• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 1999.11b
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• pp.204-208
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• 1999

Friction was measured on filter paper sheets impregnated with model compounds representing wood extractives using an apparatus based on the horizontal plane principle. The best lubrication of paper surfaces was achieved when they were completely separated by a densely packed film of saturated long-chain amphophilic molecules, such as fatty acids. The fatty acids adsorbed with their polar ends on the paper surface, causing their hydrocarbon chaine to be orientated perpendicularly to the paper surface. The saturated C18-acid, stearic acid, was an efficient lubricator for paper surfaces. The introduction of a double bond in stearic acid eliminated its lubricating ability. The spatial length of the lubricating fatty acid thereby decreases from 24${\AA}$ to 11${\AA}$. However the transisomer of oleic acid, elidic acid, had the ability to lower friction due to an increased spatial length of the fatty acid. Both the spatial length of the hydrocarbon chain and the number of lubricating chains may be of importance for the paper-to-paper friction caused by wood extractives. A hydrophilic head-graup in the wood extractive and an ordered molecular layer of lubricating molecules seems also to be prerequisites for efficient lubrication. A chemical weak boundary layer between the paper sheets was suggested to cause the low friction when long chain saturated fatty acids were deposited on paper.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.9
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• pp.1248-1256
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• 1993

The propagation and delay properties in opical fiber are particularly attractive because digital signal processing and conventional analog signal processing techniques such as those using surface acoustic wave devices are limited In their usefulness for signal bandwidth exceeding one or two GHz, although they are very effective at lower frequencies. Since an accurate, low loss and short time delay elements can be obtained by using such an optical fiber, optical signal precessing has attracted much attention for high speed and broad-band signal precessing in particular channel separation filtering for optical FDM signals. In this paper, we consider a coherent optical lattice filter, which uses coherent light sources and consists of directional couplers and optical fiber delay elemnts. The optical fiber fitters are more restricted than the usual digital filters. The reasons are as follows. 1) the coupling coefficients of directional couplers are restricted to the number between 0 and 1. 2) optical signal E(complex amplitude) is divided into J If-$\boxUl$ and J L/7$\div$$\boxUl$ at the directional coupler. Considering these restrictions and in this case all the coupling coefficients of summing and branching elements are set to be equal, we have given design formulae for optical lattice filter, which make the best use of optical signal energy.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.681-685
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• 2013

A pilot-scale sand-box experiment was performed in order to investigate the effect of cross-flow velocity on the clogging of the filter sand in a model filtration pond. The clogging phenomenon was observed during the operation with the cross-flow varied in stages in a range of 0~40 cm/sec, and the experimental result was analyzed using a numerical code. Results showed that the cross-flow velocity in this range had no influence on the development of clogging and that clogging occurred mostly on the filter-surface. It was found that while the production rate decreased from $5m^3/m^2-day$ to $3m^3/m^2-day$ the clogging coefficient of the top 50 cm layer increased up to about 30,000 sec, which corresponded to 87% of the clogging coefficient of the total 2.4 m layer. Of the clogging coefficient of the top 50 cm layer, surface clogging constituted 90% while the other 10% was intermediate clogging. It was also found that the surface clogging increased while the intermediate clogging remained constant as the operation continued, and that filtrate turbidity along the filtration depth remained constant in spite of the increase in clogging.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.1
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• pp.115-125
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• 2019

In this paper, the image is received from the camera and the lane is sensed. There are various ways to detect lanes. Generally, the method of detecting edges uses a lot of the Sobel edge detection and the Canny edge detection. The minimum use of multiplication and division is used when designing for the hardware configuration. The images are tested using a black box image mounted on the vehicle. Because the top of the image of the used the black box is mostly background, the calculation process is excluded. Also, to speed up, YCbCr is calculated from the image and only the data for the desired color, white and yellow lane, is obtained to detect the lane. The median filter is used to remove noise from images. Intermediate filters excel at noise rejection, but they generally take a long time to compare all values. In this paper, by using addition, the time can be shortened by obtaining and using the result value of the median filter. In case of the Sobel edge detection, the speed is faster and noise sensitive compared to the Canny edge detection. These shortcomings are constructed using complementary algorithms. It also organizes and processes data into parallel processing pipelines. To reduce the size of memory, the system does not use memory to store all data at each step, but stores it using four line buffers. Three line buffers perform mask operations, and one line buffer stores new data at the same time as the operation. Through this work, memory can use six times faster the processing speed and about 33% greater quantity than other methods presented in this paper. The target operating frequency is designed so that the system operates at 50MHz. It is possible to use 2157fps for the images of 640by360 size based on the target operating frequency, 540fps for the HD images and 240fps for the Full HD images, which can be used for most images with 30fps as well as 60fps for the images with 60fps. The maximum operating frequency can be used for larger amounts of the frame processing.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.371-378
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• 2000

