• 대한의용생체공학회:의공학회지
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• 제28권6호
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• pp.732-743
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• 2007

Background noise is one of the major complaints of not only hearing impaired persons but also normal listeners. This paper describes the results of two experiments in which speech recognition performance was determined for listeners with normal hearing and sensorineural hearing loss in noise environment. First, we compared speech enhancement algorithms by evaluation speech recognition ability in various speech-to-noise ratios and types of noise. Next, speech enhancement algorithms by reducing background noise were presented and evaluated to improve speech intelligibility for sensorineural hearing impairment listeners. We tested three noise reduction methods using single-microphone, such as spectrum subtraction and companding, Wiener filter method, and maximum likelihood envelop estimation. Their responses in background noise were investigated and compared with those by the speech enhancement algorithm that presented in this paper. The methods improved speech recognition test score for the sensorineural hearing impaired listeners, but not for normal listeners. The results suggest the speech enhancement algorithm with the loudness compression can improve speech intelligibility for listeners with sensorineural hearing loss.

• 디지털융복합연구
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• 제10권1호
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• pp.365-369
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• 2012

본 논문에서는 열차 선로 모니터링을 위한 열차의 위치 및 이동을 추정하는 비전 기반 기법을 제안한다. 퍼지 분류기를 이용하여 열차의 상태를 판별하며, 프레임 차와 배경 감산을 각각 열차의 움직임과 존재를 판결하기 위해서 사용하고, 퍼지 분류기의 언어 변수로 사용된다. 실험 결과에서 제안하는 기법은 열차의 위치와 움직임을 정확히 추정하는 것을 볼 수 있다. 그러므로 제안하는 기법은 군중 밀도를 추정하거나 안전 감시를 수행하는 열차 모니터링 시스템에 활용될 수 있을 것이다.

• 대한방사선기술학회지:방사선기술과학
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• 제24권2호
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• pp.23-28
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• 2001

The purpose of this study is to compare the 3-dimensional MR angiography(MRA) with digital subtraction angiography(DSA) for the evaluation of pedal artery. MR angiography was performed using three-dimensional FISP acquisition before, and four sequential acquisitions after the injection of gadolinium(0.2 mmol/kg, 3 ml/sec). MRA was compared with DSA for a correct identification of the arterial segment. Out of 168 segments, 32 segmints were invisible in both MRA and DSA. At the level of ankle, 48 segments were visible in both examinations, and 18 segments were visible only in MRA. In the foot area, 34 segments were visible in MRA, but not in DSA. Three arterial segments were visible only in DSA. 3D MRA is comparable to DSA for the evaluation of pedal artery, thus it gives additional Information for the planning of treatment in lower extremity artery.

• Journal of Yeungnam Medical Science
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• 제36권2호
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• pp.109-114
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• 2019

Background: Transforaminal epidural block (TFEB) is an effective treatment option for radicular pain. To reduce complications from intravascular injection during TFEB, use of imaging modalities such as real-time fluoroscopy (RTF) or digital subtraction angiography (DSA) has been recommended. In this study, we investigated whether DSA improved the detection of intravascular injection during TFEB at the whole spine level compared to RTF. Methods: We prospectively examined 316 patients who underwent TFEB. After confirmation of final needle position using biplanar fluoroscopy, 2 mL of nonionic contrast medium was injected at a rate of 0.5 mL/s under RTF; 30 s later, 2 mL of nonionic contrast medium was injected at a rate of 0.5 mL/s under DSA. Results: Thirty-six intravascular injections were detected for an overall rate of 11.4% using RTF, with 45 detected for a rate of 14.2% using DSA. The detection rate using DSA was statistically different from that using RTF (p=0.004). DSA detected a significantly higher proportion of intravascular injections at the cervical level than at the thoracic (p=0.009) and lumbar (p=0.011) levels. Conclusion: During TFEB at the whole spine level, DSA was better than RTF for the detection of intravascular injection. Special attention is advised for cervical TFEB, because of a significantly higher intravascular injection rate at this level than at other levels.

• 대한영상의학회지
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• 제85권1호
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• pp.24-35
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• 2024

자발두개내압저하(spontaneous intracranial hypotension)은 기립성 두통을 특징으로 하는 질환이며, 영상기법의 발달과 질환에 대한 인식이 높아짐에 따라 발견 빈도가 점차 증가하고 있는 추세이다. 이전에는 이 질환에서의 특징적인 뇌 자기공명영상 소견들이 많이 알려져 있었다. 그러나 최근에는 척추에서의 뇌척수액 누출이 원인으로 알려짐에 따라 척추 자기공명영상 소견이 주목받고 있다. 또한 뇌척수액 누출 부위를 정확히 확인할 수 있는 초고속 CT 척수조영술(ultrafast CT myelography), 디지털 감산 척수조영술(digital subtraction myelography) 등이 개발되었다. 이 종설에서는 자발두개내압저하의 진단, 척추 자기공명영상 소견, 최신 영상검사법과 치료에 대해 다루고자 한다.

