• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.2
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• pp.45-50
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• 2004

The field utilization factor (equation omitted) (the mean electric field / the maximum electric field) of standard sphere gaps was calculated by the charge simulation method, taking into account the ground plane and shanks. n changes mainly with g/r and slightly with 1$_1$, 1$_2$ and 1, where D=2r is the sphere diameter, g is the gap length, 1$_1$ and 1$_2$, respectively, are the lengths of the upper and lower shank, and t is the shank diameter. Generally, (equation omitted) increases as 1$_1$,1$_2$ and t each becomes larger. IEC standard 60052(2002) limits t$\leq$0.2D 1$_1$$\geq$1D and prescribes A=1$_2$＋D＋g where A is the height of the spark point on the upper sphere. Therefore, (equation omitted) is the largest when A=9D and the smallest when A=3D. The simple equation of a straight line, (equation omitted)=1- (g/3r), can generally be used as a representative value of (equation omitted) for a wide variety of sphere diameters that are permitted by the IEC standard. The maximum electric field E$_{m}$ at sparkover of standard air gaps has also been calculated by the relation E$_{m}$=V/(equation omitted)g). E$_{m}$ describes a U-curve for g/r, up to the sphere diameter of 1 m. Moreover, for 1.5-m and 2-m diameters and especially .for negative polarity, sparkover voltages have been calculated by integration of the ionization index.index.

• Journal of Korea Technology Innovation Society
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• v.8 no.1
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• pp.277-295
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• 2005

The objective of the study is to verify the discriminatory power of valuation indexes in predicting IT small and medium sized manufacturing firms' going concern or firms' failure. The result of the study is expected to be useful in loan evaluation, investment decision, internal management decision making and business improvement. The results of study is as follows. First, we find that at least six valuation index elements are significant ex-ante variable which are discriminating between firms' going concern and firms' failure in IT small and medium sized manufacturing firms in various analysis' results. Second, these index elements are composed of 2 indexes-the ability of technology R&D, the efficient strategy of market penetration and six index elements explain 46% of the total variance. This explainable power of these indexed is similar to that of the existing 16 index elements. Finally, we find that the most important success factor of IT small and medium sized manufacturing firms are the ability of technology R&D and the efficient strategy of market penetration.

• Explosives and Blasting
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• v.15 no.3
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• pp.20-32
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• 1997

The pressure-time profile of the explosion gases can be controlled fot the use of cartridge explosives with two techniques Known as Decoupling and Spacing the charges. Decoupling consists in leaving and empty space between the explosive column and wall of the blast hole. Four different decoupling index, 1.4, 1.8, 2.34, 3.0 are selected in this field study. The level of ground vibrations with each decoupling index are measured and the empirical particle vibrations with each decoupling index are measured and the empirical particle velocity equation from these data was obtained. The condition of new cracks at blast hole are also examined. As the decoupling index in increased, the level of the blast vibration is decreased,. But the cracks in rock masses are efficiently formed to remove the broken rock. The vibration constant associated with a given site $K=1564.5(D.I)^{-1.3233}$ in terms of D.I(decopling index).

• Journal of applied mathematics & informatics
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• v.27 no.1_2
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• pp.267-273
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• 2009

A representation for the Drazin inverse of an arbitrary square matrix in terms of the eigenprojection was established by Rothblum [SIAM J. Appl. Math., 31(1976) :646-648]. In this paper perturbation results based on the representation for the Darzin inverse $A^D\;=\;(A-X)^{-1}(I-X)$ are developed. Norm estimates of $\parallel(A+E)^D-A^D\parallel_2/\parallel A^D\parallel_2$ and $\parallel(A+E)^#-A^D\parallel_2/\parallel A^D\parallel_2$ are derived when IIEI12 is small.

