• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.126-129
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• 2001

LIPCA (LIghtweight Piezo-composite Curved Actuator) is an actuator device which is lighter than other conventional piezoelectric ceramic type actuator. LIPCA is composed of a piezoelectric ceramic layer and fiber reinforced light composite layers, typically a PZT ceramic layer is sandwiched by a top fiber layer with low CTE (coefficient of thermal expansion) and base layers with high CTE. LIPCA has curved shape like a typical THUNDER (thin-layer composite unimorph feroelectric driver and sensor), but it is lighter an than THUNDER. Since the curved shape of LIPCA is from the thermal deformation during the manufacturing process of unsymmetrically laminated lay-up structure, an analysis for the thermal deformation and residual stresses induced during the manufacturing process is very important for an optimal design to increase the performance of LIPCA. To investigate the thermal deformation behavior and the induced residual stresses of LIPCA at room temperature, the curvatures of LIPCA were measured and compared with those predicted from the analysis using the classical lamination theory. A methodology is being studied to find an optimal stacking sequence and geometry of LIPCA to have larger specific actuating displacement and higher force. The residual stresses induced during the cooling process of the piezo-composite actuators have been calculated. A lay-up geometry for the PZT ceramic layer to have compression stress in the geometrical principal direction has been designed.

• 한국수소및신에너지학회논문집
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• 제21권6호
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• pp.540-546
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• 2010

In order to confirm the effect of Nafion ionomer content in catalyst layer on the performance of PEMFC, we have fabricated several electrodes which were prepared by varying the quantity of Nafion ionomer from 24 wt.% to 39 wt.% in catalyst layer. The effect of Nafion ionomer of each electrode was evaluated with cyclic voltammetry measurement. In addition, cell performance was obtained through single cell test using hydrogen and air. The Pt utilization and performance of single cell were changed by addition of Nafion ionomer to the electrode. Single cell fabricated with 33 wt.% of Nafion ionomer in catalyst layer showed the maximum Pt utilization and performance.

• 센서학회지
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• 제29권2호
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• pp.118-122
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• 2020

This paper proposes a specific sensor-design strategy and the possibility of improving the sensing performance, which can be obtained by replacing part of the existing plasmonic sensor based on the Kretschmann configuration method with an effective refractive-index layer. By replacing the metal layer with an effective refractive-index layer composed of gold and the material to be sensed, an improvement in the detection performance, accompanied by an increase in the sensed incident angle, is observed, and the gold-composition ratio that demonstrates the best result is presented. Subsequently, an increase in the sensed incident angle generated in the previous step can be suppressed by randomly etching a portion of the prism adjacent to the metal layer in a sub-wavelength scale. Finally, this study analyzes the optimization of the metal-layer thickness in a given sensor structure. An effective refractive thin-film surface plasmon resonance sensor design that can achieve optimal sensing performance is then proposed.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2004년도 춘계공동학술대회 논문집
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• pp.52-55
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• 2004

VMS (virtual manufacturing system) may be defined as a transparent interface/control mechanism to support human decision-making via simulation and monitoring of real operating situation through modeling of all activities in RMS (real manufacturing system). The three main layers in VMS are business process layer, manufacturing execution layer, and facility operation layer, and each layer is represented by a specific software system having its own input modeler module. The current version of these input modelers has been implemented based on its own 'local' framework, and as a result, there are no information sharing mechanism, nor a common user view among them. Proposed in this paper is a unified modeler framework covering the three VMS layers, in which the concept of PPR (product-process-resource) model is employed as a common semantics framework and a 2D graphic network model is used as a syntax framework. For this purpose, abstract class PPRObject and GraphicObject are defined and then a subclass is inherited from the abstract class for each application layer. This feature would make it easier to develop and maintain the individual software systems. For information sharing, XML is used as a common data format.

• 한국정보과학회논문지:정보통신
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• 제37권1호
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• pp.57-65
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• 2010

최근 카메라가 장착된 이동통신기기 환경에서 사용자로부터 정보의 입력을 위한 문자 인식 기술이 많이 요구되고 있다. 일반적으로 임베디드 환경에서 개발된 광학 문자 인식기(Optical Character Recognizer) 모듈은 특정 플랫폼에 대한 의존성 때문에 재사용하기 어렵다. 본 논문은 다양한 이동통신기기 환경에 쉽게 적용될 수 있는 광학 문자 인식기를 위한 소프트웨어 아키텍처를 제안한다. 제안된 아키텍처는 플랫폼 의존 지원계층, 인터페이스 계층, 엔진 지원계층 그리고 엔진 계층으로 나뉜다. 엔진 지원 계층에서는 다양한 하드웨어 엔디안 정책에 대응하기 위해 플러그인 데이터 구조를 지원한다. 제안된 아키텍쳐의 실제적인 적용을 통해 제안된 방법의 실효성을 보인다.

