• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.3039-3045
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• 2013

Dual-frequency ultrasound assisted photocatalysis (DUAP) method was proposed to degrade a stable organic model effluent, cresol red (CR), using the prepared $Fe^{3+}$-doped $TiO_2$ with active carbon fiber loading ($Fe^{3+}-TiO_2/ACF$) as photocatalyst. The influence of key factors, including Fe doping amount and power density of dual-frequency ultrasounds (20/40 kHz), on the degradation efficiency was investigated. The degradation efficiency rises to 98.7% in 60 min accompanied by the color removal of CR liquid samples from yellow to colorless transparent at optimal conditions. A synergy index of 1.40 was yielded by comparison with single ultrasound assisted photocatalysis (SUAP) and the photocatalysis without ultrasound assisted (UV/$TiO_2$), indicating that a clear synergistic effect exists for the DUAP process. Obvious enhancement of degradation efficiency for the DUAP process should be attributed to production of large amount of free radicals by strong cavitational effects of dual ultrasounds.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.211-218
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• 2007

The objectives of this study have been carried out to investigate the solubilization of municipal sewage sludge by single and dual frequency ultrasonic pretreatment, and the methane production characteristics of pretreated sewage sludge by specific methanogenic activity test for sewage sludge reduction. The waste activated sludge was collected from thickened tank of Suyoung sewage treatment plant in Busan city, and its concentration was adjusted to 1.0% total solids. Ultrasonic frequency was varied 15, 20, 15+20 kHz, and acoustic density was used a maximum 176W/L. The dual frequency ultrasonic pretreatment was found to be more effective than single frequency ultrasonic in the solubilization rate and methane production. The $SCOD_{Cr}/TCOD_{Cr}$, rate were 15.2%, 13.9%, 17.0% with single frequency of 15 kH2, 20 kHz, dual frequency of 15+20 kHz, respectively. The application of dual frequency ultrasound for sewage sludge pretreatment can be interest for sewage treatment plants having problems in sludge treatment and disposal.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.271-279
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• 2022

Functional cosmetics containing various ingredients that improve skin health are currently being developed. In addition, technologies that help increase the absorption rate of such cosmetics have recently gained significant attention. Sonophoresis is a method to increase the transdermal absorption of cosmetics using ultrasound. A skin-mimicking phantom was fabricated using polydimethylsiloxane, Strat-M^TM membrane, and thermochromic pigments. Gel-type cosmetics used in skin mask packs and epidermal-growth-factor-based nano-cosmetics were tested for their absorption rates at ultrasound frequencies of 1, 3, and 10 MHz in the single frequency mode, and 1/3 and 3/10 MHz in the dual frequency mode. The gel-type cosmetics and epidermal-grow-factor-based nano-cosmetics showed the highest absorption rate at 3/10MHz dual frequency. The size of the cosmetic particles decreased by 5-9 %. Furthermore, the temperature rise caused by ultrasound could be visually recognized by the thermochromic pigment in the phantom turning white. We presented a skin-mimicking phantom. The device can be customized according to the size of the ultrasound probe and has the advantage of quantitatively evaluating the transdermal permeability of cosmetics at a low cost. The development of the skin-mimicking phantom will be useful for determining the suitable conditions required to increase the absorption rate of cosmetics using ultrasound.

• 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 Korean Society of Environmental Engineers
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• v.28 no.2
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• pp.207-215
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• 2006

This study evaluated the effect of ultrasonic irradiation on reducing membrane fouling for the treatment of chemically treated leachate and biologically treated leachate. The experiments on improvement of membrane flux according to the membrane types(MF and UF) and membrane materials were performed with changing frequency(40 kHz and 120 kHz) and intensity(200 W and 400 W) of ultrasound in ultrasonic membrane separation apparatus which ultrasound can be periodically irradiated. Additionally, the effect of dual frequency ultrasound which 40 kHz md 120 kHz are irradiated simultaneously was evaluated. The improvement of membrane flux by periodical ultrasound irradiation was higher in microfiltration(MF) membrane than in ultrafiltration(UF) membrane. It was sustained more in the MF membrane of polyvinylidene fluoride(PVDF) than in that of polysulfon(PS). Ultrasonic improvement of membrane flux was different depending on the characteristics of target wastewater. It was sustainably maintained without reclogging using dual frequency ultrasound although the improvement of membrane flux was lower.

