• Geomechanics and Engineering
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• 제14권2호
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• pp.107-113
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• 2018

Coal samples with different joints morphology were subjected to uniaxial compression experiments, cracks evolution was recorded by Nikon D5300 and acoustic emission (AE) energy signals were collected by AEwin Test for Express-8.0. During loading process, coal samples deformed elastically with no obvious cracks changes, then they expanded gradually along the trace of the original cracks, accompanied by the formation of secondary cracks, and eventually produced a large-scale fracture. It was more interesting that the failure mode of samples were all shear shape, whatever the original cracks morphology was. With cracks and damage evolution, AE energy radiated regularly. At the early loading stage, micro damage and small scale fracture events only induced a few AE events with less energy, while large scale fracture leaded to a number of AE events with more energy at the later stage. Based on the multifractal theory, the multifractal spectrum could explain AE energy signals frequency responses and the causes of AE events with load. Multifractal spectrum width (${\Delta}{\alpha}$), could reflect the differences between the large and small AE energy signals. And another parameter (${\Delta}f$) could reflect the relationship between the frequency of the least and greatest signals in the AE energy time series. This research is helpful for us to understand cracks evolution and AE energy signals causes.

• Safety and Health at Work
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• 제11권1호
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• pp.50-60
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• 2020

Background: The relationship between risk factors and likelihood of occupational injury has been studied. However, what has been published has only provided a limited explanation of why some of the employees working in the same environment as other employees suffered a single-injury event, while other employees experienced multiple-injury events. This article reports on an investigation of whether artisanal and small-scale miners in Migori County of Kenya are susceptible to a single-injury or multiple-injury incidences, and if so, what underpinning parameters explain the differences between the single incident injured and the multiple incident injured group. Mine management commitment to safety in artisanal and small-scale mining (ASM) operations is also considered. Materials and methods: The research objectives were achieved by surveying 162 uninjured and 74 injured miners. A structured, closed-end questionnaire was administered to participants after the stratification of the study population and systematic selection of the representative samples. Results: The results showed that most injured miners suffer a single-injury incident rather than experiencing multiple-injury events, and laceration (28.40%) was the common injury suffered by the miners. The analysis showed that the risk factors for the single incident injured group were not similar to those in the multiple incident injured group. The research also found mine workers have low opinion about mine management/owners commitment to safety. Conclusion: The study concluded that mine management and miners need to be educated and sensitized on the dangers of this operation. Provision of safety gears and positive safety culture must be a top priority for management.

• Safety and Health at Work
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• 제13권2호
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• pp.163-169
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• 2022

Background: It is estimated that about 13 million artisanal and small-scale miners carry out their activities under harsh, precarious, unfriendly, and risky conditions. Yet, our understanding of the extent to which these workers use personal protective equipment (PPE) and navigate through the various risks and hazards they face is still limited. This article has two main objectives. First, it explores the extent of usage of PPE among artisanal and small-scale miners for the prevention of hazards and risks. Second, it examines the coping strategies used by these miners as a response to experiences of occupational injuries and risks Methods: A cross-sectional survey of small-scale miners was conducted in six communities across three districts in Ghana, West Africa. The mixed methods approach was adopted. A total of 148 small-scale miners participated in the study. Six focus group discussions (FGDs) were held across the six communities. The data were analysed using descriptive statistics. Chi-square tests were used to analyse the relationship between some socio-demographic characteristics (sex, age, and educational background) and the usage of PPE. Open-ended questions and responses from FGDs were analysed based on the content and verbatim quotations from miners. Results: Findings suggest that 78% of the miners interviewed do not use the appropriate PPE citing reasons such as cost, and their personal discomfort associated with use of PPE. There was no significant relationship between socio-demographic characteristics (i.e., sex, age, education and major mining activity) and the usage of PPE. The study further revealed four main coping strategies used by miners to handle the risks. These are rest, taking unprescribed medication and hard drugs, registration with health insurance scheme and savings and investments. Conclusion: This study shows that very few artisanal miners use PPE despite the significant hazards and risks to which they are exposed. The study recommends to the government to put in place measures to ensure that miners adhere to health and safety regulations before undertaking mining activities. This means that health and safety plans and use of PPE should be linked to the license acquisition process for miners.

• 한국융합학회논문지
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• 제9권3호
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• pp.53-59
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• 2018

본 논문에서는 스마트 공장에서 의사결정 모델을 이용한 순차 마이닝 기반 제조공정을 제안한다. 제안하는 모델은 소규모의 제조공정에서 순차 마이닝 의사결정 모델을 적용하여 제조 효율을 높이는 방법이다. 제조 단계 중 제품 제조 과정에서 나타나는 데이터를 입력 변수들로 구성하고, 시간당 제조량과 불량률을 출력 변수로 구성한다. t-검정을 통해 유의수준이 높은 변수만을 사용하여 GSP 알고리즘과 REPTree 알고리즘을 이용한 규칙과 모델을 생성한다. 의미있는 순차 규칙과 의사결정 모델은 정확도, 민감도, 특이성, 예측도를 통해 유의미함을 확인한다. 결과적으로, 실제 제조에 적용한 결과 불량률은 0.38%가 개선되었고, 시간당 제조량은 평균 1.89/h 증가되었다. 이는 소규모 제조 공정에서 데이터 마이닝 분석을 통한 제조 효율을 높이기 위한 의미있는 결과를 나타낸다.

