• 제목/요약/키워드: Drop simulation

검색결과 766건 처리시간 0.022초

신속 시작법용 액적 생성 장치에서의 액적 생성에 대한 연구 (A Study on the Drop Formation of the Liquid Jet Device for Rapid Prototyping)

  • 이우일;김선민;박종선
    • 대한기계학회논문집B
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    • 제25권8호
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    • pp.1021-1029
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    • 2001
  • Rapid prototyping(RP) is a novel technology to create 3D products directly from CAD system. This study proposes a new RP method which uses the PZT ceramic plate to make a Drop-On-Demand liquid jet from the nozzle. The characteristic of drop formation in the new system is investigated both numerically and experimentally. The optimal drop for 3-D Printing can be obtained by the proper amplitude and frequency of the applied voltage. Also the process of the drop formation is analyzed using the pressure wave theory and verified by numerical simulation. First, the pressure wave generated by the deformation of the Piezo-plate at the nozzle is analyzed by solving the 2D axisymmetric wave equation via Finite Element Method. Finally, the drop formation process is simulated using a commercial software, FLOW 3D considering the pressure at the nozzle obtained by solving the wave equation as the boundary condition.

드롭숄더 슬리브의 어깨각도 변화에 따른 패턴 연구 (Study of Patterns According to Changes in Shoulder Angle in Drop Shoulder Sleeves)

  • 이하은;이은혜;최정욱
    • 한국의상디자인학회지
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    • 제26권2호
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    • pp.15-32
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    • 2024
  • Modern fashion manifests in forms that mirror the diverse lifestyles and personalities of consumers. It transcends mere aesthetic designs and embodyies practicality. There is a preference for comfortable, highly functional attire, leaning towards easy wear. Casual wear, in particular, embraces a sense of freedom not found in standard business attire. It seeks a comfortable, natural silhouette through tactile fabrics rather than sportswear. Loose, drop shoulder sleeves enhance comfort and mobility and often become key elements in casual wear designs. Given that clothing must balance aesthetics with functionality, especially across various activities, it is natural to prioritize functional design. Research on patterns suited for dynamic conditions is imperative. The rise of drop shoulder styles necessitates the development of corresponding sleeve patterns. It is crucial to differentiate pattern drafting methods due to the resulting silhouette variations. This study aims to categorize drop shoulder pattern drafting techniques based on shoulder extension and angle dimensions. Each method will be examined, and drop shoulder sleeve patterns and wear forms will be studied using a 3D virtual system. This research holds significance in providing valuable insights and foundational data for designing diverse drop shoulder sleeve patterns, contributing to their practical development and advancement.

계통 안정도 모의를 통한 전력계통의 무력화 방안 (The Incapacition Method of Power System Assessing Transient Stability Index and Voltage Drop/Rise Duration Index)

  • 임재성;강현구;김택원;문승일;임완권
    • 한국군사과학기술학회지
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    • 제12권4호
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    • pp.532-539
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    • 2009
  • When assailing some area, it is important to consider targeting power system. This paper describes effective method that power networks are incapacitated based on assessing TSI and VDI. For this, we compose realistic scenario and analyze the simulation results in a view of stability. The simulation results show the destruction effects when occur the contingency in the specified area. To perform this process, the simulation tool PSS/E and DSAT are used.

혈관계 시스템 모델과 CFD의 결합을 통한 관상동맥 내 혈류의 수치적 해석 (Numerical analysis of the blood flow in coronary artery combining CFD method with the vascular system modeling)

  • 심은보;박명수;고형종;김경훈
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 1999년도 추계 학술대회논문집
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    • pp.152-157
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    • 1999
  • For the simulation of the blood flow in coronary artery, the system modeling of coronary hemodynamics is combined with CFD technique. The blood flow in coronary artery interacts with the global coronary circulation. Especially in case of the coronary artery with stenosis, the interaction plays an important role in the hemodynamics of the circulation. In this study we present a combined numerical approach using both the CFD technique for flow simulation and the global system model of coronary circulation. We use a lumped parameter model for the global simulation of coronary circulation whereas the finite element method is employed to compute the viscous flow field in stenosed coronary artery, The time variation of the pressure drop due to stenosis is obtained from the proposed numerical method. Numerical results shows that the flow resistance and pressure drop due to stenosis has a relatively large value in systole.

