• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.9-10
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• 2005

A study on the combustion and exhaust emissions characteristics by using Emulsion Fuel in Diesel Engine is performed experimentally. In this paper, the experiments are performed at engine speed 1800rpm, emulsion fuel ratio is 0%, 5%, 10%, 15%, 20%, 25%, and main measured items are specific fuel consumption, NOx and Soot emissions etc. The obtained conclusions are as follows. 1) Specific fuel consumption increase maximum 19.8% at low load, but is not effected at full load. 2) NOx emissions decrease 30% in case of emulsion fuel ratio 25% at full load. 3) Soot emission decrease 58.9% in case of emulsion fuel ratio 25% at full load.

• Journal of Power System Engineering
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• v.11 no.1
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• pp.51-55
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• 2007

A study on combustion characteristics using emulsified fuel in a diesel engine were performed experimentally. In this paper, the experiments were performed at engine speed 1800rpm, emulsion ratios were 0%, 10%, 20%, and main measured items were specific fuel consumption, cylinder pressure, rate of pressure rise, rate of heat release etc. The obtained conclusions were as follows. 1) Specific fuel consumption increased maximum by 19.8% at low load, but was not affected at full load. 2) Rate of pressure rise and rate of heat release were about the same in the case of 10% and 20% of emulsion ratio. 3) Cylinder Pressure increased 9.6%, rate of pressure rise increased 53.4% in case of emulsion ratio 20% at full load. 4) Rate of heat release increased 72.4% in case of emulsion ratio 20% at full load.

• Journal of Biosystems Engineering
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• v.34 no.2
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• pp.71-76
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• 2009

This study was conducted to investigate the load acting on a tractor engine when it delivers the maximum power at drawbar. The results of the drawbar tests on the 5 locally-made and 14 imported tractors conducted at NIAE in 2004, and the 15 tractors tested at OECD test stations in foreign countries were analyzed and presented by the torque load ratio, defined as a ratio of the engine torque load caused by drawbar pull to its full-load capacity, as a function of pull speed. The NIAE test results showed that the torque load ratio increased from 20 to 80% with pull speed less than 5 km/h. At speeds faster than 5 km/h, it was 80${\sim}$110% regardless of the pull speed. However, the OECD test results showed that the torque load ratio was evaluated mostly to be 70${\sim}$90% in the entire pull speed range. The same trend was also shown for the maximum drawbar load. The difference in the torque load ratio may be attributable to bias-ply tires for locally-made and some imported tractors. It is also suggested that the input torque load may be increased safely up to 120% of the full load capacity of the tractor engine for an accelerated life test of tractor transmissions.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.5
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• pp.211-221
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• 1998

Thermal behavior on the cylinder block of a 4-cylinder, 4-stroke 2.0L SOHC gasoline engine was numerically and experimentally analyzed. The numerical calculation was performed using the finite element method. The cylinder block was modelled as a three dimensional finite element by considering its geometry. The physical domain was devided into hexahedron elements. 16 thermocouples were installed at points of 2mm inside from cylinder wall near top ring of piston in cylinder block, which points have suffered major thermal loads and suggested as proper measurement points for engine design by industrial engineers. Under full load and 9$0^{\circ}C$ coolant temperature condition, temperature behavior of cylinder block according to engine speed were analyzed. The results showed that temperature rose gradually to conform to a function of 2nd~4th order of engine speed at intake side, exhaust and siamese side, respectively. As engine load was changed from 100 to 50% by 25% step, temperature curve also conformed to 2nd~7th order function of engine speed. Temperature differences by load condition were similar among 100, 75% and 50%. Under full load and coolant temperature of 11$0^{\circ}C$, temperature behavior were also analyzed and the result also showed conformance to 2n d~7th order function of engine speed. Temperature curve was transferred in parallel upwards corresponding coolant temperature rise.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.1
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• pp.44-50
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• 2007

Diesel engines have high thermal efficiency, and they have less CO & HC emissions than another engines. while NOx & Soot emissions are very much. compared with exhaust emission standards. However, the limit level is more and more strengthened yearly due to the importance of environmental protection. So, the optimal countermeasures for the reduction of NOx & Soot emissions below limit level are required. Therefore. the author has investigated the effects of emulsified fuel on the characteristics of exhaust emissions. using an four-cycle, four-cylinder and direct injection diesel engine because the using of emulsified fuel among various methods for reducing NOx & Soot emissions is simple in installation low in cost and high in efficiency. The results of investigation according to various operating conditions are as follows : 1) Specific fuel consumption increase maximum 19.8% at low load. but is not affected at full load. 2) In case of emulsion ratio 25%, NOx emission decrease 32% at 75% load. 30% at full load. 3) In case of emulsion ratio 25%, Soot emission decrease 84% at 75% load, 59% at full load.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.146-153
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• 2011

