• Journal of the Korean Society for Nondestructive Testing
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• 제32권4호
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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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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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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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• 제8권1호
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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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• 제25권2호
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• pp.103-109
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• 2005

Fiber reinforced plastic material should be inspected in fabrication process in order to enhance quality by prevent defects such as delamination and void. Generally, ultrasonic technique is widely used to evaluate FRP. In conventional ultrasonic techniques, transducer should be contacted on FRP. However, conventional contacting method could not be applied in fabrication process and novel non-contact evaluating technique was required. Laser-based ultrasonic technique was tried to evaluate CFRP plate. Laser-based ultrasonic waves propagated on CFRP were received with various transducers such as accelerometer and AE sensor in order to evaluate the properties of waves due to the variation of frequency. Velocities of laser-based ultrasonic waves were evaluated for various fiber orientation. In addition, laser interferometry was used to receive ultrasonic wave in CFRP and frequency was analysed.

• Smart Structures and Systems
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• 제26권5호
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• pp.657-666
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• 2020

A rotational pulse-echo ultrasonic propagation imager that can inspect cylindrical specimens for material nondestructive evaluations is proposed herein. In this system, a laser-generated ultrasonic bulk wave is used for inspection, which enables a clear visualization of subsurface defects with a precise reproduction of the damage shape and size. The ultrasonic waves are generated by a Q-switched laser that impinges on the outer surface of the specimen walls. The generated waves travel through the walls and their echo is detected by a Laser Doppler Vibrometer (LDV) at the same point. To obtain the optimal Signal-to-Noise Ratio (SNR) of the measured signal, the LDV requires the sensed surface to be at a right angle to the laser beam and at a predefined constant standoff distance from the laser head. For flat specimens, these constraints can be easily satisfied by performing a raster scan using a dual-axis linear stage. However, this arrangement cannot be used for cylindrical specimens owing to their curved nature. To inspect the cylindrical specimens, a circular scan technology is newly proposed for pulse-echo laser ultrasound. A rotational stage is coupled with a single-axis linear stage to inspect the desired area of the specimen. This system arrangement ensures that the standoff distance and beam incidence angle are maintained while the cylindrical specimen is being inspected. This enables the inspection of a curved specimen while maintaining the optimal SNR. The measurement result is displayed in parallel with the on-going inspection. The inspection data used in scanning are mapped from rotational coordinates to linear coordinates for visualization and post-processing of results. A graphical user interface software is implemented in C++ using a QT framework and controls all the individual blocks of the system and implements the necessary image processing, scan calculations, data acquisition, signal processing and result visualization.

• Journal of the Korean Society for Nondestructive Testing
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• 제25권2호
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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.

• Medical Lasers
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• 제10권3호
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• pp.161-169
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• 2021

Background and Objectives Fractional microneedle radiofrequency systems are popular options to increase elasticity in aging skin. Laser-assisted drug delivery is a promising method for the epidermal injection of topically applied drugs and cosmetic ingredients. This study assesses the safety and efficacy of topical delivery of L-ascorbic acid, vitamin E, and ferulic acid after fractional microneedle radiofrequency treatment for reducing photodamage. Materials and Methods In this prospective, single-center, split-face, controlled pilot study, six women (mean age, 48.0 years; range, 35-57 years; Fitzpatrick skin types III and IV) exhibiting mild to moderate photodamage, underwent a single session of fractional microneedle radiofrequency treatment. The patients were instructed to apply the antioxidant formulation to only one side of the face. Patients were evaluated 3 days, 7 days, and 4 weeks thereafter, using three-dimensional imaging and ultrasound. Ex vivo, the full-thickness human skin was used for molecular and histological evaluation. Statistical analysis was achieved by applying t-tests, Mann-Whitney U tests, and one-way analyses of variance. Results Compared to the untreated side, the antioxidant-treated side exhibited a significant increase in dermal thickness (10.32% vs. 17.54%, p < 0.05), but not in skin elasticity (4.76% vs. 4.69%, p > 0.05). The difference in erythema between the sides was statistically not significant (p > 0.05). In the ex vivo model, expression of FGF2 in the skin was significantly increased after application of the antioxidant formulation, as compared to results obtained subsequent to fractional microneedle radiofrequency treatment only (p < 0.01). Conclusion This study demonstrates that for the treatment of photodamaged skin, laser-assisted delivery of the antioxidant formulation is a safe and effective adjuvant modality following fractional microneedle radiofrequency.

