• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.5
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• pp.551-560
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• 2020

Recently, the offshore wind power generator market is expected to grow significantly because of increased energy demand, reduced dependence on fossil fuel-based power generation, and environmental regulations. Consequently, wind power generation is increasing worldwide, and several attempts have been made to utilize offshore wind power. Norway's Petroleum Safety Authority (PSA) requires a leg-structure design with a collision energy of 35 MJ owing to the event of a collision under operation conditions. In this study, the results of the numerical analysis of a wind turbine installation vessel subjected to ship collision were set such that the maximum collision energy that the leg could sustain was calculated and compared with the PSA requirements. The current leg design plan does not satisfy the required value of 35 MJ, and it is necessary to increase the section modulus by more than 200 % to satisfy the regulations, which is unfeasible in realistic leg design. Therefore, a collision energy standard based on a reasonable collision scenario should be established.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.1-9
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• 2016

This paper was studied in two ways with respect to the information received from the video signal separation technique of PPI Scop radar device. The proposed technique consists in generating an image signal through the video signal separation and synthesis, symbol generation, the residual image signal generation process. This technology can greatly improve the operating convenience with improved ease of discrimination, screen readability for the operator in analyzing radar information. The first proposed method was constructed for high-speed FPGA-based information processing systems for high speed operation stability of the system. The second proposed method was implemented intelligent algorithms and a software algorithm function curve associated resources.This was required to meet the constraints on the radar information, analysis system. Existing radar systems have not the frame data analysis unit image. However, this study was designed to image data stored in the frame-by-frame analysis of radar images with express information MPEG4 video. Key research content is to highlight the key observations expresses the target, the object-specific monitoring information to the positive image processing algorithm and the function curve delays. For high-definition video, high-speed to implement data analysis and expressing a variety of information was applied to the ARM Processor Support in Pro ASIC3.

• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.34-38
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• 2009

This paper is related with optimum burst structure design for high efficient TDMA satellite return link transmission. In general, some typical burst structure for data transmission is composed of a pair of preamble and traffic data in the DVB-RCS (Digital Video Broadcasting. Return Channel via Satellite) and IPOS (IP over Satellite) standard. This structure has some difficulties to increase spectral efficiency that it requires a large of preamble length, high SNR environment, or receiver complexity. To cope with them, burst structure with distributed pilot symbol can be used to alleviate the residual frequency offset effect by calculating accurate frequency offset than conventional one. In particular, we investigate some relevant to proposed distributed pilot structure, previously and analyze their strong points/drawbacks in terms of synchronization to draw the most appropriate one.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.11
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• pp.874-882
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• 2003

The condition assessment of engineering systems has increased in importance because the manpower needed to operate and supervise various plants has been reduced. Especially, induction motors are at the core of most engineering processes, and there is an indispensable need to monitor their health and performance. So detection and diagnosis of motor faults is a base to improve efficiency of the industrial plant. In this paper, a model-based fault detection system is developed for induction motors, using steady state vibration signals. Early various fault detection systems using vibration signals are a trivial method and those methods are prone to have missed fault or false alarms. The suggested motor fault detection system was developed using a model-based reference value. The stationary signal had been extracted from the non-stationary signal using a data segmentation method. The signal processing method applied in this research is FFT. A reference model with spectra signal is developed and then the residuals of the vibration signal are generated. The ratio of RMS values of vibration residuals is proposed as a fault indicator for detecting faults. The developed fault detection system is tested on 800 hp motor and it is shown to be effective for detecting faults in the air-gap eccentricities and broken rotor bars. The suggested system is shown to be effective for reducing missed faults and false alarms. Moreover, the suggested system has advantages in the automation of fault detection algorithms in a random signal system, and the reference model is not complicated.

• Journal of Navigation and Port Research
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• v.40 no.5
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• pp.241-247
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• 2016

The tracking filter plays a key role in the accurate estimation and prediction of maneuvering a vessel's position and velocity when attempting to enhance safety by avoiding collision. Therefore, in order to achieve accurate estimation and prediction, many oceangoing vessels are equipped with the Automatic Radar Plotting Aid (ARPA) system. However, the accuracy of prediction depends on the tracking filter's ability to reduce noise and maintain a stable transient response. The purpose of this paper is to derive the optimal values of the gain parameters used in tracking a High Dynamic Warship. The algorithm employs a ${\alpha}-{\beta}-{\gamma}$ filter to provide accurate estimates and updates of the state variables, that is, positions, velocity and acceleration of the high dynamic warship based on previously observed values. In this study, the filtering coefficients ${\alpha}$, ${\beta}$ and ${\gamma}$ are determined from set values of the damping parameter, ${\xi}$. Optimization of the damping parameter, ${\xi}$, is achieved experimentally by plotting the residual error against different values of the damping parameter to determine the least value of the damping parameter that results in the optimum smoothing coefficients leading to a reduction in the noise corruption effect. Further investigation of the performance of the filter indicates that optimal smoothing coefficients depend on the initial and average velocity of the target.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.1
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• pp.93-99
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• 2005

