 26.34%~504.22% of coefficient of variation. But the variation of analytical performance in the 2nd and 3rd rounds decreased to 40.42%~52.55% and 10.74%~20.98%, respectively. The difference of analytical performance among participants was decreased by operation of subsquent round. By distribution of Running Performance Index (RPI), over 50% of participants belongs to Category 3 in the first round. The average percentage of participants assigned to Category 3 in the 2nd and 3rd round was decreased to 37.2%. A definite analytical performance improvement of participants seems to be obtained. "A" and "B" group have more participants assigned to Category 3 than those of "C" group through the distribution of RPI by group divided to similar participant. By the distribution of RPI all participants, the percent of participant being over 200 RPI in the 1st round was 43%~52%, but decreased to 9%~29% and 9%~27%, in the 2nd and 3rd round, respectively. These results mentioned above indicate that the analytical performance of all participants have been improved by subsquent Quality Control Program although newcomers joined and a few participants droped out. But, there are some participants with poor analytical performance. Industrial Health Research Institute (IHRI) will offer service such as education, communication and visitation to them, and improve quality of their analytical performance in the future.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2661-2669
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• 2010

In this study, a finite element formulation based first-order shear deformation theory is developed for non-linear behaviors of laminated composite plates containing matrix cracking. The multi-directional stiffness degradation is developed for adopting the stiffness variation induced from matrix cracking, which is proposed by Duan and Yao. The matrix cracking can be expressed in terms of the variation of material properties, such as Young's modulus, shear modulus and Possion ratio of plates, and sequently it is possible to predict the variation of the local stiffness. Using the assumed natural strain method, the present shell element generates neither membrane nor shear locking behavior. Numerical examples demonstrate that the present element behaves quite satisfactorily either for the linear or geometrical nonlinear analysis of laminated composite plates. The results of laminated composite plates with matrix cracking may be the benchmark test for the non-linear analysis of damaged laminated composite plates.

• Asian Journal of Turfgrass Science
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• v.10 no.1
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• pp.1-11
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• 1996

Fifty accessions in Zoysia species and forty-one hybrid lines were evaluated in order to detect analyze the genectic variation of Zoysiagrasses and to obtain the basic information for breeding. 1.Plant height ranged from 13 to 34.5cm, leaf length from 7 to 26cm, leaf width from 2 to 7mm, and first leaf height from 1.1 to 8.5cm 2. The correlations among plant height, leaf length and first-leaf height were high, but leaf Width was correlated only With leaf length. 3. Stolon length was varied from 10 to 108cm, number of stolons from 12 to 53, internode length from 2 to 6.1cm and coverage percentage from 10 to 90%. 4.There were correlation among stolen length, number of stolons, internode length and coverage percentage except between stolen and internode length. 5.M1J and MC2 showed the highest level in stolen length, number of stolons and coverage percentage. Therefore they will be the best breeding materials for the purpose of fast covering. 6.According to the analysis on October 26, 1995, yellow color-change rate of leaves ranged from 5 to 85%, red color-change from 0 to 75% and sum of yellow and red change from 20 to 95%. Speciallty M2M1 and FL-41 kept green color untill early December, indicating that they had the late dormancy. 7. Visual assessment of stolon length and number of stolons, showed similar tendency With actually measured data. 8. Shoot density was very high in M2M1 and S2, and showed negative correlation with leaf width. 9. It is known in Korea that the darker green color of lawngrass is, the better it looks. There were 11 lines with dark green color leaves such as J 85-10, Meyer in Z. japonira, one asacession in Z. matrella and M2M1, M2S8, JM2, 55C2 in hybrid lines.

