• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.10
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• pp.851-856
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• 2016

Despite all the recent advances in biodegradable material-based microneedles, the bending and failure (especially buckling) of a biodegradable microneedle during skin tissue insertion remains a major technical hurdle for its large-scale commercialization. A reduction in skin tissue puncture force during microneedle insertion remains an essential issue in successfully developing a biodegradable microneedle. Here, we consider uniaxial and equibiaxial prestrains applied to a skin tissue as mechanophysical stimuli that can reduce the skin tissue puncture force, and investigate the effect of prestrain on the changes in skin tissue puncture force. For a porcine skin tissue similar to that of humans, the skin tissue puncture force of a flat-end microneedle is measured with a z-axis stage equipped with a load cell, which provides a force-time curve during microneedle insertion. The findings of this study lead to a quantitative characterization of the relationship between prestrain and the skin tissue puncture force.

• Restorative Dentistry and Endodontics
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• v.16 no.2
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• pp.85-98
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• 1991

The aim of this study was to investigate the effect of low - power laser used in the medical field for various purposes to suppress pain responses evoked by noxious electrical or mechanical stimuli. After both inferior alveolar nerves and the left anterior digastric muscle of cats under general anesthesia were exposed, a recording electrode for the jaw opening reflex was inserted into the anterior digastric muscle. The right inferior alveolar nerve was dissected under a surgical microscope until the response of the functional single nerve could be evoked by the electrical stimulation of the dental pulp or oral mucosa. The electrical stimulus was applied with a rectangular pulse of 10 ms duration for measuring the threshold intensity of a single nerve fiber in the inferior alveolar nerve which responds to stimulation of dental pulp and oral mucosa. Then a pulse of 1 ms duration was applied for determination of conduction velocity. A noxious mechanical stimulus to the oral mucosa was applied by clamping the receptive field with an arterial clamp. The Ga-As diodide laser(wave length, 904 nm ; frequency, 1,000 Hz) was irradiated to the prepared tooth cavity, inferior alveolar nerve and oral mucosa as a pulse wave of 2 mW for 6 minutes. This was followed by a continuous wave of 15 mW for 3 minutes. The action potential of the nerve and EMG of the digastric muscle evoked by the noxious electrical stimulus and nerve response to noxious mechanical stimulus were compared at intervals of before, immediately after, and at 5, 10, 20, 40, 60 minutes after laser irradiation. The results were as follows: The conduction velocity of the intrapulpal $A{\delta}$- nerve fiber recorded from the inferior alveolar nerve before irradiation had a mean value of $6.68{\pm}2.07m/sec$. The laser irradiation did not affect the conduction velocity of the AS - nerve fiber and did not change the threshold intensity or amplitude of the action potential either. The EMG of the digastric muscle evoked by noxious electrical stimulation to the tooth was not changed by the laser irradiation, whether in latency, threshold intensity or amplitude. The laser irradiated to the receptive field of the oral mucosa which was subjected to noxious stimuli did not affect the amplitude of the action potential or the frequency either.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.429.2-429.2
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• 2014

ZnO nanowire is known as synthesizable and good mechanical properties. And, stimuli-responsive polymer is widely used in the application of tunable sensing device. So, we combined these characteristics to make precise tunable sensing devise. In this work, we investigate the dependence of ZnO nanowire alignment and morphology on si substrate using nanosphere template with various conditions via hydrothermal process. Also, pH-temperature dependant tuning ability of nanostructure was studied. The brief experimental scheme is as follow. First, Zno seed layer was coated on a si wafer ($20{\times}20mm$) by spin coater. And then $1.15{\mu}m$ sized close-packed PS nanospheres were formed on a cleaned si substrate by using gas-liquid-solid interfacial self-assembly method. After that, zinc oxide nanowires were synthesized using hydrothermal method. Before the wire growth, to specify the growth site, heat treatment was performed. Finally, NIPAM(N-Isopropylacrylamide) was coated onto as-fabricated nanostructure and irradiated by UV light to form the PNIPAM network. The morphology, structures and optical properties are investigated by FE-SEM(Field Emission Scanning electron Microscopy), XRD(X-ray diffraction), OM(Optical microscopy), and WCA(water contact angle).

