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Numerical Analysis of Collapse Behavior in Industrial Stack Explosive Demolition (산업용 연돌 발파해체에서 붕괴거동에 관한 수치해석적 연구)

  • Pu-Reun Jeon;Gyeong-Jo Min;Daisuke Fukuda;Hoon Park;Chul-Gi Suk;Tae-Hyeob Song;Kyong-Pil Jang;Sang-Ho Cho
    • Explosives and Blasting
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    • v.41 no.3
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    • pp.62-72
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    • 2023
  • The aging of plant structures due to industrialization in the 1970s has increased the demand for blast demolition. While blasting can reduce exposure to environmental pollution by shortening the demolition period, improper blasting design and construction plans pose significant safety risks. Thus, it is vital to consider optimal blasting demolition conditions and other factors through collapse behavior simulation. This study utilizes a 3-D combined finite-discrete element method (FDEM) code-based 3-D DFPA to simulate the collapse of a chimney structure in a thermal power plant in Seocheon, South Korea. The collapse behavior from the numerical simulation is compared to the actual structure collapse, and the numerical simulation result presents good agreement with the actual building demolition. Additionally, various numerical simulations have been conducted on the chimney models to analyze the impact of the duct size in the pre-weakening area. The no-duct, duct, and double-area duct models were compared in terms of crack pattern and history of Z-axis displacement. The findings show that the elapse-time for demolition decreases as the area of the duct increases, causing collapse to occur quickly by increasing the load-bearing area.

Agent Model Construction Methods for Simulatable CPS Configuration (시뮬레이션 가능한 CPS 구성을 위한 에이전트 모델 구성 방법)

  • Jinmyeong Lee;Hong-Sun Park;Chan-Woo Kim;Bong Gu Kang
    • Journal of the Korea Society for Simulation
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    • v.33 no.2
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    • pp.1-11
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    • 2024
  • A cyber-physical system is a technology that connects the physical systems of a manufacturing environment with a cyber space to enable simulation. One of the major challenges in this technology is the seamless communication between these two environments. In complex manufacturing processes, it is crucial to adapt to various protocols of manufacturing equipment and ensure the transmission and reception of a large volume of data without delays or errors. In this study, we propose a method for constructing agent models for real-time simulation-capable cyberphysical systems. To achieve this, we design data collection units as independent agent models and effectively integrate them with existing simulation tools to develop the overall system architecture. To validate the proposed structure and ensure reliability, we conducted empirical testing by integrating various equipment from a real-world smart microfactory system to assess the data collection capabilities. The experiments involved testing data delay and data gaps related to data collection cycles. As a result, the proposed approach demonstrates flexibility by enabling the application of various internal data collection methods and accommodating different data formats and communication protocols for various equipment with relatively low communication delays. Consequently, it is expected that this approach will promote innovation in the manufacturing industry, enhance production line efficiency, and contribute to cost savings in maintenance.

Comparative analysis of wavelet transform and machine learning approaches for noise reduction in water level data (웨이블릿 변환과 기계 학습 접근법을 이용한 수위 데이터의 노이즈 제거 비교 분석)

  • Hwang, Yukwan;Lim, Kyoung Jae;Kim, Jonggun;Shin, Minhwan;Park, Youn Shik;Shin, Yongchul;Ji, Bongjun
    • Journal of Korea Water Resources Association
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    • v.57 no.3
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    • pp.209-223
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    • 2024
  • In the context of the fourth industrial revolution, data-driven decision-making has increasingly become pivotal. However, the integrity of data analysis is compromised if data quality is not adequately ensured, potentially leading to biased interpretations. This is particularly critical for water level data, essential for water resource management, which often encounters quality issues such as missing values, spikes, and noise. This study addresses the challenge of noise-induced data quality deterioration, which complicates trend analysis and may produce anomalous outliers. To mitigate this issue, we propose a noise removal strategy employing Wavelet Transform, a technique renowned for its efficacy in signal processing and noise elimination. The advantage of Wavelet Transform lies in its operational efficiency - it reduces both time and costs as it obviates the need for acquiring the true values of collected data. This study conducted a comparative performance evaluation between our Wavelet Transform-based approach and the Denoising Autoencoder, a prominent machine learning method for noise reduction.. The findings demonstrate that the Coiflets wavelet function outperforms the Denoising Autoencoder across various metrics, including Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and Mean Squared Error (MSE). The superiority of the Coiflets function suggests that selecting an appropriate wavelet function tailored to the specific application environment can effectively address data quality issues caused by noise. This study underscores the potential of Wavelet Transform as a robust tool for enhancing the quality of water level data, thereby contributing to the reliability of water resource management decisions.

