• 대한수학회보
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• 제54권6호
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• pp.1883-1891
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• 2017

An optimally labelled graph of bandwidth 2 is an ordered pair (G, f) where G is a simple graph with bw(G) = 2 and $f:V(G){\rightarrow}[n]$ is a bijection such that bw(G, f) = 2. In this paper, the number of optimally labelled graphs of bandwidth two of order n is enumerated by counting linear forests.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.285-288
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• 1996

This paper deals with an (s, S) spare-part inventory model with general leadtime. In the model, if the inventory level falls to a reorder point s, a replenishment order quantity Q is ordered. Assumming that the number of operating units is one and the lifetime of a unit follows an exponential distribution, we derive the expected cost rate and suggest a procedure to obtain the optimal pair of (s, S) minimizing the cost rate.

• 대한수학회보
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• 제35권4호
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• pp.778-783
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• 1998

A pointed-group is an ordered pair (G,c) where G is a group and c is a specific element of G. Thus a pointed-group is a group together with a distinguish element. The aim of this paper is to generalize the result proved by R.C. Lyndon in [4], that every nilpotent group variety is finitely based for its laws.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제27권3호
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• pp.109-124
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• 2020

We establish coincidence point theorem for S-non-decreasing mappings under Geraghty-type contraction on partially ordered metric spaces. With the help of obtain result, we derive two dimensional results for generalized compatible pair of mappings F, G : X² → X. As an application, we obtain the solution of integral equation and also give an example to show the usefulness of our results. Our results improve, sharpen, enrich and generalize various known results.

• ETRI Journal
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• 제33권3호
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• pp.344-354
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• 2011

In this paper, a model is introduced named double relation chains (DRC) based on ordered sets. It is proved that using DRC and special relationships among the members of an alphabet, vectors of this alphabet can be stored and searched in a tree. This idea is general; however, one special application of DRC is the longest prefix matching (LPM) problem in an IP network. Applying the idea of DRC to the LPM problem makes the prefixes comparable like numbers using a pair of w-bit vectors to store at least one and at most w prefixes, where w is the IP address length. This leads to good compression performance. Based on this, two recently introduced structures called coded prefix trees and scalar prefix trees are shown to be specific applications of DRC. They are implementable on balanced trees which cause the node access complexity for prefix search and update procedures to be O(log n) where n is the number of prefixes. As another advantage, the number of node accesses for these procedures does not depend on w. Additionally, they need fewer number of node accesses compared to recent range-based solutions. These structures are applicable on both IPv4 and IPv6, and can be implemented in software or hardware.

• 품질경영학회지
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• 제24권1호
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• pp.44-49
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• 1996

This paper deals with a (Q, r) spare-part inventory model with gamma leadtime. In the model, if the inventory level falls to a reorder point r, a replenishment order quantity Q is ordered. Assumming that the number of operating units is one and the lifetime of a unit follows an exponential distribution, we derive the expected cost rate and suggest a procedure to obtain the optimal pair of (Q, r) minimizing the cost rate. A numerical example is presented to explain the model.

• Bulletin of the Korean Chemical Society
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• 제21권4호
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• pp.434-440
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• 2000

We present the results of computer simulation for the steady shear flows of rodlike molecules using nonequi-librium molecular dynamics simulation (NEMD) method. The model particle is a rigid rod composed of lin-early connected 6-sites and the Lennard-Jones 12-6 potential governs interactions between sites in different molecules. The system of rodlike molecules exhibits the change of orientational structure, that is, isotropic-nematic transition at high shear rates. We elucidate the nature of the ordered system developed from an isotro-pic phase by steady shear through an analysis of various quantities: orientational order parameters, orientational pair correlation functions, orientational distribution function, and snapshots of configurations. The effects of temperature and density on the shear rate dependence of orientational structure are described.

