• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.375-382
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• 2004

The compressive strength of concrete is used as the most basic and important material Property when reinforced concrete structures are designed. It has become a problem to use this value, however, because the control specimen sizes and shapes are different from every country. In this study, the effect of specimen sizes and shapes on compressive strength of concrete specimens was experimentally investigated based on fracture mechanics. Experiments for the Mode I failure was carried out by using cylinder, cube, and prism specimens. The test results are curve fitted using least square method(LSM) to obtain the new parameters for the modified size effect law(MSEL). The analysis results show that the effect of specimen sizes and shapes on ultimate strength is apparent. In addition, correlations between compressive strengths with size, shape, and casting direction of the specimen are investigated. For cubes and prisms the effect of placing direction on the compressive strength was investigated.

• Journal of The Korean Astronomical Society
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• v.41 no.6
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• pp.157-161
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• 2008

We have estimated the fractal dimension of the molecular clouds associated with the Hii region Sh 156 in the Outer Galaxy. We selected the $^{12}CO$ cube data from the FCRAO CO Survey of the Outer Galaxy. Using a developed code within IRAF, we identified slice-clouds (2-dimensional clouds in velocity-channel maps) with two threshold temperatures to estimate the fractal dimension. With the threshold temperatures of 1.8 K, and 3 K, we identified 317 slice-clouds and 217 slice-clouds, respectively. There seems to be a turn-over location in fractional dimension slope around NP (area; number of pixel) = 40. The fractal dimensions was estimated to be D = $1.5\;{\sim}\;1.53$ for $NP\;{\geq}\;40$, where $P\;{\propto}\;A^{D/2}$ (P is perimeter and A is area), which is slightly larger than other results. The sampling rate (spatial resolution) of observed data must be an important parameter when estimating fractal dimension. Fractal dimension is apparently invariant when varying the threshold temperatures applied to slice-clouds identification.

• Progress in Superconductivity
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• v.7 no.2
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• pp.135-139
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• 2006

We fabricated YBCO coated conductors (CCs) by TFA-MOD process and evaluated microstructure, texture formation, and critical temperature ($T_c$) and current ($I_c$). YBCO precursor solution was synthesized using metal-trifluoroacetates and dip coated on $LaAlO_3$(LAO) substrate. The phase formation and microstructure was characterized by X-ray diffraction and scanning electron microscopy (SEM) and the degree of texture was evaluated by pole-figure analysis. The CC was heat-treated in various calcining temperatures ($370^{\circ}C-460^{\circ}C$) and firing temperatures ($750^{\circ}C-800^{\circ}C$). As fired at $775^{\circ}C$ for 4h, the CC had the highest $T_c$ of 89.5 K and $I_c$ of 40 A/cm-width ($J_c=2.0\;MA/cm^2$). Microstructural observation indicated that the YBCO film was dense and homogeneous and had a strong cube texture without formation of second phase and its in-plane full-width at half-maxima; $5.2^{\circ}$ under optimum condition.

• The Journal of Advanced Prosthodontics
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• v.15 no.5
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• pp.248-258
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• 2023

PURPOSE. This study aims to evaluate the effects of exposure energy on the lateral resolution and mechanical strength of dental zirconia manufactured using digital light processing (DLP). MATERIALS AND METHODS. A zirconia suspension and a custom top-down DLP printer were used for in-office manufacturing. The viscosity of the suspension and uniformity of the exposed light intensity were controlled. Based on the exposure energy dose delivered to each layer, the specimens were classified into three groups: low-energy (LE), medium-energy (ME), and high-energy (HE). For each energy group, a simplified molar cube was used to measure the widths of the outline (X_o and Y_o) and isthmus (X_i and Y_i), and a bar-shaped specimen of the sintered body was tested. A Kruskal-Wallis test for the lateral resolution and one-way analysis of variance for the mechanical strength were performed (α = .05). RESULTS. The zirconia green bodies of the ME group showed better lateral resolution than those of the LE and HE groups (both P < .001). Regarding the flexural strength of the sintered bodies, the ME group had the highest mean value, whereas the LE group had the lowest mean value (both P < .05). The ME group exhibited fewer agglomerates than the LE group, with no distinctive interlayer pores or surface defects. CONCLUSION. Based on these findings, the lateral resolution of the green body and flexural strength of the sintered body of dental zirconia could be affected by the exposure energy dose during DLP. The exposure energy should be optimized when fabricating DLP-based dental zirconia.