• Asia-Pacific Journal of Business
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• v.11 no.3
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• pp.199-215
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• 2020

Purpose - This article tries to test if the conditional consumption capital asset pricing model (CCAPM) with bank credit for household as a conditional variable can explain the cross-sectional variation of stock returns in Korea. The performance of conditional CCAPM is compared to that of multifactor asset pricing models based on Arbitrage Pricing Theory. Design/methodology/approach - This paper extends the simple CCAPM to the conditional version of CCAPM by using bank credit for household as conditioning information. By employing KOSPI and KOSDAQ stocks as test assets from the second quarter of 2003 to the first quarter of 2018, this paper estimates risk premiums of conditional CCAPM and a variety of multifactor linear models such as Fama-French three and five-factor models. The significance of risk factors and the adjusted coefficient of determination are the basis for the comparison in models' performances. Findings - First, the paper finds that conditional CCAPM with bank credit performs as well as the multifactor linear models from Arbitrage Pricing theory on 25 test assets sorted by size and book-to-market. When using long-term consumption growth, the conditional CCAPM explains the cross-sectional variation of stock returns far better than multifactor models. Not only that, although the performances of multifactor models decrease on 75 test assets, conditional CCAPM's performance is well maintained. Research implications or Originality - This paper proposes bank credit for household as a conditional variable for CCAPM. This enables CCAPM, one of the most famous economic asset pricing models, to conform with the empirical data. In light of this, we can now explain the cross-sectional variation of stock returns from an economic perspective: Asset's riskiness is determined by its correlation with consumption growth conditional on bank credit for household.

• Structural Engineering and Mechanics
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• v.70 no.5
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• pp.551-562
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• 2019

In the present study, a suitable mathematical model considering parabolic transverse shear strains for dynamic analysis of laminated composite skew plates under different types of impulse and spatial loads was presented for the first time. The proposed mathematical model satisfies zero transverse shear strain at the top and bottom of the plate. On the basis of the cubic variation of thickness coordinate in in-plane displacement fields of the present mathematical model, a 2D finite element (FE) model was developed including skew transformations in the mathematical model. No shear correction factor is required in the present formulation and damping effect was also incorporated. This is the first FE implementation considering a cubic variation of thickness coordinate in in-plane displacement fields including skew transformations to solve the forced vibration problem of composite skew plates. The effect of transverse shear and rotary inertia was incorporated in the present model. The Newmark-${\beta}$ scheme was adapted to perform time integration from step to step. The $C^0$ FE formulation was implemented to overcome the problem of $C^1$ continuity associated with the cubic variation of thickness coordinate in in-plane displacement fields. The numerical studies showed that the present 2D FE model predicts the result close to the analytical results. Many new results varying different parameter such as skew angles, boundary conditions, etc. were presented.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.287-295
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• 2022

Citrus tristeza virus (CTV) is efficiently transmitted in a semi-persistent manner by the brown citrus aphid (Toxoptera citricida (Kirkaldy)). Currently, the most sensitive method for detecting plant viruses in insect vectors is reverse-transcription quantitative polymerase chain reaction (RT-qPCR). In this study, the elongation factor-1 alpha (EF-1α) gene and acidic p0 ribosomal protein (RPAP0) gene were confirmed to be suitable reference genes for RT-qPCR normalization in viruliferous T. citricida aphids using the geNorm, NormFinder, and BestKeeper tools. Then the relative CTV titer in aphids (T. citricida) at different post-acquisition feeding times on healthy plants was quantified by RT-qPCR using EF-1α and RPAP0 as reference genes. The relative CTV titer retained in the aphids gradually decreased with increasing feeding time. During the first 0.5 h of feeding time on healthy plants, the remaining CTV titer in aphids showed about 80% rapid loss for the highly transmissible isolate CT11A and 40% loss for the poorly transmissible isolate CTLJ. The relative CTV titer in aphids during more than 12 h post-acquisition times for CT11A was significantly lower than at the other feeding times, which is similar to the trend found for CTLJ. To our knowledge, this is the first report about the relative titer variation of CTV remaining in T. citricida at different post-acquisition feeding times on healthy plants.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.101-111
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• 2006

