• New & Renewable Energy
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• v.5 no.4
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• pp.52-58
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• 2009

Upgrading of pyrolysis wax oil using HZSM-5 catalyst has been conducted in a continuous fixed bed reactor at $450^{\circ}C$, 1hour, LHSV 3.5/h. The catalytic degradation was studied with a function of catalyst amount and reaction temperature. The raw pyrolysis wax oil shows relatively high boiling point distribution ranging from around $300^{\circ}C$ to $550^{\circ}C$, which has considerably higher boiling point distribution than that of commercial diesel. The catalytic degradation using HZSM-5 catalyst shows the high conversion of pyrolysis wax oil to light hydrocarbons. The liquid product obtained shows high gasoline range fraction as around 90% fraction and considerably high aromatic fraction in liquid product. Here, the experimental variable such as catalyst amount and reaction temperature was influenced on the product distribution.

• Analytical Science and Technology
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• v.12 no.2
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• pp.159-165
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• 1999

The adsorption and separation behaviors of transition metal ions using a merrifield resin bound 1,12-diaza-3,4:9,10-dibenzo-5,8-dioxacyclopentadecane (NTOE) and 1,12,15-triaza-3,4:9,10-dibenzo-5,8-dioxacycloheptadecane(NDOE) were investigated in aqueous solution. The orders of adsorption degree(E) and distribution ratio(D) of transition metal ions were Cu(II)$t_R$) of metal ions were affected by adsorption degree(E) and distribution ratio(D). This results showed good separation efficiency of Ag(I) from mixed metal solution.

• Analytical Science and Technology
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• v.11 no.4
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• pp.248-253
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• 1998

The adsorption and separation behaviors of alkali, alkaline earth and transition metal ions using a poly-dibenzo-18-crown-6 were investigated in aqueous solution. The adsorption degree(E) and distribution ratio(D) of alkali, alkaline earth metal ions were Li(I)$t_R$) of metal ions were affected by the adsorption degree(E) and distribution ratio(D). This results showed good separation efficiency of K(I), Sr(II), Ag(I) and Pb(II) from the mixed metal solution.

• Korean Journal of Plant Resources
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• v.12 no.4
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• pp.297-302
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• 1999

This study was carried out to find morphological characters of flower and its distribution in mixed population of Paeonia lactiflora Pallas. In distribution of flowering periods, early, medium, and late matured type were 18%, 56%, and 26%, respectively. Flowering duration was less than eight days in 9% of flowers. In next 9 to 11 days, 12 to 14 days and more than 15 days showed, 50%, 37% and 4% respectively. For flower sizes, small size below 9cm diameter were 11%, medium size between 9 to 13cm diameter and large size above 13cm diameter were 65% and 24%, respectively. Among six kinds of flower colors - red, red pink, pink, light pink, pale yellow and white, pink color flowers was dominant, showed 56%. In flower types, single flower was 76%, and anemone, crown, bomb and japanese types were also present. Flower stem diameter were positively correlated with flowering duration, flower size and number of stamens, and negatively correlated with number of stamens and pistils, number of pistils and petals.

• Korean Journal of Plant Resources
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• v.13 no.3
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• pp.179-187
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• 2000

The achene morphology about 16 taxa of Korean Aster L. sensu lato were investigated to estimate its taxonomic values. The achene shapes were divided into four types; oblanceolate-oblong, obovate, oblong and obovate-oblong. The trichome shape on achene six types; uniseriate-conical, filiform, cylindrical, capitate type, long stalk capitate and globular. Their distributional features on upper part of achene four types; absent, sparse distribution of conical trichome, dense distribution of conical trichome and mixed distribution of conical and capitate trichome. The achene shapes and trichome characteristics were regarded to be a good characters in delimiting taxa because these did not differ among individuals in same taxa, but differ among the taxa. If Korean Aster L. sensu late were divided into Kalimeris, Heteropappus, Aster, Cymnaster, the capitate forms and mixed distribution of conical and capitate trichome were recognized as the good characters in delimting above section such as genus Kalimeris and Heteropappus, section Pseudocalimeris of Aster L. sensu stricto.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.675-677
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• 2005

This study proposes a fuzzy classification using EM algorithm. For cluster validation, this approach iteratively estimates the class-parameters in the fuzzy training for the sample classes and continuously computes the log-likelihood ratio of two consecutive class-numbers. The maximum ratio rule is applied to determine the optimal number of classes.

