• Geomechanics and Engineering
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• 제28권4호
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• pp.335-346
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• 2022

Buckling failure is a typical slope instability mode that should be paid more attention to. It is difficult to provide systematic guidance for the monitoring and management of such slopes due to unclear mechanism. Here we examine buckling failure as the potential instability mode for a slope above a railway tunnel in southwest China. A comprehensive model test system was developed that can be used to conduct buckling failure experiments. The displacement, stress, and strain of the slope were monitored to document the evolution of buckling failure during the experiment. Monitoring data reveal the deformation and stress characteristics of the slope with different slipping mass thicknesses and under different top loads. The test results show that the slipping mass is the main subject of the top load and is the key object of monitoring. Displacement and stress precede buckling failure, so maybe useful predictors of impending failure. However, the response of the stress variation is earlier than displacement variation during the failure process. It is also necessary to monitor the bedrock near the slip face because its stress evolution plays an important role in the early prediction of instability. The position near the slope foot is most prone to buckling failure, so it should be closely monitored.

• Journal of Preventive Medicine and Public Health
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• 제45권5호
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• pp.283-290
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• 2012

Objectives: People who have chronic diseases, as well as gait imbalance or psychiatric drug use, may be susceptible to injuries from falls and slips. The purpose of this study was to evaluate the effect of musculoskeletal diseases on incidental fall-related injuries among adults in Korea. Methods: We analyzed data from the 4th Korea National Health and Nutrition Examination Survey (2007-2009), which are national data obtained by a rolling survey sampling method. The 1-year incidence of fall-related injuries was defined by health service utilization within the last year due to injury occurring after a slip and fall, and musculoskeletal diseases included osteoarthritis, rheumatoid arthritis, osteoporosis, and back pain. To evaluate the effects of preexisting musculoskeletal diseases, adults diagnosed before the last year were considered the exposed group, and adults who had never been diagnosed were the unexposed group. Results: The weighted lifetime prevalence of musculoskeletal disease was 32 540 per 100 000 persons. Musculoskeletal diseases were associated with a higher risk of fall-related injury after adjustment for sex, age, residence, household income, education, occupation, visual disturbance, paralysis due to stroke, and medication for depression (odds ratio [OR], 1.41; 95% confidence interval [CI], 1.03 to 1.93). As the number of comorbid musculoskeletal diseases increased, the risk of fall-induced injuries increased (p-value for trend <0.001). In particular, patients who had any musculoskeletal condition were at much higher risk of recurrent fall-related injuries (OR, 6.20; 95% CI, 1.06 to 36.08). Conclusions: One must take into account the risk of fall-related injuries and provide prevention strategies among adults who have musculoskeletal diseases.

• Structural Engineering and Mechanics
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• 제58권3호
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• pp.577-596
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• 2016

FRP-concrete interfacial mechanical properties determine the strengthening effect of RC beams strengthened with FRP. In this paper, the model experiments were carried out with eight specimens to study the failure modes and the strengthening effect of RC beams strengthened with FRP. Then a theoretical model based on interfacial performances was proposed and interfacial mechanical behaviors were studied. Finite element analysis confirmed the theoretical results. The results showed that RC beams strengthened with FRP had three loading stages and that the FRP strengthening effects were mainly exerted in the Stage III after the yielding of steel bars, including the improvement of the bearing capacity, the decreased ultimate deformation due to the sudden failure of FRP and the improvement of stiffness in this stage. The mechanical formulae of the interfacial shear stress and FRP stress were established and the key influence factors included FRP length, interfacial bond-slip parameter, FRP thickness, etc. According to the theoretical analysis and experimental data, the calculation methods of interfacial shear stress at FRP end and FRP strain at midspan were proposed. When FRP bonding length was shorter, interfacial shear stress at FRP end was larger that led to concrete cover peeling failure. When FRP was longer, FRP reached the ultimate strain and the fracture failure of FRP occurred. The theoretical results were well consistent with the experimental data.

