• Korean Management Science Review
• /
• v.13 no.2
• /
• pp.25-48
• /
• 1996

Mixed Model Assembly Lines (MMALs) are increasingly used to produce differentiated products on a single assembly line without work-in-process storage, Usually, a typical MMAL consists of a number of (1) stations doing exactly the same operation on every job, (2) stations involving operations with different choices, and (3) stations offering operations that are not performed on every job, or that are performed on every job but with many options. For stations of the first type there is no sequencing problem at all. However, for the second type a set-up cost is incurred each time the operation switches from one choice to another. At the third type of stations, different models, requring different amounts and choices of assembly work, creates an uneven flow of work along the line and variations in the work load at these stations. When a subsequence of jobs requires more work load than the station can handle, it is necessary to help the operations at the station or to complete the work elsewhere. Therefore, a schedule which minimize the sum of set-up cost and utility work cost is desired. So this study has developed Fixed Random Ordering Rule (FROR), Fixed Ascending Ordering Rule (FAOR), Fixed Descending Ordering Rule, and Extended NHR (ENHR). ENHR is to choose optimal color ordering of each batch with NHR, and to decide job sequence of the batch with it, too. As the result of experiments, ENHR was the best heuristic algorithm. NHR is a new heuristic rule in which only the minimum addition of violations from both partial sequence and unassigned sequence at every branch could be considered. And this is a heuristic sequencing rule for the third type of stations at MMAL. This study developed one more heuristic algorithm to test the performance of NHR, which is named as Practical Heuristic Rule (PHR).

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.27 no.1
• /
• pp.59-85
• /
• 2016

The purpose of this study was to synthesize the effects of the information literacy instruction using meta-analysis. Results using random-effect models were as follows. First, the overall average effect size (ES) of information literacy instruction (Hedges'g) was 0.72, which could be interpreted based on Cohen's guidelines as moderate to large. Second, the two types of information literacy instruction, demonstrating more than medium ESs, did not show significant differences in their ESs. Third, the ESs of information literacy instruction differed depending on the measuring variables. Fourth, grade, study design and the form of the measurement tool were moderator variables that explain the differences in ESs. In sum, the effects of information literacy instruction, having more than medium effect size, seem quite stable across instruction types and study designs.

• Proceedings of the Korean Society of Plant Biotechnology Conference
• /
• 2005.11a
• /
• pp.106-111
• /
• 2005

For breeding of a new rootstock for eggplant production, somatic hybrids between two species, Solanum integrifolium and S. sanitwongsei were obtained through protoplast fusion. The former species has been commonly used for rootstock for eggplant production in Japan. Eggplants on these rootstocks are more productive than ungrafted plants, but are susceptible to bacterial wilt caused Ralstonia solanacearum. While the latter species is resistant, the growth of eggplants on this rootstock is rather slow and low yield. Protoplast of both species were isolated from cotyledons, and inactivated with iodoacetamide or UV-irradiation, then fused electrically. The fused products were then cultured. Regenerated plantlets were then transplanted on soil then maintained in a green house. The plants were classified into four groups. Those in the first group showed morphological characters intermediate of the parentalspecies. The plants bore fruit with viable seeds. The plants showed a chromosome number of 2n=48, the sum of those of the parental species, and are suggested to be symmetric fusion products. While plants in the other groupswas less vigorous and showed chromosome number 2n= 68 to 72 suggesting asymmetric fusion products by genomic in situ hybridization(GISH). Isozyme pattern of shikimate dehydrogenase (SKDH; EC 1.1.1.25), isocitrate dehydrogenase (IDH; EC 1.1.1.41) and phosphoglucomutase (PGM; EC 2.7.5.1) showed that 24 regenerated plants in three groups were somatic hybrids. Analysis of random amplified polymorphic DNA (RAPD) showed that 43 S. integrifolium-specific and 57 S. sanitwongsei-specific bands were all found in 24 plants. Both somatic hybrids and its S1 plants were found to be resistant to bacterial wilt, and eggplant grafted these plants using for rootstocks were more productive than grafted mother plants. Now, S1 progenies are used for commercial eggplant production in Osaka Prefecture.

