• The Korean Journal of Applied Statistics
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• v.24 no.1
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• pp.11-23
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• 2011

Robust unit root tests are developed for dynamic panels consisting of TAR processes. The test statistics are all based on diverse combinations of individual t-type tests for significance of TAR coefficients. Limiting null distributions are established. A Monte-Carlo experiment compares the proposed tests. The tests are applied to a panel data set of Canadian unemployment rates which show asymmetric features as well as having outliers.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.1
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• pp.21-31
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• 2019

This paper examines how corporate social responsibility is related to the degree of asymmetric information in the Korean financial market. Recent theory argues that there is a negative relationship between a firm's corporate social responsibility and its information asymmetry. To test this hypothesis, we use the environment, social and governance (ESG) score, published by the Korean Corporate Governance Service, to proxy a firm's management practices toward socially responsible activities. In the entire sample of the Korean firms, we find contrasting results; the ESG score shows negative relationships with the price impact measure but statistically insignificant relationships with the dispersion of analyst forecasts. However, the ESG score shows negative relationships with both measures when we exclude chaebol affiliates from the sample. These findings are robust when we examine environmental, social and corporate governance scores separately. This set of results argues for the extant theory, expecting a negative relationship between a firm's engagement in corporate social responsibility and asymmetric information. It further argues for the importance of firm characteristics in determining the influence of socially responsible activities.

• Journal of Korea Multimedia Society
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• v.6 no.4
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• pp.620-629
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• 2003

Fingerprinting schemes are techniques applied to protect the copyright on digital goods. These enable the merchants to identify the source of illegal redistribution. Let us assume the following situations connectedly happen: As a beginning, buyer who bought digital goods illegally distributed it, next the merchant who found it revealed identity of the buyer/traitor, then the goods is illegally distributed again. After this, we describe it as“The second illegal redistribution”. In most of anonymous fingerprinting, upon finding a redistributed copy, a merchant extracts the buyer's secret information from the copy and identifies a traitor using it. Thus the merchant can know the traitor's secret information (digital fingerprints) after identification step. The problem of the second illegal distribution is that there is a possibility of the merchant's fraud and the buyer's abuse: that is a dishonest employee of the merchant might just as well have redistributed the copy as by the buyer, or the merchant as such may want to gain money by wrongly claiming that the buyer illegally distributed it once more. The buyer also can illegally redistribute the copy again. Thus if the copy turns up, one cannot really assign responsibility to one of them. In this paper, we suggest solution of this problem using two-level fingerprinting. As a result, our scheme protects the buyer and the merchant under any conditions in sense that (1) the merchant can obtain means to prove to a third party that the buyer redistributed the copy. (2) the buyer cannot worry about being branded with infamy as a traitor again later if he never distribute it.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.833-843
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• 2021

This research examines the impact of audit quality on the extent to which firm-specific information is integrated with a firm's share price - which is determined inversely using stock price synchronicity. The study sample consists of non-financial companies listed on the Amman Stock Exchange i.e., the Jordanian Stock Market, from 2014-2018. After examining 810 firm-year observations from Jordanian industrial companies listed on the ASE, during the study period, we find that the companies using one of the BIG4 audit firms for auditing have less synchronous and more informative stock prices, suggesting high-quality audit improved governance and reduce information asymmetry between firms' insiders and investors which enhances the capitalization of firm's specific information into the stock price, thus less synchronous and more informative stock return. The findings remain consistent over 2 separate measurements of stock price synchronicity (Market and Industry model and Market Model) and show robustness for fixed effect tests. Our multivariate regression results are also robust after controlling for a number of features at the firm level with potential associations with stock price synchronicity. These include the firm size, leverage, return on assets (ROA), and market to book value (MBV).

• The Journal of Asian Finance, Economics and Business
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• v.9 no.1
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• pp.133-142
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• 2022

This study examines the relationship between debt maturity structure and bankruptcy risk. There are various studies of leverage's effect on bankruptcy risk. Debt maturity, however, has not received the attention it deserves, especially in emerging markets with a high degree of information asymmetry. Using Vietnamese listed company data and various estimations, we find that leverage is positively associated with the likelihood of default. Importantly, short-term leverage shows a significantly positive effect on bankruptcy risk, while long-term leverage does not show significant results. The findings highlight that rollover risk firms are exposed to when using short-term debt increases bankruptcy risk. Meanwhile, firms do not cope with this risk in case of long-term debt adoption. High information asymmetry in emerging markets may be the main reason for the difference. The result is robust for subsamples of firms in different financial conditions, in concentrated and competitive industries, as well as for manufacturing and non-manufacturing companies. We also find that firms in a better financial situation and concentrated industries experience a higher short-term leverage effect than their counterparts. We, however, do not find a significant difference in the impact between manufacturing and non-manufacturing companies. This paper is among the first to examine the relation between debt maturity and bankruptcy risk in Vietnam.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2375-2393
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• 2016

