• 한국정보통신설비학회:학술대회논문집
• /
• 2007.08a
• /
• pp.22-26
• /
• 2007

In the fibre to the home (FTTH) era, it is expected that broadband network provisioning will require thousands of optical fibres to be accommodated in a central office for optical access networks. An optical fibre line testing system could be used to reduce maintenance costs and improve service availability depending on the PON's element manager capabilities and the maintenance procedures adopted by the network supplier. When monitoring optical fibres transmitting communication lights, a wavelength of 1625 nm is used for maintenance testing. The splitter installed optical filters allow the communication light to pass but that cut off the test light in the front of optical line terminals (OLTs) and optical network terminals (ONTs). In the economic point of view, We design new planer lightwave circuit splitter embedded filtter and study it optical property.

• Communications for Statistical Applications and Methods
• /
• v.22 no.3
• /
• pp.209-222
• /
• 2015

Time series are used in many studies for model building and analysis. We must be very careful to understand the kind of time series data used in the analysis. In this review article, we will begin with some issues related to the use of aggregate and systematic sampling time series. Since several time series are often used in a study of the relationship of variables, we will also consider vector time series modeling and analysis. Although the basic procedures of model building between univariate time series and vector time series are the same, there are some important phenomena which are unique to vector time series. Therefore, we will also discuss some issues related to vector time models. Understanding these issues is important when we use time series data in modeling and analysis, regardless of whether it is a univariate or multivariate time series.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.5
• /
• pp.653-659
• /
• 2010

Friction stir welding results in low distortion and high joint strength compared with other welding procedures, and is able to join all aluminium alloys that are not considered as virtually weldable with classical liquid state techniques. The comparative study on high cycle fatigue properties between A16005-T6 friction stir welds and MIG weld joints have been performed and fracture mechanisms for the fatigue specimens were investigated. Although mechanical properties are lower than the corresponding base material, FSW joints of A16005-T6 become higher at tensile and fatigue strength in comparison with the traditional fusion weld(MIG). The fracture surfaces of FSW and MIG fatigue specimens cleary show different aspects of the fracture morphology. MIG weldments were characterized by voids and cleavage(brittle fracture) but FSW specimens showed the presence of ductile fracture surface.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.11b
• /
• pp.244-249
• /
• 2002

Rubber seat is extensively used to reduce the vibration of machine or structure. Over the years an enormous effort has been put into developing procedures to provide properties of rubber material for design function. However, there are still a lot of difficulties to analyze static characteristics of rubber components with hyper elasticity and nonlinear large deformation. In this paper material property is obtained by strain-stress curve using a tension test. Mooney-Rivlin Coefficients are gotten by fitting strain-stress curve. The visco-elastic characteristics of refrigerator rubber mount is determined by using ANSYS. And to minimize the rubber stiffness, the rubber seat shape optimization is performed.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2000.05a
• /
• pp.41-45
• /
• 2000

Geotube is made of permeable but soil-tight geotextile, hydraulically filled with soil include dredged sand and mud, which has been successfully applied in hydraulic and coastal engineering projects. Ceotube method is getting popular and being used a lot in many countries of the world because of the simplicity of the placement and construction, cost effectiveness and minimum impact on the environment, and enable to store & isolate contaminated materials as obtained by harbor dredging. Laboratory tests and field construction were performed to determine the design methodology and construction procedures. From the results of laboratory and field construction, the retention ratio of solid particle is a minimum 86%. The minimum permeability and the tensile strength of geotextile are $\alpha$ x 10$^{-4}$ cm/sec and 20t/m, respectively Also, based on the environmental test results, it can be concluded that this method does meet the Korean EPA standards.

• Journal of Mechanical Science and Technology
• /
• v.18 no.6
• /
• pp.1010-1018
• /
• 2004

This study presents the methodological aspects of combustion instability modeling and provides the numerical results of the model (sub-scale) combustion chamber, regarding geometrical dimensions and operating conditions, which are for determining the combustion stability boundaries using the model chamber. An approach to determine the stability limits and acoustic characteristics of injectors is described intensively. Procedures for extrapolation of the model operating parameters to the actual conditions are presented, which allow the hot-fire test data to be presented by parameters of the combustion chamber pressure and mixture (oxidizer/fuel) ratio, which are customary for designers. Tests with the model chamber, based on the suggested scaling method, are far more cost-effective than with the actual (full-scale) chamber and useful for injector screening at the initial stage of the combustor development in a viewpoint of combustion instabilities.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.7 no.6
• /
• pp.279-286
• /
• 1999

Failure of spot-weld joints in car body may cause noise, vibration and safety problems. Systematic procedures for estimating fatigue strength of general spot-weld joints are developed in this paper. Fatigue test results for various spot-welded specimens are analysed using the finite element method. It is found that the maximum principal strain at the nugget boundary on the inner surface governs the fatigue failure of spot-welded joints.

• Korean Management Science Review
• /
• v.27 no.3
• /
• pp.1-14
• /
• 2010

In this paper we study the access network design problem in Universal Mobile Telecommunication Systems (UMTS) networks. Given the location of radio base stations (node-Bs), their traffic demands, and the candidate facility centers for locating radio network controllers (RNCs), the problem is to determine the configuration of access network, including the number and location of facility centers, the number of RNCs in each facility center, and the links between RNCs and node-Bs, with the objective being to design such a network at the minimum cost. We provide a mathematical formulation of the problem with constraints on RNC and node-B capacities, along with a lower bounding method. We develop a heuristic algorithm with two different initial solution methods designed to strengthen the solution quality. The computational efficacy of their procedures is then demonstrated on a number of test problems.

• Journal of Pharmaceutical Investigation
• /
• v.34 no.5
• /
• pp.379-383
• /
• 2004

Statistical interpretations in a bioequivalence trial are considered and studied when the missing observations occurred in $2\;{\times}\;2$ crossover experiment. Patel (1985) suggested the approximate test procedures for carryover effect and drug effect in $2\;{\times}\;2$ crossover design when some of data are missing in the second period. A modified Patel method is newly proposed to the bioequivalence trial and it is compared with the current method through the simulation study.

• Structural Engineering and Mechanics
• /
• v.16 no.1
• /
• pp.63-81
• /
• 2003

This paper describes experimental and theoretical investigations on the behaviour of thin walled composite (TWC) filled columns under eccentric loading conditions. Details of the experimental investigation including description of the test columns, testing arrangements, failure modes, strain characteristics, load-deformation responses and effects of various geometric and material parameters are presented. The current paper also introduces the use and effect of lightweight Volcanic Pumice Concrete (VPC) in TWC columns. Analytical models for the design of columns under eccentric loading conditions have been developed taking into consideration the effect of confined concrete. The performance of design equations is validated through experimental results. The proposed design models are found to produce better results compared with available design procedures and Code based formulations. A computer program is developed to generate the interaction diagrams based on the proposed design equations that can be used for design purposes.