• Macromolecular Research
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• 제12권2호
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• pp.145-155
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• 2004

Facilitated transport membranes for the separation of olefin/paraffin mixtures have long been of interest in separation membrane science because olefins, such as propylene and ethylene, which are important chemicals in petrochemical industries, are currently separated by energy-intensive cryogenic distillation processes. Recently, solid polymer electrolyte membranes containing silver ions have demonstrated remarkable performance in the separation of olefin/paraffin mixtures in the solid state and, thus, they can be considered as alternatives to cryogenic distillation. Here, we review recent progress, and critical issues affecting in the use of facilitated olefin transport membranes; in particular, we provide a general overview with reference to carrier properties, transport mechanisms, and separation performance.

• 한국ITS학회 논문지
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• 제8권6호
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• pp.98-111
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• 2009

본 연구의 목적은 ITS 업무요령 및 ITS 성능평가 제도 개선을 위한 법.규정의 개정을 제안한다. 본 연구는 ITS 업무요령 및 ITS 성능평가 제도의 현황과 문제점을 분석하고 개선방안을 제시함으로써 신뢰성 있는 교통정보를 제공하고, 제도 개선을 통하여 민원 발생의 우려를 줄이며, 사회적 비용도 감소시키게 된다. 또한, ITS 장비와 센터의 유지관리 기준과 ITS 성능평가 업무의 직무분석을 통한 업무분담 체계화, ITS 성능평가기관의 역할 정립과 기술위원회의 기능을 정립하여 ITS 성능평가 제도 개선 하에서 생산되는 교통 자료의 신뢰성이 높아지고 새로운 차원의 서비스를 도출할 수 있어서 ITS 시스템의 효율성 증대 및 투자 효과의 극대화를 제공할 것이다.

• 한국통신학회논문지
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• 제18권9호
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• pp.1283-1294
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• 1993

큰 대역폭과 낮은 비트 에러율을 가진 고속망환경에서 기존의 낮은 대역폭과 놀은 비트 에러율을 가진 망환경에서 개발된 트랜스포트 프로토콜을 사용할 경우에 비효율적인 구조와 오버헤드로 인하여 성능이게 크게 저하한다. 따라서 고속망환경에 알맞는 새로운 프로토콜로 HSTP(High Speed Transport Protocol)가 제안되었다. 본 연구는 HSTP의 3가지 에러제어 기법과 TP4의 2가지 에러제어 기법을 이용했을 때의 성능과 HSTP의 rate control을 이용하여 흐름제어를 할 경우의 성능을 시뮬레이션 연구를 통하여 평가, 비교하였다.

• Journal of information and communication convergence engineering
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• 제7권3호
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• pp.241-246
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• 2009

Advances in mobile and wireless networking technologies have enabled mobile ad hoc networks applicable to a wide range of areas. Many cases of even such ad hoc networks demand to be accessible to the global network. Owing to be diversified in features depending on applications, however, some those networks may consist of devices or nodes which do not facilitate all the same transport protocols. This results in unreachable situations of establishing ad hoc network: such as non-existence of all required access points, faults or contention in a path of particular protocol communication. Interworking between different transport protocols can alleviate such problems. This paper proposes an interworking scheme to improve data transport performance and network accessibility, especially in such a mobile ad hoc network that is applicable to data communications among ships or user's convenient u-health services. Modeling and simulation analysis are used to verify the improvement.

• 한국정보통신학회논문지
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• 제13권1호
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• pp.60-66
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• 2009

유비쿼터스 네트워크 환경에서는 하나의 서비스를 제공하기 위하여 여러 가지 종류의 전달 프로토콜을 포함하는 다종 프로토콜 네트워크 환경이 될 수 있다. 이러한 다종 프로토콜 네트워크 환경에서 서로 다른 전달 프로토콜 간 연동성을 제공함으로써 네트워크 환경 구축을 위한 비용증가나 네트워크 환경의 미시설 또는 장애발생, 그리고 특정 전달 프로토콜 네트워크 환경으로의 트래픽 혼잡 등의 문제를 해소할 수 있다. 본 논문에서는 무선 네트워크를 구성하는 일부 노드에 SDR (Software Defined Radio)과 같은 기능을 부여함으로써 서로 다른 전달프로토콜을 포함하는 다종 네트워크의 전달성능을 향상시킬 수 있는 방안을 제시하고, 시뮬레이션 분석을 통하여 그 타당성과 전달성능이 향상될 수 있음을 보이고 그 결과를 제시한다.

