• Transactions of the Korean Society of Mechanical Engineers B
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• 제20권11호
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• pp.3655-3665
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• 1996

An analytical solution is presented for the conduction-dominated solidification of a binary mixture in a semi-infinite medium. The present approach differs from that of other solution by these four characteristics. (1) Solid fraction is determined from the phase diagram, (2) thermophysical properties in mushy zone are weighted according to the local solid fraction, (3) non-equilibrium solidification can be simulated and (4) the cooling condition of under-eutectic temperature can be simulated. Up to now, almost all analyses are based on the assumption of constant properties in mushy zone and solid fraction linearly with temperature or length. The validation for these assumptions, however, shows that serious error is found except some special cases. The influence of microscopic model on the macroscopic temperature profile is very small and can be ignored. But the solid fraction and average solid concentration which directly influence the quality of materials are drastically changed by the microscopic models. An approximate solution using the method of weighted residuals is also introduced and shows good agreement with the analytical solution. All calculations are performed for NH$_{4}$Cl-H$_{2}$O and Al-Cu system.

• Proceedings of the KWS Conference
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• 대한용접접합학회 2009년 추계학술발표대회
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• pp.87-91
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• 2009

Welding is one of the most important joining processes and the effect of welding residual stresses in the structure has a great deal of influence on its quality. In this paper, recent development in computational welding mechanics, particularly calculation of welding residual stresses, is introduced. The hypoelastic formulation of finite element analysis for thermoelastic-plastic deformation is applied to welding processes to find residual deformations and stresses. Leblond's phase evolution equation coupled with the energy equation is employed to calculate the phase volume fraction; this plays an important role as a kinetics parameter affecting phase fraction effects in the mechanical constitutive equation of welded materials. Furthermore, transformation plasticity is taken into account for an accurate evaluation of stress. The influence of the phase transformation and the transformation plasticity on residual stress is investigated by means of numerical analyses using metallurgical parameters in Leblond's phase evolution equation that are adjusted with respect to various cooling rates in a CCT-diagram. Coding implementation is conducted by way of the ABAQUS user subroutines, UMAT.

• Korean System Dynamics Review
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• 제17권3호
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• pp.121-143
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• 2016

The purpose of this study to analyze the effect of Mindfulness on the Therapeutic Relationship using System Dynamics. The biggest factor in psychotherapy's treatment outcome is the Therapeutic Relationship including the quality of the therapist (empathy, therapeutic presence) and therapy alliance. Mindfulness practice can facilitate the therapeutic relationship. In order to analyze the therapeutic relationship, I measure FFMQ(Five Facet Mindfulness Questionnaire), Empathy, Therapeutic presence and Therapy alliance. Participants consist of 55 mental health professionals (doctor, psychologist, psychiatrist, counselor, social worker). The result of the study will be explained. First, with the causal loop diagram research, I analyze how mindfulness can influence the quality of therapist and therapy alliance. The result of literature research indicate that mindfulness increase therapist's empathy, congruence, therapeutic presence, flow, therapy alliance. And then mindfulness reinforces the ability of therapeutic relationship. Secondly, through the real data research and simulation analysis, mindfulness practicing period (year and hour a day) of therapist is studied. The result of the therapist experiencing mindfulness practice period is over 5 years and the daily hours of practice is 2 - 2.5 hours in order to enhance the therapeutic relationship. After reviewing the result of the research it is important to understand the practicing period and daily practice of mindfulness. With daily practice and time, the level of mindfulness will increase and influence positively the therapeutic relationship between therapist and client.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제41권4호
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• pp.171-178
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• 2018

Recently, the continuing operation of nuclear power plants has become a major controversial issue in Korea. Whether to continue to operate nuclear power plants is a matter to be determined considering many factors including social and political factors as well as economic factors. But in this paper we concentrate only on the economic factors to make an optimum decision on operating nuclear power plants. Decisions should be based on forecasts of plant accident risks and large and small accident data from power plants. We outline the structure of a decision model that incorporate accident risks. We formulate to decide whether to shutdown permanently, shutdown temporarily for maintenance, or to operate one period of time and then periodically repeat the analysis and decision process with additional information about new costs and risks. The forecasting model to predict nuclear power plant accidents is incorporated for an improved decision making. First, we build a one-period decision model and extend this theory to a multi-period model. In this paper we utilize influence diagrams as well as decision trees for modeling. And bayesian statistical approach is utilized. Many of the parameter values in this model may be set fairly subjective by decision makers. Once the parameter values have been determined, the model will be able to present the optimal decision according to that value.

