• 한국항행학회논문지
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• 제16권5호
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• pp.846-852
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• 2012

영상분할 결과는 알고리즘에 관련된 매개변수들에 따라 다르기 때문에 최적 분할을 위하여 시행 착오법이 많이 이용된다. 본 논문에서는 3차원 변량 분석법을 이용하여 영역기반 active contour 방법에 관련된 최적 매개변수들을 결정하는 방법을 제안한다. 3원 변량 분석법에 의해서 추출된 결과와 사용자가 영상에서 직접 그린 결과가 상호 비교된다. 마지막으로 각 매개변수들의 주요 효과와 상호작용 효과를 측정하고 최적 값을 추출하기 위하여 점 추정 및 구간 추정 값을 계산한다. 본 논문에서 제안한 방법은 구간 상수 모델을 대상으로 영상분할시 최적 매개변수들을 추출하는데 큰 도움을 줄 것이다.

• Clinical and Experimental Pediatrics
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• 제57권6호
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• pp.264-270
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• 2014

Purpose: Acute necrotizing encephalopathy (ANE) is a fulminant disease of the brain characterized by bilateral thalamic lesions, and is prevalent among children in East Asia. The prognosis of ANE is usually poor with a high mortality rate and neurological sequelae. This study aimed to delineate the clinical characteristics and prognostic factors of ANE. Methods: We retrospectively analyzed clinical data of 399 pediatric patients with encephalitis who were admitted to Samsung Medical Center from December 1998 to March 2011. We enrolled ten patients (11 cases) with ANE and analyzed their demographic, clinical, and neuroimaging data. The location and extent of the brain regions were checked based on fluid-attenuated inversion recovery, T1-, and T2-weighted imaging findings; the presence of contrast enhancement, restricted diffusion, and hemorrhage. Results: Ten patients were identified, including one patient with two episodes. The median age of onset was 1.5 years (0.4-8.4 years). The mortality rate was 40%, and only 30% of patients survived without neurological sequelae. The definite involvement of the brainstem on brain magnetic resonance imaging was significantly correlated with mortality (P =0.04). Conclusion: Broad and extensive brainstem involvement suggested the fulminant course of ANE. Early diagnosis of ANE before brainstem involvement, through careful identification of symptoms of brain dysfunction, may be the best way to achieve better neurological outcomes.

• Investigative Magnetic Resonance Imaging
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• 제25권2호
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• pp.93-100
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• 2021

Purpose: (1) To evaluate the trabecular pattern at the femoral attachment of the posterior cruciate ligament (PCL) in patients with a PCL injury; (2) to analyze bone microarchitecture by applying gray level co-occurrence matrix (GLCM)-based texture analysis; and (3) to determine if there is a significant relationship between bone microarchitecture and posterior instability. Materials and Methods: The study included 96 patients with PCL tears. Trabecular patterns were evaluated on T2-weighted MRI qualitatively, and were evaluated by GLCM texture analysis quantitatively. The grades of posterior drawer test (PDT) and the degrees of posterior displacement on stress radiographs were recorded. The 96 patients were classified into two groups: acute and chronic injury. And 27 patients with no PCL injury were enrolled for control. Pearson's correlation coefficient and one-way ANOVA with Bonferroni test were conducted for statistical analyses. This protocol was approved by the Institutional Review Board. Results: A thick and anisotropic trabecular bone pattern was apparent in normal or acute injury (n = 57/61;93.4%), but was not prominent in chronic injury and posterior instability (n = 31/35;88.6%). Grades of PDT and degrees of posterior displacement on stress radiograph were not correlated with texture parameters. However, the texture analysis parameters of chronic injury were significantly different from those of acute injury and control groups (P < 0.05). Conclusion: The trabecular pattern and texture analysis parameters are useful in predicting posterior instability in patients with PCL injury. Evaluation of the bone microarchitecture resulting from altered biomechanics could advance the understanding of PCL function and improve the detection of PCL injury.

