• Title/Summary/Keyword: 변이 조건

Search Result 1,864, Processing Time 0.031 seconds

Accuracy analysis on the temperature measurement with thermistor (인공위성용 서미스터의 온도측정 정확도 분석)

  • Suk, Byong-Suk;Lee, Yun-Ki;Lee, Na-Young
    • Aerospace Engineering and Technology
    • /
    • v.7 no.1
    • /
    • pp.115-120
    • /
    • 2008
  • The thermistors and AD590 are widely used for temperature measurement in space application. The resistance of thermistor will vary according to the temperature variation therefore the external voltage or current stimulus signal have to be provided to measure resistance variation. Recently high resolution electro optic camera system of satellite requires tight thermal control of the camera structure to minimize the thermal structural distortion which can affects the image quality. In order to achieve $1^{\circ}$(deg C) thermal control requirement, the accuracy of temperature measurement have to be higher than $0.3^{\circ}$(deg C). In this paper, the accuracy of temperature measurement using thermistors is estimated and analyzed.

  • PDF

Estimation of Trapping Efficiency Using VFSMOD: Application to Cheongmi Basin (VFSMOD를 이용한 토사저감효율 산정: 청미천 유역에서의 적용)

  • Son, Minwoo;Byun, Jisun
    • Proceedings of the Korea Water Resources Association Conference
    • /
    • 2015.05a
    • /
    • pp.338-338
    • /
    • 2015
  • 하천으로 유입되어 수질 오염을 야기하는 오염원은 오염 배출원이 명확하여 하나의 점으로 나타낼 수 있는 점오염원(Point Source)과 오염원이 명확치 않은 비점오염원(Non-point)으로 구분된다. 생활하수, 축산폐수와 같이 오염원이 명확한 점오염원은 하천 유입 이전에 처리장을 거쳐 정화작업이 가능한 반면, 비점오염원은 오염원이 명확치 않아 처리에 어려움이 따른다. 또, 오염물의 양과 이동 경로가 예측이 불가능하고 강우시에는 특별한 처리 없이 하천으로 바로 유입된다. 비점 오염원의 종류는 토사, 영양물질, 유기물질, 농약, 바이러스 등 다양하다. 이 중에서 토양에 흡착되어 이동하는 질소와 인은 하천으로 유입되어 부영양화를 야기하는 특성이 있어 더욱 처리가 필수적이다. 이러한 비점오염원으로 인한 수질 오염을 줄이기 위해 여러 최적관리기법(Best Management Practices, BMPs)이 제시되어 있으며 오염 물질의 하천 유입을 차단하는 것에 중점을 둔다. 가장 널리 이용되는 방법으로는 비점오염원 저감시설 중 하천변에 식물체를 설치하여 토양의 유실을 막는 식생대(Vegetative Filter Strip, VFS)가 있다. 식생 밀집 지역의 설치를 통해 표면 유출을 차단하고 토양 유실 감소와 수체로의 오염물질 확산을 막을 수 있다. 이에 VFSMOD-w를 이용하여 강우시 식생대를 통한 토양 유실 감소 효율에 대한 연구를 수행하였다. 연구 대상 지역으로 비교적 수문 및 토양 자료가 풍부한 청미천 유역을 선정하였다. 그 결과, 식생대의 길이와 식생대 내 식물체의 파종간격이 가장 지배적인 영향을 미치는 것이 확인된다. 이때, 식물체의 종류는 식물체 파종으로 인해 변화되는 토양의 수정된 Manning의 조도계수로 구분한다. 모든 강우 및 식물체 조건이 동일할 때, 식생대 내 식물의 파종 간격이 좁고 식생대의 길이가 길수록 토사 저감 효율이 증가하는 결과가 도출되었다. 식물체의 높이, 식물체의 종류 및 식물의 파종간격이 입력 자료로 요구되나 이 중 식물체의 높이는 토사 저감 효율에 영향을 미치지 않는 것으로 나타났다. 또, 동일한 강우 조건에서 식생대의 길이가 0.5 m에서 1.0 m로 2배 증가하였을 때 토사 저감 효율이 두 경우 모두 95% 이상의 효율을 보이는 것이 나타났다. 이는 식생대의 길이가 증가할수록 토사 저감 효율이 증가하나 일정 길이 이상이 되면 대부분의 토사가 저감되는 것을 의미한다. 결론적으로 식생의 파종 간격이 좁을수록 토사 저감 효율이 증가하더라도 식물체의 성장을 고려한 적절한 파종 간격을 선정하여야 한다. 즉, 식생대의 설치는 적절한 파종 간격 및 식생대 길이를 식생대 설치지역의 강우 특성에 따라 결정지어야 한다고 판단된다.

