• 한국환경복원기술학회지
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• 제21권4호
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• pp.75-86
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• 2018

This research was thereby made to study and analysis ecological, landscape, and stability qualities of roadside cut Slopes in expressways and national highways that went through revegetation works. Also, evaluation items and framework for integrated assessment of plant structure and restored state for the maintenance were suggested. Following is the summary of the result. firstly, for stabilization of introduced native plant species on roadside cut slops, assessment on the post-project environmental management through long-term monitoring and maintenance works must be made. It signifies a form of authentic recovery and restoration by the native plants. second, current evaluation framework on the test beds is well managed with clear evaluation standards and table while its method of assessing the post management with only test bed results lacks conformity with this study site. Newly developed evaluation framework on the post construction sites is estimated to be used as assessment standards on any roadside construction sites. Third, after site investigation distinction was observed among different revegetating construction types in the long-term perspective. Due to the different duration time of vegetation state between seed-spray measures(degraded in time) and layer-spray measure(maintained), the use of coarse straw-mat mulching work or Coir net was suggested in long term maintenance of cut slopes. forth, segmentation of post environmental assessment is organized into three large categories of "ecological", "stabile", and "landscape" qualities regarding post restoration quality and stability of slope through native plants with which categories marks 50, 30, 20 points of rates. fifth, components of the post environmental assessment were segmented in twelve categories driving results from former experimental construction and newly focused items on site. In the future, it is possible to propose a customized assessment method considering the location and location of construction work if the research on the application of post-environment assessment methods for road construction surface recording is conducted systematically.

• 한국도로학회논문집
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• 제17권5호
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• pp.33-38
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• 2015

PURPOSES : The purpose of this paper is to investigate the application of thermoelectric technology to concrete structures for harvesting solar energy that would otherwise be wasted. In various fields of research, thermoelectric technology using a thermoelectric module is being investigated for utilizing solar energy. METHODS: In our experiment, a halogen lamp was used to produce heat energy instead of the solar heat. A data logger was used to record the generated voltage over time from the thermoelectric module mounted on a concrete specimen. In order to increase the efficiency of energy harvesting, various factors such as color, architecture, and the ability to prevent heat absorption by the concrete surface were investigated for the placement of the thermoelectric module. RESULTS : The thermoelectric module produced a voltage using the temperature difference between the lower and upper sides of the module. When the concrete specimen was coated with an aluminum foil, a high electric power was measured. In addition, for the power generated at low temperatures, it was confirmed that the voltage was generated steadily. CONCLUSIONS: Thermoelectric technology for energy harvesting can be applied to concrete structures for generating electric power. The generated electricity can be used to power sensors used in structure monitoring in the future.

• Smart Structures and Systems
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• 제15권3호
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• pp.769-785
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• 2015

Although timber structures have been extensively used in underground temporary supporting system, their actual performance is poorly understood, resulting in potentially conservative and over-engineered design. In this paper, a novel wireless sensor technology, SmartPlank, is introduced to monitor the field performance of timber structures during underground construction. It consists of a wooden beam equipped with a streamlined wireless sensor node, two thin foil strain gauges and two temperature sensors, which enables to measure the strain and temperature at two sides of the beam, and to transmit this information in real-time over an IPv6 (6LowPan) multi-hop wireless mesh network and Internet. Four SmartPlanks were deployed at the London Underground's Tottenham Court Road (TCR) station redevelopment site during the Stair 14 excavation, together with seven relay nodes and a gateway. The monitoring started from August 2013, and will last for one and a half years until the Central Line possession in 2015. This paper reports both the short-term and long-term performances of the monitored timber structures. The grouting effect on the short-term performance of timber structures is highlighted; the grout injection process creates a large downward pressure on the top surface of the SmartPlank. The short and long term earth pressures applied to the monitored structures are estimated from the measured strains, and the estimated values are compared to the design loads.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.1-8
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• 2021

본 연구에서는 도로 포장 유지관리에 필요한 핵심정보를 생산해 낼 수 있는 저비용·고효율 포장상태 모니터링 기술을 개발하고자 하였다. 특히 시각정보와 고가 센서에 의존하는 기존 장비의 단점을 보완하기 위해 소음과 인공지능 기반의 포장상태등급 평가시스템을 고안하였다. 시스템 개발을 위한 아이디어 정립부터 기능 정의, 정보흐름 및 아키텍쳐 설계 과정을 거쳤으며, 생산된 프로토타입에 대한 성능 검증과 활용 전주기에 대한 실증 평가를 수행하였다. 그 결과, 높은 수준의 인공지능 평가 신뢰도가 확보되었으며, 하드웨어와 소프트웨어적 요소 외에도 시스템 활용에 관한 짜임새 있는 가이드라인이 개발되었다. 또한 현장평가 과정을 통해 비전문가도 쉽고 빠른 조사와 분석이 가능하고, 직관적인 시각적 정보 제공을 통해 관리자의 업무 지원이 가능함도 확인하였다. 반면에 학습에 고려되지 않은 외부 조건에 대한 선행 판별 기술, 시스템 간소화, 가변 주행속도 대응 기술 등 기술의 완성도 제고도 필요함을 알 수 있었다. 본 연구를 시작으로 1960년대 이후 반세기 이상 지속되어온 포장상태 모니터링 기술의 새로운 패러다임이 제시되길 기대한다.