• Advances in nano research
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• v.2 no.2
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• pp.121-133
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• 2014

Polymer nanocomposites are advanced nanomaterials which exhibit dramatic improvements in various mechanical, thermal and barrier properties as compared with the neat polymer. Polystyrene/ alumina nanocomposites were prepared by an ultrasound-assisted solution casting method at filler loadings ranging from 0.2 to 2% and also at different ultrasonic frequencies, viz. 58 kHz, 192/58 kHz, 430 kHz, 470 kHz and 1 MHz. The composites were subjected to mechanical property tests (tensile and impact tests) and cavitation erosion tests to study the enhancement in functional properties. Filler dispersion in the polymer matrix was observed by SEM analysis. The effect of frequency on filler dispersion in the matrix was studied by SEM analysis and functional property enhancement of the composite material. The composites prepared at dual (high/ low) frequency (192/58 kHz) were found to show better property enhancement at low filler loadings as compared with neat polymer and also with composites prepared without ultrasound, thus reinforcing the finding that ultrasound-assisted synthesis is a promising method for the synthesis of nanocomposites.

• Medical Lasers
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• v.8 no.2
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• pp.80-83
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• 2019

Necrobiosis lipoidica (NL) is a rare, idiopathic, chronic granulomatous inflammatory disease of collagen degeneration with the risk of ulceration. Many procedures have been proposed to treat this rare disease. In this study, we applied LDM^®-MED for the management of NL, and this condition in our patient was chronic and refractory to other therapeutic options. To the best of our knowledge, no study has explored treatment of NL using ultrasound. Our results suggest that application of LDM^®-MED seems to be an effective treatment option for NL. Long-term and systematic studies are needed to determine whether such application of LDM^®-MED will be an innovative and effective treatment option for NL and various kinds of chronic wounds.

• Progress in Medical Physics
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• v.18 no.3
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• pp.172-178
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• 2007

An ultrasonic bone densitometer has been developed by measuring speed of sound signal transmitted and received on the skin, not through the horizontal axis but through the vertical one in tissue. The SOS(speed of sound) method measuring the time difference between the ultrasound signals reflected from the both sides of surface of bone could produce more precise result compared with the BUA(broadband ultrasound attenuation) method measuring the frequency difference. Middle finger is selected to be the best measurement position in order to increase the accuracy, after due consideration that the thickness of flesh at the down part of thumb shows too much variation although the ratio of the receiving signal is higher than the other fingers. The measured value by using SOS method shows almost the same result as compared with the conventional DEXA method.

• 전자공학회논문지 IE
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• v.49 no.2
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• pp.18-23
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• 2012

A method to determine the equivalent circuits of broadband ultrasound transducers is necessary for designing filters that match the impedances of the transducer and the analysis of the transducer. A method is proposed to determine the equivalent circuits of broadband transducers with 2 resonances in the frequency band of interest. The circuit parameters are estimated by iterative Levy method with the measured electrical conductance data. The method is illustrated by computing the conductance and susceptance of the equivalent circuits of 3 types of broadband transducers. The equivalent circuit of a transducer.

• Medical Lasers
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• v.9 no.1
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• pp.39-43
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• 2020

Background and Objectives Breast reconstruction has the advantage of reducing the loss of the body image of patients after mastectomy surgery, and also improving the quality of the social and sexual life of breast cancer patients. However, in surprising and unfortunate number of patients, acute postoperative pain persists beyond the normal course of postsurgical recovery. We set out to investigate the effect of local dynamical micro-massage (LDM) treatment for achieving pain relief and reducing other postoperative complications. Materials and Methods We performed a retrospective analysis on 58 patients who underwent LDM treatment for postoperative pain management at Soonchunhyang University Bucheon Hospital between February 2017 and June 2019. Those patients who complained of persistent postoperative pain, which was uncontrollable with medication, were treated with LDM. The degree of pain and discomfort with contracture were recorded using numerical rating scale (NRS) scoring system with numbers from 0 to 10 ('none' to 'worst'). Results The median NRS score of pain was reduced by 62.3% from the start to the end of LDM treatment (p<0.001). Further, the NRS score of discomfort with contracture was reduced 66.0% (p<0.001). There was no complication related to the LDM treatment. Conclusion Dual-frequency ultrasound LDM can be an effective therapeutic option for persisting pain after breast reconstruction surgery. It was also effective in improvement of discomfort with contracture and erythema of the surgical wound.