• Structural Monitoring and Maintenance
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• 제9권4호
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• pp.305-321
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• 2022

Bridge structural health monitoring with the aim of continuously assessing structural safety and reliability represents a topic of major importance for worldwide infrastructure managers. In the last two decades, due to their potential economic and operational advantages, drive-by approaches experienced growing consideration from researcher and engineers. This work addresses two technical topics regarding indirect frequency estimation methods: bridge and vehicle dynamics overlapping, and bridge expansion joints impact. The experimental campaign was conducted on a mixed multi-span bridge located in Lombardy using a Ford Galaxy instrumented with a mesh of wireless accelerometers. The onboard time series were acquired for a number of 10 passages over the bridge,performed at a travelling speed of 30 km/h, with no limitations imposed to traffic. Exploiting an ad-hoc sensors positioning, pitch vehicle motion was compensated, allowing to estimate the first two bridge bending frequencies from PSD functions; moreover, the herein adopted approach proved to be insensitive to joints disturbance. Conclusively, a sensitivity study has been conducted to trace the relationship between estimation accuracy and number of trips considered in the analysis. Promising results were found, pointing out a clear positive correlation especially for the first bending frequency.

• 드라이브 ㆍ 컨트롤
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• 제15권2호
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• pp.9-21
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• 2018

The aim of this study was to develop and test a model of an auto-sensing hydraulic breaker that can automatically change its 4-step impact mode according to the rock strength using SimulationX. The auto-sensing hydraulic breaker with a 4-step variable impact mode has the advantage of obtaining optimal impact energy and impact frequency under various rock conditions compared to an auto-sensing hydraulic breaker with a 2-step variable impact mode, which has already been developed overseas. Several steps were necessary to conduct this study. First, the operation principle of the auto-sensing hydraulic breaker with the 2-step variable impact mode was analyzed. Based on the findings, an analysis model of the auto-sensing hydraulic breaker with the 4-step variable impact mode was developed (and compared with the 2-step variable impact mode) Finally, an analysis of the results established that the stepwise variable of the impact mode was implemented according to the rock strength and the difference of each impact mode was confirmed. This study is expected to contribute to the development of auto-sensing hydraulic breakers that are superior to those developed by advanced companies in foreign countries.

• 한국자동차공학회논문집
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• 제17권5호
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• pp.133-139
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• 2009

When two cars impact each other, it is usually known smaller vehicle's passenger likely to be more seriously injured than bigger one's. Generally it is known that SUVs and Light Truck Vehicles (LTVs) are bigger and heavier than passenger vehicles and their drive height such as bumper rail and side member, and front end stiffness are higher than those of passenger vehicles. Because of these characteristics the occupants of passenger vehicle struck by SUVs or LTVs are more likely to experience severe injury or fatal injury. To evaluate SUV and LTV's aggressivity to passenger vehicle, SUV to passenger vehicle and LTV to passenger vehicle head-on crash test have been carried out. And finally the way how to reduce incompatibility between SUV and LTV and passenger vehicles is suggested.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.72-77
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• 2007

Since 2000, sports utility vehicles(SUVs) occupy about 40% of domestic vehicle sales. As sports utility vehicle sales are increased the probability of crash accident between SUVs and passenger vehicles increases. Generally, SUVs are heavier than passenger vehicles and their drive height and front end stillness are higher than passenger vehicles. Because of these characteristics SUVs cause more severe injury and fatal injury in SUV to passenger vehicle head-on impact. To evaluate SUV's aggessivity to passenger vehicle, we carried out SUV to passenger vehicle head-on crash test. And finally the way how to reduce incompatibility between SUVs and passenger vehicles is suggested.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 추계학술대회논문집; 한국과학기술회관, 8 Nov. 1996
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• pp.324-329
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• 1996

Vibration characteristics of the feeding system in a CD-ROM drive are identified by a theoretical modeling as well as vibration experiments. For this purpose, we establish a vibration model due to the rigid-body motion and perform the modal testings using the impact hammer and shaker. The analysis and experiments show that the feeding system has three rigid-body vibration modes in the low-frequency region and two of them come from the tilting modes. In order to remove the harmful tilting modes for the tracking servo control, a methodology to find the optimal positions of the dampers is also proposed in this study.

• International Journal of Advanced Culture Technology
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• 제10권2호
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• pp.116-121
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• 2022

Digital technology has now pervaded and become an inseparable part of our daily life. The art museum sector is evolving into a business model that adapts to the new digital format due to the requirement for survival and development. This study examines the development state of China's art museum industry and investigates the current business model innovation trend in the art museum industry from three perspectives: reorganization and development of the art museum industry's business model theory; reconstruction of the art museum industry's display and marketing logic; and innovation of the art museum industry's operation mechanism, based on a systematic assessment of domestic and international research. This research can provide reference value for digital technology to drive the innovation of business model in art museum industry. Moreover, the study has important reference significance for the development strategy of art museum industry.

