• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.49-54
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• 2011

Now the world will regulate the CO2 emission due to environmental issues. For an alternative plan photovoltaic system is watched. So, photovoltaic system is trend of big city and it is mandatory for renovation of construction. Oil & gas filling station existed in city is suitable to found the photovoltaic system. But the general photovoltaic system in oil & gas filling station is difficult to found because it is classified into hazardous area. This paper evaluates intrinsic safety evaluation of solar cell for making basic data to found for the photovoltaic system on hazardous area. The intrinsic safety characteristic is evaluated by short-circuit ignition test using IEC type spark ignition test apparatus and temperature rising test. The result of short-circuit ignition test, propane-air mixture gas is exploded on condition that 4 solar cells(9[V], 90[mA]) are connected serially under insolation 800[W/$m^2$]. So, if a larger solar module will be used at oil & gas filling station than we were tested, it needs explosion proof. As the result of rising temperature test, the temperature rising due to short circuit is not so much, but when the temperature rises due to radiant heat, it demands careful consideration for environmental influence.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.348-354
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• 1996

This study was carried out to investigate factors influencing on the groundwater quality at controlled horticulture in Honam area in 1995. The deeper groundwater sampling, the lower concentrations of $NH_4-N$ and $NO_3-N$ were observed. There was no difference in concentrations of $SO_4\;^{2-}$ and $Na^+$ in the groundwater below 15m. Contents of $NH_4-N$, $NO_3-N$ and $PO_4\;^{3-}$ in groundwater were the highest at rice transplanting season(the late May) and that of $SO_4\;^{2-}$, $Na^+$ and $Cl^-$ were the highest at dry season(the mid-February). Continuous cultivation of horticultural crops showed higher concentration of $NH_4-N$, $NO_3-N$, $PO_4\;^{3-}$, $Na^+$ and $Cl^-$ in groundwater than rotational culture with rice. The longer cultivation years with horticultural crops, the higher concentrations of $NO_3-N$, $PO_4\;^{3-}$, $SO_4\;^{2-}$ and $Cl^-$ were shown, and constitutional ratio of $NO_3-N$ among the anions increased gradually. Nitrate-N level, exceeded 20mg/l, the critical level for agricultural usage, frequently at Yongjinmyeon Wanju and Janglockdong Kwangju, and $PO_4\;^{3-}$ levels were higher at Seogtandong Iksan than the other places.

• Journal of Fisheries and Marine Sciences Education
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• v.24 no.6
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• pp.920-933
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• 2012

Marine algal flora and community structure were investigated seasonally at four stations in Busan, in which coastal area and estuary affected by Nakdong river are involved, from February 2011 to October 2011. Total 78 species including 9 of cholophyta, 17 of phaeophyta and 52 of rhodophyta were found during the study period. Maximum and minimum species number were recorded at station 1(57 species) and at 3(32 species). As based on the cluster analysis, grouping pattern between the four stations was significantly affected by season and Nakdong river run off. At station 3 directly exposured on Nakdong river run off, species diversity was relatively low and dominant species were similar throughout four seasons. However, coverage at the station was relatively high because of Ulva bloom. This difference results from salinity and nitrates concentrations closely related with river runoff controlled according to precipitation. Marine algal coverage was high at lower salinity and higher nitrate concentration. In conclusion, the spatio-temporal distribution of benthic marine algae in estuary of Nakdong river was mainly determined by the precipitation and river run off with the seasons, whereas that in coastal area was seasonally affected by general physical, chemical, biological and dynamic factors.

• Journal of IKEEE
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• v.16 no.4
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• pp.316-321
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• 2012

In this paper, we study the energy-efficient deployment strategy for micro base station (BS) in wireless cellular systems. Firstly, we formulate a general problem pertaining to total energy consumption minimization with the requirement of area spectral efficiency (ASE). We start from an observation about the correlation between the area covered by an additional micro BS and the increment of ASE. Under such an observation, we propose an efficient greedy micro BS deployment algorithm. Simulations show that the proposed deployment algorithm can deploy micro BSs with a slight performance reduction comparing with the optimal solution.

