• Journal of Magnetics
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• 제19권2호
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• pp.185-191
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• 2014

In this study we evaluated that flow rate changes affect the (time of flight) TOF image and contrast-enhanced (CE) in a three-dimensional TOF angiography. We used a 3.0T MR System, a nonpulsatile flow rate model. Saline was used as a fluid injected at a flow rate of 11.4 cm/sec by auto injector. The fluid signal strength, phantom body signal strength and background signal strength were measured at 1, 5, 10, 15, 20 and 25-th cross-section in the experienced images and then they were used to determine signal-to-noise ratio and contrast-to-noise ratio. The inlet, middle and outlet length were measured using coronal images obtained through the maximum intensity projection method. As a result, the length of inner cavity was 2.66 mm with no difference among the inlet, middle and outlet length. We also could know that the magnification rate is 49-55.6% in inlet part, 49-59% in middle part and 49-59% in outlet part, and so the image is generally larger than in the actual measurement. Signal-to-noise ratio and contrast-to-noise ratio were negatively correlated with the fluid velocity and so we could see that signal-to-noise ratio and contrast-to-noise ratio are reduced by faster fluid velocity. Signal-to-noise ratio was 42.2-52.5 in 5-25th section and contrast-to-noise ratio was from 34.0-46.1 also not different, but there was a difference in the 1st section. The smallest 3D TOF MRA measure was $2.51{\pm}0.12mm$ with a flow velocity of 40 cm/s. Consequently, 3D TOF MRA tests show that the faster fluid velocity decreases the signal-to-noise ratio and contrast-to-noise ratio, and basically it can be determined that 3D TOF MRA and 3D CE MRA are displayed larger than in the actual measurement.

• Journal of Trauma and Injury
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• 제28권3호
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• pp.158-169
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• 2015

Purpose: Frostbite can affect still soldiers. Initial clinical manifestations are similar for superficial and deep frostbite, so early treatment is identical. It is under-estimated by physicians. We try to identify the challenges of managing these complex tissue injuries. Methods: A retrospective analysis of 84 patients hospitalized at AFCH from 2009 to 2015 was conducted. We investigated differences of epidemiological characteristics, identification of soft tissue injury, treatment and complications between superficial (SF: 43; 51.2%) and deep (DF: 41; 48.8%) frostbite. Results: The major (94.0%) developed frostbite in dry circumstances (89.3%). Wet circumstances (66.7%) were more susceptible to DF rather than dry (46.7%). The 38 (45.2%) arrived to specialist within 7days. Most prone sites were feet, followed by hands. Toes had more deep injuries. DF presented more increased levels of ALT, CPK, CKMB, CRP. The bone scan of W+S+ was 48.3%, 87.1% and W+S- was 20.7%, 12.9%, respectively. The treatment resulted in improved or normalized perfusion scan with matching clinical improvement. It was a good tool to assess treatment response. Eighteen normal and 8 stenotic type of PCR resulted in normal with matching clinical improvement. One continuous obstructive waveform led to minor amputation. Twelve underwent both PCR and MRA. Among 6 normal PCR, 5 showed normal and one stenosis in MRA. All 5 stenosis and one obstruction showed the same findings in MRA. It was a good tool to evaluate vascular compromise. They were treated with rapid rewarming (11.6%, 22.0%), hydrotherapy (16.3%, 29.3%), respectively. Six (14.6%) underwent STSG, 2 (4.9%) had digital amputation in DF. Berasil, Ibuprofen, Trental were commonly administered. PGE1 was administered selectively for 6.8, 10.8 days, respectively. Raynaud's syndrome (16.3%), CRPS (4.7%), LOM (14.6%) and toe deformity (4.9%) were specific sequelae. Conclusion: We should recommend intensive foot care education, early rewarming and evacuation to specialized units. The bone scanning and PCR should allow for a more aggressive and active approach to the management of tissue viability.

• Investigative Magnetic Resonance Imaging
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• 제22권2호
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• pp.94-101
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• 2018

Purpose: To determine the value of the appearance of the high signal intensity halo sign for detecting carotid intraplaque hemorrhage (IPH) on maximum intensity projection (MIP) of time-of-flight (TOF) MR angiography (MRA), based on high signal intensity on magnetization-prepared rapid acquisition with gradient-echo (MPRAGE) sequencing. Materials and Methods: A total of 78 carotid arteries in 65 patients with magnetization-prepared rapid acquisition gradient-echo (MPRAGE) positive on carotid plaque MR imaging were included in this study. High-resolution MR imaging was performed on a 3.0-T scanner prior to carotid endarterectomy or carotid artery stenting. Fast spin-echo T1- and T2-weighted axial imaging, TOF, and MPRAGE sequences were obtained. Carotid plaques with high signal intensity on MPRAGE > 200% that of adjacent muscle on at least two consecutive slices were defined as showing IPH. Halo sign of high signal intensity around the carotid artery was found on MIP from TOF MRA. Continuous and categorical variables were compared among groups using the Mann-Whitney test and Fisher's exact tests. Results: Of these 78 carotid arteries, 53 appeared as a halo sign on the TOF MRA. The total IPH volume of patients with a positive halo sign was significantly higher than that of patients without a halo sign ($75.0{\pm}86.8$ vs. $16.3{\pm}18.2$, P = 0.001). The maximum IPH axial wall area in patients with a positive halo sign was significantly higher than that of patients without a halo sign ($11.3{\pm}9.9$ vs. $3.7{\pm}3.6$, P = 0.000). Conclusion: High signal intensity halo of IPH on MIP of TOF MRA is associated with total volume and maximal axial wall area of IPH.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2001년도 제6차 학술대회 초록집
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• pp.134-134
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• 2001

