• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.64-67
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• 1997

In the total artificial heart(TAH), a transcutaneous information transmission system(TITS) is vely important to monitor the TAH status and detect the device failure, and repair the possible problems. First of all, the communication channel(skin) and method were simulated in terms of transmittance, scattering, reflection and absorption, then the system was designed with size reduction including low power consumption and reliability compared to the previous one. The informations are transmitted through the skin(approximately 1cm in depth) by frequency modulated near infrared(NIR) pulses using 780nm laser diodes as transmitters and photodiode as receiver with high speed and high spectral sensitivity. The logic high and low frequencies are 3MHz, 1MHz respectively. The system is a bidirectional data link for more than 38.4Kbps data rate, full-duplex with a bit error rate of less than $10^{-5}$.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.177-184
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• 2011

In this study, the system for application of the bone stimulation was implemented using high frequency and low strain method. The whole system consists of the high frequency and low strain vibration stimulation system 177 for stimulating bone, LVDT sensor, and wireless sensor based on tri-axial accelerometer. To evaluate the usefulness of the system, the frequencies and accelerations from function generator were applied to the vibration stimulation system. The range of frequency was 17 Hz, 30 Hz, 45 Hz, 50 Hz and the range of acceleration was set 0.3 g, 0.6 g, 1g, and 2 g. The measured frequencies and acceleration using LVDT (linear variable difference transformer) sensor and 3-axial accelerometer were estimated and compared. The range of frequencies average difference was from 0.0 to 0.004 Hz. As the standard deviation of frequencies estimated by LVDT sensor and accelerometer was below 0.03 Hz and the output frequencies of function generator were similar: Also the results of t-test were satisfied with conditions of p > 0.05. And the acquired frequencies and acceleration from vibration measuring device module were estimated and analyzed. As the mean of accelerations was similar to the acceleration applied from function generator. And the standard deviation of acceleration estimated from vibration measuring device module was ranged from 0.019 g to 0.038 g. Also the results of t-test were satisfied with conditions of p > 0.05. Therefore, these results were airy similar to the acceleration applied from function generator. As a result, the usefulness of the system was confirmed. n a further study, clinical experiment will be carried out with the authorization of IRB (institutional review board) so that appropriate frequency and strain would be investigated in clinical field.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.8 no.2
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• pp.79-88
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• 2014

In Republic of Korea, there are considerable vulnerability in electrical stimulating swallowing-assist equipments even though they are professional medical equipments and have high penetration rate with heavy frequency of use. Therefore, in this article, we developed Device Management and Safety Diagnosis Manual for Electrical Stimulating Swallowing-Assist Equipments system. For achieving this, we collected and analysed international standard data from international organizations like International Electrotechnical Commission(IEC). After literature reviews, we build maintenance worksheet and equipment procedure manual for electrical stimulating swallowing-assist equipments according to evidences we collected. These manual and protocol would be used as standard process and contribute to sustain accuracy, effectiveness of the devices, also decrease failure rate and assist to save medical documents.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.7
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• pp.534-538
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• 2010

X-ray systems for medical treatment use noninvasive procedures. Being capable of locally inspecting the inside of the body, X-ray systems are routinely used for basic diagnosis. X-ray systems to be used for medical purposes were originally made with a gas filled tube inside an induction coil in the initial stages of development but with this approach it becomes difficult to take a satisfactory picture through thick body sections, non invasively. However continued development made it possible to take non-invasive pictures of breasts, blood vessels and other body parts through thick body sections. Recently, high-voltage X-ray generators of more compact size, increased generation efficiency, and sophisticated output control have become possible. All of these features are made possible by the use of a high-frequency output from an inverter and a fast switching semiconductor device. In this paper, we describe a new X-ray generator operating with a resonant inverter in order to reduce switching loss and high frequency noise. In addition, in order to identify the differences amongst types of rectification, we have compared output and the quality of X-ray pictures obtained with full-wave rectification and dual-voltage rectification methods.

• Laser Solutions
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• v.15 no.4
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• pp.1-5
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• 2012

We demonstrate that reduced graphene oxide (rGO) coated thin aluminum film is an effective optoacoustic transmitter for generating high pressure and high frequency ultrasound previously unattainable by other techniques. The rGO layer of different thickness is deposited between a 100 nm-thick aluminum film and a glass substrate. Under a pulsed laser excitation, the transmitter generates enhanced optoacoustic pressure of 64 times the aluminum-alone transmitter. A promising optoacoustic wave generation is possible by optimizing thermoelasticity of metal film and thermal conductivity of rGO in the proposed transmitter for laser-induced ultrasound (LIUS) applications.

• Healthcare Informatics Research
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• v.24 no.4
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• pp.387-393
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• 2018

Objectives: This paper describes an experience of implementing seamless service trials online and offline by adopting Internet of Things (IoT) technology based on near-field communication (NFC) tags and Bluetooth low-energy (BLE) beacons. The services were provided for both patients and health professionals. Methods: The pilot services were implemented to enhance healthcare service quality, improve patient safety, and provide an effective business process to health professionals in a tertiary hospital in Seoul, Korea. The services to enhance healthcare service quality include healing tours, cancer information/education, psychological assessments, indoor navigation, and exercise volume checking. The services to improve patient safety are monitoring of high-risk inpatients and delivery of real-time health information in emergency situations. In addition, the services to provide an effective business process to health professionals include surveys and web services for patient management. Results: Considering the sustainability of the pilot services, we decided to pause navigation and patient monitoring services until the interference problem could be completely resolved because beacon signal interference significantly influences the quality of services. On the other hand, we had to continue to provide new wearable beacons to high-risk patients because of hygiene issues, so the cost increased over time and was much higher than expected. Conclusions: To make the smart connected hospital services sustainable, technical feasibility (e.g., beacon signal interference), economic feasibility (e.g., continuous provision of new necklace beacons), and organizational commitment and support (e.g., renewal of new alternative medical devices and infrastructure) are required.

