• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2007년도 정기총회 및 학술발표대회
• /
• pp.67-70
• /
• 2007

A methodology to evaluate fatigue vulnerability of steel bridge members affected by corrosion and truck traffic variation is proposed. A fatigue limit state function including corrosion and traffic variation effects is established to make the criterion whether the steel bridge member is damaged by fatigue. Corrosion effects are expressed as increase of the average corrosion depth, and the traffic variation effects are modeled as the accumulated number of stress cycles. Reliability analysis is carried out by Monte-Carlo simulation method for the fatigue limit state function. The methodology Proposed is verified by comparing reference study and applying for the steel bridge in service.

• Journal of Power Electronics
• /
• 제14권2호
• /
• pp.324-340
• /
• 2014

Recent developments in power electronics technology have spurred interest in the use of renewable energy sources as distributed generation (DG) generators. The key component in DG generators is a grid-connected inverter that serves as an effective interface between the renewable energy source and the utility grid. The multifunctional inverter (MFI) is special type of grid-connected inverter that has elicited much attention in recent years. MFIs not only generate power for DGs but also provide increased functionality through improved power quality and voltage and reactive power support; thus, the capability of the auxiliary service for the utility grid is improved. This paper presents a comprehensive review of the various MFI system configurations for single-phase (two-wire) and three-phase (three- or four-wire) systems and control strategies for the compensation of different power quality problems. The advances in practical applications and recent research on MFIs are presented through a review of nearly 200 papers.

• 한국지진공학회:학술대회논문집
• /
• 한국지진공학회 2002년도 추계 학술발표회 논문집
• /
• pp.51-60
• /
• 2002

In this study we developed the visualization scheme of spatial ground-motion measurements in real time by using DSS data. Even though this scheme itself is useful for national earthquake mitigation plans, this scheme could be served as the crucial core for constructing rapid earthquake damage evaluation system. DSS is the abbreviation of Data Subscription Service and this is the pre-assigned request for the seismic stations to send very limited brief data with high priority and negligible transmission load. In addition to visualize the damage area with intensity, the corresponding epicenter can be estimated roughly for quick event alarm. For the interpolation of spatially irregular PGA data, the program, named as surface. of GMT was used with NetCDF grid file format. Since the grid file is similar to a postscript file, the program, called as shading, was coded with C language by using Matpak library in order to convert grid files into image files.

• Journal of Welding and Joining
• /
• 제31권3호
• /
• pp.22-30
• /
• 2013

Due to ELV banning, automotive electronics cannot use four kinds of heavy metal element (Pb, Hg, Cd, $Cr^{6+}$) from 2016. Therefore, this study was focused on degradation characteristics of Sn-3.0Ag-0.5Cu Lead-free solder joint with OSP and ENIG finsh under various reliability assessment method, as like to thermal shock test and high temeprature/high humidity test with test duration for cabin electronics. Also, we compared bonding strength degradation to other advanced research results of electronic control unit for engine room because of difference service temperature with mount location in automotive. Whisker growth phenomenon and mitigation method which were essentially consideration items for Pb-free car electronics were examined. Conformal coating is a strong candidate for mitigating whisker growth in automotive electronics. Necessary condition to adapt Pb-free in car electronics was shown.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.39-42
• /
• 2007

It is necessary to estimate the dynamic characteristics of stay cables ie., the natural frequencies and the damping ratios of the stay cables to design cable damper for appropriate mitigation of cable vibrations and/or to estimate the tension of cables in service. In this study, a cable exciting robot for evaluating dynamic characteristics of stay cables has been developed, and the feasibility of the developed system has been demonstrated through a field test on the stay cable installed at the test yard of Highway and Transportation Technology Institute (HTTI). The dynamic characteristics of the stay cable were estimated based on acceleration data as well as displacement measured by digital image processing technique.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2010년도 정기 학술발표대회
• /
• pp.70.1-70.1
• /
• 2010

