• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.1
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• pp.187-194
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• 1996

In this paper, we propose regression neural networks based on regression trees. We map regression trees into three layered feedforward networks. We put multi feature split functions in the first layer so that the networks have a better chance to get optimal partitions of input space. We suggest two supervised learning algorithms for the network training and test both in single feature split and multifeature split functions. In experiments, the proposed regression neural networks is proved to have the better learning performance than those of the single feature split regression trees and the single feature split regression networks. Furthermore, we shows that the proposed learning schemes have an effect to prune an over-grown tree without degrading the learning performance.

• Proceedings of the KAIS Fall Conference
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• 2008.11a
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• pp.375-378
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• 2008

생태방음벽의 적합한 식물종은 최소한의 유지관리만을 통해 성장할 수 있는 식물을 선정하는 것이 매우 중요하다. 지상부의 성장이 억제되고, 지하부의 성장이 활발해야 하기 때문에 레볼센트리, 소나타, 페난트 등이 가장 적합한 식물종으로 판단된다. 코스모스의 경우는 발아율, 생명력, 번식력 등이 매우 좋으나 지하부의 성장이 다른 품종에 비해 약 35%이상 크게 성장하고 지하부의 성장이 50%미만이기 때문에 식생방음벽으로서는 적합하지 않다. 그리고 여러 조건을 충족할 수 있는 추후 실험이 이루어져야 할 것으로 사료된다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.285-288
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• 1998

Ultrasonic signal characteristics related with the growth of electrical trees in epoxy resin are examined under 67[Hz] ac voltage application along with a CCD camera and PD current method. The ultrasonic sensor with a resonant frequency of 200[Hz] supported by a mechanical spring is attached directly to the lower-side of plane electrode. The magnitude of Partial discharge and count rate of ultrasonic signals have been measured according to the tree growth from a needle tip in an epoxy sample.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1507-1508
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• 2006

XLPE 절연 전력케이블의 제조과정에서 발생하는 가교부산물을 제거할 목적으로 14주기노화를 실시하며, XLPE 절연체에 발생하는 수트리를 가속 발생 성장시킬 목적으로 가속수트리 열화를 실시한다. 22.9kV 트리억제형(TR CNCV-W) 케이블에 대하여 14주기노화 전과 후, 120, 240, 360일 가속수트리(AWTT) 후의 파괴전압을 분석하였다. 14주기노화는 상승효과와 감소효과가 비슷하게 작용하는 것으로 나타났으며, 240일 AWTT 이후에 노화가 가속되는 것으로 나타났다.

• Journal of Internet Computing and Services
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• v.10 no.5
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• pp.65-78
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• 2009

The most commonly adopted approach to find valuable information from tree data is to extract frequently occurring subtree patterns from them. Because mining frequent tree patterns has a wide range of applications such as xml mining, web usage mining, bioinformatics, and network multicast routing, many algorithms have been recently proposed to find the patterns. However, existing tree mining algorithms suffer from several serious pitfalls in finding frequent tree patterns from massive tree datasets. Some of the major problems are due to (1) modeling data as hierarchical tree structure, (2) the computationally high cost of the candidate maintenance, (3) the repetitious input dataset scans, and (4) the high memory dependency. These problems stem from that most of these algorithms are based on the well-known apriori algorithm and have used anti-monotone property for candidate generation and frequency counting in their algorithms. To solve the problems, we base a pattern-growth approach rather than the apriori approach, and choose to extract maximal frequent subtree patterns instead of frequent subtree patterns. The proposed method not only gets rid of the process for infrequent subtrees pruning, but also totally eliminates the problem of generating candidate subtrees. Hence, it significantly improves the whole mining process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.59-69
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• 1997

The growth and microstructural characterization of epitaxial yttrium silicide ($YSi_2$) on the (100)Si substrate are investigated. The $YSi_2$ film grow epitaxilly through the solid phase reaction during vacuum annealing above $400^{\circ}C$. The epitaxial relationships between the hexagonal $YSi_2$ film and the (100)Si substrate are [0001]$YSi_2$//[011]Si and [0001]$YSi_2$//[011]Si in the (1100)$YSi_2$//(100)Si plane relation. The YSi$_2$ film consists of the two types of domains which have two different azimuthal orientations making an angle of $90^{\circ}$ to each other. The two types of domains in the $YSi_2$film are equivalent in volume fraction and crystalline quality, which has been proved from the equivalent integrated intensities of (2201) asymmetric reflection of X-ray diffraction. The formation of a double -domain structure is discussed on the basis of geometrical matching at interface between the (1100)$YSi_2$ film and the (100)Si substrate, and growth model is proposed.

