• Advances in nano research
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• 제9권2호
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• pp.123-131
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• 2020

Conventional fabrics that have modified in to conductive fabrics using conductive nanomaterials have novel applications in different fields. These of fabrics can be used as heat generators with the help of the Joule heating mechanism, which is applicable in thermal therapy and to maintain the warmth in cold weather conditions in a wearable manner. A modified fabric can also be used as a sensor for body temperature measurements using the variation of resistance with respect to the body temperature deviations. In this study, polyol synthesized silver nanowires (Ag NWs) are incorporated to commercially available cotton fabrics by using drop casting method to modify the fabric as a thermogenic temperature sensor. The variation of sheet resistance of the fabrics with respect to the incorporated mass of Ag NWs was measured by four probe technique while the bulk resistance variation with respect to the temperature was measured using a standard ohm meter. Heat generation profiles of the fabrics were investigated using thermo graphic camera. Electrically conductive fabrics, fabricated by incorporating 30 mg of Ag NWs in 25 ㎠ area of cotton fabric can be heated up to a maximum steady state temperature of 45℃, using a commercially available 9 V battery.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.876-893
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• 2014

The resistance performance of an icebreaking cargo vessel according to the variation of waterline angles is investigated numerically and experimentally. A recently developed Finite Element (FE) model is used in our analysis. A resistance test with synthetic ice is performed in the towing tank at Pusan National University (PNU) to compare and validate the computed results. We demonstrate good agreement between the experimental and numerical results. Shipice interaction loads are numerically calculated based on the Fluid Structure Interaction (FSI) method in the commercial FE package LS-DYNA. Test results from model testing with synthetic ice at the PNU towing tank are used to compare and validate the numerical simulations. For each waterline angle, numerical and experimental comparisons were made for three concentrations (90%, 80%, and 60%) of pack ice. Ice was modeled as a rigid body, but the ice density was the same as that used in the experiments. A comparative study according to the variation of stem angles is expected to be conducted in the near future.

• 전기전자학회논문지
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• 제20권3호
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• pp.226-234
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• 2016

전기 저항 단층촬영법(ERT)은 대상체 내부 단면의 저항률 분포를 추정하고 이를 영상화하는 기술이다. ERT의 영상복원은 매우 비정치성이 강한 역문제의 일종으로 의미있는 영상을 얻기 위해서는 조정기법이 사용된다. 대표적으로 l2-norm 조정기법, l1-norm 조정기법, Total Variation 조정기법이 사용되며, 조정기법에 따라 ERT의 영상복원 성능이 달라진다. 즉, 상황에 맞는 적절한 조정기법의 사용은 ERT 영상 복원을 개선할 수 있다. 따라서, 본 논문에서는 모의실험을 통하여 상황에 따른 세 가지 조정기법의 영상복원 성능을 비교하였다.

• 센서학회지
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• 제27권6호
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• pp.357-361
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• 2018

This paper presents an averaging current adjustment technique for reducing the pixel resistance variation in a bolometer-type uncooled infrared image sensor. Each unit pixel was composed of an active pixel, a reference pixel for the averaging current adjustment technique, and a calibration circuit. The reference pixel was integrated with a polysilicon resistor using a standard complementary metal-oxide-semiconductor (CMOS) process, and the active pixel was applied from outside of the chip. The averaging current adjustment technique was designed by using the reference pixel. The entire circuit was implemented on a chip that was composed of a reference pixel array for the averaging current adjustment technique, a calibration circuit, and readout circuits. The proposed reference pixel array for the averaging current adjustment technique, calibration circuit, and readout circuit were designed and fabricated by a $0.35-{\mu}m$ standard CMOS process.

• Journal of Welding and Joining
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• 제32권6호
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• pp.1-7
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• 2014

For the resistance spot welds of CR1180 and GA1180 TRIP steels, the weld quality evaluation method using the digitalized X-ray transmission imaging apparatus was investigated in comparison with the crosssectional examination method. In the case of the resistance spot welding of CR1180, three circular regions, such as WZ(white zone), GZ(grey zone) and DZ(dark zone), appeared on X-ray image and they corresponded to the diameters of indentation mark, nugget and corona bond, respectively. The variation of X-ray transmission thickness due to the thickness variation of the weld seemed to be mainly responsible for the formation of those contrasts. The X-ray image contrast formed from the variation of transmission thickness at the outer border line of DZ could also enable the inspections of the notch shape, nonuniformity of the welding pressure and spatter from its sharpness, concentricity and the normal straight line, respectively. The X-ray image of the resistance spot weld of galvannealed GA1180 TRIP steel was very similar to that of CR1180 TRIP steel except the crown shaped outer border line of DZ which was considered to be due to the melting behavior of zinc having the boiling temperature even lower than the melting temperature of steel.

