Jo Aug 14, 2026
Accurate positioning of nodes distributed in wireless sensor networks is very important for ensuring the reliability of data transmission and guaranteeing the completeness of collected data by determining the phase and monitoring range of sensor networks. However, guaranteeing the accuracy of positioning in sensor networks needs a large consumption of node resource as well as an increasing cost of installation.
Pak Sin Il, a section head at the Faculty of Communication, proposed a new algorithm for positioning the whole network by iterating the process of estimating the coordinates and path loss factors of the connected unknown nodes from the anchor nodes whose positions are known, based on Received Signal Strength Indication (RSSI) model.
In order to increase the accuracy of position decision and path loss factor estimation, he calculated the power level of white noise and introduced weighting coefficient that is proportional to the information quantities.
The experimental results indicated that the proposed algorithm can guarantee much higher accuracy than other modern positioning methods.
You can find the details in his paper “A Method for Improving Accuracy of Positioning Based on RSS Model in 3D Wireless Sensor Networks” in “Proceedings of KUTIC-2025”.
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Jo Aug 13, 2026
Continuous measurement of oxygen concentration is essential in production processes, environmental analysis, medical applications, etc. An electrochemical oxygen sensor measures oxygen concentration by measuring produced current on the basis of electrochemical principles. It has a relatively long response time.
A moving average filter is not sensitive to whether the phase response is linear or not, and therefore it is used in many applications for noise processing in various measurement systems. There are several types of moving average filters including simple moving average (SMA) filter, linear decay moving average (LDMA) filter and raised cosine moving average (RCMA) filter. The disadvantage of these moving average filters is that they cannot achieve sufficient denoising effects if the filter order is limited. A special case of the moving average filter is an exponential moving average (EMA) filter.
Han Chol Hak, a section head at the Faculty of Automatics, proposed an improved exponential moving average filter (EMA) by determining the optimal coefficient to suit smooth noisy signals of sensors.
First, he analyzed the variation of deterministic signal accuracy and noise reduction characteristics according to the coefficient value of EMA filter. Through simulation, he determined the optimal coefficient which depends on the signal to noise ratio (SNR) and the frequency of input signals by approximation. Then, he set sample frequency constraints to obtain good filtering effect. Finally, he designed an improved EMA filter that changes the optimal coefficient according to input signals, and compared it with a simple moving average filter (SMA) for oxygen sensor signals.
The results show that the proposed algorithm outperforms other moving average filters for smooth noisy signals.
If more information is needed, you can refer to his paper “An Improved Exponential Moving Average Filter Design and Application in Electrochemical Oxygen Sensor Signal Denoising” in “Proceedings of KUTIC-2025”.
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Jo Aug 12, 2026
Time delay produces detrimental effects on the stability and performance of control systems, and the control is generally more difficult unless the delay is compensated.
IMC has a remarkable effect on improving the control performance of systems with large time delays.
Hong Kwang Hyok, a researcher at the Faculty of Automatics, has proposed a modified internal model control based PID (IMC-PID) control strategy by incorporating the structure of predictive functional control (PFC) together with DOB.
First, he used particle swarm optimization (PSO) for the optimal calculation of the IMC filter time constant. Then, he combined PFC and DOB with IMC-PID controller to compensate for the effect of time delay and disturbance. Thus, he could not only enhance disturbance rejection ability but also ensure predictive control.
He applied the proposed method to a first order plus dead time (FOPDT) process to analyze the effectiveness. The simulation results showed that the proposed controller can effectively compensate for the effects of time delay and disturbance.
You can find the details in his paper “Improved IMC-PID Controller Combining Predictive Functional Control Structure and Disturbance Observer” in “Proceedings of KUTIC-2025”.
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Jo Aug 11, 2026
For high frequency vibration rejection, constant boundary layer control design and dynamic sliding mode control (DSMC) design using an integrator have been proposed. However, they use only one output feedback, so disturbance rejection and robustness enhancement are limited.
