• 한국멀티미디어학회논문지
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• 제13권11호
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• pp.1630-1642
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• 2010

최근 시각 기반 인터페이스의 실현을 위해 손 동작 인식 기술 개발의 필요성이 증가하고 있다. 이러한 시각 기반 인터페이스의 입력으로 사용되는 손 동작은 손 모양의 연속적인 변화로 정의되므로, 효율적인 손 모양 인식 알고리즘의 개발은 필수적이다. 본 논문에서는 손 모양 인식 과정 중 빈번히 발생할 수 있는 손의 회전에 의한 인식 성능 저하를 다룬다. 제안하는 방법은 회전에 강인한 손 모양 인식 알고리즘 개발을 위해 손 동작 인식 환경을 고려하여 비디오 내 인접 프레임간의 높은 상관관계를 이용한다. 특히, 정지 영상에 기반한 기존 연구와의 차별 점은 객체 추적에서 사용되는 템플릿 갱신을 손 모양 인식에 도입하였다는 것이다. 제안한 방법의 유효함을 보이기 위해, 손이 좌우로 회전하는 비디오를 입력으로 템플릿 정합 기반의 방법, PCA와 LBP을 제안하는 방법과 비교 실험하였다. 제안한 방법은 일반적인 템플릿 정합 기반의 손 모양 인식보다 22.7%, KL-Transform을 도입한 템플릿 정합보다 14.5%, PCA 보다 10.7%, LBP 보다 4.3%의 성능 개선을 보였다.

• Journal of Korean Neurosurgical Society
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• 제63권4호
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• pp.504-512
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• 2020

Objective : An important factor during pituitary adenoma surgery is to preserve pituitary stalk (PS) as this plays a role in reduction of the risk of postoperative diabetes insipidus. The hypothalamic-hypophyseal tract (HHT) projects through the PS to the posterior pituitary gland. To reconstruct white matter fiber pathways, methods like diffusion tensor imaging (DTI) tractography have been widely used. In this report we attempted to predict the position of PS using DTI tractography and to assess its intraoperative correlation during surgery of pituitary adenomas. Methods : DTI tractography was used to tract the HHT in nine patients before craniotomy for pituitary adenomas. The DTI location of the HHT was compared with the PS position identified at the time of surgery. DTI fiber tracking was carried out in nine patients prior to the planned craniotomy for pituitary adenomas. In one patient, the PS could not be identified during the surgery. In the other eight patients, a comparison was made between the location of the HHT identified by DTI and the position of the PS visualized at the time of surgery. Results : The position of the HHT identified by DTI showed consistency with the intraoperative position of the PS in seven patients (88.9% concordance). Conclusion : This study shows that DTI can identify the position of the HHT and thus the position of the PS with a high degree of reliability.

• 비파괴검사학회지
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• 제26권2호
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• pp.108-114
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• 2006

3차원 디지털 스펙클 토모그래피를 개발하여 레이저 영상 신호로부터 비정상, 비대칭 부탄 유동의 밀도분포를 분석하였다. 이러한 유동 해석을 위해 3가지 각도에서 CCD 영상으로부터 스펙클의 이동 신호를 획득하여 유동이 없을 때와 있을 때의 스펙클 변화를 상호 상관법에 의해 계산하였다. 이 때 스펙클의 이동 신호는 유동의 밀도 구배에 따라 굴절각으로 변환될 수 있다. 그 굴절각을 적분하여 광선의 주름 변이를 얻고 이로부터 실시간 곱셈산술재건법(MART)을 이용하여 부탄의 3차원 밀도장 재건을 수행하였다.

• 대한통합의학회지
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• 제4권4호
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• pp.67-75
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• 2016

Purpose: The purpose of this study was to compare Hip-Knee-Ankle(HKA) angle and muscle activation ratio between vastus medialis(VM), rectus femoris(RF), and vastus lateralis (VL), and by this, to examine their relationship. It is aimed to explore how the activation ratio among the muscles involved in patellofemoral kinetics would vary in relation with the frontal alignment of the lower extremity. Subjects and Methods: 26 healthy subjects were recruited for the study. The HKA angles were measured with radiograph. The VM, RF, VL muscle activation level were measured by surface electromyography while each participant performed 4 different types of movement (isometric knee extension, squat, ambulation, step-up) and VM/RF, VM/VL, RF/VL ratios were calculated. Pearson correlation was used to estimate the relationship between the HKA angle and the muscle ratio. Results: There was significant moderate correlation between HKA angle and VM: RF on the left side during ambulation (p<0.05). Moderate correlations were also observed during step-up and squat with less significance (p<0.1). Conclusion: The frontal alignment of the knee measured by the HKA angle was conditionally associated with muscle activation ratio between VM and RF (VM:RF); On the left, during ambulation, step-up, and squat, the more valgus knee tended to correlate with the more VM muscle activation ratio, which is expected to induce more stabilizing effect to the patella and its tracking. It suggests that the frontal alignement measured by the HKA-angle can affect PF kinetics. It also indicates a possibility that increase in valgus alignment of the knee, by the HKA measurement, may not act unfavorably to generate PFP.

