• Nuclear Engineering and Technology
• /
• 제51권4호
• /
• pp.996-1007
• /
• 2019

We investigated the influence of the aspect ratio (H/R) of the oxide layer on the reactor vessel heating in three-layer configuration. Based on the analogy between heat and mass transfers, we performed mass transfer experiments to achieve high Rayleigh numbers ranging from $6.70{\times}10^{10}$ to $7.84{\times}10^{12}$. Two-dimensional (2-D) semi-circular apparatuses having the internal heat source were used whose surfaces of top, bottom and side simulate the interfaces of the oxide layer with the light metal layer, the heavy metal layer, and the reactor vessel, respectively. Multi-cell flow pattern was identified when the H/R was reduced to 0.47 or less, which promoted the downward heat transfer from the oxide layer and possibly mitigated the focusing effect at the upper metallic layer. The top boundary condition greatly affected the natural convection of the oxide layer due to the presence of secondary flows underneath the cold light metal layer.

• 교육시설
• /
• 제13권2호
• /
• pp.50-60
• /
• 2006

In search of the improvement plan for elementary schools which aims at the efficient application of new educational programs according to the introduction of the 7th National Curriculum, the analysis results for the spatial configuration regarding the modernized elementary schools in Busan City are as follows: 1) The analysis of expansion in the building area reveals that the building area per classroom has been increased from $200m^2$ in 1995 to $350m^2$ in 2005 based on the data gathered from the constructed schools during that period. 2) While the ratio of classrooms per the gross school area has been decreased from 35% in the late 1990s to 20% in the 2000s, the entire school size continue to become larger, which is considered as desirable change. 3) New construction and addition of special classrooms and multi-purpose spaces have continued to be increased. Multi-purpose spaces were positively considered in the early 2000s, but recently built schools tend to limit the construction of multi-purpose spaces only to lower grades' space or not to obtain them owing to the analysis that its utilization is limited. 4) Most schools constructed after 1999 are equipped with dining hall and multi-purpose halls, and show the increase in their sizes. Especially, dining hall tend to be located on the upper floors for better environmental conditions.

• 한국안전학회지
• /
• 제16권3호
• /
• pp.12-18
• /
• 2001

The objective of the present work is to examine the effect of inclined angle of channel with multi heat source on thermal stability of electronic equipment. The heat sources are mounted on both sides of channel walls by two kinds of configuration such as the zig-zag md symmetric on. Conductive heat transfer was estimated by using of thermocouples and heat flux sensor. Thus, convective heat transfer and mean Nusselt number could be obtained. With increased inclined angle, the convective heat transfer coefficient was decreased. When inclined angle was smaller than 30 degree, The average Nusselt number of Big-zag configuration was larger than that of symmetric. Furthermore, when protruding ration was 0.082, the temperature was strongly affected by inclined angle. whereas, when protruding ration was 0.25, the temperature was strongly affected by heat source configuration.

• 한국측량학회지
• /
• 제27권3호
• /
• pp.385-392
• /
• 2009

본 연구의 목적은 멀티 GPS 센서를 이용하여 장대교량의 형상을 실시간으로 모니터링 하고 관리 할 수 있는 방안에 대하여 연구하는데 있다. 멀티 GPS 센서를 장대교량의 주요 지점에 설치하고 변위를 실시간으로 측정함으로써 장대교량의 3차원적인 형상거동을 관리 할 수 있을 것으로 판단된다. 본 연구에서 개발한 형상관리시스템은 교량의 전체적, 지점별 변위정보를 수치화, 시각화하고 위험발생에 따라 능동적으로 대응이 가능하며 측정데이터의 DB화를 통해서 계측정보를 실시간으로 관리하고 제공 할 수 있을 것으로 판단된다. 또한 GPS센서를 이용한 형상관리시스템은 GPS 센서를 이용한 장대교량의 3차원 절대변위 및 거대변위의 효과적인 측정에 의한 교량의 전체적인 형상관리에 활용할 수 있을 것으로 판단된다.

• Smart Structures and Systems
• /
• 제30권6호
• /
• pp.583-599
• /
• 2022

In this paper, a multi-objective wireless sensor network configuration optimization method is proposed. The proposed method aims to determine the optimal information and lifespan wireless sensor network for structural health monitoring of large-scale infrastructures. In particular, cluster-based wireless sensor networks with multi-type of sensors are considered. To optimize the lifetime of the wireless sensor network, a cluster-based network optimization algorithm that optimizes the arrangement of cluster heads and base station is developed. On the other hand, based on the Bayesian inference, the uncertainty of the estimated parameters can be quantified. The coefficient of variance of the estimated parameters can be obtained, which is utilized as a holistic measure to evaluate the estimation accuracy of sensor configurations with multi-type of sensors. The proposed method provides the optimal wireless sensor network configuration that satisfies the required estimation accuracy with the longest lifetime. The proposed method is illustrated by designing the optimal wireless sensor network configuration of a cable-stayed bridge and a space truss.