• Journal of the Korean Home Economics Association
• /
• v.43 no.8 s.210
• /
• pp.55-68
• /
• 2005

The purpose of this study is to examine the effects of negative life events on mental health and to explore possible main and moderating effects of spousal support on mental health with a focus on gender differences. The data for this study were taken from a nationwide random sample of 1,504 married men and women ranging in age from 30 to 59 through structured questionnaires. The data were analyzed using the SPSS WIN program which was used to calculate frequency, mean, 1-test, multiple regressions. The main results were as follows: First, by examining mental health of Korean men and women, women were more likely than men to experience higher levels of depression. Second, there was no gender difference in the sum of experience of negative life events, therefore the date of this study did not support the differential exposure hypothesis. In addition, men perceived more support from their spouses than women. Third, results show that especially the event concerning with job/financial problems has negative impacts on mental health of both men and women, and vulnerability to undesirable life events was not found. Fourth, spousal support is associated with better mental health regardless of gender, and it reduces the harmful effects of life events concerning with job/financial area for both men and women. Also, spousal support reduces the magnitude of the harmful effects of life events concerning with health of men. This study focused on the impact of negative life events and the couple process. It was possible to explore the strength of social support provided from spouse of most importance to the individuals. These results affirm the importance of supportive relationships between couples as a buffer, mitigating harmful effects of negative life events on mental health.

• The Journal of the Acoustical Society of Korea
• /
• v.10 no.1
• /
• pp.20-29
• /
• 1991

A fundamental assumption in conventional linear predictive coding (LPC) analysis procedure is that the input to an all-pole vocal tract filter is white process. In the case of periodic inputs, however, a pitch bias error is introduced into the conventional LP coefficient. Multi-pulse (MP) LP analysis can reduce this bias, provided that an estimate of the excitation is available. Since the prediction error of conventional LP analysis can be modeled as the sum of an MP excitation sequence and a random noise sequence, we can view extracting MP sequences from the prediction error as a classical detection and estimation problem. In this paper, we propose an algorithm in which the locations and amplitudes of the MP sequences are first obtained by applying a likelihood ratio test (LRT) to the prediction error, and LP coefficients free of pitch bias are then obtained from the MP sequences. To verify the performance enhancement, we iterate the above procedure with adaptive threshold at each step.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.40 no.5
• /
• pp.211-219
• /
• 2014

Objectives: The purpose of this research was to create a scoring system that provides comprehensive assessment of patients with oromaxillofacial cancer or odontogenic infection, and to statistically reevaluate the results in order to provide specific criteria for elective tracheostomy. Materials and Methods: All patients that had oral cancer surgery (group A) or odontogenic infection surgery (group B) during a period of 10 years (2003 to 2013) were subgrouped according to whether or not the patient received a tracheostomy. After a random sampling (group A: total of 56, group B: total of 60), evaulation procedures were observed based on the group classifications. For group A, four factors were evaluated: TNM stage, reconstruction methods, presence of pathologic findings on chest posterior-anterior (PA), and the number of systemic diseases. Scores were given to each item based on the scoring system suggested in this research and the scores were added together. Similarly, the sum score of group B was counted using 5 categories, including infection site, C-reactive protein level on first visit, age, presence of pathologic findings on chest PA, and number of systemic diseases. Results: The scoring system rendered from this research shows that there is a high correlation between the scores and TNM stage in oral cancer patients, or infection sites in odontogenic infection patients. However, no correlation between pathologic findings on chest PA could be found in either group. The results also indicated that for both groups, the hospital day increased with the tracheostomy score. The tracheostomy score cutoff value was 5 in oral cancer patients and 6 in odontogenic infection patients which was used for elective tracheostomy indication. Conclusion: The elective tracheostomy score system suggested by this research is a method that considers both the surgical and general conditions of the patient, and can be very useful for managing patients with severe oral disease.

