Jo Aug 26, 2023
With a flood of display devices with different resolutions, there are increasing demands for efficient image scaling algorithms, which can improve performances of real-time applications such as remote desktop and screen sharing. Image downscaling algorithms can be divided into two classes ― content-adaptive and non-adaptive. Non-adaptive algorithms produce aliasing, blur and halo artifacts though they are very fast. Content-adaptive algorithms have been proposed to improve perceptual quality of scaled images at the expense of computational power.
Many of the content-adaptive downscalers employ non-adaptive algorithms like box filtering and Bicubic as fundamental tools. This means that the performance of those adaptive scaling methods can be improved by using a superior non-adaptive algorithm.
Kim Su Hyon, a researcher at the Faculty of Information Science and Technology, has proposed a new non-adaptive spatial filter kernel based on a circular area pixel model to improve the underlying frameworks of many state-of-the-art downscalers.
A pixel in a digital camera is the basic element of a sensor and its shape is rectangular. However, a point of light in a scene is spread by an optical system and creates a blurred circular image onto the pixel. In the spatial domain, an optical PSF (Point Spread Function) describes the degree to which an optical system spreads a point of light. Though the PSF from a circular aperture can be expressed by a sombrero function, it is usually modelled with simpler expressions such as a uniform circular disk. Therefore, from the optical point of view, he used a circular area pixel model rather than a rectangular one.
Since his kernel is one-dimensional, the proposed algorithm has two steps: horizontal and vertical processing. For upscaling, an original and a target pixel are treated as circular regions. For downscaling, only target pixel is treated as an elliptical region.
Abundant objective comparisons showed that the proposed downscaling algorithm is the fastest and has the highest PSNR and SSIM values among the commonest non-adaptive image scaling algorithms. Visual comparisons also showed that his algorithm produces the clearest images without blurring and halo effects. His filter kernel can replace the existing spatial kernels of edge-adaptive image downscalers to improve their performance further.
For further information, you can refer to his paper “ A New Image Downscaling Algorithm based on a Circular Area Pixel Model” in “ ACM Conference Proceedings” (EI).
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Jo Aug 24, 2023
Thae Il Gwang, a researcher at the Faculty of Mining Engineering, has built an experimental jaw crusher for analyzing the working properties of jaw crushers commonly used in stoping faces and concentrating mills.
It is composed of a jaw crusher, sensors and a control circuit.
The crusher consists of a body with a fixed jaw, a movable jaw, an eccentric shaft, a connecting rod, a drawbar and a spring. Some structural modification was made to the drawbar and eccentric shaft to install necessary units for experiments.
Sensors are installed on the connecting rod and the eccentric shaft, respectively. They are used for measuring compressive force on the connecting rod and angular displacement on the eccentric shaft.
The control circuit can be connected with a computer to control the jaw crusher and to collect and send measured data.
The data sent to the computer is analyzed by an application for working properties and the computer displays angular displacement, angular velocity and moment of the eccentric shaft, crushing force on the movable jaw, and power consumption for crushing.
This device is used for analyzing fracture mechanism of different ores or for improving working properties of jaw crushers.
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Jo Aug 23, 2023
A research team led by Kang Song Il, a researcher at the Faculty of Mining Engineering, has developed a load cell capable of precisely measuring mechanical properties of coal faces in full consideration of the effect of eccentric load in order to explain ground pressure characteristics.
The load cell consists of an elastic body and a resistance wire sensor.
The elastic body consists of four beams whose two sides are fixed and each beam has two resistance wire sensors on both sides. A total of 16 resistance wire sensors form a bridge circuit.
As four resistance wire sensors are connected in series on each branch of the bridge circuit, different deformations generated from them do not affect the overall measurement results. Instead, only total resistance change generated on the four resistance wire sensors is related to the measurement results.
The load on the elastic body is represented as the change of the sensor as it is transferred to the resistance wire sensor. Resistance values are calculated from the relationship between the resistance and the change, and displayed as resistance values in the multi-channel measuring device.
The load cell is installed in the support of a coal face. Vertical load is measured by a ground pressure meter between a beam and a middle support, which is set up in the middle of a beam of the support, while side load is measured by the meter in a lagging, which is set up between a coal wall and a bridge of the support.
The ground pressure characteristics in an area can be figured out by the properties of a certain area obtained in a mathematical method from measured values and the properties of known areas.
This device is helpful to get a correct description of ground pressure characteristics found in all kinds of coal mines and faces in different geological conditions, and to measure precisely the mechanical properties of corresponding rock mass such as cohesion, angle of internal friction and Poisson coefficient, which makes it possible to establish suitable methods of supporting mines. It will lead to a significant reduction in the consumption of materials such as supports, and safe working conditions and stability of coal production.
