• 한국방재학회:학술대회논문집
• /
• 2008.02a
• /
• pp.63-66
• /
• 2008

The bridge deck section composed of a concrete slab resting on two I-beam girders are known to be susceptible to flutter instability and vortex shedding. Moreover, the cable stayed bridge in construction is more vulnerable to wind rather than in service when the free cantilever construction method is applied. This paper describes the effect of the dynamic wind loads on the bridge during construction and the effect of alternative temporary stabilizing measures. Therefore, a series of wind tunnel tests and numerical analysis were carried out to determine if any countermeasures were required.

• Proceedings of the KIEE Conference
• /
• 2004.11b
• /
• pp.119-121
• /
• 2004

This paper presents a methodology which can make alternatives of distribution system, and can calculate reliability costs, harmonics costs, and construction costs. And by using total cost of the system, decision maker can select the most economic and reasonable alternative. As a result, not only we can decide most economical and reasonable result, but we can get proper reliability and harmonics level. The usefulness of the method is verified by applying it to the test system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.207-208
• /
• 2007

Recently, high performance microelectronic devices are designed in multi-layer structure in order to make dense wiring of metal conductors in compact size. Imprint lithography have received significant attention due to an alternative technology for photolithography on such devices. In this work, we synthesized dielectric composite materials based on epoxy resin, and investigated their thermal stabilities and dynamic mechanical properties for thermal imprint lithography. In order to enhance the mechanical properties and toughness of dielectric material, various modified polyetherimide(PEI) was applied in the resin system. Curing behaviours, thermal stabilities, and dynamic mechanical properties of the dielectric materials cured with various conditions were studied using dynamic differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), and Universal Test Method (INSTRON).

• Journal of the military operations research society of Korea
• /
• v.28 no.2
• /
• pp.116-124
• /
• 2002

In just-in-time production systems, U-shaped production lines rather than traditional straight lines are often adopted since they have some advantages. The advantages of U-lines over straight lines are that the workstations required can be reduced and the necessary number of workers can be easily adjusted when the demand rates are changed. In this paper, we present a new genetic algorithm(GA) to minimize the number of workstations primarily and improve the work relatedness secondarily in the U-line production systems. Also, a new heuristic method is presented according to the work related factors and characteristics of U-line balancing. Some major aspects of the proposed GA are discussed, with emphasis on representation, decoding and evaluation function. Extensive experiments are carried out on well-known test-bed problems in the literature to verify the performance of our algorithm . The computational results show that our algorithm is a promising alternative to existing heuristics.

• Proceedings of the Korean Society of Toxicology Conference
• /
• 2003.10b
• /
• pp.124-124
• /
• 2003

A murine local lymph node assay(LLNA) has been developed as an alternative method to guinea pig maximization test for contact sensitization potential. This study was carried out to investigate the potential use of cytokine producing cells to discriminate between allergens and irritant in the LLNA.(omitted)

• Computers and Concrete
• /
• v.24 no.4
• /
• pp.295-302
• /
• 2019

Evolutionary algorithms based on conventional statistical methods such as regression and classification have been widely used in data mining applications. This work involves application of gene expression programming (GEP) for predicting compressive strength of fly ash geopolymer concrete, which is gaining increasing interest as an environmentally friendly alternative of Portland cement concrete. Based on 56 test results from the existing literature, a model was obtained relating the compressive strength of fly ash geopolymer concrete with the significantly influencing mix design parameters. The predictions of the model in training and validation were evaluated. The coefficient of determination ($R^2$), mean (${\mu}$) and standard deviation (${\sigma}$) were 0.89, 1.0 and 0.12 respectively, for the training set, and 0.89, 0.99 and 0.13 respectively, for the validation set. The error of prediction by the model was also evaluated and found to be very low. This indicates that the predictions of GEP model are in close agreement with the experimental results suggesting this as a promising method for compressive strength prediction of fly ash geopolymer concrete.