• Transactions on Electrical and Electronic Materials
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• 제18권5호
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• pp.253-256
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• 2017

A thin Te interlayer was applied to a Ni/n-InGaAs contact to reduce the contact resistance between Ni-InGaAs and n-InGaAs. A 5-nm-thick Te layer was first deposited on a Si-doped n-type $In_{0.53}Ga_{0.47}As$ layer, followed by in situ deposition of a 30-nm-thick Ni film. After the formation of the Ni-InGaAs alloy by rapid thermal annealing at $300^{\circ}C$ for 30 s, the extracted specific contact resistivity (${\rho}_c$) reduced by more than one order of magnitude from $2.86{\times}10^{-4}{\Omega}{\cdot}cm^2$ to $8.98{\times}10^{-6}{\Omega}{\cdot}cm^2$ than that of the reference sample. A thinner Ni-InGaAs alloy layer with a better morphology was obtained by the introduction of the Te layer. The improved interface morphology and the graded Ni-InGaAs layer formed at the interface were believed to be responsible for ${\rho}_c$ reduction.

• 한국압력기기공학회 논문집
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• 제11권2호
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• pp.45-50
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• 2015

In many cases, the field fracture mechanism of the thermoplastic pipe is considered as either brittle or environmental fractures. Thus the estimation of the lifetime by modeling slow crack growth considering such fracture mechanisms is required. In comparison of the some conventional and empirical equations to explain the slow crack growth rate such as the Paris' law, the crack layer theory can be used to simulate the crack and process zone growth behaviors precisely, so the lifetime of thermoplastic pipe can also be accurately estimated. In this study, the modified crack layer theory for the stress corrosion cracking (SCC) of high density polyethylene is introduced with detailed algorithm. The oxidation induction time of the HDPE is also considered for the reduction of specific fracture energy during exposed to chemical environments. Furthermore, the parametric study for an important SCC parameter is conducted to understand the slow crack growth behavior of SCC.

• 한국기후변화학회지
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• 제5권3호
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• pp.249-256
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• 2014

Permafrost is frozen soil below $0^{\circ}C$ for two or more years. Surface of permafrost is called as active layer that seasonally thaws during the summer. Although the thawing of permafrost may deepen the active layer and consequently increase the microbial activity, the microbial community structure in this habitat has not yet been well described. In this study, we presented bacterial and archaeal diversity in the active layer soil from Resolute, Canada using pyrosequencing analysis. The soil sample was collected from the surface of the marsh covered with moss and Carex. A total of 7,796 bacterial reads for 40 phyla and 245 archaeal reads for 4 phyla were collected, reflecting the high diversity of bacteria. Predominant bacterial groups were Proteobacteria (37.7%) and Bacteroidetes (30.0%) in this study. Major groups in Archaea were Euryarchaeota (51.4%) and Thaumarchaeota (46.1%). Both methane producing archaea and consuming bacteria were detected in this study. Although it might be difficult to characterize microbial community with only one sample, it could be used for the basis of assessing the relative importance of the specific groups with a high resolution on the bacterial and archaeal community in this habitat.

• 폴리머
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• 제29권3호
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• pp.300-303
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• 2005

폴리우레탄을 PU1000(poly(propylene glycol), PPG, 분자량 1000 g/mol로 제조된 폴리우레탄)과 PU2000(PPG 분자량 2000 g/mol로 제조된 폴리우레탄)을 이용하여 다층구조와 발포체 다층구조로 제조하였고 동력학 특성과 음향특성을 기준물질인 PU1000과 비교 조사하였다. 다층구조 폴리우레탄의 감쇠 피크는 PU1000에 비해 낮은 온도로 이동한 반면에 발포체를 이용한 다층구조에서의 감쇠 피크는 PU1000에 비해 높은 온도로 이동하였고 감쇠 범위 또한 넓어졌다. 음향특성인 투과손실 측면에서 보면 다층구조의 투과손실은 기준이 되는 PU1000에 비해 100 Hz이하와 600 Hz의 특정 주파수 영역에서 효과적이었고 발포체 다층구조의 경우는 실험 범위인 1000 Hz이하 전영역에서 아주 우수한 투과손실이 얻어졌다

• Ocean and Polar Research
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• 제39권4호
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• pp.257-267
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• 2017

Although Pacific mackerel (Scomber japonicus) is an important commercial species in Korea, its recruitment mechanism remains largely unknown. Diel vertical positioning of larvae in the water column, which is affected by their specific gravity and the surrounding water density, may help to provide an understanding on recruitment success through predator avoidance and prey availability. The specific gravity measurement on Pacific mackerel eggs and larvae would seem to be essential information necessary to learn about the transport process from spawning to nursery grounds, and consequently the recruitment success. Eggs were artificially fertilized, and larvae were fed with rotifer when their mouths opened 3-4 days after hatching. We conducted the experiment using a density gradient water column to measure the ontogenetic changes in specific gravity from fertilization to 10 days after hatching. Egg specific gravity was stable during most of the embryonic period, but a sudden increase to $1.0249g\;cm^{-3}$ happened just before hatching. However, the specific gravity of newly hatched larvae was much lighter ($1.0195g\;cm^{-3}$), and specific gravity tended to increase continuously after hatching. Comparison of specific gravity with seawater density reveals that eggs and newly hatched larvae can float in the surface layer of the ocean. For the later period of the experiment, the specific gravity showed a cyclic diel pattern: the highest in the evening while the lowest at dawn. The fullness of larval stomach may be responsible for the observed differences in specific gravity, because stomach fullness was lower (40-60%) at midnight, and higher (80-85%) in evening. The diel pattern of specific gravity might provide clues regarding how larvae match the diel vertical migration of prey organisms.