• 정보처리학회논문지C
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• 제8C권1호
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• pp.1-11
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• 2001

전통적으로 프로그램이 갖춰야 할 품질조건으로 정확성, 신뢰성, 효율성, 호환성, 이식성 등 여러 가지가 제안되어 왔지만, 최근에는 보안성이란 새로운 항목이 요구되고 있다. 보안성은 설계된 프로그램의 흐름을 사용자가 임의로 변경함으로써 보안 침해수단으로 사용하는 사례가 늘어나면서 그 중요성이 더욱 강조되고 있다. 이러한 보안 침해기법은 기본적으로 스택의 조작에서부터 출발한다. 스택과 관련된 일련의 동작들은 프로세서에 따라 고유하게 이루어지고, C 언어는 그러한 고유한 특성에 따라 스택을 관리한다. 본 논문에서는 스택 조작을 통한 보안침해의 개념을 살펴보고, 팬티엄(Pentium), 알파(Alpha), 스파크(SPARC) 등이 제공하는 스택 메커니즘을 자세히 조명해 본 후, 그 것들이 프로그램의 보안성에 어떻게 영향을 미치는지를 규명함으로써 안전 한 프로그램 작성을 위한 치침에 기여하도록 한다.

• Structural Engineering and Mechanics
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• 제46권2호
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• pp.213-229
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• 2013

Although performance based assessment procedures are mainly developed for reinforced concrete and steel buildings, URM (Unreinforced Masonry) buildings occupy significant portion of buildings in earthquake prone areas of the world as well as in IRAN. Variability of material properties, non-engineered nature of the construction and difficulties in structural analysis of masonry walls make analysis of URM buildings challenging. Despite sophisticated finite element models satisfy the modeling requirements, extensive experimental data for definition of material behavior and high computational resources are needed. Recently, nonlinear equivalent frame models which are developed assigning lumped plastic hinges to isotropic and homogenous equivalent frame elements are used for nonlinear modeling of URM buildings. The equivalent frame models are not novel for the analysis of masonry structures, but the actual potentialities have not yet been completely studied, particularly for non-linear applications. In the present paper an effective tool for the non-linear static analysis of 2D masonry walls is presented. The work presented in this study is about performance assessment of unreinforced brick masonry buildings through nonlinear equivalent frame modeling technique. Reliability of the proposed models is tested with a reversed cyclic experiment conducted on a full scale, two-story URM building at the University of Pavia. The pushover curves were found to provide good agreement with the experimental backbone curves. Furthermore, the results of analysis show that EFM (Equivalent Frame Model) with Dolce RO (rigid offset zone) and shell element have good agreement with finite element software and experimental results.

• 한국건축시공학회지
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• 제12권4호
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• pp.401-414
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• 2012

The adoption of Green Frame is expected to provide economic benefits, since construction costs are reduced by the in-situ production of precast concrete column and beam. The cost reduction can ultimately be realized by saving transportation costs and the overhead and profit of PC plants. The cost structure of Green Frame, which is built up using composite precast concrete members, is similar to that of a bearing-wall structure, but the difference in construction process has resulted in some cost differences for a few items. In particular, production and installation is the principal work involved in Green Frame made by precast concrete members, while form and concrete work is the principal work for a bearing-wall structure. As such, the rental time and fee for a tower crane should be compared through time analysis. To verify reliability, this study focused on developed residential projects to estimate the construction costs. Through this analysis, it was found that the costs of Green Frame were 1.57% lower than the costs of bearing-wall structure. The results of this study will help in the development of a management plan for the structural work of Green Frame.

• 공학논문집
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• 제3권1호
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• pp.139-146
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• 1998

프레임 릴레이는 다양한 네트워크를 연결하기 위하여 사용되는 고속광역네트워크 기술이다. 패킷교환방식과 회선교환방식의 장점을 결합함으로써, 프레임 릴레이는 오늘날 기업의 다양한 업무환경에 적합한 고성능/고신뢰도의 통신 서비스를 제공한다. 본 논문에서는 프레임 릴레이기술의 기본개념 및 특징을 정리하고, 표준화현황을 고찰하였으며, 국내의 프레임 릴레이 산업 및 서비스 현황을 분석하였다. 또한, 프레임 릴레이를 이용한 기업망 원격접속 다이얼-업 서비스를 위한 시험망을 구성하여, 프레임 릴레이 다이얼-업 서비스의 기능 및 비용효과를 분석하였다.

• 한국정보통신학회논문지
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• 제21권12호
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• pp.2279-2284
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• 2017

비면허 대역(Unlicensed)을 사용한 최근 무선통신이 증가하고 있으며 사용범위도 점차 넓어지고 있다. 비면허 대역은 통신 장비 간에 간섭을 용인하는 전재조건과 비면허통신 증가로 주파수 중첩과 간섭 현상이 증가하고 있다. 특히 2.4GHz 대역을 사용하는 블루투스, 무선랜, 무선식별 시스템(RFID)의 간섭 현상은 심각해지고 있다. 이러한 환경의 도심지에서는 무선 전송매체 상태가 간섭과 방해전파의 환경이 대부분일 것이다. 방해전파환경에서 효과적 전송을 할 수 있는 방법은 대략 2가지로 생각할 수 있다. 첫 번째는 IEEE 802.11의 RTS/CTS방식이 있고 두 번째로는 프레임 분할(fragmentation)방식이 있다. 본 논문에서는 방해전파 환경에서 일정크기 이상의 프레임을 전송할 경우 무선 환경의 간섭으로 전송이 어려워진다. 이러한 환경에서 신뢰성 전송과 효율적 전송을 하기 위해 프레임을 일정한 작은 단위로 분할하여 전송하여 효과적 전송과 신뢰성을 확보한 프레임분할 전송기법을 구현하여 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5459-5473
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• 2017

