• Polymer(Korea)
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• v.36 no.5
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• pp.593-598
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• 2012

Solution polymerization behaviors of L-lactide using single and mixed aluminium catalyst systems were studied. Triisobutylaluminium (TIBA) was a reference catalyst for mixing. For the $Al(O-i-Pr)_3$/TIBA catalytic systems, the molecular weight of the resulting polylactide (PLA) decreased as the composition of $Al(O-i-Pr)_3$ increased. The higher molecular weight shoulder was revealed in their GPC curve. At TIBA of 80 mol% a bimodal GPC curve was shown. The conversion in the trimethylaluminium (TMA)/TIBA catalysts system decreased as the composition of TMA in the mixed catalyst increased. The conversion in the trioctylaluminium (TOA)/TIBA catalysts system decreased as the composition of TOA in the mixed catalyst increased. The unimodal molecular weight distribution was observed with the TOA/TIBA catalyst systems. The Al compounds-mixed catalyst could produce a higher molecular weight shoulder in the GPC curve.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.317-324
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• 2020

Plastic wastes generated from domestic waste are separated by mixed discharge with foreign substances, and the cost of the separation and screening process increases, so recycling is relatively low. In this study, as a fundamental study for recycling mixed plastic wastes generated from domestic waste into concrete aggregates, changes in concrete properties according to the plastic waste types and the substitution rate were evaluated experimentally. The mixed plastic waste aggregate(MPWA) was found to have a lower density and a higher absorption rate compared to the coarse aggregate with good particle size distribution. On the other hand, the single plastic waste aggregate(SPWA) was composed of particles of uniform size, and both the density and the absorption rate were lower than that of the fin e aggregate. It was found that the MPWA substitution concrete did not cause a material separation phenomenon due to a relatively good particle size distribution even with the largest amount of plastic waste substitution, and the amount of air flow increased little. The compressive strength and flexural strength of the PWA substitution concrete decreased as the amount of substitution of the PWA increased due to the low strength of the PWA, the suppression of the cement hydration reaction due to hydrophobicity, and the low adhesion between the PWA and the cement paste. It was found that the degree of deterioration in compressive strength and flexural strength of concrete substituted with MPWA having good particle size distribution was relatively small.

• Journal of Distribution Science
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• v.14 no.2
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• pp.5-12
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• 2016

Purpose - The present study examines the interrelationship between various components constituting shopping experience in the context of the Indian shopping malls. Research design, data, and methodology - Extracting components of shopping experience from the literature review, the study used Interpretive Structural Modelling (ISM) to propose a conceptual model. The study adopted a mixed methods research involving theoretical constructs from past research, qualitative assessment of relationship between the constructs and imposing definite order and direction to qualitative relations based on mathematical computations. Results - Proposed model indicates that the five components of shopping experience (ambience, physical infrastructure, convenience, marketing focus and safety and security) do not converge directly into shopping experience. Rather, they operate following a hierarchy of influences in which marketing focus plays the role of the initiator. Conclusions - This model points at the order of preference of different components of shopping experience and can be a useful guide for retail industry, especially mall developers and supermarket/hypermarket, may use the findings in key decisions about development of physical infrastructure, which are based on marketing focus.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2168-2177
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• 2018

The unavoidable forecast error of wind power is one of the biggest obstacles for wind farms to participate in day-ahead electricity market. To mitigate the deviation from forecast, installation of energy storage system (ESS) is considered. An accurate model of wind power forecast error is fundamental for ESS sizing. However, previous study shows that the error distribution has variable kurtosis and fat tails, and insufficient measurement data of wind farms would add to the difficulty of modeling. This paper presents a comprehensive way that makes the use of mixed skewness model (MSM) and copula theory to give a better approximation for the distribution of forecast error, and it remains valid even if the dataset is not so well documented. The model is then used to optimize the ESS power and capacity aiming to pay the minimal extra cost. Results show the effectiveness of the new model for finding the optimal size of ESS and increasing the economic benefit.

• Journal of Distribution Science
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• v.18 no.9
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• pp.19-30
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• 2020

Purpose: As an environmental concern increases, customers pay more attention to purchase organic food. While customers' purchase intention of organic food has been widely studied, there are lacks of researches regarding the moderation effect of environmental concern and the interactive effect of level of education based on the Theory of Planned Behavior (TPB). This study examines the influence of level of education and environmental concern on purchase intention based on the Theory of Planned Behavior and organic food in Vietnam. Research design, data and methodology: The methodology of mixed methods of qualitative and quantitative is applied with a survey of 420 customers being conducted to collect data from three biggest cities in Vietnam: Ho Chi Minh, DaNang and Hanoi. SPSS 23 and SMART-PLS 3.2 are used for data analysis. Results: The result shows that the customers have more environmental concern which increases their attitude to the intention of purchasing organic food. Moreover, there has not the three-way interactive effect of level of education, environmental concern and attitude on purchase intention toward organic food. Conclusions: This enriches the existing literature with the moderation of environmental concern to the relationship between attitude and purchase intention toward organic food in Vietnam based on the Theory of Planned Behavior.

