• International Journal of Precision Engineering and Manufacturing
• /
• v.4 no.1
• /
• pp.23-29
• /
• 2003

Stencil is used normally as a mask for solder pasting on pad of a printed circuit board (PCB). The objective of this study is to develop a stencil cutting system and determine the optimal conditions to make good-quality stencil by using a Nd:YAG laser. The effects of process parameters such as laser power, type of mask, gas pressure, cutting speed and pulse duration on the cut edge quality were investigated. In order to analyze the cut surface characteristics (roughness, kerfwidth, dross) optical microscopy, SEM microscopy and roughness measurements were used. As a result, the optimal conditions of cutting process parameters were determined, and the practical feasibility of the proposed system was also examined by using a commercial Gerber file for PCB stencil manufacturing.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.13 no.10
• /
• pp.805-811
• /
• 2000

Reliability of PBGA(plastic ball grid array) package is weak compared with normal plastic packages. The low reliability is caused by low resistance to the popcorn cracking, which is generated by moisture absorption in PCB(prited circuit board). In this paper, plasma treatment process was used and we analyzed its effects to interface adhesion. The contents of C and Cl decrease after plasma treatment but those of O, Ca, N relatively increase. The plasma treatment improves the adhesion between EMC(epoxy molding compound) and PCB(solder mask). The grade of improvement was over 100% Max, which depends on the properties of EMC. The RMS(root mean square) roughness value of the solder mask surface increases to plasma treatment. There is little difference of adhesion in RF power and treatment time.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.285-285
• /
• 2011

EUVL (Extreme Ultra Violet Lithography) is one of competitive lithographic technologies for sub-30nm fabrication of nano-scale Si devices that can possibly replace the conventional photolithography used to make today's microcircuits. Among the core EUVL technologies, mask fabrication is of considerable importance since the use of new reflective optics having a completely different configuration compared to those of conventional photolithography. Therefore new materials and new mask fabrication process are required for high performance EUVL mask fabrication. This study investigated the etching properties of SnO2 (Tin Oxide) as a new absorber material for EUVL binary mask. The EUVL mask structure used for etching is SnO2 (absorber layer) / Ru (capping / etch stop layer) / Mo-Si multilayer (reflective layer) / Si (substrate). Since the Ru etch stop layer should not be etched, infinitely high selectivity of SnO2 layer to Ru ESL is required. To obtain infinitely high etch selectivity and very low LER (line edge roughness) values, etch parameters of gas flow ratio, top electrode power, dc self - bias voltage (Vdc), and etch time were varied in inductively coupled Cl2/Ar plasmas. For certain process window, infinitely high etch selectivity of SnO2 to Ru ESL could be obtained by optimizing the process parameters. Etch characteristics were measured by on scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses. Detailed mechanisms for ultra-high etch selectivity will be discussed.

• The Korean Journal of Pain
• /
• v.34 no.2
• /
• pp.241-245
• /
• 2021

Background: It has been reported that a new type of headache may develop as a result of face mask use during the COVID-19 pandemic. The aim of this study is to investigate the clinical features of face mask-related headache during the COVID-19 pandemic. Methods: This is a cross-sectional study carried out on healthcare workers at the Afyonkarahisar Health Sciences University. The number of workers at our university was established. Sample size was calculated using the G*Power program. A questionnaire consisting of questions relating to pre-existing headache, an aggravation in headache, and de-novo headache was filled out by 3 neurologists with all participants. Results: Data was collected from a total of 375 participants, after the exclusion of 5 individuals who refused to participate. Out of all participants, 26 (6.9%) used a filtering mask, 274 (73.1%) used a surgical mask, 75 (20.0%) participants used a combination of both masks. The number of participants with preexisting headache was 114 (30.4%) had pre-existing headache. Of those with pre-existing headache, 77 (67.5%) healthcare workers had reported an aggravation in their headache after mask use. De-novo headache was observed in 116 (30.9%) of participants. De-novo headache characteristics included throbbing in 17 (14.7%) participants and pressing in 99 (85.3%) participants. In addition, symptoms such as tachypnea, sleep disturbance, and fatigue were found to be significantly higher. Conclusions: This study indicates that healthcare workers develop headaches due to use of masks during the COVID-19 outbreak.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.21 no.1
• /
• pp.129-143
• /
• 1997

This study is about'The Costumes of Ch'oyong dance. (namely Ch'oyong-mu-bok; 처용무복)': emphasis on its structure and change. 1 studied Akhakguebum (the book of music and dance; 낙학궤범), Eui-Gue-Do (a collection of a series of paintings showing the whole processes of the royal courtesies and ceremonies; 의궤도) and some genre painting (풍증화). 'The costumes of Ch'oyong-Dance'were composed of robe(의), pants-skirt(대) , outer-skirt (상) , scarf-string(천의·길경) , shirt(한삼) , hat with mask (사교·가면) , belt(대) and shoes (혜) . According to the position, the colours of robe(의) and pants-skirt(군) were different. What is called, it is'the Colour of Five-Position (오방색) .'The Costumes of choyong-Dance' can be divided three factors by its symbolic means; i. e. shamanism, buddhism and bureaucratism. The pants-skirt(군), outer-skirts(상), scarf · string(천의·길경) and mask are considered as shamanic factor. However, the scarf(천의) , string(길경) and patterns(만화)which are decorated with many lotus patterns enclosed with vine are considered as buddhistic factor. And the hat (사모) , robe(의) , outer-skirt(상) , belt(대) and shoes(잔) are considered as bureaucratic factor. Ch'oyong is endowed with some power by these factors, and its symbolic means became stronger and enlarged by 'the Colour of five-position'. As time goes, the forms and details of robe had been changed noticeable; sleeve-width, neck-line and patterns. The shamanic, buddhistic and bureaucratic factors are reduced. These changes were derived from the changes of Ch'oyong·Dance. On the ground of the shape of mask and round-neckline robe(단영) , someone has an opinion that Ch'oyong is an aribian. However, according to this study, Ch'oyonh is Korean traditional thing; round-neckline robe already existed and settled in Silla dynasty and Ch'oyong-mask symbolized shamanic power.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.7
• /
• pp.1716-1725
• /
• 1996

