PURPOSES : The purpose of this study is to investigate the tendency of material property estimation under different concrete distress conditions and curling conditions when non-destructive tests such as rebound hammer and surface deflection test are applied to concrete pavement. METHODS : Nondestructive tests using Schmidt hammer and Falling Weight Deflectometer were performed to inspect the expressway concrete pavements constructed more than 20 years ago. Some results were compared with core tested elastic modulus and compressive strength. RESULTS : As a result of the rebound test, the section with Alkali-Silica Reaction(ASR) distress was outside the range of the existing estimation formula, but the control section was found to be within the range of the existing estimation formula. As a result of the physical property estimation through deflection test, the section with ASR distress showed greater fluctuations in the estimated material properties and deflection ratio compared to the control section, showing that the ASR damage seems to affect the slab deflection behavior. CONCLUSIONS : The rebound test may not sufficiently reflect the decline in material properties due to concrete damage. The deflection test can obtain results that reflect the deterioration of material properties, but it was confirmed that significant variability may occur, so it seems to necessary to perform complementary indoor core tests with nondestructive testing(NDT) tests.

As the capacity of renewable power generation facilities rapidly increases, the variability of electric power system and gas turbine power generation is also increasing. Therefore, problems may occur that require urgent repair while the gas turbine rotor is stopped. When the gas turbine rotor turning is stopped and then restarted, if the turning period is not appropriate, severe vibration may occur due to rotor bending. As a result of the experiment, it was confirmed that normal operation is possible when the gap data measured at the start of rotor turning after maintenance work is similar to the existing value. And the vibration value at the start of rotor turning was lower as the rotor temperature was lower or the stop period was shorter.

Coupled thermo-hydraulic-mechanical (THM) processes are essential for the long-term performance of deep geological disposal of high-level radioactive waste. In this study, a numerical sensitivity analysis was performed to analyze the effect of rock properties on THM responses after the execution of the heater test at the Kamaishi mine in Japan. The TOUGHFLAC simulator was applied for the numerical simulation assuming a continuum model for coupled THM analysis. The rock properties included in the sensitivity study were the Young’s modulus, permeability, thermal conductivity, and thermal expansion coefficients of crystalline rock, rock salt, and clay. The responses, i.e., temperature, water content, displacement, and stress, were measured at monitoring points in the buffer and near-field rock mass during the simulations. The thermal conductivity had an overarching impact on THM responses. The influence of Young’s modulus was evident in the mechanical behavior, whereas that of permeability was noticed through the change in the temperature and water content. The difference in the THM responses of the three rock type models implies the importance of the appropriate characterization of rock mass properties with regard to the performance assessment of the deep geological disposal of high-level radioactive waste.

PURPOSES : The purpose of this study is to measure and analyze the fugitive dust generated by each process through field tests to develop a technology to reduce fugitive dust generated during excavation-restoration work on road pavements. METHODS : The testbed was constructed based on a typical excavation-restoration construction section and comprised five sections for reproducibility and repeated measurements. The excavation-restoration work was divided into pavement cutting, pavement crushing, pavement removal, excavation, and restoration processes and fugitive dust generated by each process was measured. Fugitive dust (TSP, PM10, PM2.5, and PM1) was measured using a GRIMM particle spectrometer, which applies the principle of a light scattering spectrometer and can be measured in real-time. RESULTS : Analyses of the average mass concentration of PM10 generated by the excavation-restoration process are as follows: 1286.3 μg/m³ from pavement cutting, 246.8 μg/m³ from pavement crushing, 697.0 μg/m³ from pavement removal, 747.9 μg/m³ from excavation process, and 350.6 μg/m³ from the restoration process. In addition, the average particle size distribution of the excavationrestoration construction was in the order of PM10~PM2.5 (67 %), PM1 or less (24 %), and PM2.5~PM1 (9 %). The pavement cutting process is characterized by the emission of high concentrations of fugitive dust over a short time, compared to other processes. The pavement crushing process has the characteristic of steadily generating fugitive dust for a long period, although the emission concentration is small. CONCLUSIONS : In this study, it was found that the concentration and characteristics of fugitive dust generated during road pavement excavation-restoration works vary by process and the reduction technology for each process should be developed accordingly.

고준위방사성폐기물의 심지층처분시스템을 이루는 요소인 공학적방벽이 처분환경에서 어떻게 변화할 것인가를 이해하기 위해 In-DEBS 시험이 계획되었고, In-DEBS 시험을 수행할 위치를 선정하기 위하여 심지층처분을 위한 지하연구시설인 KURT 부지 및 확장구간에 대한 지질 및 수리지질학적 자료가 조사, 분석되었다. KURT 부지 및 확장구간에서 조사된 자료를 이용하여 시험을 수행할 수 있다고 판단되는 연구 갤러리를 결정하였고, 연구 갤러리 내에서의 국지적인 특성을 파악하기 위하여 시추공 조사가 이루어졌다. 부지규모 자료의 분석 및 시추공 조사 자료를 이용하여 지하수 유동에 관한 수리지질학적 특징 및 지하수 유입량이 평가되었으며, In-DEBS 시험을 현장에서 준비하고 수행하기 위해 요구되는 조건을 함께 고려하여 In-DEBS 시험에 이용될 대구경 시추공의 위치를 선정하였다. 굴착된 대구경 시추공의 공벽을 조사하여 지하수 유입량을 평가하고 공벽 부근의 수리전도도 분포를 평가하였다. 본 연구를 통해 정리된 수리지질학적 자료는 In-DEBS 시험 현장에서 관측되고 있는 자료를 해석하여 공학적방벽의 변화 과정을 해석할 때에 기초 자료로 활용될 수 있을 것으로 기대된다.

