• Title/Summary/Keyword: Simulation operation

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Interpretation of Simultaneous Nitrification & Denitrification Reaction by Modifying Activated Sludge Models(ASMs) (활성슬러지 모델 수정을 통한 동시 질산화.탈질 반응 해석)

  • Kim, Hyo-Su;Kim, Ye-Jin;Lee, Sung-Hak;Moon, Tae-Sup;Choi, Jae-Hoon;Kim, Chang-Won
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.2
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    • pp.199-206
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    • 2008
  • Simultaneous nitrification and denitrification means that nitrification and denitrification occur concurrently in the same reaction vessel under low DO concentration. Some mathematical models developed to simulate simultaneous nitrification and denitrification reaction, but they have the complex model structures or have limitations of model application. To solve these problems, if possible that predict the behavior of simultaneous nitrification and denitrification reaction by activated sludge model, structures of the model is less complex than previous models and applies the various operation conditions. But original activated sludge models have difficulties in representing the denitrification reaction under aerobic condition. So the aim of this study is to interpret simultaneous nitrification and denitrification reaction by modifying activated sludge model. Original activated sludge model No.1(ASM1) was selected and modified. The simulation result in modified ASM1 predicted appropriately for the measured data. This indicates the structures of ASM1 are properly improved for interpretation of simultaneous nitrification and denitrification reaction.

Design and Implementation of Single-Feed Dual-Band Circular Polarization Triangular Antenna for Reception of GPS and DMB Signals (GPS와 DMB 신호 수신을 위한 단일 급전 이중 대역 원형 편파 삼각 패치 안테나 설계 및 구현)

  • Lee, Won-Kew;Kim, Sung-Min;Yang, Woon-Gen
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.9 s.100
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    • pp.893-902
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    • 2005
  • We propose a novel single-feed triangular patch antenna with bar-type slots for dual-band circular polarization operation. And also propose a H-type slotted triangular patch antenna to enhance the ratio of the resonance frequencies. 3 cases of desist examples with bar-type slots were investigated and also 4 cases of H-slotted antennas were investigated to meet the dual-band requirement for GPS(Global Positioning System) and DMB(Digital Multimedia Broadcasting). One suitable design example was implemented and measured. Simulation results of the design example for GPS and DMB system show that axial ratio and maximum gain are 3.80 dB, 8.85 dBi for low-band at 1.575 GHz and 2.02 dB, 8.60 dBi for high-band at 2.642 GHz, respectively. Measured results of the implemented antenna show that $S_{11}$ is -12.43 dB for low-band at 1.575 GHz and less than -18.75 dB for high-band, respectively.

3-Phase Power Quality Disturbance Generator with Phase Jump Function (위상급변 기능을 갖는 3상 전력품질 외란발생기)

  • Lee, B.C.;Choi, S.H.;Paeng, S.H.;Park, S.D.;Choi, N.S.;Kim, I.D.;Chun, T.W.;Kim, H.G.;Nho, E.C.
    • The Transactions of the Korean Institute of Power Electronics
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    • v.11 no.5
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    • pp.463-470
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    • 2006
  • This paper deals with a new 3-phase power quality disturbance generator. The proposed generator can provide phase jump as well as voltage sag, swell, outage, unbalance, and over and under voltage. The operating principle of the generator is described in each mode of disturbance. The magnitude of the phase jump is analysed and it is found that the magnitude is the function of the turn-ratios of the transformers consisting the generator. The scheme has simple structure compared with the conventional one, and the major components of the proposed scheme are SCR thyristor and transformer, which guarantees high reliability and cost-effective implementation of the generator. Furthermore, high efficiency can be obtained because there is no PWM switching of the semiconductor devices, and it is easy to control the system. Simulations are carried out to confirm the operation in each disturbance mode, and experiments has been done with 5kVA power rating. The usefulness of the proposed scheme is verified through simulation and experimental results. It is expected that the scheme can be applied to the performance test of the custom power devices such as UPS, DVR, DSTATCOM, and SSTS with cost-effective system.

