• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.262-262
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• 2006

Biodegradable and amphiphilic di-block and tri-block copolymers, prepared with monomethoxy poly ethylene glycol (MPEG) and ${\varepsilon}-caprolactone\;({\varepsilon}-CL)$, were used for the application of W1/O/W2 multi- emulsion capsules. The effects of topology and the ratio of hydrophilic moiety of PCL-based polymers on the encapsulation efficiency of the $W_{1}/O/W_{2}$ multi-emulsion capsules containing Ascorbic Acid-2-Glucoside (AA-2-G) were investigated. The ratio of PEG and PCL was 1:0.5, 1:0.75, 1:1, and 1:1.25. PEG-PCL block copolymers were added to the first step of the preparation of $W_{1}/O$ emulsions. The dispersion stability, the particle size, the morphology of the $W_{1}/O/W_{2}$ multi-emulsion capsules were observed using an on-line turbidity meter, dynamic light scattering (DLS), a confocal microscopy (with FITC) and an optical microscopy. Biodegradable behavior of the PEG-PCL block copolymers and release behavior of AA-2-G were also observed by Gel Permeation Chromatography (GPC) and High Performance Liquid Chromatography (HPLC).

• 대한화장품학회지
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• 제20권1호
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• pp.37-51
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• 1994

Glutaraldehyde를 사용하여 화학적인 가교반응에 의해 empty cross-linked chitosan microcapsule을 제조하였다. 또한 chitosan bead는 sodium hydroxide 용액을 이용한 coaervation에 의해 제조하였다. 이들의 제조를 위해 수상/유화제/유기상으로 이루어진 w/o emulsion을 형성시킨 후 에멀젼의 안정성에 영향을 미치는 요소들에 대해 조사하였다. 보조계면활선제로 n-hexanol을 첨가한 결과 유화안정성이 상승적으로 증가하는 경향을 보였다. Chitosan microcapsule은 광택이 나는 형태로 내부가 투명한 반면 chitosan bead는 백탁으로 내부가 불투명하며 매우 porous한 구조를 하고 있었다. Chitosan bead의 유리 아미노기의 분석은 picric acid titration으로 수행하였으며, 아미노산 반응의 종결여부는 ninhydrin color test에 의해 판정하였다. 또한 fluoroscamine에 의한 형광분석으로 chitosan bead의 표면에 많은 반응성 아미노기가 존재하고 있음을 정성적으로 확인할 수 있었으며, 이를 생리활성 펩티드의 커플링 반응에 이용할 수 있었다. 모델 펩티드로서 콜라겐의 receptor 부분에 해당하는 생체내 growth factor로 알려진 Gly-His-Lys를 각 아미노산 유도체를 차례로 커플링하여 chitosan bead 위에서 합성할 수 있으며, 세포 성장인자와 같은 여러 가지 생리 활성 펩티드의 운반체로서 chitosan bead가 쉽게 이용될 수 있는 가능성을 보여 주었다.

• Journal of Pharmaceutical Investigation
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• 제31권1호
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• pp.43-47
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• 2001

Sterically stabilized liposomes (SSL) have been introduced for longer circulation in blood than conventional liposomes (CL). However, there are a couple of problems in SSL preparation due to the instability of phospholipid and the degradation of drug in aqueous conditions. To solve these problems, it is necessary to go through lyophilization process. Therefore, in this study, effects of lyophilization on SSL were evaluated for physical characteristics changes upon rehydration of lyophilized SSL such as the particle size, efficiency of drug entrapment, turbidity and drug release. SSL containing streptozocin, a water-soluble anticancer drug as a model compound, were prepared with DSPC and DSPE-PEG 2000. The size was controlled to 100 nm by extrusion with polycarbonate membrane, and sucrose was used as a cryoprotectant for lyophilization at the 1:3 (lipid:sucrose) ratio. Upon rehydration of lyophilized SSL, the average size was in the range of $50{\sim}200\;nm$ which is adequate for longer circulation in blood, and the encapsulation efficiency was kept as its initial state. Rehydrated SSL were not adsorbed to rat plasma protein and revealed a similar drug release profile to that of fresh SSL before lyophilization. Therefore, lyophilization could be introduced efficiently to overcome aqueous instability problems of SSL.