• 한국강구조학회 논문집
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• 제19권2호
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• pp.139-146
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• 2007

국내 LRFD 도로교설계규정의 휨에 대한 재료 저항계수 정립 시 기초 통계자료로 활용하기 위하여 국산 강재를 적용한 강합성 플레이트 거더 단면의 정모멘트 및 부모멘트 하 휨저항강도를 통계적으로 분석하였다. 최근 국내에서 생산된 16,000여 표본의 구조용 강재와 철근에 대한 항복강도와 인장강도 등의 기계적 특성을 통계적으로 분석하여, 공칭강도에 대한 편심계수(bias factor)와 변동계수(coefficient of variation)를 구하였다. 이들 국산 강재와 철근을 적용하여 정 부모멘트를 받는 도로교 강합성 플레이트 거더교 대표단면에 대한 재료 비선형 소성해석을 수행하였으며, 해석결과로부터 모멘트-곡률 곡선을 구하고 단면의 휨저항강도를 산정하였다. 공칭휨강도와 극한휨저항강도를 비교하고 대표적 강합성 단면에 대한 편심계수와 변동계수 통계치를 제시하였다.

• 조명전기설비학회논문지
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• 제24권1호
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• pp.136-144
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• 2010

봉형접지극은 우리나라 배전계통에 가장 많이 사용하고 있는 접지전극이다. 현재 배전계통에 사용하고 있는 봉형접지극은 접지동봉, 심타용접지봉 그리고 도전성콘크리트접지봉 등이 주로 사용되고 있다. 그러나 접지저항값은 토질에 따라 소정의 접지저항값을 얻기가 어려울 때가 많아 접지저항저감제를 사용하게 된다. 본 연구에서는 봉형접지지전극 중 가장 많이 사용하고 있는 접지동봉에 물을 제공하였을 때 얻어진 접지저항값을 기준으로 접지저항저감제의 사용방법(시공법), 접지저항저감제의 종류 등에 따라 얻어진 초기접지저항값, 시간경과(1년)에 따른 저항값의 변화폭 추이 등을 비교 검토한 연구이다. 본 연구 결과를 요약하면 신공법으로 접지저항저감제를 사용하였을 때 낮은 초기접지저항저감을 얻는 효과뿐만 아니라 시간경과에 따른 접지저항값의 변화폭도 적어 안정됨을 확인할 수 있었다.

• 센서학회지
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• 제26권1호
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• pp.56-59
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• 2017

This paper presents the Inkjet-printed strain gauge using PEDOT:PSS. The strain gauge (width 0.6 mm, length 20 mm, thickness $0.3{\mu}m$) was printed on the PET film using PEDOT:PSS ink. The resistance variation of the fabricated strain gauge was measured by the digital multi-meter with the displacement range of -4 to 10 mm. As the measured result, resistance variation (${\Delta}R/R_0$) has approximately 0.75%, linearity of 99.87%. The fabricated strain gauge is expected to the various applications such as tape type pressure sensor, PMS(pressure mapping sensor), wearable devices.

• 대한기계학회논문집B
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• 제21권1호
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• pp.57-67
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• 1997

The solidification process of Al 4.5%Cu alloy is numerically studied in the presence of contact resistance between mold and cast. Natural convection is considered in the liquid and mushy regions. The porosity approach is applied to the mushy zone modeling and linear variation of the solid fraction on the temperature is assumed. Results show that the mushy region is wider in the case with a contact resistance compared to the perfect contact condition. The temperature of the cast with a temporal variation in the contact heat transfer coefficient changes very rapidly in the early stage of the casting process compared to that with constant contact heat transfer coefficient.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1428-1429
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• 2011

This paper variation of stranded cable conductor with CIP(Cold Isostatic Press) technology. Conductor as cable material takes majority costs. Thus many experiments have been done on conductor compaction. The core technology is to maintain the resistance of circular stranded conductor after compaction process, while reducing the weight of conductor diameter, but by increasing filling factor. Testing by varying the compaction ratio using 300SQ conductor, conductor after CIP process shows lower resistance rather than conductor before CIP process.