• Journal of Ecology and Environment
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• v.37 no.2
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• pp.81-90
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• 2014

This study examined the main factors affecting the distribution of Phytolacca americana, an exotic plant species in Korea, in coastal sand dunes. The areas examined from June 2004 to February 2006 were in Sindusagu where was located on Sindu-ri, Wonbuk-myen, Taean-gun, Chungcheongnam-do. The vegetation, sediment properties, sizes and ages of Robinia pseudoacacia, P. americana and Pinus thnunbergii and spatial distribution of P. americana were assessed. Firstly, correlation coefficients (CC) between P. americana's root biomass and sediment properties were not significant. Secondly, of the four community types, P. americana was not in the mixed herbaceous community and its density was the highest in the P. thunbergii-R. pseudoacacia and R. pseudoacacia community The Poisson distribution analysis revealed the distribution of P. americana to be severely clumped. The root biomass of P. americana and the basal area of R. pseudoacacia were significantly correlated, but the CCs between P. thunbergii and other two species were not significant. The ages of P. americana and R. pseudoacacia in a quadrat were significantly correlated. Thirdly, P. americana's ages in a quadrat were mostly similar to each other. Therefore, the spatial distribution of P. americana was largely influenced by R. pseudoacacia but not by the sediment properties, and plants in a narrow area were concurrently germinated.

• Journal of Distribution Science
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• v.19 no.10
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• pp.17-22
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• 2021

Purpose: Covid-19 has caused an unprecedented situation for the tourism industry with slumping demand during the outbreak and many uncertainties about tourist behavior in the post-pandemic. This study is aimed to discover the distribution in the behavior of tourists in Vietnam, whose government has taken serious and early actions towards the health crisis and among the earliest to reopen the economy. Research design, data, and methodology: We adopted a mixed-method approach - combining qualitative interviews with quantitative research using a questionnaire survey. Through the form of the online survey through social networking channels: Facebook, Gmail. The study received 261 valid responses for analysis. Multivariate analysis techniques were used: descriptive statistics, exploratory factor analysis (EFA). Results: From the data and result of EFA, the result showed that the distribution of tourist behavior could be grouped into four main factors, including (1) the general impacts, (2) travel-related behaviors; (3) attitudes and preferences regarding modes of tours and destinations; (4) awareness of safety and hygiene. Conclusions: These results highlighted the importance of the theory of perceived risks in explaining the travelers' prudent decisions. In addition, this study provides practical implications for policymakers and various stakeholders of Vietnam's tourism industry in formulating the recovery strategy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5C
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• pp.171-185
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• 2011

Ready-mixed shotcrete that mixed with high quality aggregate and can improve construction quality is produced in a dry mortar plant and transported to construction sites. Because of using aggregate that produced in a special plant, Ready-mixed shotcrete has many advantages : good grain-size distribution, minimum stone powder, high quality and standardization material, etc. In this basic study different from the existing study that limited to additive and accelerator, the improvement of aggregate quality was tried to upgrade the shotcrete performance. The investigation about the construction conditions of shotcrete was performed and the result of an opinion poll was analyzed for a good grasp of the problems in domestic shotcrete quality. Pilot Plant Test was also performed to minimize the material segregation in plant manufacturing process. In additions, the field test was performed to find the optimum contents of synthetic fiber, appearing the same flexible toughness with that of steel fiber, and to find the optimum replacement ratio of blast furnace slag.

• Journal of the Korean Geosynthetics Society
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• v.2 no.1
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• pp.27-37
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• 2003

The factors affecting shear strength and friction characteristics of the fiber-mixed soil can be classified into engineering properties of soil; particle-size, distribution, and particle shape, physical and mechanical properties of fiber; shape, length, diameter, tensile strength, elastic modulus, friction coefficient, and mixed ratio and external factors; confined stress and compaction condition. In this study, a series of shear friction tests and pull-out tests were performed to evaluate the friction properties of fiber-mixed soil according to soil type, fiber type, fiber mixed ratio and compaction degree. The materials and test conditions used in this study are as follows. Soils: SM and ML; mixing fibers: three types of polypropylene fibers(net type 38mm and 60mm, and line type 60mm); reinforcement: geogrid; mixing ratio: 0.2% and 0.3%; degree of compaction : 85% and 95%.