• Journal of Korean Society of Water and Wastewater
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• v.16 no.6
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• pp.726-732
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• 2002

Pressure drop could happen in the water distribution systems due to pipe breaks or maintenance. The pressure drop causes the water service shutdown and nodal water demands should be reduced in some areas. The conventional analysis method of water distribution systems can not consider the change of nodal water demands caused by these pressure drops. This study is to investigate the variation of nodal water demands according to the nodal water pressure and its effect on the analysis of water distribution systems. For these purpose, one real water service district was selected as a study area. As a result, nodal water demand patterns according to the water pressure could be suggested. Also, we could confirm that the suggested new analysis method for the water distribution systems which considering water pressure drops could be more reliable than the conventional method.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.6
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• pp.463-474
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• 1997

Metallic elements in dustfall have been known as notable air pollutants directly or indirectly influencing human health and wealth. The first aim of this study was to obtain precise spatial distribution patterns of 5 elements (Pb, Zn, K, Cr, and Al) in dustfall around Suwon area. To predict isometric lines of metal fluxes deposited on unsupervised random sites, the study has applied both spatial statistics as a receptor model and a GIS (geographic information system). Total of 31 sampling sites were selected in the study area (roughly 3 by 3 km grid basis) and dustfall samples were then collected monthly basis by the British deposit gauges from Dec., 1995 to Nov., 1996. The metallic elements in the dustfall were then analyzed by an atomic absorption spectrometer (AAS). On the other hand, a base map overlapped by 7 layers was constructed by using the AutoCAD R13 and ARC/INFO 3.4D. Four different spatial interpolation and expolation techniques such as IDW (inverse distance weighted averaging), TIN (triangulated irregular network), polynomial regression, and kriging technique were examined to compare spatial distribution patterns. Each pattern obtained by each technique was substantally different as varing pollutant types, land of use types, and topological conditions, etc. Thus, our study focused intensively on uncertainty analysis based on a concept of the jackknife and the sum of error distance. It was found that a kriging technique was the best applicalbe in this study area.

• Nuclear Engineering and Technology
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• v.37 no.5
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• pp.503-510
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• 2005

An instrumental neutron activation analysis was used to measure the concentrations of about 24 elements associated with airborne particulates (PM10) that were collected in the most polluted urban region of Daejeon city, Korea from 2000 to 2002. Using the measurement data for various elements, both the extent of elemental pollution in the study area and the seasonality in their distribution characteristics were examined. Examinations of their distribution patterns indicated that most elements with crustal origin tend to exhibit seasonal peaks during spring, while most elements with anthropogenic origin tend to exhibit seasonal peaks during fall or winter. In order to explain the factors regulating their mobilization properties, the data were processed by a factor analysis. Results of the factor analysis suggested competing roles of both industrial and natural source processes, despite that the study site is located at a downwind position of the industrial complex. Based on the overall results of this study, it is concluded that the site may be strongly impacted by man-made sources but the general patterns of elemental distributions in the study area inspected over a seasonal scale are quite consistent with those typically observed from natural environment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.547-554
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• 2016

Analyze the customer daily load patterns, be used to determine the optimal charging and discharging schedule which can minimize the electrical charges through the battery energy storage system(BESS) installed in consumers is an object of this paper. BESS, which analyzes the load characteristics of customer and reduce the peak load, is essential for optimal charging and discharging scheduling to save electricity charges. This thesis proposes optimal charging and discharging scheduling method, using particle swarm optimization (PSO) and penalty function method, of BESS for reducing energy charge. Since PSO is a global optimization algorithm, best charging and discharging scheduling can be found effectively. In addition, penalty function method was combined with PSO in order to handle many constraint conditions. After analysing the load patterns of target BESS, PSO based on penalty function method was applied to get optimal charging and discharging schedule.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.3
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• pp.53-61
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• 1999

Impinging jets are observed when exhaust gases from missiles or V/STOL aircrafts impinge on the ground, flame deflector, ship deck, etc. The flow shows different patterns according to the nozzle geometry, nozzle-to-plate distance, and plate angle, for example. This paper describes experimental works on the phenomena (pressure distribution, occurrence of stagnation bubble, and so on.) when underexpanded supersonic jets impinge on a perpendicular flat plate using a supersonic cold-flow system, and compares the results with those obtained using a shock tunnel. The flow characteristics for the supersonic cold-flow system were also investigated. Surface pressure distribution of supersonic cold-flow system differed from that of shock tunnel because of water and temperature in the low-pressure chamber. Surface pressure distribution as to underexpanded ratio showed similar patterns together.

