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Abstract This work characterizes the structural, magnetic, and ferroelectric properties of epitaxial LuFeO3 orthoferrite thin films with different Lu/Fe ratios. LuFeO3 thin films are grown by pulsed laser deposition on SrTiO3 substrates with Lu/Fe ratio ranging from 0.6 to 1.5. LuFeO3 is antiferromagnetic with a weak canted moment perpendicular to the film plane. Piezoresponse force microscopy imaging and switching spectroscopy reveal room temperature ferroelectricity in Lu‐rich and Fe‐rich films, whereas the stoichiometric film shows little polarization. Ferroelectricity in Lu‐rich films is present for a range of deposition conditions and crystallographic orientations. Positive‐up‐negative‐down ferroelectric measurements on a Lu‐rich film yield ≈13 µC cm−2 of switchable polarization, although the film also shows electrical leakage. The ferroelectric response is attributed to antisite defects analogous to that of Y‐rich YFeO3, yielding multiferroicity via defect engineering in a rare earth orthoferrite.

Ferroelectricity in orthoferrite perovskites has stimulated intense research, but the mechanism remains unclear. Here, the authors propose an antisite defect mechanism for introducing ferroelectricity in magnetically ordered YFeO3 and the family of rare earth orthoferrites.

AbstractIn a multi-channel distribution environment, the selection and assessment of suppliers are pivotal to effective retailer performance management. This necessitates heightened qualifications and competence from suppliers. This study examines the relationship between the perception of supplier firms’ status, evaluation performance, and overall satisfaction of food buyers with suppliers in online/offline channels. In addition, this study investigates the moderating impacts of the distribution channel to explore the influence of the online/offline distribution channel on this relationship. For exploratory research, food buyers from 20 large retailers headquartered in Seoul, South Korea, were surveyed, and 110 valid questionnaires were used for analysis. Results of the study indicate that among suppliers’ firm factors, suppliers’ firm size and experience with the retailer were significantly and positively related to buyer satisfaction. Likewise, among evaluation factors, product competency and delivery reliability were significantly and positively related to buyer satisfaction. In addition, the results reveal that the distribution channel has moderating effects on the relationship between firm size and buyer satisfaction, as well as between experience with the retailer and buyer satisfaction. Therefore, the study verified that the distribution channel is an important factor that must be considered not only in the consumer market but also in the buying behavior research of the business-to-business market.

Bond resistance is critical for reinforcing fibers in cementitious materials. Recently, crimped shape memory alloy fibers (SMA) have been raised as candidates for providing abundant benefits such as improved strength, enhanced durability, and crack closing. This study aimed to examine the influence of wave-depth and wave-length of crimped SMA fibers on their bond behavior. The crimped fibers in this study were categorized in four groups based on the wave-length. Each group had four types of fibers that considered the ratio of wave-depth to wave-length (DLR). Thus, a total of sixteen types of fibers were prepared with variations in wave-length and wave-depth. The tensile test used bare crimped SMA fibers, while the pullout tests used half dog-bone specimens. After the tests, the finite element model was used to evaluate the interaction parameters that were difficult to measure in the experience test. The results showed that the fibers with the smallest wave-length showed the largest maximum bond resistance in the same dept-to-length ratio (DLR) group, and that values decreased with an increasing wave-length. In addition, the smallest wave-length fibers demonstrated the most effective stiffness. Furthermore, the finite element analysis discovered that the geometric friction coefficients of the crimped SMA fibers were affected significantly by the geometric variation. The longer wave-length fiber revealed the larger estimated frictional coefficient.

This study evaluated the pullout resistance performance of a developed double-arched steel fiber. Pullout experiments were conducted to assess the resistance load, bond strength, and energy absorption capacity of the fiber according to the geometry and tensile strength of the fiber. Double-arched (DA) steel fibers demonstrated peak and residual resistance loads approximately 36–112% and 29–163% higher than hooked-end and single-arched steel fibers, respectively. The DA steel fiber also significantly increased the bond strength and energy absorption capacity by approximately 58–159% and 125–130%, respectively, compared to the hook-end and single-arched steel fibers. Moreover, the DA fiber exhibited a more significant increase rate in pullout resistance load, bond strength, and energy absorption capacity with increasing tensile strength. A prediction model was also developed to incorporate the influence of plastic bending and friction resistance on the pullout behavior of the DA fiber. The resistance loads and decreasing trend obtained from the prediction model exhibited a very close agreement with the experimental results.

