• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.26.3-27
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• 2009

한 기의 영상레이더 위성을 이용하여 동일한 촬영지역에 대해 적절한 기선벡터(Baseline)을 유지하는 두 장(scene)의 영상을 획득하여 그 지역의 정밀 표고차를 추출하는 레이더 간섭계(Interferometry) 임무를 수행하기 위해서는 반복지상궤적을 유지하도록 위성의 궤도를 주기적으로 조정해 주어야 한다. 이 연구에서는 반복지상궤적 유지 정밀도를 극대화시키기 위하여 최적의 기준궤도를 생성하고 이를 유지하기 위한 속도증분 및 궤도 조정 일정을 산출할 수 있는 궤도최적화 S/W 를 개발하였다. 이 연구의 최적 궤도 설계 문제는 다음과 같다. "시작시간 $T_0$에서 초기 접촉궤도 상태벡터 (ECEF 위치 및 속도벡터) $x_0$이고, 지상궤적반복주기 p 이후의 시간 $T_0+p$에서도 초기 접촉궤도 상태벡터와 동일한$x_0$가 되도록 궤도를 유지하려고 할 때, 여명 궤도(dawn-dusk and sun-synchronous orbit)에서 운영되는 위성의 연료소모(또는 속도증분)를 최소화시키는 가상의 궤도조정(maneuver) 횟수, 시기, 크기를 찾아라." 이 연구에서는 궤도최적화 문제를 풀기 위하여 GRACE 중력모델(GGM02C)이 적용된 수치적 방법의 위성궤도예측 알고리즘을 시스템 설계에 적용하였고, 매개변수 최적화 방법 중 구속조건이 있는 비선형 최적화 기법의 하나인 연속 2차 계획법(sequential quadratic programming)을 사용하여 해를 구하였다. 개발된 궤도최적화 S/W의 성능을 분석하기 위하여 고도 550km의 여명궤도를 돌며 지상궤적반복주기가 28일인 영상레이더 위성에 대해 적용하였다. 해석 결과를 통해, 비록 시스템의 비선형이 큼에도 불구하고 최소의 속도증분으로 정밀한 반복지상궤적이 유지됨을 알 수 있었다.

• The Korean Journal of Applied Statistics
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• v.22 no.3
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• pp.585-594
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• 2009

Researchers of microarray experiment transpose processed images of raw data to possible data of statistical analysis: it is preprocessing. Preprocessing of microarray has image filtering, imputation and normalization. There have been studied about several different methods of normalization and imputation, but there was not further study on the order of the procedures. We have no further study about which things put first on our procedure between normalization and imputation. This study is about the identification of differentially expressed genes(DEG) on the order of the preprocessing steps using two-dye cDNA microarray in colon cancer and gastric cancer. That is, we check for compare which combination of imputation and normalization steps can detect the DEG. We used imputation methods(K-nearly neighbor, Baysian principle comparison analysis) and normalization methods(global, within-print tip group, variance stabilization). Therefore, preprocessing steps have 12 methods. We identified concordance measure of DEG using the datasets to which the 12 different preprocessing orders were applied. When we applied preprocessing using variance stabilization of normalization method, there was a little variance in a sensitive way for detecting DEG.

• The Korean Journal of Nuclear Medicine
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• v.39 no.6
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• pp.413-420
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• 2005

Purpose: Neuroreceptor PET studies require 60-120 minutes to complete and head motion of the subject during the PET scan increases the uncertainty in measured activity. In this study, we investigated the effects of the data-driven head mutton correction on the evaluation of endogenous dopamine release (DAR) in the striatum during the motor task which might have caused significant head motion artifact. Materials and Methods: $[^{11}C]raclopride$ PET scans on 4 normal volunteers acquired with bolus plus constant infusion protocol were retrospectively analyzed. Following the 50 min resting period, the participants played a video game with a monetary reward for 40 min. Dynamic frames acquired during the equilibrium condition (pre-task: 30-50 min, task: 70-90 min, post-task: 110-120 min) were realigned to the first frame in pre-task condition. Intra-condition registrations between the frames were performed, and average image for each condition was created and registered to the pre-task image (inter-condition registration). Pre-task PET image was then co-registered to own MRI of each participant and transformation parameters were reapplied to the others. Volumes of interest (VOI) for dorsal putamen (PU) and caudate (CA), ventral striatum (VS), and cerebellum were defined on the MRI. Binding potential (BP) was measured and DAR was calculated as the percent change of BP during and after the task. SPM analyses on the BP parametric images were also performed to explore the regional difference in the effects of head motion on BP and DAR estimation. Results: Changes in position and orientation of the striatum during the PET scans were observed before the head motion correction. BP values at pre-task condition were not changed significantly after the intra-condition registration. However, the BP values during and after the task and DAR were significantly changed after the correction. SPM analysis also showed that the extent and significance of the BP differences were significantly changed by the head motion correction and such changes were prominent in periphery of the striatum. Conclusion: The results suggest that misalignment of MRI-based VOI and the striatum in PET images and incorrect DAR estimation due to the head motion during the PET activation study were significant, but could be remedied by the data-driven head motion correction.

