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Carbon-coated iron oxide nanoparticles as contrast agents in magnetic resonance imaging
Bae, Hongsub,Ahmad, Tanveer,Rhee, Ilsu,Chang, Yongmin,Jin, Seong-Uk,Hong, Sungwook Springer 2012 Nanoscale research letters Vol.7 No.1
<P>Coprecipitated ferrite nanoparticles were coated with carbon using a hydrothermal method. From transmission electron microscope pictures, we could see that the coated iron oxide nanoparticles were spherical in shape with an average diameter of 90 nm. The strong bonding of carbon on the nanoparticle surfaces was checked by noting the C = O and C = C vibrations in Fourier transform infrared spectra. The spin-lattice relaxation process [<I>T</I><SUB>1</SUB>] and spin-spin relaxation process [<I>T</I><SUB>2</SUB>] relaxivities of hydrogen protons in the aqueous solution of coated nanoparticles were determined to be 1.139 (mM·s)<SUP>-1 </SUP>and 1.115 (mM·s)<SUP>-1</SUP>, respectively. These results showed that the carbon-coated iron oxide nanoparticles are applicable as both <I>T</I><SUB>1 </SUB>and <I>T</I><SUB>2 </SUB>contrast agents in magnetic resonance imaging.</P><P><B>PACS</B>: 81.05.y; 76.60.Es; 61.46; 75.50.k; 87.61.</P>
무회전축 회전식 수상태양광 시스템 및 실증 데이터 분석
지홍섭(Hongsub Jee),김민우(Minwoo Kim),배재성(Jaesung Bae),정정호(Jeongho Jeong),이재형(Jaehyeong Lee) 한국태양광발전학회 2021 Current Photovoltaic Research Vol.9 No.4
In this study, the pivotless tracking type floating photovoltaic system was demonstrated successfully. The photovoltaic modules were installed on buoyant objects and the dynamic stability reinforcement mooring gear, tension control equipment and buoyant stabilizer were used to provide enough buoyance and stability and response to the external environment. After installation of the pivotless tracking type floating photovoltaic system, generated solar energy was collected and analyzed.
Comparison of Solar Cells Interconnection with Metal Ribbons and Electrically Conductive Adhesives
Jaesung Bae(배재성),Juhwi Kim(김주휘),Jeongho Jeong(정정호),Jangwon Yoo(유장원),Chanyong Lee(이찬용),Hongsub Jee(지홍섭),Donggun Lim(임동건),Chaehwan Jeong(정채환),Jaehyeong Lee(이재형) 한국태양에너지학회 2021 한국태양에너지학회 학술대회논문집 Vol.2021 No.11
Ahmad, Tanveer,Bae, Hongsub,Rhee, Ilsu,Chang, Yongmin,Jin, Seong-Uk,Hong, Sungwook American Scientific Publishers 2012 Journal of Nanoscience and Nanotechnology Vol.12 No.7
<P>Gold-coated iron oxide (Fe3O4) nanoparticles were synthesized for use as a T2 contrast agent in magnetic resonance imaging (MRI). The coated nanoparticles were spherical in shape with an average diameter of 20 nm. The gold shell was about 2 nm thick. The bonding status of the gold on the nanoparticle surfaces was checked using a Fourier transform infrared spectrometer (FTIR). The FTIR spectra confirmed the attachment of homocysteine, in the form of thiolates, to the Au shell of the Au-Fe3O4 nanoparticles. The relaxivity ratio, R2/R1, for the coated nanoparticles was 3-fold higher than that of a commercial contrast agent, Resovist, which showed the potential for their use as a T2 contrast agent with high efficacy. In animal experiments, the presence of the nanoparticles in rat liver resulted in a 71% decrease in signal intensity in T2-weighted MR images, indicating that our gold-coated iron oxide nanoparticles are suitable for use as a T2 contrast agent in MRI.</P>
Yousaf Iqbal,Hongsub Bae,이일수,Sungwook Hong 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.4
Polyethylene-glycol (PEG)-coated nickel-ferrite nanoparticles were prepared for magnetic hyperthermia applications by using the co-precipitation method. The PEG coating occurred during the synthesis of the nanoparticles. The coated nanoparticles were rod-shaped with an average length of 16 nm and an average diameter of 4.5 nm, as observed using transmission electron microscopy. The PEG coating on the surfaces of the nanoparticles was confirmed from the Fourier-transform infrared spectra. The nanoparticles exhibited superparamagnetic characteristics with negligible coercive force. Further, magnetic heating effects were observed in aqueous solutions of the coated nanoparticles. The saturation temperature could be controlled at 42 C by changing the concentration of the nanoparticles in the aqueous solution. Alternately, the saturation temperature could be controlled for a given concentration of nanoparticles by changing the intensity of the magnetic field. The Curie temperature of the nanoparticles was estimated to be 495 C. These results for the PEG-coated nickel-ferrite nanoparticles showed the possibility of utilizing them for controlled magnetic hyperthermia at 42 C.
