• 대한기계학회논문집A
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• 제31권4호
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• pp.417-424
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• 2007

This paper reports fabrication and characterization of a pressure sensor using a pitch-based carbon fiber. Pitch-based carbon fibers have been shown to exhibit the piezoresistive effect, in which the electric resistance of the carbon fiber changes under mechanical deformation. The main structure of pressure sensors was built by performing backside etching on a SOI wafer and creating a suspended square membrane on the front side. An AC electric field which causes dielectrophoresis was used for the alignment and deposition of a carbon fiber across the microscale gap between two electrodes on the membrane. The fabricated pressure sensors were tested by applying static pressure to the membrane and measuring the resistance change of the carbon fiber. The resistance change of carbon fibers clearly shows linear response to the applied pressure and the calculated sensitivities of pressure sensors are $0.25{\sim}0.35 and 61.8 ${\Omega}/k{\Omega}{\cdot}bar$ for thicker and thinner membrane, respectively. All these observations demonstrated the possibilities of carbon fiber-based pressure sensors.

• 한국광학회지
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• 제17권2호
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• pp.143-148
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• 2006

광섬유 내 브릴루앙 산란의 이득 스펙트럼을 측정하는 새로운 방법을 제안하고 실험하였다. 기존의 측정 방식과는 달리, 주입전류를 직접 변조하여 광주파수 변조된 하나의 레이저 다이오드로부터 펌프광과 프로브광을 발생시키고, 주입전류를 사각파로 변조할 때 나타나는 광주파수 처핑을 이용하여 펌프/프로브간 광주파수 차이를 연속적으로 변화시키는 방법으로 브릴루앙 이득 스펙트럼을 측정하였다. 통신용 단일모드 광섬유의 브릴루앙 이득 스펙트럼을 측정하여 기존 문헌의 결과와 거의 일치하는 결과를 얻었다.

• 한국안전학회지
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• 제22권1호
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• pp.36-39
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• 2007

It is important to know Minimum Ignition Energy(MIE) of flammable materials for ignition hazard of chemical processes etc.. Currently a capacitor discharge is used mainly to measure the MIE. Then, it is impossible to control actively discharge energies and discharge time because the MIE measurement uses a high voltage capacitor and fixed capacitor. However, the control of discharge energy and discharge time will be convenient if self-sustain discharge is used. In this paper, we measured the MIE by self-sustain discharge of a pulse shape to propose the new measuring method of the MIE. AS a result, ignition energies are increased gradually as discharge duration time gets longer, and discharge current grows larger. Also, an arc discharge and a glow discharge occurred during the experimental period, and the ignition by glow discharges happened when discharge duration time was $90{\mu}s$, discharge current was 8A and 1A Especially, the MIE occurred the 0.05mm and 0.08mm of the gap distance between discharge electrode in the same discharge duration time.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 학술대회 논문집 전문대학교육위원
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• pp.49-51
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• 2002

In this thesis, Josephson junction using high-Tc superconducting multi-layer thin film has been fabricated by on-axis RF magnetron sputtering method. And, the characterizations were performed by X-ray diffraction, SEM and the measuring system of critical current density. The physical properties of multi-layer superconducting thin films were also analyzed with the measured results. To fabricate the multi-layer superconducting thin films, the optimum partial pressure of Argon and Oxgen and the temperature of substrate were measured. Also, YBaCuO thin film was grown on MgO and $SrTiO_3$ substrates by rf-sputtering and LGO thin film of 30 A was epitaxially grown on the YBaCuO thin film as a josephson junction with the same condition. The schottky barrier at the contact surface between YBaCuO/LGO and YBaCuO/Au and the energy gap of 0.5 ${\sim}$ 0.6 mV in Nb were observed from the dI/dV-V of YBaCuO/LGO/Au/Nb and YBaCuO/Au/Nb.

• 한국정보처리학회논문지
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• 제4권8호
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• pp.2106-2119
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• 1997

초고속 통신망 구축일 활발해지면서 기존의 근거리통신망(Local Area Network)을 초고속 통신망에 접속하는 장치의 개발에 대한 필요성이 증가하고 있다. 이러한 중간 접속장치는 Ethernet, FDDI 등에서 발생하는 패킷을 처리할 수 있어야 할 뿐만 아니라, 점차 그 수요가 증가하고 있는 멀티미디어 데이터를 효과적으로 수용할 수 있도록 설계되어야 한다. 본 논문에서는 이러한 기능을 수행하는 중간 접속장치로써 NDAS(Network Data Access System)를 제안하고자 한다. 이를 위하여 NDAS 시스템의 기능 및 하드웨어 구조 등을 제시하고, 멀티미디어 데이터 트래픽 특성인 Burstiness를 수용할 수 있는 버퍼 용량을 시뮬레이션을 통해 제시하였다.

