• 경영과학
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• 제31권4호
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• pp.135-150
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• 2014

This paper analyzes the operational efficiency of 91 individual retail stores in Seoul by a two-step procedure. In the first step, a data envelopment analysis (DEA) model is used to identify the efficiency scores. Three inputs (store size, number of items, and number of employees) and two outputs (sales and number of customers) are used for the efficiency measurement. In the second step, a Tobit regression model is used to identify the drivers of efficiency. DEA efficiency scores are used to test hypotheses on the impact of five independent variables, namely store age, number of items per store size, number of items per employee, trade area index, and number of competitors. Results of the Tobit analysis show that number of items per store size, number of items per employee, and number of competitors play a significant role in influencing the operational efficiency of retail stores. Managerial implications of the study are discussed.

• Child Studies in Asia-Pacific Contexts
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• 제5권1호
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• pp.39-49
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• 2015

Not all parents are skilled in scaffolding their young children's numeracy learning. The present study investigated the effectiveness of a parent training program in promoting Filipino young children's number sense via card game playing at home. Participants were 161 young children and their parents; families were of a relatively low socioeconomic status. During the 10-week intervention period, parents in the experimental group received training on how to use number game cards to help their children acquire various numeracy concepts; parents in the control group received no special instructions. Children in the experimental group showed greater improvements in their performance on six number sense tasks (namely numeral identification, object counting, rote counting, missing number, numerical magnitude comparison, and addition) over the intervention period than did children in the control group. Findings of the present study suggest that providing simple training to parents on strategies for fostering their young children's number sense at home is important for giving children a good early start in basic number knowledge.

• 대한기계학회논문집B
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• 제32권6호
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• pp.421-428
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• 2008

In this paper, we investigated the flow of an incompressible viscous fluid past a sphere which is oscillated one-dimensionally over flow regimes including laminar flow at Reynolds number of 100, 200 and Strouhal number of up to 5000. In order to analyze flow and estimate critical Strouhal number, we introduce three-dimensional vortex element method. With this method, separation only appears in decreasing velocity region during the high Strouhal numbers. We find out that vorticity distribution around sphere is proportionl to the Strouhal number. And we can decide that low Strouhal number is below 100, high Strouhal number is above 500 from many results. Thus the critical Strouhal number(St) effected to the flow field is expected to be 100

• 한국수학교육학회지시리즈D:수학교육연구
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• 제21권1호
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• pp.1-13
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• 2018

While the utility of the number line is considerable, articulating its conceptual foundation is often neglected in school mathematics. We suggest that it is important to build up strong conceptual foundations in the earlier grades so that number lines can be used in a more meaningful way and that any misconceptions associated with the number line can be prevented or intervened. This paper addresses unit, direction, and origin as the key elements of number lines and presents activities from Davydov's curriculum for early grades that promote exploration of those key elements and may resolve some students' misconceptions. As shown in sample activities from Davydov's curriculum, this paper suggests that students can broaden their perspectives on the number line and use it versatilely in various areas of mathematics learning when they deeply engage in the construction of a number line and have flexibility in interpreting the relationships between key number line elements.

• 대한수학회보
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• 제58권4호
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• pp.829-836
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• 2021

In this paper, we consider several domination parameters like perfect domination number, locating-domination number, open-locatingdomination number, etc. in the Mycielski graph M(G) of a graph G. We found upper bounds for locating-domination number of M(G) and computational formulae for perfect locating-domination number and open locating-domination number of M(G). We also showed that the perfect domination number of M(G) is at least that of G plus 1 and that for each positive integer n, there exists a graph G_n such that the perfect domination number of M(G_n) is equal to that of G_n plus n.

• Wind and Structures
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• 제13권4호
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• pp.347-362
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• 2010

Researches on the Reynolds number effect on bridge decks have made slow progress due to the complicated nature of the subject. Heretofore, few studies on this topic have been made. In this paper, aerostatic coefficients, Strouhal number ($S_t$), pressure distribution and Reynolds number ($R_e$) of Great Belt East Bridge and Sutong Bridge were investigated based on deterministic vortex method (DVM). In this method, Particle Strength Exchange (PSE) was chosen to implement the simulation of the flow around bluff body and to analyze the micro-mechanism of the aerostatic loading and Reynolds number effect. Compared with the results obtained from wind tunnel tests, reliability of numerical simulation can be proved. Numerical results also showed that the Reynolds number effect on aerostatic coefficients and Strouhal number of the two bridges can not be neglected. In the range of the Reynolds number from $10^5$ to $10^6$, it has great effect on the Strouhal number of Sutong Bridge, while the St is difficult to obtain from wind tunnel tests in this range.

