• Wind and Structures
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• v.36 no.6
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• pp.405-421
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• 2023

Strong wind is the main factors of wind-damage of high-rise buildings, which often creates largely economical losses and casualties. Wind pressure plays a critical role in wind effects on buildings. To obtain the high-resolution wind pressure field, it often requires massive pressure taps. In this study, two traditional methods, including bilinear and bicubic interpolation, and two deep learning techniques including Residual Networks (ResNet) and Generative Adversarial Networks (GANs), are employed to reconstruct wind pressure filed from limited pressure taps on the surface of an ideal building from TPU database. It was found that the GANs model exhibits the best performance in reconstructing the wind pressure field. Meanwhile, it was confirmed that k-means clustering based retained pressure taps as model input can significantly improve the reconstruction ability of GANs model. Finally, the generalization ability of k-means clustering based GANs model in reconstructing wind pressure field is verified by an actual engineering structure. Importantly, the k-means clustering based GANs model can achieve satisfactory reconstruction in wind pressure field under the inputs processing by k-means clustering, even the 20% of pressure taps. Therefore, it is expected to save a huge number of pressure taps under the field reconstruction and achieve timely and accurately reconstruction of wind pressure field under k-means clustering based GANs model.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.5
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• pp.343-351
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• 2024

In this paper, we introduce the machine learning model to estimate the nominal wake field of a ship from the afterbody hullform using a 3 dimensional CNN (Convolutional Neural Network) model. The convolution layers extract the features of the hullform and they are connected to the nominal wake field. In this research, two different models were tested. The one learns the velocity field itself while the other learns the Fourier coefficients expressing the wake field. Both models showed about 4% volumetric mean velocity error for the test data not used in the learning process. In the case study of two sample ships included in the test data, the direct prediction model showed the better estimation results than the Fourier coefficient based model. Application cases for estimating cavitation performance using the developed model were also introduced.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.160-162
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• 2016

A compact model of tunnel field effect transistor (TFET) has been developed. The model includes a surface potentia calculation module and a band-to-band-tunneling current module. Model comparison with TCAD shows that the mode calculates TFET surface potential and drain current accurately.

• Proceedings of the KIEE Conference
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• 1985.07a
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• pp.127-130
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• 1985

A stochastic model to predict radio interference field as caused by corona discharges on high voltage transmission lines has been developed. This model is based on corona discharge distributed randomly in time and space. A stochastic model for the corona current induced by corona discharges on power lines is proposed. On the basis of the proposed corona current model, a rigorous analysis is presented to evaluate the radio interference (RI) field caused by corona discharges on a single conductor using the stochastic method.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.6
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• pp.1628-1645
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• 2015

This study was designed to analyze the present condition of the lifelong education field training program and to implement the need assessment of field training program based on the job model application. In order to achieve these goals, surveys were conducted through questionnaires and in-depth interviews targeting staffs of lifelong education institution in Busan area. The 115 subjects were analyzed by frequency distribution, the paired samples t-test, and the Borich's need analysis. The result showed that the field training program was poorly executed during the year of 2013 due to deficiency of certified practitioners and systematic guidelines. Also, the most highly demanded tasks were promoting change, networking, planning, developing programs and conducting surveys among various roles of lifelong educators. On the other hand, the need for the assisting and supporting programs were relatively low. Finally, this study concluded the need for developing systematic guidelines and for accrediting as a lifelong education field training institution nationwide. The results of this study would ultimately contribute to enhance the quality of lifelong education field training program.

• Journal of Environmental Science International
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• v.24 no.7
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• pp.865-874
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• 2015

This study was conducted to investigate the correlation between the distribution chart and input data of the predicted 3-second gust and damage cost, by using the forecast field and analysis field of Regional Data Assimilation Prediction System (RDAPS) as initial input data of Korea risk assessment model (RAM) developed in the preceding study. In this study the cases of typhoon Rusa which caused occurred great damage to the Korean peninsula was analyzed to assess the suitability of initial input data. As a result, this study has found out that the distribution chart from the forecast field and analysis field predicted from the point where the effect due to the typhoon began had similarity in both 3-second gust and damage cost with the course of time. As a result of examining the correlation, the 3-second gust had over 0.8, and it means that the forecast field and analysis field show similar results. This study has shown that utilizing the forecast field as initial input data of Korea RAM could suit the purpose of pre-disaster prevention.

