Down-Scaled 3D Medical Image Transfer System Using Instant Messenger

Objective: We have developed an instant messenger system that supports transmitting 3D medical image objects for telediagnostic use. Methods: We used thresholding and down-scaling technique to build down-scaled 3D object with 80 sliced Digital Imaging and Communication in Medicine(DICOM) images. And, we also construct instant messenger for medical data transfer and general communication. We measured total image size and transmission time which were decreased when applied peer to peer connection using instant messenger for medicine. Results: Our study showed that total DICOM image size was decreased around 1% and transmission time was also decreased by 1.59% when we use proposed system. Conclusion: Proposed methods have a potential to be a useful tool in ubiquitous health network system. Also, we expect the synergy effect is increased by developing 3D object technique and security solutions.ope

실리콘 기반 소자를 이용한 적외선 검출

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 박영준.Lights in nature can be classified into various bands depending on the wavelength. Among the many types of light, near infrared (NIR) light has a wavelength of 780?2500 nm. The NIR wavelength band is widely used in various types of sensor devices, as well as in communication. Therefore, there is substantial demand for efficient and cost-effective NIR detectors. However, although materials such as InGaAs, Ge, and PbS are applied in detectors to detect NIR wavelengths, these materials are not compatible with the widely used and cost-effective Si-based integration process. Thus, this dissertation focuses on detection of NIR light using a Si based device. However, the crucial obstacle in using Si as an NIR detection material is that it has band gap energy of 1.12 eV, and therefore, it does not absorb wavelengths longer than 1150nm. One possible solution is utilizing the Franz?Keldysh effect (FKE) in the Si devices. The FKE dictates that a semiconductor can absorb a photon with lower energy than the band-gap energy by tunneling the valence electrons to the conduction band in the presence of a strong electric field. This phenomenon can be used to detect infrared (IR) photons if the junction is biased in the FKE bias region. In this dissertation, to investigate the detection of NIR with a Si-based device, we attempt to use the Zener diode and the NMOSFET, which can generate tunneling currents in the presence of a strong electric field. When a strong reverse bias is applied to the Zener junction, a tunneling current is generatedthe NMOSFET also has a tunneling current when the bias condition generates a gate-induced drain leakage (GIDL) current. In such a bias condition for both devices, NIR with wavelengths of 1310nm and 1550nm, which have lower energy than the band-gap energy of Si, are irradiated to the Zener diode and the NMOSFET. In the case of the Zener diode, an avalanche multiplication is investigated to cause more absorption by applying an additional, stronger electric field than the normal reverse bias condition, which causes a tunneling current to flow. However, because the negative temperature coefficient is due to the Joule heat generation of the junction in the bias regime of the avalanche multiplication, the methodology of a pulsed bias scheme is applied to mitigate the unintentional increase in the junction temperature and the associated degradation of the photo-responsivity under a DC bias. Accordingly, the NMOSFET in the condition in which GIDL flows can also absorb wavelengths of 1310nm and 1550nm by FKE. Additionally, the photo-generated current can be amplified by avalanche multiplication under a strong electric field with the pulsed bias scheme between the drain and the substrate. Thus, this dissertation concludes that Si-based junctions can be used to detect IR signals using the FKE generation followed by multiplication through the newly proposed methodology of pulse measurement, which minimizes both the thermal effect and the degradation of photo-responsivity.1 Introduction (1) 1.1 Motivation (1) 1.2 Optical characteristics of Silicon for IR detectors (3) 1.3 Common view of the Franz-Keldysh effect (5) 1.4 Si devices for an IR photo detector (5) 1.5 Infrareds laser sources (6) 1.6 Outline of the Dissertation (8) 2 Fundamentals of optical transition in Silicon (10) 2.1 The Franz-Keldysh effect (10) 2.2 Tunneling current based on the Franz-Keldysh effect (14) 2.2.1 Tunneling probability (14) 2.2.2 Tunneling Current of the Zener diode (15) 2.2.3 Gate Induced Drain Leakage Current of NMOS (15) 2.3 Phonon-assisted tunneling in the indirect band gap of semiconductor (17) 2.4 Photo Responsivity (18) 3 IR detection with the Zener diode (19) 3.1 Zener diode as a photodetector (19) 3.1.1 Reverse current characteristics of the Zener junction (18) 3.1.2 Feature of the experimental Zener diode (23) 3.1.3 Temperature coefficient of the reverse current (24) 3.2 DC Measurement (25) 3.2.1 Degradation in photo sensitivity (25) 3.2.2 Temperature dependency of the photo sensitivity (28) 3.3 The pulsed bias scheme (31) 3.3.1 Circuit diagram for the pulsed bias scheme (31) 3.3.2 Response of the input pulsed wave (33) 3.4 IR Photo response in the pulsed bias scheme (35) 3.4.1 Bias dependency of photo generated current (35) 3.4.2 Photo responsivity for the infrared signal (38) 3.5 Effect of defects in the junction on the FKE (40) 3.5.1 Correlation of the FKE current with the trap density (40) 4 GIDL regime in the NMOSFET for IR detection (42) 4.1 MOSFET as the photodetector of the infrared light (42) 4.1.1 Energy band of the surface junction in the GIDL bias (42) 4.1.2 Structure of the NMOSFET test pattern (45) 4.2 DC Measurement results (50) 4.2.1 Limitation of the photo sensitivity in the DC bias scheme (50) 4.3 Pulsed bias scheme to induce the NMOS GIDL (58) 4.3.1 Circuit diagram for the pulsed bias scheme (58) 4.3.2 Current response to the Pulsed wave (60) 4.4 IR photo response under the pulsed bias scheme (62) 5 Multiplication of IR signal with NMOSFET (65) 5.1 Multiplication of the FKE current (65) 5.1.1 Schematics of the multiplication of FKE current (65) 5.2 Results of the DC Measurement (68) 5.2.1 Multiplication by the substrate bias (68) 5.2.2 Temperature dependency (72) 5.2.3 Degradation in the photo sensitivity (74) 5.3 Pulsed bias scheme (79) 5.3.1 Circuit diagram for pulsed bias scheme (79) 5.3.2 Response to the input pulsed wave (81) 5.4 Enhanced response by the multiplication (84) 5.5 Simulated results for the NMOS (87) 6 Conclusions (92) 6.1 Summary (92) 6.2 Further works (94)Docto