• 한국지능시스템학회논문지
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• 제19권2호
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• pp.265-272
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• 2009

Fuzzy number intuitionistic fuzzy sets (FNIFSs), each of which is characterized by a membership function and a non-membership function whose values are trigonometric fuzzy number rather than exact numbers, are a very useful means to describe the decision information in the process of decision making. Wang [10] developed some arithmetic aggregation operators, such as the fuzzy number intuitionistic fuzzy weighted averaging (FIFWA) operator, the fuzzy number intuitionistic fuzzy ordered weighted averaging (FIFOWA) operator and the fuzzy number intuitionistic fuzzy hybrid aggregation (FIFHA) operator. In this paper, based on the FIFHA operator and the FIFWA operator, we investigate the group decision making problems in which all the information provided by the decision-makers is presented as fuzzy number intuitionistic fuzzy decision matrices where each of the elements is characterized by fuzzy number intuitionistic fuzzy numbers, and the information about attribute weights is partially known. An example is used to illustrate the applicability of the proposed approach.

• 한국작물학회지
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• 제11권
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• pp.99-103
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• 1972

들깨 수량에 영향하는 형질을 정확히 알기 위하여 형질상호간의 상관관계와 경로계수를 분석한 바 그 결과를 요약하면 다음과 같다. 1. 경장은 경식경, 화방수, 경중과 유효분지수는 화방수와 높은 정의 상관을 그리고 유효분지수는 1,000입중과 화방수는 1,000입중과 각각 높은 부의 상관을 보였다. 2. 수량에 직접적으로 영향하는 형질은 경중, 화방수 1,000입중 유효분지수, 경직경등이다. 3. 간접적 효과는 경장대 경중, 유효분지수 대 화방수, 화방수 대 경중간에 높은 값을 보였다. 4. 들깨의 수량은 경장이 길고 유효분지수 및 화방수가 많으며 1,000입중과 경중이 무거운것일수록 수량이 많다는 사실을 알수 있다.

• 한국환경과학회지
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• 제21권1호
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• pp.23-30
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• 2012

The aerosol number concentration have measured with an aerodynamic particle sizer spectrometer(APS) at Gosan site in Jeju, Korea, from March 2010 to March 2011. And then the atmospheric aerosol number concentration, the temporal variation and the size distribution of aerosol number concentration have been investigated. The aerosol number concentration varies significantly from 748 particles/$cm^3$ to zero particles/$cm^3$. The average number concentration in small size ranges are very higher than those in large size ranges. The number concentrations in the size range 0.25~0.28 ${\mu}m$, 0.40~0.45 ${\mu}m$ and 2.0~2.5 ${\mu}m$ are about 84 particles/$cm^3$, 2 particles/$cm^3$ and 0.4 particles/$cm^3$, respectively. The number concentrations in range of larger than 7.5 ${\mu}m$ are below 0.001 particles/$cm^3$. The seasonal variations in the number concentration for smaller particle(<1.0 ${\mu}m$) are not much, but the variations for larger particle are very evident. And strong amplitudes of diurnal variations of entire averaged aerosol number concentration are not observed. Size-fractioned aerosol number concentrations are dramatically decreased with increased particle size. The size-fractioned aerosol number concentrations in size range 0.8~4.0 ${\mu}m$ during nighttime are evidently higher than during daytime, but similar levels are appeared in other size range. The seasonal differences in the size-fractioned number concentrations for smaller size range(<0.7 ${\mu}m$) are not observed, however, the remarkable seasonal differences are observed for larger size than 0.7 ${\mu}m$.

• 동아시아식생활학회지
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• 제16권5호
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• pp.497-505
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• 2006

This questionnaire study was conducted to investigate the levels of recognition and attitude for Korean traditional food among Japanese tourists. The aim was to provide basic data for making a detailed marketing direction alignment of globalization and commercialization of Korean traditional food. The results can be summarized as follows. The 'Korean wave(Hanliu)' was 'the number of known Korean star performers'(3.77 points), 'the number of watched Korean dramas'(3.67 points), 'the number of watched Korean movies'(3.44 points), 'the number of owned Korean singer's tapes or CDs'(3.04 points), 'the number of read books'(2.83 points), and 'the number of viewed cartoons'(2.49 points), in order. The high-intake frequency of Korean traditional foods was 'Bibimbap', 'Galbigui', 'Baechookimchi', 'Bulgogi', 'Kkakdugi', 'Tteokbokki', 'Japchae', 'Galbitang', 'fajeon', and 'Namullyu' in order. On the other hand, the intake frequency of 'Songpyeon', 'Inielmi', 'Sikhye' and 'Sujeonggwa' was very low. The most effective 'Hanliu' item for raising the recognition of Korean traditional food was 'the number of read books'. The most effective 'Hanliu' item for raising the experience of Korean cooking was 'the number of read books', followed by 'the number of watched Korean movies', 'the number of watched Korean dramas', and 'the number of viewed cartoons' in order. The most effective 'Hanliu' item for raising the intake frequency of Korean traditional food was' the number of watched Korean dramas', followed by 'the number of watched Korean movies' and 'the number of read books' in order.