• Journal of Korean Neurosurgical Society
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• 제45권1호
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• pp.11-15
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• 2009

Objective : The aim of study was to review our patient population to determine whether there is a critical aneurysm size at which the incidence of rupture increases and whether there is a correlation between aneurysm size and location. Methods : We reviewed charts and radiological findings (computed tomography (CT) scans, angiograms, CT angiography, magnetic resonance angiography) for all patients operated on for intracranial aneurysms in our hospital between September 2002 and May 2004. Of the 336 aneurysms that were reviewed, measurements were obtained from angiograms for 239 ruptured aneurysms by a neuroradiologist at the time of diagnosis in our hospital. Results : There were 115 male and 221 female patients assessed in this study. The locations of aneurysms were the middle cerebral artery (MCA, 61), anterior communicating artery (ACoA, 66), posterior communicating artery (PCoA, 52), the top of the basilar artery (15), internal carotid artery (ICA) including the cavernous portion (13), anterior choroidal artery (AChA, 7), A1 segment of the anterior cerebral artery (3), A2 segment of the anterior cerebral artery (11), posterior inferior cerebellar artery (PICA, 8), superior cerebellar artery (SCA, 2), P2 segment of the posterior cerebral artery (1), and the vertebral artery (2). The mean diameter of aneurysms was $5.47{\pm}2.536\;mm$ in anterior cerebral artery (ACA), $6.84{\pm}3.941\;mm$ in ICA, $7.09{\pm}3.652\;mm$ in MCA and $6.21{\pm}3.697\;mm$ in vertebrobasilar artery. The ACA aneurysms were smaller than the MCA aneurysms. Aneurysms less than 6 mm in diameter included 37 (60.65%) in patients with aneurysms in the MCA, 43 (65.15%) in patients with aneurysms in the ACoA and 29 (55.76%) in patients with aneurysms in the PCoA. Conclusion : Ruptured aneurysms in the ACA were smaller than those in the MCA. The most prevalent aneurysm size was 3-6 mm in the MCA (55.73%), 3-6 mm in the ACoA (57.57%) and 4-6 mm in the PCoA (42.30%). The more prevalent size of the aneurysm to treat may differ in accordance with the location of the aneurysm.

• Nuclear Engineering and Technology
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• 제47권4호
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• pp.479-487
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• 2015

The thallium-doped sodium iodide [NaI(Tl)] scintillation detector is preferred as a gamma spectrometer in many fields because of its general advantages. A silicon photomultiplier (SiPM) has recently been developed and its application area has been expanded as an alternative to photomultiplier tubes (PMTs). It has merits such as a low operating voltage, compact size, cheap production cost, and magnetic resonance compatibility. In this study, an array of SiPMs is used to develop an NaI(Tl) gamma spectrometer. To maintain detection efficiency, a commercial NaI(Tl) $2^{\prime}{\times}2^{\prime}$ scintillator is used, and a light guide is used for the transport and collection of generated photons from the scintillator to the SiPMs without loss. The test light guides were fabricated with polymethyl methacrylate and reflective materials. The gamma spectrometer systems were set up and included light guides. Through a series of measurements, the characteristics of the light guides and the proposed gamma spectrometer were evaluated. Simulation of the light collection was accomplished using the DETECT 97 code (A. Levin, E. Hoskinson, and C. Moison, University of Michigan, USA) to analyze the measurement results. The system, which included SiPMs and the light guide, achieved 14.11% full width at half maximum energy resolution at 662 keV.

