• Computers and Concrete
• /
• v.19 no.6
• /
• pp.641-649
• /
• 2017

The discovery of the Interfacial Transition Zone (ITZ) by Farran in 1956 initiated a new era in the study of the behaviour of concrete. Acknowledged as the weak link, this ITZ was studied extensively, numerically as well as experimentally. While the complementary experimental tests illustrated the visual behaviour of this specimen under increasing monotonic compression loading, a perfect bond within the ITZ has also been studied by using finite element analysis for comparison purposes. Finite element analysis was used to evaluate the degree of correctness and precision of the proposed ITZ model. This paper discusses the use of the cutoff bar in finite element modeling, representing the ITZ of a single aggregate (inclusion) in a mortar matrix. Experiments were conducted to investigate the influence of the ITZ model on the single inclusion specimen's strength. The model was tested for some inclusions that varied in dimension and shape. The effect of inclusion shape on the stress concentrations of the specimens was examined. The aim of this research work is to propose a simple yet accurate ITZ model to be used in the commercially available finite element software packages.

• International Journal of Aeronautical and Space Sciences
• /
• v.18 no.1
• /
• pp.56-62
• /
• 2017

Because adhesively bonded joints are used in many structural systems, it is important to predict accurate adhesive strengths. Composite aircraft with many joints are easily exposed to low temperatures and high relative humidity. This paper presents a humidity aging effect on the adhesive strength of a composite single-lap joint (SLJ). The adhesive strength of the SLJ is predicted using a finite element analysis with a cohesive zone model (CZM) technique. The humidity aging effect is evaluated based on the adhesive strength and CZM parameters. A lap joint test is carried out on the composite SLJ specimens, which are exposed for four months of 100% R.H. at $25^{\circ}C$. The predicted strengths are in good agreement with experimental data, and the actual crack propagation is satisfactorily simulated using the local CZM technique.

• Journal of the Korean Geotechnical Society
• /
• v.24 no.8
• /
• pp.53-60
• /
• 2008

In this study, various kinds of behavior characteristics such as deformation area zone of back ground, failure angle and rotation point are examined on the laterally loaded single pile in the homogeneous ground through a model test. The main obtained conclusions are summarized as follows; In the back ground of single pile to which the lateral load is applied, failure surface shows almost linear movement characteristics and it is inclined to converge to constant values no matter how the length of pile and the pile head displacement.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.577-580
• /
• 2003

Stress state of chip formation zone is one of the main problems in metal cutting mechanics. In two-dimensional case this process is usually considered as consistent shears of work material along single of several shear surfaces. separating chip from workpiece. These shear planes are assumed to be trajectories of maximum shear stress forming corresponding slip-line field. This paper suggests new approach to the constriction of slip-line field, which Implies uniform compression in chip formation zone. On the base of given model it has been found that imaginary shear line in orthogonal cutting is close to the trajectory of maximum normal stress and the problem about its determination have been considered. It has been shown that there is a second central slip-line field inside chip, which corresponds well to experimental data about stress distribution on tool rake face and tool-chip contact length. The suggested model could be useful in solution of various problems of machining.

• Transactions of the Korean hydrogen and new energy society
• /
• v.20 no.4
• /
• pp.344-351
• /
• 2009

A multi-zone model was used to predict the operating range of homogeneous charge compression ignition (HCCI) engine, the boundaries of the operating range were determined by knock (presented by ring intensity), misfire (presented by sensitivity of indicated mean effective pressure to the initial temperature). A HCCI engine fueled with Di-Methyl Ether (DME) was simulated under different initial temperature and equivalence ratios, and the operating range was well produced by the model. Furthermore, the model was applied to develop the operating range for thermal stratification in the preceding condition of initial temperature and equivalence ratios. The computations were conducted using Senkin application of the CHEMKINII kinetics rate code.

