• 한국해양공학회지
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• 제23권6호
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• pp.111-116
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• 2009

The cracking due to hydration heat in mass concrete must be resolved to improve the stability and durability of concrete structures. In this study, the economic efficiency was improved by replacing a copper pipe with a steel one for the heat pipe, and the heat pipe was standardized to significantly improve the operation efficiency, such as the processing, transport, assembly, and construction time. As a result of the experiment, the peak temperature of the ICSHP, ISSHP, and ISUHP specimens decreased by about $7.2{\sim}10.9^{\circ}C$ compared to the OPC specimen and the probability of a thermal crack being generated in the ICSHP, ISSHP, and ISUHP specimens decreased by up to 84~88%.

• 태양에너지
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• 제12권3호
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• pp.116-125
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• 1992

증발부를 접시형으로 하고 응축부를 나선형 그루우브로 하는 히이트파이프에서 움직이지 않는 경우와 회전을 하는 경우 입 열량에 따라 벽면과 증기의 온도분포를 구하여 전열특성을 연구하였다. 본 연구에 사용된 히이트파이프는 단순 히이트파이프보다 우수한 전열특성을 가지며, 히이트파이프의 열전달은 입열량과 회전수가 증가하면 증가하였다.

• 대한기계학회논문집B
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• 제35권8호
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• pp.799-804
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• 2011

본 논문에서는 자연채광 시스템 LFLP(Linear Fresnel Light Pipe)와 DBLP(Double Blind Light Pipe)시스템을 비교하였다. LFLP시스템은 평행한 빛을 선형프레넬렌즈를 이용하여 선형 형태로 빛으로 집광하여 자연채광에 이용하는 시스템이며, DBLP시스템은 베네시안 형태의 블라인드를 이용하여 빛을 반사시켜 자연채광에 이용하는 시스템이다. DBLP시스템은 LFLP시스템을 개선한 것으로 시스템 앞쪽에 위치한 블라인드는 태양의 고도에 따른 빛을, 뒤쪽에 위치한 블라인드는 태양의 방위각에 따른 빛을 변광부로 반사시키도록 설계 되었다. DBLP시스템의 변광부는 콘모양으로 이루어 져 있으며 블라인드에 의해 반사된 빛을 산광부로 보내주는 역할을 하며, 산광부로 들어온 빛은 실내조명에 사용된다. 따라서 맑은날(clear sky)을 기준으로 두 시스템의 효율을 비교하면 DBLP시스템이 LFLP시스템보다 세배 높게 나오는 것으로 나타났다.

• 복합신소재구조학회 논문집
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• 제6권4호
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• pp.16-23
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• 2015

The industrialization and urbanization forced to increase the density of pipelines such as water supply, sewers, and gas pipelines. The materials used for the existing pipe lines are mostly composed of concretes and steels, but it is true that the development for more durable and efficient materials has been continued performed to produce long lasting pipe lines. Recently, underground pipes serve in diverse applications such as sewer lines, drain lines, water mains, gas lines, telephone and electrical conduits, culverts, oil lines, etc. In this paper, we present the result of investigation pertaining to the structural behavior of unplasticized polyvinyl chloride (PVC-U) flexible pipes buried underground. In the investigation of structural behavior such as a ring deflection, pipe stiffness, 4-point bending test, experimental and analytical studies are conducted. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is about 8% although there are significant variations in the mechanical properties of the pipe material. In addition, it was found by the 4-point bending test there is no problem in the connection between the pipes by coupler.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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• pp.95-101
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• 1996

In this paper, the steady 2-dimensional model for a long horizontal line with different end temperatures undergoing natural convection at very high Rayleigh number is proposed to numerically investigate the heat transfer and flow characteristics. The dimensionless governing equations are solved by using SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm which is developed using control volumes and staggered grids. The numerical results are verified by comparison with the operating PWR test data. The analysis focuses on the effects of variation of the heat transfer rates at the pipe surface, the thermal conductivities of the pipe material and the thickness of the pipe wall on the thermal stratification. The results show that the heat transfer rate at the pipe surface is the controlling parameter. A significant reduction and disappearance of thermal stratification phenomenon is observed at the Biot number of 5.0$\times$10$^{-2}$. The results also show that the increment of the thermal conductivity and thickness of the wall weakens the thermal stratification and somewhat reduces azimuthal temperature gradient in the pipe wall. Those effects are however minor, when compared with those due to the variation of the heat transfer rates at the surface of the pipe wall.

