• Journal of Korean Society of Steel Construction
• /
• v.10 no.3 s.36
• /
• pp.473-486
• /
• 1998

A numerically stable technique to remove the limitation in choosing a shift in the subspace iteration method with shift is presented. A major difficulty of the subspace iteration method with shift is that because of singularity problem, a shift close to an eigenvalue can not be used, resulting in slower convergence. This study solves the above singularity problem using side conditions without sacrifice of convergence. The method is always nonsingular even if a shift is an eigenvalue itself. This is one of the significant characteristics of the proposed method. The nonsingularity is proved analytically. The convergence of the proposed method is at least equal to that of the subspace iteration method with shift, and the operation counts of above two methods are almost the same when a large number of eigenpairs are required. To show the effectiveness of the proposed method, two numerical examples are considered.

• Computational Structural Engineering
• /
• v.11 no.1
• /
• pp.205-216
• /
• 1998

A solution method is presented to solve the eigenvalue problem arising in the dynamic analysis of nonclassicary damped structural systems with multiple eigenvalues. The proposed method is obtained by applying the modified Newton-Raphson technique and the orthonormal condition of the eigenvectors to the linear eigenproblem through matrix augmentation of the quadratic eigenvalue problem. In the iteration methods such as the inverse iteration method and the subspace iteration method, singularity may be occurred during the factorizing process when the shift value is close to an eigenvalue of the system. However, even though the shift value is an eigenvalue of the system, the proposed method provides nonsingularity, and that is analytically proved. Since the modified Newton-Raphson technique is adopted to the proposed method, initial values are need. Because the Lanczos method effectively produces better initial values than other methods, the results of the Lanczos method are taken as the initial values of the proposed method. Two numerical examples are presented to demonstrate the effectiveness of the proposed method and the results are compared with those of the well-known subspace iteration method and the Lanczos method.

• Clinical and Experimental Pediatrics
• /
• v.46 no.6
• /
• pp.591-596
• /
• 2003

Purpose : Kawasaki disease(KD) is rare in infants <3 months of age. In this younger group, the diagnosis may be delayed due to lack of most of the clinical criteria, resulting in a high risk of cardiac complications. We examined clinical characteristics in these patients for early recognition and treatment. Methods : We conducted a retrospective study on the infants with KD aged three months or younger treated at our hospital from January 1998 to July 2002. Results : Of a total of 291 patients treated during the study period, 11(3.8%) were three months old or younger. Of the 11 patients, 10 had atypical presentations. Infants had fewer of the accepted criteria, and the most common findings were fever(100%) and oral mucosal changes(72.7%). Erythema at the site of BCG inoculation was observed in six of the 11 patients(unknown in the remaining five). This feature proved a definite diagnostic clue in two patients in whom cardiac complications developed in the subacute phase. Cardiac complications were found in six patients(54.5%) : three had coronary dilatation, two had coronary wall irregularity, and one had mitral valve prolapse with regurgitation. Defervescence occurred within $1.1{\pm}0.3day$ in 10 of the 11 patients treated with intravenous immunoglobulin(IVIG) and one was given a second course of IVIG. Echocardiographic abnormality persisted in only one patient with mitral regurgitation at the 6-month follow-up. Conclusion : Most patients with KD younger than three months of age have atypical presentations and a high complication rate. For early diagnosis, erythema at the BCG inoculation site, if present, could be used as a valid diagnostic clue to atypical KD in this age group.

• The KIPS Transactions:PartC
• /
• v.18C no.5
• /
• pp.331-338
• /
• 2011

The RFID system includes a section of wireless communication between the readers and the tags. Because of its vulnerability in terms of security, this part is always targeted by attackers and causes various security problems including the leakage of secret and the invasion of privacy. In response to these problems, various protocols have been proposed, but because many of them have been hardly implementable they have been limited to theoretical description and theorem proving without the accurate verification of their safety. Thus, this study tested whether the protocol proposed by Kenji et al. satisfies security requirements, and identified its vulnerabilities such as the exposure of IDs and messages. In addition, we proposed an improved RFID security protocol that reduced the number of public keys and random numbers. As one of its main characteristics, the proposed protocol was designed to avoid unnecessary calculations and to remove vulnerabilities in terms of security. In order to develop and verify a safe protocol, we tested the protocol using Casper and FDR(Failure Divergence Refinements) and confirmed that the proposed protocol is safe in terms of security. Furthermore, the academic contributions of this study are summarized as follows. First, this study tested the safety of a security protocol through model checking, going beyond theorem proving. Second, this study suggested a more effective method for protocol development through verification using FDR.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.18 no.2
• /
• pp.278-283
• /
• 2008

