• Journal of Korean Institute of Industrial Engineers
• /
• v.41 no.6
• /
• pp.521-529
• /
• 2015

Statistical process control techniques have been greatly implemented in industries for improving product quality and saving production costs. As a primary tool among these techniques, control charts are widely used to detect the occurrence of assignable causes. In most works on the control charts it considered the problem of monitoring the mean and variance, and the quality characteristic of interest is normally distributed. In some situations monitoring of the minimum and maximum values is more important and the quality characteristic of interest is the Weibull distribution rather than a normal distribution. In this paper, we consider the statistical design of minimum and maximum control charts when the distribution of the quality characteristic of interest is Weibull. The proposed minimum and maximum control charts are applied to the wind data. The results of the application show that the proposed method is more effective than traditional methods.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.393-396
• /
• 2003

A systematic investigation for the process design in deep drawing is necessary to improve the quality of drawn cups. This study concentrates mainly on the influence of process design strategy on the product quality. Several types of process design were chosen from initial blank of 100mm in diameter to make final cup of 50mm in diameter. Forming analysis are carried out to find out optimal design in terms of drawing force. We assume that the case which shows minimum drawing force in the subsequent operations is the best case. Through experiments it is found that the case which shows minimum drawing force also results in minimum drawing force and better product quality than other case. Thus, it is shown that this design strategy is very effective in the improvement of quality in drawn cups.

• Industrial Engineering and Management Systems
• /
• v.9 no.3
• /
• pp.204-214
• /
• 2010

A manufacturing/remanufacturing system is investigated with the consideration of required minimum quality of end-of-used products. A constant demand is satisfied by remanufacturing end-of-used products and manufacturing raw materials outsourced from outside. It is assumed in this system that the buyback price and remanufacturing cost are related to the different quality level of end-of-used products. For remanufacturing, only the used products that satisfy a required minimum quality level will be recycled. Thus, the returning rate is a function of the required minimum quality level. Functions of returning rate, buyback price and remanufacturing cost, which are closely connected to the quality level of end-of-used products, are investigated here. Treating the required minimum quality level of end-of-used products, the length of a cycle, the number of manufacturing lots and remanufacturing lots in a cycle as decision variables, the mathematical models with the objective of minimizing the average total cost are constructed. Through construction of a solution process based on Tabu Search algorithm and calculating examples, the validity of the models is illustrated.

• Journal of Power Electronics
• /
• v.7 no.1
• /
• pp.72-80
• /
• 2007

Voltage sags are one of the most frequently occurring power quality problems challenging power systems today. The Unified Power Quality Conditioner (UPQC) is one of the major custom power solutions that are capable of mitigating the effect of supply voltage sags at the load or Point of Common Coupling (PCC). A UPQC-Q employs a control method in which the series compensator injects a voltage that leads the supply current by $90^{\circ}C$ so that the series compensator at steady state consumes no active power. However, the UPQC-Q has the disadvantage that its series compensator needs to be overrated. Thus it cannot offer effective compensation. This paper proposes a new control scheme for the UPQC-Q that offers minimum power injection. The proposed minimum power injection method takes into consideration the limits on the rated voltage capacity of the series compensator and its control scheme. The validity of the proposed control scheme is investigated through simulation and experimental results.

• Journal of Wellbeing Management and Applied Psychology
• /
• v.6 no.4
• /
• pp.1-10
• /
• 2023

Purpose: As an important provision to protect the rights and interests of low-income groups, it is worth studying whether the minimum wage policy can improve the quality of life for people. Research design, data and methodology: Using data from the 2015 and 2017 China General Social Survey (CGSS), this paper employs the logit model to estimate the probability of an individual's annual income being higher than the per capita disposable income of their province. It also utilizes the DID model to analyze the impact of minimum wage increases on individuals' annual incomes. Results: The analysis reveals that an overall increase in the minimum wage raises the probability of an individual's annual income exceeding the per capita disposable income by 3%. Among them, the probability increased by 2.2% for males and by 3.2% for females. Furthermore, the impact of the minimum wage on annual income varies depending on the individual's income level. Notably, the most positive and significant impact is observed for individuals whose income level is close to the minimum wage standard. Conclusions: This provides evidence that the increase in the minimum wage has effectively improved the quality of life for the population.

