• 대한기계학회논문집A
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• 제22권3호
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• pp.644-653
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• 1998

In resistance spot weld, the assurance of weld quality has been a long-standing problem. Since the weld nuggets if resustance spot welding form between the workpieces, visual detection of defects in usually impossible. Welding quality of resistance spot welding can be verified by non destructive and destructive inspections such as X-Ray inspection and testing of weld strength. But these tests, in addition to being time-consuming and costly, can entail risks due to sampling basis. The purpose of this study is the development of the monitoring system based on fuzzy inference, aimed at diagonosis of quality in resistance spot welding. The fuzzy inference system consists of fuzzy input variables, fuzzy membership functions and fuzzy rules. For inferring the welding quality(strength), the experimental data of the spot welding were acquired in various welding conditions with the monitoring system designed. Some fuzzy input variables-maximum, slop and difference values of electrode movement signals-were extracted from the experimental data. It was confirmed that the fuzzy inference values of strength have a .${\pm}$5% error in comparison with actual values for the selected welding conditions(9-10.5KA, 10-14 cycle, 250-300 $kg_f$). This monitoring system can be useful in improving the quality assurance and reliability of the resistance spot welding process.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.249-251
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• 2022

본 연구에서는 뇌파를 이용하여 드론을 제어하기 위한 기계학습을 논의한다. 드론의 이륙과 전진, 후진, 좌측 이동 그리고 우측 이동을 제어대상으로 정의하였고 이를 제어하기 위한 뇌파의 신호를 전두엽을 대상으로 하는 Fp1·Fp2 2채널 건식 전극(NeuroNicle FX2) 뇌파 측정장비를 통하여 5.19초동안 각 제어대상과 연관된 행동의 운동 심상을 눈을 뜬 상태에서 측정(Sampling Rate 250Hz, Cutoff Frequency 6~20Hz) 하였다. 측정된 뇌파신호에 대해 매틀랩의 분류학습기를 이용해서 삼중 계층 신경망, 로지스틱 회귀커널, 비선형 3차 SVM 학습을 실시하였으며 학습결과 로지스틱 회귀 커널 학습에서 드론의 이륙과 전진, 후진, 좌측 이동 그리고 우측 이동을 위한 가장 높은 정확도를 가지고 있음을 클래스 참양성률로 확인할 수 있었다.

• Journal of Welding and Joining
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• 제15권4호
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• pp.42-62
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• 1997

Resistance spot welding has been widely used in the sheet metal joining processes because of its high productivity and convenience. Recently, automobile industries are trying to replace partly steel sheets with aluminum alloy sheets. Among currently produced aluminum alloys, Al alloy sheets of Al-Mg-Si(6000 series) are being tested. Especially, 6000 series are the most probable substitute in view of strength and weldability. In this paper, an attempt was made to apply resistance spot welding to joining of dissimilar sheet metals (KS6383+SCPZn or KS6383+SHCP). An effort was made to balance heating rate in the Al alloy with that in the steel sheets by increasing electrode tip diameter. Although resistance spot welding of Al alloy sheet and sheet metals does not produce desirable nugget, it proved to have reasonable strength if optimal weld condition is found by tensile-shear strength and fatigue life test. Since spot weld joints in automobile are always experiencing repeated load, spot welding methodology proposed in this paper is found to be not suitable to automobile body manufacturing.

