• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.319-324
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• 2011

This paper dealt with a partial discharge (PD) detection method for insulation diagnosis in cast-resin transformers. To detect PD pulse, a planar-capacitive probe was designed and fabricated. The probe has no insulation problem and can be installed on cast-resin transformers even in operation since it does not connect with high voltage conductor. The PD measurement system consists of the capacitive probe, a coupling network of 100 [kHz] low-cutoff frequency, and an amplifier with a gain of 40 [dB] and a frequency bandwidth of 500 [Hz]~45 [MHz]. A plane-needle and a plane-plane electrode system were fabricated to simulate insulation defects in a cast-resin transformer. Sensitivity of the PD measurement system, which is evaluated by a standard calibrator was 0.35 [mV/pC] for positive and 0.45 [mV/pC] for negative, respectively. The PD detection by the capacitive probe was less sensitive than that by a coupling capacitor according to IEC 60270, but we could analyze the magnitude and the phase distribution of PD pulse.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.172-175
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• 2002

The technique of induced discharge by a pulsed CO2 laser is being applied to control electrical discharge path, material processing, triggered lightning for protecting the power equipments. In this paper, we have investigated about the characteristics of the induced discharge at atmospheric conditions by using a plasma channel, which is produced when a pulsed CO2 laser radiation is focused by a focusing mirror as a trigger source. A plasma channel produced by laser radiation has an effect on decreasing the threshold voltage and inducing the discharge in both needle electrodes. We have confirmed a delay time between a produced plasma channel and an electrical discharge after laser radiation. We provided the decreased voltage lower than the natural discharge voltage between electrode type of needles and was induced the discharge by forming a plasma channel between them. In this research we could understand the time delay of induced discharge by laser radiation, and the characteristics of the discharge cause by the decrease in the threshold voltage, and the polarity effect by changes of plasma channel positions between two electrodes.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.1
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• pp.106-111
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• 2024

A triboelectric nanogenerator is a promising energy harvester operated by the combined mechanism of electrostatic induction and contact electrification. It has attracting attention as eco-friendly and sustainable energy generators by harvesting wasting mechanical energies. However, the power generated in the natural environment is accompanied by low frequencies, so that the output power under such input conditions is normally insufficient amount for a variety of industrial applications. In this study, we introduce a non-contact rotational triboelectric nanogenerator using pedaling and gear systems (called by P-TENG), which has a mechanism that produces high power by using rack gear and pinion gear when a large force by a pedal is given. We design the system can rotate the shaft to which the rotor is connected through the conversion of vertical motion to rotational motion between the rack gear and the pinion gear. Furthermore, the system controls the one directional rotation due to the engagement rotation of the two pinion gears and the one-way needle roller bearing. The TENG with a 2 mm gap between the rotor and the stator produces about the power of 200 ㎼ and turns on 82 LEDs under the condition of 800 rpm. We expect that P-TENG can be used in a variety of applications such as operating portable electronics or sterilizing contaminated water.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.11
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• pp.1022-1027
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• 2005

An experimental study is conducted to investigate the characteristics of the ion wind generated by the electric field between a needle electrode and the parallel plate electrodes. The ion wind enhances heat and mass transfer between the surface and the surrounding gas. Moreover such enhancement makes no noise or vibration. This study is conducted to develop the electronic cooling device. The measured gas velocities and heat transfer coefficients are proportional to the applied voltage. The heat transfer coefficient can be increased as compared with a natural convection. The maximum enhancement of heat transfer obtained in this system is $47\%$ for 3 W in heat transfer rate.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.200.2-200.2
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• 2016

Carbon-based materials have been known as ablative material and have been used for thermal protection systems. Ablation is an erosive phenomenon that results in thermochemical and thermomechanical changes on materials. Ablation resistance is one of the key properties that determines performance and life-time of the thermal protection material under ablative conditions. In this study, ablation properties of graphite, 3-dimensional (C/C) composites (needle-punched type and rod type) were investigated byusing a plasma wind tunnel which produce a supersonic plasma flow from a segmented arc heater with the power level of 0.4 MW. The mass losses and surface roughness changes which contain main result of the ablation are measured. A morphological analysis ofthe carbon-based materials, before and after the ablation test, are performed through field emission scanning electron microscopy (FE-SEM) and non-contact 3D surface measuring system. Electronic balance and a portable surface roughness tester were used for evaluation of the recession and mass loss of the test samples.