Numerical Simulation of The Pressure-Flow Control Characteristics of Shunt Valves Used to Treat Patients with Hydrocephalus (수두층 치료용 션트밸브의 압력-유량 제어특성 수치해석)

  • 장종윤;이종선;서창민
    • Journal of Biomedical Engineering Research
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    • v.22 no.5
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    • pp.403-412
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    • 2001
  • The Present study analyzed the pressure-flow characteristics of a Korean shunt valve. Changes in the characteristic currie depending on the design parameters were also investigated. The Korean shunt valve used in the present study was constant pressure type and our analyses were validated through experiments. We applied fluid-structure interaction to solve the flow dynamic Problem because the small diaphragm in the valve was made from flexible silicone elastomers. Considering the material nonlinearity of the hyper-elastic material. the Mooney-Rivlin approximation was employed. The results of the numerical analyses were close to the experimental results The major Pressure drop was observed to happen in the small diaphragm. The slope of the pressure-flow characteristic curve was computed to be 0.37mm$H_2O$.hr/cc, which was similar to the average value of commercial shunt valves. 0.40mm$H_2O$.hr/cc. Therefore. our valves analyzed in the Present study showed a Proper Pressure control characteristics of the constant pressure type shunt valves. The opening pressure could be controlled by adjusting the amount of predeflection of the valve diaphragm. In order to obtain opening pressures of 25mm$H_2O$ and 80mm$H_2O$, respectively, and the required predeflection was found to be 10.2$\mu$m and 35.3$\mu$m. The flow orifice size was found to be within 10$\mu$m during valve operation Therefore, Precision design and manufacturing techniques are necessary for successful operations of the shunt valve. The study indicated the amount of predeflection as well as the magnitude of corner rounding of the diaphragm edge are important design parameters to influence the slope of the pressure-flow characteristic curve.

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Seismic Techniques for the Integrated Assessment of Structural Integrity of Concrete Runway (콘크리트 활주로 건전도상태의 종합평가를 위한 비파괴 탄성파기법)

  • Joh Sung-Ho;Kang Tae-Ho;Cho Mi-Ra;Suh Young-Chan;Kwon Soo-Ahn
    • Journal of the Korean Geotechnical Society
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    • v.21 no.4
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    • pp.51-63
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    • 2005
  • Concrete pavement may suffer from material deterioration or structural problems, which lead to surface cracks and deflection of a concrete pavement. Degraded concrete pavement, when it is still under operation, should be recovered by an urgent maintenance to avoid the discontinued service leading to the significant traffic problems and economic loss. Seismic techniques are good tools to assess the structural integrity of concrete runway. It is because seismic techniques can evaluate engineering properties nondestructively and quickly and the evaluation can be extended to subgrade. In this study, a series of numerical simulations of stress-wave propagation were performed to verify feasibility of seismic techniques as an assessment tool. Based on the results of the numerical simulation, a framework of using seismic techniques was presented fur the nondestructive integrated assessment fur structural integrity of concrete runway. And the presented framework was applied to $\bigcirc\bigcirc$ concrete runway with surface cracks, which required urgent maintenance, to identify the causes of the surface cracks. The results obtained from the structural integrity assessment were compared with the measurements of the cores collected from the same runway for verification of the presented framework.

Signal Timing Calculation Model of Transit Signal Priority using Shockwave Theory (충격파 이론을 이용한 대중교통 우선신호의 신호시간 산정모형)

  • Park, Sang Sup;Cho, Hye Rim;Kim, Youngchan;Jeong, Youngje
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.35 no.4
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    • pp.897-905
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    • 2015
  • This research suggested the traffic signal calculation model of active transit signal priority using a shockwave model. Using this signal priority timing optimization model, the shockwave area is computed under the condition of Early Green and Green Extension among active transit signal priority techniques. This study suggested the speed estimation method of backward shockwave using average travel time and intersection passing time. A shockwave area change is calculated according to signal timing change of transit signal priority. Moreover, this signal timing calculation model could determine the optimal signal priority timings to minimize intersection delay of general vehicles. A micro simulation analysis using VISSIM and its user application model ComInterface was applied. This study checked that this model could calculate the signal timings to minimize intersection delay considering saturation condition of traffic flow. In case studies using an isolated intersection, this study checked that this model could improve general vehicle delay of more over ten percentage as compared with equality reduction strategy of non-priority phases. Recently, transit priority facilities are spreading such as tram, BRT and median bus lane in Korea. This research has an important significance in that the proposed priority model is a new methodology that improve operation efficiency of signal intersection.

