사이버 훈련 환경에 시험트래픽 공급을 위한 Hidden Router 개념

김광수(Kwangsoo Kim),홍수연(Su-Youn Hong),김태규(Taekyu Kim),김동화(Donghwa Kim),김용현(Yong-Hyun Kim) 한국통신학회 2018 한국통신학회 학술대회논문집 Vol.2018 No.6

Aza-[4+3] and Aza-[3+2] Annulations for Synthesis of Dihydroazepines and Dihydropyrroles from Alkynes, Sulfonyl Azides, and 1,3-Dienes

Kim, Sanghyuck,Mo, Juntae,Kim, Jaeeun,Ryu, Taekyu,Lee, Phil Ho Wiley (John WileySons) 2014 ASIAN JOURNAL OF ORGANIC CHEMISTRY Vol.3 No.9

Fast Auto-focus Control Algorithm Using the VCM Hysteresis Compensation in the Mobile Phone Camera

Taekyu Kim,Heechul Hwang,Chanho Han,Dukgyoo Kim 대한전자공학회 2005 ITC-CSCC :International Technical Conference on Ci Vol.2005 No.1

Optical Properties of Annealed Lead-Tungstate Single Crystals

Taekyu Kim 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.2

PbWO4 single crystals were grown in argon by using the Czochralski method and annealed in air. The thermoluminescence (TL) peaks below 110 K originate from intrinsic defect centers generated during growth, and those above 154 K are related to a local oxygen excess. The 420-nm absorption bands of annealed PbWO4 are related to the annealing temperature. The TL emission spectrum of as-grown PbWO4 mainly originate from the WO3 associated with oxygen vacancies or F-centers and that of annealed PbWO4 is due to the WO2− 4 complex interacting with O2− owing to oxygen diffusion during the annealing process. The correlation between annealing and luminescence shows that structural defects are greatly influenced by the post-growth annealing.

The Information Value of Credit Rating Changes and Insider Trading

Taekyu Kim,Jungsoon Shin 한국재무학회 2011 한국재무학회 학술대회 Vol.2011 No.11

This paper examines the relationship between credit rating changes, insider trading, and future stock returns. We find that prior insider trading is negatively related to credit rating changes. Insiders are more likely to purchase shares before a downgrade rather than before an upgrade. Thus, an investor is likely to face information signals that seem to systematically disagree on the value of the firm simultaneously: for example, insider purchases and downgrades. We also document that both insider trading and credit rating changes have additional power to explain market-adjusted stock returns, regardless of the negative relationship between credit rating changes and insider trading. Finally, we show that the information value of insider trading is mainly coming from insider purchases, while that of credit rating changes is mostly driven by credit rating downgrades.

The Influence of Credit Scores on Dividend Policy: Evidence from the Korean Market

KIM, Taekyu,KIM, Injoong Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.2

The paper investigates the mechanism through which corporate credit ratings affect dividend payments by decomposing the mean difference of dividends into a part that is explained by the determinants of dividends and a residual part that is contributed by the pure credit group effect, in the framework of the traditional dividend model of Fama and French (2001). Historically, better credit rated firms have shown consistently higher propensity to pay dividends especially during the economic crisis period. According to the counter-factual decomposition technique of Jann (2008), better rated firms are more responsive to the firm characteristics that have positive impact on dividends and poor rated firms are more responsive to the negative dividend predictors. As a result, good (bad) credit ratings make corporate managers become more bold (timid) in their dividend payments and they tend to pay more (less) dividends than what their firm characteristics prescribe. The degree of information asymmetry increases for the poor group firms during crisis periods and they attempt to reserve more cash in preparation for future investments. The decomposition results suggest that the credit group effect can potentially exceed the effect of firm characteristics because firms of different credit ratings can respond to the very same firm characteristics in a different manner.

Reduced Complexity Detection for V-BLAST Systems from Iteration Canceling

Taekyu Kim,Sin-Chong Park 대한전자공학회 2008 ITC-CSCC :International Technical Conference on Ci Vol.2008 No.7

V?BLAST is an effective detection method for MIMO communication system, but has large computational complexity due to its successive iteration. In this paper, we proposed modified V-BLAST to lessen its computational complexity reducing the number of successive iteration. As a result of this simplification, the computational complexity of the detection is lowered significantly. Simulation results show that the proposed V-BLAST reduces calculation complexity by about the 30% while achieving a very close BER performance as the original one.