• Journal of Genetic Medicine
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• v.4 no.1
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• pp.38-44
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• 2007

Purpose : Menkes disease is an X-linked recessively inherited disorder caused by the mutation of the ATP7A gene encoding copper-transporting P-type AT Pase. The phenotypic features are progressive neurological degeneration, mental retardation, loose skin, and vascular complications. Early diagnosis and treatment are very important for the prognosis of Menkes disease. Here, we describe nov el mutations of the ATP7A gene and prenatal diagnosis by mutation analysis. Methods : Five unrelated Korean Menkes patients were included in this study. They presented with depigmented wool-like hair, progressive neurologic deterioration, and hypotonia in infancy. Serum copper and ceruloplasmin levels w ere decreased. Brain magnetic resonance imaging revealed tortuous intracranial vessels. Mutation analysis has been carried out using cDNA from cultured skin fibroblasts or genomic DNA from peripheral leukocytes. Prenatal diagnosis was performed in two cases using chorionic villi samples or amniocytes. Results : Four novel mutations have been identified from four different families; c.3511+1G>A (p.E1099_N1171delinsMfsX 18), c.4005+5 G>A (p.V1268_R1335del), c.1870_2172del (p.S624_Q724del), and c.3352 G>A (p.G1118S). T he remaining one was previously reported (c.1933 C>T (p.V 1268_R1335del)). On prenatal DNA analysis, one w as diagnosed as normal, while the other turned out to be a female heterozygote with p.S624_Q724del mutation of the ATP7A gene. Conclusion : We identified 4 novel mutations of the ATP7A gene. Prenatal diagnosis in families at risk is critical in order to choose preventiv e options including an early treatment with copper-histidine therapy or therapeutic termination. Most mutations of the ATP7A gene were frame-shift mutations and prenatal diagnosis has been successfully carried out.

• Electronics and Telecommunications Trends
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• v.27 no.3
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• pp.32-42
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• 2012

본고에서는 디지털 홀로그래피 기술을 디지털 콘텐츠 관점에서 다룰 수 있는 연구 개발 결과를 다루었다. 디지털 홀로그래피(DH: Digital Holographic) 기술을 디지털 홀로그래픽 콘텐츠 관점으로 접근하기 위한 기반 기술 분야로서 DH 콘텐츠 저작도구 기술, 매니지먼트 기술, 공간 인식 기반 인터랙션 기술, 화질 평가 및 휴먼팩터 기술 및 응용 콘텐츠 제작 기술 등으로 분류하여 기술하였다. 또한 디지털 홀로그래픽 콘텐츠 제작을 위한 연구 개발 결과로서 3차원 영상정보 획득, 홀로그래픽 프린지 데이터 생성과 DH 콘텐츠의 광학적 수치적 복원 및 DH 콘텐츠의 운용 테스트베드 등의 구현 결과를 제시하였다. 본고에서 제시한 디지털 홀로그래픽 콘텐츠 제작을 위한 기반 기술을 향후 실용화될 디지털 홀로그램의 광학적 복원 장치와 접목한다면 새로운 형태의 홀로그래픽 실감형 콘텐츠가 활성화될 수 있을 것으로 예상된다.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1301-1304
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• 1987

We have analized electrical error factors generated in the digitizing process of the linear scanning digital radiography system, and obtained improved results using error calibration hardwares. And characteristics of digital radiography system were evaluated by measuring several imaging properties.

