• 대한수학회논문집
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• 제30권4호
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• pp.363-377
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• 2015

Let R be a ring, (S,${\leq}$) a strictly ordered monoid and ${\omega}$ : S ${\rightarrow}$ End(R) a monoid homomorphism. The skew generalized power series ring R[[S,${\omega}$]] is a common generalization of (skew) polynomial rings, (skew) power series rings, (skew) Laurent polynomial rings, (skew) group rings, and Mal'cev-Neumann Laurent series rings. In this paper, we investigate the interplay between the ring-theoretical properties of R[[S,${\omega}$]] and the graph-theoretical properties of its zero-divisor graph ${\Gamma}$(R[[S,${\omega}$]]). Furthermore, we examine the preservation of diameter and girth of the zero-divisor graph under extension to skew generalized power series rings.

• 대한수학회보
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• 제56권4호
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• pp.841-852
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• 2019

We establish the generalized Myers theorem for Finsler manifolds under integral Ricci curvature bound. More precisely, we show that the forward complete Finsler n-manifold whose part of Ricci curvature less than a positive constant is small in $L^p$-norm (for p > n/2) have bounded diameter and finite fundamental group.

• 대한수학회논문집
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• 제11권1호
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• pp.109-115
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• 1996

A number of authors have generalized contraction mapping theorems in metric spaces. In this paper, we give some common fixed point theorems related with the diameter of the orbit on metric spaces. We generalize the results of M. Ohta and G. Nikaido [6], also Taskovic [8].

• Tribology and Lubricants
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• 제27권2호
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• pp.71-76
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• 2011

In this study, the nondimensional load capacity of water hydrodynamic journal bearings is calculated. A generalized coordinate formulation is applied to handle the complexity of bearing geometry. A window-based analysis program is developed to analysis the cylindrical hydrostatic bearings. Load capacities are calculated according to some design parameters such as clearance, diameter of orifice, size of recesses and temperature. The results are presented and discussed.

• Journal of applied mathematics & informatics
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• 제34권5_6호
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• pp.451-465
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• 2016

A Radio labeling of the graph G is a function g from the vertex set V (G) of G to ℤ⁺ such that |g(u) - g(v)| ≥ diam(G) + 1 - d_G(u, v), where diam(G) and d(u, v) are diameter and distance between u and v in graph G respectively. The radio number rn(G) of G is the smallest number k such that G has radio labeling with max{g(v) : v ∈ V(G)} = k. We investigate radio number for some families of generalized caterpillar graphs.

• Kyungpook Mathematical Journal
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• 제61권3호
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• pp.671-677
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• 2021

For a distance-regular graph with valency k, second largest eigenvalue r and diameter D, it is known that r ≥ $min\{\frac{{\lambda}+\sqrt{{\lambda}^2+4k}}{2},\;a_3\}$ if D = 3 and r ≥ $\frac{{\lambda}+\sqrt{{\lambda}^2+4k}}{2}$ if D ≥ 4, where λ = a₁. This result can be generalized to the class of edge-regular graphs. For an edge-regular graph with parameters (v, k, λ) and diameter D ≥ 4, we compare $\frac{{\lambda}+\sqrt{{\lambda}^2+4k}}{2}$ with the local valency λ to find a relationship between the second largest eigenvalue and the local valency. For an edge-regular graph with diameter 3, we look at the number $\frac{{\lambda}-\bar{\mu}+\sqrt{({\lambda}-\bar{\mu})^2+4(k-\bar{\mu})}}{2}$, where $\bar{\mu}=\frac{k(k-1-{\lambda})}{v-k-1}$, and compare this number with the local valency λ to give a relationship between the second largest eigenvalue and the local valency. Also, we apply these relationships to distance-regular graphs.

• International Journal of Precision Engineering and Manufacturing
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• 제2권2호
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• pp.65-72
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• 2001

The design of multi-stage gear drives is a time-consuming process, since on includes more complicated problems, which are not considered in the design of single-stage gear drives. The designer has th determine the number of reduction stages and the gear ratios of each reduction state. In addition, the design problems include not only the dimensional design but also the configuration design of gear drive elements. There is no definite rule and principle for these types of design problems. Thus the design practices largely depend on the sense and the experiences of the designer , and consequently result in undesirable design solution. We propose a new generalized design algorithm to support the designer at the preliminary design phase of multi-stage gear drives. The proposed design algorithm automates the design process by integrating the dimensional design and the configuration design process. The algorithm consists of four steps. In the first step, a designer determines the number of reduction stage. In the second step. gear ratios se chosen by using the random search method. In the third step, the values of basic design parameter are chosen by using the generate and test method. Then, the values of other dimension, such ad pitch diameter, outer diameter, and face width, are calculated for the configuration design in the final step. The strength and durability of a gear is guaranteed by the bending strength and the pitting resistance rating practices by using the AGMA rating formulas. In the final step, the configuration design is carried out b using the simulated annealing algorithm. The positions of gears and shafts are determined to minimize the geometrical volume(size) of a gearbox, while satisfying spatial constraints between them. These steps are carried out iteratively until a desirable solution is acquired. The propose design algorithm has been applied to the preliminary design of four-stage gear drives in order to validate the availability. The design solution have shown considerably good results in both aspects of the dimensional and the configuration design.