• 한국정보과학회논문지:정보통신
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• 제33권1호
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• pp.28-37
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• 2006

최근 새로운 트랜스포트 계층 프로토콜인 SCTP를 기반으로 한 트랜스포트 계층 이동성 지원방안이 제안되었다. 본 논문에서는 이들 트랜스포트 계층 이동성 지원 방안이 지금까지 제안되어 온 대표적인 IPv6 기반 네트워크 계층에서의 이동성 지원 방안들에 비하여 어느 정도의 성능을 보이는지 그 위치를 가늠해 보고, 이들 각 프로토콜이 수반하는 오버헤드를 비교하였다 시뮬레이션 결과를 통하여 트랜스포트 계층에서의 종단 간 이동성 지원 방안이 네트워크 계층 이동성 지원 방안들이 수반하는 오버헤드보다 더 낮은 오버헤드를 가지며 전송 성능이나 핸드오버 지연 측면에서 MIPv6와 유사하거나 더 좋은 성능을 보임을 알 수 있었다.

• 한국정밀공학회지
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• 제12권7호
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• pp.92-98
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• 1995

In the cluster tool, it is necessary to precisely control the vacuum pressure for the wafer transportation between transport module and cassette or process modules with the range of 1*10$^{-4}$ to 5*10$^{-5}$ torr. So we have designed the pressure control system for the transport module of the cluster tool and have evaluated its performance. Digital PID is utilized with the weighted sum of both three previous errors and one current error. The feedback signal is put into the nitrogen mass flow controller using the transport module controller. This pressure control system can prevent the transport module from the particle generation and backstreaming of hazardous process gases of the process chamber.

• Computers and Concrete
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• 제31권6호
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• pp.485-499
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• 2023

Both damage and unsaturated conditions accelerate the transport of erosive media inside concrete. However, their combined effects have not been fully investigated. A multiscale mortar model using representative volume elements is developed, capturing the number and distribution in each phase. Afterwards, mortar damage microstructure evolution is simulated in the tensile process. Finally, the unsaturated mortar transport is predicted and analysed. The results indicate that damage significantly affects the diffusion process in the early stage, while the transport performance is weakened due to the obstruction of the nontransport phase in the later stage. The higher the saturation and the more connected pores, the faster the diffusion rate of chloride ions. Chloride ions spread around the cracks in a tree-like manner along. The model can very well predict the chloride ion transport performance of unsaturated and damaged mortar.

• 유통과학연구
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• 제15권11호
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• pp.59-72
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• 2017

Purpose - This paper evaluated the efficiency performance of the three major maritime transport markets and examined the determinants of the performance. The firms' revenue fluctuates with the changes of the economic cycle; hence it is important for them to set up business strategies to improve efficiencies. A lack of efficiency measurements for shipping firms leads to a significant gap in determining their overall performance. Research design, data, and methodology - Each of DEA scores was adopted for the evaluation and panel regression was used to examine the impact of determinants on the performance. The analysis included 50 shipping firms from three maritime transport markets as follows; 15 firms of container liners, 18 firms of bulk carrier and 17 firms of tanker carriers, and its period was from 2010 to 2016. Results - In the CCR model, container liners were the highest, tanker carriers were the second, and bulk carriers were the lowest in operation efficiency and financial efficiency. By region, operation efficiency and financial efficiency was high in the order of America, Asia, and Europe. Conclusions - This study suggests business strategies for maritime transport companies based on the analytical results of determinants of operational and financial efficiency.

• Nuclear Engineering and Technology
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• 제54권10호
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• pp.3766-3777
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• 2022

It is essential to ensure the safety of spent nuclear fuel (SNF) transport cask in drop situation that is included in transport accident scenarios. The safety of the drop situation is affected by the impact absorption performance of impact limiters. Therefore, when designing an impact limiter, the uncertainty in the material properties that affect the impact absorption performance must be considered. In this study, the material properties of the wood inside the impact limiter were selected as the variables for a parametric study. The sensitivity analysis of the drop response of the SNF transport cask with impact limiter was performed. The minimum wood strength required to prevent a direct collision between the cask and floor was derived from the analysis results. In addition, the plastic strain response was analyzed and strain-based evaluation was performed. Based on this result, the critical values of wood properties that change the impact dynamic characteristics were investigated. Finally, the optimal material properties of wood were obtained to secure the structural safety of the SNF transport cask. The results of this study can contribute to the development of SNF transport cask, thereby ensuring safety in transport accident conditions.