• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.61-68
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• 2015

The function of Feed Water Ring is to provide the flow path from Feedwater Nozzle to inside of SG(steam generator). Significant amounts of general FAC on the outside of the Feed Water Ring are not likely due to the low flow velocities in this area. However, on the interior of the Feed Water Ring, there may be areas of local higher flow velocity which could lead to higher FAC rates. These may include the inlet tee from the Feedwater Nozzle into the Feed Water Ring, the areas where the Feed Water Ring changes diameter, and especially the entrance area to the J-Nozzles. In this paper, the results of root cause analysis of through-wall hole observed at domestic WH 51F SG Feed Water Ring and its effect on the integrity and performance of SG are described. And, the maintenance strategy for WH 51F SG Feed Water Ring and the monitoring strategy for Downcomer Feed Water Ring of CE System 80 SG are presented.

• The Korean Journal of Ecology
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• v.10 no.3
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• pp.151-159
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• 1987

Relationships between soil factors and the growth of annual ring of Pinus densiflora grown on stony mountain were investigated at two sites of the different parent rocks: the one was formed by granite at Mt. Gwanag, Seoul and the other feldspar porphyry at Mt. Bipa, Daegu. The growth of annual ring was influenced by the physical factors of soil, such as soil depth, field caacity and water content of soil, rather than by the KDICical factors, such as total nitrogen, potassium, and calcium of soil. Of the soil factors affecting the growth of annual ring, soil depth, field capacity, water content of soil and organic matter closely interrelated with each other. All of these factors influenced water content of soil which might affect the water potential of Pinus densiflora leaves. In fact, the leaf water potential, affecting as the main factor for the growth of annual ring, of the pine grown in a deep soil was higher than that of the pine in a shallow soil.

• Journal of the Korean Wood Science and Technology
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• v.33 no.2 s.130
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• pp.17-23
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• 2005

Juvenile and transitional-juvenile wood samples from loblolly pine (Pinus taeda) were immersed in water to investigate longitudinal and tangential swelling properties. Increment cores from twenty-six loblolly pine trees were sampled at breast height (1.37 m). Earlywood rings 5 and 9 were separated from the core, extracted, oven-dried and immersed in water at room temperature. The variance in longitudinal swell was significant for ring 5 compared to ring 9 (p = 0.001). It was found that tangential swell might predict longitudinal swelling of juvenile wood at ring 9 but not at ring 5. Poor correlation in ring 5 suggests that swelling response in younger juvenile wood may differ. The swell response at ring 5 did not follow the shrinkage models discussed in the literature while ring 9 adhered to the expected curve.

• Journal of Korean Society on Water Environment
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• v.31 no.1
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• pp.19-28
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• 2015

The purpose of this research is reconstruction of annual precipitation based on Tree-ring series at Seorak mountain and examine its effectiveness. To do so we performed nonlinear time series characteristics test of Tree-ring series and reconstructed annual precipitation of Gangneung from 1687 to 1911 using Artificial neural network and Nonlinear autoregressive exogeneous input (NARX) model which reflects stochastic properties. As a result, Tree-ring series at Seorak Mountain shows nonlinear time series property and reconstructed annual precipitation series drawn from NARX is similar in statistical characteristics of observed annual time series.

• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.38-49
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• 2006

LNG storage in lined rock cavern demands various techniques concerned with rock mechanics, thermo-mechanics and hydrogeology in design, construction and maintenance stage. LNG pilot cavern was constructed in Daejeon in order to verify these techniques. In this paper, evaluation of drainage system and ice ring formation was studied by numerical simulation. By Modflow analysis in the viewpoint of aquifer and Seep/W analysis in the viewpoint of flow system, it was verified that the drainage system in the pilot cavern was efficiently operated. Since ice ring formation can be simulated by interactive relation between heat transfer and water flow, coupled analysis of those was performed. In this analysis, the position of ice ring was presumed and it was demonstrated that the formation is affected by velocity and direction of groundwater flow.