• 대한후두음성언어의학회지
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• 제15권1호
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• pp.31-36
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• 2004

Background and Objectives : It has been shown that the epilaryngeal tube in the human airway is responsible for vocal ring, or the singer's formant. In previous study, authors showed that in trained tenors, besides the conventional singer's formant in the region of ,5500Hz, another energy peak was observed in the region of 8,000Hz. This peak was interpreted as the second resonance of the epilarynx tube. Singers in other voice categories who produce vocal ring are assumed to have the same peak, but no measurements have as yet been made. Materials and Methods : Fifteen tenors, fourteen baritones, seven sopranos and five mezzo sopranos attending the music college, department of vocal music who could reliably produce the head and chest registers were chosen for this study. Each subject was asked to produce an/ah/sound for at least three seconds for the head register sound(tenors ; G4, barions ; E4 sopranos ; F5 and mezzosopranos ; C5) and for the chest register sound (tenors ; C3, baritones ; D3, sopranos ; D4 and Mezzosoprano ; A3). The sound data was analyzed using the Fast Fourier Transform (FFT)-based power spectrum, Long term average(LTA) power spectrum using the FFT algorithm of the Computerized Speech Lab (CSL, Kay elemetrics, Model 4300B, USA). Statistical analysis was performed using the Mann-Whitney test of the Statistical Package for Social sciences(SPSS). Results : For head register sounds, a significant increase was seen in the 2,200-3,400Hz region(p<0.05) and the Similar to the head register sounds, there was a significant increase in energy in the four trained singer group compared with the untrained group in the 2,200-3,100Hz region(p<0.05), the 7,800-8,400Hz region(p<0.05) for the chest register sounds. Conclusions : When good vocal production was made for the head and chest registers, an energy peak was observed near 2,500Hz, a frequency already known as the "singer's formant', in all subjects in the study group. Another region of increased energy was observed around 8,000Hz that had not been noticed previously. The authors believe this region to be the second singer's formant.

• Asian Pacific Journal of Cancer Prevention
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• 제16권12호
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• pp.5019-5024
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• 2015

Background: The purpose of this study was to assess the dosimetric and clinical feasibility of volumetric modulated arc based hypofractionated stereotactic radiotherapy (RapidArc) treatment for large acoustic schwannoma (AS >10cc). Materials and Methods: Ten AS patients were immobilized using BrainLab mask. They were subject to multimodality imaging (magnetic resonance and computed tomography) to contour target and organs at risk (brainstem and cochlea). Volumetric modulated arc therapy (VMAT) based stereotactic plans were optimized in Eclipse (V11) treatment planning system (TPS) using progressive resolution optimizer-III and final dose calculations were performed using analytical anisotropic algorithm with 1.5 mm grid resolution. All AS presented in this study were treated with VMAT based HSRT to a total dose of 25Gy in 5 fractions (5fractions/week). VMAT plan contains 2-4 non-coplanar arcs. Treatment planning was performed to achieve at least 99% of PTV volume (D99) receives 100% of prescription dose (25Gy), while dose to OAR's were kept below the tolerance limits. Dose-volume histograms (DVH) were analyzed to assess plan quality. Treatments were delivered using upgraded 6 MV un-flattened photon beam (FFF) from Clinac-iX machine. Extensive pretreatment quality assurance measurements were carried out to report on quality of delivery. Point dosimetry was performed using three different detectors, which includes CC13 ion-chamber, Exradin A14 ion-chamber and Exradin W1 plastic scintillator detector (PSD) which have measuring volume of $0.13cm^3$, $0.009cm^3$ and $0.002cm^3$ respectively. Results: Average PTV volume of AS was 11.3cc (${\pm}4.8$), and located in eloquent areas. VMAT plans provided complete PTV coverage with average conformity index of 1.06 (${\pm}0.05$). OAR's dose were kept below tolerance limit recommend by American Association of Physicist in Medicine task group-101(brainstem $V_{0.5cc}$ < 23Gy, cochlea maximum < 25Gy and Optic pathway <25Gy). PSD resulted in superior dosimetric accuracy compared with other two detectors (p=0.021 for PSD.

