• 문화기술의 융합
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• 제8권5호
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• pp.713-721
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• 2022

LED 비디오월을 방송 현장에서 사용하기 위해서는 몇 가지 알아두어야 할 사항이 있다. 첫째, 픽셀이 촘촘히 배열되어 있기 때문에 짧은 배열 주기로 인한 무아레 현상이 나타날 수 있고, 둘째, 픽셀 간의 거리(픽셀피치)가 촬영하는 카메라 이미지 센서에 기록될 수 있다. 무아레 현상이 발생하거나 픽셀피치가 관찰되게 되면 시청자의 입장에서는 불편함을 느끼게 된다. 무아레 현상은 카메라의 촬영거리나 각도를 조정하면서 감소시킬 수 있지만, 픽셀피치가 이미지 센서에 녹화되는 걸 방지하기 위해서는 LED 비디오월과 카메라와의 거리를 충분히 확보하거나, 거리가 확보된 상태에서도 픽셀피치가 녹화되지 않도록 방송 현장에서 사용되는 줌렌즈의 배율을 적절하게 변화시켜 운용해야 한다. 원하는 화각을 얻기 위해 배율을 변경시켜 초점거리를 변동시키게 되면 의도치 않게 픽셀피치가 녹화되는 결과를 초래할 수 있다. 본 논문에서는 비디오월과의 거리가 충분히 확보된 상태에서 줌렌즈의 배율을 변경하면서 픽셀피치가 관찰되지 않는 범위에 대해 알아보았다. LED 비디오월에 영상을 재생시켜 B4 마운트 줌렌즈를 장착한 HD 카메라와 서버를 사용해 LED 비디오월 상태를 녹화하였고, TV 화면으로 재생하여 픽셀피치가 관찰되는지 확인해 보았다.

• IEIE Transactions on Smart Processing and Computing
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• 제6권2호
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• pp.76-84
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• 2017

This paper presents an efficient method for generating spatiotemporal images in order to detect leukocyte motion in microvessels. Leveraging the constraint that leukocytes move along the contour line of the blood vessel wall, our proposed method efficiently generates spatiotemporal images for leukocyte motion detection. To that end, translational motion caused by in vivo movement is first removed by a template matching method. Second, the blood vessel region is detected by an automatic threshold selection method in order to binarize temporal variance images. Then, the contour of the blood vessel wall is expressed via B-spline function. Finally, using the detected blood vessel wall's contour as an initial curve, the plasma layer for the most accurate position is determined in order to find the spatial axis via snake, and the spatiotemporal images are generated. Experimental results show that the spatiotemporal images are generated effectively through comparison of each step with three images.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1315-1317
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• 2008

The plasma display panel is an image expression display using gas discharge. However gas discharge characteristics vary with temperature. Furthermore, the potential difference among three electrodes appears in sustain period due to external applied voltages. It affects to the wall charge state accumulated on the electrodes. This research aims at identifying that the discharge characteristics depend on the potential difference and temperature. The results show that the wall charge loss increases with increase of the number of applied pulse during sustain period and it severely appears at high temperature.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.671-674
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• 2008

We investigate the slippage effect in a micro-channel depending on the surface characteristics; hydrophilic, hydrophobic, and super-hydrophobic wettabilities. The micro-scale grooves are fabricated on the vertical wall to make the super-hydrophobic surfaces, which enable us visualize the flow fields near walls and directly measure the slip length. Velocity profiles are measured using micro-particle image velocimetry (Micro-PIV) and compared those in the hydrophilic glass, hydrophobic PDMS, and super-hydrophobic PDMS micro-channels. To directly measure the velocity in the super-hydrophobic micro-channel, the transverse groove structures are fabricated on the vertical wall in the micro-channel. The velocity profile near the wall shows larger slip length and, if the groove structure is high and wide, the liquid meniscus forms curves into the valley so that the wavy flow is created after the grooves.

• 대한기계학회논문집B
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• 제31권10호
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• pp.889-894
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• 2007

The effect of the axial slit of outer cylinder on Taylor-Couette flow was experimentally investigated. The radius ratio and aspect ratio of the model was 0.825 and 48, respectively. The depth of slits was 5mm and total 18 slits were azimuthally located along the inner wall of outer cylinder. We used PIV method to measure the flow field and applied refractive index matching method to resolve the image distortion due to the complex model geometry. The results showed the axial slit did not affect the transition from laminar Couette flow to Taylor vortex. The effect of slit wall appeared when the Reynolds number is larger than Re=143 and the slit model shows the transition to turbulent Taylor vortex flow above Re=143.

• Imaging Science in Dentistry
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• 제46권4호
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• pp.245-249
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• 2016

Purpose: This study was designed to evaluate differences in the required visibility of anatomic structures according to the diagnostic tasks of implant planning and periapical diagnosis. Materials and Methods: Images of a real skull phantom were acquired under 24 combinations of different exposure conditions in a cone-beam computed tomography scanner (60, 70, 80, 90, 100, and 110 kV and 4, 6, 8, and 10 mA). Five radiologists evaluated the visibility of anatomic structures and the image quality for diagnostic tasks using a 6-point scale. results: The visibility of the periodontal ligament space showed the closest association with the ability to use an image for periapical diagnosis in both jaws. The visibility of the sinus floor and canal wall showed the closest association with the ability to use an image for implant planning. Variations in tube voltage were associated with significant differences in image quality for all diagnostic tasks. However, tube current did not show significant associations with the ability to use an image for implant planning. conclusion: The required visibility of anatomic structures varied depending on the diagnostic task. Tube voltage was a more important exposure parameter for image quality than tube current. Different settings should be used for optimization and image quality evaluation depending on the diagnostic task.