Simplistic Beam Theory-based Structural Safety Evaluation Method for Block Structure on the A-Carrier (블록 구조물 적치용 지지대의 빔 이론 기반 구조 안전성 평가법)

  • Myung-Su Yi;Joo-Shin Park
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.30 no.4
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    • pp.358-364
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    • 2024
  • Type A carrier structures that support blocks or equipment gradually deform over time with load changes, reducing the area in contact with the block and changing the load pattern from distributed to concentrated during construction work in the shipyard. This phenomenon has the potential to misrepresent actual service loads. In particular, A carriers are often used by small manufacturers, who often do not have specialized engineering capabilities, necessitating the development of a method for easy calculation of carrier safe working load. This study proposes a quick evaluation method for the long-term safe working load of Type A carriers, to predict the plastic deformation and safety issues resulting from changes in load distribution. Based on the results of finite element analysis (beam and shell modeling) of the centralized load, beam-theory was modified to propose a method for determining the distributed load conditions of the A-carrier. In beam modeling, the theoretical value was multiplied by a correction factor of 0.73 for concentrated loads and 0.69 for distributed loads to obtain a safe working load. For shell modeling, a correction factor of 0.75 can be used for concentrated loads and 0.69 for distributed loads. This study can serve as a basis for improving the safety of shipbuilding, enabling quick and effective decisions for determining safe working loads in actual working environments.

A Service Life Prediction for Unsound Concrete Under Carbonation Through Probability of Durable Failure (탄산화에 노출된 콘크리트 취약부의 확률론적 내구수명 평가)

  • Kwon, Seung Jun;Park, Sang Soon;Nam, Sang Hyeok;Lho, Byeong Cheol
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.2
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    • pp.49-58
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    • 2008
  • Generally, steel corrosion occurs in concrete structures due to carbonation in down-town area and underground site and it propagates to degradation of structural performance. In general diagnosis and inspection, only carbonation depth in sound concrete is evaluated but unsound concrete such as joint and cracked area may occur easily in a concrete member due to construction process. In this study, field survey of carbonation for RC columns in down-town area is performed and carbonation depth in joint and cracked concrete including sound area is measured. Probability of durable failure with time is calculated through probability variables such as concrete cover depth and carbonation depth which are obtained from field survey. In addition, service life of the structures is predicted based on the intended probability of durable failure in domestic concrete specification. It is evaluated that in a RC column, various service life is predicted due to local condition and it is rapidly decreased with insufficient cover depth and growth of crack width. It is also evaluated that obtaining cover depth and quality of concrete is very important because the probability of durable failure is closely related with C.O.V. of cover depth.

Automated Data Extraction from Unstructured Geotechnical Report based on AI and Text-mining Techniques (AI 및 텍스트 마이닝 기법을 활용한 지반조사보고서 데이터 추출 자동화)

  • Park, Jimin;Seo, Wanhyuk;Seo, Dong-Hee;Yun, Tae-Sup
    • Journal of the Korean Geotechnical Society
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    • v.40 no.4
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    • pp.69-79
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    • 2024
  • Field geotechnical data are obtained from various field and laboratory tests and are documented in geotechnical investigation reports. For efficient design and construction, digitizing these geotechnical parameters is essential. However, current practices involve manual data entry, which is time-consuming, labor-intensive, and prone to errors. Thus, this study proposes an automatic data extraction method from geotechnical investigation reports using image-based deep learning models and text-mining techniques. A deep-learning-based page classification model and a text-searching algorithm were employed to classify geotechnical investigation report pages with 100% accuracy. Computer vision algorithms were utilized to identify valid data regions within report pages, and text analysis was used to match and extract the corresponding geotechnical data. The proposed model was validated using a dataset of 205 geotechnical investigation reports, achieving an average data extraction accuracy of 93.0%. Finally, a user-interface-based program was developed to enhance the practical application of the extraction model. It allowed users to upload PDF files of geotechnical investigation reports, automatically analyze these reports, and extract and edit data. This approach is expected to improve the efficiency and accuracy of digitizing geotechnical investigation reports and building geotechnical databases.

