534 research outputs found

    The Effect Of Corporate Governance On Unfaithful Disclosure Designation And Unfaithful Disclosure Penalty Points

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    This paper investigates the relation between Unfaithful Disclosure Corporations (ā€œUDCā€) and corporate governance using listed firm (KOSPI and KOSDAQ) data in Korea. Prior literature reports that corporate governance has an impact on the level of disclosure and the quality of disclosure provided by companies. However, it is hard to find the studies about corporate governance and UDC at the term of disclosure quality. Compare to some financially advanced countries, Korea established corporate governance in a relatively short period of time; hence concerns have been raised the corporate governance have not played effective role to monitor management. We question how corporate governance affects companiesā€™ unfaithful disclosure by using several corporate governance proxy variables and UDC data which is unique system in Korea. From the empirical tests, we find a negative association between the proportion of outside directors, an indicator of the boardā€™s independence, and UDC designation, among companies listed on both KOSPI and KOSDAQ. On the other hand, there is a significant positive association between the proportion of outside directors and UDCsā€™ imposed and accumulated penalty points among KOSDAQ-listed companies. This implies that outside director system effectively play a monitoring role however due to different natures of members included in outside directors, the system often fails to control regarding based reasons for penalty points imposition. In addition, we find the percentage of foreign equity ownership showed statistically significant positive association with UDC designation and a significant positive association with the imposed and accumulated penalty points among KOSPI-listed companies. We interpret this results that foreign investors with a short-term investment propensity may not enough to play a proper monitoring role in Korea and thereby they cannot effectively control the disclosure quality provided by the management. We also find that there is a significant positive association between the percentage of managerial ownership and UDC designation in the KOSDAQ market.   This study will contribute to academics and disclosure-related practitioners by documenting about corporate governance and its impact on unfaithful disclosure corporations

    Chosen-ciphertext Clustering Attack on CRYSTALS-KYBER using the Side-channel Leakage of Barrett Reduction

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    This study proposes a chosen-ciphertext side-channel attack against a lattice-based key encapsulation mechanism (KEM), the third-round candidate of the national institute of standards and technology (NIST) standardization project. Unlike existing attacks that target operations such as inverse NTT and message encoding/decoding, we target Barrett Reduction in the decapsulation phase of CRYSTALS-KYBER to obtain a secret key. We show that a sensitive variable-dependent leakage of Barrett Reduction exposes an entire secret key. The results of experiments conducted on the ARM Cortex-M4 microcontroller accomplish a success rate of 100%. We only need six chosen ciphertexts for KYBER512 and KYBER768 and eight chosen ciphertexts for KYBER1024. We also show that the m4 scheme of the pqm4 library, an implementation with the ARM Cortex-M4 specific optimization (typically in assembly), is vulnerable to the proposed attack. In this scheme, six, nine, and twelve chosen ciphertexts are required for KYBER512, KYBER768, and KYBER1024, respectively

    A Statistical Verification Method of Random Permutations for Hiding Countermeasure Against Side-Channel Attacks

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    As NIST is putting the final touches on the standardization of PQC (Post Quantum Cryptography) public key algorithms, it is a racing certainty that peskier cryptographic attacks undeterred by those new PQC algorithms will surface. Such a trend in turn will prompt more follow-up studies of attacks and countermeasures. As things stand, from the attackers' perspective, one viable form of attack that can be implemented thereupon is the so-called "side-channel attack". Two best-known countermeasures heralded to be durable against side-channel attacks are: "masking" and "hiding". In that dichotomous picture, of particular note are successful single-trace attacks on some of the NIST's PQC then-candidates, which worked to the detriment of the former: "masking". In this paper, we cast an eye over the latter: "hiding". Hiding proves to be durable against both side-channel attacks and another equally robust type of attacks called "fault injection attacks", and hence is deemed an auspicious countermeasure to be implemented. Mathematically, the hiding method is fundamentally based on random permutations. There has been a cornucopia of studies on generating random permutations. However, those are not tied to implementation of the hiding method. In this paper, we propose a reliable and efficient verification of permutation implementation, through employing Fisher-Yates' shuffling method. We introduce the concept of an n-th order permutation and explain how it can be used to verify that our implementation is more efficient than its previous-gen counterparts for hiding countermeasures.Comment: 29 pages, 6 figure

    Diagnostic Value of Galectin-3, HBME-1, Cytokeratin 19, High Molecular Weight Cytokeratin, Cyclin D1 and p27kip1 in the Differential Diagnosis of Thyroid Nodules