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.3
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• pp.678-684
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• 2009

It was reported that Dipsaci Radix has decrease pain effect on the Complex Region Pain Syndrome(CRPS). the CRPS was induced by unilateral loose occlusion in 4 part of the sciatic nerve of the rats. For the fingding significantly change on CRPS rats were divided into 4 different experimental groups. and each groups were induced CRPS. Experimental group I (control group; n=15), experimental group II (100 mg/kg Dipsaci Radix dieted rats; n=15), experimental group III (300 mg/kg Dipsaci Radix dieted rats; n=15), and experimental group IV(500 mg/kg Dipsaci Radix dieted rats; n=15). The study of Dipsaci Radix concentration was that foot withdrawal threshold to the thermal stimuli(Hot plate test), foot withdrawal threshold to the mechanical stimuli(von Frey's filament) and immunohistochemistry staining that were substance P. Hot plate test and von Frey Filament were increase in experimental group II, III, IV than group I, especially group III was most significantly change than group II and IV in post-hoc(Duncan's multiple range). and In immunohistochemistry observation; group I showed increase in the group II, III, IV. especially group III had the minimal level of the substance P expression while the experimental group II, III. These results suggested that the Dipsaci Radix dieted made the decrease of pain in CRPS.

• Macromolecular Research
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• v.17 no.7
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• pp.528-532
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• 2009

The size and shape of free volume (FV) holes available in membrane materials control the rate of gas diffusion and its permeability. Based on this principle, a segmented, thermo-sensitive polyurethane (TSPU) membrane with functional gate, i.e., the ability to sense and respond to external thermo-stimuli, was synthesized. This smart membrane exhibited close-open characteristics to the size of the FV hole and water vapor permeation and thus can be used as smart food packaging materials. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), positron annihilation lifetimes (PAL) and water vapor permeability (WVP) were used to evaluate how the morphological structure of TSPU and the temperature influence the FV holes size. In DSC and DMA studies, TSPU with a crystalline transition reversible phase showed an obvious phase-separated structure and a phase transition temperature at $53^{\circ}C$ (defined as the switch temperature and used as a functional gate). Moreover, the switch temperature ($T_s$) and the thermal-sensitivity of TSPU remained available after two or three thermal cyclic processes. The PAL study indicated that the FV hole size of TSPU is closely related to the $T_s$. When the temperature varied cyclically from $T_s-10{\circ}C$ to $T_s+10^{\circ}C$, the average radius (R) of the FV holes of the TSPU membrane also shifted cyclically from 0.23 to 0.467 nm, exhibiting an "open-close" feature. As a result, the WVP of the TSPU membrane also shifted cyclically from 4.30 to $8.58\;kg/m^2{\cdot}d$, which produced an "increase-decrease" response to the thermo-stimuli. This phase transition accompanying significant changes in the FV hole size and WVP can be used to develop "smart materials" with functional gates and controllable water vapor permeation, which support the possible applications of TSPU for food packaging.

• The Korean Journal of Physiology
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• v.24 no.2
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• pp.389-402
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• 1990

The physiological characteristics of the neurons receiving the ventral root afferent inputs were investigated in the cat. A total of 70 cells were identified in the lumbosacral spinal cord. All these cells responded only to the C-strength stimulation of the distal stump of cut ventral root and the estimated conduction velocities of the VRA fibers were not faster than 4 m/sec. The majority of them were silent in resting state. For 49 cells, their peripheral receptive fields were characterized. Among them, 25 cells were exclusively excited by VRA inputs, 8 were inhibited and the remaining cells recevied both excitatory and inhibitory VRA inputs. According to the response pattern to the mechanical stimuli applied to their receptive fields, only a fourth of them were typical high threshold cell, a sixth, wide dynamic range cells, while remainings were a rather complex cells. Most of the cells receiving VRA inputs, received only the A ${\delta}-peripheral$ nerve inputs. Intravenous injection of morphine decreased the response of spinal cells to the VRA activation. The responses were abolished completely by counter irritation to the common peroneal nerve with C-strength-low frequency stimuli. These physiological properties of the spinal neurons receiving the VRA inputs are differ in some aspect from the spinal neurons receiving nociceptive inputs from the periphery, but still were consistent with the contention that VRA system might carry nociceptive informations arising from the spinal cord and/or neraby surrounding tissues.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.6
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• pp.603-611
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• 2021

