• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2011년도 춘계학술대회 논문집
• /
• pp.1074-1079
• /
• 2011

This paper describes the influence on the nonlinear critical speed results of a specific railway vehicle depending on various constraint conditions. In the roller-rig tests, proper constraints are inevitable to safely hold the test vehicles. Particularly, the test results using KRRI roller-rig are more sensitive to constraint conditions because it is a kind of semi-full car type. In this study, nonlinear critical speed of specific vehicle with regards to several constraint cases were predicted by computational analysis and these results were compared to find the suitable constraint conditions. And also the deviation of semi-full car model from actual full car model was investigated. According to the bifurcation analysis, the nonlinear critical speed are dependent with the constraint condition and car-body yaw motion should be free to achieve more accurate results. And the difference between semi-full and full car model was so small that KRRI's semi-full car model are valid as long as the stability is concerned.

• 대한기계학회논문집B
• /
• 제24권1호
• /
• pp.1-8
• /
• 2000

A modified low-Reynolds-number Reynolds stress model is developed for the calculation of drag-reducing turbulent flows induced by polymer injection. The results without polymer injection are compared with the results of direct numerical simulation to ensure the validity of the basic model. In case of drag reduction, profiles of mean velocity and Reynolds stress components, in two-dimensional channel flow, obtained with a proper value of viscosity ratio are presented and discussed. Computed mean velocity profile is in very good agreement with experimental data. And, the qualitative behavior of Reynolds stress components with the viscosity ratio is also reasonable.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
• /
• pp.1627-1632
• /
• 1991

A compact type LDPE autoclave reactor is analyzed with respect to the effects of the initiator feed concentration and the rate of heat transfer by employing the mixing-cell model with backflow. Singularity theory is applied for the single-cell model so that one can construct all the possible bifurcation diagrams. Since the single-cell model may not be adequate for the actual reactor, a two-cell model is also treated to predict the dynamic behavior of the reactor. As the rate of heat transfer increases, various multiplicity patterns and oscillatory motions are found. Apparently, the monomer conversion can be substantially increased with proper he-at removal and initiator supplement scheme. For this, however, the complex dynamic features accompanied must be taken into consideration in the reactor design.

• 천문학회지
• /
• 제25권1호
• /
• pp.1-9
• /
• 1992

We present new approach to analysis of velocity data of globular clusters. Maximum likelihood method is applied to get model parameters such as central potential, anisotropy radius, and total mass fractions in each mass class. This method can avoid problems in conventional binning method of chi-square. We utilize three velocity components, one from line of sight radial velocity and two from proper motion data. In our simplified scheme we adopt 3 mass-component model with unseen high mass stars, intermediate visible stars, and low mass dark remnants. Likelihood values are obtained for 124 stars in M13 for various model parameters. Our preferred model shows central potential of $W_o=7$ and anisotropy radius with 7 core radius. And it suggests non-negligible amount of unseen high mass stars and considerable amount of dark remnants in M13.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2006년도 학술발표회 논문집
• /
• pp.204-208
• /
• 2006

This study is to develop a distributed urban flood runoff model that simulates the road runoff and to test the applicability of the model by applying to Pyeongtaek city of $12.2km^2$. To generate the runoff along the runoff, agree burned DEM (Digital Elevation Model) with road networks was suggested and the proper spatial resolution of DEM was identified finer than 15 m. To test the model applicability, 32 points on the road networks were selected and the hydrographs of each point were generated. The test showed reasonable results that increase the road runoff from the high elevation roads to the low elevation roads and the road runoff considering rainwater drainage from the road also showed reasonable results.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 추계학술대회 논문집 전력기술부문
• /
• pp.74-76
• /
• 2008

The power expansion planning is large and capital intensive capacity planning. In the past the expansion planning was established with the proper supply reliability in order to minimize social cost. However, the planning not used cost minimizing objective function in the power markets with many market participants. This paper proposed the power expansion planning process in the power markets. This system is composed of Regulator and GENCO's model. Regulator model used multi-criteria decision making rule. GENCO model is very complex problem. Thus, this system transacted the part by several scenario assuming GENCO model.

• Journal of Electrical Engineering and Technology
• /
• 제6권6호
• /
• pp.760-768
• /
• 2011

The performance of transmission lines and its shielding design during a lightning phenomenon are quite essential in the maintenance of a reliable power supply to consumers. The leader progression model, as an advanced approach, has been recently developed to calculate the shielding failure rate (SFR) of transmission lines using geometrical data and physical behavior of upward and downward lightning leaders. However, such method is quite time consuming. In the present paper, an effective method that utilizes artificial neural networks (ANNs) to create a metamodel for calculating the SFR of a transmission line based on shielding angle and height is introduced. The results of investigations on a real case study reveal that, through proper selection of an ANN structure and good training, the ANN prediction is very close to the result of the detailed simulation, whereas the Processing time is by far lower than that of the detailed model.

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2001년도 추계학술발표논문집 (하)
• /
• pp.977-980
• /
• 2001

This paper is a study on the AC and PMI model for the defense computer network. It is suggested that the organization plan of PMI model is a proper model for the characteristics of military system and military defense network security demands based on defense PKI system. Futhermore, it will be presented both various types of defense AC and AC according to the role and clearance in PMI. Defense AC will provide strong users' authentication and Role Based Access Control to give more secured and trusted authentication service by using users' attribute such as role and clearance.

• 경영과학
• /
• 제20권2호
• /
• pp.135-149
• /
• 2003

Developing a proper program for customer evaluation is one of the most imminent tasks to implement CRM (Customer Relationship Management). Design of the Customer Value model is an important key to the customer evaluation progrgm. This paper proposes two models for estimating Customer Value. The first one is a Description Model for Customer Value based on customer CSI (Customer Satisfaction Index) data. This model represents as quantitative numbers what customers feel from the company or the service. The second one is a Prediction Model which employs factor analysis and regression to predict customer value. This paper exploits the two models to evaluate Customer Value as well as for customer behavior prediction.

• 경영과학
• /
• 제17권2호
• /
• pp.39-54
• /
• 2000

This paper presents a causal forecasting model using guided genetic algorithm in continuous manufacturing process. The guide genetic algorithm(GGA) is an extended genetic algorithm(GA) using penalty function and population diversity index to increase forecasting accuracy. GGA adds to the canonical GA the concept of a penalty function to avoid selecting the unproductive chromosomes and to make a proper searching direction. Also, GGA modifies the current population using the similarity of chromosomes to avoid falling into the trap of local optimal solution. For investigation GGA performance, we used a set of real data that was collected in local glass melting processes, and experimental results show the proposed model results in the better forecasting accuracy than linear regression model and canonical GA.