• Geomechanics and Engineering
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• v.36 no.5
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• pp.489-509
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• 2024

Slope stability analysis and prediction are of critical importance to geotechnical engineers, given the severe consequences associated with slope failure. This research endeavors to forecast the factor of safety (FOS) for slopes through the implementation of six distinct ML techniques, including back propagation neural networks (BPNN), feed-forward neural networks (FFNN), Takagi-Sugeno fuzzy system (TSF), gene expression programming (GEP), and least-square support vector machine (Ls-SVM). 344 slope cases were analyzed, incorporating a variety of geometric and shear strength parameters measured through the PLAXIS software alongside several loss functions to assess the models' performance. The findings demonstrated that all models produced satisfactory results, with BPNN and GEP models proving to be the most precise, achieving an R² of 0.86 each and MAE and MAPE rates of 0.00012 and 0.00002 and 0.005 and 0.004, respectively. A Pearson correlation and residuals statistical analysis were carried out to examine the importance of each factor in the prediction, revealing that all considered geomechanical features are significantly relevant to slope stability. However, the parameters of friction angle and slope height were found to be the most and least significant, respectively. In addition, to aid in the FOS computation for engineering challenges, a graphical user interface (GUI) for the ML-based techniques was created.

• Geomechanics and Engineering
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• v.37 no.4
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• pp.307-321
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• 2024

This paper delves into the critical assessment of predicting sidewall displacement in underground caverns through the application of nine distinct machine learning techniques. The accurate prediction of sidewall displacement is essential for ensuring the structural safety and stability of underground caverns, which are prone to various geological challenges. The dataset utilized in this study comprises a total of 310 data points, each containing 13 relevant parameters extracted from 10 underground cavern projects located in Iran and other regions. To facilitate a comprehensive evaluation, the dataset is evenly divided into training and testing subset. The study employs a diverse array of machine learning models, including recurrent neural network, back-propagation neural network, K-nearest neighbors, normalized and ordinary radial basis function, support vector machine, weight estimation, feed-forward stepwise regression, and fuzzy inference system. These models are leveraged to develop predictive models that can accurately forecast sidewall displacement in underground caverns. The training phase involves utilizing 80% of the dataset (248 data points) to train the models, while the remaining 20% (62 data points) are used for testing and validation purposes. The findings of the study highlight the back-propagation neural network (BPNN) model as the most effective in providing accurate predictions. The BPNN model demonstrates a remarkably high correlation coefficient (R2 = 0.99) and a low error rate (RMSE = 4.27E-05), indicating its superior performance in predicting sidewall displacement in underground caverns. This research contributes valuable insights into the application of machine learning techniques for enhancing the safety and stability of underground structures.

• Ocean Systems Engineering
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• v.14 no.2
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• pp.171-210
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• 2024

This paper focuses on the rigorous and holistic fatigue analysis of mooring chains for a deep draft semi-submersible platform in the challenging environment of the central Gulf of Mexico (GoM). Known for severe hurricanes and strong loop/eddy currents, this region significantly impacts offshore structures and their mooring systems, necessitating robust designs capable of withstanding extreme wind, wave and current conditions. Wave scatter and current bin diagrams are utilized to assess the probabilistic distribution of waves and currents, crucial for calculating mooring chain fatigue. The study evaluates the effects of Vortex Induced Motion (VIM), Out-of-Plane-Bending (OPB), and In-Plane-Bending (IPB) on mooring fatigue, alongside extreme single events such as 100-year hurricanes and loop/eddy currents including ramp-up and ramp-down phases, to ensure resilient mooring design. A detailed case study of a deep draft semi-submersible platform with 16 semi-taut moorings in 2,500 meters of water depth in the central GoM provides insights into the relative contributions of wave scatter diagram, VIMs from current bin diagram, the combined stresses of OPB/IPB/TT and extreme single events. By comparing these factors, the study aims to enhance understanding and optimize mooring system design for safety, reliability, and cost-effectiveness in offshore operations within the central GoM. The paper addresses a research gap by proposing a holistic approach that integrates findings from various contributions to advance current practices in mooring design. It presents a comprehensive framework for fatigue analysis and design optimization of mooring systems in the central GoM, emphasizing the critical importance of considering environmental conditions, OPB/IPB moments, and extreme single events to ensure the safety and reliability of mooring systems for offshore platforms.