• The Journal of Korean Physical Therapy
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• 제15권4호
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• pp.331-372
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• 2003

The purpose of study was to evaluate effects of low-intensity ultrasound and laser on healing of bone fracture. Twenty fracture patient were selected for this study(fourteen males, six females. mean aged 44.8) fracture area was humerus, tibia, forearm bones. The obtain result are as follows. 1. The result of this study were following that pain score was significantly reduced pre intervention compared with post intervention in male(P<.001). 2. The result of this study were following that pain score was significantly reduced pre intervention compared with post intervention in female(P<.001). 1. The result of this study were following that pain score was not appeared reduced pre intervention compared with post intervention in male and female(P<.001). 4. The result of this study were following that pain score was not appeared pre intervention compared with post intervention in male between age(P<.001). 5. The result of this study were following that pain score was not appeared pre intervention compared with post intervention in female between age (P<.001). 6. The result of this study were following that radiologic score was significantly reduced pre intervention compared with post intervention in male(P<.001). 7. The result of this study were following that radiologic score was significantly reduced pre intervention compared with post intervention in female(P<.001). 8. The result of this study were following that radiologic score was not appeared reduced pre intervention compared with post intervention in male and female(P<.001). 9. The result of this study were following that radiologic score was not appeared pre intervention compared with post intervention in male between ages(P<.001). 10. The result of this study were following that radiologic score was not appeared pre intervention compared with post intervention in female between ages(P<.001). 11. The result of this study were following that healing on fracture area was observed that reduced pre intervention compared with post intervention

• Annals of Rehabilitation Medicine
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• 제42권6호
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• pp.846-853
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• 2018

Objective To compare the effects of low intensity ultrasound (LIUS), traditional exercise therapy (TET), low level laser therapy (LLLT) and TET on temporomandibular joint (TMJ) pain and trismus following recovery from head and neck cancer (HNC). Methods Sixty participants following, who had experienced HNC, were randomly allocated to three groups of 20 people each. Each group received different therapy. Group A received LIUS and TET; group B received LLLT and TET; while group C received TET. All 60 participants were evaluated under the visual analog scale (VAS), the University of Washington Quality of Life questionnaire (UW-QOL) and the Vernier caliper scale (VCS) at the beginning of the therapies and after 4 weeks. Results ANOVA test revealed significant improvements across all three groups with outcomes of p<0.05. The results of the UW-QOL questionnaire showed a significant difference between groups A, B and C in favor of group A (p<0.05). The VAS results showed a more improvement in group A as compared to group B (p<0.05), while there was no statistical difference between groups B and C (p>0.05). The VCS results showed more improvement for the individuals in group B as compared to those in group C (p<0.05), while there was minimal difference between groups A and B (p>0.05). Conclusion The LIUS and TET are more effective than LLLT and/or TET in reducing TMJ pain and trismus following HNC.

• Korean Journal of Acupuncture
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• 제40권3호
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• pp.79-89
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• 2023

Objectives : The purpose of this study is to investigate various application methods of focused ultrasound and apply them to clinical use in Korean medicine. Methods : Search was performed using the search engines of electronic databases, including PubMed, ScienceDirect, Cumulative Index to Nursing and Allied Health Literature (CINAHL), ScienceON, Oriental Medicine Advanced Searching Integrated System (OASIS), China National Knowledge Infrastructure (CNKI), Wanfang Data, Japan Science Technology Information Aggregator, Electronic (J-STAGE) and Citation Information by NII (CiNii), from inception to July 2023 without language limitation. Inclusion criteria were clinical studies including randomized controlled trials (RCTs), and animal experimental studies related with focused ultrasound treatments for acupoints or meridian sinews. Results : Total 17 papers, 7 for RCT, 6 for in vivo animal studies, and other experimental studies, were finally selected. Indications used in studies were shoulder pain, back pain, chronic back pain, and degenerative knee arthritis. In experimental studies, studies on animal models of hypoxic ischemic brain damage and hyperlipidemia were also conducted. As for the acupoints, LR3, LI4, and ST36 were used in clinical studies and, in animal experimental studies, GV20, KI1, and ST36 were used. As for the dose, 4 studies below 3 W/cm² and 3 studies in the range of 0.625 to 5 W/cm² in clinical studies, and all studies did not exceed 5 W/cm². In animal experimental studies, 0.5 W/cm², 2 W/cm², 7.5 WW/cm², 15 W/cm², 10~20 W/cm² were used. In all three studies describing the penetration depth during irradiation, it was less than 1 cm. Conclusions : We suggest that focused ultrasound is an appropriate treatment tool for stimulating the acupoints to transfer heat energy. Future studies with rigorous and well-designed RCTs for various diseases will be required to ascertain the focused ultrasound stimulate acupoints or meridian sinews.