• Korean Journal of Hydrosciences
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• v.5
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• pp.33-43
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• 1994

This study is to determine the critical duration of design rainfall and to utilize it for the design of detention pond with pump station. To examine the effect of the duration and temporal distribytion of the design rainfall, Huff's quartile method is used for the 9 cases of durations (ranges from 20 to 240 minutes) with ten years return period, and the ILLUDAS model is used for runoff analysis. The storage ratio, which is the ratio of maximum storage amounts to total runoff volume, is introduced to determine the criticalduration of design rainfall. The duration which maximizes the storage ratio is adopted as the critical duration. This study is applied to 18 urban drainage watercheds with pump station in Seoul, of which the range of watershed area is 0.24~12.70$km^2$. The result of simulation shows that the duration which maximizes storage ratio is 30 and 60 minutes on the whole. It is also shown that the storage ratios of 2nd - and 3rd-quartile pattern are larger than those of 1st- and 4th-quartile pattern of temporal distribution. A simplified empirical formula for Seoul area is suggested by the regression analysis between the maximum storage ratio and the peak ratio. This formula can be utilized for the preliminary design and planning of detention pond with pump station.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.68-70
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• 2021

The wind power generators installed in the Jeju area have already exceeded the supply in the Jeju area and are being thrown away. Accordingly, the government is conducting research on installing a 2MWh-class ESS(energy storage system) through a technology development project to charge wasted power and use it in an electric vehicle charging station. In this paper, in order to stably install a 2MWh class ESS, the electric vehicle charging model and ESS discharge model were modeled and simulated using Matlab Simulink. Through simulation, it was verified that the 2MWh class ESS operates stably in various scenarios.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.68-69
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• 2014

At the present, ship traffic monitoring and management are focused on the harbor area and the specified coastal zone in South Korea. It, however, is required that the Jurisdictional Sea Area of South Korea is monitored from two viewpoints: Safety and Security. Through a safe sea line (transport route) over the world, it is possible to expand our ocean economical territory. As a first step, we have been in field campaigns for integrated ship monitoring on the Ieodo Ocean Research Station in November 2013 after the first test in Gyunggi Bay.

• Land and Housing Review
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• v.2 no.3
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• pp.217-226
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• 2011

The Seoul Metropolitan Government is striving to minimize the amount of traffic according to the supply of apartment houses along with the solution of housing shortage for the low income people through high density development near the subway area. Therefore, a stronger policy is necessary to control the traffic of the passenger cars in a subway area for the successful high density development focusing on public transportation, and especially, the estimation of the demand of cars with high reliability is necessary to control the demand of parking such as the limited supply of parking lot. Accordingly, this study developed car ownership forecasting model using Look-up Table among category analyses which are easy to be applied and have high reliability. The estimation method using Look-up-Table is possible to be applied to both measurable and immeasurable types, easy to accumulate data, and features the flexible responding depending on the changes of conditions. This study established Look-up-Table model through the survey of geographical location, the scale of housing, the accessible distance to a subway station and to a bus station, the number of bus routes, and the number of car owned with data regarding 242 blocks in Seoul City as subjects.

• 전기의세계
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• v.26 no.2
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• pp.99-103
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• 1977

The object of this work is to study an optimal design problem of the proportional load-frequency controller for the single-control area power system. The selfservice power station is still a popular means as a power supplying source on ships or in a certain manufacturing area. The power system of this kind can be formulated as a single control-area system and it attracts a certain academic interest in controlling the system frequency under disturbances. In this paper, the single control-area system is mathematically formulated as a linear, time-invariant system in state-space under certain assumptions. The optimal proportional control law and the realization of the controller in closed loop-version is studied so that the final system designed can attain the system frequency to the nominal stationing value after the small load-disturbance. As in general cases of optimal design problems, the performance index is assumed to be quadratic in states and the control effort, and the infinite time control process is assumed in this work. The final control system realized depicts certain improvements in case study; in stability, transient responses and in steady-state frequency deviation, even though the steady state error did not attain the zero value.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.E
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• pp.55-64
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• 1999

The CIT(California Institute of Technology) three-dimensional Eulerian photochemical model was applied to the Greater Seoul Area, Korea for July 24, 1994, a day of the 9-day ozone episode to understand the characteristics of photochemical air pollution problems in the area. The modeling domain was 60km$\times$60km with the girl size of 2km$\times$2km. As the base case emissions, air pollutant emission data of the National Institute of Environmental Research, Korea for the year of 1991 were used with modifications based on EKMA(Empirical Kinetic Modeling Approach) resutls. Comparisons between predicted and observed concentrations showed that the model predicted the peak concentration over the domain reasonably. It was found that the location of the peak ozone concentration was mainly decided by metorological conditions. But the model could not resolve the spatial variations of concentration station by station, which was mainly caused by localized variations in emission and meteorology.