• Journal of Physiology & Pathology in Korean Medicine
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• v.32 no.5
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• pp.315-320
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• 2018

The purpose of this study is to investigate reasearch trend of acupuncture treatment on shoulder impingement syndrome. This study investigated the recent studies about acupuncture treatment for shoulder impingement syndrome via searching Korean and foreign electronic databases(Research Information Services, National Digital Science Library, Oriental Medicine Advanced Searching Integated Services, PubMed, China National Knowledge Infrastructure). The search term was searched by combining 'shoulder impingement sydrome', 'subacrominal pain', 'acupuncture', 'needle therapy', and was limited to the articles published from 2005 to 2017. 14 studies were found to be analyzed according to the type of study, the number of cases, the type of treatment, the instruments for assessment and published year. 14 studies were published since 2005, 6 case reports, 8 randomized controlled trials. In the treatment of shoulder impingement syndrome, treatments such as acupuncture, acupotomy, pharmacopuncture, laser acupuncture, combined treatment of exercise and rehabilitation were performed. Visual analogue scale(VAS), range of motion(ROM) and various questionnaires were used as primary assessments. In each study, acupuncture treatment was reported to have a significant effect in the pain, range of motion and disability of shoulder impingement syndrome. In order to ensure objective evidence on acupuncture treatment, large scale case reports and randomized controlled trials should be continued.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.2
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• pp.20-28
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• 2012

Recently, the scientific study from traditional oriental medicine is being progressed. Moreover, through both oriental medicine and medicine are cooperated with medical examination and treatment, the study in cooperation of merits from oriental medicine as well as from medicine is progressed. In this paper, we will develop automatic needle shot using fuzzy rules and USN techniques, which a user can choose meridian pathways from the menu items built in the cellular phone, so it can perceive patient's body conditions and launch an aneurysm electric pressure of a cycle.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.3950-3956
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• 2012

In order to improve the bioactivity and mechanical properties of hydroxyapatite (HAp), chitosan (Chi) was in situ combined into HAp to fabricate a composite scaffold by a sublimation-assisted compression method. A highly porous film with sufficient mechanical strength was prepared and the bioactivity was investigated by examining the apatite formed on the scaffolds incubated in simulated body fluid. In addition, the cytotoxicity of the HAp/Chi composite was studied by evaluating the viability of murine fibroblasts (L-929 cells) exposed to diluted extracts of the composite films. The apatite layer was assessed using scanning electronic microscopy, inductively coupled plasma-optical emission spectrometry and weight measurement. Composite analysis showed that a layer of micro-sized, needle-like crystals was formed on the surface of the composite film. Additionally, the WST-8 assay after L-929 cells were exposed to diluted extracts of the composite indicated that the HAp/Chi scaffold has good in vitro cytocompatibility. The results indicated that HAp/Chi composites with porous structure are promising scaffolding materials for bone-patch engineering because their porous morphology can provide an environment conductive to attachment and growth of osteoblasts and osteogenic cells.

• The Journal of Pediatrics of Korean Medicine
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• v.33 no.3
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• pp.56-68
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• 2019

Objectives The purpose of this study to analyze the effect of Korean medicine therapy of Attention deficit hyperactivity disorders. Methods Electronic research articles were selected by using NDSL, OASIS, KISS, KMBASE, K-portal, Pubmed, Cochrane, and Ebscohost. Results We analyzed fifteen studies about Korean medicine treatment of Attention deficit hyperactivity disorders. There are eleven studies on the acupuncture treatment, and the most commonly used acupoints were GV20 and EX-HN1. There are eight studies on the herb medicine treatment. The most commonly used herbal materials are Root of Rehmanniae Radix et Rhizoma Preparata, Root of Rehmanniae Radix et Rhizoma Preparata, Sclerotium of Poria cocos Wolf, and Rhizome of Acori Gramineri Rhizoma. Syncope and hematomas were common side effects of the acupuncture treatment. Also, the acupuncture needle can be stuck or bent during the treatment. In most studies, Attention deficit hyperactivity disorders was improved when treated with Korean medicine. Conclusions More studies are needed to demonstrate the effectiveness of Korean medicine in Attention deficit hyperactivity disorders. This study can be used for various studies of Attention deficit hyperactivity disorders.

• Journal of Acupuncture Research
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• v.39 no.4
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• pp.267-274
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• 2022

In order to secure clinical evidence for the treatment of cold accumulation (CA), this study reviewed and analyzed 91 records of literature and related records. To perform a classical literature search, the Oriental Medicine Classic databases and the Uibujeonrok electronic data were searched. Books on Immunopharmacopuncture (IP) were also reviewed. A common etiology for CA was attributed to the abdomen, while the detailed sites of the abdomen differed. In IP, CA had a more comprehensive list of symptoms of physiological and pathological significance. As for the treatment of CA, typically, herbal medicine was used until the end of the Korean Empire period, and moxibustion treatment on CV4, CV6, CV-12, ST36, EX-B4, and conduction exercise therapy were also reported. Since 1965, acupuncture needle-based invasive treatment such as acupuncture for CA, and IP have been described in IP theory. Consequently, the treatment of CA (as described in the IP theory), was considered to be a more advanced method of treatment compared with the existing classical treatment methods.