• 제목/요약/키워드: Individual dispersion

검색결과 102건 처리시간 0.026초

스태틱 믹서의 혼합특성 (Mixing Characteristics of Static Mixers)

  • 양희천;박상규;오승원
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1955-1960
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    • 2003
  • Static mixers have found a large range of applications, including blending, reaction, dispersion, heat transfer and mass transfer. All static mixers have in common a straight pipe or transfer tube into which individual elements are inserted to cut, fold, twist and re-combine the mixing fluid. The operations virtually ensure uniformity in composition, concentration, viscosity and temperature. The objective of this study is to perform the experimental investigations of mixing characteristics for three mixing element types. The resulting mixing patterns were recorded with a digital camera. OPTIMAS was used to analysis the visualized images. The results clearly indicated that the mixing characteristics was highly influenced by the mixer types or mixing mode.

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Micro/Millimeter-wave Photonic Pulse Train Generation by using Low-Speed Electronics and Optical Repetition Rate Multiplication

  • Lee, J.M.;Seo, D.S.
    • 전기전자학회논문지
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    • 제11권3호
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    • pp.117-121
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    • 2007
  • 20 GHz and 40 GHz micro/millimeter-wave photonic pulse trains have been generated from a fiber ring laser with a semiconductor optical amplifier (SOA) by injecting 2 GHz gain-switched Fabry-Perot laser diode (GS-FPLD) output. To achieve efficient cross-gain modulation in the SOA at 20 GHz and 40 GHz, individual lasing modes of the 2 GHz GS-FPLD output separated to 25 and 50 picoseconds respectively by passing dispersion compensating fibers.

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노후 철근콘크리트 건물 기둥의 파괴 모드에 따른 취약도 함수 (Fragility Function According to Failure Mode for Lightly Reinforced Concrete Columns)

  • 구수현;한상환
    • 한국지진공학회논문집
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    • 제28권4호
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    • pp.215-222
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    • 2024
  • Many older reinforced concrete (RC) buildings were constructed and designed with only gravity loads in mind. Columns in those buildings have insufficient reinforcement details that do not satisfy the requirements specified in current seismic design standards. This study aims to develop drift-based fragility functions for lightly RC columns. For this purpose, a database of 193 lightly RC columns was constructed to determine central and dispersion values of drift ratios for individual damage states. Additionally, to develop more accurate fragility functions of the columns, the failure mode of RC columns was incorporated into fragility functions. The classification procedure for column failure mode is proposed in this study. Fragility functions for older RC columns are constructed according to four different damage states. The main variables of the fragility functions proposed in this study are column properties and failure mode.

Comb Transducer를 이용한 파이프 내 유도초음파 모드의 거동에 관한 연구 (A Study on the Behavior of Ultrasonic Guided Wave Mode in a Pipe Using Comb Transducer)

  • 박익근;김용권;조윤호;안연식;조용상
    • 비파괴검사학회지
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    • 제24권2호
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    • pp.142-150
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    • 2004
  • 발전설비의 보수검사에 적용하기 위한 예비 연구로 comb transducer를 이용한 파이프 내에서의 유도초음파 모드의 거동을 실험적으로 검증하였다. 유도초음파의 모드식별은 STFT와 WT에 의한 시간-주파수해석을 통하여 최적의 모드를 선정하였다. 시간-주파수해석과 이론적 해석 방법인 분산 곡선을 비교한 결과 잘 일치함을 알 수 있었으며, pitch-catch법과 선단부로부터 반사된 신호를 모드 분석한 결과 L(0,1) 모드가 다른 모드에 비해 모드변환에 의한 영향이 적었다. 따라서 L(0,1)을 최적의 모드로 선정하고, 결함위치를 추정한 결과 유용함을 알 수 있었다.

준 실시간 측정시스템을 이용한 미세입자 원소성분 배출특성 조사 (Emission Characteristics of Elemental Constituents in Fine Particulate Matter Using a Semi-continuous Measurement System)

