• Title/Summary/Keyword: Opening Load

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Adjustment of Valve Opening in Ondol Hot Water Distributor (온돌 난방분배기의 개도조정)

  • Hong, Hi-Ki;Kim, Si-Hwan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.7
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    • pp.460-467
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    • 2010
  • In housing units constructed recently in Korea, the length of ondol coil is different in each room, so the flow rate of hot water is adjusted by setting valve opening. If the flow rate is not appropriate for heating load, the room temperature seriously deviates from the set temperature range for comfort. In particular, too small valve opening can induce a noise by cavitation. In order to adjust the valve opening, two methods by zone area and a new method by return temperature rise were modelled and simulated using TRNSYS and EES. As a result, heating energy consumption during one week was the same on three methods, but the room temperature of the new method minimally deviated from the range of set temperature with a low possibility of noise.

Experimental Study for the Development of New Type Water Ejector (신형 수이젝터 개발을 위한 실험연구)

  • Mun, Soo-Bum;Choi, Hyun-Kue;Choi, Jae-Hyuk;Kwon, Hyung-Jung;Kim, Kyung-Keun;Choi, Soon-Ho
    • Journal of Advanced Marine Engineering and Technology
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    • v.30 no.6
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    • pp.677-684
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    • 2006
  • An ejector is a fluid transfer device to be used for mixing of fluids, maintaining vacuum, and overcoming a poor suction condition. To date, most ejectors have been made from the casting process. which is time-consuming and high-cost process. Therefore, a new production method of ejectors is desired if any. In this experimental study, we proposed a new type ejector manufactured from the commercial fitting materials and the welding process, which is equipped with an orifice type nozzle. The proposed ejector has a good integrity compared with the conventional ejector because the fittings have manufactured by forging and they have more strength than the casting materials. Furthermore we adopted a multi-opening orifice type nozzle for improving a suction capacity and compared with a single-opening orifice type nozzle. From the experimental results. we confirmed that the multi-opening nozzle had a food suction capacity than the single-opening nozzle and the proposed new type ejector showed higher vacuum than the conventional type ejector in non-load condition. These improved characteristics suggests that a new type ejector by using the commercial fittings opens the feasibility to be adopted in various industry fields and that the increased suction capacity can be achieved by altering the nozzle design of a conventional ejector.

Effect of the Intake Valve Opening Timings and Fuel Injection Pressures on the Exhaust Emission Characteristics of a Gasoline Engine at Part Load Condition

  • Lee, Hyung-Min;Jeong, Yeon-Hwan
    • Journal of Advanced Marine Engineering and Technology
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    • v.35 no.3
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    • pp.317-322
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    • 2011
  • This work has investigated the exhaust emissions such as Total Hydrocarbon (THC), Nitrogen Oxides(NOx), and Particulate Matter (PM) characteristics emitted from the tail-pipe of a continuously variable valve timing (CVVT) gasoline-fueled engine with different intake valve opening timings and injection pressures at the part load condition. Valve overlap period was varied from $40^{\circ}CA$ to $10^{\circ}CA$ and fuel injection pressure was increased from 3.5 bar to 5.0 bar. THC and NOx emissions decreased as intake valve opening timing was advanced regardless of fuel injection pressure. When the fuel was injected with the condition of 5.0 bar at all of valve overlap ranges, THC levels were reduced by 55%. NOx concentrations were diminished about 75% as valve overlap increased. PM size distributions were analyzed as bi-modal type of the nucleation and accumulation mode. Comparing with fuel injection pressures, PM emission levels were decreased at high pressure injection of 5.0 bar condition.

Buckling and post-buckling behaviors of 1/3 composite cylindrical shell with an opening

  • Ma, Yihao;Cheng, Xiaoquan;Wang, Zhaodi;Guo, Xin;Zhang, Jie;Xu, Yahong
    • Steel and Composite Structures
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    • v.27 no.5
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    • pp.555-566
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    • 2018
  • A 1/3 composite cylindrical shell with a central rectangular opening was axially compressed experimentally, and its critical buckling load and displacement, and strains were measured. A finite element model (FEM) of the shell with Hashin failure criteria was established to analyze its buckling and post-buckling behaviors by nonlinear Newton-Raphson method. The geometric imperfection sensitivity and the effect of side supported conditions of the shell were investigated. It was found that the Newton-Raphson method can be used to analyze the buckling and post-buckling behaviors of the shell. The shell is not sensitive to initial geometric imperfection. And the support design of the shell by side stiffeners is a good way to obtain the critical buckling load and simplify the experimental fixture.

