• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.252-257
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• 2004

Nanometer-sized structures are being applied to many devices including micro/nano electronics, optoelectronics, quantum devices, MEMS/NEMS, biosensors, etc. Especially, the thin film with submicron thickness is a basic structure for fabricating these devices, but its mechanical behaviors are not well understood. The mechanical properties of the thin film are different from those of the bulk structure and are difficult to measure because of its handling inconvenience. Several techniques have been applied to mechanical characterization of the thin film, such as nanoindentation test, micro/nano tensile test, strip bending test, etc. In this study, we focus on the strip bending test because of its high accuracy and moderate specimen preparation efforts, and measure Au thin film, which is a very popular material in micro/nano electronic devices. Au film is deposited on Si substrate by evaporation process, of which thickness is 100nm. Using the strip bending test, we obtain elastic modulus, yield and ultimate tensile strength, and residual stress of Au thin film.

• Biomaterials and Biomechanics in Bioengineering
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• 제3권1호
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• pp.59-69
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• 2016

A surface resisting protein adsorption and cell adhesion is highly desirable for many biomedical applications such as diagnostic devices, biosensors and blood-contacting devices. In this study, a surface conjugated with sulfobetaine molecules was fabricated via the click reaction for the anti-fouling purpose. An alkyne-containing substrate (Alkyne-PPX) was generated by chemical vapor deposition of 4-ethynyl-[2,2]paracyclophane. Azide-ended mono-sulfobetaine molecules were synthesized and then conjugated on Alkyne-PPX via the click reaction. The protein adsorption from 10% serum was reduced by 57%, while the attachment of L929 cells was reduced by 83% onto the sulfobetaine-PPX surface compared to the protein adsorption and cell adhesion on Alkyne-PPX. In conclusion, we demonstrate that conjugation of mono-sulfobetaine molecules via the click chemistry is an effective way for reduction of non-specific protein adsorption and cell attachment.

• Journal of Dairy Science and Biotechnology
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• 제29권2호
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• pp.43-49
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• 2011

The increasing number of analytes in concern and the alarming health and environmental consequences have required effective means of monitoring for safety control. Biosensors offer advantages as alternatives to conventional analytical methods because of their inherent specificity, simplicity, and quick response. Colorimetric biosensor, one of biosensor group, is one of the easiest and the most convenient methods because detection can be done using naked eye. Recently, a novel method for rapid detection and read-out of specific immunoassays with naked eye using polydiacetylene (PDA) was developed. Polydiacetylene has recently been in the limelight as a transducing materials because of its special features that allow optical transduction of sensory signals and inherent simplicity and ease of use in supramolecular chemistry. Various forms of PDA are used as a sensor platform for detection of various biological analytes such as viruses, DNA, proteins, bacteria and hazardous molecules.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.49-49
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• 2010

Nanopiezotronics is an emerging area of nanotechnology with a variety of applications that include piezoelectric field-effect transistors and diodes, self-powered nanogenerators and biosystems, and wireless nano/biosensors. By exploiting coupled piezoelectric and semiconducting characteristics, it is possible for nanowires, nanobelts, or nanorods to generate rectifying current and potential under external mechanical energies such as body movement (handling, winding, pushing, and bending) and muscle stretching, vibrations (acoustic and ultrasonic waves), and hydraulic forces (body fluid and blood flow). Fully transparent, flexible (TF) nanogenerators that are operated by external mechanical forces will be presented. By controlling the density of the seed layer for ZnO nanorod growth, transparent ZnO nanorod arrays were grown on ITO/PES films, and a TF conductive electrode was stacked on the ZnO nanorods. The resulting integrated TF nanodevice (having transparency exceeding 70 %) generated a noticeable current when it was pushed by application of an external load. The output current density was clearly dependent on the force applied. Furthermore, the output current density depended strongly on the morphology and the work function of the top electrode. ZnO nanorod-based nanogenerators with a PdAu, ITO, CNT, and graphene top electrodes gave output current densities of approximately $1-10\;uA/cm^2$ at a load of 0.9 kgf. Our results suggest that our TF nanogenerators are suitable for self-powered TF device applications such as flexible self-powered touch sensors, wearable artificial skins, fully rollable display mobile devices, and battery supplements for wearable cellular phones.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.278.1-278.1
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• 2013

Among the prerequisites for stable neural interfacing are the long-term stability of electrical performance of and the excellent biocompatibility of conducting materials in implantable neural electrodes. Reduced graphene oxide offers a great potential for a variety of biomedical applications including biosensors and, particularly, neural interfaces due to its superb material properties such as high electrical conductivity, decent optical transparency, facile processibility, and etc. Nonetheless, there have been few systematic studies on the graphene-based neural interfaces in terms of biocompatibility of electrode materials and long term stability in electrical characteristics. In this research, we prepared the primary culture of rat hippocampal neurons directly on reduced graphene oxide films which is chosen as a model electrode material for the neural electrode. We observed that the viability of primary neuronal culture on the present structure is minimally affected by nanoscale graphene flakes below. These results implicate that the multilayer films of reduced graphene oxides can be utilized for the next-generation neural interfaces with decent biocompatibility and outstanding electrical performance.

