• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.643-646
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• 2004

The posttensioning system of nuclear containment have to be verified its structural integrity by the periodic inspection because the structural behavior of the containment is changed by the variation of the physical property of concrete and tendon as time passes. In this study a program 'SAPONC-CANDU' which is able to monitor and analysis the micro structural behavior of the domestic CANDU type containment at all times was developed. The readings of vibrating-wire strain gauges embedded into the concrete of containment were used as input data for operating the program. This program provides the long-term prediction values and bands of the concrete strain due to the time dependent factors of the concrete and tendon of the domestic CANDU type containment.

• Design & Manufacturing
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• 제11권2호
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• pp.9-14
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• 2017

The design and manufacturing tehcnology of IC sockets beyond 0.3mm pitch were presented. We compared the developed IC socket with the conventional one especially on the core metal-insulation part. Advanced machining techniques were employed to provide high precision. Our wire electrodischarge machining and high speed machining centers were able to maintain the micro-scale precision. We performed an injection molding analysis using a commercial analysis tool to predict the performance of the developed IC socket. We found that the solidification of the plastic resin and the high level of the clamping force are responsible for the defects such as incomplete filling and short shot. From these results, we modified the IC socket and successfully remove the defects. We were also able to find out that the new design socket needs less maintenance cost.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.557-558
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• 2006

The mechanical properties of micro-hardness and internal stress of Ni-Fe alloy thin film made by electrodeposition method have been measured as a function of bath composition and current density. And also the microstructure of $200{\AA}$ Ni-Fi nanowires made using anodic aluminum oxide(AAO) templates by electrodeposition method have been observed by SEM as a function of ultrasonic treatment time and bath composition.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.110-110
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• 2009

본 연구에서는 전산유체역학적 방법을 이용하여 레이저-GMA 하이브리드 용접에서 용융풀 거동에 대한 3차원 과도해석을 수행하였다. 철강재의 주요 합금원소 중 하나인 크롬의 용융풀에서의 거동을 구현하기 위해 크롬에 대해 추가적인 보전 방정식을 도입하였다. 이를 이용하여 합금원소 분포에 대한 용접 변수별 영향을 해석적으로 분석하였으며 이를 EPMA(Electron Probe Micro Analyzer)를 통해 분석한 시험결과와도 비교하였다. 결과적으로 용접변수 중 선행 조건이 합금원소 분포에 구별할만한 영향을 미침을 알 수 있었고 이는 용융풀의 거동을 지배하는 주요 유동 패턴의 상이함에 기인한 것으로 보여진다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.146-154
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• 1999

The test facility of the 1/60-scale models for the train-tunnel interactions was recently developed to investigate the effects of entry portal shapes, flood shapes and air-shafts for reducing the micro-pressure waves radiating to the surroundings of the tunnel exits by KRRI in Korea. The launching system of train model was chosen as air-gun type. In present test rig, after train model is launched, the blast wave by the driver did not enter to inside of the tunnel model. The train model is guided on the one-wire system from air-gun driver to the brake parts of test facility end. Some cases of the experiments were compared with numerical simulations to prove the test facility.

• 한국입자에어로졸학회지
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• 제13권1호
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• pp.11-16
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• 2017

Indoor air quality is of increasing concern because it is closely related human health. An air handling unit (AHU) can be used to control the indoor air quality related to particulate matters and $CO_2$ as well as air conditioning such as temperature and humidity of indoor air. An electrostatic precipitator has a high collection efficiency and low pressure drop, however, ozone can possibly generate from its chargers, which is one of drawbacks to apply it for indoor air control. Here we compared four charging electrodes such as a $50{\mu}m$ tungsten wire, a $100{\mu}m$ tungsten wire, a $16{\mu}m$-thickness Al foil and a carbon fabric comprised of $5-10{\mu}m$ fibers. The carbon fabric electrode showed a superior particle collection efficiency and a lower ozone generation at a given power consumption compared to tungsten wires of 50, $100{\mu}m$ and an Al foil electrode. This low ozone generating, micro-sized electrode can be applied to the electrostatic precipitator in AHU for indoor air control.

• 소성∙가공
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• 제22권1호
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• pp.23-29
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• 2013

In this study, a micro/nano-random-pattern-structure surface was machined by electric discharge machining (EDM) followed by replicating the EDM surface with a silicone elastomer having low energy and greater hydrophobicity. The variation of hydrophobicity was of prime interest and was examined as a function of the surface roughness of the replicated silicone elastomer. The hydrophobicity was evaluated by the water contact angle (WCA) measured on the relevant surface. For the experiments, the original surfaces were machined by die sinking electric discharge machining (DS-EDM) and wire cutting electric discharge machining (WC-EDM). The ranges of surface roughness were Ra $0.8{\sim}19{\mu}m$ for the DS-EDM and Ra $0.5{\sim}4.7{\mu}m$ for the WC-EDM. In order to fabricate a hydrophobic surface, the EDM surfaces were directly replicated using a liquid-state silicone elastomer, which was thermally cured. The measured WCA on the replicated surfaces for DS-EDM was in the range of $115{\sim}130^{\circ}$ and for WC-EDM the WCA was in the range of $123{\sim}150^{\circ}$. Additionally, the dynamic hydrophobicity was evaluated by measuring an advancing and a receding WCA on the replicated silicone elastomer surfaces.

