• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.241-242
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• 2006

Spherical glass lenses are used in many optical industries. The curvature, eccentricity and height of a tool affect the surface roughness and curvature of lenses. The purpose of this study is the development and performance of a self-diagnostication ultra-precision lens polishing machine. In this paper, structure analysis is performed to reduce maximum displacement and to maintain outside the resonance region by CATIA V5. A spherical center setting gage is developed to increase accuracy of the manufactured lenses. The surface roughness, curvature and thickness of the manufactured lenses are measured and studied.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.1059-1066
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• 2003

A power generation system are proposed to convert ambient mechanical vibration into electrical energy using cantilever-type piezoelectric materials. The vibration-based power device can be used for self-powered systems without batteries. This paper presents the theoretical analysis for the coupled equations of piezoelectric and structural motions and investigates the dynamic characteristics of the self-power system using transfer function method. The theoretical model is verified by the finite element analysis of the resonance frequency, the dynamic response of the structure and the sensor sensibility. Experimental results measured using a prototype system agrees with the theoretical predictions. The system is shown to produce 2.53㎼ in average. Finally, we perform the optimal design for system variables to maximize output power.

• Analytical Science and Technology
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• v.8 no.4
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• pp.699-705
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• 1995

Monolayers of hypericin, a photodynamic polycyclic quinoidal compound, were prepared at the air-water interface, and were transferred to metal substrates to form Langmuir-Blodgett (LB) monolayers. The structural characteristics of hypericin LB monolayers and self-assembled (SA) monolayers were investigated using surface-enhanced resonance Raman scattering (SERRS) spectroscopy. Both the spectroscopic data and the surface pressure - area (${\pi}-A$) isotherms suggest that hypericin forms ${\pi}-{\pi}$ aggregates that orient vertically to the subphase surface. Whereas the ordering and orientation of control was less effective in SA monolayers, a higher structural regularity was attained in LB systems. The effect of subphase on the structural integrity of the monolayer was also investigated.

• Journal of Korean Vacuum Science & Technology
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• v.2 no.1
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• pp.13-19
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• 1998

We have calculated the electronic structure of impurity atoms in metal host by using the tight binding model in the recursion method. For a self-consistent calculation, we assumed that the effect of impurity introduction was localized only at the impurity site and its neighbours. We calculated the Madelung term by limiting the contribution to Vm of the charge perturbations to the first shell around the impurity with Evjen technique. The calculated local density of states and charge transfer values have been compared with the experimental values for a single impurity in metal host. We fund that d-reso-nance state came from the repulsive interaction between impurity d-state and host band, and the position of d-resonance state depended on the difference of valence electrons between the host and the impurity. the results also showed that the charge transfer value between an impurity and host metal was comparable to the ionicity difference between them.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.15-19
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• 2006

A ferredoxin adsorbed hetero self-assembled layer was fabricated on chemically modified Au substrate, 4-Aminothiophenol (4-ATP) was deposited onto Au substrate and then N-succinimidyl-3-[2-pyridyldithio] propionate (SPDP) was adsorbed on the 4-ATP layer, since SPDP was used as a bridging molecule for ferredoxin adsorption, Ferredoxin/SPDP/4-ATP structured hetero layer was constructed because of strong chemical binding of ferredoxin, SPDP, and 4-ATP, The surface of the ferredoxin-adsorbed SPDP/4-ATP layer was observed by scanning tunneling microscopy, The hetero film formation was verified by surface plasmon resonance measurement. The current flow and rectifying property based on the scanning tunneling spectroscopy I-V characteristics was achieved in the proposed hetero layer. Thus, the hetero layer structure of ferredoxin functioned as a molecular diode with rectifying property, The proposed molecular diode can be usefully applied for the development of molecular scale electronic devices.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.264-266
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• 2005

Recently, on-line diagnosis methods through wired and wireless networks are widely adopted in the diagnosis of industrial Electric Facilities, such as generators, transformers and motors. Also smart sensors which includes sensors, signal conditioning circuits and micro-controller in one board are widely studied in the field of condition monitoring. This paper suggests an self-powered system suitable for condition-monitoring smart sensors, which uses parasitic vibrations of the facilities as energy source. First, vibration-driven noise patterns of the electric facilities are presented. And then, an electromagnetic generator which uses mechanical mass-spring vibration resonance are suggested and designed. Finally energy consumption of the presented smart sensor, which consists of MEMS vibration sensors, signal conditioning circuits, a low-power consumption micro-controller, and a ZIGBEE wireless tranceiver, are presented. The usefulness and limits of the presented electromagnetic generators in the field of electric facility monitoring are also suggested.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.211-211
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• 2011