• Analytical Science and Technology
• /
• v.37 no.2
• /
• pp.79-86
• /
• 2024

Among the nutrients in feed, amino acids and minerals are important for the growth and development of pets. In particular, interest in nutritional components related to the health of pets is increasing as pet-raising households and pet food markets have recently grown. Therefore, in this study, 55 pet food products distributed in South Korea were purchased, and the content of 3 essential and conditionally essential amino acids (taurine, lysine, arginine) and 4 minerals (Ca, P, Na, K) was investigated. Among the three amino acids, arginine was found to have the highest content, and the average content was 1.79 and 1.37 % in cat and dog foods, respectively. On the other hand, the taurine content was the lowest, but it was found to be higher than the minimum requirement of 0.10 % for cats set by the American Association for Feed Control (AAFCO) and the European Federation of Pet Food Industries (FEDIAF). As a result of the four-component analysis of minerals, the content of Ca was found to be the highest, and the average content was confirmed to be 1.64 and 1.25 % in cat and dog food, respectively. On the other hand, Na was the lowest, but it was higher than the AAFCO minimum requirement and FEDIAF minimum requirement for young cat and dog food. Among all 55 samples examined, the content of the three amino acids and the four inorganic components was confirmed to be suitable for the recommended minimum intake and maximum allowable intake presented by AAFCO and FEDIAF.

• The Journal of the Acoustical Society of Korea
• /
• v.30 no.3
• /
• pp.123-128
• /
• 2011

In this paper, we propose the improved noise power estimation in speech enhancement under various noise environments. The previous MS algorithm tracking the minimum value of finite search window uses the optimal power spectrum of signal for smoothing and adopts minimum probability. From the investigation of the previous MS-based methods it can be seen that a fixed size of the minimum search window is assumed regardless of the various environment. To achieve the different search window size, we use the noise classification algorithm based on the Gaussian mixture model (GMM). Performance of the proposed enhancement algorithm is evaluated by ITU-T P.862 perceptual evaluation of speech quality (PESQ) under various noise environments. Based on this, we show that the proposed algorithm yields better result compared to the conventional MS method.

• Journal of Korean Society for Quality Management
• /
• v.15 no.2
• /
• pp.20-26
• /
• 1987

An algorithm for the minimum total process percent defective under marginal costs is presented. Initial process is single series system, which is constructed by k process units, and each process is considered priority. Minimum of total process percent defective for parallel-series system exists when additional process setup costs are larger than marginal costs.

• Industrial Engineering and Management Systems
• /
• v.8 no.3
• /
• pp.162-170
• /
• 2009

This paper deals with a closed-loop remanufacturing system with one manufacturer and one remanufacturer. The manufacturer sells new products bearing the 'Extended Producer Responsibility (EPR).' It is assumed that the manufacturer's collection rate of used products depends only on the buy-back cost, while that of the remanufacturer depends on the minimum allowed quality level of used products in addition to the buy-back cost. Through the development of mathematical models with the objective function of maximizing profit, we study an efficient operation policy of each party. The decision variables are the unit selling price of new products and remanufactured products, the unit buy-back cost of the used products of the manufacturer and remanufacturer, and the minimum allowed quality level. The validity of the model is examined through numerical examples and sensitivity analysis.

• Journal of Korean Society of Rural Planning
• /
• v.17 no.2
• /
• pp.13-21
• /
• 2011

The federal government has been implemented several housing policies attempting to improve living quality at Eup-Myun area(rural area), but those were mostly fund supports to reconstruct or repair houses. Existing minimum housing standard is focused on urban apartments and indoor space, but the houses of Eup-Myun area are scattered and are different from urban's house space. Therefore, this study focused on these area, and intended to propose suitable minimum housing standard for Eup-Myun area. Based on literature reviews about housing standard of England, U.S., Japan and South Korea, questionnaire survey was given to 50 experts divided into 2 groups, professors of architecture and researchers on rural environment. This study proposed the direction of new minimum housing standard of Eup-Myun area, it could be added to 2 household composition, be divided into 2 groups, agricultural and non-agricultural residents into facility guideline, be added to outdoor facilities, for example warehouse and open yard, and finally be inserted water quality into environment standard. The results of this study provide insightful strategies for rural housing standard.