점착트랩은 특정 광파장에 유인되는 곤충의 반응을 이용하여 비행 곤충의 유살 및 모니터링에 널리 이용되고 있다. 그러나 유색 점착트랩은 해당 색상에 반응을 보이는 모든 곤충을 유인하기 때문에 비표적곤충(Non target insect)이 부착되는 문제가 발생한다. 비표적곤충은 부착면을 차지하여 표적곤충의 유인을 방해하며, 해충밀도 모니터링에 필요한 노력과 시간 소요를 증대시킨다. 본 연구에서는 비표적 곤충과 이물질의 부착을 물리적으로 방지하기 위하여 내경 5mm, 10mm의 방지망을 설치하였을 때, 각 처리에 따른 유입 곤충의 종다양성 지수를 분석하여 방지망의 현장 적용 가능성을 검정하였다. 그 결과 망을 처리하지 않은 트랩과 5mm, 10mm 방지망을 설치한 트랩 간 종다양성 지수에서 유의한 차이를 보이지 않았다. 그러나 포획된 총 종의 수는 망을 처리하지 않은 트랩에서 높게 나타났는데 이는 대형 비표적 곤충의 포획수가 높은 것이 주 요인이었다. 표적 해충인 총채벌레, 가루이 등 미소해충의 유입 빈도 또한 무처리, 5mm, 10mm 간에 유의한 차이를 보이지 않아 방지망의 설치가 표적곤충인 미소해충의 유입에 악영향이 없으며, 5mm 망을 적용하여도 무방하다는 결과를 얻었다.

Airport concrete pavement slabs show contraction and expansion behavior due to environmental factors such as temperature and humidity. Among the various environmental factors, temperature is the most influential factor in the concrete slab. However, it is inadequate to consider air temperature or surface temperature as influential factors especially for airport concrete slabs with very large thicknesses. Therefore, this study intends to utilize the equivalent linear temperature difference calculated from the data of the thermometer embedded in 5 depths(50mm, 150mm, 250mm, 350mm, 450mm) on the airport concrete slab. Equivalent linear temperature difference is the temperature difference between the uppermost and lowermost part of the concrete slab, which shows the same behavior due to actual temperature. Since the upper part of the concrete slab is more affected by air temperature than the lower part, the daily temperature range is large. Therefore, the equivalent linear temperature difference increases during the day and decreases at night, and concrete slabs show curl-down during the day and curl-up at night. This daily variation of curling behavior causes a difference in HWD experimental results. The HWD(Heavy Weight Deflectometer) test is mainly performed to investigate the condition of the pavement. And the calculated values are deflection, ISM(Impact Stiffness Modulus), LTE(Load Transfer Efficiency). The equivalent linear temperature difference represents the behavior of the concrete slab by the environmental load, and the calculated values by the HWD test represent the behavior. Therefore, the purpose of this study is to investigate the behavior of concrete slab by combined load including environmental load and traffic load through correlation analysis between these values. This study was supported by Incheon International Airport Corporation(BEX00625) and Korea Airports Corporation.

Airport concrete slabs behave by combined loads including environmental loads and traffic loads. To analyze the behavior of concrete slabs by combined load, the dynamic strain gages were embedded at 2 depths(50mm, 450mm) and 3 locations(corner, Center and Mid-Edge). And the thermometers were embedded at 5 depths(50mm, 150mm, 250mm, 350mm, 450mm) in actual airport concrete slabs. HWD(Heavy Weight Deflectometer) is a device to measure the deflection by applying an impact load. The values calculated by the HWD test are deflection, ISM(Impact Stiffness Modulus), LTE(Load Transfer Efficiency). Concrete slabs tend to expand during the summer when the temperature is high, and contract during the winter when the temperature is low. In addition, the drying shrinkage occurs as age increases. Field HWD test were conducted in March, May, August, and November to examine seasonal and age-specific changes. Furthermore, the temperature difference between top and bottom of concrete slabs causes the curl-up and curl-down behavior. The test was conducted 3 times at 12o`clock, 16o`clock, 21o`clock, 3o`clock, 7o`clock to examine temporal changes. The strain of the slab at HWD strike was measured 500 times per second because the strain occurred instantaneously, and the temperature was measure 1 times per 10 minutes. The calculated values and the measured values varied according to environmental loads. In order to examine these values in various angles, the equivalent linear temperature difference obtained by converting the temperature by depth into the uppermost lowermost temperature difference, the temperature of the slab which changes seasonally as a whole, and the drying shrinkage which occurs as the age increases are considered. Therefore, the purpose of this study is to clarify the behavior of concrete slabs by combined load considering long - term drying shrinkage, annual variation of temperature, and daily variations. This study was supported by Incheon International Airport Corporation(BEX00625) and Korea Airports Corporation.