• Journal of Advanced Marine Engineering and Technology
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• v.30 no.3
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• pp.396-402
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• 2006

In this study, dynamic characteristics of water hammer pressure in water supply piping system with water hammer arrester has been investigated experimentally to characterize the transient pressure of water hammer in high rise building. Experiments were conducted to verify the absorption effects by water hammer arresters with 3 different gas volumes of water hammer pressure generated by sudden valve closure. As the results, it has been found that zoning and sizing of pipe diameter for suitable flow velocity and water hammer arresters with effective pressure absorption capacity have to be installed to protect water hammer problems in building water supply piping system.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.1
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• pp.120-126
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• 2001

This study deals with a flow and pressure ripple characteristics for a hydrostatic transmission(HST) consisting of a vari-able axial piston pump connected in an open loop to a fixed displacement axial piston motor. These flow ripples produced by pump and motor in HST interacts with the source impedances of the pump or motor and dynamic characteristics of the connected pipeline, and results in a pressure ripples, Pressure ripples. Pressure ripples in HSP is major source of vibration, which can lead to fatigue failure of components and cause noise. In this paper, the flow ripples generated by a swash plate type axial piston pump or motor in HST are measured by making use of hydraulic pipeline dynamics and the measured pressure data at two points along the pipeline. By using the self-checking functions, the validity of the method us investigated by comparison with the measured and estimated pressure ripples at the halfway section of the pipeline, and good agreement is achieved.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 1999.12a
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• pp.26-29
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• 1999

An integrated sewer management system was developed for the analysis of sewer flow and for optimal operation of sewer works using ArcView and SWMM. SWMM and ArcView were dynamically linked together using Avenue in order to construct user-friendly management system. The developed system was applied to a residential area in Choonchun city to verify its utilities. All the relevant field data were analyzed on the basis of developed system, and the modeling of sewer flow was implemented using MET, RUNOFF, TRANSPORT in SWMM. As this system can provide comprehensive prediction of flow and pollution profiles, it could serve as a tool not only for optimal management, but also for decision support system to examine the efficiency of planning and implementation of sewer projects.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.381-385
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• 2009

This paper describes performance characteristics of a centrifugal fan having a different volute casing. The centrifugal fan has a backward blade type, and is used in a refuse collecting system. The flow characteristics inside the components are analyzed by three-dimensional Navier-Stokes analysis, and also compared to the results by experiments. Distributions of pressure and efficiency obtained by numerical simulation has a good agreement with the experimental results. Throughout the numerical simulation of the centrifugal fan, a fan efficiency is increased by decreasing local losses in the blade passage. It is found that the fan efficiency is enhanced by decreasing the distance between the shroud of a impeller and casing. Detailed flow analysis is also analyzed and discussed using the results obtained by numerical simulation.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.435-436
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• 2015

국내 도심지 전력계통망을 구성하고 있는 지중송전선로는 345kV, 154kV XLPE 케이블로 건설되고 있다. 도심지의 확장과 수요증가로 선로의 대용량화, 대도체화가 진행되고 있고, 송전용량 증대를 위한 신기술도 역시 지속 발전하고 있다. 새로운 신자재, 신공법이 아닌 케이블 재배치, 매설심도 조정 등 시스템 디자인을 통해 허용전류를 극대화하고, 경제적인 대용량 송전선로를 구축하기 위하여 연구한 송전케이블의 관로 최적시공방안을 소개하고자 한다.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.3
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• pp.33-38
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• 2002

This paper deals with pressure ripple attenuation far separated-type Hydrostatic Transmission (HST) consisting ova variable axial piston pump connected in an open loop to a fried displacement axial piston motor. Pressure ripples in HST is major source of vibration which can lead to fatigue failure of components and cause noise. In order to reduce the pressure ripple, an annular tube tripe hydraulic filter is proposed to attenuate pressure ripples with the high frequencies components to achieve better noise reduction in HST. The basic principle of a hydraulic filter is allied to propagation of pressure wave, reflection, absorption in cross section of discontinuity and resonance in the hydraulic pipeline. It is experimentally shown that the hydraulic filter attenuates about 30∼40dB of pressure ripple with high frequencies. These results will assist in modeling and design of noise reduction in hydraulic control systems, and provide a means of designing a quieter HST.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.3
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• pp.151-158
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• 2008

