Jo Oct 1, 2025
The Korean people have celebrated Chusok (Harvest Moon Day) as a great folk holiday from olden times.
The term Chusok, which literally means autumn evening, originated from the practice of celebrating the full moon day in autumn of abundant harvest.
The Korean people have long regarded visiting their ancestral graves on the day of Chusok as a natural duty and a traditional custom.
When they visited their ancestral graves, they carried dishes cooked of new cereals to hold a memorial service, dressed in festive clothing.
For successful celebration of Chusok, they made all dishes the day before.
The special festival dishes of Chusok are half-moon-shaped new rice cake, steamed rice cake, chestnut dumpling, liquor, etc., among which half-moon-shaped rice cake has been accepted to be indispensable as a symbolic dish of Chusok.
Nochi made of glutinous rice powder, malty powder, etc. was also famous as a special dish of Pyongyang
People enjoyed the day playing several folk games including ssirum, swinging, tug of war, etc.
Enjoying the full moon was another custom of the day.
They either gathered in their house yards or climbed high mountains around them to see the rising moon.
This custom reflects the inner world of the sentimental and emotional Korean nation.
The Korean people still celebrate Chusok significantly as a traditional folk holiday and as an occasion of recollecting the unforgettable revolutionary forerunners, comrades, family members, relatives and friends who passed away.
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Jo Sep 30, 2025
On-demand charging schemes have been recently proposed to make efficient charging schedules of mobile chargers by introducing MCDM methods in wireless rechargeable sensor networks (WRSNs). However, most of the existing schemes use paired ratio scale (PRS) for weight assignment of multiple criteria to exaggerate the actual paired difference between them, and in the case of using FCNP of paired interval scale (PIS) for weight assignment of multiple criteria, weight compensation is not considered.
What is more, it is still unknown which is the best method for integrating FCNP with several MCDM approaches.
Rim Ju Song, a student at the Faculty of Communications, with the help of Ri Man Gun, an institute head of the same faculty, has proposed novel CS methods by integrated FCNP-VWA-MCDM(i) called FCVM(i) for solving all these problems.
The proposed methods first assign the weights to multiple criteria discriminating charging request node (cRNs) using FCNP and make compensation of them to be relatively exact weights with VWA. Then, on the basis of these weights, MCDM(i) is used to select the most proper next charging position. Recharging schedule is drawn up in this way and, at the same time, reasonable partial charging time at the selected charging locations are determined using the assigned weights with FCNP-VWA.
The extended experimental results prove that the FCVM(1) using TOPSIS gives the best performance among FCVM(i) methods.
You can find the details in his paper “FCVM(i): Integrated FCNP-VWA-MCDM(i) Methods for On-Demand Charging Scheduling in WRSNs” in “Journal of Data Science and Intelligent Systems” (SCI).
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Jo Sep 29, 2025
Fractal interpolation function (FIF) is a function which interpolates a given data set and whose graph is a fractal set. In 1986, M. F. Barnsley introduced the FIF using an iterated function system (IFS). Ever since, many researchers have studied the FIFs and applied them to a lot of scientific fields such as computer graphics, function approximation, signal processing, metallurgy, earth science, surface physics, geography, geology, medical science, chemistry, etc.
Rakotch contraction is the generalization of Banach contraction, which implies that the use of Rakotch’s fixed point theorem enables modeling of more objects than the use of Banach’s fixed point theorem. Moreover, hidden variable recurrent fractal interpolation functions (HVRFIFs) with Hölder function factors are more general than fractal interpolation functions (FIFs), recurrent FIFs and hidden variable FIFs with Lipschitz function factors.
Ro Chung Il, a researcher at the Faculty of Applied Mathematics, has demonstrated that HVRFIFs can be constructed using the Rakotch’s fixed point theorem, and investigated the analytical and geometric properties of those HVRFIFs.
Firstly, he constructed nonlinear hidden variable recurrent fractal interpolation functions with Hölder function factors on the basis of a given data set using Rakotch contractions. Next, he analyzed the smoothness of the HVRFIFs and showed that they are stable for the small perturbations of the given data. Finally, he obtained the lower and upper bounds for their box-counting dimensions.
If further information is needed, please refer to his paper “Analytical properties and the box-counting dimension of nonlinear hidden variable recurrent fractal interpolation functions constructed by using Rakotch’s fixed point theorem” in “Applied Mathematics and Computation” (SCI).
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Jo Sep 28, 2025
It is well known that cylindrical shell structures are widely used in many industrial fields including mechanical, aerospace, ship building, chemical and architectural industries. Typical examples are fuselage in the aerospace industry or submarines in the shipping industry, and vessels in the chemical industry. In the structures of these examples, various types of composite materials are being applied, either due to their performance or structural requirements. In addition, these structures will be worked in different environments and load conditions.
Generation of vibrations leads to noise. Therefore, there have been many studies to analyze the vibration and acoustic characteristics of these structures and as a result, various shell theories have been proposed. Based on these shell theories, studies have been carried out to develop solution methods with high computational accuracy and computational efficiency for vibration analysis of laminated composite cylindrical shells.
However, the study of the vibro-acoustic analysis of stepped cylindrical shells is limited, and what is more, there is no study of acoustic analysis.
U Ju Hyok, a researcher at the IT Institute, has analyzed the vibro-acoustic responses of laminated composite multi-stepped cylindrical shells immersed in fluid medium by applying the energy and spectral boundary element method.
He has verified the accuracy and reliability of the proposed method by comparing it with the results obtained by references. Then, he has conducted several numerical analyses to provide the influence of geometry, material properties, boundary condition, fluid medium and force types on vibro-acoustic behaviors of the laminated composite multi-stepped cylindrical shells.
For more information, please refer to his paper “Vibro-Acoustic Response Analysis of Laminated Composite Multi-Stepped Cylindrical Shells Immersed in Fluid Medium” in “Journal of Vibration Engineering & Technologies” (SCI).
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Jo Sep 26, 2025
In the wireless recharge sensor network (WRSN), charging scheduling is to schedule charging tasks by employing a mobile charger (MC).
Drawing up the charging schedule of a MC which maximizes the network lifetime by determining the most suitable charging location and charging time is a consistent and invariant guideline for on-demand charging scheme in WRSNs.
To this end, Ri Man Gun, an institute head at the Faculty of Communications, has proposed a new charging scheduling scheme based on an integrated FCNP-VWA-PROMETHEE (iFCVP).
This scheme first assigns relative weights to the multi-criteria characterizing the charging request nodes with FCNP, and compensates them with VWA to make more accurate weights. These weights are then used to select the most suitable next-to-be-charged location by the PROMETHEE. Together with determination of the charging order, the partial charging time at the selected charging locations are reasonably determined using the weights assigned by FCNP-VWA by considering the trade-off between the performance metrics.
The results of the extensive simulation show that the proposed scheme gives superior performance over several existing integrated MCDM methods.
For more information, you can refer to his paper “iFCVP: an integrated FCNP-VWA-PROMETHEE method for on-demand charging scheduling in WRSNs” in “Proceedings of Ninth International Congress on Information and Communication Technology” (EI).
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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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