• Title/Summary/Keyword: Dominant discharge

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Management for Improvement in Water Quality and Change of Fish Assemblage in Urban Dong Stream with Input of Seawater (해수 투입에 따른 동천 주변 환경 개선 평가를 위한 어류상 변화 및 관리 방안)

  • Kwak, Seok-Nam;Kim, Dong-Myung;Chung, Yong-Hyun
    • Journal of Fisheries and Marine Sciences Education
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    • v.27 no.1
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    • pp.253-261
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    • 2015
  • The chemical water quality and fish assemblage of Dong Stream to assessment of environmental improvement after discharge seawater were investigated from July to December 2013. BOD and DO were significantly different between before and after discharge seawater, while pH and SS did not significant. A total of 11 fish species, 218 individuals and 10,525.1g were collected. Dominant fish species were Mugil cephalus, Konosirus punctatus, Acanthogobius flavimanus and Leiognathus nuchalis which account for 77.5% of total individuals collected, and they were estuarian species. Peak number of species and individuals, and biomass occurred in September, whereas diversity index were highest in November. The water ecosystem of Dong Stream have been changed estuarian environment. As a result of stream assessment on water quality and ecosystem, water quality have been improved as 'III' grade. These results suggested that stream restoration policies such as drain pipes maintenance, management of pollution sources and riverbed dredging to improve environment and recover habitate of Dong Stream were need for set up and establishment of regular monitoring system.

Characteristics of Hydraulic Head Variation at Multi-packer Wells in a Coastal Area (해안지역 다중패커공에서의 수리수두 변화 특성)

  • Cheong, Jae-Yeol;Hamm, Se-Yeong;Ok, Soon-Il
    • The Journal of Engineering Geology
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    • v.25 no.2
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    • pp.291-298
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    • 2015
  • For hydrogeological studies, it is of importance to observe hydraulic head in order to interpret groundwater flow, characterize aquifers, and calibrate groundwater flow model. This study analyzed the zonal variation of hydraulic heads at the eight monitoring wells (GM-1~GM-8) installed with multi-packers in a coastal area and verified vertical and lateral trends of the hydraulic gradients. Hydraulic heads were expressed as the depth of water because the monitoring wells have different depths. The hydraulic gradient at the nearest well (GM-5) shows 0.0142 with increasing trend of hydraulic gradient along depth. This fact indicates typical phenomenon of the discharge area. On the other hand, GM-1 and GM-2 wells in coastal area demonstrate constant hydraulic gradient down to the depth of 100 meters while at the zone of deeper than 100 m the hydraulic gradients illustrate 0.0196 and 0.0735, respectively. This indicates that horizontal flow is dominant at shallower zone than 100 m whereas upward flow is dominant at the zone deeper than 100 m. GM-3 well located farther than the other wells from the coast shows a small hydraulic gradient of 0.0046 that evidences a prevalent horizontal flow between the recharge area and the discharge area.

Roles of Wind Stress Variations in the Western North Pacific on the Decadal Change of ENSO (ENSO 십년 변동에 미치는 북서태평양 지역에서의 바람 응력 변동의 역할)

  • Lee, Yoon-Kyoung;Moon, Byung-Kwon;Kwon, Min-Ho;Jhun, Jong-Ghap
    • Journal of the Korean earth science society
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    • v.27 no.6
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    • pp.687-694
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    • 2006
  • This paper investigated the effects of wind stress forcing in the western North Pacific on ENSO decadal change before and after the late 1970s. The SVD analysis of SODA data shows that a positive wind stress curl is dominant in the western North Pacific at the ENSO mature phase, which leads to the ENSO phase change by discharge/recharge heat contents in the equatorial Pacific. Before the late 1970s, the wind stress curl in the western North Pacific was strong. This strong wind forcing that is associated with the fast discharge of heat contents in the equator led to the short period and the weak intensity of ENSO occurred during the 1960-1970. On the other hand, after the late 1970s the relatively weak wind stress curl was accompanied with the long period and the strong intensity of ENSO. The simple coupled model experiments also confirm that the amplitude and dominant period of ENSO decrease when the wind stress curl in the western North Pacific projects more strongly into the ocean at the TNSO mature phase. Our results support that the changes in the behavior of ENSO after the late 1970s are associated with the wind stress variation in the western North Pacific.

