• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.555-558
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• 1997

A new approach to silent MR imaging using a rotating DC gradient has been explored and experimentally studied. As is known, acoustic or sound noise has been one of the major problems in handling patients, mainly due to the fast gradient pulsings in interaction with the main magnetic field. The sound noise is also proportionally louder as the magnetic field strength becomes larger. In this article, we have described a new imaging technique using a mechanically rotating DC gradient coil as an approach toward silent MR imaging, i.e., a mechanically rotated DC gradient effectively replaces both the phase encoding as well as the readout gradient pulsings and data obtained in this manner provides a set of project ion data which later can be used or the projection reconstructionorwithsomeinterpolation techniques one can also perform conventional 2-D FFT (Fast Fourier Transform) image reconstruction. We found, with this new technique, that the sound noise intensity compared with the conventional imaging technique, such as spin echo sequence, is reduced down to -20.7 dB or about 117.5 times. The experimental pulse sequence and its principle are described and images obtained by the new silent MR imaging technique are reported.

• 한국가시화정보학회지
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• 제14권3호
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• pp.15-21
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• 2016

The circular and flat heat pipe were experimentally investigated by using neutron imaging technique. This experimental study was performed at the DINGO of OPAL research reactor, Australia. The diameter of the circular heat pipe is 10 mm and the dimension of flat is $10(width){\times}3(thickness)mm2$, respectively. We used the distilled water as a coolant. The coolant distributions and 2-phase flow patterns were measured under heating conditions. Experimental results show that neutron imaging technique is a good tool to visualize the 2-phase flow and phenomena in the heat pipe. The coolant distributions and 2-phase flow patterns depend on installation posture of the heat pipe and volume ratio of the coolant. Finally, it was discussed to calculate the void fraction by neutron imaging technique.

• ETRI Journal
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• 제28권4호
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• pp.521-524
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• 2006

In this letter, we propose a novel computational integral imaging reconstruction technique based on a lenslet array model. The proposed technique provides improvement of viewing images by extracting multiple pixels from elemental images according to ray tracing based on the lenslet array model. To show the feasibility of the proposed technique, we analyze it according to ray optics and present the experimental results.

• 대한수학회논문집
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• 제16권3호
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• pp.519-541
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• 2001

Magnetic Resonance Electrical Impedance Tomography(MREIT) is a new medical imaging technique for the cross-sectional conductivity distribution of a human body using both EIT(Electrical Impedance Tomography) and MRI(Magnetic Resonance Imaging) system. MREIT system was designed to enhance EIT imaging system which has inherent low sensitivity of boundary measurements to any changes of internal tissue conductivity values. MREIT utilizes a recent CDI (Current Density Imaging) technique of measuring the internal current density by means of MRI technique. In this paper, a mathematical modeling for MREIT and image reconstruction method called the alternating J-substitution algorithm are presented. Computer simulations show that the alternating J-substitution algorithm provides accurate high-resolution conductivity images.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권2호
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• pp.1235-1238
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• 2007

There are several researches on 2D gaze tracking techniques to the 2D screen for the Human-Computer Interaction. However, the researches for the gaze-based interaction to the stereo images or 3D contents are not reported. This paper presents a gaze-based 3D interaction technique on autostereoscopic display system.

• Journal of Yeungnam Medical Science
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• 제4권1호
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• pp.1-15
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• 1987

Magnetic Resonance (M.R.) is rapidly emerging technique that provides high quality images and potentially provides much more diagnostic information than do conventional imaging modalities. M.R.I. is conceptually quite different from currently used imaging methods. The complex nature of M.R.I. allows a great deal of flexibility in image product ion and available information, and key points are as follows. 1. M.R.I. offers a non-invasive technique with which to gene rate in vivo human images without ionizing radiation and with no known adverse biological effects. 2. Imaging mechanism of M.R.I. is quite different from conventional imaging modality and for more accurate diagnostic application, It is necessary for physician to understand imaging mechanism of M.R.I. 3. M.R. makes available basic chemical parameters that may provide to be useful for diagnostic medical imaging and more specific pathophysiologic information which are not available by alternate techniques. 4. M.R. can be produced by number of different methods. This flexibility allows the imaging technique to be applicated for particular clinical purpose. Multiplanar and three dimensional imaging may extend the imaging process beyond the single section available with current CT. 5. Future directions include efforts to; a. Further development of hard ware b. More fasternning scan time c. Respiratory and cardiac gated imaging d. Imaging of additional nuclei except hydrogen e. Further development of contrast media f. M.R. in vivo spectroscopy g. Real time M.R. imaging.

