• Korean System Dynamics Review
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• v.14 no.2
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• pp.31-53
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• 2013

This article deals with a Causal-Loop analysis of the characteristics of Ouroboros effects. The meaning of the effects is that solutions to problems are usually intended as final fixes, but more often than not, while solving one problem, they generate more problems. It means 'to worsen through attempts to make better.' The Ouroboros effects are very dangerous because they are regarded as a kind of self-destructive mechanisms. While existing researchers recognize the risks of the effects, they are not able to solve the systematic problem but only to describe the symptom. Such a way to deal with the effects results in difficulty to clarify the cause-and-effect relationship within the system. Thus the authors are focusing on explaining the effects by SD (System Dynamics), which are considered as the sole methodology to do effectively so far since SD is a great tool to discover structural causes. To solve the self-destructive problem of the effects, the authors analyze the characteristics of several cases of the effects in elaborating the CLD (Causal Loop Diagram) for each case. The analysis reveals the structural characteristics of the effects and how to correct them towards maintaining the sustainability of systems.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.106-113
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• 2004

Most of mechanical structures are composed of many substructures connected to one another by various types of mechanical joints. In automotive engineering, it is important to study these connected structures under various dynamic forces for the evaluations of fatigue life and stress concentration exactly. In this study, the dynamic response of vehicle structure to external forces is classified an inverse problem involving strains from the experiment and the analysis. The practical dynamic forces are determined by the combination of the analytical and experimental method with analyzed strain by quasi-static finite element analysis under unit force and with measured strain by a strain gage under driving load, respectively. In a stressed body, inter-molecular chemical bonds are failed beyond the certain magnitude. The failure of molecular structure in material is considered as a time process of which rate is determined by mechanical stress. That is, the failure of inter-molecular chemical bonds is the fatigue lift of material. This kinetic concept is expressed as lethargy coefficient. And S-N curve is obtained with the lethargy coefficient from quasi-static tensile test. Equivalent practical dynamic force is obtained from the identification of practical dynamic force for one loading point. Using the practical dynamic force and S-N curve, fatigue life of a window pillar is analyzed with FEM under the identified force by the procedure of above mentioned.

• Journal of Korean Port Research
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• v.7 no.1
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• pp.13-24
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• 1993

The rapid progress of the intermodal freight transportation in recent years has induced fierce competition among the adjacent hub ports for container transport. This brings increased attention to the evaluation of the port competitive ability. But it is not easy to evaluate the port competitive ability because this belongs to ill-defined system which is composed of ambiguous interacting attributes. Paying attention to this point, this paper deals the competitive ability of container port in Far-East Asia by fuzzy integral evaluation which is adequate to interacting ambiguous attribute problem. For this, the proposed fuzzy evaluation algorithm is applied to the real problem, based on the factors such as cargo volumes, costs, services, infrastructure and geographical sites These are extracted from the precedent study of port competitive ability, etc. The results show that the port evaluation factors come in following order ; services, costs, infrastructure, geographical sites and cargo volumes. There are some interactions(interaction coefficient, ${\lambda}=-0.664$ between evaluation attributes. The port competitive ability comes in following order : Singapore, Hongkong, Kobe, Kaoshiung and Busan. According to the sensitivity analysis, the rank between Busan and Kaoshiung changes when ${\lambda}=0.7$. From the analysis of the results, we confirmed that the proposed fuzzy evaluation algorithm is very effective in the complex-fuzzy problem which is composed of hierarchical structure with interacting attributes.

• Education of Primary School Mathematics
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• v.18 no.3
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• pp.203-216
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• 2015

This study analyzed changes of representations which had come up in the problem-solving process of math-gifted 6th grade students that ACODESA had been applied. The class was designed on a ACODESA procedure that enhancing the use of varied representations, and conducted for 40minutes, 4 times over the period. The recorded videos and interviews with the students were transcribed for analysing data. According to the result of the analysis, which adopted Despina's using type of representation, there appeared types of 'adding', 'elaborating', and 'reducing'. This study found that there is need for a class design that can make personal representations into that of public through small group discussions and confirmation in the problem-solving process.

• Structural Engineering and Mechanics
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• v.78 no.2
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• pp.135-143
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• 2021

In this study, continuous contact problem in the functionally graded (FG) layer loaded with a FG flat punch resting on the elastic semi-infinite plane was analyzed by the finite element method (FEM). It was assumed that the shear modulus and density of the layer and punch varied according to exponentially throughout their depth. FG layer's weight was included to the problem and additionally all surfaces were considered as frictionless. Analysis of FG materials was performed with a special macro which was added to the ANSYS program. Firstly, the shear modulus of the punch was considered to be very rigid and the results of initial separation load (λcr) and distance (xcr) were compared with the analytical solution. Afterwards, results obtained from the contact analysis made according to the inhomogeneity parameters (β, γ) between FG punch-FG layer which had been unprecedented in the literature were discussed. As a result, FG punch's stress values at the punch edges where stress accumulations occurred were found to be smaller than the rigid punch. The security of the structure, longer life of the material and ease of production are directly related to the reduction of the stress values. The results obtained in this study are important in this respect. Also this work is the first study that investigates the effect of FG punch on the FG layer.

