• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.336-340
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• 2014

The noise and vibration have been evaluated by using the finite element model in the vehicle developing stage. The sound pressure of the vehicle compartment is predicted by the acoustic cavity model coupled with the body structure. In general, the structural model has been focused to study in the improvement of the noise. It is not easy to treat the structural model, instead the acoustic cavity model is relatively simple and aids in root cause analysis of vibro-acoustic issues. Therefore, the acoustic transfer function of the cavity is more efficient for finding out the main contribution parts of the vehicle booming noise. And examples about the run-up booming noise demonstrate the validity of the AFT analysis for improving the vibro-acoustic sensitivity.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.6
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• pp.3-14
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• 2005

Accurate estimation of the spatial distribution of rainfall is critical to the successful modeling of hydrologic processes. The objective of this study is to evaluate the applicability of spatially distributed rainfall data. Spatially distributed rainfall was calculated using Kriging method and Thiessen method. The application of spatially distributed rainfall was appreciated to the runoff response from the watershed. The results showed that for each method the coefficient of determination for observed hydrograph was $0.92\~0.95$ and root mean square error was $9.78\~10.89$ CMS. Ordinary Kriging method showed more exact results than Simple Kriging, Universal Kriging and Thiessen method, based on comparison of observed and simulated hydrograph. The coefncient of determination for the observed peak flow was 0.9991 and runoff volume was 0.9982. The accuracy of rainfall-runoff prediction depends on the extent of spatial rainfall variability.

• Journal of the Society of Naval Architects of Korea
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• v.43 no.6 s.150
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• pp.683-692
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• 2006

The BEM, known as solving boundary value problems, could have some advantages In solving domain problems which are mostly solved by FEM and FDM. Lately, in the elastic-plastic nonlinear problems, BEM could provide the subdomain approach for the region where the plastic deformation could occur and the unknown nodal displacement of this region are added as the unknown of the boundary integral equation for this approach. In this paper, initial stress method was used to establish the formulation of such BEM approach. And a simple rectangular plate having a circular hole was analyzed to verify the suggested method and the result is compared with that from FEM. It is shown that the result of two methods are showing similar stress-strain curves at the root of perforated plate and furthermore the plastic deformation obtained by BEM shows more reasonable behavior than that of FEM.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1518-1523
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• 2008

Train collision and derailment are types of accident with low probability of occurrence, but they could lead to disastrous consequences including loss of lives and properties. The development of the risk assessment model has been called upon to predict and assess the risk for a long time. Nevertheless, the risk assessment model is recently introduced to the railway system in Korea. The classification of the hazardous events and causes is the commencement of the risk assessment model. In previous researches related to the classification, the hazardous events and causes were classified by centering the results. That classification was simple, but might not show the root cause of the hazardous events. This study has classified the train collision and derailment based on the relevant hazardous event including faults of the train related the accidents, and investigates the causes related to the hazardous events. For the risk assessment model, FTA (fault tree analysis) and ETA (event tree analysis) methods are introduced to assess the risk.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.303-311
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• 2005

The problem of conjugate laminar film condensation of the pure saturated vapor in forced flow over a flat plate has been investigated as boundary layer solutions. A simple and efficient numerical method is proposed for its solution. The interfacial temperature is obtained as a root of 3rd order polynomial for laminar film condensation, and it is presented as a function of the conjugate parameter. The momentum and energy balance equations are reduced to a nonlinear system of ordinary differential equations with four parameters: the Prandtl number, Pr, Jacob number, $Ja^{\ast}$, defined by an overall temperature difference, a property ratio R and the conjugate parameter ${\zeta}$. The approximate solutions thus obtained reveal the effects of the conjugate parameter.

• 연구논문집
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• s.33
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• pp.123-135
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• 2003

Using the residence time calculated by computer simulation for temperature and gas velocity distribution in CVC reactor, the kinetics on the formation of $TiO_2$ nano powder was analyzed for coagulation process, After abrupt increase of particle size at initial growth stage (< 0.2 $\mus$ ), the particle grew in proportion of cubic root to time. The numerically calculated particle sizes well agreed with the experimental results. However, the coarse rutile $TiO_2$ powders having the particle size of over 40 nm were formed on the surface of quratz rod in the reactor. it is thought that the fine anatase particles condensed on quratz rod were sintered in a heated CVC reactor to grow and transform to coarse rutile phase, and the critical size for phase transformation anstase-to-rutile was around 25 nm tn this study.

• Journal of Plant Biology
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• v.7 no.1
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• pp.11-14
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• 1964

Change of the amount of carbohydrates in relations with nitrogen metabolism was studied under the different manners of supply and with different sources of nitrogen. In barley plant supplied with nitrogen through root, the depression periods of glucose and sucrose content occurred at 2 days after, but the amounts of both sugars were different with the different sources of nitrogen; there were in sequence diminished by treatment of NO3, NH4 and urea. In sunflower leaves sprayed with urea both sugar contents were inversely related to the urea concentration sprayed, and depressing periods of the sugars appeared immediately in the N-deficient plant but late in the N-abundant one.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.263-270
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• 1995

The use of the shape memory alloy, Nitinol wire, is investigated as an actuator for enhancing the damping in structural vibration systems. The first-order mathematical model of the Nitinol wire is obtained from the experimental data for an actuator. Finite element method is utilized for the strain gage sensor model, which is installed at the root of cantilever beam. A simple system, cantilever beam, is built as a flexible structural system to implement a control law with the Nitinol wire actuator. The system model including sensor and actuator is derived, which agrees with the experimental results. The actuator dynamics is augmented with the system so as to design PI controller and the one of robust controllers, LQG/LTR controller, and the control laws are implemented experimentally. The experimental study shows the feasibility of utilizing the Nitinol wire as an actuator for the purpose of vibration control.

• Journal of Plant Biology
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• v.27 no.3
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• pp.149-162
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• 1984

Anatomical characters of the secondary xylem in roots of Lauraceae, including 6 genera and 13 species grown in Korea, were studied systematically. Lauraceors members studied anatomically possess characters of the secondary xylem that are in the main more specialized than those found in the primitive angiosperm families. The specialized characters are as follows; (1) mostly solitary pores with some radially multiples, (2) mostly simple perforation plates and partially scalariform perforation plates in all species, (3) slightly oblique end wall of vessel element, (4) predominantly alternate intervascular pitting, (5) paratracheal axial parenchyma in all species, (6) heterogeneous II or III vascular rays. It is considered that the series of specialization in this family from the perforation plates and angle of end wall to the vessel axis is as follows; MachiluslongrightarrowNeolitsealongrightarrowLinderalongrightarrowCinammomumlongrightarrowIozostelongrightarrowLitsea.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.226-234
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• 1998

The concept of dynamic tracking line is proposed as the feasible tracking region for a robot in a robot-conveyor system, which takes the conveyor speed into consideration. This paper presents an effective method to identify the dynamic tracking line in a robotic workcell. The maximum line speed of a robot is derived in an analytic form using the parameterized dynamics and kinematics of the manipulator, and some of its properties are established mathematically. The identification problem of the dynamic tracking line is then formulated as a root-solving problem for a single-variable equation, and solved by using a simple numerical technique. Finally, numerical examples are presented to demonstrate the methodology and its applications in workspace specification.