• Journal of Industrial Technology
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• v.22 no.B
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• pp.89-93
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• 2002

When testing products before shipment to the customer, quality characteristics are measured to decide whether or not their values are between the specification limits. Unfortunately, this testing procedure can lead to incorrect decisions because of gauge error. That is, good products can erroneously be qualified as bad, and bad products as good, and this has consequences for producer's and consumer's risk. In cases of such as this, the compressed gauge limit can be used to achieve the desired product quality level dictated by the manufacturer or the customer. A compressed gauge limit is a limit set by the manufacturer on a test gauge that is tighter than the specification limit established by the customer. The compressed gauge limits should be set at levels to achieve the defect levels desired by the customer and simultaneously minimize the loss of good product that is rejected due to errors in the gauges. In this article, the models for determining the defect levels and the losses obtained by adding compressed gauge limits will be developed. A response surface model approach is utilized which allows an optimal operating condition to be generated relatively easily.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.2
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• pp.71-81
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• 2014

Time synchronization system using dual frequency bands is designed and the error sources are analyzed for alternative synchronized-pseudolite navigation system (S-PNS) which aims at military application. To resolve near/far problem, dual frequency band operation is proposed instead of pulsing transmission which degrades level of reception. In dual frequency operation H/W delay should be considered to eliminate errors caused by inter-frequency bias (IFB) difference between the receivers of the pseudolites and users. When time synchronization is performed across the sea, multipath error is occurred severely since the elevation angle between pseudolites is low so total reflection can be happened. To investigate the difference of multipath effects according to location, pseudolites are set up coastal area and land area and performances are compared. The error source related with tropospheric delay is becoming dominant source as the coverage of the PNS is broadening. The tropospheric delay is measured by master pseudolite receiver directly using own pseudorange and slave pseudorange. Flight test is performed near coastal area using S-PNS equipped with developed time synchronization system and test results are also presented.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.54-62
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• 2017

When gears mesh, shock and noise are produced as results of tooth error and tooth deformation under load. Transmission error (TE) is the most important cause of gear noise and vibration because TEs affect the changes of the force and the speed of gears. Gear tooth modification research plays a positive role in reducing TE and improving the design level and transmission performance of transmission systems. In high-precision manufacturing gear, gear tooth modification is also commonly used to reduce noise in practical applications. In order to study the accuracy of gear transmission, some empirical gear profile micro-modifications are introduced, and a helical gear pair is modeled and analyzed in RomaxDesigner software to investigate the utility of these modification methods. Some of these will be selected as experimental proposals for gear pairs, and these manufactured gears will be tested and compared in a semi-anechoic room later. The final purpose of this study is to find reasonable and convenient empirical formulae to facilitate improved gear production.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.04a
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• pp.288-295
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• 2003

An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the recovery technique. In case of the recovery technique, the SPR(superconvergent patch recovery) approach has been modified for p-adaptive mesh refinement. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly. To verify the proposed algorithm, the limit value approach is proposed which utilizes the exact strain energy computed from the extrapolation equation. A new pre-processor is developed for the p-version finite element program in which the vector graphic editor is used for the automatic generation of node connection and coordinate by halfedge solid data structure according to uniform or nonuniform p-distribution. The general 2-D algorithm is also developed to generate face modes and internal modes in accordance with different mesh types. The quality of the error estimator is investigated with the help of two mumerical examples. The results show that the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.

• International Journal of Safety
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• v.9 no.1
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• pp.30-34
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• 2010

A big difference is seen in the perception of self-responsibility concerning safety, as a result of my survey on the safety measures taken in the pipeline construction at workers level between Japan and Indonesia. Specifically, when an accident occurs, a worker in Indonesia will think that the responsibility depends on the person who causes it. However a worker in Japan will think that safety is can only be protected by law and regulations. There is also another difference in the understanding of construction period. It is alright in Indonesia to take 5 times longer period than it takes in Japan if the cost is less. The idea of punctual delivery is very strong in Japan. Through this survey, points which construction industry in Japan could learn from Indonesia came to surface. In addition, over the recent years, several nasty accidents at Japanese sites were caused due to human error to disregard the law. Japanese should arouse the awareness of self-responsibility in this regard. Risk management should be upon self-recognition of each individual worker in both countries. What is important is the "work attitude education", "to grow sense of self-responsibility by thinking on one's own for one's self" in the education curriculum of man to man learning as in technical educational program.