Some methods of calculation of test load value from design load data were investigated which will be applied at strap installed full-scale airframe of composite aircraft. These methods were applied to left wing of KC-100 composite aircraft and the calculated test load values were compared with each others. Generally since test load values are differently calculated according to each aircraft type and position of straps, all calculation methods mentioned at this study need to be applied and compared to each aircraft. Finally the most appropriate method needs to be selected.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.2
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• pp.78-85
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• 2003

This study aims to investigate the effect of partially distributed loads on the static behavior of parabolic arches by using the elastic-plastic finite element model. For this purpose, the vertical, the radial, and the anti-symmetric load cases are considered, and the ratio of loading range and arch span is increased from 20% to 100%. Also, the elastic-visco-plastic analysis has been carried out to estimate the elapse time to reach the stable state of arches when the ultimate load obtained by the finite element analysis is applied. It is noted that the ultimate load carrying capacities of parabolic arches are 6.929 tf/$m^2$ for the radial load case, and 8.057 tf/$m^2$ for the vertical load case. On the other hand, the ultimate load is drastically reduced as 2.659 tf/$m^2$ for the anti-symmetric load case. It is also shown that the maximum ultimate load occurs at the full ranging distributed load, however, the minimum ultimate loads of the radial and vortical load cases are obtained by 2.336 tf/$m^2$, 2.256 tf/$m^2$, respectively, when the partially distributed load is applied at the 40% range of full arch span.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.67-75
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• 2014

A full-scale static test for a composite structure small aircraft (KC-100) was conducted in the KARI. The test includes 15 full-scale test and 7 local test conditions. Test requirements with test schedule, test article with dummy structures, test load generation, test system, and equipment are introduced for the test. Test load data of the 1st test condition(U1) was analyzed to evaluate an accuracy of load control for the test. The analysis results show that load data obtained during test were within tolerance of Static Null Pacing Error(SNPE) and the error value of load control was 8.6N. The error of load controls for the full-scale static test using dozens of actuators was calculated by a method suggested by authors. Test data for all other test conditions is also shown in this paper. Finally, reactions measured from restraint system of the U1 test condition show that the reaction changes as load increment. The factors which may change the change of reactions for a full-scale static test are introduced in this study.

• Wind and Structures
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• v.14 no.4
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• pp.301-319
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• 2011

The full-scale measurements are compared with the wind tunnel test results for the long-span roof latticed spatial structure of Shenzhen Citizen Center. A direct comparison of model testing results to full-scale measurements is always desirable, not only in validating the experimental data and methods but also in providing better understanding of the physics such as Reynolds numbers and scale effects. Since the quantity and location of full-scale measurements points are different from those of the wind tunnel tests taps, the weighted proper orthogonal decomposition technique is applied to the wind pressure data obtained from the wind tunnel tests to generate a time history of wind load vector, then loads acted on all the internal nodes are obtained by interpolation technique. The nodal mean wind pressure coefficients, root-mean-square of wind pressure coefficients and wind pressure power spectrum are also calculated. The time and frequency domain characteristics of full-scale measurements wind load are analyzed based on filtered data-acquisitions. In the analysis, special attention is paid to the distributions of the mean wind pressure coefficients of center part of Shenzhen Citizen Center long-span roof spatial latticed structure. Furthermore, a brief discussion about difference between the wind pressure power spectrum from the wind tunnel experiments and that from the full-scale in-site measurements is compared. The result is important fundament of wind-induced dynamic response of long-span spatial latticed structures.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1656-1663
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• 2016

A capacitive wireless power transfer (C-WPT) system uses an electric field to transmit power through a physical isolation barrier which forms a pair of ac link capacitors between the metal plates. However, the physical dimension and low dielectric constant of the interface medium severely limit the effective link capacitance to a level comparable to the main switch output capacitance of the transmitting circuit, which thus narrows the soft-switching range in the light load condition. Moreover, by fundamental limit analysis, it can be proved that such a low link capacitance increases operating frequency and capacitor voltage stress in the full load condition. In order to handle these problems, this paper investigates optimal design of double matching transformer networks for C-WPT. Using mathematical analysis with fundamental harmonic approximation, a design guideline is presented to avoid unnecessarily high frequency operation, to suppress the voltage stress on the link capacitors, and to achieve wide ZVS range even with low link capacitance. Simulation and hardware implementation are performed on a 5-W prototype system equipped with a 256-pF link capacitance and a 200-pF switch output capacitance. Results show that the proposed scheme ensures zero-voltage-switching from full load to 10% load, and the switching frequency and the link capacitor voltage stress are kept below 250 kHz and 452 V, respectively, in the full load condition.