• Journal of the Korean Society of Radiology
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• v.11 no.6
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• pp.493-500
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• 2017

In this study, data analysis has been conducted by INFINITT program to analyze the effect of signal to noise ratio(SNR) and contrast to noise ratio(CNR) of flow related enhancement(FRE) and computed tomography Angiography(CTA) on cerebrovascular diseases for qualitative evaluations. Based on the cerebrovascular image results achieved from 63 patients (January to April, 2017, at C University Hospital), we have selected 19 patients that performed both FRE-MRA and CTA. From the 19 patients, 2 were excluded due to artifacts from movements in the cerebrovascular image results. For the analysis conditions, we have set the 5 part (anterior cerebral artery, right and left Middle cerebral artery, right and left Posterior cerebral artery) as the interest area to evaluate the SNR and CNR, and the results were validated through Independence t Test. As a result, by averaging the SNR, and CNR values, the corresponding FRE-MRA achieved were: anterior cerebral artery ($1500.73{\pm}12.23/970.43{\pm}14.55$), right middle cerebral artery ($1470.16{\pm}11.46/919.44{\pm}13.29$), left middle cerebral artery ($1457.48{\pm}17.11/903.96{\pm}14.53$), right posterior cerebral artery ($1385.83{\pm}16.52/852.11{\pm}14.58$), left posterior cerebral artery ($1318.52{\pm}13.49/756.21{\pm}10.88$). by averaging the SNR, and CNR values, the corresponding CTA achieved were: anterior cerebral artery ($159.95{\pm}12.23/123.36{\pm}11.78$), right middle cerebral artery ($236.66{\pm}17.52/202.37{\pm}15.20$), left middle cerebral artery ($224.85{\pm}13.45/193.14{\pm}11.88$), right posterior cerebral artery ($183.65{\pm}13.47/151.44{\pm}11.48$), left posterior cerebral artery ($177.7{\pm}16.72/144.71{\pm}11.43$) (p < 0.05). In conclusion, MRA had high SNR and CNR value regardless of the cerebral infarction or cerebral hemorrhage observed in the 5 part of the brain. Although FRE-MRA consumed longer time, it proved to have less side effect of contrast media when compared to the CTA.

• The Journal of Korean Society for Radiation Therapy
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• v.19 no.2
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• pp.99-106
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• 2007

Purpose: The patient's position and anatomy during the treatment course little bit varies to some extend due to setup uncertainties and organ motions. These factors could affected to not only the dose coverage of the gross tumor but over dosage of normal tissue. Setup uncertainties and organ motions can be minimized by precise patient positioning and rigid immobilization device but some anatomical site such as prostate, the internal organ motion due to physiological processes are challenge. In planning procedure, the clinical target volume is a little bit enlarged to create a planning target volume that accounts for setup uncertainties and organ motion as well. These uncertainties lead to differences between the calculated dose by treatment planning system and the actually delivered dose. The purpose of this study was to evaluate the differences of interfractional displacement of organ and GTV based on the tomoimages. Materials and Methods: Over the course of 3 months, 3 patients, those who has applied rectal balloon, treated for prostatic cancer patient's tomoimage were studied. During the treatment sessions 26 tomoimages per patient, Total 76 tomoimages were collected. Tomoimage had been taken everyday after initial setup with lead marker attached on the patient's skin center to comparing with C-T simulation images. Tomoimage was taken after rectal balloon inflated with 60 cc of air for prostate gland immobilization for daily treatment just before treatment and it was used routinely in each case. The intrarectal balloon was inserted to a depth of 6 cm from the anal verge. MVCT image was taken with 5 mm slice thickness after the intrarectal balloon in place and inflated. For this study, lead balls are used to guide the registration between the MVCT and CT simulation images. There are three image fusion methods in the tomotherapy, bone technique, bone/tissue technique, and full image technique. We used all this 3 methods to analysis the setup errors. Initially, image fusions were based on the visual alignment of lead ball, CT anatomy and CT simulation contours and then the radiation therapist registered the MVCT images with the CT simulation images based on the bone based, rectal balloon based and GTV based respectively and registered image was compared with each others. The average and standard deviation of each X, Y, Z and rotation from the initial planning center was calculated for each patient. The image fusions were based on the visual alignment of lead ball, CT anatomy and CT simulation contours. Results: There was a significant difference in the mean variations of the rectal balloon among the methods. Statistical results based on the bone fusion shows that maximum x-direction shift was 8 mm and 4.2 mm to the y-direction. It was statistically significant (P=<0.0001) in balloon based fusion, maximum X and Y shift was 6 mm, 16mm respectively. One patient's result was more than 16 mm shift and that was derived from the rectal expansions due to the bowl gas and stool. GTV based fusion results ranging from 2.7 to 6.6 mm to the x-direction and 4.3$\sim$7.8 mm to the y-direction respectively. We have checked rotational error in this study but there are no significant differences among fusion methods and the result was 0.37$\pm$0.36 in bone based fusion and 0.34$\pm$0.38 in GTV based fusion.

