• 한국임상수의학회지
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• 제33권2호
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• pp.107-112
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• 2016

The objective of this study was to determine potential contributing factors associated with biosecurity level of farrow-to-finish pig farms and to develop a classification tree model to explore how these factors related to each other based on prediction model. To this end, the author analyzed data (n = 193) extracted from a cross-sectional study of 344 farrow-to-finish farms which was conducted between March and September 2014 aimed to explore swine disease status at farm level. Standardized questionnaires with information about basic demographical data and management practices were collected in each farm by on-site visit of trained veterinarians. For the classification of the data sets regarding biosecurity level as a dependent variable and predictor variables, Chi-squared Automatic Interaction Detection (CHAID) algorithm was applied for modeling classification tree. The statistics of misclassification risk was used to evaluate the fitness of the model in terms of prediction results. Categorical multivariate input data (40 variables) was used to construct a classification tree, and the target variable was biosecurity level dichotomized into low versus high. In general, the level of biosecurity was lower in the majority of farms studied, mainly due to the limited implementation of on-farm basic biosecurity measures aimed at controlling the potential introduction and transmission of swine diseases. The CHAID model illustrated the relative importance of significant predictors in explaining the level of biosecurity; maintenance of medical records of treatment and vaccination, use of dedicated clothing to enter the farm, installing fence surrounding the farm perimeter, and periodic monitoring of the herd using written biosecurity plan in place. The misclassification risk estimate of the prediction model was 0.145 with the standard error of 0.025, indicating that 85.5% of the cases could be classified correctly by using the decision rule based on the current tree. Although CHAID approach could provide detailed information and insight about interactions among factors associated with biosecurity level, further evaluation of potential bias intervened in the course of data collection should be included in future studies. In addition, there is still need to validate findings through the external dataset with larger sample size to improve the external validity of the current model.

• 한국자원식물학회지
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• 제16권2호
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• pp.99-108
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• 2003

본 연구는 경기도 안성지역에 소재하는 노거수의 합리적인 보전 및 관리방안을 제시하기 위해 수행하였다. 안성지역에 분포하는 노거수는 총 6종으로 조사되었다. 주요 수종은 느티나무, 은행나무, 음나무, 참배나무, 취앙네, 소나무 등의 순으로 전형적 온대기후대에서 수명이 상대적으로 긴 수종들임을 알 수 있었다. 그 가운데 느티나무는 전체 수종 가운데 73.5%를 차지하여 가장 많이 분포하였다. 본 조사에서 나타난 노거수들의 흉고직경은 전체의 76.4%가 1.5 m 이상으로 나타났으며 수고는 10-14 m 범위가 47.1%를 차지하였다. 노거수의 추정연령 은 200∼299년 범위가 38.2%로 가장 높은 분포를 나타냈으며 500년 이상도 20.6%나 조사되었다. 또한 안성시 노거수의 64.7%는 민속신앙 또는 전설, 고사 등의 전승 유래를 지니고 있어 매우 중요한 생물 문화재적 가치를 지니고 있는 것으로 조사되었다. 안성 지역의 대부분 노거수에는 조류 및 착생식물 등의 생물이 함께 서식하고 있음이 조사되었다. 노거수에 대한 관리실태는 전체에서 98.3%가 병충해 및 가지절단 등과 같은 심각한 훼손상태로 방치되어 있는 것으로 나타났으며 전체 조사 노거수의 47.1%는 근원부 주변이 콘크리트 및 아스콘 등으로 포장되어 투수 및 통기조건이 매우 불량한 것으로 조사되었다. 또한 완전히 없어져 버린 노거수도 1종이 조사되었다.

• The Korean Journal of Ecology
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• 제14권1호
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• pp.25-38
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• 1991

Berchemia berchemiaefolia is a native a native rare plant which has been designating as the Natural Monument, No. 266, since 1980. The floristic composition, population structure and maintenance mechanism of the Berchemia berchemiaefolia forest were investigated in conjunction with the habitat consisted of the block field or screes. Through the present study, the authors found a new habitat of Berchemia berchemiaefolia in the northeastern slope on Mt. Kumdansan located at Hajeok-ri, Cheongcheon-myeon, Koesan-gun, chungbuk province. Gravels consisted of the block field belonged to granule, pebble and cobble as the range of grain size, $\Phi$=-1.5~6.6 values. The tree layer of Berchemia berchemiaefolia community was mainly composed of Quercus variabilis, Pinus densiflora and Q. serrata including Berchemia berchemiaefolia and of this community were similar to that of Q. variabilis. By the age distribution, it was considered that the community was a discontinued one as the pattern of distribution was a normal distribution type(N type). Phenological cycle including leafing, blooming and seed-bearing period between both sites of block field and valley or close canopy showed some differences. The seed production of Berchemia berchemiaefolia was 8, 655, 000 seeds/ha/year, but only 406, 000 seeds/ha/year of them were developed as saplings, and only 4 saplings were developed to mature trees.

