• Korea Trade Review
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• v.46 no.2
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• pp.281-299
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• 2021

This paper analyzes the feasibility of using machine learning methods to forecast the employment. The machine learning methods, such as decision tree, artificial neural network, and ensemble models such as random forest and gradient boosting regression tree were used to forecast the employment in Busan regional economy. The following were the main findings of the comparison of their predictive abilities. First, the forecasting power of machine learning methods can predict the employment well. Second, the forecasting values for the employment by decision tree models appeared somewhat differently according to the depth of decision trees. Third, the predictive power of artificial neural network model, however, does not show the high predictive power. Fourth, the ensemble models such as random forest and gradient boosting regression tree model show the higher predictive power. Thus, since the machine learning method can accurately predict the employment, we need to improve the accuracy of forecasting employment with the use of machine learning methods.

• Annual Conference on Human and Language Technology
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• 2018.10a
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• pp.19-22
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• 2018

본 논문에서는 기존 Stack Pointer Network의 의존 파싱 모델을 확장한 Bi-Stack Pointer Network를 제안한다. Stack Pointer Network는 기존의 Pointer Network에 내부 stack을 만들어 전체 문장을 읽어 dependency tree를 구성한다. stack은 tree의 깊이 우선 탐색을 통해 선정되고 Pointer Network는 stack의 top 단어(head)의 자식(child)을 선택한다. 제안한 모델은 기존의 Stack Pointer Network가 지배소(head)정보로 의존소(child)를 예측하는 부분에 Biaffine attention을 통해 의존소(child)에서 지배소(head)를 예측하는 방향을 추가하여 양방향 예측이 가능하게 한 모델이다. 실험 결과, 제안 Bi-Stack Pointer Network모델은 UAS 91.53%, LAS 90.93%의 성능을 보여주어 기존 최고 성능을 개선시켰다.

• The KIPS Transactions:PartC
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• v.17C no.1
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• pp.69-80
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• 2010

Wireless sensor networks (WSN) consisting of a large number of sensors aim to gather data in a variety of environments and are being used and applied to many different fields. The sensor nodes composing a sensor network operate on battery of limited power and as a result, high energy efficiency and long network lifetime are major goals of research in the WSN. In this paper we propose a novel tree-based clustering approach for energy efficient wireless sensor networks. The proposed scheme forms the cluster and the nodes in a cluster construct a tree with the root of the cluster-head., The height of the tree is the distance of the member nodes to the cluster-head. Computer simulation shows that the proposed scheme enhances energy efficiency and balances the energy consumption among the nodes, and thus significantly extends the network lifetime compared to the existing schemes such as LEACH, PEGASIS, and TREEPSI.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.56-65
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• 2009

This study was carried out to embody monitoring system of growing environments of fruit tree with Ubiquitous Sensor Network and to analyze various fruit qualities by the tree's vigor in the apple orchard located in Poonggi-eup, Yeongju-shi, Gyeongsangbukdo, Korea. The tree's vigor of apple trees was influenced to insolation, temperature, and humidity and it had influence on the weights, sugar contents and the quality(especially in mineral contents) of apples. The use of Ubiquitous Sensor Network will not only contribute to improve the quality of fruit by the offer of scientific fruit-cultivation method, but also to expand its application more and more.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9B
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• pp.751-759
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• 2008

Carrier Ethernet backbone network integrates distributed layer-2 based metro networks. In this networks, Multiple Spanning Tree Protocol (MSTP) has been uscd as a main routing protocol that allows multiple spanning trees in a network. A better routing protocol called IEEE802.1aq - Shortest Path Bridging (SPB) is recently proposed, that generates the shortest spanning tree per a destination node. As SPB provides a routing path per a destination node, there is no way to adapt network traffic at normal condition. If we are free from the principle of "a spanning tree per a destination node", we can achieve adaptive routing. Based on this philosophy, we propose a new spanning tree based protocol - Edge Node Divided Spanning Tree (ENDIST). ENDIST divides an edge node into sub-nodes as many as connecting links from the node and each sub-node generates a single shortest path tree based on SPB. Depending on network or nodal status, ENDIST chooses a better routing path by flow-basis. This added traffic engineering ability contributes to enhanced throughput and reduced delay in backbone networks. The simulation informs us that ENDIST's throughput under heavy load performs about 3.4-5.8 and 1.5-2.0 times compared with STP's and SPB's one respectively. Also, we verified that ENDIST's throughput corresponds to the theoretical upper bound at half of cases we investigated. This means that the proposed ENDIST is a dramatically enhanced and the close-to-perfect spanning tree based routing schemes.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.5
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• pp.1303-1315
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• 2012

