• The Transactions of the Korean Institute of Power Electronics
• /
• v.20 no.6
• /
• pp.491-497
• /
• 2015

This study proposes a new control method for a resistance spot welding inverter to improve weld quality. The proposed method is based on the dynamic resistance characteristics of steel sheets to be welded. A point in the second peak value of the dynamic resistance occurs during one shot of the welding current flow. A constant voltage control is applied from zero to the peak point, and a constant current control is adopted from the peak point to the end of the shot. The mixed mode control of the constant voltage and current guarantees high weld quality. Experiments are conducted with a 5 kA power supply and 0.5 mm steel sheets to compare quality. Experimental results show that weld quality is improved more than 10 times that of the conventional control method.

• Journal of Korean Society for Quality Management
• /
• v.43 no.1
• /
• pp.57-66
• /
• 2015

Purpose: The purpose of this study is to apply the constrained Bayesian estimation methodology for product quality control process and prove the effectiveness of the product management by comparing with the well-known Bayes estimator through data performance result. Methods: The Bayes and constrained Bayes estimators were produced based on the theoretical background and for confirming the effectiveness of suggested application, the deviation index was defined and calculated for the comparison. Results: The statistical analysis result shows that applying the suggested estimation methodology, that is, constrained Bayes estimator improves the effectiveness of the index with regard to reduce the error by matching the first two empirical moments. Conclusion: Considering the advanced Bayesian approaches such as constrained Bayes estimation for the product quality control process, the newly defined deviation index reduces the error for estimating the parameter histogram which is reflected both location and deviation parameters and furthermore various Bayesian perspective approaches seems to be meaningful for managing the product quality control process.

• Journal of Korean Society for Quality Management
• /
• v.21 no.1
• /
• pp.44-54
• /
• 1993

Factory Automation is being implemented rapidly in almost of industries. This new trend and technology have a great influence on even traditional quality control system, and make it be changed with new approaches and methodologies. In these environments, this study has brief review on automation and quality control system, gives checkpoints of the automation system design with the viewpoint of quality control. Also this study proposes a detail system configuration and specifications of each system conponent in the configuration. In the last, a brief implementation guideline for the automation system in the scope of information technology is also presented.

• Journal of Broadcast Engineering
• /
• v.6 no.2
• /
• pp.148-159
• /
• 2001

This paper presents a selective duality control system to control relative picture quality among the video programs in terms of Peak Signal-to-Noise Ratio (PSNR) . The selective quality control system allows variable bit rate (VBR) for each video program to maintain the pre-determitted relative picture Quality among aggregated video programs while keeping a constant bit rate for alt programs to be transmitted over a single constant bit rate (CBR) channel. Thus is achieved by simultaneous controlling the video encoders to generate VBR video streams at the central controller. furthermore, we also suggest a buffer regulation method based on the analysis of the constraints Imposed by sender/receiver buffer sizes and the total transmission rate. Through various simulation results, it is found that the proposed quality control system guarantees that the video buffers neither overflow nor underflow and the quality control errors do not exceed 0.1 dB.

• Proceedings of the Safety Management and Science Conference
• /
• 1999.11a
• /
• pp.53-72
• /
• 1999

IPQC system was introduced for the flight safety at the age of scientific safety management in the 1980s. In spite of performing this system, aircraft accidents caused by human factors, which were above 70% among all flight accident factors, have not been reduced. Accordingly, throughout this paper I analyzed the aircraft accident factors by means of a literature study and a pilot survey. Then, based on the notion of TQC(Total Quality Control), I hierarchically classified Individual Quality into Capacity Management, Safety Management, and General Management and did the low-ranked management factors as well. AHP (Analytic Hierarchy Process), one of the scientific management methods, was used for estimating the relative importance of Individual Quality Control factors and the heavy aircraft accident causes over the last 20 years were analyzed according to the flight ranks. Based on the comparative analysis of results derived above, an IPQC model as flight ranks is established. In short, according to this newly suggested model we can obtain the maximum flight safety with the preventive actions against aircraft accidents caused by human factors and by improving the operation effect under the reasonable pilot management.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.6
• /
• pp.1480-1489
• /
• 1996

