경험식에 기반한 폭발 해석방법은 폭압-시간 이력곡선을 하중으로 적용하여 해석하는 방법이다. 이 방법은 모델링이 간단하고 해 석시간이 짧아 효율적이지만, 일부 연구에 따르면 근거리 폭발 해석에는 적합하지 않음이 보고되고 있다. 본 연구에서는 예로써 환산 거리 0.4~1.0의 근거리 폭발조건에 있는 RC 보에 대해 해석방법에 따른 결과의 차이 및 원인을 분석하였고, 이를 통해 경험식 방법을 이용한 해석의 적용 범위를 구체적으로 검토 및 확인할 수 있었다. 사용된 유한요소해석 프로그램은 LS-DYNA이다. 해석결과에 따르 면, 원거리 폭발 실험 데이터를 근거로 하는 경험식 해석방법은 충격량을 과소평가하고 있었다. 이로 인해 RC 보의 처짐은 측정된 처 짐 또는 ALE(Arbitrary Lagrangian Eulerian) 해석결과에 비해 작게 계산되었다. 구조체의 응답이 크게 나타나는 근거리 폭발에 대해 서는 ALE 해석방법을 사용하는 것이 더 적합할 것으로 사료된다.

PURPOSES : The objective of this study is to present a practical application method for measuring the setting time of concrete in the field, considering different concrete blending and curing environments. METHODS : In the experimental environment of the concrete setting experiment, a mold was made in the laboratory, and the curing temperature was performed at laboratory room temperature (20-25 ℃), heater (30 ℃), and dryer (40 ℃). In the field, the experimental method was performed in summer and autumn, setting experiments on penetration resistance, ultrasonic pulse velocity, and semi-calorimeter. RESULTS : The result of the concrete setting time experiment was that the early setting time was achieved in the combination of filash and slag when the concrete was mixed, and the setting time in the curing environment was the same as the early setting time in the field. The setting time measurement method shows the correlation of the high crystal coefficient at UPV with 0.99 based on PR and the good ratio of 92 % to 107 % on average. In addition, the semi-calorimeter shows a good crystal coefficient of 0.96 to 0.99 and a good setting time of 88 % to 101 % on average. CONCLUSIONS : The analysis of the setting time of the concrete shows that the curing temperature is more affected than the mixture, and it is considered that the UPV test, which evaluates the reliability of the degree of purification, is easy to sampie among the three methods.

In the event of an contingency situation of physical protection in nuclear facilities, the first organization to deal with at the forefront is the Special Response Forces (SRF). Since the SRF has to perform nuclear facility protection at the actual battle site, they must repeatedly train tactical understanding such as shooting, entry, and suppression so that their body can remember it even in real contingency situations (called Muscle Memory). In reality, however, repeated training using firearms is very difficult due to high risk and high cost, except for some military and police organizations. Using the advantages of VR technology, the Korea Institute of Nuclear nonproliferation and control (KINAC) has developed educational contents of “VR Shooting Training Center (VR STC)” to enable low-risk, low-cost, and repeated shooting training for these high-risk, high-cost training. This content was developed by dividing it into an “indoor” and “outdoor” training field. Educational firearms are all developed as gas guns to add to the sense of reality, and trainees can choose firearms, distance movement of targets and other options. The “Indoor training field” was developed by imitating an actual indoor shooting field, in particular the “outdoor training field” was developed using VR technology and motion tracking technology. Therefore, in “outdoor training field”, trainees can move freely within the designated spot of not only in VR content but also reality and then have to perform some missions. Trainees have to overcome random obstacles as they move to a designated destination, and at the destination, they are attacked by terrorists. Therefore, trainees must complete missions by concealing their bodies using objects around them. The one training course includes a total of 10 missions, and after the training is completed, comprehensive training results such as shooting accuracy and mission completion are expressed. VR STC will be a representative example of making high-risk, high-cost training into low-risk, low-cost, and repeated training. In this respect, VR technology can be used to develop various radiation protection curriculums accompanied by high risk and high cost, and can improve educational effects.

