• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.189-199
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• 2016

Many implantable hearing aids are being developed as alternatives to conventional hearing aids which has inconveniences for use and social stigma that make hearing-impaired people avoid to wear it. Particularly, the fully-implantable middle ear hearing devices (F-IMEHD) are being actively studied for mixed or sensorineural hearing impaired people. In development of F-IMEHD, the most difficult problem is improving the performance of implantable microphone. Recently, Cho et al. have studied the tympanic membrane installed microphone which has better sensitivity and is easier to operate on patient than the microphone implanted under the skin. But, it may cause howling problem due to the feedback signal via oval window and ossicle chain from the transducer on round window in the middle ear cavity, therefore, a feedback canceller is necessary. In this paper, we designed NLMS (normalized least mean square) adaptive feedback canceller for F-IMEHD with tympanic membrane installed microphone and a transducer implemented at round window, and computer simulation was performed to verify its operation. The designed adaptive feedback canceller has a delay filter, a 64 point FIR fixed filter and a 8-tap adaptive FIR filter. Computer simulation of the feedback path is modeled by using the data obtained through human cadaver experiment.

• 한국의학물리학회지:의학물리
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• 제16권3호
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• pp.155-159
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• 2005

생체에 이식되는 장치에 사용하기 위한 무선에너지 전송 시스템을 개발하였다. 이것은 체내에 이식된 장치에 경피적으로 전기에너지를 공급할 수 있는 것이다 경피적으로 결합된 트랜스포머의 권선간의 거리는 인간의 피부 두께를 고려하여 약 10$\~$20 mm이다. 본 연구에서는 Class-E 공진증폭기를 사용하여 높은 효율을 얻고자 하였다. 최대 전류는 각 주파수에서 50 mA 이상의 전류를 얻을 수 있었다. 개발된 시스템은 500 kHz, 1 MHz 및 4 MHz의 서로 다른 주파수에서 정확하게 동작하고 있다는 것을 보여주고 있다.

• 전기학회논문지P
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• 제64권3호
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• pp.175-181
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• 2015

In this paper, the neuromuscular electrical stimulation medical devices for non-implantable incontinence treatment other than vaginal insertion type was developed and commercialized. The structure of medical devices for electrical stimulation based on the anatomy of the pelvic floor muscle designed. Then, the optimum parameters that may be effective in pelvic floor muscle electrical stimulation was set. The circuit system based on the optimum parameters were designed and manufactured. The frequency of the pulse voltage for electrical stimulation is 75[Hz], the pulse width is 300[${\mu}s$], the development of medical devices was to have seven program functions to the various treatments. The circuit system of medical devices was composed of microcontroller, comparator and converter. The performance of the developed circuit system in KTC(Korea Testing Certification) were carried out medical equipment inspection test. Test results, test specifications were satisfied with the medical device, the performance was verified to be commercialized as a medical device. The development of medical devices were validated risk assessment and product performance through a software validation. Commercialization of medical equipment was acquired to enable the certification standards of the international standard IEC 60601-1.

• 대한의용생체공학회:의공학회지
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• 제36권1호
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• pp.31-36
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• 2015

In this study, we evaluated the effects of static magnetic fields of earphones and headphones on pacemakers and implantable cardioverter defibrillators(ICDs). Five pacemakers and three ICDs were subjected to in-vitro test with three headphones which were an in-ear earphone, clip-on headphone, and closed-back headphone. Each implantable device was placed in close proximity(within 3 mm) to the ear-pad of each of the earphone and headphones for 3 min. As a result, no effects were observed on the pacemakers for the earphone and headphones during the test, but an effect was observed on one ICD for the clip-on and closed-back headphone during the test. When the ICD was placed in close proximity to the headphones, the ICD temporarily suspended functions of tachyarrhythmia detection and therapy. The effect was not observed in this study when the headphones were at least 2 cm from the ICD. Based on these findings, patients with ICDs should be advised to keep earphones and headphones at least 2 cm apart from their ICDs.

• 대한의용생체공학회:의공학회지
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• 제22권4호
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• pp.349-358
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• 2001

A novel electro-mechanical implantable ventricular assist system is developed as a bridge to transplantation or recovery for patients with end-stage heart failure. The developed system is composed of an implanted blood pump, an external monitoring system which stores data, and a wearable system including a portable external driver and a portable power supply system. The blood pump is designed to be implanted into the left upper abdominal space and provides blood flow from the left ventricular apex to the aorta. The pulsatile blood flow is generated by a double cylindrical cam. There was mo excessive heat emission from the blood pump into the temperature-controlled chamber in the heat test and no stagnated flow within the blood sac by the observation in the flow visualization test. Animal experiments were performed using sheep and calves. The maximum assist flow rate reached 7.85L/min in the animal experiment. The evaluation results showed that the developed system was feasible for the implantable ventricular assist system. The long-term in vitro durability test and mid-term in vivo experiments are in progress and mow the modified next model is under development.

