• Journal of The Korean Association For Science Education
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• v.36 no.1
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• pp.75-86
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• 2016

The purpose of the present study is to develop and validate an instrument to assess STEM career motivation. We developed 32 items for 7 constructs (i.e. education experience, career value, academic self-efficacy, career self-efficacy, career interest, parents' support, and career motivation) on STEM career motivation based on Social Cognitive Career Theory (SCCT; Lent et al.,1994). 767 first year high school students participated in this study. The items were validated by Messick's framework (1995). In this study, we examined the validity of items in four aspects (i.e. content, substantive, structural and generalizability of validity). Methodologically, we used Rasch analysis, Exploratory factor analysis, confirmative factor analysis based on structural equation modelling. We confirmed that our instrument with 32 items as valid and reliable for measuring the STEM career motivation. In addition, we tested the STEM career motivation model based on SCCT. Our model explained the data well, suggesting that external factors (education experience and parents' support) and cognitive factors (perception of value, self-efficacy and interest) were significantly related to STEM career motivation.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.1
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• pp.99-108
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• 2001

The study was carried out to evaluate characteristics of inorganic phosphate fractions in cultivating soil with paper mill sludge comport(PMSC). The experiment were conducted in cultivating corn by a pot test. The place of the pot test was a plastic house. The pot size was 1/5000a and PMSC was added at rates of 0, 30, and 100 Mg/ha. The pot experiment was divided to two treatments, one in which corn was cultivated and the other which was not. The items of measurement was pH and inorganic phosphate fractions which were determined for the pot tests for 80 days. The results can be concluded as follows, pH increased depending on the higher rates of PMSC application to the soil during the Pot tests, because calcium content was high and contents of nutrient were high. When the application rates of PMSC were increased, Saloid-P and Fe-P decreased, while Al-P and Ca-P in soil increased during the pot tests. According to the increase of PMSC application rates, the growth and the yield of com significantly increased Such results seem to be associated with the higher nutrient level from PMSC application. Although uptake of phosphorus in corn decreased in the corn with increased application of the PMSC, phosphate deficiency didn't appear in the pot test.

• Journal of the Korean Wood Science and Technology
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• v.38 no.1
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• pp.17-26
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• 2010

Recently, yellow poplar (Liriodendron tulipifera L.) is getting attention in Korea due to the fast growing and high yield and quality of lumber. But, it is thought that the color difference between heartwood and sapwood may restrict the practical use of it. This study was aimed to enhance the value of yellow poplar lumber by the color control using high temperature heat-treatment, which had been tried for domestic cedar (Kim et al., 2009). The material properties including surface color of yellow poplar lumber were evaluated according to heat treatment conditions. The difference of color between sapwood and heartwood could be reduced by heat treatment at a temperature about $200^{\circ}C$. Long heating time was more effective in reducing the difference. The Equilibrium Moisture Content (EMC) of heat-treated wood was as low as 50 percent of the control. The result obviously indicates that heat-treated wood is more dimensionally stable in the change of moisture condition. The durability against wood rotting fungi also increased by the heat-treated, but it was not so effective as the case of cedar. The changes of mechanical properties of heat-treated yellow poplar were very similar to that of heat-treated cedar. In order to develop new use of heat-treated yellow poplar, the changes of mechanical properties should be considered. There were no significant changes in microscopic structure which may cause changes in mechanical properties. Further study of heat-treated wood is needed to scrutinize the causes of changes of material properties.

