• International Journal of Automotive Technology
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• 제7권1호
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• pp.83-90
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• 2006

The purpose of this paper is to describe the design and implementation of an unmanned ground vehicle, called the TailGator at CIMAR (Center for Intelligent Machines and Robotics) of the University of Florida. The TailGator is a gas powered, four-wheeled vehicle that was designed for the AUVSI Intelligent Ground Vehicle Competition and has been tested in the contest for 2 years. The vehicle control model and design of the sensory systems are described. The competition is comprised of two events called the Autonomous Challenge and the Navigation Challenge: For the autonomous challenge, line following, obstacle avoidance, and detection are required. Line following is accomplished with a camera system. Obstacle avoidance and detection are accomplished with a laser scanner. For the navigation challenge, waypoint following and obstacle detection are required. The waypoint navigation is implemented with a global positioning system. The TailGator has provided an educational test bed for not only the contest requirements but also other studies in developing artificial intelligence algorithms such as adaptive control, creative control, automatic calibration, and internet-base control. The significance of this effort is in helping engineering and technology students understand the transition from theory to practice.

• 대한의용생체공학회:의공학회지
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• 제30권4호
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• pp.333-340
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• 2009

MR compatible coaxial-slot antenna for microwave hyperthermia was developed while its structure and size of each part were determined by computer simulation using finite element method(FEM). Its local heating performance was evaluated using tissue-mimic phantom and swine muscles. 2% agarose gel mixed with 6mM/$\ell$ $MnCl_2$ as a biological tissue-mimic phantom was heated by the proposed antenna driven by a 2.45GHz microwave generator. The temperature changes of the phantom were monitored using multi-channel digital thermometer at the distance of 0mm, 5mm, 10mm and 20mm from the tip center of the antenna. Also muscle tissue of swine was heated for 2 and 5minutes with 50W and 30W of microwave generator powers, respectively, to evaluate the local heating performance of the antenna. MRI compatibility was also verified by acquiring MR images and MR temperature map. MR signals were acquired from the agarose gel phantom using $T2^*$ GRE sequence with 1.5T clinical MRI scanner(Signa Echospeed, GE, Milwaukee, WI, U.S.A.) at Pusan Paik Hospital and were transferred to PC in order to reconstruct MR images and temperature map using proton resonance frequency(PRF) method and laboratory-developed phase unwrapping algorithm. Authors found that it has no severe distortion due to the antenna inserted into the phantom. Finally, we can conclude that the suggested coaxial-slot antenna has an excellent local heating performance for both of tissue-mimic phantom and swine muscle, and it is compatible to 1.5T MRI scanner.

• 한국생산제조학회지
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• 제20권1호
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• pp.47-52
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• 2011

It is well known that stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates because the layup of composite laminates influences their properties. Ultrasonic NDE of composite laminates is often based on the backwall echoes of the sample. A pair of such transducers was mounted in a holder in a nose-to-nose fashion to be used as a scanning probe on composites. Miniature potted angle beam transducers were used (Rayleigh waves in steel) on solid laminates of composites. Experiments were performed to understand the behavior of the transducers and the nature of the waves generated in the composite (mode, wave speed, angle of refraction). C-scan images of flaws and impact damage were then produced by combining the pitch-catch probe with a portable manual scanner known as the Generic Scanner ("GenScan"). The pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave to fiber orientation of the CFRP composites, including low level porosity, ply waviness, and cracks. Therefore, it is found that the experimentally Rayleigh wave variation of pitch-catch ultrasonic signal was consistent with numerical results and one-side ultrasonic measurement might be very useful to detect the defects.

• 한국통신학회논문지
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• 제28권8C호
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• pp.803-810
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• 2003

본 논문은 여성 자궁경부암의 원인이 되는 인두유종 바이러스(papillomavirus)를 진단하기 위한 HPY-DNA 칩의 영상으로부터 탐촉자(probe)의 위치를 찾아내고 각 탐촉자에서의 교잡반응(hybridization) 여부를 결정하기 위한영상리 방법의 구현에 관한 것이다. HPV-DNA 칩은 22종의 HPV를 알아내기 위한 탐촉자들과 환자 샘플과 항상 반응하는 마커들로 구성되어 있다. 침 영상에서 탐촉자 들의 위치는 마커와 상대적으로 고정되어 있어서 도터(dotter)와 스캐너(scanner)의 정밀도에 따른 오차만을 갖는다. 한편 각 탐촉자는 진단신뢰도를 높이기 위하여 4번 씩 인쇄된다. 본 논문은 마커들간의 상대거리와 탐촉자의 중복 인쇄라는 사전정보를 템플릿 정합방법과 결합하여 안정적으로 마커를 찾고, 교잡반응 여부를 정확히 분류하는 방법을 제시한다. 정규화된 상관도를 정합도(matching measure)로 채택하여, 마커들의 상대적 위치에 대하여 평균을 취하면 안정적으로 마커를 찾을 수 있다는 것을 실험을 통하여 보인다. 또한 이미 계산된 정합도를 특징(feature) 값으로 사용하여 4개의 중복 탐촉자에 대한 평균 특징 값을 분류(classification)하면 탐촉자의 교잡반응 여부를 정확히 알아낼 수 있다는 실험 결과를 보인다.

