• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.341-345
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• 2010

WMN is one of efficient solutions to provide Internet services for users by forming wireless backbone networks with wireless links. The dominant technology for WMNs is the IEEE 802.11, which provides multi-channel and multi-rate capabilities. One of important issues in WMNs is the network capacity and it is essential to design a multi-channel protocol that leverages the network capacity. However, when wireless links that use different data rates operate on the common channel, the performance of high-rate links is severely degraded by the presence of the low-rate links, which is often referred as performance anomaly. In this paper, we propose a Tree-based Channel Assignment (TreeCA) protocol to mitigate the performance anomaly problem by distributing data rates over multiple channels. TreeCA performs channel assignments based on the tree WMN architecture to accommodate the Internet traffics efficiently. Parent nodes on the tree distribute their child nodes over multiple channels so that the performance anomaly is reduced. Through simulations, we observed that the proposed TreeCA outperforms the existing multi-channel protocols for WMNs.

• Journal of Korean Society of Forest Science
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• v.96 no.3
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• pp.251-258
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• 2007

Airborne Lidar (light detection and ranging) can be an effective alternative in forest inventory to overcome the limitations of conventional field survey and aerial photo interpretation. In this study, we attempt to develop methodologies to identify individual trees and to estimate tree height from airborne Lidar data. Initially, digital elevation model (DEM) data representing the exact ground surface were generated by removing non-ground returns from the multiple-return laser point clouds, obtained over the coniferous forest site of rugged terrain. Based on the canopy height model (CHM) data representing non-ground layer, individual tree heights are extracted through pseudo-grid method and moving window filtering algorithm. Comparing with field survey data and aerial photo interpretation on sample plots, the number of trees extracted from Lidar data show over 90% accuracy and tree heights were underestimated within 1.1m in average at two plantation stands of pine (Pinus koraiensis) and larch (Larix leptolepis).

• Journal of KIISE
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• v.42 no.4
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• pp.512-521
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• 2015

Internet users purchase goods on the Internet and express their positive or negative emotions of the goods in product reviews. Analysis of the product reviews become critical data to both potential consumers and to the decision making of enterprises. Therefore, the importance of opinion mining techniques which derive opinions by analyzing meaningful data from large numbers of Internet reviews. Existing studies were mostly based on comments written in English, yet analysis in Korean has not actively been done. Unlike English, Korean has characteristics of complex adjectives and suffixes. Existing studies did not consider the characteristics of the Internet language. This study proposes an emotional classification method which increases the accuracy of emotional classification by analyzing the characteristics of the Internet language connoting feelings. We can classify positive and negative comments about products automatically using the Internet emoticon. Also we can check the validity of the proposed algorithm through the result of high precision, recall and coverage for the evaluation of this method.

• Journal of the Korean Society for information Management
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• v.25 no.3
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• pp.143-158
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• 2008

This study was conducted under the premise of providing the model for the construction of the library and the digital library in PUST, the joint construction from South and North Korea. First, we determined the problems in the construction of digital libraries as well as possible issues that may rise from the construction of the digital library in PUST. The results of the research showed that there were imminent problems from the operation of a digital library with the inadequate progress in the Held of copyright. In addition, the difference in the language system and the knowledge foundations of the two countries will produce problems in the homepage access, database construction, and information retrieval. In order to overcome these predictable problems, this research proposes the following: (1) parallel operation of both digital and high-drive libraries; (2) duplexing the homepage through the application of unicode concerning the digital library; (3) development and application of converted letter codes through the establishment of NCHAR data type; and (4) construction of an authority database.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.22 no.2
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• pp.137-143
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• 2004

The electronic distance measurement(EDM) instrument, introduced first in the 1950s since those early days has, undergone continual refinement. Rapid advances established in related technologies have made it lighter, smaller and more precise equipment. Understanding for the principle, the standardized observation technique and the precision of EDM instrument is mostly important to improve the quality and the reliability of by-product in the field of engineering and industrial surveying. Periodical and accurate calibration is necessary to maintenance the precision of EDM instrument. This paper describes the calculated example of zero error and scale error as a correction of EDM by applying the least square method to baseline observations in test area. Also here we deal with the testing criteria for precision instrument testing according to different types of EDM instruments.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.3
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• pp.299-304
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• 2010

Depending on the progress of the surveying and information processing technology, the rapidly developing field of spatial information and the 3D real world spatial information for a variety of content on the computer was able to easily access. In this research, to study on the spot or to use aerial photographs to measure trees of the acquired data, calculate the trees height, forest area and capacity, determine the distribution of the density of acquired points in the forest and analyze accurate and objective information was acquired. The United States, Canada and so on through the capacity of trees biomass, forest resource analysis, time series monitoring, wildfire behavior modeling and applied research and has been declared. During worldwide is increasing interest in forest resources. In nationally, extensive research and analysis of the forest consists of the correct management and protection of forest resources to be effective.