• Wind and Structures
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• v.27 no.1
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• pp.29-40
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• 2018

To investigate the characteristics of the combined wind field produced by the natural wind field and the train-induced wind field on the bridge, the aerodynamic models of train and bridge are established and the overset mesh technology is applied to simulate the movement of high-speed train. Based on ten study cases with various crosswind velocities of 0~20 m/s and train speeds of 200~350 km/h, the distributions of combined wind velocities at monitoring points around the train and the pressure on the car-body surface are analyzed. Meanwhile, the difference between the train-induced wind fields calculated by static train model and moving train model is compared. The results show that under non-crosswind condition, the train-induced wind velocity increases with the train speed while decreases with the distance to the train. Under the crosswind, the combined wind velocity is mainly controlled by the crosswind, and slightly increases with the train speed. In the combined wind field, the peak pressure zone on the headstock surface moves from the nose area to the windward side with the increase of wind velocity. The moving train model ismore applicable in analyzing the train induced wind field.

• Journal of The Korean Society of Agricultural Engineers
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• v.60 no.5
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• pp.95-104
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• 2018

The purpose of this study was to explore the extent of difficulties experienced by facilitators in the rural field forum and to derive a theoretical model for improving the satisfaction of facilitators in the rural field forum. Based on grounded theory, qualitative analysis used data collected through individual in-depth interviews with 10 facilitators who are working at the rural field forum. This collected data was analyzed using the Nvivo 11 program. Using a derived theoretical model, the result of analyzing the difficulties experienced by facilitators in the rural field forum showed the core phenomenon identified as difficulties on-site the forum. There was a clarification of the issues regarding improvement of their labour conditions in order to solve the difficulties on-site the forum. The issues towards improving labour conditions were low allowance, equal assignment, guaranteed four major insurances and so on. The facilitators have been trying to activate the rural field forum by promoting their own capacity through the cooperation between colleagues, post training, seminars, and conferences.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.673-678
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• 2005

The objective of this paper is to develop the microorganism concentration simulation model for the health related effect analysis while farmers and water managers reuse the wastewater for agricultural irrigation. This model consists of the CE-QUAL-R1 model and the CREAMS-PADDY model. The CE-QUAL-R1 model is the 1-D numerical model to analyze the water quality of the reservoir and the CREAMS-PADDY model is modified from CREAMS model for considering the hydrologic cycles in paddy field. This model was applied to examine the application by the observed data from 2003 in Byoungjum study area. From this research, the average root mean square error (RMSE) for the simulated concentration during the calibration period was 0.51 MPN/100ml and correlation coefficient $(R^2)$ was 0.71. And the RMSE for the simulated concentration during the verification period was 0.46 MPN/100ml and $R^2$ was 0.73. This simulation results show that the coliform inflow concentrations by the wastewater irrigation wield great influence upon the temporal coliform concentrations in paddy field.

• Wind and Structures
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• v.20 no.3
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• pp.389-404
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• 2015

In this study, residential building damage states observed from a post-tornado damage survey in Joplin after a 2011 EF 5 tornado were used to reconstruct the near-surface wind field. It was based on well-studied relationships between Degrees of Damage (DOD) of building and wind speeds in the Enhanced Fujita (EF) scale. A total of 4,166 one- or two-family residences (FR12) located in the study area were selected and their DODs were recorded. Then, the wind speeds were estimated with the EF scale. The peak wind speed profile estimated from damage of buildings was used to fit a translating analytical vortex model. Agreement between simulated peak wind speeds and observed damages confirms the feasibility of using post-tornado damage surveys for reconstructing the near-surface wind field. In addition to peak wind speeds, the model can create the time history of wind speed and direction at any given point, offering opportunity to better understand tornado parameters and wind field structures. Future work could extend the method to tornadoes of different characteristics and therefore improve model's generalizability.