Shape memory alloys (SMAs) demonstrate a shape memory effect and superelasticity that can provide recovery performance to structural members. In this study, a round SMA bar was designed to replace the conventional deformed steel bar, particularly within the plastic hinge section of structural members. To integrate the SMA bar and the existing steel bar, a mechanical coupler was proposed by utilizing the advantages of both one-touch and threaded couplers. Uniaxial tensile tests were conducted to analyze the performance of the proposed coupler and the mechanical properties of the SMA–steel connected bar. Stress and strain relationships were examined for steel bars mechanically connected with the SMA bar and for SMA bars before and after exhibiting the shape memory effect. To induce the shape memory effect, SMA should be heated above the finished austenite temperature. Due to the difficulty of accurately measuring strain on the heated bar using traditional contact methods, we employed digital image correlation technology for precise strain measurement of the heated SMA bar. The experimental results indicate the effective application of SMA bars within the plastic hinge region of structural members using the proposed mechanical coupler.

The present study examined the difference between women and men in perceiving leadership roles. Two experiments, one conducted online and the other in a lab, investigated the subjective experiences of Japanese men and women when they are assigned with different roles (e.g., leader vs. subordinate). Both studies revealed that women perceived their role as less legitimate when they were assigned leader role (vs. subordinate role). In contrast, men did not differ in their perceived legitimacy according to the assigned roles. This discrepancy in legitimacy perception in response to different roles between men and women accounted for a significant variance in women’s lower sense of status when they were a leader (vs. subordinate), but not among men. Our study results illustrate the psychological barrier operating for women in organizations that are embedded in a cultural context in which women leaders are highly underrepresented.

This study proposed cement composites with natural green earth to detect elevated and abnormal temperatures. The thermochromic properties of the green earth pigment were examined with increasing temperature, and mixed cement composites were designed based on the pigment content and elevated temperatures. Cement composites with a pigment content of at least 3% demonstrated an irreversible color transition from grayish green to brown. The transition range of the temperature and the change in RGB values depended on the pigment content The color transition ranged from 250° to 350°C for specimens with pigment contents of 3% and 6% and from 200° to 300°C for specimens with a pigment content of 9%. In addition, the specimens with pigments showed a significant drop in weight between 200 and 250 °C, followed by a gradually decreasing rate similar to that of the control specimen. The change in the compressive strength at room temperature was minimal, regardless of the pigment content in the cement composites. After subjected to elevated high temperatures, the compressive strength was reduced by approximately 31.4% for the control specimen and 53.2% for specimens with pigments. The pigment content had minimal effect on the loss of strength.

Due to the prolonged COVID-19 pandemic, wearing masks has become essential for social interaction, disturbing emotion recognition in daily life. In the present study, a total of 39 Korean participants (female = 20, mean age = 24.2 years) inferred seven emotions (happiness, surprise, fear, sadness, disgust, anger, surprise, and neutral) from uncovered, mask-covered, sunglasses-covered faces. The recognition rates were the lowest under mask conditions, followed by the sunglasses and uncovered conditions. In identifying emotions, different emotion types were associated with different areas of the face. Specifically, the mouth was the most critical area for happiness, surprise, sadness, disgust, and anger recognition, but fear was most recognized from the eyes. By simultaneously comparing faces with different parts covered, we were able to more accurately examine the impact of different facial areas on emotion recognition. We discuss the potential cultural differences and the ways in which individuals can cope with communication in which facial expressions are paramount.

