• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.2
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• pp.127-133
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• 2008

The purpose of this study is to investigate the seismic performance of both exterior precast concrete cladding panels and their connections on steel frame, when these cladding systems are considered as the structural components. The degrees of their participation of lateral stiffness to the main building are evaluated in terms of different heights of the cladding panels. Considering the cladding system as an integrated building provides additional lateral stiffness, as well as a mechanism for energy dissipation and this system can be used as one of an advanced passive seismic control system. Hysteresis behaviors of connectors are modeled and integrated into a nonlinear finite element analysis program, ABAQUS. The results show that connections play the most important role in structural cladding system and they improve seismic performance of overall building response.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.5
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• pp.141-151
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• 2018

A trajectory analysis program was developed to predict KSLV-II (Korea Space Launch Vehicle-II) performance with the reducing weight. The program estimates the LEO (Low Earth Orbit) / SSO (Sun-Synchronous Orbit) injection performance, which is determined as payload weight for the orbits, with decreasing the structural ratio or increasing rocket engine power. It is expected that the KSLV-II can transport up to 4.5 tons, 3 tons of space payloads at LEO, SSO with a reduced structural ratio by 60% of the original. It also shows that the KSLV-II can transport up to 3.65 tons at SSO by applying advanced engines of 90 tonf, 10 tonf class with the reduced structure.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.457-463
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• 2003

A general program of meanline design and/or performance prediction for centrifugal/mixed-flow compressors is successfully commercialized using various empirical loss models. 4 types of diffusers, 3 types of exit elements, shrouded/unshrouded impellers and real gas option are included in the program capabilities. Total 16 cases of benchmark test results proved its reliability to be effectively utilized in the development processes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.3
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• pp.1003-1010
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• 2013

In this study, a simulation program was developed, which predicts the performance of cold-air forced circulation type air cooled showcase. The showcase has an excellent display effect in addition to preserving the grocery. In the program, the compressor was analyzed using performance data supplied by the manufacturer and the capillary tube pressure drop was analyzed using a homogeneous model. The evaporator and condenser were analyzed by dividing the heat exchangers into small elements, where energy balance and appropriate heat transfer correlations were used. A showcase model with two 3/4 HP compressors, capillary tubes of 1.6 mm inner diameter, a fin-and-tube evaporator and condenser was tested, and the results are compared with the predicted values. It is shown that both evaporation and condensation temperatures are adequately predicted by the program.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.3
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• pp.67-72
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• 2018

Recently, noise reduction in an axial fan producing the small pressure rise and large flow rate, which is one type of turbomachine, is recognized as essential. This study describes the design and optimization techniques of MPI parallel program to simulate the flow-induced noise in the axial fan. In order to simulate the code using 100 million number of grids for flow and 70,000 points for noise sources, we parallelize it using the 2D domain decomposition. However, when it is involved many computing cores, it is getting slower because of MPI communication overhead among nodes, especially for the noise simulation. Thus, it is adopted the one-sided communication to reduce the overhead of MPI communication. Moreover, the allocated memory and communication between cores are optimized, thereby improving 2.97x compared to the original one. Finally, it is achieved 12x and 6x faster using 6,144 and 128 computing cores of KISTI Tachyon2 than using 256 and 16 computing cores for the flow and noise simulations, respectively.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.1
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• pp.71-79
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• 2014

A parallelization of the bi-conjugate gradient solver for the pressure equation of the CUPID (component unstructured program for interfacial dynamics) code, which was developed for analyzing the components of a pressurized water-cooled reactor, was studied in a symmetric multi-processing system. The parallel performance was investigated for three typical parallel programming models (MPI, OpenMP, Hybrid) by solving incompressible backward-facing step flow at various grid resolutions. It was confirmed that parallel performance was low when problem size was small or the memory requirement for each thread was considerably higher than the cache memory. Furthermore, it was shown that MPI was better than OpenMP regardless of the problem size, and Hybrid was the best when the number of threads was relatively small.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.9
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• pp.897-904
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• 2017

Optical equipment consists of various components, and a detector is mounted and operated on aircraft, tanks, and warships for target detection and classification. The structural stability and optical performance of aeronautical optical equipment operated at several kilometers of altitude are degraded owing to vibration generated in the aircraft. It is necessary to verify the structural stability and optical performance requirements of the equipment in vibration environment conditions during the design phase. In this study, vibration environment conditions were analyzed using a test standard and the measurements of the vibration generated in aircraft. The conditions were classified as endurance and operating vibration conditions for structural stability and optical performance verification, respectively. The structural stability was verified according to natural frequency analysis, response analysis for the endurance vibration condition, and static analysis. The optical performance was verified by applying the vibration response analysis results to the optical design/analysis program.

• Water for future
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• v.29 no.6
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• pp.141-154
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• 1996

A computer program is developed in order to investigate the fluid flow and heat ransfer of a water body in a 2-D vertical rectangular coordinate. The specific purpose of this study is to obtain a physical insight of several fluid flow problems which occur in a lake and the water and wastewater treatment facility like a primary clarifier. The performance of computer program developed is successfully evaluated by the comparison of other two experimental and computational data in open literature : the first comparison is made against the numerical data associated with the cooling water discharge and the other is numerical and experimental works for the primary clarifier of Sarina City at Ontario. Further, the computer program is applied to investigate the feature of lake flow, say lake turnover, and 2-D vertical channel flow in terms of temperature, wind velocity and flow rate, etc. The computational results appear to be physically acceptable and consistent. The computer program developed in this study shows the possibility of the viable tool to figure out the flow characteristics of water reservoir.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1003-1009
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• 2012

Heat exchanger has been widely used in the industry which needs energy transport, and the application of the plate type heat exchanger having high efficiency has been greatly increased. In this study main design parameters are analyzed and new equations are induced. The induced formulation was compared with a commercial program in order to design an optimal heat exchanger. The equations of heat transfer coefficient and pressure drop for Chevron angles are introduced as functions of Reynolds number. The program implemented the equations is tested with Chevron angle variation. The results show that the convective heat transfer coefficients take errors within 8% and the pressure drops have errors within 5% in the analysis conditions.

• Journal of Navigation and Port Research
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• v.37 no.1
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• pp.1-7
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• 2013

In this paper the developed prediction technique of wave-making resistance performance for a ship attached with a vertical blade had been verified. Numerical analysis program as a prediction technique had been developed using the Rankine source panel method and the vortex lattice method(VLM). The nonlinearity of the free surface conditions was fully taken into account using the iterative method and the trim and the sinkage of the ship were also considered in the numerical analysis program. Panel cutting method was applied to get hull surface panels. Numerical computations were carried out for a 4000TEU container carrier and the vertical blade was attached 6 different locations astern. To investigate the validity of the numerical analysis program the commercial viscous flow field analysis program FLUENT was used to obtain the viscous flow field around the ship and the model test was performed. The model test results were compared with the numerical analysis results.