• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.47-53
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• 2007

The laminar combustion characteristics of interacting coal particles in a convective flow are numerically investigated at particle arrangement and size difference. The numerical simulations, which use the two-step global reaction model to account for the surrounding gas effect, show the detailed interaction among the inter-space particles, undergoing devolatilization and subsequent char burning. Several parametric studies, which include the effect of the gas temperature (1700 K), high pressure(10 atm) and variation in geometrical arrangement of the particle diameter on the volatile release rate and the char combustion rate, have been carried out. The comparison indicates that the shift to the multiple particle arrangement resulted in the substantial change of the combustion characteristics and that the volatile release rate of the interacting coal particles exhibits a strong dependency on the particle spacing and size difference.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.407-408
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• 2008

This paper presents a synchronous pipeline design for IP-based H.264 decoding system. The first optimization for pipelining aims at efficiently resolving the data dependency due to motion compensation/intra prediction feedback data flow in H.264 decoder. The second one would enhance the efficiency of execution per each pipelining stage to explore the optimized latency and stage number. Thus, the 3 stage pipeline of CAVLD&ITQ|MC/IP&Rec.|DF is obtained to yield the best throughput and implementation. In experiments, it is found that the synchronous pipelined H.264 decoding system, based on existing IPs, could deal with Full HD video at 125.34MHz, in real time.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.196-204
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• 1996

This paper presents a new scheduling algorithm, which is the most improtant subtask in the high level synthesis. The proposed algorithm performs scheduling in consideration of resource sharing concept based on characteristics of conditionsla bransches in the intermediate data structure. CDFG (control data flow graph) generated by a VHDL analyzer. This algorithm constructs a conditon graph based on time frame of each operation using both the ASAP and the ALAP scheduling algorithm. The conditon priority is obtained from the condition graph constructed from each conditional brance. The determined condition priority implies the sequential order of transforming the CDFG with conditonal branches into the CDFG without conditional branches. To minimize resource cost, the CDFG with conditional branches are transformed into the CDFG without conditonal brancehs according to the condition priority. Considering the data dependency, the hardware constraints, and the data execution time constraints, each operation in the transformed CDFG is assigned ot control steps. Such assigning of unscheduled operations into contorl steps implies the performance of the scheduling in the consecutive movement of operations. The effectiveness of this algorithm is hsown by the experiment for the benchmark circuits.

• Journal of computational fluids engineering
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• v.7 no.4
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• pp.1-7
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• 2002

The phase-change transformation processes are relevant in many engineering applications. In particular, this phenomenon plays an important role in the extraction and fabrication operations in the metallurgical industry. The control of the heat transfer and fluid flow patterns is important to achieve casting quality and competitive production times. In the present study, a simple finite-element algorithm is developed for solid-liquid phase change problems. Natural convection in the liquid phase due to the temperature dependency of water density is considered by a numerical model. The predictions are compared with measurements by the particle image velocimetry(PIV). to show that the calculation results are in good agreement with the experiment results.

• Transactions of the Korean Society of Mechanical Engineers
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• v.8 no.2
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• pp.133-140
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• 1984

A "two-fluid" equation model has been applied for predicting gas-solid suspension flows through a Venturi tube. In the "two-fluid"equation model, the bulk motion of the particles is considered as a continuum whose governing equation is obtained by averaging the conservation equations over a volume and expressing the equations in differential forms. Closure of the time-mean equations is achieved by modeling the turbulent correlations with an extended mixing-length theory. Proposed closure model is found to aptly simulate the dependency of the static pressure drop on the particle size, flow rate and the loading ratio.d the loading ratio.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1851-1856
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• 2008

A numerical program based on computational fluid dynamics has been developed to simulate characteristics of an EHD induction micropump. The ambiguity of boundary conditions was removed by adopting an equation formulated for electric potential as the dependent variable. The calculations show that the dependency of frequency agrees well with the experiments and the previous analysis. The instability, caused by backflows, is getting stronger as the channel depth increases, which is consistent with experiments. The present study reveals that it is due to the limit in the penetration depth which the electric field can affect. Despite the disadvantage of large channel depth, there is a certain optimal depth for the maximum flow rate.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.511-521
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• 2010

This paper presents a new algorithm to determine accurate bus-wise transmission loss allocation utilizing path-integrals dictated by the transaction strategy. For any transaction strategy, the total sum of the allocated transmission losses of all buses is equal to the actual loss given by the AC power-flow calculation considering the distributed slack. In this paper, the bus-wise allocation of the transmission loss is calculated by integrating the differential loss along a path determined by the transaction strategy. The proposed algorithm is also compared with Galiana's method, which is the well-known transmission loss allocation algorithm based on integration. The performance of the proposed algorithm is evaluated by case studies carried out on the WSCC 9-bus, IEEE 14-bus, New England 39-bus, and IEEE 118-bus systems. The simulation results show that the proposed algorithm is fast and accurate with a large step size.

• The Transactions of the Korea Information Processing Society
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• v.6 no.6
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• pp.1646-1655
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• 1999

This thesis presents a new VHDL intermediate format CDDG(Control Dominated Data Graph) and a minimal constrained scheduling algorithm for an optimal control dominated ASIC design. CDDG is a control flow graph which represents conditional branches and loops efficiently. Also it represents data dependency and such constraints as hardware resource and timing. In the proposed scheduling algorithm, the constraints using the inclusion and overlap relation among subgraphs. The effectiveness of the proposed algorithm has been proven by the experiment with the benchmark examples.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2008.04a
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• pp.11-14
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• 2008

This paper is currently being conducted to develop a nonlinear finite element analysis methods for predicting the structural behavior of reinforced concrete structures, exposed to fire. The changes in thermal parameters are discussed from the point of view of changes of structure and chemical composition due to the high temperature exposure. Although, this study considers codes standard fire for reinforced concrete frame, any other time-temperature relationship can be easily incorporated.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.63-67
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• 2002

In this study, the performance of the Stirling type orifice Pulse tube refrigerator (OPTR) with a linear compressor was investigated by experiment. The dynamic pressures at three points and a temperature at the cold heat exchanger are measured to explore the dependency of the orifice on the performance of the OPTR. The experimental results show that the opening of the orifice has significant effects on the no load temperature and cool down characteristics. The Pressure amplitude in Pulse tube decrease as the opening of the orifice increase, but the mass flow rate through the orifice and the electric input Power to the compressor increase. The results show that the operating frequency and charging Pressure does not affect on the no load temperature. The pressure amplitude in pulse tube decrease as the operating frequency increase or the charging Pressure decreased.