• Journal for History of Mathematics
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• v.27 no.2
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• pp.111-125
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• 2014

Jisuguimundo is an inimitable magic hexagon devised by Choi Seok-Jeong, who was the author of GuSuRyak as well as a prime minister in Joseon dynasty. Jisuguimundo, recorded in GuSuRyak, is also known as Hexagonal Tortoise Problem (HTP) because its nine hexagons resemble a tortoise shell. We call the sum of numbers in a hexagon in Jisuguimundo a magic sum, and show that the magic sum of hexagonal tortoise problem of order 2 varies 40 through 62 exactly and that of hexagonal tortoise problem of order 3 varies 77 through 109 exactly. We also find all of the possible solutions for hexagonal tortoise problem of oder 2.

• Communications of Mathematical Education
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• v.24 no.1
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• pp.195-220
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• 2010

The magic square is one of the number arrangements and the sums of each row, column, and diagonal are all equal. The meaning of "方" is "Square". If we don't consider the condition of 'square' then is it possible any number arrangement? There are many special number arrangements such as "magic five number circle(緊五圖)", "magic six number circle(聚六圖)", "magic eight number circle(聚八圖)", "magic nine number circle(攢九圖)", "magic eight camp circle(八陣圖)", "magic nine camp circle(連環圖)" in the ancient Chinese mathematics books such as "楊輝算法", "算法統宗". Also, there is a very special and beautiful number arrangement Jisuguimoondo(地數龜文圖) in the mathematics book "Goosuryak(九數略)" written by Choi suk jung(崔錫鼎) in the Joseon Dynasty. In this study, we introduce a various number arrangements and their properties.

• Journal for History of Mathematics
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• v.31 no.4
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• pp.183-196
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• 2018

In this study, we propose an approximate method to make Jisuguimundo with magic number 93 to 109. In this method, for two numbers p, q with a relationship of M = 2p+q, we use eight pairs of two numbers with sum p and five pairs of two numbers with sum q. Such numbers must be between 1 and 30. Instead of determining all positions of thirty numbers, this method shows that Jisuguimundo with magic number 93 to 109 can be made by determining positions of thirteen numbers $a_i$(i = 1, 2, ${\cdots}$, 8), $b_5$, $c_i$(i = 1, 2, 3, 4). Method 1 is used to make Jisuguimundo with magic number 93 to 108, and method 2 is used to make Jisuguimundo with magic number 109.

• Journal for History of Mathematics
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• v.30 no.2
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• pp.71-86
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• 2017

When looking for solutions of Jisuguimundo with magic number 88~92 and 94~98, alternating method is applied to each possible partitions of each magic number. But this method does not apply in case of finding solutions of Jisuguimundo with magic number 87, 93, and 99. In this study, it is shown that solutions of Jisuguimundo with magic number 87, 93, and 99 can be found by applying alternating method to two partitions. These two partitions are derived partitions obtained by each partitions of magic number 87, 93, and 99. If every number from 1 to 30 which satisfy every unit path of Jisuguimundo can be found in all components of these two derived partitions, that arrangement is just a solution of Jisuguimundo. The method suggested in this study is more developed one than the method which is applied to just one partition.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.1
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• pp.77-93
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• 2011

Jisuguimundo(地數龜文圖) is a magic hexagon created by Suk-Jung Choi in his book about three hundreds years ago in Korea. Recently attention is focused on jisuguimundo, and it is known that jisuguimundos exist when magic number is from 77 to 108, however a general method making jisuguimundos is not known so far. Up to now, methods of making jisuguimundos using computers are known. In this study, a method making jisuguimundos is suggested using pairs of two numbers with sum p and q ($p{\neq}q$) alternately when magic number is from 88 to 92, and from 94 to 98, without using computer in elementary math class as a task for problem solving. Mathematical theory is introduced for this method, and jisuguimundos are presented which are found out through this method. Elementary students are expected to make their own jisuguimundo using this method.

• Journal of the Korean School Mathematics Society
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• v.15 no.1
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• pp.155-169
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• 2012

In this paper, we explored the possibility that JiSuYongYukDo and JiSuGuiMunDo which were posed by Suk-Jung Choi can be used for storytelling. Firstly, from the solutions of JiSuYongYukDo and JiSuGuiMunDo which were offered by Suk-Jung Choi, students can inquire out finding four characteristics such as: He chose expected values as magic numbers, used pairs of two complementary numbers, there are independent four pairs of numbers which do not affect other pairs, and the array which exchange every two complementary numbers in certain solution is also solution. Secondly, in case of JiSuYongYukDo students can inquire out finding six numbers that satisfy certain condition instead of finding solutions, and in case of JiSuGuiMunDo students can inquire out finding eleven numbers that satisfy certain conditions instead of finding solutions. And through this strategy, they know that Suk-Jung Choi style solutions can be obtained variously in one's own way without undergoing many trials and errors.

• Journal of the Korean School Mathematics Society
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• v.14 no.3
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• pp.261-275
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• 2011

Seok-Jung Choi's Jisuguimundo mentioned as a brilliant legacy in the history of Korean mathematics had been cloaked in mystery for 300 years. In the meantime there has been some efforts to find solutions, and some particular answers were found, but no one achieved full success mathematically. By the way, H-alternating method showed that to find solutions of Jisuguimundo is possible, even though that method restricted magic number to 88~92 and 94~98. In this paper, $n{\times}n$ Jisuguimundo is defined, and it is showed that finding solutions of it is always possible in case of partition $({\upsilon}+1)+{\upsilon}+({\upsilon}+1)$ & co-partition ${\upsilon}+({\upsilon}+1)+{\upsilon}$, partition $({\upsilon}+1)+({\upsilon}-1)+({\upsilon}+1)$ & co-partition $({\upsilon}-1)+({\upsilon}+1)+({\upsilon}-1)$, partition $({\upsilon}+1)+({\upsilon}+2)+({\upsilon}+1)$ & co-partition $({\upsilon}+2)+({\upsilon}+1)+({\upsilon}+2)$, and partition $({\upsilon}+1)+({\upsilon}+3)+({\upsilon}+1)$ & co-partition $({\upsilon}+3)+({\upsilon}+1)+({\upsilon}+3)$. And It is suggested to find solutions of $n{\times}n$ Jisuguimundo could be used as a task for problem solving.