• Journal of the Mineralogical Society of Korea
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• v.16 no.4
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• pp.321-331
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• 2003

We researched the variation of mineral composition with depth and the Cu adsorption behavior of Hwangto in the Okjong area, Hadong. The 4 Hwangto samples were collected from depth 10 cm, 25 cm, 2∼3 m and under 3 m from surface, and analyzed using the X­ray Diffractometer. The Hwangto samples were mostly composed of clay minerals such as kaolinite and halloysite. Two samples from 10 cm and 25 cm contained Fe or Al hydroxide minerals, for example goethite or gibbsite. As depth increases, the content of quartz decreases but that of kaolinite increases. The amount of Cu removal was rapidly rised from pH 4, and reached about 90％ at pH 6 and above 90％ at pH 7. It is regarded that the trend of Cu removal was affected by the difference in mineral composition. It was relatively well matched between experimental value and calculated value by MINTEQA2 program in the case of high Cu concentration. From this study the precipitation has important role for the removal of Cu ions, particularly in the case of high Cu concentration. However, it was discord between experimental value and calculated one in the dilute concentration circumstances. The reason may be the mistake in parameters, insufficient reaction time, and inadequate consideration of reaction site in mineral surface.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.6
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• pp.606-615
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• 2010

This study aims to identify the characteristics of soil in Mongolia, one of the major Asian dust sources that influence the Korean Peninsula. Soil particle size was analyzed and the result shows that sand (57.5~97.3%) was identified prominently in most regions, followed by silt (2.5~34.7%) and clay (0.0~7.8%). Soil pH of the covered regions were in the range 7.1~10.1, either weak alkaline or strong alkaline. Analysis of ion species in the soil samples exhibited that $Na^+$ ($91.9\;mg\;kg^{-1}$), $Cl^-$ ($65.9\;mg\;kg^{-1}$), and $Ca^{2+}$ ($53.5\;mg\;kg^{-1}$) were detected more in the soil than other species such as ${SO_4}^{2-}$ ($19.2\;mg\;kg^{-1}$), ${NO_3}^-$ ($46.6\;mg\;kg^{-1}$), ${NH_4}^+$ ($3.9\;mg\;kg^{-1}$), $K^+$ ($22.0\;mg\;kg^{-1}$), and $Mg^{2+}$ ($10.2\;mg\;kg^{-1}$). As for heavy metal content in the soil, concentrations of soil-borne metals including Fe, Al, Ca, Mg, and K tended to be high, while metals that come from manmade sources Pb, Cd, Cr, V, and Ni were remarkably low. The concentration of organic carbon (OC) was relatively high at $15.9\;{\mu}g\;mg^{-1}$, while elemental carbon (EC), directly released in the process of fossil fuel combustion, was not detected at all or found in very small amounts. The result indicates that pollution from manmade sources scarcely occurred. The analysis results from this study may contribute to improving modeling accuracy by providing input data for Asian dust prediction models, and be used as base data for determining the process of physiochemical transformation of Asian dust during long-range transport.

• Korean Journal of Psychosomatic Medicine
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• v.11 no.1
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• pp.77-88
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• 2003

Objectives: The purpose of this study was to compare reliability and validity of three Korean versions of the 20-item Toronto Alexithymia scale and to confirm the most reliable and validated Korean translation of the 20-item Toronto Alexithymia Scale for both clinical and research purpose in Korea. The first one was a Korean version of the 20-Item Toronto Alexithymia Scale developed by Lee YH et al in 1996 which was designated as TAS-20K(1996) in this study. This scale had a problem with one item due to the cultural difference regarding the word 'analyzing' between western culture and Korean culture. The second one was the revised version of TAS-20K(1996) on that point by Lee YH et al in 1996 without validation which was designated as TAS-20K(2003) in this study. The third one was a 23-item Korean version developed by Sin HG and Won HT in 1997, which was somewhat different from the 20-item Toronto Alexithymia Scale(TAS-20) in the number of total item, the content of some items and the scoring method. This scale was designated as S-TAS here. Methods: 408 medical students were tested with one scale composed of all the different items randomly arranged from the three versions. We evaluated goodness-of-fit and Cronbach $\alpha$ coefficients of three scales for reliability. We used confirmatory factor analysis to compare validity. Results: TAS-20K(2003) showed that it had better internal consistency than TAS-20K(1996), which implied that the cultural difference should be considered in the Korean translation. Both TAS-20K(2003) and S-TAS replicated three-factor structures and had adequacy of fit, good internal consistency and acceptable validity. However, S-TAS had one item with poor item-factor correlation and didn't show high correlation between item 2 and factor 1 as before in 1997. Conclusion: Although S-TAS had added 3 items and changed the content of two items, it didn't show better reliability and validity than TAS-20K(2003). Therefore it is proposed to use TAS-20K (2003) as the Korean version of the 20-item Toronto Alexithymia Scale(TAS-20K) for international communication of results of Alexithymia research. It has good internal consistency and validity and maintains original items, the same construct and scoring method as the 20-item Toronto Alexithymia Scale.

