• Industrial Engineering and Management Systems
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• v.15 no.4
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• pp.403-431
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• 2016

The objective of this study is to integrate the business, maintenance and production processes of a manufacturing system by incorporating errors. First, the required functions are estimated according to the historical data. The system activities are simulated by Visual SLAM software and the required outputs are obtained. Several outputs including lead times in different dimensions, total cost and production rates are computed through simulation. Finally, data envelopment analysis (DEA) is utilized in order to select the best option between the defined scenarios due to the multi-criteria feature of the problem. This is the first study in which the lead times, cost and production rates are simultaneously considered in the integrated system imposed of business, maintenance and production processes by incorporating errors. In the current study, the major bottlenecks of the system being studied are identified and suggested different strategies to improve the system and make the best decision.

• The Journal of the Korea Contents Association
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• v.7 no.5
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• pp.36-46
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• 2007

This paper presents an automated English scoring system designed to help non-native speakers of English, Korean-speaking learners in particular. The system is developed to help the 3rd grade students in junior high school improve their English grammar skills. Without human's efforts, the system identifies grammar errors in English sentences, provides feedback on the detected errors, and scores the sentences. Detecting grammar errors in the system requires implementing a special type of rules in addition to the rules to parse grammatical sentences. Error production rules are implemented to analyze ungrammatical sentences and recognize syntactic errors. The rules are collected from the junior high school textbooks and real student test data. By firing those rules, the errors are detected followed by setting corresponding error flags, and the system continues the parsing process without a failure. As the final step of the process, the system scores the student sentences based on the errors detected. The system is evaluated with real English test data produced by the students and the answers provided by human teachers.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.69.2-69
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• 2002

Process measurements contain random and gross errors and the size estimation of gross errors is required for production accounting. Mixed integer programming technique had been applied to identify and estimate the gross errors simultaneously. However, the compensate model based on mixed integer programming used all measured variables or spanning tree as gross error candidates. This makes gross error estimation problem combinatorial or computationally expensive. Mixed integer programming with test statistics is proposed for computationally inexpensive gross error identification /estimation. The gross error candidates are identified by measurement test and the set of gross error candidates are...

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.3
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• pp.213-223
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• 1999

This study provides a improved model of digital basemap production that can efficiently identify and correct the various errors generated in digital map production process. In order to fulfill the requirements that the new model calls for, this study provides a typology of errors by analyzing the errors in digital basemap data. Computer programs for automatic error searching and for checking the correctness of the digital codes in the data have also been developed. Exsiting visual error-checking process has also been analyzed and more systematic process is suggested. As a result, it is found that the improved model of digital basemap production suggested in this study contributes to improving the quality of the digital map database by providing a systematic method for efficient error-searching and correction of digital map data.

• English Language & Literature Teaching
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• v.13 no.2
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• pp.63-90
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• 2007

The present study investigated what combination of three form-focused options - explicit explanation, production practice, and corrective feedback - may be effective in helping low-proficiency learners improve accuracy in communicative writing. The subjects were 34 Korean university students enrolled in 'Business English 1' and the study lasted 11 weeks. The relative clause structure was selected as the target structure. The study found that the combination of explicit explanation, sentence-level production practice, communicative writing practice, and recasts had a significantly greater effect on improved accuracy than the combination of communicative writing practice and recasts and that of explicit explanation, communicative writing practice, and recasts. Because the second and third combinations didn't lead to significantly improved accuracy, it can be concluded that of the form-focused options forming the first combination sentence-level production practice made a decisive contribution to the significant increase in accuracy. It also found that the provision of self-correcting opportunities before providing recasts on errors committed in sentence-level production practice resulted in significantly greater accuracy in communicative writing than the provision of recasts alone on them. The results of the study suggest that we should make low-proficiency Korean learners have sentence-level production practice which is intensive and focused and make them self-correct targeted errors before providing them with narrowly focused recasts in order to help them to improve writing accuracy.

• Phonetics and Speech Sciences
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• v.7 no.2
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• pp.3-8
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• 2015

Denasalization that nasals are replaced by stops is an unusual error pattern related to manner of articulation. The purpose of this study is to investigate the prevalence of denasalization and to scrutinize the nasal production according to phonological context for typically developing children and children with speech sound disorders(SSD). 220 typically developing children and 48 SSD children from 2~6 years of age were tested with a formal word test, and those who demonstrate denasalization were selected. In addition, the nasal production of SSD children with denasalization were analyzed for the correctness and the error types using the formal word test and spontaneous conversation. The results were as follows: (1) Denasalization was shown in below 10% of 2-3 years of age with typically developing children and in above 20% of 2-5 years of age with SSD. (2) The SSD children who demonstrate denasalization were categorized into 4 types according to the error context of nasals; nasal errors with all word positions, nasal errors with word-final and word-medial positions, nasal errors with word-medial position preceding vowels, and nasal errors with word-medial position preceding obstruents. These results indicate that denasalization is a clinically important error pattern, and word-medial position preceding obstruents is an essential context for denasalization in terms of Korean phonotactics.