Taste-responsive neurons in the nucleus of the solitary tract (NST), the first gustatory nucleus, often respond to thermal or mechanical stimulation. Alcohol, not a typical taste modality, is a rewarding stimulus. In this study, we aimed to investigate the effects of ethanol (EtOH) and/or temperature as stimuli to the tongue on the activity of taste-responsive neurons in hamster NST. In the first set of experiments, we recorded the activity of 113 gustatory NST neurons in urethane-anesthetized hamsters and evaluated responses to four basic taste stimuli, 25% EtOH, and 40℃ and 4℃ distilled water (dH₂O). Sixty cells responded to 25% EtOH, with most of them also being sucrose sensitive. The response to 25% EtOH was significantly correlated with the sucrose-evoked response. A significant correlation was also observed between sucrose- and 40℃ dH₂O- and between 25% EtOH- and 40℃ dH₂O-evoked firings. In a subset of the cells, we evaluated neuronal activities in response to a series of EtOH concentrations, alone and in combination with 32 mM sucrose (EtOH/Suc) at room temperature (RT, 22℃-23℃), 40℃, and 4℃. Neuronal responses to EtOH at RT and 40℃ increased as the concentrations increased. The firing rates to EtOH/Suc were greater than those to EtOH or sucrose alone. The responses were enhanced when solutions were applied at 40℃ but diminished at 4℃. In summary, EtOH activates most sucrose-responsive NST gustatory cells, and the concomitant presence of sucrose or warm temperatures enhance this response. Our findings may contribute to elucidate the neural mechanisms underlying appetitive alcohol consumption.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1427-1434
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• 2021

In this paper, we propose a psychological state estimation process that computes children's attention and tension in response to training stimuli. Joint attention was adopted as the training stimulus required for behavioral intervention, and the Discrete trial training (DTT) technique was applied as the training protocol. Three types of training stimulation contents are composed to check the user's attention and tension level and provided mounted on a character-shaped tabletop robot. Then, the gaze response to the user's training stimulus is estimated with the vision-based head pose recognition and geometrical calculation model, and the nervous system response is analyzed using the PPG and GSR bio-signals using heart rate variability(HRV) and histogram techniques. Through experiments using robots, it was confirmed that the psychological response of users to training contents on joint attention could be quantified.

• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.126-135
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• 2021

Stimuli-responsive hydrogels are being extensively studied to alter their physiochemical properties in response to external changes such as temperature, pH, light and mechanical stress. This study reports multi-responsive hydrogel having optical change response to external stress. First, we synthesized a novel spiropyran cross-linker successfully by grafting poly(ethylene glycol) diacrylate (PEGDA) on both side of spiropyran and introduced to hydrogel. In the results, the yellow spriopyran structure was conversed to purple merocyaine structure by internal stress during swelling of the hydrogels cross-linked with the SP-PEGDAs. Also, the hydrogel could be visualized the swelling and deswelling process in response to pH, by converting MC and prontonated MC structure.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.5
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• pp.237-243
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• 2004

Glial cells are activated in neuropathy and play a key role in hyperalgesia and allodynia. This study was performed to determine whether minocycline could attenuate heat hyperalgesia and mechanical allodynia, and how glial cell activation and nuclear factor kappa B (NF-kappaB) were regulated by minocycline in a model of chronic constriction of sciatic nerve (CCl). When minocycline (50 mg/kg, oral) was daily administered from 1 day before to 9 days after ligation, heat hyperalgesia and mechanical allodynia were attenuated. Furthermore, when minocycline treatment was initiated 1 or 3 days after ligation, attenuation of the hypersensitive behavior was still robust. However, the effect of attenuation was less when minocycline was started from day 5. In order to elucidate the mechanism of pain attenuation by minocycline, we examined the changes of glia and NF-kappaB, and found that attenuated hyperalgesia and allodynia by minocycline was accompanied by reduced microglial activation. Furthermore, the number of NF-kappaB immunoreactive cells increased after CCI treatment and this increase was attenuated by minocycline. We also observed translocation of NF-kappaB into the nuclei of activated glial cells. These results suggest that minocycline inhibits activation of glial cells and NF-kappaB, thereby attenuating the development of behavioral hypersensitivity to stimuli.