This study discusses a nonlinear electrical impedance tomography (EIT) technique under different analysis conditions to propose its optimal implementation parameters. The forward problem for calculating electric potential is defined by the complete electrode model. The inverse problem for reconstructing the target electrical conductivity profile is presented based on a partial-differential-equation-constrained optimization approach. The electrical conductivity profile is iteratively updated by solving the Karush–Kuhn–Tucker optimality conditions and using the conjugate gradient method with an inexact line search. Various analysis conditions such as regularization scheme, number of electrodes, current input patterns, and electrode arrangement were set differently, and the corresponding results were compared. It was found from this study that the proposed EIT method yielded appropriate inversion results with various parameter settings, and the optimal implementation parameters of the EIT method are presented. This study is expected to expand the utility and applicability of EIT for the non-destructive evaluation of structures.

Current scientometric indexes do not encourage the linguistic diversity of sources cited in academic texts and researchers are not motivated to cite texts written in smaller languages. This diminishes the cultural diversity of the sources cited and limits the representation of small and indigenous cultures. This text proposes a scientometric measure designed to encourage the linguistic diversity of sources cited in articles, books, and papers. The Linguistic Diversity Index is based on two stipulations: (a) the more linguistically diverse the sources, the higher the score, and (b) the rarer the languages cited, the higher the score. If such a metric were used for the evaluation of social science and humanities journals, it would encourage the publication of papers that cite ideas from rarely represented cultural groups such as indigenous nations, ethnic groups from small countries, and other linguistic groups that have been omitted from mainstream scientific discourse. This might help to produce new research, which would help to improve the situation for these groups and create an epistemology that is more just to small cultural groups.

The present study examined the daily well-being of Koreans (n = 353,340) for 11 weeks during the COVID-19 pandemic (January 20 -April 7). We analyzed whether and how life satisfaction, positive affect, negative affect, and life meaning changed during the outbreak. First, we found that the well-being of Koreans changed daily in a cubic fashion, such that it declined and recovered during the early phase but declined substantially during the later phase (after COVID- 19 was declared world pandemic by WHO). Second, unlike other emotions, boredom displayed a distinctive pattern of linear increase, especially for younger people, suggesting that boredom might be, in part, responsible for their inability to comply with social distancing recommendations. Third, the well-being of older people and males changed less compared to younger people and females. Finally, daily well-being dropped significantly more in the hard-hit regions than in other regions. Implications and limitations are discussed.

Crop tolerance to crowding stress, specifically plant population density, is an important target to improve productivity in processing sweet corn. Due to limited knowledge of biological mechanisms involved in crowding stress in sweet corn, a study was conducted to 1) investigate phenotypic and transcriptional response of sweet corn hybrids under different plant densties, 2) compare the crowding stress response mechanisms between hybrids and 3) identify candidate biological mechanisms involved in crowding stress response. Yield per hectare of a tolerant hybrid (DMC21-84) increased with plant density. Yield per hectare of a sensitive hybrid (GSS2259P) declined with plant density. Transcriptional analysis found 694, 537, 359 and 483 crowding stress differentially expressed genes (DEGs) for GSS2259P at the Fruit Farm and Vegetable Farm and for DMC21-84 at the Fruit Farm and Vegetable Farm, respectively. Strong transcriptional change due to hybrid was observed. Functional analyses of DEGs involved in crowding stress also revealed that protein folding and photosynthetic processes were common response mechanisms for both hybrids. However, DEGs related to starch biosynthetic, carbohydrate metabolism, and ABA related processes were significant only for DMC21-84, suggesting the genes have closer relationship to plant productivity under stress than other processes. These results collectively provide initial insight into potential crowding stress response mechanisms in sweet corn.

Previous research has shown that parental support has beneficial effects on the psychological well-being of adolescents. Going beyond prior research, the present study made distinctions between information, emotional, and financial parental support and examined adolescents from United States (N = 1,002), China (N = 1,172), South Korea (N = 3,993), and Japan (N = 1,112). The frequency and impact of different types of perceived parental support on adolescents’ positive self-belief and distress levels have been investigated. Consistent with the existing literature, the results showed American adolescents perceived greater emotional and informational support than others, while Chinese, Korean, and Japanese adolescents perceived greater tangible support compared to American adolescents. Notably, Chinese adolescents reported higher levels of parental support than other East Asian adolescents. The perceived parental support influenced positive self-beliefs equally across cultural groups, but informational support impacted distress to a greater degree for American adolescents than East Asian adolescents. The implications of the present research are discussed.