• The Korean Journal of Air & Space Law and Policy
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• v.23 no.2
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• pp.137-172
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• 2008

The earliest safety data programs, the FDR and CVR, were electronic reporting systems that generate data "automatically." The FDR program, originally instituted in 1958, had no publicly available restrictions for protections against sanctions by the FAA or an airline, although there are agreements and union contracts forbidding the use of FDR data for FAA enforcement actions. This FDR program still has the least formalized protections. With the advent of the CVR program in 1966, the precursor to the current FAR 91.25 was already in place, having been promulgated in 1964. It stated that the FAA would not use CVR data for enforcement actions. In 1982, Congress began restricting the disclosure of the CVR tape and transcripts. Congress added further clarification of the availability of discovery in civil litigation in 1994. Thus, the CVR data have more definitive protections in place than do FDR data. The ASRS was the first non-automatic reporting system; and built into its original design in 1975 was a promise of limited protection from enforcement sanctions. That promise was further codified in an FAR in 1979. As with the CVR, from its inception, the ASRS had some protections built in for the person who might have had a safety problem. However, the program did not (and to this day does not) explicitly deal with issues of use by airlines, litigants, or the public media, although it appears that airlines will either take a non-punitive stance if an ASRS report is filed, or the airline may ignore the fact that it has been filed at all. The FAA worked with several U.S. airlines in the early 1990s on developing ASAP programs, and the FAA issued an Advisory Circular about the program in 1997. From its inception, the ASAP program contained some FAA enforcement protections and company discipline protections, although some protection against litigation disclosure and public disclosure was not added until 2003, when FAA Order 8000.82 was promulgated, placing the program under the protections of FAR 193, which had been added in 2001. The FOQA program, when it was first instituted through a demonstration program in 1995, did not contain protections against sanctions. Now, however, the FAA cannot take enforcement action based on FOQA safety data, and an airline is limited to "corrective action" under the program. Union contracts can exclude FOQA from the realm of disciplinary action, although airline practice may be for airlines to require retraining if there is no contract in place forbidding it. The data is protected against disclosure for litigation and public media purposes by FAA Order 8000.81, issued in 2003, which placed FOQA under the protections of FAR 193. The figure on the next page shows when each program began, and when each statute, regulation, or order became effective for that program.

• Journal of The Korean Digital Architecture Interior Association
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• v.11 no.1
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• pp.5-13
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• 2011

This research proposed the space planing methode and diagrams of restaurant kitchens to improve hygiene by analyzing the related contents collected from books and researches in interior design and HACCP (Hazard Analysis and Critical Control Point). HACCP is an effective and scientific hygiene system for food safety in order to prevent cross-contamination from food hazards. Based on the analyses, improvement of food production environments like restaurant kitchens is necessary for food hygiene. The space planing methode of restaurant kitchens to improve hygiene are followings: The circulation planing is that the direction of movement of the food, workers, waste, and dishes should be fractionated and managed for cross-contamination prevention. The space separation planing is that the spaces in the kitchen should be classified and divided into contaminated area and non-contaminated and clean area depending on the degree of cleanliness. The zoning is space arrangement with feed-back process to check the possible points of cross-contamination and correct space arrangement until the possibility of cross-contamination disappear in kitchen. However, if cross-contamination is unavoidable in some points in restaurant kitchens, hygiene facilities such as washing rooms, pass rooms, and double doors with air-shower should be located in order to remove contamination.

