• Proceedings of the KOSOMBE Conference
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• v.1992 no.05
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• pp.27-47
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• 1992

Engineers have developed new instruments that aid in diagnosis and therapy Ultrasonic imaging has provided a nondamaging method of imaging internal organs. A complex transducer emits ultrasonic waves at many angles and reconstructs a map of internal anatomy and also velocities of blood in vessels. Fast computed tomography permits reconstruction of the 3-dimensional anatomy and perfusion of the heart at 20-Hz rates. Positron emission tomography uses certain isotopes that produce positrons that react with electrons to simultaneously emit two gamma rays in opposite directions. It locates the region of origin by using a ring of discrete scintillation detectors, each in electronic coincidence with an opposing detector. In magnetic resonance imaging, the patient is placed in a very strong magnetic field. The precessing of the hydrogen atoms is perturbed by an interrogating field to yield two-dimensional images of soft tissue having exceptional clarity. As an alternative to radiology image processing, film archiving, and retrieval, picture archiving and communication systems (PACS) are being implemented. Images from computed radiography, magnetic resonance imaging (MRI), nuclear medicine, and ultrasound are digitized, transmitted, and stored in computers for retrieval at distributed work stations. In electrical impedance tomography, electrodes are placed around the thorax. 50-kHz current is injected between two electrodes and voltages are measured on all other electrodes. A computer processes the data to yield an image of the resistivity of a 2-dimensional slice of the thorax. During fetal monitoring, a corkscrew electrode is screwed into the fetal scalp to measure the fetal electrocardiogram. Correlations with uterine contractions yield information on the status of the fetus during delivery To measure cardiac output by thermodilution, cold saline is injected into the right atrium. A thermistor in the right pulmonary artery yields temperature measurements, from which we can calculate cardiac output. In impedance cardiography, we measure the changes in electrical impedance as the heart ejects blood into the arteries. Motion artifacts are large, so signal averaging is useful during monitoring. An intraarterial blood gas monitoring system permits monitoring in real time. Light is sent down optical fibers inserted into the radial artery, where it is absorbed by dyes, which reemit the light at a different wavelength. The emitted light travels up optical fibers where an external instrument determines O2, CO2, and pH. Therapeutic devices include the electrosurgical unit. A high-frequency electric arc is drawn between the knife and the tissue. The arc cuts and the heat coagulates, thus preventing blood loss. Hyperthermia has demonstrated antitumor effects in patients in whom all conventional modes of therapy have failed. Methods of raising tumor temperature include focused ultrasound, radio-frequency power through needles, or microwaves. When the heart stops pumping, we use the defibrillator to restore normal pumping. A brief, high-current pulse through the heart synchronizes all cardiac fibers to restore normal rhythm. When the cardiac rhythm is too slow, we implant the cardiac pacemaker. An electrode within the heart stimulates the cardiac muscle to contract at the normal rate. When the cardiac valves are narrowed or leak, we implant an artificial valve. Silicone rubber and Teflon are used for biocompatibility. Artificial hearts powered by pneumatic hoses have been implanted in humans. However, the quality of life gradually degrades, and death ensues. When kidney stones develop, lithotripsy is used. A spark creates a pressure wave, which is focused on the stone and fragments it. The pieces pass out normally. When kidneys fail, the blood is cleansed during hemodialysis. Urea passes through a porous membrane to a dialysate bath to lower its concentration in the blood. The blind are able to read by scanning the Optacon with their fingertips. A camera scans letters and converts them to an array of vibrating pins. The deaf are able to hear using a cochlear implant. A microphone detects sound and divides it into frequency bands. 22 electrodes within the cochlea stimulate the acoustic the acoustic nerve to provide sound patterns. For those who have lost muscle function in the limbs, researchers are implanting electrodes to stimulate the muscle. Sensors in the legs and arms feed back signals to a computer that coordinates the stimulators to provide limb motion. For those with high spinal cord injury, a puff and sip switch can control a computer and permit the disabled person operate the computer and communicate with the outside world.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.5
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• pp.508-517
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• 2004