Up to date, the life extension of industrial plant structures has been strongly required in the field of iron-manufacturing company, atomic or power generation company and so on. Fault monitoring, maintenance of aging structural components, safety assessment and residual life prediction may be recognized as typical and/or practical methods in terms of life extension methods. Based on the construction of damage scenario, precise analysis method and development of the risk or reliability assessment, a number of studies have been carried out in this viewpoint. In conjunction with the finite element analysis technique, a practical procedure for the safety assessment of iron-manufacturing plant structures was developed in this paper with a particular interest in furnace. By virtue of the detailed finite element analyses for blust furnace under an operational condition, the validity of the proposed procedure for safety assessment was presented.

• Journal of the Korean Ceramic Society
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• v.39 no.10
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• pp.948-954
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• 2002

Porous reaction bonded SiC with high fracture strength was developed using Si melt infiltration method for use of the support layer in high temperature gas filter that is essential to develop the next generation power system such as integrated gasification combined cycle system. The porosity and pore size of porous RBSC developed in this study were in the range of 32∼36% and 37∼90 ${\mu}m$ respectively and the maximum fracture strength of porous RBSC fabricated was 120 MPa. The fracture strength and thermal shock resistance of porous RBSC fabricated by Si melt infiltration were much improved compared to those of commercially available porous clay bonded SiC due to the formation of the strong SiC/Si interface between SiC particles. The characteristics of pore structure of porous RBSC was varied depending on the amounts of residual Si as Well as the size of SiC particle used in green body.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.42-51
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• 2013

In this study, oil palm biomass such as empty fruit bunch (EFB) and palm kernel shell (PKS) was used as raw materials for making pellets. Hardwood sawdusts were also mixed with EFB and PKS for making pellets. For improving a bad forming behavior in a pelletizer, 1 to 3 per cent of corn starch based on oven-dried weight biomass was added. The starch contributed to the decrease of dust generation in addition to the improvement of forming capability during pellet forming. Heating values of every pellets made of EFB and PKS were higher than 4,300 kcal/kg for the first grade pellet, irrespective of addition of sawdusts. However, the pellets made of EFB and PKS had ash contents over 3 per cent, which made it impossible to be applied for home use. Instead, they could be applied for industrial use. For studying their combustion characteristics, the pellets from the mixtures of EFB, PKS and sawdusts were analyzed using thermal gravimetric analyzer (TGA). From the TGA results, thermal decomposition of EFB and PKS occurred following three including endothermic reaction and dehydration, devolatilization of the major chemical components, and finally combustion of residual lignin and char.

• Journal of Energy Engineering
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• v.12 no.1
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• pp.1-10
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• 2003

Pressurized fluidized bed combustion unit is operated at pressures of 1~1.5 MPa with combustion temperatures of 850~87$0^{\circ}C$. The pressurized coal combustion system heats steam, in conventional heat transfer tubing, and produces a hot gas supplied to a gas turbine. Gas cleaning is a vital aspect of the system, as is the ability of the turbine to cope with some residual solids. The need to pressurize the feed coal, limestone and combustion air, and to depressurize the flue gases and the ash removal system introduces some significant operating complications. The proportion of power coming from the steam : gas turbines is approximately 80:20%. Pressurized fluidized bed combustion and generation by the combined cycle route involves unique control considerations, as the combustor and gas turbine have to be properly matched through the whole operating range. The gas turbines are rather special, in that the maximum gas temperature available from the FBC is limited by ash fusion characteristics. As no ash softening should take place, the maximum gas temperature is around 90$0^{\circ}C$. As a result a high pressure ratio gas turbine with compression intercooling is used. This is to offset the effects of the relatively low temperature at the turbine inlet.

• Fire Science and Engineering
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• v.19 no.2 s.58
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• pp.63-68
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• 2005

In this study, the arc dispersion properties were analyzed according to switching of high sensitive type Residual Current Protective Device(RCD) contacts. Arc dispersion and ignition process was taken by high speed imaging system(HSIS). In this experiment, electric lamps(60 W) and heaters(950 W) were connected in parallel as loads. In case of normal RCD, it took about 2.3(ms) from the generation of arc to the extinction of uc. When arc was dispersed in normal RCD, it did not ignite cotton. Whereas, in case of RCD deteriorated by NaCl solution, the range of arc dispersion was wider and the arc lasted for 3.3[ms] more compared to normal RCD. And the arc ignited cotton. In order to prevent accidents caused by RCD, we should be careful of environmental factors, such as dust and humidity, and the parts of RCD should be used as incombustible materials.