• Earthquakes and Structures
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• 제23권4호
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• pp.329-338
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• 2022

This work addresses the optimization controller design problem combining the AI evolution bat (EB) optimization algorithm with a fuzzy controller in the practical application of a reinforced concrete frame structure. This article explores the use of an intelligent EB strategy to reduce the dynamic response of Lead Rubber Bearing (LRB) composite reinforced concrete frame structures. Recently developed control units for plant structures, such as hybrid systems and semi-active systems, have inherently non-linear properties. Therefore, it is necessary to develop non-linear control methods. Based on the relaxation method, the nonlinear structural system can be stabilized by properly adjusting the parameters. Therefore, the behavior of a closed-loop system can be accurately predicted by determining the behavior of a closed-loop system. The performance and durability of the proposed control method are demonstrated by numerical simulations. The simulation results show that the proposed method is a viable and feasible control strategy for seismically tuned composite reinforced concrete frame structures.

• Computers and Concrete
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• 제30권5호
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• pp.357-367
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• 2022

In this paper, we propose an efficient control method that can be transformed into a general building control problem for building structure control using these reliability criteria. To facilitate the calculation of controller H∞, an efficient solution method based on Linear Matrix Inequality (LMI) is introduced, namely H∞-based LMI control. In addition, a self-tuning predictive grey fuzzy controller is proposed to solve the problem caused by wrong parameter selection to eliminates the effect of dynamic coupling between degrees of freedom (DOF) in Self-Tuning Fuzzy Controllers. We prove stability using Lyapunov's stability theorem. To check the applicability of the proposed method, the proposed controller is applied and the control characteristics are determined. The simulation assumes system uncertainty in the controller design and emphasizes the use of acceleration feedback as a practical consideration. Simulation results show that the performance of the proposed controller is impressive, stable, and consistent with the performance of LMI-based methods. Therefore, an effective control method is suitable for seismic reinforcement of civil buildings.

• Smart Structures and Systems
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• 제30권5호
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• pp.537-544
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• 2022

The optimal design of structural composite materials is a research topic that attracts the attention of lots researchers. For many more thirty years, there has been increasing interest in the applications in all kinds of topics, which means taking advantage of fuzzy set theory, fuzzy analysis, and fuzzy control for designing high-performance and efficient structural systems is a fundamental concern for engineers, and many applications require the use of a systems approach to combine structural and active control systems. Therefore, an intelligent method can be designed based on the mitigation method, and by establishing the stable of the closed-loop fuzzy mitigation system, the behavior of the closed-loop fuzzy mitigation system can be accurately predicted. In this article, the intelligent algorithm and optimum design of fuzzy theory for structural control has been provided and demonstrated effective and efficient in practical engineering issues.

• Journal of Preventive Medicine and Public Health
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• 제33권2호
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• pp.174-183
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• 2000

울산시에서 대기 오염 정도가 서로 다른 석유화학공단 인근지역의 초등학생들과 교외지역의 초등학생들을 대상으로 1999년 4월 14일부터 20일까지 공단지역의 A초등학생 51명(남자 27명, 여자 24명), B초등학생 99명(남자 49명, 여자 50명) 및 교외지역의 C초등학생 100명(남자53명, 여자 47명)을 대상으로 의한 호흡기계 증상 유병률 등을 파악하는 설문조사, 폐기능 검사, 흉부 방사선 검사 등을 조사하였으며 그 결과는 다음과 같다. 1. 호흡기계 증상 유병률 조사에서 석유화학공단 인근 A초등학생과 B초등학생은 교외지역의 C초등학생에 비하여 '만성기침', '운동시 호흡곤란' 같은 호흡기계 증상 유병률이 높았다. 2. 조사 초등학생의 폐기능 검사는 연령, 성별로 구분한 다음 폐기능에 영향을 주는 신장, 체중 등의 공변인을 조정 후 비교한 결과 공단지역의 11세 A초등학생과 B초등학생은 교외지역의 C초등학생에 비하여 FVC 및 FEV1이 낮았다. 이상과 같은 결과로 볼 때 공단지역에 거주하는 어린이는 대기오염 등 환경적요인에 호흡기계증상 유병률, 폐기능 등에 영향을 받은 것으로 추정되며 장기적으로 공단지 역에 거주하는 초등학생들에 대하여 호흡기계증상 유병률, 폐기능 검사 등을 주기적으로 전향적 연구가 필요한 것으로 생각되며 또한 호흡기질환의 발생률 및 유병률 등을 면밀히 관찰하는 추가적 연구도 필요한 것으로 사료된다.