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Numerical investigations on the effect of tortuosity on friction factor in superconducting CICC configuration

  • Vaghela, Hitensinh;Lakhera, Vikas;Bhatt, Kunal;Sarkar, Biswanath
    • 한국초전도ㆍ저온공학회논문지
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    • 제23권4호
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    • pp.49-55
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    • 2021
  • The Cable in Conduit Conductor (CICC) configurations are designed, tested and realized to make high field superconducting (SC) magnets. The evolution of CICC design makes it challenging to forecast thermo-hydraulic behavior. A common objective of thermo-hydraulic studies is to obtain the most reliable predictive correlation for friction factor in CICC geometries and to reduce the dependency on the experiment. So far, only the void fraction and Reynolds number have been considered in the predictive correlations in an explicit way. In the present paper, the CICC twisting pattern dependency, called tortuosity (τ), on the pressure drop prediction, has been assessed through a numerical simulation approach. The CICC twisting pattern with 6+1 petals (solid conductor in the present study) with different twisting pitches is mimicked in the numerical simulation for the range 100 ≤ Re ≤10000 and 1 < τ < 1.08 and a correlation for friction factor, f, has been proposed as a function of Re and τ.

냉각유동에 의한 SMART 핵연료집합체의 압력강하변화 및 구조특성 (Pressure Drop Variations and Structural Characteristics of SMART Nuclear Fuel Assembly Caused by Coolant Flow)

  • 김해란;이영신;이현승;박남규
    • 대한기계학회논문집A
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    • 제36권12호
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    • pp.1653-1661
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    • 2012
  • 본 논문에서는 냉각유동에 의한 SMART 핵연료집합체의 압력강하변화 및 구조특성을 연구하였다. 난류 모델인 BSL 레이놀즈 응력 모델로서 냉각수의 유동을 모델링하여 유체고체연계 해석을 수행하였다. 우선, 지지격자체에 지지된 핵연료봉의 진동해석을 수행하여 실험 결과와 비교하였는데 실험에서의 고유진동수는 48 Hz 로서 시뮬레이션 값과 2% 의 오차를 발생하였다. 핵연료집합체의 압력강하는 한국원자력연구원에서 수행한 실험적 값과 비교하여 8%의 오차가 발생하였고 해석의 타당성을 증명하였다. 유체해석에서는 집합체를 통과하는 각 구간의 유체 속도와 이차유동에 의한 와류생성과정을 관찰하였다. 마지막으로 진동해석과 유체해석의 연계를 통하여 유체유발진동에 의한 연료봉의 변위 값을 관찰하고 최대 변위가 발생하는 곳의 변위 PSD 를 계산하였다.

R-22 대체용 혼합냉매의 Drop-In 열역학적 성능 계산 (Drop-In Evaluation of Thermodynamic Performance of R-22 Alternative Refrigerant Mixtures)

  • 주종문;김창년;박영무
    • 설비공학논문집
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    • 제8권3호
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    • pp.423-436
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    • 1996
  • Thermodynamic performance of eight zeotropic R-22 alternative refrigerant mixtures selected by AREP(R-22 Alternative Refrigerants Evaluation Program) and R-32/R-125/R-134a(23%/25%/52%), namely R-407C were evaluated by the "drop-in" simulation method. An existing air conditioner was selected and its design data were used for the simulation. "ARI Test A" air conditions were applied. The degree of vapor superheat at the compressor inlet fixed at $5^{\circ}C$ for all the mixtures. The results of the simulation were compared with those of R-22. COPs of all mixtures except for R-32/R-227ea(35%/65%) and R-32/R-125/R-134a(10%/70%/20%), were higher than that of R-22 by 2%~8%, while the capacities were all lower than that of R-22 by 13%~27%. COP of R-32/R-134a(40%/60%) was 2.4% higher but the capacity was 15% lower than those of R-22. In the case of R-32/R-134a(30%/70%), COP and capacity were 5.5% higher and 15% lower than those of R-22, respectively. Among the ternary mixtures, R-407C and R-32/R-125/R-134a(30%/10%/60%) showed the best performance. COP of R-407C was 2.4% higher than those of R-22 but the capacity was 15% lower.