Nanostructures, with a diversity of shapes, built on substrates have been developed within many research areas. Lithography is one powerful, but complex, technique to make structures at the nanometer scale, such as platinum nanowires for studying CO catalytic reactions [1], or aluminum nanodisks for studying the plasmon effect [2]. In this work, we approach a facile method to construct nanostructures using noble metals on a titania thin film by using self-assembled structures as a pattern. Here, a large-scale silica monolayer is transferred to the titania thin film substrates using a Langmuir-Blodgett trough, followed by the deposition of a thin transition metal layer. Owing to the hexagonal close-packed structure of the silica monolayer, we would obtain a metal nanostructure that includes separated metallic triangles (islands) after removing the patterning silica beads. This nanostructure can be employed to investigate the role of metal-oxide interfaces in CO catalytic reactions by changing the patterning silica particles with different sizes or by replacing the oxide support. The morphology and chemical composition of the structure can be characterized by scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. In addition, we modify these islands to a connected island structure by reducing the silica size of the patterning monolayer, which is utilized to generating hot electron flow based on the localized surface plasmon resonance effect of the metal nanostructures.

• Macromolecular Research
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• v.15 no.7
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• pp.633-639
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• 2007

A variety of NMR techniques were applied to the micro-chemical structural characterization of polyanilines prepared via an efficient synthetic method in a self-stabilized dispersion medium in which the polymerization was conducted in a heterogeneous organic/aqueous biphasic system without any stabilizers. Here, the monomer and growing polymer chain were shown to function simultaneously as a stabilizer, imparting compatibility for the dispersion of the organic phase, and as a form of flexible template in an aqueous reaction medium. Polymerizations predicated on this concept generated polyanilines with a low defect content: solution state $^{13}C-NMR$ and solid $^{13}CDD/CP/MAS$ spectroscopy indicated that the synthesized HCPANi and its soluble derivative, HCPANi-t-BOC, evidenced distinctly different NMR spectra with fewer side peaks, as compared to conventionally prepared PANis, and the complete structural assignments of the observed NMR peaks could be determined via the combination of both 1D and 2D techniques. Ortho-linked defects in HCPANi were estimated to be as low as 7%, as shown by a comparison of the integration of the carbonyl carbon resonance peaks.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.4
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• pp.77-87
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• 2023

PURPOSE: The purpose of this study was to investigate the changes in the flexibility and elasticity of the muscles when the hamstrings were stretched in one direction and when they were stretched in three directions. METHODS: In this study the subjects were divided into two groups, namely the 'one-direction stretching exercise of the hamstring muscle in the neutral position' group (female: 14 people, male: 14 people) and the 'three-way stretching exercise' group (female: 12 people, male: 14 people) considering the positions of the three hamstring muscles. The elasticity and flexibility of the hamstring muscles were measured before and after the self-extension exercise, and the average value of two measurements was noted. To evaluate the flexibility of the hamstring muscle, a 'sit and reach' test was performed, and muscle elasticity was measured using the MyotonPRO® device. RESULTS: After the stretching exercise, flexibility increased in both groups. In terms of muscle elasticity, the body dynamic strength and resonance frequency of the stretching one-direction stretching group decreased after the stretching exercise. CONCLUSION: To alter the muscle characteristics and increase the flexibility when performing a stretching exercise, selecting and stretching only one muscle with the lowest range of motion yields effective results. The ideal technique to be employed appears to be to stretch the entire hamstring muscle in one direction from the neutral position.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.12
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• pp.1064-1071
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• 2015

In this paper, the electrical characteristics of interdigital capacitor with single-layer and multi-layer graphene were compared and analyzed in the microwave region. In equivalent circuit, a capacitor coupled with graphene showed the clear difference in electrical components such as resistance, inductance, and capacitance. In particular, for the capacitor with single-layer graphene, additional inductance and resistance occurred and the electrode resistance was also increased. Meanwhile, the self-resonance frequency of capacitor was shifted toward lower frequency region and its transmitted characteristic was considerably improved at frequency ranging from 0.4 to 4 GHz. The electrical characteristics of the capacitor with multi-layer graphene were somewhat different than the bare capacitor. In conclusion, we could confirm that single-layer graphene greatly influenced the electrical characteristics and performances of interdigital capacitor compared to multi-layer graphene.