• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 춘계 학술발표회
• /
• pp.607-614
• /
• 2010

Shear behavior of granular soils largely affects the safety and stability of underground and earth structures. This study presents the characteristics of shear zone in a direct shear test using shear wave and electrical resistivity measurements. An innovative direct shear box made of transparent acrylic material has been developed to prevent direct electric current. Bender elements and electrical resistivity probe are embedded in the wall of direct shear box to estimate the shear wave velocities and the electrical resistivity at the shear and non-shear zones. Experimental results show that the void ratio and shear wave velocity at shear zone increase during shearing while the values remain constant at non-shear zone. The results demonstrate correlation among the contact force, small strain shear modulus, and void ratio at shear zone. This study suggests that the application of the modified direct shear box including shear wave and electrical resistivity measurements may become an effective tool for analyzing soil behavior at shear zone.

• Geomechanics and Engineering
• /
• 제7권1호
• /
• pp.105-131
• /
• 2014

In this paper, the effects of variability of smear zone characteristics induced by installation of prefabricated vertical drains on the preloading design are investigated employing analytical and numerical approaches. Conventional radial consolidation theory has been adopted to conduct analytical parametric studies considering variations of smear zone permeability and extent. FLAC 2D finite difference software has been employed to conduct the numerical simulations. The finite difference analyses have been verified using three case studies including two embankments and a large-scale laboratory consolidometer with a central geosynthetic vertical drain. A comprehensive numerical parametric study is conducted to investigate the influence of smear zone permeability and extent on the model predictions. Furthermore, the construction of the trial embankment is recommended as a reliable solution to estimate accurate smear zone properties and minimise the post construction settlement. A back-calculation procedure is employed to determine the minimum required waiting time after construction of the trial embankment to predict the smear zone characteristics precisely. Results of this study indicate that the accurate smear zone permeability and extent can be back-calculated when 30% degree of consolidation is obtained after construction of the trial embankment.

• 한국안전학회지
• /
• 제30권6호
• /
• pp.139-147
• /
• 2015

This study deals with actual commuting distance and influence of risk factors depending on commuting distance and mode in order to reestablish actual commuting zone of primary school students. Data mining analysis(CHAID) was applied for this reestablishment using survey results from 6,927 primary school students in Seoul Metro. Six risk factors; convenience level of commuting path condition, convenience level of road crossing condition, vehicle speed on commuting path, segregation level between commuter and vehicle, congestion level of commuting path, and public security level and two mode; walking and cycle are considered in the analysis. As the results of CHAID analysis, commuting distance was divided into four zones; Internal Zone(0.491km under), External Zone(0.492 ~ 1.492km, 1.493 ~ 2.699km), Commutable Zone(2.70km over), and awareness level on safety is declined as commuting distance is increased. The risk factor affecting on safety is recognized differently by students depending on commuting distance and mode. For students commuting by walking, vehicle speed on commuting path and convenience level of commuting path condition are recognized as the prime risk factor within Internal Zone and Commutable Zone, respectively. For students commuting by cycle, convenience level of road crossing condition and vehicle speed on commuting path are recognized as the prime risk factor within Commutable Zone. Analysis results show that improved plan and program for commuting path for primary school students are required considering actual commuting distance and method.

• 한국콘텐츠학회논문지
• /
• 제22권2호
• /
• pp.116-124
• /
• 2022

2019년 9월 충남 아산 김민식 군의 사망사고 이후 어린이보호구역에 대한 인식이 높아지고 있으며, 지속해서 교통법 개정이 이루어지고 있다. 하지만 이러한 노력에도 불구하고 어린이 교통사고의 수는 크게 줄어들지 않고 있다. 이것은 어린이 행동 특성과 교통 환경을 고려한 새로운 정책적 방향의 필요성을 나타낸다. 이에 본 연구는 사례분석을 통해 국내의 어린이보호구역의 현황 및 문제점을 파악하였다. 그리고 교통안전 선진국인 스웨덴의 비전 제로(Vision Zero) 정책과 홈 존(Home Zone)의 개념, 그리고 공학적 위주의 도로설계 사례 및 운영 방식에 대해 분석하였다. 또한 양국의 사례를 방재디자인의 기본원리를 중심으로 비교하고 정리하였다. 본 연구는 국내 어린이보호구역의 문제점 개선을 위한 디자인과 정책의 방향성을 제시하는데 목표를 두고 있다. 이를 통해 본 연구 결과가 국내 어린이보호구역 내 사망사고 감소를 위한 향후 연구 발전 자료로써 활용되기를 기대한다.

