• 한국세라믹학회지
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• 제47권6호
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• pp.623-626
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• 2010

We synthesized ZnO nanowires patterned on Si substrate and investigated the field emission properties of the nanowires. Firstly, Au catalyst layers were fabricated on Si substrate by photo-lithography and lift-off process. The diameter of Au pattern was $50\;{\mu}m$ and the pattern was arrayed as $4{\times}4$. ZnO nanowires were grown on the Au catalyst pattern by the aid of Au liquid phase. The orientation of the ZnO nanowires was vertical on the whole. Sufficient brightness was obtained when the electric field was $5.4\;V/{\mu}m$ and the emission current was $5\;mA/cm^2$. The threshold electric field was $5.4\;V/{\mu}m$ in the $4{\times}4$ array of ZnO nanowires, which is quite lower than that of the nanowires grown on the flat Si substrate. The lower threshold electric field of the patterned ZnO nanowires could be attributed to their vertical orientation of the ZnO nanowires.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.111-114
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• 2003

In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternating field vertically to the EPD field has been developed for the first time and applied to the electrophoretic deposition process. The applied alternating electric field caused a force to be exerted on each YBCO particle and resulted in a shaking of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. The usual commercial electrical power was used for the vertically applied alternating voltage and the induced electric field was 25-120 V/cm at 60Hz. The thick film fabricated by the method developed in this paper showed better surface uniformity without crack and porosity and improved film characteristics such as critical temperature ($T_{c,zero}$ : 90 K) and critical current density ($2354\;A/cm^2$). Therefore, it is expected that the shaky-aligned electrophoretic deposition method can be used to fabricate superconductor films through a simpler process and at less expense.

• Applied Microscopy
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• 제45권1호
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• pp.23-31
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• 2015

Dark field (DF) transmission electron microscopy image has become a popular characterization method for two-dimensional material, graphene, since it can visualize grain structure and multilayer islands, and further provide structural information such as crystal orientation relations, defects, etc. unlike other imaging tools. Here we present microstructure of graphene, particularly, using DF imaging. High-angle grain boundary formation wass observed in heat-treated chemical vapor deposition-grown graphene on the Si substrate using patch-quilted DF imaging processing, which is supposed to occur by strain around multilayer islands. Upon the crystal orientation between layers the multilayer islands were categorized into the oriented one and the twisted one, and their local structure were compared. In addition information from each diffraction spot in selected area diffraction pattern was summarized.

• Journal of Advanced Marine Engineering and Technology
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• 제27권1호
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• pp.100-107
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• 2003

This study was to control magnetic field orientation-typed sensorless vector control by applying the theory of a rotor flux observer to drive an induction motor. This research suggested a new speed estimation method that estimates speed with the rotor flux obtained by using a flux observer and the variable of state current detected by a current sensor without a speed sensor. Because the speed estimation method is independent from the motor constants, it is not necessary to control the gain of the parameters and the algorithm is simple. In the findings of the study, the researcher was convinced of the control function and the possibility of realization in the simulation experiment of sensorless vector control system by using DSP(Digital Signal Prosessor).

• 멤브레인
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• 제4권2호
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• pp.96-105
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• 1994

이 논문은 거대전하고분자의 막전달 현상을 위한 이론적 모델을 연구하는데 있다. 전기적 힘에 의한 전하고분자 물질의 형상은 빠르게 곧게 뻗으면서 진행되며, 곧게 뻗는 시간과 길이는 막 전달의 동적현상을 이해하는데 도움을 주고 있다. 빠르게 곧게 뻗을 때, 전하고분자의 두 끝이 전기힘 방향으로 동시에 끌리는 현상이 일어난다. 이같은 형식의 이해는 거대전하고분자의 막분리를 이해하는데 도움을 주고 있다.

• Journal of the Korean Wood Science and Technology
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• 제42권3호
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• pp.346-355
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• 2014

소나무의 가도관과 유연벽공의 미세구조를 연구하는데 공초점반사현미경법을 이용하여 획득한 3차원 화상을 사용하였다. 가도관 유연벽공의 토러스, 마르고, 벽공연의 미세구조가 명확하게 관찰되었으며, 교분야벽공의 미세구조로 가도관과 방사유세포 사이의 연결구조 및 방사유세포 내의 역학적 지지구조도 관찰할 수 있었다. 가도관 세포벽의 3차원 화상에서는 S1, S2, S3층과 이 층들의 사이에 있는 이행층의 존재도 확인할 수 있었다. 또한 S3층과 S2층의 마이크로 피브릴 배향의 관찰이 가능하였고, 유연벽공 주변의 복잡한 마이크로피브릴 배향 특성도 직접적으로 확인할 수 있었다. 본 연구의 결과 공초점반사현미경법은 소나무 가도관의 세포벽, 유연벽공, 교분야벽공의 미세구조를 연구하는데 유용하게 이용될 수 있는 현미경 기법으로 여겨졌다.