• Asian Pacific Journal of Cancer Prevention
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• 제15권15호
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• pp.6155-6160
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• 2014

Background: This study was conducted to investigate whether apparent diffusion coefficient (ADC) measurements by dividing the liver into left and right hepatic lobes may be utilized to improve the accuracy of differential diagnosis of benign and malignant focal liver lesions. Materials and Methods: A total of 269 consecutive patients with 429 focal liver lesions were examined by 3-T magnetic resonance imaging that included diffusion-weighted imaging. For 58 patients with focal liver lesions of the same etiology in left and right hepatic lobes, ADCs of normal liver parenchyma and focal liver lesions were calculated and compared using the paired t-test. For all 269 patients, ADC cutoffs for focal liver lesions and diagnostic accuracy in the left hepatic lobe, right hepatic lobe and whole liver were evaluated by receiver operating characteristic curve analysis. Results: For the group of 58 patients, mean ADCs of normal liver parenchyma and focal liver lesions in the left hepatic lobe were significantly higher than those in the right hepatic lobe. For differentiating malignant lesions from benign lesions in all patients, the sensitivity and specificity were 92.6% and 92.0% in the left hepatic lobe, 94.4% and 94.4% in the right hepatic lobe, and 90.4% and 94.7% in the whole liver, respectively. The area under the curve of the right hepatic lobe, but not the left hepatic lobe, was higher than that of the whole liver. Conclusions: ADCs of normal liver parenchyma and focal liver lesions in the left hepatic lobe were significantly higher than those in the right hepatic lobe. Optimal ADC cutoff for focal liver lesions in the right hepatic lobe, but not in the left hepatic lobe, had higher diagnostic accuracy compared with that in the whole liver.

• 한국정보통신학회논문지
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• 제19권10호
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• pp.2223-2231
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• 2015

본 논문에서는 기존의 평면형 모노폴 안테나에서 변형된 구조를 갖는 무선 USB 동글용 내장형 안테나를 제안한다. 제안된 안테나는 기존의 모노폴 구조에 'n' 구조를 결합 한 후 Strip1, Strip2, Strip3를 삽입하여 이중 광대역 특성을 구현하였고, 50-Ω 동축케이블을 이용하여 급전하였다. 안테나는 유전율 4.4인 FR-4 기판 위에 설계되었고 전체 크기는 10 mm(W) × 50 mm(L) × 1mm(t) 이다. 반사손실 측정 결과 -10dB를 기준으로 740 MHz (2.26 ~ 3.0 GHz), 1,200 MHz (5.16 ~ 6.36 GHz)의 이중 공진 특성을 확인하였다. 또한 동작 주파수 대역에서 전방향의 방사패턴을 얻었으며, 2.4 GHz대역에서 최대이득 2.26∼3.81 dBi 그리고 5.5 GHz대역에서 최대이득 2.21∼5.79 dBi의 값을 얻었다.

• 한국자기학회지
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• 제16권1호
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• pp.102-106
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• 2006

이 연구의 목적은 약물의 분리나 약물전달 시스템에 이용 할 수 있도록 마그네타이트 나노 입자의 표면을 개질, 즉 생체적합성, 저독성의 특성을 갖는 키토산을 이용하여 키토산이 피복된 나노 크기의 자성체 입자를 제조하는 것이다. 본 연구에서는 음향화학법을 적용한 공침 기술을 이용, 균일한 마그네타이트 나노 입자를 합성하였다. 계면활성제인 올레인산을 가하여 입자간의 응집을 막았다. 물과 계면활성제의 농도비 R=[물]/[계면활성제]를 조절하여 평균크기가 2nm에서 9nm인 마그네타이트 입자를 선택적으로 합성하였다. 이 방법을 통하여 합성된 마그네타이트 나노 인자를 염기성 수용액에 분산시켰다. 초음파를 조사하면서 키토산 용액을 서서히 가하여 마그네타이트 나노 입자의 표면을 키토산으로 피복하였다. 이때 키토산의 농도가 증가할수록 입자가 수 나노미터 크기씩 증가하는 것을 입도 분석기와 원자 현미경 관찰을 통해서 확인 할 수 있었다. 합성된 마그네타이트 분말과 키토산이 피복된 마그네타이트 나노 입자 모두 실온에서 초상자성을 보이는 것으로 나타났다.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제23권2호
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• pp.57-62
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• 2012

