• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.82-82
• /
• 2010

유기 쌍안정성 소자는 비휘발성 기억 소자 중에서 구조가 간단하고 제작비용이 저렴하며 유연성을 가지기 때문에 많은 연구가 진행되고 있다. 현재 유기물/무기물 나노복합소재를 사용하여 소자 성능 향상이 기억소자의 성능 향상을 위하여 여러 가지 유기물/무기물 나노복합소재를 사용하여 제작한 유기 쌍안정성 소자가 유연성을 가진 비휘발성 기억소자로 대두되고 있다. 본 연구에서는 ZnO 나노입자를 포함한 PMMA 복합층을 사용하여 제작한 유기 쌍안정성 기억소자를 제작하여 메모리 특성을 조사하였다. 이와 더불어 활성층에 효과적인 전하주입을 위하여 전극과 PMMA/ZnO 층 사이에 $C_{60}$ 층을 삽입한 구조를 가진 메모리 소자의 성능 향상에 대하여 연구하였다. Indium tin oxide 가 증착된 유리 기판위에 $C_{60}$ 층을 스핀코팅 방법으로 적층하였다. 1 wt% ZnO 나노입자와 1 wt% PMMA를 혼합하여 스핀코팅 방법으로 $C_{60}$ 층 위에 박막을 형성하였다. 그리고, 전극으로 Al을 열증착으로 형성하였다. $C_{60}$ 층이 있는 유기 쌍안정성 기억 소자와 $C_{60}$ 층이 없는 두 가지의 소자에 대하여 전류-전압 (I-V) 특성을 측정하여 각각의 소자에서의 전류 히스테리시스 현상이 발생하는 원인을 규명하였다. I-V 특성 결과와 전자적 구조를 사용하여 유기 쌍안정성 소자에서의 쓰기, 지우기 및 읽기 동작에 대한 과정을 설명하였다. 두 소자의 I-V 특성을 비교하므로 $C_{60}$ 층을 사용하여 유기 쌍안정성 소자의 성능이 향상됨을 알 수 있었다. 또한 $C_{60}$ 층을 사용하여 제작된 유기 쌍안정성 소자의 성능이 향상된 원인을 규명하였다.

• Proceedings of the Korean Society for Information Management Conference
• /
• 1998.08a
• /
• pp.133-136
• /
• 1998

본 연구는 대학도서관의 효율적인 조직구조의 형성방안을 위하여 대학 도서관 조직구조의 상황변수, 기본변수, 구조형태 및 조직유효성 간에 상호영향을 미치는 요인을 규명하고자 한 것으로서 이론적인 배경을 토대로 연구모형을 설계한 후에 실증적인 검증을 시도하였다. 이 검증을 위하여 상황변수는 환경, 기술, 규모, 전략유형, 권력유형을 채택하고, 기본변수는 복잡화, 공식화, 집권화를 채택하였으며, 구조형태는 단순조직, 기능별조직, 분관조직, 주제별조직(I)(II)로 구분하였고, 조직유효성 변수는 능률성, 유연성, 정보자료관리 및 만족성을 채택하였으며, 만족성은 조직몰입과 직무만족으로 세분하였다. 연구결과 조직구조의 상황변수, 기본변수 및 구조형태는 상호간에 영향을 주며, 궁극적으로 조직유효성에 영향을 주지만 그 내용은 극히 미약한 것으로 나타났다. 그리고 모든 측면에서 조직유효성이 높은 조직은 없고, 조직유효성에 영향을 미치는 구조형태는 극히 미약한 것으로 분석되었다.

• Proceedings of the Korean Information Science Society Conference
• /
• 1999.10c
• /
• pp.451-453
• /
• 1999

멀티미디어 멀티캐스트에서의 통신 관리를 위한 기존의 많은 방법들은 인터넷이나 ATM망 같은 특정 전송환경에 의존적이었고, 효율적인 통신 관리 메카니즘이 부족했다. 본 논문에서는 다양한 멀티미디어 멀티캐스트 어플리케이션에 적용될 수 있는 유연하고 확장 가능한 통신 관리 구조를 정의한다. 이 구조는 제어와 터미널의 분리를 통해 원격제어 및 이동 제어가 가능하게 함으로서 다양한 방법으로 서비스를 이용할 수 있는 환경을 제공하며, 호 제어와 연결 제어를 분리하여 연결자원의 효율적인 사용을 가능케 했으며, 연결제어를 위해 기존의 프로토콜의 접합을 사용함으로서 네트워크 환경에 독립적인 환경을 제공할 수 있고, 기존 전송 네트워크의 최소한의 수정 및 구조의 실용성 증가를 기대할 수 있다.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.9 no.4
• /
• pp.182-193
• /
• 1997

The interaction of monochromatic incident waves with a horizontal flexible membrane is investigated in the context of two-dimensional linear hydro-elastic theory. First, analytic diffraction and radiation solutions for a submerged impermeable horizontal membrane are obtained. Second, the theoretical prediction was compared with a series of experiments conducted in a two-dimensional wave tank at Texas A & M University. The measured reflection and transmission coefficients reasonably follow the trend of predicted values. Using the developed computer program, the performance of surface-mounted or submerged horizontal membrane wave barriers is tested with various system parameters and wave characteristics. It is found that the properly designed horizontal flexible membrane can be an effective wave barrier.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.21 no.1
• /
• pp.1-11
• /
• 2008