Fatigue reliability analysis of steel bridge welding member by fracture mechanics method

  • Park, Yeon-Soo;Han, Suk-Yeol;Suh, Byoung-Chul
    • Structural Engineering and Mechanics
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    • v.19 no.3
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    • pp.347-359
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    • 2005
  • This paper attempts to develop the analytical model of estimating the fatigue damage using a linear elastic fracture mechanics method. The stress history on a welding member, when a truck passed over a bridge, was defined as a block loading and the crack closure theory was used. These theories explain the influence of a load on a structure. This study undertook an analysis of the stress range frequency considering both dead load stress and crack opening stress. A probability method applied to stress range frequency distribution and the probability distribution parameters of it was obtained by Maximum likelihood Method and Determinant. Monte Carlo Simulation which generates a probability variants (stress range) output failure block loadings. The probability distribution of failure block loadings was acquired by Maximum likelihood Method and Determinant. This can calculate the fatigue reliability preventing the fatigue failure of a welding member. The failure block loading divided by the average daily truck traffic is a predictive remaining life by a day. Fatigue reliability analysis was carried out for the welding member of the bottom flange of a cross beam and the vertical stiffener of a steel box bridge by the proposed model. Results showed that the primary factor effecting failure time was crack opening stress. It was important to decide the crack opening stress for using the proposed model. Also according to the 50% reliability and 90%, 99.9% failure times were indicated.

Shear resistance of corrugated web steel beams with circular web openings: Test and machine learning-based prediction

  • Yan-Wen Li;Guo-Qiang Li;Lei Xiao;Michael C.H. Yam;Jing-Zhou Zhang
    • Steel and Composite Structures
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    • v.47 no.1
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    • pp.103-117
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    • 2023
  • This paper presents an investigation on the shear resistance of corrugated web steel beams (CWBs) with a circular web opening. A total of five specimens with different diameters of web openings were designed and tested with vertical load applied on the top flange at mid-span. The ultimate strengths, failure modes, and load versus middle displacement curves were obtained from the tests. Following the tests, numerical models of the CWBs were developed and validated against the test results. The influence of the web plate thickness, steel grade, opening diameter, and location on the shear strength of the CWBs was extensively investigated. An XGBoost machine learning model for shear resistance prediction was trained based on 256 CWB samples. The XGBoost model with optimal hyperparameters showed excellent accuracy and exceeded the accuracy of the available design equations. The effects of geometric parameters and material properties on the shear resistance were evaluated using the SHAP method.

Hydraulic Performance Characteristics of Kaplan Turbine (카프란수차의 수력학적 성능특성)

  • Lee C. H.;Park W. S.
    • 한국신재생에너지학회:학술대회논문집
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    • 2005.06a
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    • pp.443-446
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    • 2005
  • The Kaplan turbine model has been tested and analyzed. The blade angle and the guide vane opening of the turbine model were designed to be varied according to the best combination of guide vane and runner blade opening. When the changes in head and output were comparatively large, the efficiency drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed model in this study will be suitable for small hydro power stations with large changes in head and load.

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Development of Kaplan Type Turbine for Low Head Hydro Resources (저낙차 수자원활용을 위한 카프란수차 개발)

  • Lee, Chul-Hyung;Park, Wan-Soon
    • Proceedings of the Korea Water Resources Association Conference
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    • 2007.05a
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    • pp.1992-1996
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    • 2007
  • The Kaplan turbine model has been tested and analized. The blade angle and the guide vane opening of the turbine model were designed to be varied according to the best combination of guide vane and runner blade opening. When the changes in head and output were comparatively large, the efficincy drop were small, so the efficiency characteristics and stability of the entire operating condition were maintained in good condition. These results showed that the developed model in this study will be suitable for small hydro power stations with large changes in head and load.

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New Engineering J and COD Estimation Method for Circumferential Through-Wall Cracked Pipes-Combined Tension and Bending Load (원주방향 관통균열이 존재하는 배관의 새로운 J-적분 및 COD 계산식-인장하중과 굽힘모멘트가 동시에 작용하는 경우)

  • Huh, Nam-Su;Kim, Yun-Jae;Kim, Young-Jin
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.7
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    • pp.85-90
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    • 2001
  • In order to apply the Leak-Before-Break(LBB)concept to nuclear piping, accurate estimation of J-integral and crack opening displacement(COD) is essential for complex loading, such as combined tension and bending. This paper proposes a new engineering method to estimate J-integral and the COD for circumferential through-wall cracked pipes subject to combined tension and bending loading. The proposed method to estimate the COD is validated against three published pipe test data, generated from a monotonically increasing bending load with a constant internal pressure, which shows excellent agreements.

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Structural Analysis on Durability of Forklift due to Opening and Closing Between Forks (개폐에 따른 지게차 포크의 내구성에 대한 구조해석)

  • Cho, Jaeung;Han, Moonsik
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.22 no.2
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    • pp.199-205
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    • 2013
  • Stress and deformation on forklift happened at loading, unloading or moving freight are studied by structural and fatigue analysis in this study. As model 1 as closing type between forks has lower stress and stain than model 2 at opening type, model 1 has more durability than model 2. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'SAE bracket history' with the severest change of load at model 1 and 2, maximum life is shown with Cycle. Minimum damage with 854 at model 2 becomes much higher than model 1. As the gap between forks becomes open, the damage probability becomes higher. The structural result of this study can be effectively utilized with the safe and stable design of forklift by investigating prevention and durability against its damage.