Key agreement is paramount in secure wireless communications. A promising approach to address key agreement schemes is to extract secure keys from channel characteristics. However, because channels lack randomness, it is difficult for wireless networks with stationary communicating terminals to generate robust keys. In this paper, we propose a Robust Secure Key Agreement (RSKA) scheme from Received Signal Strength (RSS) in stationary wireless networks. In order to mitigate the asymmetry in RSS measurements for communicating parties, the sender and receiver normalize RSS measurements and quantize them into q-bit sequences. They then reshape bit sequences into new l-bit sequences. These bit sequences work as key sources. Rather than extracting the key from the key sources directly, the sender randomly generates a bit sequence as a key and hides it in a promise. This is created from a polynomial constructed on the sender's key source and key. The receiver recovers the key by reconstructing a polynomial from its key source and the promise. Our analysis shows that the shared key generated by our proposed RSKA scheme has features of high randomness and a high bit rate compared to traditional RSS-based key agreement schemes.

• Language and Information
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• v.15 no.2
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• pp.1-21
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• 2011

Of the coordination structures in Korean, the symmetric and asymmetric properties of verbal coordination have challenged both theoretical and computational approaches. This paper shows how a typed feature structure grammar, HPSG, together with the notions of 'type hierarchy' and 'constructions', can provide a robust basis for parsing (un)tensed verbal coordination as well as pseudo-coordination found in the language. We show that the analysis sketched here and computationally implemented in the existing resource grammar for Korean, Korean Resource Grammar (KRG), can yield proper syntactic structures as well as enriched semantic representations for real-time applications such as machine translation.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.457-461
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• 2001

Advantages of switched reluctance motor(SRM) drives make it an attractive candidate for replacing adjustable speed ac and dc drives in both industrial and consumer applications. Furthermore, a simple, low cost and robust SRM drive can be efficiently operated in the hostile environment of an automobile. Generally, the speed control of SRM has a large step change or large torque reference, the output of its PI controller is often saturated. When this happens, the integral state is not consistent with the SRM input, while may give rise to the windup phenomenon. This paper proposes anti-windup control method for SRM speed control system by hysteresis current controlled asymmetry bridge converter. The experimental results show that the speed response has much improved performance, such as a small overshoot and fast settling time at the acceleration and particulary deceleration period with braking mode.

• Structural Engineering and Mechanics
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• v.26 no.4
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• pp.459-477
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• 2007

A bi-directional tuned mass damper (BTMD) in which a mass connected by two translational springs and two viscous dampers in two orthogonal directions has been introduced to control coupled lateral and torsional vibrations of asymmetric building. An efficient control strategy has been presented in this context to control displacements as well as acceleration responses of asymmetric buildings having asymmetry in both plan and elevation. The building is idealized as a simplified 3D model with two translational and a rotational degrees of freedom for each floor. The principles of rigid body transformation have been incorporated to account for eccentricity between center of mass and center of rigidity. The effective and robust design of BTMD for controlling the vibrations in structures has been presented. The redundancy of optimum design has been checked. Non dominated sorting genetic algorithm (NSGA) has been used for tuning optimum stages and locations of BTMDs and its parameters for control of vibration of seismically excited buildings. The optimal locations have been observed to be reasonably compact and practically implementable.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.415.2-415.2
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• 2014

Cost-effective, robust devices for solid-state lighting industry that converts electricity to light revolutionize the current lighting industry. Phosphor materials used in these devices should be synthesized in a low-cost and effective method for use in WLEDs. In this presentation, the synthesis of Eu3+ ions doped BaMoO4 phosphor samples by a facile synthesis process for red component of WLEDs will be shown. The tetragonal phase of the host lattice was substantiated by the X-ray diffraction patterns. The morphological studies were carried out by using a field-emission scanning electron microscope and transmission electron microscope. These confirmed the formation of a shuttle like particles with perpendicular protrusions in the middle of the particle. The photoluminescence (PL) properties exhibited good emission with a high asymmetry ratio when excited with ultraviolet B wavelengths (~ 280-315 nm). The cathodoluminescence (CL) spectra showed similar results to the PL spectra, indicating the rich red emission. The results suggest that this phosphor is a good material as red region component in the development of tri-band UV excitation based WLEDs.