• Korean Journal of Materials Research
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• v.19 no.8
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• pp.437-442
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• 2009

This paper describes an improved strategy for controlling the adhesion force using both the antiadhesion and adhesion layers for a successful large-area transfer process. An MPTMS (3-mercaptopropyltrimethoxysilane) monolayer as an adhesion layer for Au/Pd thin films was deposited on Si substrates by vapor self assembly monolayer (VSAM) method. Contact angle, surface energy, film thickness, friction force, and roughness were considered for finding the optimized conditions. The sputtered Au/Pd ($\sim$17 nm) layer on the PDMS stamp without the anti-adhesion layer showed poor transfer results due to the high adhesion between sputtered Au/Pd and PDMS. In order to reduce the adhesion between Au/Pd and PDMS, an anti-adhesion monolayer was coated on the PDMS stamp using FOTS (perfluorooctyltrichlorosilane) after $O_2$ plasma treatment. The transfer process with the anti-adhesion layer gave good transfer results over a large area (20 mm $\times$ 20 mm) without pattern loss or distortion. To investigate the applied pressure effect, the PDMS stamp was sandwiched after 90$^{\circ}$ rotation on the MPTMS-coated patterned Si substrate with 1-${\mu}m$ depth. The sputtered Au/Pd was transferred onto the contact area, making square metal patterns on the top of the patterned Si structures. Applying low pressure helped to remove voids and to make conformal contact; however, high pressure yielded irregular transfer results due to PDMS stamp deformation. One of key parameters to success of this transfer process is the controllability of the adhesion force between the stamp and the target substrate. This technique offers high reliability during the transfer process, which suggests a potential building method for future functional structures.

• International Journal of Contents
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• v.5 no.3
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• pp.50-56
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• 2009

Internet is being used for several activities by a great range of users. These activities include communication, e-commerce, education, and entertainment. Users are required to register regarding website in order to enroll web activities. However, registration can be done by automated hacking software. That software make false enrollments which occupy the resources of the website by reducing the performance and efficiency of servers, even stop the entire web service. It is crucial for the websites to have a system which has the capability of differing human users and computer programs in reading images of text. Completely Automated Public Turing Test to Tell Computers and Human Apart (CAPTCHA) is such a defense system against Optical Character Recognition (OCR) software. OCR can be defined as software which work for defeating CAPTCHA images and make countless number of registrations on the websites. This study proposes a new CAPTCHA context that is Korean CAPTCHA by means of the method which is splitting CAPTCHA images into several parts with random rotation values, and drawing random lines on a grid background by using Korean characters only. Lines are in the same color with the CAPTCHA text and they provide a distortion of image with grid background. Experimental results show that Korean CAPTCHA is a more secure and effective CAPTCHA type for Korean users rather than current CAPTCHA types due to the structure of Korean letters and the algorithm we are using: rotation and splitting. In this paper, the algorithm of our method is introduced in detail.

• The Journal of the Acoustical Society of Korea
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• v.15 no.4
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• pp.43-49
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• 1996

This research proposes a system for speaker independent Korean continuous speech recognition with 247 DDD area names using keyword spotting technique. The applied recognition algorithm is the Dynamic Programming Neural Network(DPNN) based on the integration of DP and multi-layer perceptron as model that solves time axis distortion and spectral pattern variation in the speech. To improve performance, we classify word model into keyword model and non-keyword model. We make an experiment on postprocessing procedure for the evaluation of system performance. Experiment results are as follows. The recognition rate of the isolated word is 93.45% in speaker dependent case. The recognition rate of the isolated word is 84.05% in speaker independent case. The recognition rate of simple dialogic sentence in keyword spotting experiment is 77.34% as speaker dependent, and 70.63% as speaker independent.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.251-269
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• 2013

