• 한국재료학회지
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• 제18권11호
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• pp.577-582
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• 2008

Directional solidification experiments were carried out at $1-300\;{\mu}m/sec$ solidification rates in the single crystal superalloy, CMSX 10. The solid/liquid interface morphology changed from planar to dendritic, and the dendrite spacing became finer as the solidification rate increased. The pool size of the ${\gamma}/{\gamma}'$ eutectic, formed between dendrites, reduced as the solidification rate increased. The phase formation temperatures, such as the solidus, liquidus and eutectic, were estimated by differential scanning calorimetry (DSC) analysis. The morphology of the ${\gamma}/{\gamma}'$ phase, known to be eutectic, showed ${\gamma}'$ cells with a $\gamma$ intercellular network, and this ${\gamma}/{\gamma}'$ was composed of coarse and fine ${\gamma}/{\gamma}'$ regions. In this study, it is suggested that the ${\gamma}/{\gamma}'$ phase was a coupled peritectic.The solidification procedure of the ${\gamma}/{\gamma}'$ between dendrites is also discussed.

• 열처리공학회지
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• 제19권5호
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• pp.249-256
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• 2006

Structural studies have been performed on precipitation hardening found in $L1_2$ ordered ${\gamma}^{\prime}-Ni_3(Al,Ti)$ alloys using transmission electron microscopy. A uniform solid solution of ${\gamma}^{\prime}-L1_2$ ordered phase supersaturated with Ni can be obtained by solution annealing in a suitable temperature range. The ${\gamma}^{\prime}$ phase hardens appreciably by the fine precipitation of disordered ${\gamma}$. The shape of ${\gamma}$ precipitates formed during aging is initially spherical or round-cubic and grow into platelets as aging proceeds. High resolution electron microscopy revealed that the ${\gamma}$ precipitates are perfectly coherent with the matrix ${\gamma}^{\prime}$ as long as the ${\gamma}$-precipitates are plates. The loss of coherency initiates by the introduction of dislocations at the ${\gamma}/{\gamma}^{\prime}$ interface followed by the step formation at the dislocations. The ${\gamma}$ precipitates become globular after the loss of coherency. The strength of ${\gamma}^{\prime}-Ni_3(Al,Ti)$ increases over the temperature range of experiment by the precipitation of fine ${\gamma}$ particles. The peak temperature where a maximum strength was obtained shifted to higher temperature.

• 충청수학회지
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• 제32권2호
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• pp.245-250
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• 2019

In this paper, the notion of ${\gamma}$-operation on a supratopological space is introduced. We found that the ${\gamma}$-operation induces a supratopology (topology) containing a given supratopology. We also introduce the notions of (${\gamma}$, S)-continuous function and almost ${\Gamma}$-supracompact defined by ${\gamma}$-operation on a supratopological space and investigate some properties for such notions.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제17권2호
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• pp.145-150
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• 2010

In this paper, we introduce the concepts of faintly ${\gamma}$-continuity and extremely ${\gamma}$-closed graph. And we study characterizations of such functions and relationships between faintly ${\gamma}$-continuity and extremely ${\gamma}$-closed graph.

• Kyungpook Mathematical Journal
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• 제49권3호
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• pp.457-471
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• 2009

Let S = {a, b, c, ...} and ${\Gamma}$ = {${\alpha}$, ${\beta}$, ${\gamma}$, ...} be two nonempty sets. S is called a ${\Gamma}$-semigroup if $a{\alpha}b{\in}S$, for all ${\alpha}{\in}{\Gamma}$ and a, b ${\in}$ S and $(a{\alpha}b){\beta}c=a{\alpha}(b{\beta}c)$, for all a, b, c ${\in}$ S and for all ${\alpha}$, ${\beta}$ ${\in}$ ${\Gamma}$. An element $e{\in}S$ is said to be an ${\alpha}$-idempotent for some ${\alpha}{\in}{\Gamma}$ if $e{\alpha}e$ = e. A ${\Gamma}$-semigroup S is called an E-inversive ${\Gamma}$-semigroup if for each $a{\in}S$ there exist $x{\in}S$ and ${\alpha}{\in}{\Gamma}$ such that a${\alpha}$x is a ${\beta}$-idempotent for some ${\beta}{\in}{\Gamma}$. A ${\Gamma}$-semigroup is called a right E-${\Gamma}$-semigroup if for each ${\alpha}$-idempotent e and ${\beta}$-idempotent f, $e{\alpha}$ is a ${\beta}$-idempotent. In this paper we investigate different properties of E-inversive ${\Gamma}$-semigroup and right E-${\Gamma}$-semigroup.