A Study on the Performance Improvement of OpenGL based 3D Graphics Applications on Engineering Workstations

In 1992, OpenGL from SGI became the most important 3D-API for engineering graphics applications including 3D CAD. The accelerating performance for OpenGL-based 3D graphics application is the first issue of current engineering workstation market. The performance of 3D CAD application is adopted in the area of the hardware devices like microprocessor, main memories, and sub memories. And software includes device drives and operating system. Although the higher performance of 3D CAD application is acquired by the optimized balance of these parts, workstation has many difficulties by generic constructing of computer system. In this paper, the improvement of the performance of OpenGL based 3D graphics for the developers and users of 3D CAD applications on engineering workstations is studied. The analysis of the performance in the configuration of microprocessor, amount of memories, OpenGL acceleration of graphic subsystem and operating environments are investigated. The effects on improving OpenGL 3D-API and 3D CAD applications by the configuration of microprocessors, memories, graphics subsystems and operating environments are also examined. The single configuration of microprocessor is better than multiple configuration. The amounts of memories are major impact element of workstation and applications. And the accelerating performance of OpenGL in graphics subsystem is not proportioned to that of 3D CAD applications. Controlling by configuring of environmental factors of graphics subsystem, operating systems, and device drivers make the higher improvements of performance. Therefore, users and developers of graphics engineering workstations should apply it for the optimized systems for 3D CAD applications.１. 서론 = 1 １.１. 연구 배경 = 1 １.２. 연구 목적 = 2 １.３. 연구 방법 = 3 ２. 마이크로프로세서 구성에 따른 3D 그래픽스 성능 변화 = 10 ２.１. OpenGL 3D-API 성능 분석 = 11 ２.２. OpenGL 기반 3D CAD 어플리케이션 성능 분석 = 18 ２.３. 마이크로프로세서 성능에 따른 3D 그래픽스 성능 변화 = 25 ３. 기억장치 용량 변화에 따른 3D 그래픽스 성능 변화 = 28 ３.１. 마이크로프로세서와 주기억장치 구성에 따른 성능 변화 = 28 ３.２. 보조기억장치 운용에 따른 3D 그래픽스 성능 변화 = 38 ３.２.１. I/O 서브시스템 변화에 따른 성능 개선 = 38 ３.２.２. 가상 기억장치 변화에 따른 3D 그래픽스 성능 변화 = 39 ４. 그래픽스 서브시스템에 따른 OpenGL 가속 성능 변화 = 41 ４.１. OpenGL 그래픽스 서브시스템에 따른 3D 그래픽스 성능 = 45 ４.２. OpenGL 3D 성능 요소 분석 = 53 ４.３. 그래픽스 서브시스템 설정에 따른 3D-API 가속 성능 분석 = 55 ４.４. 그래픽스 서브시스템의 3D CAD 어플리케이션 성능 분석 = 67 ４.５. 드라이버 개정에 의한 OpenGL 가속 성능 변화 = 77 ５. 운영 환경에 따른 3D 그래픽스 성능 분석 = 82 ５.１. 운영 체제에 따른 3D 그래픽스 성능 변화 = 82 ５.２. OpenGL 프로그래밍 단계의 성능 저하 요소 분석 = 90 ６. 고찰 = 93 ６.１. 마이크로프로세서와 기억장치 구성 = 93 ６.２. 그래픽스 서브시스템 구성 = 98 ６.３. 운영 환경 개선에 의한 성능 변화 = 99 ７. 결론 = 10

