• Journal of the Korean Society of Safety
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• v.15 no.1
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• pp.100-105
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• 2000

Correlation between propagation of bush-type electrical tree and internal partial discharges(PD) was discussed. We used specimens with needle-plane electrode system made of LDPE(Low Density Polyethylene), observed inception and propagation of electrical tree by optical microscope interfaced with computer and investigated characteristics of phase resolved PD pulses accompanying with propagation of electrical tree. Electrical tree generally growed bush-type tree. PD data detected and analyzed were average discharge current and statistical operator of q-n, $\psi$- $q_{avg}$, $\psi$-n, ${\psi}-q_{max}$ distribution. Parameters used were skewness, kurtosis, average discharge phase, cross-correlation factor, asymmetry and etc. In generally, average discharge current had good linear relationship with propagation of bush type electrical tree on this experiment. Peak discharge magnitude and repetition rate were increased, but they had not good linear relationship.p.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.358-364
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• 2007

This paper suggests MPLS restoration method that use an aggregation tree. For the restoration of the MPLS network, this paper presents a scheme that reconstruct multiple path through aggregation tree that grow from many node to a target node. Contrary to a multicast tree where a message that send at one node is passed to a group of node, an aggregation tree is a tree that data is passed from many node to one destination node. Through an experiment we confirmed that the restoration scheme that uses aggregation tree shows taster speed comparing with the existing other restoration scheme.

• The KIPS Transactions:PartD
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• v.12D no.7 s.103
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• pp.965-978
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• 2005

There are many defects that cause the schedule and qualify problems during software development. This paper designs the opportunity tree framer work that removes and manages the schedule and quality problems as well. For the similar projects, we can estimate defects and prepare to solve them by using domain expert knowledge and the opportunity tree framework which can greatly improve the software process. This research provides solution of schedule defect problem and detection of defect and its causes that happen on software development.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.2
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• pp.82-102
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• 2008

Packet losses tend to occur during short error bursts separated by long periods of relatively error-free transmission. There is also a significant spatial correlation in loss among the receiver nodes in a multicast session. To recover packet transmission errors at the transport layer, tree-based protocols construct a logical tree for error recovery before data transmission is started. The current tree construction scheme does not scale well because it overloads the sender node. We propose a scalable recovery tree construction scheme considering these properties. Unlike the existing tree construction schemes, our scheme distributes some tasks normally handled by the sender node to specific nodes acting as repair node distributors. It also allows receiver nodes to adaptively re-select their repair node when they experience unacceptable error recovery delay. Simulation results show that our scheme constructs the logical tree with reduced message and time overhead. Our analysis also indicates that it provides fast error recovery, since it can reduce the number of additional retransmissions from its upstream repair nodes or sender node.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2060-2062
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• 1999

When the high voltage is applied on insulation materials that have voids and impurities inner one, then probability of electrical tree inception is increased at defects. Electrical tree gives a profit to degradation analysis, because it is possible to observe by eyes and provides electrical degradation step. And electrical tree is divided to three types in usual - tree type, bush type and chestnut type tree. But these three types are divided not by method of quantitative analysis but visual and experiential analysis. In this paper, three types of electrical tree were calculated by quantitative analysis using fractal mathematics and classified to fractal dimensions (FD). FD of tree types are 1.1$\sim$1.4, bush types are 1.4$\sim$1.6 and chestnut type trees have above 1.6 FD.

• Journal of the Korea Society of Computer and Information
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• v.12 no.4
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• pp.111-117
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• 2007

We present an efficient decoding scheme for Huffman codes in which we use a properties of canonical prefix tree. After Huffman tree is converted to canonical Huffman tree, we represent Huffman tree with minimum information using rules associated with values of nodes in canonical tree. The proposed scheme can reduce memory to store Huffman tree information while maintains the same Processing time. The memory size in order to represent tree information is 2h + 2klogn which is less than those of previous methods. But the number of search is similar to previously proposed techniques.

• Journal of the Korea Furniture Society
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• v.23 no.4
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• pp.479-484
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• 2012

Tree-ring dating can be used to date scientifically prehistoric timbers, historical buildings or woodcrafts. It gives a calendar year to each tree ring and produces the felling dates of logs or wood panels. In this study, we applied tree-ring dating to a medicine cabinet in Seoul Museum of History. We obtained tree-ring data from radial or cross section by taking photographs with a digital camera. The cabinet were dated A.D. 1821 to the last ring. It was about 50 year older than the previous medicine cabinets. Tree-ring patterns indicated that the origin of woods for the cabinet would be near Sorak mountains.

• International Journal of Computer Science & Network Security
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• v.21 no.7
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• pp.56-62
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• 2021

The surge in generic attacks execution against cipher text on the computer network has led to the continuous advancement of the mechanisms to protect information integrity and confidentiality. The implementation of explicit decision tree machine learning algorithm is reported to accurately classifier generic attacks better than some multi-classification algorithms as the multi-classification method suffers from detection oversight. However, there is a need to improve the accuracy and reduce the false alarm rate. Therefore, this study aims to improve generic attack classification by implementing two hybridized decision tree algorithms namely Naïve Bayes Decision tree (NBTree) and Logistic Model tree (LMT). The proposed hybridized methods were developed using the 10-fold cross-validation technique to avoid overfitting. The generic attack detector produced a 99.8% accuracy, an FPR score of 0.002 and an MCC score of 0.995. The performances of the proposed methods were better than the existing decision tree method. Similarly, the proposed method outperformed multi-classification methods for detecting generic attacks. Hence, it is recommended to implement hybridized decision tree method for detecting generic attacks on a computer network.

• Journal of Forest and Environmental Science
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• v.35 no.2
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• pp.115-120
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• 2019

There are many countries having a long history of exotic tree introduction from different countries and several countries including New Zealand, Brazil and Hungary have successfully introduced exotic trees. Korea's tree breeding program for introduction of exotic tree was originally started from 1924. Records reveal that hundreds of tree species were introduced from many countries and tested their germination and viability. About 415 introductions were eliminated since they had been introduced and tested. Subsequently, seven exotic trees that proved successful in trials and plantations have planted for afforestation. Simultaneously, several promising exotic trees are still under the test. In this paper, we will succinctly review and evaluate their comparative growth performance of the exotic trees in the plantation programs of the country to coping with climate change.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.01a
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• pp.287-288
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• 2021

본 논문에서는 macOS의 파일시스템인 HFS+의 B-tree구조를 디지털 포렌식의 관점에서 분석할 수 있는 기능을 갖춘 도구의 구현에 대하여 다룬다. HFS+ 파일시스템의 파일과 디렉토리에 대한 메타정보를 카탈로그 B-tree에서 구하여 디지털 포렌식 정보로 활용한다. HFS+파일시스템 포렌식 분석도구는 C/C++언어로 구현된다. 텍스트 기반의 명령행 프로그램으로 구현되며 macOS/Windows에서 터미널/명령프롬프트에서 각각 실행될 수 있도록 제작된다. 타임스탬프/파일크기/위치 등의 메타데이터의 파싱기능, 리프노드에 저장된 데이터를 이용한 파일/디렉토리 트리 구조의 재구성, B-tree구조에 의한 키워드 탐색 기능, 인덱스 노드 없이 B-tree 리프노드의 구성에 의한 파일/디렉토리 파싱/검색 기능 등이 구현된다.