• 대한수학회보
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• 제60권5호
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• pp.1295-1298
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• 2023

It is known that the complex projective space ℂℙⁿ admits a spin structure if and only if n is odd. In this paper, we provide another proof that ℂℙ^2m does not admit a spin structure, by using a circle action.

• 충청수학회지
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• 제20권2호
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• pp.157-161
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• 2007

We show that there is an equivariant symplectic embedding of a two-torus with a nontrivial action into a symplectic manifold with a symplectic circle action if and only if the circle action on the manifold is non-Hamiltonian. This is a new equivalent condition for non-Hamiltonian action and gives us a new insight to solve the famous conjecture by Frankel and McDuff.

• East Asian mathematical journal
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• 제36권5호
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• pp.593-604
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• 2020

Let the circle act on a compact oriented manifold with a discrete fixed point set. At each fixed point, there are positive integers called weights, which describe the local action of S¹ near the fixed point. In this paper, we provide the author's original proof that only uses the Atiyah-Singer index formula for the classification of the weights at the fixed points if the dimension of the manifold is 4 and there are at most 4 fixed points, which made the author possible to give a classification for any finite number of fixed points.

• 대한수학회논문집
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• 제9권2호
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• pp.415-418
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• 1994

Let G be a compact Lie group and let $S^1$ denote the unit circle in $R^2$ with the standard metric. Since every smooth compact Lie group action on $S^1$ is smoothly equivalent to a linear action (cf. [3J TH 2.0), we may think of $S^1$ with a smooth G-action as S(V) the unit circle of a real 2-dimensional orthogonal G-module V.(omitted)

• 품질경영학회지
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• 제44권4호
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• pp.845-853
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• 2016

Purpose: This research is to find the general and somewhat prevailing problems in quality circle papers. Many quality circles try to benchmark awarded papers even though they may have common problems. By pointing out popular problems in papers, many quality circles hopefully could be guided to the right direction in working out improvement actions. Methods: Many papers awarded in national quality circle conferences are deeply analyzed to figure out common problems. 69 recent papers are analyzed step by step and the most important and frequently occurring problems in each step are indicated. Results: Many prevailing problems are found in each step of QC stories. Especially finding themes, Grasping status quo, Cause analysis, Setting targets, Development of and Implementing counter attacks are the most common areas that have problems. Conclusion: Some problems are already too popular to be recognized as problems. In this paper those problems are logically criticized and thereby right directions for future quality circle activities are proposed.

• 대한수학회논문집
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• 제36권4호
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• pp.829-833
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• 2021

We investigate the Möbius transformation action of PSL(2, ℝ) on the set of mutually distinct ordered triple points of ℝ ∪ {∞}.

• 수산해양기술연구
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• 제35권3호
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• pp.209-214
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• 1999

The turning circle of a ship is the path followed by her center of gravity in making a turn of 360$^{\circ}$degrees or more with helm at constant angle. But generally it means her path traced at full angle of the rudder. For the ordinary ship the bow will be inside and the stern outside this circle.It has been usually understood that the turning circle is not essentinally affected by ship's speed at Froude numbers less than about 0.30. However, it is recently reported that the speed provide considerable effects upon the turning circle in piloting many ships actually at sea. In this paper, the author analyzed what effects the speed could provide on the turning circle theoretically from the viewpoint of ship motions and examined how the alteration of the speed at Froude no. under 0.30 affect the turning circle actually, through experiments of actual ships of a small and large size.The main results were as follows.1. Even though ship's speed at Froude no. under 0.30, the alteration of the speed affects the turning circle considerably.2. When the full ahead speeds at Froude no. under 0.30 of small and large ships were increased about 3 times slow ahead speeds, the mean rates of increase of the advances, tactical diameters and final diameters of thease ships were about 16%, 21% and 19% respectively.3. When the full ahead speeds at Froued no. under 0.30 of small and large ships were increased about 3 times slow ahead speed, the mean rate of increase of the turning circle elements of large ships was greater 10% than that of small ships. 4. When the full ahead speeds at Froued no. under 0.30 of small and large ships were increased about 3times slow ahead speeds, the mean rates of increase of the tactical diameter and final diameter of thease ships were greater than that of the advances of thease ships. 5. When only alteration of speed or sip's head turning is the effective action to avoid navigational fixed hagards, reducing the speed is always more advantageous than increasing the speed in order to shorten fore or transverse distance.