• Journal of the East Asian Society of Dietary Life
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• v.17 no.6
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• pp.860-875
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• 2007

The purpose of this study was to investigate the seasonal variation in the mineral contents of fruits and vegetables available all the year -round. We analyzed Na, K, Mg, Ca, P, Fe Cr, Mn, Cu, Zn, Se, and Al concentrations by ICP-mass in 4 fruits and 17 vegetables items which are frequently consumed in Koreans. For Na content, fall apples showed the highest levels among 4 seasons, but fall tangerines contained the lowest amount of Na among the four seasons. Among the vegetables, the spinach, carrots, and lettuce contained relatively high amounts of Na. The K contents of cucumbers, cabbage, and zucchini were higher in the fall than in the other seasons. For Ca and Fe contents, spring strawberries, fall pears, and fall cabbage had the highest levels. The Cr contents of the apples were higher in the fall and winter than those were in the spring and summer. The strawberries contained their highest amounts of Cr, Mn, and Cu in the spring. The above results showed there are seasonal differences in the mineral contents of fruits and vegetables. Additionally, the fruits and vegetables tended to contain more minerals in the season they were harvested. Therefore, it is recommended to consume those fruits and vegetables during their harvest season.

• Clean Technology
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• v.29 no.3
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• pp.193-199
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• 2023

Biomass has been used to secure renewable energy certificates (REC) in domestic and overseas coal-fired power plants. In recent years, biofuel has been diversified from traditional wood pellets to non-woody biomass. Non-woody biomass has a higher content of alkaline metals such as K and Na than wood-based biomass, resulting in a lower melting point and an increase in slagging on boiler tubes, which reduces boiler efficiency. This study analyzed the effect of kaolin, an additive commonly used to increase melting points, on biomass co-firing to coal through thermochemical equilibrium calculations. In a previous experiment on biomass co-firing to coal conducted at 80 kW_th, it was interpreted that the use of kaolin actually increased the amount of fouling. In this study, analysis showed that when kaolin was added, aluminosilicate compounds were generated due to Al₂O₃, which is abundant in coal, and mullite was formed. Thus, it was confirmed that the amount of slag increased when more kaolin was used. Further analysis was conducted by increasing the biomass co-firing rate from 0% to 100% at 10% intervals, and the results showed non-linear liquid slag generation. As a result, it was found that the least amount of liquid slag was generated when the biomass co-firing rate was between 50 and 60%. The phase diagram analysis showed that high melting point compounds such as leucite and feldspar were most abundantly generated under these conditions.

• Journal of the Mineralogical Society of Korea
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• v.16 no.2
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• pp.135-149
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• 2003