Stiffness estimation of a shear building due to local damages is usually achieved though structural analysis based on the assumed material properties and idealized numerical modeling of structure. Conventional numerical modeling, however, frequently causes an inevitable error in the structural response and this makes it difficult to exactly predict the damage state in structure. To solve this problem, this paper introduces a damage detection technique for shear building using genetic algorithm. The introduced algorithm evaluates the damage in structure using a flexibility matrix since the flexibility matrix can exactly be obtained from the field test in spite of using a few lower dynamic modes of structure. The introduced algorithm is expected to be more effectively used in damage detection of structures rather than conventional method using the stiffness matrix. Moreover, even in cases when an accurate measurement of structural stiffness cannot be expected, the proposed technique makes it possible to estimate the absolute change in stiffness of the structure on the basis of genetic algorithm. The validity of the proposed technique is demonstrated though numerical analysis using OPENSEES.

• Polymer(Korea)
• /
• v.30 no.1
• /
• pp.56-63
• /
• 2006

We have synthesized two types of diamine monomers containing various chain length to prepare polyimides with layered structure. By using these diamines, homo-polyimides and co-polyimides having hydrophobic and hydrophilic segment of flexible side chain were synthesized. The segregated layered structures were formed by repulsive force with main chain as the side chains reach a critical length because the rigid main chains are packed into layered structure with the flexible side chains occupying the space between layers. As a result, the gallery space of each homo-polyimide was increased at spacing of $32.7\~48{\AA}\;or\;7\~10.5{\AA}$ as the increased hydrophobic or hydrophilic side chain length through X-ray diffraction. The gallery space of co-polyimides was also showed similar phenomenon by repulsive force of side chains with different properties. We have also confirmed that gallery space and molar volume were significantly depended on length of flexible side chain via molecular modeling.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.19 no.2 s.72
• /
• pp.171-185
• /
• 2006

A sophisticated reliability analysis method is proposed to evaluate the reliability of real nonlinear complicated dynamic structural systems excited by short duration dynamic loadings like earthquake motions by intelligently integrating the response surface method, the finite element method, the first-order reliability method, and the iterative linear interpolation scheme. The method explicitly considers all major sources of nonlinearity and uncertainty in the load and resistance-related random variables. The unique feature of the technique is that the seismic loading is applied in the time domain, providing an alternative to the classical random vibration approach. The four-parameter Richard model is used to represent the flexibility of connections of real steel frames. Uncertainties in the Richard parameters are also incorporated in the algorithm. The laterally flexible steel frame is then reinforced with reinforced concrete shear walls. The stiffness degradation of shear walls after cracking is also considered. The applicability of the method to estimate the reliability of real structures is demonstrated by considering three examples; a laterally flexible steel frame with fully restrained connections, the same steel frame with partially restrained connections with different rigidities, and a steel frame reinforced with concrete shear walls.

• Journal of Digital Convergence
• /
• v.17 no.6
• /
• pp.297-305
• /
• 2019

The purpose of this study was to examine resilience and empathy on the relation between humanity and friendship of the early adolescents using structural equation modeling. The subjects were total 332 students of the 5th and 6th grade in elementary school and 1st and 2nd grade in junior school. The data were collected by means of the self-report questionnaire. The results of this study were as follows: Firstly, the direct effect of humanity on resilience, empathy, and friendship was found. Resilience also influence friendship directly, but empathy did not affect friendship. Secondly, humanity had influence on friendship partially mediated by resilience, but not mediated by empathy. This result shows that resilience was better mediated between humanity and friendship than empathy. Additionally, sex differences were found on empathy, but the differences were not found on resilience. The results revealed that the adolescents who scored high on humanity were better at friendship and when the higher humanity score was, the higher level of resilience was found, and this had an indirect effect on friendship quality.

• Journal of the Korea Society of Computer and Information
• /
• v.15 no.5
• /
• pp.93-101
• /
• 2010

Although various network management architectures such as centralized, distributed, and hybrid have been presented, any one is not always efficient in all the environment. In this paper, we propose a hierarchical and split network management architecture based on MA+SNMP in order to manage a network of many small NEs distributed over the wide area. Our hierarchical architecture has MA-based proxy management nodes for the flexibility and overhead reduction in NMS as well as SNMP-based NEs considering NE's capacity. Through the analysis with real experiments, we show that our proposal improves some drawbacks and the processing delay of the existing architectures in the given environment.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.4
• /
• pp.21-29
• /
• 1987

In this paper the liquid sloshing effects in vertical storage tanks under earthquake loadings are studied. The study focuses on the investigation of the effect of the flexibility of the tank wall on the hydrodynamic forces exerted on it. The tank structure is modelled using finite elements. The motion of the liquid is expressed by the Laplace equation. The equation of motion of the fluid shell system is formulated including the coupling effect between the shell motion and the sloshing motion. A procedure is developed to obtain the natural frequencies and the mode shapes of the sloshing motion as well as the shell vibration. Dynamic analyses have been carried out for several tanks with different dynamic characteristics utilizing the time history method as well as the response spectra method.