• Journal of Advanced Marine Engineering and Technology
• /
• 제29권1호
• /
• pp.86-97
• /
• 2005

Nowadays, Water Mist Fire Extinguishing System is increasingly used in maritime field for various application. The fire extinguishing capability of the system should be verified by hydraulic calculation in the same manner as the conventional water based fire extinguishing system such as sprinkler system. water spray system and etc. Additionally, the review of effectiveness of friction loss calculation method used for hydraulic calculation is needed because the pipe flow characteristic of its piping system has higher Reynolds number than that of the conventional system. In this paper the review work was carried out based on the NFPA Code 750.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2010년 춘계학술대회논문집
• /
• pp.127-128
• /
• 2010

As P-new-city is planned and constructed, district eating utilizing an existing near-by power plant's waste heat is considered as an economic and environment friendly way of providing heating to the new city. Many pipeline diameters and pumping station location and capacity were assumed, investigated and optimized, to satisfy the customers' heat demand considering common district heating pipe-network design and construction practice, and also and construction, pumping station land price and construction and the pumping energy cost during lifetime of DH systems.

• 한국수자원학회논문집
• /
• 제40권4호
• /
• pp.325-334
• /
• 2007

본 연구에서는 점진적인 유량 및 압력이 변화하는 상수관망에서 Rigid Water Column Theory를 이용하여 정상모형의 확장기간 모의해석보다 정확하고 수충격 해석보다는 계산비용 및 노력 측면에서 효율적으로 장시간 부정류 해석 모형을 개발하였다. 개발된 모형을 이용하여 실제관망에 대하여 24 시간 열 수요량을 고려한 부정류 해석 및 밸브폐쇄로 인한 수충격해석 모의에 적용하였고 해석 결과는 다음과 같다. 24 시간 일변화 모의의 경우에 수요량이 증가할 경우 모든 관로에서 압력감소가 나타났으며 수요량이 감소할 경우 압력증가가 나타났다. 그리고 일 수요량의 변화에 따라 나타난 절점에서의 유량 및 압력 변화폭은 각 절점마다 다르고 수요량과 유량의 변화양상이 반대로 나타나는 관로도 발생하고 있으며 KYPIPE2의 결과와 본 모형의 유량 및 압력차이도 발생하고 있어 상수관망의 동역학적 해석의 필요성이 대두되었다. 밸브폐쇄로 인한 수충격모의에 본 모형이 적용되었을 때 본 모형은 유체의 압축성을 무시함으로 인해 밸브 완전 폐쇄와 동시에 압력과 유량의 변화가 전 관망에 발생하였고 수충격모형은 유체의 탄성으로 인해 발생된 압력파의 도달시간이 필요함으로 압력과 유량변화가 지체되어 나타났으나 전체적인 변화양상 및 변화폭의 크기 등은 유사한 경향을 나타내어 본 모형의 적용성을 입증하였다. 본 연구에서 개발된 프로그램은 장기간 점진적인 관로 부정류를 비교적 정확하게 해석할 수 있을 것으로 판단되며 이를 이용하여 관로내 오염물의 확산해석, 수요량을 고려한 절점에서의 압력제어 및 누수저감, 장기간 관로내의 유량 및 압력 변화를 고려한 관망관리 등의 분야에서 효율적으로 이용될 수 있을 것으로 기대되었다.

• 상하수도학회지
• /
• 제26권5호
• /
• pp.609-617
• /
• 2012

A dynamic water quality model is presented in order to simulate water quality under slowly varying flow conditions over time. To improve numerical accuracy, the proposed model uses a lumped system approach instead of extended period simulation, unlike the other available models. This approach can achieve computational efficiency by assuming liquid and pipe walls to be rigid, unlike the method of characteristics, which has been successfully implemented in rapidly varying flows. The discrete volume method is applied to resolve the advection and reaction terms of the transport equation for water quality constituents in pipes. Numerical applications are implemented to the pipe network examples under steady and unsteady conditions as well as hydraulic and water quality simulations. The numerical results are compared with EPANET2, which is a widely used simulation model for a water distribution system. The model results are in good agreement with EPANET2 for steady-state simulation. However, the hydraulic simulation results under unsteady flows differ from those of EPANET2, which causes a deviation in water quality prediction. The proposed model is expected to be a component of an integrated operation model for a water distribution system if it is combined with a computational model for rapidly varying flows to estimate leakage, pipe roughness, and intensive water quality.