• Advances in concrete construction
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• v.16 no.3
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• pp.127-139
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• 2023

In this study, the steel fiber and the polypropylene fiber were used to enhance the mechanical properties of fully recycled coarse aggregate concrete. Natural crushed stone was replaced with recycled coarse aggregate at 100% by volume. The steel fiber and polypropylene fiber were used as additive material by incorporating into the mixture. In this test two parameters were considered: (a) steel fiber volume ratio (i.e., 0%, 1%, 1.5%, 2%), (b) polypropylene fiber volume ratio (i.e., 0%, 0.1%, 0.15%, 0.2%). The results showed that compared with no fiber, the integrity of cubes or cylinders mixed with fibers after failure was better. When the volume ratio of steel fiber was 1~2%, the width of mid-span crack after flexural failure was 5~8 mm. In addition, when the volume ratio of polypropylene fiber was 0.15%, with the increase of steel fiber content, the static elastic modulus and toughness of axial compression first increased and then decreased, and the flexural strength increased, with a range of 6.5%~20.3%. Besides, when the volume ratio of steel fiber was 1.5%, with the increase of polypropylene fiber content, the static elastic modulus decreased, with a range of 7.0%~10.5%. The ratio of axial compression toughness first increased and then decreased, with a range of 2.2%~8.7%. The flexural strength decreased, with a range of 2.7%~12.6%. On the other hand, the calculation formula of static elastic modulus and cube compressive strength of fully recycled coarse aggregate with steel-polypropylene fiber was fitted, and the optimal fiber content within the scope of the test were put forward.

• Journal of Animal Science and Technology
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• v.49 no.5
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• pp.639-646
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• 2007

To evaluate the effect of fiber sources on chewing activity, five sheep were consecutively fed diets containing 45% of a fiber source selected from 7 tested fiber sources of alfalfa hay cube(AHC), corn cob (CC), corn silage(CS), cotton seed hull(CSH), peanut hull(PHL), rice straw(RS) and sugarcane bagasse (SCB). Number of chew showed significantly higher value in CC(p<0.001) then other sources. RS and CC had highest(p<0.01) rumination times of 352 and 367 min/d, respectively. CC also showed the highest number of chew per kg NDF intake(p<0.01), but rumination time per kg NDF intake showed no difference except CSH(p<0.001). These results suggest that chewing activities were greatly affected by the fiber sources, and therefore it should be accounted in the formulation for ruminant feed.

• Journal of Distribution Science
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• v.14 no.3
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• pp.85-91
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• 2016

Purpose - Prior research has suggested that consumers typically prefer to have a larger number of options. However, preference of assortment size may depend on how depleted resources in consumers' mind are. Reduced capacity for self-regulation by resource depletion makes people rely on more intuitive and less effortful decision processing. When they are mentally depleted, people are likely to focus on the choice difficulty from large assortment, which leads to preference for the small assortment when they make a decision. It could be an important question potentially how being in a depleted mode through effortful self-regulation will influence on the evaluation of assortment size. To answer this questioner, we hypothesized that being engaged in self-regulation, as compared with not being engaged in self-regulation, will influence on the evaluation of product assortment size such as attractiveness, difficulty of choice, and anticipated regret. Research design, data, and methodology - In this study, we first manipulated self-regulatory resource availability using a self-regulation task (i.e., instructing participants to solve Sudoku puzzle vs. to solve diagram cube by filling any diagrams that they prefer into cube instead of number) and asked to indicate the difficulty of the tasks available to them ("How much difficulty did you feel when you complete the task?") Next, participants were asked to imagine that they were planning to buy a laptop at one of the two stores (small assortment: 6 options vs. large assortment: 30 options), both offering good quality of products. After reading the product descriptions, participants were instructed to consider all the information and choose a store that they would like to shop. Finally we measured the choice difficulty, evaluation of product assortments, and anticipated regret on a 7-point scale. We conducted two-way ANOVA in testing the main hypothesis that depleted consumers will show poorer subsequent self-control than non-depleted consumers when they make a decision in large assortment. Results - Compared with non-depleted participants, depleted participants showed the bigger difference from the degree of choice difficulty and product attractiveness between large and small assortments, but the result revealed only a significant interaction effect of resource depletion and assortment size on choice difficulty. Also depleted participants showed the smaller difference from the degree of anticipated regret between large and small assortments than non-depleted participants. Conclusion - Depleted individuals by a prior task are relatively effortless and intuitive form of choosing products so that they try to avoid making effortful trade-offs among choice difficulty such as large assortment, compare with non-depleted individuals. However, for anticipated regret, non-depleted individuals in small assortment anticipate more regret by excluding or at least restricting the possibility of buying attractive items or another kind of potential items than depleted individuals, regardless less choice difficulty in small option. To sum up, it is important to note that individuals are influenced by self-regulatory resources and their self-regulatory conditions contribute to the overall positive or negative impact of product assortment on choice.

