• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2000년도 동계총회 및 제16회 자기공명 학술발표회
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• pp.20-20
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• 2000

• 세라미스트
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• 제22권3호
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• pp.269-280
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• 2019

Ceramic layered double hydroxide (LDH) nanohybrids have attracted considerable interest in biomedical science due to their unique structural feature and characteristics in biological condition. Many studies on LDH nanoparticles have been reported in diagnosis applications including magnetic resonance imaging (MRI) contrast agents in order to not only provide better imaging performance through multimodal imaging strategy, but realize therapeutic function which treat cancers in one platform. This review highlights the recent progress in MRI T₁ contrast agent, dual modal imaging system, and MRI-guided drug delivery systems ranging from synthetic method and characterization to evaluation in vitro and in vivo based on the ceramic LDH nanohybrids. Future research directions are also suggested for next-generation bio-imaging contrast agent.

• 한국방사선학회논문지
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• 제17권6호
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• pp.827-833
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• 2023

방사선 촬영 조영제는 특수 조영을 필요로 하는 병원에서 인체 장기 및 특정한 부위 검사를 촬영할 때 흔히 쓰이고 있다. 특히 컴퓨터단층촬영(Computed Tomography CT) 조영제는 요오드(Iodine)라는 물질이 혼합되어 있는데 이것이 방사선의 에너지를 흡수하면서 방사선 영상 이미지에서 하얀색으로 보이게 되어 영상의 화질을 더욱 개선시킨다. 또한, 혈관에서 혈액과 같이 움직이는 CT 조영제는 근육 및 물과 확연히 구분을 시켜주고 있어 조영제를 병원에서 많이 사용하고 있다. 이러한 조영제는 엑스레이를 흡수하지만, 엑스레이를 흡수하기 위해서는 밀도가 높거나 방사선 흡수계수가 높아야 한다. 조영제가 혈관에 투입되기 때문에 밀도가 높으면 혈관에 무리가 가서 환자는 쇼크 상태가 오기 때문에 물과 비슷한 밀도를 맞춰야 하고 부작용에 대해 항상 신경을 써야한다. 또한, CT 조영제의 양을 환자의 체형에 따라 조절하면서 쓰고 남은 조영제를 폐기하는데 이것을 방사선 차폐재로 재활용을 할 수 있는 아이디어를 알아보고자 하였다. 조영제와 물을 혼합하는 방법에는 조영제 10%와 물 90%, 조영제 30%와 물 70%, 조영제 50%와 물 50%으로 3가지로 혼합하였다. CT 촬영은 광주광역시 U병원에서 GE사 4채널 CT를 사용하였으며 조영제와 물을 혼합하여 듀란병에 저장하였으며, 물 90%와 조영제 10% 혼합 액체의 밀도가 1.4 g/mL 정도일 때의 물질을 찾아보면 MYLAR라는 물질과 비슷한 것을 확인하였고, 물 70%와 조영제 30% 혼합 액체의 밀도가 1.76 g/mL일 때는 Polyvinylidene과 비슷한 물질인 것을 알 수 있었으며, 물 50%와 조영제 50%일 때 혼합 액체의 밀도는 2.3 g/mL일 때는 콘크리트(concrete) 밀도와 비슷한 밀도를 구성하고 있음을 알 수 있었다. 본 실험의 결과를 통해서 물 50%와 조영제 50%를 혼합한 액체는 콘크리트 차폐와 비슷한 밀도를 가지고 방사선의 차폐가 가능하였다. 따라서 콘크리트 두께와 비교하여 조영제를 50% 이상 첨가한 두께를 이용한 차폐재를 만든다면 충분한 차폐재의 역할을 할 수 있을 것으로 생각된다.

• 한국토양비료학회지
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• 제48권6호
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• pp.634-640
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• 2015

Chelating agents have been proposed to improve the efficiency of phytoextraction of heavy metal hyperaccumulator. However, little studies to elucidate mechanism of chelating agents to increase cadmium (Cd) extractability have been conducted. The objectives of this study were to evaluate effect of different chelating agents on Cd extractability and to determine mechanism of Cd mobilization affected by these agents. An arable soil was spiked with inorganic Cd ($CdCl_2$) to give a total Cd concentration of $20mgCdkg^{-1}$. Ethylenediaminetetraacetic acid (EDTA) and citric acid (CA) were selected and mixed with the arable soil at the rates of 0 and $5mmolkg^{-1}$. The mixture soils were incubated at $25^{\circ}C$ for 4 weeks in dark condition. Concentration of F1 Cd fractions (water soluble) significantly increased with addition of EDTA but did not changed with addition of CA. Especially; concentration of F5 Cd fractions (residual) significantly increased with addition of CA. Increase in water soluble with EDTA might be attributed to complexation of Cd and EDTA. Dissolved organic carbon concentration significantly increased with EDTA addition, but did not with CA implying that considerable amount of CA was decomposed to inorganic carbon by microorganism. Log activity of carbonate ($CO_3{^{2-}}$) which might be generated from CA increased with addition of CA. Increase in residual Cd fraction might be due to precipitation of Cd as $CdCO_3$. As a result, EDTA was effective in increasing Cd extractability, by contrast CA had significant effect in reducing Cd extractability.