Purpose： To evaluate the physiologic background of poorly visualized aneurysms during DSA a contrast-enhanced MRA(CEMRA) due to hemodynamical isolation on clinical and experiment data. Method： Two cases of intracranial aneurysm which were poorly visualized on DSA a CEMRA and one case of intracranial aneurysm which had poor turnover of contrast mediu during DSA were selected for this clinical study. We evaluated the turnover of blood in t terminal aneurysm of handmade elastic silicon phantoms for comparative experiment. Flo experiments with DSA and contrast enhanced MRA were performed in elastic phantoms aneurysm with 3 different diameters (2, 5 and 10 mm) of neck mimicking basilar ti aneurysm, attached to pulsatile pump similar to that of human physiologic parameters. W compared the results with those of computational flow dynamics(CFD).

• 대한디지털의료영상학회논문지
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• 제17권1호
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• pp.43-48
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• 2015

Intracrnial 3D TOF MR angiography was performed in 30 normal volunteers with both 1.5 and 3.0 T MRI system with high resolutions. Used Voxel sizes were $0.39{\times}0.39{\times}0.2$(1.5 T) and $0.19{\times}0.19{\times}0.35$(3.0 T), respectively. High image quality and depiction of small vessel branches were equality demonstrated with 1.5 T and 3.0 T HR TOF MRA(p<0.05). Intracranial high resolution TOF MRA with 1.5 T and 3.0 T provides high diagnostic information with having merits and demerits in depiction of vascular branches.

• 한국전산유체공학회지
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• 제20권2호
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• pp.7-15
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• 2015

This paper attempts to evaluate the accuracy and efficiency of a design optimization procedure by combining wavelets-based multi resolution analysis method and proper orthogonal decomposition (POD) technique. Aerodynamic design procedure calls for high fidelity computational fluid dynamic (CFD) simulations and the consideration of large number of flow conditions and design constraints. Thus, even with significant computing power advancement, current level of integrated design process requires substantial computing time and resources. POD reduces the degree of freedom of full system by conducting singular value decomposition for various field simulations. In this research, POD combined Design Optimization model is proposed and its efficiency and accuracy are to be evaluated. For additional efficiency improvement of the procedure, multi resolution analysis method is also being employed during snapshot constructions (POD training period). The proposed design procedure was applied to the optimization of wing aerodynamic performance. Throughout the research, it was confirmed that the POD/MRA design procedure could significantly reduce the total design turnaround time and also capture all detailed complex flow features as in full order analysis.

• 수산해양기술연구
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• 제51권1호
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• pp.16-25
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• 2015

Visual census and hydro-acoustic survey was carried out at Ulju small scale marine ranching area (MRA) to estimate demersal fish aggregations on September and November 2013. In this hydro-acoustic survey, the authors combined an image sonar with a scientific echo sounder to monitor an underwater situation and compare two acoustic data. Consequently, visual census survey was useful to estimate fish species composition for hydro-acoustic survey, because it is easy to identify aggregated fish species and overcome limits on a fishing depth and ability of an conventional fishing gear like a bottom gill-net or a fish trap at marine ranching area. Mean fish density was estimated as $0.757g/m^2$ on September and $0.219g/m^2$ on November and Fish abundance was finally calculated as 1.51ton (coefficient of variation, CV=13.1%) on September and 0.44ton (CV=47.7%) on November, respectively. Hydro-acoustic survey combined with the image sonar was useful to monitor fish aggregations and estimate fish stocks around artificial reefs at shallow coastal MRA. We were able to easily identify the underwater structures like an artificial reef and a fishing rope as well as fish aggregations from image sonar data. Therefore, the method was effective to separate unwanted echo signals in acoustic data of scientific echo sounder.

• 지능정보연구
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• 제18권3호
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• pp.185-202
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• 2012

