• 핵의학기술
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• 제18권1호
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• pp.19-25
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• 2014

PET/MRI에서는 MRI의 진단적 가치를 높이기 위해 T1 조영제를 사용하고 있다. PET의 감쇠 보정을 위해 T1 시컨스 계열인 VIBE DIXON은 조영제에 직접적으로 영향을 미치지만, 실제 ${\mu}-map$과 감쇠 보정된 PET 영상에는 큰 변화가 없었다. 그러므로 PET/MRI 검사시 조영제 사용은 PET 데이터 얻기 전 후 언제든 사용할 수 있을 것이다.

• Investigative Magnetic Resonance Imaging
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• 제25권4호
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• pp.209-217
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• 2021

Magnetic resonance angiography (MRA) plays an important role in accurate diagnosis and appropriate treatment planning for patients with arterial disease. Contrast-enhanced (CE) MRA is fast and robust, offering hemodynamic information of arterial flow, but involves the risk of a side effect called nephrogenic systemic fibrosis. Various non-contrast-enhanced (NCE) MRA techniques have been developed by utilizing the fact that arterial blood is moving fast compared to background tissues. NCE MRA is completely free of any safety issues, but has different drawbacks for various approaches. This review article describes basic principles of CE and NCE MRA techniques with a focus on how to generate angiographic image contrast from a pulse sequence perspective. Advantages, pitfalls, and key applications are also discussed for each MRA method.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2199-2206
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• 2014

본 연구는 자기공명 견관절조영검사 시 단위 부피당 가돌리늄 함유량이 2배 많은 1mmol/mL 조영제를 이용하여 T1 단축효과를 높임으로서 진단적 가치가 높은 영상을 얻을 수 있는 방법을 증명하고자 하였다. 2012년 1월부터 2013년 8월까지 0.5mmol/mL 함유량을 가진 기존의 조영제를 사용한 20명과 1mmol/mL 함유량을 가진 새로운 조영제를 사용한 21명 등 총 41명의 환자를 연구대상으로 하였다. 연구방법은 가돌리늄 함유량에 따른 대조도 차이를 알아보기 위하여, 견관절의 관절공간과 인접한 근육조직인 극상근, 그리고 상완골두의 신호강도를 각각 측정한 후 신호대잡음비와 대조도대잡음비를 비교하였다. 연구 결과, 가돌리늄 함유량이 높은 1mmol/mL 조영제가 0.5mmol/mL 조영제에 비해 SNR이 모두 높았으며(관절공간 38.01%, 극상근 8.40%, 상완골두12.78%), CNR도 가돌리늄 함유량이 높은 1mmol/mL 조영제가 높았다(관절공간과 극상근 48.96%, 관절공간과 상완골두 42.00%). 결론적으로 T1 단축효과를 높이는 다양한 방법 중 현실적으로 구현하기 용이한 가돌리늄 함유량이 높은 1mmol/mL 조영제를 이용하면 효율적으로 T1 단축효과를 높여 진단적 가치가 높은 영상을 얻을 수 있을 것으로 판단된다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.1-1
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• 2011

We developed a new generalized synthetic procedure, called as "heat-up process," to produce uniform-sized nanocrystals of many transition metals and oxides without a size selection process. We were able to synthesize uniform magnetite nanocrystals as much as 1 kilogram-scale from the thermolysis of Fe-oleate complex. Clever combination of different nanoscale materials will lead to the development of multifunctional nano-biomedical platforms for simultaneous targeted delivery, fast diagnosis, and efficient therapy. In this presentation, I would like to present some of our group's recent results on the designed fabrication of multifunctional nanostructured materials based on uniform-sized magnetite nanoparticles and their medical applications. Uniform ultrasmall iron oxide nanoparticles of <3 nm were synthesized by thermal decomposition of iron-oleate complex in the presence of oleyl alcohol. These ultrasmall iron oxide nanoparticles exhibited good T1 contrast effect. In in vivo T1 weighted blood pool magnetic resonance imaging (MRI), iron oxide nanoparticles showed longer circulation time than commercial gadolinium complex, enabling high resolution imaging. We used 80 nm-sized ferrimagnetic iron oxide nanocrystals for T2 MRI contrast agent for tracking transplanted pancreatic islet cells and single-cell MR imaging. We reported on the fabrication of monodisperse magnetite nanoparticles immobilized with uniform pore-sized mesoporous silica spheres for simultaneous MRI, fluorescence imaging, and drug delivery. We synthesized hollow magnetite nanocapsules and used them for both the MRI contrast agent and magnetic guided drug delivery vehicle.

