• Journal of IKEEE
• /
• v.20 no.2
• /
• pp.200-204
• /
• 2016

In this paper, we have estimated the performance of an overflow valve for EURO type CRDI(common rail direct injection) engine. In order to implement the overflow valve with friendly circumstance, it is necessity for considering spring load. Especially, the performance evaluation of diesel car with accuracy control will be considered a mileage improvement and circumstance regulation. In order to evaluate the performance of overflow valve, The leak test system checks the pressure, switching time and operating time under 3.0 bar below 100 cc, 3.3 bar among 150 cc and 200 cc, finally 4.0 bar upper 250 cc.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.5
• /
• pp.534-538
• /
• 1997

Some physiological characteristics and cultivar differences of winter barley to salt stress were studied during seedling stage. Salt stress was caused by adding NaCl solution to the pot culture soil. Measurements of the responses to salt stress and of the responses after relief from stress were done in terms of leaf water potential, chlorophyll and free proline contents, seedling height and seedling dry weight, and survival rate of leaves. Under salt stress ($\Psi_{\pi}$ =-20bar) seedling height and seedling weight were decreased by 2~22% and by 25~39% respectively, showing some differences among cultivars. Chlorophyll contents was decreased by 33~49%, and free proline content was remarkably increased from control 0.2~0.3mg to salt stress 9.6~14.7mg. The leaf water potential of seedling grown under salt stress with NaCl solution($\Psi_{\pi}$ =-10 or -20bar) was decreased from control -3.3bar to salt stress -9.0bar or -16.2bar respectively but there were no large differences among cultivars with time after relief from salt stress. Leaf survival rate was high in order of Baegdong, Milyang12, Olbori, Durubori and Hyangmaeg, and decrease rate of seedling dry weight was low in the order of Baegdong, Olbori, Hyangmaeg, Milyang12, Durubori. The increase in free proline contents was high in the order of Milyang12, Hyangmaeg, Baegdong, Durubori and Olbori.

• KCI Concrete Journal
• /
• v.13 no.2
• /
• pp.67-74
• /
• 2001

In this study, a numerical model for the simulation of reinforced concrete columns subject to cyclic loading is presented. The model consists of three separate models representing concrete, reinforcing steel bars and bond-slip between a reinforcing bar and ambient concrete. The concrete model is represented by the plane stress plastic-damage model and quadrilateral finite elements. The nonlinear steel bar model embedded in truss elements is used for longitudinal and transverse reinforcing bars. Bond-slip mechanism between a reinforcing bar and ambient concrete is discretized using connection elements in which the hysteretic bond-slip link model defines the bond stress and slip displacement relation. The three models are connected in finite element mesh to represent a reinforced concrete structure. From the numerical simulation, it is shown that the proposed model effectively and realistically represents the overall cyclic behavior of a reinforced concrete column. The present plastic-damage concrete model is observed to work appropriately with the steel bar and bond-slip link models in representing the complicated localization behavior.

• Journal of the Korean Society of Industry Convergence
• /
• v.9 no.1
• /
• pp.21-27
• /
• 2006

The laminar burning velocity was measured using a spherical combustion bomb with central ignition. Mixtures with equivalence ratio between 0.6 and 1.2, were tested. The computation was carried out for the burning velocity using premix code of Chemkin program under the unburned gas pressure of 0.5bar-30bar and temperature of 300K-700K at ${\Phi}1.0$. The results showed little difference between these two methods. The burning velocity was decreased by increasing the pressure and increased by increasing the temperature. The burning velocity was predicted by using the following equations $$S_L(m/s) = S_{st}(T/300)^{1.85}(P)^{-0.45}$$ $$(0.5bar{\leq}P{\leq}30bar,\;300K{\leq}T{\leq}700K)$$).