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    The distinction between benign and malignant thyroid tumors is critical for the management of patients with thyroid nodules. We applied immunohistochemical staining for galectin-3, HBME-1, cytokeratin 19 (CK19), high molecular weight cytokeratin (HMWCK), cyclin D1 and p27kip1 in 295 thyroid lesions to determine their diagnostic accuracy. The expression of all markers was significantly associated with differentiated thyroid carcinoma (DTC).The sensitivity for the diagnosis of DTC was 94.7% with galectin-3, 91.3% with HBME-1, and 90.3% with CK19. The specificities of these markers were 95.5%, 69.7%, and 83.1%, respectively. Combining these markers, co-expression of galectin-3 and CK19 or galectin-3 and HBME-1 was seen in 93.2% of carcinomas but in none of the benign nodules. Comparing follicular variant of papillary carcinoma (FVPC) with follicular carcinoma (FC), the expression of galectin-3, CK19, and HMWCK was significantly higher in FVPC. When comparing FC with FA, the expression of galectin-3 and HBME-1 was significantly higher in FC. These results suggest that 1) galectin-3 is a useful marker in the distinction between benign and malignant thyroid tumors, 2) the combined use of HBME-1 and CK19 can increase the diagnostic accuracy, and 3) the use of CK19 and HMWCK can aid in the differential diagnosis between PC and FC

    Comparative outcomes of the pathogen in cultured Jones tubes used in lacrimal bypass surgery according to follow up periods

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    AIM: To evaluate the pathogens in cultured Jones tubes used in lacrimal bypass surgery according to the postoperative periods and to obtain data for the prevention of infection of functional lacrimal stent invention. METHODS: Totally 71 patients (81 eyes) who underwent the removal of Jones tubes were enrolled in study. All the removed Jones tubes were cultured for bacterial and fungal identification and tested for bacterial antibiotic sensitivity. The results were analyzed according to the duration of the inserted Jones tube after lacrimal bypass surgery. RESULTS: Of the 81 eyes, bacteria were isolated from 69 eyes (85.2%) and fungi from 6 eyes (7.4%). Among 69 eyes, 40.6% showed Staphylococcus aureus (S. aureus), 11.6% were Pseudomonas aeruginosa (P. aeruginosa). Gram-positive bacteria were isolated more than Gram-negative bacteria, but Gram-negative bacteria showed a higher incidence in the Jones tube implanted for over 10y (P=0.035). The antibiotic sensitivity test showed that 46.4% of S. aureus were resistant to oxacillin. In terms of antibiotics commonly used in ocular clinical practice, vancomycin was sensitive to S. aureus and Streptococcus pneumoniae (S. pneumoniae), amikacin responded to P. aeruginosa and Proteus mirabilis (P. mirabilis). Trimethoprim/sulfamethoxazole (TMP/SMX) was all sensitive to S. aureus, S. pneumoniae and P. mirabilis except P. aeruginosa. CONCLUSION: S. aureus is the most commonly found organism in the Jones tube after lacrimal bypass surgery, and 46.4% of them are methicillin-resistant S. aureus (MRSA), sensitive to vancomycin. Especially, P. mirabilis responded with amikacin is dominantly detected in the Jones tubes implanted for more than 10y

    A Statistical Verification Method of Random Permutations for Hiding Countermeasure Against Side-Channel Attacks

    Get PDF
    As NIST is putting the final touches on the standardization of PQC (Post Quantum Cryptography) public key algorithms, it is a racing certainty that peskier cryptographic attacks undeterred by those new PQC algorithms will surface. Such a trend in turn will prompt more follow-up studies of attacks and countermeasures. As things stand, from the attackersā€™ perspective, one viable form of attack that can be implemented thereupon is the so-called ā€œside-channel attackā€. Two best-known countermeasures heralded to be durable against side-channel attacks are: ā€œmaskingā€ and ā€œhidingā€. In that dichotomous picture, of particular note are successful single-trace attacks on some of the NISTā€™s PQC then-candidates, which worked to the detriment of the former: ā€œmaskingā€. In this paper, we cast an eye over the latter: ā€œhidingā€. Hiding proves to be durable against both side-channel attacks and another equally robust type of attacks called ā€œfault injection attacksā€, and hence is deemed an auspicious countermeasure to be implemented. Mathematically, the hiding method is fundamentally based on random permutations. There has been a cornucopia of studies on generating random permutations. However, those are not tied to implementation of the hiding method. In this paper, we propose a reliable and efficient verification of permutation implementation, through employing Fisherā€“Yatesā€™ shuffling method. We introduce the concept of an -th order permutation and explain how it can be used to verify that our implementation is more efficient than its previous-gen counterparts for hiding countermeasures

    New Heteroleptic Cobalt Precursors for Deposition of Cobalt-Based Thin Films

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    A new series of heteroleptic complexes of cobalt were synthesized using aminoalkoxide and ??-diketonate ligands. The complexes, [Co(dmamp)(acac)]2 (3), [Co(dmamp)(tfac)]2 (4), [Co(dmamp)(hfac)]2 (5), [Co(dmamp)(tmhd)]2 (6), and [Co(dmamb)(tmhd)]2 (7), were prepared by two-step substitution reactions and studied using Fourier transform infrared spectroscopy, mass spectrometry, elemental analysis, and thermogravimetric analysis (TGA). Complexes 3-7 displayed dimeric molecular structures for all of the complexes with cobalt metal centers interconnected by ??2-O bonding by the alkoxy oxygen atom. TGA and a thermal study of the complexes displayed high volatilities and stabilities for complexes 6 and 7, with sublimation temperatures of 120 ??C/0.5 Torr and 130 ??C/0.5 Torr, respectively
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