• Investigative Magnetic Resonance Imaging
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• 제21권1호
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• pp.20-27
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• 2017

Purpose: To evaluate quantification results of single breath-hold (SBH) magnetic resonance (MR) cine imaging compared to results of conventional multiple breath-hold (MBH) technique for left ventricular (LV) function in patients with cardiac arrhythmia. Materials and Methods: MR images of patients with arrhythmia who underwent MBH and SBH cine imaging at the same time on a 1.5T MR scanner were retrospectively reviewed. Both SBH and MBH cine imaging were performed with balanced steady state free precession. SBH scans were acquired using temporal parallel acquisition technique (TPAT). Fifty patients ($65.4{\pm}12.3years$, 72% men) were included. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF), myocardial mass, and LV regional wall motion were evaluated. Results: EF, myocardial mass, and regional wall motion were not significantly different between SBH and MBH acquisition techniques (all P-values > 0.05). EDV, ESV, and SV were significant difference between the two techniques. These parameters for SBH cine imaging with TPAT tended to lower than those in MBH. EF and myocardial mass of SBH cine imaging with TPAT showed good correlation with values of MBH cine imaging in Passing-Bablok regression charts and Bland-Altman plots. However, SBH imaging required significantly shorter acquisition time than MBH cine imaging ($15{\pm}7sec$ vs. $293{\pm}104sec$, P < 0.001). Conclusion: SBH cine imaging with TPAT permits shorter acquisition time with assessment results of global and regional LV function comparable to those with MBH cine imaging in patients with arrhythmia.

• 한국분무공학회지
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• 제3권1호
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• pp.1-9
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• 1998

Two measurement techniques of droplet sizing, an imaging technique(PMAS) and a phase-Doppler measurement technique (PDPA), have been compared using a water spray from a pressurized-type swirl nozzle. The result showed that SMD measured by PDPA was larger than that measured by PMAS by about 40 %. Such discrepancy of SMD could be explained by the fact that the light signal intensity used by PDPA can be biased towards larger particles. On the other hand there could be lower opportunity to capture the images of the large particles with PMAS, since the large particles could be out of sight due to their high speed.

• 대한의용생체공학회:의공학회지
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• 제20권2호
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• pp.165-172
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• 1999

본 연구에서는 MRI 영상에서 위상을 조절하여 영상 대조를 증가 시키는 방법을 제안 하였다 영상하고자 하는 물체 자체가 갖는 위상에 따라 영상의 대조가 변하기 때문에 본 방법은 자화율 영상이나 유속 영상에 유용하게 쓰일 수가 있다. 본 논문에서는 위상 분포에 따른 영상의 대조를 증가 시키기 위하여 RF 펄스를 복셀 내에서 위상을 갖도록 디자인 하였다. 따라서 복셀에서의 신호의 크기는 물체자체의 위상과 RF 펄스에의하여 가해준 위상이 결합에 의하여 결정된다. 외부위상 변화에 따른 신호의 변화를 분석하였고 그때 디자인된 RF 펄스를 이용하여 자화율만의 영상과 유속만의 영상을 얻었다. 컴퓨터 시뮬레이션의 결과는 제안된 알고리즘이 복셀내에 위상을 갖는 물체의 영상에 유용하고 그런 물체만을 영상하는데 유용함을 보였다.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1998년도 학술발표대회 논문집 제17권 1호
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• pp.239-242
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• 1998

A new real time sound field visualization technique is introduced in this study using PIV(Particle Imaging Velocimetry) technique. Small particles of which density is small enough to follow up the air flow are used for sound visualization. When the driving frequency is in the vicinity of the resonance frequency of the simplified 2-dimensional muffler system, an acoustic streaming is shown and of which velocity distribution is obtained through PIV technique. It is experimentally proved that the present technique is able to visualize and quantify the sound field's energy flow.