• 디지털콘텐츠학회 논문지
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• 제11권4호
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• pp.425-431
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• 2010

본 연구에서는 돌발성 난청을 보이는 환자를 대상으로 임상에서 자주 사용 하는 기법인 3D FSE과 새로운 기법인 3D FIESTA-C 을 정량적으로 비교 분석하여 3D FIESTA 기법의 효과와 유용성을 고찰해보고자 한다. 감각신경성 난청으로 진단받은 40명의 환자를 대상으로 3.0T MR scanner를 이용하여 3D FSE 영상과 3D FIESTA 영상인 축상면 T2 영상을 획득하였다. 획득한 3D FSE 영상과 3D FIESTA 영상은 신경의 주행방향에 수직으로 재구성을 시행하여 내이도의 오른쪽, 왼쪽의 시상면 영상을 획득 하였다. 분석 결과 3D FSE 기법을 이용한 그룹과 3D FIESTA기법을 이용한 두 그룹에서의 신호대 잡음비는 3D FIESTA 기법을 이용한 그룹에서 높은 신호대 잡음비를 보였으며 두 그룹에서의 대조도대 잡음비는 3D FIESTA 기법을 이용한 그룹에서 높은 대조도대 잡음비를 보였다.

• 한국음향학회지
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• 제27권2호
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• pp.57-65
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• 2008

초음파 진단기의 설정은 영상의 질에 영향을 준다. sonographer는 최적의 영상을 얻기 위해 초음파 영상의 질에 영향을 주는 설정 변수에 대한 효과를 이해해야 한다. 본 연구에서는 4가지 대표적인 영상 조절 변수 즉 TGC (Time Gain Control), 이득 (Gain), 주파수 (Frequency), DR (Dynamic Range)를 고려하였다. 초음파 영상의 질은 LCS (Law Contrast Sensitivity) 관점에서 정량적으로 비친 평가하였다. 실험은 임상용 초음파 진단기 (SA-9000 PRIME, Medison, Korea)를 사용하여 초음파 평가 팬텀 (539, ATS, USA)의 LCS 타겟을 영상화하였다. 영상 조절 변수의 설정을 변화하면서, 각 설정에 대한, 6개의 LCS 영상 (+15 dB, +C dB, +3 dB, -3 dB, -6 dB, -15 dB)을 취득하고, 영상에 대한 LCS픽셀 값을 계산하였다. 실험결과 TGC가 최대, Gain은 중간에서 최대사이, 주파수가 Pen모드, DR이 40-66 dB일 때 타겟 영상 (LCS)의 평균 픽셀 값이 높았다. 모든 타겟 영상에서 DR이 40 dB일 때에 LCS가 좋은 영상을 얻었다. 본 결과는 임상에서 잘 발견되는 solid lesion (+15, +6, +3 dB 타겟과 유사) 또는 cystic lesion (-15, -6, -3 dB 타겟과 비슷)이 있는 mass 평가 시 적절한 영상조절 변수 설정에 유용한 정보를 제공할 것으로 기대된다.

• Investigative Magnetic Resonance Imaging
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• 제26권2호
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• pp.125-134
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• 2022

Purpose: The aim of this study was to investigate the change in signal sensitivity over different acquisition start times and optimize the scanning window to provide the maximal signal sensitivity of [1-¹³C]pyruvate and its metabolic products, lactate and alanine, using spatially localized hyperpolarized 3D ¹³C magnetic resonance spectroscopic imaging (MRSI). Materials and Methods: We acquired 3D ¹³C MRSI data from the brain (n = 3), kidney (n = 3), and liver (n = 3) of rats using a 3T clinical scanner and a custom RF coil after the injection of hyperpolarized [1-¹³C]pyruvate. For each organ, we obtained three consecutive 3D ¹³C MRSI datasets with different acquisition start times per animal from a total of three animals. The mean signal-to-noise ratios (SNRs) of pyruvate, lactate, and alanine were calculated and compared between different acquisition start times. Based on the SNRs of lactate and alanine, we identified the optimal acquisition start timing for each organ. Results: For the brain, the acquisition start time of 18 s provided the highest mean SNR of lactate. At 18 s, however, the lactate signal predominantly originated from not the brain, but the blood vessels; therefore, the acquisition start time of 22 s was recommended for 3D ¹³C MRSI of the rat brain. For the kidney, all three metabolites demonstrated the highest mean SNR at the acquisition start time of 32 s. Similarly, the acquisition start time of 22 s provided the highest SNRs for all three metabolites in the liver. Conclusion: In this study, the acquisition start timing was optimized in an attempt to maximize metabolic signals in hyperpolarized 3D ¹³C MRSI examination with [1-¹³C] pyruvate as a substrate. We investigated the changes in metabolic signal sensitivity in the brain, kidney, and liver of rats to establish the optimal acquisition start time for each organ. We expect the results from this study to be of help in future studies.