• 한국도로학회논문집
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• 제17권6호
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• pp.1-9
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• 2015

PURPOSES : The objective of this study is to propose a quality control and quality assurance method for use during asphalt pavement construction using non-destructive methods, such as ground penetrating radar (GPR) and an infrared (IR) camera. METHODS : A 1.0 GHz air-coupled GPR system was used to measure the thickness and in situ density of asphalt concrete overlay during the placement and compaction of the asphalt layer in two test construction sections. The in situ density of the asphalt layer was estimated based on the dielectric constant of the asphalt concrete, which was measured as the ratio of the amplitude of the surface reflection of the asphalt mat to that of a metal plate. In addition, an IR camera was used to monitor the surface temperature of the asphalt mat to ensure its uniformity, for both conventional asphalt concrete and fiber-reinforced asphalt (FRA) concrete. RESULTS : From the GPR test, the measured in situ air void of the asphalt concrete overlay gradually decreased from 12.6% at placement to 8.1% after five roller passes for conventional asphalt concrete, and from 10.7% to 5.9% for the FRA concrete. The thickness of the asphalt concrete overlay was reduced from 7.0 cm to 6.0 cm for the conventional material, and from 9.2 cm to 6.4 cm for the FRA concrete. From the IR camera measurements, the temperature differences in the asphalt mat ranged from $10^{\circ}C$ to $30^{\circ}C$ in the two test sections. CONCLUSIONS : During asphalt concrete construction, GPR and IR tests can be applicable for monitoring the changes in in situ density, thickness, and temperature differences of the overlay, which are the most important factors for quality control. For easier and more reliable quality control of asphalt overlay construction, it is better to use the thickness measurement from the GPR.

• 대한토목학회논문집
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• 제32권6C호
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• pp.239-247
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• 2012

연직배수재가 설치된 연약지반 상에 도로성토를 실시할 경우 연약지반에 측방유동이 발생될 지 여부를 예측할 수 있는 방법이 제안되었다. 이 측방유동예측법을 조사하기위해 연직배수공법을 적용하여 지반개량공사가 실시된 연약지반 상에 도로성토가 시공된 우리나라 서해안과 남해안 지역 연약지반에서 계측관리가 실시된 13개 현장 200개 측점의 현장계측자료를 수집 분석하였다. 수평배수재를 설치한 연약지반에서 수평변위와 사면안전율과의 관계를 조사할 경우는 연약지반의 지표면수평변위량 보다는 지중최대수평변위량을 적용하는 것이 바람직하였다. 성토사면의 사면안전율이 1.4 이상이면 대부분의 연약지반 최대수평변위는 50mm 이하로 발생되었고 사면안전율이 1.2 이하이면 대부분의 최대수평변위는 100mm 이상으로 발생되었다. 최대수평변위량이 50mm 이하로 발생하면 전단변형이 발생하지 않았으므로 측방유동이 발생할 우려가 없는 안전한 현장으로 판단된다. 반면에 최대수평변위량이 100mm 이상으로 크게 발생하는 현장에서는 전단파괴가 발생할 가능성이 있다고 판단된다. 이런 현장에서는 즉각 대책을 강구한 후 성토를 계속함이 바람직하다고 판단된다. 또한 연직배수재를 설치한 연약지반에서 안정수가 3.0이하이고 지지안전율이 1.7 이상이면 안전한 성토시공이 가능하며 안정수가 4.3 이상이고 지지안전율이 1.2 이하이면 연약지반에 전단변형의 발생은 물론이고 전단파괴의 가능성까지도 예상된다.

• 한국도로학회논문집
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• 제3권1호
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• pp.165-176
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• 2001

줄눈콘크리트포장의 줄눈은 온도 및 습도변화에 기인하여 발생하는 슬래브내에 무작위하게 발생하는 균열을 제어할 목적으로 설계된다. 이러한 인위적인 균열 (줄눈)은 자연발생적인 균열에 비하여 줄눈채움, 하중전달장치등의 보호대책을 강구하는 것이 용이하다는 장점을 가지고 있다. 줄눈채움의 잠재적인 이점은 표면수의 하부층으로의 침투로 인한 하부층의 약화 및 비압축성 물질 (작은 입자위 골재)의 줄눈내에 끼어듦으로 인한 스폴링을 방지하는데 있다. 합리적인 줄눈 채움의 설계를 위해서는 줄눈폭의 변화 (줄눈의 수평 움직임)의 산정이 중요한 입력요소이다. LTPP SMP 연구에 포함된 16개의 줄눈콘크리트포장의 줄눈의 수평움직임에 대한 장기 현장계측자료를 토대로 상당수의 줄눈에서 수평움직임을 허용하지 않고 있다는 것이 밝혀진바 있다. 이러한 현상을 줄눈잠김이라고 한다. 줄눈잠김이 발생하는 원인은 설계상에 계획된 줄눈부의 균열이 발생하지 않기 때문이라고 추정된다. 본 연구에서는 임의의 줄눈콘크리트포장에서 줄눈잠김의 비율을 예측할 수 있는 모델을 제시하였고 줄눈 잠김이 포장체의 성능에 미치는 영향을 조사하였다.