• Bulletin of the Korean Chemical Society
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• 제31권3호
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• pp.639-644
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• 2010

Amphiphilic porphyrin derivatives have been synthesized and characterized by $^1H$ NMR and MALDI-TOF-MS. All porphyrin derivatives showed very high solubility to aqueous medium as well as hydrophobic organic solvent. The UV-vis absorption of the porphyrin derivatives showed significant broadness and decrease of maximum intensity of absorption in aqueous solution. SEM experiment showed the formation of spherical micellar structure. The $T_1$ relaxation time of aqueous medium was drastically decreased in the presence of Mn(III)-porphyrin derivative, indicating that the supramolecular micelle has strong possibility to use as a $T_1$ contrast agent.

• 한국임상수의학회지
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• 제17권1호
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• pp.243-246
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• 2000

A 3-year old female Poodle dog was presented with a history of anorexia, vomiting, abdominal pain and depression for 2 days. After physical and blood examination, excretory urogram(EU) and ultrasonography of the abjomen were conducted. On radiographs and ultrasonographs, dilation of diverticulum, sinus, proximal ureter of right kidney and mild dilation of left renal medullar were found. And there was some leakage of contrast agent in the proximal ureter area of right kidney. So this was diagnosed as a rupture of right proximal ureter. This dog was undertaken a surgery of nephrectomy of right kidney. On surgery, dilation of right kidney and hemorrhage, adhesion were found at the proximal ureter and some calculi were also found in the pelvis of right kidney. There were no complications after surgery.

• 한국가시화정보학회지
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• 제3권1호
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• pp.26-35
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• 2005

The combination of ultrasound echo images with digital particle image velocimetry (DPIV) method has resulted in a two-dimensional, two-component velocity field measurement technique appropriate for opaque flow conditions including blood flow in clinical applications. Advanced PIV processing algorithms including an iterative scheme and window of offsetting were used to increase spatial resolution. The optimum concentration of the ultrasound contrast agent used for seeding was explored. Velocity validation tests in fully developed laminar pipe flow and pulsatile flow showed good agreement with both optical PIV measurements and the known analytic solution. These studies indicate that echo PIV is a promising technique for the non-invasive measurement of velocity profiles and shear stress.

• 제어로봇시스템학회논문지
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• 제18권7호
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• pp.617-621
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• 2012

This paper studies asymptotic consensus problem for linear multi-agent systems. We propose a distributed state feedback control algorithm for solving the problem under fixed and undirected network communication. In contrast with the conventional algorithms that use global information (e.g., graph connectivity), the proposed algorithm only uses local information from neighbors. The principle for achieving asymptotic consensus is that, for each agent, a distributed update law gradually increases the coupling gain of LQR-type feedback and thus, the overall stability of the multi-agent system is recovered by the gain margin of LQR.

• 한국인쇄학회지
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• 제16권1호
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• pp.25-38
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• 1998

The developing agent is the materials which first acts on silver grain and make it into metallic silver by reducing reaction. There are several types in developing agent, and according to Lumiere-Andresen principle, substitution product which has amino or hydroxyl group in benzen nucleus has a developing power, but all reduing substances are not in used. In the developing effect, not only the role of developing agent but also that of assistant materials are important. But in this work, we have studied effect, change by lith developing agent which require high contrast image. We made an developing experiment after having manufactured developing solution used hydroquinone and another developing agents like chlorohydroquinone, pyrocatechol and pyrogallol as developing agent. And we added that did in addition of diethanolamine and ascorbic acid, and then we examined the possibility of use.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.292-297
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• 1999

Evolving in artificial agent is an extremely difficult problem, but on the other hand, a challenging task. At present the studies mainly centered on single agent learning problem. In our case, we use simulated soccer to investigate multi-agent cooperative learning. Consider the fundamental differences in learning mechanism, existing reinforcement learning algorithms can be roughly classified into two types-that based on evaluation functions and that of searching policy space directly. Genetic Programming developed from Genetic Algorithms is one of the most well known approaches belonging to the latter. In this paper, we give detailed algorithm description as well as data construction that are necessary for learning single agent strategies at first. In following step moreover, we will extend developed methods into multiple robot domains. game. We investigate and contrast two different methods-simple team learning and sub-group loaming and conclude the paper with some experimental results.