• Resources Recycling
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• v.23 no.1
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• pp.25-32
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• 2014

The purpose of this research is to develop a process and a system to collect, purify and reuse the residual quantity of trimethylgallium, used as a raw material, upon GaN epitaxial growth for LED from a metal organic chemical vapor deposition(MOCVD) equipment. This research reviews whether TMGa collected from the process can be used through a chemical and structural characteristics evaluation. As a result of analyzing the purity using ICP-MS and ICP-AES, 7N high purity (99.99999%) of TMGa was obtained. According to checking the structural change of TMGa through NMR analysis, TMGa having pure $(CH_3)_3Ga$ structure was obtained without structural change. For reliability review of the collected TMGa, u-GaN was deposited using the MOCVD process and an structural, optical and electrical characteristics evaluation was conducted. As a result, it was found out that the reuse was possible.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.1
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• pp.80-87
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• 2010

The method of function synthesis is essential when we control the systems not known their characteristic, by predicting the function to satisfy a relation between input and output from the given pairs of input-output data. In general the most systems operate non-linearly, it is easy to come about problem is composed with combinations of parameter, constant, condition, and so on. Genetic programming is proposed by one of function synthesis methods. This is a search method of function tree to satisfy a relation between input and output, with appling genetic operation to function tree to convert function into tree structure. In this paper, we indicate problems of a function synthesis method by an existing genetic programming propose four type of new improved method. In other words, there are control of function tree growth, selection of local search method for early convergence, effective elimination of redundancy in function tree, and utilization of problem characteristic of object, for preventing function from complicating when the function tree is searched. In case of this improved method, we confirmed to obtain superior structure to function synthesis method by an existing genetic programming in a short period of time by means of computer simulation for the two-spirals problem.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.2253_2254
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• 2009

무선 모바일 통신 시장의 성장에 따라 수동 소자로 구성된 모듈에 대한 관심이 높아지고 있다. 본 논문에서는 수동소자를 이용한 Wi-MAX용 트리플렉서를 설계하였다. 트리플렉서는 Wi-MAX의 RF Front-end단 앞부분에 연결되며, IEEE 802.16에 따른 2GHz, 3GHz, 5GHz 대역을 선택, 분리해주는 역할을 한다. 제안된 트리플렉서는 저역통과필터, 대역통과필터, 고역통과필터로 구성하였으며, 수동소자의 최소화로 인해 삽입손실 향상을 중점으로 설계하였다. 회로해석 결과, 각 대역별 (2/3/5GHz) 삽입손실은 각각 -0.5dB, -0.6dB, -0.4dB 였으며, 반사손실은 -20dB, -20dB, -12dB, 격리도는 -20dB, -24dB, -25dB의 특성을 보였다. 수동 소자의 최소화 설계로 인해 모듈 및 시스템의 저가화를 기대할 수 있다.

• Journal of KIISE:Information Networking
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• v.32 no.4
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• pp.543-550
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• 2005

Demand for better services in the Internet has been increasing due to the rapid growth of the Internet, and hence next generation routers are required to perform intelligent packet classification. For a given classifier defining packet attributes or contents, packet classification is the process of identifying the highest priority rule to which a packet conforms. A notable characteristic of real classifiers is that a packet matches only a small number of distinct source-destination prefix pairs. Therefore, a lot of schemes have been proposed to filter rules based on source and destination prefix pairs. However, most of the schemes are based on sequential one-dimensional searches using trio which requires huge memory. In this paper, we proposea memory-efficient two-dimensional search scheme using source and destination prefix pairs. By constructing binary prefix tree, source prefix search and destination prefix search are simultaneously performed in a binary tree. Moreover, the proposed two-dimensional binary prefix tree does not include any empty internal nodes, and hence memory waste of previous trio-based structures is completely eliminated.