• KIISE Transactions on Computing Practices
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• v.21 no.3
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• pp.247-256
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• 2015

Since the Gulf War, air power has played a key role. However, the effect of high-tech weapons, such as laser-guided bombs and electronic optical equipment, drops significantly if they do not match the weather conditions. So, aircraft that are assigned to carry laser-guided bombs must replace these munitions during bad weather conditions. But, there are no objective criteria for when weapons should be replaced. Therefore, in this paper, we propose an algorithm to predict the hit rate of laser-guided bombs using cloud image processing. In order to verify the accuracy of the algorithm, we applied the weather conditions that may affect laser-guided bombs to simulated flight equipment and executed simulated weapon release, then collected and analyzed data. Cloud images appropriate to the weather conditions were developed, and applied to the algorithm. We confirmed that the algorithm can accurately predict the hit rate of laser-guided bombs in most weather conditions.

• Journal of KIISE
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• v.43 no.9
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• pp.1008-1014
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• 2016

Data such as Twitter, Facebook, and customer reviews belong to the informal document group, whereas, newspapers that have grammar correction step belong to the formal document group. Finding consistent rules or patterns in informal documents is difficult, as compared to formal documents. Hence, there is a need for additional approaches to improve informal document analysis. In this study, we classified Twitter data, a representative informal document, into ten categories. To improve performance, we revised and expanded features based on LDA(Latent Dirichlet allocation) word distribution. Using LDA top-ranked words, the other words were separated or bundled, and the feature set was thus expanded repeatedly. Finally, we conducted document classification with the expanded features. Experimental results indicated that the proposed method improved the micro-averaged F1-score of 7.11%p, as compared to the results before the feature expansion step.

• Magazine of the Korean Society of Hazard Mitigation
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• v.8 no.1
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• pp.48-52
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• 2008

대형태풍 카트리나가 준 주요 교훈 중의 하나는, 위험도 분석에 기반한 종합적인 재해경감 프로그램의 중요성이다. 미국에서는 이를 위해 다양한 위험도 분석(risk analysis) 프로그램 개발에 노력해 왔다. HAZUS(Hazarda-US) 프로그램은 대표적인 자연재해 예측 시스템으로서, 위험요인 파악(hazard identification), 지역사회의 취약성 분석(vulnerability of the society), 그리고 피해결과예측(loss estimation)의 세 가지 요소로 구성된다. 1992년 지진을 대상으로 개발된 이 프로그램은 현재, 지진 홍수 허리케인 윈드에 대해 피해예측을 할 수 있는 HAZUS-MH MR3가 사용 중에 있다. FEMA에서는 주정부에서 HAZUS를 활용, 피해 예측에 기반한 재해경감 정책을 추진할 수 있도록 다양한 재정적 기술적 지원을 하고 있다. 이에 따라, 2004년 머릴랜드 주에서는 미국 최초로 주 전역에 걸친 홍수피해 예측을 실히하고 이를 바탕으로 다양한 경감정책을 추진하였다. 머릴랜드 주정부에서 Salisbury 대학에 의뢰하여 수행한 홍수 피해 예측 과정은, 조사구역 및 위험요인(홍수) 결정, 사용 데이터 확정, 수문학적 분석, 수리학적 분석, 피해예측(건물 용도별 피해면적, 건물 용도별 피해액, 건물 재질별 피해면적, 건물 재질별 피해액, 지역의 경제학적 피해)의 과정으로 수행되었다. 홍수피해 예측 결과, 100년 빈도 홍수가 재현될 경우, 주 전체 면적 중 13%이상의 지역에서 약 80조 이상의 피해액이 예측됨에 따라, 종합적인 재해경감 대책의 필용성이 제기되었다. 이에 따라, 머릴랜드 주정부에서는 홍수피해예측 결과를 토대로, 주정부 재해경감 예산 재분배, 홍수터 보호, 건물규제 강화, 토지이용계획 재조정 등 보다 과학적이고 종합적인 재해경감 프로그램을 추진하였다. 머릴랜드 주정부의 이번 연구는 주정부로서는 최초로 HAZUS를 활용하여 주 전역에 걸친 피해예측을 실시한 것으로서, 피해예측 시스템이 어떻게 주정부의 과학적 피해경감 프로그램에 기여할 수 있는 지를 보여주는 사례이다.

• Journal of The Korean Association of Information Education
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• v.22 no.3
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• pp.345-356
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• 2018

The purpose of this paper is to analyze the elementary school students' level of computational thinking ability by analyzing the domestic question and examination results of Beaver Challenge 2017. Based on the results of the 'Challenge' results of Beaver Challenge 2017, the achievement by element, gender, and grade of elementary school students II (elementary school 3.4) and group III (elementary school 5.6) Respectively. As a result of the analysis, the achievement by the evaluation factors showed difference within each group. In addition, there was no significant difference in achievement according to gender except for one area of group II. The achievement level of each grade was statistically significant in the group III. The results of this study are expected to provide implications for the level of students related to what can be evaluated in elementary school information education and contribute to the follow-up research.