• 전자공학회논문지 IE
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• 제46권4호
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• pp.42-48
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• 2009

본 논문에서는 전송 대역폭에 따라 손실을 최소화하며 적응적으로 압축률을 조절하는 준무손실 영상 부호화 알고리즘을 제안한다. 제안하는 방법은 슬라이스 부호화 간격으로 부호화된 비트량과 목표 부호화 비트량을 이용하여 적응적으로 허용 오류 범위를 변경한다. 실험 결과, 제안하는 방법은 기존 알고리즘들에 비하여 효과적으로 전송 대역폭에 맞추어 압축률을 조절할 뿐만 아니라 화질 또한 향상됨을 알 수 있다.

• 동력기계공학회지
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• 제6권2호
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• pp.54-59
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• 2002

The principle of the FDM(fused deposition modeling) process is based on the layer by layer manufacturing technology, like other RP(rapid prototyping) process. In the FDM process, each layer may have different shape. Therefore, the built model may have stairs shape on its surface. This stairs shape is one of the serious problems in the FDM process. Thus in this study, cube models and spherical models were fabricated by FDM process to investigate the influence of injection amount on surface roughness. Models with various road width were also built to investigate the influence of road width on surface roughness. Surface roughness of the models was measured and analyzed. The result obtained in this study are expected to help selecting the part build orientation for optimum surface roughness.

• 디지털산업정보학회논문지
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• 제6권2호
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• pp.11-17
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• 2010

In this paper, we propose efficient rate control algorithm for video near-lossless compression. The proposed method adjusts pixel error range using amounts of previous encoded bits and target bits at a slice encoding interval. Thus, encoded bits by the proposed method are transmitted well through limited bandwidth without overflow. Also, target bits and encoded bits can be controlled according to transmission policy. Experimental results show that our proposed method not only almost fits compression ratio, but also has better image quality.

• The Korean Journal of Physiology and Pharmacology
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• 제7권6호
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• pp.295-301
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• 2003

Striatum plays a crucial role in the movement control and habitual learning. It receives an information from wide area of cerebral cortex as well as an extensive serotonergic (5-hydroxytryptamine, 5-HT) input from raphe nuclei. In the present study, the effects of 5-HT to modulate synaptic transmission were studied in the rat corticostriatal brain slice using in vitro extracellular recording technique. Synaptic responses were evoked by stimulation of cortical glutamatergic inputs on the corpus callosum and recorded in the dorsal striatum. 5-HT reversibly inhibited coticostriatal glutamatergic synaptic transmission in a dose-dependent fashion (5, 10, 50, and $10{\mu}M$), maximally reducing in the corticostriatal population spike (PS) amplitude to $40.1{\pm}5.0$% at a concentration of $50{\mu}M$ 5-HT. PSs mediated by non-NMDA glutamate receptors, which were isolated by bath application of the NMDA receptor antagonist, d,l-2-amino-5-phospohonovaleric acid (AP-V), were decreased by application of $50{\mu}M$ 5-HT. However, PSs mediated by NMDA receptors, that were activated by application of zero $Mg^{2+}$ aCSF, were not significantly affected by $50{\mu}M$ 5-HT. To test whether the corticostriatal synaptic inhibitions by 5-HT might involve a change in the probability of neurotransmitter release from presynaptic nerve terminals, we measured the paired-pulse ratio (PPR) evoked by 2 identical pulses (50 ms interpulse interval), and found that PPR was increased ($33.4{\pm}5.2$%) by 5-HT, reflecting decreased neurotransmitter releasing probability. These results suggest that 5-HT may decrease neurotransmitter release probability of glutamatergic corticostriatal synapse and may be able to selectively decrease non-NMDA glutamate receptor-mediated synaptic transmission.