• Environmental Engineering Research
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• v.23 no.1
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• pp.21-27
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• 2018

Air pollution index (API) is used in Mainland China and includes only $SO_2$, $NO_2$ and $PM_{10}$. In 2016, air quality index (AQI) replaced API. AQI contains three more air pollutants (CO, $O_3$ and $PM_{2.5}$). Both the indices emphasize on the effect of a single pollutant, whereas the contributions of all other pollutants are ignored. Therefore, in the present work, a novel air quality index (NAQI), which emphasizes on all air pollutants, has been introduced for the first time. The results showed that there were 19 d (5.2%) in API, 28 d (7.7%) in AQI and 183 d (50.1%) in NAQI when the indices were more than 100. In API, $PM_{10}$ and $SO_2$ were regarded as the primary pollutants, whereas all five air pollutants in AQI were regarded as primary. Furthermore, four air pollutants (other than the CO) in NAQI were regarded as primary pollutants. $PM_{10}$, as being the primary pollutant, contributed greatly in these air quality indices, and accounted for 51.2% (API), 37.0% (AQI) and 52.6% (NAQI). The results also showed that particulate matter pollution was significantly high in Luzhou, where stricter pollution control measures should be implemented.

• Journal of Korean Society of Forest Science
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• v.113 no.2
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• pp.187-197
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• 2024

In this study, we aimed to identify the factors influencing post-fire mortality in Korean red pine (Pinus densiflora) using Cox's proportional hazards model and analyze the impact of these factors. We monitored the mortality rate of fire-damaged pine trees for seven years after a forest fire. Our survival analysis revealed that the risk of mortality increased with higher values of the delta normalized difference vegetation index (dNDVI), delat normalized burn ratio (dNBR), bark scorch index (BSI), bark scorch height (BSH) and slope. Conversely, the risk of mortality decreased with higher elevation, greater diameter at breast height (DBH), and higher value of delta moisture stress index (dMSI) (p < 0.01). Verification of the proportional hazards assumption for each variable showed that all factors, except slope aspect, were suitable for the model and significantly influenced fire occurrence. Among the variables, BSI caused the greatest change in the survival curves (p < 0.0001). The environmental change factors determined through remote sensing also significantly influenced the survival rates (p < 0.0001). These results will be useful in establishing restoration plans considering the potential mortality risk of Korean red pine after a forest fire.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.78-83
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• 1981

This study was attempted to determine the major weed species occurring in Korean turfgrass, Zoysia japonica Steud. and to evaluate the most effective means for controlling them. More or less 40 weed species were determined to occur in Korean turfgrass. In terms of quantity and frequency of occurrence, Trifolium repens L., Digitaria sanguinalis (L.) Scop., Draba nemorosa var. hebecarpa Lindbl, Erigeron canadensis L., and Cyperus amuricus Max were observed to be the major weeds. Simpson's index, 0.306 was obtained to be the major weeds. Simpson's index, 0.306 was obtained in the golf course, Jinryang, Gyungsan-gun, meaning that no specific weed species were dominant, but in Kyungpook National University campus, Trifolium repense L. was a single dominant species, indicating Simpson's index, 0.776. The most effective herbicides to control Trifolium repense L. and other broad leaf weeds were MCPP [2-(2-methyl-4-chlorophenoxy) propionic acid), followed by 2,4-D (2,4-dichlolophenoxy acetic acid). Increased rates of both herbicides increased markedly their effectivity against weeds, with very slight injury against turfgrass. MCPP at 2.8 kg(a.i.)/ha gave excellent control without any injury and 2,4-D at 1.0 kg(a.i.)/ha.

• Journal of Korea Foundry Society
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• v.23 no.5
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• pp.235-243
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• 2003

The collapsibility of sodium silicate-bonded sands mixed with the L.D converter slag powder to form a hardener were investigated. Five to six percent sodium silicate on the basis of silica sand and 30-40% L.D converter slag powder on the basis of sodium silicate, were mixed and the compressive strength, surface stability index(SSI), bench time, retained strength of the standard sand specimens were measured. The properties were similar to those of general inorganic bonded self-setting molds. The compressive strength and surface stability index were increased and the retained strength and bench time were decreased with increased amount of the L.D converter slag powder. The retained strength of sodium silicate-bonded self-setting molds with the L.D converter slag powder were decreased than $CO_2$ sand molds. The collapsibility of sodium silicate-bonded self-setting molds with the L.D converter slag powder were superior in comparison with $CO_2$ sand molds. The L.D converter slag powder could be used as hardener and collapse agent for the sodium silicate-bonded self-setting molds.