  • PDF

A study of the removal efficiency of acidic gas at various operating conditions using Computation Fluid Dynamics (전산유체역학을 이용한 반건식 반응기의 운전조건에 따른 산성가스제거효율에 관한연구)

  • Lee, Geon-Ju
    • Journal of the Korea Organic Resources Recycling Association
    • /
    • v.19 no.1
    • /
    • pp.93-101
    • /
    • 2011
  • The modeling of SDR was carried out for the application of the solid waste incineration system. To find optimum operating condition for removal of acidic gases, computation fluid dynamic(CFD) model was used. In this study, the temperature profile of SDR(spray dry reactor) and the gas velocity profile for different models were investigated. In this model, the diameter of SDR was 3 meter and the height of SDR was 9 meter. The amount of inlet combustion gas of SDR was $6,125Nm^3/hr$ and the inlet temperature of SDR was 493 K. The amount of lime injection of SDR was 151 kg/hr. When the inlet shape of SDR was changed, the temperatur of SDR was changed and the gas velocity of SDR was 0.48 m/sec to 1.17m/sec and the outlet gas velocity of SDR was 6.9 m/sec to 7.42m/sec As a result of modeling, the average velocities in SDR and outlet were 0.489 m/sec and 7.424 m/sec, respectively, in which the temperature of outlet in SDR was 448 K.

Varietal Differences of Germination and Emergence Capacity under Low Temperature Conditions in Barley (대맥에서 저온 발아 및 출현력의 품종간 차이)

  • Chun, J.U.;Lee, E.S.;Lee, S.Y.
    • KOREAN JOURNAL OF CROP SCIENCE
    • /
    • v.29 no.2
    • /
    • pp.152-156
    • /
    • 1984
  • Germination and emergence of 16 barley cultivars bred in Korea were studied under different low temperature conditions in laboratory at Suweon. This study revealed that the barley cultivars differed markedly in their germination rate index (GRI), emergence rate index (ERI), and dry matter weight. The seeds of Baekdong, Namhaebori, Gangbori and Buheung germinated better than others in $4^{\circ}C$ plot. Yeongsanbori, Kwangseong and Baekdong had very poor ERI values, but Buhobori, Namhaebori, Oweolbori, Albori and malting barley, Sacheon 6 had very good ERI values. Germination rate index were not correlated with emergence rate index under any temperature conditions. The correlation coefficient between ERI of $4^{\circ}C$ and $7^{\circ}C$ plots was very high. Those results showed that for screening the varieties or lines with good emergence capacity under low temperature conditions ERI, FS and dry matter weight would be available.

  • PDF

A Study on Elastic Shear Buckling Coefficients of Horizontally Curved Plate Girder Web Panels (강곡선 플레이트거더 복부판의 전단좌굴계수에 관한 연구)

  • Lee, Doo-Sung;Lee, Sung-Chul
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.28 no.3A
    • /
    • pp.367-373
    • /
    • 2008
  • In the design of horizontally curved plate girder web panels, it is required to evaluate accurately the elastic buckling strength under pure shear. Currently, elastic shear buckling coefficients of curved web panels stiffened by transverse intermediate stiffeners are determined by assuming conservatively that straight web panels without curvature are simply supported at the juncture between the flange and web. However, depending upon the geometry and the properties of the curved plate girder, the elastically restrained support may behave rather closer to a fixed support. The buckling strength of curved girder web is much greater (maximum 38%) than that of a straight girder calculated under the assumption that all four edges are simply supported in Lee and Yoo (1999). In the present study, a series of numerical analyses based on a 3D finite element modeling is carried out to investigate the effects of geometric parameters on both the boundary condition at the juncture and the horizontal curvature of web panel, and the resulting data are quantified in a simple design equation.

The analysis of columnar to equiaxed dendritic transition during alloy solidification (합금응고시 주상정으로부터 등축정 수지상으로의 천이에 관한 해석)

  • 김신우
    • Journal of the Korean Crystal Growth and Crystal Technology
    • /
    • v.8 no.1
    • /
    • pp.187-192
    • /
    • 1998
  • Generally the solidified microstructures of materials consist of the columnar and equiaxed dendritic regions, and many theoretical studies about columnar-to-equiaxed transition have been done because that is closely related to the mechanical and physical properties of products. In this study, the modified equation based on the Hunt's analytical columnar-to-equiaxed transition condition which was derived from heterogeneous nucleation and grain growth in front of the columnar dendrite tip under directional solidification, was obtained applying the growth-velocity-dependent distribution coefficient and liquidus slope to Hunt's. The effects of the number of nucleation sites, nucleation temperature, alloy composition, growth velocity and liquid temperature gradient on the transition for Al-Cu alloys have been investigated.

