• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.681-688
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• 2003

Rock damage induced by blasting can not be avoided during tunnel construction and may affect tunnel stability. But the mutual interaction between tunnel blasting design and tunnel stability design is generally not considered. Therefore this study propose a methodology to take into considration the results of the blasting damage in tunnel stability design. Rock damage is evaluated by dynamic numerical analysis for the most common blasting pattern adopted in road tunnel. Damage zone is determined by using the continuum damage model which is expressed as a function of volumetric strain. And the damage effect is taken into account by the damaged rock stiffness and the damaged failure criteria in tunnel stability assessment. The extend of plastic zone and deformation increase compared to the case of not considering blast-induced rock damage.

• Advances in concrete construction
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• 제1권3호
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• pp.239-252
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• 2013

Mortar microstructure is considered as a three-phase composite material, which is cement paste, fine aggregate and interfacial transition zone. Interfacial transition zone is the weakest link between the cement paste and fine aggregate, so it has a significant role to determine the properties of cementitious composites. In this study, specimens (w/c = 0.35, 0.45, 0.55) with various volume fractions of fine aggregate ($V_f$ = 0, 0.1, 0.2, 0.3 and 0.4) were cast and tested. To predict the equivalent migration coefficient ($M_e$) and migration coefficient of interfacial transition zone ($M_{itz}$), double-inclusion method and Mori-Tanaka theory were used to estimate. There are two stages to estimate and calculate the thickness of interfacial transition zone (h) and migration coefficient of interfacial transition zone ($M_{itz}$). The first stage, the data of experimental chloride ion migration coefficient ($M_s$) was used to calculate the equivalent migration coefficient of fine aggregate with interfacial transition zone ($M_e$) by Mori-Tanaka theory. The second stage, the thickness of interfacial transition zone (h) and migration coefficient of interfacial transition zone ($M_{itz}$) was calculated by Hori and Nemat-Nasser's double inclusion model. Between the theoretical and experimental data a comparison was conducted to investigate the behavior of interfacial transition zone in mortar and the effect of interfacial transition zone on the chloride migration coefficient, the results indicated that the numerical simulations is derived to the $M_{itz}/M_m$ ratio is 2.11~8.28. Additionally, thickness of interfacial transition zone is predicted from $10{\mu}m$, 60 to $80{\mu}m$, 70 to $100{\mu}m$ and 90 to $130{\mu}m$ for SM30, M35, M45 and M55, respectively.

• Geomechanics and Engineering
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• 제17권1호
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• pp.97-107
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• 2019

Based on the results of Han et al. (2016), in the failure zone ahead of the tunnel face it can be obviously identified that a shear failure band occurs in the lower part and a pressure arch happens at the upper part, which was often neglected in analyzing the face stability of shield tunnel. In order to better describe the collapse failure feature of the tunnel face, a new improved failure mechanism is proposed to evaluate the face stability of shield tunnel excavated in layered soils in the framework of limit analysis by using spatial discretization technique and linear interpolation method in this study. The developed failure mechanism is composed of two parts: i) the rotational failure mechanism denoting the shear failure band and ii) a uniformly distributed force denoting the pressure arch effect. Followed by the comparison between the results of critical face pressures provided by the developed model and those by the existing works, which indicates that the new developed failure mechanism provides comparatively reasonable results.

• 대한토목학회논문집
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• 제39권1호
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• pp.73-80
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• 2019