• Journal of the Korean Data and Information Science Society
• /
• 제14권2호
• /
• pp.237-245
• /
• 2003

MDS(multi-dimensional scaling) for preference data is a graphical tool which usually figures out how consumers recognize, evaluate certain products. This article is mainly concerned with an optimal scaling for MDS when target configuration is available. Rotation of axis and SUR(seemingly unrelated regression) methods are employed to get a new configuration which is obtained as close to the target as we can. Methodologies developed here are also illustrated via a real data set.

• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2003년도 춘계학술대회논문집
• /
• pp.258-261
• /
• 2003

In this study, finite element analysis for multi-stage deep drawing process of rectangular configuration with extreme aspect ratio is carried out especially for the blank design. The analysis of rectangular deep drawing process with extreme aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profile. In order to solve the difficulties, numerical approach using finite element method is performed in the present analysis and design. A series of experiments for multi-stage rectangular deep drawing process are conducted and the deformed configuration is investigated by comparing with the results of the finite element analysis. Additionally, to minimize amount of removal material after trimming process, finite element simulation is applied for the blank modification. The analysis incorporates brick elements for a rigid-plastic finite element method with an explicit time integration scheme using LS-DYNA3D.

• 한국전산유체공학회지
• /
• 제12권4호
• /
• pp.28-37
• /
• 2007

In this study, a multi-block structured grid deformation code based on a hybrid of a transfinite interpolation algorithm and spring analogy was developed. The configuration was modeled by a Bezier surface. A combination of the spring analogy for block vertices and the transfinite interpolation for interior grid points helps to increase the robustness and makes it suitable for distributed computing. An elliptic smoothing operator was applied to the block faces with sub-faces in order to maintain the grid smoothness and skewness. The capability of this code was demonstrated on a range of simple and complex configurations including an airfoil and a wing-body configuration.

• 정보처리학회논문지C
• /
• 제16C권6호
• /
• pp.753-760
• /
• 2009

시간과 장소에 상관없이 인터넷 서비스를 제공 받고자 하는 인터넷 사용자들의 요구가 증가함에 따라 MANET(Mobile Ad-Hoc Network) 환경에서도 인터넷 연결성을 제공하기 위한 연구들이 주목을 받고 있다. 기존 DHCP(Dynamic Host Configuration Protocol) 기반 방식의 경우는 망 내 노드들에게 주소를 할당하기 위하여 다중 홉 거리에 있는 DHCP 서버와 메시지를 교환해야 하기 때문에 메시지 손실이 쉽게 발생할 수 있으며, 이로 인해 주소 설정의 안정성이 감소하고 주소 설정 시간이 증가하는 문제점이 있다. 따라서 본 논문에서는 노드가 DHCP 서버로부터 하나의 주소만을 할당 받는 것이 아니라 일정 크기의 주소 영역을 할당 받을 수 있게 하였다. 또한 주소 영역을 할당 받은 노드가 이웃의 주소 요청 노드들에게 자신의 주소 영역 중 일부를 할당할 수 있도록 하는 새로운 주소 설정 기법을 제안하였다. 모의 실험을 통하여 제안 기법이 기존 DHCP 기법에 비하여 주소 설정 시간과 제어 메시지 수 측면에서 각기 77%와 61%의 성능을 향상시킬 수 있음을 보였다.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제7권1호
• /
• pp.36-42
• /
• 2007

A low-power compact driver for multistandard physical layer is presented. The proposed driver achieves low power and small area through the voltage-mode driver with trans-impedance configuration and the novel hybrid driver,. In the voltage-mode driver, a trans-impedance configuration alleviates the problem of limited common-mode range of error amplifiers and the area and power overhead due to pre-amplifier. For a standard with extended output swing, only current sources are added in parallel with the voltage-mode driver, which is named a 'hybrid driver'. The hybrid architecture not only increases output swing but reduces overall driver area. The overall driver occupies $0.14mm^2$. Power consumptions under 3.3-V supply are 24.5 mW for the voltage-mode driver and 44.5 mW for the hybrid driver.