This study numerically investigates flexural behavior of press braked U-type section girders for fabrication simplicity. In order to improve structural stability during construction, the top flanges of press braked U section girder are laterally braced by installation of precast half-deck. Thus, laterally unbraced length is taken by the pocket spacing of the half-deck. This study performed 3D nonlinear finite element analyses on the U-type section girders along with inner bend radii to thickness ratio (ri/t). The numerical models reflect initial imperfection and residual stress. Through the finite element analyses, the flexural strength of the press-braked U-type section models were compared with those of general welded girder.

It has been more than twenty years since the application of GFRP bridge decks in construction fields. Recently, a few studies by governments and individual researchers have investigated in-use GFRP bridge decks. Areas of trouble include the problems of cracking, spalling and the de-bonding of the pavement or the wearing surface on GFRP bridge decks, all of which affect the long-term durability and serviceability of these new construction materials. Related to these problems, reflective cracks on asphalt pavement are directly related to pultruded GFRP bridge decks. This study investigates the behavior of an adhesive joint under weak-axis bending by tests and FE analyses to identify the causes of pavement cracks in in-use pultruded GFRP bridge decks. In detail, the flexural stiffness and the load-carrying capacities in strong and weak axes are measured during bending tests on pultruded GFRP decks. Next, tensile local failures of an epoxy adhesive due to the concentration of deformations at adhesive joints are identified via a weak-axis bending test. Finally, the tensile failure of an epoxy adhesive due to the local concentration of deformation at an adhesive joint under weak-axis bending is verified through a finite element analysis.

In recent days composite bridge decks are increasingly used to new and rehabilitated bridges due to their many advantages such as light weight, high strength, high durability, low maintenance costs and fast installation. To further promote usage of composite bridge decks, the authors have developed decks of new profile having innovative vertical snap-fit connection. Through this development, significant enhancement of constructability and economy are obtained by overcoming the drawbacks of conventional composite decks of tongue-and-groove connection. The paper introduces some research results and notable applications for the developed composite decks of snap-fit connection using for pedestrian bridges. Owing to their considerable advantages of the developed composite decks, increasing number of applications is currently underway in Korea.

This study was conducted to evaluate the health risk of workers exposed to phenyl glycidyl ether to prevent themfrom developing occupational diseases. The workplaces that coat floor with epoxy were selected and the sampleswere collected and analyzed with NIOSH 1619 Method. Unit risk was calculated according to the animalcarcinogenicity study. Excess cancer risk was also calculated by multiplying unit risk by exposure concentration.Monte Carlo simulation was performed to calculate the median, cumulative 90%, and cumulative 95% value.Phenyl glycidyl ether is a skin, eye irritator and can result in allergic reaction, nausea, intoxication. Unit risk wascalculated as 0.04 (mg/m³)-¹ based on the tumor incidence in rats. Geometric mean and geometric standarddeviation was also calculated as 0.112 ppm and 0.223, respectively by the workplace environment measurements.The median, cumulative 90%, and cumulative 95% value of excess cancer risk were calculated as 0.0244, 0.1328,0.1596, respectively. Not only cumulative 90% and cumulative 95% value but also the median of excess cancerrisk is much higher than 1×10-⁴ by the risk characterization, so there is a possibility of carcinogenesis to workers.Therefore, supervisors or managers of each workplace have to keep doing the risk management of their workplacesfor workers to reduce exposure to phenyl glycidyl ether.

본 연구에서는 2경간 합성바닥슬래브의 기여도를 반영하여 철골모멘트골조의 연쇄붕괴저항성능의 더욱 정확한 평가를 위해 사용할 수 있는 개선된 에너지기반 비선형정적 해석법을 제시하고자 한다. 이를 위해, 우선 재료적/기하학적 비선형 유한요소해석을 수행하여 2경간 합성바닥슬래브의 거동을 살펴보았다. 2경간 합성바닥슬래브의 변형형상을 이상화하여 에너지기반 해석을 위한 근사모델을 개발하였다. 제안모델은 기둥제거 시나리오하에서 2경간 합성바닥슬래브의 일방향 축인장력 및 변형에너지응답을 모델링하는데 쉽게 이용할 수 있음을 보여주고 있다.

온돌은 동북지방주거에서는 가장 중요한 요소 중 하나이다. 약 2천 년 남짓 유구한 역사 동안, 독특한 온돌양식과 온돌문화를 형성하였으며, 아파트온돌, 라지에이터, 공기조화 난방 등으로 발전하였다, 온돌은 동북 대가족 문화의 주요한 요소일 뿐 만 아니라, 농가의 공간형성과 구축에도 중요한 단서이다. 온돌은 자연형 에너지사용으로 고효율 방식이다. 전통의 온돌-일반적으로 흙 벽돌과 벽돌을 쌓아서 만들고, 음식을 할 때 사용되는 그 여열을 통해 외부와 연결된 부뚜막을 통해 내부와 연결된 고래가 있는 방구들을 지나 굴뚝으로 열을 전달한다. 오늘날 동북의 신농촌은 아주 빠른 건설개발단계에 있다. 기술의 발전과 관념의 변화에 따라, 사람들은 전통온돌을 기반으로 한 혁신적인 시도들을 선보이고 있다. 새로운 온돌을 만들어 내기도 한다. (뜬바닥온돌,에너지절약온돌 등.) 신형온돌은 전통온돌의 모든 기능을 계승할 뿐만 아니라, 지속가능한 발전의 요구와도 맞는다. 즉 전통문화에 현대적 기술을 결합한 형태이다. 본 논문은 동북지역농가를 연구대상으로 하였으며, 온돌의 내포된 함의, 형식과 종류, 난방방식 및 기타 신형 온돌의 발전과 변천에 대해서 다루고 있다.

