• Journal of the Korean association of regional geographers
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• v.10 no.3
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• pp.682-688
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• 2004

• Journal of the Korean Institute of Educational Facilities
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• v.25 no.6
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• pp.13-18
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• 2018

• Journal of the Korean Institute of Educational Facilities
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• v.26 no.4
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• pp.7-10
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• 2019

• The Pure and Applied Mathematics
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• v.10 no.4
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• pp.207-215
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• 2003

Let R be a prime ring with characteristic different from two and let $\theta,\varphi,\sigma,\tau$ be the automorphisms of R. Let d : $R{\rightarrow}R$ be a nonzero ($\theta,\varphi$)-derivation. We prove the following results: (i) if $a{\in}R$ and [d(R), a]$_{{\theta}o{\sigma},{\varphi}o{\tau}}$=0, then $\sigma(a)\;+\;\tau(a)\;\in\;Z$, the center of R, (ii) if $d([R,a]_{\sigma,\;\tau)\;=\;0,\;then\;\sigma(a)\;+\;\tau(a)\;\in\;Z$, (iii) if $[ad(x),\;x]_{\sigma,\;\tau}\;=\;0;for\;all\;x\;\in\;RE$, then a = 0 or R is commutative.

• Korean Journal of Human Ecology
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• v.9 no.2
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• pp.215-221
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• 2000

Pueraria Radix has known to contain several ingredients of medical action. However, the bitter taste of Pueraria Radix has been an obstacle to develope the products and improve the added value of Pueraria Radix. To moderate the bitter taste of extracts from Pueraria Radix, charcoal powder was used successfully as an adsorbent. The component of the bitter taste from Pueraria Radix was hydrophobic, which mostly eluted with 40-60% ethanol and estimated to be acidic. Puerarin, the essential medical ingredient remained after the adsorption and seemed not be affected by the adsorption to charcoal powder.

• The Journal of the Acoustical Society of Korea
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• v.11 no.1
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• pp.42-51
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• 1992

This paper proposes an acquisition and the representation method of the 3-dimensional information. The proposed range finder system can reduce the computation time by only calculating the ${\triangle}R$ of each pixel compared to the existing methods. We also propose a shape feature extraction method by considering the sign change of the acquired range data. Finally, the effectiveness of this system is demonstrated by several experiments.

• Journal of Applied Reliability
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• v.10 no.3
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• pp.183-197
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• 2010

Web businesses are one of the most dynamic industries where lots of new business models are emerging while the other obsoleted ones are fading away almost every day. It is, therefore, difficult to establish a classification scheme for ever-changing web businesses. Previous researches on business models focus on classifying web businesses in one dimension which made some web sites difficult to fit into one category. We propose two dimensional classification scheme based on the means and the sources of revenue. The two dimensional classification provides more clear and broad perspectives of the web businesses and ways to identify web sites in combinations of several business models.

• The Mathematical Education
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• v.50 no.1
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• pp.61-67
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• 2011

There may be two methods defining the rational exponent $a^{\frac{m}{n}}$ for any positive real number a. The one which is used in all korean highschool mathematics textbooks is to define it as $\sqrt[n]{a^m}$, that is $(a^m)^{\frac{1}{n}}$. The other is to define it as $(\sqrt[n]a)^m}$, that is $(a^{\frac{1}{n}})^m$. In this paper, we insist that the latter is more appropriate and universal, and that the contents of current textbooks on the definition of the rational exponent should be corrected.

• Biomolecules & Therapeutics
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• v.23 no.5
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• pp.428-433
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• 2015

Acetylshikonin, a natural naphthoquinone derivative compound, has been used for treatment of inflammation and cancer. In the present study, we have investigated whether acetylshikonin could regulate the NF-${\kappa}B$ signaling pathway, thereby leading to suppression of tumorigenesis. We observed that acetylshikonin significantly reduced proliferation of several cancer cell lines, including human pancreatic PANC-1 cancer cells. In addition, acetylshikonin inhibited phorbol 12-myristate 13-acetate (PMA) or tumor necrosis-${\alpha}$ (TNF-${\alpha}$)-induced NF-${\kappa}B$ reporter activity. Proteome cytokine array and real-time RT-PCR results illustrated that acetylshikonin inhibition of PMA-induced production of cytokines was mediated at the transcriptional level and it was associated with suppression of NF-${\kappa}B$ activity and matrix metalloprotenases. Finally, we observed that an exposure of acetylshikonin significantly inhibited the anchorage-independent growth of PANC-1 cells. Together, our results indicate that acetylshikonin could serve as a promising therapeutic agent for future treatment of pancreatic cancer.

• Research in Mathematical Education
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• v.10 no.2 s.26
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• pp.125-134
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• 2006

We study on the mathematical disposition of mathematically gifted students in the middle school of Korea. For this purpose, we use a tool which is a psychological test about disposition of mathematics disliking. The tool was developed by Kim et al. (2001: Studies on Exploring Mathematics Disliking Factors and Devising Tools to Analyze Students' Disliking Trends about School Mathematics. J. Korea Soc. Math. Ed. Ser. A Mathematical Education. 40(2), 217-239) to analyze the mathematical disposition of underachievers and we investigate the characteristic of it.