• Proceedings of the KSME Conference
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• 2008.11a
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• pp.35-39
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• 2008

In this study, electromechanical properties of carbon nanotube (CNT) thin film on flexible substrates were measured using a micro-tensile machine with functionality of simultaneous measurements of displacement, load and electrical resistance. The CNT thin film of about 100 nm thick was deposited on flexible substrates, polyethylene terephthalate (PET) using spraying and ink-jetting techniques. To investigate the effect of process condition on the electromechanical properties of CNT thin film, sets of CNT samples were fabricated under various heat treatments and microwave process. The microstructures of the CNT thin film before and after tensile test were investigated using Scanning Electron Microscope (SEM), and the failure modes of the CNT thin films were identified to understand their electromechanical behaviors and interaction with the flexible substrates. Based on the experimental results, the use of CNT thin film as flexible electrodes and strain gages is discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.207-207
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• 2013

기존의 그래핀 성장에 관한 연구는 열화학기상증착법(Chemical vapor deposition; CVD)을 이용한다. 그래핀 성장 제어 요소로는 촉매 기판인 전이 금속[Ru, Ir, Co, Re, Pt, Pd, Ni, Cu], 기판 전처리 과정, 수소/메탄 가스 혼합비, 작업 진공 상태, 기판온도[$800{\sim}1,000^{\circ}C$, 냉각 속도 등으로 보고 되고 있다. 그래핀 성장 원리는 Cu 촉매 기판에 메탄 가스를 $1,000^{\circ}C$ 온도에서 분해해서 탄소를 고용 시킨 후 급랭하는 도중에 석출되는 탄소에 의해 그래핀 시트가 형성되는 것으로 알려져 있다. 기존의 CVD를 열원을 이용할 경우 내부 챔버에 생기는 잠열에 의해 cooling profile의 제어가 용이하지 않다. 본 연구에서는 근적외선(Near Infrared; NIR) 열원을 이용한 CVD로 챔버 내부 잠열을 최소화하고, 냉각 공정을 Natural, Linear, Convex cooling type으로 디자인해서 cooling profile 제어가 그래핀 성장에 미치는 영향을 연구 하였다. 이렇게 성장된 그래핀을 임의의 기판(SiO2, Glass, PET film) 위에 습식방법으로 전이 시킨 후, 전기적 구조적 및 광학적 특성을 면저항(four-point probe), 전계방사 주사전자현미경(Field Emission Scanning Electron Microscope; FE-SEM), 마이크로 라만 분광법(Micro Raman spectroscopy) 및 광학현미경(optical microscope), 투과도(UV/Vis spectrometer)의 측정으로 잠열이 최소화된 NIR-CVD에서 cooling profile에 따른 그래핀 성장을 평가하였다.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.90-90
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• 2012

극세섬유는, 1970년대 말부터 일본의 합섬업체들이 천연소재인 Silk를 모방하기 위해 개발을 시작하였으며, 개발된 섬유의 굵기가 0.5d(1denier=1g/9,000m)이하인 것을 말한다. 이후 극세사에 대한 끊임없는 노력으로, 1980년대에는 천연스웨이드 풍의 인조피혁의 제조가 가능한 0.1d이하급 초극세사가 N/P(Nylon/Polyester) 복합방사된 형태로 개발되었으며, 일본, 및 한국 등에서 이들 소재로 제조된 직편물 제품이 첨단 고부가소재로서 호황을 누려왔다. 이러한 초극세사는 다양한 형태로 발전되어왔는데, 해도형(Islands-in-a-Sea Type), N/P(Nylon/PET), P/N(PET/Nylon) 등이 대표적인 형태이며, 가공공정 중에서 분할이 되면서 그 특성을 발현한다고 하여 분할사, 형태에 따라서 N/P 분할사라 하기도 한다. 최근들어 이러한 N/P 분할사는 기존의 의류용 용도뿐만 아니라, Wiping Cloth, 극세사 타울, 항진드기용 침장 등 다양한 비의류용 소재로도 확대 전개되고 있으며, 이렇게 다양화 되어가고 있는 용도에 따른 공정별 최적 가공 방법에 대한 연구가 진행 중이다. 사가공 공정에 있어서는 텍스쳐링 방법이 적용되기도 하는데, 가장 보편화된 텍스쳐링 방법으로는 DTY(Draw Texturing Yarn), ATY(Air Texturing Yarn) 등의 형태가 있으며, 이러한 텍스쳐링 방법은 물성에 민감한 N/P 분할사의 강도, 신도, 분할도에 영향을 미치게 된다. 본 연구에서는 기존의 텍스쳐링 방법이 아닌 Fancy사 형태로 사가공을 하였으며, 직물로 제직하고, 분할 가공하여 직물로써의 물성까지 분석하였다. Fancy사는 색이나 형의 변화로 디자인효과를 준 실을 말하는데, 심사, 부사, 압사로 이뤄지며 의장사, 장식사 등으로 불려지기도 한다. 주요 공정을 보면, 크릴형성용 부사를 500-600T/M으로 가연한 연사를 얻는 제1공정과, 이 가연된 부사와 심사를 합사하는 제2공정 및 합사된 크릴의 뒤틀림을 방지하기 위하여 압사로 크릴을 고정하여 주는 제3공정으로 이루어진다. 사용된 N/P 분할사는 NP30/36dty, NP50/36dty를 사용하였으며, 부사의 오버피드 및 피드되는 사에 따라 각각 8종, 7종의 Fancy사를 제조하여 섬도(Denier), 강도(Tenacity), 신도(Elongation)를 측정하였다. 또한, 이들 사들로 제직 및 분할가공을 하여 인장강도, 인장신도, 인열강도, 마모강도, 공기투과도 등의 물성과 중량, 두께를 측정하였으며, 온도, NaOH 농도, 시간 등의 분할 가공조건에 따른 직물의 인열강도 변화도 측정하였다. 이렇게 공정별 조건에 따른 물성의 변화분석을 통해 추후 N/P의 제품화 전개에 도움이 되고자 하였다.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.1 no.1
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• pp.38-45
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• 2015

