• Land and Housing Review
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• v.8 no.4
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• pp.249-256
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• 2017

Urbanization can be remarkable affected flood, pollutant loading, ecological system, and green infrastructure by distortion of hydrologic cycle. In order to mitigate these problems in urban, Low Impact Development(LID) technique has been introduced and applied in the world. SWMM model was calibrated with sets of field monitoring data and applied for calculation of runoff and pollutant loading in Asan-tangjung LID city under 2016 rainfall. Runoff reduction of watershed and catchment basins were showed efficiency 12.2% and 62.0%, respectively. Reduction of COD and TP loading also high efficiency in catchment basins were evaluated 74.9 and 71.4%. The results of this study can be used effectively in decision making processes of urban development project by comparing watershed runoff and pollutant reduction by designs of sort of LID technique, LID volume and location.

• Conservation Science in Museum
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• v.22
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• pp.15-26
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• 2019

This study was focused on the three-dimensional convergence modeling that can multilaterally analyze internal and external shapes of the Sam-Chongtong Hand Canon by optical precision scanning optimized for acquiring the surface shape and X-ray CT scanning used for obtaining the internal shape. First, the scanning results were converted by compatible extension, after which three-dimensional deviation analysis was conducted to verify mutual conformities. Accordingly, most (56.98%) deviations between the two scanning models was found be ±0.1mm. This result did not influence registration and merging based on the ICP algorithm. The merged data exhibited the external surface color, detailed shapes, internal width, and structure of the hand canon. The three-dimensional model based on optical surface scanning and X-ray CT scanning can be used for traditional technique interpretation as well as digital documentation of cultural heritage. In the future, it will contribute to deliver accessible scientific information of exhibits for visitors.

• Membrane Journal
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• v.24 no.1
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• pp.31-38
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• 2014

Rainwater harvesting is a process by which rainwater collected from rooftop or other catchment is purified so that the water can be directly or indirectly used by human beings for beneficial uses. As rainwater is increasingly considered for high quality purposes, membranes have gained an important place in rainwater treatment. It has advantages such as the production of high quality water, small footprint, and affordable energy consumption. Nevertheless, membrane fouling is regarded as a serious problem similar to the cases of water treatment and wastewater reclamation. In this study, we applied microfiltration (MF) membranes for rainwater treatment. In addition, a low pressure ultraviolet (UV) process was also use as a pretreatment to control notonly. To quantify the effect of UV on organic matters, both total organic carbon (TOC) and UV absorbance (UVA) were measured. Moreover, the effect of UV pretreatment on membrane fouling was investigated. Experimental results indicated that the pretreatment of membranes using LPUV was effective to control fouling of MF membranes only when the rainwater was contaminated by algae. This was attributed the reduction and modification of organics after UV treatments. It is likely that the UV/MF process is a promising option for water treatment in decentralized water treatment such as micro water grid systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12A
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• pp.1922-1931
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• 1999

A multicast traffic’s feature is the function of providing a point to multipoints cell transmission, which is emerging from the main function of ATM switch. However, when a conventional point-to-point switch executes a multicast function, the excess load is occurred because unicast cell as well as multicast cell passed the copy network. Additionally, due to the excess load, multicast cells collide with other cells in a switch. Thus a deadlock that losses cells raises, extremely diminishes the performance of switch. An input queued switch also has a defect of the HOL (Head of Line) blocking that less lessens the performance of the switch. In the proposed multicast switch, we use shared memory switch to reduce HOL blocking and deadlock. In order to decrease switch’s complexity and cell's processing time, to improve a throughput, we utilize the method that routes a cell on a separated paths by traffic pattern and the scheduling algorithm that processes a maximum 2N cell at once in the control part. Besides, when cells is congested at an output port, a cell loss probability increases. Thus we use the Output Memory (OM) to reduce the cell loss probability. And we make use of the method that stores the assigned memory (UM, MM) with a cell by a traffic pattern and clears the cell of the Output memory after a fixed saving time to improve the memory utilization rate. The performance of the proposed switch is executed and compared with the conventional policy under the burst traffic condition through both the analysis based on Markov chain and simulation.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.176-187
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• 1993

Based on the analysis of ecomorphological characters for 84 tree and shrub species, climax indices were estimated so as to interpret the position of the successional sere for the species in the natural deciduous forest. Nineteen ecomorphological characters, considered to be associated with successional gradient in the forest, were selected for the study. One of 2 to 4 steps per character for each species was given on a standardized scale of increasing climaxness, and the index was computed by percent of the sum of the scoring values for total score. Calculated mean value of 54.2 for all indices. Carpinus laxiflora had the highest index value of 83.3, and Populus davidiana recorded the lowest of 18.8. The most climax group, greater than 70 of the index, contained only 9 species, intermediate group, between 40 to 70 of the index, had 58 species, and the most pioneer group, less than 40 of the index comprised 17 species. The result has noticed that the large number of species would take advantage of most diverse resource and niche in the intermediate stage of the sere in the forest. The three components, i.e., light absorption, reproduction, and wood quality were used as axes for a 3-dimensional projection of the relative position for 44 species by principal component analysis. Along the similar ecomorphological characters, four recognized species group were classified by cluster analysis. The distribution pattern of plant families on the index gradient showed that the Betulaceae and Aceraceae had the widest seral amplitude, and the Salicaceae was a family typified as pioneer. There were no families specializing entirely with climax niche.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.10
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• pp.1021-1027
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• 2008