In the draft of the IEEE 802.11s standard, a tree topology is established by the proactive tree-building mode of the Hybrid Wireless Mesh Protocol (HWMP). It is used for cases in which the root station (e.g., gateway) is an end point of the majority of the data connections. In the tree topology, the root or central stations (e.g., parent stations) are connected to the other stations (e.g., leaves) that are one level lower than the central station. Such mesh stations are likely to suffer heavily from contention in bottleneck links when the network has a high traffic load. Moreover, the dependence of the network on such stations is a point of vulnerability. A failure of the central station (e.g., a crash or simply going into sleep mode to save energy) can cripple the whole network in the tree topology. This causes performance degradation for end-to-end transmissions. In a connected mesh topology where the stations having two or more radio links between them are connected in such a way that if a failure subsists in any of the links, the other link could provide the redundancy to the network. We propose a scheme to utilize this characteristic by organizing the network into concentric tiers around the root mesh station. The tier structure facilitates path recovery and congestion control. The resulting mode is referred to as Tier-based Proactive Path Selection Mode (TPPSM). The performance of TPPSM is compared with the proactive tree mode of HWMP. Simulation results show that TPPSM has better performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.346-353
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• 2011

Routing schemes that service applications with various delay times, maintaining the long network life time are required in wireless sensor & actor networks. However, it is known that network lifetime and hop count of trees used in routing methods have the tradeoff between them. In this paper, we propose a Pareto Ant Colony Optimization algorithm to find the Pareto tree set such that it optimizes these both tradeoff objectives. As it enables applications which have different delay times to select appropriate routing trees, not only satisfies the requirements of various multiple applications but also guarantees long network lifetime. We show that the Pareto tree set found by proposed algorithm consists of trees that are closer to the Pareto optimal points in terms of hop count and network lifetime than minimum spanning tree which is a representative routing tree.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.405-408
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• 2016

Games like Go, Chess, Janggi have helped to brain development of the people. These games are developed by computer program. And many algorithms have been developed to allow myself to play. The person winning chess program was developed in the 1990s. But game of go is too large number of cases. So it was considered impossible to win professional go player. However, with the use of MCTS(Monte Carlo Tree Search) and CNN(Convolutional Neural Network), the performance of the go algorithm is greatly improved. In this paper, using CNN and MCTS were proceeding development of go algorithm. Using the manual of go learning CNN look for the best position, MCTS calculates the win probability in the game to proceed with simulation. In addition, extract pattern information of go using existing manual of go, plans to improve speed and performance by using it. This method is showed a better performance than general go algorithm. Also if it is receiving sufficient computing power, it seems to be even more improved performance.

• Journal of the Korea Society of Computer and Information
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• v.16 no.9
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• pp.107-114
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• 2011

Because of boost of communications devices furnishing diverse services and rapid expansion of mobile business, good use and management of the existing network system become very important. Also, offering service corresponding with user communication requirement grades which vary widely in each person, is vital for communication service provider. In this paper, SGOSST, a mechanism of efficient network construction with minimum cost for network QoS is proposed. In experiments, though spending 252.97% more execution times, our SGOSST QoS network consumed 5.11% less connecting costs than the network constructed by weighted minimum spanning tree method. Therefore our mechanism can work well for efficient operation and service providing in the network formed with users and communication devices of various service requirement grade as smart/mobile equipment.

• Journal of the Korea Society of Computer and Information
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• v.20 no.4
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• pp.87-93
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• 2015

Recently, an idea has been suggested in which members construct the network by sharing their surplus bandwidth of their own access point. This kind of network is called public-shared network. As an application, SVC video streaming delivery system on public-shared network has been proposed. To send video stream from the stream server to clients, a tree structure is constructed where the root is a stream server, internal nodes are sharable access points, and leafs are clients. The previous researches have focused on constructing the minimal sharable-bandwidth tree which can serve all video streaming requests using the minimal sharable bandwidth. In this paper, we have shown that the problem of constructing a tree structure with given sharable access points to serve maximal video streaming requests is NP-hard. We also have developed an efficient heuristic algorithm for this problem and evaluated experimentally our algorithm.