• Journal of KIISE:Software and Applications
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• v.32 no.2
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• pp.108-118
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• 2005

The software of the nuclear power plant digital control system is a safety-critical system where many techniques must be applied to it in order to preserve safety in the whole system. Formal specifications especially allow the system to be clearly and completely specified in the early requirements specification phase, therefore making it a trusted method for increasing safety. In this paper, we discuss a systematic method, which generates PLC-based FBD programs from the requirements specification using NuSCR, a formal requirements specification method. This FBD programs takes an important position in design specification. The proposed method can reduce the possible errors occur in the manual design specification, and the software development cost and time. To investigate the usefulness of our proposed method, we introduce the fixed set-point rising trip example, a trip logic of BP in DPPS RPS, which is presently being developed at KNICS.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.6
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• pp.490-500
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• 2000

A new technique for the source location of acoustic emission (AE) in plates whose thichness are close to or thinner than the wavelength has been studied by introducing wavelet transform de-noising technique. The detected AE signals were pre-processed using wavelet transform to be decomposed into the low-frequency, high-amplitude flexural components and the high-frequency, low-amplitude extensional components. If the wavelet transform de-noising was employed, we could successfully filter out the extensional wave component, one of the critical errors of source location in plates by arrival time difference method. The accuracy of source location appeared to be significantly improved and independent of the setting of gain and threshold, plate thickness, sensor-to-sensor distance, and the relative position of source to sensors. Since the method utilizes the flexural component of relatively high amplitude, it could be applied to very large, thin-walled structures in practice.

• Journal of Drive and Control
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• v.11 no.2
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• pp.30-35
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• 2014

The pumps of electro-hydrostatic actuators operate most frequently in boundary lubrication speed range, as they compensate for the position control errors as a control element. When conventional swash plate type piston pumps are applied to electro-hydrostatic actuators, the frictional power losses as well as the wear rate of sliding components, such as piston shoes can increase drastically under the boundary friction condition. In this paper, the power losses of the piston shoes were investigated which were engendered by a frictional solid-to-solid contact and leakage flow rate of their hydrostatic bearing. In order to reduce them, DLC-coating was applied to the swash plate and the ball joint of pistons along with its effects were demonstrated. In addition, it was also shown that the wear rate of the piston shoes could be markedly reduced using the DLC-coated swash plate.

• Journal of the Korea Society of Computer and Information
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• v.11 no.3
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• pp.1-10
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• 2006

It is widely accepted that the coverage with high user densities can only be achieved with small cell such as micro- and pico-cell. The smaller cell size causes frequent handovers between cells and a decrease in the permissible handover Processing delay. This may result in the handover failure. in addition to the loss of some Packets during the handover. In these cases. re-transmission is needed in order to compensate errors, which triggers a rapid degradation of throughput. In this paper, we propose a new handover scheme in the next generation mobile communication systems, in which the handover setup process is done in advance before a handover request by predicting the handover cell based on mobile terminal's current position and moving direction. Simulation is focused on the handover failure rate and Packet loss rate. The simulation results show that our proposed method provides a better performance than the conventional method.

• Journal of Radiation Protection and Research
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• v.44 no.1
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• pp.43-52
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• 2019

Background: The mid-term performance of clinical linear accelerator (LINAC) during volumetric modulated arc therapy (VMAT) treatment period is not performed in clinical practice and usually replaced with one-time plan quality assurance (QA). In this research we aim to monitor daily reproducibility of VMAT delivery from tracking individual leaf movement error and dosimetric error to evaluate the mid-term quality of the machine used. Materials and Methods: First, multileaf collimator (MLC) information was imported into MATLAB program to determine which of the MLC leaves in the leaf bank had the maximum RMS position error (maxRMS). We estimated where the maximum positional errors (maxPE) of the chosen leaf occur along its path length and tracked its daily variations over the entire treatment period. Secondly, picture information of dosimetric error from portal dosimetry was imported into MATLAB where representative high gamma index region (HGR) was determined as HGR with length of > 1 cm and their centers were daily tracked. Results and Discussion: The maxPEs in the brain and tongue cases were distributed broader than in other cases, but all data were found located within ${\pm}0.5mm$. From first day to last day all of five cases show the similar visual pattern of HGRs and Centers of the longest HGRs remained within ${\pm}1mm$ of that in first day. These findings prove excellent mid-term performance of the LINAC used in VMAT treatments over a full course of treatment. Conclusion: Tracking the daily location changes of leaf movement and dosimetric error can be a good indicator of predicting the daily quality like stability and reproducibility of beam delivering in VMAT treatment.