• Explosives and Blasting
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• v.9 no.1
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• pp.3-13
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• 1991

The cautious blasting works had been used with emulsion explosion electric M/S delay caps. Drill depth was from 3m to 6m with Crawler Drill ${\phi}70mm$ on the calcalious sand stone (soft -modelate -semi hard Rock). The total numbers of test blast were 88. Scale distance were induced 15.52-60.32. It was applied to propagation Law in blasting vibration as follows. Propagtion Law in Blasting Vibration $V=K(\frac{D}{W^b})^n$ were V : Peak partical velocity(cm/sec) D : Distance between explosion and recording sites(m) W : Maximum charge per delay-period of eight milliseconds or more (kg) K : Ground transmission constant, empirically determind on the Rocks, Explosive and drilling pattern ets. b : Charge exponents n : Reduced exponents where the quantity $\frac{D}{W^b}$ is known as the scale distance. Above equation is worked by the U.S Bureau of Mines to determine peak particle velocity. The propagation Law can be catagorized in three groups. Cubic root Scaling charge per delay Square root Scaling of charge per delay Site-specific Scaling of charge Per delay Plots of peak particle velocity versus distoance were made on log-log coordinates. The data are grouped by test and P.P.V. The linear grouping of the data permits their representation by an equation of the form ; $V=K(\frac{D}{W^{\frac{1}{3}})^{-n}$ The value of K(41 or 124) and n(1.41 or 1.66) were determined for each set of data by the method of least squores. Statistical tests showed that a common slope, n, could be used for all data of a given components. Charge and reduction exponents carried out by multiple regressional analysis. It's divided into under loom over loom distance because the frequency is verified by the distance from blast site. Empirical equation of cautious blasting vibration is as follows. Over 30m ------- under l00m ${\cdots\cdots\cdots}{\;}41(D/sqrt[2]{W})^{-1.41}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}A$ Over 100m ${\cdots\cdots\cdots\cdots\cdots}{\;}121(D/sqrt[3]{W})^{-1.66}{\;}{\cdots\cdots\cdots\cdots\cdots}{\;}B$ where ; V is peak particle velocity In cm / sec D is distance in m and W, maximLlm charge weight per day in kg K value on the above equation has to be more specified for further understaring about the effect of explosives, Rock strength. And Drilling pattern on the vibration levels, it is necessary to carry out more tests.

• Research in Plant Disease
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• v.11 no.2
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• pp.179-184
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• 2005

A previous study reported that the stem and root rot of paprika (Capsicum annum L. var, grossum) caused by Nectria haematococca became a threat to safe cultivation of the plant in the country. However, no strategies for control the disease have been suggested. In this study, fungicides registered for pepper were screened to evaluate their control effects on the disease. Among fungicides tested, prochloraz manganase complex com pletely suppressed mycelial growth of the pathogen at 10 ppm a.i. tebuconazole, benomyl, and carbendazim $\cdot$kasugamycin also effectively inhibited mycelial growth of the fungus. However, kresoxim-methyl and triflox ystrobin did not suppress mycelial growth but significantly suppressed conidial germination of the fungus. Azoxystrobin, benomyl, prochloraz, tebuconazol, and carbendazim$\cdot$ kasugamycin were also effective to retard conidial germination. In vivo tests, tebuconazole strongly inhibited the plant growth even at 16,000x (15.6 ppm a.i.), while others did not induce chemical injury at 4,000x or 8,000x when drenched into a rockwool cube. In a greenhouse test, prochloraz manganase complex at 125 ppm a.i. (4,000x) showed highest control value by $89.9\%$. Other fungicides thiophanate-methylthiram, axozystrobin, trifloxystrobin, and benomyl presented $60-80\%$ control value in the hydroponic cultivation system. However, application time and interval remained to be investigated for identify maximum residue limit.

• Journal of the Korea Concrete Institute
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• v.22 no.1
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• pp.123-130
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• 2010

In this study, mixed recycled coarse aggregate (RCA) was produced by mixing RCA from waste concrete in order to evaluate a new method of RCA production. Bond strength between reinforcing bars and RCA concrete was qualitatively evaluated as a part of continuous studies to establish design code of reinforced concrete structural members using recycled aggregate. For practical application, specimens were manufactured with the ready mix RCA concrete. Parameters investigated include: concrete compressive strength (i.e 21, 27 and 40 MPa), replacement levels (i.e 0, 30, 60 and 100%), bar position (i.e vertical and horizontal) and bar location (75 and 225 mm). For the pull-out test, each specimen was in the form of a cube, with each side of 150 mm in length and a deformed bar, 16 mm in diameter, was embedded in the center of each specimen. From the test results, the most of HT type specimen with compressive strength of 21 and 27 MPa showed lower bond strength than the ones provided in CEB-FIP and considered in reinforcement location factor ($\alpha\;=\;1.3$). It was reasoned that bonded area of top bar specimen was reduced at the soffit of reinforcement because of bleed water of fresh concrete. Therefore the reinforcement location factor in current KCI design code should be reviewed and modified.