PURPOSES : This study aims to understand the effect of defective dowel bar installation on jointed concrete pavement (JCP), which can cause joint freezing, spalling, cracking, and faulting and finally shorten the lifespan of the pavement. METHODS : A comprehensive field survey was undertaken at an expressway construction site in South Korea to assess dowel bar installation conditions. In addition, finite element (FE) analysis was used to simulate JCP behavior with both vertical and horizontal dowel misalignments. Different temperature conditions, including a change of -55 °C and gradient of -0.1 °C/mm, were integrated into the FE model to examine horizontal slab contraction and simultaneous slab curling. RESULTS : The analysis revealed pronounced slab behaviors under specific temperature changes, particularly when combined with dowel misalignments. The simultaneous effects of horizontal contraction and slab curling owing to temperature changes and gradients became more evident in the presence of dowel misalignments. CONCLUSIONS : The results confirmed that dowel bar misalignment considerably affected the behavior of the JCP, thereby emphasizing the importance of the proper installation of dowel bars.

최근 기후변화와 더불어 사과원 병해충 방제 횟수, 주변 식생 등의 변화로 인해 노린재류의 발생 밀도가 증가하고 피해가 점점 늘어나고 있다. 사과원 노린재류의 방제는 주로 살충제를 이용하고 있으나 이들의 강한 이동성과 농약 잔류, 작업자에 대한 농약 노출 등의 문제를 야기하는 단점이 있어 이러한 문제를 해결할 수 있는 새로운 해충 방제 수단이 필요한 실정이다. 본 연구는 사과원의 주요 노린재 중 썩덩나무노린재와 갈색날개노린재의 알을 이용하여 사과원 주변의 알 기생봉을 탐색하고 이들에 대한 야외 기생률을 알아보고자 실시하였다. 저온 저장된 두 종의 알을 사과원에 배치하고 이후 수거하여 알에서 채집된 기생봉을 동정한 결과 썩덩큰검정알벌(Trissolcus japonicus Ashmead)로 확인되었다. 야외 기생률은 썩덩나무노린재의 경우 약 27%, 갈색날개노린재는 21%로 나타났다. 추후 이 기생봉에 대한 생태 특성, 인공 사육, 야외 방사 기술 등의 생물적 방제제로 활용하기 위한 다양한 연구를 진행할 예정이다.

이동성 해충인 벼 멸구류를 조사하기 위해 우리나라를 포함한 아시아지역 12개국 13기관에서 농촌진흥청 아시아식량작물협력협의체(AFACI) 프로그램의 일환으로 “아시아지역 이동성 병해충 국제협력 네트워크 구축”프로젝트를 수행하고 있다. 본 연구에서는 벼 멸구류 및 거미류 의 포장 발생 실태를 파악하기 위해 2016년부터 2018년까지 경남 밀양, 전남 신안, 전북 완주지역의 무농약 논포장에서 6월말부터 9월말까지 점착트랩을 이용한 타락법으로 멸구류 발생 상황을 조사하였다. 2018년도에 애멸구는 7월 중순 이후에 밀도가 높아졌고, 흰등멸구는 신안지역에서 8월 이후에 밀도가 증가하기 시작하였다. 벼멸구는 모두 지역에서 발견되지 않았다. 거미류는 모든 지역에서 후반기로 갈수록 개체수가 증가하고, 9월 초순에 가장 많이 발생하였다.

In Vietnam, reclaimed asphalt pavement technology is considered as the key to reduce the cost of pavement construction, and decrease the industrial waste from flexible pavement rehabilitation. Ministry of Transportation has concentrated to develop RAP technology since 2008. As a result, there are three trademark of recycling technologies applied in Vietnam such as Wirtgen (Germany), Hall Brothers (U.S.), and Sakai (Japan). This paper is focused on asphalt pavement investigation of field and laboratory tests from Cold In-place recycling technology. The laboratory tests carried out on the material were conventional tests including Marshall stability, indirect tensile strength... Field data was collected using a Benkelman beam and core specimens for indirect tensile strength test.

PURPOSES: The occurrence of unexpected disasters, including fire events, increases as the road network becomes complicated and traffic volume increases. When a fire event occurs on and under bridges, the damage extensively influences direct damage to structures, vehicles, and human life and secondary socioeconomic issues owing to traffic blockage. This study investigated potential fire-hazard risks on bridges of the Korean national route roadMETHODS: The investigation was conducted using field investigation and analysis with satellite pictures and road views from commercial websites and the Bridge Management System (BMS). From the filed investigation, various potential fire resources were identified. The satellite pictures and road views were helpful in measuring and recognizing conditions underneath bridges, stowage areas, etc.RESULTS : There are various potential fire resources underneath bridges such as piled agricultural products, parked petroleum tanks, construction equipment, and attached high-voltage cables. A total of 94.6% of bridges have underneath clearances of less than 15 m. A bridge underneath volume that can stow a potential fire hazard resource was 7,332 m3 on average, and most bridges have about 4,000 m3 of space. Based on the BMS data, the amounts of PSC and steel girders were 29% and 25%, respectively.CONCLUSIONS : It was found that the amount of stowed potential fire hazard resources was proportional to the underneath space of bridges. Most bridges have less than 15 m of vertical clearance that can be considered as a critical value for a bridge fire. The fire risk investigation results should be helpful for developing bridge fire-protection tools.