Comparison of Unmonochromatized Synchrotron Radiation and Conventional X-rays in the Imaging of Mammographic Phantom and Human Breast Specimens: A Preliminary Result

A simple imaging setup based on the principle of coherence-based contrast X-ray imaging with unmonochromatized synchrotron radiation was used for studying mammographic phantom and human breast specimens. The use of unmonochromatized synchrotron radiation simplifies the instrumentation, decreases the cost and makes the procedure simpler and potentially more suitable for clinical applications. The imaging systems consisted of changeable silicon wafer attenuators, a tungsten slit system, a CdWO4 scintillator screen, a CCD (Charge Coupled Device) camera coupled to optical magnification lenses, and a personal computer. In preliminary studies, a spatial resolution test pattern and glass capillary filled with air bubbles were imaged to evaluate the resOolution characteristics and coherence-based contrast enhancement. Both the spatial resolution and image quality of the proposed system were compared with those of a conventional mammography system in order to establish the characteristic advantages of this approach. The images obtained with the proposed system showed a resolution of at least 25 µm on the test pattern with much better contrast, while the images of the capillary filled with air bubbles revealed coherence-based edge enhancement. This result shows that the coherence-based contrast imaging system, which emphasizes the refraction effect from the edge of materials of different refractive indexes, is applicable to imaging studies in fundamental medicine and biology, although further research works will be required before it can be used for clinical applications.ope

Assessment of Attenuation Correction Techniques with a 137Cs Point Source

Purpose: The objective of this study was to assess attenuation correction algorithms with the 137Cs point source for the brain positron emission tomography (PET) imaging process. Materials & Methods: Four different types of phantoms were used in this study for testing various types of the attenuation correction techniques. Transmission data of a 137Cs point source were acquired after infusing the emission source into phantoms and then the emission data were subsequently acquired in 3D acquisition mode. Scatter corrections were performed with a background tail-fitting algorithm. Emission data were then reconstructed using iterative reconstruction method with a measured (MAC), elliptical (ELAC), segmented (SAC) and remapping (RAC) attenuation correction, respectively. Reconstructed images were then both qualitatively and quantitatively assessed. In addition, reconstructed images of a normal subject were assessed by nuclear medicine physicians. Subtracted images were also compared. Results: ELAC, SAC, and RAC provided a uniform phantom image with less noise for a cylindrical phantom. In contrast, a decrease in intensity at the central portion of the attenuation map was noticed at the result of the MAC. Reconstructed images of Jaszack and Hoffan phantoms presented better quality with RAC and SAC. The attenuation of a skull on images of the normal subject was clearly noticed and the attenuation correction without considering the attenuation of the skull resulted in artificial defects on images of the brain. Conclusion: the complicated and improved attenuation correction methods were needed to obtain the better accuracy of the quantitative brain PET images.ope

Three-dimensional image analysis of the skull using variable CT scanning protocols-effect of slice thickness on measurement in the three-dimensional CT images

Purpose : To evaluate the quantitative accuracy of three-dimensional (3D) images by means of comparing distance measurements on the 3D images with direct measurements of dry human skull according to slice thickness and scanning modes. Materials and Mathods : An observer directly measured the distance of 21 line items between 12 orthodontic landmarks on the skull surface using a digital vernier caliper and each was repeated five times. The dry human skull was scanned with a Helical CT with various slice thickness (3, 5, 7 mm) and acquisition modes (Conventional and Helical). The same observer measured corresponding distance of the same items on reconstructed 3D images with the internal program of V-works 4.0/supTM(Cybermed Inc., Seoul, Korea). The quantitative accuracy of distance measurements were statistically evaluated with Wilcoxons' two-sample test. Results: 11 line items in Conventional 3 mm, 8 in Helical 3mm, 11 in Conventional 5mm, 10 in Helical 5mm, 5 in Conventional 7mm and 9 in Helical 7mm showed no statistically significant difference. Average difference between direct measurements and measurements on 3D CT images was within 2mm in 19 line items of Conventional 3mm, 20 of Helical 3mm, 15 of Conventional 5mm, 18 of Helical 5mm, II of Conventional 7mm and 16 of Helical 7mm. Conclusion: Considering image quality and patient's exposure time, scanning protocol of Helical 5mm is recommended for 3D image analysis of the skull in CT.ope