• 한국실내디자인학회논문집
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• 제27권1호
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• pp.48-57
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• 2018

Recently, cosmetic shops are facing a complicate economy situation and a great number of brands are attempting two-way communication with customers, not one-way communication. 'Brand' equity is important to deliver virtual brand mark as visual image. We have 4 steps for brand identity structure, and this study is about the first 'brand-awareness' and the second step 'brand-image'. We investigated the correlation between brand-awareness and brand-image after searching which spatial elements are highly effective to both steps as we designated 5 cosmetic shops. We already organized the means of spatial analysis and we separated into two elements, constructive and decorative. For constructive element, a shop needs a distinct ceiling and wall design, and for decorative element, strong brand image communication is required through showcase design. We proved that brand awareness and brand image have the correlation, which also can be in direct proportion, by regression analysis. The result of this study shows that improving brand awareness as the primary element for cosmetic road shop can be an effective way to enhance brand image.

• 대한의용생체공학회:의공학회지
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• 제19권6호
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• pp.571-575
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• 1998

초음파 영상 진단 장비의 중요한 특징 중의 하나는 실시간으로 생체내의 연부 조직에 대한 정보를 보여준다는 것이다. 심초음파도는 심장판막 및 심벽의 상태를 실시간 단면 영상으로 보여줄 수 있으므로 심장 질환 진단에 널리 이용되고 잇다. 그러나, 초음파 영상은 스펙클 잡음이나 영상 탈락 등으로 인하여 화질이 많이 열화되어 있다. 그러므로, 이러한 초음파 영상을 개선시킬 수 있는 새로운 기술을 개발하는 것이 매우 중요하다. 본 연구에서는 심초음파도의 개선된 이진 영상을 검출하기 위한 영상 처리 기술을 제안한다. 아날로그 영상인 심초음파도로부터 디지털 동영상 파일을 만들고, 이것을 다시 프레임 단위로 각각 8bit 그레이 레벨을 갖는 정지 영상으로 변환하여 저장하였다. 효율적인 영상 처리를 위해 심중격과 삼첨판을 중심으로 한 심장 부위를 관심 영역으로 두었고, 스펙클 잡음이 포함된 각각의 영상은 영상 개선 필터와 모폴러지 필터를 이용하여 처리되었다. 그 결과, 원 영상이나 문턱치에 의한 이진 영상에 비해 명확한 윤곽선을 가진 개선된 이진 영상을 얻을 수 있었다. 결론적으로, 본 논문에서 제안한 장법은 보다 최적의 초음파 이진 영상 처리 기술 개발과 심초음파 영상의 좌심실벽 운동과 같은 정량적 분석에 중요한 심벽 윤곽선 검출 등에 기여할 수 있을 것이라 생각된다.

• 대한두개안면성형외과학회지
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• 제18권2호
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• pp.76-81
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• 2017

Background: A transcaruncular approach is typically used for reconstructions of medial wall fractures. However, others reported that a transconjunctival approach was conducive for securing an adequate surgical field of view. In this study, we aimed to examine the extent of repair of medial wall fracture via a transconjunctival approach. Methods: We retrospectively reviewed the medical records of 50 patients diagnosed as having medial wall fracture via preoperative computed tomography and who underwent surgery between March 2011 and February 2014. The fracture location was defined by dividing each of the anterior-posterior and superior-inferior distances into three compartments. Results: A transcaruncular approach was used in 7 patients, while the transconjunctival approach was performed in the remaining 43 patients. The transconjunctival approach enabled a relatively broad range of repair that partially included the front and back of the medial wall, and was successful in 86% of the entire study population. Conclusion: It is known that more than 50% of total cases of the medial wall fracture occur mainly in the middle-middle portion, a majority of which can be reconstructed via a transconjunctival approach. We used a transconjunctival approach in identifying the location of the fracture on image scans except for cases including the fracture of the superior portion in patients with medial wall fracture. If it is possible to identify the location of the fracture, a transconjunctival approach would be an useful method for the reconstruction in that it causes no damages to the lacrimal system and is useful in confirming the overall status of the floor.

• 한국멀티미디어학회논문지
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• 제23권8호
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• pp.903-914
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• 2020

In this paper, we present a novel algorithm to generate a 3D model of patient-specific orbital implant, which is finally produced by the 3D printer. Given CT (computed tomography) scan data of the defective orbital wall or floor, we compose the depth image of the defect site by using the depth buffering, which is a computer graphics technology. From the depth image, we compute the 3D surface which fills the broken part by interpolating the points around the broken part. By thickening the 3D surface, we get the 3D volume mesh of the orbital implant. Our algorithm generates the patient-specific orbital implant whose shape is accurately coincident to the broken part of the orbit. It provides the significant time efficiency for manufacturing the implant with supporting high user convenience.