• Nuclear Engineering and Technology
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• 제46권6호
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• pp.817-824
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• 2014

To ensure the safety of research reactors, the water level must be maintained above the required height. When a pipe ruptures, the siphon phenomenon causes continuous loss of coolant until the hydraulic head is removed. To protect the reactor core from this kind of accident, a siphon breaker has been suggested as a passive safety device. This study mainly focused on two variables: the size of the pipe rupture and the timing of air entrainment. In this study, the size of the pipe rupture was increased to the guillotine break case. There was a region in which a larger pipe rupture did not need a larger siphon breaker, and the water flow rate was related to the size of the pipe rupture and affected the residual water quantity. The timing of air entrainment was predicted to influence residual water level. However, the residual water level was not affected by the timing of air entrainment. The experimental cases, which showed the characteristic of partical sweep-out mode in the separation of siphon breaking phenomenon [2], showed almost same trend of physical properties.

• Nuclear Engineering and Technology
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• 제30권6호
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• pp.581-591
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• 1998

Numerical analysis was peformed for the two-dimensional turbulent natural convection for a long horizontal line with different end temperatures. The turbulent model has been applied a standard k-$\varepsilon$ two equation model of turbulence similar to that the proposed by the Launder and Spalding. The dimensionless governing equations are solved by using SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm which is developed using control volumes and staggered grids. The numerical results are verified by comparison with the operating PWR test data. The analysis focuses on the effects of variation of the heat transfer rates at the pipe surface, the thermal conductivities of the pipe material and the thickness of the pipe wall on the thermal stratification. The results show that the heat transfer rate at the pipe surface is the controlling parameter for mitigating of thermal stratification in the long horizontal pipe. A significant reduction and disappearance of the thermal stratification phenomenon is observed at the Biot number of 4.82$\times$10$^{-1}$ . The results also show that the increment of the thermal conductivity and thickness of the wall weakens a little the thermal stratification and somewhat reduces temperature gradient of y-direction in the pipe wall. These effects are however minor, when compared with those due to the variation of the heat transfer rates at the surface of the pipe wall.

• International Journal of Naval Architecture and Ocean Engineering
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• 제12권1호
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• pp.596-604
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• 2020

Previous studies on pipe auto-routing algorithms generally used such algorithms as A*, Dijkstra, Genetic Algorithm, Particle Swarm Optimization, and Ant Colony Optimization, to satisfy the relevant constraints of its own field and improve the output quality. On the other hand, this study aimed to significantly improve path-finding speed by applying the Jump Point Search (JPS) algorithm, which requires lower search cost than the abovementioned algorithms, for pipe routing. The existing JPS, however, is limited to two-dimensional spaces and can only find the shortest path. Thus, it requires several improvements to be applied to pipe routing. Pipe routing is performed in a three-dimensional space, and the path of piping must be parallel to the axis to minimize its interference with other facilities. In addition, the number of elbows must be reduced to the maximum from an economic perspective, and preferred spaces in the path must also be included. The existing JPS was improved for the pipe routing problem such that it can consider the above-mentioned problem. The fast path-finding speed of the proposed algorithm was verified by comparing it with the conventional A* algorithm in terms of resolution.

• Nuclear Engineering and Technology
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• 제53권12호
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• pp.3879-3891
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• 2021

A heat pipe residual heat removal system is proposed to be incorporated into the reactor driven subcritical (RDS) facility, which has been proposed by MIT Nuclear Reactor Laboratory for testing and demonstrating the Fluoride-salt-cooled High-temperature Reactor (FHR). It aims to reduce the risk of the system operation after the shutdown of the facility. One of the main components of the system is an air-cooled heat pipe heat exchanger. The alkali-metal high-temperature heat pipe was designed to meet the operation temperature and residual heat removal requirement of the facility. The heat pipe model developed in the previous work was adopted to simulate the designed heat pipe and assess the heat transport capability. 3D numerical simulation of the subcritical facility active zone was performed by the commercial CFD software STAR CCM + to investigate the operation characteristics of this proposed system. The thermal resistance network of the heat pipe was built and incorporated into the CFD model. The nominal condition, partial loss of air flow accident and partial heat pipe failure accident were simulated and analyzed. The results show that the residual heat removal system can provide sufficient cooling of the subcritical facility with a remarkable safety margin. The heat pipe can work under the recommended operation temperature range and the heat flux is below all thermal limits. The facility peak temperature is also lower than the safety limits.

• Tribology and Lubricants
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• 제22권4호
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• pp.225-229
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• 2006

The issue with the drainpipe now a day is that they are laid underground. Causing us to perform additional work to repair, such as digging up the ground and peeling off the insulator that surrounds the pipe. And such series works are difficult that concession appears from government and municipal office. However, if we can save time and money. Performance of piping robot that we are studied in existing session through fixing unit and improvement of cutting bit shorten and wished to heighten work efficiency. And we are trying to develop a unit that can cut up the projecting parts which connects with the interior part of the drainpipes.