• Title/Summary/Keyword: Durability Performance Evaluation

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Development Process of Wire Brush Automatic Transplanter of Plait Fixation Method (엮음고정방식의 와이어 브러시 자동 식모기 개발 프로세스)

  • In-Chul Lee
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.4_2
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    • pp.577-584
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    • 2023
  • In this study, among the parts of oil vapor collectors that are already being produced, weaving wire brush automatic transplanters for oil vapor collectors for machine tools of the weaving fixing method, which are not automated due to the specificity of the process and are being produced manually, are developed and reliability is secured through performance evaluation. did Oil vapor collectors play an important role in removing air pollutants and improving air quality, and the coagulation effect of the collection technology is mostly due to brushes. In the experiment, an automatic transplanter was developed to automatically manufacture and produce the wire brush of the oil vapor collector, which is manufactured and used manually. For the experiment of the developed wire brush, an experimental chamber was built, and performance and durability were evaluated through the dust collection efficiency evaluation using the electrostatic precipitator method of contaminants (oil mist). Through this study, we intend to reduce the production time and unit cost of collectors and improve the environment at industrial sites.

Accuracy Evaluation of Machine Learning Model for Concrete Aging Prediction due to Thermal Effect and Carbonation (콘크리트 탄산화 및 열효과에 의한 경년열화 예측을 위한 기계학습 모델의 정확성 검토)

  • Kim, Hyun-Su
    • Journal of Korean Association for Spatial Structures
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    • v.23 no.4
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    • pp.81-88
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    • 2023
  • Numerous factors contribute to the deterioration of reinforced concrete structures. Elevated temperatures significantly alter the composition of the concrete ingredients, consequently diminishing the concrete's strength properties. With the escalation of global CO2 levels, the carbonation of concrete structures has emerged as a critical challenge, substantially affecting concrete durability research. Assessing and predicting concrete degradation due to thermal effects and carbonation are crucial yet intricate tasks. To address this, multiple prediction models for concrete carbonation and compressive strength under thermal impact have been developed. This study employs seven machine learning algorithms-specifically, multiple linear regression, decision trees, random forest, support vector machines, k-nearest neighbors, artificial neural networks, and extreme gradient boosting algorithms-to formulate predictive models for concrete carbonation and thermal impact. Two distinct datasets, derived from reported experimental studies, were utilized for training these predictive models. Performance evaluation relied on metrics like root mean square error, mean square error, mean absolute error, and coefficient of determination. The optimization of hyperparameters was achieved through k-fold cross-validation and grid search techniques. The analytical outcomes demonstrate that neural networks and extreme gradient boosting algorithms outshine the remaining five machine learning approaches, showcasing outstanding predictive performance for concrete carbonation and thermal effect modeling.

Evaluation of Durability and Slope Stability of Green Soil using Cementitious Materials (시멘트 계 재료를 사용한 녹생토의 내구성 및 사면 안정성 평가)

  • Kim, Il-Sun;Choi, Yoon-Suk;Yang, Eun-Ik
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.5
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    • pp.45-53
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    • 2018
  • Among the various slope stabilization methods, the green soil method based on the growth of plants is advantageous to the environment, but the durability and slope stability are insufficient when the green soil method is applied to a steep slope and rock slope sites. Therefore, in this study, green soil, which improved the adhesion performance and the vegetation environment, was developed using cementitious materials and ECG, and the durability and slope stability as well as the possibility of its use as a rock vegetation base material were assessed. From the results, the adhesive force and internal friction angle were higher than that of the existing green soil so that it could be used for in situ construction. The soil hardness value was 26 mm, which was slightly higher than that of the best growth condition of the plant, 18~23 mm, and the drying shrinkage strain was approximately 3%; hence, it is not expected to affect the durability of green soil. The results of a rainfall intensity simulation for evaluating the slope adhesion force showed that slope failure did not occur under all conditions. The damage decreased with increasing slope angle. Therefore, the green soils developed in this study have excellent durability and slope stability and can be used for rock slope sites.

A Study on the Evaluation of Hydrodynamic Performance of Trileaflet Prosthetic Heart Valves (삼엽식 인공판막의 수력학적 성능평가에 관한 연구)

