• Nuclear Engineering and Technology
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• v.52 no.9
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• pp.2017-2024
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• 2020

In this study, a fractional order proportional integral derivative (FOPID) controller is designed to create the reference power trajectory and to conquer the uncertainties and external disturbances. A fractional nonlinear model was utilized to describe the nuclear reactor dynamic behaviour considering thermal-hydraulic effects. The controller parameters were tuned using optimization method in Matlab/Simulink. The FOPID controller was simulated using Matlab/Simulink and the controller performance was evaluated for Hard variation of the reference power and compared with that of integer order a proportional integral derivative (IOPID) controller by two models of fractional neutron point kinetic (FNPK) and classical neutron point kinetic (CNPK). Also, the FOPID controller robustness was appraised against the external disturbance and uncertainties. Simulation results showed that the FOPID controller has the faster response of the control attempt signal and the smaller tracking error with respect to the IOPID in tracking the reference power trajectory. In addition, the results demonstrated the ability of FOPID controller in disturbance rejection and exhibited the good robustness of controller against uncertainty.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1127-1134
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• 2002

The present paper provides an engineering J estimation equation for surface cracked plates under combined bending and tension. The proposed equation is based on the reference stress approach, and the most relevant normalising loads to define the reference stress for accurate J estimations are given for surface cracked plates under combined bending and tension. Comparisons with J results from extensive 3-D FE analyses, covering a wide range of crack geometry, plate geometry and loading combination, show overall good agreement not only at the deepest point but also at arbitrary points along the crack front. for pure tension, agreement between the estimated J and the FE results is excellent, even at the surface point. On the other hand, for pure bending and combined bending and tension, the estimated J values become less accurate for locations close to the surface point. Thus the results in this paper will be useful to assess short-term fracture or low cycle fatigue of surface defects in plates under combined bending and tension.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.04a
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• pp.355-360
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• 2009

Nowadays, the condition of overcrowded cities has raised a question which is insufficient land in cities, and has gotten worse because of the influx of the population continuously. It has rapidly constructed a skyscraper increasingly that the solution to secure a living space against these overcrowded cities until 2000, but these are already positioning itself as one of the new type of residence. The necessity of skyscraper as facilities of residence inside cities has be available both a solution for overcrowded cities and a meaning for a symbol of its represented a landmark. However, constructing skyscrapers indiscreetly can not guarantee dweller's life environment, and it contains risks unless design and facilities criteria are provided. Now, a skyscraper as a new substitute constituting a living space in the future for overcrowded cities deals with a systematic correlation between a city and construction. Therefore the aim of this study were to indicate a method for improvement of dweller's life environment at skyscraper through establishing a point of reference to inculcate them for a sustainable skyscraper from now on.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.10
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• pp.1029-1036
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• 2011

An energy-efficient reference walking trajectory generation algorithm is suggested utilizing allowable ZMP (Zero-Moment-Point) region, which maxmizes the energy efficiency for cyclic gaits, based on three-dimensional LIPM (Linear Inverted Pendulum Model) for biped robots. As observed in natural human walking, variable ZMP manipulation is suggested, in which ZMP moves within the allowable region to reduce the joint stress (i.e., rapid acceleration and deceleration of body), and hence to reduce the consumed energy. In addition, opimization of footstep planning is conducted to decide the optimal step-length and body height for a given forward mean velocity to minimize a suitable energy performance - amount of energy required to carry a unit weight a unit distance. In this planning, in order to ensure physically realizable walking trajectory, we also considered geometrical constraints, ZMP stability condition, friction constraint, and yawing moment constraint. Simulations are performed with a 12-DOF 3D biped robot model to verify the effectiveness of the proposed method.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.350-353
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• 2009

The shielding enclosure is very essential device to test the electromagnetic wave power generated by various RF equipments. Some standards for the shielding enclosures were established to test them in right method. Generally, There are IEEE-STD-299 and MIL-STD-285 and NSA-65-6 of the method for measuring the effectiveness of shielding enclosures, the IEEE-STD-299 combined MIL-STD-285 and NSA-65-6 about the method for measuring shielding effectiveness(SE) about 1969 years, but, the measurement point of 299 proposal is many points(including shielding wall, seam, coner beat, shielding door, etc) and demand long time of measurement. To improve SE test method for shielding enclosures was studied and suggested to develop a proper test procedure. First, we measure reference level as frequency range and H/V polarization, secondly, measure leakage point, and finally, measure shield effect and calculate SE. Our method has a merit of the less measurement point than IEEE-STD-299, and shorten time than 299, and define representation SE of shielding enclosure effectively.

