• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.146-149
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• 2007

The 2-step manufacturing method consisting of preforming and stamping processes was developed to manufacture composite bipolar plates for PEMFCs. The preform was composed of expanded graphite, graphite flake and phenol resin. Precuring conditions were optimized by checking the electrical conductivity, flexural strength and microstructure. Precuring temperature ($100^{\circ}C$) slightly above the melting point of phenol powders ($90^{\circ}C$) induced moderate curing, but also prevented excessive curing. Preforms utilizing the tangled structure of expanded graphite were easily fabricated at low pressure of 0.07-0.28MPa. The proper precuring time, 5min, was determined to fabricate the preform stably because insufficient and excessive precuring deteriorated the flexural strength of composite bipolar plates.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.304-307
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• 2006

A plane stress yield function YLD2000(Yoon et al., 2000) is applied to the finite element analysis S/W Z-Stamp because it is required to conduct proper consideration of aluminum alloy which has anomalous behavior. In the previous study, verification of the yield function and developed S/W is implemented. In this paper, two real parts of automobile body are additionally considered to verify the validity of Z-Stamp. The one is the benchmark problem #2 of Numisheet 2005 and the other is a small member part. In case of benchmark problem, formability simulation result and try-out result are compared with each other. In case of the small member part, formability analysis is implemented to predict the problem during the developing time.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1597-1600
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• 2003

Fine-Blanking is an advanced and precision stamping process, by which a component with precise geometry and smooth cut surface can be produced without any further major secondary operations. By applying the Fine-Blanking technology, the significant improvement of the component should be obvious. As the components are with good shape, smooth surface and precise size, they can be ready for assembly without any further secondary operations. The productivity is increased, the production cycle time and the component cost are significantly reduced. We apply the fine-Blanking for chain sprocket. And do Mecanical test for compress strenth. impaact, roughness, Brinell hardness, dimensional stability.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.223-227
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• 2007

New forming technologies are being introduced to automotive manufacturing processes. Among them, a simultaneous forming is one of the innovative forming technologies to be able to reduce production time and cost. Several parts can be simultaneously manufactured by the process, while the conventional stamping demands the same number of die sets with the number of parts. In this study, the automotive rear floor side member was manufactured by the simultaneous forming. The position and the size of initial blank were determined by forming analyses and try-outs, and the blank movement during the forming was controlled by introducing the spotweld.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.273-280
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• 2000

Building structures which are in need of large open space make the damping effect of the structures decrease greatly. Assembly and office buildings with a lower natural frequency have a higher possibility of experiencing excessive vibration induced by human activities. These excessive vibration make the residents uncomfortable and the serviceability deterioration. The loads induced by human activities were classified into two types. First type is in place loads as like jumping, foot stamping and body bouncing. The other type is moving loads as like walking, running and dancing. A series of laboratories experiments had been conducted to study the dynamic loads induced by human activities, The earlier works were mainly concerned to parameters study of dynamic loads as like activity type, weight, sex, surface condition of structure and etc. In this paper, we have measured directly the walking loads by using the platform. And we have evaluated and analyzed load-time history of walking loads. One of the most important parameter is pacing rate (walking speed) in the walking loads. The difference between the maximum value and minimum value of walking loads depends on the walking speed.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.104-109
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• 2008

Nowadays, the researches for improving LCD manufacturing process and reducing cost are getting accelerated and additionally new types of process are widely developed. In this situation, APEM(Anti Photo Exposure Method) which does not need photo-lithography is realized as one of possible alternative of LCD process. APEM makes LCD pattern by stamping and it can reduce the process cost and process time because of its simplicity. But optical alignment between pattern glass and target glass is very critical fact to realize the precise patterns. So, the analysis of deflection of large size of glass is carried out and design of experiment method is applied for optimal design of jig.

