• 대한기계학회논문집B
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• 제27권7호
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• pp.948-955
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• 2003

Pressure coefficient in rotating discharge hole was measured to gain insight into the influence of rotation to the discharge characteristics of rotating discharge hole. Pressure measurements were done by the telemetry system that had been developed by the authors. The telemetry system measures static pressure using piezoresistive pressure sensors. Pressure coefficients in rotating discharge hole were measured in longitudinal direction and circumferential direction with various rotating speed and 3 pressure ratios. From the results, the pressure coefficient, and therefore the discharge coefficient, is known to decrease with the increase of Ro number owing to the increase of flow approaching angle to the discharge hole inlet. However, there exists critical Ro number where the decrease rate of discharge coefficient with the increase of Ro number changes abruptly; flow separation occurs from the discharge hole exit at this critical Ro number. Critical Ro number increases with the increase of length-to-diameter ratio, but the increase is small where the length-to-diameter ratio is higher than 3. The decrease rate of discharge coefficient with the increase of Ro number depends on the pressure recovery at the discharge hole, and the rate is different from each length-to-diameter ratio; it has tendency that the short discharge hole shows higher decrease rate of discharge coefficient.

• 한국습지학회지
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• 제19권3호
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• pp.335-344
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• 2017

본 연구에서는 미계측유역의 설계홍수량을 산정하는 방안으로 유역의 면적비를 적용하는 방안을 제안하였다. 이를 위해 유역출구에서의 실측자료를 활용하여 유출매개변수를 결정하고 면적비를 적용하여 첨두홍수량을 산정하였다. 위 방법론을 검증하기 위해 소하천 유역의 관측유량 및 하천정비종합계획의 설계홍수량과의 비교를 통해 면적비 전이 방법론의 타당성을 검토하였다. 그 결과를 정리하면 다음과 같다. 면적비를 적용한 유출량과 관측유량자료를 비교한 결과 14~25% 정도의 차이를 보였다. 제안된 방법론의 타당성을 재확인하기 위해 하천정비종합계획에서 산정된 첨두유량과 소유역과의 면적비로 계산한 첨두유량을 비교하였다. 이를 위해 31개소의 소하천을 대상으로 설계홍수량을 비교한 결과, 20% 정도의 홍수량의 차이가 발생하였다. 따라서 면적비를 적용한 미계측지역에서의 첨두유량 산정방법론이 타당하다고 판단된다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.1425-1427
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• 2009

In this paper, we investigated influence of gas pressure and gas mixing ratio on the abnormal discharge characteristics of fluorescent lamp. Abnormal discharge characteristics have been examined by changing inner gas pressure and mixing ratio. As the inner gas pressure and mixing ratio increase, the occurrence of abnormal discharge was delayed. It was found out that the occurrence of abnormal discharge is sufficiently delayed at the optimized inner gas pressure and mixing ratio.

• 대한영양사협회학술지
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• 제18권1호
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• pp.16-29
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• 2012

The purpose of this study was to investigate the changes in nutritional status of gastrectomy patients. The anthropometric and biochemical data were measured at pre-operation, at discharge, 1 month after discharge, and 3 months after discharge. Nutrient intake levels, nutrients adequacy ratio (NAR), mean adequacy ratio (MAR), and the proportion of patients with intake levels inferior to those of dietary reference intakes (DRIs) were analyzed at discharge, 1 month after discharge, and 3 months after discharge. Finally, the data on 23 patients (15 male and 8 female) were collected and used for statistical analysis. Fifteen patients underwent subtotal gastrectomy, and 8 patients underwent total gastrectomy. Compared to pre-operation, body weight and body mass index of subjects significantly decreased at discharge, 1 month after discharge, and 3 months after discharge (P<0.001). Serum albumin (P<0.001), total lympocyte count (P<0.001), total cholesterol (P<0.001), hemoglobin (P<0.001), hematocrit (P<0.001), and mean corpuscular hemoglobin concentration (P<0.05) were significantly different between pre-operation, at discharge, 1 month after discharge, and 3 months after discharge. The proportions of patients with lower nutrient intake levels than DRIs were substantial. MAR at discharge, 1 month after discharge, and 3 months after discharge were 0.70, 0.80 and 0.91, respectively. Especially, the NARs of folate, niacin, vitamin $B_2$, vitamin C, and zinc were all low. Considering the various nutritional problems of gastrectomy patients, systematic medical nutrition therapy is needed after gastrectomy.

• Tribology and Lubricants
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• 제17권1호
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• pp.22-27
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• 2001

This paper presents an analysis of eccentricity ratio of rolling piston using mobility method which is a powerful tool for analyzing dynamically-loaded journal bearings with efficiency and applicability. And, we investigate influences of design parameters (discharge pressure, radial clearance, rotational velocity of shaft, and eccentricity of compressor) on bearing load and eccentricity ratio. The results show that the discharge pressure, radial clearance and rotational velocity of shaft have significant influence on eccentricity ratio, and the discharge pressure and eccentricity of compressor have influence on bearing load.