• 대한인간공학회지
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• 제30권1호
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• pp.19-28
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• 2011

Objective: The aim of this study is to reclassify human errors and to develop hands-on tools to apply the new classification for preventing human error accidents in highway construction site. Background: The main cause of accidents in highway construction was reported as the carelessness of workers. However, such diagnosis could not help us operationally prevent accidents in real workplace. Method: The accidents in highway construction were reanalyzed and the causes of human error were reclassified in order to educate and improve the awareness of human error in highway construction. Field survey and interview with safety managers and workers were conducted to find the causal relationship between the actual accidents and the human errors. Results: The most frequently observed human errors in highway construction were classified into six categories such as mis-perception, distraction, memory fail, slip, cognition error and mis-judgment. In order to provide hands-on tools to increase the awareness of human error in construction field, the human error checklist and card sorting diary were developed. Especially, the card sorting diary was designed to increase the ability in human error inspection of safety manager at construction site. Moreover, posters were developed based on actual accident cases. Conclusion: We suggested that the improved awareness and analytical report on checklist, card sorting diary and posters for construction field could collectively prevent the accident. Application: The classification of human error, hands-on tools and posters can be directly applicable on highway construction site. This analytical and collective approach preventing human error-related accident could be extended to other construction workplaces.

• 대한안전경영과학회지
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• 제25권2호
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• pp.17-28
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• 2023

This study aimed to verify the validity of the evaluation items and weight determination of the indoor environmental safety area, which has the most frequent accidents, among the safety certification evaluations of educational facilities by the Ministry of Education of the Republic of Korea, which has been conducted since May 2021. As a preceding study, the evaluation items of the school safety evaluation checklist being implemented in the US state of Vermont were compared, and the causes of accidents judged by teachers in the accident experiences written by 200 Korean teachers were compared with the safety certification evaluation items belonged to the Ministry of Education. In addition, research literature using the AHP analysis technique on safety risks of elementary and secondary schools in China and safety evaluation index study cases of 539 elementary school children in Indonesia were analyzed. Through these preceding studies, measures to add and adjust evaluation items were derived and the validity and importance rankings of evaluation items were calculated through AHP questionnaires to teachers and safety experts. In addition, a survey was conducted on 104 ordinary people to verify the results of expert analysis. As a result of expert AHP analysis, 'safety education and disaster response training (.396)' was the highest priority for the relative importance of the first layer, followed by 'safety measures (.387)' and 'building materials'. Safety (.216)' was found to be the highest priority. In the overall importance ranking of the 13 second-tier screening items, safety accident prevention education had the highest priority and disaster preparedness training ranked second, proving that the Ministry of Education's review weight was underestimated. In addition, slip and collision accident countermeasures, which were not in the existing Ministry of Education review items, ranked 4th, laboratory practice room safety measures ranked 6th, and sanitation, cleanliness, hazardous substance management, and cafeteria/cooking room safety measures ranked 9th, indicating a significant level of importance. Referring to the importance ranking, which is the result of this study, it is suggested that it is necessary to review the weight of each review item again.

• 지질공학
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• 제26권4호
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• pp.531-549
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• 2016