• Korean Journal of Family Medicine
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• v.39 no.6
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• pp.360-363
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• 2018

Background: Acute alcoholic intoxication patients (AAIP) are a common public health problem. The aim of this study was to perform a comprehensive laboratory analysis for these patients to investigate the co-morbid medical problem. Methods: We retrospectively reviewed laboratory findings of AAIP who were transferred to the emergency department (ED) from January 2017 to June 2017. Results: A total of 160 male patients were enrolled. Sixteen patients (16/160, 10.0%) and three patients (3/160, 1.9%) had macrocytic anemia and microcytic anemia, respectively. A total of 33 patients (33/160, 20.6%) showed thrombocytopenia ($<150{\times}10^9/L$). Twelve patients (12/159, 7.5%) showed low serum albumin level (<3.5 g/dL). Three patients (3/160, 1.9%) had chronic kidney disease stages 3-4 based on estimated glomerular filtration rate. Six patients (6/27, 22.2%) had high hemoglobin A1c (HbA1c) level (>7.0%). Positive rates of hepatitis B surface antigen and antiHBs antibody (anti-HBs Ab) were 3.5% (5/141) and 49.0% (68/141), respectively. Conclusion: Patients with AAIP who were transferred to ED had various laboratory abnormalities (anemia, thrombocytopenia, high HbA1c). They had low positive rate of anti-HBs Ab. This might be a public health problem, suggesting the need of hepatitis B virus vaccination program for AAIP. Our data suggest the need of further nationwide studies.

• Steel and Composite Structures
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• v.30 no.1
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• pp.57-67
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• 2019

This paper deals with the static analysis of axially functionally graded rectangular plates. It is assumed that the flexural rigidity of the plate varies exponentially along one of the plate's in-plane dimensions. Both an analytical approach and a numerical method are utilized to solve the problem. The analytical solution is obtained by using the Green's function method. To employ this approach, the adjoint boundary value problem is established. Then, exact solutions for deflection of the plate for different boundary conditions are found. In another way, a finite element formulation for the problem is developed. In order to demonstrate the validity of the Authors' formulation, the results obtained via both mentioned schemes are compared with each other for functionally graded plates and with results of previously published works for homogeneous plates. The effect of plate parameters on the response of the plate is also investigated. To remind the research background, a brief review on the application of Green's function method in plates' analysis and functionally graded plates is also presented.

• Convergence Security Journal
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• v.18 no.4
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• pp.35-43
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• 2018

Currently, digital evidence takes judicial discretion in adopting it, which does not clarify the criteria for adoption, and it can shorten the analysis time of digital evidence with distributed processing techniques. However, due to the development of cryptographic techniques, there is a problem in that it is not suitable for the 48 hour limit of the warrant request. In this paper, we analyze the precedents for admissibility of evidence and the probative power in the civil/criminal proceedings, and discuss the need for objective and detailed adoption criteria to replace judicial discretion. In addition, we'd like to propose a preliminary application form for analysis of digital evidence as a problem for limit time for warrant claims from the perspective of forensics and a solution to the problem.

• The Journal of Asian Finance, Economics and Business
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• v.10 no.2
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• pp.313-320
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• 2023

In general, using information and communication technology (ICT) to support problem-solving is becoming increasingly common across various industries, sectors, and regions. However, there have been few analyses on the factors affecting ICT problem-solving among officers working at People's Committees of mountainous communes. Using survey data, exploratory factor analysis (EFA), and multivariable linear regression, this study examined the factors that influence the use of ICT in resolving works among community officers at People's Committees in the Northwest mountainous region of Vietnam. The results showed that three factors with statistical significance affecting the dependent variable are computer skills, gender, and occupation of community officers. Therefore, it is recommended that officers participate in ICT training courses or engage in regular self-study to improve their computer skills and qualifications. Both men and women should also prioritize the use of ICT equipment. The study also found that officers in managerial positions were more likely to use ICT for problem-solving than their counterparts. However, some factors that affect the use of ICT were not identified in this study, leaving room for further research.

• Nonlinear Functional Analysis and Applications
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• v.28 no.2
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• pp.497-520
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• 2023

Numerous problems in science and engineering defined by nonlinear functional equations can be solved by reducing them to an equivalent fixed point problem. Fixed point theory provides essential tools for solving problems arising in various branches of mathematical analysis, such as split feasibility problems, variational inequality problems, nonlinear optimization problems, equilibrium problems, complementarity problems, selection and matching problems, and problems of proving the existence of solution of integral and differential equations.The theory of fixed is known to find its applications in many fields of science and technology. For instance, the whole world has been profoundly impacted by the novel Coronavirus since 2019 and it is imperative to depict the spread of the coronavirus. Panda et al. [24] applied fractional derivatives to improve the 2019-nCoV/SARS-CoV-2 models, and by means of fixed point theory, existence and uniqueness of solutions of the models were proved. For more information on applications of fixed point theory to real life problems, authors should (see [6, 13, 24] and the references contained in).