• Proceedings of the Korea Concrete Institute Conference
• /
• 1994.10a
• /
• pp.319-324
• /
• 1994

Bond test was carried out to assess the effect of several variables on bond characteristics between reinforcing bar and concrete. Key variables are concrete compressive strength(low, medium high, and ultra-high), bar diameter(13mm and 22mm), and concrete cover(25mm; 1-inch, 38mm; 1.5-inch, and 51mm; 2-inch). Confining effect and bar spacing are not taken into account. Thirty-two specimens subjected to uniaxial tension were tested under hypothesis uniform bond stress distribution along the reinforcing bar embeded in concrete. Test results(ultimate bond stress) were compared with bond and development provisions of the ACI building Code(ACl 318-89) and local bond stress versus slip relationship diagram represented to show effect of the above variables.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.05a
• /
• pp.510-513
• /
• 2004

The objectives of this research are to evaluate the effect of the compressive strength of concrete, reinforcing bar size, spacing of column transverse bars related to the concrete confinement effects on anchorage bond strength and bond behavior of beam-column joints subjected to cyclic loading and to predict the bond behavior of beam-column joints according to the variables by Finite Element Analysis appling the interface element between concrete and reinforced bar surface in a three-dimensional configuration. This paper shows that to verify the results by three-dimensional nonlinear finite element analysis appling a interface element, the test results that were already conducted are compared with analytic results. The behavior of bond and anchorage of beam bar is expressed by a local bond stress-slip relationship and the failure mode of bond is predicted by principal stress contour.

• Journal of Korean Society for Quality Management
• /
• v.31 no.2
• /
• pp.117-130
• /
• 2003

This paper investigates the economic design of synthetic control charts. The synthetic control chart has been proven to be statistically superior to the $\bar{X}$-control chart, but its economic characteristics have not been known. We develop an economic model of the synthetic control chart, based on Duncan's model. The synthetic chart has one more decision variable, the lower control limit for the conforming run length. In addition to this, the significance level and the power of the synthetic chart are more complicated than those of the $\bar{X}$-chart. These features make the optimization problem more difficult. We propose an optimization algorithm by adapting the congruent gradient algorithm. We compare the optimal cost of the synthetic chart with that of (equation omitted)-control chart, under the same input parameter set of Duncan’s. For all cases investigated, the synthetic chart shows superior to the $\bar{X}$-chart. The synthetic control chart is easy to implement, and it has better characteristics than the $\bar{X}$-chart in economical sense as well as in statistical sense, so it will be a good alternative to the traditional control charts.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.77-81
• /
• 2006

An attempt has been made to measure existing steel stress using magnetoelasticity. A device has been developed and used for the measurement of magnetism in response to the deformation of a steel bar. The proposed technique can be used for the assessment of existing reinforced concrete structures by the measurements of steel stress embedded inside concrete. A traditional technique requires to break the existing steel bar to measure existing strain. However, the proposed technique is developed to measure the stress without damaging the steel bar. A successful application of magnetoelasticity depends on the establishment of relationship between elastic and magnetic response due to loading. To investigate the correlation between the two, steel bars are loaded in tension under uniaxial loading while the magnetic reading is recorded. Based on the test results, equations are suggested to predict stress for steel bars with different diameters.

• Bulletin of the Korean Mathematical Society
• /
• v.57 no.3
• /
• pp.677-690
• /
• 2020

In this article, we study a reaction-diffusion system with homogeneous Dirichlet boundary conditions, which describing a three-species food chain model. Under some conditions, the predator-prey subsystem (u₁ ≡ 0) has a unique positive solution (${\bar{u_2}}$, ${\bar{u_3}}$). By using the birth rate of the prey r1 as a bifurcation parameter, a connected set of positive solutions of our system bifurcating from semi-trivial solution set (r₁, (0, ${\bar{u_2}}$, ${\bar{u_3}}$)) is obtained. Results are obtained by the use of degree theory in cones and sub and super solution techniques.

• Special Issue of the Society of Naval Architects of Korea
• /
• 2008.09a
• /
• pp.29-32
• /
• 2008

Hinged cross bar which is fitted for buyer's special item in cell guide of container vessels has an advantage of efficiency on container loading. In this paper, the main focus is to confirm the structural adequacy of hinged cross bar supporting structure in cell guide under the considered loading condition for container vessel.