Magnetic heating of triethylene glycol (TREG)-coated zinc-doped nickel ferrite nanoparticles
Ahmad, Ashfaq,Bae, Hongsub,Rhee, Ilsu,Hong, Sungwook Elsevier 2018 Journal of magnetism and magnetic materials Vol.447 No.-
<P><B>Abstract</B></P> <P>Triethylene glycol (TREG)-coated nickel-zinc (Ni-Zn) ferrite nanoparticles were synthesized via the hydrothermal method and characterized for application to magnetic hyperthermia. Ni-Zn ferrite particles of Ni<SUB>1−x</SUB>Zn<SUB>x</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> with three different zinc contents of x=0.2, 0.4, and 0.6 were formulated to investigate the structural and magnetic properties according to the zinc content. Transmission electron microscopy images revealed that the particles were spherical in shape and that the average diameters of the particles were 10.67, 13.02, and 18.73nm for zinc contents of 0.6, 0.4, and 0.2, respectively. Fourier transform infrared spectroscopy confirmed that the TREG was firmly coated on the surface of the particles. The saturation magnetization decreased with the increasing zinc content in the particles, which affected the heating ability of the particles in the alternating magnetic field. The heating ability of the Ni<SUB>0.8</SUB>Zn<SUB>0.2</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> and Ni<SUB>0.6</SUB>Zn<SUB>0.4</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> particles facilitated the aqueous solution of these particles to reach the target temperature of 42°C for magnetic hyperthermia, while an aqueous solution of Ni<SUB>0.2</SUB>Zn<SUB>0.8</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> particles with a high particle concentration did not reach the target temperature. The high specific absorption rates of the Ni<SUB>0.8</SUB>Zn<SUB>0.2</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> and Ni<SUB>0.6</SUB>Zn<SUB>0.4</SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> particles indicate that these particles are applicable to magnetic hyperthermia.</P> <P><B>Highlights</B></P> <P> <UL> <LI> TREG-coated Ni-Zn ferrite nanoparticles were synthesized via the hydrothermal method. </LI> <LI> Ni-Zn ferrite particles with three different zinc contents were formulated. </LI> <LI> The high specific absorption rates indicate that particles are applicable to magnetic hyperthermia. </LI> </UL> </P>
바이패스 다이오드 구성에 따른 슁글드 태양광 모듈의 특성 시뮬레이션
배재성(Jaesung Bae),지홍섭(Hongsub Jee),박용섭(Yong Seob Park),이재형(Jaehyeong Lee) 한국신재생에너지학회 2021 한국신재생에너지학회 학술대회논문집 Vol.2021 No.7
최근 건물 일체형 태양광 발전과 같은 도심형 신재생에너지 발전이 증가하게 되면서 제한된 면적에서 높은 출력을 생산할 수 있는 고밀도, 고효율 태양광 모듈에 대한 관심도 커지고 있다. 고밀도 태양광 모듈을 제작하기 위한 방법은 Multi-wire, Gapless, Shingled과 같이 여러가지 기술이 있다. 그 중 Shingled 기술의 경우 일반적인 태양전지를 분할/접합하여 제작하는 구조로 하나의 분할 셀 전면부에 다른 분할 셀이 오버랩 되어 접합되기 때문에 전면부의 버스바 영역이 수광영역으로 바뀌어 더 높은 출력을 생산할 수 있다. 또한, 일반적인 태양광 모듈에 비해 태양전지간의 절연을 위한 공간이 감소하게 되므로 고효율, 고밀도 태양광 모듈로 제작할 수 있다. 하지만 슁글드 태양광 모듈의 경우 분할된 셀들이 직렬로 접합되어 하나의 스트링으로 제작되기 때문에 일반적인 태양광 모듈에 비해 음영에 의한 출력 손실이 발생하기 쉬워진다. 그러므로 음영에 따른 슁글드 태양광 모듈의 출력 손실을 최소화하기 위해서는 슁글드 스트링의 회로구성 및 바이패스 다이오드의 최적화가 필요하다. 본 연구에서는 슁글드 태양광 모듈의 직렬 연결 배선 및 스트링 구조를 설계하였고 그에 따라 바이패스 다이오드 수를 가변하여 나타나는 특성을 시뮬레이션 하였다. 결과적으로 시뮬레이션을 통해 바이패스 다이오드의 수를 최적화하였고 그에 따른 슁글드 태양광 모듈의 음영 특성을 분석하였다.
Intensive Analysis of Core—Shell Silica-Coated Iron-Oxide Nanoparticles for Magnetic Hyperthermia
Iqbal, Yousaf,Bae, Hongsub,Rhee, Ilsu,Hong, Sungwook American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.11
<P>We report the synthesis and characterization of silica-coated iron-oxide nanoparticles with a core-shell structure, which can be used for magnetic hyperthermia. The nanoparticles were synthesized by the reverse micelle method. The silica coating was performed simultaneously with the synthesis of the nanoparticles. The nanoparticles were characterized using various analytical tools. X-ray diffraction measurements confirmed their cubic spinel structure. Transmission electron microscopy (TEM) revealed monodisperse nanoparticles of nearly spherical core-shell structures with an average diameter of 17 nm. The bonding of the silica on the surface of the iron-oxide nanoparticles was confirmed by Fourier transform infrared spectrometry (FTIR). The silica-coated iron-oxide nanoparticles exhibited superparamagnetic properties with a saturation magnetization of 48.8 emu/g measured with a vibrating sample magnetometer (VSM). The applicability of the nanoparticles to magnetic hyperthermia was tested by measuring the temperature increase in an aqueous solution of nanoparticles in a 260 kHz alternating magnetic field. An optimum nanoparticle concentration of approximately 2.0 mg/ml achieved a saturation temperature of 42 degrees C, the target value for magnetic hyperthermia. The specific absorption ratio (SAR) for this sample was 87 W per gram of iron. The dependence of the SAR on the nanoparticle concentration and magnetic field strength was also measured. These results demonstrated the applicability of silica-coated iron-oxide nanoparticles to magnetic hyperthermia.</P>