화강암, 화강편마암, 변성퇴적암류와 같이 다양한 지질환경에서 지하수내 자연방사성물질인 우라늄과 Rn-222의 산출특성에 대한 지하수의 수리화학적 영향, 지질과의 상관성, 단층대의 영향 등에 대해서 알아보고자 하였다. 이 연구를 위하여 영동지역을 대상으로 2차례에 걸쳐 지하수 49점, 지표수 4점을 채취하였다. 지하수내 우라늄과 지표 암석과의 상관성을 알아보기 위해 감마스펙트로메트리를 이용하여 40지점에서 지표방사능을 측정하였다. 지하수 화학적 유형 $Ca-HCO_3$, $Na-HCO_3$, $Ca-HCO_3(SO_4+NO_3)$등 3가지 유형을 보인다. 환경부 권고치인 우라늄 $30{\mu}g/L$를 초과하는 지하수는 총 49지점 중 2점이며, Rn-222의 경우 미국 EPA 기준치인 148 Bq/L를 초과하는 지하수는 총 40지점중 11점이다. 초과하는 지하수는 주로 화강편마암과 흑운모편마암 지질과 지질경계부에 분포한다. 지표방사능 세기와 지하수내 우라늄함량과는 뚜렷한 상관관계를 보여지 않는다. 아울러 $N45^{\circ}E$ 방향의 주향이동단층인 영동단층은 $82^{\circ}$의 고경도로 상반에 해당되는 화강암 및 화강편마암지역에서 고함량의 우라늄과 Rn-222가 산출되며, 하반에 해당되는 퇴적암지역에는 고함량의 지하수가 확인되지 않는데, 이와 같은 뚜렷한 차이는 지질의 영향과 더불어 단층대가 방사성물질의 이동 및 확산을 차단시키는 역할에도 원인이 있을 것으로 추정된다.

• Geomechanics and Engineering
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• 제24권3호
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• pp.215-226
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• 2021

To study the evolution mechanism of cracks in rocks with multiple defects, rock-like samples with multiple defects, such as strip-shaped through-going cracks and cavity groups, are used, and the crack propagation law and changes in AE (acoustic emission) and strain of cavity groups under different inclination angles are studied. According to the test results, an increase in the cavity group inclination angle can facilitate the initial damage degree of the rock and weaken the crack initiation stress; the initial crack initiation direction is approximately 90°, and the extension angle is approximately 75~90° from the strip-shaped through-going cracks; thus, the relationship between crack development and cavity group initiation strengthens. The specific performance is as follows: when the initiation angle is 30°, the cracks between the cavities in the cavity group develop relatively independently along the parallel direction of the external load; when the angle is 75°, the cracks between the cavities in the cavity group can interpenetrate, and slip can occur along the inclination of the cavity group under the action of the shear mechanism rupture. With the increase in the inclination angle of the cavity group, the AE energy fluctuation frequency at the peak stress increases, and the stress drop is obvious. The larger the cavity group inclination angle is, the more obvious the energy accumulation and the more severe the rock damage; when the cavity group angle is 30° or 75°, the peak strain of the local area below the strip-shaped through-going fracture plane is approximately three times that when the cavity group angle is 45° and 60°, indicating that cracks are easily generated in the local area monitored by the strain gauge at this angle, and the further development of the cracks weakens the strength of the rock, thereby increasing the probability of major engineering quality damage. The research results will have important reference value for hazard prevention in underground engineering projects through rock with natural and artificial defects, including tunnels and air-raid shelters.

• 한국지반공학회논문집
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• 제15권1호
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• pp.113-125
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• 1999

부산시 남구 문현동 산사태 지역에 산출하는 점토광물에 대해 X-선회절분석, 주사전자현미경 관찰 및 화학분석 등의 조사를 행하여 산출상태 및 광물학적 특성을 검토하였다. 그 결과, 본 지역에는 할로이사이트, 버미큘라이트, 운모/버미큘라이트 혼합층광물, 버미큘라이트/스멕타이트 혼합층광물, 카오리나이트, 일라이트 등의 여러 점토광물이 다량 산출되는 것으로 나타났다. 산출상태로 보아 이들 점토광물은 기반암인 안산암의 풍화변질에 의해 형성된 것으로 나타났다. 즉, 안산암의 초기 풍화단계에서 할로이사이트가 형성되고, 그 후의 중간단계에서 버미큘라이트, 운모/버미큘라이트 혼합층광물 및 버미큘라이트/스멕타이트 혼합층광물이 형성되었으며, 최종의 풍화단계에서 카오리나이트가 주로 형성된 것으로 사료된다. 특히 산사태 발생지역의 중심부와 미끄러진 바닥면의 점토에서 할로이사이트, 버미큘라이트, 버미큘라이트/스멕타이트 혼합층광물 등의 팽윤성 점토광물이 다량 산출되었다. 따라서 이들 점토광물은 물을 흡수하여 팽창하게 되며, 이에 따라 사면의 전단저항을 급격히 약화시킬 수 있기 때문에 산사태 발생의 중요한 원인을 제공한 것으로 생각된다. 지질 및 구성광물 등의 검토 결과, 이 지역의 산사태는 급한 경사면, 집중호우, 절리의 발달, 암석의 변질작용, 그리고 팽윤성 점토광물 등의 요인이 복합적으로 작용되어 발생된 것으로 사료된다. 따라서 산사태의 조사 및 방지대책에 있어서 지질과 함께 점토광물에 대한 검토가 필요한 것으로 사료된다.