  • 박승식
    • 한국대기환경학회지
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    • 제26권2호
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    • pp.190-201
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    • 2010
  • Fine particulate matter < $1.8{\mu}m$ was collected as a slurry using the Semicontinuous Elements in Aerosol Sampler with time resolution of 30-min between May 23 and 27, 2002 at the Sydney Supersite, Florida, USA. Concentrations of 11 elements, i.e., Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Se, and Zn, in the collected slurry samples were determined off-line by simultaneous multi-element graphite furnace atomic absorption spectrometry. Temporal profiles of $SO_2$ and elemental concentrations combined with meteorological parameters such as wind direction and wind speed indicate that some transient events in their concentrations are highly correlated with the periods when the plume from an animal feed supplement processing facility influenced the Sydney sampling site. The peaking concentrations of the elemental species during the transient events varied clearly as the plume intensity varied, but the relative concentrations for As, Cr, Pb, and Zn with respect to Cd showed almost consistent values. During the transient events, metal concentrations increased by factors of >10~100 due to the influence of consistent plumes from an individual stationary source. Also the multi-variate air dispersion receptor model, which was previously developed by Park et al. (2005), was applied to ambient $SO_2$ and 8 elements (Al, As, Cd, Cr, Cu, Fe, Pb, and Zn) measurements between 20:00 May 23 and 09:30 May 24 when winds blew from between 70 and $85^{\circ}$, in which animal feed processing plant is situated, to determine emission and ambient source contributions rates of $SO_2$ and elements from one animal feed processing plant. Agreement between observed and predicted $SO_2$ concentrations was excellent (R of 0.99; and their ratio, $1.09{\pm}0.35$) when one emission source was used in the model. Average ratios of observed and predicted concentrations for As, Cd, Cr, Pb, and Zn varied from $0.83{\pm}0.26$ for Pb to $1.12{\pm}0.53$ for Cd.

대규모 도시개발사업에 대한 대기질 평가 사례 연구 (A Case Study on the Air Quality Impact Assessment for the Large Scale Urban Development)

  • 김상목;이상훈;박근형;우재균;구윤서;김성태;한진석
    • 환경영향평가
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    • 제16권6호
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    • pp.381-391
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    • 2007
  • The air quality modeling was carried out to assess the impact of air quality for large scale urban development. The site for the assessment is Multi-fuctional Administrative City which locates in Yeongi-gun, Chungcheongnam-do and estimated population in 2030 is 500,000. Two automatic weather monitoring stations were installed to monitor the meteorological variables for a year and upper air meteorological parameters were measured using radiosonde for 5 days with 4 hours interval in every season. The air quality of standard air pollutants were also measured for 5 days continuously in every season. The results of wind field analysis based on the site measurements and CALMET modeling showed that the valley and mountain winds were prevailed when the sypnotic wind was weak. It also showed that wind speed and directions were highly space-variable within the site basin. The variable wind characteristics implies that the Gaussian dispersion model such ISC3 and AERMOD are not appropriate and the unsteady-sate Lagrangian model such as CALPUFF is preferable. CALPUFF model was applied to assess air quality impact of new sources. The new sources were those for individual and group heating facilities as well as the traffic increases. The results showed that the estimated concentrations of CO and $SO_2$ pollutants by summing the impact concentration of new sources by the dispersion model and the ambient air concentrations by the site measurements were acceptable but those of PM-10 and $NO_2$ would violate ambient air quality standards at several locations due to high ambient air concentrations. It is recommended that the emission reductions near the site should be enforced to improve the ambient air quality.

영과잉 및 허들 회귀모형을 이용한 과학화 전투훈련 자료 분석 (Analysis of scientific military training data using zero-inflated and Hurdle regression)

  • 김재오;방성완;권오정
    • Journal of the Korean Data and Information Science Society
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    • 제28권6호
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    • pp.1511-1520
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    • 2017
  • 본 연구는 과학과 전투훈련 자료를 분석하여 작전 및 군사훈련 방법을 향상하고 필요한 군사교리를 검증하기 위한 것이다. 우리는 과학화 전투훈련 중 대대급 공격작전에 대해 개별 전투원이 공격작전간 개인 화기를 이용하여 적을 중상 이상의 전투불능 상태로 만든 인원수를 반응변수로 둔다. 본 연구의 반응변수는 영이 지나치게 많이 관측되어 전통적인 일반화 선형모형에서 분석이 제한된다. 우리는 과대산포 및 영이 과도하게 관측된 점을 고려하여 영과잉 회귀모형과 허들 회귀모형을 자료에 적합하여 분석한다. 우리의 분석 결과는 대한민국 육군의 보병대대와 같은 소부대의 다양한 작전 및 전술적 요인에 대한 분석과 전술제대의 군사교리 검증함에 있어 적절한 참고자료로 활용될 수 있다.