Measurement of deflections of certain bridges is usually hampered by corruption of the GPS signal by multipath associated with passing vehicles, resulting to unrealistically large apparent displacements. Field data from the Gorgopotamos train bridge in Greece and systematic experiments revealed that such bias is due to superimposition of two major effects, (i) changes in the geometry of satellites because of partial masking of certain satellites by the passing vehicles (this effect can be faced with solutions excluding satellites that get temporarily blocked by passing vehicles) and (ii) dynamic multipath caused from reflection of satellite signals on the passing trains, a high frequency multipath effect, different from the static multipath. Dynamic multipath seems to have rather irregular amplitude, depending on the geometry of measured satellites, but a typical pattern, mainly consisting of a baseline offset, wide base peaks correlating with the sequence of main reflective surfaces of the vehicles passing next to the antenna. In cases of limited corruption of GPS signal by dynamic multipath, corresponding to scale distortion of the short-period component of the GPS waveforms, we propose an algorithm which permits to reconstruct the waveform of bridge deflections using a weak fusion of GPS and RTS data, based on the complementary characteristics of the two instruments. By application of the proposed algorithm we managed to extract semi-static and dynamic displacements and oscillation frequencies of a historical railway bridge under train loading by using noisy GPS and RTS recordings. The combination of GPS and RTS is possible because these two sensors can be fully collocated and have complementary characteristics, with RTS and GPS focusing on the long- and short-period characteristics of the displacement, respectively.

• Journal of Fashion Business
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• v.12 no.3
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• pp.99-115
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• 2008

International exchange gets active in nations with the increase of Internet use and heading toward digital age. Thus the communication conveying image of nations effectively plays an important role in an international society. Sports events are regarded as important international exchange events and good opportunities for public relations of one's own country and taken as tools of planting good images in other nations. This study surveyed the concept and history of uniform through the documents and previous studies in order to find the aesthetic characteristics of sportswear uniform applying the image of national ensign and investigates the origin and start time in Korea of selected 6 sports items. As a result of finding the expression way of ensign image and drawing the aesthetic characteristics by analyzing the use and variation of ensign colors, the use of colors other than ensign and reflection of ensign form in collected 60 sports uniforms, this study could draw the symbolical beauty, beauty of variation and beauty of brevity. First, symbolical beauty is the aesthetic characteristics expressing uniforms by using the pattern ensign symbolizes and ensign colors themselves or enlarging a part of ensign. Second, beauty of variation is the aesthetic characteristics creating geometrical new patterns in uniform through the distortion and exaggeration of ensign shape, or transforming the colors themselves of ensign. Third, beauty of brevity is the aesthetic characteristics using other colors only as decorative factor while applying the main colors of ensign to the most part of uniform, or unifying the uniforms with only one color of ensign. As a result of survey, the proportion of the symbolical beauty was highest in summer season and beauty of brevity and beauty of variation followed and the proportion of beauty of variation was highest and the symbolical beauty and beauty of brevity followed after that in winter season. This study found the way of expressing image of one's own country in sports uniform through this article, expecting the exact recognition on sports uniform and the diversity of sports uniform design in which the images of the nation are expressed more variously.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.6
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• pp.525-534
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• 2018

Camera calibration is the process of determining the parameters such as the focal length of a camera, the position of a principal point, and lens distortions. For this purpose, images of checkerboard have been mainly used. When targets were automatically recognized in checkerboard image, the existing studies had limitations in that the user should have a good understanding of the input parameters for recognizing the target or that all checkerboard should appear in the image. In this study, a methodology for automatic target recognition was proposed. In this method, even if only a part of the checkerboard image was captured using rectangles including eight blobs, four each at the central portion and the outer portion of the checkerboard, the index of the target can be automatically assigned. In addition, there is no need for input parameters. In this study, three conditions were used to automatically extract the center point of the checkerboard target: the distortion of black and white pattern, the frequency of edge change, and the ratio of black and white pixels. Also, the direction and numbering of the checkerboard targets were made with blobs. Through experiments on two types of checkerboards, it was possible to automatically recognize checkerboard targets within a minute for 36 images.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.2
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• pp.128-134
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• 2019

In shipbuilding, accurate fabrication of curved hull plates is one of the most important steps, since the shape of ship hull, which is very critical in the overall performance of a ship, is a collection of such plates. The curved hull plates forming process requires a significant amount of time by skilled workers in shipbuilding. In general, the workers cause thermal distortion in the plate and forming initial shape using gas heat source. So shipbuilding companies need skilled workers who have long experience. To solve the problem, a lot of researchers tried to develop automation system for curved hull plates. In this paper, we propose automatic heating system with gantry robot, high frequency induction heater to replace the gas heat source and automatic measurement system. We apply the system to forming concave type plate that is actually used in ship manufacturing. In addition, a system was developed to automatically generate heating information, such as the heating location and the heating speed, for actual heating process. Then the system was applied to the actual heating material. It is shown that the proposed triangle heating pattern makes desired concave shape successfully. The induction heating system showed that it can be used for automation system of curved hull plates forming process replacing gas heat source.

