• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.187-187
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• 2013

알루미늄 표면에 산/알칼리 에칭법을 이용하여 복합구조를 형성시키고 소수성 물질을 코팅한 후 접촉각과 구름각을 측정하여 초발수 특성을 확인하였다. 표면의 복합구조는 전자현미경을 이용하여 정밀하게 관찰되었고 표면의 구조 및 잔류물에 따른 초발수 특성의 변화를 관찰하였다. 이는 향후 다양한 기능성 코팅 소재 분야에 유용하게 적용될 수 있을 것으로 기대된다.

• Proceedings of the Korean Society for Information Management Conference
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• 2003.08a
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• pp.245-251
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• 2003

이 연구에서는 통제된 색인어를 이용하여 파악한 지식 구조와 통제되지 않은 키워드를 이용한 지식 구조를 비교하여 두 구조가 어떤 차이점을 보이는지를 살펴보았다. 또한 색인효과가 어떻게 나타나는지, 비통제어를 사용한 경우가 실제적으로 더 상세한 하위 영역을 표현하는지를 확인하고자 하였다. 실험 결과 통제된 색인어인 주제명표목을 사용한 영역지도와 비통제 색인어인 키워드를 사용한 영역지도 둘 다 인공지능 분야의 주요 분야들을 비슷하게 나타냈지만, 주제명표목을 사용한 경우에 색인효과가 일부 나타났다. 그리고 대체적으로 주제명표목에 기반한 영역지도보다는 키워드에 기반한 영역지도가 더 상세하게 나타났다.

• Information and Communications Magazine
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• v.29 no.3
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• pp.41-48
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• 2012

최근 스마트폰의 도입과 더불어서 이동 인터넷 트래픽이 급증하고 있어서 미래 인터넷의 새로운 구조를 분석 및 연구할 때 이동성(Mobility)을 중요한 설계 요구사항으로 정하고 있다. 본 고에서는 미래 인터넷에서 이동 네트워크 구조 연구의 필요성에 대해 설명한다. 또한, 이동성 관리 연구에 있어서 최근에 많은 이슈가 되고 있는 분산/동적 이동성 관리에 대해 살펴보고 국내외의 여러 연구 그룹에서 제안하고 있는 대표적인 이동 네트워크 구조 및 연구 동향에 대해 기술한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1185-1188
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• 2002

대규모의 Network Management System 에서 고려되어야 할 점은 계층별로 관리구조가 정의 되어야 하며 또한 여러 정보를 수집 및 분석을 하기에 적합한 구조가 선행되어야 한다는 것이다. 이에 따라서 우리는 기본적인 망 관리시스템의 구조와 특성을 알아야 하며, 대규모의 에이전트기반 시스템에서의 설계 시 가장 중요한 안정성을 검증하는 방법을 실제 ATM PVC 구성의 예를 통해 알아보고자 한다. 이러한 예를 통해 Agent 시스템의 설계에 고려되어야 할 여러 가지 문제점들을 본 논문에서 제기하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10b
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• pp.42-44
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• 2000

본 논문에서는 최근 다양한 분야에 응용되고 있는 Computer-supported Cooperative work(CSCW)를 위한 새로운 구조적 모델을 제안한다. 본 논문에서는 제안하는 구조적 모델은 현재까지 만들어져온 CSCW 시스템 모델들의 특징과 구조를 분석하고서, 분산 환경을 기반 환경으로 해서 보다 객체 지향적으로 설계한 것으로서 완벽한 peer to peer의 구조를 취한다. DOVE(Distributed Objected-oriented Virtual Environment)라는 분산 환경 하에서 설계된 본 시스템은 DOVE가 제공하는 서비스의 하나인 객체 그룹 원격 호출(Object group method invocation)을 이용해서 객체들에 대해서 멀티캐스팅하는 방식을 사용했으며 이를 통해 cooperative work를 위한 최고의 성능을 제공할 수 있도록 설계되었다.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.5
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• pp.187-197
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• 2007

