• Journal of the Korean Society of Safety
• /
• v.12 no.1
• /
• pp.122-128
• /
• 1997

A new approach, called "two-phase approach", has been proposed In this study. Using this approach to solve MONLP(multiobjective nonlinear programming problem), the solution process is divied into two phase. In the first phase, the min-operator is used to aggregate the membership degree of fuzzy goals and constraints. In the second phase, the $\gamma$-operator is used to test and find an efficient solution in the sense of nondominated. It has been shown that no matter what the solution of the problem is unique or not, an efficient solution can be always obtained at the second phase. The proposed approach can be applied to industrial safety problem with multiobjective problems. On the basis of proposed approach, an illustrative numerical example is presented.presented.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.88-91
• /
• 2004

The multiphase flow simulator, MPS, is developed based on the fractional flow approach considering tile fully three phase flow with general initial and boundary condition. Most existing fractional flow-based models are limited to two-phase flow and specific boundary conditions. Although there appears a number of three-phase flow models, they were mostly developed using pressure based approaches. As a result, these models require cumbersome variable-switch techniques to deal with phase appearance and disappearance. The use of fractional flow based approach in MPS makes it unnecessary to use variable-switch to handle the change of phase configurations. Also most existing fractional flow based models consider only specific boundary conditions. However, the present model considers general boundary conditions of most possible and plausible cases which consists of ten cases.

• Journal of Ocean Engineering and Technology
• /
• v.37 no.3
• /
• pp.122-128
• /
• 2023

Autonomous berthing is a crucial technology for autonomous ships, requiring optimal trajectory planning to prevent collisions and minimize time and control efforts. This paper presents a two-phase, two-point boundary value problem (TPBVP) strategy for creating an optimal berthing trajectory for a twin-propeller, twin-rudder ship with autonomous berthing capabilities. The process is divided into two phases: the approach and the terminal. Tunnel thruster use is limited during the approach but fully employed during the terminal phase. This strategy permits concurrent optimization of the total trajectory duration, individual phase trajectories, and phase transition time. The efficacy of the proposed method is validated through two simulations. The first explores a scenario with phase transition, and the second generates a trajectory relying solely on the approach phase. The results affirm our algorithm's effectiveness in deciding transition necessity, identifying optimal transition timing, and optimizing the trajectory accordingly. The proposed two-phase TPBVP approach holds significant implications for advancements in autonomous ship navigation, enhancing safety and efficiency in berthing operations.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2005.05a
• /
• pp.295-298
• /
• 2005

High temperature deformation behavior of $\alpha\;and\;\beta$ phase of Ti-6Al-4V was investigated within the framework of a self-consistent approach at various temperature ranges. To examine the flow behavior of u-phase, Ti-7.0Al-1.5V alloy was used, whose chemical composition is close to that of the $\alpha$ phase in Ti-6Al-4V at hot working temperatures. The flow stress of $\beta$ phase was predicted by using self-consistent approach. The flow stress of $\alpha$ phase was higher than that of $\beta$ phase above $750^{\circ}C$, while the $\beta$ phase revealed higher flow stress than a phase at $650^{\circ}C$. It was found that the relative strength and strain rate ratio between $\alpha\;and\;\beta$ phase significantly varied with temperature. From this approach, the mode for grain matrix deformation was proposed as a mixed type of both iso-stress and iso-strain rate modes.

• Korean Management Science Review
• /
• v.24 no.1
• /
• pp.91-111
• /
• 2007

In this paper an effective two-phase approach adopting modified p-median mathematical model is proposed for grouping machines and parts in cellular manufacturing(CM). Unlike the conventional methods allowing machines and parts to be improperly assigned to cells and families, the proposed approach seeks to find the proper block diagonal solution where all the machines and parts are properly assigned to their most associated cells and families in term of the actual machine processing and part moves. Phase 1 uses the modified p-median formulation adopting new inter-machine similarity coefficient based on the non-binary production data-based part-machine incidence matrix(PMIM) that reflects both the operation sequences and production volumes for the parts to find machine cells. Phase 2 apollos iterative reassignment procedure to minimize inter-cell part moves and maximize within-cell machine utilization by reassigning improperly assigned machines and parts to their most associated cells and families. Computational experience with the data sets available on literature shows the proposed approach yields good-quality proper block diagonal solution.

