• 한국통신학회논문지
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• 제35권3B호
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• pp.485-492
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• 2010

지능형 교통 시스템에는 도로 환경 정보 제공, 차량 근거리 네트워크 연동, 추돌사고예방 및 보행자 안전 제공 등의 다양한 분야의 연구가 진행되고 있다. 이와 관련하여 운전자 및 보행자 안전을 위한 감지 정확도, 정보 신뢰성, 유지보수 편의성을 기초하는 USN 기술이 주목 받고 있다. 본 연구는 다양한 센서를 이용하여 USN을 도로에 구축하고 개발된 도로기지국(RSU)과 연동하여 실시간 도로 환경 정보 수집하고 차량단말기(OBU) 및 교통 센터에 제공하는 Road Weather Information System을 개발하였다. RSU는 운전자 안전을 위해 노변 정보를 수집하고 이를 분석하여 서비스 우선순위에 따라 IP와 비콘 서비스를 OBU 및 상위 터미널에 제공한다. 상위 터미널에는 IP 기반 셋톱박스 응용 프로그램을 개발하여 교통 정보 및 도로 환경 정보, 환경 센서 오류 등에 정보를 제공한다. 결과적으로, RWIS는 노변 정보의 실시간 수집을 발전시켜 지능형 교통 시스템에 운전자 안전을 보완하고, 기술융합으로 다양한 서비스 방법을 제시하였다.

• Smart Structures and Systems
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• 제23권6호
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• pp.653-667
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• 2019

Using cross-ties to connect cables together when forming a cable network is regarded as an efficient method of mitigating cable vibrations. Cross-ties have been extended and fixed on bridge decks or towers in some engineering applications. However, the dynamics of this kind of system need to be further studied, and the effects of extending cross-links to bridge decks/towers on the modal response of the system should be assessed in detail. In this paper, a system of two cables connected by an inter-supported cross-link with another lower cross-link extended to the ground is proposed and analyzed. The characteristic equation of the system is derived, and some limiting solutions in closed form of the system are derived. Roots of cable system with special configurations are also discussed, attention being given to the case when the two cables are identical. A predictable mode behavior was found when the stiffness of inter-connection cross-link and the cross-link extended to the ground were the same. The vector of mode energy distribution and the degree of mode localization index are proposed so as to distinguish global and local modes. The change of mode behaviors is further discussed in the case when the two cables are not identical. Effects of cross-link stiffness, cross-link location, mass-tension ratio, cable length ratio and frequency ratio on $1^{st}$ mode frequency and mode shape are addressed.

• 한국ITS학회 논문지
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• 제21권1호
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• pp.1-16
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• 2022

최근 환경에 대한 관심이 커지면서 전동킥보드는 도시 내 친환경 교통수단으로써 주목받고 있다. 이에 따라 실질적 이용행태 및 이용목적에 대한 다양한 연구가 실시되고 있으나, 개인의 통행성향을 반영한 이용의향에 대한 연구는 미비한 실정이다. 따라서, 본 연구에서는 서울시 통근자를 대상으로 실시한 설문조사를 활용하여 요인분석을 통해 응답자의 통행성향을 분석하고, 공유 전동킥보드 이용의향에 대한 이항 로지스틱 회귀모형을 구축하여 개인의 통행행태가 어떻게 영향을 미치는지 규명하였다. 모형추정 결과, 공유 전동킥보드 이용의향에 영향을 미치는 요인으로, 연령, 주수단(승용차), 버스정류장 접근시간, 통행성향 변수(통행 비효용, 직접 운전, 인터넷/스마트폰 친화, 추가 지불 의사)가 통계적으로 유의한 것으로 분석되었다. 본 연구의 결과는 향후 공유 전동킥보드의 효율적인 운영과 이용 활성화를 위한 통행행태적 측면의 기초자료로 활용될 수 있을 것으로 기대된다.

