• Journal of Biomedical Engineering Research
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• v.37 no.4
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• pp.147-151
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• 2016

Tibial defect, or fracture is very routine musculoskeletal case which brings fully uncomfortable and painful situations to patient. Moreover, it has long hospitalization period because of its risk of non-union. There are many studies using ultrasound, vibration, and laser for bone regeneration to figure out fast bone healing. Among them, Low Level Laser Therapy (LLLT) is already known that it is very easy to treat and may have positive effect for bone regeneration. However, LLLT has uncertain energy dose because of scattering and absorption of laser in tissue. In this study, we used interstitial LLLT to treat tibial defect in animal study. The Interstitial LLLT can overcome some limitations caused by laser scattering or absorption in tissue medium. The results were evaluated using u-CT which can calculate X-ray attenuation coefficient and bone volume of bone defect area. These results showed that interstitial LLLT may affect fast bone healing process in early phase.

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.155-156
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• 2007

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.155-156
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• 2008

• Proceedings of the Optical Society of Korea Conference
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• 2006.02a
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• pp.359-360
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• 2006

Functional photoacoustic tomography is a new non-invasive imaging modality, and it is emerging as a very practical method for imaging biological tissue structures by means of laser-induced ultrasound. Structures with high optical absorption, such as blood vessels, can be imaged with the spatial resolution of ultrasound, which is not limited by the strong light scattering in biological tissues. By varying wavelengths of the laser light and acquiring photoacoustic images, optical absorption spectrum of each image pixel is found. Since the biochemical constituents of tissues determine the spectrum, useful functional information like oxygen saturation ($SO_2$) and total haemoglobin concentration (HbT) can be extracted. In this study, as a proof-of-principle experiment, hypoxic brain tumor vasculature and traumatic brain injury (TBI) of small animal brain are imaged with functional photoacoustic tomography. High resolution brain vasculature images of oxygen saturation and total hemoglobin concentration are provided to visualize hypoxic tumor vasculature, and hemorrhage on the cortex surface by the TBI.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.369-369
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• 2016

A nanostructure composite is a highly suitable substance for photoacoustic ultrasound generation. This allows an input laser beam (typically, nanosecond pulse duration) to be efficiently converted to an ultrasonic output with tens-of-MHz frequency. This type of energy converter has been demonstrated by using a carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite film that exhibit high optical absorption, rapid heat transition, and mechanical durability, all of which are necessary properties for high-amplitude ultrasound generation. In order to develop the CNT-PDMS composite film, a high-temperature chemical vapor deposition (HTCVD) method has been commonly used so far to grow CNT and then produce a CNT-PDMS composite structure. Here, instead of the complex HTCVD, we use a mixed solution of hydrophobic multi-walled CNT and dimethylformamid (DMF) and fabricate a solution-processed CNT-PDMS composite film over a spherically concave substrate, i.e. a focal energy converter. As the solution process can be applied over a large area, we could easily fabricate the focal transmitter that focuses the photoacoustic output at the moment of generation from the CNT-PDMS composite layer. With this method, we developed photoacoustic energy converters with a large diameter (>25 mm) and a long focal length (several cm). The lens performance was characterized in terms of output pressure amplitude for an incident pulsed laser energy and focal spot dimension in both lateral and axial. Due to the long focal length, we expect that the new lens can be applied for long-range ultrasonic treatment, e.g. biomedical therapy.

• Journal of Oral Medicine and Pain
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• v.30 no.4
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• pp.401-410
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• 2005

The purpose of this study was to assess the effect of heat therapy on cutaneous blood flow and skin temperature at pre-auricular region. Moist heat therapy and ultrasound therapy were applied to 20 healthy subjects(male: 10, female: 10). Cutaneous blood flow and skin temperature before and after heat therapy were measured with laser doppler flowmetry and thermocouple. The results were as follows ; 1. Cutaneous blood flow and skin temperature were significantly increased after moist heat therapy and ultrasound therapy. 2. In application of moist heat therapy, cutaneous blood flow and skin temperature were more increased and maintained longer than in ultrasound therapy. 3. Before heat therapy, cutaneous blood flow and skin temperature were higher in male. 4. There was no significant gender difference in changes of cutaneous blood flow and skin temperature after heat therapy. In conclusion, both moist heat therapy and ultrasound therapy increased cutaneous blood flow and skin temperature significantly, and moist heat therapy was more effective to increase cutaneous blood flow and skin temperature and to maintain increased cutaneous blood flow and skin temperature. There was no significant gender difference in the effect of heat therapy on cutaneous blood flow and skin temperature.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.4
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• pp.388-392
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• 2012

