• 전자공학회논문지
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• 제50권12호
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• pp.247-253
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• 2013

본 연구의 목적은 Direct DR(Digital Radiography), Indirect DR, I.I(Image Intensifier) DR에서 X선 광자 검출 방식에 따른 선량측정 및 획득된 영상을 정량적이고 객관적인 측정을 통해 DR System을 비교 평가 하는 것이다. Rando phantom을 사용하여 입사표면선량을 측정하였으며, 측정된 입사표면선량 값을 통해 PCXMC 프로그램을 사용하여 유효선량과 방사선 조사로 인한 위험을 평가하였다. 21cm 아크릴 phantom을 사용하여 SNR(Signal to Noise Ratio), NPS(Noise Power Spectrum), CNR(Contrast to Noise Ratio)을 측정하였으며, 측정값은 통계학적 분석기법을 사용하여 유의성을 평가하였다. 입사표면선량, 주요장기선량, 유효선량 모두 direct DR이 가장 낮게 측정되었으며, direct DR 선량을 기준으로 I.I type DR은 약 1.3배, indirect DR은 약 2.4배 높은 선량 비율로 측정되었다. 방사선량에 따른 위험도 역시 동일한 비율로 측정되었다. SNR 측정 결과 direct DR측정값을 기준으로 I.I DR은 약 7.25배, indirect DR이 약 1.48배 낮은 비율로 측정되었다. CNR 측정 결과 direct DR 측정값을 기준으로 I.I DR은 약 1.16배 높고, indirect DR이 약 0.87배 낮은 비율로 측정되었다. 따라서 a-selenium 검출소자를 사용하여 X선 광자를 검출하는 방식인 direct DR은 적은 선량으로 우수한 화질의 영상을 구현함으로써 선량에 민감한 소아나 생식선이 포함된 검사 등에 유용할 것으로 사료된다. 또한 많은 진단 정보를 위한 영상 평가가 요구되는 경우에는 indirect DR이 유용할 것으로 판단된다.

• Journal of Smart Tourism
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• 제3권1호
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• pp.1-8
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• 2023

• 대한두경부종양학회지
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• 제13권1호
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• pp.16-23
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• 1997

Although normal thyroid epithelial cells do not constitutively express HLA-DR antigen, their expression in wide spread within thyroid glands obtained from the human with autoimmune thyroid disease and with many neoplastic thyroids. We have, therefore, studied immunohistochemically with regard to the expression of HLA-DR antigen of thyroidectomy specimens from 50 patients of various thyroid diseases with use of paraffin-embedded tissue. One or two sections from each case were stained with commercially available mouse monoclonal antibody for class II HLA-DR antigen(HLA-DR/Alpha, DAKO) and examined by semiquantitative counting system for thyrocytes, neoplastic thyrocytes and other cells expressing HLA-DR antigen. All patients with lymphocytic thyroiditis(2/2) and diffuse hyperplasia(Graves' disease)(5/5), most patients with Hashimoto's disease(9/ll) expressed HLA-DR antigens in thyrocyte with abundant HLA-DR expressing lymphocytic infiltrates with lymph follicle formation in its vicinity or adjacent to the lesion. Most patients with papillary carcinoma(9/1l) had HLA-DR antigen detected in malignant thyrocytes ; while follicular carcinoma(0/3) and follicular adenoma(0/5) did not have detactable HLA-DR immunoreactivity. Adenomatous goiter(3/7) had HLA-DR antigen detected focally in lesser than half cases. Conversely, in four papillary carcinomas and three adenomatous goiters, HLA-DR expression of thyrocytes was found in the absence of HLA-DR expressing lymphoid infiltrates. In such cases therefore other factors more than thyroid autoimmunity must be causative for HLA-DR immunoreactivity. The results of this study indicate as follows. 1) The expression of HLA-DR on thyrocytes involved in autoimmune reactions appeared to be secondary to cytokine release from associated lymphocytic infiltrates. 2) Thyrocytes in thyroid lesions with equal degrees of lymphocytic infiltration without HLA­DR expression exhibited no HLA-DR immunoreactivity. 3) In neoplastic thyrocytes, most papillary carcinoma(9/11) exhibited detactable HLA-DR expression, while follicular carcinoma/adenoma(0/3/0/5) exhibited no detactable HLA-DR immunoreactivity which suggest the existence of divergent mechanisms inducing and modulating HLA-DR expression of different types of neoplastic thyrocytes.