• 한국수자원학회논문집
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• 제37권10호
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• pp.881-888
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• 2004

본 연구에서는 지류와 본류의 합류부의 접근각도, 상류부 유량 및 본류와 지류의 유량비 변화에 따른 수리 모형실험을 통한 합류부의 수리학적 특성을 파악하였다. 합류부의 수리학적 특성은 합류점 부근의 유속과 관련된 최대유속의 크기 및 발생위치를 분석하였다. 합류점 부근의 최대유속은 접근각도가 증가함에 따라 점차 증가하며, 이는 유량 및 유량비가 증가하는 경우에도 동일한 경향을 나타낸다. 합류점 부근의 최대유속의 발생지점은 접근각도가 증가함에 따라 거리가 증대되는 것으로 나타났다. 또한, 유량이 증가하는 경우에도 거의 동일한 양상을 보여준다.

• 대한기계학회논문집B
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• 제24권7호
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• pp.957-966
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• 2000

The effect of rotation on the discharge coefficient of orifices with various length-to-diameter ratios and two different inlet corner radii was studied. Length-to-diameter ratios of the orifices range from 0.2 to 10, while the inlet shapes are square edged, or round edges of radius-to-diameter ratio of 0.5. From the experiment, we found that rotational discharge coefficient and Rotation number, when based on ideal exit velocity of the orifice considering momentum transfer from the rotor, describe the effect of rotation very well. In this study, the discharge coefficients of rotating orifices are shown to behave similar to those of the well-known non-rotating orifices. For both rotating and non-rotating orifices, the discharge coefficients increase with the length-to-diameter ratio until a maximum is reached. The flow reattachments in the relatively short orifices are responsible for the increase. The coefficient then decreases with the length-to-diameter ratio due to the friction loss along the orifice bore. The length-to-diameter ratio that yields maximum discharge coefficient, however, increases with the Rotation number because the increased flow-approaching angle requires larger length-to-diameter ratio for complete reattachment. The length-to-diameter ratio for complete reattachment is shorter for round edged orifices than that of square edged orifices by about a unit length-to-diameter ratio.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권2호
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• pp.103-108
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• 2004

This paper shows the simulation of electric field distribution and removal characteristics of Escherichia coli for water discharge tube with globular $SiO_2$. At the experiments of the removing Escherichia coli used the discharge tube with globular dielectric($SiO_2$), because the electric field is increased when applied voltage is increased, the removed ratio of Escherichia coli was related with increasing of applied voltage. When a passing number of test water in water discharge tube is increased, the removed ratio of Escherichia coli is increased because passing number of territory with electric field is increased. When diameter of globular dielectric($SiO_2$) is increased, the removed time of Escherichia coli was decreased because electric field for dielectric polarization of globular dielectric($SiO_2$) was increased. Also, the removed ratio of Escherichia coli of the water discharge tube with globular dielectric($SiO_2$) was measured higher than the removal ratio of the discharge tube without globular dielectric($SiO_2$)

• 한국물환경학회지
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• 제24권4호
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• pp.452-457
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• 2008

Nonpoint source (NPS) pollution is caused by rainfall moving over and through the ground. As the runoff moves, it picks up and carries away various pollutants from NPS. The discharge pattern of NPS pollutant loads is affected by the distribution of the rainfall during the year. This study analysed relationship between the rainfall event and the stream flow rate, and estimated the rainfall discharge ratio on the specific design flow which can be used as nonpoint discharge coefficient for the estimation of NPS pollution load. It is considered that nonpoint discharge coefficient can be effectively used for the calculation of NPS pollution load at the time of water quality modelling for the management of Total maximum daily load (TMDL).

• 상하수도학회지
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• 제19권5호
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• pp.619-624
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• 2005

This work is for examining a simplified equation based on the rational formula, which can easily decide storm-water detention volume in small urban catchments. The storm-water detention volume is determined by the inflow hydrograph flowing to detention basin and the outflow hydrograph discharged from the detention basin. The ratio of average outflow over the period of rainfall duration against allowable discharge was 0.5 in former simplified equation. But this research has found that the average outflow ratio depends on the storage methodology. In the case of the on-line storage method, the average outflow ratio is a function of the time of concentration of the catchments and rainfall duration, which ranged from 0.5~1.0. In the case of the off-line storage method, the average ratio is a function of peak discharge and allowable discharge except above time of concentration and rainfall duration, where its function value ranged from 1.0~2.0. When applying this equation to small catchment in Mokpo city, South Korea, we could easily calculate the relation curve between the storm-water detention volume and allowable discharge.