• Journal of Digital Convergence
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• v.11 no.10
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• pp.737-746
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• 2013

This research aim is to investigate the rate and pattern of re-using the four-digit personal identification numbers(PINs). 1313 types of PINs were observed by 224 students who took this author's classes from last 2006 to 2011 at A-university. Some students used PINs as few as 3-4 and as many as 12-13. The average is 5.86 per person. The rates of re-using PINs were calculated by each student. 87%(195/224) of students reused PINs and 64% of them reused with just only one type of PINs, 20% reused with 2 types, and about 3% reused with 3-4 types. With respect to PINs, 884 out of the total 1313 PINs were reused, that is around 64.3%. In a broad sense, a pair of slight modification of PINs were also observed, that is, new PINs were partly matched in position or size of numbers of previous PINs. And if the reuse rate falling under the slight modification of PINs, 10.4% is added, about 75% of the PINs were reused in a broad sense. The re-using rate of male students is higher than the one of female students. This paper's results may provide to make plan for hacks of passwords.

• Smart Media Journal
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• v.9 no.4
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• pp.52-59
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• 2020

This second survey, which collected 2392 disclosing grades data for 2012~ 2017, nearly twice the first survey, was conducted to supplement the result of the first survey on the reuse of 4-digit passcodes(PCs) data. In addition of second survey, we found that the more number of used PCs, the higher reuse rate, up to 4 numbers of PCs were used for reusing and there may be personal differences even on the single site. The results of this paper that were not available in the first survey were close to the those of foreign research on the reuse of passwords using a mixture of numbers, letters and special characters. This second survey provided an inference that an opportunity to indirectly approach the domestic situation of re-using password, where data collection is impossible and that domestic regulation such as periodic change of password may increase the re-using password.

• Journal of Convergence for Information Technology
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• v.8 no.6
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• pp.159-164
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• 2018

This paper deals with the comparative analysis the two surveys called term1, term2 by collecting 4-digit password data 1313 for 2006~2011 and 2519 for 2012~ 2017. Numbers lacking prudence were significantly reduced in the term2 survey and over time, the use of four digit PWs became increasingly prudent. There was a difference in the use of digit numbers between male and female. The top five types accounted over 60%, which imply that certain types of preferences are present. It was the outcome of this paper that we can indirectly deduce these facts. Studies such as reuse of four digit PWs in user's convenience will need to be supplemented in the near future.

• The KIPS Transactions:PartC
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• v.15C no.3
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• pp.213-220
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• 2008

A MANET is an autonomous, infrastructureless system that consists of mobile nodes. In MANET, on-demand routing protocols are usually used because network topology changes frequently. The current approach in case of broken routes is to flag an error and re-initiate route discovery either at the source or at the intermediate node. Repairing these broken links is a costly affair in terms of routing overhead and delay involved. Therefore, this paper propose a NAODV(Neighbor-aware AODV) protocol that stands on the basis of an AODV. It sets up the route rapidly if it operates for setting the route directly by using sequence number of neighbor nodes without re-search the route when the route to destination node is broken. Also, it reduces loss of packets. We use NS-2 for the computer simulation and validate that the proposed scheme is better than general AODV in terms of packet delivery ratio and average end-to-end delay. Also, when the proposed protocol is applied to the large ad-hoc network with multiple nodes, the performance is more efficient.