• The Journal of Engineering Geology
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• v.27 no.3
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• pp.331-343
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• 2017

In this study to improve stability, workability and economics of the H-Pile+Earth plate or H-Pile+Earth plate+Cutoff grouting currently in use, we had developed HCS method belonging to the retaining wall which is consisting of a combination H-Pile, Plastic Sheet Pile and Steel Square Pipe for gap maintenance and reinforcement of flexible plastic Sheet Pile, and the behavior of each member composing HCS method is investigated by three-dimensional finite element analysis. To numerically analyze the behavior of the HCS method, we have performed extensive three-dimentional finite element analysis for three kinds of plastic Sheet Pile size, two kinds of H-Pile size and three kinds of H-Pile installation interval, one kinds of Steel Square Pipe and three kinds of Steel Square Pipe installation interval. After analyzing the numerical results, we found that the combinations of $P.S.P-460{\times}131.5{\times}7t$ (PS7) and H-Pile $250{\times}250{\times}9{\times}14$ (H250), $P.S.P473{\times}133.5{\times}9t$ (PS9) and H-Pile $300{\times}200{\times}9{\times}14$ (H300) is the most economical because these combinations are considered to have a stress ratio (=applied stress/allowable stress) close to that as the stiffness of H-Pile, plastic Sheet Pile and Steel Square Pipe composite increased, the horizontal displacement of the retaining wall and the vertical displacement of the upper ground decreased. Especially, due to the arching effects caused by the difference in stiffness between H-Pile and plastic Sheet Pile, a large part of the earth pressure acting on plastic Sheet Pile caused a stress transfer to H-Pile, and the stress and displacement of plastic Sheet Pile were small. Through this study, we can confirm the behavior of each member constituting the HCS method, and based on the confirmed results of this study, it can be used to apply HCS method in reasonable, stable and economical way in the future.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.913-917
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• 2007

The turbocharger for a vehicle is consisting of a centrifugal compressor and turbine. These compressor and turbine are vibrating and emitting noises through the T/C body, exhaust system (Catalyst, Bellows, Pipe, etc) and Intake system (Hoses, Intercooler pipes, Intercooler) as rotating. A turbocharger cold test bench is constructed to reduce these noises, especially for the purpose of realizing transient operating environment and oil temperature control to simulate the vehicle operating characteristics with intake system and exhaust system. This research laid the groundwork to develop a lower noise level T/C through understanding the mechanism of the noise source of T/C.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.522-527
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• 1997

A total of 386 critical flow data points from 19 runs of 27 runs in the Marviken Test were selected and compared with the predictions by the correlations based on the critical flow scaling parameters. The results show that the critical mass flux in the very large diameter pipe can be also characterized by two scaling parameters such as discharge coefficient and dimensionless subcooling( $C_{d, ref}$ and $\Delta$ $T^{*}$$_{sub}$). The agreement between the measured data and the predictions are excellent.t.ons are excellent.t.

• Journal of Aerospace System Engineering
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• v.4 no.1
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• pp.10-14
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• 2010

The Fuel system of T-50 Advanced Trainer is equipped with two boost pump and fuel flow proportioner for feeding fuel to turbo jet engine. when an unexpected failure occurs, they can feed the fuel to turbo jet engine which fuel quantity required. fuel quantity control method is applied for minimizing the center of gravity change. and fuel quantity control method is controlled by FQMS(Fuel Quantity Measuring System) and FFP(Fuel Flow Proportioner). This paper presents life cycle extension plans of FFP hydraulic motor by design improvements of connecting and arrangement of pipe comparing with KF-16.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.3
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• pp.1-7
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• 2006

By the reason of increased demand of high productivity, the researches on manufacturing process and equipments for reducing cycle time have been made in many directions of a machine tool industries. Especially high productivity is very important to machining center with high-speed spindle. This paper proposed method of reducing T-T(tool to tool) time which results in shorter unclamping time. T-T time varies as factors such as a hydraulic system, a drawbar mass, a flow meter, a disc spring, piston and pipe diameters. In this paper We could find design factors has much influence on decreasing the unclamping time using DOE(Design of Experiment) and optimized the level of the factors using AMESim $4.0^{(R)}$ and visualNastran $4D^{(R)}$ Finally, we have verified improved result of the optimized factors with initial design.

• Proceedings of the SAREK Conference
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• 2004.11a
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• pp.129-129
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• 2004

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2015.08a
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• pp.107-112
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• 2015

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.3
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• pp.239-245
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• 2003

In the nuclear power plant, emergency core coolant system (ECCS) is furnished at reactor coolant system (RCS) in order to cool down high temperature water in case of emergency. However, in this coolant system, thermal stratification phenomenon can occur due to coolant leaking in the check valve. The thermal stratification produces excessive thermal stresses at the pipe wall so as to yield thermal fatigue crack (TFC) accident. In the present study, effects of turbulence penetration on the thermal stratification into T-branches with square cross-section in the modeled ECCS are analysed numerically. $textsc{k}$-$\varepsilon$ model is employed to calculate the Reynolds stresses in momentum equations. Results show that the length and strength of thermal stratification are primarily affected by the leak flow rate of coolant and the Reynolds number of the main flow in the duct. Turbulence penetration into the T-branch of ECCS shows two counteracting effects on the thermal stratification. Heat transport by turbulence penetration from the main duct to leaking flow region may enhance thermal stratification while the turbulent diffusion may weaken it.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.176-182
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• 2018

The purpose of this study was to investigate the safety and rationality of buckling strength and length coefficient by comparing with the design standards of domestic and foreign compression materials based on the buckling test results of circular steel pipe with ball joints. The types of round steel pipes selected for buckling performance evaluation were ø$48.6{\times}2.8t$, ø$60.5{\times}3.2t$ and ø$76.3{\times}3.2t$. For the design of domestic and foreign compression materials, Korea 's Load Resistance and Factor Design, Japan' s Limit State Design, and British Standard BS5950 standard were applied. In this study, we compared and analyzed the buckling performance between the experimental results of the previous research and the domestic and foreign design standards. The results were summarized as follows. As a result of applying the full length of the member to the buckling length in the compression materials design standards of each country, it was 64-89% of the buckling strength by the experiment. Therefore, it is deemed desirable to perform the member design according to the current design standard formula for safety. Experimental results show that the measured buckling strength was 1.02-1.43 times higher than the buckling strength of pure cylindrical steel tubes in the design standards of Korea, Japan and the United Kingdom compression materials. Consequently, it seemed that the buckling strength of individual member in the design of space frame structure should be considered buckling coefficient as the length of pure round steel pipe rather than the length of inter-node.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.11
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• pp.403-408
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• 2014

In the Internet of Things(IoT) era, many of the things or objects that enclose our environments are able to associate with those things on the Internet. To construct IoT systems, it needs to consider a component for acquiring and aggregating of sensory data via things with sensors and instruments, which is connected by diverse networks, in IoT environment. An IoT system is intrinsically distributed in a variety of ways. In addition, to manage an IoT system efficiently, interoperability is needed to meet requirements while the IoT system is designed to deliver data among its applications. In this paper, a reference architecture based on asynchronous messaging is defined and used for designing an IoT system. To apply the architecture, we discuss how to manage data streams with real-time characteristics and make a prototype based on pipe-and-filter to produce and consume them by a pub/sub messaging system NaradaBrokering.