We described a near-field scanning microwave microscope which uses a high-quality dielectric resonator with a tunable screw. The operating frequency is f=4.5 5GHz. The probe tip is mounted in a cylindrical resonant cavity coupled to a dielectric resonator We developed a hybrid tip combining a reduced length of the tapered part with a small apex. In order to understand the function of the probe, we fabricated three different tips using a conventional chemical etching technique and observed three different NSMM images for patterened Cr films on glass substrates. We measured the reflection coefficient of different metal thin film samples with the same thickness of 300m and compared with theoretical impedance respectly. By tuning the tunable screw coming through the top cover, we could improve sensitivity, signal-to-noise ratio, and spatial resolution to better than $1{\mu}m$. To demonstrate the ability of local microwave characterization, the surface resistance of metallic thin films has been mapped.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.4
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• pp.477-483
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• 2008

The paper introduces mobile handset multi-band chip antenna to be used on meander line PIFA structure and parasite patch. The proposed antenna uses an FR-4 substrate. The top layer is consist of meander lines PIFA structure to implement GSM900 and is connected with each rad and meander line on the via-hole for maximize space efficiency. The middle layer is designed with the signal line and gap to implement a DCS and PCS bands, the bottom layer which is added to a parasite patch on the ground can be show an adjust of frequency and impedance character by the connection of the radiators of middle layer and coupling. The fabricated antenna with the dimension of $28{\times}6{\times}4\;mm^3$. The ground plane a dimension of $45{\times}90\;mm$, designed by a commercial software CST simulator. The experimental results show that the bandwidth for(VSWR<3) is 90($875{\sim}965$) MHz in GSM900 band operation and 380($1,670{\sim}2,050$) MHz in DCS, PCS band operation. The maximum gains of antenna are 0.25 dBi, 3.65 dBi and 3.3 dBi at resonance frequencies and it has omni-directional pattern practically.

• Journal of Biomedical Engineering Research
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• v.38 no.1
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• pp.16-24
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• 2017

For the development of feasible retinal prosthesis, one of the important elements is acquiring proper judging tool if electrical stimulus leads to patient's visual perception. If evoked potential to electrical stimulus is recorded in primary visual (V1) cortex, it means that the stimulus effectively evokes visual perception. Therefore, in this study, we established VEP recording system on V1 cortex using BioPAC modules as the judging tool. And the measuring system was evaluated by recording VEP of mice. After anesthesia, normal mice (C57BL/6J strain; n = 6) were secured to stereotaxic apparatus (Harvard Apparatus, USA). For the recording of VEP, the stainless steel needle electrode (impedance: $2-5k{\Omega}$) was positioned on the surface of the cortex through the burr hole at 2.5 mm lateral and 4.6 mm caudal to bregma. DA 100C and EEG 100C BioPAC modules were used for the trigger signal and VEP recording, respectively. When left eye was blocked by black cover and right eye was stimulated by flash light using HMsERG (RetVet Corp, USA), VEP response at left V1 cortex was detected, but there was no response at right V1 cortex. Amplitudes and latencies of P2, N3 peaks of VEP recording varied according to the depths of the electrodes on V1 cortex. From the surface upto $600{\mu}m$ depth, amplitudes of P2 and N3 increased, while deeper than $600{\mu}m$, those amplitudes decreased. The deeper the insertion depth of the electrode, the latency of N1 peaks tends to be delayed. However, there was no statistically significant difference among the latencies of P2 and N3 peaks (P > 0.05, ANOVA). Our VEP recording data such as the insertion depth and the latency and amplitudes of peaks might be used as guidelines for electrically-evoked potential (EEP) recording experiment in near future.