Environmental Studies in the Lower Part of the Han River -VII. Long Term Variations and Prospect of the Phytoplankton Community- (한강하류의 환경학적 연구 -VII. 식물플랑크톤군집의 장기간 변화와 전망-)

  • Lee, Jin-Hwan;Jung, Seung-Won
    • ALGAE
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    • v.19 no.4
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    • pp.321-327
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    • 2004
  • The literature review on the dynamics of the phytoplankton communities in terms of species composition, standing crops, abundant species and dominant species in the lower part of the Han River from 1940s to 2000s was conducted for the prospective prediction of their succession patterns. Total of 326 taxa were identified and they belonged to 47 blue-green algae, 139 green algae, 12 euglenoids, 126 diatoms, 6 din flagellates and 2 silicoflagellates. Composition of phytoplankton communities were 83.6% diatoms, 10.5% blue-green algae and 5.3% green algae in the middle of 1960s, whereas those were 43.2% diatoms, 40.7% green algae and 13.6% blue-green algae in the 1990s. Before 1990s, Synedra ulna, Melosira varians, Cymbella tumida, Synedra acus, Cymbella ventricosa, Navicula cryptocephala, Nitzschia palea, Aulacoseira granulata, Gomphonema parvulum and Cymbella affinis were most frequent, while those after 1990 were Asterionella formosa, Asterionella gracillima, Aulacoseira granulate, Aulacoseira granulata var. angustissima, Chlorella vulgare, Fragilaria crotonensis and Synedra ulna. Phytoplankton blooms were frequent from winter to the late spring and rare in summer due to heavy rain and discharge. Seasonal variations of the dominant species were fairly obvious; Asterionella gracillima and Aulacoseira granulata in spring, Aulacoseira granulate and Aulacoseira granulate var. angustissima in summer and autumn, Asterionella gracillima and Stephan discus hantzschii in winter. Recently blue-green algae, Microcystis, Aphanocapsa, Dactylococcopsis have been more abundant than those of the previous reports. Based on the current situations, Stephan discus hantzschii f. tennis, Asterionella gracillima, Aulacoseira granulate and blue-green algae will be more abundant and blooms of those species will be more frequent.

Simulation on the PCB Particle Trajectories in Corona-discharge Electrostatic Separator (코로나 방전 정전선별기 내 PCB 입자의 이동궤도 시뮬레이션)

  • Han, Seongsoo;Park, Seungsoo;Kim, Seongmin;Park, Jaikoo
    • Resources Recycling
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    • v.23 no.6
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    • pp.30-39
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    • 2014
  • The trajectories of PCB(Printed Circuit Board) particles in the corona discharge electrostatic separation was simulated. The PCB particles are prepared by crushing bare board, which disassembled from electronic components, consist mostly of copper and FR-4(Flame Retardant Level-4) Firstly, a model was established for calculating of detachment points of PCB particles from the rotating electrode in separator. The model of detachment points was derived from equilibrium of force such as gravity force, centrifugal force, electrostatic force. The trajectories of particles after detachment was calculated by acceleration derived from time-integrating method of motion equation. In this simulation, particle size, supplied voltage, rotation speed of rotating roll electrode and angle of induction electrode were adopted as variables. While the trajectories of FR-4 particles were affected by all variables, rotation speed of rotating roll electrode was dominant variables affecting trajectories of copper particles.

Thermo-hydraulic Modeling in Fault Zones (단층대에서의 열-수리적 거동 모델링)

  • Lee, Young-Min;Kim, Jong-Chan;Koo, Min-Ho;Keehm, Young-Seuk
    • Economic and Environmental Geology
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    • v.42 no.6
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    • pp.609-618
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    • 2009
  • High permeable faults are important geological structures for fluid flow, energy, and solute transport. Therefore, high permeable faults play an important role in the formation of hydrothermal fluid (or hot spring), high heat flow, and hydrothermal ore deposits. We conducted 2-D coupled thermal and hydraulic modeling to examine thermohydraulic behavior in fault zones with various permeabilities and geometric conditions. The results indicate discharge temperature in fault zones increases with increasing fault permeability. In addition, discharge temperature in fault zones is linearly correlated with Peclet number ($R^2=0.98$). If Peclet number is greater than 1, discharge temperature in fault zones can be higher than $32^{\circ}C$. In this case, convection is dominant against conduction for the heat transfer in fault zones.

