• Science of Emotion and Sensibility
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• v.26 no.3
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• pp.149-160
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• 2023

This study develops a time-varying system-based noncontact fabric sensor that can measure cerebral blood-flow signals to explore the possibility of brain blood-signal detection and emotional evaluation. The textile sensor was implemented as a coil-type sensor by combining 30 silver threads of 40 deniers and then embroidering it with the computer machine. For the cerebral blood-flow measurement experiment, subjects were asked to attach a coil-type sensor to the carotid artery area, wear an electrocardiogram (ECG) electrode and a respiration (RSP) measurement belt. In addition, Doppler ultrasonography was performed using an ultrasonic diagnostic device to measure the speed of blood flow. The subject was asked to wear Meta Quest 2, measure the blood-flow change signal when viewing the manipulated image visual stimulus, and fill out an emotional-evaluation questionnaire. The measurement results show that the textile-sensor-measured signal also changes with a change in the blood-flow rate signal measured using the Doppler ultrasonography. These findings verify that the cerebral blood-flow signal can be measured using a coil-type textile sensor. In addition, the HRV extracted from ECG and PLL signals (textile sensor signals) are calculated and compared for emotional evaluation. The comparison results show that for the change in the ratio because of the activation of the sympathetic and parasympathetic nervous systems due to visual stimulation, the values calculated using the textile sensor and ECG signals tend to be similar. In conclusion, a the proposed time-varying system-based coil-type textile sensor can be used to study changes in the cerebral blood flow and monitor emotions.

• Progress in Medical Physics
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• v.7 no.2
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• pp.67-77
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• 1996

Purpose: To get a 3-D coordinates of intracranial target position was investicated in axial, sagittal and coronal magnetic resonance imaging with a preliminary experimented target localizer. Material and methods : In preliminal experiments, the localizer is made of engineering plastic to avoid the distrubance of magnetic field during the MR image scan. The MR localizer displayed the 9 points in three different axial tomogram. The bright signal of localizer was obtjained from 0.1～0.3％ of paramagnetic gadolinium/DTPA solution in T1WI or T2WI. In this study, the 3-D position of virtual targets were examined from three different axial MR images and the streotactic position was compared to that of BRW stereotactic system in CT scan with same targets. Results: This study provided the actual target position could be obtained from single scan with MRI localizer which has inverse N-typed 9 bars. This experiment was accomplished with shimming test for detection of image distortion in MR image. However we have not found the image distortion in axial scan. The maximum error of target positions showed 1.0 mm in axial, 1.3 mm for sagittal and 1.7 mm for coronal image, respectivelly. The target localization in MR localizer was investicated with spherical virtual target in skull cadaver. Furthermore, the target position was confirmed with CRW stereotactic system showed a 1.3 mm in discrepancy. Summary : The intracranial target position was determined within 1.7 mm of discrepancy with designed MR localizer. We found the target position from axial image has more small discrepancy than that of sagittal and coronal image.

• Journal of Sensor Science and Technology
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• v.11 no.2
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• pp.67-76
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• 2002

We have presented a 2-dimensional fluxgate sensor with ferrite core, excitation, and pick-up coil. This fluxgate sensor system consists of a sensing element, driving circuits for excitation coil and signal processing for detecting second harmonic frequency component which is proportional to the DC magnetic to be measured. The sensor core is excited by a square waveform of voltage through the excitation coil of 80 turns. The second harmonic output of pick-up coil(x and y axis: 100 turns) is measured by FFT spectrum analyzer. This result is compared with output of PSD(phase sensitive detector) unit for detecting the second harmonic component. The measured maximum sensitivity is about 1580 V/T at driving frequency of 1.5 kHz and excitation current of 2 App. The nonlinearity of this system is measured about 2.3%(PSD) and about 1%(second harmonics of the pick-up). The angle error of the system is ${\pm}2$ %/FS.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.297-309
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• 2009

The study analyzed the mechanism of plantar foot pressure distribution during pitching wedge swinging on a flat, an up hill lie and a down hill lie to provide the fundamental information regarding biomechanical motion data by using plantar foot pressure measuring instrument. In the results, time factor spanning according to slope differences, plantar foot pressure factor and swing motion on the slope could have negative effect on the coiling of lower limbs during back swing, as well as the blocking of the lower limbs to minimize the dispersion of the weight and the release of the lower limbs after the impact during the down swing process. Moreover, since slope is one of many external factors affecting swing motion, address motion on an up hill lie limits the lower limbs movement, therefore, a relatively narrow stance is better on a down hill lie. It is estimated that a relatively wide stance would be better in order to limit the bigger activation of the lower limbs. Not only for the address motion but also during the down swing on an up hill lie it is concluded that the weight should be on the left foot in order to keep the body balance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.67-73
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• 2016