교통안전과 효율적인 교통관리의 도로교통정책이 간선도로 등 일정규모 이상의 도로에서 주로 이루어지고 있어 상대적으로 생활도로의 안전성은 열악한 상황이다. 특히, 보행자의 안전이 주가 되어야 할 주거지역의 생활권 도로까지 차량이 우선시 되는 경우가 발생하는 등 상대적으로 생활도로에 대한 개선은 이루지 못한 실정이다. 이에 본 연구는 생활도로 내 교차로 알림이 설치기준을 제시하기 위하여 광주광역시를 중심으로 현장조사를 실시하였고, 생활도로내 교차로에 영향을 미치는 영향인자와의 관계를 다중회귀분석을 통한 예측모형으로 도출하였다. 나아가 생활도로내 사고예측 모형을 통한 실측값을 제시 한 후 교차로 알림이가 설치된 지점의 값과 비교 검증하여 생활도로내 교차로 알림이 설치기준을 제시하였다. 이를 통해 생활도로 내 잦은 교통사고를 예방하고 생활도로를 이용하는 이용자들의 편의성 및 안전을 고려한 교차로 알림이 설치가 이루어 질 수 있을 것으로 기대된다.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.606-607
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• 2015

The traffic volume on the road shows various trends reflecting regional characteristics for monthly and hourly, and economic loss affecting users varies according to the selected period for the maintenance of road pavements. Therefore, in this study, the user cost (or delay cost) for monthly and hourly on the work zone near the Maesang Bridge Section on Poseung-Gu, Pyeongtaek-si, Gyeonggi-do was calculated using the time series models and VISSIM, and based on the result, the effect of user cost reduction according to the selection of best maintenance period was examined. The analysis result showed that the month of the lowest user cost occurred due to the maintenance of target section was January (10,293,258 KRW/Day×1km) and the month of the greatest user cost occurred was November (13,337,495 KRW/Day×1km).

• Geomechanics and Engineering
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• 제35권2호
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• pp.109-119
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• 2023

Ground subsidence in urban areas due to excessive development and degraded underground facilities is a serious problem. Geophysical surveys have been conducted to estimate the distribution and scale of cavities and subsidence. In this study, electrical resistivity tomography (ERT) was performed near an area of road subsidence in an urban area. The subsidence arose due to groundwater leakage that carried soil into a neighboring excavation site. The ERT survey line was located between the main subsidence area and an excavation site. Because ERT data are affected by rapid topographic changes and surrounding structures, the influence of the excavation site on the data was analyzed through field-scale numerical modeling. The effect of an excavation should be considered when interpreting ERT data because it can lead to wrong anomalous results. A method for performing 2D inversion after correcting resistivity data for the effect of the excavation site was proposed. This method was initially tested using a field-scale numerical model that included the excavation site and subsurface anomaly, which was a loosened zone, and was then applied to field data. In addition, ERT data were interpreted using an existing in-house 3D algorithm, which considered the effect of excavation sites. The inversion results demonstrated that conductive anomalies in the loosened zone were greater compared to the inversion that did not consider the effects of excavation.

• 자동차안전학회지
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• 제15권3호
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• pp.7-16
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• 2023

In 2019, a child died by a school zone traffic accident in Asan, Chungcheongnam-do, the Republic of Korea. Just after the accident, under the name of the "Minsik Law", the Road Traffic Act and the Specific Crime Aggravated Punishment Act were partially revised and went into effect in Korea on March 25, 2020. The new Korean law providing for harsh penalties is designed to reduce automobile accidents in school zones. However, the penalties under the new law seems to be unconstitutionally and unduly harsh. Under the new law, a negligent driver who kills a child at a school zone could be sentenced to indefinite imprisonment, or imprisonment for 3 years or more. The criminal responsibility of a negligent driver at a school zone is the same as serious intentional felonies such as rape, robbery, abandonment resulting in death. Also, even in the case of a school zone accident, if an accident driver complies with the speed limit and other traffic laws and it is impossible to avoid the accident, the driver should not be punished. So, in order to meet the principle of proportionality, the new Korean law should be revised again. In order to find out the appropriate level and punishment method for drivers who cause accidents in school zones, this thesis will compare and analyze the laws of Korea with those of the United States, Germany, and Japan. This paper also reviews the decision of the Constitutional Court of the Republic of Korea in February 2023 that the "Minsik Law" was constitutional. Based on these analyses, this thesis seeks the direction and amendments to properly revise Korean law. In addition, this thesis is intended to present exemplary measures to improve the school zone safety.