u-방재City는 첨단 IT 인프라를 기반으로 유비쿼터스기술과 단위서비스를 활용하여 시민이 안전하고 편안하게 생활할 수 있도록 재난으로부터의 피해를 최소화한 도시이며, u-방재City 서비스란 도시의 지능화된 기반시설과 정보통신망을 활용하여 재난상황을 상시 모니터링하고, 이를 통해 재난의 사전 예방과 상황 발생 시 신속한 대응이 가능하도록 하는 서비스로 정의된다. 이러한 u-방재City 서비스는 지역간 서비스간 상호 운용성 확보가 매우 중요하며 국가재난관리의 큰 틀 내에서 추진되어야 하는데, 이를 위해서는 지역의 재난발생 특성과 서비스 수요 및 인프라 여건 등을 종합적으로 조사 분석하여 서비스 모델을 개발하여야 한다. 본연구는 u-방재City 서비스의 체계적인 개발과 효율적인 운영을 위해 지역의 재난발생 특성과 재난관리 업무현황, 서비스 제공을 위한 인프라 여건, 서비스 수요 및 요구사항 등을 조사 분석하고, 이를 토대로 u-방재City 서비스 개발 및 운영 방향을 제시함을 목적으로 한다.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2008년도 정기총회 및 학술발표대회
• /
• pp.469-472
• /
• 2008

In general, structures in service gradually lose original performance according to time due to initial defects in design and construction, or exposure to unfavorable external conditions such as repeated loading or deteriorating environment, and in extreme cases, may collapse in large disaster. Therefore, in order to maintain the serviceability of structures at optimal level, advanced structure measuring system which can inform optimal time point and method of maintenance is required in addition to accurate prediction of residual life the structure by periodic inspection. To guarantee the safety level of bridge structure and to prevent from disaster, the integration of safety network for bridge structures are needed. Therefore in this study, to enhance the effectiveness of safety network for bridge, the connection methodologies between safety network and pre-installed bridge monitoring system are investigated.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2008년도 정기총회 및 학술발표대회
• /
• pp.601-604
• /
• 2008

가속도분석 시스템은 Quanterra 기록계에서 지원하는 DSS(Data Subscription Service)를 이용하여 전국의 가속도계로 부터 수신된 DSS 값을 가속도 값으로 계산한다. 지진발생시 지도상에 관측된 지점의 가속도 값을 표출하고 가속도계의 설치 장소에 따른 가속도 값 특성을 분석하여 분리 적용하는 방안과 가속도계의 비정상 작동에 대한 대책을 연구한다.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2008년도 정기총회 및 학술발표대회
• /
• pp.489-492
• /
• 2008

Nowadays in order to estimate safety diagnosis of bridge, a lot of data like static and dynamic displacement, accelerometer, wind velocity and so on are demanded. When it comes to measure these data, cabled sensor is essential equipment. But cabled sensors have also inefficient factors. From this point of view, considering practical aspects of using these expensive equipments which have been used to examine safety diagnosis, measuring by cabled sensors is restrictive in some respect. Recently to improve theses problems, Wireless sensor system was introduced. But this system can't perform intelligent reaction because database of this system is just based on internet. In this paper, the intelligent bridge safety management model which can be installed easily, measured at all times and dealing intelligently with various situations is developed to improve these problems.

• 한국방재학회:학술대회논문집
• /
• 한국방재학회 2008년도 정기총회 및 학술발표대회
• /
• pp.63-66
• /
• 2008

The bridge deck section composed of a concrete slab resting on two I-beam girders are known to be susceptible to flutter instability and vortex shedding. Moreover, the cable stayed bridge in construction is more vulnerable to wind rather than in service when the free cantilever construction method is applied. This paper describes the effect of the dynamic wind loads on the bridge during construction and the effect of alternative temporary stabilizing measures. Therefore, a series of wind tunnel tests and numerical analysis were carried out to determine if any countermeasures were required.