• 한국학교보건학회지
• /
• 제17권2호
• /
• pp.115-126
• /
• 2004

Purpose: The aim of the study is to provide information about selecting school sites for new schools in congested urban areas and to propose a method to manage harmful environments around primary and secondary schools. Method: Four schools were selected around Gilum New Town and Ilsan City. The problems were identified by counting the businesses classified as harmful and prohibited in a school zone through surveying, collecting reports from relevant sources, and asking questions of authorities in school districts. Results: It was found that many harmful businesses prohibited by the Law of School Health were present in the safe zone of schools in both Ilsan city and Gilum New Town. The school site of Bohyun Elementary School was classified as poor because there was a steep ascent at the entrance and the school was surrounded by a dangerous, steep boundary. We suggested that an education and environment assessment system by completed before the school site was selected. Conclusion: There is a urgent need to improve the approval and permission process of harmful businesses as well as regulatory standards of school site selection in the light of the shortage of land.

• 한국해양공학회:학술대회논문집
• /
• 한국해양공학회 2004년도 학술대회지
• /
• pp.401-407
• /
• 2004

This study is on the constant-current stress corrosion test related to the load stress in welded zone and non-welded zone of high tensile strength steel for natural gas transmission. The surface corrosion pattern of the welded zone of API 5L-X65 specimens for natural gas transmission showed global corrosion and narrow pitting, and the pitting was increased by increasing the load stress. Initially, the average relative electrode potential and the average relative current of the high tensile strength steel for natural gas transmission specimens was decreased suddenly, and the average relative electrode potential was higher and the average relative current was lower in welded zone than base metal. and the average relative electrode potential was decreased by increasing the load stress, and the average relative current was somewhat increased by increasing the load stress. The corrosion rate was less in welded zone than base metal, and the corrosion rate was decreased by increasing the load stress.

• Korean Chemical Engineering Research
• /
• 제58권3호
• /
• pp.493-497
• /
• 2020

Hazardous area classification is designed to prevent chemical plant explosions in advance. Generally, the duration of the explosive atmosphere is used for zone type classification. Herein, IEC code, a quantitative zone type classification methodology, was used to achieve Zone 2 NE, which indicates a practical non-explosion condition. This study analyzed the operating pressure of a vessel handling propane to achieve Zone 2 NE by applying the IEC code via MATLAB. The resulting zone type and hazardous area grades were compared with the results from other design standards, namely API and EI codes. According to the IEC code, the operating pressure of vessels handling propane should be between 101325-116560.59 Pa. In contrast, the zone type classification criteria used by API and EI codes are abstract. Therefore, since these codes could interpret excessively explosive atmospheres, care is required while using them for hazardous area classification design.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2011년도 춘계학술대회
• /
• pp.407-409
• /
• 2011

최근 Smart Phone에서 WiFi Zone의 활용도가 증가되고 있다. WiFi Zone의 무선 인터넷은 무선이 가지고 있는 취약점을 그대로 가지고 있기 때문에 보안에 대한 취약점이 존재하고 침해사고에 대비한 연구가 필요하다. 본 논문에서는 WiFi Zone에서 암호가 설정된 무선 AP의 패킷을 수집하여 분석하고, 해당 무선 AP의 access 암호를 알아낸다. 암호분석과 WiFi Zone의 취약점을 분석하여 War Driving 기술을 사용하여 무선 인터넷의 취약점을 분석하고, 무선 AP에 대한 공격과 ARP Spoofing 공격을 하여 해당 무선 AP를 마비시키거나 위장 무선 AP를 설정하여 정보를 취득 하였다. 본 논문 연구를 통하여 Smart Phone과 무선 네트워크 보안성을 강화하는 연구 자료로 사용할 것이다.

• Journal of Mechanical Science and Technology
• /
• 제17권2호
• /
• pp.269-279
• /
• 2003

The anti-plane shear problem of bonded elastic materials containing a crack at an arbitrary angle to the graded interfacial zone is investigated in this paper The interfacial zone is modeled as a nonhomogeneous interlayer of finite thickness with the continuously varying shear modulus between the two dissimilar, homogeneous half-planes. Formulation of the crack problem is based upon the use of the Fourier integral transform method and the coordinate transformations of basic field variables. The resulting Cauchy-type singular integral equation is solved numerically to provide the values of mode 111 stress intensity factors. A comprehensive parametric study is then presented of the influence of crack obliquity on the stress intensity factors for different crack size and locations and for different material combinations, in conjunction with the material nonhomogeneity within the graded interfacial zone.

• 교육시설
• /
• 제15권6호
• /
• pp.12-21
• /
• 2008

The purpose of this study was to research on relationship between the circulation system of students and resident users in elementary school complex. 4 elementary schools in Seoul were chosen for this study. The method of this study is a plan analysis, an on-the-spot survey, and user behavior observation. The circulation system of students and resident users at school zone(outside) and Community school were observed. The following is the main results of this study. First, circulation systems are mixed between public zone and student zone in Community school. Therefore these zones shall be planed separated. Second, resident users tend to go directly to the facilities gathered together. Therefore main entrance has to be located closely to the facilities gathered together. In accordance with this results, both the main entrance of Community school and the students facilities have to be considered when planing the circulation system in school from now on.