Experimental study for a submerged structure was conducted to protect coastal structures and shorelines. The rectangular submerged structure known as the most efficient shape among various submerged structures in the literature was fabricated at the nose of a rubble mound breakwater. The reflection coefficients and the run-up heights along the slope of a breakwater were measured for different significant wave heights and periods. It is found in this study that the reflection coefficient is affected more relatively by the significant wave period than the significant wave height and the run-up heights are reduced approximately 28% in terms of ${^{RU}}_{2%}$ and 26% in terms of ${^{RU}}_{33%}$, respectively, by the installation of a submerged structure inducing the interception and breaking of waves.

• Journal of Korea Multimedia Society
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• v.11 no.8
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• pp.1093-1100
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• 2008

Feistel and SPN are the two main structures in designing a block cipher algorithm. Unlike Feistel, an SPN has an asymmetric structure in encryption and decryption. In this paper we propose an SPN algorithm which has a symmetric structure in encryption and decryption. The whole operations in our SPN algorithm are composed of the even numbers of N rounds where the first half of them, 1 to N/2, applies function and the last half of them, (N+1)/2 to N, employs inverse function. Symmetry layer is executed to create a symmetry block in between function layer and inverse function layer. AES encryption and decryption algorithm, whose safety is already proved, are exploited for function and inverse function, respectively. In order to be secure enough against the byte or word unit-based attacks, 32bit rotation and simple logical operations are performed in symmetry layer. Due to the simplicity of the proposed encryption and decryption algorithm in hardware configuration, the proposed algorithm is believed to construct a safe and efficient cipher in Smart Card and RFID environments where electronic chips are built in.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.3
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• pp.59-67
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• 1993

The variations of the natural frequencies and the peak response acceleration at the top of prestressed concrete reactor building due to random variability and/or model uncertainty of structural parameters are studied. The results may be used as essential input parameters in seismic probabilistic risk assessment or seismic margin assessment of the reactor building. The sensitivity test of each structural parameter is first performed to determine the most influential parameter upon the natural frequency of structure model. Then Monte Carlo simulation technique is applied to evaluate the effect of parameter variation on the natural frequencies and the peak response acceleration. The acceleration time history is obtained by direct integration scheme. As the study results, it is found that the fundamental natural frequency and the peak response acceleration at the top of the building are most strongly affected by Young's modulus among the structural parameters, in which the value of mean plus one standard deviation obtained by probabilistic approach deviates up to about (+)12% from the result of deterministic method. Considering the uncertainty of flexural rigidity, the structural responses vary in range of (-)4%~(+)14%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1127-1132
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• 2013

The failure of reactor internals may have a significant effect on the safe operation and shutdown of a reactor. Various agings related to neutron irradiation occur or can potentially occur in the reactor internals owing to high neutron irradiation levels. Austenitic stainless steel, one of the principal materials constituting the reactor internals, shows different mechanical material behaviors such as tensile/creep properties and fracture toughness with neutron irradiation levels. This variation should be considered when the structural integrity of the reactor internals against agings during the design lifetime or continued operation period is evaluated. In this study, user subroutine programs considering the variation of mechanical material behaviors with neutron irradiation levels were developed. The programs were validated by testing them for various conditions.

• Composites Research
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• v.30 no.1
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• pp.15-20
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• 2017

In this study, LIPCA-S2 actuator with a piezoelectric single crystal layer and a carbon/epoxy layer was designed and evaluated to increase actuation performance of piezo-composite unimorph actuator. A curvature change model generated by the induced strain of a piezoelectric layer was used to predict the tip displacement of the piezo-composite unimorph cantilever. However, we found that there was big difference between the predicted and the measured tip displacement of LIPCA-S2 cantilever actuator when we used the previous linear prediction model. A new prediction model considering the change of piezoelectric strain coefficient and elastic modulus for the compression stress variation of the PMN-29PT single crystal layer was used and it was found that the difference between the predicted and the measured tip displacement reduced considerably.