• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.80-89
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• 1992

An experimental study of in-cylinder of flow and combustion characteristics in two gasoline engines of different intake ports which are denoted as original port and masked shroud head (MSH) ports is presented. The flows generated by the MSH and the original port are invest- igated by laser Doppler velocimeter(LDV) under steady flow and motoring (non-firing) condit -ions. Combustion characteristics with different swirl levels produced by two intake ports are analyzed by combustion pressure measurement and statistical calculation. The swirl inside the cylinder of the MSH port engine is found to be much higher than the original port, and the MSH has a large eddy motion of cylinder diameter size. Using ensemble average method to valuate engine turbulence under motoring condition, the MSH port engine is shown to have h -igher turbulence intensity than the original port, so that the effect of the MSH port on fast burn is shown. Also the cyclic variations of peak pressure and the reaching time in the MSH port are apparently reduced.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.11a
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• pp.256-259
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• 2007

In this paper, the combustion characteristics of hybrid rocket were studied with various port number of the cylindrical multi-port grain. For the regression rate case, as the port number increases, the both port regression rate and end-surface regression rate tend to increase. For the performance parameter case, as the port number increases, the O/F ratio tends to decreases and the specific impulse tends to increase.

• Journal of Korea Port Economic Association
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• v.31 no.4
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• pp.189-207
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• 2015

The purpose of this study is to examine the relationship between the network characteristics of ports and their performance that is represented by port competitiveness for the port operators. The study employs Social Network Analysis (SNA) to evaluate network characteristics comprising four centrality indices. For this research, data from Containerization International Yearbooks for 2006-2011 is used to analyze the service networks of 20 major liner shipping companies. In SNA, nodes (vertices) in the network are the ports and links (edges) in the network are connections realized by vessel movements, such that the liner shipping network determines the port network. In addition, panel regression analysis has been employed to investigate the relationship between port network characteristics and their performance. The results suggest that the four centrality indices identify the roles of the world's major ports from 2006 to 2011 and that port performance is determined not only by macroeconomic variables and service capabilities but also by the eigenvector centrality of ports in networks.

• Journal of Korea Port Economic Association
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• v.39 no.4
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• pp.295-308
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• 2023

Busan Port, as Korea's representative trading port, handles a variety of port cargo from bulk cargo to container cargo. Busan Port is currently functioning as a container specialized port for North Port and Busan New Port, and Gamcheon Port is also handling container cargo mainly in bulk cargo. This study intends to examine the overlapping cargoes and specialized cargoes between these ports and Busan Port as the amount of import and export cargoes in ports designated as trade ports in Korea is increasing. In order to understand the characteristics of the major cargoes handled in the port, the quantitative change is confirmed through the total cargo volume of major domestic ports and the trend of changes in import/export cargo between Busan Port and major ports is analyzed. There are many specialized investigation methods, but as the most basic method, we will examine quantitative changes and causes by simply examining the data for 10 years as the amount of change by cargo. In addition, the causes of these fluctuations should be reclassified into domestic and foreign causes by identifying changes in customers in different ports and shipping volumes, changes in consumption areas, and transshipment volumes. Through the analysis of the major cargo volume of each port, the characteristics and fluctuation trends of major cargo handled in Busan Port and other ports are identified, and the competitive cargoes of each port are verified. Through this, the characteristics and competitiveness of the port are inferred, and implications for the cargo volume of Busan Port and future countermeasures are suggested.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.4
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• pp.17-23
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• 2007

This paper describes the flow and performance characteristics inside the post-chamber of the multi-port hybrid rocket motor. Using the computational fluid dynamics (CFD) technique, the non reactive compressible flow fields in the downstream of the fuel grain was numerically calculated. The motor performance obtained from computational results were in agreement with that conducted by the ground motor firing test. Besides, the flow field characteristics inside the post-chamber were discussed under different port numbers (1 port and 3 ports) of the fuel grain. The flow pattern showed that the performance of multi-port hybrid rocket motor having three grain ports is higher than that of the single-port one due mainly to the difference of incoming mass flow rate irrespective to the pressure field.