• 한국재료학회지
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• 제26권2호
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• pp.100-108
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• 2016

Zinc Sulfide (ZnS) is one of the II-VI semiconducting materials, having novel fundamental properties and diverse areas of application such as light-emitting diodes (LEDs), electroluminescence, flat panel displays, infrared windows, catalyst, chemical sensors, biosensors, lasers and biodevices, etc. However, despite the remarkable versatility and prospective potential of ZnS, research and development (R&D) into its applications has not been performed in much detail relative to research into other inorganic semiconductors. In this study, based on global patent information, we analyzed recent technical trends and the current status of R&D into ZnS applications. Furthermore, we provided new technical insight into ZnS applicable fields using in-depth analysis. Especially, this report suggests that ZnS, due to its infrared-transmitting optical property, is a promising material in astronomy and military fields for lenses of infrared systems. The patent information analysis in this report will be utilized in the process of identifying the current positioning of technology and the direction of future R&D.

• 공업화학
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• 제27권2호
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• pp.185-189
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• 2016

많은 생체 친화적인 센서들 중에서 avidin-biotin system은 높은 상호 특이적인 친화성으로 인하여 많은 생물학적인 응용 연구에 이용되어 왔다. 효과적인 avidin-biotin 바이오센서 개발을 위해 avidin-biotin 간의 상호 반응성을 증대시키기 위해서는 높은 표면적을 가지는 전극이 필요하다. 본 연구에서는 이러한 목적을 위해 gold nanorods electrode를 사용하였다. 전기화학적인 특성은 cyclic voltammetry (CV)와 electrochemical impedance spectroscopy (EIS)를 가지고 redox couple $[Fe(CN)_6]^{3-/4-}$를 사용하여 다양한 biotin의 농도에 따라 분석되었다. 결론적으로 nanorod의 전극은 1 ng/mL보다 낮은 biotin의 농도도 감지할 수 있음을 보였다.

• BioChip Journal
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• 제12권4호
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• pp.268-279
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• 2018

Flower-shaped organic-inorganic hybrid nanostructures, termed nanoflowers, have received considerable recent attention as they possess greatly enhanced activity, stability, durability, and even selectivity of entrapped organic biomolecules, which are much better than those from the conventional methods. They can be synthesized simply via co-incubation of organic and inorganic components in aqueous buffer at room temperature and yield hierarchical nanostructures with large surface-to-volume ratios, allowing for low-cost production by easy scale-up, as well as the high loading capacity of biomolecules without severe mass transfer limitations. Since a pioneering study reported on hybrid nanoflowers prepared with protein and copper sulfate, many other organic and inorganic components, which endow nanoflowers with diverse functionalities, have been employed. Thanks to these features, they have been applied in a diverse range of areas, including biosensors and biocatalysis. To highlight the progress of research on organic-inorganic hybrid nanoflowers, this review discusses their synthetic methods and mechanisms, structural and biological characteristics, as well as recent representative applications. Current challenges and future directions toward the design and development of multi-functional nanoflowers for their widespread utilization in biotechnology are also discussed.

• 한국동물생명공학회지
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• 제36권1호
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• pp.45-50
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• 2021

In recent years, various methods of measuring body temperature have been developed using wireless biosensors to facilitate an early detection of pregnancy and parturition in cows. However, there are no studies on real-time monitoring of cattle body temperature throughout pregnancy. Therefore, we investigated the daily mean ruminal temperature in pregnant cows throughout pregnancy using a ruminal bio-capsule sensor and then evaluated the temperature variation between pregnant and non-pregnant cows. In pregnant cows, the mean and standard deviation of ruminal temperature was 38.86 ± 0.17℃. Ruminal temperature in pregnant cows slowly decreased until 180 to 190 days after artificial insemination and after that, the temperature increased dramatically until just before parturition. Furthermore, the means ruminal temperature was significantly different between pregnant and nonpregnant cows. The mean and standard deviation of ruminal temperature were as follows: 38.68 ± 0.01℃ from days 80 to 100, 38.78 ± 0.02℃ from days 145 to 165, 38.99 ± 0.45℃ from days 200 to 220, 39.14 ± 0.38℃ from days 250 to 270 before parturition. Therefore, our results could provide useful data for early detection of pregnancy and parturition in Korean cows.

• Bulletin of the Korean Chemical Society
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• 제22권2호
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• pp.194-198
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• 2001

In order to look for polymeric materials applicable to the oxygen electrode membranes of biosensors, polyurethanes (PUs) were synthesized from poly(butylene succinate) diol (Mn 1150), poly(ethylene glycol) (Mn 200), and 4,4'-methylenebis(cyclohexyl isocyanate). The PUs (Mn 15000-100000) underwent the crystallization and melting transitions in the temperature range of 20-30 $^{\circ}C$ and 90-110 $^{\circ}C$, respectively. The oxygen permeability for the PU membranes prepared by the solution casting method could not be measured since oxygen simply leaked through the membranes with an audible noise. However, when the PUs were blended with carboxylated poly(vinyl chloride) (CPVC), the permeability could be measured. The oxygen permeability coefficient (Po2) of the PU/CPVC $(96}4)$ membranes (6.4 Barrer) was high enough for the application as the electrode membranes. The Po2 decreased dramatically when the CPVC content increased from 4 to 5 wt%, but decreased very slowly and approached to that of CPVC (~0.26 Barrer) when the CPVC content increased further. The scanning electron micrographs of the membranes revealed that the PU membranes were composed of large crystal grains with many pores, but the size of the PU crystal grains and pores decreased progressively with increasing the CPVC content.