• Korean Chemical Engineering Research
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• 제60권3호
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• pp.347-355
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• 2022

안전밸브(PSV)는 다양한 원인으로 발생하는 압력이 설정 압력에 도달하면 자동적으로 스프링이 작동하면서 분출되고 일정 압력 이하가 되면 정상상태로 복원되는 안전장치이다. 안전밸브는 압력상승 등 비정상 상태에서 정상 작동할 수 있도록 주기적인 검사와 모니터링 이행이 필수적이다. 그러나 현행 안전검사는 정해진 주기에만 수행되고 있어 정상작동 여부의 안전성을 확보하는 데 어려움이 있다. 따라서 안전관리에 필요한 안전밸브의 고장모드와 원인요소를 찾아 평가항목을 개발하였다. 그리고 항목의 우선순위를 도출하여 안전성 확보를 위한 의사결정 정보를 제공하고자 한다. 이를 위해 15명의 전문가를 대상으로 안전밸브(PSV)의 Failure Mode Cause Factor(FMCFs)와 관련하여 중요하다고 판단되는 평가요인을 도출하기 위해 3차례에 걸친 델파이(Delphi) 조사를 수행하였다. 그 결과 안전밸브의 6개 고장모드와 그 하위요인 22개의 평가요인을 선정하였다. 이와 같이 선정된 평가요인들의 우선순위를 분석하기 위해 계층구조를 도식화하였고 우선순위 계산에는 계층적 의사결정 방법(AHP)을 적용하였다. 분석결과 FMCFs의 고장모드 우선순위는 'Leakage'(0.226), 'Fail to open'(0.201), 'Fail to relieve req'd capacity'(0.152), 'Open above set pressure'(0.149), 'Spuriously open'(0.146), 'Stuck open'(0.127) 순으로 확인하였다. FMCFs의 하위 우선순위는 'PSV component rupture'(0.109), 'Fail to PSV size calculation'(0.068), 'PSV Spring aging'(0.065), 'Erratic opening'(0.059), 'Damage caused by improper installation and handling'(0.058), 'Fail to spring'(0.053) 등의순으로확인하였다. 우선순위가 결정된 FMCFs 효율적인 관리를 통해 안전밸브의 취약점을 파악하고 안전성을 향상하는데 기여할 수 있을 것으로 기대된다.

• 한국환경과학회지
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• 제16권2호
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• pp.179-185
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• 2007

Nitrous oxide ($N_2O$) is an important trace gas in the atmosphere not only because of its large global warming potential (GWP) but also because of the role in the ozone depletion in the stratosphere. It has been known that soil is the largest natural source of $N_2O$ in global emission. However, anthropogenic sources contributing from industrial section is likely to increase with rising the energy consumption, and transportation as well. In this study, a total of 32 gasoline-powered passenger vehicles (ranging from small to large engine's displacement and also ranging from aged catalyst to new catalyst) were tested on the chassis dynamometer system in order to elucidate the characteristics of $N_2O$ emission from automobiles under different driving modes. Ten different driving modes developed by NIER were adapted for the test. The results show that the $N_2O$ emission decreases logarithmically with increase of vehicle speed over the all test vehicles ($N_2O$) emission = -0.062 Ln (vehicle speed) + $0.289,\;r^2=0.97$). It revealed that the larger engine's displacement, the more $N_2O$ emission were recorded. The correlation between $N_2O$ emission and catalyst aging was examined. It found that the vehicles with aged catalyst (odometer record more than 8,0000km) emit more $N_2O$ than those with new catalyst. Average $N_2O$ emission was $0.086{\pm}0.095\;N_2O-g/km$ (number of samples=210) for the all test vehicles over the test driving modes.

• Journal of Photoscience
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• 제9권2호
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• pp.521-523
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• 2002

5-aminolevulinic acid (ALA) has been used to stimulate endogenous protoporphyrin IX (PpIX) in tumor and then initiate PDT. Recently, ALA-Hexyl ester (He-ALA) was found much effective than ALA on producing PpIX in cancer cells. To clarify the transportation mechanism of ALA and He-ALA, the detection of them is the important step. ALA and its derivatives all don't emit fluorescence, so the Raman spectroscopy was used here for the direct detection of ALA and He-ALA. The results showed that ALA and He-ALA have the common strong Raman peaks at 2930, 2950 CM$\^$-1/, due to the CH$_2$ vibration. The peak 3050 CM$\^$-1/ appeared in ALA spectrum can be attributed to OH vibration, while the peaks of 2860, 2900 CM$\^$-1/ in He-ALA spectrum were assigned as the modes of CH$_3$. This Raman spectral characteristic is consistence with the structure difference of He-ALA and ALA. Thus, Raman spectroscopy provides a new way to detect and distinguish ALA and He-ALA, and could be explored further in biology system.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.792-796
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• 2006

