• Structural Engineering and Mechanics
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• v.77 no.3
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• pp.417-439
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• 2021

The geometric nonlinearity has been successfully integrated with the design of steel structural system. Thus, the tubular lattice girder, one application of steel structural systems have already been optimized to obtain an economic design following the completion of computationally expensive design procedure. In order to decrease its computing cost, this study proposes to employ five multi-objective metaheuristics for the design optimization of geometrically nonlinear tubular lattice girder. Then, the employed multi-objective optimization algorithms (MOAs), NSGAII, PESAII, SPEAII, AbYSS and MoCell are evaluated considering their computing performances. For an unbiased evaluation of their computing performance, a tubular lattice girder with varying size-shape-topology and a benchmark truss design with 17 members are not only optimized considering the geometrically nonlinear behavior, but three benchmark mathematical functions along with the four benchmark linear design problems are also included for the comparison purpose. The proposed experimental study is carried out by use of an intelligent optimization tool named JMetal v5.10. According to the quantitative results of employed quality indicators with respect to a statistical analysis test, MoCell is resulted with an achievement of showing better computing performance compared to other four MOAs. Consequently, MoCell is suggested as an optimization tool for the design of geometrically nonlinear tubular lattice girder than the other employed MOAs.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.9
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• pp.2976-2990
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• 2022

The adaptive adjustment of reference or weight vectors in decomposition-based methods has been a hot research topic in the evolutionary community over the past few years. Although various methods have been proposed regarding this issue, most of them aim to diversify solutions in the objective space to cover the true Pareto fronts as much as possible. Different from them, this paper proposes a knee point-based reference vector adaptive adjustment strategy to concurrently balance the convergence and diversity. To be specific, the knee point-based reference vector adaptive adjustment strategy firstly utilizes knee points to construct the adaptive reference vectors. After that, a new fitness function is defined mathematically. Then, this paper further designs a many-objective evolutionary algorithm with knee point-based reference vector adaptive adjustment strategy, where the mating operation and environmental selection are designed accordingly. The proposed method is extensively tested on the WFG test suite with 8, 10 and 12 objectives and MPDMP with state-of-the-art optimizers. Extensive experimental results demonstrate the superiority of the proposed method over state-of-the-art optimizers and the practicability of the proposed method in tackling practical many-objective optimization problems.

• Journal of People, Plants, and Environment
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• v.24 no.2
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• pp.179-194
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• 2021

Background and objective: Plant-based biofilter system has become a promising candidate for improving indoor air quality due to its eco-friendly and sustainable nature. However, it remains controversial whether indoor air purification using a biofilter is effective. Methods: This study used the one-group pre- and post-test design to analyze the effects of the operation of the plant-based biofilter system on indoor air quality, students' perception of indoor air quality, health effects, and subjective and objective attentiveness. Results: Results of this study show that the application of the plant-based biofilter system changed the air environment in the classroom. The operation of the plant-based biofilter system significantly decreased PM_2.5 and PM₁₀ and slightly increased temperature and humidity. Satisfaction with air quality and subjective attentiveness were significantly improved but objective attentiveness and health effects were not improved. Conclusion: Further studies need to be conducted for improving indoor air quality of schools and evaluating the health effects and attention of occupants to present the objective performance of the plant-based biofilter system.

• Journal of Applied Reliability
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• v.15 no.2
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• pp.90-100
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• 2015

Reliability growth rate (or reliability growth curve slope) have the two cases of trend as a constant or changing one during the reliability growth testing. The changing case is very common situation. The reasons of reliability growth rate changing are that the failures to follow the NHPP (None-Homogeneous Poisson Process), and the solutions implemented during test to break out other problems or not to take out all of the root cause permanently. If the changing were big, the "Goodness of Fit (GOF)" of reliability growth curve to test data would be very low and then reduce the accuracy of assessing result with test data. In this research, we are using Duane model and AMSAA model for assessing test data and projecting the reliability level of complex and repairable system as like construction equipment and vehicle. In case of no changing in reliability growth rate, it is reasonable for reliability engineer to implement the original Duane model (1964) and Crow-AMSAA model (1975) for the assessment and projection activity. However, in case of reliability growth rate changing, it is necessary to find the method to increase the "GOF" of reliability growth curves to test data. To increase GOF of reliability growth curves, it is necessary to find the proper parameter calculation method of interesting reliability growth models that are applicable to the situation of reliability growth rate changing. Since the Duane and AMSAA models have a characteristic to get more strong influence from the initial test (or failure) data than the latest one, the both models have a limitation to contain the latest test data information that is more important and better to assess test data in view of accuracy, especially when the reliability growth rate changing. The main objective of this research is to find the parameter calculation method to reflect the latest test data in the case of reliability growth rate changing. According to my experience in vehicle and construction equipment developments over 18 years, over the 90% in the total development cases are with such changing during the developing test. The objective of this research was to develop the newly assessing method and the process for GOF level increasing in case of reliability growth rate changing that would contribute to achieve more accurate assessing and projecting result. We also developed the new evaluation method for GOF that are applicable to the both models as Duane and AMSAA, so it is possible to compare it between models and check the effectiveness of new parameter calculation methods in any interesting situation. These research results can reduce the decision error for development process and business control with the accurately assessing and projecting result.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.279-284
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• 2004

In this study, we suggested the ring creep test using the ring specimen of Arsene for estimating the burst creep properties of the cladding in stead of burst creep test. For this objective, we used the load-displacement conversion relationship of ring specimen called LCRR which had been determined on our previous study at high temperature by performing the ring tensile test and the numerical analysis. Then we carried out both the ring creep test and the burst creep test between 350 $^{\circ}C$ and 600$^{\circ}C$ which were higher then the in-service temperature of the cladding in a reactor. The creep properties from the ring creep test with applying LCRR were compared with those from the burst creep test of closed-end specimens. From the results, it could be seen an very strong relationship between them, especially in Larson- Miller parameter. So, it is expected that we can easily anticipate the creep properties of not only claddings but also various small pressure pipes using the ring creep test.