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Jo Aug 21, 2023
A research team led by Kim Haeng Sok, a researcher at the Faculty of Electrical Engineering, has developed a partial discharge measurement system for insulation condition estimation in electrical power equipment.
Measurement of partial discharges (PD) is an effective way to evaluate insulating material degradation in high voltage equipment.
Partial discharge promotes degradation of insulating material and extends discharge paths to destroy insulation.
The partial discharge measurement system consists of a pulse current sensor, a measurement device and a display device. Partial discharge signals are transferred to the measurement device via a pulse current sensor, and after noise detection and correction, they are described as the amount of discharge to evaluate the state of insulation. A ferrite core is used for the pulse current sensor and the measurement device is aimed at filtering, amplifying and processing the signals.
The research team decided structural parameters of the pulse current sensor and detected the PD signals involved in noise by processing wavelet signals.
The system provides possibility to prevent hazards of high voltage equipment by evaluating in real time the state of insulation for any kind of electric power equipment. It can be widely adapted in the fields of electrical power industry.
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Jo Aug 18, 2023
A research team led by Pak In Hui, a researcher at the Faculty of Biology and Medicine Engineering, has developed an electrical stimulator combined with low-frequency and medium-wave heat. It is a modern computer-controlled medical device of our own style in which optimization and digitization are fully realized.
The stimulator consists of a body, an RS-232C data transmission bus, a computer therapy control program, and therapeutic conductors. The body is divided into three parts: diagnosis, therapy and display.
The therapeutic conductors include a massage stimulator to relieve the tension of visceral organs and muscles and improve blood circulation, a roll needle stimulator capable of self-searching and stimulating various treatment points, and a device for treating diseases using a midwave tunnel effect.
They determined the optimal stimulus parameters for appropriate frequency, intensity, time and method to accurately detect and measure light blood reaction points on the skin surface and to treat diseases and dysfunctions.
When diseases destroy the homeostasis of human body, the stimulator can effectively treat them by giving frequency and midwave tunnel stimulus to the corresponding acupuncture points. It is particularly effective for digestive and urinogenital diseases.
This device can automatically control all treatment processes by computer therapy control programs according to diseases and patient’s conditions, and it can save many drugs as it provides non-infestation therapy. Thus, it will enjoy wide application in the field of public healthcare.
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Jo Aug 17, 2023
A research team led by Kim Pyong Hun, a section head at the General Assay Office, has developed a device for rapidly determining the concentration of biochemical indexes in human blood and other body fluids by spectrophotometric method.
The automated biochemistry analyzer is a medical analytical instrument for diagnosing several kinds of diseases by rapidly determining the concentration of biochemical indexes of blood and other body fluids such as GOT, GPT, TP, CK, GLU, LDH, etc.
It consists of sample injection unit, regeants injection unit, reaction and optical monochromator unit, stirring unit, washing unit, power supply unit, control unit, etc.
In the sample injection unit, the range of sample setting volume is 1 to 20μL with 0.1μL stepping. The sample disk has a total of 120 positions. The sample probe works above the reaction cuvette, and then returns to the sample probe rinse trough.
In the regeants injection unit, the range of reagent setting volume is 10 to 400μL with 1μL stepping. The reagent disk has 80 positions in total. The reagent probe works in the same way as the sample probe. Reagent bottle volumes are 15ml, 20ml, 70ml, etc.
In the reaction and optical monochromator unit, reaction cuvette volume is about 150～500μL. The range of wavelength in the photometric system is 340～750nm. The wavelength accuracy is ±2nm. The light source is a 20W/12V life quartz halogen lamp. The measurement range is 0 to 4Abs. The incubation bath temperature is 37±0.1℃. The reaction disk has 80 positions in all.
In the stirring unit, stirring is carried out after addition of sample and reagent each. After stirring, the stirring rod comes back to the rinse trough.
In the washing unit, the reaction cuvettes are washed after measurement.
In the reagent cooling unit, all reagents are kept at 5~15℃.
In the power supply unit, power is supplied to the signal amplifier and controller as well as to the probe for injecting liquor necessary for sample injection, reagent injection, washing, etc. and to the switching valves for selecting liquor.
The analysis methods include rate assay, end-point assay and 2-point assay. The calibration methods include 1-point linearity, 2-point linearity, multi-point linearity and non-linearity.
The automated biochemistry analyzer is applicable to the following indexes: GOT 35.4~56.3u/L, GPT 25.6~42.3u/L, TP 4.54~5.66mg/dL, CK 115~173u/L, GLU 76.4~106mg/dL, ALB 2.54~4.06mg/dL, LDH 152~214u/L, etc.
The accuracy of the analyzer is ≤1.5% for biochemical indexes.
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