• Journal of the Korean Chemical Society
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• v.58 no.6
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• pp.575-579
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• 2014

Development of liposomes has been actively studied for effective delivery of drug at tumor site. However, despite their preferential accumulation at tumor site, the therapeutic efficacy of such liposomal drug has been limited because of low drug release. Therefore, we developed a temperature-sensitive liposome (TSL), which can be made to maximize release of drug by external stimulation such as ultrasound. Doxorubicin (DOX) as a model drug was encapsulated into TSL by a pH gradient method. The particle size of the TSL was $142.0{\pm}6.24nm$. Surface charge was $-10.55{\pm}1.12mV$. Release of drug from TSLs was up to 80% within 15 min at over $42^{\circ}C$ measured by fluorescence intensity. Cytotoxicity of released DOX from TSLs with ultrasound was highly increased compared to TSLs without ultrasound. Taken together, we demonstrate that temperature sensitive drug release from TSLs with ultrasound, which may be useful for cancer therapy to increase drug concentration at tumor site by external stimulation.

• Journal of Biomedical Engineering Research
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• v.30 no.5
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• pp.418-427
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• 2009

As many people are westernizing their life style and food consumption habits, a number of patients who have malignant tumors which grow very rapidly and hazardously destroy the human body are increasing. Ultrasonic hyperthermia is not only one of the tumor treatment methods which employs the non-radioactive ultrasonic waves to increase the temperature at the tumor region up to $40\sim45^{\circ}C$ to destroy and suppress tumor cells but also has been proved by many studies. Due to the rapid development of High Intensity Focused Ultrasound(HIFU), the ultrasound hyperthemia extensively boosts its applications in clinical field. For those reasons, Computed simulation factor should be needed before inspection to patients. To prove efficiency of ultrasonic hyperthermia, precise acoustic field measurement considering tissue characteristics and a heating experiment with tissue mimicking material phantom were conducted for effectiveness of simulation program. Finally, in this study, the computer simulation program verified the anticipated temperature effects induced by ultrasound hyperthermia. In the near future, it is hoped that this simulation program could be utilized to improve the efficiency of ultrasound hyperthermia.

• Journal of the Korean Burn Society
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• v.23 no.2
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• pp.64-67
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• 2020

High-intensity focused ultrasound (HIFU) has been regarded as a non-invasive uterine-preserving treatment for women with uterine myoma. Numerous studies have reported that it is a relatively safe and effective treatment for uterine myoma. However, severe complications, such as deep thermal burn injuries, bowel perforation, and bladder injury, were reported on rare occasions. We report a case of a 4th degree burn on the lower abdomen after HIFU treatment for uterine myoma. Physicians must consider the possibility of deep thermal burn injuries when managing uterine myoma with HIFU.

• Journal of Sensor Science and Technology
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• v.18 no.5
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• pp.377-384
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• 2009

The ultrasonic hyperthermia for oncology has been developed and studied. The HIFU(high intensity focused ultrasound) is the most recent method to treat the tumor by using ultrasound. In this study, an insertion-type transducer for treating a prostate cancer, which can focus the ultrasonic beam mechanically and electrically, was designed and developed. The developed transducer was composed of three arrays, and each array has 32 elements. For the purpose of the mechanical focusing, both side arrays are slanted to the center array by $15^{\circ}$. With this structure, NFL(near field length) was set up as 30 mm. The PZT-4 and two matching layers were used, and the backing layer was excepted to prevent energy losses. The acoustic field analysis and the heating test were performed to evaluate the performance of developed transducer. The shape of an acoustic field, peak pressure, and acoustic pressure distribution were compared with numerical simulation. The NFL was 32 mm, the beam width was 5 mm, focal area was $40\;mm^2$, and peak pressure was 5.5 MPa. With heating by using developed transducer, the temperature increased up to $33^{\circ}C$ at focal zone. As a result of this study, the usefulness of suggested transducer for prostate cancer hyperthermia was confirmed by the acoustic field analysis and the heating test with TMM(tissue mimicking) phantom.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.484-485
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• 2008

