• Journal of Advanced Marine Engineering and Technology
• /
• v.22 no.1
• /
• pp.77-84
• /
• 1998

Based on experimental analysis, the characteristics of pulsating pressure wave propagation is clarified by testing of 4-stroke gasoline engine. The pulsating pressure wave in exhaust system is generated by pulsating gas flow due to working of exhaust valve. The pulsating pressure wave is closely concerned to the loss of engine power according to back pressure and exhaust noise. It is difficult to exactly calculate pulsating pressure wave propagation in exhaust system because of nonlinear effect. Therefore, in the first step for solving these problems, this paper contains experimental model and analysis method which are applied two-port network analysis. Also, it shows coherence function, frequency response function, back pressure, and gradient of temperature in exhaust system.

• Journal of Korean Society on Water Environment
• /
• v.20 no.6
• /
• pp.676-684
• /
• 2004

Many researchers have been carrying on study to figure out the exact collision efficiency between bubble and floc. Collision efficiency can has generally been quantified by using trajectory analysis which uses the hydrodynamic, the electrostatic and van der waals forces. Two types of method are considered to induce the hydrodynamic force in the trajectory analysis. One is to use stream function and the other is to use mobility function. There was some difference between stream and mobility function depending upon modelling factors and conditions in trajectory analysis.

• Proceedings of the KIEE Conference
• /
• 1996.11a
• /
• pp.77-79
• /
• 1996

This paper presents an integrated stability analysis by the direct energy function method based on Equivalent Mechanical Model(EMM) which reflects the system behavior related to both angle and voltage stabilities. Actually, angle and voltage stability are intimately related in power system, so complete decoupling of these stability analysis is not possible in general, particularly in stressed power systems. In this paper, it is shown that a identical energy function can be used for angle and voltage stability analysis. The proposed energy function reflects the line resistances and reactive powers under the constraints of the same R/X ratio. The energy margin between UEP and SEP presents a good collapse proximity index in both types of stability analysis.

• Korean Journal of Construction Engineering and Management
• /
• v.12 no.5
• /
• pp.12-22
• /
• 2011

Design value engineering (VE) has been performed in many construction projects according to the changes in the construction for most of the VB function analysis that performed, are problems that focus on function analysis and generating ideas based on individual experience of VE team member than generating ideas and value improvement of systematic function analysis. This may be due to the quotation of previously performed function analysis data, general function analysis, and abstract function definitions that do not cite the concrete characteristics of each facility. Therefore, in this study, the proposed cases from the existing design VE workshops, the current conditions of the connection between functions and ideas and of the idea categorization by building part were studied to determine why functions and ideas are not connected, and to propose pertinent improvement directions. on a performance-based function categorization system by building part that can provide the logical connection between functions and ideas in the function definition/categorization and function arrangement phases in the function analysis phase, the most important phase in VE activities, was developed by reflecting the required performance and functions for each part of the facility.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.4
• /
• pp.279-289
• /
• 2017

This paper presents some of the methods used to incorporate the parts constituting a product. A new relation function concept and its structure are introduced to analyze the relationships of component parts. This relation function has three types of information, which can be used to establish a relation function structure. The relation function structure of the analysis criteria was established to analyze and present the data. The priority components determined by the analysis criteria can be integrated. The analysis criteria were divided based on their number and orientation, as well as their direct or indirect characteristic feature. This paper presents a design algorithm for component integration. This algorithm was applied to actual products, and the components inside the product were integrated. Therefore, the proposed algorithm was used to conduct research to improve the brake discs for bicycles. As a result, an improved product similar to the related function structure was actually created.

• The Journal of the Acoustical Society of Korea
• /
• v.35 no.2
• /
• pp.118-124
• /
• 2016

In this paper, contribution analysis method using a partial coherence function is dealt with in the case of underwater radiation noise. When performing the contribution analysis using a partial coherence function, it is important to select the order of system input. But in the case of frequency correlated systems, it is very difficult to properly select the order of system input. In order to solve this problem, the contribution analysis is performed by subdividing the area of contribution using multiple coherence function. And the new contribution analysis method is presented by using the relationship between the contribution characteristic matrix and multiple coherence function. In order to validate the new method, calculation is performed about multi-input / single-output model which is composed of sine waves. The result of calculation shows that it is possible to derive the exact contribution values.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.38 no.2
• /
• pp.75-86
• /
• 1996