• 한국전기전자재료학회논문지
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• 제21권7호
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• pp.629-637
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• 2008

We report several experimental data capable of evaluating the amorphous-to-crystalline (a-c) phase transformation in $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ (x = 0, 0.05, 0.1) thin films prepared by a thermal evaporation. The isothermal a-c structural phase changes were evaluated by XRD, and the optical transmittance was measured in the wavelength range of $800{\sim}3000$ nm using a UV-vis-IR spectrophotometer. A speed of the a-c transition was evaluated by detecting the reflection response signals using a nano-pulse scanner with 658 nm laser diode (power P = $1{\sim}17$ mW, pulse duration t = $10{\sim}460$ ns). The surface morphology and roughness of the films were imaged by AFM. It was found that the crystallization speed was so enhanced with an increase of Ag content. While the sheet resistance of c-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was similar to that of c-phase $Ge_2Sb_2Te_5$ (i.e., $R_c{\sim}10{\Omega}/{\square}$), the sheet resistance of a-phase $(Ag)_x(Ge_2Sb_2Te_5)_{1-x}$ was found to be lager than that of a-phase $Ge_2Sb_2Te_5$, $R_a{\sim}5{\times}10^6{\Omega}{/\square}$. For example, the ratios of $R_a/R_c$ for $Ge_2Sb_2Te_5$ and $(Ag)_{0.1}(Ge_2Sb_2Te_5)_{0.9}$ were approximately $5{\times}10^5$ and $5{\times}10^6$, respectively.

• Journal of Korean Neurosurgical Society
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• 제56권4호
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• pp.330-333
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• 2014

Objective : To identify the accuracy and efficiency of the computed tomographic (CT)-based navigation system on upper cervical instrumentation, particularly C1 lateral mass and C2 pedicle screw fixation compared to previous reports. Methods : Between May 2005 and March 2014, 25 patients underwent upper cervical instrumentation via a CT-based navigation system. Seven patients were excluded, while 18 patients were involved. There were 13 males and five females; resulting in four degenerative cervical diseases and 14 trauma cases. A CT-based navigation system and lateral fluoroscopy were used during the screw instrumentation procedure. Among the 58 screws inserted as C1-2 screws fixation, their precise positions were evaluated by postoperative CT scans and classified into three categories : in-pedicle, non-critical breach, and critical breach. Results : Postoperatively, the precise positions of the C1-2 screws fixation were 81.1% (47/58), and 8.6% (5/58) were of non-critical breach, while 10.3% (6/58) were of critical breach. Most (5/6, 83.3%) of the critical breaches and all of non-critical breaches were observed in the C2 pedicle screws and there was only one case of a critical breach among the C1 lateral mass screws. There were three complications (two vertebral artery occlusions and a deep wound infection), but no postoperative instrument-related neurological deteriorations were seen, even in the critical breach cases. Conclusion : Although CT-based navigation systems can result in a more precise procedure, there are still some problems at the upper cervical spine levels, where the anatomy is highly variable. Even though there were no catastrophic complications, more experience are needed for safer procedure.

• Journal of Nutrition and Health
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• 제35권10호
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• pp.1053-1059
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• 2002

In post-genome period, the technique for identifying gene expression has been changed to high throughput screening. In the field of molecular nutrition, the need for this technique to clarify molecular function of the specific nutrient is essential. In this study, we have tested the zinc-regulated gene expression in zinc-deficient U937 cells, using cDNA microarray which is the cutting-edge technique to screen large numbers of gene expression simultaneously. The study result can be used for the preliminary gene screening data for clarifying, using monocyte U937 cell line, molecular Zn aspect in atherosclerosis. U937 cells were cultured in Zn-adequate (control, 12 $\mu$M Zn) or Zn-deficient (experimental, 0 $\mu$M Zn) ESMI media during 2 days, respectively. Cells were harvested and RNA was extracted. Total RNA was reverse-transcriptinized and synthesized cDNA probe labeled with Cy-3. fluorescent labeled cDNA probe was applied to microarray slide for hybridization slide, and after then, the slide was scanned using fluorescence scanner. ‘Highly expressed genes’ in Zn-deficient U937 cells, comparing to Zn-adequate group, are mainly about the genes for motility protein, immune system protein, oncogene and tumor suppressor and ‘Less highly expressed genes’ are about the genes for transcription, apoptosis associated protein, cell cycle, and several basic transcription factors. The results of this preliminary study imply the effectiveness of cDNA microarray for expression profiling of a singly nutrient deficiency, specially Zn. Furthur study, using tailored-cDNA array and capillary endothelial cell lines, would be beneficial to clarify molecular Zn function, more in detail.