• Archives of Pharmacal Research
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• 제26권5호
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• pp.426-431
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• 2003

This study was carried out to investigate the addition of water-soluble isoflavone into milk by means of microencapsulation technique. The yield of microencapsulation, sensory attributes, and capsule stability of water-soluble isoflavone microcapsules in milk were measured. Coating materials used was polyglycerol monostearate (PGMS), and core material was water-soluble isoflavone. The encapsulation yield of water-soluble isoflavone with PGMS was 67.2% when the ratio of coating material to core material was 15 : 1. The rate of water-soluble isoflavone release from capsules was 18, 19, and 25% when stored at 4,20, and $30^{\circ}C$ for 12 days in milk, respectively. In sensory evaluation, beany flavor and color of microencapsuled water-soluble isoflavone added milk were significantly different from uncapsuled water-soluble isoflavone added milk, however, bitterness was not significantly different. In vitro study, micro-capsules of water-soluble isoflavone in simulated gastric fluid with the range of 3 to 6 pHs were released 3.0∼15.0%, however, the capsules in simulated intestinal fluid with pH 7 were released 95.7% for 40 min incubation time. In conclusion, this study provided that PGMS as coating materials was suitable for the microencapsulation of water-soluble isoflavone, and the capsule containing milk was almost not affected with sensory attribute.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.552-552
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• 2012

We fabricated reduced graphene oxide field-effect transistor (RGO-FET) on glass for highly sensitive temperature and IR detection. The device has the channels of RGO responsive to physical stimuli such as temperature and IR. The RGO sensing layers are fabricated from exfoliated graphene oxide sheets that are deposited to form a thin continuous network by electrostatic assembly. These graphene oxide networks are reduced toward reduce graphene oxide by exposure to a hydrazine hydrate vapor. To improve performance and eliminate interferences from oxygen and water vapor absorption to electrical properties of RGO-FET, the sensor devices were encapsulated by the tetratetracontane layer after annealing treatment. The device with encapsulation layer showed lower hysteresis, improved stability, and better repeatability. The temperature response of RGO-FET is examined by measuring changing the temperature, the device exhibited the high sensitivity and repeatability even with the temperature interval of 1 K. We also demonstrated that our devices have capability of IR sensing.

• 한국식품과학회지
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• 제31권2호
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• pp.280-284
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• 1999

Ascorbic acid의 불안정성을 극복하기 위하여, 탈수화/재수화의 방법을 이용하여 soybean phosphatidyl choline으로 제조한 리포솜에 ascorbic acid를 미세캡슐화하였다. Ascorbic acid는 46.8%의 효율로 리포솜내에 포집되었다. 리포솜 내에서의 ascorbic acid는 수용액에서보다 안정성이 매우 증대되었다. 예로 pH 5.0의 acetate buffer에서의 ascorbic acid는 7일 경과 후에 대부분이 산화되지만, 같은 조건에서 리포솜에 미세캡슐화되었을 경우는 40일이 경과하여도 22.8%가 환원된 상태를 유지하였다. 이러한 결과는 리포솜으로 ascorbic acid를 미세캡슐화하면 저장 기간을 향상시키는 보호 수단으로 이용될 수 있음을 의미한다.