• 한국ITS학회 논문지
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• 제16권5호
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• pp.121-133
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• 2017

1990년대 중반 이후 어린이보호구역 개선사업 등 학교 주변 안전과 보행환경 개선을 위한 정책이 적극적으로 추진되어 왔으나, 어린이 통학 시의 주요 이동경로가 이루어지는 통학로까지는 확대되지 못해 사고예방 효과가 크지 않았다. 또한 자동차 급증으로 첨두시간대의 간선도로 교통이 이면도로로 우회함에 따라 어린이들의 주요 생활공간인 학교 권역까지 침범하는 등 어린이 안전과 환경을 위협하고 있다. 이에 본 연구는 국내 어린이 교통사고 특성을 파악하고 서울시 여의도 중고등학교 및 경기도 운중초등학교를 중심으로 현장조사를 수행하여 문제점을 분석하였다. 또한 보행자 보호구역(어린이보호구역 포함)에 가변형속도제한표지 및 비콘을 설치하여 해당시설이 차량의 통행속도에 미치는 영향을 분석하였다. 분석결과 가변형속도제한표지는 약 8.3km/h의 통행속도 감속효과가 나타났으며 비콘의 경우 미미하나마 오히려 0.8km/h의 통행속도가 증가하는 현상이 도출되었다. 또한 설치전후의 신호위반 차량대수를 조사한 결과 승용차, 버스, 화물차의 신호위반율이 약 3% 감소하였다.

• 대한기계학회논문집B
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• 제30권2호
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• pp.136-143
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• 2006

A particle image velocimetry (PlV) technique has been applied to measure the quantitative flow field characteristics behind a road vehicle with/without an air spoiler attached on its trunk and to estimate its effect on the wake. A vehicle model scaled in the ratio of 1/43 is set up in the mid-section of a closed-loop water tunnel. The Reynolds number based on the vehicle length is $10^5$. To investigate the three-dimensional structure of the recirculation zone and vortices, measurements are carried out on the planes both parallel and perpendicular to the free stream, respectively. The results show significant differences in the recirculation region and the vorticity distributions according to the existence of the air spoiler. The focus and the saddle point, appearing just behind the air spoiler, are disposed differently along the spanwise direction. Regarding the streamwise vortices, the air spoiler produces large wing tip vortices. They have opposite rotational directions to C-pillar vortices which are commonly observed in case that the air spoiler is absent. The wing tip vortices generate the down-force and as a result, they can make the vehicle more stable in driving.

• 대한교통학회지
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• 제27권5호
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• pp.39-49
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• 2009

본 연구는 현재의 보행자 보호구역 선정기준 문제점을 분석하여 현실에 맞는 기준 재정립에 관해 기술하였다. 구체적인 사항으로는 보행자 교통사고의 문제점에 대하여 통계자료를 기본으로 보행자 교통사고의 추이, 사고의 발생 유형, 행동유형 등을 종합적으로 분석하고 보행자 교통사고의 감소를 위한 대책으로 보행자 보호구역을 지정 운영하고 있는 국내 외의 사례를 활용하여 국내의 Zone30 구역 선정 기준을 도출하였다. 또한, 현장조사를 통해 교통량과 속도가 보행자 사고에 미치는 영향을 분석하여 정량적인 기준을 제시하였으며, 정량적 기준 외에 사고유형, 도로기능, 사고위치 등 보행자 교통사고 발생건수 등의 사고특성을 분석하여 기준을 제시하였다. 특히 교통사고의 통계자료를 활용하여 보행자 안전성에 역점을 두었다. 또한, Zone30 구역의 안전시설 설치에 관한 설치기준 및 운영방안의 체계적인 정립이 이루어지지 않아 각 지방 단위별로 일관성이 없고 혼란이 발생하여 Zone30 구역에 설치될 시설설치 표준지침 수립과 운영방안을 제시하였으며, Zone30 구역 교통운영별 시설물 배치도를 제시하여 설치기준을 제시하였다.