• Journal of the Korean Society for Nondestructive Testing
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• v.33 no.5
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• pp.465-471
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• 2013

A steam generator in nuclear power plant is a heatexchager which is used to convert water into steam from heat produced in a nuclear reactor core, and the steam produced in steam generator is delivered to the turbine to generate electricity. Because of damage to steam generator tubing may impair its ability to adequately perform required safety functions in terms of both structural integrity and leakage integrity, eddy current testing is periodically performed to evaluate the integrity of tubes in steam generator. This assessment is normally performed during a reactor refueling outage. Currently, the eddy current testing for steam generator of nuclear power plant in Korea is performed in accordance with KEPIC & ASME Code requirements, the eddy current testing system is consists of remote data acquisition unit and data analysis program to evaluate the acquired data. The KEPIC & ASME Code require that the electrical properties of remote data acquisition unit, such as total harmonic distortion, input & output impedance, amplifier linearity & stability, phase linearity, bandwidth & demodulation filter response, analog-to-digital conversion, and channel crosstalk shall be measured in accordance with the KEPIC & ASME Code requirements. In this paper, the measurement requirements of electrical properties for eddy current testing instrument described in KEPIC & ASME Code are presented, and the measurement results of newly developed eddy current testing instrument by KHNP(Korea Hydro & Nuclear Power Co., LTD) are presented.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.46-51
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• 2013

In this paper, a dual-band antenna is proposed for the RF power harvester system as well as RFID tag. The proposed antenna operates as the passive and active RFID tag antenna in the UHF and microwave band, respectively. In addition, to charge the battery of an active RFID tag in the microwave band, it harvest the RF signal for tagging from the passive RFID tag antenna in the UHF band. The proposed antenna operates in the UHF band (917~923.5 MHz) and microwave band (2.4~2.45 GHz). In order to obtain the dual-band operation, the dipole structure and meander parasitic elements are proposed as the ${\lambda}/2$ and $1{\lambda}$ dipole antenna, respectively. The radiating dipole structure in the microwave band acts as the coupled feed for the meander parasitic elements in the UHF band. The impedance bandwidth (VSWR < 2) of the proposed antenna covers 917~923.5 MHz (UHF band) and 2.4~2.45 GHz (Microwave band). Measured total efficiencies are over 45 % in the UHF band and over 70 % in the microwave band. Peak gains are over 0.18 dBi and 2.8 dBi in the UHF and microwave band with an omni-directional radiation pattern, respectively.

• Applied Biological Chemistry
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• v.47 no.3
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• pp.300-306
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• 2004

Eight cation or anion-responsive polymer membranes were prepared by a casting procedure employing polyvinyl chloride, Bis (2-ethylhexyl)sebacate and each electroactive material in the ratio of 66 : 33 : 1. The resulting membranes were separately installed onto the sensitive area of the ionic electrodes to produce an 8-channel taste sensor array. The taste sensors of the array were connected to a high-input impedance amplifier and the amplified sensor signals were interfaced to a PC via an A/D converter. The taste evaluation system was applied to a discriminant analysis on six groups of marketed beverages like sikhye, sujunggwa, tangerine juice, ume juice, ionic drink and green tea. When the signal data from the sensor array were analyzed by principal component analysis after normalization, the 1st, 2nd and 3rd principal component explained most of the total data variance. The six groups of the analyzed beverages were discriminated well in the three dimensional principal component space. The half of the five groups of the analyzed beverages was also discriminated in the two dimensional principal component plane.

• Journal of the Korean Electrochemical Society
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• v.23 no.3
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• pp.57-65
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• 2020

It is crucial to investigate the thermal degradation of lithium-ion batteries (LIBs) to understand the possible malfunction at high temperature. Herein, we investigated the effects of surface film formation on the thermal degradation of lithium cobalt oxide (LiCoO₂, LCO) cathode that is one of representative cathode materials. Cycling test at 60℃ exhibited poorer cycleability compared with the cycling at 25℃. Cathodes after the initial 5 cycles at 60℃ (60-LCO) exhibited higher impedance compared to the cathode after initial 5 cycles at 25℃ (25-LCO), resulting in the lower rate capability upon subsequent cycling at 25℃, although the capacity values were similar at the lowest C-rate of 0.1C. In order to understand degradation of the LCO cathode at the high temperature, we analyzed the cathodes surface using X-ray photoelectron spectroscopy (XPS). Among various peaks, intensity of lithium hydroxide (LiOH) increased substantially after the operation at 60℃, and the C-C signal that represents the conductive agent was distinctly lower on 60-LCO compared to 25-LCO. These results pointed to an excessive formation of cathode-electrolyte interphase including LiOH at 60℃, leading to the increase in the resistance and the resultant degradation in the electrochemical performances.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.1
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• pp.13-22
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• 2001

