Jo Sep 25, 2025
Scientific operation of production processes with quantitative evaluation of sensory characteristics is important for improving product quality in the food industry. In order to achieve the target quality in the production processes with controllable parameters, the set-point of process parameters must be controlled to suit the operating conditions. In food production processes where the quality is represented as sensory characteristics, it is particularly important to quantitatively evaluate the quality of products.
Set-point control methods include intelligent supervisory control, case-based reasoning, etc. In addition to rule-based reasoning, case-based reasoning that utilizes operation expertise and cases to infer similar solutions corresponding to similar conditions has been widely applied to the optimal operation of industrial processes.
One of the major challenges in applying case-based reasoning to the set-point control of industrial processes is to constantly adapt the case base to the changing characteristics of processes, thus increasing the accuracy of reasoning. There was a methodology to solve this problem, which failed to deal with updating the case base with operational experience and new knowledge obtained during the online operation of industrial processes.
Song Kwang Rim, a researcher at the Faculty of Automation Engineering, has proposed a new method for online updating and addition of case base and applied it to the set-point control of a rolled cake production process.
First, he presented an approach for quantitatively evaluating the rolled cake based on the sensory quality. Second, he proposed an interactive method of acquiring knowledge from operator’s experiences and adapting the case base according to the behavior of the process and the quantitatively evaluated quality level.
The comparative experiments for validation show that the proposed method results in 4.1% improvement in the ratio of good products.
You can find the details in his paper “Acquisition of adaptive knowledge in case-based reasoning for the online set-point control of industrial process” in “Third International Conference on Communications, Information System, and Data Science (CISDS 2024)” (EI).
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Jo Sep 24, 2025
Hazardous industrial wastewater usually contains many toxic heavy metals such as chromium, nickel, copper, zinc, lead, cadmium and mercury. The discharge of industrial wastewater containing such heavy metals without being treated not only destroys the ecological environment but also produces a negative effect when it enters animal or human bodies.
Chromium is one of the metals used in the industrial processes including stainless steel and alloy steel production, pulp production, electroplating, textile industry, metal refining, tanning, glass industry, petroleum refining, etc. Trivalent chromium existing in the waste water is generally produced from inorganic pigments, glass preparation, ceramics, etc., and it may be produced by reduction of hexavalent chromium in reducing atmosphere. Chromium ions are toxic heavy metal ions, which seriously contaminate soil and water. Therefore, it is very important to remove chromium ions in the wastewater before it is discharged into rivers or lakes.
Chromium, like other metals, can be treated in various ways such as chemical precipitation, ion exchange, membrane filtration, solvent extraction, electrochemical processes, biological methods and photo catalysis. Recently, adsorption method has been widely applied to wastewater treatment due to its simple operation and low cost.
Ri Kyong Hun, a researcher at the Faculty of Mining Engineering, has investigated the preparation of inorganic adsorbents for removing heavy metals from wastewater and other scientific and technological problems for efficient removal of chromium in wastewater by the adsorbents.
He worked on the synthesis of heavy metal adsorbents by low-temperature hydrothermal synthesis method to prepare nanocrystalline inorganic adsorbents (erdite) of 80nm in diameter and 100nm in length at 90℃ for 24h under the conditions of S/Fe > 3 and OH-/Fe > 20.
From the experiments to use the mother liquid back to the synthetic experiments, he has confirmed that a little addition of only Na2S·9H2O to the mother liquid makes it possible to effectively synthesize erdite. The removal efficiency of these sorbents for Cr(III) is above 99.8%.
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Jo Sep 23, 2025
Active disturbance rejection control (ADRC) is one of the notable disturbance and uncertainty estimation and attenuation techniques.
Kim Ho, dean of the Faculty of Automation Engineering, has proposed a method based on the maximum sensitivity index, with an attempt to solve the problems arising in the parameter tuning of ADRC.
Then, he has applied it to the temperature control of a water glass reaction tank subject to strong model uncertainties and disturbances.