• 지구물리와물리탐사
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• 제7권1호
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• pp.93-98
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• 2004

The sand-covered Muweilah archaeological site in the United Arab Emirates (UAE) is a unique Iron Age site, and has been subject to intensive investigations. However, excavations are time consuming and may require twenty years to complete. Thus geophysical surveys were undertaken with the objective of characterising the site more expeditiously. This paper presents preliminary results of these surveys. Ground penetrating radar (GPR) was tested as a primary imaging tool, with an ancillary shallow time domain EM (MetalMapper) system. Dense 3D GPR datasets were migrated to produce horizontal (plan view) depth slices at 10 cm intervals, which is conceptually similar to the archaeologists' excavation methodology. The objective was to map all features associated with anthropogenic activity. This required delineating extensive linear and planar features, which could represent infrastructure. The correlation between these and isolated point reflectors, which could indicate anthropogenic activity, was then assessed. Finally, MetalMapper images were used to discriminate between metallic and non-metallic scatterers. The moderately resistive sand cover allowed GPR depth penetration of up to 5 m with a 500 MHz system. GPR successfully mapped floor levels, walls, and isolated anthropogenic activity, but crumbling walls were difficult to track in some cases. From this study, two possible courtyard areas were recognised. The MetalMapper was less successful because of its limited depth penetration of 50 cm. Despite this, the system was still useful in detecting modem-day ferruginous waste and bronze artefacts. The results (subject to ongoing ground-truthing) indicated that GPR was optimal for sites like Muweilah, which are buried under a few metres of sand. The 3D survey methodology proved essential to achieve line-to-line correlation for tracking walls. In performing the surveys, a significant improvement in data quality ensued when survey areas were flattened and de-vegetated. Although MetalMapper surveys were not as useful, they certainly indicated the value of including other geophysical data to constrain interpretation of complex GPR features.

• 제어로봇시스템학회논문지
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• 제12권5호
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• pp.431-437
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• 2006

In this paper vector code correlation(VCC) method and an algorithm to promote the image-processing performance in building an effective measurement system using cameras are described far automatically berthing and controlling the ship equipped with side-thrusters. In order to realize automatic ship berthing, it is indispensable that the berthing assistant system on the ship should continuously trace a target in the berth to measure the distance to the target and the ship attitude, such that we can make the ship move to the specified location. The considered system is made up of 4 apparatuses compounded from a CCD camera, a camera direction controller, a popular PC with a built-in image processing board and a signal conversion unit connected to parallel port of the PC. The object of this paper is to reduce the image-processing time so that the berthing system is able to ensure the safety schedule against risks during approaching to the berth. It could be achieved by composing the vector code image to utilize the gradient of an approximated plane found with the brightness of pixels forming a certain region in an image and verifying the effectiveness on a commonly used PC. From experimental results, it is clear that the proposed method can be applied to the measurement system for automatic ship berthing and has the image-processing time of fourfold as compared with the typical template matching method.

• Journal of Cardiovascular Imaging
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• 제30권1호
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• pp.50-58
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• 2022

BACKGROUND: Little is known regarding right ventricular (RV) remodeling immediately after Tetralogy of Fallot (TOF) repair. We sought to describe myocardial deformation by cardiac magnetic resonance imaging (CMR) after TOF repair and investigate associations between these parameters and early post-operative outcomes. METHODS: Fifteen infants underwent CMR without sedation as part of a prospective pilot study after undergoing complete TOF repair, prior to hospital discharge. RV deformation (strain) was measured using tissue tracking, in addition to RV ejection fraction (EF), volumes, and pulmonary regurgitant fraction. Pearson correlation coefficients were used to determine associations between both strain and CMR measures/clinical outcomes. RESULTS: Most patients were male (11/15, 73%), with median age at TOF repair 53 days (interquartile range, 13,131). Most patients had pulmonary stenosis (vs. atresia) (11/15, 73%) and 7 (47%) received a transannular patch as part of their repair. RV function was overall preserved with mean RV EF of 62% (standard deviation [SD], 9.8). Peak radial and longitudinal strain were overall diminished (mean ± SD, 33.80 ± 18.30% and -15.50 ± 6.40%, respectively). Longer hospital length of stay after TOF repair was associated with worse RV peak radial ventricular strain (correlation coefficient (r), -0.54; p = 0.04). Greater pulmonary regurgitant fraction was associated with shorter time to peak radial RV strain (r = -0.55, p = 0.03). CONCLUSIONS: In this small study, our findings suggest presence of early decrease in RV strain after TOF repair and its association with hospital stay when changes in EF and RV size are not yet apparent.