Recently, wireless power transmission has attracted much interest and is the subject of much research in industry and academia. As its name implies, it is a technology which involves transferring power without wires. This paper presents the design of an ICT-based wireless power transmission system. The proposed system consists of a wireless transceiver unit and high-efficiency coil unit, which can increase both the transmission efficiency and the effective power distance. In particular, the wireless transceiver unit was designed to work with the ICT technique to enable real-time remote monitoring. Also, studies were done relating to the effect of reducing the standby power. The optimal frequency of IGBT devices used in industrial wireless power systems of 20[KHz] was utilized. The values of $23.9[{\mu}H]$ and $2.64[{\mu}F]$ were selected for L and C, respectively, through many field experiments designed to optimize the system design. In addition, an output current controlling algorithm was developed for the purpose of reducing the standby power. The results presented in this paper represent a 75[%] to 85[%] higher power transmission efficiency with a 10[%] increase in the effective power transmission distance compared with the existing systems. As a result, the proposed system exhibits a lower standby power and maintenance costs. Also, the designed wireless transceiver unit facilitates fault detection by means of user acquired data with the development of the ICT applied program.

• Korean Chemical Engineering Research
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• v.60 no.2
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• pp.249-254
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• 2022

With the rapid advance of the semiconductor and Information and communication technologies, remote environment monitoring technology, which can detect and analyze surrounding environmental conditions with various types of sensors and wireless communication technologies, is also drawing attention. However, since the conventional remote environmental monitoring systems require external power supplies, it causes time and space limitations on comfortable usage. In this study, we proposed the concept of the self-powered remote environmental monitoring system by supplying the power with the levitation-electromagnetic generator (L-EMG), which is rationally designed to effectively harvest biomechanical energy in consideration of the mechanical characteristics of biomechanical energy. In this regard, the proposed L-EMG is designed to effectively respond to the external vibration with the movable center magnet considering the mechanical characteristics of the biomechanical energy, such as relatively low-frequency and high amplitude of vibration. Hence the L-EMG based on the fragile force equilibrium can generate high-quality electrical energy to supply power. Additionally, the environmental detective sensor and wireless transmission module are composed of the micro control unit (MCU) to minimize the required power for electronic device operation by applying the sleep mode, resulting in the extension of operation time. Finally, in order to maximize user convenience, a mobile phone application was built to enable easy monitoring of the surrounding environment. Thus, the proposed concept not only verifies the possibility of establishing the self-powered remote environmental monitoring system using biomechanical energy but further suggests a design guideline.

• Journal of the Korean Society for Nondestructive Testing
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• v.17 no.3
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• pp.156-161
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• 1997

The eddy current probe was designed for the test of fin tubes that have uneven outer and inner surfaces to enhance the efficiency of heat emission. Because of the surface roughness of the fin tube, it needs much care to detect flaws in the tube employing eddy current test(ECT). We made ECT probes with different coil lengths and performed eddy current test using these probes for artificially flawed specimens. By the fast Fourier transform and digital filtering, signals from these probes were processed to characterize frequency spectra. From the analysis of eddy current signals and their frequency spectra, we concluded that, for the effective testing of the tubes with the fins of 1mm pitch, 4mm coil length gave the highest S/N ratio.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.5
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• pp.405-412
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• 2004

In this paper, Non-contact power supply(NCPS) with the long primary cable longer than 20m and the large air-gap between the primary and secondary of Non-Contacting Transformer(NCT) is presented. The NCT has a large leakage inductance bigger than its magnetizing inductance because it has low coupling, and it is not efficient for NCPS to transfer the primary energy to the secondary one. In order to improve this problem, the voltage-gain characteristics of the series resonant converter, the parallel resonant converter, and the series-parallel resonant converter are analyzed respectively. In addition, the experimental results of 10kW prototype the series-parallel resonant converter is presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1478-1485
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• 2007