직접 변환 수신기를 위한 RF 회로 설계에 관한 연구

Docto

Transflective LCD using hybrid substrate made by soft lithography

학위논문(석사) --서울대학교 대학원 :전기. 컴퓨터공학부, 2009.2.Maste

A Study of cavity varnish application on the marginal leakage of the various dental restorations

치의학과/석사[영문] [한글] 모든 치과용 충전물은 변연누출이 일어난다. 이 변연누출을 막기 위하여 치과용 varnis h를 아말감 충전에서 특히 많이 사용하고 있다. 이에 저자는 copal resin varnish인 Copa lite**(R) (Cooley and Cooley, Ltd., Houston, Texas, U.S.A.)와 불소가 함유된 Durapha t**(R) (Woelm Pharma., Eschwege, West Germany)의 변연폐쇄 효과를 구명하고자 발거된 상하악 소구치 120개 협면과 설면에 240개의 5급 와동을 형성하고 varnish를 1회, 2회 또 는 3회씩 도포하고 Amalgam(Cavex, Holland BV Keur and Sneltjes), Heliosit**(R) (Viva dent, Schaan, Liechitenstein) 그리고 Hipol**(R) (부평치과화학공업사, 인천, 한국)로 충전하였다. 그후 24시간 생리적 식염수에 보관 50회의 온도변화를, 72시간 생리적 식염 수에 보관 100회의 온도변화를 각각 120개의 와동에 실시하고 2% methylene blue에 24시 간 침윤시켰다. 시편을 교정용 레진에 포매한 후 절단하고 색소의 침투 정도를 금속현미 경(PME/MG, Olympus Optical Co., LTD., Japan)으로 관찰하여 다음과 같은 결론을 얻었다 . 1. 아말감 충전시 Copalite**(R) 3회 또는 Duraphat**(R) 1회 도포의 경우가 varnish를 도포하지 않은 군보다 변연페쇄가 우수하였다. 2. Heliosit**(R) 또는 Hipol**(R) 충전시 varnish를 도포한 경우가 도포하지 않은 경 우보다 변연누출이 많았다. 3. 모든 충전군에서 Copalite**(R) 와 Duraphat**(R) 사이에는 통계적으로 유의할 만한 차이가 없었다.(P>0.05) 4. 50회와 100회의 온도변화 처리 사이에 아말감의 변연누출은 통계적으로 유의할 만한 차이가 있었으나 (P<0.05), Heliosit**(R) 또는 Hipol**(R) 은 유의차를 나타내지 않았 다. (P>0.05) 5. Heliosit**(R) 와 Hipol**(R) 사이의 변연누출은 통계적으로 유의할 만한 차이가 없 었다. A STUDY OF CAVITY VARNISH APPLICATION OF THE MARGINAL LEAKAGE OF THE VARIOUS DENTAL RESTORATIONS Hee Joong Kim, D.D.S. Department of Dental Science, Graduate School, Yonsei Universtiy (Directe by Prof. Chung Suck Lee, D.D.S., Ph.D.) This study was undertaken to evaluate the effects of varnish application and thermocycling on the marginal leakage. 240 cavities of Class V were prepared on the 120 extracted premolars, and the cavities were filled with amalgam, Heliosit**(R) , and Hipol**(R) after application of Copalite**(R) or Duraphat**(R). All specimens were immersed in methylene blue solution for 24 hours after thermoparts. The sectioned specimens observed with the metallurgical microscope. The following results were obtained: 1. The marginal seal was more effective in the amalgam-filled cavitics after application of Copalite**(R) threethimes or an application of Duraphat**(R) varnish than in chose without varnish applicaions. 2. Of the composite resin-filled cavities, the leakage of the varnish applied cases showed much more than without aplication. 3. There was no significant difference in the effect of margical sealing between Copalite**(R) and Duraphar**(R) applications. 4. There was a significant difference in the degree of the marginal leakage of amalgam-filled cavities between the groups of thermocycling times, but no significant difference in resin-filled cavities. 5. There was no significant difference in the degree of the marginal leakage between the Heliosit**(R) and the Hipol**(R) resin-filled cavities.restrictio

NPC 인버터에서의 PWM 기법에 관한 연구

학위논문(석사)--서울대학교 대학원 :전기공학부,2000.Maste