• 한국항행학회논문지
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• 제9권2호
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• pp.147-155
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• 2005

본 논문에서는 기존 코플래나 웨이브가이드(CPW), 유한접지(FG) CPW, 그리고 접지(G) CPW와 같은 세 종류의 균일단면 구조의 CPW와 $TE_{01{\delta}}$ 모드 유전체공진기(DR : Dielectric Resonator)간의 결합 특성을 연구하고 마이크로스트립과 DR과의 결합과 같은 병렬 공진 특성을 보이는 CPW 와 DR간의 결합회로의 설계 방법을 제안한다. 결합 특성은 DR을 CPW의 접지와 신호선사이의 두 간격 중의 하나의 중심 상에 유전체 지지대(Support)를 이용하여 위치시키고 접지 방향으로 이동하면서 연구되었다. HFSS(High Frequency Structure Simulator : Finite Element Method Commercial Tool)의 시뮬레이션과 측정된 S-파라미터 값은 잘 일치했다. 마지막으로, 위에서 언급한 세 종류의 CPW와 DR과의 결합과 마이크로스트립라인과 DR과의 결합을 무부하 품질계수인 $Q_u$를 이용하여 비교하였다. 비교결과 CPW와 DR과의 결합은 마이크로스트립라인과 DR과의 결합보다 높은 $Q_u$ 값을 나타냈고 그 중에서 GCPW와 DR과의 결합이 가장 높은 $Q_u$를 보여줬다.

• Clinical and Experimental Pediatrics
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• 제64권7호
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• pp.370-372
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• 2021

• 대한전기학회논문지:전력기술부문A
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• 제48권10호
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• pp.1279-1286
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• 1999

In conventional GPS/DR integration schemes, the GPS position (or pseudo-range) information is used in calibrating DR sensors. In those schemes, however, an inaccurate calibration may degrade the position accuracy when the GPS measurement is not available. This paper presents a new integration scheme where the GPS velocity information is used in calibrating DR sensors. Also proposed is a new error model of DR sensors for calibrating the bias error and the tilt error in dynamic environments. The proposed model makes it possible that the errors of both the DR sensor parameters and the velocity are calibrated using the GPS carrier-based velocity(or the pseudo-range rate) measurement while the DR position error is calibrated using the GPS position measurement. Since the DR sensors are calibrated accurately, the positioning accuracy is drastically improved when the GPS measurements are unavailable.

• Communications for Statistical Applications and Methods
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• 제28권5호
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• pp.553-562
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• 2021

Directional regression (DR; Li and Wang, 2007) is well-known as an exhaustive sufficient dimension reduction method, and performs well in complex regression models to have linear and nonlinear trends. However, the extension of DR is not well-done upto date, so we will extend DR to accommodate multivariate regression and large p-small n regression. We propose three versions of DR for multivariate regression and discuss how DR is applicable for the latter regression case. Numerical studies confirm that DR is robust to the number of clusters and the choice of hierarchical-clustering or pooled DR.

• ETRI Journal
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• 제28권2호
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• pp.131-144
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• 2006

This work demonstrates a dead-reckoning (DR) scheme for a low-cost land navigation system and a DR/GPS system design using the sigma point Kalman filter (SPKF). T hrough an observability analysis and some simulations, it is shown that the performances of a stand-alone DR system and DR/GPS system can be improved by employing the proposed DR scheme and SPKF. By using the designed DR scheme and filter, the stand-alone DR system does not have any undetectable errors occurring on the curve trajectory. And the DR/GPS system can provide a stable and seamless navigational solution even in the case where the initial heading estimation error is large, such as 160 degrees, or when the GPS signal is unavailable due to tunnels, buildings, and so on. Simulation results indicate a satisfactory performance of the proposed system.