• Journal of Advanced Marine Engineering and Technology
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• 제37권8호
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• pp.886-892
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• 2013

고압호스 조립체는 건설기계, 선박, 항공기, 산업기계, 공작기계 및 자동차 등의 각종 유압장치에 널리 유압배관으로 사용된다. 이는 유연성이 필요한 부분에 유체동력($P^*Q$)으로 전달해야 함으로서, 고장이 발생할 경우는 유압시스템 전체가 작동이 불가능함으로서 신뢰성이 매우 중요한 부품이다. 가속 수명 시험 데이터는 와이블분포 분석을 통해서 형상 모수를 추종 하였다. 본 시험연구에서는 실제 가속수명시험 조건의 충격압력과 반복 굽힘을 변화시켜 시험시간을 감소시켰다. 가속수명시험 모형은 GLL(generalized linear)모형을 사용하였으며, 충격압력과 반복 굽힘에 대한 가속지수는 각각 6.64와 4.46으로 확인되었다. 또한 시험 결과에 대한 분석결과 형상모수(${\beta}$)는 6.19이며, 실제 사용조건인 35 MPa과 굽힘 반경 R100 mm를 적용하였을 경우 척도모수(${\eta}$)는 $1.035{\times}108$사이클로 확인되었다.

• 대한영상의학회지
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• 제81권3호
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• pp.632-643
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• 2020

목적 자기공명영상 근거 영상표현형과 생체분자학적 아형, 유전자 발현 프로파일 근거 위험도 등 유방암 유전체 특징의 관계를 분석하고자 하였다. 대상과 방법 The Cancer Genome Atlas와 and the Cancer Imaging Archive에 공개된 자료를 이용하였다. 122개의 유방암의 자기공명영상에서 영상표현형이 추출되었다. 유전자 발현 프로파일에 따라 PAM50아형을 분류하고 위험도를 지정하였다. 영상표현형과 생체분자학적 특징의 관계를 분석하였다. 예측모델을 알아보기 위해 penalized generalized regression analysis를 이용하였다. 결과 PAM50아형은 maximum 2D diameter (p = 0.0189), degree of correlation (p = 0.0386), 그리고 inverse difference moment normalized (p = 0.0337)와 유의하게 관련이 있었다. 위험도 시스템 중에 GGI와 GENE70이 통계적으로 유의하게 8개의 영상표현형 특징을 서로 공유하였다(p = 0.0008~0.0492). Maximum 2D diameter가 두 위험도 시스템에서 가장 유의하게 관련있는 특징이었으나(p = 0.0139, p = 0.0008) 예측모델의 전반적인 연관 정도는 약했고 가장 높은 연관계수는 GENE70이 0.2171이었다. 결론 영상표현형 중에 maximum 2D diameter, degree of correlation, 그리고 inverse difference moment normalized가 PAM50 아형 그리고 GENE70과 같은 유전자 발현 프로파일 근거 위험도와 그 연관도는 약하였으나 유의한 관련을 보였다.

• 한국임상수의학회지
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• 제29권1호
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• pp.107-111
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• 2012

Three dogs (An 8 years-old intact female Poodle, a 7 years-old intact male Schunauzer, and an 8 yearsold Golden Retriever) were presented due to acute vomiting, dyspnea, and generalized weakness. Megaesophagus was confirmed through radiographic examination in all 3 dogs. Relative oesophageal diameter (ROD) was measured and results of ROD measurements showed the possibility of megaesophagus secondary to myasthenia gravis in three dogs. Thus we performed anticholinesterase test as screening test for myasthenia gravis. In all three dogs, esophageal diameter was reduced after neostigmine methylsulfate administration. For definite diagnosis of acquired myasthenia gravis, serum acetylcholine receptor antibody titer was measured, but definite diagnosis was confirmed only in one case. However, based on history, radiographic findings, anticholinesterase test, ROD measurement, other two cases were still suspected as megaesophagus secondary to myasthenia gravis. Treatment with pyridostigmine bromide was initiated in all dogs, and improvement of esophageal diameter was shown in all dogs. One dog was successfully managed for 15 months after initial treatment and, is still alive, but other two dogs were died shortly after initial treatment, because of severe aspiration pneumonia.