• Journal of Magnetics
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• 제14권2호
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• pp.53-61
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• 2009

Herein, different concepts for domain wall propagation based on currents and fields that could potentially be used in magnetic data storage devices based on domains and domain walls are reviewed. By direct imaging, we show that vortex and transverse walls can be displaced using currents due to the spin transfer torque effect. For the case of field-induced wall motion, particular attention is paid to the influence of localized fields and local heating on the depinning and propagation of domain walls. Using an Au nanowire adjacent to a permalloy structure with a domain wall, the depinning field of the wall, when current pulses are injected into the Au nanowire, was studied. The current pulse drastically modified the depinning field, which depended on the interplay between the externally applied field direction and polarity of the current, leading subsequently to an Oersted field and heating of the permalloy at the interface with the Au wire. Placing the domain wall at various distances from the Au wire and studying different wall propagation directions, the range of Joule heating and Oersted field was determined; both effects could be separated. Approaches beyond conventional field- and current-induced wall displacement are briefly discussed.

• 한국의학물리학회지:의학물리
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• 제20권2호
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• pp.80-87
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• 2009

비혈관 스텐트(식도용, 담도용, 대장용, 십이지장용, 기관지용) 재질로 가장 널리 사용되고 있는 Nitinol wire 형상기억합금의 기계적 특성 향상을 위해 초음파 나노표면 개질(UNSM) 기술을 적용하여 Nitinol wire의 상변화와 초탄성 특성 및 표면 잔류응력 등의 변화를 연구하였으며, 탄력에너지와 부식내구성을 통한 스텐트의 수명 연장방법을 연구하고자 하였다. 본 연구에 사용된 Nitinol wire는 ${\phi}1.778$ mm로 UNSM 처리 전후의 표면거칠기 값은 Ra=0.092${\mu}m$와 Ra=0.093${\mu}m$로 비슷 하였지만, 초기시편에서는 미세결함과 인발가공 흔적이 확연히 관찰되었으나, UNSM 후에는 인발가공 흔적과 미세 표면 결함은 사라진 것이 발견되었다. 또한 잔류응력 측정 결과, 초기 시험편에는 +3.65 MPa였으나 UNSM 처리 후에는 -4.09 MPa로 확인되었으며, XRD를 통한 결정구조 분석 결과 $42.28^{\circ}$에서 초기보다 약한 (110) 오스테나이트 피크가 관찰되었으며, 대신 (020), ($1{\overline{1}}1$), 그리고 (021) 피크가 명확히 Martensite (B19' Monoclinic lattices) 구조로 확인되었고, (300)의 R상 (Rhombohedral lattices)에 대한 추가 피크가 미비하게 관찰되었다. 탄성변형에 따른 에너지 흡수력과 하중 제거에 따른 에너지의 회복력인 탄력계수(modulus of resilience) $U_r$은 단위체적당 변형률 에너지로 4.31 $MJ/m^3$에서 5.85 $MJ/m^3$로 증가하였다. 이와 같이 표면결함 제거와 인장응력을 압축응력으로 재편성하는 것만으로도 피로내구성을 크게 향상시킬 수 있다고 사료되며, 생체적합성과 더불어 내부식성, 내마모성 및 내구수명 향상을 실용화할 수 있는 표면개질 장치가 개발된다면, 현재 한국인 사망원인 1위인 순환계 질환(심근경색, 뇌졸중 등)에 사용되는 혈관계통의 스텐트 개발에도 응용개발연구가 가능할 것으로 예상된다.

• 센서학회지
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• 제9권3호
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• pp.171-176
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• 2000

반응성 스퍼터링과 고주파 마그네트론 스퍼터링으로 각각 증착된 MgO 박막과 그 위에 증착된 백금박막의 열처리 온도 및 시간에 따른 물리적, 전기적 특성을 4침 탐침기, 주사전자현미경 및 X선 회절법을 이용하여 분석하였다. $1000^{\circ}C$, 2시간의 열처리 조건하에서 MgO 박막은 백금박막과 화학적 반응없이 백금박막의 열산화막에 대한 부착특성을 개선시켰으며, 그 위에 증착된 백금박막의 면저항 및 비저항은 각각 $0.1288\;{\Omega}/{\square}$, $12.88\;{\mu}{\Omega}{\cdot}cm$이었다. Lift-off 방법을 이용하여 $SiO_2$/Si기판상에 백금 저항체를 만들었으며, 백금 와이어, 백금 페이스트 그리고 SOG를 이용하여 마이크로 열 센서용 박막형 Pt-RTD를 제작하였다. $25{\sim}400^{\circ}C$의 온도범위에서 $1.0{\mu}m$의 두께를 갖는 제작된 Pt-RTD의 저항온도계수는 벌크 백금에 가까운 $3927ppm/^{\circ}C$로 측정되었다. 측정온도범위내에서 저항값은 선형적인 변화를 보였다.