Recently, a tracking algorithm called the spatial-temporal context model has been proposed to locate a target by using the contextual information around the target. This model has achieved excellent results when the target undergoes slight occlusion and appearance changes. However, the target location in the current frame is based on the location in the previous frame, which will lead to failure in the presence of fast motion because of the lack of a prediction mechanism. In addition, the spatial context model is updated frame by frame, which will undoubtedly result in drift once the target is occluded continuously. This paper proposes two improvements to solve the above two problems: First, four possible positions of the target in the current frame are predicted based on the displacement between the previous two frames, and then, we calculate four confidence maps at these four positions; the target position is located at the position that corresponds to the maximum value. Second, we propose a target reliability criterion and design an adaptive threshold to regulate the updating speed of the model. Specifically, we stop updating the model when the reliability is lower than the threshold. Experimental results show that the proposed algorithm achieves better tracking results than traditional STC and other algorithms.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.489-494
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• 2001

This paper develops a finite element model for frontal crash analysis of a large-sized truck. It is composed of 220 parts, 70,041 nodes and 69,073 elements. This paper explains only major parts' models in detail such as frame, cab, floor, and bumper which affect on crash analysis a lot. In order to prevent penetration not only at a part itself but also between parts, all contact areas are defined using type-36, self-impact type. The developed model's reliability is validated by comparing simulation and crash test results. The results used for model validation are vehicle pulses at B-pillar, and frame and deformation of frame and cab. The frontal crash simulation is performed with the same conditions as crash test. And, it is performed using PAM-CRASH installed in super-computer SP2. The developed model whose reliability is verified may be used as a base to develop a finite element model for occupant behavior and injury coefficient analysis.

• Structural Engineering and Mechanics
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• 제63권2호
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• pp.259-268
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• 2017

In this paper, the incremental nonlinear dynamic analysis is used to evaluate the seismic performance of steel moment frame structures. To this purpose, three special moment frame structure with 5, 10 and 15 stories are designed according to the Iran's national building code for steel structures and the provisions for design of earthquake resistant buildings (2800 code). Incremental Nonlinear Analysis (IDA) is performed for 15 different ground motions, and responses of the structures are evaluated. For the immediate occupancy and the collapse prevention performance levels, the probability that seismic demand exceeds the seismic capacity of the structures is computed based on FEMA350. Also, fragility curves are plotted for three high-code damage levels using HASUS provisions. Based on the obtained results, it is evident that increase in the height of the frame structures reduces the reliability level. In addition, it is concluded that for the design earthquake the probability of exceeding average collapse prevention level is considerably larger than high and full collapse prevention levels.9.

• Physical Therapy Rehabilitation Science
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• 제12권3호
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• pp.259-267
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• 2023

Objective: Rehabilitative ultrasound imaging is a safe and noninvasive technique for evaluating muscle thickness. A dual probe-fixing frame (DPF) can provide visual feedback during exercises targeting specific muscles. The purpose of this research was to verify the reliability and validity of the DPF for dual-probe ultrasound (DPU)-based visual feedback exercises, allowing users to use both hands freely. Design: This cross-sectional study used repeated measures to compare muscle thickness measurements obtained using the handheld device and DPF with DPU. Methods: Twenty healthy adults participated in the study. Measurements were taken over two sessions, with a two-day interval between the sessions. The thicknesses of the rectus abdominis (RA) and transverse abdominis (TrA) muscles were measured using DPU. The DPF with DPU developed by the research team, was used along with a laptop-based muscle viewer. Bland-Altman analysis and intraclass correlation coefficients (ICCs) calculations were used in statistical analyses to evaluate agreement and reliability, respectively. Results: The results of the Bland-Altman analysis showed small average differences between the handheld and DPF methods for both RA and TrA muscle thicknesses. Inter-rater reliability analysis showed high ICC values for DPF measurements of both RA (0.908-0.912) and TrA (0.892-741) muscle thicknesses. Intra-rater reliability analysis also showed good ICC values for measurements taken by a single examiner over two days. Conclusion: The findings of this study demonstrate that the DPF provides reliable and valid measurements of muscle thickness during visual feedback exercises using the DPU.

• Earthquakes and Structures
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• 제2권3호
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• pp.279-295
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• 2011

This paper develops a probabilistic methodology for the seismic reliability analysis of structures with random properties. The earthquake loading is assumed to be described in terms of response spectra. The proposed methodology takes advantage of the response spectra and thus does not require explicit dynamic analysis of the actual structure. Uncertainties in the structural properties (e.g. member cross-sections, modulus of elasticity, member strengths, mass and damping) as well as in the seismic load (due to uncertainty associated with the earthquake load specification) are considered. The structural reliability is estimated by determining the failure probability or the reliability index associated with a performance function that defines safe and unsafe domains. The structural failure is estimated using a performance function that evaluates whether the maximum displacement has been exceeded. Numerical illustrations of reliability analysis of elastic and elastic-plastic single-story frame structures are presented first. The extension of the proposed method to elastic multi-degree-of-freedom uncertain structures is also studied and a solved example is provided.