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Investigating Performances of Takeover Activities using Google Trend Search Volume Index
Kyounghun Bae,Hail Jung,Daejin Kim 한국재무학회 2018 한국재무학회 학술대회 Vol.2018 No.05
Ways to measuring public attention are important questions, and many researchers use indirect measures to capture investors’ attention such as trading volume (Hou et al., 2008), extreme returns (Barber and Odean, 2008), and news and headlines (Yuan, 2008). On this research, we use Google search volume index which provides a direct measure to detect people’s interest. Using M&A data of the United States, we investigate the causality over search volume query changes on takeover returns. We find abnormal trends in Google search volume index such as volume reaching the spike before the mergers announcements. We present that earlier search volume hits the spike, more outperforming on both acquirer and target sides. We further believe that our research can contribute to the academia as a novel method to detect possible information leakage problem.
Kyounghun Bae,Jinyoung Ju,Hyoung-Goo Kang 한국재무학회 2017 한국재무학회 학술대회 Vol.2017 No.11
본 연구는 2001 년에서 2016 년까지 총 15 개년 동안 채권 수익률 자료와 매출액, 순이익자료를 이용하여 매출액 서프라이즈와 이익 서프라이즈가 채권 수익률에 미치는 영향에 대해 분석하였다. 분석 결과, 매출액 서프라이즈와 이익 서프라이즈는 채권 수익률에 긍정적인 영향을 주고 있음을 발견하였다. 즉 기존 문헌에 존재하는 주식시장의 이익 서프라이즈 효과 이외에도 채권시장에 매출액 서프라이즈로 인한 효과가 존재한다. 본 연구는 기관투자자들의 비중이 높은 채권시장도 순이익 성장의 지속성에 대한 정보가 제대로 반영되고 있지 않고 있음을 시사한다.
Text-based industry classification by Autoencoder
Kyounghun Bae,Daejin Kim,Rocku Oh 한국재무학회 2018 한국재무학회 학술대회 Vol.2018 No.05
Industry classification has been one of the crucial issues in financial analysis. However, classical industry classification systems have several limitations. Several studies have been progressed to overcome the limitations by using the text information that firms use to describe their business process and products. In this paper, we propose an industry classification methodology based on their business descriptions by reducing high dimensions using autoencoder to avoid a high dimensionality problem in vector space. The main contribution of this paper is first, we overcome the limitation of cosine similarity measure where the word vector is large and highly sparse by reducing the dimension of word vector utilizing the autoencoder. Second, we are able to visualize the relative industry relation of the firms based on the lower dimensional information extracted from the business description text. The relative location can also describe the industry-level relationship as well as the position of individual firms which were originally involved in conflicting assignment problem in terms of the classical classification scheme.
A Fidelity-Embedded Regularization Method for Robust Electrical Impedance Tomography
Lee, Kyounghun,Woo, Eung Je,Seo, Jin Keun IEEE 2018 IEEE transactions on medical imaging Vol.37 No.9
<P>Electrical impedance tomography (EIT) provides functional images of an electrical conductivity distribution inside the human body. Since the 1980s, many potential clinical applications have arisen using inexpensive portable EIT devices. EIT acquires multiple trans-impedance measurements across the body from an array of surface electrodes around a chosen imaging slice. The conductivity image reconstruction from the measured data is a fundamentally ill-posed inverse problem notoriously vulnerable to measurement noise and artifacts. Most available methods invert the ill-conditioned sensitivity or the Jacobian matrix using a regularized least-squares data-fitting technique. Their performances rely on the regularization parameter, which controls the trade-off between fidelity and robustness. For clinical applications of EIT, it would be desirable to develop a method achieving consistent performance over various uncertain data, regardless of the choice of the regularization parameter. Based on the analysis of the structure of the Jacobian matrix, we propose a fidelity-embedded regularization (FER) method and a motion artifact reduction filter. Incorporating the Jacobian matrix in the regularization process, the new FER method with the motion artifact reduction filter offers stable reconstructions of high-fidelity images from noisy data by taking a very large regularization parameter value. The proposed method showed practical merits in experimental studies of chest EIT imaging.</P>
수직형 실린더 내 분리 충전된 이종 PCM의 융해/응고 실험
김경훈(KyoungHun Kim),김형국(Hyungkuk Kim),박천완(ChunWan Park),백종현(JongHyeon Peck),강채동(Chaedong Kang) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.5
태양열 열원 축열 시스템에서 상 변화물질(PCM)은 열원이용 온도에 따라 종류를 달리할 수 있다. 본 연구에서는 냉난방 겸용 시스템에의 적용을 위해 수직 방향 이중 실린더 내에 충전된 이종 PCM의 융해/응고 실험을 수행하였다. 이종 PCM은 수직 방향의 원형 모듈 안에 분리 충전되어 있고 각각의 PCM 충전부에 열전대를 장착하여 융해/응고 동안 온도를 측정하였다. PCM 각각의 상 변화점은 78 ℃, 27.8℃ 이다. 그 결과, 융해 시 이종 PCM의 상층부부터 원추형으로 융해가 진행되는 것과, 융해/응고 동안 상 변화에 의한 열 전달이 인접한 PCM에 의해 부분 간섭을 받아 진행되는 것이 확인되었다. Phase change material(PCM) in solar heat source heat pump system is changeable to the utilizing temperature of the heat source. In the experiment, melting/solidification of the two PCMs in a vertically cylindrical heat transfer module was investigated whether to use heat pump system. The two PCMs are stored but separated to wall and the temperature of the PCM is measured to thermocouples which are installed to PCM layer. The melting point of PCMs is 27.8℃ and 78 ℃, respectively. To the results, the PCM is conically melted from top of region. Moreover, due to phase change, some interference on heat transfer between the two PCMs is observed during melting/solidification.