• Journal of applied mathematics & informatics
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• v.14 no.1_2
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• pp.461-471
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• 2004

In recent years, large volumes of data are transferred between a computer system and various subsystems through digital logic circuits and interconnected wires. And there always exist potential errors when data are transferred due to electrical noise, device malfunction, or even timing errors. In general, parity checking circuits are usually employed for detection of single-bit errors. However, it is not sufficient to enhance system reliability and availability for efficient error detection. It is necessary to detect and further correct errors up to a certain level within the affordable cost. In this paper, we report a generation of 3-distance code using the characteristic matrix of a PBCA.

• Tribology and Lubricants
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• v.27 no.1
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• pp.13-18
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• 2011

The ultra-precision products which recently experienced high in demands had included the large areas of most updated technologies, for example, the semiconductor, the computer, the aerospace, the media information, the precision machining. For early 21st century, it was expected that the ultra-precision technologies would be distributed more throughout the market and required securing more nation-wise advancements. Furthermore, there seemed to be increasing in demand of the single crystal diamond tool which was capable of the ultra-precision machining for parts requiring a high degree of complicated details which were more than just simple wrapping and policing. Moreover, the highest degree of precision is currently at 50 nm for some precision parts but not in all. The machining system and technology should be at very high performed level in order to accomplish this degree of the ultra-precision.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.51-55
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• 2000

Objectives . In large-scale field trials, randomization by cluster is frequently used because of the administrative convenience, a desire to reduce the effect of treatment contamination, and the need to avoid ethical issues that might of otherwise arise. Cluster randomization trials are experiments in which intact social unit, e.g., families, schools, cities, rather than independent individuals are randomly allocated to intervention groups. The positive correlation among responses of subjects from the same cluster is in matter in cluster randomization. This thesis is to compare the results of three randomization methods by standard error of estimator of treatment effect. Methods : We simulated cholesterol data varing the size of the cluster and the level of the correlation in clusters and analyzed the effect of cholesterol-lowering agent. Results : In intra-cluster randomization the standard error of the estimator of treatment effect is smallest relative to that in inter-cluster randomization and that in individual randomization. Conclusions : Infra-cluster randomization is the most efficient in its standard error of estimator of treatment effect but other factor should be considered when selecting a specific randomization method.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.3
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• pp.50-59
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• 2014

It has been focused on that the major reasons of aircraft accidents resulted not from human error but from the failure of teamwork or communication in 1980's. Such opinions were suggested in the workshop, so called, "Resource Management on the Flight Deck" by NASA in 1979. The researchers agreed the fact the source of human error was originated from the failure in teamwork, communication or even in leadership of captain. Due to the rapid development of aircraft technologies, the reasons for aircraft accident could be easily found out. According to the analysis results of the technology, most of reasons for the accident might directly be connected not to human error or stick-Rudder skill but to situational awareness, communication, leadership or decision making in the aircraft. This paper has tried to research empirically the satisfaction of flight crews who have gone thorugh CRM training in the commercial airline. Based on the quantitative scale by J. Ford et al. (2014), this paper has proved which characteristics of CRM training has a positive impact on the overall satisfaction of CRM training. It was proven that the teamwork and decision making programs among CRM training have a major effect to the satisfaction level of flight crews.

• Journal of Environmental Science International
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• v.24 no.4
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• pp.393-401
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• 2015

Rainfall-runoff model of Jeju Oedo Stream was used to compute the optimal unit hydrograph by HEC-HMS model that reflecting on watershed characteristics. Each rainfall event was comparatively analyzed with the actual flow measurement using Clark, Snyder and SCS synthetic methods for derived unit hydrograph. Subsequently, the null hypothesis was established as p-value for peak flow and peak time of each unit hydrograph by one-way ANOVA(Analysis of variance) was larger than significance level of 0.05. There was no significant difference in peak flow and peak time between different methods of unit hydrograph. As a result of comparing error rate with actual flow measurement data, Clark synthetic unit graph best reflected in Oedo Stream as compared to other methods, and error rate of Clark unit hydrograph was 0.02~1.93% and error rate at peak time was 0~2.74%.