• Smart Structures and Systems
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• 제1권4호
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• pp.355-368
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• 2005

Large and complex structures are being built now-a-days and, they are required to be functional even under extreme loading and environmental conditions. In order to meet the safety and maintenance demands, there is a need to build sensors integrated structural system, which can sense and provide necessary information about the structural response to complex loading and environment. Sophisticated tools have been developed for the design and construction of civil engineering structures. However, very little has been accomplished in the area of monitoring and rehabilitation. The employment of appropriate sensor is therefore crucial, and efforts must be directed towards non-destructive testing techniques that remain functional throughout the life of the structure. Fiber optic sensors are emerging as a superior non-destructive tool for evaluating the health of civil engineering structures. Flexibility, small in size and corrosion resistance of optical fibers allow them to be directly embedded in concrete structures. The inherent advantages of fiber optic sensors over conventional sensors include high resolution, ability to work in difficult environment, immunity from electromagnetic interference, large band width of signal, low noise and high sensitivity. This paper brings out the potential and current status of technology of fiber optic sensors for civil engineering applications. The importance of employing fiber optic sensors for health monitoring of civil engineering structures has been highlighted. Details of laboratory studies carried out on fiber optic strain sensors to assess their suitability for civil engineering applications are also covered.

• 한국식품저장유통학회지
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• 제9권2호
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• pp.194-199
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• 2002

천연식초를 이용하여 분말식초의 제조방법을 개발하고 아울러 분말식초의 품질특성 및 제조공정을 평가하여 분말식초의 제조 가능성을 검토하고자 하였다. 식초와 포접물질을 혼합한 포접물의 최적 농도는 피복물질의 양이 많을수록 흡습이 잘 되지 않고 열에도 안정함을 보였으나 포접물질의 양이 증가할수록 포접물질의 맛이 강하게 나타나 식초의 고유한 관능적인 특성이 떨어지므로 포접물의 농도를 30。bx 로 결정하였다. 분무건조공정을 최적화하기 위해 인입온도와 flow rate를 독립변수로 하고 분말식초의 품질특성을 나타내는 수분, 산도, 흡습성, 당함량, 열안정성 등을 종속변수로 하여 반응표면분석법을 실시한 결과, 분무공정의 최적조건은 inlet temperature는 19$0^{\circ}C$, flow rate는 550 L/h로 결정할 수 있었다.

• KSBB Journal
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• 제17권1호
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• pp.33-37
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• 2002

PLGA 미립구로부터 G-CSF의 방출 거동 양상을 향상 시키기 위하여 G-CSF를 분자량 5000인 methoxy polyethylene glycol-aldehyde로 PEGylation 시켰다. 대부분의 G-CSF는 mono-PEGylation 되었으며, 이를 SDS-PAGE, HPLC, 및 펩타이드 지도 분석을 통해 확인하였다. W/O/W 방법을 사용하여 G-CSF 및 PEGylated G-CSF의 PLGA 미립구를 제조하였으며, 이때 봉입율은 높은 상태였다. 미립구내로 더 많은 G-CSF를 봉입하기 위하여 액상의 G-CSF 및 PEGylated G-CSF을 농축하였고 native gel과 gel filtration 크로마토 그래피를 통하여 단백질이 안정함을 확인하였다. 이렇게 제조한 PLGA 봉입체의 in vitro 방출 거동을 조사한 결과 PEGylated G-CSF는 native G-CSF에 비하여 더 오랜 시간 동안 방출이 지속되었고 최대 방출량도 증가하였다.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1457-1461
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• 2013

The $Fe_3O_4$-core and Ag-shell ($Fe_3O_4@Ag$ nanoeggs) were prepared through the encapsulation of 3-aminopropyltriethoxysilane-coated magnetite nanoparticle in nano-Ag shell by a simple chemically controlled procedure. The $Fe_3O_4@Ag$ nanoeggs were characterized by scanning electron microscopy, transmission electron microscopy, UV-vis spectrum and superconducting quantum interference device magnetometer, respectively. A detailed analysis is provided of how the hydrolysis and condensation of 3-aminopropyltriethoxysilane and the pH value are vital in fabricating the $Fe_3O_4@Ag$ nanoeggs. The prepared $Fe_3O_4@Ag$ nanoeggs possessed uniform size, improved monodispersity, stability against aggregation and high magnetization, which were utilized for the detection of latent fingerprints deposited onto different surfaces. The experimental results showed that the latent fingerprints developed with the $Fe_3O_4@Ag$ nanoeggs powders exhibited excellent ridge details with minimal background staining.