  • 김혁필;이계한
    • Journal of Biomedical Engineering Research
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    • v.18 no.2
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    • pp.147-156
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    • 1997
  • Various prosthetic heart valves have been developed and used clinically, but they have problems, such as thrombogenecity, hemoltsis, high cost and low durability. New types of trileaflet polymer heart valves have been developed in order to use them as inlet and outlet valves in a ventricular assist device. The aim of this study is to determine the hydrodynamic effectiveness of the newly designed trileaflet polymer valves and their feasibility for temporary use in the blood pumps. Trileaflet polymer valves are made of polyurethane, because of its good blood compatibility, high tonsil strength and good resistance to fatigue. An in vitro experimental investigation was perf'ormed in order to ev91ua1e hydrodynamic performance of the trileaflet polymer valves having different design and fabrication tech- niques. The St. Jude Medical valve (SJMV) and floating-type monoleaflet polymer valve (MLPV) were also tested The pressure drop across the valve, leakage volume, and the flow patterns mere investigated for valves. The result of comparative tests showed that the trileaflet polymer valves had a better hydrodynamic performance than the others. TPV which has two stable membrane shape showed the lowest back flow. The pressure hops of TPVs were lower than that of MLPV, but slightly higher than SJMV. The hydrodynamic performance of valves under the pulastile flow showed the similar results as steady flow. The velocity profiles and turbulent intensities were measured at the distal sites of valves using a hot-film anemometer. Central flow was maintained in trileaflet polymer valves, and the maximum turbulent intensities were lower in TPVs comparing to MLPV.

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Performance Evaluation for Deteriorated Masonry of Military Facilities (조적조 노후 군시설의 성능평가기준)

  • Yang, Eun-Bum;Shin, Jong-Hyun;Lee, Chan-Sik
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.7 no.3
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    • pp.167-174
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    • 2003
  • Military facilities with masonry have a great portion in the whole military facilities. But lots of them have been used for more than 20 years, the degree of deterioration of the facilities are serious. Futhermore, as insufficient budget for the facilities maintenance and poor maintenance, the performance of the aged masonry facilities have continually decreased. We suggest a structural performance assessment criteria for the military facility through literature review, interview with experts and questionnaire. The major assessment factors for the structural performance include the inclining and sinking degree of the facilities, durability of materials and resisting force of the structural members.

Development and Evaluation of Trimodal Silver Paste for High-Frequency EMI Shielding Films with a Focus on Flexibility, Durability, and Shielding Characteristics (고주파 EMI 차폐 필름을 위한 트라이모달 실버 페이스트의 개발과 유연성, 내구성 및 차폐 특성에 대한 평가)

  • Hyun Jin Nam;Seonwoo Kim;Yubin Kim;Se-Hoon Park;Moses Gu;Su-Yong Nam
    • Journal of the Microelectronics and Packaging Society
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    • v.31 no.3
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    • pp.42-49
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    • 2024
  • In the electromagnetic wave shielding material market, superior shielding performance in the high-frequency range, along with flexibility and durability, has emerged as critical requirements. The need for high-performance EMI (Electromagnetic Interference) films to address electromagnetic wave interference issues is growing, particularly in various industrial sectors such as smart electronic devices, automotive electronic systems, and communication equipment. In this study, a trimodal silver paste was developed and fabricated into an EMI film, with its performance evaluated. The developed silver paste, utilizing a modified epoxy binder, exhibited properties suitable for screen printing processes. The film demonstrated excellent shielding performance, with an average attenuation of -99 dB in the high-frequency range of the 5G spectrum (26.5 GHz to 40 GHz), and a shielding effectiveness of -90.3 dB at 33.6 GHz. Flexibility and durability tests showed that the film maintained its flexibility even at a curvature radius of 1 mm. In the bending cycle test, the resistance increased by approximately 25.5% from 0.51 Ω to 0.64 Ω after 10,000 cycles in the outer bending scenario, while in the inner bending scenario, the resistance decreased by about 3.6%, indicating reduced resistance to compressive stress.

Methodology of Field Investigation and Laboratory Test for Distresses of Old Concrete Pavements (노후 콘크리트 포장 파손에 대한 현장조사 및 실내시험 방법)

  • Lee, Ki Sang;Lee, Jun Hyeok;Kang, Min Soo;Cho, Nam Hyun;Jeong, Jin Hoon
    • International Journal of Highway Engineering
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    • v.18 no.5
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    • pp.21-29
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    • 2016
  • PURPOSES : The purpose of this study is to suggest a specific investigation guideline to decide priority of repairing old concrete pavements that pile up substantially. METHODS : In this study, a principle of division of homogeneous sections was proposed to reflect the characteristics of the pavement reasonably in the specific investigation results. In addition, a checklist and guideline of field investigation were suggested for the old concrete pavement sections, which require inspection toward their durability and structural performance. Furthermore, the items of laboratory test necessary to the old concrete pavement were suggested based on the existing laboratory test considering characteristics of the old concrete pavement. The present condition of the old concrete pavement could be analyzed by the test results. RESULTS : A method of division of homogeneous sections suitable for the specific investigation of the old concrete pavement was suggested. The proportions of distress severity of pavement sections were compared by distress type to figure out the present state of the old concrete pavement. Scaling, durability cracking (or alkali-silica reaction), and longitudinal spalling were selected as the most severe distress types. The detailed positions of the sections were also suggested. The checklist of the specific investigation was categorized by field survey and laboratory test, and its evaluation criteria were proposed. The three types of the sections of durability cracking (or alkali-silica reaction), bridge connection, and asphalt overlay were selected as the sections of the field survey. The compressive strength, void structure, and chloride penetration depth were suggested as the items of the laboratory test. CONCLUSIONS : A fundamental level of the guideline was suggested in this study to resolve the problem of old concrete pavement. Appropriate guidelines related to the repair of the old concrete pavement should be provided by performing additional research efforts.

