• 한국공간구조학회논문집
• /
• 제6권3호
• /
• pp.111-121
• /
• 2006

들림형 보구조는 휨재와 뜬지주, 스트링으로 조합되는 구조로서, 스트링에 PS력을 도입하여 휨재의 응력과 변형을 조절함으로써 구조능력을 높이는 구조시스템이다. 기존의 연구결과와 실사례를 조사하여 들림형 보구조의 특성과 구조계획시 구성방식을 파악하였다. 그 결과, 연력도형의 보의 형상 및 높낮이 그리고 스트링의 sag설정, 평면배열, 뜬지주의 수와 구성이 설계인자로서 고려될 수 있음을 파악하였고, 실사례와 구조적 거동의 연구고찰을 통해 그 설계인자의 세부 구성방식을 나타내었다. 또한 들림형 보구조는 큰 부가하중이 작용할 때의 구조부담을 줄이기 위하여 부가하중에 대해 별도의 저항 메카니즘을 고안함으로써 구조효율을 높일 수 있는 방식이 고려될 수 있음을 보였다.

• 한국정보과학회논문지:시스템및이론
• /
• 제32권11_12호
• /
• pp.598-607
• /
• 2005

본 논문에서는 새로운 외부 메모리 인덱스 자료 구조인 접미사 B-tree를 제안한다. 접미사 B-tree는 String B-tree와 마찬가지로 문자열을 키로 가지는 B-tree이다. String B-tree의 노드는 복잡한 Patricia ie로 구현된 반면, 접미사 B-tree의 노드는 일반적인 B-tree처럼 배열로 구현되어 보다 간단하고 구현하기 쉽다. 그럼에도 불구하고 접미사 B-tree에서 배열을 이용하여 String B-tree만큼 효율적으로 분기를 찾을 수 있다. 결과적으로 문자열 알고리즘 분야에서 기본적이고 중요한 문제인 문자열 매칭을 String B-tree와 동일한 디스크 접근을 사용하여 수행할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제4권5호
• /
• pp.956-967
• /
• 2010

Rapid growth of internet applications has increased the importance of intrusion detection system (IDS) performance. String matching is the most computation-consuming task in IDS. In this paper, a new algorithm for multiple string matching is proposed. This proposed algorithm is based on the canonical Aho-Corasick algorithm and it utilizes a bidirectional and parallel processing structure to accelerate the matching speed. The proposed string matching algorithm was implemented and patched into Snort for experimental evaluation. Comparing with the canonical Aho-Corasick algorithm, the proposed algorithm has gained much improvement on the matching speed, especially in detecting multiple keywords within a long input text string.

• 한국공간구조학회논문집
• /
• 제19권3호
• /
• pp.69-76
• /
• 2019

A Beam String Structure (BSS) is a type of hybrid structures, which is composed of upper structural members, lower strings, and struts. Due to the advantages that the pre-tensioned strings elicit pre-caber of the upper structural members, the deflection can be greatly reduced without increasing the structural member size. In this study, a two-way beam string structure is proposed to endure bi-directional loading. The two-way beam string structure consists of two cable parts, namely, sagging and arch-shaped cables. A parametric study is presented aimed at proposing design guide lines of the two-way beam string structures. Numerical finite element analyses through the ABAQUS package were implemented to obtain their behaviors.

• Smart Structures and Systems
• /
• 제12권3_4호
• /
• pp.327-344
• /
• 2013

Beam string structure (BSS) is introduced as a new type of hybrid prestressed string structures. The composition and mechanics features of BSS are discussed. The main principles of wavelet packet transform (WPT), principal component analysis (PCA) and support vector machine (SVM) have been reviewed. WPT is applied to the structural response signals, and feature vectors are obtained by feature extraction and PCA. The feature vectors are used for training and classification as the inputs of the support vector machine. The method is used to a single one-way arched beam string structure for damage detection. The cable prestress loss and web members damage experiment for a beam string structure is carried through. Different prestressing forces are applied on the cable to simulate cable prestress loss, the prestressing forces are calculated by the frequencies which are solved by Fourier transform or wavelet transform under impulse excitation. Test results verify this method is accurate and convenient. The damage cases of web members on the beam are tested to validate the efficiency of the method presented in this study. Wavelet packet decomposition is applied to the structural response signals under ambient vibration, feature vectors are obtained by feature extraction method. The feature vectors are used for training and classification as the inputs of the support vector machine. The structural damage position and degree can be identified and classified, and the test result is highly accurate especially combined with principle component analysis.