Slope stability analysis is a geotechnical engineering problem characterized by many sources of uncertainty. Some of them are connected to the variability of soil properties involved in the analysis. In this paper, a numerical procedure of probabilistic analysis of slope stability is presented based on Spencer's method of slices. The deterministic analysis is extended to a probabilistic approach that accounts fur the uncertainties and spatial variation of the soil parameters. The procedure is based on the first-order reliability method to compute the Hasofer-Lind reliability index and Monte-Carlo Simulation. A probabilistic stability assessment was performed to obtain the variation of failure probability with the variation of soil parameters in homogeneous and layered slopes as an example. The examples give insight into the application of uncertainty treatment to the slope stability and show the impact of the spatial variability of soil properties on the outcome of a probabilistic assessment.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.303-303
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• 2022

The purpose of this study was to evaluate agronomic characteristics and identify the useful traits to utilize the wheat genetic resources for breeding programs by understanding the phenotypic variation among germplasm through multivariate analysis. In this study, a total of 394 wheat accessions were characterized for 15 agronomic traits using the National Agrobiodiversity Center (NAC) descriptor list, of which 31 accessions from 6 species and 363 unidentified accession (Triticum spp.) available at the NAC, Rural Development Administration (RDA), Korea. Growth characteristics such as leaf width, culm length, spike length, spikelet length, solid stemmed, days to heading, days to maturity, grain-filing period, and also seed characteristics such as width, height, area, perimeter, circle, solidity, and germination percent were studied. Among the 15 agronomic characteristics, the germination percent showed the smallest variation between resources (CV = 0.4%), and the spikelet length (CV = 66.5%) showed the highest variation. A strong positive correlation was found between seed traits such as seed height and seed area (r = 0.90), seed height and seed perimeter (r = 0.87) and seed length and width (r = 0.80). Principal component analysis (PCA) was conducted and the first five principal components comprised 76.7% of the total variance. Among the first five PCs, PCI accounted for 28.5% and PC2 for 20.0%. Wheat resources (394) were classified into four clusters based on cluster analysis, consisting of 215 resources(I), 117 resources(II), 48 resources(III), and 14 resources(IV). Among the clusters, the resources belonging to Cluster III showed the lowest seed width, height, area, and perimeter characteristics compared to other clusters. The wheat resources belonging to cluster IV had small seed width and low germination percent, but took longer to form heads and mature than resources in other clusters. These results will serve as the basis for further genetic diversity studies, and important agronomic characteristics will be used for improving wheat, including developing high-yielding and resistant varieties to biotic and abiotic stresses via breeding programs.

• The korean journal of orthodontics
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• v.17 no.2
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• pp.311-320
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• 1987

The purpose of this study was to investigate the growth changes of maxilla and mandible and position changes of first permanent molars of growing children The author analyzed the data using cephalometric roentgenogram of 43 boys and 39 girls age of 6 to 11 with normal occlusion The obtained results were as follows 1 The eruption path of maxillary and mandibular first permanent molar superimposed on TM-ANS and mandibular plane shows individual variation 2 There was no correlation between horizontal and vertical changes of maxillary first permanent molar, but positive correlation in mandibular first permanent molar 3 As the eruption, the forward changes of mandibular first permanent molar was significantly greater than that of maxillary first permanent molar 4 As the ages were increased, there were irregular growth changes of maxilla and mandible 5 Growth changes of lower anterior facial height was relatively stable 6 N-S-${\bar{6}}$ was stable after age 7.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.9 no.2
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• pp.73-82
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• 1989

When the flood occurs in the alluvial rivers, the rivers adjust to the flood by means of the mechanism of the river bed variations and its morphological changes to pass that safely, the numerical model was developed to simulate the process of the alluvial river bed variation due to flood wave and carried out by the flood routing for flood wave and the sediment routing for river bed variation. The flood wave, river bed variation, and bed material size distribution may be analysed and predicted by this model. The ability of this model to predict the process of river bed response was proved by the application to the reach from Paldang dam to Indogyo site. In view of the flood analysis considering the sediment process, the effects of river bed variation for the flood routing may be negligible because the river bed variation is smaller than the unsteady flow variation during the same period. By the application of this model, it is shown that, in occurring of sequential flood events, the variation of the river bed and bed material size distribution due to flood wave is more dependent on the first flood event than the latter flood events, and that the river bed variation in this reach of the downstream Han river is dependent on the degradation and the coarsening of bed materials.