• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1661-1678
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• 2016

Clustering is one of the key technologies in vehicular networks. Constructing and maintaining stable clusters is a challenging task in high mobility environments. DWCM (Distributed and Weighted Clustering based on Mobility Metrics) is proposed in this paper based on the d-hop dominating set of the network. Each vehicle is assigned a priority that describes the cluster relationship. The cluster structure is determined according to the d-hop dominating set, where the vehicles in the d-hop dominating set act as the cluster head nodes. In addition, cluster maintenance handles the cluster structure changes caused by node mobility. The rationality of the proposed algorithm is proven. Simulation results in the NS-2 and VanetMobiSim integrated environment demonstrate the performance advantages.

• 농업과학연구
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• 제37권1호
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• pp.13-18
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• 2010

In order to prepare the technical fundamental in production of premium quality fruits of 'Niitaka' pears, we compared the quality parameters and storability of the fruits that had various fruit set position in a cluster. The fruits set on $4^{th}$ from basal part in fruit cluster had the largest fruit size. The weight of fruits set on the higher position than $4^{th}$ from basal part in fruit cluster showed decreasing tendency. The production rates of marketable fruits which had 500g to 899g in weight were the high in $3-5^{th}$ from basal part in cluster than those in other position. The differences of fruit height and diameter which represent balanced fruit shape also showed less difference in the fruits set on $4-5^{th}$ from basal part in cluster than the fruits set closely on basal part in cluster. The fruits set on $3-4^{th}$ from basal part in cluster showed lower rate in incidence of core breakdown and pithiness disorder during 4 months of cold storage than those on the closer position to basal part in cluster.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제4권3호
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• pp.337-340
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• 2004

The clustering problem can be formulated as the problem to find the number of clusters and a partition matrix from a given data set using the iterative or non-iterative algorithms. The author proposes a nearest neighbor and validity-based clustering algorithm where each data point in the data set is linked with the nearest neighbor data point to form initial clusters and then a cluster in the initial clusters is linked with the nearest neighbor cluster to form a new cluster. The linking between clusters is continued until no more linking is possible. An optimal set of clusters is identified by using the conventional cluster validity index. Experimental results on well-known data sets are provided to show the effectiveness of the proposed clustering algorithm.

• 한국환경과학회지
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• 제24권12호
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• pp.1673-1679
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• 2015

This study was conducted to investigate the effects of fruit set internode on the germination of watermelon seeds. Generally fruits setted in higher than 20 internode were high percent of germination, fruit setted in low internode(5-10) is low. The higher fruit-set internode, fruit weight was significantly increased, but 1,000 seed weight was decreased the more fruit set internode. However number of seed was about 300 seeds irrespective of fruit-set internode. Investigating viability of seed by BP test, general percent germination was recorded highest at 5 flower cluster above 20 internode of fruit-set internode. In contrast, condition of fruit setted on 3, 4, 6 flower cluster were high percent of germination, regarded as unnormal germination not to be as normal seedling by 2~3%. Seed harvested at 5 flower-cluster had high viability on hypocotyl height and diameter of seedling through early growth test, but were not significant. Therefore 5 flower-cluster was optimum fruit-set internode to obtain high-quality seed.

• Korean Journal of Mathematics
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• 제14권1호
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• pp.65-70
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• 2006

In this article, we mention some subsequent developments of the theory of cluster sets, and present a new boundary cluster set for a simply connected domain in the complex plane and its applications.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2806-2808
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• 2010

The structure of 3-aminophenol $(CO_2)_1$ cluster was computationally studied both in the ground and the lowest singlet excited electronic states. The ground state structure and binding energy of the cluster was investigated using the second-order M$\ddoot{o}$ller-Plesset perturbation theory (MP2) at the complete basis set (CBS) limit. The excited state geometry of the cluster was obtained at the second-order approximate coupled cluster (CC2) level with cc-pVDZ basis set, and the $S_0-S_1$ absorption spectrum was simulated by calculating Franck-Condon overlap integral. The ground state geometry of the global minimum with a very high binding energy of 4.3 kcal/mol was found for the cluster, due to the interaction between amino group and $CO_2$ in addition to the strong $\pi-\pi$ interaction between the aromatic ring and $CO_2$. The excited state geometry shows a very big shift in the position of $CO_2$ compared to the ground state geometry, which results in low intensity and broad envelope in the Franck-Condon simulation.