Recently, virtual reality (VR) and augmented reality (AR) technologies are attracting attention as core technologies in the era of the 4th industrial revolution. These virtual and augmented reality technologies are being used in a variety of industries, including the construction industry, healthcare industry, and manufacturing industry, to innovate in communication and collaboration, education and simulation, customer service and reinvention of the customer experience. In this paper, VR-based experiential safety education was conducted for workers of shipbuilding companies in Ulsan city, and for them, the educational effectiveness such as immersion, site applicability, safety accident prevention, education satisfaction, overall performance, and safety behavior in VR-based safety experience education were measured. In addition, we examined whether the immersion of VR-based safety experience education affects site applicability, safety accident prevention, educational satisfaction, overall performance, and safety behavior. Furthermore, it was analyzed whether site applicability plays a mediating role in the relationship between immersion and safety accident prevention. As a result, it was found that the immersion of VR-based safety experience education affects site applicability, safety accident prevention effect, education satisfaction, overall performance, and safety behavior, and that site applicability mediates between immersion and safety accident prevention. Based on these results, we suggests a direction for the development of VR-based contents in the field of safety and health and the transformation of safety and health education in the future.

PURPOSES : This study primarily aims to develop and evaluate a Smart Station - a novel underground pipeline measure system - to overcome the challenges of conventional surveying methods. METHODS : This study built two prototypes of the Smart Station. By reflecting issues revealed through the field tests of the first prototype, this study produced the second Smart Station prototype. The organization of the hardware units in the second prototype was reconfigured to maximize its usability for operators in the field. Furthermore, by developing the ‘Digital Twin X’, an integrated Smart Station management software suite, the second prototype was capable of 1) producing a digital workbook for field operators, 2) managing underground pipeline information, and 3) displaying 3-dimensional maps in and around an underground pipeline. The applicability of the second prototype was examined through three field tests conducted in one open space location, where no urban valley effects were expected, and two locations in a downtown area, with urban valley effects. Given the actual field installation of underground pipelines, this study collected data via both conventional surveying methods and the Smart Station to evaluate the performance of the Smart Station. Analyzing the field data, this study examined the data collection time and position accuracy of an underground pipeline measured by the Smart Station. RESULTS : The field test results revealed that both the conventional surveying method and the Smart Station produced similar performances in data collection time and measurement accuracy in the open space test location. However, in the case of downtown locations affected by urban valley effects, the Smart Station achieved 100 % measurement accuracy while the conventional surveying method achieved 93 % accuracy. It was also observed during the field test that no data were collected due to the constraints of the work schedule and various field conditions (e.g., weather and/or traffic congestion). The data collection times at the open space locations were 10 s for both the conventional surveying method and the Smart Station. However, the data collection times at the downtown locations appeared to be 10 s and 360 s by the Smart Station and the conventional surveying methods, respectively, thereby proving that the Smart Station outperforms the conventional method in its measurement efficiency. CONCLUSIONS : It is envisioned that the Smart Station produces higher work efficiency for field operators as it enables them to collect high accuracy data in a timely and quick manner and not only build a database for the collected data but also vividly visualize it in the field. In the future, it is necessary to conduct additional field tests under various conditions for the in-depth investigation of a Smart Station. In addition, it is expected that the Smart Station will be enhanced by coupling augmented reality (AR) technologies.

In this study, actual odor conditions were investigated in restaurants, livestock facilities, and major odor discharge facilities around daily life, and an odor modeling program was performed to find ways to improve odors in odor discharge facilities. The odor modeling results of restaurants around daily life showed that the complex odor concentration of large restaurants, which are close to residential areas, is higher than the acceptable complex odor standard at the receiving point. It was judged that a plan to increase the height of the restaurant odor outlets and a plan to reduce the amount of odor discharge was necessary. As a result of modeling the life odor of livestock housing facilities, when the distance from the housing facility is far away, the actual emission concentration is much lower than the acceptable emission concentration at the receiving point. It was judged that such facilities need to be reviewed for ways to reduce the emission of odorous substances, such as sealing the livestock housing facilities or improving the livestock environment. The main odor emission business sites that show complex odor concentration as 1,000 times or greater than the outlet odor emission standard were businesses associated with surfactant preparation, compounded feed manufacturing, textile dyeing processing, and waste disposal. Due to the separation distance and high exhaust gas flow rate, it was found that odor reduction measures are necessary. In this study, it was possible to present the allowable odor emission concentration at the discharge facilities such as restaurants, livestock houses, and industrial emission facilities by performing the process of verifying the discharge concentration of the actual discharge facility and the result of living odor modeling. It is believed that suitable odor management and prevention facilities can be operated.

