• 한국수학사학회지
• /
• 제18권4호
• /
• pp.125-134
• /
• 2005

이 논문에서는 평면영역의 해석함수에 대한 이론과 대표영역에 대하여 연구하였다. 다중연결 평면영역의 대표영역에 대한 소개 및 새로운 대표영역이 나오게 된 계기를 알아보고, 그 대표영역에 대한 성질을 조사하였다. 그리고 양해석적으로 동치인 영역들을 알아보았다

• 한국해양공학회지
• /
• 제32권5호
• /
• pp.333-340
• /
• 2018

This paper addresses the concept of the representative mean position, which was devised to improve the numerical efficiency of a time domain fatigue analysis of a mooring chain. To investigate the influence of an artificial offset of the floater on the fatigue of the mooring chain, a parametric study was performed on the moored FPSO under various combinations of offsets and environmental conditions. Tension time histories were calculated using the de-coupled analysis method, and fatigue damages were calculated to determine the influence of the offset. The parametric study was extended to a more realistic case to determine the actual effect of the representative mean position, where a comparison was made between the two different analysis results, one using the representative mean position and the other one using the actual mean position. It was confirmed that the application of the representative mean position guaranteed the conservatism of the fatigue damage with the enhanced numerical efficiency in the time domain fatigue analysis.

• 한국전자파학회지:전자파기술
• /
• 제2권4호
• /
• pp.66-73
• /
• 1991

This paper reviews two representative time-domain techniques for the simulation of the electromagnetic fields, which are known as FD - TD and TLM. The fundamental ideas of two tec- hniques are explained in detail. Also, the implimentation of the boundary conditions, the statability condition, and the representation of media in the problems are described briefly.

• 한국전자거래학회지
• /
• 제12권3호
• /
• pp.269-282
• /
• 2007

본 논문에서는 도메인 온톨로지를 사용하여 개인화 된 개념 기반의 검색 기법을 제안하였다. 제안 모델은 도메인 온톨로지를 이용한 컨텐츠의 대표 개념 추출, 컨텐츠 가중치와 개념 가중치를 이용한사용자 프로파일 구성 그리고 개인화 된 개념 기반 검색 과정으로 구성된다. 컨텐츠의 대표 개념은 TScore 기법을 이용하여 추출하였고, 사용자 프로파일은 개인 정보 수집 모듈을 통해 개념 가중치가 높은 개념을 대상으로 구성하였다. 개념 기반 검색을 위해 사용자 프로파일의 개념 집합과 컨텐츠의 대표 개념 집합간에 유사도를 비교하여 개인이 선호하는 개념의 우선순위에 의해 컨텐츠를 검색하였다. 본 논문에서 제안한 기법의 효율성을 검증하기 위하여 인터넷 사이트에서 컨텐츠를수집하고사용자프로파일을구성하여 실험하였다. 실험 결과, 제안한 검색기법이 기존의 기반의 검색 기법에 비해 우수함을 보였다. 제안된 기법은 개인화 된 추천 시스템이나 전자 도서관 등과 같은 분야에서 효율적으로 적용할 수 있으리라 기대된다.

• ETRI Journal
• /
• 제37권2호
• /
• pp.369-379
• /
• 2015

Fault management of virtualized network environments using user-driven network provisioning systems (NPSs) is crucial for guaranteeing seamless virtual network services irrespective of physical infrastructure impairment. The network service interface (NSI) of the Open Grid Forum reflects the need for a common standard management API for the reservation and provisioning of user-driven virtual circuits (VCs) across global networks. NSI-based NPSs (that is, network service agents) can be used to compose user-driven VCs for mission-critical applications in a dynamic multi-domain. In this article, we first attempt to outline the design issues and challenges faced when attempting to provide mission-critical applications using dynamic VCs with a protection that is both user-driven and trustworthy in a dynamic multi-domain environment, to motivate work in this area of research. We also survey representative works that address inter-domain VC protection and qualitatively evaluate them and current NSI against the issues and challenges.

• Journal of information and communication convergence engineering
• /
• 제15권4호
• /
• pp.244-249
• /
• 2017

Wearable sensor-based gait analysis has been widely conducted to analyze various aspects of human ambulation abilities under the free-living condition. However, there have been few research efforts on using wearable sensors to analyze human walking on an unstable surface such as on a ship during a sea voyage. Since the motion of a ship on the unstable sea surface imposes significant differences in walking strategies, investigation is suggested to find better performing wearable sensor-based gait analysis algorithms on this unstable environment. This study aimed to compare two representative gait event algorithms including time domain and frequency domain analyses for detecting heel strike on an unstable platform. As results, although two methods did not miss any heel strike, the frequency domain analysis method perform better when comparing heel strike timing. The finding suggests that the frequency analysis is recommended to efficiently detect gait event in the unstable walking environment.

