• Journal of Digital Contents Society
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• v.16 no.4
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• pp.583-593
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• 2015

Today, caused by the growth of computer and communication technology, multimedia, especially image data are being used in different application divisions. JPEG2000 that is widely used these days provides a Region-of-Interest(ROI) technique. The extraction of ROI has to be rapidly executed and automatically extracted in a huge amount of image because of being seen preferentially to the users. For this purpose, this paper proposes a method about preferential processing and automatic extraction of ROI using the distribution of edge in the code block of JPEG2000. The steps are the extracting edges, automatical extracting of a practical ROI, grouping the ROI using the ROI blocks, generating the mask blocks and then quantization, ROI coding which is the preferential processing, and EBCOT. In this paper, to show usefulness of the method, we experiment its performance using other methods, and executes the quality evaluation with PSNR between the images not coding an ROI and coding it.

• The Journal of the Acoustical Society of Korea
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• v.19 no.8
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• pp.68-77
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• 2000

Line special frequency (LSF) parameters have been widely used in low bit-rate speech coding due to their efficiency for representing the short-time speech spectrum. In this paper, a new distance measure based on the masking properties of human ear is proposed for quantizing LSF parameters whereas most conventional quantization methods are based on the weighted Euclidean distance measure. The proposed method derives the perceptual distance measure from the definition of noise-to-mask ratio (NMR) which has high correspondence with the actual distortion received in the human ear and uses it for quantizing LSF parameters. In addition, we propose an adaptive bit allocation scheme, which allocates minimal bits to LSF parameters maintaining the perceptual transparency of given speech frame for reducing the average bit-rates. For the performance evaluation, we has shown the ratio of perceptually transparent frames and the corresponding average bit-rates for the conventional and proposed methods. By jointly combining the proposed distance measure and adaptive bit allocation scheme, the proposed system requires only 770 bps for obtaining 95.5% perceptually transparent frames, while the conventional systems produce 89.9% at even 1800 bps.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.6
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• pp.867-873
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• 2018

Recently, interests in the field of image processing have increased with the increased demand for digital imaging devices. However, digital images are damaged by the noise generated by various causes during image processing. Generally in digital imaging devices, noise such as AWGN, etc. is generated and performance and reliability are deteriorated, and various researches are in progress to remove it. Accordingly in the present paper, an algorithm to protect the high frequency components of the images and to efficiently remove AWGN is proposed. The proposed algorithm calculates the final output by adjusting estimate values applied with Gaussian mask and weight values applied according to the local mask distribution. And for performance evaluation of the proposed algorithm, simulations were performed with the existing methods, and the characteristics were compared through PSNR and the processed, enlarged images.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.179-190
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• 1999

To automate the polishing process, a polishing robot with two axes which is attached to a machining center with three axes has been developed by our previous research. This automatic polishing robot is able to keep the polishing tool normal to the curved surface of die and is able to maintain a constant pneumatic pressure. Therefore, in the case of a curved surface die, the surface roughness to be polished by the system with five axes is improved superior than the surface by a three-axis machining center. However, because the polishing robot was big and heavy, a polishing workspace was limited and then it was difficult to attach the robot to machining center. In this study, the smaller and lighter polishing robot than the previous has been designed to improve defects due to the magnitude and weight of the robot. And the sliding mode control ins applied to polishing robot to improve the tracking performance. To obtain switching parameters of sliding mode control, the signal compression method is used. Code separation program to separate the date for a three-axis machining center and a two-axis polishing robot from a five-axis NC data is improved for users to check conveniently the separated trajectory and to handle many data by using the graphic user interface. To evaluate the polishing performance of the developed robot, the polishing experiment for shadow mask was carried out. The result shows the automatic polishing robot has a good trajectory tracking performance and obtains a good polished workpiece efficiently under recommended polishing conditions.