Objectives : Characteristic symptoms, including hyperactivity and easy distractibility, in children with attention-deficit hyperactivity disorder (ADHD) suggest that their brain status, even at rest, might differ from that of healthy children. This study was conducted in order to determine whether resting state brain activity is compromised in medication-naive children with ADHD. Methods : Twenty medication-naive children with ADHD (mean age $10.3{\pm}2.5$) and 28 age- and gender-matched healthy volunteers (mean age $10.3{\pm}2.0$) underwent measurements for resting state brain activity using functional magnetic resonance imaging (fMRI). Among resting state related-independent components (RSICs) extracted from fMRI data using independent component analysis, a significant difference in RSICs was observed between groups, using a mixed Gaussian/gamma model. Results : Except for IQ, which was higher in the healthy control group, no demographic difference was observed between the two groups (p<.001). Significantly less activation of one RSIC, which includes the bilateral precuneus/posterior cingulate cortex, occipito-temporal junction, and anterior cingulate cortex, was observed in the ADHD group, compared with the control group (p<.05). Conclusion : An abnormal RSIC, posterior default mode network (DMN), was observed in the medication-naive ADHD group. Results of our study suggest that abnormality of posterior DMN is one of the main pathophysiologies of ADHD.

• 디지털융복합연구
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• 제11권11호
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• pp.613-620
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• 2013

본 연구는 MRI를 사용하여 급성 및 만성 요통환자들의 척추주변근육에 나타나는 변화를 정량적으로 측정 및 분석하고 이를 토대로 요통에 대한 진단 및 치료에 임상적 기초자료를 제공하고자 2012년 8월부터 2013년 1월까지 내원한 환자로 요통이 발생한지 12주 이내의 급성요통환자 20명과 요통이 발생한지 12주 이상 경과된 만성 요통 환자 20명을 대상자로 선정하여 MRI를 촬영한 후 측정하여 비교하였다. 왼쪽과 오른쪽의 지방변성율에서는 척추세움근과 뭇갈래근에서 유의한 차이가 있었고(p<.001), 전체 집단 간 지방변성율 비교에서도 급성요통군과 만성요통군간의 큰허리근, 척추세움근, 뭇갈래근에서 유의한 차이가 있었다(p<.001). 사후검정에서는 급성요통군과 만성요통군에서 각각 다열근과 척추세움근의 지방변성율이 가장 높은 것으로 나타났다. 만성 요통군에서 다열근과 척추기립근의 심한 지방율의 변성은 척추의 안정성을 유지하는 근육의 근력 약화로 나타나는데 본 연구결과를 토대로 급성 만성요통환자들의 재활운동과정에 있어서 뭇갈래근, 급성 요통군은 뭇갈래근과 큰허리근에 더 주의를 기울이고 재활운동 선정 과정에서 중요한 자료와 근거를 제시 할 수 있으라고 사료된다.

• 구강회복응용과학지
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• 제34권1호
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• pp.32-38
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• 2018

목적: 3.6 mm 이하 좁은 직경 임플란트의 일정 기간 생존율을 초기고정 값과 방사선학적 계측을 통해 분석해보고자 하였다. 연구 재료 및 방법: 24명의 환자에 식립된 직경 3.6 mm 이하, 길이 7 mm 이상의 38개의 임플란트를 조사하였다. 식립된 임플란트의 platform 직경, body 직경, 길이, 식립 부위 등을 확인하였고 식립 시 골유도재생술의 동반 시행 여부, 완성된 보철의 형태를 확인하였다. 초기고정 값은 임플란트 식립 직후 측정한 implant stability quotient (ISQ) 값을 확인하였고, 방사선 사진을 통해 식립된 임플란트의 근 원심 marginal bone level (MBL)을 측정하였다. 결과: 전체 임플란트의 생존율은 92.11% 이었고 ISQ값은 평균 66.26으로 나타났다. 생존한 임플란트의 MBL 변화는 평균 $0.14{\pm}0.31mm$를 나타내었다. Platform 직경이 body 직경보다 큰 임플란트 중 실패한 임플란트는 없었다. 결론: 좁은 직경의 임플란트는 좁은 직경의 치조제에 안정적인 치료 결과를 나타낸다 사료된다.