• Weed & Turfgrass Science
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• v.6 no.4
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• pp.283-291
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• 2017

Zoysiagrass has been used in Korea as a native grass. Informations on distributions, classifications, breeding efforts and outputs, current production and uses of zoysiagrasses in Korea are summarized. During past a few decades, collection of naturally growing zoysiagrass ecotypes has been continued, followed by evaluation, selection and cross-pollination. Classification efforts using important morphological, biochemical traits and DNA polymorphisms resulted in the several suggestions of grouping zoysiagrass species and varieties. Zoysia japonica consistently form separate group, while Zoysia sinica and Zoysia macrostackya have been separately or inter-mixed. Z. matrella with some variations frequently grouped separately but with some similarity with Z. tenuifolia, which was recently renamed as Z. pacifica. Hybrid types of zoysiagrasses were frequently found in Korea. New varieties such as 'Kunhee' and 'Green Ever' etc. were bred by ecotype selections, while 'Senock', 'Semil', 'Millock' were bred through pollination. Molecular approaches were also used to introduce beneficial genes into zoysiagrasses with no practical outputs by legal regulations. Currently popular varieties are inter-specific hybrid types such as 'Anyang' and other local zoysiagrasses as well as common zoysiagrass (Zoysia japonica) Production area in Korea was estimated as 2,947 ha with increasing problems of mixed or contaminated species and varieties.

• Journal of Forest and Environmental Science
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• v.34 no.2
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• pp.126-135
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• 2018

Wood decay fungi were collected in 47 different locations in eight provinces of South Korea from 2011 to 2013. One thousand and five hundreds three fruiting bodies of wood-decay fungi were collected, identified, and classified into 2 phyla, 7 classes, 19 orders, 56 families, 159 genera and 365 species. The most dominant genus and species found were Trametes and T. versicolor. The highest species diversity was found in broad-leaved forest (273 species), and was also found at elevations of 500-1,000 m (227 species). A total of 333 species were collected from broad-leaved trees, 87 species from coniferous trees, and 55 species were collected from both forest types. Gymnopilus liquiritiae was the most dominant species in coniferous trees, while T. versicolor, which was mostly collected from tree trunks below 500 m in elevation, was dominant in broad-leaved trees. Results from the quantitative cluster analysis of wood decay fungi showed that the highest species diversity index was 1.80 in the mixed forests, while the highest similarity among forest types was shown between the broad-leaved and mixed forests.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10A
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• pp.1597-1602
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• 1999

An analog / digital mixed mode frequency multiplication and distribution ASIC for switch link or network synchronization of ATM switching system for B-ISDN has designed. This ASIC generates 234-7 MHz system clock and 77.76 MHz, 19.44 MHz user clocks using 46.94 MHz external clock. It also includes digital circuits for checking and selecting between the two external clocks. For effective ASIC design, full custom technique is used in analog PLL circuit and standard cell based technique is used in digital circuit. Resistors and capacitors are specially designed so the chip can be implemented in 0.8$\mu\textrm{m}$ digital CMOS technology.

• Clean Technology
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• v.8 no.2
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• pp.67-76
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• 2002

Dewatered sludge of 400,000t/y from water treatment plants in Korea is being disposed through landfill and ocean dumping. However, the disposal is posing more and more serious environmental problems at the same time not only because of landfill site shortage in municipal suburbs, but because of the concern it will contaminate the oceans. In this study, the research on utilizing the sludge dried by flash dryer as covering soil in the landfill sites was carried out to solve these problems on environmental affinity. Both dewatered and dried sludge were exposed to the natural condition and observed according to the atmospheric changes. An experiment of soil engineering characteristics of the dried sludge and tests on mixed sludge(silty sandy soil : dried sludge = 10:90 ~ 30:70) such as particle size distribution, liquid and plastic limit, moisture content, specific gravity and compaction test were carried out. According to the compaction test, the compaction was confirmed as the optimum water content ratio was observed in the condition of SM-silty sand of particle size distribution, NP of liquid and plastic limit, 101.4% of moisture content, 2.04~2.12 of specific gravity. The results showed that dried sludges mixed with at least 30% of natural soil could be used as daily covering soil in the landfill sites.

• Nuclear Engineering and Technology
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• v.7 no.4
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• pp.277-284
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• 1975

A result of measurement for the relative dose distribution of neutron gamma mixed radiation field in the biological irradiation facility installed at TRIGA Mark-III reactor is described. The relative dose distributions of neutron-gamma mixed radiation field in the biological exposure room have been experimentally determined using a thermoluminescent dosimeter. Presented herein in graphical forms are the experimental results obtained. It as observed that the region commonly having the characteristics of rather homogeneous horizontal and lateral dose distributions is confined to the area bounded by the two planes horizontally parallel to the beam direction with heights of about 40 cm and 130 cm, respectively, at distances beyond 100 cm from the segmentary surface of the aluminum pool liner projected into the the exposure room, while other areas show a steeper gradient in dosage, especially the places adjacent to the segment of the aluminum pool liner and near the inner po${\gamma}$lion of the concrete walls of the exposure room.