• Korean Journal of Optics and Photonics
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• v.35 no.4
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• pp.164-169
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• 2024

We applied recursive numerical computation to create a basic design of a camera optical module for mobile phones. To enhance the resolution performance for a 38-degree field of view, we constructed the optical system with six non-spherical lenses. However, to increase its applicability to a compact mobile phone, we limited the overall length to 5 mm in the design. Using the data obtained from the basic design, we proceeded with optimization design using the Zemax design tool. The optimized optical system achieved a resolution performance with a modulation transfer function value of more than 19% for a 280 lines/mm pattern and image distortion within 1.0% for all wavelength rays. In this paper, we verify the feasibility of using recursive numerical computation for the basic design of a compact mobile phone camera.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.2
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• pp.75-79
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• 2017

Honeycomb-shaped Ag-grid transparent conductive electrodes (TCEs) were fabricated using two different processes, high density plasma etching and lift-off, and the optical and electrical properties were compared according to the fabrication method. For the fabrication of the Ag-grid TCEs by plasma etching, etch characteristics of the Ag thin film in $10CF_4/5Ar$ inductively coupled plasma (ICP) discharges were studied. The Ag etch rate increased as the power increased at relatively low ICP source power or rf chuck power conditions, and then decreased at higher powers due to either decrease in $Ar^+$ ion energy or $Ar^+$ ion-assisted removal of the reactive F radicals. The Ag-grid TCEs fabricated by the $10CF_4/5Ar$ ICP etching process showed better grid pattern transfer efficiency without any distortion or breakage in the grid pattern and higher optical transmittance values of average 83.3 % (pixel size $30{\mu}m/line$ width $5{\mu}m$) and 71 % (pixel size $26{\mu}m/line$ width $8{\mu}m$) in the visible range of spectrum, respectively. On the other hand, the Ag-grid TCEs fabricated by the lift-off process showed lower sheet resistance values of $2.163{\Omega}/{\square}$ (pixel size $26{\mu}m/line$ width $18{\mu}m$) and $4.932{\Omega}/{\square}$ (pixel size $30{\mu}m/line$ width $5{\mu}m$), respectively.

• Journal of Yeungnam Medical Science
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• v.5 no.1
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• pp.33-42
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• 1988

The abdominal tumors in children are different from those of adult. These tumors are the third most common one, preceded by leukemia and brain tumors, in children under 15 years. X-ray examination is the most important method among diagnostic approaches. The role of diagnostic imaging is to identify the precise anatomic location and extent of pathologic process with the minimal number of imaging procedures. 23 cases of abdominal tumors were reviewed in respect of age incidence, site of origin, radiologic findings. The results are briefly summarized as follows : 1. Neuroblastoma was the most common(6 cases) and wi1m's tumor(5 cases), choledocal cyst(4 cases), ovarian mass(3 cases), hydronephrosis(2 cases), were descending order in frequency. 2. The most common site was retroperitoneum(60%). Kidney was the single most common site of origin. 3. Radiologic findings. The most common findings of plain radiography was ill defined soft tissue mass and this method was helpful in the presence of calcification especially in neuroblastoma. Ultrasonographic pattern was anechoic(cystic), echoic or mixed pattern, but this method provide less precise anatomical details, nevertheless ultrasonography wes paticullary useful imaging modality for the pediatric abdominal tumors. IVP findings were renal displacement, caliceopelvic system distortion or nonvisualization of kidney, these information was helpful in determining the location of tumors. CT scan showed homogenous or inhomogenous, cystic or solid, mass with their anatomic location. 4. Ultrasonography was the most widely used specific diagnostic method, but had limited value in detecting the anatomic location of tumors. CT scan was superior to ultrasound for determining the extent of tumors.