The high repetition operating characteristics of pulsed Nd:YAG laser by parallel mesh and alternating charge-discharge system (병렬 메쉬 및 교번 충.방전 방식에 의한 펄스형 Nd:YAG 레이저의 고반복 동작특성에 관한 연구)

  • Park, K.R.;Kim, B.G.;Hong, J.H.;Kim, W.Y.;Kim, H.J.;Cho, J.S.
    • Proceedings of the KIEE Conference
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    • 1999.11d
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    • pp.1060-1062
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    • 1999
  • Pulsed Nd:YAG laser is used widely for materials processing and instrumentation. It is very important to control the laser energy density in materials processing by a pulsed Nd:YAG laser. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this study, the alternating charge-discharge system was designed to adjust a pulse repetition rate. And the parallel mesh is added to increase laser output power. This system is controlled by one chip microprocessor and allows to replace an expensive condenser for high frequency to a cheap condenser for low frequency. In addition, we have investigated the current pulse shape of flashlamp and the operating characteristics of a pulsed Nd:YAG laser. As a result, it is found that the laser output of the power supply using the parallel mesh and the alternating charge-discharge system is not less than that of typical power supply. As the pulse repetition rate rises from 10pps to 110pps by the step of 20pps at 1000V and 1200V, it is found that the laser efficiency decreases but the laser output power increases about 5W at each step.

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The high repetition operating characteristics of pulsed Nd:YAG laser by alternating charge-discharge system (펄스형 Nd:YAG 레이저의 교번 충.방전 방식에 의한 고반복 동작특성)

  • Kim, W.Y.;Park, K.R.;Kim, B.G.;Hong, J.H.;Kang, U.;Kim, H.J.
    • Proceedings of the KIEE Conference
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    • 1999.07e
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    • pp.2204-2206
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    • 1999
  • Pulsed Nd:YAC laser is used widely for materials processing and instrumentation. It is very important to control the laser energy density in materials processing by a pulsed Nd:YAG laser. A pulse repetition rate and a pulse width are regarded as the most dominant factors to control the energy density of laser beam. In this study, the alternating charge-discharge system was designed to adjust a pulse repetition rate. This system is controlled by one chip microprocessor and allows to replace an expensive condenser for high frequency to a cheap condenser for low frequency. In addition. we have investigated the current pulse shape of flashlamp and the operating characteristics of a pulsed Nd:YAG laser. As a result, it is found that the laser output of the power supply using the alternating charge-discharge system is not less than that of typical power supply. As the pulse repetition rate rises from 30pps to 120pps by the step of 30pps at 1200V, it is found that the laser efficiency decreases but the laser output power increases about 6W at each step.

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Hydrogeological Controls on the Discharge Rate of Choosan Spring in the Nari Basin of Ulleung Island, South Korea (울릉도 나리분지 추산용천수 수량의 수리지질학적 지배요소)

  • Byeongdae Lee;Min Han;Chung-Ryul Ryoo;Byong-Wook Cho
    • The Journal of Engineering Geology
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    • v.34 no.1
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    • pp.13-24
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    • 2024
  • The purpose of this study is to identify the geology, geologic structure, hydrogeology and geomorphic characteristics of the Nari Basin and establish the controls on the discharge of water 20,000~40,000 m3/day from the Choosan Yongchulso, Ulleung Island, South Korea. Pumice and lapilli tuffs showing well-developed stratification are the predominant rock types surrounding the spring. The spring shows a structure whereby discharge occurs along a lens-like erosion cave formed by differential erosion of strata comprising tuff or pumice tuff. The Choosan Yongchulso is located at the point where the planation surface of the Nari Basin' ends and steep slopes begin. The basin is bounded on all sides by these steep slopes, except in the north, where the Choosan Yongchulso is located. Given these geomorphic characteristics, the Choosan Yongchulso is regarded as the ultimate outlet of the basin catchment area.

A Study on the Predictive Diagnosis of the Cable Joint Using Ultrasonic Technique (초음파 측정기법을 사용한 케이블 접속부 예방진단 연구)

  • 곽희로;이동준;박동화
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.14 no.6
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    • pp.78-84
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    • 2000
  • In this paper, the diagnosis technique was proposed by measuring and analyzing ultrasonic signals caused by partial discharge on the interface of cable joint. The measured ultrasonic signal was filtered by wavelet transform, and then the dominant signal of filtered signal was analyzed by fast fourier transform(FFT). As a result, it was confirmed that different characteristics were obtained with the moisture and the metal powder on the interface of cable joint and with voltage increment.

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