• Journal of Korea Society of Industrial Information Systems
• /
• v.23 no.2
• /
• pp.19-28
• /
• 2018

In this paper, we studied on the sampling of ocean meteorological data to analyze signature of naval ships. The newest ocean meteorological data, that was quality controled by the Korea Meteorological Administration(KMA), was collected. Outliers were removed from the data by setting the usable range of data. After that, the data size was reduced through the random sampling method, taking geopolitical significance and effective area of buoy, for probabilistic analysis. Moreover, the sample sizes were set at 100, 200, and 400 by considering the population size and a 95% confidence level. The final sample was obtained using the two-dimensional stratified sampling method based on highly correlated water temperature and air temperature. The sum of the squared errors and the confidence interval was calculated to compare the result of sampling. As a result, this study proposed reasonable sample size for infra­red signature analysis of naval ships.

• KIISE Transactions on Computing Practices
• /
• v.21 no.1
• /
• pp.94-99
• /
• 2015

With the recent machine learning paradigm of using nonparametric Bayesian statistics and statistical inference based on random sampling, the Dirichlet distribution finds many uses in a variety of graphical models. It is a multivariate generalization of the gamma distribution and is defined on a continuous (K-1)-simplex. This paper presents a sampling method for a Dirichlet distribution for the problem of dividing an integer X into a sequence of K integers which sum to X. The target samples in our problem are all positive integer vectors when multiplied by a given X. They must be sampled from the correspondingly gridded simplex. In this paper we develop a Markov Chain Monte Carlo (MCMC) proposal distribution for the neighborhood grid points on the simplex and then present the complete algorithm based on the Metropolis-Hastings algorithm. The proposed algorithm can be used for the Markov model, HMM, and Semi-Markov model for accurate state-duration modeling. It can also be used for the Gamma-Dirichlet HMM to model q the global-local duration distributions.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.31 no.1
• /
• pp.91-103
• /
• 2006

Given a bill of materials (BOM) tree T labeled by the breadth first search (BFS) order from node 0 to node n and a general network ${\Im}=(V,A)$, where V={1,2,...,m} is the set of production facilities and A is the set of arcs representing transportation links between any of two facilities, we assume that each node of T stands for not only a component. but also a production stage which is a possible stocking point and operates under a periodic review base-stock policy, We also assume that the random demand which can be achieved by a suitable service level only occurs at the root node 0 of T and has a normal distribution $N({\mu},{\sigma}^2)$. Then our integrated model of facility location problems and safety stock optimization problem (FLP&SSOP) is to identify both the facility locations at which partitioned subtrees of T are produced and the optimal assignment of safety stocks so that the sum of production cost, inventory holding cost, and transportation cost is minimized while meeting the pre-specified service level for the final product. In this paper, we first formulate (FLP&SSOP) as a nonlinear integer programming model and show that it can be reformulated as a 0-1 linear integer programming model with an exponential number of decision variables. We then show that the linear programming relaxation of the reformulated model has an integrality property which guarantees that it can be optimally solved by a column generation method.

• Journal of the East Asian Society of Dietary Life
• /
• v.7 no.2
• /
• pp.199-210
• /
• 1997

The purpose of this study was to investigate the mutual relationship between food preference and nutrient intake status of high school students, based on the their personal characters which are sex, age, family type, number of family, mother's age, occupation, and school career. 439 students were selected with random stratified cluster sampling method. The study used a self-administrated questionnaire and 24-hour recall method for 5 days as instrument tools. Statistical methods applied to analyze the data were frequency, percent, Willcoxon Rank-sum test, Kruskal-Wallis test, ${x^2}-test$ by contingence table, and Spearman's correlation coefficient in non parametric statistical methods. Some of interesting results are as follows : 1. The correlation between sex and the set of characters of mother's age, school career and income is highly significant. However there is no any significant difference on the kinds of job and the types of family. 2. The relation between the preference of main dishes and the nutrient intake show a significant difference except to the noodles. This marks that preference of main dishes shows a direct proportion with the nutrient intakes except for the fat, vitamin A, vitamin C. 3. The preference of animal food marks a direct proportion with the nutrients such as energy, protein, fat, fiber, phosphorus, iron, vitamin $B_{1}$, vitamin $B_{2}$, and niacin 4. The preference of vegetable food gives some influence on the nutrient intake but the preference of soup is insignificant, the preference of Kimchi is in reverse proportion, and the preference of vegetable marks a direct proportion with the nutrient intake. 5. The preference of snacks marks a direct proportion with all kinds of nutrients intake except for the vitamin A, and vitamin C.