Most tumors are believed to overexpress several receptors, and small peptides targeting these receptors were developed for diagnosis and tumor therapy during past decade. Here we report that fibroadenoma can be visualized by bladder cancer specific peptide. A 9-mer bladder cancer specific peptide, which was discovered from the phage display method, was synthesized by peptide synthesizer, and additional tyrosine was conjugated at the N-terminal for radioiodination (Y-BP). Y-BP was radiolabeled with $^{131/124}I$ using Iodogen tube. The rat treated with N-butyl-N-(4-hydroxybutyl)nitrosamine for 8 weeks was allowed to grow until large size tumor was developed under axilla. The tumor model was microPET imaged sequentially using [$^{18}F$]FDG and radioiodinated $^{124}I-Y-BP$. The tumor was excised and examined by immunostaining studies. Radioiodinated $^{124}I-Y-BP$ was purified using fast protein liquid chromatography (FPLC) in > 90% radiochemical purity. The whole tumor was well visualized by [$^{18}F$]FDG with several intense focal uptake within tumor. The tumor was also clearly seen with $^{124}I-Y-BP$ at 4 h post-injection, and to our surprise the tumor uptake of $^{124}I-Y-BP$ lasted up to three days. The tumor was diagnosed histologically as a fibroadenoma derived from mammary gland. In conclusion, the bladder cancer specific peptide showed the good potential as a new radiotracer for the detection of breast fibroadenoma.

• The Korean Journal of Nuclear Medicine Technology
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• v.13 no.3
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• pp.147-151
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• 2009

Purpose: 2-[$^{18}F$]Fluoro-2-deoxy-D-glucose ([$^{18}F$]FDG) particularly plays as a important role in Positron Emission Tomography (PET) imaging in nuclear medicine. Domestic [$^{18}F$]FDG auto synthesizers are installed in Seoul National University Bundang Hospital (SNUBH) at June 2008, these modules were known that it's synthetic yields were guaranteed in average $45{\pm}5%$ so far. To improve yields and convenience of domestic [$^{18}F$]FDG auto synthesizer, numerous trials in reaction time, base concentration, pressure and temperature were performed to increase [$^{18}F$]FDG yields. Materials and Methods: Several synthetic factors (temperature, time and pressure) and shortcoming were corrected based on many evaporation test. Syringe dispensing of tetra-butylammonium bicarbonate (TBAB) was replaced with micro pipette to prepare tetrabutyl ammonium fluoride salt ([$^{18}F$]TBAF). Troublesome refill of liquid nitrogen every 2 hours which was used to protect vacuum system was changed to charcoal cartridge, base guard filter. To monitor the volume of delivered $[^{18}O]OH_2$ from cyclotron by surveillance camera, we set up the volumetric vial on the cover of the module. In addition to, the recovery vial was added in [$^{18}F$]FDG production system to recover [$^{18}F$]FDG loss due to the leak of valve ($V_{13,14}$) in [$^{18}F$]FDG purification process. Results: When we used micro pipette for adding TBAB ($30\;{\mu}L$ in 12% $H_2O$ in acetonitrile), this quantitative dispensation has enabled to improve $5.5{\pm}1.7%$ residual fluorine-18 activity in fluorine separation cartridge compared to syringe adding. Besides, the synthetic yields of [$^{18}F$]FDG has increased $58{\pm}2.6%$ (n=19), $58{\pm}2.9%$ (n=14), $60%{\pm}2.5%$ (n=17) for 3 months. The life cycle of charcoal cartridge and base vacuum was 3 months prior to filling liquid nitrogen every 2 hours and additional side separator can prevent pump corrosion by organic solvent. After setting of volumetric indicator vial, the operator can easily monitor the total volume of irradiated $[^{18}O]OH_2$ from cyclotron. The recovery vial can be used for the stabilizer when an irregular [$^{18}F$]FDG loss was generated by the leak of valves ($V_{13,14}$). Conclusions: We has optimized appropriate synthetic conditions (temperature, time, pressure) in domestic [$^{18}F$]FDG auto synthesizer. In addition to, the remodeling with several accessories improve yields of domestic [$^{18}F$]FDG auto synthesizer with reliable reproducibility.