• 한국도로학회논문집
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• 제7권1호
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• pp.11-20
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• 2005

본 연구는 재활용 아스팔트 혼합물의 역학적 특성과 재생혼합물 내 바인더의 대형분자(Large molecular size : LMS)와의 상관성을 조사하였다. 재생 혼합물은 여러 가지 혼합 방법으로 제작하여 역학적 강도 시험을 수행하였고 재생혼합물 내의 RAP 굵은골재(R), 매트릭스(M) 및 신규 굵은골재(V) 시료에 코팅된 바인더의 노화 상태를 gel-permeation chromatography(GPC)를 통해 조사하였다. 재생혼합물 내 바인더의 노화상태 분석을 위한 혼합물 제조에는 원형골재 (13mm 강자갈)가 굵은골재로 사용되었다. GPC를 통한 재생혼합물 내 바인더의 노화상태를 분석한 결과 신 구 바인더의 노화 정도에 차이를 확인했으며, 혼합 방법에 따라 재생혼합물의 바인더 노화 상태가 서로 상이함을 확인하였다. 역학적 강도 특성과 R, M, V시료의 LMS에 대한 상관성분석결과 재생혼합물의 역학적 특성이 혼합물 내의 재료 중 어느 특정 재료의 바인더 LMS와 더 밀접한 상관관계를 보였다. 또한 LMS가 어느 정도 증가될 때까지는 강도특성이 향상되나 LMS가 보다 더 커지면 강도성능이 저하되는 경향을 보여 혼합물 제조시 제대로 회복되지 못한 노화된 아스팔트가 향후 노화가 더욱 진행되면 재생혼합물의 강도 성능이 저하될 것으로 판단되었다.

• 한국위성정보통신학회논문지
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• 제6권1호
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• pp.80-85
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• 2011

본 논문에서는 소프트웨어 기반의 실시간 GPS L1 수신기에 대한 블록 상관기법을 제안한다. 최근 다양한 위성항법 환경에서 보다 효율적인 항법 수신기 개발을 위하여 소프트웨어 기반의 실시간 수신기 개발이 필요하다. 실시간 소프트웨어 수신기는 입력신호 처리부, 신호획득부, 신호추적부, 항법데이터 처리부, 항법해 계산부로 구성되고 각 처리부는 해당 기능을 수행하기 위한 단위 컴포넌트로 구성된다. 이러한 소프트웨어 환경에서의 수신기 개발을 용이하게 수행하기 위한 소프트웨어 기반의 수신기를 개발함으로써 다양한 모델을 적용하거나 새로운 컴포넌트 조합으로 다양한 시뮬레이션을 수행할 수 있다는 장점을 제공하고 있다. 본 논문에서는 이러한 소프트웨어 기반의 수신기가 실시간의 성능을 나타낼 수 있는 블록 상관기법을 제안하고 이에 대한 성능을 검증하였다.

• 한국통신학회논문지
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• 제30권9C호
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• pp.887-898
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• 2005

본 논문에서는 피로를 인식하기 위하여 베이지안 네트워크를 기반으로 한 확률 모델을 제안하고자 한다. 먼저 적외선 조명을 조사하여 눈거풀의 움직임, 시선 방향, 얼굴의 움직임 및 얼굴 표정 같은 얼굴특징정보를 측정하였다. 그러나 각각의 얼굴특징정보만으로 생체 피로를 결정하기에는 충분하지 않다. 그러므로, 본 논문에서는 생체 피로를 확률적 추론하기 위하여 가능한 많은 피로 원인에 대한 정보와 얼굴특징정보들로 베이지안 네트워크 모델을 구성하여 BN 피로지수를 산출하였다. 또한, BN 피로지수의 문턱치값은 MSBNX 시물레이션 결과 0.95로 산출되었다. 실험 결과 BN 피로지수와 TOVA 응답 시간을 비교한 결과 밀접한 상관관계가 있음을 확인하여 제안한 피로인식모델의 유효성을 입증하였다.