DEVELOPMENT OF A LYMAN-α IMAGING SOLAR TELESCOPE FOR THE SATELLITE (인공위성 탑재용 자외선 태양카메라(LIST) 개발)

  • Jang, M.;Oh, H.S.;Rim, C.S.;Park, J.S.;Kim, J.S.;Son, D.;Lee, H.S.;Kim, S.J.;Lee, D.H.;Kim, S.S.;Kim, K.H.
    • Journal of Astronomy and Space Sciences
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    • v.22 no.3
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    • pp.329-352
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    • 2005
  • Long term observations of full-disk Lyman-o irradiance have been made by the instruments on various satellites. In addition, several sounding rockets dating back to the 1950s and up through the present have measured the Lymanα irradiance. Previous full disk Lymanα images of the sun have been very interesting and useful scientifically, but have been only five-minute 'snapshots' obtained on sounding rocket flights. All of these observations to date have been snapshots, with no time resolution to observe changes in the chromospheric structure as a result of the evolving magnetic field, and its effect on the Lyman-o intensity. The Lymanα Imaging Solar Telescope(LIST) can provide a unique opportunity for the study of the sun in the Lymanα region with the high time and spatial resolution for the first time. Up to the 2nd year development, the preliminary design of the optics, mechanical structure and electronics system has been completed. Also the mechanical structure analysis, thermal analysis were performed and the material for the structure was chosen as a result of these analyses. And the test plan and the verification matrix were decided. The operation systems, technical and scientific operation, were studied and finally decided. Those are the technical operation, mechanical working modes for the observation and safety, the scientific operation and the process of the acquired data. The basic techniques acquired through the development of satellite based solar telescope are essential for the construction of space environment forecast system in the future. The techniques which we developed through this study, like mechanical, optical and data processing techniques, could be applied extensively not only to the process of the future production of flight models of this kind, but also to the related industries. Also, we can utilize the scientific achievements which are obtained throughout the project And these can be utilized to build a high resolution photometric detectors for military and commercial purposes. It is also believed that we will be able to apply several acquired techniques for the development of the Korean satellite projects in the future.

Remediation of Sediments using Micro-bubble (미세기포를 이용한 퇴적물 정화)

  • Kang, Sang Yul;Kim, Hyoung Jun;Kim, Tschung Il;Park, Hyun Ju;Na, Choon Ki;Han, Moo Young
    • Journal of Korean Society of Environmental Engineers
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    • v.38 no.8
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    • pp.420-427
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    • 2016
  • This study was conducted on the sediment remediation using micro-bubble to remove fine particles. For this study, characteristics of contamination and release in sediment were analyzed. And then, the characteristics of bubbles on removal efficiency was investigated at various operation conditions. In particle size distribution of the sediment used for the study, the proportion of clay and silt (<0.075 mm) was about 7.7%, sand (0.075~4.75 mm) was about 67.8%, and gravel (4.75) was 24.5%. Total nitrogen (TN) and total phosphorus (TP) of the sediment were 2,790~3,260, 261~311 mg/kg respectively. Ignition loss and water content were 4.1~9.6, 32.9~53.2% respectively. In analysis of removal efficiency according to operation conditions of micro-bubble, it was the highest when operation condition is pressure 6 atm, pressurized water ratio 30%, and coagulant dosage 15 ppm. At the time, the sediment's removal efficiency was 19.9%. Accordingly removal efficiency of TN and TP were 21.4, 22.6% respectively. Finally a research was found that fine particles in sediment were almost removed by micro-bubble, which led to decrease nutrients' release at about 20.1~64.3% in comparison to sediment including lots of fine particles.