• Design & Manufacturing
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• v.17 no.3
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• pp.48-54
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• 2023

In this study, an injection mold with ultra-small surface properties was manufactured using nanosecond laser processing. A superhydrophobic characteristic analysis was performed on the PET specimen manufactured through this. To this end, a hydrophobic pattern was defined using the Cassie-Baxter model. The defined features were selected with a spot diameter of 25um and pitch spacing of 30um and 35um. As a result of the basic experiment, it was confirmed that the fine pattern shape had an aspect ratio of 1:1 when the pitch interval was 35um and 20 iterations. Through the determined processing conditions, a hydrophobic pattern was implemented on the core surface of KP4. A specimen with a hydrophobic pattern was produced through injection molding. The height of the molded hydrophobic pattern is 20 ㎛ less than the depth of the core and the contact angle measurement results are 92.1°. This is a contact angle smaller than the superhydrophobic criterion. Molding analysis was performed to analyze the cause of this, and it was analyzed that the molding was not molded due to the lack of pressure in the injection machine.

• Nuclear Medicine and Molecular Imaging
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• v.41 no.3
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• pp.226-233
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• 2007

Purpose: Dual reporter gene imaging has several advantages for more sophisticated molecular imaging studies such as gene therapy monitoring. Herein, we have constructed hepatoma cell line expressing dual reporter genes of sodium iodide symporter (NIS) and enhanced green fluorescence protein (EGFP), and the functionalities of the genes were evaluated in vivo by nuclear and optical imaging. Materials and Methods: A pRetro-PN vector was constructed after separating NIS gene from pcDNA-NIS. RSV-EGFP-WPRE fragment separated from pLNRGW was cloned into pRetro-PN vector. The final vector expressing dual reporter genes was named pRetro-PNRGW. A human hepatoma (HepG2) cells were transfected by the retrovirus containing NIS and EGFP gene (HepG2-NE). Expression of NIS gene was confirmed by RT-PCR, radioiodine uptake and efflux studies. Expression of EGFP was confirmed by RT-PCR and fluorescence microscope. The HepG2 and HepG2-NE cells were implanted in shoulder and hindlimb of nude mice, then fluorescence image, gamma camera image and I-124 microPET image were undertaken. Results: The HepG2-NE cell was successfully constructed. RT-PCR showed NIS and EGFP mRNA expression. About 50% of cells showed fluorescence. The iodine uptake of NIS-expressed cells was about 9 times higher than control. In efflux study, $T_{1/2}$ of HepG2-NE cells was 9 min. HepG2-NE xenograft showed high signal-to-background fluorescent spots and higher iodine-uptake compared to those of HepG2 xenograft. Conclusion: A hepatoma cell line expressing NIS and EGFP dual reporter genes was successfully constructed and could be used as a potential either by therapeutic gene or imaging reporter gene.

• Journal of Animal Science and Technology
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• v.45 no.2
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• pp.191-198
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• 2003

This study was carried out to investigate a usefulness of the microsatellite DNA markers for individual identification and parentage verification in three dog breeds. A total of 59 random dog (31 Chiwawa, 20 Poongsan, 8 Labrador Retriever) samples were genotyped by using 14 markers (Chiwawa dog), 16 markers (Poongsan dog), and 12 markers (Labrador Retriever dog) among the 17 international standard markers (PEZ1, 3, 5, 6, 8, 10, 11, 12, 13, 15, 16, 17, 20, 21, FHC2010, FHC2054 and FHC2079), respectively. The number of alleles per locus varied from 4 to 14 with a mean value of 6.07 in Chiwawa dog, 2 to 9 with a mean of 4.75 in Poongsan dog, and 3 to 5 with a mean of 4.00 in Labrador Retriever dog. Observed heterozygosity was ranged 0.419${\sim}$0.968 (mean 0.755), 0.300${\sim}$0.950 (mean 0.597) and 0.125${\sim}$0.750 (mean 0.604), and expected heterozygosity was ranged 0.432${\sim}$0.883 (mean 0.711), 0.262${\sim}$0.817 (mean 0.559) and 0.425${\sim}$0.808 (mean 0.660) in these three dog breeds. PIC value was ranged 0.397${\sim}$0.856 (mean 0.659), 0.222${\sim}$0.772 (mean 0.503) and 0.354${\sim}$0.717 (mean 0.563) in these three dog breeds. Of the 17 markers, PEZ1, PEZ3, PEZ6, PEZ10, PEZ12 loci, PEZ1, PEZ6, PEZ13 loci, and PEZ8, PEZ12 loci have relatively high PIC value (＞0.7) in Chiwawa dog, Poongsan dog and Labrador Retriever dog, respectively. The exclusion probability was ranged 0.240${\sim}$0.741, 0.111${\sim}$0.616, and 0.198${\sim}$0.529, and the combination of microsatellite loci was 0.9999, 0.9991, and 0.9968 in Chiwawa dog, Poongsan dog and Labrador Retriever dog, respectively. These results can give basic information for developing parentage verification and individual identification system in these three dog breeds.