• Korean Journal of Optics and Photonics
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• v.34 no.6
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• pp.261-268
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• 2023

We propose a compact differential interference contrast microscopic module, which enables snapshot measurements for quantitative phase imaging. The proposed module adopts the lateral shearing interferometric principle, which can obtain self-interference without a reference. Due to the absence of the reference, the system is more stable than the typical interferometric systems. It uses a polarization grating to generate two laterally shifted wavefronts based on its birefringence and polarizing beam-splitting characteristics. Furthermore, the use of a polarization camera does not require sequential measurements for the phase extraction. In the experiments, we observe and measure the timely varying changes of various specimens to verify the system performance with the bright field images and phase contrast images. Because the proposed microscopic module also has the merit of being adaptable to typical microscopy instead of using an imaging camera, it can conveniently replace conventional contrast microscopy.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.434-440
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• 2023

This paper propose the method that measure the main system parameters for current control of a.c. motor adopting the vector control technique. The automatical method that tuning PI control gains for current control of servo motors are used frequently through the information of main system parameters, wire resistance and inductance. In this study, the techniques to measure these two system parameters through the control of 3-phase inverter are presented. These control and measuring method are implemented by measuring output phase current obtained as a results of the step current control using simple proportional feedback input. Moreover, this method use freewheeling current of inverter at special switching mode for measuring inductance. This analytic strategy is could measure and calculate the system parameters without the complex measurement algorithm and new additional measuring circuits. That is could measure the total resistance and total inductance including wiring resistance and conduction resistance of switching devices using real driving circuits to control the motors.

• The Journal of the Acoustical Society of Korea
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• v.26 no.7
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• pp.328-333
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• 2007

In this paper, we describe characteristics of a movable bridge called the Anjok and propose an improved string model which has delay line controller in physical modeling of the Gayageum. Movable bridge, the Anjok determines the length of vibrating string and transmits the vibration of each string to the body of the Gayageum. We analyze the variations in frequency domain and implement the Anjok model as parametric form using the first-order polynomial fitting in logarithmic scale graph, because the length of string changes fundamental frequency. In order to implement the Anjok model, frequency fitting, tension fitting and frequency fitting using leaky integrator are used. The frequency fitting using leaky integrator has the best results among those. Proposed string model with the Anjok model can represent real tuning system of the real Gayageum and the proposed model could synthesize sounds which is similar to original sounds.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.363-368
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• 2024

Steel structures used in marine environments, such as ships, offshore structures or sub-structures in wind power generation facilities are prone to corrosion. In this study, the corrosion fatigue crack propagation characteristics due to the environmental load are examined by experiment at -1050 mV vs. SCE, which is equivalent to the anti-corrosion potential of zinc anodes that are widely used as sacrificial anodes. In this study, for this purpose, an experimental study is conducted on the effect of cathodic protection on the propagation of fatigue cracks in the seawater environment under the condition of -1050 mV vs. SCE, considering the wave period in synthetic seawater. Cathodic protection prevents corrosion; however, excessive protection generates hydrogen through chemical reactions as well as calcareous deposits. The fatigue crack propagation rate appeared to be faster than the rate in a seawater corrosion environment at the early stages of the experiment. As the crack length and stress intensity factor K increased, the crack propagation rate became slower than the fatigue crack propagation rate in seawater. However, the crack growth rate was faster than that in the atmosphere.

• Journal of the Korean Applied Science and Technology
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• v.29 no.3
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• pp.486-494
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• 2012

Nano-emulsion with phase inversion temperature (PIT) emulsifying system was prepared to use rapeseed oil from originating Jeju in order to apply various cosmetic applications. Natural rape seed oil (NRSO) extraction was extracted using n-hexane as a solvent. NRSO extract showed a light yellowish color of viscous liquid as well as yield was $43{\pm}2.5%$. Acid value was $2.76{\pm}0.5$ and gravity was $0.89{\pm}0.05$. Droplet size of PIT-Yuche-NE with 20wt% of rapeseed oil was 50-120nm (average: $82{\pm}5.8nm$) and zeta potential was -29.5mV. It was thermodynamically good stable emulsion due to $(PEG)_{5-30}$fattyacidether. Some conclusions from the result of characteristic experiment were obtained as follows. First, the anti-oxidative activity was measured by free radical scavenging activity using DPPH (1,1-diphenyl-2-picrylhydrazyl radical). Anti-oxidative activity of PIT-Yuche-NE was $37.2{\pm}6.7%$ on 10mg/mL compared with PIT-Toco-NE (Natural tocopherol nano-emulsion, $28.8{\pm}6.5%$ on 10 mg/mL) and PIT-Nokcha-NE (Green tea extract nano-emulsion, $29.6{\pm}7.2%$ on 10mg/mL). Second, the collagen synthesis activity of PIT-Yuche-NE was $148{\pm}15.2%$ compared with PIT-Toco-NE (Natural tocopherol nano-emulsion, $121{\pm}13.5%$ on 10mg/mL) and PIT-Nokcha-NE (Green tea extract nano-emulsion, $95{\pm}12.7%$ on 10mg/mL). Third, the effectiveness of moisturizing activity of Yuche-CRM with Aramo-TS after 6 hours increase $47{\pm}3.9%$ (*p-value￡0.05, n=7) whereas Both Toco-CRM was $30{\pm}5.2%$ (*p-value￡0.05, n=7) and Nokcha-CRM was $35{\pm}4.5%$. Therefore, Yuche-CRM has higher moisturizing effect than other two creams. Finally, Nano-emulsion stabilizing rapeseed oil using PIT emulsifying system of this study can be used to apply cosmetics industry and pharmaceutical industry.