We propose a custom analysis technique for the dark field (DF) image based on transmission electron microscopy (TEM). The custom analysis technique is developed based on the DigitalMicrograph® (DM) script language embedded in the Gatan digital microscopy software, which is used as the operational software for most TEM instruments. The developed software automatically scans an electron beam across a TEM sample and records a series of electron diffraction patterns. The recorded electron diffraction patterns provide DF and ADF images based on digital image processing. An experimental electron diffraction pattern is recorded from a IrMn polycrystal consisting of fine nanograins in order to test the proposed software. We demonstrate that the developed image processing technique well resolves nanograins of ~ 5 nm in diameter.

PURPOSES: The purpose of this study is to suggest a specific investigation guideline to decide priority of repairing old concrete pavements that pile up substantially. METHODS : In this study, a principle of division of homogeneous sections was proposed to reflect the characteristics of the pavement reasonably in the specific investigation results. In addition, a checklist and guideline of field investigation were suggested for the old concrete pavement sections, which require inspection toward their durability and structural performance. Furthermore, the items of laboratory test necessary to the old concrete pavement were suggested based on the existing laboratory test considering characteristics of the old concrete pavement. The present condition of the old concrete pavement could be analyzed by the test results. RESULTS: A method of division of homogeneous sections suitable for the specific investigation of the old concrete pavement was suggested. The proportions of distress severity of pavement sections were compared by distress type to figure out the present state of the old concrete pavement. Scaling, durability cracking (or alkali-silica reaction), and longitudinal spalling were selected as the most severe distress types. The detailed positions of the sections were also suggested. The checklist of the specific investigation was categorized by field survey and laboratory test, and its evaluation criteria were proposed. The three types of the sections of durability cracking (or alkali-silica reaction), bridge connection, and asphalt overlay were selected as the sections of the field survey. The compressive strength, void structure, and chloride penetration depth were suggested as the items of the laboratory test. CONCLUSIONS : A fundamental level of the guideline was suggested in this study to resolve the problem of old concrete pavement. Appropriate guidelines related to the repair of the old concrete pavement should be provided by performing additional research efforts.

이 논문에서는 게이트 절연막 위에 vapor deposition polymerization(VDP)방법을 사용하여 성막한 유기 점착층을 진공 열증착하여 유기 박막 트랜지스터(OTFTs)소자를 제작할 수 있음을 증명하였다. 우리가 제작한 Staggered-inverted top-contact 구조를 사용한 유기 박막 트랜지스터는 전기적 output 특성이 포화 영역안에서는 포화곡선을, triode 영역에서는 비선형적인 subthreshold를 확실히 볼 수 있음을 발견했다. 0.2μm 두께를 가진 게이트 절연막위에 유기 점착층을 사용한 OTFTs의 장 효과 정공의 이동도와 문턱전압, 그리고 절멸비는 각각, 약 0.4cm2/Vs, -0.8V, 106 이 측정되었다. 게이트 절연막의 점착층으로써 폴리이미드의 성막을 위해, 스핀코팅 방법 대신 VDP 방법을 도입하였다. 폴리이미드 고분자막은 2,2bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride(6FDA)와 4,4'-oxydianiline(ODA)을 고진공에서 동시에 열 증착 시킨 후, 그리고 150℃에서 1시간, 다시 200℃에서 1시간 열처리하여 고분자화된 막을 형성하였다. 그리고 점착층이 OTFTs의 전기적 특성에 주는 영향을 설명하기 위해 비교 연구하였다.

About one hundred twenty thousand (±twenty thousands) people are wounded and about two thousand persons are dead from industrial accidents in Korea ［1］, Therefore, Korea is notoriously called as a haven of disaster. This study investigated the safety situation of industries and attitude of safety managers to reduce the occurrence of accidents. The period of investigation was during March through August, 1977. Two hundreds of safety managers were replied, but replies of 183 were used because some of them were inappropriately answered for the questions. Their replies were analyzed by SAS program. As a result, only three persons out of 183 managers were women, 83% of them are married, 25.1% were graduated from university, 15.2% were graduated from two-year college. Full time safety managers were only 8% of them. Safety managers who have experienced injured before their current position were 26.3%. This confirms that company allocated injured persons to a safety department. Korea also needed an educational agency like NIOSH and a punishment agency like OSHA in USA［5］. These agencies can solve a fundamental problem of safety management for small-and-medium size industries. Furthermore, a new safety management bureau for controlling these two agencies will be necessary to reduce accidents in near future.

This study evaluated the orientation control of steel fibers in cementitious materials using magnetic field. With the increases in the range of the magnetic field, the effective length of the orientation control of the steel fiber is increased and the orientation control effect is larger.