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SIP 프록시 서버를 위한 우선순위 스케줄링 기반의 과부하 제어 알고리즘
이장현 ( Janghyun Lee ),조인휘 ( Inwhee Joe ) 한국정보처리학회 2011 한국정보처리학회 학술대회논문집 Vol.18 No.2
SIP (Session Initiation Protocol)는 사용자간의 멀티미디어 세션의 초기화, 변경 및 종료를 위한 응용 계층의 시그널링 프로토콜이다. SIP는 실시간 멀티미디어 서비스 통신에 많이 이용되기 때문에 주로 Unreliable Transport Protocol을 사용한다. 따라서 손실된 SIP 메시지들의 신뢰성을 보장하기 위하여 재전송 메커니즘을 제공한다. 하지만 이러한 재전송 메커니즘은 SIP 프록시 서버가 과부하 상황일 경우 신뢰성보다는 오버헤드가 증가되는 문제점을 가진다. 기존의 여러 SIP 과부하 제어 방법이 제안되었지만 네트워크 혼잡이 증가함에 따라 프록시 서버의 처리율이나 호 설정 시간의 지연 문제를 효율적으로 해결하지 못한다. 본 논문에서는 SIP 시그널링 네트워크에서 프록시 서버가 과부하 상황일 경우 낮은 호 설정 지연시간과 높은 처리율을 위해 우선순위 스케줄링 기반의 과부하 제어 알고리즘을 제안한다. 그리고 기존 과부하 제어에서 사용하는 알고리즘과 제안하는 알고리즘을 비교하여 보았다. 성능 평가 결과 부하에 따른 프록시 서버의 처리율과 호 설정 시간의 지연 측면에서 기존의 과부하 제어 알고리즘보다 향상됨을 보였다.
COVART 모델 기반의 함정 취약성 설계 및 평가 방법론 개발에 관한 연구
이장현(JangHyun Lee),김광식(KwangSik Kim) (사)한국CDE학회 2011 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2011 No.1
It is important to assess and improve the warship survivability for the weapon threats which have an critical effect on warship. Warship Survivability is defined as the capability of a warship to avoid or withstand a man-made hostile environment. The survivability of the warship consists of three categories (susceptibility, vulnerability and recoverability). Firstly, the susceptibility is defined as the inability of a warship to avoid radars, guns, missiles and ETC. Secondly, the vulnerability is defined as the inability of a warship to withstand the man-made hostile environment. Finally, the recoverability is defined as the ability of a warship to recover the damaged components and systems. This paper has described the vulnerability assessment for the hypothetical system which is composed of critical components. Also, the procedure based on the CAVART model is suggested to calculate the vulnerable probability of the damaged warship.
확률밀도함수(PDF)를 이용한 함정 피격성 분석 기법 연구
김광식(KwangSik Kim),이장현(JangHyun Lee),황세윤(SeYun Hwang),반일환(IlHwan Ban) (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.2
The survivability of the warship is defined as the capability of a warship to avoid or withstand a man-made hostile environment. The survivability of the warship consists of three categories (Susceptibility, Vulnerability and Recoverability). A warship performance in susceptibility terms is measured by the probability of detection, and probability of hit. So, the level of susceptibility of a warship in encounter with threat is dependent upon attributes for detection equipment and weapon system. This paper has described the theoretical procedure for the susceptibility assessment. And, the theoretical background which is suggested to assess the susceptibility of a warship is based on the simplified probabilistic theory. The main emphasis of this paper would be on simplified calculation model based on the probability density function for probability of hit. It implements assessment of the probability of hit given a both singlehit and multiple-hit. The susceptibility is accessed for a RCS (Radar Cross Section) and the hit probability for a rectangular target is applied for a given threat.
비규격 스틸커튼월 부재의 적용을 위한 로봇 레이저용접 성능에 관한 연구
나상호 ( Na¸ Sangho ),이장현 ( Lee¸ Janghyun ),박영미 ( Park¸ Youngmi ),김성진 ( Kim¸ Sungjin ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.2
In irregular curtain walls, the nominal stress required for each member varies greatly depending on the shape, so it is inefficient to design members based on the maximum required stress. Then, built-up members are absolutely necessary, but built-up members manufactured by Manpower-welding cannot be constructed in an irregular curtain wall building because it' not precise. In order to address the problems, this paper presents why Robotic-laser-welding should be used in irregular curtain walls using Gwanggyo Galleria Department Store involving 3D printing as an example. Results verify the performance of Robot-Laser-Welding as an efficient solution for precise steel curtain wall members.
나상호 ( Na Sangho ),이장현 ( Lee Janghyun ),박영미 ( Park Youngmi ),김성진 ( Kim Sungjin ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.1
3D printing has the unique advantage of the ability to customize freeform products even in small quantities. It was recently applied successfully in the node connection system for the irregular shaped glass design of Gwanggyo Galleria Department Store. This was achieved by applying 3D printing technology for an innovative smart node design. The novel system offers flexibility to address various design challenges in addition to maximizing construction quality and reducing construction period. In this paper, we aim to examine the use of 3D printing based innovative technologies in the construction industry. With this aim in mind, we present the case of the Gwanggyo Galleria Department Store's smart nodes. The key objective of this study is creating awareness in the construction industry of the need to utilize fourth industrial revolution technology in architecture.
오진우(JinWoo Oh),이장현(JangHyun Lee),김학선(HakSun Kim),이정호(JungHo Lee),이수혁(SooHyuk Lee),김한샘(HanSam Kim) 한국소음진동공학회 2015 한국소음진동공학회 학술대회논문집 Vol.2015 No.10
Various absorber is used in the noise reduction equipments and acoustic construction site. Representative absorbers are Glass-wool and Poly-ester. Both of them has a high absorption coefficient. When the absorber is installed, absorber is needed finishing, perforated plate and film, to maintain the shape, prevent scatter and keep from water. These finishing layer cause shift of the absorption coefficient. Experiment was performed at acoustic facility(reverberant room) by referring KS I ISO 2805 standard.
4-계층 모델 기반의 선박 수명주기관리 시스템 프레임워크
김승현(Seunghyun Kim),이장현(Janghyun Lee),이경호(Kyungho Lee),서흥원(Heungwon Suh) (사)한국CDE학회 2010 한국CDE학회 논문집 Vol.15 No.5
Product Lifecycle Management (PLM) is an integrated business approach to manage the creation and distribution of product information throughout the product development process. From the product perspective, PLM encompasses a holistic approach to product development and product information management. It supports the integrated product information in conjunction with the efficient product structures and BOM (Bill Of Material), user interfaces, proper functions, design processes and enterprise integration. Therefore, PLM should not only satisfy required functions as an enterprise software but also offer a systematic method for the efficient application from the initial stage of its development. Recently, many shipyards have been considering the PLM as a strategic solution to get the efficient management of product information such as 3-D models, BOM, drawings, documents, and the other product data. Though many studies on PLM are performed, most of them are performed in a function based approach adequate for mass productive assembly industries. It could not help having limitations on applying the proper PLM system to the shipbuilding business since the requirements of shipbuilding PLM are too diverse and huge to design the architecture. This study presents the PLM framework which effectively reflects the diverse requirements of shipbuilding PLM. In order to get the macroscopic architecture of shipbuilding PLM, authors suggest the four-tier architecture model which considers the various requirements collected from shipyards. Entities of ship design data are modeled BOM in terms of product structure and hierarchical class diagram. Applicable functions of shipbuilding PLM are also investigated by analysis of issues of ship design. Finally, by reflecting the design process of shipbuilding, To-Be ship design procedure cooperated with the suggested PLM framework has been summarized.