• Journal of Pharmacopuncture
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• v.9 no.1
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• pp.121-126
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• 2006

Objective : The purpose of the study was to observe local reactions of BV and BVP skin test, and to compare those between BV and BVP. Methods : We performed BV or BVP Skin test to 42 patients, and then we measured wheal and erytherma on skin test area by digital caliper after 15 minutes. Results : 1. In BV Skin test, the mean size of wheals was $l0.l0{\pm}0.78mm$ and the mean size of erythermas was $29.85{\pm}6.23mm$. 2. In BVP Skin test, the mean size of wheals was $7.05{\pm}3.20mm$ and the mean size of erythermas was $19.58{\pm}7.62mm$. 3. The local reactions of BVP Skin test decreased significantly(P<0.01) than those of BV skin test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.964-969
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• 2005

In this study, we suggested the ring creep test using the ring specimen of Arsene for estimating the burst creep properties of the cladding in stead of burst creep test. For this objective, we used the load-displacement conversion relationship of ring specimen called LCRR which had been determined on our previous study at high temperature by performing the ring tensile test and the numerical analysis. Then we carried out both the ring creep test and the burst creep test between $350^{\circ}C$ and $600^{\circ}C$ which were higher than the in-service temperature of the cladding in a reactor. The creep properties from the ring creep test with applying LCRR were compared with those from the burst creep test of closed-end specimens. From the results, it could be seen an very strong relationship between them, especially in Larson-Miller parameter. So, it is expected that we can easily predict the creep properties of not only claddings but also various small pressure pipes using the ring creep test.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.335-343
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• 1998

Recently, new experimental criteria for reinforced concrete frame structures in high seismic regions have been reported in United States. The objective of the criteria is to get more reliable test data which are valid to compare with other test data done by different researchers. The criteria precribe test method of specimens, analysis method of test data, and limiting values needed to specimens like drift angle, energey dissipation ratio, stiffness, and strength. These criteria might be usefel to get objective conclusion. Shear wall structures, which belong to one of earthquake resisting systems, also need this kind of criteria. But, the general response of shear wall structures is a little bit different from that of frame structures since shear wall restrains the horizontal displacement caused by horizontal force and increases the stiffness and strength. The objective of this paper is to propose a criterion for limiting drift and energy dissipation ratio of shear walls based on structural testing. These are the most important values for presenting the capacity of shear walls. Limiting drift and energy dissipation ratios were examined for tests on shear walls having ductile type failures. Test data were analyzed and compared to the results for a suggested acceptance criteria that involve a limiting drift that is a function of aspect ratio and a limiting energy dissipation ratio that is a function of displacement ductility and damping.

• Journal of Korean Neurosurgical Society
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• v.52 no.5
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• pp.472-475
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• 2012

Objective : The aim of this study is to establish the value of hand elevation test as a reproducible provocative test for the diagnosis of carpal tunnel syndrome (CTS). Methods : We had a prospective study of 45 hands of 38 patients diagnosed with CTS between April 2005 and February 2009. The diagnosis of CTS was based on the American Academy of Neurology clinical diagnostic criteria. Experimental and control group patients underwent Tinel's test, Phalen's test, carpal compression test and hand elevation test as provocative tests for CTS. Results : We used chi-square analysis to compare Tinel's test and Phalen's test, carpal compression test with hand elevation test. The sensitivity and specificity of the hand elevation test is 86.7% and 88.9% each. Tinel's test had 82.2% sensitivity and 88.9% specificity. Phalen's test had 84.4% sensitivity and 86.7% specificity. Carpal compression test had 84.4% sensitivity 82.2% specificity. Comparisons of sensitivity and specificity between hand elevation test and Tinel's test, Phalen's test, and carpal compression test had no statistically significant differences. To compare the diagnostic accuracies of four tests, the area under the non-parametric receiver operating character curve was applied. Conclusion : The hand elevation test has higher sensitivity and specificity than Tinel's test, Phalen's test, and carpal compression test. Chi-square statistical analysis confirms the hand elevation test is not ineffective campared with Tinel's test, Phalen's test, and carpal compression test.

• Environmental Engineering Research
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• v.22 no.4
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• pp.339-346
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• 2017

The objective of this study is the evaluation of the performance of a large-scale respirometer (LSR) of 17.7 L in the determination of the methane generation rate constant (k) values. To achieve this objective, a comparison between anaerobic (GB21) and LSR tests was conducted. The data were modeled using a linear function, and the resulting correlation coefficient ($R^2$) of the linear regression is 0.91. This result shows that despite the aerobic conditions, the biodegradability values that were obtained from the LSR test produced results that are similar to those from the GB21 test. In this respect, the LSR test can be an indicator of the anaerobic biodegradability for landfill waste. In addition, the results show the high repeatability of the tests with an average coefficient of variance (CV) that is lower than 10%; furthermore, the CV for the LSR is lower than that of the GB21, which indicates that the LSR-test method could provide a better representation of waste samples. Therefore, the LSR method allows for both the prediction of the long-term biodegradation potential in a shorter length of time and the reduction of the sampling errors that are caused by the heterogeneity of waste samples. The k values are $0.156y^{-1}$ and $0.127y^{-1}$ for the cumulative biogas production (GB21) and the cumulative oxygen uptake for the LSR, respectively.