• Management Science and Financial Engineering
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• v.15 no.2
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• pp.69-100
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• 2009

In this paper, we consider a relatively new two-machine flow shop scheduling problem where the unit time WIP cost increases as a job passes through various stages in the production process, and the objective is to minimize the total WIP (work-in-process) cost. Specifically, we study three special cases of the problem. First, we consider the problem where processing times on machine 1 are identical. Second, the problem with identical processing times on machine 2 is examined. The recognition version of the both problems is unary NP-complete (or NP-complete in strong sense). For each problem, we suggest two simple and intuitive heuristics and find the worst case bound on relative error. Third, we consider the problem where the processing time of a job on each machine is proportional to a base processing time. For this problem, we show that a known heuristic finds an optimal schedule.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.144-147
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• 2000

A numerical method for the solution of one-dimensional inverse heat conduction problem is established and its performance is demonstrated with computational results. The present work introduces the maximum entropy method in order to build a robust formulation of the inverse problem. The maximum entropy method finds the solution that maximizes the entropy functional under given temperature measurement. The philosophy of the method is to seek the most likely inverse solution. The maximum entropy method converts the inverse problem to a non-linear constrained optimization problem of which constraint is the statistical consistency between the measured temperature and the estimated temperature. The successive quadratic programming facilitates the maximum entropy estimation. The gradient required fur the optimization procedure is provided by solving the adjoint problem. The characteristic feature of the maximum entropy method is discussed with the illustrated results. The presented results show considerable resolution enhancement and bias reduction in comparison with the conventional methods.

• Journal of the Korean Home Economics Association
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• v.39 no.5
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• pp.15-26
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• 2001

The purpose of this study is to examine specific consumer problems in internet commerce and analyze them in the age of information. The way of sorting consumer problems in internet commerce from this study. For this empirical analysis, the data was collected 319 consumers by internet on-line survey from Feb. 13 to Feb. 20, 2000. The methods for study was frequency, percentage, mean, correlation, multiple regression using SAS PC program. The major findings of this study were as follows: 1. The level of consumer problem experiences in internet commerce was examined. The problems of privacy was the most problem and the problem of price was the second. Then delivery, advertisement, information was next, and the problem of quality, and A/S, change, cancel was the next consumer problem. 2. Among factors influence on experience consumer problem in internet commerce, the amount of usable money, information search were significant.

• International Journal of Advanced Culture Technology
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• v.7 no.3
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• pp.158-165
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• 2019

Knowledge based system includes tools for constructing, testing, validating and refining the system along with user interfaces. An important issue in the design of a complete knowledge based system is the ability to produce explanations. Explanations are not just a series of rules involved in reasoning track. More detailed and explicit form of explanations is required not only for reliable reasoning but also for maintainability of the knowledge based system. This requires the explanation mechanisms to extend from knowledge oriented analysis to task oriented explanations. The explicit modeling of problem solving structures is suggested for explanation generation as well as for efficient and effective reasoning. Unlike other explanation scheme such as feedback explanation, the detailed, smaller and explicit representation of problem solving constructs can provide the system with capability of quality explanation. As a key step to development for explanation scheme, the problem solving methods are broken down into a finer grained problem solving primitives. The system records all the steps with problem solving primitives and knowledge involved in the reasoning. These are used to validate the conclusion of the consultation through explanations. The system provides user interfaces and uses specific templates for generating explanation text.

• Journal of Korean Public Health Nursing
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• v.11 no.2
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• pp.152-170
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• 1997

The purpose of this study was to identify physical. psychological. sexual and socio-cultural problems that the adolescents have experienced and to assess the demands of counseling about the experienced problems. The design of this study was descriptive-survery study. The sample size was 601 middle and high school students. Data analysis was done by frequencies. Percent. t -test. ANOVA. Pearson correlation coefficiency, stepwise regression and Cronbach's $\alpha$ Score was produced for the reliability of the tool by using the item analysis method. The results was as follows : 1. The distribution of the each item that the adolescents experienced according to the physical, psychalogical. Sexual and Socio-cultural problem Categories was examined. In the physical problem category, the number of items that half and more than half of the adolescents experienced of often or frequently were 10 among all 19 items. In the psychological problem category. 13 item were among all 19 items. In the sexual problem category, 1 item among all 17 items and in the socio-cultural problem category, 10 items were among all 30 items. 2. The distribution of the each items that the adolescents wanted to the counseling according to the physical. psychological. sexual and socio-cultural problem categories was examined. In the physical problem category, the numbers of the items that half and more than half of the adolescents wanted counseling were 1 among all 19 items. In the psychological problem category, the numbers of the items that half and more than half of the adolescents wanted counseling were 2 items among all 19 items. In the sexual problem category, 0 item among all 17 items and in the socio-cultural problem category, 2 items were among all 30 items. 3. In the comparison of the female student and male student about the experienced problems and the demands of counseling according to the physical. psychological. sexual and socio-cultural problem categories. There was a significant difference statistically in all categories between groups(P<.001) 4. In the comparison of high school students and middle school students about the demands of counseling according to the physical. psychological. sexual and socio-cultural problem categories(P<.001). Particulary, grade II of high school students have experienced problems according to the physical. psychological. sexual and socio-cultural problem categories. There was a significant difference statistically in all categories(P<.001). 5. In the correlation between the experienced problem and the demands of counseling according to 4 categories. there was the positive correlation at P<.001 level. 6. The less the satisfaction for family and school life. the more experienced problems according to the physical. psychological. sexual and socio-cultural problem categories. There was a significant difference statistically in all categories(P<.001).