Study for the Homogeneity of Freeway Free-Flow Speed under the State of LOS-A Low Density (LOS A 저밀도 상태에서 고속도로 자유교통류 속도의 동질성에 관한 연구)

  • Yoon, Byoung Jo;Oh, Seung Hwoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.6D
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    • pp.779-784
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    • 2011
  • Freeway FFS (Free-Flow Speed) under the state of LOS (Level of Service) A has been regarded as a homogeneous state to all levels of traffic volume. The features of low-density FFS is served as the basic data for a decision on limited maximal speed, accident analysis, simulation modeling etc. A few researches for the macroscopic characteristics of design and operation speed have been reported, and any study for the microscopic features of freeway free-flow speed under the state of low density has not been done. Therefore, the characteristics of low-density FFS according to the level of traffic volume (1-3 veh/30 sec) and daily hour periods (0-5, 6-8, 9-11, 12-19, 20-23) is microscopically analyzed in this study with huge volume and speed data. It was found that speed distributions are changed and show different behaviors under the conditions of traffic volume levels and daily time periods. V85s (85th percentile speed) at early morning and night periods decrease when levels of traffic volume increase, whereas V85s at day time do not show considerable differences. Especially, FFSs of levels of traffic volume at early morning and night periods, despite low density, is analyzed as heterogeneity, but homogeneity at day time.

A Study on the Airflow Distribution in the Diagonal Ventilation Circuit for the Design of a High Level Radioactive Waste Repository (고준위 방사성 폐기물 처분장 설계를 위한 Diagonal 환기 회로 내 공기량 분배에 관한 연구)

  • Hwang, In-Phil;Choi, Heui-Joo;Roh, Jang-Hoon;Kim, Jin
    • Tunnel and Underground Space
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    • v.22 no.3
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    • pp.173-180
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    • 2012
  • In this study, diagonal ventilation circuits that are advantageous in air flow direction control were studied. Based on the results of the study, it could be seen that air volumes in diagonal ventilation circuits could also be calculated using numerical formulas or programs if the air volumes and air flow directions to be infused into diagonal branches are determined in advance as with other serial/parallel circuits. To apply the results, design plans for high level radioactive waste repositories applied with diagonal ventilation circuits and parallel ventilation circuits. To compared the each design plans and obtain expected operation results, ventilation network simulations were conducted through the Ventsim program which is a ventilation networking program. Based on the results, in the case of diagonal repositories that was expected to cause great increases in resistance, fan pressure was 1570 pa, total flux was 84 $m^3/s$, fan efficiency was 76.4%, fan power consumption was 181.2 kW and annual fan operating costs were 178,710,838 and thus maximum around 8% differences were shown in pressure and flux values and a difference of around 1.5% was shown in terms of operating costs.

Analysis of Payload Technical Specifications for Efficient Agriculture and Forestry Satellite Observation (효율적인 농림업 위성관측을 위한 탑재체 기술사양 분석)

  • Kim, Bum-Seung;Lee, Kyung-Do;Hong, Suk-Young;Lee, Woo-Kyung
    • Korean Journal of Remote Sensing
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    • v.32 no.3
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    • pp.287-305
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    • 2016
  • Over the past half century, satellites have continuously expanded their roles in remote sensing applications. As the number of satellites to be launched are expected to continuously increase in coming years, the research on satellite payloads will be in high demands. Earth Observation (EO) satellites are nowadays widely utilized for various purposes. Especially, Agriculture and forestry applications are considered as their major application areas. Since about 85% of domestic land cover is classified as forest or cropland areas, it would be reasonable to suggest that the demand for these satellites should be of high priority. In this paper, a comprehensive analysis is performed on the technical specifications of satellite payloads that may be applicable to agricultural applications. We attempted to build a solid database on payload specifications by collecting relevant information available from various related institutes and academic research works. A number of experts involved in national agricultural research and satellite development programs have been invited to investigate required payload design. Based on the current technology development status and future plan, multiple options for future satellite payload designs have been suggested bearing in mind that the results may be applicable to the future agriculture and forestry satellite payload design. The proposed payload specifications are analyzed in depth through satellite operation simulations under the mission of observing the national agriculture areas. The proposed design scheme and simulation results may be used as technical references to satellite payload design for future space missions.

