• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.4
• /
• pp.775-787
• /
• 2014

Availabilities of subsea Blowout Preventers (BOP) in the Gulf of Mexico Outer Continental Shelf (GoM OCS) is investigated using a Markov method. An updated ${\beta}$ factor model by SINTEF is used for common-cause failures in multiple redundant systems. Coefficient values of failure rates for the Markov model are derived using the ${\beta}$ factor model of the PDS (reliability of computer-based safety systems, Norwegian acronym) method. The blind shear ram preventer system of the subsea BOP components considers a demand rate to reflect reality more. Markov models considering the demand rate for one or two components are introduced. Two data sets are compared at the GoM OCS. The results show that three or four pipe ram preventers give similar availabilities, but redundant blind shear ram preventers or annular preventers enhance the availability of the subsea BOP. Also control systems (PODs) and connectors are contributable components to improve the availability of the subsea BOPs based on sensitivity analysis.

• International Journal of Railway
• /
• v.7 no.2
• /
• pp.35-39
• /
• 2014

Urban subways are one of the main parts of urban transportation networks in every city that always requires much attention in order to improve its efficiency in aspects of safety, reliability speed and costs. As the viewpoint of costs, an accurate design, especially design of vertical alignment, can have a dominant role to reduce the costs of urban railway projects. This paper seeks to evaluate the advantages and disadvantages of designing chain vertical alignment for urban subways in compare to flat vertical alignment. To achieve this goal, line A of Qom subway in Iran was selected as a case study in this research. Five parameters considered in the technical-economical evaluation: (1) energy consumption, (2) rolling stock, (3) operation, (4) civil works and geotechnical and (5) hydrological, drainage and pumping. According to the results, a power saving of about 40% have been estimated in the chain vertical alignment for the train without regenerative braking in compare with the flat vertical alignment, although the power saving was calculated less than 10% for the train with regenerative braking. Finally it was found that due to the modern rolling stock technology, the chain vertical alignment represents fewer advantages in compare to the past years.

• Journal of Power System Engineering
• /
• v.18 no.2
• /
• pp.57-61
• /
• 2014

Due to the changes of marine transportation industry, it requires ship in larger scale and high speed. In order to operate efficiently, the engine should be work in high power and high horse power. The increase of the number of the propeller blades and the pitch of the screw and the weight, vibration of shafting problems occurs. To evaluate the safety of the system through analyzing the dynamic characteristics propulsion shafting system, was used to prove or to verify the Lalanne & Ferraris model validation.. It indicates that the Program through Campbell diagram and Critical speed map, Root rocus map, to ensure the reliability of the experimental model.

• Computational Structural Engineering
• /
• v.2 no.2
• /
• pp.93-99
• /
• 1989

Since 1960's, structural engineers have recognized that the inherent random nature of loadings and materials as well as the imperfect structural analysis may be important factors in the structural safety evaluation. Based on the successful developments of the reliability-based structural analysis and design, the design criteria of the standards are recently developed(or modified) in the light of the probabilistic concepts. To develop the probability - based criteria for the domestic buildings, the probabilistic characteristic of loadings acting on structures should be defined first. In this study, therefore, live load data on apartment buildings have been collected and analyzed in systematic manner, and their probabilistic characteristics have been studied. Based on the results, the lifetime extreme values are computed and compared with current design loads. More rational design loads are suggested, which are more consistent in the probabilistic concepts.

• Proceedings of the KSR Conference
• /
• 2005.11a
• /
• pp.412-417
• /
• 2005

To ensure the safety of the tunnelling without the loss of economy, the tunnel seismic profiling(TSP) method for the prediction ahead of tunnel face, begins to be used routinely in these days. TSP method does not interfere the tunnelling works while the horizontal drilling does, and its prediction length is longer than that of the drilling. Yet the most frequently adopted technique of TSP in Korea is the multi-shot and 2 receiver array using in-hole receivers, even though this array requires as many as 26 drill-holes for receiver installation and ballasting, which results in 3-6 hours of suspension in excavation work. In this paper, multi-receiver and lesser shot array using side-wall attached 3 component geophones is to be described to prove the efficiency in terms of the survey time as well as the reliability of the method by comparison of the predicted weak points and the face mapping results. The predictions mostly agreed with the real fractures or joint developed zones which have been confirmed during the excavation. It also has been found that TSP method can be effectively applied to perform draining ground water ahead of tunnel face by imaging the geologic discontinuities.