• 로봇학회논문지
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• 제19권3호
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• pp.229-235
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• 2024

This research focuses on reducers, vital components in service robots, with a special emphasis on friction reducers designed for use in environments where interaction with humans is essential. For service robots to effectively perform advanced tasks, it is crucial to have reducers that offer high precision, high reduction ratios, and strong resistance to impacts. To meet these requirements, our study introduces a new design methodology and proposes a friction reducer featuring a multi-layer ball array structure. Compared to traditional gearbox-based reducers, the friction reducer developed in this study demonstrates a higher reduction ratio and improved shock absorption. The performance of this newly proposed reducer has been verified through experimental analysis. It was confirmed that by minimizing drive losses, the system has high backdrivability, delivering a torque of 15 Nm. Additionally, it was observed that the system showed an immediate response without backlash to fine input vibrations.

• 전력전자학회논문지
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• 제12권3호
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• pp.221-233
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• 2007

본 논문에서는 고성능 단축 선형전동기에 적용할 수 있는 최단시간 위치 패턴 알고리즘에 대하여 논한다. 근래 들어 LCD/PDP 및 반도체 산업이 발달함에 따라 대형의 고성능 위치제어 시스템에 대한 요구가 높아지고 있으며 이러한 시스템에서는 공정 주기의 단축을 위하여 시간요소를 최소화시킨 최적 위치 패턴이 반드시 필요하다. 특히 반도체 산업 분야에서는 공작기계 분야와 달리 3차원 입체 위치 패턴보다는 단축 패턴에 대한 수요가 비교적 많은 편이다. 본 연구에서는 가속도가 사다리형인 위치 패턴을 기본으로 하여 연구를 진행하였으며 위치 및 시간을 변수로 고려한 패턴 분석을 통하여 최단시간에 목적하는 위치에 도달하기 위한 패턴을 비교적 간단히 구현할 수 있음을 보이고 이를 시뮬레이션 및 간이 실험으로 구현 가능성을 입증하였다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.4-4
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• 2008

The progress in flat panel displays over the last two decades has been astonishing. In just 20 years, the LCD-TV grew up from a 2-inch curiosity, to an industry that will sell about 120 million flat panel TV's this year, with viewing area up to 4000 times larger. That success is based on continuous innovation, especially in manufacturing processes. For the next decade to bring another doubling of the business, progress will need to continue in four major areas: Human factors, ecological impact, visual quality, and of course continued drive towards affordability. This talk will detail the technology advances that can allow this industry to meet those challenges. Human factors. Today, we adapt our lifestyle to our technology. People organize their offices, and their homes, around displays. We pass around mobile phones to share images, rather than experiencing them as a group. Billions of newspapers continue to be sold daily. Advances in flexible displays can lead to large portable displays. "New era projection" includes the handheld Pico Projectors that are already on the market, and will ultimately appear integrated in mobile phones the same way cameras do today. "Eco" impact. Today TV's are one of the top energy consumers in a U.S. home, and the fastest growing. Watching a large flat panel TV can cost twice as much as running a large refrigerator. With today's concern about energy consumption, regulations are starting to emerge worldwide to limit TV electrical use. Fortunately, good solutions exist in using light management films to eliminate bulbs, saving power without increasing cost. Going forward, LED backlights will drive another step downward. OLED displays might be the ultimate solution. Visual quality. The color of an LCD-TV is still often considered inferior to a far less expensive CRT. And almost all displays suffer from representing a three-dimensional world on a two dimensional surface. The technology to improve color is available today, and will likely move from premium sets into the mainstream as costs come down. 3D is now arriving in movie theaters worldwide, and that will drive up the demand for similar realistic images in home theaters. And the technology is emerging today for 3D representation to move beyond specialized applications into everyday use, on screens large and small. Affordability. The world takes cost-down miracles for granted in consumer electronics. Each of these other advances will be balanced with a drive for affordability, especially as the market grows in emerging countries. The other three challenges must be met without increasing cost. Putting this all together, the next few years will emphasize "eco friendly" designs, and enhanced images such as 3D. By 2013 we will start to see serious penetration by emissive technologies (OLED, high efficiency plasma, or other), with the "ultimate display" likely not in the market for a decade. Lots of opportunities for innovation remain ahead of us.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 the technical trends in the world automobile and lubricant market
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• pp.55-62
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• 2002

Significant changes in the performance requirements of finished lubricants is having a pronounced impact on the quality and manufacturing approach for base stocks, the building block for these products. Separation processing is no longer capable of producing high yields of premium base stocks and is rapidly being replaced with hydroprocessing. Isoparaffins are the most desirable component because of their high Viscosity Index, low pour point and excellent stability. This paper will discuss industry trends and the drive towards higher quality base stocks. Manufacturing options are discussed and examples presented to demonstrate the performance of these premium base stocks.