• 대한원격탐사학회지
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• 제37권6_2호
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• pp.1901-1922
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• 2021

대부분의 대규모 지진은 기존의 활성단층이 재활하여 발생하므로, 이러한 활성단층의 위치와 특성을 파악하는 것은 지진재해 연구와 지진방재 측면에서 매우 중요하다. 최근에는 활성단층 조사에서 지표지질조사에 앞서 실시하는 선형구조 분석에 다양한 원격탐사 기술이 유용하게 활용되고 있다. 본 논문에서는 원격탐사 기술 중 이러한 활성단층 조사에 널리 활용되는 위성원격탐사, 항공원격탐사, 그리고 InSAR, LiDAR 기법의 간단한 원리와 적용사례를 소개하고자 한다. 또한, GIS를 활용하여 단층활동에 의해 형성된 경사급변점과 주향이동단층의 수평변위를 분석한 사례를 소개하고자 한다. 토의에서는 항공사진을 활용하여 DEM을 구축할 때 발생할 수 있는 문제점들과 해결방안, 항공 LiDAR 기반 DEM의 문제점을 극복하여 개발한 새로운 기법인 RRIM에 대해 논의하고자 한다. 활성단층 조사에서 어떤 원격탐사 기술이 활용되는지 이해하고 각 원격탐사기법의 장단점과 한계점을 이해하여 상황에 따라 적절한 방법을 활용하는 것은 효율적인 활성단층조사를 위해 중요하다.

• 대한토목학회논문집
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• 제38권6호
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• pp.895-906
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• 2018

우리나라의 어린이보호구역 개선사업은 어린이가 주로 활동하는 유치원, 초등학교 주변에서 많이 발생하고 있어 어린이 교통사고 예방책의 일환으로 추진하고 있다. 하지만 어린이보호구역내 안전시설물에 대한 필수 설치 시설물과 적정 설치 수준에 대한 연구가 부족한 바, 본 연구에서는 자료포락분석을 활용한 안전시설물 설치의 효율성을 상대적으로 평가하여 개선방안을 제시하였다. 화성시 관내 초등학교중 총 28개 어린이보호구역에 대한 시설물 현황과 사고현황 자료를 구축하였다. 기존 연구상에 효과가 입증된 주요 시설물 6개(고원식 교차로, 고원식 횡단보도, 방호울타리, 미끄럼방지시설, 과속방지턱, 단속카메라)만 투입요소로 하여 분석하였다. 분석결과 28개소 중 12개소만 효율성이 있는 것으로 나타났으며, 16개소는 효율성이 떨어지는 것으로 나타났다. 효율집단으로 구분된 어린이보호구역은 방호울타리, 미끄럼방지시설, 단속카메라 설치가 비효율집단으로 구분된 어린이보호구역보다 적게 설치한 것으로 나타났다. 방호울타리는 어린이보호구역 전체연장 중 47% 정도만 설치하여도 충분히 효율성이 있는 것으로 나타났으며, 미끄럼방지시설의 개소 수는 $km^2$당 8.7개 정도면 효율성이 있는 것으로 나타났다. 비교대상의 수가 28개소로 상대적 효율성 평가지표로 활용하는 데는 본 연구가 한계가 있으며, 향후 전국단위로 그룹화 하여 각 그룹별로 효율성 평가할 수 있을 것으로 판단된다.