• Structural Monitoring and Maintenance
• /
• 제5권4호
• /
• pp.429-443
• /
• 2018

Fatigue is a principal failure mode for steel structures, and it is still less understood than any other modes of failure. Fatigue life estimation of metal bridges is a major issue for making cost effective decisions on the rehabilitation or replacement of existing infrastructure. The fatigue design procedures given by the standard codes are either empirical or based on nominal stress approach. Since the fatigue life estimation through field measurements is difficult and costly, more researches are needed to develop promising techniques in the fatigue analysis of bridges through Finite Element Analysis (FEA). This paper aims to develop a methodology for the Fatigue life estimation of railway steel bridge using FEA. The guidelines of IIW-1823-07 were used in the development of the methodology. The Finite Element (FE) package ANSYS and the programming software MATLAB were used to implement this methodology on an Indian Railway Standard (IRS) welded plate girder bridge. The results obtained were compared with results from published literature and found satisfactory.

• 드라이브 ㆍ 컨트롤
• /
• 제19권1호
• /
• pp.1-7
• /
• 2022

Recently, a re-painting robot was developed to semi-automatically conduct blasting work in bridge spaces to improve work productivity and worker safety. In this study, a vision sensor-based monitoring module was developed to automatically move the re-painting robot along the path. The monitoring module provides direction information to the robot by analyzing the boundary between the painting surface and the metal surface. To stably measure images in unstable environments, various techniques for improving image visibility were applied in this study. Then, the driving performance was verified in a similar environment.

• Design & Manufacturing
• /
• 제6권1호
• /
• pp.79-83
• /
• 2012

Anti-theft safety caps for bolted joints are necessary to ensure the safety of citizens and prevent theft of manholes, bridge guardrails, bulletin boards, subway safety handrails and others. Safety caps enhance the look of bolted joints, avert accidents that involve hitting the head of bolts, hamper them from coming loose by covering the head of bolts. This study focuses on press die design methods and press molding condition setting to resolve bursting and cracks in products, and on molding material selection and heat treatment technologies to boost life extension.

• 한국환경과학회지
• /
• 제5권4호
• /
• pp.481-494
• /
• 1996

This study was performed to investigate the relationship between concentrations of heavy metals in sediment and the depths of 27 sampling sites along the West Nakdong river in downstream of Nakdong River. The deepest site was Kangdong bridge nearby 20ft. From here, the depth was shallowed to Chidong gradually. In each site the smaller mesh was, the liger concentration of heavy metal becomed. Concentration of Zn, Cd, Cr and Cu at inflow point of Shinoe stream was 576.016 ppm, 262.307 ppm, 68.674 ppm and 61.634 ppm, respectively, the concentration was the higest at this point. From here, it was lowered gradually. The concentration of heavy metal at inflow point of Joman river was 155.328 ppm, 56.485 ppm, 25.200 ppm and 31.172 ppm, respectively, those concentrations were liger than other points with the exception of Shinoe stream. Therefore, woman river and Shinoe stream were the major source of pollution in West Nakdong river. Among two sources Shinoe stream was more important source of pollution. West Nakdong river has become lake by Noksan floodgate because it's pollution has had influence on Bonglim.

• 전기학회논문지
• /
• 제58권4호
• /
• pp.756-762
• /
• 2009

This paper proposes a high efficient Dual Buck Inverter design with a zero voltage switching (ZVS) control technique. The ZVS control is realized by adding a feedback loop circuit which is implemented by simple RS latch and TTL gate. The used load was 200W -Ceramic Metal Halide Lamp. The experimental results show that the proposed Inverter system could avoid the acoustic resonance and achieve high efficiency by Zero Voltage Switching.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2001년도 하계학술대회 논문집 C
• /
• pp.1372-1374
• /
• 2001

This paper describes fabrication and characteristics of metal thin-film pressure sensor for working at high temperature. The proposed pressure sensor consists of a chrom thin-film, patterned on a Wheatstone bridge configuration, sputter-deposited onto thermally oxidized Si membranes with an aluminium interconnection layer. The fabricated pressure sensor presents a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.097 $\sim$ 1.21 mV/V kgf/$cm^2$ in the temperature range of 25 $\sim$ $200^{\circ}C$ and the maximum non-linearity is 0.43 %FS.

• Journal of Welding and Joining
• /
• 제15권3호
• /
• pp.47-55
• /
• 1997

Dynamic characteristics of the short circuit mode are investigated using the Volume of Fluid (VOF) method. When the initial molten drop volume, contact area and wire feed rate are given, rate change of the molten bridge profiles, pressure and velocity distributions are predicted. The electromagnetic force with proper boundary conditions are included in the formulation to consider the effects of welding current. It is found that the molten metal is transferred to the weld pool mainly due to the pressure difference caused by the curvatures in the initial stage, and electromagnetic force becomes dominant factor in the final stage of short circuit transfer. Necking occurs at the contact position between the molten drop and weld pool, and the initial molten drop volume and welding current have significant effects on break-up time.

• Journal of Electrical Engineering and Technology
• /
• 제1권4호
• /
• pp.496-502
• /
• 2006

In this paper, we studied the development of the electronic ballast for 250W MH (Metal-Halide) lamps. We were able to improve the input power factor by using a PFC IC. To provide the lamp with the rated voltage required, we used the buck-type dc-dc converter. The stress of the switching devices in the inverter could be reduced by this method. To eliminate the acoustic resonance phenomena of MH lamps, the voltage of the lamp added the high frequency sine-wave to the low frequency square-wave by using the full bridge typed inverter. We have developed a simple igniter using the L and C elements. We could control the dimness of the lamp by varying the output voltage of the buck converter. The buck converter output voltage could be controlled by using a microprocessor.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.587-590
• /
• 2000

This paper presents the characteristics of metal thin-film pressure sensors. The micro pressure sensors consists of a chrom thin-film, patterned on a Wheatstone bridge configuration, sputter-deposited onto thermally oxidized Si wafer an aluminium interconnection layer. The fabricated micro pressure sensors shows a low temperature coefficient of resistance, high-sensitivity, low non-linearity and excellent temperature stability. The sensitivity is 1.16~1.21 mV/V.kgf/$\textrm{cm}^2$ in the temperature range of 25~l0$0^{\circ}C$ and the maximum non-linearity is 0.21 %FS.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2001년도 전력전자학술대회 논문집
• /
• pp.556-559
• /
• 2001

In this paper, we proposed AC/DC boost converter to improve input current harmonic reduction in SMAW(shielded metal-arc welding). The proposed harmonic reduction with the boost converter design and the UC2854 integrated circuit which controls the converter, The topology of welding power supply is made of a pair of boost converter and welder half-bridge IGBT inverter. The voltage arc is modeled by a variable resistance in series with a voltage source. The results has been confirmed by PSIM simulation tool. The simulation results show that input at current is nearly sinusoidal with low harmonic contents and sinusoidal input current waveform at high power factor.