In this paper, a meteorological system including a wind speed & direction module and the DSP(Digital Signal Processor) sensor interface circuit board are proposed. This DSP system accepts and process the informations from a wind speed & direction module, the atmospheric pressure sensor, the ambient air temperature sensor and transfers it to the PC monitoring system. Especially, a wind speed & direction module and a DSP hardware are directly designed and applied. A wind speed & direction module have a construction that it have four film type RID(Resistive Temperature Detectors) resistive sensor adhered around the circular metal body heated constantly by heating coil for obtaining vector informations about wind. By this structure, the module is enabled precise measurement having a robustness about vibration, humidity, corrosion. A sensor signal processing circuit is using TMS320F2812 TI(Texas Instrument) Corporation high speed DSP. An economical meteorological system could be constructed through the data from wind speed & direction module and by the fast processing of DSP interface circuit board.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.183-183
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• 2015

Indium tin oxide (ITO)는 넓은 밴드갭을 가지는 n-type의 축퇴 반도체로 태양전지, 스마트윈도우, 터치 센서, organic light emitting displays (OLEDs) 등에 널리 적용된다. 최근 touch screen panels (TSPs)의 높은 전기적 특성 및 고해상도 요구에 따라 고품질 ITO 박막개발의 수요도 증가하는 추세이다. 지금까지 ITO 박막의 물성 및 기계적 특성에 관한 많은 연구가 진행되어 왔지만 ITO 초박막 에서의 근본적인 물성 변화에 대한 연구는 미흡한 실정이므로, 이러한 연구는 필수적이라 할 수 있다. ITO 초박막은 광학적 특성은 우수하나, 낮은 결정성으로 인해 전기적 특성이 나쁘다는 단점을 가지며, 이러한 ITO 박막의 결정성은 초기 박막 성장과정에 많은 영향을 받는다. ITO 박막의 초기성장과정은 핵이 생성된 후(nucleation), 각각의 위치에서 성장하게 되고(growth), 합쳐지면서(coalescence) 연속적인 막을 형성 하는데(continuous), 이러한 초기 박막 성장 과정 중에 핵 생성 밀도를 증가시키고 박막이 연속적으로 되는 두께를 감소시킨다면, 더욱 더 고품질의 ITO 초박막을 얻을 수 있을 것이다. 따라서, 본 연구에서는 박막 초기 형성 과정 중 섬들이 합체되는 두께를 최소화시키기 위하여 EMF(electromagnetic field strength) 시스템을 이용하였다. EMF 시스템은 DC 캐소드에 전자석 코일을 장착하여 전자기장을 추가로 부가한 것으로, 이를 이용할 경우 스퍼터 원자가 중성상태로 기판에 도달하는 것이 아니라, 이온화되어 Vp-Vf의 차이로 가속되어 추가적인 에너지를 공급받음으로써 기판표면상에서 확산을 촉진시키므로 박막이 연속적으로 되는 임계 두께를 감소시킬 수 있는 것으로 기대된다. 실험은 실온에서 DC 마그네트론 스퍼터링법을 이용하였으며, 유리기판위에 4, 6, 8, 10, 12, 20 nm의 두께로 ITO 박막을 제작하였다. 스퍼터링 파워는 150 W (3.29 W/cm3), 작업 압력은 0.13 Pa, 기판과 타깃 사이의 거리는 70 mm였다. 각각의 두께에서 EMF 파워 0, 5, 10, 15, 20, 25, 30 W로 인가하여 박막을 제작한 후, EMF 파워에 따른 ITO 박막의 초기 성장 과정중 표면상태를 AFM (atomic force microscope) 이미지를 통하여 관찰하였다. 또한, 두께 약 8 nm에서와 20 nm일 때의 전기적 특성 및 광학적 특성을 관찰하였으며, 두 박막 모두 EMF 파워 15 W를 인가하였을 때 그 특성이 가장 향상되는 것을 확인하였다. 이러한 결과를 통하여 박막은 초기 성장이 중요하므로, 매우 얇은 두께에서 좋은 특성을 가진 박막을 제작하여야 박막의 두께를 증가시켰을 때도 좋은 특성의 막을 얻을 수 있음을 알 수 있었다. 또한, EMF 파워를 증가시킴에 따라 자장강도를 증가시키는 것과 같은 효과 즉, 플라즈마 임피던스가 감소하는 효과를 내어 증착 중 고 에너지 입자 (Ar0, O-)에 의한 박막손상이 감소한 것으로 판단된다. 따라서 적정 EMF 파워 15 W를 인가하였을때 가장 물성이 좋은 ITO 박막을 얻을 수 있었다. 즉, EMF 시스템을 이용하여 저온 공정에서 결함농도가 적은 고품질의 ITO 초박막을 제작할 수 있었다.