For estimation of maximum daily fresh snow accumulation (MDFSA), a novel model based on an artificial neural network (ANN) was proposed. Daily precipitation, mean temperature, and minimum temperature were used as the input data for the ANN model. The ANN model was regularized and trained using a set of 19,923 data points, observed daily in South Korea between 1960 and 2016. Leave-one-out cross validation was performed to validate the model. When the input data were known at the gauged locations, the correlation coefficient between the observed MDFSA and the estimated one by the ANN model was 0.90. When the input data were spatially interpolated at ungauged locations using the ordinary kriging (OK) method, the correlation coefficient was 0.40. The difference in correlation coefficients between the two methods implies that, while the ANN model itself has good performance, a significant portion of the uncertainty of the estimated MDFSA at ungauged locations comes from high spatial variability of the input variables that cannot be captured by the network of in situ gauges. However, these correlation coefficients were significantly greater than the correlation coefficient obtained by spatially interpolating the MDFSA values with the OK method (R = 0.20). These findings suggest that our ANN model significantly reduces the uncertainty of the estimated MDFSA caused by its high spatial variability.

Factors influencing the accuracy of UAV-photogrammetry-based snow depth distribution maps were investigated. First, UAV-based surveys were performed on the 0.04 km2 snow-covered study site in South Korea for 37 times over the period of 13 days under 16 prescribed conditions composed of various photographing times, flight altitudes, and photograph overlap ratios. Then, multi-temporal Digital Surface Models (DSMs) of the study area covered with shallow snow were obtained using digital photogrammetric techniques. Next, the multi-temporal snow depth distribution maps were created by subtracting the snow-free DSM from the multi-temporal DSMs of the study area. Then, snow depth in these UAV-Photogrammetry-based snow maps were compared to the in situ measurements at 21 locations. The accuracy of each of the multi-temporal snow maps were quantified in terms of bias (median of residuals, QΔD) and precision (the Normalized Median Absolute Deviation, NMAD). Lastly, various factors influencing these performance metrics were investigated. The results are as follows: (1) the QΔD and NMAD of the eight surveys performed at the optimal condition (50 m flight altitude and 80% overlap ratio) ranged from −2.30 cm to 5.90 cm and from 1.78 cm to 4.89 cm, respectively. The best survey case had −2.30 cm of QΔD and 1.78 cm of NMAD; (2) Lower UAV flight altitude and greater photograph overlap lower the NMAD and QΔD; (3) Greater number of Ground Control Points (GCPs) lowers the NMAD and QΔD; (4) Spatial configuration and accuracy of GCP coordinates influenced the accuracy of the snow depth distribution map; (5) Greater number of tie-points leads to higher accuracy; (6) Smooth fresh snow cover did not provide many tie-points, either resulting in a significant error or making the entire photogrammetry process impossible.

Concrete edge failure of a single anchor in concrete is strongly dependent on the tensile performance of the concrete, which can be greatly improved by the addition of steel fibers. This study investigated the effect of steel fibers on the shear failure mode and edge breakout resistance of anchors installed in steel fiber-reinforced concrete (SFRC) with fiber volume percentages of 0.33, 0.67, and 1.00%. The anchor used in the study was 30 mm in diameter, with an edge distance of 75 mm and embedment depth of 240 mm. In addition to the anchor specimens, beam specimens were prepared to assess the relationship between the tensile performance of SFRC beams and the shear resistance of SFRC anchors. The ultimate flexural strength of the beam and the breakout shear resistance of the anchor increased almost linearly with increasing volume fractions of fiber. Therefore, based on the ACI 318 design equation, a term was proposed using the ultimate flexural strength of concrete instead of the compressive strength to determine the concrete breakout shear resistance of an anchor in the SFRC. The calculated shear resistance of anchors in both the plain concrete and SFRC were in good agreement with the measurements. In addition to the load capacity of the SFRC anchors, the energy absorption capacity showed a linear increase with that of the SFRC beam.

