• 대한수학회논문집
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• 제17권2호
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• pp.253-260
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• 2002

For an outer action $\alpha$ of a finite group G on a factor M, it was proved that H is a, normal subgroup of G if and only if there exists a finite group F and an outer action $\beta$ of F on the crossed product algebra M $\times$$_{\alpha}$ G = (M $\times$$_{\alpha}$ F. We generalize this to infinite group actions. For an outer action $\alpha$ of a discrete group, we obtain a Galois correspondence for crossed product algebras related to normal subgroups. When $\alpha$ satisfies a certain condition, we also obtain a Galois correspondence for fixed point algebras. Furthermore, for a minimal action $\alpha$ of a compact group G and a closed normal subgroup H, we prove $M^{G}$ = ( $M^{H}$)$^{{beta}(G/H)}$for a minimal action $\beta$ of G/H on $M^{H}$.f G/H on $M^{H}$.TEX> H/.

• 한국경영과학회지
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• 제17권3호
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• pp.137-158
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• 1992

We study the Multiple Product Single Facility Stockout Avoidance Problem (SAP). That is the problem of determining, given initial inventories, whether there is a multiple product single facility production schedule that avoids stockouts over a given time horizon. The optimization version of the SAP where stockouts are pnelized linearly is also studied. We call this problem the Weighted Stockout Problem (WSP). Both problems are NP-hard in the strong sense. We develop Mixed Integer Linear Programming (MIP) formulations for both the SAP and the WSP. In addition, several heuristic algorithms are presented and performances are tested using computational experiments. We show that there exist polynomial algorithms for some special cases of the SAP and the WSP. We also present a method to phase into a target cyclic schedule for infinite horizon problems. These can be used as a practical scheduling tool for temporarily overloaded facilities or to reschedule production after a disruption.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2000년도 추계학술대회 논문집
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• pp.165-173
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• 2000

Analytic models have been developed to solve integrated production-distribution problems in supply chain management (SCM). As one of major constraints in analytic models, capacity, which is the total operation time in this paper has mostly been known or disregarded assuming infinite capacity. Also, as major factors, machine processing time to fabricate or assemble a part or product at a certain machine center in production system and vehicle processing time to deliver a product to a customer by a certain vehicle in distribution system have been fixed and regarded as a static factor, But in the real systems significant differences exit between capacity and the required time to achieve the production-distribution plan and between processing time and consumed time to process a part or product. In this paper, capacity and processing times in the analytic model are considered as dynamic factors and adjusted by the results from independently developed simulation model, which includes general production-distribution characteristics. Through experiments, we obtain the more realistic solutions reflecting stochastic natures by performing the iterative analytic-simulation procedure.

• 전기학회논문지P
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• 제58권4호
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• pp.632-632
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• 2009

The purpose of this study is to present the range of defects mentioned in the Product Liability (PL) and to establish an objective basis and grounds for the analysis of accidents expected to happen by analyzing and presenting the external flame pattern and electrical characteristics of an LED streetlight lamp, a new lighting lamp. From the analysis of the cross-section of a cable carbonized by an external flame, it was observed that the wire's strand and insulation material had solidly adhered, and that greater voids were formed at the surface than at the center. Irregular carbide lumps were formed in the globe directly exposed to the flame, and the globe carbonized by the indirect flame showed characteristics that they had melted and flowed downward. It was found that the forward and backward resistances of the normal LED were approximately 1.74 [$M{\Omega}$] and 140 [$M{\Omega}$], respectively. The lamp burnt by the strong flame exhibited infinite forward and backward resistances and the LED did not emit light. The carbonized LED lamp was gray and exhibited fine delaminations. According to the Product Liability, a product defect signifies a simple product defect. Most of the defects were caused by the lack of stability, and the defect of the product itself occurred during the design and manufacture. The defects in warnings and markings include an insufficiency of handling manuals and warnings, expressive warranty violations, defective markings, etc. In order to prevent an accident resulting from a product, it is necessary to prepare safety warnings and documentation, establish clear-cut lines of liabilities, and subscribe insurances. However, it could be seen that important factors against the Product Liability were product improvement, response to compensation requests and law suits, credit restoration, etc.