• Korean Journal of Community Nutrition
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• v.9 no.4
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• pp.528-535
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• 2004

In order to observe the effects of resistant starches on human glycemic response, nine female university students were investigated using cellulose (CED), resistant starch 3 (RS3D) and resistant starch 4 (RS4D) diets. Each woman's blood sugar and insulin, triacylglycerol and free fatty in plasma concentration were measured at fasting state, then 15, 30, 45, 60, 75, 90 and 120 minute after each test diet feeding. Glycemic indices of the Cellulose diet (CED: 57.9 $\pm3.00$), the Resistant starch 3 diet (RS3D: 52.6 $\pm7.9$) and the Resistant starch 4 diet (RS4D: 52.9 $\pm10.2$) were similar to each other, but they were significantly lower in comparison with those of white wheat bread diet (WWBD: 100). Insulinemic indices of the CED (49.8 $\pm8.2$), RS3D (50.0 $\pm7.3$) and RS4D (72.4 $\pm7.7$) were significantly lower in comparison with the white wheat bread diet (WWBD: 100), but among the dietary fiber diets, the insulinemic index of RS4D was significantly higher than the CED and the RS3D. Plasma triacylglycerol contents of the CED, RS3D and RS4D including WWBD showed gradual increase in tendency after lowering in early stage of each test diet feeding, but not significantly different in each dietary fiber added diet. Plasma free fatty acid contents of the CED, RS3D and RS4D including WWBD showed gradual decrease in tendency after each test diet feeding, but not significantly different by each dietary fiber added diet. In above results, we speculate that resistant starch 3 controls rapid elevation of blood sugar by delaying intestinal digestion and absorption of cellulose, but the result appears to be different from RS4 in comparison. Thus, RS3 intakes may contribute to the diet therapy of diabetic humans, but more studies on RS4 is needed in the future. (Korean J Community Nutrition 9(4): 528∼535, 2004)

• Journal of the korean academy of Pediatric Dentistry
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• v.8 no.1
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• pp.103-117
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• 1981

The data about dental caries obtained from 1438 preschool children (male 797, female 641) in Seoul aged from 3 to 6 were analyzed by their sexes, ages, jaws and teeth surfaces. The results were as follows. 1. dmf rate : 92.63% 2. dmft index : 6.06 dmft rate 30.81 % dmfs index : 11.82 dmfs rate 12.02 % 3. d,m & f rate d rate: 79.45% m rate: 8.15% f rate : 12.40 % 4. dft index : 5.94 5. The order of caries susceptible tooth 1. Lower deciduous 2nd molar 2. Lower deciduous 1st molar 3. Upper deciduous 2nd molar 4. Upper deciduous lateral incisor 5. Upper deciduous cental incisor 6. Upper deciduous lateral incisor 7. Lower deciduous canine 8. Upper deciduous canine 9. Lower deciduous central incisor 10. Lower deciduous lateral incisor 6. Predilection sites of each tooth A) Deciduous central incisor ; Max. : Mesial cavity Mand. : Mesio-distal cavity B) Decidous lateral incisor ; Max. : Mesial cavity Mand. : Distal cavity=Mesial cavity C) Deciduous canine; Max. : Labial cavity Mand. : Distal cavity D) Decidous 1st molar ; Max. : Disto-occlusal cavity Mand.: Disto-occlusal cavity E) Deciduous 2nd molar ; Max. : Linguo-occlusal cavity Mand.: Occlusal cavity 7. All the values in caries criteria in 1981 were somewhat lower than in 1968, but m & f rate were increased.