• 한국방사선학회논문지
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• 제7권4호
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• pp.307-311
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• 2013

본 논문에서는 피폭선량 절감을 위해 기존의 선량보다 낮은 선량으로 CT검사를 했을 경우에 병변의 유무를 충분히 가릴 수 있는지 scan parameter(절편두께, Helical Pitch)와 3차원으로 영상재구성시 threshold값의 설정에 따른 영상의 변화정도를 3차원 영상화를 통하여 시료의 체적 변화를 알아보고, 피폭선량절감을 위한 CT에서 허용 가능한 scan parameter를 찾고자 연구를 시도하였다. 실험방법으로는 실리콘을 이용하여 시료를 제작하였으며, 이때 시료의 크기는 직경이 50, 40, 30, 20, 10mm로 10mm 간격으로 5개의 구형 모형을 제작하였고, 5개의 시료를 관전압, 관전류를 각각 120Kvp, 50mA로 고정하고, 단면두께(1.0, 2.0, 3.0, 5.0, 7.0mm), Helical Pitch(1.5, 2.0, 3.0)를 각각 변화시켜 Scan 하고 영상 간의 interval은 (1.0, 2.0, 3.0, 5.0, 7.0mm)로 구성하여, 영상을 workstation으로 전송하고, Volume Rendering Technique를 사용하여 threshold(-200,-50,50 ~1,000) 값을 변화시키면서 3차원 영상으로 재구성하고, 시료의 체적을 측정하였다. 실험결과 Helical pitch가 1.5일 때 체적변화가 가장 적었고, Helical pitch가 3.0일 때 체적변화가 가장 많이 감소하였으며, 절편두께가 증가할수록 시료의 체적도 실측치보다 감소한다는 것을 실험을 통해 확인 할 수 있었다. 또한 3차원 영상재구성시 threshold 범위를 -200~1,000으로 설정한 경우, 시료의 체적의 변화가 가장 적은 것으로 나타났다.

• 대한디지털의료영상학회논문지
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• 제17권1호
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• pp.13-18
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• 2015

Purpose : Skip the repetitive HRCT axial scan in order to reduce the exposure of patients during chest HRCT scan, Helical Scan Data into a reconstructed image, and exposure of the patient change and visually evaluate the usefulness of the HRCT images. Materials and method : Patients were enrolled in the survey are 50 people who underwent chest CT scans of patients who presented to the hospital from January 2015 to March 2015. 50 people surveyed 22 people men and 28 people women people showed an average distribution of 30 to 80 years age was 48 years. 50 patients to Somatom Sensation 64 ch (Siemens) model with 120 kVp tube voltage to a reference mAs tube current to mAs (Care dose, Siemens) as a whole, including the lungs and the chest CT scan was performed. Scan upon each patient CARE dose 4D (Automatic exposure control, Siemens Medical Solution Erlangen, Germany) was to maintain the proper radiation dose scan every cross-section through a device that automatically adjusts the tube current of. CT scan is the rotation time of the Tube slice collimation, slice width 0.6 mm, pitch factor was made under the terms of 1.4. CT scan obtained after the raw data (raw data) to the upper surface of the axial images and coronal images for each slice thickness 1 mm, 5 mm intervals in the high spatial frequency calculation method (hight spatial resolution algorithm, B60 sharp) was the use of the lung window center -500 HU, windows were reconstructed into images in the interval -1000 HU to see. Result : 1. Measure the total value of DLP 50 patients who proceed to chest CT group A (Helical Scan after scan performed with HRCT) and group B (Helical Scan after the HR image reconstruction to the original data) compared with the group divided, analysis As a result of the age, but show little difference for each age group it had a decreased average dose of about 9%. 2. A Radiation read the results of the two Radiologist and a doctor upper lobe and middle lobe of the lung takes effect the visual evaluation is not a big difference between the two images both, depending on the age of the patient, especially if the blood vessels of the lower lobe (A: 3.4, B: 4.6) and bronchi(A: 3.8, B4.7) image shake caused by breathing in anxiety (blurring lead) to the original data (raw data) showed that the reconstructed image is been more useful in diagnostic terms. Conclusion : Scan was confirmed a continuous, rapid motion video to get Helical scan is much lower lobe lung reduction in visual blurring, Helical scan data to not repeat the examination by obtaining HRCT images reorganization reduced the exposure of the patient.