• 한국통신학회논문지
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• 제37B권10호
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• pp.938-946
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• 2012

간섭정렬(Interference Alignment : IA)은 높은 신호 대 잡음 비(Signal to Noise Ratio : SNR)에서 다중 사용자 간섭 채널에서 도달 가능한 최대 자유도를 얻을 수 있는 데이터 전송 기법이다. 그러나 대부분의 간섭정렬에 대한 연구는 네트워크 내의 모든 채널의 정보를 송, 수신단에서 완벽하게 알아야 하는 비현실적인 가정에 기반을 둔다. 본 논문에서는 K 사용자 다중안테나 간섭채널에서 간섭정렬을 위한 채널 상태 정보 (Channel-State Information : CSI)의 궤환 량을 효율적으로 감소시킬 수 있는 CSI 궤환 구조를 제안한다. 기존의 IA기법은 K의 2차함수의 형태로 궤환 오버헤드가 증가하는 반면, 제안된 궤환 구조는 송, 수신 단 사이에서 계산된 IA 송신기의 순차적인 교환을 통하여 K에 선형적으로 증가하는 오버헤드를 갖는다. 또한, 주어진 궤환 구조 하에서 제한된 궤환 채널에 의한 잔여 간섭의 세기를 분석하였으며, 이 때 발생하는 잔여 간섭을 최소화 할 수 있는 IA 조건, 즉, 주어진 채널환경에 따라 각 수신단에서 잔여 간섭을 최소화할 수 있는 최적의 IA 쌍을 순차적으로 결정하는 알고리즘을 제안한다.

• 대한수학교육학회지:학교수학
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• 제9권2호
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• pp.291-312
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• 2007

복소수의 취급이 처음으로 시작되는 제 10-단계 교과서들을 살펴본 결과 그 도입 방법은 모두 이차방정식 $x^2+1=0$을 만족하는 해를 생각하는 과정에서 새로운 수 i를 도입하여 사용하고 있다. 이 방법은 우선 새로운 수 i의 도입이 인위적이기 때문에 학생들이 도입과정에서 혼란스러워하며, 이차방정식을 잘 이해하지 못하는 학생들이 이해하도록 하게 하는 것이 어렵다. 이에 비하여 복소수 도입을 좌표평면 위의 점인 순서쌍과 화살표를 사용하여 도입하면 이차방정식을 이해하지 못한 학생들까지도 흥미를 갖고 학습에 임하게 할 수 있고, 또 수체계를 체계적인 확장으로 다룰 수 있어 학습 효과도 높일 수 있다. 그러나 고등학교 과정에 적합한 지도 내용의 개발이 없어서인지 고등학교에서 순서쌍을 사용한 복소수 도입은 시도되고 있지 않다. 여기서는 수체계의 확장 과정을 초등학교 과정부터 중학교과정을 거쳐 복소수 도입까지 연계되는 체계적이고 가시적인 표현을 통하여 학습할 수 있도록 지도 내용을 개발하였다. 그리고 이 내용으로 지도를 하여본 결과 개발된 학습내용으로 학습지도가 가능함을 알았고, 이 학습이 바람직한 학습임도 알 수 있었다.

• International Journal of Contents
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• 제13권3호
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• pp.25-31
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• 2017

With tremendous advancement of information and communication technologies, mobile learning systems have been widely adopted in language learning contexts, and several frameworks have been developed for identifying and categorizing different factors of mobile-assisted language learning (MALL). However, pre-existing frameworks have limitations when evaluating the importance level of criteria. The purpose of this study is to develop a comprehensive hierarchical framework for identifying and categorizing success factors of MALL and prioritizing them according to the importance level. To do that, AHP method is used to quantitatively estimate weight values of MALL criteria. Results reveal that the priority of MALL criteria is ordered as follows: content, system, learner, language learning. Local weights of each criterion are also analyzed; for example, usefulness, accuracy, and authenticity are critical factors for improving MALL contents. Ease of use and mobility of MALL systems are also considered more critical than other systematic factors. In addition, availability of immediate feedback and self-directness has the highest weight values of importance. The findings of the study are discussed regarding hierarchical orders of MALL criteria and conclude that successful MALL implementation may be achieved if related elements are diversely measured and evaluated. Pedagogical implications and suggestions for further research are also presented.