• Journal of Biomedical Engineering Research
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• v.38 no.1
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• pp.49-55
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• 2017

The prevalence of obesity has noticeably increased worldwide over several decades with various complication. Even though anti-obesity drug treatments have been spotlighted by resulting in effective mean weight losses, its adverse effects cannot be overlooked. Thus, this study aimed to evaluate the effects of multi-frequency whole body vibration, one of the mechanical stimulus, as a countermeasure against obesity. Thirty-two-6-week-old C57BL/6J male mice were equally assigned to four groups: the Control group (CON, n = 8), the Sham group (Sham, n = 8), the sham with single frequency whole body vibration (S+V, n = 8), and the sham with multi frequency whole body vibration (S+MV, n = 8). After 4 weeks, morphologic changes in the adipose tissue were evaluated from three-dimensional images using in vivo micro-computed tomography. At 4 weeks, the volume of the abdominal adipose tissue, which had the highest value in Sham group, noticeably reduced in S+MV group compared to it in S+V group. These results implied that the accumulation of abdominal adipose tissue can be effectively reduced through applying multi-frequency whole body vibration.

• Journal of Biomedical Engineering Research
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• v.31 no.5
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• pp.395-400
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• 2010

Hypertension is the chronic disease that the 16% of total population are suffering, and it needs to be studied to find alternative treatment because of the tolerance and side effect of medications that may bother some patients. in this paper, we verified practicality of implantable electrical stimulator that can readily change stimulus magnitude and frequency. And this device is possible to stimulate baroreflex or parasympathetic nerve. Therefore we performed in vitro tests and animal experiment for device's operating conditions. This device consist of implantable electrical stimulator and extracorporeal control/monitoring system. Stimulator was designed to make 1Hz~100Hz pulses and it can change continuous or periodic pulse train type. And this device can control stimulator's function and monitor stimulator's status and patients' blood pressure at exterior of body using ZigBee module as wireless telecommunication. We verified that stimulator have error rate under 5% at 50mm depth of organs and, stimulator makes high-efficiency energy with closer position of two electrodes. Also we can confirm the performance of device that decreasing blood pressure and heart rate of a rat by electrical stimulation.

• Journal of Korean Medical Ki-Gong Academy
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• v.10 no.1
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• pp.130-157
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• 2007

The purpose of this research is to seek for efficient health maintenance device and to suggest desirable daily habit, based on the inquiry on interrelationship between workers' daily lives and their heartbeat change level. The paper survey about general features, case history and daily habits was conducted on workers during medical examination in Jeollabukdo, and examined their change of heartbeat as well. The results of research deducted from data analysis are as follows; 1. There found very positive interrelations between time-domain analysis and frequency-domain analysis, and MHR and LF/HF ratio had negative connection with other analyses. 2. The recipient showed high time-domain analysis when they are younger, have worked shorter or have spouse, and it contributes to stable sympathetic nerve and parasympathetic nerve as it stimulates autonomic nervous system. 3. According to the result of frequency-domain analysis, recipients showed higher TP and LF when they are younger, and the highest HF when they are under 34.The level of VLF was higher for university graduates than the ones who finished high school. The recipients showed higher TP and HF when they don't have spouse, and lower TP, LF and HF when they have worked longer. 4. The level of RMSSD and TSRD was high for the people who don't have case history, and HF was high when they don't have any disease in progress. 5. According to the result concerning correlation of daily habits with time-domain analysis and frequency-domain analysis, cigarette, alcohol and sleeping hours don't affect heartbeat change, but the ones who regularly workout showed higher result in every analysis. It shows that the autonomic nervous system of recipients who regularly exercise response more actively. The result mentioned above suggests that the change of heartbeat is a direct index which shows the change of autonomic nervous system, and it depends on the exercise the most. Thus, workout is proved to be the best method in order for workers to take care of their health.

• Journal of the Korea Computer Industry Society
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• v.2 no.4
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• pp.565-572
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• 2001

At the most recent years, laser medical instruments, laser applications and laser nuclear fusion need strong visible light and ultraviolet rays. Nonlinear optical devices, such as harmonic generators and parametric oscillators, provide a means of extending the frequency range of available laser sources. Frequency conversion is a useful technique for extending the utility of high-power lasers. It utilizes the nonlinear optical response of an optical medium in intense radiation fields to generate new frequencies. These progresses have been used to generate high-power radiation in all spectral regions, from the ultraviolet to the far infrared. Optical parametric oscillators and amplifiers generate two waves of lower frequency They are capable of generating a range of wavelengths from a single frequency source, in some cases spanning the entire visible and near infrared regions. Consequently, in order to obtain the green light, the pulsed Nd:YAG laser using multiple-mesh PFN(Pulsed Forming Network) method with Nonlinear optical device was adopted. We compared the current pulseshapes with the laser output energy, and conversion efficiency.