• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.6
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• pp.1063-1068
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• 2016

Anomalous propagation echo is a kind of abnormal radar signal occurred by irregularly refracted radar beam caused by temperature or humidity. The echo frequently appears in ground-based weather radar due to its observation principle and disturb weather forecasting process. In order to improve accuracy of weather forecasting, it is important to analyze radar data precisely. Therefore, there are several ongoing researches about identifying the anomalous propagation echo with data mining techniques. This paper conducts researches about implementation of classification method which can separate the anomalous propagation echo in the raw radar data using naive Bayes classifier with various kinds of observation results. Considering that collected data has a class imbalanced problem, this paper includes SMOTE method. It is confirmed that the fine classification results are derived by the suggested classifier with balanced dataset using actual appearance cases of the echo.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.6
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• pp.665-670
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• 2014

A SVM is a kind of binary classifier in order to find optimal hyperplane which separates training data into two groups. Due to its remarkable performance, the SVM is applied in various fields such as inductive inference, binary classification or making predictions. Also it is a representative black box model; there are plenty of actively discussed researches about analyzing trained SVM classifier. This paper conducts a study on a method that is automatically detecting the line-shaped echoes, sun strobe echo and radial interference echo, using the SVM algorithm because the line-shaped echoes appear relatively often and disturb weather forecasting process. Using a spatial clustering method and corrected reflectivity data in the weather radar, the training data is made up with mean reflectivity, size, appearance, centroid altitude and so forth. With actual occurrence cases of the line-shaped echoes, the trained SVM classifier is verified, and analyzed its characteristics using the decision tree method.

• Proceedings of the Acoustical Society of Korea Conference
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• 1993.06a
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• pp.50-53
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• 1993

ISDN에 기초한 음성 서비스가 가능해지고 망이 점차 광대역 ISDN으로 진화함에 따라, ISDN 전화기의 송화자 에코의 적절한 규정이 필요하며, 이는 ISDN 전화기의 송화 및 수화음량정격 및 단말결합손실에 의해 좌우된다. 따라서, 전화기의 송화 및 수화음량정격이 규정되어질 경우, 에코가 없는 전화통화를 할 수 있는 단말결합손실의 규정이 필요하며, 실질적으로 이에 대한 규정은 가중 단말결합손실(weighted terminal coupling loss ; TCLw)과 에코 안정손실(stability loss)로 분류되어 규정될 수 있다. 본고에서는 이와 관련된 국제기준을 고찰하고, 국내기준의 제안과 단말결합손실 및 안정손실의 측정결과에 대해서 기술한다.

• Investigative Magnetic Resonance Imaging
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• v.3 no.2
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• pp.179-187
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• 1999

Purpose : This paper introduces a computationally inexpensive context-dependent classification of multi-echo MRI with Bayes compound decision model. In order to produce accurate region segmentation especially in homogeneous area and along boundaries of the regions, we propose a classification method that uses contextual information of local enighborhood system in the image. Material and Methods : The performance of the context free classifier over a statistically heterogeneous image can be improved if the local stationary regions in the image are disassociated from each other through the mechanism of the interaction parameters defined at he local neighborhood level. In order to improve the classification accuracy, we use the contextual information which resolves ambiguities in the class assignment of a pattern based on the labels of the neighboring patterns in classifying the image. Since the data immediately surrounding a given pixel is intimately associated with this given pixel., then if the true nature of the surrounding pixel is known this can be used to extract the true nature of the given pixel. The proposed context-dependent compound decision model uses the compound Bayes decision rule with the contextual information. As for the contextual information in the model, the directional transition probabilities estimated from the local neighborhood system are used for the interaction parameters. Results : The context-dependent classification paradigm with compound Bayesian model for multi-echo MR images is developed. Compared to context free classification which does not consider contextual information, context-dependent classifier show improved classification results especially in homogeneous and along boundaries of regions since contextual information is used during the classification. Conclusion : We introduce a new paradigm to classify multi-echo MRI using clustering analysis and Bayesian compound decision model to improve the classification results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.1253-1260
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• 2013

Eco-town development projects have often prevailed throughout the World to initiate the new form of sustainable development plans. As a future development type, the eco-town project shares underlying notions with sustainable development, which has been recently revised into a wider definition; (i) energy efficiency, (ii) climate adaptation, and (iii) socio-economic development. There are four types of eco-town projects based on its characteristics and aims depending on project sites, regions, or countries. This paper tried to demonstrate the types of eco-town projects and summarizes its strategy plans from each type. Many eco-town cases can be placed in one of types, however there cannot be strictly discrete classification by its complicated and composite characteristics of them. In conclusion, the analyzed types can be a useful strategy plan for pursuing further eco-town projects in domestic as well as in international regions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.10
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• pp.1965-1972
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• 1994