• 한국음향학회지
• /
• 제27권8호
• /
• pp.395-402
• /
• 2008

바이올린, 비올라, 첼로, 콘트라베이스 등 비올족 현악기는 현의 진동이 브리지를 통해 몸체로 전달되고 공명을 일으켜 큰 소리를 내게 되어 있다. 즉 현악기에서는 현의 진동이 음원이 되며 현의 재질, 구조와 경계조건이 음색에 결정적 영향을 미치게 된다. 본 연구에서는 첼로에서 한쪽 끝은 고정되고 다른 끝은 손가락에 의해 운지된 현의 진동을 양 끝이 고정된 개방현의 진동과 비교하여 해석하고 실험하였다. 해석과 실험의 결과는 운지된 현의 진동이 양단이 고정된 개방현의 진동과 크게 다른 것을 보여준다. 또 운지된 현에서 손가락 끝과 현의 접촉 조건에 의해서도 음색이 크게 달라지므로 접촉조건을 조절함으로써 악기의 음색을 바꿀 수 있음을 설명해 준다.

• Nuclear Engineering and Technology
• /
• 제52권4호
• /
• pp.734-741
• /
• 2020

A new air-cooled waste heat removal system with a direct contact heat exchanger was designed for SMRs requiring 200 MW of waste heat removal. Conventional air-cooled systems use fin structure causing high thermal resistance; therefore, a large cooling tower is required. The new design replaces the fin structure with a vertical string type direct contact heat exchanger which has the most effective performance among tested heat exchangers in a previous study. The design results showed that the new system requires a cooling tower 50% smaller than that of the conventional system. However, droplet formation on a falling film along a string caused by Rayleigh-Plateau instability decreases heat removal performance of the new system. Analysis of Rayleigh-Plateau instability considering drag force on the falling film surface was developed. The analysis results showed that the instability can be prevented by providing thick string. The instability is prevented when the string radius exceeds the capillary length of liquid by a factor of 0.257 under stagnant air and 0.260 under 5 m/s air velocity.

• 한국공간구조학회논문집
• /
• 제13권4호
• /
• pp.49-56
• /
• 2013

Beam string structures(BSS) are one kind of efficient structure system because the bending moment in the beams is reduced greatly through the struts and the strings. As the struts in BSS are used as middle supports to the beam and always in compression, the buckling of the struts should be avoided. This paper investigates the lateral buckling of the struts in BSS. Firstly, the strut of a one-strut BSS is simplified into an analytical model by considering load is formulated and some special cases of the model are analyzed. Finally, the lateral buckling load of the strut is numerically examined by means of parameter studies. It is known that, because on end of the struts is jointed to the beam while the other end is connected to the strings, the buckling of the struts not only depends on the length of the struts and the stiffness of the joints, but also depends on the rise and the lateral stiffness of the beam, the layout of the strings and the number of the struts.

• 한국공간구조학회:학술대회논문집
• /
• 한국공간구조학회 2008년도 춘계 학술발표회 논문집
• /
• pp.127-132
• /
• 2008

최근, 지진하중에 대한 대공간구조무의 응답특성에 관한 연구가 다수 수행되었으며, 라이즈/스팬비가 큰 지붕구조에 대하여서는, 수평지진입력에 대한 역대칭모드의 증폭이 지배적으로 됨이 지적되었다. 본 연구에서 제안하는 정적지진하중평가법에서는, 라이즈가 있는 지붕구조의 내진설계를 수행함에 있어, 허용응력도설계법을 따르며, 그림1과 같이 설계용전단력를 지붕면에 따라 부가하는 정적평가법을 채용하고 이를 정적지진하중평가법이라 부르기로 한다. 본 논문의 구성으로서는, 정적평가법의 개념 및 정적설계식의 유도과정을 나타내고, 라이즈/스팬비가 서로 다른 지붕구조물을 대상으로 하여, 본 평가법에 의한 결과와 정적응답해석을 수행한 결과를 비교하고, 정적평가법의 타당성에 대하여 검토한다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2006년도 추계 학술대회논문집
• /
• pp.66-69
• /
• 2006

In the present study, we propose a virtual boundary method for simulation of massive inextensible flexible strings immersed in viscous fluid flow. The fluid motion is governed by the Navier-Stokes equations and a momentum forcing is added in order to bring the fluid to move at the same velocity with the immersed surface. A massive inextensible flexible string model is described by another set of equations with an additional momentum forcing which is a result of the fluid viscosity and the pressure difference across the string. The momentum forcing is calculated by a feedback loop. Simulations of several numerical examples are carried out, inlcuding a hanging string which starts moving under gravity without ambient fluid, a string swimming within a uniform flow and a uniform flow over two side-by side strings. The numerical results agree well with the theoretical analysis and previous experimental observations. Preliminary results of a swimming elongated fishlike body will also be presented.