Adaptive SMC (ASMC) is used for control of systems with unknown or bounded disturbances. However, these methods do not keep the sliding variable at the ideal value zero. To increase the robustness of Smith predictor for control of delay processes, a robust Smith predictor and a PI control method for multivariable processes have been developed.
Kim Ho, dean of the Faculty of Automatics, developed a linear PI adaptive dynamic sliding mode control (DSMC) system based on Robust Smith Predictor (RSP).
In order to primarily suppress the disturbance and model perturbation of a plant, he implemented the equivalent control by a PI output feedback control loop. As the outer switching controller is designed for extended systems with an integrator, it automatically becomes a DSMC and chattering free. A linear PI feedback system with sliding variables as output is used for switching gain adaptation of sliding-mode control, and consequently, the optimality and adaptability of PI adaptive algorithm are guaranteed by the linear feedback control theory.
He verified through simulation that the proposed SMC system shows high performance that cannot be achieved by any one control alone for all indexes, namely, tracking performance, disturbance rejection, robustness, adaptability and chattering rejection.
For more information, please refer to his paper “Decentralized PI Adaptive Sliding Mode Controller with Double Output Feedback for TITO Processes” in “Proceedings of KUTIC-2025”.
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Jo Aug 10, 2026
The age of relics is determined by the amount of natural radiation that they were exposed to in the soil. Among the relics unearthed in our country are many ceramics showing the excellent culture of the nation. Quartz, the main component of ceramics, is compatible with thermoluminescence measurements because of the peculiarity of ceramics manufacture, and the relationship between the thermoluminescence intensity and the irradiated dose can be used to calculate the annual dose and to estimate the age of ceramics. The accuracy of the age is determined by the accuracy of thermoluminescence intensity measurements at the time of heating a quartz sample at a constant rate, and by the accuracy of annual dose estimates.
Kim Sung Ryol, a researcher at the Institute of Analysis, proposed a heating rate stabilization method for reproducibility and accuracy of thermoluminescence intensity and a method for estimating the annual dose rate from a ceramic sample in the soil by MCNP.
Unlike before, he applied heating temperature control to the set-point tracking method to ensure stability and to achieve correct detection of the peaks obtained from the thermoluminescence curve. In addition, he developed an MCNP-based annual dose rate assessment program to ensure the speediness of dating.
It was verified that the internal and external dose simulation calculation functions of the newly-developed computational system are in good agreement with the measurements reported in the literature and that it can be used to determine the annual dose rate of a real object.
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Jo Aug 9, 2026
The working principle of electron microscopes is to form an image by using electron beams and electron lenses instead of light beams and optical lenses in optical microscopes. The design and focusing characteristics of magnetic lenses determine the main parameters of electron microscopes. The electro-optical (EO) system of transmission electron microscopy can be classified into illumination and imaging systems. The former consists of an electron gun and a focusing lens while the latter is made up of a sample chamber, an objective lens and intermediate and projective lenses. In an EO system, lenses are the most important components and the one that plays a crucial role among lenses is an objective lens.
There are many studies in the literature on the method of calculating the focal length of magnetic lenses in transmission electron microscopes, but these calculations are empirical, based on only pole-piece diameter, gap and the number of excitation turns in a magnetic lens. The effect of the change of various factors such as other structural dimensions, magnetic lens material and magnetic circuit configuration on the focal length is not mentioned, .
In magnetic lenses, the pole-piece diameter and the gap are of primary importance, but the magnetic circuit constituting the lens, the position of the magnetic flux-making coil, and other structural dimensions will influence the magnetic field distribution and the focal length. Therefore, the conventional focal length calculation method presents many problems in the design of real magnetic lenses.
Kim Hak Chol, a researcher at the Faculty of Electronics, proposed a new method of calculating the focal length by simulating the magnetic field distribution and trajectory of a magnetic lens.
Using a simulation tool, he set the structure dimensions, excitation conditions and material settings just like real ones and calculated the magnetic field distribution based on them. Then, he determined the focal length from the trajectory data by means of the method of calculating the focal length based on the electro-optical theory.
Unlike conventional focal length calculations, the proposed method can improve the accuracy of magnetic lens design, with all the factors affecting the focal length in consideration.
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