In this study, biofilm process was introduced for treating nonpoint source pollutants. The ceramic media were provided for biofilm growth in the reactors. The packing ratio of ceramic media was 5% and 15(v/v)%, respectively. Thereafter, the reactors were operated intermittently with the different interevent periods such as 0, 5, 10 and 15 days, respectively. The removal efficiencies of COD and NH$_4{^+}$-N were investigated at the different operating conditions such as media packing ratio, temperature, and interevent period. Additionally, Polymerase chain reaction(PCR)-denaturing gel gradient electrophoresis(DGGE) and INT-dehydrogenase activity(DHA) test were conducted to observe the microbial community and activity in the biofilm. Consequently, the interevent period seemed to have no significant influence on the COD removal efficiency. COD was removed within 6$\sim$8 hours at 25$^{\circ}C$ and about 15 hours at 10$^{\circ}C$. DGGE profiles showed that the initial species of microorganisms were changed from seeded activated sludge into the microorganisms detected in sediments. INT-DHA test also showed that the activities of microorgnaisms were not decreased even in the 15 days of interevent period.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.9
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• pp.643-653
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• 2013

In this study, trend analysis was performed by various runoff analysis method of Non-point Pollution Source(NPS) at the impervious area. The characteristics of rainfall at impervious area appeared to be influenced by rainfall strength and it appeared that first flush phenomenon occurs often if rainfall strength acts largely. It is judged that the measure is required to be prepared against that now that concentration difference of non-point pollution source appeared to be big by precedent number of days of no rainfall. As the result of calculating Decrease Rate (DR) by first flush of non-point pollution source, it is judged that it is important to prepare the measure against the pollutants about initial rain and it is necessary to calculate the capacity of non-point pollution source processing facilities regarding that now that the non-point pollution source integrated at impervious area showed the characteristics that are flowed out in high concentration by initial rain in case of non-rainfall considering the characteristics of non-point pollution source at impervious area. When taking 50% of non-point pollution source as the standard for decrease rate that was evaluated previously, it appeared as 15~60 min in case of TSS and it appeared as 30~90 min in case of organic compound, but the characteristic whose decrease rate is below 50% also appeared even till rainfall-runoff ends. Based on that, it is judged that it could be used as the reference when designing the structural BMPs facilities later.

• Journal of the Korean Society for Nondestructive Testing
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• v.16 no.3
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• pp.162-173
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• 1996

Dry magnetic particle inspection(MPI) was performed to detect the surface defects of steel ingot cast billets. Magnetic properties of several materials were characterized by the measurement of the B-H hysteresis curve. The inspection results were evaluated in terms of the magnetizing current, temperature, and the amount of magnetic particles applied to billets. Magnetic flux leakage near the defect site of interest was measured and compared with the results of calculation by the finite element method in the case of direct magnetizing current. Direct and alternating magnetizing currents for materials were deduced by the comparison of the inspections. Results of the magnetic particle inspection by direct magnetizing current were compared with those of finite element method calculations, which were verified by measuring magnetic leakage flux above the surface and the surface defects of the material. For square rods, due to the geometrical effect, the magnetic flux density at the edges along the length of the rods was about 30% of that at the center of rod face for a sufficiently large direct magnetizing current, while it was about 70% for an alternating magnetizing current. Thus, an alternating magnetizing current generates rather uniform magnetic flux density over the rods, except for the region on the face across about 10 mm from the edge. The attraction of the magnetic particle by the magnetic leakage field was nearly independent of the surface temperature of the billets up to $150^{\circ}C$. However, the temperature should have been limited below $60^{\circ}C$ for an effective fixing of gathered magnetic particles to the billet surface using methylene chloride. We also found that the amount of applied magnetic particles tremendously affected the detection capability.

• Fire Science and Engineering
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• v.31 no.2
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• pp.52-60
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• 2017

Numerical simulations were performed to evaluate the habitability of an operator for a cabinet fire in the main control room of a nuclear power plant presented in NUREG-1934. To this end, a Fire Dynamics Simulator (FDS), as a representative fire model, was used. As the criteria for determining the habitability of operator, toxic products, such as CO, were also considered, as well as radiative heat flux, upper layer temperature, smoke layer height, and optical density of smoke. As a result, the probabilities of exceeding the criteria for habitability were evaluated through the sensitivity analysis of the major input parameters and the uncertainty analysis of fire model for various fire scenarios, based on V&V (Verification and Validation). Sensitivity analyses of the maximum heat release rate, CO and soot yields, showed that the habitable time and the limit criterion, which determined the habitability, could be changed. The present methodology will be a realistic alternative to enhancing the reliability for a habitability evaluation in the main control room using uncertain information of cabinet fires.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.3
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• pp.317-328
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• 2010

This paper describes the results of complete Bouguer anomalies computed from the Free-air anomalies that derived from Sandwell and DNSC08 marine gravity models. Complete bouguer corrections consist of three parts: the bouguer correction (Bullard A), the curvature correction (Bullard B) and the terrain correction (Bullard C). These all corrections have been computed over the East Sea on a $1'{\times}1'$elevation data (topography and bathymetry) derived from ETOPO1 global relief model. In addition, a constant topographic (sea-water) density of $2,670kg/m^3$($1,030kg/m^3$) has been used for all correction terms. The distribution of complete bouguer anomalies computed from DNSC08 are -34.390 ~ 267.925 mGal, and those from Sandwell are -32.446 ~ 266.967 mGal in East Sea. The mean and RMSE value of the difference between DNSC08 and Sandwell is $0.036{\pm}2.373\;mGal$. The highest value of complete bouguer anomaly are found around the region of $42{\sim}43^{\circ}N$ and $137{\sim}139^{\circ}E$ (has the lowest bathymetry) in both models. These values show that the gravity distribution of both models, DNSC08 and Sandwell, are very similar. They indicate that satellite-based marine gravity model can be effectively used to analyze the geophysical, geological and geodetic characteristics in East Sea.