• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.631-640
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• 2001

Round robin scheduling discipline, which is a sort of frame-based scheduling, is quite simple and straightforward for handling multiple queues, and by putting a different weight on each queue, a network can offer differentiated services such as different bandwidth, or delay bound. The most typical algorithm among this disciplines is the weighted round robin(WRR). Also, WRR algorithm can be implemented efficiently by dynamic binary scheduling wheel(DBSW) architecture. This paper performs the analysis of the DBSW architecture and compares the results with simulation results. The analysis data and simulation data show that the DBSW structure decreases average buffer length because it is capable of maintaining the allocated weight of each VC correctly.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.3
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• pp.213-220
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• 2014

A program that predicts trajectories of projectiles influenced by the interference flow field of helicopters is developed. The interference flow field are computed using a compressible inviscid solver in conjunction with an actuator disc model. The trajectories are predicted using 6-DOF (Degree of Freedom) equations as well as an alternative form of modified point mass equations of motion. The method for the interference flow field prediction method are validated with ROBIN(ROtor Body INteraction) model. A Sierra international bullet and a 105mm projectile are used to validate the trajectory method. Trajectories of a Sierra International bullet and a HYDRA 70 rocket firing from a helicopter are predicted.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.3 s.357
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• pp.41-50
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• 2007

In this paper, a new Dual Round-Robin (DRR) based iterative SLIP (iSLIP) scheduling scheme, called DiSLIP is proposed for IP switching systems. By using DRR followed by iSLIP, DiSLIP can exploit desynchronization effect of DRR and high performance of iSLIP, while the drawbacks of two schemes are minimized. 'Through computer simulation, we verify the switch throughput and total waiting time of the proposed scheme under nonuniform and correlated self-similar traffic. Moreover, the proposed scheme can considerably reduce the complexity of parallel matching logics compared to iSLIP. From the result, we observe that the proposed scheme outperforms DRR on throughput as well as iSLIP schemes on complextiy.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.50-56
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• 2009

SoC(System on a Chip) has several masters, slaves, arbiter and decoder in bus architecture. Master initiates the data transactions like CPU, DMA and DSP and slave responses the data transactions like SRAM SDRAM and register. Furthermore, as multiple masters can't use a bus concurrently, arbiter plays an role in bus arbitration. In compliance with the selection of arbitration method, SoC performance can be changed definitely. Fixed priority, round-robin, TDM arbitration are used in general arbitration method, In this study, we compose TLM algorithm and analyze general arbitration methods through TLM simulation. Consequently, we propose the hybrid bus arbitration policy and verify the performance, compared with the other arbitration methods.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.85-87
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• 2008

DMWs are common feature of the PWR in the welded connections between carbon steel and stainless steel piping. The nickel-based weld metal, Alloy 82/182, is used for welding the dissimilar metals and is known to be susceptible to PWSCC. A round-robin program has been implemented to benchmark the numerical simulation of the transient temperature and weld residual stresses in the DMWs. To solve the round-robin problem related to Pressurizer Safety & Relief nozzle, the thermal elasto-plastic analysis is performed in the DMW by using the FEM. The welding includes both the DMW of the nozzle to safe-end and the SMW of the safe-end and piping. Major results of the analyses are discussed: The axial and circumferential residual stresses are found to be -88MPa(225MPa) and -38MPa(293MPa) on the inner surface of the DMW; where the values in parenthesis are the residual stresses after the DMW. Thermo-mechanical interaction by the SMW has a significant effect on the residual stress fields in the DMW.

• The Journal of the Korea Contents Association
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• v.2 no.4
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• pp.85-92
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• 2002

This paper proposes the cell scheduling algorithm proper to high-speed ATM switch. The proposed algorithm is the VRR(Variable weight Round Robin) combined the FRR to variant QLT. The FRR performs the cell service of the fixed weight by each buffer. So, FRR don't support the QoS of ATM service classes although it is easy to implement a high speed switch. VRR uses the method expaned to variable weight according to buffer state as well as schedules the cell according the Fixed weight based FRR. The simulation to evaluate the proposed algorithm was done by AweSim arid Visual C++. The result graphs show that the proposed algorithm is excellent, especially in the aspect of cell loss. This area is engaged by English Abstract.