• KCID journal
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• v.18 no.2
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• pp.122-141
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• 2011

The purpose of this study was to analyze the conditions of small fishing village & fishing port and to suggest the development direction of them. For this, we tried to field survey and research of development demands for 100 sample places. The results of this study were as follows; First, Small fishing villages & fishing ports have different characteristics and their primary industry was a fisheries. And they have a poor condition for basic facilities and industrial facilities, more smaller fishing port. Second, The living satisfaction of residents was decreased gradually because of a decrease in amount of catching fish, a population aging and etc. Residents and public officers was to demand an expansion of basic facilities, an investment of national expenditure and a simplification of administrative procedure. Third, We could establish the development directions by geographical location and funcion of them. And They must development consider their characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.1
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• pp.9-16
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• 2009

This paper is the second of 2 companion papers which investigate in-cylinder swirl generation characteristics in helical port engine with wide valve angle. Two wide valve-angle engines, which are same ones and have slightly different rig swirl number, were used to compare the characteristics of cylinder-flow. One intake port is deactivated to induce swirl flow. A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field during intake stroke. The results show that the intake flow component passing through valve area near the cylinder wall is not negligible in helical port engine with wide valve angle contrary to conventional one. The effect of this velocity component on in-cylinder increases as the swirl ratio rises and compression process progresses. Consequently, this component destroys in-cylinder swirl flow completely during compression resulting in no actual swirl at the end stage of compression.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3108-3113
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• 2008

This paper investigated the behaviors of combustion characteristics at part load condition with various intake charge motions induced by the port masking schemes in the CVVT (Continuously Variable valve Timing) engine. Time resolved in-cylinder and exhaust emissions were measured by the fast response HC and NOx analyzers to examine their formation mechanisms and behavior characteristics. As a result, in-cylinder HC decreased with the advanced intake valve timings but HC at the exhaust port increased due to the worse combustion stabilities. However HC reduction could be achieved by the application of the port maskings with a enhancement of the engine stability. NOx also decreased with early intake timings by internal EGR but increased with the charge motion controls which enhance the combustion behavior.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.10
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• pp.761-768
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• 2008

This paper is the first of 2 companion papers which investigate in-cylinder swirl generation characteristics in helical port engine with wide valve angle. Two wide valve-angle engines, which are same ones and have slightly different rig swirl number, were used to compare the characteristics of cylinder-flow. One intake port is deactivated to induce swirl flow. A PIV (Particle Image Velocimetry) was applied to measure in-cylinder velocity field during intake stroke. The results show that the intake flow component passing through valve area near the cylinder wall is not negligible in helical port engine with wide valve angle contrary to conventional one. The effect of this velocity component on in-cylinder increases as the swirl ratio rises and intake process progresses. Consequently, this component interferes the formation of in-cylinder swirl flow resulting in lower actual swirl.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.12 s.243
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• pp.1360-1368
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• 2005

This study investigates the characteristics of spray, such as evaporation rate and spray trajectory, for a 4-hole injector which is applied to a 4-valve motorcycle gasoline engine. Three dimensional, unsteady, compressible flow and spray within the intake-port and cylinder have been simulated using the VECTIS code. Spray characteristics were investigated at 6000 rpm engine speed. Furthermore, we visualized fuel behavior in the intake-port using a CCD camera synchronized with a stroboscope in order to compare with the analytical results. Boundary and intial conditions were employed by complete 1-D simulation of the engine using the WAVE code. Fuel was injected into the intake-port at two time intervals relative to the position of the intake valves so that the spray arrived when the valves were closed and fully open. The results showed that the trajectory of the spray was directed towards the lower wall of the port with injection against the closed valves. With open valve injection, a large portion of the fuel was lifted by the co-flowing air towards the upper half of the port and this was confirmed by simulation and visualization.