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AT급전방식에서 AT간격에 따른 전압강하 및 대지누설전류에 대한 연구 (A Study on the Voltage Drop and Earth Leakage Current according to Interval of AT in the AT Feeding Method)

  • 김민석;최승혁;이종우
    • 전기학회논문지
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    • 제60권9호
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    • pp.1708-1714
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    • 2011
  • AT feeding system of the electric railway system is installed every about 10km at between the feeder and catenary in parallel and the mid-point of the transformer is connected to the rail The supply voltage of this system is doubled than rolling stock voltage. So the voltage drop is smaller than usual. And the other merit of this system is the decreasing inductive disturbance to the communication line because of the reduced current in rail which runs reversed in a point of view of rolling stock. Also, ATP(Auto Transformer Post) is installed to reduce the voltage drop and to mitigate the inductive disturbance, but still now the proper distance between the ATP and AT feeding system is not established which ranges from 2 to 10[km]. The stable result of simulation(which is set that the end of the line AT is installed) to the voltage drop and inductive disturbance can not analyzes the effect to the supply system due to the ATP. This paper analyzes the effect to the system depending on the location of ATP by forecasting the voltage drop and inductive disturbance.

A computational framework for drop time assessment of a control element assembly under fuel assembly deformations with fluid-structure interaction and frictional contact

  • Dae-Guen Lim;Gil-Yong Lee;Nam-Gyu Park;Yong-Hwa Park
    • Nuclear Engineering and Technology
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    • 제56권8호
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    • pp.3450-3462
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    • 2024
  • This paper presents a computational framework for drop time assessment of a control element assembly (CEA) under fuel assembly (FA) deformations. The proposed framework consists of three key components: 1) finite element modeling of CEA, 2) fluid-structure interaction to compute drag force, and 3) modeling of frictional contact between CEA and FA. Specially, to accommodate the large motion of CEA, beam elements based on absolute nodal coordinate formulation (ANCF) are adopted. The continuity equation is utilized to calculate the drag force, considering flow changes in the cross-sectional area during the CEA drop. Lastly, beam-inside-beam frictional contact model is employed to capture practical contact conditions between CEA and FA. The proposed framework is validated through experiments under two scenarios: free falls of CEA within FA, encompassing undeformed and deformed scenarios. The experimental validation of the framework demonstrated that the drop time of CEA can be accurately predicted under the complex coupling effects of fluid and frictional contact. The drop times of the S-shaped deformation case is longer than those of the C-shaped deformation case, affirming the time delay due to frictional force. The validation confirms the potential applicability to access the safety and reliability of nuclear power plants under extreme conditions.

IGBT 순방향 전압강하의 계산 (Calculation of Forward Voltage Drop of IGBTs)

  • 최병성;정상구
    • 대한전기학회논문지:전기물성ㆍ응용부문C
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    • 제49권3호
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    • pp.161-164
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    • 2000
  • A simple methode for calculating the forward voltage drop of IGBTs is presented, on the voltage drops on the p+ body, the reverse biased depletion region between p+body and epi-layer, the epi layer, and the forward biased collector junction. The decrease of the total current density in the epi layer near the p+ body is taken into account. The proposed methode allows a simple but accurate determination of the forward voltage drop in IGBTs, avoiding the complex path taken in the previous model for the forward voltage drops on channel, accumulation region, and epi region. Numerical simulations for 1kV NPT-IGBT with a uniformly doped collector are shown to support the analytical results.

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