노동조합과 임금구조 (Trade Union and Wage Structure)

  • 류재우
    • 노동경제논집
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    • 제30권1호
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    • pp.31-53
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    • 2007
  • 본 연구는 노동조합이 임금수준 및 분포에 미치는 효과를 우리나라의 제조업 생산직 남자 노동자를 중심으로 분석하였다. 임금수준에 대한 효과를 분석함에 있어서는 연립방정식을 사용하여 기업 특성을 충분히 통제한 위에 노조의 임금프리미엄을 정확하게 추정하고자 하였다. 노동조합과 기업의 수익성과의 관계에 관해서는 노동조합이 흑자를 얻고 있는 기업들의 수익성을 낮춘다는 사실이 확인되었다. 임금수준에 관해서는 노조가 있는 기업의 노동자가 누리는 임금프리미엄은 5~8%인 것으로 추정되었다. 그러나 노조원이 실제로 누리는 임금 및 고용상의 이득은 이들 수치가 제시하는 것보다 크다. 노조가 학력이나 외부 경력 등에 대한 한계보상을 낮추고 대신 근속에 대한 보상을 높이는 방식으로 선임자에게 유리한 임금체계를 구조화시킨 위에 강력한 고용보호정책으로 노조원의 근속연수를 비노조 부문의 두 배가 되게끔 만들었기 때문이다. 임금분산에 대한 분석에서는 노조기업 노동자간의 임금분산이 더 작아 이론적인 예측과 합치하는 것으로 나타난 반면, 인적 속성을 통제한 이후의 임금분산은 노조부문에서 더 크게 나타났다.

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가산자료모형을 이용한 서해 태안군 유어객의 편익추정 (Estimating the Economic Value of Recreation Sea Fishing in the Yellow Sea: An Application of Count Data Model)

  • 최종두
    • 자원ㆍ환경경제연구
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    • 제23권2호
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    • pp.331-347
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    • 2014
  • 본 연구는 서해에 위치한 태안군을 방문하는 유어객의 방문 편익을 분석하기 위하여 개별여행비용법과 가산자료모형을 이용하여 수요모형을 추정하고 경제적 가치를 측정하였다. 여행객방문속성을 감안하여 분석모형으로 포아송모형(Poisson Model, PM), 음이항모형(Negative Binomial, NB), 절단된 포아송모형(Truncated Poisson Model, TPM), 절단된 음이항모형(Truncated Negative Binomial, TNB)을 분석에 이용하였다. 분석결과 추정계수들은 통계적으로 유의하게 나타났으며, 경제이론에도 부합되는 결과를 도출하였다. 과산포(overdispersion)현상은 발견되지 않았으며, 모형적합도검정을 통하여 절단된 포아송모형이 적정모형으로 선정되었다. 또한, 서해 태안군 해역내 유어활동의 경제적가치를 추정하기 위하여 유어객의 연평균 출조횟수와 최적모형으로 선정된 절단된포아송모형(TPM)으로 분석한 결과 1인 1회 출조당 경제적 가치는 254,453원이며, 1인당 연간 총 경제적 가치는 1,536,896원으로 도출되었다.

다수기 원자력발전소 사고 시 소외 방사성물질 농도 계산 방법 (A Method to Calculate Off-site Radionuclide Concentration for Multi-unit Nuclear Power Plant Accident)

  • 이혜린;이기만;정우식
    • 한국안전학회지
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    • 제33권6호
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    • pp.144-156
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    • 2018
  • Level 3 Probabilistic Safety Assessment (PSA) is performed for the risk assessment that calculates radioactive material dispersion to the environment. This risk assessment is performed with a tool of MELCOR Accident Consequence Code System (MACCS2 or WinMACCS). For the off-site consequence analysis of multi-unit nuclear power plant (NPP) accident, the single location (Center Of Mass, COM) method has been usually adopted with the assumption that all the NPPs in the nuclear site are located at the same COM point. It was well known that this COM calculation can lead to underestimated or overestimated radionuclide concentration. In order to overcome this underestimation or overestimation of radionuclide concentrations in the COM method, Multiple Location (ML) method was developed in this study. The radionuclide concentrations for the individual NPPs are separately calculated, and they are summed at every location in the nuclear site by the post-processing of radionuclide concentrations that is based on two-dimensional Gaussian Plume equations. In order to demonstrate the efficiency of the ML method, radionuclide concentrations were calculated for the six-unit NPP site, radionuclide concentrations of the ML method were compared with those by COM method. This comparison was performed for conditions of constant weather, yearly weather in Korea, and four seasons, and the results were discussed. This new ML method (1) improves accuracy of radionuclide concentrations when multi-unit NPP accident occurs, (2) calculates realistic atmospheric dispersion of radionuclides under various weather conditions, and finally (3) supports off-site emergency plan optimization. It is recommended that this new method be applied to the risk assessment of multi-unit NPP accident. This new method drastically improves the accuracy of radionuclide concentrations at the locations adjacent to or very close to NPPs. This ML method has a great strength over the COM method when people live near nuclear site, since it provides accurate radionuclide concentrations or radiation doses.