• 한국항행학회논문지
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• 제14권6호
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• pp.975-983
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• 2010

본 논문에서는 하노이의 탑 (Tower of Hanoi; ToH) 문제를 확장한 문제들을 소개하고, ToH 문제의 상태 공간을 그래프로 표현하기 위한 새로운 방안을 제시하고자 한다. 확장한 문제들로는 기둥의 수를 늘린 경우, 디스크 스택의 수를 늘린 경우, 그리고 일반 상태 간의 이동에 대한 세 가지를 소개하고, 다른 변종 문제들을 소개하고자 한다. 우리가 본 논문에서 제시한 새로운 표현 방안은 기존의 하노이 그래프 표현에 대해 확장된 방식의 그래프 표현을 제시하는 것이다. 제안된 표현에서는 각 디스크마다 하나의 직교좌표를 부여해 줌으로써 링크의 표시와 상태의 변화가 디스크가 어느 기둥에 배치되어 있는가와 시각적으로 일치된 시각화를 가능하게 해 준다. 제안된 표현을 기존의 하노이 그래프와 비교해 보면, 제안된 표현에서 디스크를 옮길 수 없는 링크를 제거하면 기존의 하노이 그래프와 isomorphic하다. 따라서, 제안된 표현은 기존의 하노이 그래프를 확장하여 표현력을 고도화한 것임을 알 수 있다. 제안된 표현에 대한 독자들의 이해를 돕기 위해, 우리는 본 논문에서 디스크의 개수가 2와 3인 경우에 대한 제안된 표현의 시각화 예를 제시하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권9호
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• pp.4788-4813
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• 2019

In this paper, we introduce concepts of optimal and near optimal secret data hiding schemes. We present a new digital image steganography approach based on the Galois field $GF(p^m)$ using graph and automata to design the data hiding scheme of the general form ($k,N,{\lfloor}{\log}_2p^{mn}{\rfloor}$) for binary, gray and palette images with the given assumptions, where k, m, n, N are positive integers and p is prime, show the sufficient conditions for the existence and prove the existence of some optimal and near optimal secret data hiding schemes. These results are derived from the concept of the maximal secret data ratio of embedded bits, the module approach and the fastest optimal parity assignment method proposed by Huy et al. in 2011 and 2013. An application of the schemes to the process of hiding a finite sequence of secret data in an image is also considered. Security analyses and experimental results confirm that our approach can create steganographic schemes which achieve high efficiency in embedding capacity, visual quality, speed as well as security, which are key properties of steganography.

• Journal of Preventive Medicine and Public Health
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• 제52권2호
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• pp.101-108
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• 2019

Objectives: To objectively determine and compare the physical activity (PA) levels of adults newly diagnosed with type 2 diabetes (T2D) and adults without T2D in Vietnam using an accelerometer. Methods: A total of 120 participants with newly diagnosed T2D and 120 adults without T2D were recruited from a large hospital in Hanoi, the capital city of Vietnam. All participants wore an ActiGraph GT3X accelerometer for at least 5 days, including 1 weekend day. Freedson cut-off points were used to estimate different intensities of PA. In addition, comparisons between groups were made with respect to achieving the World Health Organization (WHO) and International Diabetes Federation (IDF) recommended PA guidelines. Results: Men with T2D had significantly lower levels of PA than men without T2D. The respective multivariable-adjusted mean values of daily step count, daily light-intensity, moderate-intensity, and moderate-to-vigorous-intensity PA were approximately 14%, 19%, and 22% lower in the men with T2D than in their non-T2D counterparts. However, women with T2D accumulated a greater number of steps per day than women without T2D. Only 59.2% of the adults with T2D met the minimum recommended level of PA (WHO and IDF), compared to 74.2% of adults without T2D (p<0.05). After adjusting for potential confounders, participants with T2D experienced 50.0% significantly lower odds of achieving PA recommendations. Conclusions: Vietnamese men with T2D were less physically active than those without T2D, and adults with T2D were less likely to meet PA guidelines. The results suggest a need for integrating PA into the self-management of this chronic condition.

• The Journal of Asian Finance, Economics and Business
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• 제9권4호
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• pp.197-212
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• 2022

The study uses the audited financial statements of 26 Vietnamese commercial banks listed on the Ho Chi Minh City Stock Exchange (HOSE) and Hanoi Stock Exchange (HOSE) during the 2008-2018 period to estimate the system GMM model, which provides empirical evidence on the effect of the variables of customer deposit to total assets (DEPO) ratio, loan to assets (LTA) ratio, liquidity of commercial banks (LIQ), credit development (CRD) ratio, external funding (EFD) ratio, and credit loss provision (LLP) ratio on liquidity risk. The study confirms that commercial banks' internal factors play the most important role, and there is no empirical evidence on macro variables that affect liquidity risk. Finally, in accordance with the theoretical framework, the study uses an estimation method with the R language and the bootstrap methodology to give empirical proof of the nonlinear correlation and U-shaped graph between commercial bank size and liquidity risk. The importance of commercial bank size in absorbing and moderating the effects of liquidity shocks is demonstrated, however, excessive growth in commercial bank size would increase liquidity risk in commercial bank operations.