• Journal of the Korea Concrete Institute
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• v.15 no.2
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• pp.323-334
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• 2003

For performance-based design using nonlinear static analysis, it is required to predict the inelastic behavior of structural members accurately. In the present study, a nonlinear numerical analysis was peformed to develop the method describing the moment-curvature relationship of structural wall with boundary confinement. Through the numerical analysis, variations of behavioral characteristics and failure mechanism with the arrangement of vertical reinforcement and the length of boundary confinement were studied. According to the analysis, the maximum moment-carrying capacity of structural walls with adequately confined boundary elements is developed at the moment the unconfined concrete reaches the ultimate compressive strain. Walls with flexural re-bars concentrated on the boundaries fails in a brittle manner. As vortical re-bars in the web increases, the brittle failure is prevented and a ductile failure occurs. Based on the findings, moment-curvature curves for walls with a variety of re-bar arrangement were developed. According to the proposed relationships, deformability of the structural walls wth boundary confinement increases as the compressive strength of the confined concrete increases compared to the applied compressive force.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.563-570
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• 2015

The existing research on the damage detection method for building structures has considered the damages from the excessive loadings such as the earthquake. However, the structural performance of building structures could be reduced due to the deterioration based on the chloride, carbonation during the long-term time. Thus, to effectively manage the healthiness of structures, the deterioration influences on the structures should be checked. In this study, the corrosion of rebars by the chloride is considered as the deterioration factor. To consider the structural performance reduction of the corroded rebars, the yield strength, cross-sectional area, rupture strain of rebars and the compressive strength of cover concrete based on the corrosion level are estimated. These properties of rebars and cover concrete are used for the procedure to evaluate the structural performance reduction of structural member level and the building level. The moment-curvature analysis is performed to evaluate the structural performance reduction of structural member level. Also, the eigenvalue analysis and the pushover analysis are performed to investigate the natural period and mode shape and the strength and deformation performance of buildings, respectively.

• Science of Emotion and Sensibility
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• v.7 no.3
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• pp.15-25
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• 2004

The regression analysis and Adaptive -Network based Fuzzy-inference system (ANFIS) were applied to the explanation on human's visual texture of cotton fabrics with 7 mechanical properties. The ANFIS uses the structure with fuzzy membership function and neural network. The results obtained by the statistical analysis through the coefficient of correlation and regression analysis showed that subjective texture had a linear relationship with mechanical properties. But It had a relatively low coefficient of determination and was difficult that the statistical analysis explained other relationship with the exception of a lineality and interaction among mechanical properties. Comparing the statistical analysis, the ANFIS was an effective tool to explain human's non-linear perceptions and their interactions. But to apply ANFIS to human's perceptions more effectively, it is necessary to discriminate effective input variables through controlling the properties of samples.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.289-294
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• 2015

Linear mixed models are commonly used in the clinical pharmaceutical studies to analyze repeated measures such as the crossover study data of bioequivalence studies. In these models, random effects describe the correlation between repeated outcomes and variance-covariance matrix explain within-subject variabilities. Bioequivalence analysis verifies whether a 90% confidence interval for geometric mean ratio of Cmax and AUC between reference drug and test drug is included in the bioequivalence margin [0.8, 1.25] performed using linear mixed models with period, sequence and treatment effects as fixed and sequence nested subject effects as random. A Levofloxacin study is referred to for an example of real data analysis.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.118-121
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• 2010

초대형 플로팅 구조물의 상부구조는 육상 구조물과는 달리 파랑하중의 영향을 받기 때문에 하부부체의 변형에 의해서 상부구조물에는 부가 모멘트가 크게 발생한다. 이와 같은 부가모멘트의 저감을 위하여 보-기둥 접합부에 반강접의 도입에 관한 연구와 반강접의 비선형 거동을 고려한 상부구조물의 연구는 초기단계이다. 본 연구에서는 초대형 플로팅 구조물의 상부구조물에 정적하중과 진폭의 크기가 다른 파랑하중이 동시에 작용할 경우 강접 골조와 부분적으로 반강접 접합부가 사용된 상부구조체에 대한 1, 2차 소성해석을 수행하였다. 접합부는 웨브에 더블 앵글을 가진 상하 앵글(TSD)접합을 적용하였으며 상부 구조물에 파랑하중이 작용할 경우 소성거동에 따른 응답특성에 대하여 분석하였다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.265-271
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• 2014