PURPOSES : The objective of this study was to evaluate the field applicability of chip seals using recycled aggregates by comparing performance between natural aggregates and recycled aggregates for chip seals. METHODS : In order to check the performance of chip seals using recycled and natural aggregates, Bitumen Bond Strength (BBS) test, Vialit and bleeding tests were carried out. Cationic emulsions (RS(C)-2 and latex modified RS(C)-2L) were used in the tests. Granite aggregates were used as the natural aggregate and recycled aggregate from road wastes were used as the recycled aggregate. The aggregate was used with uniform gradation between 10 mm and 4.75 mm to clearly compare the performance difference between natural and recycled aggregates. RESULTS : Test results showed that the aggregate retention was low for both natural and recycled aggregates when applying RS(C)-2 (unmodified emulsion), but there was almost no difference between them when applying RS(C)-2L and RS(C)-2L-1 (modified emulsion) in the Vialit test results. In the bleeding tests, there was no bleeding for both natural and recycled aggregates when applying RS(C)-2 and RS(C)-2L. CONCLUSIONS: It was possible to apply chip seals using recycled aggregates in the field because the chip seals with recycled aggregates and RS(C)-2L (modified emulsion) showed aggregate retention similar to that of natural aggregates, and there was no bleeding.

Development of high-performance eco-friendly cold asphalt and its manufacturing system

본 연구의 목적은 고준위폐기물 처분기술 개발과 관련하여 현장실증 연구를 위해 사용될 공학규모 이상의 균질 완충재 블록 을 제작하기 위한 새로운 방법론을 제시하는 것이다. 이와 관련하여 플롯팅 다이(floating die) 방식의 프레스 재하 및 냉간 등방압프레스(CIP; Cold Isostatic Press) 기법을 국내 최초로 완충재 제작에 적용하였다. 또한 소요 밀도기준을 충족하는 완충재 블록을 생산하기 위한 최적의 제작조건(프레스 및 CIP의 소요 압력)과 현장 적용성을 분석하였다. 상기 기법의 적용을 통해 완충재 블록 내 밀도분포 편차가 현저히 감소하였으며, 이와 동시에 평균 건조밀도가 소폭 상승하고 약 5%의 크기가 감소하였다. 또한 CIP 적용을 통해 응력이완(stress release) 현상이 감소하고, 이로 인해 시간 경과에 따른 표면균열 발생이 현저히 저감됨을 시험제작을 통해 확인하였다. 본 연구에서 제시된 방법론은 공학규모 이상의 균질한 완충재 블럭을 성형할 수 있으며, 또한 이는 선진핵주기 고준위폐기물처분시스템(AKRS; Advanced Korea Reference Disposal System of HLW)의 완충재 소요 밀도기준을 충족하는 것으로 분석되었다.

Greenhouse gas emission from agricultural land is recognized as an important factor influencing climatic change. In this study, the national CO2 emission was estimated for paddy soils, using soil GHG emission model (DNDC) with 1 km2 scale. To evaluate the applicability of the model in Korea, verification was carried out based on field measurement data using a closed chamber. The total national CO2 emission in 2015 was estimated at 5,314 kt CO2-eq, with the emission per unit area ranging from 2.2~10.0 t CO2-eq ha-1. Geographically, the emission of Jeju province was particularly high, and the emission from the southern region was generally high. The result of the model verification analysis with the field data collected in this study (n=16) indicates that the relation between the field measurement and the model prediction was statistically similar (RMSE=22.2, ME=0.28, and r2=0.53). More field measurements under various climate conditions, and subsequent model verification with extended data sets, are further required.

Recently, advanced metering infrastructure (AMI) has been recognized as a core technology of smart water grid, and the relevant market is growing constantly. In this study, we developed all-in-one smart water meter of the AMI system, which was installed on the test-bed to verify both effectiveness and field applicability in office building water usage. Developed 15 mm-diameter smart water meter is a magneto-resistive digital meter, and measures flow rate and water quality parameters (temperature, conductivity) simultaneously. As a result of the water usage analysis by installing six smart water meters on various purposes in office building water usage, the water usage in shower room showed the highest values as the 1,870 L/day and 26.6 liter per capita day (LPCD). But, the water usage in laboratory was irregular, depending on the many variables. From the analysis of the water usage based on day of the week, the water usage on Monday showed the highest value, and tended to decrease toward the weekend. According to the PCA results and multivariate statistical approaches, the shower room (Group 3) and 2 floor man’s restroom sink (Group 1-3) have been classified as a separate group, and the others did not show a significant difference in both water use and water quality aspects. From the analysis of water usage measured in this study, the leak or water quality accident did not occur. Consequently, all-in-one smart water meter developed in this study can measure flow rate and water quality parameters (temperature, conductivity) simultaneously with effective field applicability in office building water usage.