• 농업생명과학연구
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• 제46권1호
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• pp.105-111
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• 2012

본 연구는 딸기 '설향' 품종의 화방별 착과순서에 따른 과중 및 당도의 변화를 조사하여 각 화방별로 착과량 조절 기준의 타당성을 검정하고자 하였다. 1화방은 2, 3화방에 비하여 착과수, 과중, 당도, 대과성 과실의 비율이 높았다. 동일 화방 내에서도 상위 과실은 하위에 착과된 과실보다 과중이 증가하였고, 당도도 높았다. 과실의 과중이 증가할수록 당도가 증가하여 과중과 당도는 높은 정의 상관관계를 보였다. 설향 품종의 각 화방별 적정 착과수는 1화방 9~10개, 2화방 6개, 3화방 4개, 4화방 3개 정도 착과시키는 것이 상품수량을 증가시킬 수 있을 것으로 생각된다.

• Journal of Information Technology Applications and Management
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• 제26권1호
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• pp.53-64
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• 2019

The purpose of this study is to find out the fast delivery route that several drones return a truck again after departing from it for delivery locations at each cluster while the truck goes through the cluster composed of several delivery locations. The main issue is to reduce the total delivery time composed of the delivery time by relatively slow trucks via clusters and the sum of maximum delivery times by relatively fast drones in each cluster. To solve this problem, we use a three-step heuristic approach. First, we cluster the nearby delivery locations with minimal number of clusters satisfying a constraint of drone flight distance to set delivery paths for drones in each cluster. Second, we set an optimal delivery route for a truck through centers of the clusters using the TSP model. Finally, we find out the moved centers of clusters while maintaining the delivery paths for the truck and drones and satisfying the constraint of drone flight. distance in the two-dimensional region to reduce the total delivery time. In order to analyze the effect of this study model according to the change of the number of delivery locations, we developed a R-based simulation prototype and compared the relative efficiency, and performed paired t-test between TSP model and the cluster-based models. This study showed its excellence through this experimentation.

• 전자공학회논문지C
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• 제34C권7호
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• pp.51-60
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• 1997

Prototype based methods are commonly used in cluster analysis and the results may be highly dependent on the prototype used. In this paper, we propose a fuzzy clustering method that involves adaptively expanding convex polytopes. Thus, the dependency on the use of prototypes can be eliminated. The proposed method makes it possible to effectively represent an arbitrarily distributed data set without a priori knowledge of the number of clusters in the data set. Specifically, nonlinear membership functions are utilized to determine whether a new cluster is created or which vertex of the cluster should be expanded. For this, the membership function of a new vertex is assigned according to not only a distance measure between an incoming pattern vector and a current vertex, but also the amount how much the current vertex has been modified. Therefore, cluster expansion can be only allowed for one cluster per incoming pattern. Several experimental results are given to show the validity of our mehtod.

• 한국통신학회논문지
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• 제35권8A호
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• pp.810-819
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• 2010

본 논문에서는 환경 감시 등 무선 센서네트워크 응용을 위한 LEACH 프로토콜 기반의 망 수명 개선 알고리즘을 제안한다. 첫 째, LEACH 프로토콜에 따른 클러스터 구성시 각 클러스터에 노드 수를 균등하게 배분한다. 둘째, 클러스터 형성시 각 클러스터별로 헤더 역할을 담당할 노드의 순서를 설정한다. 이후, 정해진 순서에 따라 헤더가 일정 수의 패킷을 수신후 다음 노드에게 헤더 역할을 양도한다. 이렇게 함으로써 각 노드의 에너지 소비를 균등하게 하여 망 전체의 수명이 증대되도록 하였다. 시뮬레이션 결과 망 수명은 LEACH에 비해 두 배 증가하였고 망 전체의 에너지 소비는 1/4로 감소됨을 보여주었다.