• 한국자동차공학회논문집
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• 제12권1호
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• pp.99-105
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• 2004

The car seat head restraint is used for neck injury(whiplash injury) prevention in rear end impacts. The purpose of this study was to evaluate the seat head restraints for the total number of 34 domestic cars. H-POINT machine and HRMD(head restraint measuring device) were applied to measure backset(the distance between head and seat head restraint) and height(height gap between head and seat head restraint). For tendency study of driver's head position, we took the 320 driver's pictures in the street. As results, There were only five percent drivers in good and acceptable zone. For car seat head restraint system, the results was 9 cars for good zone, 10 cars for acceptable zone, 9 cars for marginal zone and 6 cars for poor zone were evaluated. For a precise evaluation the of whiplash injury, detailed FE neck model will be developed and the clinical database should be constructed for model validation.

• International Journal of Safety
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• 제5권2호
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• pp.18-23
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• 2006

Studies have claimed that ESE (Early Streamer Emission) air terminals offer a vastly increased zone of protection over that of traditional lightning rods (Franklin rods) by causing the emission of an upward streamer/leader: The upward streamer/leader will propagate towards the tip of the downward leader at an early stage in the attachment process.. This paper shows the results of a performance evaluation test of a particular type of the ESE air terminal (called "ElecHippo") with a simple rod tested at the Korea Electrotechnology Research Institute (KERI). The corona emission current of the ElecHippo made by Yong-Jin Enterprise Corp. has also been measured at the Occupational Safety & Health Research Institute (OSHRI). The results show that the ElecHippo meets the French standard of NFC 17-102-1995. The results also verify the ESE performance by measuring the ion emission current generated in the discharge electrode gap as a function of the capacitance and inductance of the equipped devices. Finally, we propose a new method for grounding the system to reduce the lightning damage by combining the ESE air terminal, the early discharge earth plate, the lightning strike recorder and the surge protection device.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1273-1274
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• 2007

In this paper, a Optical Voltage Transformer has been designed and fabricated to improve temperature stability caused by materials properties and insulation in measuring system, using single crystal $Bi_{12}SiO_{20}$ as Pockels effect cells for Gas Insulated Switchgear[GIS] System. LD[wavelength: 850nm] was used as optical source, InGaAs as optical detector to measure optical power, Polarizing Beam Splitter as Polarizer and Analyzer, and Multi-mode Optical-fiber[62.5/$125{\mu}m$] as Light transmission line. OPT was assembled in order to pockels effect, and adopted direct electric field type. The linearity of OPT maintains variation for applied voltage range from 100V - 3000V during the test of electric property, As the temperature was changed from $25^{\circ}C$ to $60^{\circ}C$. the result of this study shows that characteristics of OPT are good, and it can be reflected for practical optical sensors in GIS system.

• 폴리머
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• 제35권3호
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• pp.272-276
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• 2011

선택 반사를 보여주는 콜레스테릭 액정의(cholesteric liquid crystal; CLC) planar 배열이 유도되는 메카니즘을 CLC 셀의 선택 반사율과 FTIR $C{\equiv}N$ 피크 세기를 측정하여 조사하였다. 배향막을 사용한 경우보다는 planar 배열 유도가 완전하지는 않았지만 shear force를 이용하거나 또는 고분자 기판을 연신하여 배향막을 사용하지 않은 상태에서 planar 배열을 유도하였다. CLC의 planar 배열이 유도되는 메카니즘은 기판 표면에 접촉하는 액정분자들이 한 방향으로 늘어서면, 그 액정분자 위에 CLC의 나선 구조들이 기판에 수직으로 형성되며 planar 배열이 유도되는 것이다.

• 한국광학회지
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• 제27권6호
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• pp.229-232
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• 2016

마이크로 갭을 포함하는 테라헤르츠파 메타물질을 이용하면 공명주파수 근방의 투과 스펙트럼 변화를 관측함으로써, 높은 감도로 마이크로 크기의 곰팡이, 박테리아 등의 미생물을 검출할 수 있다. 공명주파수의 스펙트럼 변화폭은 미생물의 굴절률 및 마이크로 갭에 위치한 미생물의 개수에 크게 의존한다. 테라헤르츠 메타물질을 통해 다양한 미생물들을 검출하였으며, 또한, 세척 과정을 통해 센서의 재사용이 가능함을 보였다. 유한차분 시간영역 전산모사를 이용하여 메타물질 공명주파수의 미생물 개수 및 굴절률 의존성을 확인하고 실험결과를 검증하였다.