• 농업과학연구
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• 제38권2호
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• pp.309-314
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• 2011

The purpose of this study is to select the dominant discharge which mostly affects the formation of the channel shape in Yo-Stream. So far, three different discharge conditions such as bankfull discharge, discharge of a specific recurrence interval, and effective discharge have been considered as an indicator of dominant discharge. Therefore, three different discharge conditions were studied and based on the study results, dominant discharge was selected for Yo-Stream. When comparing bankfull discharge and effective discharge at Beonam stream gaging station, it has turned out that effective discharge was 10 $m^3$/sec, which is 6 times greater than bankfull discharge of 58.83 $m^3$/sec. Furthermore, when comparing bankfull discharge and discharge of a specific recurrence interval, bankfull discharge was quite similar to discharge with recurrence interval of 1.52 years. Previous study results also indicate that dominant discharge occurs with recurrence interval of similar duration. Therefore, discharge of 58.83 $m^3$/sec was considered as a dominant discharge, which corresponds to discharge with recurrence interval of 1.52 years.

• Wind and Structures
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• 제16권1호
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• pp.47-60
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• 2013

A dominant opening in a windward wall, which generates large internal pressures in a building, is a critical structural design criterion. The internal pressure fluctuations are a function of the dominant opening area size, internal volume size and external pressure at the opening. In addition, many buildings have background leakage, which can attenuate internal pressure fluctuations. This study examines internal pressure in buildings for a range of dominant opening areas, internal volume sizes and background porosities. The effects of background porosity are incorporated into the governing equation. The ratio of the background leakage area $A_L$ to dominant opening area $A_W$ is presented in a non-dimensional format through a parameter, ${\phi}_6-A_L/A_W$. Background porosity was found to attenuate the internal pressure fluctuations when ${\phi}_6$ is larger than 0.2. The dominant opening discharge coefficient, ${\kappa}$ was estimated to lie between 0.05 to 0.40 and the effective background porosity discharge coefficient ${\kappa}^{\prime}_L$, was estimated to be between 0.05 to 0.50.

• 오토저널
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• 제11권5호
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• pp.55-64
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• 1989

The effect of discharge have been investigated for condition of spark in a multiple spark ignition engine, as the spark duration, capacitive and inductive discharge energy were calculated for condition of spark by ignition wave and energy formula. The useful portion of spark discharge is divided into capacitance portion and inductance portion. It was found that capacitive discharge energy and spark duration were increased according to increasing number of spark, and inductive discharge energy was increased according to increasing spark interval. Therefore engine torque was increase and lean misfire limit was extended comparing with the standard ignition system. It found that spark energy was discharged within ignition delay period availability acted on the formation and growth of flame kernel, and total spark energy was increased according to increasing number of spark times, but discharged spark energy after ignition delay became unavailable energy. And the capacitive discharge energy has the dominant effect for stoichiomeric or not very rich air-fuel mixture but inductive discharge energy has the dominant effect for lean air-fuel mixture.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1897-1899
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• 2000

This paper describes the frequency characteristics and the number of pulse of ultrasonic signals due to partial discharge occurred at each electrode. The defects which could occur in a transformer were simulated by using needle-plane electrode, IEC(b) electrode and void electrode. As a result, the dominant frequency of ultrasonic signals generated by corona in oil and partial discharge in void was hardly changed regardless with the applied voltage, but in case of surface discharge in oil, its dominant frequency moved to low frequency with the applied voltage. The increasing rate of pulse number per second was high in order of the surface discharge in oil, the partial discharge in void, the corona in oil.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.1571-1575
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• 2006

하도 형성 유량은 현재 하도의 형태와 특성을 결정하는 유량을 말하는 것으로 지배유량라고도 불린다. 지배유량과 동일한 개념에서 충적하천에서 장기간에 걸쳐 동일한 규모의 유량이 하도에 적용된다고 가정할 때, 현재의 하천과 같은 형상을 나타내게 만드는 유량이 하도 형성 유량이며, 이것은 크게 강턱유량과 유효유량의 개념으로 설명된다. 금회 연구에서는 국내에서 많이 이용되는 1.58년 빈도의 홍수량을 포함하여 각종 빈도의 홍수량을 결정하고, 이를 1차원 부등류 해석 프로그램에서 모의하여 수위 및 유량을 결정하였다. 하도 형성 유량 산정을 위해 이용된 홍수의 빈도는 1.01년, 1.58년, 2년, 2.33년, 5년이다. 각 빈도별 홍수량은 해당하천의 하천정비 기본계획에서 제시된 80년 빈도 홍수량과 무차원성장곡선을 이용하여 산정하였다. 오차분석 결과 조사된 전체 하천에서 1.01년 빈도의 홍수량이 강턱에 가장 근접하는 결과를 나타내었으며, 국내에서 관행적으로 이용하던 국내에서 관행적으로 이용되는 1.58년 빈도 홍수량은 강턱유량의 개념에서 하도 형성 유량에 접근할 때는 과대하게 평가되는 점을 확인할 수 있었다.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2006년도 학술발표회 논문집
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• pp.1107-1111
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• 2006