초음파는 의학적 진단 및 치료의 목적으로 널리 사용되어 왔다. 일반적으로, 초음파 조사의 생물학적 무해성은 많은 연구를 통하여 보고되었으나, 최근 초음파 집속을 통한 강력 초음파의 사용에 대한 열적 안전성 평가가 중요한 요소로 대두되고 있다. 이에 본 연구에서는 강력 집속 초음파의 전달 에너지와 열적 분포를 측정하여 안전성 평가에 활용 가능한 초음파 열분포 팬텀을 제안하였다. 온도 분포 측정용 팬텀은 초음파 조직유사 팬텀 재료인 한천을 이용하였으며, 음향학적 특성의 유사성을 평가하였다. 온도 효과를 측정하기 위하여 $3{\times}3$의 형태로 온도 센서를 팬텀 내부에 배열하여 초음파 조사에 따른 온도 분포를 측정하였고 온도 측정을 위한 시스템을 개발하여, 초음파 가열 실험을 수행하였다. 본 연구에서 제안된 초음파 온도 분포 측정용 팬텀의 유용성을 확인하였으며, 온도 분포용 팬텀을 통한 강력 집속 초음파 장비의 열적 성능 평가에 적용 될 수 있을 것으로 사료되었다.

• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.150-157
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• 2017

Three types of piezoelectric single crystals [PMN-PT (Generation I $[Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3]$), PMN-PZT (Generation II $[Pb(Mg_{1/3}Nb_{2/3})O_3-Pb(Zr,Ti)O_3]$), PMN-PZT-Mn (Generation III)] were grown by the solid-state single crystal growth (SSCG) method, and their dielectric and piezoelectric properties were measured and compared. Compared to (001) PMN-PT and PMN-PZT single crystals, the (001) PMN-PZT-Mn single crystals exhibited a higher transition temperature between the rhombohedral and tetragonal phases ($T_{RT}=144^{\circ}C$), as well as a higher coercive electric field ($E_C=6.3kV/cm$) and internal bias field ($E_I=1.6kV/cm$). The (011) PMN-PZT-Mn single crystals showed the highest coercive electric field ($E_C=7.0kV/cm$), and the highest stability of $E_C$ and $E_I$ during 60 cycles of polarization measurement. These results demonstrate that both Mn doping (for higher electromechanical quality factor ($Q_m$)) and a (011) crystallographic orientation (for higher coercive electric field and stability) are necessary for high power transducer applications of these piezoelectric single crystals. Specifically, the (011) PMN-PZT-Mn single crystal (Gen. III) had the highest potential for application in the fields of SONAR transducers, high intensity focused ultrasound (HIFU), ultrasonic motors, and others.

• Journal of the Korean Ceramic Society
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• v.55 no.2
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• pp.166-173
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• 2018

In order to investigate the effect of Mn on the dielectric and piezoelectric properties of PMN-PT [$Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$], four different types of 71PMN-29PT samples were prepared using the solid-state single crystal growth (SSCG) method: (1) Undoped single crystals, (2) undoped polycrystalline ceramics, (3) Mn-doped single crystals, and (4) Mn-doped polycrystalline ceramics. In the case of single crystals, the addition of 0.5 mol% Mn to PMN-PT decreased the dielectric constant ($K_3{^T}$), piezoelectric charge constant ($d_{33}$), and dielectric loss (tan ${\delta}$) by about 50%, but increased the coercive electric field ($E_C$) by 50% and the electromechanical quality factor ($Q_m$) by 500%, respectively. The addition of Mn to PMN-PT induced an internal bias electric field ($E_I$) and thus specimens changed from piezoelectrically soft-type to piezoelectrically hard-type. This Mn effect was more significant in single crystals than in ceramics. These results demonstrate that Mn-doped 71PMN-29PT single crystals, because they are piezoelectrically hard and simultaneously have high piezoelectric and electromechanical properties, have great potential for application in fields of SONAR transducers, high intensity focused ultrasound (HIFU), and ultrasonic motors.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.3
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• pp.116-123
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• 2023