• 한국자기공명학회논문지
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• 제9권2호
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• pp.93-102
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• 2005

Purpose: To develop an advanced non-linear curve fitting (NLCF) algorithm for dynamic susceptibility contrast study of brain. Materials and Methods: The first pass effects give rise to spuriously high estimates of $K^{trans}$ in voxels with large vascular components. An explicit threshold value has been used to reject voxels. Results: By using this non-linear curve fitting algorithm, the blood perfusion and the volume estimation were accurately evaluated in T2*-weighted dynamic contrast enhanced (DCE)-MR images. From the recalculated each parameters, perfusion weighted image were outlined by using modified non-linear curve fitting algorithm. This results were improved estimation of T2*-weighted dynamic series. Conclusion: The present study demonstrated an improvement of an estimation of kinetic parameters from dynamic contrast-enhanced (DCE) T2*-weighted magnetic resonance imaging data, using contrast agents. The advanced kinetic models include the relation of volume transfer constant $K^{trans}\;(min^{-1})$ and the volume of extravascular extracellular space (EES) per unit volume of tissue $\nu_e$.

• 정보관리연구
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• 제32권1호
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• pp.50-70
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• 2001

오늘날의 통신망은 전형적으로 이형의 다중 플랫폼이며, 서로 다른 제조회사의 통신망 장비를 복합적으로 구성하여 사용하기 때문에 이식성과 플랫폼 독립성을 지원하는 이동 에이전트(mobile agent)를 이용하는 것이 효율적이다. 따라서, 이동 에이전트는 네트워크 관리를 위해 관리 장비에 SNMP(Simple Network Management Protocol) 에이전트처럼 정적으로 존재하는 것이 아니라, 관리자를 대신하여 이동하고 자율적인 실행을 통해 통신망 장애를 진단하고 고칠 수 있도록 독립적으로 기능 구현이 가능하며, 나아가 지능이 있는 이동 에이전트를 제공할 수 있다. 이 연구는 효율적인 통신망 관리를 위해서 SNMP 에이전트의 관리 정보인 MIB를 JAMAS 상의 이동 에이전트가 접근하여 대화를 통해 수집한 후, 관리자에게 전달하는 MIB 브라우저 역할 수행의 이동 에이전트를 구현하고, 기존 방식과 제안된 이동 에이전트를 적용한 모델간의 성능을 평가하여 효율성을 입증한다.

• 대한핵의학회지
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• 제39권2호
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• pp.141-145
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• 2005

Hypoxia (decreased tissue oxygen tension) is a component of many diseases such as tumors, cerebrovascular diseases and ischemic heart diseases. Although hypoxia can be secondary to a low inspired $pO_2$ or a variety of lung disorders, the most common cause is ischemia due to an oxygen demand greater than the local oxygen supply. In the heart tissue, hypoxia is often observed in persistent low-flow states, such as hibernating myocardium. Direct "hot spot" imaging of myocardial tissue hypoxia is potentially of great clinical importance because it may provide a means of identifying dysfunctional chronically ischemic but viable hibernating myocardium. A series of radiopharmaceuticals that incorporate nitroimidazole moieties have been synthesized to detect decreased local tissue pO2. In contrast to agents that localize in proportion to perfusion, these agents concentrate in hypoxic tissue. However, the ideal agents are not developed yet and the progress is very slow. Furthermore, the research focus is on tumor hypoxia nowadays. This review introduces the myocardial hypoxia imaging with summarizing the development of radiopharmaceuticals.

• 대한자기공명의과학회:학술대회논문집
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• 대한자기공명의과학회 2007년도 학술대회
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• pp.30-30
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• 2007

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2002년도 International Symposium on Magnetic Resonance
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• pp.45-46
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• 2002

• Investigative Magnetic Resonance Imaging
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• 제23권1호
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• pp.34-37
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• 2019

Gadolinium contrast agents (CAs) are integral components of clinical magnetic resonance imaging (MRI). However, safety concerns have arisen regarding the use of gadolinium CAs, due to their association with nephrogenic systemic fibrosis (NSF). Furthermore, recently the long-term retention of $Gd^{3+}-based$ CAs in brains patients with normal renal function raised another possible safety issue. The safety concerns of $Gd^{3+}-based$ CAs have been based on the ligand structure of $Gd^{3+}-based$ CAs, and findings that $Gd^{3+}-based$ CAs with linear ligand structures showed much higher incidences of NSF and brain retention of CAs than $Gd^{3+}-based$ CAs with macrocyclic ligand structure. In the current study, we report the in vivo biodistribution profile of a new highly stable multifunctional $Gd^{3+}-based$ CA, with macrocyclic ligand structure (HNP-2006). MR imaging using HNP-2006 demonstrated a significant contrast enhancement in many different organs. Furthermore, the contrast enhanced tumor imaging using HNP-2006 confirmed that this new macrocyclic CA can be used for detecting tumor in the central nervous system. Therefore, this new multifunctional HNP-2006 with macrocyclic ligand structure shows great promise for whole-body clinical application.