• 한국정보과학회논문지:시스템및이론
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• 제31권9호
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• pp.503-513
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• 2004

최근 분산 컴퓨팅 환경에서 데이타와 서비스의 복제는 통신비용의 감소, 데이타 가용성 증가, 그리고 단일 서버의 병목현상을 피하기 위해 필수적이다. 기존의 대표적인 복제 프로토콜로 네트워크를 논리적으로 구성하는 Tree quorum 프로토콜과 Grid프로토콜이 있다. Tree quorum프로토콜은 최선의 경우 가장 우수한 읽기 성능을 보이는 반면 트리의 높이가 증가할수록 노드의 수가 기하급수적으로 증가한다는 단점을 가지고 있다. Grid프로토콜은 읽기 동작에 있어 높은 가용성을 가지는 반면 고장이 없는 환경에서도 같은 읽기 및 쓰기 성능을 보이는 단점을 가지고 있다. 따라서 본 논문에서는 기존의 복제 프로토콜이 가지는 문제점을 해결하고, 대칭적 트리 구조를 이용하여 노드의 장애가 발생하는 환경에서도 우수한 성능을 갖는 복제 프로토콜을 제안한다. 제안된 복제 프로토콜은 Tree quorum 프로토콜에 비해 적은 저기 비용을 가지며, 적은 수의 노드 구성 환경에서도 높은 읽기 가용성을 가진다. 또한 응답시간 면에서도 우수한 성능을 보인다.

• Journal of Electrical Engineering and Technology
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• 제8권4호
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• pp.840-849
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• 2013

This paper presents a statistical approach to analyze electrical tree inception voltage, electrical tree breakdown voltage and tree breakdown time of unsaturated polyester resin subjected to AC voltage. The aim of this work was to show that Weibull and lognormal distribution may not be the most suitable distributions for analysis of electrical treeing data. In this paper, an investigation of statistical distributions of electrical tree inception voltage, electrical tree breakdown voltage and breakdown time data was performed on 108 leaf-like specimen samples. Revelations from the test results showed that Johnson SB distribution is the best fit for electrical tree inception voltage and tree breakdown time data while electrical tree breakdown voltage data is best suited with Wakeby distribution. The fitting step was performed by means of Anderson-Darling (AD) Goodness-of-fit test (GOF). Based on the fitting results of tree inception voltage, tree breakdown time and tree breakdown voltage data, Johnson SB and Wakeby exhibit the lowest error value respectively compared to Weibull and lognormal.

• 한국멀티미디어학회논문지
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• 제6권5호
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• pp.753-768
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• 2003

이 논문은 다차원의 특징벡터를 벡터 근사치로 표현한 후 색인 트리를 구성하여 검객의 효율을 높이는 VA(Vector Approximate)-트리를 제안한다. 이 논문에서 제안하는 VA-트리는 전체적인 색인구조의 저장 공간을 줄이기 위해서 VA-화일의 벡터 근사치 개념을 이용하여 데이터양이 증가해도 검색 성능이 저하되지 않도록 하는 트리 형태의 구조를 갖는다. VA-트리는 MBR 기반의 색인구조이지만 MBR간에 겹침이 발생하지 않는 분할 방법을 사용하여 검색 효율을 높인다. 제안하는 색인구조와 기존의 여러 다차원 색인구조와의 성능 평가를 통해 제안하는 방법의 우수함을 보인다.

• 한국조경학회지
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• 제27권4호
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• pp.143-150
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• 1999

The purpose of this research is to find som ways to model tree forms more efficiently in reference with surveying structural data and handling parameters in plant Editor of AccuRender, the AutoCAD-based rendering software adopting the procedural plant modeling technique. In case of modelling a new tree, because it is efficient to modify an existing tree data as a template, we attempted to classify 81 species' data from existing plant library including conifers and deciduous tree. According to the qualitative characteristics and quantitative parameters of geometrical and branching structure, 8 types of tree form were classified with factor and cluster analysis. Some critical aspects found in the distributions of standardized scores of parameters in each type were discussed for explaining the tree forms intuitively. For adaptability of the resulted classification and typical parameters, 10 species of tree were measured and modelled, and proved to be very similar to the real structures of tree forms. CG or CAD-based plant modelling technique would be recommended not only as a presentation tool but for planting design, landscape simulation and assessment.

• 한국조경학회지
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• 제27권2호
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• pp.19-28
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• 1999

This study quantified shading, evapotranspiration and windspeed-reduction effects of trees on use and cost of heating and cooling energy in two residential neighborhoods of Chuncheon different in tree cover. Annual savings per residence of heating energy were approximately 1,210 MJ(1%) and those of cooling energy, 130 kWh(10%) in study district 1 having tree cover of about 10% . For district 2 with tree cover of about 20%, annual heating and cooling savings were 2,130 MJ(2%) and 180 kWh(19%) per residence, respectively. Trees annually saved energy costs by approximately ￦31,000 ($26, $1=￦1,200) per residence in district 1 and by ￦49,000($41) in district 2. One tree taller than 3 m resulted in annual energy savings of ￦8,000($7) in the study districts. Energy savings by trees in district 2, which had higher tree cover by 10% difference than district 1, were about 2 times greater than those in district 1. This implies that more tree plantings could enhance energy saving effects. Of the total costs saved, 58% was attributed to windspeed reduction and 47%, evapotranspiration. However, shading increased energy costs by 5% due to tree plantings at the wrong locations. Full tree plantings on the west and north of buildings and avoidance of shade-tree plantings of use of solar-friendly trees on the south are recommended to increase building energy savings efficiently.