• Radiation Oncology Journal
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• 제36권2호
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• pp.114-121
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• 2018

Purpose: To explore the feasibility of maximum diameter as a response assessment method for vestibular schwannomas (VS) after stereotactic radiosurgery or fractionated stereotactic radiotherapy (RT), we analyzed the concordance of RT responses between maximum diameters and volumetric measurements. Materials and Methods: Forty-two patients receiving curative stereotactic radiosurgery or fractionated stereotactic RT for VS were analyzed retrospectively. Twelve patients were excluded: 4 did not receive follow-up magnetic resonance imaging (MRI) scans and 8 had initial MRI scans with a slice thickness >3 mm. The maximum diameter, tumor volume (TV), and enhanced tumor volume (ETV) were measured in each MRI study. The percent change after RT was evaluated according to the measurement methods and their concordances were calculated with the Pearson correlation. The response classifications were determined by the assessment modalities, and their agreement was analyzed with Cohen kappa statistics. Results: Median follow-up was 31.0 months (range, 3.5 to 86.5 months), and 90 follow-up MRI studies were analyzed. The percent change of maximum diameter correlated strongly with TV and ETV (r(p) = 0.85, 0.63, p = 0.000, respectively). Concordance of responses between the Response Evaluation Criteria in Solid Tumors (RECIST) using the maximum diameters and either TV or ETV were moderate (kappa = 0.58; 95% confidence interval, 0.32-0.85) or fair (kappa = 0.32; 95% confidence interval, 0.05-0.59), respectively. Conclusions: The percent changes in maximum diameter and the responses in RECIST were significantly concordant with those in the volumetric measurements. Therefore, the maximum diameters can be used for the response evaluation of VS following stereotactic RT.

• 한국터널지하공간학회 논문집
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• 제12권3호
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• pp.239-245
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• 2010

본 논문에서는 방대한 크기의 지상 레이저 스캔 자료로부터 터널의 내공 단면을 효율적으로 추출하기 위하여, 헤시(hash) 기반 구조체를 이용한 터널 중심선 자동 추정 및 터널 내공 단면 구성 포인트 클라우드 추출 방식을 제안하였다. 즉, 헤시 기반 구조체에 입력한 레이저 스캔 자료로부터 일정한 방향의 단면들을 추출한 후 각 단면의 중심점을 연결하여 터널의 중심선을 추정하였으며, 추정된 중심선을 따라 일정 간격 및 두께로 터널 내공 단면 구성 포인트 클라우드를 추출하였다. 결과적으로 약 750만개의 포인트로 구성된 레이저 스캔 자료로부터 1 m 간격으로 0.1 m 두께의 단면 구성 포인트 클라우드를 추출하는데 3초미만의 시간이 소요되었으며 메모리는 124 MB가 소요되었다. 그러나 터널 중심선 추정 후 오류 포인트 제거, 시점 및 종점 추가 작업을 수동으로 수행해야 히는 한계도 드러내었다.

• 대한방사선치료학회지
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• 제19권1호
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• pp.27-33
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• 2007