This paper presents three dimensional structure of RF packages and the improvement effect of its electrical characteristics when implementing RF transceivers. We divided RF modules into several subunits following each subunit function based on the partitioning algorithm which suggests a method of three dimension stacking interconnection, PAA(pad area array) interconnection and stacking of three dimensional RF package structures. 224MHz ITS(Intelligent Transportation System) RF module subdivided into subunits of functional blocks of a receiver(RX), a transmitter(TX), a phase locked loop(PLL) and power(PWR) unit, simultaneously meeting the requirements of impedance characteristic and system stability. Each sub­functional unit has its own frequency region of 224MHz, 21.4MHz, and 450KHz~DC. The signal gain of receiver and transmitter unit showed 18.9㏈, 23.9㏈. PLL and PWR modules also provided stable phase locking, constant voltages which agree with design specifications and maximize their characteristics. The RF module of three dimension stacking structure showed $48cm^3$, 76.9％ reduction in volume and 4.8cm, 28.4％ in net length, 41.8$^{\circ}C$, 37% in maximum operating temperature, respectively. We have found that three dimensional PAA package structure is able to produce high speed, high density, low power characteristics and to improve its functional characteristics by subdividing RF modules according to the subunit function and the operating frequency, and the features of physical volume, electrical characteristics, and thermal conditions compared to two dimensional RF circuit modules.

• Journal of Pharmacopuncture
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• v.19 no.3
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• pp.197-206
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• 2016

Introduction: This study aims to investigate the effects of acupuncture stimulation on the radial artery's pressure pulse wave, along with various hemodynamic parameters, and to explore the possible underlying mechanism of pulse diagnosis in healthy participants in their twenties. Methods and analysis: This study is a prospective, single-arm, exploratory clinical study. A total of 25 healthy participants, without regard to gender, in their twenties will be recruited by physicians. Written informed consent will be obtained from all participants. The participants will receive acupuncture once at ST36 on both sides. The radial arterial pulse waves will be measured on the left arm of the subjects by using an applicable pulse tonometric device (KIOM-PAS). On the right arm (appearing twice), electrocardiogram (ECG), photoplethysmogram (PPG), respiration and cardiac output (CO) signals, will be measured using a physiological data acquisition system (Biopac module), while the velocity of blood flow, and the diameter and the depth of the blood vessel will be measured using an ultrasonogram machine on the right arm (appearing twice). All measurements will be conducted before, during, and after acupuncture. The primary outcome will be the spectral energy at high frequencies above 10 Hz ($SE_{10-30Hz}$) calculated from the KIOM-PAS device signal. Secondary outcomes will be various variables obtained from the KIOM-PAS device, ECG, PPG, impedance cardiography modules, and an ultrasonogram machine. Discussion: The results of this trial will provide information regarding the physiological and the hemodynamic mechanisms underlying acupuncture stimulation and clinical evidence for the influence of acupuncture on the pressure pulse wave in the radial artery. Ethics and dissemination: This study was approved by the Institutional Review Board (IRB) of Kyung Hee University's Oriental Medical Center, Seoul, Korea (KOMCIRB-150818-HR-030). The study findings will be published in peer-reviewed journals and presented at national and international conferences. Trial registration number: This trial was registered with the Clinical Research Information Service (CRIS) at the Korea National Institute of Health (NIH), Republic of Korea (KCT0001663), which is a registry in the World Health Organization's (WHO's) Registry Network.