• Safety and Health at Work
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• 제1권1호
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• pp.51-60
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• 2010

Objectives: The level of benzene exposure in the petrochemical industry during regular operation has been well established, but not in turnaround (TA), where high exposure may occur. In this study, the characteristics of occupational exposure to benzene during TA in the petrochemical companies were investigated in order to determine the best management strategies and improve the working environment. This was accomplished by evaluating the exposure level for the workers working in environments where benzene was being produced or used as an ingredient during the unit process. Methods: From 2003 to 2008, a total of 705 workers in three petrochemical companies in Korea were studied. Long- and short-term (< 1 hr) samples were taken during TAs. TA was classified into three stages: shut-down, maintenance and start-up. All works were classified into 12 occupation categories. Results: The long-term geometric mean (GM) benzene exposure level was 0.025 (5.82) ppm (0.005-42.120 ppm) and the short-term exposure concentration during TA was 0.020 (17.42) ppm (0.005-61.855 ppm). The proportions of TA samples exceeding the time-weighted average, occupational exposure level (TWA-OEL in Korea, 1 ppm) and the short-term exposure limit (STEL-OEL, 5 ppm) were 4.1% (20 samples of 488) and 6.0% (13 samples of 217), respectively. The results for the benzene exposure levels and the rates of exceeding the OEL were both statistically significant (p < 0.05). Among the 12 job categories of petrochemical workers, mechanical engineers, plumbers, welders, fieldman and scaffolding workers exhibited long-term samples that exceeded the OEL of benzene, and the rate of exceeding the OEL was statistically significant for the first two occupations (p < 0.05). Conclusion: These findings suggest that the periodic work environment must be assessed during non-routine works such as TA.

• 한국환경보건학회지
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• 제47권4호
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• pp.366-377
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• 2021

Background: Polycyclic aromatic hydrocarbons (PAHs) are generated in petrochemical complexes, can spread to residential areas and affect the health of residents. Although harmful PAHs are mainly present in particle phase, gas phase PAHs can generate stronger toxic substances through photochemical reaction. Therefore, the risk assessment for PAHs around the petrochemical complex should consider both particle and gas phase concentrations. Objectives: This study aimed to investigate the concentration characteristics of particle and gas phase PAHs by season in residential areas around petrochemical complexes, and to assess the risk of PAHs. Methods: Samples were collected for 7 days by seasons in 2014~2015 using a high volume air sampler. Particle and gas phase PAHs were sampled using quartz filter and polyurethane foam, respectively, analyzed by GC-MS. Chronic toxicity and probabilistic risk assessment were performed on 14 PAHs. For chronic toxicity risk assessment, inhalation unit risk was used. Monte-Carlo simulation was performed for probabilistic risk assessment using the mean and standard deviation of measured PAHs. Results: The concentration of particle total PAHs was highest in autumn. The gas phase concentration was highest in autumn. The average gas phase distribution ratio of low molecular weight PAHs composed of 2~3 benzene rings was 85%. The average of the medium molecular weight composed of 4 benzene rings was 53%, and the average of the high molecular weight composed of 5 or more benzene rings was 9%. In the chronic toxicity risk assessment, 7 of the 14 PAHs exceeded the excess carcinogenic risk of 1.00×10^-6. In the Monte-Carlo simulation, Benzo[a]pyrene had the highest probability of exceeding 1.00×10^-6, which was 100%. Conclusions: The concentration of PAHs in the residential area around the petrochemical complex exceeded the standard, and the excess carcinogenic risk was evaluated to be high. Therefore, it is necessary to manage the air environment around the petrochemical complex.

• 한국식물생명공학회:학술대회논문집
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• 한국식물생명공학회 2004년도 생명공학 실용화를 위한 비젼
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• pp.196-196
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• 2004

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2003년도 가을 학술발표회 논문집
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• pp.203-204
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• 2003

Generally, polymeric foam has many advantages, such as light-weight, good impact absorptivity and adiabatic properties. Poly (ethylene terephthalate) PET has good recyclability and no toxicity. Hence, if we make foam of PET, it could be used for various applications such as heat insulating material, recyclable packing material, and food vessel. Thus these properties are attractive interests to manufacturers. (omitted)

• 월간포장계
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• 통권130호
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• pp.54-56
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• 2004

• 방재와보험
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• 통권12호
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• pp.82-86
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• 1979