• Journal of The Korean Association For Science Education
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• v.26 no.6
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• pp.765-774
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• 2006

The purpose of this study was to suggest an instructional direction for improving scientific problem-finding ability. For this purpose, the present study made an in-depth analysis about activity on problem finding tasks of high school students in an ill-structured scientific problem situation. Subjects were divided into two groups (cooperative and individual) and two kinds of problem finding tasks were administered to two groups. Results indicated that a cooperative activity on problem finding happened to a series of steps exploring problem situation, expressing knowledge and experience, discussing provisional problems, creating various problems and selecting the best problem. Besides, a cooperative activity on problem finding depended heavily on prior knowledge and experience, and in the meantime, various scientific concepts turned out to naturally be expressed. As for the problems found out during a cooperative activity, their scores in creativity factors, including the degree of agreement in original problem selection came out to be on the whole, as excellent. In addition, the types of the problems found out in open problem situation showed that they were more various than those found out in closed problem situation. Subjects perceived that activity on problem finding had positive influence on scientific concept and science process skills. Findings of this study have the following educational implications: First, it is needed to prepare for educational environment that enables students to explore various knowledge and information. Second, the offering of various opportunities is needed to enlarge the scope of scientific knowledge and experience. Third, it is needed to prepare for a study atmosphere that lets students express their knowledge and experiences freely.

• IE interfaces
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• v.7 no.3
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• pp.193-199
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• 1994

The purpose of this paper is to develop a method of the sensitivity analysis that can be applicable to a degenerate tree solution of the minimum cost flow problem. First, we introduce two types of sensitivity analysis. A sensitivity analysis of Type 1 is the well known method applicable to a spanning tree solution. However, this method have some difficulties in case of being applied to a degenerate tree solution. So we propose a sensitivity analysis of Type 2 that keeps solutions of upper bounds remaining at upper bounds, those of lower bounds at lower bounds, and those of intermediate values at intermediate values. For the cost coefficient, we present a method that the sensitivity analysis of Type 2 is solved by using the method of a sensitivity analysis of Type 1. Besides we also show that the results of sensitivity analysis of Type 2 are union set of those of Type 1 sensitivity analysis. For the right-hand side constant or the capacity, we present a simple method for the sensitivity analysis of Type 2 which uses arcs with intermediate values.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.104-111
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• 1998

This study solves the inverse kinematics problem of industrial FANUC robot. Because every joint angle of FANUC robot is dependent on the position of end-effector and the direction of approach vector, arm metrix T6 is very complicated and each joint angle is a function of other joint angles. Therefore, the inverse kinematics problem can not be solved by conventional methods. Noticing the fact that if one joint angle is known, the other joint angles are calculated by the algebraic methods. $ heta$1 is calculated using neumerical analysis method, and solves inverse kinematics problem. This proposed method, in this study, is more simpler and faster than conventional methods and is very useful in the real-time control of the manipulator.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.3
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• pp.364-373
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• 1999

A combination of conjugate gradient and Levenberg-Marquardt method is used to estimate the spatially varying scattering coefficient, ${\sigma}(r)$, in the solid and hollow spheres by utilizing the measured transmitted beams from the solution of an inverse analysis. The direct radiation problem associated with the inverse problem is solved by using the $S_{12}-approximation$ of the discrete ordinates method. The accuracy of the computations increased when the results from the conjugate gradient method are used as an initial guess for the Levenberg-Marquardt method of minimization. Optical thickness up to ${\tau}_0=3$ is used for the computations. Three different values of standard deviation are considered to examine the accuracy of the solution from the inverse analysis.

• Journal of The Korean Association For Science Education
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• v.17 no.3
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• pp.273-288
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• 1997

The purpose of this study was to review the studies related to the problem of context in science education. Firstly, studies on context and context effects in science education (and also those related in cognitive psychology) were summarized according to the topics concerning science learning, such as deductive reasoning and probabilistic judgement, controlling variables, scientific inquiry skills, memory and consistency of misconceptions, selecting cognitive strategies and problem solving, achievement and momentum effect, and interest, religion and culture. Secondly, the common problems appeared from the analysis of the studies were discussed, such as (1) how to define contexts?, (2) how to classify contexts?, (3) how to characterize the effects of contexts? and (4) how to explain the context effects? Finally, the implications of the analysis of the studies on the problem of context were discussed in terms of recent development of science education, such as misconception studies, STS science education and the application of the history of science to science teaching.