This study proposes a fully non-contact measurement method to assess acoustic nonlinearity of narrowband surface waves generated by a line-arrayed laser beam by using a laser-ultrasonic detector in the way of two-wave mixing (TWM) method. This method was applied to figure out a relationship between plastic deformation and nonlinearity characteristics of a plastically deformed aluminum specimens. The experimental results showed that the acoustic nonlinearity of the laser-generated surface wave increased proportionally to the level of tensile deformation. This tendency is in good agreement with the result of measurement by contact method with PZT-transducer.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.377-377
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• 2016

Under nanosecond-pulsed laser irradiation, light-absorbing thin films have been used for photoacoustic transmitters for ultrasound generation. Especially, nanostructured absorbers are attractive due to high optical absorption and efficient thermoacoustic energy conversion: for example, 2-dimensional (2-D) gold nanostructure array, synthetic gold nanoparticles, carbon nanotubes (CNTs), and reduced graphene oxides. Among them, CNT has been used to fabricate a composite film with polydimethylsiloxane (PDMS) that exhibits excellent photoacoustic conversion performance for high-frequency, high-amplitude ultrasound generation. Previously, CNT-PDMS nanocomposite films were made by using a high-temperature chemical vapor deposition (HTCVD) process for CNT growth. However, this approach is not suitable to fabricate large-area CNT films (>several cm2). This is because a chamber dimension of HTCVD is limited and also the process often causes nonuniform CNT growth when the film area increases. As an alternative approach, a solution-based process can be used to overcome these issues. We develop PDMS composite transmitters, based on the solution process, using several nanostructured light-absorbers such as CNTs, nanoink powders, and imprinted regular arrays of gold nanostructure. We compare fabrication processes of each composite transmitters and photoacoustic output performance.

• Medical Lasers
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• v.8 no.1
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• pp.35-38
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• 2019

Thread-lifting is a minimally invasive procedure that shows good results and fewer complications as compared with those results and complications of standard surgery. Many procedures and techniques have been developed to create a younger appearance of facial/neck skin for aging people, and the demand for an improved aesthetic appearance is increasing. Since the incidence of side effects is much less than that of non-absorbable threads, which can lead to complications such as foreign body reactions, polydioxanone (PDO) threads are predominantly used for face lift procedures. A 66-year-old woman presented to our clinic with inflamed palpable masses. She had undergone a face lift with absorbable threads in our clinic 5 months previously. Excisional biopsy was performed with the patient under local anesthesia. During the operation, any threads were not detected and there was both fibrotic scar tissue and granulomatous tissue. For effectively promoting healing and managing the scars, treatment with LDM^®-MED was performed on the day after surgery. The treatment was performed according to the author's protocol. Although foreign body granuloma as a complication after using non-absorbable thread types have been previously reported, it is relatively rare to find this type of complication after using absorbable thread. In this report, we present a case in which a 66-year-old female with foreign body granuloma after undergoing a face lift using absorbable threads was treated with the application of dual-frequency ultrasound, which promoted wound healing.

• Journal of the Korean Society for Nondestructive Testing
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• v.25 no.2
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• pp.95-102
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• 2005

There are many tube and pipeline in nuclear power plant under high temperature and high pressure. Erosion and corrosion defects were expected on these tube and pipe-line by environmental and mechanical factors. These erosion and corrosion defects ran be evaluated by ultrasonic technique. In these study, Scanning Laser Source(SLS) technique was applied to detect defect and construct image. This technique also makes detection possible on rough and curved surfaces such as tube and pipe-line by scanning. Conventional ultrasonic scanning technique requires immersion of specimen or water jet for transferring ultrasonic wave between transducer and specimen. However, this SLS technique does not need contacting and couplant to generate surface wave and to get flaw images. Therefore, this SLS technique has several advantages, for complicated production inspection, non-contact, remote from specimen, and high resolution. In this study, SLS images were obtained with various conditions of generation laser ultrasound and receiving in order to enhance detectability of flaws on the tube. Stress corrosion cracks were produced on tube and images of stress corrosion cracks were constructed by using SLS technique.