A high intensity focuses ultrasound (HIFU) is one of the emerging technologies in the biomedical field. The piezoelectric HIFU transducer is a device that utilizes the thermal energy generated by high ultrasound energy. Recently an operating frequency of the HIFU transducer is to expand above a 7 MHz. In this study, the acoustic pressures and temperature distributions in the tissue that generated by the HIFU transducer at 10 MHz were calculated with the finite element method. In addition, the pressure focusing characteristics of the device were analyzed. The geometrical variables are the piezomaterial thickness, lens shape, water height, and film thickness. The results shown that the acoustic pressure increased and saturated gradually when the height/radius (H_L/R_L) ratio of the lens increased. Moreover, the focal area was gradually decreases with H_L/R_L ratio of the lens. In case of the optimized HIFU transducer, the maximum pressure and temperature were analyzed about 19 MPa and 65℃ respectively. And the -3 dB focused distances in the axial and lateral direction are around 2.3 mm and 0.23 mm respectively.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.14 no.5
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• pp.394-402
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• 2021

The entry of an aging society and the extension of human life expectancy, the increasing interest in women's social advancement and men's appearance, and the natural interest in K-culture through media media, while receiving worldwide attention, Focus on K-Bueaty. Recently, looking at the occupation of the medical tourism field, in the case of aesthetic medicine tourism such as molding and dermatology, it has gained popularity not only in Asia such as China and Japan, but also in North America and Europe. The first external confirmation of human aging is the wrinkles on the skin of the face. Clean, wrinkle-free, elastic and healthy skin is a desire of most people. Skin condition and condition such as focused ultrasonic stimulation (HIFU: High Intensity Focused Utrasound) and low frequency, high frequency (RF: Radio Frequency), galvanic therapy using microcurrent, cryotherapy using rapid cooling, etc. Depending on the method of management, the effect of the treatment differs depending on the output and the stimulation site, etc., even in the treatment of medical equipment and beauty equipment using the same mechanism. In this research, in order to develop invasive high-frequency dermatological devices using a large number of beauty medical devices and microneedles of beauty devices, the international standards IEC 60601-2 (standards for individual medical devices) and MFDS (Ministry of) We designed and developed a high-frequency output device in compliance with the high-frequency stimulation standard announced in the Food and Drug Safety (Ministry of Food and Drug Safety). The circuit design consists of an amplifier (AMP: Amplifier) using Class-A Topology and a power supply device using Half-Bridge Topology. As a result of measuring the developed high-frequency output device, an average efficiency of 63.86% was obtained, and the maximum output was measured at 116.7W and 50.67dBm.

• Archives of Plastic Surgery
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• v.47 no.1
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• pp.20-25
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• 2020

Background Ultrasonic dissection devices cause less thermal damage to the surrounding tissue than monopolar electrosurgical devices. We compared the effects of using an ultrasonic dissection device or an electrocautery device during prosthetic breast reconstruction on seroma development and short-term postoperative complications. Methods We retrospectively reviewed the medical records of patients who underwent implant-based reconstruction following mastectomy between March 2017 and September 2018. Mastectomy was performed by general surgeons and reconstruction by plastic surgeons. From March 2017 to January 2018, a monopolar electrosurgical device was used, and an ultrasonic dissection device was used thereafter. The other surgical methods were the same in both groups. Results The incidence of seroma was lower in the ultrasonic dissection device group than in the electrocautery group (11 [17.2%] vs. 18 [31.0%]; P=0.090). The duration of surgery, total drainage volume, duration of drainage, overall complication rate, surgical site infection rate, and flap necrosis rate were comparable between the groups. Multivariate analysis revealed that the risk of seroma development was significantly lower in the ultrasonic dissection device group than in the electrocautery group (odds ratio for electrocautery, 3.252; 95% confidence interval, 1.242-8.516; P=0.016). Conclusions The findings of this study suggest that the incidence of seroma can be reduced slightly by using an ultrasonic dissection device for prosthesis-based breast reconstruction. However, further randomized controlled studies are required to verify our results and to assess the cost-effectiveness of this technique.