The clutch system is a subcomponent of the transmission that is designed to engage and disengage power flow between the engine and the transmission. Recently, the engine power of automobile has been continuously increased because of customer's demand for the bigger one. As the engine power is increased, the vibration transmitted to the hydraulic clutch operating system has been increased. Therefore the demand for the reduction of clutch pedal vibration during the operation has been increased. This paper describes the pressure pulsation reduction characteristics of the damper cylinder which is applied to the hydraulic clutch operating system. And the purpose of this study is to propose an analysis model and investigate the effect of the design variable variations for the hydraulic clutch system. Especially, we studied the effect of damper cylinder parameter variations on the hydraulic clutch system performance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1248-1256
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• 2005

This study was undertaken to investigate the flow characteristics of emulsified fuel with the ultrasonic energy-adding system by using the chaotic method. Efffcts of water contents within emulsified fuel, flow rate and tube length with 5m in diameter from an emulsified chamber has been discussed on the strange attractor and power spectral density function. Five probe sensors were set up from 0.5 to 2.5m by length in 0.5m increments in the tube. In particular, the chaotic features of this system have been practically characterized in terms of chaotic statistics such as the power spectral density function and phase space portraits by resorting to the somewhat noble deterministic chaos theory. In the tube, the dominant frequency increased with increasing water contents and flow rate, but decreased a little with an increase in the length from the emulsified chamber.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.961-965
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• 2004

본 연구에서는 상수관망의 신뢰도 기반 최적화설계에서 시스템 구성물의 기계적 고장의 영향뿐만이 아니라 관로의 수리학적 능력과 절점수요에서의 불확실성이 결합되어 인식할 수 있는 새로운 방법을 제시하였다. 수질과 연관된 신뢰도 문제는 고려하지 않았고 단지 수량의 항으로 수요자들의 요구량을 충족시키기 위해 급수관망의 공급능력을 고려하였다. 수량의 관점에서 관망의 신뢰도의 측정은 절점 수요량들이 항상 만족되어진다고 가정한 상태에서 불충분한 수두의 정도를 이용한다. 따라서 절점신뢰도는 공급되는 절점수두가 미리 규정된 최소수두를 상외하거나 충족시키는 확률로 정의되어진다. 이 모형에 의해 설계된 상수관망은 정상관망 상태구성(구성물의 고장이 발생하지 않았을 경우)와 미리 정해진 고장 시나리오의 범위와 연관된 관망의 악화된 구성상태 모두에서 절점에서의 임의의 수요량과 임의의 수리학적 능력하에서 상수공급량의 항으로 규정된 수준의 서어비스의를 제공할 수 있다. 본 모형은 다양한 관망구성에 내해 상수관망의 신뢰도의 정도를 결정하기 위해서 Monte-Carlo 모의를 이용하였다. 실제 상수관망에 내해 본 인구모형을 이용하여 신뢰도 및 최적화 해석이 수행되었다. 해석결과 본 모형은 합리적으로 관망 전체에 대해 합리적인 범위의 신뢰도를 유지하면서 관망의 건설비용의 치적화가 수행될 수 있었다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.953-954
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• 2006

Guaranteeing survivability is the most important issue in designing and operating optical transmission network. For dual system of optical transmission network, there should be two routes of the optical to prepare an error in one cable route. If a route is selected based on the standard of unused optical core when choosing an optical cable, dual optical cable routes could be installed in duplicated line. This paper simulates the installation of duplicated line when designing an optical transmission network, detects the status of duplicated line that could happen during transfer construction and switching and accomplishes a system that can confirm the location based on a map.