• The Journal of Engineering Geology
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• v.9 no.2
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• pp.161-176
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• 1999

The objectives of this study are to analyze the changes of geo-surface topography in the Siwha embankment and the Ahsan city area by the image processing of Landsat Thematic Mapper data, and to estimate the reclaimed amount of the exposed tidal flat in the Siwha area using the GIS. False color composite, Tasseled cap, NVDI(normalized difference vegetation index), and supervised classification techniques were used to analyze the distribution of sediments and the aspect of topographical variations caused by artificial human actions. The total amount of the exposed tidal flat was estimated on the basis of the database snch as aerial photography, hydrographic chart, geological map, and scheme drawing in the Siwha area. The possible excavation regions for a seawall were predicted analyzing the supervised classification image of Landsat TM data. Tasseled cap images were used to observe the distribution of sediments. The difference of the NDVI images between spring and summer seasons indicates that deciduous and coniferous forests were distributed over the whole areas. The total fill-volume of the exposed Siwha tidal flat and the fill-volume of the construction planning seawall were calculated as $581,485,354\textrm{m}^3{\;}and{\;}3,387,360\textrm{m}^3$, respectively, from the digital terrain analysis. Daebu Island, Sunkam Island, and the part of Songsan-myeon were chosen as the cut area to make the seawall, and their cut-volumes were estimated as $5,229,576\textrm{m}^3,{\;}79,227,072\textrm{m}^3,{\;}and{\;}47,026,008\textrm{m}^3$, respectively. Therefore, the cut-volume of Daebu Island alone among three areas was sufficient to make the seawall.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.8
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• pp.95-101
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• 2009

Random numbers are used in many sorts of applications. Some applications, like simple software simulation tests, communication protocol verifications, cryptography verification and so forth, need various levels of randomness with various process speeds. In this paper, we propose a fast pseudorandom generator module for embedded systems. The generator module is implemented in hardware which can run in two modes, one of which can generate random numbers with higher randomness but which requires six cycles, the other providing its result within one cycle but with less randomness. An ASIP (Application Specific Instruction set Processor) was designed to implement the proposed pseudorandom generator instruction sets. We designed a processor based on the MIPS architecture,, by using LISA, and have run statistical tests passing the sequence of the Diehard test suite. The HDL models of the processor were generated using CoWare's Processor Designer and synthesized into the Dong-bu 0.18um CMOS cell library using the Synopsys Design Compiler. With the proposed pseudorandom generator module, random number generation performance was 239% faster than software model, but the area increased only 2.0% of the proposed ASIP.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.796-806
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• 2014

The key for the commercial deployment of IGCC power plants or chemical (methanol, dimethyl ether, etc.) production plants based on coal gasification is their economic advantage over plants producing electricity or chemicals from crude oil or natural gas. The better economy of coal gasification based plants can be obtained by co-production of electricity and chemicals. In this study, we carried out the economic feasibility analysis on the process of co-producing electricity and DME (dimethyl ether) using coal gasification. The plant's capacity was 250 MW electric and DME production of 300,000 ton per year. Assuming that the sales price of DME is 500,000 won/ton, the production cost of electricity is in the range of 33~58% of 150.69 won/kwh which is the average of SMP (system marginal price) in 2013, Korea. At present, the sales price of DME in China is approximately 900,000 won/ton. Therefore, there are more potential for lowering the price of co-produced electricity when comparing that from IGCC only. Since the co-production system can not only use the coal gasifier and the gas purification process as a common facility but also can control production rates of electricity and DME depending on the market demand, the production cost of electricity and DME can be significantly reduced compared to the process of producing electricity or DME separately.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.4
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• pp.372-378
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• 2014

Noise in biomedical X-ray image degrades the quality so that it might causes to decrease the accuracy of diagnosis. Especially the noise reduction techniques is quite essential for low-dose biomedical X-ray images obtained from low radiation power in order to protect patients, because their noise level is usually high to well discriminate objects. This paper proposes an efficient method to remove the noise in low-dose X-ray images while preserving the edges with diverse resolutions. In the proposed method, a noisy image is at first decomposed into several images with different resolutions in pyramidal representation, then the stable map of edge confidence is obtained from each of analyzed image using a fuzzy logic-based edge detector. This map is used to adaptively determine the parameter for guided filters, which eliminate the noise while preserving edges in the corresponding image. The filtered images in the pyramid are extended and synthesized into a resulted image using interpolation technique. The superiority of proposed method compared to the median, bilateral, and guided filters has been experimentally shown in terms of noise removal and edge preserving properties.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.503-512
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• 2018

SAR(Synthetic Aperture Radar) is a technology to acquire images by processing signals obtained from radar, and there is an increasing demand for utilization of high-resolution SAR images. In this paper, for high-speed processing of high-resolution SAR image data, a study for SAR image processing algorithms to achieve optimal performance in multi-core based computer architecture is performed. The performance deterioration due to a large amount of input/output data for high resolution images is reduced by maximizing the memory utilization, and the parallelization ratio of the code is increased by using dynamic scheduling and nested parallelism of OpenMP. As a result, not only the total computation time is reduced, but also the upper bound of parallel performance is increased and the actual parallel performance on a multi-core system with 10 cores is improved by more than 8 times. The result of this study is expected to be used effectively in the development of high-resolution SAR image processing software for multi-core systems with large memory.