No Response Instead Of Stock Recommendations: Evidence From Korea

The objectives of this study are to confirm the theories and findings of empirical research related to stock recommendations in analysts reports and to examine from various angles the significance of stock recommendation revisions in the Korean capital market. In a considerable number of analysts reports, no stock recommendations are made; this area of the report remains blank. In this study, the blank is labeled No Response. We analyze the factors related to the decision to omit stock recommendations and the informational content of analysts reports in which no stock recommendations are made. There is no previous research on this phenomenon in Korea or other countries. Under the assumptions that the optimum portfolio of investors is affected by the trading of stocks, and that analysts reports reflect market expectations, we investigate the informational content of reports in which no stock recommendations are made by observing the abnormal returns on the day of disclosure

Fem-Based Conductive Heat Transfer Analytical Description of Solidification Rate and Temperature Gradient During Lateral Laser Beam Oscillation Welding of Aluminum Alloy

This study investigates the feasibility of utilizing the finite element method (FEM)-based conductive heat transfer (CHT) analysis simulation to determine temperature gradients and solidification rates at the solid–liquid interface during laser beam oscillation welding. By comparing experimental observations with FEM-based CHT analysis, the underlying microstructural evolution and grain formation during welding were examined. FEM-based CHT enables the calculation of temperature gradients (G) and solidification rates (R), offering insights into the formation of equiaxed structures, which are crucial for suppressing hot cracking. Columnar-to-equiaxed structure transition thresholds, such as G/R and G3/R, accurately predict the emergence of fully equiaxed grain structures, validated by electron backscatter diffraction. This research provides valuable insights into temperature gradients and solidification rates in oscillation welding, guiding process design for achieving refined equiaxed structures and minimizing hot cracks

Deep Learning-based Penetration Depth Prediction in Al/Cu Laser Welding using spectrometer signal and CCD Image

In the laser welding of thin Al/Cu sheets, proper penetration depth and wide interface bead width ensure stable joint strength and low electrical conductance. In this study, we proposed deep learning models to predict the penetration depth. The inputs for the prediction models were 500 Hz-sampled low-cost charge-coupled device (CCD) camera images and 100 Hz-sampled spectral signals. The output was the penetration depth estimated from the keyhole depth measured coaxially using optical coherence tomography. A unisensor model using a CCD image and a multisensor model using a CCD image and the spectrometer signal were proposed in this study. The input and output of the data points were resampled at 100 and 500 Hz, respectively. The 500 Hz models showed better performance than the 100 Hz models, and the multisensor models more accurately predicted the penetration depth than the unisensor models. The most accurate model had a coefficient of determination (R2) of 0.999985 and mean absolute error of 0.02035 mm in the model test. It was demonstrated that low-cost sensors can successfully predict the penetration depth during Al/Cu laser welding

The Effect Of CEO Change On Information Asymmetry

This study investigated the relationship between CEO changes and information asymmetry. In the first year after a CEO change, management ability is evaluated in an atmosphere of high pressure and scrutiny regarding company performance. In such circumstances, CEOs selectively disclose information in an effort to inflate their performance evaluation. In addition, new CEOs influence not only management decisions, but also information disclosure strategies related to both financial and nonfinancial information. Therefore, the motivations of new CEOs regarding information disclosure can increase information asymmetry, and financial analysts must put extra effort toward reducing this asymmetry. This study measured information asymmetry by the unfaithful disclosure firm designation and analyst forecast errors. The sample is composed of firms active in the Korea Composite Stock Price Index (KOSPI) from 2006 to 2009. We found that there is a significant positive relationship between CEO change and information asymmetry as measured by unfaithful disclosure firm designation and analyst forecast errors. These results imply that CEO turnover increases information asymmetry due to managers’ intentional efforts to reduce the level of available information

Investor perception of fair value evaluation: focusing on financial instruments

This study analyzed capital market investors’ recognition of the predictability of fair value-based valuation. It was examined if market investors overvalue the predictive value of fair value by comparing that value with that measured in accounting performance. The results reveal that investors are likely to overvalue fair value more than predictive values reflected in accounting performance. In particular, the results show that investors can gain abnormal returns through the market anomaly due to the functional fixation that investors cannot distinguish between unrealized profits and realized ones. Though there are considerable studies about accrual anomaly, few studies explore it with the separation of unrealized profits from total accruals. A number of studies about the causes of accrual anomaly have been conducted from various perspectives. The analysis of this study argues that the unrealized profits derived from fair value evaluation can be a cause of accrual anomaly. On the basis of the result, this study suggests that information about unrealized earnings should be reported separately

Heterogeneities in Nanog Expression Drive Stable Commitment to Pluripotency in the Mouse Blastocyst