• 한국융합학회논문지
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• 제13권5호
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• pp.1-8
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• 2022

국내에서는 4차 산업혁명의 핵심기술인 드론 등을 이용하여 사회기반시설(SOC)를 디지털화하는 한국판뉴딜 정책을 추진 중에 있고, 국외에서도 열화상카메라 등 융복합센서를 드론에 탑재하여 다양한 산업 분야에서 활용하는 사례가 증가하고 있다. 본 연구에서는 고속도로 교면포장 공사에서 포장 품질을 개선하기 위하여 드론에 열화상 카메라를 탑재하여 포장 작업 구간에 대한 온도 측정 및 검증을 수행하였다. 기존의 방식인 레이저 온도계를 활용한다면 포장 온도를 부분적으로만 측정이 가능하지만, 제안된 방식을 활용하면 포장 작업 구간 전체에 대한 실시간 온도 모니터링 뿐 아니라 온도 분포 확인을 통한 균일성 검증이 가능한 것을 확인하였다. 제안된 방식을 현장에 적용한다면 도로 개방 시기(포장 표면온도≦40℃)에 대한 오판의 가능성을 낮춰줌에 따라 고속도로 포장 품질관리 제고 및 신속한 교통 개방 시기 결정이 가능할 것으로 기대된다.

• 대한원격탐사학회지
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• 제40권1호
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• pp.1-8
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• 2024

Busan is the 6th largest port city in the world, where nitrogen dioxide (NO₂) emissions from transportation and port industries are significant. This study aims to assess the NO₂ products of the Geostationary Environment Monitoring Spectrometer (GEMS) over Busan using ground-based instruments (i.e., surface in-situ network and Pandora). The GEMS vertical column densities of NO₂ showed reasonable consistency in the spatiotemporal variations, comparable to the previous studies. The GEMS data showed a consistent seasonal trend of NO₂ with the Korea Ministry of Environment network and Pandora in 2022, which is higher in winter and lower in summer. These agreements prove the capability of the GEMS data to monitor the air quality in Busan. The correlation coefficient and the mean bias error between the GEMS and Pandora NO₂ over Busan in 2022 were 0.53 and 0.023 DU, respectively. The GEMS NO₂ data were also positively correlated with the ground-based in-situ network with a correlation coefficient of 0.42. However, due to the significant spatiotemporal variabilities of the NO₂, the GEMS footprint size can hardly resolve small-scale variabilities such as the emissions from the road and point sources. In addition, relative biases of the GEMS NO₂ retrievals to the Pandora data showed seasonal variabilities, which is attributable to the air mass factor estimation of the GEMS. Further studies with more measurement locations for longer periods of data can better contribute to assessing the GEMS NO₂ data. Reliable GEMS data can further help us understand the Asian air quality with the diurnal variabilities.

• Smart Structures and Systems
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• 제33권2호
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• pp.145-163
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• 2024

The evaluation of dynamic characteristics of bridges under operational traffic loads is a crucial aspect of bridge structural health monitoring. In the vehicle-bridge interaction (VBI) system, the vibration responses of bridge exhibit time-varying characteristics. To address this issue, an accurate time-frequency analysis method that combines the autoregressive power spectrum based empirical wavelet transform (AR-EWT) and local maximum synchrosqueezing transform (LMSST) is proposed to identify the time-varying instantaneous frequencies (IFs) of the bridge in the VBI system. The AR-EWT method decomposes the vibration response of the bridge into mono-component signals. Then, LMSST is employed to identify the IFs of each mono-component signal. The AR-EWT combined with the LMSST method (AR-EWT+LMSST) can resolve the problem that LMSST cannot effectively identify the multi-component signals with weak amplitude components. The proposed AR-EWT+LMSST method is compared with some advanced time-frequency analysis techniques such as synchrosqueezing transform (SST), synchroextracting transform (SET), and LMSST. The results demonstrate that the proposed AR-EWT+LMSST method can improve the accuracy of identified IFs. The effectiveness and applicability of the proposed method are validated through a multi-component signal, a VBI numerical model with a four-degree-of-freedom half-car, and a VBI model experiment. The effect of vehicle characteristics, vehicle speed, and road surface roughness on the identified IFs of bridge are investigated.