• Journal of Positioning, Navigation, and Timing
• /
• v.10 no.4
• /
• pp.253-262
• /
• 2021

Global Navigation Satellite Systems (GNSS) based precise positioning using Real Time Kinematic (RTK) technique has been proposed as an enabler of the formation operation of moving vehicles. In RTK methods, the integer ambiguity of GNSS carrier phase measurements must be resolved. Although there have been many proposed algorithms for the integer ambiguity resolution, the widelane combination of carrier phase measurements and LAMBDA methods have gained the most popularity in literatures when dual frequency GNSS measurements were used. In this paper, we evaluated five alternative methods to determine relative positions of moving base and rover receivers; the round-off scheme of widelane carrier phase, instant least-squares and Kalman filter-based LAMBDA with widelane carrier phase, instant least-squares and Kalman filter-based LAMBDA with dual frequency measurements. The paper presented the performance of each method using flight test data, which showed their strength and weakness in the aspects of time-to-first-fix, ambiguity resolution success ratio, and relative position errors. Based on that, we provided practical recommendations of RTK operations for moving vehicles.

• ETRI Journal
• /
• v.41 no.2
• /
• pp.184-196
• /
• 2019

Wavelet packet modulation (WPM) is a multicarrier modulation (MCM) technique that has emerged as a potential alternative to the widely used orthogonal frequency-division multiplexing (OFDM) method. Because WPM has overlapped symbols, equalization cannot rely on the use of the cyclic prefix (CP), which is used in OFDM. This study applies linear minimum mean-square error (MMSE) equalization in the time domain instead of in the frequency domain to achieve low computational complexity. With a modest equalizer filter length, the imperfection of MMSE equalization results in subcarrier attenuation and noise amplification, which are considered in the development of a bit-loading algorithm. Analytical expressions for the bit error rate (BER) performance are derived and validated using simulation results. A performance evaluation is carried out in different test scenarios as per Recommendation ITU-R M.1225. Numerical results show that WPM with equalization-aware bit loading outperforms OFDM with bit loading. Because previous comparisons between WPM and OFDM did not include bit loading, the results obtained provide additional evidence of the benefits of WPM over OFDM.

• Journal of information and communication convergence engineering
• /
• v.22 no.1
• /
• pp.23-32
• /
• 2024

This study aims to improve the quality of distance learning by developing webcast-based e-learning media and integrating it into an e-learning platform for functional job training purposes at the National Research and Innovation Agency, Indonesia. This study uses a Technology Acceptance Model (TAM) to assess and predict user perceptions of information systems using webcast platforms as an alternative to conventional applications. The research method was an online survey using Google Forms. Data collected from 136 respondents involved in practical job training were analyzed using structural equation modeling to test the technology acceptance model. The results showed that the proposed model effectively explained the variables associated with the adoption of web-based e-learning during the COVID-19 pandemic in Indonesia for participants engaged in functional job training. These findings suggest that users' perceptions of ease of use, usefulness, benefits, attitudes, intentions, and webcast usage significantly contribute to the acceptance and use of a more effective and efficient webcast-based e-learning platform.

• Transactions of Materials Processing
• /
• v.33 no.5
• /
• pp.354-362
• /
• 2024

In this paper, the capabilities of recurrent neural networks (RNNs) to describe the viscoelastic properties of acrylonitrile-butadiene styrene (ABS) are investigated. The RNN model was trained using one-dimensional strains and corresponding stress data generated by the finite element method. The optimal model was then employed to predict the viscoelastic behavior of unseen test data. Furthermore, the viscoelastic-based RNN model was tested for extrapolation using other types of strain and corresponding stress data beyond the training set. The agreement between the predicted and actual stresses demonstrates the robust performance of the trained RNN model in predicting different types of strain inputs for larger strain tests, despite being trained only with step strain inputs. Therefore, the use of RNNs can be considered a viable alternative to conventional models for predicting viscoelastic behavior.