• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.97-106
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• 2003

In ARQ based error control, imperfect error detection leaves error remains on a packet. Aiming for a reduction of error remains in multicopy transmission ARQ system, we propose a rule of requesting a retransmission and deciding a correct copy, (identified as $(m, \;{\sigma})$rule). While the probability of error remains is reduced by the employment of the $(m, \;{\sigma})$ rule at multicopy transmission ARQ, delay and throughput performance may be degraded in comparison with those of conventional single copy transmission ARQ. Thus, we develop an analytical method to evaluate the performance trade-off in multicopy transmission ARQ following the $(m, \;{\sigma})$ rule. From the numerical results obtained by the analytical method, we investigate the effect of channel characteristics on the performance of error remains, packet loss, throughput, and packet delay, and confirm that the adaptability of the $(m, \;{\sigma})$ rule to conform to various QoS requirements with ease.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.85-88
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• 2001

In this paper, we propose a retransmission based error control scheme in which a stop-and-wait ARQ is simultaneously performed in two adjacent layers for the node-to-node error control. We develop an analytical numerical method to calculate the probability of error remains and the moments of the high layer message delay time at steady state. Using the analytical method, we investigate the performance of double-layered ARQ scheme with respect to the properties of the employed CRC codes and the characteristics of the involved channel.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.319-322
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• 2002

In this paper, we consider a generalized rule of retransmission request, identified as (Μ, $\sigma$) rule for multicopy transmission ARQ. Following a revised rule to conform with a strict criterion for requesting a retransmission, we can reduce the probability that a packet accepted by the receiving node is still being infected with errors. In turn, such amendment invokes a degradation of delay and throughput performance. For a quantitative evaluation of (Μ, $\sigma$) rule, we develop an analytical method to calculate probability of error remains, maximum throughput, average and peak delays, and delay variation. From the numerical examples made by use of the analytical method, we observe a performance trade-off between probability of error remains and delay/throughput. We also confirm the adaptability of (Μ, $\sigma$) rule to meet various QoS requirements.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.2
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• pp.10-17
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• 2004

A real depth of cut in deformed zone has larger than an ideal depth of cut. So the heat generated during grinding operation makes the deformation of a workpiece surface as convex farm. Consequently the workpiece surface remains a geometric error as concave form after cooling In this study, the grinding force and the geometric error were examined in surface grinding. Through magnitude and mode of geometric error were evaluated according to grinding conditions, an optimal grinding condition was proposed to minimize the geometric error In addition, the relationship between the geometric error and the grinding force was examined. Due to least square regression, It was possible to predict the geometric error by using the grinding force.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.3
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• pp.391-397
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• 2018

This paper proposes a interpolation error compensation method for PMSM torque control. In PMSM torque control, two dimensions look-up table(2D-LUT) is used for current reference generation due to its stable and robust torque control performance. However, the stored data in 2D-LUT is discreet, it is impossible to store all over the operation range. To reduce the reference generation error in this region, the 2D-Interpolation method is conventionally used, however, this method still remains the error affected by the number of stored data. Besides, in the case stored by fixed unit, this error is increased in field weakening region because of the small number of stored data. In this paper, analyzing the cause of this interpolation error, and compensating the method to reduce this error. Proposed method is verified by the simulation and experiment.

• Phonetics and Speech Sciences
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• v.3 no.3
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• pp.181-189
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• 2011

The present study aimed to determine the phonological errors of children in Korean-Vietnamese speaking multicultural families through comparison analyses with those of Korean monolingual peers with phonological disorders. The subjects were 38 children aged about 4-6 years. To examine phonological errors, the Urimal Test of Articulation and Phonation (words) was used. Performances were analyzed by frequency. The results showed some differences between the two groups. There was a tendency for children in Korean-Vietnamese speaking multicultural families to show a higher frequency of phonological errors than Korean monolingual children with phonological disorders. However, the former showed lower error percentages in a few error patterns than the latter such as syllable final consonant deletion, showing similar patterns to those of the normal children. They also showed very unique error patterns such as the highest error percentage in palatal affricates. It remains to be seen if these error patterns are just delay in acquisition or phonological disorders.

• Journal of the Korea Institute of Military Science and Technology
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• v.2 no.2
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• pp.261-270
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• 1999

This paper presents how to evaluate the accuracy and uncertainty of the measuring techniques and the measurement systems, and establish their accreditation procedures. There are largely static error and dynamic error in the measurement error. In particular, the static error which always remains in the measurement systems is obtained by proposed error equations. In addition, the accreditation procedures are proposed.

• Nuclear Engineering and Technology
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• v.56 no.10
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• pp.4087-4096
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• 2024

Despite being developed more than four decades ago based on expert judgment, the THERP time-reliability correlation (TRC) remains widely employed for calculating diagnosis human error probabilities in human reliability analysis for nuclear power plant risk assessment. However, with numerous advancements in nuclear plant equipment and operations, as well as the emergence of plants featuring advanced interfaces, there's a growing need to validate the THERP TRC. The objective of this study is to establish a TRC for the diagnosis human error probability in a modern reference nuclear power plant equipped with up-to-date human-machine interfaces and compare it with the median of the THERP TRC. To achieve this goal, we devised a method to gather event diagnosis times from a simulator and developed procedures to derive diagnosis TRCs using this data. Our findings indicate that while the median of the THERP TRC offers a conservative diagnosis human error probability for up to 25 min, it becomes overly optimistic beyond this threshold.

• Journal of the Korean Operations Research and Management Science Society
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• v.15 no.2
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• pp.97-104
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• 1990

The problem is a variation of the weighted set-covering problem (SCP) which requires the minimum-cost cover to be self-covering. It is shown that direct extension of the well-known greedy heuristic for SCP can have an arbitrarily large error in the worst case. It remains an open question whther these exists a greedy heuristic with a finite error bound.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.10
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• pp.977-987
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• 2012

One of the most significant errors in the pseudo-range measurement performance of GNSSes (Global Navigation Satellite Systems) is their multipath error for high-precision applications. Several schemes to mitigate this error have been studied. Most of them, however, have been focused on the GPS (Global Positioning System) L1 C/A (Coarse/Acquisition) signal that was designed in the 1970s and is still being used for civil navigation. Recently, several modernized signals that were especially conceived to more significantly mitigate multipath errors have been introduced, such as Time Multiplexed and Composite Binary Offset Carrier (TMBOC and CBOC, respectively) signals. Despite this advantage, however, a problem remains with the use of TMBOC and CBOC modulations: the ambiguity of BOC (Binary Offset Carrier)-modulated signal tracking. In this paper, a novel unambiguous multipath error mitigation scheme for these modernized signals is proposed. The proposed scheme has the same complexity as HRCs (High Resolution Correlators) but with low ambiguity. The simulation results showed that the proposed scheme outperformed or performed at par with the HRC in terms of their multipath error envelopes and running averages in the static and statistical channel models. The ranging error derived by the mean multipath error of the proposed scheme was below 1.8 meters in an urban area in the statistical channel model.