• Korean Journal of Environmental Biology
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• v.31 no.1
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• pp.1-9
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• 2013

In this study, we tried to describe the distribution patterns of marine opportunistic mollusks in Korean waters where various environmental stresses have been imposed. Five opportunistic molluscan species were found from four types of disturbed benthic environments around Korea. Theora fragilis, Macoma incongrua, Musculista senhousia were typical dominant species mainly in the coastal area such as harbour regions and semi-enclosed regions where their sediments were enriched with organic matter and summer hypoxia occurred. However, in the waste dumping areas located in the Yellow Sea and southeastern shelf, small size bivalves such as Thyasira tokunagai and Raetellops pulchella were typical opportunistic species.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.240-241
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• 2010

Research on modification and replacement of conventional AC distribution system to DC distribution system has been widely conducted. When DC system is applied, it is possible to improve energy transferring efficiency because most of the home appliances are electric loads which require DC input voltage. Furthermore, compatibility with renewable energy sources and secondary batteries should be improved as they are DC based power sources. To design energy efficient DC system, it is important to understand the load characteristics of the electric devices. In this paper, the electric appliances are classified to 3 types: motor, heating, and electric loads and their typical power consumptions are shown. Load patterns of load which can be used in analyzing the designed system are modeled according the statistics. Feasibility of the developed load patterns are verified by applying it in distribution system design tool.

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.6
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• pp.463-474
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• 2001

In this study, the concentrations of major anthropogenic volatile organic compounds(VOCs) which include benzene, toluene, m, p-xylene, o-xylene, and ethylbenzene were measured at the Nan-ji-do landfill site during the spring and fall season of 2000. the temporal distribution characteristics of these VOCs were investigated over varying time scale. According to our study, the mean concentration of those species were computed to be 1.65$\pm$2.68(benzene), 9.62$\pm$9.32(toluene), 1.84$\pm$2.90(m, p-xylene), 0.83$\pm$1.43(o-xylene), and 1.17$\pm$1.21 ppb(ethylbenzene). The VOCs levels in the study area are not distinctively higher than the level typically found in urban area that can be subject to the influence of various anthropogenic source processes. Inspection of their temporal trends exhibited various patterns for the diurnal(and seasonal) cycle. Although each species showed distinctive patterns in temporal distribution trends, we were able to find the strong correlations among most concurrently measured VOCs except for benzene.

• Journal of the korean society of oceanography
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• v.37 no.3
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• pp.178-186
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• 2002

The mud deposit located to the south of Cheju Island, the East China Sea, is characterized by an upwelling system or, on occasions, a combined upwelling-downwelling system. The water mass here is associated with relatively high suspended matter concentrations. In the present study, a vertical I-D model is used to undertake numerical experiments for evaluating the upwelling and downwelling effects on the suspended particulate matter distribution patterns within the water column. The results show that: (1) because the upwelling or downwelling velocity tends to be of the same order of magnitude as the settling velocity of suspended particles, a number of different patterns of suspended matter concentration distribution are possible, depending on the relative importance of the velocities; (2) the presence of upwelling can enhance the suspended particulate matter concentration; and (3) in an upwelling-downwelling system, maximum concentrations may or may not lie in the middle of the water column, depending on, once again, the interrelationships between the opwelling/downwelling velocities and the settling velocity. Hence, the physical processes associated with upwelling/downwelling appear to be relevant to the suspended material distribution over shelf mud areas.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.267-276
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• 2017

In any reactor physics analysis, the instantaneous power distribution in the core can be calculated when the actual bundle-wise burnup distribution is known. Considering the fact that CANDU (Canada Deuterium Uranium) utilizes on-power refueling to compensate for the reduction of reactivity due to fuel burnup, in the CANDU fuel management analysis, snapshots of power and burnup distributions can be obtained by simulating and tracking the reactor operation over an extended period using various tools such as the $^*SIMULATE$ module of the Reactor Fueling Simulation Program (RFSP) code. However, for some studies, such as an evaluation of a conceptual design of a next-generation CANDU reactor, the preferred approach to obtain a snapshot of the power distribution in the core is based on the patterned-channel-age model implemented in the $^*INSTANTAN$ module of the RFSP code. The objective of this approach is to obtain a representative snapshot of core conditions quickly. At present, such patterns could be generated by using a program called RANDIS, which is implemented within the $^*INSTANTAN$ module. In this work, we present an alternative approach to derive the patterned-channel-age model where a simulated-annealing-based algorithm is used to find such patterns, which produce reasonable power distributions.