• Structural Engineering and Mechanics
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• 제85권5호
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• pp.679-691
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• 2023

Many codes allow designers to use the bending moment diagram computed by elastic analysis and modify it by a certain amount of moment redistribution (MR) to account for plastic behaviour of continuous beams. However, several researchers indicated that the MR at the ultimate limit state (𝛽_u) for some beams deviate significantly from the specified values of various codes. This paper examines the applicability of the provisions on 𝛽_u in ACI 318-19 and Eurocode 2 through numerical investigations and comprehensively explores the influencing factors. The results show that some parameters not considered in those codes influence 𝛽_u to a certain extent, where the ratio of tensile reinforcement ratio at intermediate support to tensile reinforcement ratio at midspan (𝜌_s1/𝜌_s2) and load type are crucial parameters to consider. The specific combination of these two parameters may make the codes overestimate or significantly underestimate the 𝛽_u. On the other hand, the yield state of both critical sections is found to have an important influence on the influence degree of each parameter on 𝛽_u. The yield conditions are investigated, and an empirical judgment equation is proposed. In addition, the influence laws of the critical parameters on 𝛽_u have been further proved by theoretical derivation. Finally, due to 𝜀_t is found to have a better linear correlation with 𝛽_u than x_u/d, equations as a function of 𝜀_t for predicting the 𝛽_u of continuous beams under the two loads are proposed, respectively.

• Journal of the Korean Home Economics Association
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• 제24권2호
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• pp.75-82
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• 1986

This study was measured experimentally the Configuration factor of the adult female with the purpose of explaning quantitatively the human body's radiant heat exchange in a small scale of a house. And it is a investigatio about human clothed body's heat resistance which have great influence on radiant heat exchange. The result of this study was diagrammatized the [Shape×Area Factor] for the sake of making it easy to calculate the quantity of the actual human body's radiant heat exchange, and designed a diagram to make it easy to find the value of the human clothed body's heat resistance and clothing surface temperature. Thus, this research can be used as a basic resource for not only calculating wuantitatively radiant heat exchange of human clothed body and unclothed body in the radiant heating system of low temperature but also designing the thermal environment in a room.

• Journal of the Korea Safety Management & Science
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• 제11권4호
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• pp.119-125
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• 2009

We predict the earthquake rate in Korea following Bayesian approach. We make a model that can utilize the data to predict other levels of earthquake. An event tree model which is a frequently used graphical tool in describing accident initiation and escalation to more severe accident is transformed into an influence diagram model. Prior distributions for earthquake occurrence rate and probabilities to escalating to more severe earthquakes are assumed and likelihood of number of earthquake in a given period of time is assessed. And then posterior distributions are obtained based on observed data. We find that the minor level of earthquake is increasing while major level of earthquake is less likely.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 한국주거학회 2009년도 추계학술발표대회 논문집
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• pp.186-191
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• 2009

With the change of the housing market, construction company should diversify publicity activities. Especially, TV advertisement exerts a stronger influence on customers. So it's important to understand process materialized with company's strategic image. 1) First of all, it was found that clusters is the assignment of a set of similar character with cluster analysis 2) An attempt was made to draw a diagram to measure the objective distance between advertisement Image and remained brand image. It's possible to confirm which Idea of advertisement concept is effective and whether present strategy is collect or not.

• Korean System Dynamics Review
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• 제14권1호
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• pp.31-53
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• 2013

The purpose of this study is to explain the impact of hosting mega event using the system dynamics and to establish the model for analysis of the impact of hosting mega event. The results are as follows. First, the growth of inbound tourists have influenced long term effect. Second, the export has increased for a limited period only after the hosting mega event, but the increase in export returned to the previous state in terms of economic impact of mega event. Third, nation brand has been improved for a limited period only such as the economical impact in terms of socio-cultural impact of mega event. Last, citizenship consciousness has been improved after hosting mega event. Further researches have to be carried out to modify and reinforce the model.

• International Journal of Automotive Technology
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• 제6권6호
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• pp.625-633
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• 2005

Vehicle drift was reduced using statistical six sigma tools. The study was performed through four steps: M (measure), A (analyze), I (improve), and C (control). Step M measured the main factors which were derived from a fishbone diagram. The measurement system capabilities were analyzed and improved before measurement. Step A analyzed critical problems by examining the process capability and control chart derived from the measured values. Step I analyzed the influence of the main factors on vehicle drift using DOE (design of experiment) to derive the CTQ (critical to quality). The tire conicity and toe angle difference proved to be CTQ. This information enabled the manufacturing process related with the CTQ to be improved. The respective toe angle tolerance for the adjustment process was obtained using the Monte Carlo simulation. Step C verified and controlled the improved results through hypothesis testing and Monte Carlo simulation.