• International Journal of Quality Innovation
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• v.3 no.2
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• pp.46-56
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• 2002

The presence of imprecise measurement may seriously affect the efficiency of process control and production cost. A cost model is derived to determine the design parameters of the economic asymmetric $\bar{X}$ and S control charts including measurement errors. The effects of imprecise measurement on the performance of the economic asymmetric $\bar{X}$ and S control charts and production cost are examined for the case where the process mean and process standard deviation may change. Application of the proposed control charts is demonstrated through an example. Numerical examples illustrate the effects of imprecise measurement on the design parameters of the proposed control charts. It shows that the imprecision measurement may seriously affrct the ability of the proposed control charts to detect process disturbances quickly, change the sampling frequency, and increase the production cost compared to the control charts excluding measurement errors.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.425-428
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• 2015

New technologies using a CNC machine are being developed to reduce the production cost of free-form buildings. For production of free-form members using such technologies, vast free-form buildings should be first split into multiple panels that are productible. Taking into consideration of the curved surface of free-form members, the segmented free-form panels may vary in shape and size, which may cause a lot of errors. In addition, it is time-consuming for the work. However, the current panelizing work is completed with the trials and errors of engineers and architectural designers even in large-scale projects, which results in increased construction duration and cost. Thus, it is necessary to develop a technology for panelizing free-form panels so as to maximize the economic feasibility of production technologies for free-form concrete members. The study intends to develeop automatic panelizing algorithms of free-form buildings considering the curved surface and size of free-form panels and the production conditions. The developed algorithms will be useful in applying the production technologies of free-form buildings using CNC machine and reducing the cost.

• The Korean Journal of Ecology
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• v.28 no.4
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• pp.215-222
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• 2005

MODIS (Moderate Resolution Image Spectrometer) is a core satellite sensor boarded on Terra and Aqua satellite of NASA Earth Observing System since 1999 and 2001, respectively. MODIS LAI, FPAR, and GPP provide useful means to monitor plant phonology and material cycles in terrestrial ecosystems. In this study, LAI, FPAR, and GPP in Korea were evaluated and errors associated with cloud contamination on MODIS pixels were eliminated for years $2001\sim2003$. Three-year means of cloud-corrected annual GPP were 1836, 1369, and 1460g C $m^{-2}y^{-1}$ for evergreen needleleaf forest, deciduous broadleaf forest, and mixed forest, respectively. The cloud-originated errors were 8.5%, 13.1%, and 8.4% for FPAR, LAI, and GPP, respectively. Summertime errors from June to September explained by 78% of the annual accumulative errors in GPP. This study indicates that cloud-originated errors should be mitigated for practical use of MODIS vegetation products to monitor seasonal and annual changes in plant phonology and vegetation production in Korea.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.159-168
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• 2015

Aggregate Production Planning determines levels of production, human resources, inventory to maximize company's profits and fulfill customer's demands based on demand forecasts. Since performance of aggregate production planning heavily depends on accuracy of given forecasting demands, choosing an accurate forecasting method should be antecedent for achieving a good aggregate production planning. Generally, typical forecasting error metrics such as MSE (Mean Squared Error), MAD (Mean Absolute Deviation), MAPE (Mean Absolute Percentage Error), and CFE (Cumulated Forecast Error) are utilized to choose a proper forecasting method for an aggregate production planning. However, these metrics are designed only to measure a difference between real and forecast demands and they are not able to consider any results such as increasing cost or decreasing profit caused by forecasting error. Consequently, the traditional metrics fail to give enough explanation to select a good forecasting method in aggregate production planning. To overcome this limitation of typical metrics for forecasting method this study suggests a new metric, WACFE (Weighted Absolute and Cumulative Forecast Error), to evaluate forecasting methods. Basically, the WACFE is designed to consider not only forecasting errors but also costs which the errors might cause in for Aggregate Production Planning. The WACFE is a product sum of cumulative forecasting error and weight factors for backorder and inventory costs. We demonstrate the effectiveness of the proposed metric by conducting intensive experiments with demand data sets from M3-competition. Finally, we showed that the WACFE provides a higher correlation with the total cost than other metrics and, consequently, is a better performance in selection of forecasting methods for aggregate production planning.