• 대한의용생체공학회:의공학회지
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• 제44권6호
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• pp.414-427
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• 2023

Implantable bioabsorbable combination products undergo inherent degradation and systemic absorption within the physiological environment, thereby streamlining the therapeutic regimen and obviating the imperative for invasive extraction procedures. This inherent property not only enhances patient convenience and therapeutic efficacy but also underpins a paradigm of support characterized by heightened safety parameters. Within the regulatory landscapes of Korea, the United States, and Europe, implantable bioabsorbable combination products are meticulously classified into distinct categories, either as pharmaceutical implants or as implantable medical devices, depending on their primary mode of action. This scholarly investigation systematically examines the regulatory frameworks governing implantable bioabsorbable combination products in South Korea, the United States, and Europe. Notable discrepancies across national jurisdictions emerge concerning regulatory specifics, including terminology, product classification, and product name associated with these products. The conspicuous absence of standardized approval regulations presents a formidable barrier to the commercialization of these advanced medical devices. This academic discourse passionately emphasizes the critical need for formulating and implementing a sophisticated regulatory framework capable of streamlining the product approval process, thereby paving the way for a seamless path to commercializing implantable bioabsorbable combination products.

• 대한의용생체공학회:의공학회지
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• 제31권5호
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• pp.401-406
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• 2010

Recently, many implantable medical devices have been developed and manufactured in many countries. In these devices, generally, energy is supplied by a transcutaneous method to avoid the skin penetration due to the power wires. As the most transcutaneous power transmission methods, the electromagnetic coupling between two coils and resonance at a specific frequency has been used widely. However, in case of a transcutaneous power transmitter with a fixed switching frequency to drive an electromagnetic coil, inefficient power transmission and thermal damage by the undesirable current variation may occur, because the electromagnetic coupling state between a primary coil and a secondary coil is very sensitive to skin thickness of each applied position and by person. In order to overcome these defects, a transcutaneous power transmitter of which operating frequency can be automatically tracked into the resonance frequency at each environment has been designed and implemented. Through the results of experiments for different coil surroundings, we have been demonstrated that the implemented transcutaneous power transmitter can track automatically into a varied resonance frequency according to arbitrary skin thickness change.

• 한국멀티미디어학회논문지
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• 제19권2호
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• pp.375-385
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• 2016

Recently, several implantable hearing aids such as cochlear implant, middle ear implant, etc., which have a module receiving power and signal from outside the body, are frequently used to treat the hearing impaired patients. Most of implantable hearing aids are adopted permanent magnet pairs to couple between internal and external devices for the enhancement of power transmission. Generally, the internal device which containing the magnet in the center of receiving coil is implanted under the skin of human temporal bone. In case of MRI scanning of a patient with the implantable hearing aid, however, homogeneous magnetic fields of the MRI might be interfered by the implanted magnet. For the above reasons, the MR image is degraded by large area of artifact, so that diagnostics are almost impossible in deteriorated region. In this paper, we proposed an external coil system that can reduce the artifact of MR image due to the internal coupling magnet. By finite element analysis estimating area of MR artifact according to varying current and shape of the external coil, optimal coil parameters were extracted. Finally, the effectiveness of the proposed external coil system was verified by confirming the artifact at real MRI scan.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1996년도 추계학술대회
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• pp.273-276
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• 1996

In the Total Artificial Heart (TAH) and Ventricular Assist Device (VAD), the size implanting the internal controller into human body is very serious problem. Hence, we need the size reduction of that controller for safe implantation. Using PSD302 chip for microcontroller-based applications, we could decrease the number of components in the digital control board and miniaturize the digital control board. We could replace a ROM, RAM, and a latch with that single chip, so the size of the newly developed board could be half the previous board.

• 대한의용생체공학회:의공학회지
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• 제28권4호
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• pp.539-548
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• 2007

In the paper, a wireless charger with the function of auto-shutdown for fully implantale middle ear hearing devices (F-IMEHD) has been designed. The wireless charger can communicate with an implant module to be turned off automatically shutdown after an internal rechargeable battery has been fully-charged by electromagnetic coupling using two coils. For the communication with an implant module, the wireless charger uses the load shift keying (LSK) method. But, the variation of the mutual inductance due to the different distance between two coils can cause the communication error in receiving the fully-charged signal from an implant module. To solve the problem, the implemented wireless charger has a variable reference generator for LSK communication. The wireless charger generates proper level of the reference voltage for a comparator using an ADC (analog-to-digital converter) and a DAC (digital-to-analog converter). Through the result of experiment, it has been confirmed that the presented wireless charger can detect signals from implantable module. And wireless charger can stop generating electromagnetic flux after an implanted battery has been fully charged in spite of variable coil distance according to different skin thickness.