Methodology of Selecting Criteria for Pedestrian only Street (차없는 거리 선정기준 수립을 위한 방법론 정립 연구)

  • Kim, Yoomi;Park, Jejin;Lee, Junyoung;Ha, Taejun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.5
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    • pp.867-879
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    • 2016
  • Since the 1970s, the region of its own pedestrian center and environmental pollution caused by exhaust gases have been reduced gradually in a continuous increase of the vehicle, school route the central business district, around the school, the sidewalk where the vehicle do not pass, facilities of minimum for the safety of pedestrians and systematic management of an area where an unspecified number and alleys impassable is insufficient. Recently, in response to the "Law for convenience enhancing safety and walking" is enforced in Korea, research on Pedestrian only Street has been actively about the government, the standard for calculating the weights of evaluation associated with it. it is a actuality, however, there are insufficient, evaluation for business promotion is being conducted evaluation polite manner by using, for example, scale residence time and purpose of the passengers as there is no car that has been carried out on a voluntary basis through the municipality have. In this study, by suggesting a method for the selection of the street without a car, make a survey by placing a purpose in the selection method presentation of the street with no car to be construction future, was researching. F.G.I (Focus Group Interview) survey, professors, staff in urban, traffic field of experts in order to present the weights for the evaluation of the Pedestrian only Street by using the evaluation index by type of Pedestrian only Street, was interviewed about the evaluation index for the conducted for professionals engaged in the engineering company, and randomly selected 200 peoples, weighted evaluation of the street with Pedestrian only Street was proposed. By classifying the items purpose and goals of the evaluation type by this by applying the weight, and present the weight of the detailed indicators each corresponding to each item, and scored on the basis of the result, in this paper it can be so that one methodology for the selection standard for the construction as Pedestrian only Street, and the weight of the evaluation of the type that has been derived, the selection and evaluation methods and then added to these criteria to settle careful study of the reference should be performed further.

Fish Distribution, Compositions and Community Structure Characteristics during Juksan-Weir Construction in Yeongsan River Watershed (영산강 수계에서 죽산보 건설 중의 어류 분포.종 조성 및 군집구조 특성)

  • Ko, Dae-Geun;Choi, Ji-Woong;Lim, Byung Jin;Park, Jong Hwan;An, Kwang-Guk
    • Korean Journal of Environment and Ecology
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    • v.26 no.6
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    • pp.892-901
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    • 2012
  • The purpose of this research was to analyze fish fauna, distribution patterns, and fish community structures in the Juksan-Weir regions of upper weir(R-UW) and lower weir(R-LW), which was constructed in 2011 on Yeongsan River watershed. Our outcomes will provide valuable information in the impact analysis of weir constructions next decades, even if the current research is limited to distributions and fauna studies of fishes. The fishes observed were 8 family and 30 species in all the sites, and the number of the species in the regions of R-UW and R-LW was 23(938 individuals) and 27(1,680 individuals), respectively, indicating greater abundance in the lower region of Juksan-Weir. Most dominant species was Opsarichthys uncirostris amurensis with relative abundance of 42%, and this species had greater abundance in the R-LW(49%) than in the R-UW(30%). Coilia nasus, was the migratory fish sampled in this region and had no differences of abundance between the two regions. The extic species observed were Carassius cuvieri, Lepomis macrochirus, and Micropterus salmoides. The two formers of Carassius cuvieri(1.2%) and Lepomis macrochirus(3.7%) dominated in the R-UW, whereas Micropterus salmoides had greater dominance in the region of R-LW. According to tolerance guild analysis, the proportion of sensitive species ranged from 0.4 to 0.5%, and that of tolerant species ranged from 65% to 70%, implying a severe pollution of nutrients and organic matters in the water body. In the mean time, according to trophic guild analysis, the proportion of carnivores(57 - 77%) was evidently higher than that of insectivores(10 - 20%), indicating a dominance of the carnivores. Especially, high abundance of the bass, exotic species, may disturb the fish overall food chain, so the efficient ecosystem management may be required for the conservation of endemic species. When we examined fish data files of last 60 years, the species of Culter brevicauda, designated as endangered species, was observed firstly in our research area and the total number was 5 individuals(0.2% of the total). So, this region observed should be conserved as a protection zone and further monitoring studies should be done in the future.