• Journal of Institute of Control, Robotics and Systems
• /
• v.9 no.7
• /
• pp.498-506
• /
• 2003

A computer vision system applied to an intelligent safety vehicle has been required to be worked on a small sized real time special purposed hardware not on a general purposed computer. In addition, the system should have a high reliability even under the adverse road traffic environment. This paper presents a design and an implementation of an onboard hardware system taking into account for high speed image processing to analyze a road traffic scene. The system is mainly composed of two parts: an early processing module of FPGA and a postprocessing module of DSP. The early processing module is designed to extract several image primitives such as the intensity of a gray level image and edge attributes in a real-time Especially, the module is optimized for the Sobel edge operation. The postprocessing module of DSP utilizes the image features from the early processing module for making image understanding or image analysis of a road traffic scene. The performance of the proposed system is evaluated by an experiment of a lane-related information extraction. The experiment shows the successful results of image processing speed of twenty-five frames of 320$\times$240 pixels per second.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.13 no.6
• /
• pp.56-62
• /
• 2005

The fatigue analysis and lifetime evaluation are very important in design procedure to assure the safety and reliability of the rubber components. Fatigue lifetime prediction methodology of the rubber component was proposed by incorporating the finite element analysis and fatigue damage parameter from fatigue test. Finite element analysis of 3D dumbbell specimen and rubber component were performed based on a hyper-elastic material model determined from material test. The Green-Lagrange strain at the critical location determined from the FEM was used for evaluating the fatigue damaged parameter of the natural rubber. Fatigue life of the rubber component are predicted by using the fatigue damage parameter at the critical location. Predicted fatigue lifes of the rubber component agreed fairly well the experimental fatigue lives.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.11
• /
• pp.1457-1463
• /
• 1999

This paper develops an real-time expert system for the electronic interlocking system. it obtains the higher safety by determining the railway interlocking strategy in order to prevent trains from colliding, and derailing in the viewpoint of veteran expert, considering the situation of station in real-time. The expert system determines the real-time interlocking strategy by confirming the interlocking relationships among signal facilities based on the interlocking knowledge base from input information such as signal, points, and it is implemented as the rule-based system in order to represented accurately and effectively the interlocking relationships. Especially in case of emergency the function which determines the rational route coordinating with IIKBAG on the workstation is designed in order to minimize the spreading effect. It is implemented in C computer language for the purpose of the implementation of the inference engine using the dynamic memory allocation technique, the build and interface of the station structure database. And, the validity of the built expert system is proved by simulating the diversity cases which may occur in the real system for the typical station model.

• Journal of Electrical Engineering and Technology
• /
• v.7 no.6
• /
• pp.971-976
• /
• 2012

A 150 kJ compact capacitive pulsed power system (CCPPS) capable of delivering electrical energy into an electrothermal chemical (ETC) gun on a vehicle has been studied. The CCPPS provides pulsed electrical energy into a capillary plasma injector which generates plasma of tens of thousands $^{\circ}K$ in temperature and has a nonlinear resistance depending on the current. The design requirements of the CCPPS are as follows: the maximum power of 250 MW, the pulse width of about 0.6 ms, the volume of no more than 0.5 cubic meter, the efficiency of energy transfer over 80 % and the repetition rate of 4~5 times per minute. The constructed CCPPS is composed of four 37.5 kJ capacitor bank modules in parallel to make a trapezoid pulse shape and to satisfy the design requirements. Each module is designed to achieve high reliability, safety, efficiency and energy density to endure severe operating conditions. The results of the performance test on the CCPPS using a 120 mm ETC gun are described.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.5
• /
• pp.477-484
• /
• 2013

This paper proposes a novel switching method of active clamp snubber for efficiency improvement of PV module integrated converter(MIC) system. Recently, MIC solar system is researched about the efficiency and safety. PV MIC system is used active clamp method of snubber circuit for the price and reliability of the system. But active clamp snubber circuit has the disadvantage that system efficiency is decreased for switch operating time because of heat loss of resonant between snubber capacitor and leakage inductance. To solve this problem, this paper proposes a novel switching method of the active clamp. The proposed method is a technique to reduce power consumption by reducing the resonance of the snubber switch operation time and through simulations and experiments proved the validity.