목 적: 본원에서는 AVM (artery vein malformation)이나 뇌종양을 치료를 위하여 뇌정위방사선수술(SRS: stereotactic radiosurgery)을 시행한다. 치료위치의 확인과 선량을 검증하기위하여 본 연구에서는 Gafchromic EBT film (Gafchromic EBT QD+, International Specialty Products, USA)을 이용 두부팬톰 내의 선량분포를 계산치와 측정치를 비교하였다. 대상 및 방법: 본 실험에서는 기존의 인체모형팬톰의 두부의 2.5 cm 두께 한 슬라이스를 5장의 0.5 cm 아크릴로 대체하여 필름을 0.5 cm 간격으로 삽입할 수 있게 하였다. 4장의 필름과 5장의 아크릴판은 팬톰 단면모양을 따라 잘랐다. 이 두부팬톰에 실제 환자치료와 같은 절차로 SRS head ring과 localizer를 장착 후 0.5 cm 간격의 CT 영상을 얻어 치료계획을 수립하였다. 6 MV의 광자선을 2 cm 크기의 SRS cone을 장착하여 5개의 arc beam으로 300 cGy의 선량을 전달하였다. 필름 교정을 위해서 각각의 필름에 0, 50, 100, 200, 300, 400, 500, 600, 700, 800, 900 cGy의 선량을 조사하여 교정곡선을 얻었다. 3시간 후 팬톰내의 필름을 스캔하고 흑화도에 따른 선량으로 교정하였다. 뇌정위방사선수술의 평가를 위해 Gafchromic EBT 필름을 이용 두부팬톰 내 치료 위치를 확인하고 선량을 측정하여 계산 값과 비교하였다. 결 과: Gafchromic $EBT^{(R)}$ 필름의 선량교정 곡선은 900 cGy까지 선형을 잘 유지하였다. 모든 단면에 걸쳐 Gafchromic $EBT^{(R)}$ 필름을 이용한 두부팬톰 내 필름으로 측정한 선량과 치료계획장치(XKnife, Radionics, USA)로 계산된 선량의 차이는 5% 이내 였다. 결 론: 본 실험에서 2차원적 선량분석만이 가능한 GafChromic EBT 필름을 적층시켜 모든 슬라이스의 선량을 확인할 수 있었으며, Gafchromic $EBT^{(R)}$ 필름을 이용한 정위방사선수술에서 정도관리의 방법으로 가능할 것으로 사료된다.

• 한국운동역학회지
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• 제12권1호
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• pp.233-249
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• 2002

The purpose of this study was to employing MRI in the estimation of the biomechanical body segment parameters of Korean adults. for this purpose MRI study on 19 Korean living subjects were used to measurement. All the parameters that was concerned were inertial characteristics of human body mass of each segment, center of mass of them and the length of radius of gyration of them. The cross sectional images and saggital images of every 1cm interval were got using the 0.5 Tesla MRI from the top of head to the bottom of foot, whole body. And then, by tracing the images of the film and scanning them, got the area which the several tissues occupied in the image of slice. By summing the area of slice of each segment which were calculating and by multipling the density of the tissues, got the mass of segment and other inertial characteristics. The ratios of radius of gyration in both transverse axis and longitudinal axis though the segmental mass and segment length are as follow: male A : head($0.229\pm0.0029$), neck($0.256\pm0.0095$), thorax($0.374\pm0.0059$) abdomen($0.245\pm0.0020$), pelvis($0.368\pm0.0106$), thigh($0.288\pm0.0030$) shank($0.280\pm0.0043$), foot($0.277\pm0.0195$), upperarm($0.311\pm0.0074$) forearm($0.286\pm0.0051$), hand($0.253\pm0.0095$) female A : head($0.214\pm0.0032$), neck($0.254\pm0.0112$), thorax($0.295\pm0.0061$) abdomen($0.289\pm0.0021$), pelvis($0.329\pm0.0108$), thigh($0.288\pm0.0036$) shank($0.280\pm0.0047$), foot($0.243\pm0.0206$), upperarm($0.279\pm0.0083$) forearm($0.286\pm0.0048$), hand($0.229\pm0.0097$) male B : head($0.532\pm0.0006$), neck($0.533\pm0.0006$), thorax($0.658\pm0.0008$) abdomen($1.350\pm0.0022$), pelvis($0.875\pm0.0002$), thigh($0.213\pm0.0001$) shank($0.160\pm0.0001$), foot($0.152\pm0.0002$), upperarm($0.136\pm0.0002$) forearm($0.202\pm0.0002$), hand($0.273\pm0.0006$) female B : head($0.198\pm0.0002$), neck($0.335\pm0.0011$), thorax($0.238\pm0.0001$) abdomen($0.888\pm0.0001$), pelvis($1.318\pm0.0117$), thigh($0.095\pm0.0001$) shank($0.075\pm0.0001$), foot($0.181\pm0.0006$), upperarm($0.0.062\pm0.0001$) forearm($0.083\pm0.0001$), hand($0.105\pm0.0007$).