A rechargeable lithium–oxygen (Li–O2) battery is considered as a promising technology for electrochemical energy storage systems because its theoretical energy density is much higher than those of state-of-the-art Li-ion batteries. The cathode (positive electrode) for Li–O2 batteries is made of carbon and polymeric binders; however, these constituents undergo parasitic decomposition reactions during battery operation, which in turn causes considerable performance degradation. Therefore, the rational design of the cathode is necessary for building robust and high-performance Li–O2 batteries. Here, a binder-free carbon nanotube (CNT) electrode surface-modified by atomic layer deposition (ALD) of dual acting RuO2 as an inhibitor–promoter is proposed for rechargeable Li–O2 batteries. RuO2 nanoparticles formed directly on the binder-free CNT electrode by ALD play a dual role to inhibit carbon decomposition and to promote Li2O2 decomposition. The binder-free RuO2/CNT cathode with the unique architecture shows outstanding electrochemical performance as characterized by small voltage gaps (∼0.9 V) as well as excellent cyclability without any signs of capacity decay over 80 cycles.

Previous research indicates that social relatedness is beneficial to physical health; however, findings on the relative strength of the relationship between these variables have been inconsistent. The present study employed cross-sectional survey (Study 1) and a daily diary survey (Study 2) to examine the link between social relatedness and physical health by age. Using a representative sample of Korean adults (N = 371) aged from 20 to 69, Study 1 examines the link between social relatedness (loneliness, perceived social support) and physical health (physical symptoms, chronic health conditions) using age as a moderator. The results show that participants' age moderates the association between social relatedness and physical health. Study 2 (N = 384) further corroborated the findings from Study 1 by showing that when controlling for the physical symptoms experienced prior to the daily diary reports, the level of loneliness experienced over a 13-day period exacerbates the age differences in the physical symptoms. The present study thus provides converging evidence that social relatedness plays a significant role in physical health, particularly in the older population.

Tolerance to crowding stress has played a crucial role in improving agronomic productivity in field corn; however, commercial sweet corn hybrids vary greatly in crowding stress tolerance. The objectives were to 1) explore transcriptional changes among sweet corn hybrids with differential yield under crowding stress, 2) identify relationships between phenotypic responses and gene expression patterns, and 3) identify groups of genes associated with yield and crowding stress tolerance. Under conditions of crowding stress, three high-yielding and three low-yielding sweet corn hybrids were grouped for transcriptional and phenotypic analyses. Transcriptional analyses identified from 372 to 859 common differentially expressed genes (DEGs) for each hybrid. Large gene expression pattern variation among hybrids and only 26 common DEGs across all hybrid comparisons were identified, suggesting each hybrid has a unique response to crowding stress. Over-represented biological functions of DEGs also differed among hybrids. Strong correlation was observed between: 1) modules with up-regulation in high-yielding hybrids and yield traits, and 2) modules with up-regulation in low-yielding hybrids and plant/ear traits. Modules linked with yield traits may be important crowding stress response mechanisms influencing crop yield. Functional analysis of the modules and common DEGs identified candidate crowding stress tolerant processes in photosynthesis, glycolysis, cell wall, carbohydrate/nitrogen metabolic process, chromatin, and transcription regulation. Moreover, these biological functions were greatly inter-connected, indicating the importance of improving the mechanisms as a network.

This study analyzed the spatial variability of the linear trend of the precipitation mean, variance, lag-1 autocorrelation coefficient, and probability of dryness (PD) based on the precipitation data between 1981 and 2015 observed at 65 rain gages located across Korean Peninsula. While the result of the Mann-Kendall test based on the yearly statistics showed no temporal trend at most of the gage locations, the same test based on the 20-yearly statistics showed that statistically significant temporal trend exists at 54% (mean), 60% (variance), 61% (autocorrelation), and 61% (PD) among the total 65 rain gages. In addition, this study produced the map of the linear trend of the precipitation statistics. The map showed a clear regional and seasonal tendency implying that the impact of the climate change varies significantly within Korea. The variogram analysis revealed that the approximate characteristic scale of linear trend of hourly and daily precipitation statistics ranges between 50 km and 200 km and between 100 km and 250 km, respectively. This characteristic scale is significantly smaller than the spatial scale of atmospheric circulation, which suggests that future water resources management plans of Korea should consider this mesoscale variability that otherwise can be missed if it is based only on the GCM simulation results.