• 한국정밀공학회지
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• 제25권1호
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• pp.171-177
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• 2008

The characteristics of sheet metal process are little loss of material during process, the short processing time and the excellent price and strength. It has been widely used in autobody, electronic components, aircraftbody, etc. Lancing is a press operation in which a single-line cut or slit is made on part way across the strip stock, without removing any metal. In this paper, we examined the validity of finite element method analysis on the automobile CTR-PLR -L/R stamping process by using the lancing engineering method. As a result, it has shown that the proper lancing engineering method could prevent fracturing by improving sheet metal flow.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.265.1-265.1
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• 2013

Nanoporous anodic aluminum oxide (AAO), a self-ordered hexagonal array has various applications for nanofabrication such as nanotemplate, and nanostructure. In order to obtain highly-ordered porous alumina membranes, Masuda et al. proposed a two-step anodization process however this process is confined to small domain size and long hours. Recently, alternative methods overcoming limitations of two-step process were used to make prepatterned Al surface. In this work, we confirmed that there is a specific tendency used a PDMS stamp to obtain a pre-patterned Al surface. Using the nanoindentaions of a PDMS stamp as chemical carrier for wet etching, we can easily get ordered nanoporous template without two-step process. This chemical etching method using a PDMS stamp is very simple, fast and inexpensive. We use two types of PDMS stamps that have different intervals (800nm, 1200nm) and change some parameters have influenced the patterning of being anodized, applied voltage, soaking and stamping time. Through these factors, we demonstrated the patterning effect of large scale PDMS stamp.

• 한국통신학회논문지
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• 제34권1B호
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• pp.86-97
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• 2009

실시간 위치 측정 시스템은 사람 또는 사물의 위치를 측정하고 추적하는 시스템이다. TDOA 기반의 실시간 위치 측정 시스템은 태그로부터 전달된 신호의 도착시간 차이를 이용하여 위치를 측정한다. TDOA 기반의 실시간 위치 측정 시스템에서 리더들 간의 도착시간 차이를 계산하기 위해서는 리더 간 시각 동기화가 필수적이다. 본 논문에서는 IEEE 802.15.4 네트워크에서의 실시간 위치 측정 시스템을 위한 정밀 시각 동기 시스템을 제안한다. IEEE 802.15.4 네트워크에서 정밀한 시각 동기를 이루기 위해서 본 논문에서는 네트워크 프로토콜 스택의 지연과 지터 등의 에러요인을 분석한다. 분석된 에러 요인들에 기반하여 하드웨어 시각 측정 장치를 개발하고, 칼만 필터를 적용하여 네트워크 프로토콜에서 발생하는 지연과 지터를 최소화하였다. 제안한 기법을 통하여 성능평가 결과, 실시간 위치 측정 시스템에서의 리더들은 상호간에 10나노초 이하의 시각 동기를 이루었다.

• 한국통신학회논문지
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• 제38C권2호
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• pp.141-154
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• 2013

신호수신장치들간 시각 동기화는 TDoA를 이용한 위치 탐지에 있어 가장 중요한 전제 사항이 된다. 본 논문에서는 시스템의 시각동기 정확도를 위하여 고정밀도의 OCXO와 DPLL을 이용하여 원자 클럭을 사용하는 GPS 위성으로부터 수신되는 1 pps(pulse per second) 신호에 위상동기 되는 방식을 제안한다. GPS 기반 고정밀 타이밍 레퍼런스의 성능은 근본적으로 매우 우수한 장기간에 걸친 주파수 안정도(long-term frequency stability)를 갖는 GPS 타이밍 신호의 특성을 따라간다고 볼 수 있으며, GPS 타이밍 신호에 동기가 되면 0.001 ppb(part per billion) 급의 초정밀 타이밍 레퍼런스를 통해 시각 동기의 정확도를 향상시킨다. 제안하는, 향상된 시각 동기 정확도를 통해 TDoA 기반의 위치 탐지 기술에서의 측정 오차를 평가하고, 시각동기 오차 개선 방법이 TDoA 기반의 위치 측정 오차를 크게 개선함을 보인다.