• Journal of the Korean Society for Railway
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• v.2 no.3
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• pp.1-8
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• 1999

In this paper, descibed was the derived algorithm for calculating contact point between wheel and rail and the developed method for rail modeling. The proposed methods use travelling distance to represent rail center line position vector and rail orientation with respect to Newtonian reference frame. The methods call be easily used ill multibody dynamic analysis. Two numerical examples are shown to verify the validity of the proposed methods.

• Journal of KIISE:Information Networking
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• v.37 no.6
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• pp.489-493
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• 2010

In an indoor localization method taking the lateration-based approach, the distance between a target and an AP (Anchor Point) is estimated using RSS (Received Signal Strength) measurements. Since the characteristics of a radio signal randomly vary in time and space, errors are unavoidable in distance estimation with measured RSS. Since the accuracy of distance estimation affects the localization accuracy of a lateration-based method, additional APs hearing a target have been used for localization in the literature. However, lots of experimental results show that the accuracy of a lateration-based method is improved by using carefully selected APs measuring the high quality RSSs which the distances estimated is close to the actual distances between nodes as reference APs, not using merely more APs. In this paper, we focus on selection method of reference AP and distance estimation method reflecting on environmental dynamics. We validate our method by implementing an indoor localization system and evaluating the accuracy of our method in the various experimental environments.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.17-25
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• 2001

This paper briefly describes the new engineering method, called the enhanced reference stress method, to estimate J (or $C^*$) for non-linear fracture mechanics analysis of defective components, recently proposed by authors. The proposed method offers significant advantages over existing methods in terms of its accuracy, simplicity and robustness. Examples of application of the proposed method to typical piping integrity problems such as through-wall cracked pipes under combined loading, and surface cracked pipes under internal pressure and bending are given. Excellent agreements between the FE J and $C^*$ results and those of the proposed method provide sufficient confidence in the use of the proposed method. One notable point is that the proposed method can be used to estimate J (or $C^*$) along the crack front of surface cracks. Moreover simplicity of the proposed method makes it easy to extend to more complex problems. Thus the proposed method is attractive to assess the significance of defects under practical situations.

• Spatial Information Research
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• v.15 no.3
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• pp.301-310
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• 2007

There are 21,000 National Surveying Control Points (NSCP) made of stone for precise surveying nationwide. NSCPs that provide location information are usually buried at the top of a mountain for view points that cannot be used by the public. Recently, according to the growing ubiquitous computing generation, location-based information has become very important and a service that can be easily accessed by the public is needed. In this research, a new type of reference point for a location information service is proposed. It is an Intelligent Reference Point (IRP) equipped with RFID tags and a two-dimensional bar-code system. The IRP system is composed of an electronic tag component, a tag identification component, and an IRP service component. We designed the IRP receiver identifying RFID tag and two-dimensional barcode was designed using a PDA, digital camera, and an RFID receiver. Also designed was IRP input data and input information. Furthermore, the operation software was developed in a PDA for identifying IRP and using IRP the service, and the IRP positioning method was developed using a GIS spatial analysis.

• Journal of Positioning, Navigation, and Timing
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• v.1 no.1
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• pp.45-49
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• 2012

The flight performance evaluation of navigation system is very significant because the reliability of navigation data directly affect the safety of aircraft. Especially, the high-level navigation system such as DGPS/INS, need more precise flight performance evaluation method. The performance analysis is evaluated by comparing between the navigation system in aircraft and reference trajectory which is more precise than navigation system in aircraft. In order to verify DGPS/INS performance of m-level, the GPS receiver, which is capable post-processed Carrier-phase Differential GPS(CDGPS) method of cm-level, have to be used as reference system. The DGPS/INS is estimated the Center of Gravity (CG) point of aircraft to offer precise performance while the reference system is output the position of GPS antenna which is mounted on the outside of aircraft. Therefore, in order to more precise performance evaluation, it needs to compensate the lever arm and coordinates transformation. This paper use quaternion and Direct Cosine Matrix(DCM) methods as coordinate transformation matrix in lever arm compensation of CDGPS reference trajectory. And it compares NED errors of DCM and quaternion transformation in lever arm of reference trajectory via DGPS/INS result.