SummaryThe pluripotent epiblast (EPI) is the founder tissue of almost all somatic cells. EPI and primitive endoderm (PrE) progenitors arise from the inner cell mass (ICM) of the blastocyst-stage embryo. The EPI lineage is distinctly identified by its expression of pluripotency-associated factors. Many of these factors have been reported to exhibit dynamic fluctuations of expression in embryonic stem cell cultures. Whether these fluctuations correlating with ICM fate choice occur in vivo remains an open question. Using single-cell resolution quantitative imaging of a Nanog transcriptional reporter, we noted an irreversible commitment to EPI/PrE lineages in vivo. A period of apoptosis occurred concomitantly with ICM cell-fate choice, followed by a burst of EPI-specific cell proliferation. Transitions were occasionally observed from PrE-to-EPI, but not vice versa, suggesting that they might be regulated and not stochastic. We propose that the rapid timescale of early mammalian embryonic development prevents fluctuations in cell fate

Gas Metal Arc Welding with Undermatched Filler Wire for hot-press-formed steel of 2.0 GPa strength: Influence of filler wire strength and bead geometry

Commercial welding filler wires have less strength than hot-press-forming (HPF) steels. As the 2.0 GPa-HPF steel sheets have been released, their lap welding characteristics were investigated using gas metal arc welding in this study. The base metal was 1.1 mm-thick 2.0 GPa-HPF steel sheets, and three filler metal wires considered in this study (W540, W920, and W980) had tensile strengths of 540, 920, and 980 MPa, respectively. Gas metal arc welding was performed under a controlled short-circuit mode, and the wire feed speed (WFS) was selected as a process parameter. Tensile-shear test and microscopy were performed to evaluate the joint strength and metallurgical characteristics. The joint strength increased when WFS increased. When the WFS was 6 m/min or higher and high strength filler wires were applied to it, a heat affected zone (HAZ) fracture was observed in the tensile-shear test, with a tensile strength of approximately 1150 MPa. The fracture location was the boundary of the sub-critical HAZ (comprising tempered martensite) and intercritical HAZ (comprising polygonal ferrite and martensite). The weld metal (WM) hardness for W540 welds was 270 HV, and that for W920 and W980 was 414–419 HV, while the joint strength for the WM fracture was proportional to the throat thickness. For low WFS (when the heat input per unit length and welding current were low), high strength filler metals enhanced the joint strength, while high welding currents and deep penetration welding modes were recommended for W540. This study provided the filler wire and bead geometry design for the lap welds of 2.0 GPa HPF steel sheets

Knowledge, attitudes, and practices (KAP) toward COVID-19: a cross-sectional study in South Korea

Background The public must routinely practice precautionary behaviors to control the spread of COVID-19, as no vaccines and antiviral treatments are currently available. This paper examines the publics knowledge, attitudes, and practices (KAP) related to COVID-19 and their relationships and identified the pandemics vulnerable populations to provide recommendations for behavioral interventions and policies. Methods Data collection took place over 3 days (June 26–29) via an online survey 5 months after the Korea Centers for Disease Control and Prevention (KCDC) confirmed the first COVID case in South Korea; 970 subjects were included in the statistical data analysis. Results Knowledge directly affected both attitudes (e.g., perceived risk and efficacy belief) and practices (e.g., personal hygiene practices and social distancing). Among the influencing factors of COVID-19 preventive behaviors, efficacy belief was the most influential and significant practice factor. It mediated the relationship between knowledge and all three preventive behaviors (wearing facial masks, practicing hand hygiene, and avoiding crowded places). The level of knowledge varied by sociodemographic characteristics. Females (β = 0.06, p <  0.05) and individuals with higher levels of education (β = 0.06, p <  0.05) demonstrated higher levels of knowledge. Conclusion To increase precautionary behaviors among the public, health officials and policymakers must promote knowledge and efficacy belief. Future interventions and policies should also be developed in a person-centered approach, targeting vulnerable subgroups, embracing them, and closing the gap of KAP toward COVID-19.This work was supported by the National Research Foundation of Korea (BK21 Center for Integrative Response to Health Disasters, Graduate School of Public Health, Seoul National University); the Ministry of Health and Welfare, South Korea. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Temporal Interpolation Is All You Need for Dynamic Neural Radiance Fields

Temporal interpolation often plays a crucial role to learn meaningful representations in dynamic scenes. In this paper, we propose a novel method to train spatiotemporal neural radiance fields of dynamic scenes based on temporal interpolation of feature vectors. Two feature interpolation methods are suggested depending on underlying representations, neural networks or grids. In the neural representation, we extract features from space-time inputs via multiple neural network modules and interpolate them based on time frames. The proposed multi-level feature interpolation network effectively captures features of both short-term and long-term time ranges. In the grid representation, space-time features are learned via four-dimensional hash grids, which remarkably reduces training time. The grid representation shows more than 100 times faster training speed than the previous neural-net-based methods while maintaining the rendering quality. Concatenating static and dynamic features and adding a simple smoothness term further improve the performance of our proposed models. Despite the simplicity of the model architectures, our method achieved state-of-the-art performance both in rendering quality for the neural representation and in training speed for the grid representation.Comment: CVPR 2023. Project page: https://sungheonpark.github.io/tempinterpner