• 마이크로전자및패키징학회지
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• 제31권2호
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• pp.45-53
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• 2024

The maintenance of semiconductor equipment is crucial for the continuous growth of the semiconductor market. System management is imperative given the anticipated increase in the capacity and complexity of industrial equipment. Ensuring optimal operation of manufacturing processes is essential to maintaining a steady supply of numerous parts. Particularly, monitoring the status of substrate transfer robots, which play a central role in these processes, is crucial. Diagnosing failures of their major components is vital for preventive maintenance. Fault diagnosis methods can be broadly categorized into physics-based and data-driven approaches. This study focuses on data-driven fault diagnosis methods due to the limitations of physics-based approaches. We propose a methodology for data acquisition and preprocessing for robot fault diagnosis. Data is gathered from vibration sensors, and the data preprocessing method is applied to the vibration signals. Subsequently, the dataset is trained using Gradient Tree-based XGBoost machine learning classification algorithms. The effectiveness of the proposed model is validated through performance evaluation metrics, including accuracy, F1 score, and confusion matrix. The XGBoost classifiers achieve an accuracy of approximately 92.76% and an equivalent F1 score. ROC curves indicate exceptional performance in class discrimination, with 100% discrimination for the normal class and 98% discrimination for abnormal classes.

• 전기전자학회논문지
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• 제23권4호
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• pp.1208-1217
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• 2019

풀-브리지 서브모듈은 MMC의 단위 시스템으로서 서브모듈에 대한 수명예측은 HVDC 시스템의 유지 보수와 경제성 확보 관점에서 매우 중요하다. 그러나 일반적으로 부품의 종류, 개수, 결합 상태만을 고려하는 수명 예측은 대상 시스템의 구동상태를 고려하지 않는 일반화 된 결과로 실제 시스템의 수명과 크게 차이가 발생할 수 있다. 따라서 본 논문에서는 풀-브리지 서브모듈의 동작 특성을 반영하기 위한 목적으로 고장나무를 설계하고 기본 사상의 고장률에 MIL-HDBK-217F를 적용하여 풀-브리지 서브모듈의 수명을 예측한다. 기존의 부품고장률 분석과 제안된 고장나무 분석에 의한 기대 수명을 비교하고, 풀-브리지 서브모듈의 여유율 적용 여부에 따른 수명을 비교한다.

• 한국콘텐츠학회논문지
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• 제15권12호
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• pp.24-34
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• 2015

시맨틱 웹의 발전과 함께 RDF 데이터에 대한 사용이 증가되고 있다. RDF 데이터는 트리플로 구성되어 있으며 질의 처리 시 높은 조인 비용이 요구된다. 실체 뷰는 질의 처리 비용을 감소시키는 기법으로 알려져 있다. 실체 뷰는 질의 처리의 결과 또는 중간 결과를 저장 공간 내부에 물리적으로 저장하여 질의 처리 시 전체 데이터베이스의 접근이 아닌 실체 뷰의 접근으로 질의를 처리한다. 본 논문에서는 이를 해결하기 위해 의사 결정 트리를 사용하여 실체 뷰를 선택한다. 제안하는 기법은 의사 결정 트리를 통해 질의 처리시간뿐만 아니라 실체 뷰의 크기 및 유지비용을 고려한다. 성능평가를 통해 제안하는 기법이 기존 기법에 비해 제한된 저장 공간에서의 실체 뷰는 증가하였고 동일 개수의 실체 뷰의 유지비용은 감소함을 보인다.

• 한국산학기술학회논문지
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• 제15권8호
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• pp.5333-5341
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• 2014

최근 실내공간정보 기반의 시설물 운영관리에 대한 관심이 고조되면서 BIM과 GIS를 연계한 시설물 유지관리에 대한 다양한 연구가 진행되고 있다. 특히 대용량 데이터에 대한 형상정보의 가시화 처리는 중요한 이슈로, 유지관리 시스템 운영에 중요한 요소이다. 따라서 본 연구는 GIS 기반 BIM 모델의 효과적 가시화 구현을 위하여 IFC 스키마 기반의 시나리오를 통한 공간인덱싱 알고리즘을 설계하고, OcTree 기법을 적용하여 공간인덱싱 알고리즘을 일부 구현하였다. 구현된 결과를 IFC 샘플데이터에 테스트한 후 최종적으로 BIM 데이터의 효과적 가시화를 위한 공간인덱싱 기법을 제안한다.