• Journal of the Korea Society of Computer and Information
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• v.24 no.5
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• pp.93-102
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• 2019

The nation's fraternity and elite players who have built up a global bicycle infrastructure often find it to be a problem with the bicycle's speed and speed reduction, pain in knees and hip joints, or even with the bike itself, or with the bike's own physical defects or a riding posture. However, we found that most cases of cleat adjustment errors were likely to be true. Accurate adjustment of the cleats is the most important of the entire fitting process and can be the basis for improving the ability of the bicycle rider and preventing injury. Therefore, the study was intended to give a prior study of bicycle fitting, which can improve bicycle efficiency and prevent injury when riding bicycle, and specific ways of adjusting bicycle shoe cleats, and the following results were obtained. First, the cleat characteristics of Shimano, LOOK and Speedplay, which are currently used in public, and the characteristics during the cleat adjustment process, were derived. In addition, the structure and characteristics of dedicated shoes using cleats and the method of using pedalling by the structure of shoes after adjusting the cleats were derived. Second, the position of the shoe and its relationship with torque in pedalling was discussed, and the method of adjusting front and back of cleats was derived. Third, leg length, ASIS, Q-Angle and Q-factor etc. were analyzed and the method of setting and adjusting cleat left and right values were derived. Fourth, the relationship between walking angle and cleat rotation was analyzed, the method was derived, and the torque size and angle behind the cleat adjustment were compared and analyzed using the spinner to indicate the torque and the effective mean torque angle after the cleat adjustment.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.43 no.4
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• pp.190-197
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• 2020

Recently there was an incident that military radars, coastal CCTVs and other surveillance equipment captured a small rubber boat smuggling a group of illegal immigrants into South Korea, but guards on duty failed to notice it until after they reached the shore and fled. After that, the detection of such vessels before it reach to the Korean shore has emerged as an important issue to be solved. In the fields of marine navigation, Automatic Identification System (AIS) is widely equipped in vessels, and the vessels incessantly transmits its position information. In this paper, we propose a method of automatically identifying abnormally behaving vessels with AIS using convolutional autoencoder (CAE). Vessel anomaly detection can be referred to as the process of detecting its trajectory that significantly deviated from the majority of the trajectories. In this method, the normal vessel trajectory is gridded as an image, and CAE are trained with images from historical normal vessel trajectories to reconstruct the input image. Features of normal trajectories are captured into weights in CAE. As a result, images of the trajectories of abnormal behaving vessels are poorly reconstructed and end up with large reconstruction errors. We show how correctly the model detects simulated abnormal trajectories shifted a few pixel from normal trajectories. Since the proposed model identifies abnormally behaving ships using actual AIS data, it is expected to contribute to the strengthening of security level when it is applied to various maritime surveillance systems.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.11
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• pp.69-78
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• 2019

The purpose of this study is to propose a modeling methodology through the exchange of coordinate data of a three-dimensional custom curtain wall panel between Rhino and Revit, and to examine the validity of the model implemented in the drawing. Although the modeling means and method are different, a fundamental principle is that all three-dimensional modeling begins by defining the position of the points, the most primitive element of geometry, in the XYZ coordinate space. For the BIM modeling methodology proposal based on this geometry basic concept, the functions and characteristics associated with the points of Rhino and Revit programs are identified, and then BIM implementation process model is organized and systemized through the setting of the interoperability process algorithm. The BIM implementation process model proposed in this study is (1) Modeling and panelizing surface into individual panels using Rhino and Grasshopper; (2) Extraction of vertex coordinate data from individual panels and create CSV file; (3) Curtain wall modeling through Adaptive Component Family in Revit and (4) Automatic creation of Revit curtain wall panels through API. The proposed process model is expected to help reduce design errors and improve component and construction quality by automatically converting general elements into architectural meaningful information, automating a set of processes that build them into BIM data, and enabling consistent and integrated design management.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.2
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• pp.320-326
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• 2021

AVTE(Air Vehicle Test Equipment) is an equipment to inspect and check the status of on-board aircraft LRUs(Line Replacement Units) before and after flight for performing successful UAV(Unmanned Aerial Vehicle) missions. This paper suggests utilization of the AVTE as an operation support-equipment by implementing several critical functions for UAV-operation on the AVTE. The AVTE easily sets initialization(default) data and compensates for the installation and position errors of the LRUs which provide critical mission data and situation image with pilots without additional individual operation support-equipment. Major fault list and situation image data could be downloaded after flight using the AVTE in the event of UAV emergency situation or unusual occurrence on duty as well. We anticipate the suggested operational approach of the AVTE could dramatically reduce the cost and man power for design and manufacture of additional operation support equipment and effectively diminish workload of the operator.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.2
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• pp.71-81
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• 2022

In order for electro-optical tracking system (EOTS) to have accurate target coordinate, accurate navigation results are required. If an integrated navigation system is configured using an inertial measurement unit (IMU) of EOTS and the vehicle's navigation results, navigation results with high rate can be obtained. Due to the time-delay of the navigation results of the vehicle in the EOTS and scale factor errors of the EOTS IMU in high-speed and high dynamic operation of the vehicle, it is much more difficult to have accurate navigation results. In this paper, an integrated navigation system of EOTS which compensates time-delay and scale factor error is proposed. The proposed integrated navigation system consists of vehicle's navigation system which provides time-delayed navigation results, an EOTS IMU, an inertial navigation system (INS), an augmented Kalman filter and integration Kalman filter. The augmented Kalman filter outputs navigation results, in which the time-delay of the vehicle's navigation results is compensated. The integration Kalman filter estimates position, velocity, attitude error of the EOTS INS and accelerometer bias, accelerometer scale factor error, gyro bias and gyro scale factor error from the difference between the output of the augmented Kalman filter and the navigation result of the EOTS INS. In order to check performance of the proposed integrated navigation system, simulations for output data of a measurement generator and land vehicle experiments were performed. The performance evaluation results show that the proposed integrated navigation system provides more accurate navigation results.