• 한국콘텐츠학회논문지
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• 제15권7호
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• pp.414-427
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• 2015

본 연구는 오피스시장의 흐름을 고려하여 대형오피스빌딩 중심의 기존연구에서 벗어나, 중소형오피스빌딩에 대한 다양한 분석을 통해 모형별 중요변수 도출 및 예측력을 검증하여, 중소형 오피스를 대상으로 투자를 하고자 하는 투자자들에게 정보를 제공함이 목적이다. 중소형오피스빌딩은 대형오피스빌딩과 달리 규모에 대한 기준이 불명확하고, 주거용과 상업용이 혼재되어 있는 경우가 많기 때문에 자료수집의 한계가 있기 때문에 기존 연구는 대형오피스빌딩을 대상으로 변수간의 인과관계 추정에 탁월한 회귀모형에 편중되었다. 본 연구에서는 강남구 중소형오피스빌딩을 직접 전수조사하고 최종 1,056개의 자료를 추출하여 인과관계 과정을 추정하는 선형회귀모형외에, 반복학습을 통해 최적의 결과를 만들어내는 신경망모형 및 의사결정나무모형을 통해 매매가격 결정요인을 추가로 분석하였으며, 이를 통해 대형오피스빌딩과의 차별점을 비교하였다.

• Journal of Multimedia Information System
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• 제5권2호
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• pp.111-114
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• 2018

Traffic accident analysis is important to reduce the occurrence of the accidents. In this paper, we analyze the traffic accident with Apriori algorithm to find out an association rule of traffic accident in Korea. We first design the traffic accident analysis model, and then collect the traffic accidents data. We preprocessed the collected data and derived some new variables and attributes for analyzing. Next, we analyze based on statistical method and Apriori algorithm. The result shows that many large-scale accident has occurred by vans in daytime. Medium-scale accident has occurred more in day than nighttime, and by cars more than vans. Small-scale accident has occurred more in night time than day time, however, the numbers were similar. Also, car-human accident is more occurred than car-car accident in small-scale accident.

• 대한산업공학회지
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• 제36권1호
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• pp.13-21
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• 2010

The prediction of contract cancellation of customers is essential in insurance companies but it is a difficult problem because the customer database is large and the target or cancelled customers are a small proportion of the database. This paper proposes a new data mining approach to the binary classification by handling a large-scale unbalanced data. Over-sampling, clustering, regularized logistic regression and boosting are also incorporated in the proposed approach. The proposed approach was applied to a real data set in the area of insurance and the results were compared with some other classification techniques.

• Geomechanics and Engineering
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• 제29권4호
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• pp.451-461
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• 2022

The roadways surrounded by rock and coal will lose their stability or even collapse under rock burst. Rock burst mainly involves an evolution of dynamic loading which behaves quite differently from static or quasi-static loading. To compare the dynamic response of coal and rocks with different static strengths, three different rocks and bituminous coal were selected for testing at three different dynamic loadings. It's found that the dynamic compression strength of rocks and bituminous coal is much greater than the static compression strength. The dynamic compression strength and dynamic increase factor of the rocks both increase linearly with the increase of the strain rate, while those of the bituminous coal are irregular due to the characteristics of multi-fracture and heterogeneity. Moreover, the absorbed energy of the rocks and bituminous coal both increase linearly with an increase in the strain rate. And the ratio of absorbed energy to the total energy of bituminous coal is greater than that of rocks. With the increase of dynamic loading, the failure degree of the sample increases, with the increase of the static compressive strength, the damage degree also increases. The static compassion strength of the bituminous coal is lower than that of rocks, so the number of small-scale fragments was the largest after bituminous coal rupture.

• 품질경영학회지
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• 제9권2호
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• pp.37-43
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• 1981

In Korea small - medium companies constitute 96.6% of all of the mining and manufacturing industries, about 35.2% of the total production of value added business, an average of 35% of the actual export of industrial goods，and 47.7% of employment at the end of 1979. Now then small - medium industry companies organization style constitutes 82.1% of private companies and 82.7% of the total on an small scale under 50 persons in regular empolyees. Small - medium industry Companies have growing problems and bottle-necks in their physical conditions. Total Quality Control is contributed by small - medium industry company for more growth than present conditions. But now, Small - medium industry company do not use systematic application of Quality Control Method, the small - medium business compay products quality is not better as compared with big business Company. Specially, TQC is needed for Small - medium company for imperishable enlargement.

• 예술인문사회 융합 멀티미디어 논문지
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• 제7권6호
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• pp.693-700
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• 2017

우리나라의 광산은 지질학적인 구조와 형상이 복잡하며, 규모가 작기 때문에 광산의 개발 및 관리와 채굴계획 수립에 정교한 측량성과와 3D 모델링이 필요하다. 하지만 데이터 취득 및 처리 기술과 경제성으로 인해 현재 기존의 방법을 이용하고 있다. 광산의 구조, 갱도, 채굴면적 등을 2D 도면을 기반으로 기록 및 관리하고 있으며, 이로 인해 인력과 시간의 낭비는 물론 정확도 문제로 인한 사고의 위험도 가지고 있는 실정이다. 최근 외국에서는 지질에 대한 조사 자료와 광산에 대한 공간정보를 통합하여 데이터베이스화 하고, 이를 광산관리 및 채굴계획 수립에 활용하고 있다. 본 연구에서는 레이저스캐너를 활용하여 광산관리와 채굴계획 수립을 위한 공간정보를 구축하고자 하였다. 연구를 통해 광산에 대한 공간정보를 효과적으로 취득하고, 자료처리를 통해 모델링 된 데이터를 생성할 수 있었다. 광산관리를 위한 3D 모델은 광산의 안전한 채굴계획 수립과 운영에 중요한 도구로써 활용이 기대된다.