• Earthquakes and Structures
• /
• 제7권6호
• /
• pp.1283-1301
• /
• 2014

Ground motion modification is extensively used in seismic design of civil infrastructure, especially where few or no recorded ground motions representative of the design scenario are available. A site in Los Angeles, California is used as a study site and 28 ground motions consistent with the design earthquake scenario are selected. The suite of 28 ground motions is scaled and modified in the time domain (TD) and frequency domain (FD) before being used as input to a bilinear SDOF system. The median structural responses to the suites of scaled, TD-modified, and FD-modified motions, along with ratios of he modified-to-scaled responses, are investigated for SDOF systems with different periods, strength ratios, and post-yield stiffness ratios. Overall, little difference (less than 20%) is observed in the peak structural accelerations, velocities, and displacements; displacement ductility; and absolute accelerations caused by the TD-modified and FD-modified motions when compared to the responses caused by the scaled motions. The energy absorbed by the system when the modified motions are used as input is more than 20% greater than when scaled motions are used as input. The observed trends in the structural response are predominantly the result of changes in the ground motion characteristics caused by modification.

• Journal of Theoretical and Applied Mechanics
• /
• 제3권1호
• /
• pp.16-33
• /
• 2002

A concept of hierarchical modeling, the newest modeling technology. has been introduced early In 1990. This nu technology has a goat potential to advance the capabilities of current computational mechanics. A first step to Implement this concept is to construct hierarchical models, a family of mathematical models which are sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics In their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-. plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical analysis of hierarchical models, two kinds of errors prevail: the modeling error and the numerical approximation errors. To ensure numerical simulation quality, an accurate estimation of these two errors Is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures Is derived using element residuals and flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error Indicators for two types of errors, in the energy norm. Comparing to the classical error estimators using flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.

• Structural Engineering and Mechanics
• /
• 제8권5호
• /
• pp.513-529
• /
• 1999

A concept of hierarchical modeling, the newest modeling technology, has been introduced in early 1990's. This new technology has a great potential to advance the capabilities of current computational mechanics. A first step to implement this concept is to construct hierarchical models, a family of mathematical models sequentially connected by a key parameter of the problem under consideration and have different levels in modeling accuracy, and to investigate characteristics in their numerical simulation aspects. Among representative model problems to explore this concept are elastic structures such as beam-, arch-, plate- and shell-like structures because the mechanical behavior through the thickness can be approximated with sequential accuracy by varying the order of thickness polynomials in the displacement or stress fields. But, in the numerical, analysis of hierarchical models, two kinds of errors prevail, the modeling error and the numerical approximation error. To ensure numerical simulation quality, an accurate estimation of these two errors is definitely essential. Here, a local a posteriori error estimator for elastic structures with thin domain such as plate- and shell-like structures is derived using the element residuals and the flux balancing technique. This method guarantees upper bounds for the global error, and also provides accurate local error indicators for two types of errors, in the energy norm. Compared to the classical error estimators using the flux averaging technique, this shows considerably reliable and accurate effectivity indices. To illustrate the theoretical results and to verify the validity of the proposed error estimator, representative numerical examples are provided.

• 대한치매학회지
• /
• 제22권1호
• /
• pp.1-15
• /
• 2023

The Seoul Neuropsychological Screening Battery (SNSB) is known as a representative comprehensive neuropsychological evaluation tool in Korea since its first standardization in 2003. It was the main neuropsychological evaluation tool in the Clinical Research Center for Dementia of South Korea, a large-scale multi-center cohort study in Korea that was started in 2005. Since then, it has been widely used by dementia clinicians, and further solidified its status as a representative dementia evaluation tool in Korea. Many research results related to the SNSB have been used as a basis for the diagnosis and evaluation of patients in various clinical settings, especially, in many areas of cognitive assessment, including dementia evaluation. The SNSB version that was updated in 2012 provides psychometrically improved norms and indicators through a model-based standardization procedure based on a theoretical probability distribution in the norm's development. By providing a score for each cognitive domain, it is easier to compare cognitive abilities between domains and to identify changes in cognitive domain functions over time. Through the development of the SNSB-Core, a short form composed of core tests, which also give a composite score was provided. The SNSB is a useful test battery that provides key information on the evaluation of early cognitive decline, analysis of cognitive decline patterns, judging the severity of dementia, and differential diagnosis of dementia. This review will provide a broad understanding of the SNSB by describing the test composition, contents of individual subtests, characteristics of standardization, analysis of the changed standard score, and related studies.