• Current Photovoltaic Research
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• v.8 no.2
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• pp.54-59
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• 2020

Within the IEA (International Energy Agency) PVPS (Photovoltaic Power System) Programme Task 15, 'Enabling Framework for the Acceleration of BIPV,' a round-robin action focusing on the performance of vertical BIPV elements as a facade in different climatic environments was performed. The performance of identical (both, in construction and bill of materials (BOM)) glass-to-glass c-Si BIPV elements was monitored at seven outdoor test sites in 6 different countries in Europe and Asia. In this work, the comprehensive results of the electrical and corresponding meteorological data will be presented and discussed. The monitored data were merged, processed, and filtered for further analysis. The analysis includes the chracteristics of the module temperatures and the in-plane irradiation at the outdoor test locations, mean daily PR per test module, time series of mean daily performance ratio coefficients, and monthly yield.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.6
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• pp.336-344
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• 2001

For the establishment of the world wide unified scales of the Rockwell hardness test with conical indenters, round robin test was carried from 1998 to 2000. The pilot laboratory was MPA-NRW and 12 laboratories from 11 countries participated In this RRT. Rockwell hardness of 74 specially prepared blocks was measured for the scales of C, A, D, 45N, 30N, and 15N and the results were compared. It was found that the geometric form of indenter affects on the results very significantly and standardization in the measurement and evaluation of indenter should be established in short time for the reliable hardness measurement. KRISS showed good results in general for all of the ranges except 15N scale which showed relatively large difference compare to the mean value. It was concluded that poor control in loading velocity of the dash pot was the major reason.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.1
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• pp.1-9
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• 2010

Numerical simulation of unsteady flows around helicopters was conducted to investigate the aerodynamic interaction of main rotor and other components such as fuselage and tail rotor. For this purpose, a three-dimensional inviscid flow solver has been developed based on unstructured meshes. An overset mesh technique was used to describe the relative motion between the main rotor, and other components. As the application of the present method, calculations were made for the rotor-fuselage aerodynamic interaction of the ROBIN (ROtor Body INteraction) configuration and for a complete UH-60 helicopter configuration consisted of main rotor, fuselage, and tail rotor. Comparison of the computational results was made with measured time-averaged and instantaneous fuselage surface pressure distributions for the ROBIN configuration and thrust distribution and available experimental data for the UH-60 configuration. It is demonstrated that the present method is efficient and robust for the simulation of complete rotorcraft configurations.

• Nuclear Engineering and Technology
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• v.48 no.6
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• pp.1412-1422
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• 2016

Austenitic stainless steels (ASSs) are widely used for nuclear pipes as they exhibit a good combination of mechanical properties and corrosion resistance. However, high tensile residual stresses may occur in ASS welds because postweld heat treatment is not generally conducted in order to avoid sensitization, which causes a stress corrosion crack. In this study, round robin analyses on stress intensity factors (SIFs) were carried out to examine the appropriateness of structural integrity assessment methods for ASS pipe welds with two types of circumferential cracks. Typical stress profiles were generated from finite element analyses by considering residual stresses and normal operating conditions. Then, SIFs of cracked ASS pipes were determined by analytical equations represented in fitness-for-service assessment codes as well as reference finite element analyses. The discrepancies of estimated SIFs among round robin participants were confirmed due to different assessment procedures and relevant considerations, as well as the mistakes of participants. The effects of uncertainty factors on SIFs were deducted from sensitivity analyses and, based on the similarity and conservatism compared with detailed finite element analysis results, the R6 code, taking into account the applied internal pressure and combination of stress components, was recommended as the optimum procedure for SIF estimation.