• Journal of the Korean Mathematical Society
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• v.47 no.2
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• pp.351-361
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• 2010

For a bounded linear operator T on a separable complex infinite dimensional Hilbert space $\mathcal{H}$, we say that T is a quasi-class (A, k) operator if $T^{*k}|T^2|T^k\;{\geq}\;T^{*k}|T|^2T^k$. In this paper we prove that if T is a quasi-class (A, k) operator and f is an analytic function on an open neighborhood of the spectrum of T, then f(T) satisfies Weyl's theorem. Also, we consider the tensor product for quasi-class (A, k) operators.

• Information and Communications Magazine
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• v.34 no.2
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• pp.27-33
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• 2017

최근 IoT 기술이 홈케어, 헬스케어, 자동차, 교통, 농업, 제조업 등 다양한 분야에 적용되면서 신성장 동력의 핵심으로 IoT 서비스를 제공하거나 IoT 환경을 자체적으로 구축하여 산업현장에 도입하려는 기업이나 기관이 증가하고 있다. 그러나 IoT 환경은 인터넷을 통해 현실세계와 IoT 디바이스가 직접 연결되는 특성으로 인해서 IoT 보안의 중요성이 더욱 강조되고 있으며 IoT를 이용한 보안 사고 사례 및 취약점이 지속적으로 발표되면서 IoT 보안 위험 또한 계속 증가되고 있다. 이렇게 IoT 환경에는 많은 취약점과 보안 위협이 존재하기에 IoT 제품의 최초 설계/개발 단계부터 배포/설치/구성 단계, 운영/관리/폐기 단계까지 IoT 제품 및 서비스의 각 단계별로 보안 요구사항과 가이드라인을 적용하여 보안을 내재화하고 IoT 제품 및 서비스를 도입하는 사용자 입장에서 IoT 보안에 대해서 관심을 가지고 스스로 확인 할 수 있도록 보안 점검 기준이 필요하다. 본고에서는 IoT 디바이스의 특성과 보안 요구사항에 따른 보안 원칙 및 보안 가이드를 살펴보고 IoT 기술을 산업현장에 적용하고자 하는 기관/기업에 적용 가능한 IoT 디바이스의 보안 점검 기준을 제시한다.

• Journal of the Korean Mathematical Society
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• v.51 no.4
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• pp.791-815
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• 2014

We show amongst other that if $f,g:[a,b]{\rightarrow}\mathbb{C}$ are two functions of bounded variation and such that the Riemann-Stieltjes integral $\int_a^bf(t)dg(t)$ exists, then for any continuous functions $h:[a,b]{\rightarrow}\mathbb{C}$, the Riemann-Stieltjes integral $\int_{a}^{b}h(t)d(f(t)g(t))$ exists and $${\int}_a^bh(t)d(f(t)g(t))={\int}_a^bh(t)f(t)d(g(t))+{\int}_a^bh(t)g(t)d(f(t))$$. Using this identity we then provide sharp upper bounds for the quantity $$\|\int_a^bh(t)d(f(t)g(t))\|$$ and apply them for trapezoid and Ostrowski type inequalities. Some applications for continuous functions of selfadjoint operators on complex Hilbert spaces are given as well.

• Communications of the Korean Mathematical Society
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• v.33 no.4
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• pp.1141-1158
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• 2018

Hahn difference operator $D_{q,{\omega}}$ which is defined by $$D_{q,{\omega}}g(t)=\{{\frac{g(gt+{\omega})-g(t)}{t(g-1)+{\omega}}},{\hfill{20}}\text{if }t{\neq}{\theta}:={\frac{\omega}{1-q}},\\g^{\prime}({\theta}),{\hfill{83}}\text{if }t={\theta}$$ received a lot of interest from many researchers due to its applications in constructing families of orthogonal polynomials and in some approximation problems. In this paper, we investigate sufficient conditions for stability of the abstract linear Hahn difference equations of the form $$D_{q,{\omega}}x(t)=A(t)x(t)+f(t),\;t{\in}I$$, and $$D^2{q,{\omega}}x(t)+A(t)D_{q,{\omega}}x(t)+R(t)x(t)=f(t),\;t{\in}I$$, where $A,R:I{\rightarrow}{\mathbb{X}}$, and $f:I{\rightarrow}{\mathbb{X}}$. Here ${\mathbb{X}}$ is a Banach algebra with a unit element e and I is an interval of ${\mathbb{R}}$ containing ${\theta}$.