• Tribology and Lubricants
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• v.27 no.5
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• pp.240-248
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• 2011

Mechanical face seal installed in primary heat transport pump used for heavy water reactor prevents leakage of working fluid using thin working fluid film between primary seal ring and mating ring. If the leakage of working fluid exceeds the allowable volume, serious accident can be happened by the trouble of primary heat transport pump. The thinner fluid film exists between primary seal ring and mating ring, the less working fluid leaks out. On the other hand, if the thickness of fluid film is not enough, the life of mechanical face seal will be reduced by friction and wear. Therefore appropriate design is necessary to maximize the performance and life of mechanical face seal. In this study, numerical analysis using finite volume method was conducted to investigate the performance of mechanical face seals which have same deep straight groove and 11 different net coning values. As results, equilibrium clearance between primary seal ring and mating ring, leakage volume of working fluid, friction torque on sealing surface and stiffness of working fluid film were obtained. With increasing net coning value, equilibrium clearance and leakage volume increase, and friction torque and stiffness of fluid film decrease.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.792-796
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• 2005

The methods of times series analysis have been recognized as important tools for assisting in solving problems related to the management of water resources. Especially, After more than 40 years the so-called Hurst effect remains an open problem in stochastic hydrology. Until now, its existence has been explained fly R/S analysis that roots in early work of the British hydrologist H.E. Hurst(1951). Today, the Hurst analysis is mostly used for the hydrological studies for memory and characteristics of time series and many methodologies have been developed for the analysis. So, there are many different techniques for the estimation of the Hurst exponent(H). However, the techniques can produce different characteristics for the persistence of a time series each other. We found that DFA is the most appropriate technique for the Hurst exponent estimation for both the shot term memory and long term memory. We analyze the SOI(Southern Oscillations Index) and 6 tree-ring series for USA sites by means of DFA and the BDS statistic is used for nonlinearity test of the series. From the results, we found that SOI series is nonlinear time series which has a long term memory of H=0.92. Contrary to earlier work of Rao(1999), all the tree- ring series are not random from our analysis. A certain tree ring series show a long term memory of H=0.97 and nonlinear property. Therefore, we can say that the SOI and tree-ring series may show long memory and nonlinearity.

• Tunnel and Underground Space
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• v.25 no.1
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• pp.46-55
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• 2015

A water tube with detonating cord was devised to control the blast dust. Water diffusion experiments with different detonating cord positions were conducted during the series of experiments to optimize the design parameters of the tube. Images from high speed camera were analyzed to evaluate the results. AUTODYN program was adopted to simulate the diffusion process of water and compared with the images. Diffusion of water shows cross flow in case of external charge while the internal case shows radial flow. A bubble ring was formed during the numerical analysis of internal charge case as occurred in underwater blast. An additional bubble ring was formed by the reflection pressure from the ground. And the Weber number was determined as sufficient for spray atomization performance of the water tube.

• Journal of the Korean Society of Marine Environment & Safety
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• v.14 no.2
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• pp.157-162
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• 2008

The ship's maneuverability is the important factor to avoid ship's collisions. The ship's maneuverability is usually measured in a deep water, and the turning ability is decreased and the course stability is improved in a shallow water. The variation of the turning ability could cause the risk of collision. In this paper, we proposes application technique of Variable Safe-Guard Ring to consider the shallow water effect and to be simple to estimate the grade of collision risk simultaneously. Through the mathematical simulation, the availability of new method was varified. Therefore this method is expected enough to support a maneuver for collision avoidance.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.531-536
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• 2013

An automatic wax-ring manufacturing system for silk coating was developed, which consisted of a container, pallet with a cooling part, injection port, and removing device. The removing device is a system to load, lift, and cut the wax-ring, which is widelyused for various silk-coating industrial purposes. A novel removing device equipped with a water cooling circulation system is proposed in this paper. It has the benefit of easy control, as well as the convenience of loading and unloading without the use of other equipment. Three-dimensional modeling techniques were adopted to develop integrated functions for the automatic wax-ring manufacturing system, which made it possible to confirm the smooth integration/interface of each part and the system's interrelations with other manufacturing systems.