• 대한임상검사과학회지
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• 제45권4호
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• pp.170-179
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• 2013

There is a correct way to avoid any sequale in the central motor area during neurosurgery procedures. A clear way to find the circumference of the central sulcus, central motor, and sensory areas by giving cortical electrical stimulation to the central motor area immediate after surgery is proposed. Looking at patients who underwent brain surgery September 2009 to July 2013, the central sulcus and speech areas around the central area of the brain was investigated, using the practices of either a localized brain map check or a direct cortical electrical stimulation test. Brain maps localized around the surgical site through functional movement or speech areas were identified. Accurate tests done during surgery without damage to motor neurons or after surgery were conducted smoothly. Although successful brain map test localization can be accomplished, there are some factors that can interfere. The following phenomena can reverse the phase: (1) the first sensory / motor in the case of patients severe nerve damage; (2) placement of the electrode on top of the vessel; (3) presence of a brain tumor near the brain cortex; (4) use of anesthesia if patient cooperation is difficult; and (5) location of the electrode position and stimulus is inappropriate.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1232-1235
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• 2004

The purpose of this study is to design electrical stimulation system for pharyngeal dysfunction(dysphagia) in stroke patients. Pharyngeal muscle group activity is important, because contracting muscles provide the driving force at the initiation of the swallow and generate the pressure gradients necessary for bolus movement into the esophagus. Although we have many treatment methods for dysphagia, electrical stimulation system will be useful for stroke patients having dysphagia. Electrical stimulation can be divided into the body stimulation and electrodes. The body stimulation is divided again into frequency counter, time control and current measurement part. These parts are to control the current intensity, frequency and stimulating time. And they can be variable according to the patient's clinical assessment. The electrode plays a role to deliver the current from the system to the muscle. Also the position of the electrode can be variable according to the treatment method. We performed the clinical experiment with the stroke patient who has swallowing disorder. The videofluoroscopy was used for the observation. From the result of clinical experiment based on electrical stimulation, we expected that the dysfunction(in pharynx) level of the patient can be improved. However we could not have enough effectiveness of the treatment because of the number of patients, patient's adaptation and treatment period. We will design the optimized electrical stimulation system based on enough clinical experiment in the future.

• 한국산학기술학회논문지
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• 제10권5호
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• pp.992-999
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• 2009

심전도와 맥파를 측정함으로써 구해질 수 있는 맥파전달시간은 심혈관계의 상태를 진단하기 위한 의미 있는 지표가 된다. 그러나 맥파를 측정하는 동안 움직이거나, 측정 시에 가해지는 압력이 부정확할 경우, 잘못된 측정 결과를 얻을 수 있다. 이를 해결하기 위하여 본 논문에서는 심전도, 압력맥파 및 광전용적맥파를 동시에 측정할 수 있는 일체형 센서 시스템과 심전도를 지속적으로 측정할 수 있는 금속 전극을 개발하였으며, 실험을 통해 일체형 센서시스템 및 금속 전극의 유용성을 입증하였다.

• 국제물리치료학회지
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• 제5권2호
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• pp.718-722
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• 2014

The cerebellum is known to control balance, equilibrium, and muscle tone. If the cerebellum becomes damaged, the body is unable to retain its balancing functions or involuntary muscle movement. This is why, in stroke patients, there is a high risk of functional disability, as well as a myriad of other disabilities secondary to stroke. Ischemia was induced in SD mice by occluding the common carotid artery for 5 minutes, after which blood was reperfused. Needle electrode electrical stimulation(NEES) was applied to acupuncture points, at 12, 24, and 48 hours post-ischemia on the joksamri. Protein expression was investigated through caspase-3 antibody immuno-reactive cells in the cerebral nerve cells and Western blotting. The results were as follows: The number of caspase-3 reactive cells in the corpus cerebellum 12 and 24 hours post-ischemia was significantly (p<.05) smaller in the NEES group compared to the GI group. caspase-3 expression 12 and 24 hours post-ischemia was significantly(p<.05) smaller in the NEES group compared to the GI group. Based on these results, NEES seems to have a significant effect on Caspase-3 in the cerebellum in an ischemic state at 12 and 24 hours post ischemia, NEES delays the occurrence of early stage apoptosis-inducing Caspase-3, delaying and inhibiting apoptosis. Further systematic studies will have to be conducted in relation to the application of this study's results on stroke patients.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.49-49
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• 2010