• 수산해양기술연구
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• 제35권3호
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• pp.210-210
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• 1999

The turning circle of a ship is the path followed by her center of gravity in making a turn of 360$^{\circ}$degrees or more with helm at constant angle. But generally it means her path traced at full angle of the rudder. For the ordinary ship the bow will be inside and the stern outside this circle.It has been usually understood that the turning circle is not essentinally affected by ship's speed at Froude numbers less than about 0.30. However, it is recently reported that the speed provide considerable effects upon the turning circle in piloting many ships actually at sea. In this paper, the author analyzed what effects the speed could provide on the turning circle theoretically from the viewpoint of ship motions and examined how the alteration of the speed at Froude no. under 0.30 affect the turning circle actually, through experiments of actual ships of a small and large size.The main results were as follows.1. Even though ship's speed at Froude no. under 0.30, the alteration of the speed affects the turning circle considerably.2. When the full ahead speeds at Froude no. under 0.30 of small and large ships were increased about 3 times slow ahead speeds, the mean rates of increase of the advances, tactical diameters and final diameters of thease ships were about 16%, 21% and 19% respectively.3. When the full ahead speeds at Froued no. under 0.30 of small and large ships were increased about 3 times slow ahead speed, the mean rate of increase of the turning circle elements of large ships was greater 10% than that of small ships. 4. When the full ahead speeds at Froued no. under 0.30 of small and large ships were increased about 3times slow ahead speeds, the mean rates of increase of the tactical diameter and final diameter of thease ships were greater than that of the advances of thease ships. 5. When only alteration of speed or sip's head turning is the effective action to avoid navigational fixed hagards, reducing the speed is always more advantageous than increasing the speed in order to shorten fore or transverse distance.

• East Asian mathematical journal
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• 제35권3호
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• pp.357-363
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• 2019

Let the circle act on a compact almost complex manifold M with a non-empty discrete fixed point set. To each fixed point, there are associated non-zero integers called weights. A positive weight w is called primitive if it cannot be written as the sum of positive weights, other than w itself. In this paper, we show that if every weight is primitive, then the Todd genus Todd(M) of M is positive and there are $Todd(M){\cdot}2^n$ fixed points, where dim M = 2n. This generalizes the result for symplectic semi-free actions by Tolman and Weitsman [8], the result for semi-free actions on almost complex manifolds by the author [6], and the result for certain symplectic actions by Godinho [1].

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2007년도 추계 종합학술대회 논문집
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• pp.724-726
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• 2007

국내, 외 많은 기업들이 메세나 활동을 기업의 긍정적인 이미지 확보 및 조직 구성원 화합 등을 목적으로 활용하고 있다. 또한, 이러한 관련 영역에 대한 효과성을 측정하기 위한 연구도 동시에 진행되어 왔다. 그러나 그 측정이 포괄적이고 추상적으로 이루어지면서 심층적인 효과를 측정하기에는 무리가 있어왔다. 본 연구에서는 기업에서 진행하고 있는 주요 문화, 예술 교육 프로그램에 대해 고찰하고, 이와 연관된 메세나 활동의 효과 측정에 대해 분석했다. 이를 바탕으로 교육 효과 측정을 위한 기준으로서 대표성을 갖고 있는 요인을 추출하고자 시도했다. 이는 관련 교육 프로그램을 실질적으로 도입하기 위해 준비 중인 기업들에 있어 시사점을 갖고 있으며, 추후 연구에 있어서 이러한 기준과 효과 측정 방법에 대한 설정, 그리고 이에 대한 신뢰성을 높일 수 있는 계량적인 지표를 추가하는 것이 필요할 것이다.