• 한국융합학회논문지
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• 제9권9호
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• pp.183-189
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• 2018

본 연구는 마주보는 두 대칭렌즈를 가지는 초점거리 24mm 인 MWIR($3{\sim}5{\mu}m$)용 결상광학계의 설계 개발에 관한 것이다. 광학계는 CodeV를 사용하여 설계하였으며, 사용자의 요구조건을 만족할 수 있는 분해능과 화각을 가지도록 최적화 과정을 진행하였다. 렌즈의 초자는 국내에서 개발된 $3{\mu}m$에서 굴절률 1.7589를 갖는 초자( KCIR035 )를 포함하여 두 종류로 제한하였다. 이렇게 설계되어진 광학계는 같은 모양을 갖는 KCIR035 초자의 2장의 비구면 렌즈와 1장의 Si 초자의 구면 렌즈로 이루어져 있다. 여기서 2장의 비구면 렌즈의 배치는 마주보는 대칭구조를 이루고 있는 것이 특징이다. 그리고 이 광학계는 선폭 20lp/mm에서 MTF값이 0.35 이상인 분해능을 갖게 되었다. 따라서 이 광학계는 pixel의 크기가 $25{\mu}m$인 $206{\times}156$ 어레이 MWIR 검출소자를 사용하는 열영상 카메라에 적용할 수 있는 성능을 가진 것으로 판단된다.

• Imaging Science in Dentistry
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• 제41권2호
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• pp.53-57
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• 2011

Purpose : The purpose of this study was to evaluate the diagnostic performance of dental students in detection of mandibular condyle fractures and the effectiveness of reference panoramic images. Materials and Methods : Forty-six undergraduates evaluated 25 panoramic radiographs for condylar fractures and the data were analyzed through receiver operating characteristic (ROC) analysis. After a month, they were divided into two homogeneous groups based on the first results and re-evaluated the images with (group A) or without (group B) reference images. Eight reference images included indications showing either typical condylar fractures or anatomic structures which could be confused with fractures. Paired t-test was used for statistical analysis of the difference between the first and the second evaluations for each group, and student�fs t-test was used between the two groups in the second evaluation. The intra- and inter-observer agreements were evaluated with Kappa statistics. Results : Intra- and inter-observer agreements were substantial (k=0.66) and moderate (k=0.53), respectively. The area under the ROC curve (Az) in the first evaluation was 0.802. In the second evaluation, it was increased to 0.823 for group A and 0.814 for group B. The difference between the first and second evaluations for group A was statistically significant (p<0.05), however there was no statistically significant difference between the two groups in the second evaluation. Conclusion : Providing reference images to less experienced clinicians would be a good way to improve the diagnostic ability in detecting condylar fracture.

• International Journal of Fluid Machinery and Systems
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• 제8권2호
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• pp.73-84
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• 2015

Aerating hydroturbines have recently been proposed as an effective way to mitigate the problem of low dissolved oxygen in the discharge of hydroelectric power plants. The design of such a hydroturbine requires a precise understanding of the dependence of the generated bubble size distribution upon the operating conditions (viz. liquid velocity, air ventilation rate, hydrofoil configuration, etc.) and the consequent rise in dissolved oxygen in the downstream water. The purpose of the current research is to investigate the effect of location of air injection on the resulting bubble size distribution, thus leading to a quantitative analysis of aeration statistics and capabilities for two turbine blade hydrofoil designs. The two blade designs differed in their location of air injection. Extensive sets of experiments were conducted by varying the liquid velocity, aeration rate and the hydrofoil angle of attack, to characterize the resulting bubble size distribution. Using a shadow imaging technique to capture the bubble images in the wake and an in-house developed image analysis algorithm, it was found that the hydrofoil with leading edge ventilation produced smaller size bubbles as compared to the hydrofoil being ventilated at the trailing edge.

• 동의신경정신과학회지
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• 제33권1호
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• pp.113-122
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• 2022

Objectives: To report the effect of Korean medicine on a patient with insomnia from severe hot flashes. Methods: The patient suffered from extreme hot flashes for months. Symptoms were so severe that the patient attempted suicide. After starting psychiatric medication, symptoms persisted and hospitalization began. During hospitalization, herbal medicine, acupuncture, and psychotherapy were conducted. For evaluating therapeutical effect, Digital Infrared Thermal Imaging was performed twice during the treatment process. It was divided into major facial area and back area. The facial area was divided into two small units to measure the difference in temperature between two points. The back area was measured in the same way. Results: The temperature difference between the two points decreased over time and the patient's subjective symptoms reduced. Conclusions: Korean medicine therapy can improve symptoms of patients with insomnia accompanied by hot flashes.