As the usefulness of internet is kept changing more productively with web 1.0, web 2.0 usage of XML is also increasing very rapidly. In XML environment the most critical function is the ability of effective retrieval of useful information from XML repository. That makes the W3C XQuery more popular XQuery has very complicated structure as a query language due to the semi_structured nature of XML. FLOWOR, which stand for, let. where, order by, return, is the most commonly used expression in XQuery. In this paper we suggest the methods to handle XQuery FLWOR on relational environments. We also analyze and evaluate our approach to prove its correctness.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.5
• /
• pp.586-590
• /
• 2010

In this paper we formally define the linear detrending subsequence matching and propose its efficient index-based solution. To this end, we first present the notion of LD-windows. We eliminate the linear trend from a subsequence rather than each window itself and obtain LD-windows by dividing the subsequence into windows. Using the LD-windows we present a lower bounding theorem of the index-based solution and formally prove its correctness. Based on this lower bounding theorem, we then propose the index building and subsequence matching algorithms, respectively. Finally, we show the superiority of our index- based solution through experiments.

• Journal of KIISE:Computing Practices and Letters
• /
• v.16 no.10
• /
• pp.949-954
• /
• 2010

Computing the rotation-invariant distance between image time-series is a time-consuming process that incurs a lot of Euclidean distances for all possible rotations. In this paper we propose an innovative solution that significantly reduces the number of Euclidean distances using the triangular inequality. To this end, we first present the notion of self rotation distance and show that, by using the self rotation distance with the triangular inequality, we can prune many unnecessary distance computations. We next present that only one self-rotation is enough for all self-rotation distances required. Experimental results show that our self rotation distance-based methods outperform the existing methods by up to an order of magnitude.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
• /
• v.16 no.1
• /
• pp.47-53
• /
• 2005

Objectives : Few studies have examined the relation between the attachment styles of the primary caregivers and the behavioral problems of their children. This study was performed to identify the impact of the insecure parental attachment patterns on the development of their higher grades elementary school children's psychiatric manifestations and disorders. Methods : 504 higher elementary pupils and their primary caretakers were included in our study. Relationship Questionnaire, Kovacs Children's Depression Inventory, Spielberger's State-Trait Anxiety Inventory for children, and Korean Child Behavior Checklist were applied to them. Results : The grade-school children of the parents who belonged to preoccupied attachment type revealed higher Withdrawn, Anxious/depressed, Social Problems, Attention Problems, Delinquent Problems, Aggressive Problems, Internalizing Problems, Externalizing Problems, Total Behavioral Problems scores than ones of securely attached parents (p<0.01). Internalizing Problems score of preoccupied parents' children was highest, and one of avoidant and secure typed parents' kids followed in order (p=0.004) . More youngsters revealed Total Behavior Problem score high enough to clinically meaningful level in insecure parental attachment style than in secure one (p=0.038). Higher CDI score in insecure parental group was reported than in secure one (p=0.040). Conclusion : Parental insecure attachment can be associated with the development of the behavioral problems and psychiatric illness of their children.

• Journal of KIISE:Databases
• /
• v.36 no.4
• /
• pp.327-340
• /
• 2009

To achieve the noise reduction effect in boundary image matching, we use the moving average transform of time-series matching. Our motivation is based on an intuition that using the moving average transform we may exploit the noise reduction effect in boundary image matching as in time-series matching. To confirm this simple intuition, we first propose $\kappa$-order image matching, which applies the moving average transform to boundary image matching. A boundary image can be represented as a sequence in the time-series domain, and our $\kappa$-order image matching identifies similar images in this time-series domain by comparing the $\kappa$-moving average transformed sequences. Next, we propose an index-based matching method that efficiently performs $\kappa$-order image matching on a large volume of image databases, and formally prove the correctness of the index-based method. Moreover, we formally analyze the relationship between an order $\kappa$ and its matching result, and present a systematic way of controlling the noise reduction effect by changing the order $\kappa$. Experimental results show that our $\kappa$-order image matching exploits the noise reduction effect, and our index-based matching method outperforms the sequential scan by one or two orders of magnitude.

• Journal of Digital Convergence
• /
• v.11 no.4
• /
• pp.221-227
• /
• 2013

RFID is an automatic identification technology that can control a range of information via IC chips and radio communication. Also known as electronic tags, smart tags or electronic labels, RFID technology enables embedding the overall process from production to sales in an ultra-small IC chip and tracking down such information using radio frequencies. Currently, RFID-based application and development is in progress in such fields as health care, national defense, logistics and security. RFID structure consists of a reader that reads tag information, a tag that provides information and the database that manages data. Yet, the wireless section between the reader and the tag is vulnerable to security issues. To sort out the vulnerability, studies on security protocols have been conducted actively. However, due to difficulties in implementation, most suggestions are concerned with theorem proving, which is prone to vulnerability found by other investigators later on, ending up in many troubles with applicability in practice. To experimentally test the security of the protocol proposed here, the formal verification tool, CasperFDR was used. To sum up, the proposed protocol was found to be secure against diverse attacks. That is, the proposed protocol meets the safety standard against new types of attacks and ensures security when applied to real tags in the future.