In this study, we proposed pathological pattern detection system for X-ray chest image using artificial neural network. In a physical examination, radiologists have checked on the chest image projected the view box by a magnifying glass and found out what the disease is. Here, the detection of X-ray fluoroscopy is tedious and time-consuming for human doing. Lowering of efficiency for chest diagnosis is caused by lots mistakes of radiologist because of detecting the micro pathology from the film of small size. So, we proposed the method for disease detection using artificial neural network and digital image processing on a X-ray chest image. This method composes the function of image sampling, median filter, image equalizer used neural network and pattern recognition used neural network. We confirm this method has improved the problem of a conventional method.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.219-223
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• 2003

This paper describes an estimation of DOA(Direction Of Arrival) measurement system using DBF receiver with linear array antenna. This DBF receiver is composed of resistive FET mixer using low IF mettled. A radio frequency(RF), a local oscillator(LO) and ail intermediate frequency(IF) considered in this research are 2.09 GHz, 2.08 GHz and 10 MHz, respectively. This receiver is composed of a band-pass filter, a low-pass filter, a DC bias circuit. DOA measurement system is consist of linear array antenna, DBF receiver, AD control box and computer in the anechoic chamber. Receiving antenna is 4-array monopole antenna and DBF receiver is 4-Ch resistive FET mixer without amplifier. DOA algorithm is implemented using MUSIC algorithm with high resolution. We show that the results of DOA is $-30^{\circ},\;0^{\circ}$ and $60^{\circ}$, respectively. And we know that DOA estimation error occur by antenna radiation pattern and fabrication error of antenna array.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.8 s.239
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• pp.1093-1101
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• 2005

Hybrid mass damper systems have recently been introduced as a dynamic vibration absorber to exploit the benefits of both the conventional tuned mass damper system and the active control system. A hybrid system is programmed to function as either a conventional TMD or as an active system according to the wind conditions and the resultant building and damper mass vibration characteristics. This paper deals with the design of the robust controller for the control of the flexible box structure. The control algorithm was devised based on $H_2$(LQG) robust control logic with acceleration feedback and to improve the capability of the controller Kalman Filter was accepted for the system. To test the ability of the robust controller using the linear motor damper system, performance tests and simulations were carried out on the full-scale steel frame structure. Through the performance tests, it was confirmed that acceleration levels are reduced down.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.235-240
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• 2020

This study evaluated the improvements for circuits of a combat vehicle distribution box to reduce the noise generated in electromagnetic compatibility (EMC) testing. An analysis of the distribution boxes that failed the standard revealed the conducted noise generated from the converter and semiconductor switching elements on the circuit board. The distribution box transfers power from the generator and battery to the cooling system of a combat vehicle to keep turning the air conditioner on and off. Two methods were proposed to overcome this problem: a passive filter was added to the circuit board for the first method, and the converter and switching elements were replaced with the relays for the second method. Both methods were effective in reducing noise, but a greater improvement was obtained from the second method. The second method was applied to a combat vehicle system and was found to be suitable according to the EMC standards.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.372-375
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• 2003

The incidence of blindness resulting from diabetic retinopathy has significantly increased despite the intervention of insulin to control diabetes mellitus. Early signs are microaneurysms, exudates, intraretinal hemorrhages, cotton wool patches, microvascular abnormalities, and venous beading. Advanced stages include neovascularization, fibrous formations, preretinal and vitreous microhemorrhages, and retinal detachment. Microaneurysm count is important because it is an indicator of retinopathy progression. The purpose of this paper is to apply data mining to detect diabetic retinopathy patterns in routine fundus fluorescein angiography. Early symptoms are of principal interest and therefore the emphasis is on detecting microaneurysms rather than vessel tortuosity. The analysis does not involve image-recognition algorithms. Instead, mathematical filtering isolates microaneurysms, microhemorrhages, and exudates as objects of disconnected sets. A neural network is trained on their distribution to return fractal dimension. Hausdorff and box counting dimensions grade progression of the disease. The field is acquired on fluorescein angiography with resolution superior to color ophthalmoscopy, or on patterns produced by physical or mathematical simulations that model viscous fingering of water with additives percolated through porous media. A mathematical filter and neural network perform the screening process thereby eliminating the time consuming operation of determining fractal set dimension in every case.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1039-1044
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• 2011

Magnetron is applied in microwave ovens for generating microwaves. It is composed of r-fin, yoke, A/F seals, gasket base, filter box. The temperature is occurred highly, when magnetron operate in its systems. Therefore the thermal characteristics must be considered in the design of magnetron. Because of its geometric complex, it is difficult to analysis the thermal characteristics. In this paper, temperature analysis is performed for all components. The commercial software ANSYS is used to consider both conduction and convection. The analysis is carried out by adding each component. An experiment on the thermal characteristics is performed to verify the reliability for simulation.