The formulas for estimating the constants of storage function model including K and TL for runoff analysis and a distributed storage function model are discussed in this study. First, the relations between parameters of the storage function model and the kinematic runoff model are theoretically examined, and then optimum constants of storage function model are obtained by the Standardized Davidson-Fletcher-Powell (SDFP) method. Through this analysis, theoretical formulas were obtained as $K = 0.63 {\alpha} KsB{^0.6}$ and $T_{L}=0.11 {\alpha} KsB{^0.6} r{^0.4} {_e}$, which are difficult to use practically because of the unclarified definition of shape factors. From a practical point of view, empirical formula were derived as $K=15.6{^0.3} {_m}$ and $T_{L}=2.1B{^0.36} {_m} {_e}/r{^0.4} {_e}$ for applied watersheds. The proposed formulas are verified for several recoded floods at a few points of watersheds. It is also found that the distributed storage function. can be applied to flood runoff analysis using the new formulas aboved mentioned.

• Structural Engineering and Mechanics
• /
• v.86 no.3
• /
• pp.349-359
• /
• 2023

This paper presents a technique for determining the optimal number of elements in stochastic finite element analysis based on reliability analysis. Using the change-of-variable perturbation stochastic finite element approach, the probability density function of the dynamic responses of stochastic structures is explicitly determined. This method combines the perturbation stochastic finite element method with the change-of-variable technique into a united model. To further examine the relationships between the random fields, discretization of the random field parameters, such as the variance function and the scale of fluctuation, is also performed. Accordingly, the reliability index is calculated based on the explicit probability density function of responses with Gaussian or non-Gaussian random fields in any number of elements corresponding to the random field discretization. The numerical examples illustrate the effectiveness of the proposed method for a one-dimensional cantilever reinforced concrete column and a two-dimensional steel plate shear wall. The benefit of this method is that the probability density function of responses can be obtained explicitly without the use simulation techniques. Any type of random variable with any statistical distribution can be incorporated into the calculations, regardless of the restrictions imposed by the type of statistical distribution of random variables. Consequently, this method can be utilized as a suitable guideline for the efficient implementation of stochastic finite element analysis of structures, regardless of the statistical distribution of random variables.

• Journal of Korean Association for Spatial Structures
• /
• v.12 no.2
• /
• pp.55-63
• /
• 2012

This study is about earthquake-proof reinforcement through structural function evaluation of an school building. The purpose of this study is to comparatively analyze structure reinforcement measures in consideration of safety and usability through structural function evaluation of school buididng, to offer rational measures for earthquake-proof function and to provide help in maintaining safe structures against earthquake. For this purpose, was selected for this study as an existing school building, earthquake-proof function evaluation was conducted, and measures to reinforce earthquake-proof function was offered. As for the research method, the first and the second earthquake-proof function evaluations were conducted which is an existing reinforced concrete school building. Through the abovementioned methods, earthquake-proof function evaluation were conducted, the results were analyzed and the measure to reinforce earthquake-proof function were offered(Steel damper, Carbon plate stiffeners). The offered measure to reinforce earthquake-proof function was applied to the subject structure, and comprehensive results were derived from earthquake-proof function evaluation regarding before and after earthquake-proof function reinforcement.

• Convergence Security Journal
• /
• v.11 no.5
• /
• pp.21-29
• /
• 2011

This study is to investigate how security organizational mentoring type and mentoring function affects organizatio nal commitment. This study had selected security from 5 different security organizations of 2010 which are located i n capital area. Using judgment sampling method, 198 security were drawn for the final study. The survey used in th is study is composed of 37 questions. To practice frequency analysis, factorial analysis, reliability analysis and regre ssion, a program called SPSSWIN 18.0 was used. The value of Cronbach's ${\alpha}$, which shows the reliability of the stud y, appeared to be over .622. The result is: First, security organizational mentoring type affects mentoring function. T hat is, when a systematic mentoring is activated, friendship protecting function, career managing function and sociopsychological function are promoted. Second, security organizational mentoring type affects organizational commitmen t. That is, when a systematic mentoring is activated, organizational commitment is promoted. Third, security organiz ational mentoring function affects organizational commitment. That is, increased friendship protecting function, career managing function, socio-psychological function and role model function results in increased organizational commitment.