PURPOSES: The purpose of this study is to evaluate physical properties, durability, fatigue resistance, and long-term performance of poly-urethane concrete (PU) which can be possible application of thin layer on long-span orthotropic steel bridge and to check structural stability of bridge structure. METHODS : Various tests of physical properties, such as flexural strength, tensile strength, bond strength and coefficient of thermal expansion tests were conducted for physical property evaluation using two types of poly urethane concrete which have different curing time. Freezing and thawing test, accelerated weathering test and chloride ion penetration test were performed to evaluate the effect of exposed to marine environment. Beam fatigue test and small scale accelerated pavement test were performed to assess the resistance of PU against fatigue damage and long-term performance. Structural analysis were conducted to figure out structural stability of bridge structure and thin bridge deck pavement system. RESULTS: The property tests results showed that similar results were observed overall however the flexural strength of PUa was higher than those of PUb. It was also found that PU materials showed durability at marine environment. Beam fatigue test results showed that the resistances of the PUa against fatigue damage were two times higher than those of the PUb. It was found form small scale accelerated pavement test to evaluate long-term performance that there is no distress observed after 800,000 load applications. Structural analysis to figure out structural stability of bridge structure and thin bridge deck pavement system indicated that bridge structures were needed to increase thickness of steel deck plate or to improve longitudinal rib shape. CONCLUSIONS: It has been known that the use of PU can be positively considered to thin layer on long-span orthotropic steel bridge in terms of properties considered marine environment, resistance of fatigue damage and long-term performance.

This study aims to examine the light weight impact sound insulation of dry type system in apartment house. To achieve this goal, sounds which have same loudness according to rating methods were suggested to subjects. And followings are results. 1) The measurement frequency level average of dry type system-on is more suitable than that of dry type system-off which are dependent on specific frequency for light-weight floor impact sound. 2) Level average for measurement frequency of 100∼ｾ500Hz is more correspondent to vibration-acoustic response than that of measurement frequency of 100∼!500Hz which is for KS F 2863-2, existing rating method.

국내 고속도로의 교량은 2000년 이후 집중된 선형개량 및 신규 노선 증가 사업으로 10년 전과 비교하여 2배 이상 증가하였다. 이에 따라 유지관리 비용도 지속적으로 증가하고 있다. 현재 고속도로 유지관리 예산 비중이 가장 높은 항목은 아스팔트 교면 교량의 콘크리트 바닥판 열화에 의한 보강 부분이다. 2011년 고속도로 관리교량은 약 7,800여개에 도달한 시점에서 현재 방법으로는 향후 어느 정도 바닥판 보강 예산이 필요한지 어느 시기에 증액을 하여야되는지 명확하게 추정하기 어렵다. 본 연구에서는 신뢰도 분석 방법인 와이불 분포에 의한 생존 수명 예측 기법을 적용하여 현재 고속도로 아스팔트 계열의 교면 교량의 평균 수명을 추정하였고 이를 토대로 향후 예상 보강 비용을 추정하였다.

본 논문은 노후교량바닥판 대체용으로서 하이브리드 GFRP-강재 바닥판의 휨거동을 구조적 거동특성을 기술하고 있 다. 하이브리드 GFRP-강재 바닥판의 구조적 특성을 조사하기 위해 정적하중의 실험적 연구를 수행하였다. 하이브 리드 바닥판의 파괴모드는 초기항복을 지나서 연성거동을 나타내었다. 결과는 유한요소프로그램 ANSYS의 값과 비 교하였다. 제안된 하이브리드 바닥판이 교량적용에 유용함을 확인하였다. 하이브리드 바닥판의 두께는 유사한 휨 강성을 갖는 완전복합신소재 바닥판께와 비교하였을 때 감소될 수 있었다.

This paper presents the flexural behavior of a hybrid Glass Fiber-Reinforced Polymer(GFRP)-steel decks for use in deteriorated bridge decks replacement. Static load tests were conducted to investigate the structural characteristics of the hybrid FRP-steel deck. The tested deck panel satisfied the design criteria. The failure mode of the hybrid deck was demonstrated ductility with deformation beyond initial yielding. The responses were compared with the ANSYS finite element predictions. It was found that the presented hybrid deck was efficient for use in bridges. The thickness of the hybrid deck may be decreased when compared to that of the all FRP deck with similar flexural rigidity.

A system has been developed to reduce fluctuation of the indoor temperature in a radiant floor heating system. The system we developed and implemented is called BoilerMan. With the BoilerMan system the hot water circulation pump is controlled by computer software which implements a unique strategy. To minimize the system development time a user-friendly development environment was used. This development environment was useful in the implementation and testing of the efficiency of our strategy. The environment also serves as an easy means for system maintenance. The BoilerMan went through a few test runs against a real apartment house and the result showed significant reductions in the initial temperature overshoots against the target values. It also reduced the operatingtime of the hot water circulation pump. Such positive results were possible due to our unique strategy that exploits heating efficiency information collected from the past run of the very same system. Since the strategy was implemented with embedded software, it makes the BoilerMan flexible, too.

본 연구에서는 노후교량 바닥판 대체용으로 단품(Modular) GFRP 바닥판 구조에 대한 거동분석을 실험을 통행 실시 하였다. 그 바닥판의 성능평가로서 축소모형(1/5)의 시험편 3개에 대한 실험적 연구를 수행하였다. 시험편은 박스튜 브를 갖는 샌드위치 판이다. 교량바닥판의 구성재료는 유리섬유와 에폭시 레진이다. 모든 시험편에 대한 실험결과 로서 최대강도, 강성 및 변형능력으로 나타내었다. 실험적 결과의 타당성을 검증하기 위해 유한요소해석을 하여 비 교하였다.