• Journal of Information Processing Systems
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• 제9권4호
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• pp.511-537
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• 2013

Numerous data intensive applications demand the efficient processing of a new type of query, which is called a progressive query (PQ). A PQ consists of a set of unpredictable but inter-related step-queries (SQ) that are specified by its user in a sequence of steps. A conventional DBMS was not designed to efficiently process such PQs. In our earlier work, we introduced a materialized view based approach for efficiently processing PQs, where the focus was on selecting promising views for materialization. The problem of how to efficiently find usable views from the materialized set in order to answer the SQs for a PQ remains open. In this paper, we present a new index technique, called the Dynamic Materialized View Index (DMVI), to rapidly discover usable views for answering a given SQ. The structure of the proposed index is a special ordered tree where the SQ domain tables are used as search keys and some bitmaps are kept at the leaf nodes for refined filtering. A two-level priority rule is adopted to order domain tables in the tree, which facilitates the efficient maintenance of the tree by taking into account the dynamic characteristics of various types of materialized views for PQs. The bitmap encoding methods and the strategies/algorithms to construct, search, and maintain the DMVI are suggested. The extensive experimental results demonstrate that our index technique is quite promising in improving the performance of the materialized view based query processing approach for PQs.

• Journal of Forest and Environmental Science
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• 제38권2호
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• pp.90-101
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• 2022

The study aims to assess composition, diversity and population indices of natural regeneration of woody species in Jebel El Gerrie forest reserve, Blue Nile State, Sudan. We conducted field work between December 2018 and January 2019. We used random sampling to collect vegetation data in the forest where we made a total of 90 circular sample plots (radius 17.84 m) and distributed them proportionally to the area of each of the four density-based vegetation classes of the forest i.e. high density (C1), medium density (C2), low density (C3) and crop land (C4). In each sample plot we identified all regenerating tree species and counted their regeneration frequencies. We calculated ecological metrics of regeneration frequency, density, abundance, richness, evenness, diversity and importance value index (IVI) and drew abundance rank curve. Results revealed that out of fifteen mature tree species present, natural regeneration of 8 species, which belong to 6 families, was observed. The relatively most frequently naturally regenerating and abundant species were Anogeissus leiocarpa and Combretum hartmannianum. Richness, evenness and diversity of regenerating species were 1.33, 0.82 and 1.7, respectively. One-way ANOVA (α=0.05) of mean regeneration densities disclosed that there were significant differences (F_3,86=16.77, p=0.000) between C2 & C3 (p=0.000) and C2 & C4 (p=0.000). While regeneration of seven tree species were absent, two, two and four species were of good, poor and fair regeneration status, respectively. A comparison of mean density of natural regeneration with that of parent trees reflects a poor regeneration status of the forest. The study provides empirical results on the regeneration status of species and signifies the need for management interventions for species conservation and restoration, maintenance of biodiversity and sustainable production.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1278-1282
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• 2009

In apartment type of housing, if resident's vehicle is registered in central control office and RFID TAG is issued, identification can be recognized from the time of entrance into parking lot and intelligent parking guide system can be activated based on the residents' profile. Parking Guide System leads a vehicle to the available parking space which is closest to the entrance gate of the vehicle's owner. And when residents forget where they parked their cars, they can query to the Parking Guide and Management System and get responses about the location. For the correct operation of this system, it is necessary to find out where the residents' cars have parked in real time and which lot is available for parking of other cars. RFID is very fancy solution for this system. RFID reader gathers the ID information in RFID TAGs in parked cars and updates the DB up to date. But, when non-residents' cars are parked inside apartment, RFID reader cannot identify them nor know the exact empty/occupied status of parking spaces because they don't react to RFID reader's query. So for the exact detection of empty/occupied status, we suggest the combined use of ultrasonic sensors and RFID. We designed a tree topology with intermediate data aggregators. The depth of tree is normally more than 3 from root (central office) to leaves (individual parking lots). The depth of 2 in tree topology brings about the bottleneck in communication and maintenance. We also designed the information fields used in RFID networks and Sensor Networks.