• Journal of applied mathematics & informatics
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• v.28 no.5_6
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• pp.1285-1304
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• 2010

The purpose of this paper is to establish some sufficient conditions for oscillation of solutions of the second-order functional dynamic equation of Emden-Fowler type $\[a(t)x^{\Delta}(t)\]^{\Delta}+p(t)|x^{\gamma}(\tau(t))|\|x^{\Delta}(t)\|^{1-\gamma}$ $sgnx(\tau(t))=0$, $t\;{\geq}\;t_0$, on a time scale $\mathbb{T}$, where ${\gamma}\;{\in}\;(0,\;1]$, a, p and $\tau$ are positive rd-continuous functions defined on $\mathbb{T}$, and $lim_{t{\rightarrow}{\infty}}\;{\tau}(t)\;=\;\infty$. Our results include some previously obtained results for differential equations when $\mathbb{T}=\mathbb{R}$. When $\mathbb{T}=\mathbb{N}$ and $\mathbb{T}=q^{\mathbb{N}_0}=\{q^t\;:\;t\;{\in}\;\mathbb{N}_0\}$ where q > 1, the results are essentially new for difference and q-difference equations and can be applied on different types of time scales. Some examples are worked out to demonstrate the main results.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.01a
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• pp.85-86
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• 2016

본 논문에서는 IoT 환경에서 IoT 게이트웨이를 통해 제공되고 있는 서비스 탐색 프로토콜에 대한 문제점을 분석하고 이를 해결하기 위한 해결방법에 대한 방향을 제시한다. 현재 다양한 IoT 서비스 탐색 프로토콜이 제안되어 있으며 제안된 서비스 탐색 프로토콜은 IP 기반 프로토콜과 non-IP 기반 프로토콜로 구분된다. 최근 IoT 기반 홈 네트워크 서비스 제공을 위해 스마트 IoT 게이트웨이가 개발되었다. 제안된 IoT 게이트웨이는 이종 네트워크 인터페이스에 대한 프로토콜 컨버팅 기능은 제공하고 있으나 서비스 탐색에 대한 홍보기능을 제공하고 있지 않다. 따라서 상이한 인터페이스로 구성된 IoT 디바이스에 대한 서비스 탐색 기능을 제공하지 못한다. 본 논문에서는 이런 문제점을 정의하고 이를 해결하기 위한 IoT 게이트웨이 내부 기능을 정의하고 추가적으로 공통 IoT 서비스 탐색 프로토콜 개발에 대한 방향을 제시한다.

• Korean journal of food and cookery science
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• v.31 no.4
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• pp.423-430
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• 2015

This study was carried out to investigate the effects of dandelion leaf, root and whole part extracts on the physicochemical characteristics of pork patties stored at $4^{\circ}C$ for 10 days. Four types of pork patties were evaluated: ice-water-added (T0), dandelion leaf extract (T1), dandelion root extract (T2) and dandelion whole part extract (T3). The pH decreased significantly during storage, but increased after 10 days of storage. The pH was highest in T0 during storage. The L value of T0 increased whereas T1, T2 and T3 did not significantly changed during storage. The a value decreased with a longer storage period, and the a values for T1, T2 and T3 were higher than that of T0 during storage. The b value did not change significantly during storage. The TBARS increased with a longer storage period, and the values for T0, T1, T2 and T3 were 0.87, 0.29, 0.47 and 0.31 mg MA/kg, respectively, after 10 days of storage. The VBN content value of T0 increased, but those of T1, T2 and T3 did not significantly change during storage. The water holding capacity of T0 decreased, but those of T1, T2 and T3 did not significantly change during storage. Cooking loss increased during storage and that of T0 was higher than those of T1, T2 and T3. Hardness and chewiness decreased while springiness and cohesiveness increased during storage.

• Journal of The Korean Society of Grassland and Forage Science
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• v.25 no.1
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• pp.23-32
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• 2005

This experiment was carried out to determine on the growth characteristics, yield and palatability in mono-cropping(T1; sorghum $\times$ sudagrass hybrid, T2; soybean) and inter-cropping[T3; sorghum $\times$ sudagrass hybrid(1) + soybean(2)]. The results obtained are summarizes follows; In plant length. leaf length, leaf width and stem diameter of sorghum $\times$ sudagrass hybrid(SSH). T3(1) was lower than T1 at 1st cutting time. But in 2nd and 3rd cutting time. T3(1) was higher than T1 Stem diameter of T2 was higher than soybean of T3(2). but plant length, leaf length and leaf width of T2 were higher than T3(1). The leaf ratio of SSH in T3(1) was higher than T1 in the first cutting time, but T3(1) was higher than T1 at 2nd and 3rd cutting time. The number of tiller of T1 was higher than SSH of T3(1) at 1st cutting time, but T3(1) was higher than T1 at 2nd and 3rd cutting time. Dead stubble rate of SSH in T3(1) showed a little lower value than T1. Dry matter and fresh yield of T1 was higher than T2 and T3. But protein yield of T3 was higher than T1 The palatability of 1st cutting time was 100.0. 76.8 and $18.5\%$ on T2, T3 and T1, respectively.

• Korean Journal of Mathematics
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• v.11 no.2
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• pp.117-125
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• 2003

Let $x(t)$ satisty $$(p(t)x^{\prime}(t))^{\prime}+q(t)x^{{\alpha}}(t)+r(t)x^{{\beta}-1}x^{\prime}(t){\leq}0({\geq}0)$$. Then the zeros of $x(t)$ or $x^{\prime}(t)$ are simple.

• East Asian mathematical journal
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• v.19 no.2
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• pp.251-259
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• 2003

The concepts of t-rational extensions and t-essential extensions of modules, where t a preradical for R-Mod, are introduced. The structures of such extensions are determined. Relations between maximal t-rational extensions and other concepts of modules are studied.