Membrane bioreactors (MBRs) employ a process of biological treatment that is based on a membrane that has the advantages of producing high-quality treated water and possessing a compact footprint. However, despite these advantages, the occurrence of “fouling” during the operation of these reactors causes the difficulty of maintenance.Hence, in this study, three physical cleaning methods, namely, backwashing, air scrubbing, and mechanical cleaning ball was performed to identify optimum operating conditions through laboratory scale experiments, and apply them in a pilot plant. Further, the existing MBR process was compared with these methods, and the field applicability of a combination of these physical cleaning methods was investigated.Consequently, MCB, direct control of cake fouling on the membrane surface was found to be the most effective. Moreover, as a result of operating with combination of the physical cleaning process in a pilot plant, the TMP increasing rate was found to be – 0.00007 MPa/day, which was 185% higher than that obtained using the existing MBR process. Therefore, assuming fouling only by cake filtration, about one year of operation without chemical cleaning is considered to be feasible through the optimization of the physical cleaning methods.

최근 무인 항공기(UAV: Unmanned Aircraft Vehicle)의 활용범위가 넓어짐에 따라 다양한 형태의 무인 비행체 센서 가 개발되고 있으며 이를 활용한 국내·외 연구가 활발히 진행되고 있다. 본 연구에서는 UAV를 이용하여 촬영한 디 지털 영상의 공간해상도 및 정확도를 분석하여 식생조사에 서 무인항공사진촬영 시스템의 적용 가능성을 검토하였다. 사용된 기체는 미국 DJI사에서 제작된 S1000 기종을 이용 하였으며 고해상도 영상 촬영을 위해 RGB Camera(SONY, NEX-7)와 UAV 용 다중분광센서(Tetracam, Mini-MCA6) 를 활용하였다. 대상지는 하천생태계 교란 유해 식물인 가 시박(Sicyos angulatus)이 분포하고 있는 지역(안동시, 송내 천)을 선정하여 비행고도 150m에서 하천을 따라 500m 구 간을 촬영하였다. 촬영결과 공간해상도 3cm급 정사영상을 취득할 수 있었으며 촬영된 영상은 가시박의 개체 수준까지 파악 할 수 있었다. 이는 생태계 교란 식물의 관리 전후의 분포변화를 파악하여 관리 유형별 효과를 평가하는데 이용 가능 할 것으로 판단된다. 한편 다중분광센서를 통한 수종 분류의 가능성 여부를 알아보기 위하여 비교적 다양한 임분 을 형성하고 있는 인공식생지(국립생태원, 50m×50m)를 선 정하여 촬영하였다. 연구에 사용된 다중분광센서는 주요 파 장대별로 총 6개의(490FS10-25, 550FS10-25, 680FS10-25, 720FS10-25, 800FS10-25, 900FS20-25) 영상취득이 가능 하며 촬영된 다중분광 영상의 DN값으로 무감독 분류를 실 시하였다. 분석결과 침엽수종과 활엽수종에 대하여 80%의 분류정확도를 얻을 수 있었으며 향 후 다양한 파장대별 영 상 취득 및 분류기법을 적용하여 분류정확도를 향상 시킬 수 있을 것으로 판단된다. 무인항공촬영 시스템을 식생현황 파악에 적용한 결과, 신 속하고 정밀한 자료취득이 가능하며 특히 차량진입이 힘들 거나 육안조사가 어려운 지역의 식생조사, 특정 식생에 대 한 모니터링에 활용 가능할 것으로 판단된다.