• Journal of Advanced Marine Engineering and Technology
• /
• v.29 no.3
• /
• pp.251-259
• /
• 2005

A discrete time model reference adaptive control has been applied in order to compensate the nonlinear friction characteristics in a hydraulic proportional position control system. As nonlinear friction, static and coulomb friction forces are considered and modeled as dead zone and external disturbance respectively. The model reference adaptive control system consists of a cascade combination of the dead zone. external disturbance and linear dynamic block. For adaptive control experiment. the DSP(Digital Signal Processor) board has been interfaced the hydraulic proportional position control system. The experimental results show that the MRAC(Model Reference Adaptive Control) for compensation of static and coulomb friction are very effective.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.2
• /
• pp.133-141
• /
• 2005

The behavior of the ground in crossed zone due to the excavation of new lower tunnel rectangularly crossed to that was studied by model tests and numerical analysis in shallow cover. Results of the model tests show that earth pressure of the ground in crossed zone were redistributed due to the longitudinal arching effect by the excavation of lower tunnel. By the numerical analysis, minimum principal stress in crown of single tunnel has more decrease than parallel tunnel or crossed tunnel. Vertical stress at rectangularly crossed tunnel decrease more than single tunnel by stress shadow.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.9
• /
• pp.1139-1147
• /
• 2000

This paper describes that the size of inactive zone can be directly applied to design multiblade fan/scroll system. From the experimental studies using a five hole pitot tube and smoke test, it is found that the size of inactive zone has linear relations with the mean velocity of impeller inlet and cut-off angle gives a great influences to the fan efficiency. For the practical design, a function related with geometric parameters(i.e. inner radius, cord length, cut-off clearance and cut-off angle) of fan/scroll system is suggested. By using these formulas, the size and distribution of inactive zone can be predicted without the measurements through the full domain, it can be possible to use them to know the efficiency improvement for new model designed.

• Journal of Advanced Marine Engineering and Technology
• /
• v.32 no.8
• /
• pp.1269-1277
• /
• 2008

Ships at sea cannot exchange data among them easily so far. Basically voice-oriented communication systems are the main methods, some of them utilize the HF radio systems at lower bit rates, and for higher bit rates, the Inmarsat or VSAT are adopted. None of them are used widely because of lower qualities and higher costs. There exist many technical and economical limits to have the Internet service just like on land such as the WWW service. In order to achieve the improved transmission rates of the maritime communication networks at farther sea, MANET(Mobile Ad Hoc Network) is one of the most practical models. In this paper, a new routing protocol named EZR (Expansive Search Zone Routing Protocol) is proposed, which is based on SANET (Ship Ad Hoc Network) model that has some different features from MANET and VANET (Vehicular Ad Hoc Network). The search zone for the shortest path is firstly found by EZR. If no path is searched in the zone, the zone is expanded according to the rule of EZR. The zone-expanding and path-searching procedures are repeated until the path is found out. The performance of EZR is evaluated and compared with LAR protocol which is one of the most typical routing protocols based on geographical information. The simulated results show that EZR is much better than LAR at sea environments in terms of routing success rate, route optimality, and a single index of performance combined the previous two metrics.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.29 no.4
• /
• pp.57-67
• /
• 2023

Purpose: Recently, the operating unit remodeling compititon has been increasing rapidly in Korea, but there are no design infomation for spatial planning of sterile supply storage. Therefore, the propose of this study is to present area composition of the operating unit after remodeling. Methods: For literature review, the 6 studies and guidelines of operating unit(guidelines in the U.S, Australia, UK and Korea and 2 studies in Korea) conducted surveys and analysis. Room and space composition and zone of operating unit are redefined for this study. For obtaining area, to conduct masuring and calcuating of document of operating unit before and after remodeling in 3 cases. There are some patterns of plan in operaing unit by sterile supply storage. This study derived data for attributes of area composition of sterile supply storage. Results: The results of this study are as follows: First, Reviewing previous studies and Guidelines, for this study the suggested model was 5 zones(Operating zone, Support zone, Patient zone, Staff zone, Circulation zone) and redefined each room and space. Second, For infection control, sterile supply storage was provided to directly accessible to the operating room. Third, According to ralation of operting room and sterile supply storage, there are two types : 'double loaded type' and 'single loded type'. Sterile supply storage shall increase area of ciculation zone. Implications: This study can be used as primary data on remodeling of operating unit. In addition, it suggests that for infect control sterile supply storage is functional area.