A standard on talker echo for ISDN telophone, mainly consisting of those on sending and receiving loudness ratings and terminal coupling loss(TCL), is necessary. Accordingly, if sending and receiving loudness ratings are pre-determined, we need a standard on TCL providing echo-free telephone communications to telephone users, and the standard can be classified into that weighted TCL($TCL_w$) and that on stability loss. In this paper, in order to make a national standard on TCL, based on users' perceived quality on a talker echo, we conducted user opinion tests on talker echo. From the results of correlation between echo and user opinion on quality and measurement on TCL of telephones, we proposed the standard as follows; we must preserve TCL_w of at least 40dB and stability loss of at least 10dB when overall loudness rating for ISDN telephone, sum of sending and receiving loudness ratings, is normalized to 10dB.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1293-1294
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• 2012

• Journal of Chest Surgery
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• v.34 no.1
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• pp.51-56
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• 2001

배경: 이상적인 판막의 개발이 있기 전에는 가능하다면 원래의 판막을 보수하는 것이 좋을 것이라는 생각이 당연하며 실제 임상연구가들은 기술적으로 가능하다면 판막재건술이 판막치환에 비해 대단히 좋은 임상경과를 취한다고 보고하고 있다. 그러나 판막 치환례에서 수술성적과 임상성적이 오히려 좋게 나타나는 경우 이유가 있을 것이고 그 근본원인은 심실의 기능에 따라 좌우되리라는 가설 하에 이를 규명하고자 하였다. 대상 및 방법: 순수승모판막폐쇄부전증으로 수술 받은 40명의 환자를 대상으로 하여 고전적 판막 치환술을 시행한 12례를 1군으로, 후엽을 보전한 18례를 2군으로 그리고 성형수술을 시행한 10례를 3군으로 나누어 수술전의 심에코 소견을 포함하여 입원시에 시행한 전신상태와 수술 후 4주 이내에 시행한 심에코도의 각종 지표를 시행하였다. 결과: 일반적인 환자의 상태변화로는 1군에 비해 2군, 3군에서는 더 나은 결과를 보였으나, 통계적인 차이는 발견할 수 없었다. 뉴욕 심장협회의 분류에 따라서는 수술전보다 많은 호전이 보였으나 세군간의 유의한 차이는 발견할 수 없었다. 심에코도에 따른 심기능을 비교한 바에 의하면 1군에서는 오히려 나빠졌으며 2군, 3군에서는 수술직후에는 술전에 비해 별 차이가 없으며 회복후에는 모든 지표에서 의미있는 호전을 발견할 수 있었으나, 구별분획에 있어 두 군간에는 수술전, 수술후, 회복후의 상호간의 통계적으로 의미 있는 차이는 발견되지 않았다. 결론: 심기능의 차이가 나므로 승모판막폐쇄부전증에 대한 수술로는 가능한한 판막 성형술이 좋고, 판막 성형술이 불가능한 변형이 많은 경우 판엽 일부를 보전이라도 하는 것이 좋다.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.564-572
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• 2012

Harmonic imaging is introduced in the present article and its principle and physical characteristics is described in contrast to conventional ultrasonic imaging. The principle of the conventional image which uses ultrasonic echoes reflected at the interfaces between tissues is presented, and the nonlinear ultrasonic propagation which results in harmonic components is conceptually described. The pulse inversion technique which effectively extracts the harmonic components from the ultrasonic echo signals is introduced, and the advantages of the constructed harmonic images are summarized comparing with those of conventional ultrasonic images. The harmonic images are classified according to the mechanism of harmonic production, and the typical harmonic images obtained from patients are presented in contrast to the corresponding sonograms. Clinical significance and prospects of harmonic imaging and the future research areas are discussed.

• Ecology and Resilient Infrastructure
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• v.8 no.2
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• pp.97-111
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• 2021

This study was conducted to develop a habitat type classification system and its map based on the ecological characteristics of species, spatial type, vegetation, topography, and geological conditions preferred by species. To evaluate the relationships between species and their habitats in Korean national parks, we prepared a classification standard table for systematic classification of habitat types. This classification system divides habitats into 6 low-level and 59 mid-level ecological classes based on habitat structure. The mid-level system divided forest ecosystems into 20 subtypes, stream and wetland ecosystems into 8 types, coastal ecosystems into 7 types, arable land into 6 types, development land into 9 types, and 1 type of marine ecosystem. A habitat classification map was drawn utilizing square images, detailed vegetation maps, and forest stand maps, based on the above habitat classification system, and it covered 1,461 plots spanning 21 national parks. The habitat classification system and survey protocol, which consider domestic habitat conditions, should be further developed and applied to habitat assessment, to enhance the utility of this study.