304L stainless steel sheets are used as a primary barrier for the insulation of membrane-type liquefied natural gas(LNG) carrier cargo containment system. 304L stainless steel is a transformation-induced-plasticity(TRIP) steel that exhibits complex material behavior, because it undergoes phase transformation during plastic deformation. Since the TRIP behavior is very important mechanical characteristics in a low-temperature environment, significant amounts of data are available in the literature. In the present study, a uniaxial tensile test for 304L stainless steel was performed to investigate nonlinear mechanical characteristics. In addition, a viscoplastic model and damage model is proposed to predict material fractures under arbitrary loads. The verification was conducted not only by a material-based comparative study involving experimental investigations, but also by a structural application to the LNG membrane of a Mark-III-type cargo containment system.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.4
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• pp.629-639
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• 2024

CHAM is designed with an emphasis on encryption speed, considering that in the ISO/IEC standard block cipher operation mode, encryption functions are used more often than decryption functions. In the superscalar architecture of modern general-purpose processors, different ordering of operations can lead to different processing speeds, even if the computation configuration is the same. In this paper, we analyze the implementation efficiency and security of CHAM-like structures, which rearrange the order of operations in the ARX-based block cipher CHAM, for single-block and parallel implementations in a general-purpose processor environment. The proposed structures are at least 9.3% and at most 56.4%efficient in terms of encryption speed. The security analysis evaluates the resistance of the CHAM-like structures to differential and linear attacks. In terms of security margin, the difference is 3.4% for differential attacks and 6.8%for linear attacks, indicating that the security strength is similar compared to the efficiency difference. These results can be utilized in the design of ARX-based block ciphers.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.3
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• pp.193-201
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• 2023

In this study, a nonlinear truss finite element is developed to analyze structures with negative Poisson effect-induced tensile buckling. In general, the well-known buckling phenomenon is a stability problem under a compressive load, whereas tensile buckling occurs because of local compression caused by tension. It is not as well-known as classical buckling because it is a recent study. The mechanism of tensile buckling can be briefly explained from an energy standpoint. The nonlinear truss finite element with a torsional spring is formulated because the finite element has not been reported in the literature yet. The post-buckling analysis is then performed using the generalized displacement control method, which reveals that the torsional spring plays an important role in tensile buckling. Structures that mimic a negative Poisson effect can be constructed using such post-buckling behaviors, and one of the possible applications is a mechanical switch. The results obtained are compared to those of analytical solutions and commercial finite element analysis to assess the validity of the proposed finite element model. The numerical results show that the developed finite element model could be a viable option for the basic design of nonlinear structures with a negative Poisson effect.

• Proceedings of the KIEE Conference
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• 2006.10d
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• pp.194-196
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• 2006

본 논문에서는 새로 개발된 전력품질 보상 장치의 성능을 실험실에서 효과적으로 분석하기 위해 필요한 새로운 부하모의장치를 제안하였다. 제안하는 부하 모의장치는 2대의 PWM 인버터가 직류 단을 공유한 구조로 선형과 비 선형부하를 단일기기로 시험 가능하도록 설계되어 있다. 그리고 전력품질보상기의 하나인 능동전력필터와 연계시험을 수행하였다. 본 논문에서는 제안하는 부하모의장치와 능동전력필터의 연계 특성을 분석할 목적으로 PSCAD/EMTDC 소프트웨어를 이용하여 시뮬레이션 실시하였고 또한 실적용시 타당성을 검증할 목적으로 20kVA 용량의 부하모의장치와 10kVA용량의 능동전력필터를 제작하여 실험을 실시하였다. 시뮬레이션과 하드웨어 실험결과 제안하는 부하모의장치는 능동전력필터의 다양한 보상 능력 검증에 충분히 활용가능함을 알 수 있었다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.609-610
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• 2011

최근 친환경 생활이 강조되는 오늘날, 자전거(bicycle) 이용자 수가 급격히 늘어나고 있다. 때문에 2륜 자전거의 무인화 및 다양한 기구학적 재해석과 구조학적 재해석을 시도하고 있으며 공학적으로 활발한 연구가 진행되고 있다. 본 논문은 복잡한 2륜 자전거의 복잡한 동역학 방정식을 분석한 결과 인버터 팬들럼 모델과 유사한 점을 수학적 전개를 통하여 알 수 있었다. 이렇게 근사화된 방정식 모델을 바탕으로 비선형 제어 알고리즘을 통하여 비선형 제어기를 설계하여 2륜 자전거의 주행 안정성에 대한 진행속도와 조향각(steering angle) 제어에 대한 상관관계에 대한 연구를 시뮬레이션을 통하여 결과를 분석하고자 한다. 이러한 분석을 통한 2륜 자전거의 자세제어를 통하여 기타 로봇의 자세제어 및 다양한 시스템에 적용 가능성을 제시하고자 한다.