• 대한수학회보
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• 제47권1호
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• pp.53-61
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• 2010

In this article, we discuss the reflective function which can be represented by three exponential matrixes and apply the results to studying the existence of periodic solutions of these systems. The obtained conclusions extend and improve the foregoing results.

• Journal of applied mathematics & informatics
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• 제16권1_2호
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• pp.265-277
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• 2004

This article deals with the number of periodic solutions of the second order polynomial differential equation using the Riccati equation, and applies the property of the solutions of the Riccati equation to study the property of the solutions of the more complicated differential equations. Many valuable criterions are obtained to determine the number of the periodic solutions of these complex differential equations.

• 대한수학회보
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• 제51권2호
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• pp.457-478
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• 2014

In this paper, a 3D autonomous system, which has only stable or non-hyperbolic equilibria but still generates chaos, is presented. This system is topologically non-equivalent to the original Lorenz system and all Lorenz-type systems. This motivates us to further study some of its dynamical behaviors, such as the local stability of equilibrium points, the Lyapunov exponent, the dissipativity, the chaotic waveform in time domain, the continuous frequency spectrum, the Poincar$\acute{e}$ map and the forming mechanism for compound structure of its special cases. Especially, with the help of the Project Method, its Hopf bifurcation of codimension one is in detailed formulated. Numerical simulation results not only examine the corresponding theoretical analytical results, but also show that this system possesses abundant and complex dynamical properties not solved theoretically, which need further attention.

• Journal of Microbiology and Biotechnology
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• 제29권11호
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• pp.1683-1692
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• 2019

The rise of antimicrobial resistance (AR) is a major threat to global health. The food animal industry contributes to the increasing occurrence of AR. Multiple factors can affect the occurrence and dissemination of AR in the animal industry, including antibiotic use and farm management. Many studies have focused on how the use of antibiotics in food-producing animals has led to the development of AR. However, a few effective mitigating strategies for AR have been developed in food-producing animals, especially those exposed to the environment. The aim of this review is to summarize potential strategies applicable for mitigating AR at the environment-livestock interface.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권7호
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• pp.3401-3420
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• 2018

Pixel expansion and contrast are two major performance parameters for visual cryptography scheme (VCS), which is a type of secret image sharing. Random Grid (RG) is an alternative approach to solve the pixel expansion problem. Chen and Tsao proposed the first (k, n) RG-based VCS, and then Guo et al., Wu et al., Shyu, and Yan et al. significantly improved the contrast in recent years. However, the investigations on improving the contrast of threshold RG-based VCS are not sufficient. In this paper, we develop a contrast-improved algorithm for (k, n) RG-based VCS. Theoretical analysis and experimental results demonstrate that the proposed algorithm outperformers the previous threshold algorithms with better visual quality and a higher accuracy of contrast.

• 대한수학회보
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• 제58권4호
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• pp.973-981
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• 2021

Let R be a commutative ring with identity 1, n ≥ 3, and let 𝒯_n(R) be the linear Lie algebra of all upper triangular n × n matrices over R. A linear map 𝜑 on 𝒯_n(R) is called to be strong commutativity preserving if [𝜑(x), 𝜑(y)] = [x, y] for any x, y ∈ 𝒯_n(R). We show that an invertible linear map 𝜑 preserves strong commutativity on 𝒯_n(R) if and only if it is a composition of an idempotent scalar multiplication, an extremal inner automorphism and a linear map induced by a linear function on 𝒯_n(R).

• Steel and Composite Structures
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• 제49권2호
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• pp.197-213
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• 2023

To investigate the static properties of large high strength bolt shear connector in hybrid fiber-reinforced concrete (HFRC) and normal concrete (NC), eight push-out test specimens with single/double nut and HFRC/NC slabs were designed and push-out tests were conducted. A fine 3D nonlinear finite element (FE) model including HFRC constitutive model was established by using ANSYS 18.0, and the test results were used to verify FE models of the push-out test specimens. Then a total of 13 FE models were analyzed with various parameters including fiber volume fractions of HFRC, bolt diameter and thickness of steel flange. Finally, the empirical equations considering the contribution of polypropylene fiber (PF) and steel fiber (SF) obtained from the regression of the test results and FE analysis were recommended to evaluate the load-slip curve and ultimate capacity of the large high strength bolt shear connector embedded in HFRC/NC.

• 동양고전연구
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• 제35호
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• pp.329-358
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• 2009

왕수인 철학의 개념과 구조는 "대학"과 밀접한 관계를 맺고 있다. 왕수인 심학의 체계성은 "대학"에서 언급하고 있는 심 의 지 물이라는 네 가지 개념의 관계상에서 구축된 것으로, "대학문"은 사구교와 마찬가지로 "대학"의 8조목 가운데 특히 심 의 지 물이라는 네 개의 개념을 체계로 하는 일련의 공부과정이다. "대학" 공부론에 대한 왕수인의 사고를 더듬어보면, 초기의 격물 중심에서 성의에로, 다시 성의에서 치지로 그 공부방법이 바뀌어 감을 알 수 있다. 이는 그의 사상의 심화과정이자 교학사상의 변화과정을 말해주는 것이다. 이는 또한 왕수인 공부론의 내재화 과정이기도 하다. 왕수인은 초기에 주희의 격물론에 심취하여 내 마음 밖에서 이치를 구하는 방법을 추구하였다. 이러한 외향적인 공부방법은 이후 용장오도를 통해 '심즉리'를 주창하면서 점차 내향적인 방법으로 전환하기에 이른다. 왕수인은 "대학문"에서 "대학"의 정심 성의 치지 격물에 대한 해석을 통해 심 의 지 물을 일물일물一物로, 정 성 치 격을 일사一事로 파악하고 있다. 이는 이전의 격물 중심의 공부에서 성의 중심의 공부로, 다시 성의 중심의 공부에서 치지 중심의 공부로의 변화과정을 총괄하여 모든 공부의 합일을 주장하기에 이르렀음을 의미한다. 이 글에서는 "대학문(大學問)" 이전과 "대학문(大學問)" 이후의 자료를 비교 분석하여 왕수인의 대학관이 시기에 따라 어떻게 변화하고 있고, 각 과정에서의 공부의 중점은 어디에 있으며, 이는 왕수인사상의 변화과정 가운데 어떠한 의미를 가지고 있는지 등에 대해 살펴보기로 한다. 이를 통해 왕수인의 "대학"관에 대한 전반적인 조명이 가능할 것이다.