In ATM networks there are two methods in traffic control as schemes advancing the quality of service. One is reactive control after congestion and the other which is generally recommended, is preventive control before congestion, including connection admission control on call leel and usage parameter control, network parameter control, priority control and congestion control on cell level. In particular, usage parameter control is required for restricting the peak cell rate of bursy tracffic to the parameter negotiated at call set-up phase since the peak cell rate significantly influences the network quality of service. The scheme for progressing quality of service by usage parameter control is themethod using VSA(Virtual Scheduling Algorlithm) recommended ITU-T. The method using VSSA(Virtual Scheduling Suggested Algorlithm) in this paper is suggested by considering cell delay variation and token rate of leaky bucket, compared VSA and VSANT(Virtual Scheduling Algolithm with No Tolerance) with VSSA which polices violated cell probability of conformed peak cell rate and intentionally excessive peak cell rate. VSSA method using IPP(Interruped Poisson Process) model of input traffic source showed more quality of service than VSA and VSANT methods as usage parameter control because the suggested method reduced the violated cell probability of contformed peak cell rate and intentionally excessive peak cell rate.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.34S no.9
• /
• pp.84-90
• /
• 1997

We proposed a new bit-rate control algorithm to improve MPEG-2 video software encoder. Bit-rate Control plays an improtant role in picture quality of MPEG-2 encoder. To achieve better encoding performance such as controlling picture quality and using bity properly, we proposed a MPEG-2 bit-rate control algorithm using linear average Step-Size. Using a benchmark Program, we compared our algorithm with MPEG-2 Test Model 5. Our proposed algorithm showed better Bit-Rate Control with respect to used bits, picture quality.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.9 no.4
• /
• pp.260-267
• /
• 2007

This research note introduces the procedure of the quality control and quality assurance applied to the eddy covariance data collected at the two KoFlux sites (i.e., Gwangneung forest and Haenam farmland). The quality control was conducted through several steps based on micrometeorological theories and statistical tests. The data quality was determined at each step of the quality control procedure and was denoted by five different quality flags. The programs, which were used to perform the quality control, and the quality assessed data are available at KoFlux website (http://www.koflux.org/).

• Asian-Australasian Journal of Animal Sciences
• /
• v.21 no.1
• /
• pp.138-143
• /
• 2008

A study was conducted to evaluate nutritional value for twenty-one pork muscles. Ten market-weight crossbred pigs (five gilts and five barrows) were used for evaluating proximate chemical composition, cholesterol, total iron, calorie and fatty acid contents. As preliminary analysis revealed no noticeable sex effect, pooled data from both sexes were used for the final analysis. M. rectus femoris had the highest moisture content, while m. latissimus dorsi was lowest in moisture content (p<0.05). Protein content was highest for m. longissimus dorsi and lowest for m. supraspinatus (p<0.05). The tensor fasciae and latissimus dorsi muscles contained the highest intramuscular fat (p<0.05), while rectus femoris, adductor and vastus lateralis were lowest in intramuscular fat content. When simple correlations between chemical values were computed for the pooled dataset from all muscles, intramuscular fat had significant (p<0.05) negative linear relationships with moisture (r = -0.85) and protein (r = -0.51) contents. Calorie levels were not significantly affected by fat content, while rectus femoris and latissimus dorsi muscles showed lowest and highest calorie contents, respectively (p<0.05). Polyunsaturated fatty acid content was highest (p<0.05) for both m. adductor and m. rectus femoris, while it was lowest for m. longissimus dorsi. Collectively, the current study identified a large amount of variation in nutritional characteristics between pork muscles, and the data can be used for the development of muscle-specific strategies to improve eating quality of meats and meat products.

• Korean Journal of Digital Imaging in Medicine
• /
• v.12 no.2
• /
• pp.71-79
• /
• 2010

Thanks to the great development of technology in radiation, we are now able to reduce radiation exposure to the patients, and the radiographer and expenses in medical sector. We are also trying to produce ideal images which maintain useful information. These kinds of effort are increasing over the world. For that reason, we should get images which include necessary data of patients. Then it also can help to reduce radiation exposure to the patients. Therefore, we need to know the problems that cause a falling off in image's quality and check on generator in case of their electronic and mechanical errors. And moreover, we should anticipate the possibility of devices errors and prevent them with regular quality control. This investigation was conducted in medical institutions, institute of educations and hospitals. They are all in Seongnam-City. We used PMX-III, kVp meter to implement kVp test, mR / mAs output test, light fiel / beam alignment test, Reproducibility of exposure dose, half value layer test, reproducibility of exposure time test. in the case of hospitals, they perceive the importance of regular quality control and organize the regular quality control team so they can be satisfied with the error standard in most experiments. On the other hand, when it comes to medical institutions and institute of educations, they perceive the importance of regular quality control less than hospitals do. Radiographer need to understand the importance of regular quality control and practice it so they can get the fine ideal image with the lower dose to the patient.