  • PDF

Effect of Climatic Factors on Disease Incidence of Barley fellow Mosaic Virus (BaYMV) (기상 요인이 보리호위축병(BaYMV) 발생에 미치는 영향)

  • 박종철;서재환;김형무;이귀재;박상래;서득용
    • KOREAN JOURNAL OF CROP SCIENCE
    • /
    • v.48 no.3
    • /
    • pp.156-159
    • /
    • 2003
  • Barley yellow mosaic virus (BaYMV) cause severe damage in barley cropping field especially yield reduction about 40% to 100% depend on climatic conditions and varieties. The correlations between disease incidence (DI) and changes of climatic conditions were analyzed. The average temperature affected on the DI in early barley growing stage before wintering. However any factors was not correlated with DI during wintering season that means barley growth was closely related to virus reproduction. Significant correlation between the highest temperature and DI during barley regeneration time that temperature, especially the highest, has to be considered to set appropriate time for DI investigation.

Studies on the Optimal Conditions of Sterilization for Streptococcus pyogenes (Part 1) Effect of Heat Treatment on Typical Death Rate (항암활성을 지닌 Streptococcus pyogenes의 적정 살균조건에 관한 연구 (제 1보) 살균조건에 미치는 열 처리의 영향)

  • 유주현;김성욱;배종찬;변유량
    • Microbiology and Biotechnology Letters
    • /
    • v.9 no.4
    • /
    • pp.231-236
    • /
    • 1981
  • Studies were made on the optimal conditions of sterilization for Streptococcus pyogenes treated with heat. The results were as follows: The optimal temperature on growth of Streptococcus pyogenes was 37$^{\circ}C$ and mean generation time was 20 minutes in the logarithmic growth phase. The suspension of Streptococcus pyogenes, adjusted to pH 6-9 and treated with heat at 5$0^{\circ}C$, showed logarithmic death rate. Specific death rate constant(k) values at pH 6-9 were 0.1448, 0.1194. 0.1273 and 0.1707 minute$^{-1}$ , respectively.

  • PDF

Fermentation Characteristics of Salt-Tolerant Mutant, Candida magnoliae M26, for the Production of Erythritol (염 내성 변이균주 Candida magnoliae M26에 의한 에리스리톨 발효특성)

  • 이강희;서진호;유연우
    • KSBB Journal
    • /
    • v.17 no.6
    • /
    • pp.509-514
    • /
    • 2002
  • Experiments were carried out to optimize the fermentation conditions for the production of erythritol by salt-tolerant mutant, Candida magnoliae M26. The optimum conditions of erythritol production showed a 1.0 vvm aeration and 500 rpm agitation at 28$\^{C}$ with an initial medium pH of 7.0. The pH control during the fermentation did not improve the erythritol yield and productivity. The maximum erythritol concentration of 143.3 g/L was obtained with 57% yield and 0.70 g/L-h productivity from 250 g/L of glucose and 5 g/L of yeast extract under an optimum fermentation conditions. The medium containing 0.5 M KCl or 0.5 M NaCl enhanced the production of erythritol and glycerol. However, glycerol production increased and erythrtiol production decreased by increasing the concentration of NaCl or KCl.

Theoretical Analysis of Open Water Characteristics of a Rudder (타 단독 특성의 이론적 해석)

  • I.Y. Gong;C.G. Kang;C.M. Lee
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.29 no.1
    • /
    • pp.29-42
    • /
    • 1992
  • A potential based panel method is used to predict the open water characteristics of spade-type rudders. The inflow velocity is assumed to be constant in lime and uniform in space. Source and dipole are distributed on the rudder surface. It is assumed that the wake surface is streaming from trailing edge and it is represented by dipole distribution. In this paper, wake geometry is assumed by imposing appropriate conditions at the trailing edge and far from the body. The effects of wake geometry are studied. The pressure Kutta condition is applied at the trailing edge, the effects of which are compared with those of two-dimensional Kutta condition. The results of calculations for a spade-type rudder are compared with published results. It is concluded that this approach shows fairly good agreement with experimental results and can be used in the initial design stage of a rudder.

  • PDF