• Journal of the Korean Society of Physical Medicine
• /
• v.4 no.3
• /
• pp.193-200
• /
• 2009

Purpose：In this study is to verify the effects postural control training based on Bobath approach for body schema and visual perception on Middle Cerebral Artery(MCA) Infarcts. Methods：The subject was a 46 years old man with MCA infaction, lives in B city. An AB design for a single-subject research was used for this study. The procedures consisted of 1 time of baseline phase(A), 20 times of treatment phase(B). We applied the Bobath approach at the subject. Treatments included to facilitate trunk alignment and stability, and to train weight bearing and shifting, to facilitate pelvis movement, and to train walk especially stance phase and assist up-down stairs locomotion in environment similar to actual daily life. Results：With this treatment, the majority of body schema and visual perception and postural control was improved in treatment phase compared with in baseline phase. Therefore, this study supported the effectiveness of postural control training based on Bobath approach for body sechma and visual perception of hemiplegia. Conculusion：This study is integrated postural control training with Bobath approach that are widespread for hemiplegia and measured outcomes based on individualized therapy goals. Consequently the study is suggested the meaning of quality effectiveness of Bobath approach.

• International Journal of Fuzzy Logic and Intelligent Systems
• /
• v.6 no.3
• /
• pp.232-239
• /
• 2006

This paper is for applying interactive fuzzy linear programming for the problem of product mix planning, which is one of the aggregate planning problem. We developed a modified algorithm, which has two-phase approach for interactive fuzzy linear programming to get a better solution. Adding two-phase method, we expect to obtain not only the highest membership degree, but also a better utilization of each constrained resource.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 2002.05a
• /
• pp.1044-1051
• /
• 2002

This paper proposes a two-phase mathematical programming approach by considering classification gap to solve the proposed credit scoring problem so as to complement any theoretical shortcomings. Specifically, by using the linear programming (LP) approach, phase 1 is to make the associated decisions such as issuing grant of credit or denial of credit to applicants. or to seek any additional information before making the final decision. Phase 2 is to find a cut-off value, which minimizes any misclassification penalty (cost) to be incurred due to granting credit to 'bad' loan applicant or denying credit to 'good' loan applicant by using the mixed-integer programming (MIP) approach. This approach is expected to and appropriate classification scores and a cut-off value with respect to deviation and misclassification cost, respectively. Statistical discriminant analysis methods have been commonly considered to deal with classification problems for credit scoring. In recent years, much theoretical research has focused on the application of mathematical programming techniques to the discriminant problems. It has been reported that mathematical programming techniques could outperform statistical discriminant techniques in some applications, while mathematical programming techniques may suffer from some theoretical shortcomings. The performance of the proposed two-phase approach is evaluated in this paper with line data and loan applicants data, by comparing with three other approaches including Fisher's linear discriminant function, logistic regression and some other existing mathematical programming approaches, which are considered as the performance benchmarks. The evaluation results show that the proposed two-phase mathematical programming approach outperforms the aforementioned statistical approaches. In some cases, two-phase mathematical programming approach marginally outperforms both the statistical approaches and the other existing mathematical programming approaches.

• Proceedings of the ESK Conference
• /
• 1997.10a
• /
• pp.313-319
• /
• 1997

There is currently a focus on usability of interactive computer software. Previous research in software ergonomics has indicated the importance of evaluating the usability of software user interfaces. Software developers, interface designers or human foctors engineers often confront the task of comparative evaluation among systems, versions or interface designs. This study presents a structured model for comparative evaluation of user interface designs using usability criteria and measures. The proposed model consists of twomain phases : the prescreening phase ad the evaluation phase. The first phase involves expert judgment-based approach with qualitative criteria. The prescreening phase uses absolute measurement analytic hierarchy process to filter possible altermative interfaces to a reasonable subset. The second phase involves user-based approach such as usability testing, with quantitative criteria. The objective of the evaluation phase is to evaluate a subset of altermatives using objective measures. A set of criteria and measures for evaluating the usability of computer software designs is presented. The proposed model provides practitioners with a structured approach to select the best interface based on usability criteria and measures.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.23 no.6
• /
• pp.579-592
• /
• 2010

This paper presents a multi-phase model update approach for system identification of prestressed concrete (PSC) girders under various prestress forces. First, a multi-phase model update approach designed on the basis of eigenvalue sensitivity concept is newly proposed. Next, the proposed multi-phase approach is evaluated from controlled experiments on a lab-scale PSC girder for which forced vibration tests are performed for a series of prestress forces. On the PSC girder, a few natural frequencies and mode shapes are experimentally measured for the various prestress forces. The corresponding modal parameters are numerically calculated from a three-dimensional finite element (FE) model which is established for the target PSC girder. Eigenvalue sensitivities are analyzed for potential model-updating parameters of the FE model. Then, structural subsystems are identified phase-by-phase using the proposed model update procedure. Based on model update results, the relationship between prestress forces and model-updating parameters is analyzed to evaluate the influence of prestress forces on structural subsystems.