PURPOSES: The purpose of this study was to break away from the workforce method using cold-mix asphalt mixtures and has a constant quality and has develop repair materials of pre-production asphalt-precast types. METHODS: The selection of the repair material was determined as the results obtained through physical properties of materials and the field applicability. In case of repair materials, values obtained through Marshall stability test & the dynamic stability test & retained stability test as well as the site conditions was considered. In case of adhesive, test results were obtained through examination of the bond strength(tensile, shear) and the field applicability of the adhesive was examined through combined specimens to simulate field applications. RESULTS : According to the results of laboratory tests, in the case of repair materials, Marshall stability and dynamic stability, retained stability of cold-mix reaction type asphalt mixture is the highest. In the case of adhesive, two-component epoxy-urea has a very high bonding strength(tensile, shear) was most excellent. According to the results of field tests, when epoxy-urea was excellent workability. Also, the repair body through actual mock-up test did not occur large deformation and fracture after 12 months. CONCLUSIONS : A suitable repair material is cold-mix reaction type mixture of asphalt-precast, a suitable adhesive is a two-component epoxy-urea.

PURPOSES : Surface treatment material for pavement preventive maintenance should be inspected field applicability. This study(Part Ⅱ) aimed to checkup coating characteristics and performance analysis using lab and field tests. The hydrophobic - low viscosity filling material for pavement preventive maintenance is presented in Part Ⅰ, which is a series of companion study. METHODS: Relative comparison between general asphalt mixtures and surface treatment asphalt mixtures are analyzed and measured for the field application such as indirect tensile strength ratio(TSR), abrasion resistance, crack propagation resistance, temperature resistance, coating thickness, permeability resistance and skid resistance in terms of british pendulum number(BPN). RESULTS: It is found that TSR, crack propagation resistance and permeability resistance is increased as against uncoated asphalt specimen. Abrasion resistance and temperature resistance is secured from the initial coating thickness point of view, which is about 0.2~0.3mm. Skid resistance on the surface treatment pavement is satisfied with the BPN criteria of national highway because of exposed aggregate and crack sill induced pavement deterioration and damage cracks. CONCLUSIONS : The hydrophobic - low viscosity surface treatment material for pavement preventive maintenance is validated on field applicability evaluation based on quantitative analysis of coating thickness and performance analysis using lab and field tests.

PURPOSES : This study aims to investigate the snow-melt effects of an underground electric heater's snow-melt system via a field performance test, for evaluating the suitability of the system for use on a concrete pavement. The study also investigates the effectiveness of dynamic measures for clearing snow after snowfall events. METHODS : In order to check the field applicability, in November 2010, specimens were prepared from materials used for constructing concrete pavements, and underground electric heating meshes (HOT-mesh) were buried at depths of 50 mm and 100 mm at the site of the Incheon International Airport Construction Research Institute. Further, an automatic heating control system, including a motion sensor and pavement-temperature-controlled sensor, were installed at the site; the former sensor was intended for determining snow-melt effects of the heating control system for different snowfall intensities. Pavement snow-melt effects on snowy days from December 2010 to January 2011 were examined by managing the electric heating meshes and the heating control system. In addition, data on pavement temperature changes resulting from the use of the heating meshes and heating control system and on the dependence of the correlation between the outdoor air temperature and the time taken for the required temperature rise on the depth of the heating meshes were collected and analyzed. RESULTS : The effects of the heating control system's preheat temperature and the hot meshes buried at depths of 50 mm and 100 mm on the melting of snow for snowfalls of different intensities have been verified. From the study of the time taken for the specimen's surface temperature to increase from the preheat temperature (0℃) to the reference temperature (5~8℃) for different snowfall intensities, the correlation between the burial depth and outdoor air temperature has been determined to be as follows: Time=15.10+1.141Depth-6.465Temp CONCLUSIONS : The following measures are suggested. For the effective use of the electric heating mesh, it should be located under a slab it may be put to practical use by positioning it under a slab. From the management aspect, the heating control system should be adjusted according to weather conditions, that is, the snowfall intensity.

This study performed field examinations of a zero discharge and reuse system developed by Hong and Choi(2009). The system installed one of villages located in Hyoryeong-myeon, Gunwee-gun for the experiments. The zero discharge and reuse system consists of anoxic, FES (Ferrous Electricity System), Oxic, Cralifier processes for water treatments. The main feature of the system is to remove phosphorous by using Fe-ionizing module within the FES process. The water purification performances of the system were evaluated, while any defects for using the system were investigated through the field monitoring. It was found that the removal capacities of T-P, T-N, and BOD of the system meet the required water quality with outstanding performance from T-P by obtaining the results of over 90 % removal rates. The efficiency of T-P removal rate of the system found to be greatly influenced by whether using an automatic washing system to the Fe-ionizing module and conducting replacement of iron plate within a proper period.