Domestic zeolite ores are mostly composed of Ca-type clinoptilolite, accompanying a little amounts of mordenite. However, other types of zeolite ores rich in ferrierite, heulandite, or mordenite are less commonly found. Based on the quantitative XRD analysis, zeolite contents are determined to be nearly 50∼90 wt%. Impurities (mostly ＞ 10 wt%) in the zeolite ores chiefly consist of quartz, feldspar, smectite, and opal-CT. The determined CEC values ($CEC_{AA}$ ) of powdery samples (grain size: < 125 $\mu\textrm{m}$) of zeolite ores by the Ammonium Acetate method are mostly higher than 100 meq/100 g. Some zeolites from the Guryongpo area, corresponding to the clinoptilolite ore, are measured to be dominantly high in CEC values ranging 170∼190 meq/100 g. Cation exchange property of the zeolite ores varies greatly depending on the types or zeolite species present in the ores. Despite of the lower grade in zeolite content, the $CEC_{AA}$ of ferrierite ore is comparatively high. Compared to this, the $CEC_{AA }$ of heulandite ore is very low, though the zeolite ore exhibits the highest grade ranging up to about 90 wt%. In addition, the CEC values calculated theoretically from the framework composition of clinoptilolite-heulandite series are not consistent with those determined by the cation exchage experiment. The measured $CEC_{AA}$ of clinoptilolite ores are generally higher than those of heulandite ores. This may be due to the higher Ca abundance in exchangeable cation composition and the presence of probable stacking faults in heulandite. The variation of $CEC_{CEC}$ is roughly proportional, though not strictly compatible, to the zeolite contents in clinoptilolite ores. It seems to be caused by the fact that the $CEC_{AA}$ of clinoptilolite locally varies depending on crystal-chemical diversity, i. e., the variation in framework composition (Si/Al) and exchangeable cation composition (especially, the contents of Ca and K). In addition, the determined CEC values ($CEC_{MB}$ ) of zeolite ores by the Methylene Blue method are much higher than those calculated from smectite contents. It suggests a probable reaction of Methylene Blue ion ($C_{16}$ $H_{18}$ $N_3$S+) with larger-pore zeolites than clinoptlolite-heulandite series, i.e., ferrierite and mordenite as well as with smectite. This can be supported by the fact that the ferrierite ore accompanying little amount of smectite has the highest value in CE $C_{MB}$ .

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.103-113
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• 1995

To estimate buffer capacity and sensitivity of forest ecosystem to acid rain in Taejon, ionic components of throughfall, stemflow, soil leachate, and open rain in Pinus rigida and Quercus variabilis forest were analysed. The spatial sensitivity based on parent rock and forest type was given by IDRISI of GIS which created imagery conversion from soil and vegetation map. Parent rocks and soils were classified into acidic, sedimentary, metamorphic rock and then subdivided based on $SiO_2$ content. Average pH of vegetation leachate was higher in throughfall but lower in stemflow than open rain and higher in Quercus variabilis forest than in Pinus rigida forest. The flow of $SO{_4}^{2-}$, $NO_3{^-}$ and $Cl^-$ through vegetation leaching(throughfall plus stemflow) into soil were 7.2, 4.3, and 2.5 times, respectively, higher in Pinus rigida forest and 4.4, 2, and 2.5 times, respectively, higher in Quercus variabilis forest than in open field. But the concentration of exchangeable cations was 4.1 times higher in Pinus rigida forest and 4.6 times higher in Quercus variabilis forest than in open field. Average pH of soil leachate was lower than that of throughfall, but higher than that of stemflow. The concentration of exchangeable canons and $Al^{3+}$ in soil leachate were more in Pinus rigida forest than in Quercus variabilis forest and increase signficantly with the increase of acidic deposits. Pinus forest had more deposition and canopy interception of acidic pollutants and more nutrient loss than Quercus forest, and Quercus forest had more cation exchange and proton consumption and than consequently had less nutrient loss and better buffer capacity than Pinus forest. The 69% of forest soils was distributed on acidic rock, 25% of it on metamorphic rock, and 6% of it on intermediate and basic rock. Acidic rock residuals which had low very canon exchange capacity and high sensitivity to acid rain occupied a half of total forest land in Taejon area. Therefore forests in Taejon showed high vulnerability to acid rain and will receive much more stress with the increase of acid rain precursors.