• Journal of Environmental Health Sciences
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• v.50 no.4
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• pp.267-273
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• 2024

Background: During the coronavirus pandemic, masks played a critical role in preventing respiratory infections. While the performance of masks such as KF-certified masks and N95 masks was evaluated and managed by the authorities, the performance of common masks was not. Objectives: This study aimed to evaluate the performance of uncertified masks in four Asian countries against certification standards (Korean KF80, KF94, and US N95). Methods: Thirty uncertified mask products from Indonesia, 20 from South Korea, 26 from Taiwan, and 30 from Thailand were purchased to perform performance evaluations. The uncertified masks included disposable dental masks, cloth masks, and children's masks. Filtration efficiency and inhalation airflow resistance tests were conducted according to Korean KF80, KF94, and US N95 protocols. Results: None of the 106 identified masks complied with the KF94 standard. A few complied with the KF80 standard: four from Indonesia, four from South Korea, 13 from Taiwan, and 16 from Thailand. Some of the masks met the N95 standard: one from Indonesia, three from South Korea, two from Taiwan, and one from Thailand. Conclusions: Since many uncertified masks did not comply with performance standards, wearing them might not have provided sufficient protection. Performance of uncertified masks could provide critical information for next pandemic management.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.715-721
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• 2000

In this research, rule and neuro net based boundary extraction algorithm was developed. Extracting boundary of the interest, lean tissue, is essential for the quality evaluation of the beef based on color machine vision. Major quality features of the beef are size, marveling state of the lean tissue, color of the fat, and thickness of back fat. To evaluate the beef quality, extracting of loin parts from the sectional image of beef rib is crucial and the first step. Since its boundary is not clear and very difficult to trace, neural network model was developed to isolate loin parts from the entire image input. At the stage of training network, normalized color image data was used. Model reference of boundary was determined by binary feature extraction algorithm using R(red) channel. And 100 sub-images(selected from maximum extended boundary rectangle 11${\times}$11 masks) were used as training data set. Each mask has information on the curvature of boundary. The basic rule in boundary extraction is the adaptation of the known curvature of the boundary. The structured model reference and neural net based boundary extraction algorithm was developed and implemented to the beef image and results were analyzed.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.108-113
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• 2016

A miniaturized lab-scale Cu plating cell for the metallization of electronic devices was fabricated and its deposit uniformity and profile were investigated. The plating cell was composed of a polypropylene bath, an electrolyte ejection nozzle which is connected to a circulation pump. In deposit uniformity evaluation, thicker deposit was found on the bottom and sides of substrate, indicating the spatial variation of deposit thickness was governed by the tertiary current distribution which is related to $Cu^{2+}$ transport. The surface morphology of Cu deposit inside photo-resist pattern was controlled by organic additives in the electrolyte as it led to the flatter top surface compared to convex surface which was observed in the deposit grown without organic additives.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.71-77
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• 1996

This paper describes the development of on the machine measuring(OMM) system which can directlry measure the three dimensional machined dimensilnal accuracy using scanning probe in milling machine. Two algolithms, continuous path(CP) measurement using UC program and CAD data assisted point to point(PTP) measurement, were developed regarding specification of scanning probe. The OMM system was contructed to verify the developed system suing the proposed algorithm, and actually measured three kinds of machined TV shadow mask molds. The developed system was evaluated it's repeatability and compared with the current measurement system of CMM(Coording Measuring Machine) in terms of relative accuracy and time reduction and productivity increase.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1657-1662
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• 2017

Facial expression recognition systems using video devices have emerged as an important component of natural human-machine interfaces which contribute to various practical applications such as security systems, behavioral science and clinical practices. In this work, we present a new method to analyze, represent and recognize human facial expressions using a sequence of facial images. Under our proposed facial expression recognition framework, the overall procedure includes: accurate face detection to remove background and noise effects from the raw image sequences and align each image using vertex mask generation. Furthermore, these features are reduced by principal component analysis. Finally, these augmented features are trained and tested using Hidden Markov Model (HMM). The experimental evaluation demonstrated the proposed approach over two public datasets such as Cohn-Kanade and AT&T datasets of facial expression videos that achieved expression recognition results as 96.75% and 96.92%. Besides, the recognition results show the superiority of the proposed approach over the state of the art methods.

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.205-211
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• 1998

The MTF(modulation transfer function) measuring system with a linear CCD(charge coupled-device) was constructed to cvaluate a color CRT(catode ray tube). The measured MTF values were corrected by considering the spectral response and the pixel sizes of CCD. The effects of a spot size, video bandwidth, pitch of shadow mask holes, display luminance, and ambient illumination on image quality were studied. The uniformity of resolution and the contrast Ioss by ambient light of the color CRT monitor were measured, and the results were analyzed by MTFA(modulation threshold area).