• 품질경영학회지
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• 제37권3호
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• pp.102-122
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• 2009

In this study, we will conduct an empirical study to see how the 3PL firm's logistics service quality and relationship orientation affects the supply chain performance. To examine the research model and hypotheses, we have used an empirical method based on the field survey in which most of measurements used and verified in previous studies are selected as measurements. The results of our empirical study can be summarized as follows: First, it can be shown that higher level of logistics service quality not only affects satisfaction and relationship orientation positively, but also improves supply chain performance. Second, it can be also shown that satisfaction for logistics service quality affects relationship orientation between shipper and 3PL firm positively. Finally, it can be shown that relationship orientation affects supply chain performance positively. This paper presents much implications both theoretical and practical side.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1675-1682
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• 2017

This paper deals with three dimensional orientation estimation algorithm for an attitude and heading reference system (AHRS) based on nine-axis inertial/magnetic sensor signals. In terms of the orientation estimation based on the use of a Kalman filter (KF), the quaternion is arguably the most popular orientation representation. However, one critical drawback in the quaternion representation is that undesirable magnetic disturbances affect not only yaw estimation but also roll and pitch estimations. In this paper, a sequential direction cosine matrix-based orientation KF for AHRS has been presented. The proposed algorithm uses two linear KFs, consisting of an attitude KF followed by a heading KF. In the latter, the direction of the local magnetic field vector is projected onto the heading axis of the inertial frame by considering the dip angle, which can be determined after the attitude KF. Owing to the sequential KF structure, the effects of even extreme magnetic disturbances are limited to the roll and pitch estimations, without any additional decoupling process. This overcomes an inherent issue in quaternion-based estimation algorithms. Validation test results show that the proposed method outperforms other comparison methods in terms of the yaw estimation accuracy during perturbations and in terms of the recovery speed.

• 한국IT서비스학회지
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• 제15권1호
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• pp.1-18
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• 2016

Recently, in the bio-field success stories of ventures through a biosimilar technology is being excavated. but the growth of ICT industry has been stagnant since reaching a boom in the dissemination of early high-speed internet in 2000s. The purpose of this study is to explore the factors of change of business model and business strategy of ICT ventures and SMEs with the evolution of the digital ecosystem, and to drive the factors to be competitive on the global value chain. The researcher selected an entreprenuership, market-innovation orientation, technology-innovation orientation, and Administration-innovation orientation as internal factors influencing the global competence and healthiness of the ecosystem as external factors. The researcher applied samples of 94 ICT Venture and SMEs to a research model, and adopted 5 hypotheses. The researcher believes that only a few hypotheses were adopted because it takes time for overall innovation orientation of ICT Venture and SMEs to result in the real global competence as the their innovation orientation is still on the level of domestic market. And the researcher also thinks that only healthiness of the ecosystem affected management performances because the companies' performances of the last 3 years were so weak that the correlation between innovation orientation of each company and the performances were not big enough.

• Journal of Welding and Joining
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• 제27권6호
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• pp.62-67
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• 2009

Friction stir welding (FSW) was carried out for Al-Mg-Si series aluminum alloys which are being used for automotive body structure. Consequently, Post weld heat treatment (PWHT) was applied to the friction stir welds to evaluate the effect of the paint baking process which is one of the automotive fabrication process on friction stir welded zone (FSWZ) in 443K for 1.2Ks. Grain structure and its crystal orientation distribution was measured about both the as welded specimens and the post weld heat treated specimens. An optical microscope (OM) and an field emission scanning electron microscope (FE-SEM) was used for observing the grain structure and measuring its crystal orientation distribution, respectively. Changes on the grain structure and its crystal orientation distribution were not detected. From the present results, it was confirmed that the paint baking process after FSW do not affect on the grain structure and its crystal orientation distribution of FSWZ. The comprehensive investigations will be performed for various automotive aluminum alloys manufactured by different processes, in the future.