• 대한수학회지
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• 제52권5호
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• pp.907-928
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• 2015

We show in many cases that the Siegel-Ramachandra invariants generate the ray class fields over imaginary quadratic fields. As its application we revisit the class number one problem done by Heegner and Stark, and present a new proof by making use of inequality argument together with Shimura's reciprocity law.

• 한국보육지원학회지
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• 제12권6호
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• pp.123-137
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• 2016

The purpose of this study was to forecast demand of childcare teachers based ion four different scenarios. In order to, the demand for childcare teachers from 2015 to 2024 were forecasted using time series techniques with data on the number of childcare teachers from 2003 to 2014. Results were as followings. Firstly, the demand for childcare teachers was expected to increase until 2019, but after 2020 steadily decreased in terms of scenario 1(child teacher ratio regulation). According to scenario 2(child teacher ratio based on 17 cities and provinces), the demand for childcare teachers was expected to need 440 teachers more until 2016. Then, according to scenario 3(two teachers each class), Scenario 4-1(one teacher and one staff each 2 toddler class and 3 older class) and scenario 4-2(one teacher and one staff each class), the demand of childcare teachers and staffs were estimated. These results implicated that childcare teachers and staffs supply policy would be established according to forecast demand.

• Journal of applied mathematics & informatics
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• 제24권1_2호
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• pp.313-323
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• 2007

The equitable total chromatic number ${\chi}_{et}(G)$ of a graph G is the smallest integer ${\kappa}$ for which G has a total ${\kappa}$-coloring such that the number of vertices and edges in any two color classes differ by at most one. In this paper, we determine the equitable total chromatic number of one class of the graphs.

• 대한수학회지
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• 제42권6호
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• pp.1251-1264
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• 2005

Let D be an acyclic digraph. The competition graph of D has the same set of vertices as D and an edge between vertices u and v if and only if there is a vertex x in D such that (u, x) and (v, x) are arcs of D. The competition number of a graph G, denoted by k(G), is the smallest number k such that G together with k isolated vertices is the competition graph of an acyclic digraph. It is known to be difficult to compute the competition number of a graph in general. Even characterizing the graphs with competition number one looks hard. In this paper, we continue the work done by Cho and Kim[3] to characterize the graphs with one hole and competition number one. We give a sufficient condition for a graph with one hole to have competition number one. This generates a huge class of graphs with one hole and competition number one. Then we completely characterize the graphs with one hole and competition number one that do not have a vertex adjacent to all the vertices of the hole. Also we show that deleting pendant vertices from a connected graph does not change the competition number of the original graph as long as the resulting graph is not trivial, and this allows us to construct infinitely many graph having the same competition number. Finally we pose an interesting open problem.

• 대한산업공학회지
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• 제20권4호
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• pp.65-72
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• 1994

An independent set of nodes is a set of nodes no two of which are joined by an edge. An independent set is called maximal if no more nodes can be added to the set without destroying its independence. The greatest number of maximal independent set is the maximum possible number of maximal independent set of a graph. We consider the greatest number of maximal independent set in connected graphs with fixed numbers of edges and nodes. For arbitrary number of nodes with a certain class of number of edges, we present the connected graphs with the greatest number of maximal independent set. For a given class of number of edges, the structure of graphs with the greatest number of maximal independent set is that the two components are completely joined; one consists of disjoint triangles as many as possible and the other is the complete graph with remaining nodes.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제7권1호
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• pp.27-32
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• 2000

The quadratic fields generated by $x^2$=ax+1($\alpha\geq$1) are studied. The regulators are relatively small and are known at one. The class numbers are relatively large and easy to compute. We shall find all the values of p, where p=$\alpha^2$+4 is a prime in $\mathbb{Z}$, such that $\mathbb{Q}(\sprt{p})$ has class numbers 1, 3 and 5.

• 교육녹색환경연구
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• 제8권2호
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• pp.40-50
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• 2009

The toilet in school building is one of most crucial elements for the recent changing face in school design, but the number of toilets and urinals in most school may not be sufficient to meet current needs, especially in the girl's toilet rooms. This study aims to suggest a guideline in designing the toilet in school buildings and propose the optimum area and development of models. The survey for this study is conducted through questionnaires collected and research from 9 schools in Seoul. The results of this study, it is suggested that the number of toilet facilities in school buildings be required by ratio of 0.5 toilets per a class and 1.1 urinal per a class for boy. In case of girls, it is suggested that ratio of 1.6 toilets per a class. Based on the result, it also propose various unit plans for each class block with space such as rest zone, green zone, powder zone etc.

• 대한수의학회지
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• 제50권3호
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• pp.179-185
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• 2010

The present study was undertaken to establish reference values for the composition blood lymphocyte populations and compare forty three Hanwoo neonatal calves (KC) with twenty one Holstein calves (HC) by blood cell count and immunophynotying. The percentages of CD2+, CD4+, CD8+, CD26+, ACT2+, MHC class, MHC class II and WC1+ T cells, B cells were determined by flow cytometry. The number of lymphocyte and monocyte in HC were higher than those of KC. However, the number of neutrophils was higher in HC than KC. The proportions of CD2+, CD4+, CD8+, MHC class, and WC1+ lymphocytes remained relatively stable during the study period, while there was a moderate increase in the relative percentage of CD26+, ACT2+, MHC class II and B cell from birth to approximately 3 weeks of age. Marked differences in the relative proportions of the lymphocyte subpopulations were noted between the individual calves. The present study shows that the T-cell subpopulations are present in peripheral blood of KC at levels comparable with HC, while the MHC class II and B cell population of KC increases significantly with age. The absolute number of WBC in KC was due to the decrease of absolute number of neutrophil rather than the increase of lymphocyte. The results indicated that KC have significantly higher number of neutrophils, and proportion of MHC class II and B cell than HC.

• Journal of the Korean Statistical Society
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• 제1권1호
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• pp.11-17
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• 1973

A class of sequential binomial tests and a sequential rank test can be applied for testing two treatments when subjects are paired in many-to-one ratio. The efficiency of each test is examined in terms of the average sample number. The binomial tests are much easier and more convenient to apply than the rank test not as efficient. Within the class of binomial test, the median test appears to be the most efficient is general.

• 한국수산과학회지
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• 제46권4호
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• pp.445-453
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• 2013

Walleye pollock Theragra chalcogramma fisheries in Korean waters have changed dramatically during the last three decades: the highest catches occurred in 1981, followed by continuous decreases through the 1990s, ending with a complete collapse of the population in the 2000s. The major spawning ground of walleye pollock is located in North Korean waters, and some juveniles (called nogari in Korean, <300 mm) migrate to the south for feeding and growth. Since the 1960s, Korean fishermen have often caught juveniles, and the weight (metric tons) of juvenile catch was recorded from 1975-1997. However, because the walleye pollock were not aged, the population age structure was not delineated. We developed a model to estimate the number of walleye pollock of each size class based on catch statistics of adults and juveniles, the catch proportion of each size class, and length and weight information on specimens collected by Danish-seine and drift-gill-net fisheries. The model results demonstrated that the recruitment size of walleye pollock was consistently within the 200-250mm size class, and the highest number of this size class occurred in 1981, although values greatly fluctuated interannually. The number of juvenile pollock was 10.4 times higher than that of adult pollock during 1975-1997. The total yield of juvenile pollock was 0.95 million tons, which was equivalent to about 68.2% of total pollock production. The number of juvenile pollock caught during the same period, however, was 16 billion, comprising about 91.2% of the total number caught. Such high fishing pressure on juvenile pollock is considered one of the main factors causing the collapse of the pollock population.