Evaluation of Applicability of penetrating-type Nano-Coat for Preventing Deterioration of Concrete (침투형 Nano-Coat를 이용한 콘크리트 열화 방지 적용성 평가)

  • Lee, Jun Hee;Kim, Jo Soon;Sim, Yang Mo;Lee, Seung Woo
    • International Journal of Highway Engineering
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    • v.19 no.2
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    • pp.7-15
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    • 2017
  • PURPOSES : Infiltration of moisture, polluted material, and deicer into concrete, accompanied by freeze and thaw can cause significant deterioration of concrete pavement. In order to protect concrete from deterioration, it is necessary to prevent the infiltration of these concrete external materials. The moisture-repellent agent, which is a surface treatment and maintenance material added to concrete structures to render them water resistant, has advantages such as prevention of water infiltration and security against air permeation. Nano-coat, which is referred to as silicon hydride, is typically used as a moisture-repellent agent. Therefore, in this study, an attempt is made to use penetration-type Nano-coat as an alternative in order to evaluate its applicability through environmental resistance tests. METHODS : This study aimed to evaluate the applicability of penetration-type Nano-coat, which can provide water repellency to concrete, in concrete pavements, through various environmental resistance tests such as freezing and thawing resistance, chloride ion penetration resistance, and surface scaling resistance tests. The applicability of penetration-type Nano-coat was demonstrated based on the specification of KS F 2711, KS F 2456, and ASTM C 672. RESULTS :In the case of penetration-type Nano-coat applied on sound concrete, an increase in concrete durability was demonstrated by the negligible chloride ion penetrability and the absence of scaling, as revealed by visual observation of the surface, after 50 cycles of scaling resistance test. In addition, test result of the application of penetration-type Nano-coat on deteriorated concrete established that concrete surface pretreated by grinding provided improved durability than non-treated concrete. CONCLUSIONS :This study indicates that penetration-type Nano-coat is applicable as an effective alternative, to increase the durability of concrete structures. In addition, it was known that pretreatment of deteriorated concrete surface, such as grinding, is required to improve the long-term performance of concrete pavement.

Evaluation of Durability on Latex Modified Mortar for maintenance in concrete structure (콘크리트 구조물 보수용 라텍스개질 모르타르의 내구성능 평가)

  • Sung, Sang-Kyoung;Park, Sung-Ki;Lee, Sang-Woo;Won, Jong-Pil;Park, Chan-Gi
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.633-636
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    • 2008
  • Concrete structures are occur many various deteriorations in the course of time and many efforts have progressed to improve on performance of concrete. The purpose of this study is to evaluate the durability of latex modified mortar in order to repair concrete structure which are happened deterioration. In this study, we tested plastic shrinkage, drying shirnkage, repeated freezing and thawing, permeability and resistance of chemical solution. Latex modified mortar and two kinds of sprayed polymer mortar used on durability test. As a result of test, latex modified repair mortar was exhibited durablilty improvement compared to the conventional sprayed polymer mortars. It is judged the fact that latex modified mortar have no problem in site application but additionally many research will be necessary.

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Evaluation of Strength and Durability of Mortar using Ferronickel Slag Powder and Admixtures (페로니켈슬래그 미분말 및 혼화재의 복합사용에 따른 모르타르의 강도 및 내구성 평가)

  • Jo, Seol-Ah;Yoo, Jeong-Hwan;Park, Sang-Soon
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.3
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    • pp.262-270
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    • 2019
  • Ferronickel slag, which is an industrial byproduct, is activated by mechanochemical reaction as a nonferrous metal and can be used as an admixture. Therefore, ferronickel slag is used as a substitute resource of admixture. In this study, to evaluate the effect of mixed of ferronickel slag powder and admixture, a mortar using a mixture of ferronickel slag powder, quicklime, gypsum and calcium chloride was fabricated by vibrated and rolled manufacturing method. Strength were evaluated by flexural and compressive strength tests, and durability was evaluated by performing chlorine ion penetration resistance and chemical resistance test. When the substitution ratio of ferronickel slag powder is constant, it is considered that the mixed use of quicklime, gypsum and calcium chloride as admixtures increases the performance.