하도 형성 유량은 현재 하도의 형태와 특성을 결정하는 유량을 말하는 것으로 지배유량라고도 불린다. 지배유량과 동일한 개념에서 충적하천에서 장기간에 걸쳐 동일한 규모의 유량이 하도에 적용된다고 가정할 때, 현재의 하천과 같은 형상을 나타내게 만드는 유량이 하도 형성 유량이며, 이것은 크게 강턱유량과 유효유량의 개념으로 설명된다. 금회 연구에서는 국내에서 많이 이용되는 1.58년 빈도의 홍수량을 포함하여 각종 빈도의 홍수량을 결정하고, 이를 1차원 부등류 해석 프로그램에서 모의하여 수위 및 유량을 결정하였다. 하도 형성 유량 산정을 위해 이용된 홍수의 빈도는 1.01년, 1.58년, 2년, 2.33년, 5년이다. 각 빈도별 홍수량은 해당하천의 하천정비 기본계획에서 제시된 80년 빈도 홍수량과 무차원성장곡선을 이용하여 산정하였다. 오차분석 결과 조사된 전체 하천에서 1.01년 빈도의 홍수량이 강턱에 가장 근접하는 결과를 나타내었으며, 국내에서 관행적으로 이용하던 국내에서 관행적으로 이용되는 1.58년 빈도 홍수량은 강턱유량의 개념에서 하도 형성 유량에 접근할 때는 과대하게 평가되는 점을 확인할 수 있었다.

• Ocean and Polar Research
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• 제40권4호
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• pp.191-202
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• 2018

In this study we conducted a weekly monitoring exercise at a fixed station in the saltwater zone during the dry season (Jan-Mar, 2013) and wet season (Jun-Aug, 2013) to understand the fluctuations in phytoplankton communities and environmental factors in the Youngsan River estuary altered by a dike constructed in the coastal area. Phytoplankton communities displayed seasonality; diatoms were dominant during the dry season whereas dinoflagellates were dominant during the wet season. T-test analysis showed that water temperature was significantly different between the seasons whereas freshwater discharge from the dike was not significantly different. This suggests that seasonal variations of phytoplankton are more likely affected by water temperature than freshwater discharge. However, a short-term fluctuation was also observed in response to freshwater discharge; freshwater species appeared during or after the discharge in the dry and wet seasons and blooms of harmful species developed after the discharge. Phytoplankton communities may be affected by changes in physical factors such as turbidity and salinity and nutrient supply resulting from freshwater discharge. Especially, the nutrient supply may directly contribute to the harmful algal blooms (HABs) composed of dinoflagellates which can adapt to low salinity after freshwater discharge.

• ALGAE
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• 제23권2호
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• pp.151-162
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• 2008

Marine algal flora and community structure were seasonally examined at three sites in the vicinity of the Wolseong nuclear power plant in Korea from February to November 2006. A total of 126 seaweeds including 25 green, 31 brown, 70 red algae, and 1 marine plant were identified. The greatest number of species occurred at Jeonchonri (101 species) followed by intake (88 species) and discharge (29 species) during the study period. Of 126 seaweeds, 76 annuals and 13 warm tolerance species were recorded. Dominant species based on important value (IV > 10) were Ulva pertusa and Enteromorpha linza at intake, U. pertusa and Padina arborescens at discharge, and Sargassum horneri and Corallina pilulifera at Jeonchonri shore. Annual average biomass exhibited a wide range of variations, from 40.67g m-2 in dry weight at discharge to 133.69g m-2 at Jeonchonri. Among six functional groups, dominant group was coarsely-branched form at intake and Jeonchonri, but it was different at discharge site as filamentous form. Seaweed community structures of discharge site were distinguishable in decreasing species richness, biomass, species diversity index (H’), richness index (R), and evenness index (J’). Also, the ratios of green algae, warm tolerance species, annual algae, filamentous form and dominance index (DI) remarkably increased. Such phenomenons of discharge site are usually found under environmentally stressful conditions such as high disturbance. Thus, I can conclude that the heated effluents of nuclear power plant act as environmental stress influencing seaweed community structures and it can be detected with various community indices.

• 한국수산과학회지
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• 제42권4호
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• pp.387-394
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• 2009

Marine algal flora and community structure were examined seasonally at four study sites around Taean Power Plant, Korea from Jan. to Nov. 2006. A total of 73 algae species (12 green, 9 brown, 52 red) and 1 marine plant were identified. The number of species was maximal at the power plant Discharge (57 species) site followed by Hakampo (46 species), Intake (28 species) and Breakwater (15 species) sites during the study period. The average biomass in dry weight varied from 13.12g/m2 at Intake to 69.60g/m2 at Hakampo. Dominant and sub dominant species in terms of biomass were Gelidium divaricatum - Ulva pertusa at Intake, Chondria crassicaulis - Ulva pertusa at Discharge, Corallin a pilulifera - Chondrus ocellatus at Breakwater, and Corallina pilulifera - Sargassum thunbergii at Hakampo. Species richness of warm tolerant and green algae were greater at Discharge site than Hakampo, showing similar species richness. However, community indices were not distinguishable between Discharge and other study sites. In conclusion, species richness and biomass of seaweeds were greater at Discharge site compared to intake and breakwater sites, and the abundance of warm tolerant and green algal species were higher than Hakampo.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.107-112
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• 2001

The effect of ambient gas (steam) condensation on swirl spray characteristics were studied experimentally for low subcooling condition of the liquid. The configuration of the liquid(water) sheet and the breakup modes were examined. Also variation of the discharge coefficient, breakup length, local and the cross-sectional area-averaged SMD of droplets with the liquid flow(injection) rate were obtained. The perforation breakup mode appears dominant with condensation while the aerodynamic wave breakup mode is dominant without condensation(in the air environment). The discharge coefficient, breakup length and the mean drop sizes decrease in a same manner with increasing of the liquid flow rate for both cases(with and without condensation). The condensation effects are insignificant with the discharge coefficient. However, the local and cross-sectional area-averaged SMD are larger and the breakup length becomes shorter in the steam environment. The spray angle predicted from the volumetric flux distribution along the radial direction of the sprays in the steam environment becomes larger with condensation.