• 한국치위생학회지
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• 제17권4호
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• pp.613-620
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• 2017

Objectives: The purpose of this study is to investigate the antibacterial effect of Streptococcus mutans of tea tree ingredient. Methods: The experimental groups were each given with different concentrations (30 or 50 vol%) of tea tree prepared in saline solution. The control group applied only saline solution. The tea tree coating of the specimen were examined under a scanning electron microscope. For the antibacterial activity test of the tea tree, the contact angle of the tea tree- coated specimen's surface was analyzed. The antibacterial effect against Streptococcus mutans was determined by counting the colony forming units (CFU). The statical statics were evaluated by using one-way ANOVA and paired t-test. Results: The tea tree treated group of hydrophilic more than non treated group. Antibacterial experiments demonstrated that tee tree solution was effective against Streptococcus mutans. However there was no significant difference in depending solution concentration groups. Conclusions: The antimicrobial activity of the tea tree containing solution showed its potential for use as coating for denture and medical materials.

• Spatial Information Research
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• 제16권1호
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• pp.113-127
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• 2008

최근 모바일 환경의 급속한 발달로 이동 중인 사용자의 위치에 기반한 다양한 서비스가 가능하게 되면서 모바일 기기에서 지도를 처리하는 모바일 소프트웨어의 개발이 증대되고 있다. 본 논문은 지도를 처리하는 모바일 소프트웨어에서 성능을 결정짓는 가장 중요한 요소인 공간 인덱스를 효율적으로 구성하는 새로운 방법을 제시한다. 본 논문에서 제시하는 $AR^*$-tree는 기존의 $R^*$-tree를 변형하여 2차원 공간 데이터의 x축 및 y축에 면적 (a) 축을 추가하여 3차원 데이터를 저장한다. 그리고, 검색 시에도 면적 축에 대한 조건을 추가함으로써 작은 화면을 갖는 모바일 기기에서의 지도 가독성을 증대시키고 시간 효율성도 동시에 향상시킨다.

• 한국태양에너지학회 논문집
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• 제31권6호
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• pp.32-39
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• 2011

This study is about the installation of the solar cell modules. The solar cell modules are built by the tree-mimic structure, and the performance is compared with that of the flat-plate type solar cell module installation. The mathematical tree model, which was suggested by Fisher and Honda, is utilized to determine the location of the solar cell modules for the tree-mimic type. The experiment shows that the generated electric power of the flat-plate type is higher than that of the tree-mimic type by 30% for one month of July. This lower performance for the tree-mimic type comes from the shading effects among the solar cell modules. The theoretical calculation for the absorbed solar radiation on the two types of solar cell installation shows that the tree-mimic type is higher than the flat-plate type by 8.5%. The shading area for the tree-mimic model is calculated with time by using the 3D-CAD, which will be utilized for the optimization of the tree-mimic model in the future.

• 한국지능시스템학회논문지
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• 제21권6호
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• pp.698-704
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• 2011

본 연구는 전국 연안을 항해하는 선박의 대량의 위치정보를 실시간으로 수신하여 선박의 운항상태를 분석하는 교통분석시스템의 성능을 높이기 위한 연구를 목적으로 하고 있다. 특히 교통분석시스템에서 분석시 필요한 정보의 빠른 검색을 위하여 Quad-Tree와 R-Tree 자료 구조를 적용하여 설계하고 기존의 교통분석시스템과 본 연구를 통해 개선된 교통분석시스템과의 비교를 통해 성능의 개선을 실험으로 보여주는데 있다.

• Journal of the Korean Wood Science and Technology
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• 제47권6호
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• pp.700-708
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• 2019

To verify the possibility of using resistograph to estimate the age of big old living trees, we selected three Zelkova serrata and seven Pinus densiflora in Goesan. The mean diameters at breast height of Z. serrata and P. densiflora were 102 (92-116) cm and 80 (65-110) cm, respectively. The heights measured from the ground using a resistograph ranged at 1.2-4.3 m and 0.6-1.1 m for Z. serrata and P. Densiflora, respectively. The most appropriate needle speed to determine tree-ring boundaries for measuring ring width was 1500 r/min for both tree species. Alternatively, the suitable feed speeds for Z. serrata and P. densiflora were 50 cm/min and 150 cm/min, respectively. From the measured data, the mean numbers of tree rings of Z. serrata and P. densiflora were 57 (43-68) and 104 (93-124), respectively, and the mean tree-ring widths were 4.27 mm (3.18-5.09 mm) and 2.93 mm (2.32-3.34 mm), respectively. A comparison between the time series of tree-ring widths by resistograph and that from the local master chronologies tallied for the heartwood part. Finally, this study showed that resistograph can be used to estimate tree ages when a local master chronology is available.