• 한국항행학회논문지
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• 제2권2호
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• pp.75-83
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• 1998

본 논문에서는 저가이면서 높은 정확도를 갖는 GPS와 DR의 통합시스템 및 이 시스템의 위치 결정에 수반되는 오차문제를 고려한다. 이 통합 GPS/DR 시스템은 실시간 또는 비 실시간으로 고정밀도의 위치 정보를 제공하는 성능을 갖는다. DR 측정치에 영향을 주는 주요 오차 요인을 분석하여 이를 8개의 상태 변수의 모델로 표현하였다. 이들 변수의 상태 방정식을 사용하여 DR신호가 제공되는 매 순간에서 상태 변수값을 추산하기 위한 통합시스템용 비선형 필터를 개발한다, 1Hz의 DR 측정치와 3Hz로 제공되는 GPS 위치 정보를 위치 추산치에 대해 이 통합시스템의 정확도를 평가한다. 시뮬레이션을 통해 GPS신호가 정전되는 기간동안 통합 시스템의 성능을 두 가지 서로 다른 잡음모델에 대해 비교 검토한다. 두 잡음모델 중 하나는 단일잡용을 사용하는 반면에 또 다른 모델은 이중 잡음 모델을 채용한다. 시뮬레이션 결과로부터 이중 잡음 모델을 채용하는 GPS/DR 통합시스템은 단일 잡음 모델을 이용하는 경우에 비하여 측위성능이 우수함을 확인하였다.

• Journal of Periodontal and Implant Science
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• 제53권1호
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• pp.54-68
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• 2023

Purpose: The purpose of this study was to determine whether metformin (MF) could alleviate the expresssion of reactive oxygen species (ROS) and improve the osteogenic ability of bone marrow mesenchymal stem cells derived from diabetic rats (drBMSCs) in vitro, and to evaluate the effect of MF on the ectopic osteogenesis of drBMSCs in a nude mouse model in vivo. Methods: BMSCs were extracted from normal and diabetic rats. In vitro, a cell viability assay (Cell Counting Kit-8), tests of alkaline phosphatase (ALP) activity, and western blot analysis were first used to determine the cell proliferation and osteogenic differentiation of drBMSCs that were subjected to treatment with different concentrations of MF (0, 50, 100, 200, 500 µM). The cells were then divided into 5 groups: (1) normal rat BMSCs (the BMSCs derived from normal rats group), (2) the drBMSCs group, (3) the drBMSCs + Mito-TEMPO (10 µM, ROS scavenger) group, (4) the drBMSCs + MF (200 µM) group, and (5) the drBMSCs + MF (200 µM) + H₂O₂ (50 µM, ROS activator) group. Intracellular ROS detection, a senescence-associated β-galactosidase assay, ALP staining, alizarin red staining, western blotting, and immunofluorescence assays were performed to determine the effects of MF on oxidative stress and osteogenic differentiation in drBMSCs. In vivo, the effect of MF on the ectopic osteogenesis of drBMSCs was evaluated in a nude mouse model. Results: MF effectively reduced ROS levels in drBMSCs. The cell proliferation, ALP activity, mineral deposition, and osteogenic-related protein expression of drBMSCs were demonstrably higher in the MF-treated group than in the non-MF-treated group. H₂O₂ inhibited the effects of MF. In addition, ectopic osteogenesis was significantly increased in drBMSCs treated with MF. Conclusions: MF promoted the proliferation and osteogenic differentiation of drBMSCs by inhibiting the oxidative stress induced by diabetes and enhenced the ectopic bone formation of drBMSCs in nude mice.