• Journal of Veterinary Science
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• 제24권5호
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• pp.65.1-65.9
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• 2023

Background: Bone subtraction computed tomography angiography (BSCTA) is a useful alternative technique for improving visualization of vessels surrounded by skull bone. However, no studies have compared computed tomography angiography (CTA) and BSCTA for improving the visibility of canine cerebral blood vessels. Objectives: To evaluate the potential benefit of BSCTA for better delineation of brain arteries of the circle of Willis (CoW) in dogs by comparing BSCTA with non-subtraction computed tomography angiography (NSCTA). Methods: Brain CTA was performed for nine healthy beagle dogs using a bolus tracking method with saline flushing. A total dose of 600 mgI/kg of contrast agent with an iodine content of 370 mgI/mL was injected at a rate of 4 ml/s. Bone removal was achieved automatically by subtracting non-enhanced computed tomography (CT) data from contrast CT data. Five main intracranial arteries of the CoW were analyzed and graded on a scale of five for qualitative evaluation. Results: Scores of basilar artery, middle cerebral artery, and rostral cerebral artery in the BSCTA group were significantly higher than those in the NSCTA group (p = 0.001, p = 0.020, and p < 0.0001, respectively). Scores of rostral cerebellar artery (RcA) and caudal cerebral artery (CCA) did not differ significantly between the two groups. However, scores of RcA and CCA in the BSCTA group were higher than those in the NSCTA group. Conclusions: BSCTA improved visualization of intracranial arteries of the CoW with close contact to bone. Thus, it should be recommended as a routine scan method in dogs suspected of having brain vessel disease.

• Journal of information and communication convergence engineering
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• 제13권3호
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• pp.197-204
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• 2015

In this paper, we present an algorithm for the detection of illegally parked vehicles based on a combination of some image processing algorithms. A digital camera is fixed in the illegal parking region to capture the video frames. An adaptive Gaussian mixture model (GMM) is used for background subtraction in a complex environment to identify the regions of moving objects in our test video. Stationary objects are detected by using the pixel-level features in time sequences. A stationary vehicle is detected by using the local features of the object, and thus, information about illegally parked vehicles is successfully obtained. An automatic alarm system can be utilized according to the different regulations of different illegal parking regions. The results of this study obtained using a test video sequence of a real-time traffic scene show that the proposed method is effective.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2002년도 추계학술발표논문집 (상)
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• pp.703-706
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• 2002

군중잡음(crowd noise)이 발생하는 환경에서 음성 통화 및 화자 인식을 할 때에는 음성에 파열음이나 마찰음과 같은 유색잡음(colored noise)이 부가되어 원래 음성이 왜곡된다. 이와 같이 왜곡된 음성 신호를 처리할 때에는 군중잡음을 제거하는 과정이 반드시 필요하다. 본 논문에서는 전형적인 군중잡음의 모델인 쇼핑 센터 잡음을 분석하고, 그 결과를 이용하여 음성 신호처리시에 효과적으로 군중잡음만을 제거할 수 있는 모델을 제안한다. 제안된 모델은 시간 영역에서 마찰음과 파열음을 제거하고. DSI(Digital Speech Interpolation)를 이용하여 침묵 구간을 검출한다. 이때 주파수 영역에서는 이 침묵구간을 잡음으로 간주하여 이를 이용한 스펙트럼 차감법(spectral subtraction)으로 음성 신호에 부가된 군중 잡음을 제거하는 과정을 거친다.

• Archives of Reconstructive Microsurgery
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• 제13권2호
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• pp.130-135
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• 2004

Purpose : To observe the patency of anastomosis site and the findings of circulation of grafted fibula in osteonecrosis of femoral head treated with vascularized fibular graft by use of digital subtraction angiography. Materials and Methods : 17 cases of 11 patients who underwent vascularized fibula graft for osteonecrosis of femoral head. We performed digital subtraction angiography(DSA) for them at second week postoperatively in 12 cases, at sixth week in 1 case, at sixth month in 2 cases, at twelfth month in 1 case, and eighteenth month in 1 case which had been got DSA at second week before. We observe the patency of pedicle, and the circulation of grafted fibula such as periosteal and intraosseous vessels with time. Results : All cases except one which were thought failure of selective angiogram showed good passage of blood flow through anstomosed pedicle on DSA. We found the differences in appearance of circulation of grafted fibula with time. DSA at 2nd and 6th week postoperatively revealed both of periosteal and intraosseous vessels along the fibula and blood pooling at the tip of fibula. DSA at 6th month showed maintenance of periosteal and intraosseous vessels along the fibula but did not clearly reveal blood pooling at the tip of fibula. The findings of DSA at 12th and 18th month were similar each other. The periosteal vessels were not seen as the grafted fibular bone were incorporated into surrounding femoral bone but intraosseous vessels were still seen. Conclusion : It was thought that DSA could be used for evaluation of the status of pedicle including anastomsed site and vessels of grafted fibula with time. The periosteal vessels of fibula were decreased with time but intraosseous vessels were still seen until 18th month after vascularized fibula graft.

• 한국멀티미디어학회논문지
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• 제21권1호
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• pp.51-60
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• 2018

We present a real-time interactive particle-art with human motion based on computer vision techniques. We used computer vision techniques to reduce the number of equipments that required for media art appreciations. We analyze pros and cons of various computer vision methods that can adapted to interactive digital media art. In our system, background subtraction is applied to search an audience. The audience image is changed into particles with grid cells. Optical flow is used to detect the motion of the audience and create particle effects. Also we define a virtual button for interaction. This paper introduces a series of computer vision modules to build the interactive digital media art contents which can be easily configurated with a camera sensor.