• The Korean Journal of Nuclear Medicine Technology
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• v.19 no.2
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• pp.87-92
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• 2015

Purpose When the patients takes myocardial perfusion SPECT using $^{201}Tl$, the operator gives the patients an injection of $^{201}Tl$. But the uniformity correction map in SPECT uses $^{99m}Tc$ uniformity correction map. Thus, we want to compare the image quality when it uses $^{99m}Tc$ uniformity correction map and when it uses $^{201}Tl$ uniformity correction map. Materials and Methods Phantom study is performed. We take the data by Asan medical center daily QC condition with flood phantom including $^{201}Tl$ 21.3 kBq/mL. After postprocessing with this data, we analyze CFOV integral uniformity(I.U) and differential uniformity(D.U). And we take the data with Jaszczak ECT Phantom by American college of radiology accreditation program instruction including $^{201}Tl$ 33.4 kBq/mL. After post processing with this data, we analyze spatial Resolution, Integral Uniformity(I.U), coefficient of variation(C.V) and Contrast with Interactive data language program. Results In the flood phantom test, when it uses $^{99m}Tc$ uniformity correction map, Flood I.U is 3.6% and D.U is 3.0%. When it uses $^{201}Tl$ uniformity correction map, Flood I.U is 3.8% and D.U is 2.1%. The flood I.U is worsen about 5%, but the D.U is improved about 30% inversely. In the Jaszczak ECT phantom test, when it uses $^{99m}Tc$ uniformity correction map, SPECT I.U, C.V and contrast is 13.99%, 4.89% and 0.69. When it uses $^{201}Tl$ uniformity correction map, SPECT I.U, C.V and contrast is 11.37%, 4.79% and 0.78. All of data are improved about 18%, 2%, 13% The spatial resolution was no significant changes. Conclusion In the flood phantom test, Flood I.U is worsen but Flood D.U is improved. Therefore, it's uncertain that an image quality is improved with flood phantom test. On the other hand, SPECT I.U, C.V, Contrast are improved about 18%, 2%, 13% in the Jaszczak ECT phantom test. This study has limitations that we can't take all variables into account and study with two phantoms. We need think about things that it has a good effect when doctors decipher the nuclear medicine image and it's possible to improve the image quality using the uniformity correction map of other radionuclides other than $^{99m}Tc$, $^{201}Tl$ when we make other nuclear medicine examinations.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.1
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• pp.26-34
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• 2009

Purpose: The purpose of this study was to find out what clinicopathologic or immunohistochemical parameter that may affect FDG uptake of primary tumor in PET/CT scan of the gastric carcinoma patient. Materials and Methods: Eighty-nine patients with stomach cancer who underwent pre-operative FDG PET/CT scans were included. In cases with perceptible FDG uptake in primary tumor, the maximum standardized uptake value (SUVmax) was calculated. The clinicopathologic results such as depth of invasion (T stage), tumor size, lymph node metastasis, tumor differentiation and Lauren's classification and immunohistochemical markers such as Ki-67 index, expression of p53, EGFR, Cathepsin D, c-erb-B2 and COX-2 were reviewed. Results: Nineteen out of 89 gastric carcinomas showed imperceptible FDG uptake on PET/CT images. In cases with perceptible FDG uptake in primary tumor, SUVmax was significantly higher in T2, T3 and T4 tumors than T1 tumors ($5.8{\pm}3.1$ vs. $3.7{\pm}2.1$, p=0.002). SUVmax of large tumors (above or equal to 3 cm) was also significantly higher than SUVmax of small ones (less than 3 cm) ($5.7{\pm}3.2$ vs. $3.7{\pm}2.0$, p=0.002). The intestinal types of gastric carcinomas according to Lauren showed higher FDG uptake compared to the non-intestinal types ($5.4{\pm}2.8$ vs. $3.7{\pm}1.3$, p=0.003). SUVmax between p53 positive group and negative group was significantly different ($6.0{\pm}2.8$ vs. $4.4{\pm}3.0$, p=0.035). No significant difference was found in presence of LN metastasis, tumor differentiation, Ki-67 index, and expression of EGFR, Cathepsin D, c-erb-B2 and COX-2. Conclusion: T stage of gastric carcinoma influenced the detectability of gastric cancer on FDG PET PET/CT scan. When gastric carcinoma was perceptible on PET/CT scan, T stage, size of primary tumor, Lauren's classification and p53 expression were related to degree of FDG uptake in primary tumor.