• 생물정신의학
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• 제24권4호
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• pp.225-234
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• 2017

Objectives Local gyrification reflects the early neural development of cortical connectivity, and is regarded as a potential neural endophenotype in psychiatric disorders. Several studies have suggested altered local gyrification in patients with bipolar I disorder (BD-I). The purpose of the present study was to investigate the alterations in the cortical gyrification of whole brain cortices in patients with BD-I. Methods Twenty-two patients with BD-I and age and sex-matched 22 healthy controls (HC) were included in this study. All participants underwent T1-weighted structural magnetic resonance imaging (MRI). The local gyrification index (LGI) of 66 cortical regions were analyzed using the FreeSurfer (Athinoula A. Martinos Center for Biomedical Imaging). One-way analysis of covariance (ANCOVA) was used to analyze the difference of LGI values between two groups adjusting for age and sex as covariates. Results The patients with BD-I showed significant hypogyria in the left pars opercularis (uncorrected-p = 0.049), the left rostral anterior cingulate gyrus (uncorrected-p = 0.012), the left caudal anterior cingulate gyrus (uncorrected-p = 0.033). However, these findings were not significant after applying the multiple comparison correction. Severity or duration of illness were not significantly correlated with LGI in the patients with BD-I. Conclusions Our results of lower LGI in the anterior cingulate cortex and the ventrolateral prefrontal cortex in the BD-I group implicate that altered cortical gyrification in neural circuits involved in emotion-processing may contribute to pathophysiology of BD-I.

• 전자공학회논문지
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• 제53권10호
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• pp.109-115
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• 2016

이 논문에서는 레이저를 통한 진동판 스캔과 열화상 카메라를 사용한 진동판 촬영, 두 가지 방법을 비교하며 슬림 스피커의 분할 진동을 검출하는 방법에 대해 살펴본다. 슬림 스피커는 평판형의 구조적인 특성상 분할진동이 두드러지게 나타나고, 설치되는 공간이 좁아 무빙 코일에서 발생하는 열의 냉각이 제한적이다. 이런 특성으로 인해 슬림 스피커에서 분할진동이 제품의 품질에 큰 영향을 미친다. 본 연구에서는 진동판에서 일어나는 분할진동의 영향과 무빙 코일에 의한 진동판의 열전달 관계를 비교 탐색한다. 비교를 위한 실험은 분할진동 모드의 측정과 진동판의 열 변화 측정을 진동판 스캔과 열화상 카메라 촬영의 2단계의 실험으로 진행한다. 동일 주파수에서 발생하는 분할진동 모드와 열전달 형태를 비교하여 서로 간에 어떤 영향을 미치고 있는 지 파악할 수 있다. 그리고 이를 통해 발견한 연관성을 통해 쉽게 촬영할 수 있는 열화상만으로도 슬림 스피커가 가지는 분할진동의 형태와 경향성을 빠르게 파악하여 최적 설계에 도움이 되는 자료로 사용할 수 있을 것이다.

• 혜화의학회지
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• 제8권1호
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• pp.827-836
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• 1999

Numerous persons complained dyspepsia even though no specific objective findings are revealed by imaging study, laboratory examinations and other clinical research. To find out of so many symptoms what they are, I would to approach by two ways. One way is oriental medical literatural study and the other is Helicobacter pylori infection that is accepted as one of most important causal factors of many gastric diseases. Background/Aims: Recently, the role of Helicobacter pylori as a causal factor in the etiology of gastric cancer, peptic ulcer, gastritis and low-grade gastric mucosa-associated lymphoid tissue(MALT) lymphoma is well known. Using endoscopy, biopsy urease testing and histology are recommanded as the tests of choice. Serological test is not recommanded at the moment because of its low sensitivity and espicially low specificity. The urea breath test is more sensitive and specific noninvasive test than serologic test, but it is not widely available yet. Methods/Results: We studied 90 cases by diagnostic endoscopy as a screening test for the persons complaining gastrointestinal symptoms. As a result eighteen persons are revealed to be Helicoacter pylori infected histologicaly. Conclusion: More specific literatural studies are requied.