• Journal of ILASS-Korea
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• v.20 no.2
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• pp.107-113
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• 2015

To date, the demand for Combined Cycle Power Plant (CCPP) has been continuously increased to overcome the problem of air pollution and lack of energy. In particular, the underground CCPP is exposed to substantial fire and explosion risks induced by gas leakage. The present study conducted numerical simulations to examine the fire behavior and gas leakage characteristics for a restricted region including gas turbine and other components used in a typical CCPP system. The commercial code of FLUENT V.14 was used for simulation. From the results, it was found that flammable limit distribution of leakage gas affects fire behavior. Especially, the flame is propagated in an instant in restricted region with LNG gas. In addition, consequence analysis factors such as critical temperature and radiation heat flux are introduced. These results would be useful in making the safety guidelines for the underground CCPP.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.1
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• pp.69-78
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• 2017

As the smartphone-based devices are diffused and developed rapidly, they provide the convenience to the users. The abovementioned sentence technologies are being used not only in the existing sensor and wireless network technology but also in the application services of the diverse fields application services such as smart appliance, smart car, smart health care, etc. and the new fusion paradigm from the industry is presented by undertaking the researches in diverse area by the enterprises and research institutions. However, the smart environment exposes its weaknesses in the mobile terminal area, existing wireless network and IT security area. In addition, due to new and variant ways of attack, not only the critical information are disclosed However also the financial damages occur. This paper proposed the protocol to perform the smartphone-based safe device monitoring and safe communication. The proposed protocol designed the management procedure of registration, identification, communication protocol and device update management protocol and the safety against the attack techniques such as the an-in-the-middle-attack, impersonation attack, credential threat, information leaks and privacy invasion was analyzed. It was observed that the proposed protocol showed the performance improved by approximately 52% in the communication process than the existing system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1450-1455
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• 2009

Assumed that an IPTV camera system is to be used as an ad-hoc sensor for the surveillance and diagnostics of safety-critical equipments installed in the in-containment building of the nuclear power plant, an major problem is the presence of high dose-rate gamma irradiation fields inside the one. In order to uses an IPTV camera in such intense gamma radiation environment of the in-containment building, the radiation-weakened devices including a CCD imaging sensor, FPGA, ASIC and microprocessors are to be properly shielded from high dose-rate gamma radiation using the high-density material, lead or tungsten. But the passive elements such as mirror, lens and window, which are placed in the optical path of the CCD imaging sensor, are exposed to a high dose-rate gamma ray source directly. So, the gamma-ray irradiation characteristics of the passive elements, is needed to test. A CCD camera lens, made of glass material, have been gamma irradiated at the dose rate of 4.2 kGy/h during an hour up to a total dose of 4 kGy. The radiation induced color-center in the glass lens is observed. The degradation performance of the gamma irradiated lens is explained using an color component analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10C
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• pp.749-757
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• 2008

In this paper, we propose an authentication scheme for EVPT (Emergency Vehicle Priority Transit) service in Vehiclar Ad-hoc Networks (VANET) enable a variety of vehicle comfort services, traffic management applications, and infotainment services. These are the basis for a new generation of preventive and active safety functions. By intelligently controlling signalling at intersections, providing additional information to the driver and warning the driver in critical situations. we therefore focus on vehicle-to-infrastructure communication for the authentication between emergency vehicles and traffic lights system. This authentication process should identify the vehicle, and provide privacy protection.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.220.1-220.1
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• 2011

In recent years, the importance of Carbon Capture and Storage (hereafter CCS) is growing bigger and bigger. The development and commercialization of CCS technology are concerned for reducing carbon dioxide($CO_2$) emissions. For the most studies, the technology of $CO_2$ storage is known as the geological storage, ocean sequestration, mineral carbonation, industrial utilization, and so on. The geological storage is adjudged the most reasonable technology from economic and environmental aspects. Generally, the $CO_2$ geological storage is comprised of compression - transportation - drilling/injection - storage/management process. The critical problem is a leakage of $CO_2$ in all process. For resolving a leakage problem, it is necessary to predict and build a monitoring system. Those systems are proved safety of a leakage and received positive social perceptions of $CO_2$ geological storage. For those reasons, a risk assessment of $CO_2$ geological storage is required. A risk assessment is an estimated process of the possible effects when spilling $CO_2$. Although numerous studies of risk assessment have studied, it is incomplete to evaluate a risk and disaster quantitatively. The risk assessment will be developed for domestic application and safe $CO_2$ geological storage considering characteristics of Korea.