In this paper, the huffman decoder which is a part of the decoder in JPEG standard format is designed by using a new Ternary CAM. First, the 256 word * 16 bit-size new bit-word all parallel Ternary CAM system is designed and verified using SPICE and CADENCE Verilog-XL, and then the verified novel Ternary CAM is applied to the new huffman decoder architecture of JPEG. So the performnce of the designed CAM cell and it's block is verified. The new Ternary CAM has various applications because it has search data mask and storing data mask function, which enable bit-wise search and don't care state storing. When the CAM is used for huffman look-up table in huffman decoder, the CAM is partitioned according to the decoding symbol frequency. The scheme of partitioning CAM for huffman table overcomes the drawbacks of all-parallel CAM with much power and load. So operation speed and power consumption are improved.

• Journal of Internet Computing and Services
• /
• v.20 no.5
• /
• pp.105-111
• /
• 2019

Core technologies that lead the Fourth Industrial Revolution era, such as artificial intelligence, big data, and autonomous driving, are implemented and serviced through the rapid development of computing power and hyper-connected networks based on the Internet of Things. In this paper, we implement two different models for drivable area segmentation in various environment, and propose a better model by comparing the results. The models for drivable area segmentation are using DeepLab V3+ and Mask R-CNN, which have great performances in the field of image segmentation and are used in many studies in autonomous driving technology. For driving information in various environment, we use BDD dataset which provides driving videos and images in various weather conditions and day&night time. The result of two different models shows that Mask R-CNN has higher performance with 68.33% IoU than DeepLab V3+ with 48.97% IoU. In addition, the result of visual inspection of drivable area segmentation on driving image, the accuracy of Mask R-CNN is 83% and DeepLab V3+ is 69%. It indicates Mask R-CNN is more efficient than DeepLab V3+ in drivable area segmentation.

• Current Optics and Photonics
• /
• v.8 no.4
• /
• pp.355-365
• /
• 2024

Wavefront coding (WFC) imaging systems can redistribute the energy of an interference laser spot on an image plane sensor by wavefront phase modulation and reduce the peak intensity, realizing laser protection while maintaining imaging functionality by leveraging algorithmic post-processing. In this paper, a spiral axicon WFC imaging system is proposed, and the performance for laser protection is investigated by constructing a laser transmission model. An Airy disk on an image plane sensor is refactored into a symmetrical hollow ring by a spiral axicon phase mask, and the maximum intensity can be reduced to lower than 1% and single-pixel power to 1.2%. The spiral axicon phase mask exhibits strong robustness to the position of the interference laser source and can effectively reduce the risk of sensor damage for an almost arbitrary lase propagation distance. Moreover, we revealed that there is a sensor hazard distance for both conventional and WFC imaging systems where the maximum single-pixel power reaches a peak value under irradiation of a power-fixed laser source. Our findings can offer guidance for the anti-laser reinforcement design of photoelectric imaging systems, thereby enhancing the adaptability of imaging systems in a complex laser environment. The laser blinding-resistant imaging system has potential applications in security monitoring, autonomous driving, and intense-laser-pulse experiments.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.11 no.8
• /
• pp.1589-1595
• /
• 2007

Recently many communication systems ate adapting the OFDM(Orthogonal Frequency Division Multiplexing) for multimedia data services. However, OFDM has some problems that PAPR is increased when sub-carries are summed up with same phases. This problem causes severe signal distortions while the signal is passing through non-linear system such as power amplifier resulting in performance degradation of transmission system. In this paper, we use IF-Clipping method to solve PAPR problem and the signal distortion caused by clipping is limited by use of SAW (Surface Acoustic Wave) filter and power amplifier(TWTA). And we derive the optimal parameter(PAPR, Backoff) values to meet the spectrum mask of WiBro system.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.10
• /
• pp.72-82
• /
• 1999

The error diffusion algorithm is excellent for reproducing continuous gray-scale images to bianry images and also has good edge characteristics. However, it is well known that artifacts with objectionable patterns can occur in the halftoned images. On the other hand, a halftone algorithm using blue noise mask has been proposed. where the halftoning is achieved by a pixelwise comparison of gray-scale image with an array, the blue noise mask. It doesn't have pattern artifacts, but the halftoned image looks unclear because the quantization errors are not feedbacked compared to the error diffusion. In this paper, edge enhanced error diffusion which dithers the threshold with the blue noise mask is proposed. We show that the proposed algorithm can produce unstructured and edge enhanced halftone images. This algorithm is analyzed by the concept of an equivalent input image. The performace of the proposed algorithm is compared with that of the conventional halftoning by measuring the radially averaged power spectrum and edge correlation.