Arctangent Processor Design for the Frequency Offset Estimation of IEEE 802.16d WirelessMAN-OFDM System

Taekyu Kim,Sin-Chong Park 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

This paper presents a hardware design of an arctangent processor for the IEEE 802.16d WirelessMANOFDM system. The proposed arctangent processor does not require the division value of imaginary/real for the input argument, and uses these two values, respectively, to look up the tangent ROM table. We reduce the tangent look-up table size to one eighth of 2π rad using the imaginary and real component exchange method for memory size and operation speed. Consequently, the designed arctangent process for WirelessMAN-OFDM system takes six clocks to evaluate an arctangent value and has the resolution of 2π/256 rad. The maximum absolute error of this arctangent hardware is 1.225e-2 rad (0.7°) comparing to mathematical result.

CEO Pay-performance Sensitivity in KOSPI and KOSDAQ Firms

Taekyu Kim,Injoong Kim 한국자료분석학회 2020 Journal of the Korean Data Analysis Society Vol.22 No.4

It is important to adjust both the level and the sensitivity of CEO payments with respect to firm performance in order to elicit managerial efforts and solve the agency problem. In our panel data analysis over the period 2004-2017 on both KOSDAQ and KOSPI firms, CEO pays are positively and significantly related with the firm accounting performance in both markets. Although the average CEO pay is significantly higher for KOSPI firms and KOSDAQ firms are more susceptible to factors that reduce CEO compensation, such as leverage and risk, the mean decomposition results suggest that CEOs of KOSDAQ firms are actually overpaid considering their firm performance and other firm characteristics. Overall, the distribution of CEO pay is more dispersed and the pay performance sensitivity is higher for KOSPI firms. Therefore, care should be taken in extending results based on KOSPI samples to KOSDAQ firms, or vise versa. Not to mention that the credit ratings of the KOSPI firms are more sound, the degree of information asymmetry is less severe for the KOSPI firms. Our results suggest that the pay performance relation is weaker (stronger) among the lower (higher) credit rated firms and that the information asymmetry may weaken the pay performance sensitivity because the managerial efforts are difficult to be verified upon contract.

자사주 매입 기업의 내부자거래 분석

김태규(Taekyu Kim) 한국산업경제학회 2016 산업경제연구 Vol.29 No.5

본 연구는 자사주 매입 기업의 내부자거래 추이를 조사하고 자사주 매입 공시에 대한 주가 반응과 내부자거래 간의 관계를 분석하였다. 주요 결과는 다음과 같다. 첫째, 자사주 매입 공시 전 내부자거래는 빈번히 발생하였으며 내부자 순매수가 증가하였다. 특히 자사주 매입 공시 직전분기와 직전반기에 내부자 순매수가 가장 높게 나타났다. 그러나 자사주 매입 공시 전 6개월 동안 28%의 자사주 매입 기업에서 내부자 순매도가 관찰되었다. 둘째, 자사주 매입 공시 전 내부자는 저평가된 주식을 매수하고 고평가된 주식을 매도하는 경향을 보였다. 셋째, 자사주 매입 공시에 대한 장단기 주가 반응은 전반적으로 저평가가설을 지지하는 것으로 해석된다. 그러나 내부자거래를 이용하여 분석한 결과 내부자 매수가 발생한 자사주 매입 공시에 대한 주가 반응은 내부자 매도가 발생한 경우보다 크게 나타났다. 특히 내부자 강매도의 경우 장기 주가가 유의한 상승 반응을 보이지 않았다. 이는 일부 자사주 매입 기업들이 저평가 여부와 무관하게 허위정보신호로 자사주 매입을 공시하였을 가능성을 시사하는 것이다. 본 연구는 기업의 자사주 매입 결정 시 나타나는 내부자의 거래행태를 분석함으로써 자사주 매입 관련 정책과 내부자거래 규제 정책에 새로운 시사점을 제시할 것으로 기대된다. Stock Repurchase refers to the reacquisition by a firm of its own equity, while insider trading means the legal stock transactions by the corporate insiders such as officers, directors, and large shareholders. This paper investigates insider trading activities around stock repurchase announcements and the effect of insider trading on the stock price reactions to stock buybacks. First, numerous insider trades are observed and corporate insiders are more likely to purchase shares before stock repurchase announcements. Insiders’ net purchase ratio reaches its highest level at the one quarter before the stock repurchase announcement. However, the typical investor is also likely to face numerous insider sales prior to stock buybacks. In addition, I analyze insiders’ behaviors before stock repurchase announcements and confirm that insiders tend to buy undervalued equity and sell overvalued stock. I document that the announcement effects of stock repurchases and long-term abnormal stock returns are significantly positive. The overall results support the undervaluation hypothesis. Stock prices, however, react more to repurchase announcements with prior insider purchases than to those with prior insider sales. Moreover, repurchase announcements with strong prior insider sales show insignificant stock returns. This suggests that some firms may send false information signals via stock repurchase announcements. Exploiting insider trades around stock repurchases, this research may provide new insights on stock repurchase policies and insider trading regulations.