오늘날 정보사회에서는 정보에 대한 가치를 인식하고, 이를 위한 정보의 활용과 수집이 중요해지고 있다. 얼굴 표정은 그림 하나가 수천개의 단어를 표현할 수 있듯이 수천 개의 정보를 지니고 있다. 이에 주목하여 최근 얼굴 표정을 통해 사람의 감정을 판단하여 지능형 서비스를 제공하기 위한 시도가 MIT Media Lab을 필두로 활발하게 이루어지고 있다. 전통적으로 기존 연구에서는 인공신경망, 중회귀분석 등의 기법을 통해 사람의 감정을 판단하는 연구가 이루어져 왔다. 하지만 중회귀모형은 예측 정확도가 떨어지고, 인공신경망은 성능은 뛰어나지만 기법 자체가 지닌 과적합화 문제로 인해 한계를 지닌다. 본 연구는 사람들의 자극에 대한 반응으로서 나타나는 얼굴 표정을 통해 감정을 추론해내는 지능형 모형을 개발하는 것을 목표로 한다. 기존 얼굴 표정을 통한 지능형 감정판단모형을 개선하기 위하여, Support Vector Regression(이하 SVR) 기법을 적용하는 새로운 모형을 제시한다. SVR은 기존 Support Vector Machine이 가진 뛰어난 예측 능력을 바탕으로, 회귀문제 영역을 해결하기 위해 확장된 것이다. 본 연구의 제안 모형의 목적은 사람의 얼굴 표정으로부터 쾌/불쾌 수준 그리고 몰입도를 판단할 수 있도록 설계되는 것이다. 모형 구축을 위해 사람들에게 적절한 자극영상을 제공했을 때 나타나는 얼굴 반응들을 수집했고, 이를 기반으로 얼굴 특징점을 도출 및 보정하였다. 이후 전처리 과정을 통해 통계적 유의변수를 추출 후 학습용과 검증용 데이터로 구분하여 SVR 모형을 통해 학습시키고, 평가되도록 하였다. 다수의 일반인들을 대상으로 수집된 실제 데이터셋을 기반으로 제안모형을 적용해 본 결과, 매우 우수한 예측 정확도를 보임을 확인할 수 있었다. 아울러, 중회귀분석이나 인공신경망 기법과 비교했을 때에도 본 연구에서 제안한 SVR 모형이 쾌/불쾌 수준 및 몰입도 모두에서 더 우수한 예측성과를 보임을 확인할 수 있었다. 이는 얼굴 표정에 기반한 감정판단모형으로서 SVR이 상당히 효과적인 수단이 될 수 있다는 점을 알 수 있었다.

• 대한방사선기술학회지:방사선기술과학
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• 제33권3호
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• pp.223-230
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• 2010

본 연구에서는 MRI와 MRA를 이용하여 우리나라 사람의 뇌혈관 질환 중 뇌혈관의 파열에 의한 뇌혈관 질환을 제외하고 뇌혈관이 좁아지거나 막힌 허혈성 뇌혈관 질환의 분포(호발부위)를 분석하여 임상에서 활용할 수 있도록 하였다. 뇌혈관이 좁아지거나 막힌 허혈성 뇌혈관 질환만의 분포를 분석한 이유는 뇌혈관의 파열에 의한 출혈성 뇌혈관 질환과 뇌경색(brain infarction) 등 허혈성 뇌혈관 질환의 발생학적 기전(mechanism)이 다르기 때문이며 그 결과는 아래와 같다. 1. 연구대상자 총 626명 중 성별로는 남자가 55.0%로 여자 45.0%보다 높은 분포를 보였다. 2. 위치별 허혈성 뇌혈관 질환의 분포에서 우측 뇌혈관이 37.5%로 가장 많았으며, 좌측 뇌혈관 35.1%, 양쪽 뇌혈관 27.3% 순으로 나타났다. 3. 허혈성 뇌혈관 질환의 뇌혈관 별 분포는 ICA가 38.9%로 가장 많았으며, 다음으로 MCA 35.7%, PCA 13.4%, ACA 6.0%, VA 3.3% 순으로 나타났다. 4. A-com에 질환이 있는 경우는 한 명도 없었으며 P-com 에도 남자 1명만이 발생했다. 5. MCA에는 여자가 54.6%로 남자 42.2%보다 많아, 성별에 따라 통계적으로 유의미한 차이를 보였다($x^2$=9.64, p < .01). 6. ICA에서는 남자가 56.4%로 여자 46.8%보다 많아 통계적으로 유의미한 차이를 보였다($x^2$=5.71, p < .05). 7. BA에서도 남자가 2.3%로 여자 0.4%보다 많아 성별에 따라 유의미한 차이를 보였다($x^2$=4.25, p < .05). 8. 연령에 따른 혈관별 질환의 분포에 대한 차이는 없었으며 협착과 폐색의 분포에서는 폐색보다 협착이 많았다.

• 대한디지털의료영상학회논문지
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• 제14권1호
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• pp.7-12
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• 2012

The purpose of this study was to examine usefulness of 3T equipment-based time-of-flight magnetic resonance angiography (3T-TOF MRA) by comparing standard technique (ST) with high resolution technique (HRT) in evaluation of cerebral blood vessel. The 3T-TOF MRA was performed for 31 patients who were suspected of having cerebrovascular disease from March to July 2010. For evaluation of cerebral blood vessel, classification was conducted randomly: group I that included vertebral artery and basilar artery, group II that ranged from 2.5cm before basin part of common carotid artery to basin part of internal and external carotid arteries and to genu part of internal carotid artery, group III that ranged from vertebral part of internal carotid artery to the first basin art of anterior and middle cerebral through education recognizes the importance of dose reduction and examine if their efforts and further reduce patient dose could achieve optimization of the medical exposure is considered.