• 물과 미래
• /
• 제29권1호
• /
• pp.141-150
• /
• 1996

상수관망에서의 압력과 유량의 정상상태 해석은 수공학에 있어서 매우 중요한 문제이다. 이 경우의 기본방정식은 유량을 미지값으로 하는 연속 방정식과 에너지 방정식으로 구성되는 비선형 연립방정식이다. 이 연립방정식을 풀기 위하여 선형화 기법을 도입하여 반복적으로 해석하였고 그 결과로 나타나는 선형 연립방정식의 효율적인 해석을 위해서 frontal기법을 사용하여 계산하였다. 이 기법은 계수 메트릭스의 '0'이 아닌 요소만을 모아 계산하므로 효과적으로 분산 메트릭스를 해석할 수 있었고, 기존의 band 해석기법보다 적은 앙의 계산 기억용량으로 계산시간을 크게 단축시켜 해석할 수 있었다. 본 연구에서 제시한 상수관망의 해석모형은 기존의 해석방법보다 정확하고 효율적인 계산기법으로서 제시하였다.

• 설비공학논문집
• /
• 제12권12호
• /
• pp.1098-1125
• /
• 2000

A review on the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering in 1998 and 1999 has been done. Focus has been put on current status of research in the aspect of heating, cooling, ventilation, sanitation and building environment. The conclusions are as follows. 1) A review of the recent studies on fluid flow, turbomachinery and pipe-network shows that many experimental investigations are conducted in applications of impingement jets. Researches on turbulent flows, pipe flows, pipe-networks are focused on analyses of practical systems and prediction of system performance. The results of noise reduction in the turbomachinery are also reported. 2) A review of the recent studies on heat transfer analysis and heat exchanger shows that there were many papers on the channel flow with the application to the design of heat exchanger in the heat transfer analysis. Various experimental and numerical papers on heat exchanger were also published, however, there were few papers available for the analysis of whole system including heat exchanger. 3) A review of the recent studies on heat pump system have focused on the multi-type system and the heat pump cycle to utilize treated sewage as the heat source. The defrosting and the frosting behaviors in the fin-tube heat exchanger is experimentally examined by several authors. Several papers on the ice storage cooling system are presented to show the dynamic simulation program and optimal operation conditions. The study on the micro heat pipes for the cooling of high power electronic components is carried out to examine the characteristics of heat and mass transfer processed. In addition to these, new type of separate thermosyphon is studied experimentally. 4) The recent studies on refrigeration/air conditioning system have focused on the system performance and efficiency for new alternative refrigerants. New systems operating with natural refrigerants are drawing lots of attention. In addition to these, evaporation and condensation heat transfer characteristics of traditional and new refrigerants are investigated for plain tubes and also for microfin tubes. Capillary tubes and orifice are main topics of research as expansion devices and studies on thermophysical properties of new refrigerants and refrigerant/oil mixtures are widely carried out. 5) A review of the recent studies on absorption cooling system shows that numerous experimental and analytical studies on the improvement of absorber performance have been presented. Dynamic analysis of compressor have been performed to understand its vibration characteristics. However research works on tow-phase flow and heat transfer, which could be encountered in the refrigeration system and various phase-change heat exchanger, were seemed to be insufficient. 6) A review of recent studies on duct system shows that the methods for circuit analysis, and flow balancing have been presented. Researches on ventilation are focused on the measurement of ventilation efficiency, and variation of ventilation efficiency with ventilation methods by numerous experimental and numerical studies. Furthermore, many studies have been conducted in real building in order to estimate indoor thermal environments. Many research works to get some information for cooling tower design have been performed but are insufficient. 7) A review on the recent studies on architectural thermal environment and building mechanical systems design shows that thermal comfort analysis is sitting environment, thermal performance analysis of Korean traditional building structures., and evaluation of building environmental load have been performed. However research works to improve the performance of mechanical system design and construction technology were seemed to be insufficient.

• 한국농공학회논문집
• /
• 제59권4호
• /
• pp.17-26
• /
• 2017

In this study, EPANET model which is using on the pipe network analysis was applied to Haenam irrigation district has provided irrigation water by pipeline system about 1,125ha and then have built pipe network to study area and supply performance evaluation of existing structure was analyzed by SPA (Single Period Analysis) in EPANET. As model results of simulation average ratio of maximum supply quantity/irrigation water requirements(base demand) was analyzed by 2.63. It means also that was analyzed as being capable of ensuring the water supply capacity. It was provided the necessary information for the maintenance facility through analyzed hydraulic behaviors in the pipeline inside such as flow velocities, pressures and hydraulic grade lines. It was satisfied with the allowable design criteria that was compared analyzed results with presented allowable design standards at agricultural production infra improvement project planning and design (Pipeline design standard). In order to analyze efficiency promotions of irrigation water, using Extended Period Simulation it was compared supply quantity with irrigation water requirements while pumps set operating pattern in 24 hours, then efficiency promotions of irrigation water was determined through analyzed oversupply water quantity and occurrence time by branch lines. According to results for oversupply quantity in Haenam district by time and end of branch lines efficiency promotions of irrigation water was suggested from 0.33 % to 37.59 %. To draw reasonable operating rules for water use and through this research, it is expected to be helpful for efficient water use and operational management of agricultural pipeline system to the current agricultural irrigation.