First, he built a mathematical model of a water glass reaction tank by using the identification technique based on the step response signal, and designed a second-order linear active disturbance rejection controller based on it. Then, based on the maximum sensitivity index, he presented a formula of tuning the parameters of the second-order linear active disturbance rejection controller to achieve robustness, and verified its effectiveness using MATLAB.
As a result, he has concluded that the proposed formula is suitable when the non-delay is less than 0.3, and that time delay compensation techniques such as Smith predictor should be applied when the non-delay is more than 0.3 as the time delay is not negligible.
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Jo Sep 22, 2025
The Paleozoic erathem is important of all deposits in the earth’s crust, and they are widely distributed in many areas. Therefore, there have been many geological studies including stratigraphic, mineralogic, petrographic and mineral resources studies for Paleozoic erathem.
In our country, the Paleozoic Formations are distributed in the Pyongyang Basin, the Kaechon Basin and the Kowon Basin, where there are only lower layers because the upper layers are eroded. In Thaejawon Formation, the upper Formation of Kaechon Group, little extinct organisms and special resources have been found, unlike other Paleozoic erathem, and there have been fewer studies of these strata than other strata.
Jo Song Gil, a researcher at the Faculty of Earth Science and Technology, has conducted macrography, microscopic investigations, XRF and XRD on the lens bodies present at the top of lower Member of the Thaejawon Formation in the southern area of Jangansan syncline of Kaechon Basin, to elucidate the mineral petrographic characteristics and investigate the paleoenvironment.
He found out the elemental composition, mineral composition and lithological characteristics of the target layer and host rocks using an optical microscope, X-ray fluorescence (XRF) and X-ray diffraction (XRD). The target layer is a calcareous conglomerate lens, mostly similar to the host rock in mineral composition, with some differences in some contents and compositions. The target layer and its host rocks are deposited in the freshwater environment, and the paleosalinity of the calcareous conglomerate lens is higher than that of other strata. The redox potential of depositional environment in the target rock is higher than the host rock, and it was very dry when the target rock and its lower layer were formed.
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Jo Sep 21, 2025
The inverted pendulum system is one of the most widely-used experimental devices to verify the effectiveness of various control algorithms in the field of control engineering.
Despite being an unstable system, the inverted pendulum system is a very interesting control object with satisfactory controllability and observability that can be stabilized by one control variable.
Pak Se Yang, a researcher at the Science Engineering Institute, has designed a linear control system for the stabilization control of a flywheel inverted pendulum and applied it to an experimental device to evaluate its effectiveness.
First, he analytically derived the mathematical model of a flywheel inverted pendulum system and experimentally determined the parameter values of the model.
Next, he designed an augmented linear quadratic optimal controller as a robust controller considering the uncertainty of the model parameters and verified its control performance through semi-physical simulations. He designed a prototype experimental system and implemented a control program to experimentally verify that the theoretically designed control system actually stabilizes the system.
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Jo Sep 19, 2025
Carburization is a technological process for increasing the service life of steel by enhancing its abrasion resistance. However, carburization has low productivity because it takes a long time, and the increase in the carburizing temperature of low carbon steel to reduce carburization time causes coarsening of the prior austenite grains, which results in the decrease in the mechanical properties.
Kim Myong Gwon, a researcher at the Faculty of Materials Science and Technology, has simulated the phase constitutions of low alloy steel 18CrMn and Ti-and-Nb-microalloyed steel 18CrMnTiNb, and analyzed their microstructures and mechanical properties when they were carburized at high temperature.
The steel 18CrMnTiNb, which is microalloyed with 0.06% Ti and 0.06% Nb, has fine grain size after being carburized at 1 000℃. Its prior austenite grain size is less than 25μm. The experimental results show that high-temperature carburization of Ti-and-Nb microalloyed low carbon steels can significantly reduce the carburizing time and provide sufficient mechanical properties.
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