In recent years, the semiconductor industry and the optical industry is developed rapidly. The recent demand has expanded for optical components such as a optical lens, a optical semiconductor and a measuring instrument. Object transport systems are driven typically by the magnetic field and the conveyer belt. Recent industry requires more faster and efficient transport system. However, conventional transport systems are not adequate for transportation of optical elements and semiconductors. Because conveyor belts can damage precision optical elements by the contact force and magnetic systems can destroy the inner structure of semiconductor by the magnetic field. In this paper, the levitation transport system using ultrasonic wave is developed for transporting precision elements without damages. This transport system is using 2-mode ultrasonic wave excitation and flexural beam modes shapes are evaluated. It compared simulation results with experimental results

• International Journal of Concrete Structures and Materials
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• 제8권1호
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• pp.43-59
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• 2014

Many bridges are subject to lateral damage for their girders due to impact by over-height vehicles collision. In this study, the optimum configurations of carbon fiber reinforced polymers (CFRP) laminates were investigated to repair the laterally damaged prestressed concrete (PS) bridge girders. Experimental and analytical investigations were conducted to study the flexural behavior of 13 half-scale AASHTO type II PS girders under both static and fatigue loading. Lateral impact damage due to vehicle collision was simulated by sawing through the concrete of the bottom flange and slicing through one of the prestressing strands. The damaged concrete was repaired and CFRP systems (longitudinal soffit laminates and evenly spaced transverse U-wraps) were applied to restore the original flexural capacity and mitigate debonding of soffit CFRP longitudinal laminates. In addition to the static load tests for ten girders, three more girders were tested under fatigue loading cycles to investigate the behavior under simulated traffic conditions. Measurements of the applied load, the deflection at five different locations, strains along the cross-section height at mid-span, and multiple strains longitudinally along the bottom soffit were recorded. The study investigated and recommended the proper CFRP repair design in terms of the CFRP longitudinal layers and U-wrapping spacing to obtain flexural capacity improvement and desired failure modes for the repaired girders. Test results showed that with proper detailing, CFRP systems can be designed to restore the lost flexural capacity, sustain the fatigue load cycles, and maintain the desired failure mode.

• Smart Structures and Systems
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• 제14권4호
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• pp.659-678
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• 2014

The study is aimed at investigating the feasibility of a high TRL solution for a wing flap segment characterized by morphable camber airfoil and properly tailored to be implemented on a real-scale regional transportation aircraft. On the base of specific aerodynamic requirements in terms of target airfoil shapes and related external loads, the structural layout of the device was preliminarily defined. Advanced FE analyses were then carried out in order to properly size the load-carrying structure and the embedded actuation system. A full scale limited span prototype was finally manufactured and tested to: ${\bullet}$ demonstrate the morphing capability of the conceived structural layout; ${\bullet}$ demonstrate the capability of the morphing structure to withstand static loads representative of the limit aerodynamic pressures expected in service; ${\bullet}$ characterize the dynamic behavior of the morphing structure through the identification of the most significant normal modes. Obtained results showed high correlation levels with respect to numerical expectations thus proving the compliance of the device with the design requirements as well as the goodness of modeling approaches implemented during the design phase.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.331-332
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• 2006

Transport systems which are the important part of the factory automation have much influence on improving productivity. Object transport systems are driven typically by the magnetic field and conveyer belt. In recent years, as the transmission and processing of information is required more quickly, demands of optical elements and semiconductors increase. However, conventional transport systems are not adequate for transportation of those. The reason is that conveyor belts can damage precision optical elements by the contact force and magnetic systems can destroy the inner structure of semiconductor by the magnetic field. In this paper, the levitation transport system using ultrasonic wave is developed for transporting precision elements without damages. Vibration modes of each flexural beam are verified by using Laser Scanning Vibrometer.