Simulation of Operation Effects of Stormwater Retention Facility (우수저류시설의 운영효과 모의)

  • Lee, Kil-Seong;Chung, Eun-Sung;Shin, Mun-Joo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2006.05a
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    • pp.809-813
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    • 2006
  • 현재 대도시 인근지역의 농업용 저수지는 도시화로 인해 농경지가 많이 줄어들어 존재의의를 잃어가고 있으며 관리주체 또한 운영과 관리를 적극적으로 하지 않고 있다. 하지만 이러한 저수지를 효과적으로 운영할 경우 도시화로 인한 건기의 유지용수 부족을 해결하는데 유용하게 활용할 수 있다. 본 연구에서는 안양천 중상류 유역에 대해 SWAT 모형을 이용하여 우수저류시설에 대한 운영효과를 분석하였다. 현존하는 오전 $(57,000m^3)$, 백운$(160,000m^3)$, 삼성$(40,000m^3)$ 저수지에 대해 존재하지 않을 경우와 존재할 경우의 유황곡선을 비교하여 저류시설로 인한 수문현황의 변화를 제시하였다. 오전저수지의 경우 오전천 하류 기준으로 갈수량이 0.00002 CMS에서 0.00052 CMS로, 저수량은 0.00369 CMS에서 0.00419 CMS로 증가하였으며, 백운저수지의 경우 학의천 하류기준으로 갈수량이 0.057 CMS에서 0.060 CMS로, 저수량은 0.102 CMS에서 0.105 CMS로 증가하였으며, 삼성저수지의 경우 삼성천 하류기준으로 갈수량이 0 CMS에서 0.001 CMS로, 저수량은 0 CMS에서 0.003 CMS로 증가하였다. 또한 각각의 저수지에 대해 건기의 유지용수를 위해 일정량 방류를 할 경우 어떻게 변화하는지 비교하였다. 운영을 개선할 경우 오전 저수지의 경우 갈수량이 0.00052 CMS에서 0.01002 CMS, 백운저수지의 경우 0.060 CMS에서 0.160 CMS, 삼성저수지의 경우 0.001 CMS에서 0.007 CMS로 증가하였다. 따라서 하천의 유지유량 확보를 위해 저수지를 신설하거나 기존 농업용 저수지의 저수용량 확장 및 수문설치 등 재개발을 할 경우 유역의 갈수 시 물순환이 보다 향상될 것이다.>에서 $0.0190m^3/s$로, 갈수량$(Q_{355})$$0.0176m^3/s$에서 $0.0189m^3/s$로 약 7%가 증가하는 것으로 분석되었다. 결과로부터 침투 트렌치는 저수량 및 갈수량을 증가시키는 보조수단이 될 수 있다.해 보았다. 뿐만 아니라 이와 관련된 수문요소기술을 확보할 수 있을 것이다.역의 물순환 과정을 보다 명확히 규명하고자 노력하였다.으로 추정되었다.면으로의 월류량을 산정하고 유입된 지표유량에 대해서 배수시스템에서의 흐름해석을 수행하였다. 그리고, 침수해석을 위해서는 2차원 침수해석을 위한 DEM기반 침수해석모형을 개발하였고, 건물의 영향을 고려할 수 있도록 구성하였다. 본 연구결과 지표류 유출 해석의 물리적 특성을 잘 반영하며, 도시지역의 복잡한 배수시스템 해석모형과 지표범람 모형을 통합한 모형 개발로 인해 더욱 정교한 도시지역에서의 홍수 범람 해석을 실시할 수 있을 것으로 판단된다. 본 모형의 개발로 침수상황의 시간별 진행과정을 분석함으로써 도시홍수에 대한 침수위험 지점 파악 및 주민대피지도 구축 등에 활용될 수 있을 것으로 판단된다. 있을 것으로 판단되었다.4일간의 기상변화가 자발성 기흉 발생에 영향을 미친다고 추론할 수 있었다. 향후 본 연구에서 추론된 기상변화와 기흉 발생과의 인과관계를 확인하고 좀 더 구체화하기 위한 연구가 필요할 것이다.게 이루어질 수 있을 것으로 기대된다.는 초과수익률이 상승하지만, 이후로는 감소하므로, 반전거래전략을 활용하는 경우 주식투자기간은 24개월이하의 중단기가 적합함을 발견하였다. 이상의 행태적 측면과 투자성과측면의 실증결과를 통하여 한국주식시장에 있어서 시장수익률을 평균적으로 초과할 수 있는 거래전략은 존재하므로 이러한 전략을 개발 및 활용할 수 있으며, 특히, 한국주식시

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