• 대한수학회지
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• 제48권6호
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• pp.1125-1142
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• 2011

In this paper, we define some new sequence spaces of infinite matrices regarded as operators on $l_2$ by using algebraic properties of such the matrices under the Schur product multiplication. Some of their basic properties as well as duality and preduality are discussed.

• 대한수학회지
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• 제50권4호
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• pp.813-828
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• 2013

It is known that generalized free products of finitely generated nilpotent groups are conjugacy separable when the amalgamated subgroups are cyclic or central in both factor groups. However, those generalized free products may not be conjugacy separable when the amalgamated subgroup is a direct product of two infinite cycles. In this paper we show that generalized free products of finitely generated nilpotent groups are conjugacy separable when the amalgamated subgroup is ${\langle}h{\rangle}{\times}D$, where D is in the center of both factors.

• 산업경영시스템학회지
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• 제24권65호
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• pp.1-9
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• 2001

Enterprises confronted the Environment of infinite competition should be prepared to abrupt variations of management environment and have the ability to be changed in short term. It has to be studied, the control method of products that correspond to molt-functionalization and reduced product life which is caused by high-quality and varied customers demands. As a process control method, we must be able not only to control varies characteristic in a control at once but also to detected special values quickly for high-quality. In this paper a control method referred above is presented.

• 대한수학회논문집
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• 제34권2호
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• pp.573-583
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• 2019

This article studies the monotonicity, log-convexity of the modified Lommel functions by using its power series and infinite product representation. Some properties for the ratio of the modified Lommel functions with the Lommel function, sinh and cosh are also discussed. As a consequence, $Tur{\acute{a}}n$ type and reverse $Tur{\acute{a}}n$ type inequalities are given. A Rayleigh type function for the Lommel functions are derived and as an application, we obtain the Redheffer-type inequality.

• 한국엔터테인먼트산업학회논문지
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• 제13권5호
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• pp.47-57
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• 2019

신제품 혁신은 기업의 생존과 지속적인 성장의 핵심 요소다. 급변하는 시장 환경과 글로벌 무한 경쟁으로 혁신적인 신제품 개발의 중요성은 점점 커지고 있다. 국내 엔터테인먼트 산업 또한 경쟁의 강도가 높아지고 있어 많은 기업들이 글로벌 무한경쟁시대에서 지속적 경쟁우위를 확보하고자 혁신적인 신제품 개발에 집중하고 있다. 문제는 경쟁강도가 높아지고 아이돌 생산 시스템이 점점 고도로 발전할수록 기획 및 마케팅에 소요되는 비용은 점점 늘어난다는 것이다. 공정거래위원회에서 한 아이돌 그룹을 만드는 과정에서 드는 비용을 대략 10억 원 내외로 추산한 바 있고 몇몇 대형 기획사에서는 투자비용을 20~30억 원 내외라고 주장하고 있다. 린스타트업은 신제품 혁신 및 지속적인 경영을 위한 혁신 프레임으로 주목받고 있다. 린스타트업 이론을 적용하여 신제품 혁신을 주도하면서 지속적으로 성장하고 있는 국내기업들이 속속 등장하고 있지만 체계적인 관련 이론 및 사례 연구가 매우 제한적이다. 특히, 구체적 전략 수립에 도움을 줄 수 있는 사례연구는 드문 실정이다. 이에 본 연구는 신제품 혁신에 성공한 JYP 엔터테인먼트의 아이돌 스타 트와이스의 사례를 분석하여 실무적인 시사점을 제시하고자 하였다. 이론적으로는 린스타트업을 엔터테인먼트 산업 및 기업으로 확장하였고, 국내 엔터테인먼트 기업의 아이돌 발굴 및 육성에 관한 혁신전략 수립에 활용 가능한 기초 자료로써의 실무적 함의를 제시하였다는 점에서 본 연구의 의의가 있다.

• 대한수학회보
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• 제39권2호
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• pp.299-307
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• 2002

As a by-product of [5], we produce algebraic integers of certain values of quotients of Eisenstein series. And we consider the relation of $\Theta_3(0,\tau)$ and $\Theta_3(0,\tau^n)$. That is,we show that $$\mid$\Theta_3(0,\tau^n)$\mid$=$\mid$\Theta_3(0,\tau)$\mid$,\bigtriangleup(0,\tau)=\bigtriangleup(0,\tau^n)$ and $J(\tau)=J(\tau^n)$ for some $\tau\in\eta$.