Nanopiezotronics is an emerging area of nanotechnology with a variety of applications that include piezoelectric field-effect transistors and diodes, self-powered nanogenerators and biosystems, and wireless nano/biosensors. By exploiting coupled piezoelectric and semiconducting characteristics, it is possible for nanowires, nanobelts, or nanorods to generate rectifying current and potential under external mechanical energies such as body movement (handling, winding, pushing, and bending) and muscle stretching, vibrations (acoustic and ultrasonic waves), and hydraulic forces (body fluid and blood flow). Fully transparent, flexible (TF) nanogenerators that are operated by external mechanical forces will be presented. By controlling the density of the seed layer for ZnO nanorod growth, transparent ZnO nanorod arrays were grown on ITO/PES films, and a TF conductive electrode was stacked on the ZnO nanorods. The resulting integrated TF nanodevice (having transparency exceeding 70 %) generated a noticeable current when it was pushed by application of an external load. The output current density was clearly dependent on the force applied. Furthermore, the output current density depended strongly on the morphology and the work function of the top electrode. ZnO nanorod-based nanogenerators with a PdAu, ITO, CNT, and graphene top electrodes gave output current densities of approximately $1-10\;uA/cm^2$ at a load of 0.9 kgf. Our results suggest that our TF nanogenerators are suitable for self-powered TF device applications such as flexible self-powered touch sensors, wearable artificial skins, fully rollable display mobile devices, and battery supplements for wearable cellular phones.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.47-47
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• 2010

Discharge under the water is very hard and demand considerable high voltage. But specially improved electrode can generate plasma discharge to salty water with relatively low voltage. A round shape ceramic electrode having many pinholes combined with metallic one can generate plasma. 400 volt, 10 kHz and 3 micro second pulse width were applied to repeatedly running synthetic seawater with 10 L/m velocity, containing cultivated E. coli and Bacillus. As a result, 18, 94, 99.97, 100, 100 % disinfection rates to E. coli and 17.1, 17.1, 82.9, 99.4, 99.9 % disinfection rates to Bacillus subtilis were achieved to 1, 2, 3, 4, 5 times repetitive treatment respectively. In the plasma condition, the ions and electrons are separated and new kinds of components are re-synthesized by the intensive movement of the components. Especially chlorine ions are separated and recombined to residual free chlorine like HOCl, $OCl^-$. The residual free chlorine concentrations of discharged water were 0.25, 0.88, 1.39, 1.59, 1.66 mg $Cl_2$/L after 5 times treatment respectively. Another unconfirmed radical and oxidants for example, OH, $H_2O_2$, and $O_3$ can have an effect on microorganism of course.

• 대한물리의학회지
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• 제10권2호
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• pp.95-98
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• 2015

PURPOSE: This study was conducted to devise a method of preventing water infiltration into the surface electrodes during EMG measurements underwater and on the ground and to check the reliability of Electromyography (EMG) measurements when underwater. METHODS: Six healthy adults were selected as subjects in this study. The measurements in this study were conducted in pool dedicated to underwater exercise and physical therapy room in the hospital building. An MP150 (Biopac Systems, US, 2010) and a BioNomadix 2-channel wireless EMG transmitter (Biopac Systems, US, 2012) was used to examine the muscle activity of rectus femoris, biceps femoris, tibialis anterior, gastrocnemius of dominant side. The subjects repeated circulation tasks on the ground for more than 10 min for enough surface electrode attachment movement. After a 15-min break, subjects performed the circulation task underwater(water depth 1.1m, water temperature $33.5^{\circ}C$, air temperature $27^{\circ}C$), as on the ground, for more than 10 min, and the MVIC of each muscle was measured again. SPSS v20.0 was used for all statistical computations. RESULTS: The maximum voluntary isometric contraction (MVIC) values between the underwater and on the ground measurements showed no significant differences in all four muscles and showed a high intraclass correlation coefficient (ICC) of >0.80. CONCLUSION: We determined that EMG measurements obtained underwater could be used with high reliability, comparable to ground measurements.