• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.1
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• pp.122-128
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• 2016

The purpose of this study was to develop improved strength of an arm and a boom on over-load environment, which causes damage in the initial design statement. To develop improved strength of an excavator front group, we calculated load conditions using the MATLAB program, and using these conditions, we performed a structural analysis of an excavator front group for the maximum digging force condition. Finally we performed a topology optimization to reduce weights of an arm and a boom, and we re-modeled an arm and a boom based on the topology design results and re-performed the structural analysis. The strength of the re-design is higher than the initial design but its weight is almost the same as the initial design.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.8
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• pp.1-10
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• 1995

We have analyzed the reliability of failure models in circuit-switched networks. These models are grid topology circuit-switched networks, and each node transmits a packet to a destination node using a Flooding routing method. We have assumed that the failure of each link and node is independent. We have considered two method to analyze reliability in these models : The Karnaugh Map method and joint probability method. In this two method, we have analyzed the reliability in a small grid topology circuit switched network by a joint probability method, and comared analytic results with simulated ones. For a large grid enormous. So, we have evaluated the reliability of the network by computer simulation techniques. As results, we have found that the analytic results are very close to simulated ones in a small grid topology circuit switched network. And, we have found that network reliability decreases exponentially, according to increment of link or node failure, and network reliability is almost linearly decreased according to increment of the number of links, by which call has passed. Finally, we have found an interesting result that nodes in a center of the network are superior to the other nodes from the reliability point of view.

• Journal of Communications and Networks
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• v.9 no.3
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• pp.282-295
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• 2007

Due to the nature that high datarate leads to shorter transmission range, the performance enhancement by high datarate 802.11 WLANs may be degraded when applying high datarate to an 802.11 based multihop ad hoc network. In this paper, we evaluate, through extensive simulations, the performance of multihop ad hoc networks at multiple transmission datarates, in terms of the number of hops between source and destination, throughput, end-to-end delay and packet loss. The study is conducted based on both stationary chain topology and mesh topologies with or without node mobility. From numerical results on network performance based on chain topology, we conclude that there is almost no benefit by applying the highest datarate when the chain length is 6 hops or more. With node mobility in mesh topology, the benefit of using high datarate diminishes at even shorter number of hops. To explore the main reasons for this behavior, analyses on multihop end-to-end throughput and network k-connectivity have been conducted later in the paper, and correspondingly an auto-rate adaptation algorithm has been proposed.

• Honam Mathematical Journal
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• v.1 no.1
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• pp.27-34
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• 1979

근래(近來) Skorokhod는 확률론(確率論)의 극한문제(極限問題)와 관련(關聯)하여 모든 불연속함수공간(不連續函數空間)에 관(關)한 위상(位相)을 정의(定義)하였다. 본(本) 논문(論文)에서는 Skorokhod 수렴위상(收斂位相)을 쌍위상(雙位相)(bitopology)형(型)으로 일반화(一般化)하고 잘 알려져 있는 여러위상(位相)과 비교(比較)하여 다음과 같은 결과(結果)를 새로 얻었다. (정리(定理) 2-11); 공간(空間) X와 Y가 완비준거이가분공간(完備準距離可分空間) (Completdy quasi-metric separable space)이라면 쌍개수렴위상(雙槪收斂位相)(pairwise almost convergent topology)는 Skorokhod 쌍수렴위상(雙收斂位相) 보다 약(弱)하다. 그리고 (정리(定理) 2-12); 쌍(雙) graph 위상(位相)은 Skorokhod $J_1$-수렴위상(收斂位相)과 일치(一致)한다. 끝으로 주정리(主定理)인 (정리(定理( 3-1)과 (정리(定理) 3-2)에서 Skorokhod 쌍수렴위상(雙收斂位相)의 Compact성(性)에 관(關)한 필요충분조건(必要充分條件)을 밝혔다.

• The Transactions of the Korea Information Processing Society
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• v.4 no.9
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• pp.2235-2246
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• 1997

This paper presents an effective heuristic task scheduling algorithm for multiprocessor systems. To execute task scheduling effectively which is defined as an allocation of m's tasks onto n's processors(m > n), several problems almost at NP-hard should be cleaned up. The purpose of the task scheduling obtains the minimum execution time by mapping the tasks on a system topology or reduces the total execution time to give a minimum system topology. In order to solve this problem, in this paper, the task scheduling is done by redefining a task graph to a reconstructed task graph (RTG). An RTG is obtained by merging or copying nodes to equal the number of nodes on each level of the task graph to the number of processors of the system topology and then directly scheduled to the system topology. This method obtains a fast scheduling time and a simple scheduling method, and near-optimal execution time without executing steps such as the refinement step and the duplication step after the task scheduling.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.743-746
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• 2006

In this paper, we propose and analyze a new parallel computer topology, called the Fibonacci posterorder circulants. It connects ${\Large f}_x,\;n{\geq}2$ processing nodes, same the number of nodes used in a comparable Fibonacci cube. Yet its diameter is only ${\lfloor}\frac{n}{3}{\rfloor}$ almost one third that of the Fibonacci cube. Fibonacci cube is asymmetric, but it is a regular and symmetric static interconnection networks for large-scale, loosely coupled systems. It includes scalability and Fibonacci cube as a spanning subgraph.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.627-632
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• 2002

One main purpose of environmental monitoring after oil spill is developing ESI (Environmental Sensitivity) Maps. Environmental impacts caused by the spilt oil are strongly depending upon the coastal topology and geology. Monitoring all impacted shorelines is almost impossible; using high-resolution satellite images such as IKONOS greatly contributes to improve the efficiency of on-site researches, at the same time, reliability of ESI maps.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.1
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• pp.40-45
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• 2005

The concept of a intuitionistic fuzzy topology (IFT) was introduced by Coker 1997. The concept of a fuzzy retract was introduced by Rodabaugh in 1981. The aim of this paper is to introduce a new concepts of fuzzy continuity and fuzzy retracts in an intuitionistic fuzzy topological spaces and establish some of their properties. Also, the relations between these new concepts are discussed.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.10 no.2
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• pp.157-164
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• 2010

Up to now, in the area of fuzzy topology, almost all the researchers have investigated fuzzy continuities by using ordinary mappings. However, in this paper, we study continuities by using fuzzy mappings introduced by Demirci [2].

• Journal of the Korean Mathematical Society
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• v.45 no.1
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• pp.1-27
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• 2008

We introduce a new concept of convex spaces and a multimap class K having certain KKM property. From a basic KKM type theorem for a K-map defined on an convex space without any topology, we deduce ten equivalent formulations of the theorem. As applications of the equivalents, in the frame of convex topological spaces, we obtain Fan-Browder type fixed point theorems, almost fixed point theorems for multimaps, mutual relations between the map classes K and B, variational inequalities, the von Neumann type minimax theorems, and the Nash equilibrium theorems.