• 대한수학회지
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• 제45권6호
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• pp.1647-1659
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• 2008

Let R be a ring with identity, X the set of all nonzero, nonunits of R and G the group of all units of R. First, we investigate some connected conditions of the zero-divisor graph $\Gamma(R)$ of a noncommutative ring R as follows: (1) if $\Gamma(R)$ has no sources and no sinks, then $\Gamma(R)$ is connected and diameter of $\Gamma(R)$, denoted by diam($\Gamma(R)$) (resp. girth of $\Gamma(R)$, denoted by g($\Gamma(R)$)) is equal to or less than 3; (2) if X is a union of finite number of orbits under the left (resp. right) regular action on X by G, then $\Gamma(R)$ is connected and diam($\Gamma(R)$) (resp. g($\Gamma(R)$)) is equal to or less than 3, in addition, if R is local, then there is a vertex of $\Gamma(R)$ which is adjacent to every other vertices in $\Gamma(R)$; (3) if R is unit-regular, then $\Gamma(R)$ is connected and diam($\Gamma(R)$) (resp. g($\Gamma(R)$)) is equal to or less than 3. Next, we investigate the graph automorphisms group of $\Gamma(Mat_2(\mathbb{Z}_p))$ where $Mat_2(\mathbb{Z}_p)$ is the ring of 2 by 2 matrices over the galois field $\mathbb{Z}_p$ (p is any prime).

• Journal of Radiation Protection and Research
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• 제26권3호
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• pp.287-290
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• 2001

The 9.17MeV gamma-rays from the $^{13}C(p,\;{\gamma})^{14}N,\;^{14}N({\gamma},\;{\gamma})^{14}N$ reactions were measured. The incident 9.17MeV gamma-ray was produced from the $^{13}C(p,\;{\gamma})^{14}N$ reaction at Ep=1.75MeV resonance. The 1.75MeV proton beam was accelerated using the 3MV SNU-AMS Tandetron and 1.7MV KIGAM Tandem accelerators. The enriched 13C target was $121{\mu}g/cm^2$ self-supporting foil, and we used liquid nitrogen as a resonant absorption target. We used a HP-Ge detector with 30% efficiency and less 2keV energy resolution. We developed new method to detect the scattered 9.17MeV gamma-ray from the nitrogen target by using the energy difference between the Doppler shifted gamma-ray from the $^{13}C(p,\;{\gamma})^{14}N$ reaction and the resonant absorbed and rescattered gamma-ray from the $^{14}N({\gamma},\;{\gamma})^{14}N$ reaction.

• 물과 미래
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• 제13권4호
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• pp.41-50
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• 1980

본 연구는 Gamma 분포의 이론적 검토와 이의 수공학에의 적용, 즉 Gamma 분포의 적합성 및 Gamma 모델에 의한 하천유량의 Simulation에 대한 연구와 검토를 행하는데 그 목적을 두고 있다. 분석에 있어서 우리나라 주요하천(낙동강, 한강 및 금강)의 월유량자료를 사용하였으며 분석을 간단하게 하기 위하여 자료를 Modular coefficient로 변환시켰다. 먼저 이변수 Gamma 분포형에 대한 월류량에의 적합성을 검정하였으며 이로부터 Gamma 분포형과 Monto Carlo 기법을 기초로 한 Gamma 모델에 의하여 월류량의 Simulation을 행하였다. 그 결과 기록치와 매우 근접한 Simulation 자료를 얻을 수 있었다.

• 호남수학학술지
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• 제40권1호
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• pp.93-108
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• 2018

In this paper, we introduce the notion of ($\xi$, ${\zeta}$)-soft ${\Gamma}$-hyperideals and ($\xi$, ${\zeta}$)-soft interior ${\Gamma}$-hyperideals of ${\Gamma}$-semihypergroups by a new approach called soft intersection (briefly, S. I.). It is proved that in regular ${\Gamma}$-semihypergroups the ($\xi$, ${\zeta}$)-soft ${\Gamma}$-hyperideals and the ($\xi$, ${\zeta}$)-soft interior ${\Gamma}$-hyperideals coincide. Further, we introduce the concept of ($\xi$, ${\zeta}$)-soft simple ${\Gamma}$-semihypergroup and characterize the simple ${\Gamma}$-semihypergroups in terms of ($\xi$, ${\zeta}$)-soft ${\Gamma}$-hyperideals and ($\xi$, ${\zeta}$)-soft interior ${\Gamma}$-hyperideals.

• Journal of Radiation Protection and Research
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• 제43권4호
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• pp.137-142
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• 2018

Background: Gamma-ray detectors having a thin window of a material with low atomic number can increase the true coincidence summing effects for radionuclides emitting X-rays or gamma-rays. This effect can make efficiency calibration or spectrum analysis more complicated. In this study, a Cu shield was tested as an X-ray filter to neglect the true coincidence summing effect by X-rays and gamma-rays in gamma-ray spectrometry, in order to simplify gamma-ray energy spectrum analysis. Materials and Methods: A Cu shield was designed and applied to an n-type high-purity germanium detector having an $X-{\gamma}$ summing effect during efficiency calibration. This was tested using a commercial, certified mixed gamma-ray source. The feasibility of a Cu shield was evaluated by comparing efficiency calibration results with and without the shield. Results and Discussion: In this study, the thickness of a Cu shield needed to avoid true coincidence summing effects due to $X-{\gamma}$ was tested and determined to be 1 mm, considering the detection efficiency desired for higher energy. As a result, the accuracy of the detection efficiency calibration was improved by more than 13% by reducing $X-{\gamma}$ summing. Conclusion: The $X-{\gamma}$ summing effect should be considered, along with ${\gamma}-{\gamma}$ summing, when a detection efficiency calibration is implemented and appropriate shielding material can be useful for simplifying analysis of the gamma-ray energy spectra.