• Korean Journal of Hydrosciences
• /
• 제8권
• /
• pp.31-40
• /
• 1997

Flow carrying capacity of water distribution systems is getting reduced by deterioration of pipes in the systems. The objective of this paper is to present a managerial decision-making model for the rehabilitation of water distribution systems with a mininum cost. The decisions made by the model also satisfy the requirements for discharge and pressure at demanding nodes in the systems. Replacement cost, pipe break repair cost, and pumping cost are considered in the economic evaluation of the decision along with the break rate and the interest rate to determine the optimal replacement time for each pipe. Then, the hydraulic integrity of the water distribution system is checked for the decision by a pipe network simulator, KYPIPE, if discharge and pressure requirements are satisfied. In case the system does not satisfy the hydraulic requirements, the decision made for the optimal replacement time is revised until the requirments are satisfied. The model is well applied to an existing water distribution system, the Seoul Metropolitan Water Supply System (1st Phase). The results show that the decisions for the replacement time determined by the economic analysis are accepted as optimal and hydraulic integrity of the system is in good condition.

• 한국공간정보시스템학회 논문지
• /
• 제2권2호
• /
• pp.75-84
• /
• 2000

국가지리정보체계사업을 시작으로 여러 응용분야에서 지리정보시스템을 구축하고 있으며 특히 지자체에서는 도시정보화 차원에서 UIS(Urban Information System;도시정보시스템)를 구축하고 있다. 지자제의 업무들은 지자체의 상황에 따라 조금씩 차이를 보이지만 업무 단위로 따져볼 때 공통적으로 수행되는 업무들이 많으며, 지리정보 관련 업무 또한 예외가 아니다. 지금까지 각 지자체의 도시정보시스템은 공통업무에 대하여 중복개발이 불가피하였으며, 재사용성을 기대하기 어려웠다. 이런 비효율성을 극복하는 방안으로 컴포넌트 기술이 대두되었으며, 컴포넌트 기술을 이용하여 업무변화에 유연하고 재활용을 극대화할 수 있는 업무컴포넌트 개발이 필요하게 되었다. 본 논문은 지자체의 지리정보 관련 업무의 하나인 상수도 업무 중 상수관거의 유량 및 손실수두산정을 위한 상수도 관망해석 컴포넌트 설계를 제시하였다. 상수도 관망해석 컴포넌트는 상수도 초기유량을 산정하고, 산정된 초기유량을 토대로 절점 및 상수관거의 유량 및 손실수두를 산출하여, 상수관거 신설 및 확장에 대한 의사결정을 지원할 수 있도록 설계하였다. 컴포넌트 설계과정은 표준업무를 지원할 수 있도록 업무분석을 수행하였으며, 이의 결과물로 상수도 관망해석 알고리즘을 도출하였다. 그리고 도출된 알고리즘을 기반으로 상수도 관망해석 업무를 수행하는 상수도 관망해석 컴포넌트를 설계하고 설계 내용을 UML(Unified Modeling Language)로써 명세화하였다. 현재 설계에 따라 상수도 관망해석 컴포넌트가 개발되고 있으며, 개발된 컴포넌트를 이용한 상수도 관망해석 시스템을 구축할 예정이다. 추후에는 상수도 관망해석 컴포넌트와 상수도 업무 컴포넌트와의 통합부분에 대한 연구가 진행되어야 할 것이다.

• 한국물환경학회지
• /
• 제32권4호
• /
• pp.367-374
• /
• 2016

In this study, the RDII impact on sewer designing in the upstream monitoring area (A site) was considered. Based on the long-term (1/1/2011~12/31/2011) rainfall and flow data consisting of 10-min interval sampling in the nearby design area (B site), the maximum RDII/DWF ratio was selected. The sewer network system at B site was evaluated by the Manning equation. Scenario 1 considering the hourly maximum flow with respect to the flow velocity showed that none of the sewer pipes satisfied the minimum flow velocity condition (0.6 m/s), and 40 pipes did not achieve half of the velocity condition. In scenario 2 considering I/I, 1 the pipes satisfied 0.6 m/s, and 35 pipes showed 0.3 m/s. Scenario 3 reflected the effect of RDII. Velocities in 26 pipes were less than 0.3 m/s, and 4 pipes satisfied the velocity condition. With respect to the allowance rate, 17 pipes were shown to have more than 99%, and none of the pipes satisfied less than 95% of the allowance rate in scenario 1. In scenario 2, 17 Ed: Per the Table pipes showed more than 99% and one pipe showed less than 95%. In scenario 3, 16 pipes showed more than 99% of the allowance rate, and 19 pipes showed less than 95%. Based on these results, it is predicted that deposition would occur due to the slow flow velocity; however, capacity would not be a problem.