Explore the vast range of titles available.

‘Ideal’ transparent p -type semiconductors are required for the integration of high-performance thin-film transistors (TFTs) and circuits. Although CuI has recently attracted attention owing to its excellent opto-electrical properties, solution processability, and low-temperature synthesis, the uncontrolled copper vacancy generation and subsequent excessive hole doping hinder its use as a semiconductor material in TFT devices. In this study, we propose a doping approach through soft chemical solution process and transparent p -type Zn-doped CuI semiconductor for high-performance TFTs and circuits. The optimised TFTs annealed at 80 °C exhibit a high hole mobility of over 5 cm 2 V −1 s −1 and high on/off current ratio of ~10 7 with good operational stability and reproducibility. The CuI:Zn semiconductors show intrinsic advantages for next-generation TFT applications and wider applications in optoelectronics and energy conversion/storage devices. This study paves the way for the realisation of transparent, flexible, and large-area integrated circuits combined with n -type metal-oxide semiconductor. Designing efficient thin-film transistors and circuits based on transparent p-type semiconductors remains a challenge. Here, the authors propose a solution-based doping approach to realize high performance transparent inorganic p-type semiconductors (Zn-doped CuI) by spin coating at 80 C with good operational stability.

Through an agglomerative hierarchical clustering method, cold surges over East Asia are classified into two distinct types based on the spatial pattern of the geopotential height anomalies at 300 hPa. One is the wave-train type that is associated with developing large-scale waves across the Eurasian continent. The other is the blocking type whose occurrence accompanies subarctic blocking. During the wave-train cold surge, growing baroclinic waves induce a southeastward expansion of the Siberian High and strong northerly winds over East Asia. Blocking cold surge, on the other hand, is associated with a southward expansion of the Siberian High and northeasterly winds inherent to a height dipole consisting of the subarctic blocking and the East Asian coastal trough. The blocking cold surge tends to be more intense and last longer compared to the wave-train type. The wave-train cold surge is associated with the formation of a negative upper tropospheric height anomaly southeast of Greenland approximately 12 days before the surge occurrence. Further analysis of isentropic potential vorticity reveals that this height anomaly could originate from the lower stratosphere over the North Atlantic. Cold surge of the blocking type occurs with an amplifying positive geopotential and a negative potential vorticity anomaly over the Arctic and the northern Eurasia in stratosphere. These anomalies resemble the stratospheric signature of a negative phase of the Arctic Oscillation. This stratospheric feature is further demonstrated by the observation that the blocking type cold surge occurs more often when the Arctic Oscillation is in its negative phase.

The present study reveals the changes in the characteristics of cold surges over East Asia associated with the Arctic Oscillation (AO). Based on circulation features, cold surges are grouped into two general types: wave train and blocking types. The blocking type of cold surge tends to occur during negative AO periods, that is, the AO-related polarity of the blocking type. However, the wave train type is observed during both positive and negative AO periods, although the wave train features associated with negative AO are relatively weaker. The cold surges during negative AO are stronger than those during positive AO in terms of both amplitude and duration. The cold surges during positive AO in which the extent of effect is confined to inland China passes through East Asia quickly because of weaker Siberian high and Aleutian low, leading to short duration of these cold surges. In contrast, the cold surge during negative AO, characterized by a well-organized anticyclone–cyclone couplet with high pressure over continental East Asia and low pressure over Japan, brings continuous cold air into the entire East Asian region for more than one week with long-lasting cold advection. It is also found that the tracks of the cold surges during negative AO tend to occur more frequently over Korea and Japan and less frequently over China, compared with those during positive AO. The tracks are related to a west–east dipole structure of the ratio of rain conversion to snow according to AO phase, resulting in freezing precipitation or snowfall events over inland China (Korea and Japan) are likely to occur more frequently during the positive (negative) AO periods.

The cold surges over East Asia can be classified into wave-train type and blocking type according to their dynamic origins. In the present study, two dynamic indices are proposed to objectively identify cold surge types using potential temperature ( θ ) on the dynamic tropopause at 2-potential vorticity units (2-PVU) surface. The two indices are designed to represent primary characteristics of the two types of cold surge. The wave-train index ( WI ) is defined as a difference of anomalous θ on the 2-PVU surface between the western North Pacific and northeast China, which captures a southward (northward) intrusion of cold (warm) air mass related to the trough-ridge pattern. The blocking index ( BI ) is defined as a difference of anomalous θ between the subarctic region and northeast China, which indicates air mass overturning related to a reversal of the usual meridional θ gradient commonly observed in the occurrence of blocking type cold surge. Composite analyses based on the distribution of the WI and BI clearly demonstrate the dynamic evolutions of corresponding cold surge types. The wave-train cold surge is associated with a southeastward expansion of the Siberian High and northerly wind near surface, which is caused by growing baroclinic waves. During the blocking cold surge, a geopotential height dipole indicating the subarctic blocking and deepening of East Asian coastal trough induces a southward expansion of the Siberian High and northeasterly wind. Compared to the wave-train type, the blocking cold surge exhibits a longer duration and stronger intensity. In the new framework of these dynamic indices, we can detect a third type of cold surge when both the wave-train and the blocking occur together. In addition, we can exclude the events that do not have the essential features of the upper tropospheric disturbances or the subarctic anticyclonic circulation, which are responsible for cold surge occurrence, using the new indices.

Summer heatwave events have exhibited increasing trends, with sudden increases occurring since the early 2000s over northeastern China and along the northern boundary of Mongolia. However, the mechanism behind heatwaves remains unexplored. To quantitatively examine the feedback attribution of concurrent events related to surface temperature anomalies, the coupled atmosphere–surface climate feedback-response analysis method based on the total energy balance within the atmosphere–surface column was applied. The results demonstrate that the contributions of the latent heat flux and surface dynamic processes served as positive feedback for surface warming by reducing the heat release from the surface to the atmosphere because of deficient soil moisture based on dry conditions. Cloud feedback also led to warm temperature anomalies through increasing solar insolation caused by decreasing cloud amounts associated with anomalous high-pressure systems. In contrast, the sensible heat flux played a role in reducing the warm temperature anomalies by the emission of heat from the surface. Atmospheric dynamic feedback led to cold anomalies. The influence of ozone, surface albedo, and water vapor processes is very weak. This study provides a better understanding of combined extreme climate events in the context of radiative and dynamic feedback processes.

This study assesses improvements in the head and extension sleeve parts for a post-installed anchor. The sleeve and head details were proposed to enhance the structural performance of the post-installed anchor, and the optimal structural shape was determined through finite element analysis. The analysis results revealed that the anchor's performance was most efficiently improved when the sleeve length was 9.0 mm and the head length was 3.0 mm. In the model with these dimensions applied, the performance improved approximately 1.71 times compared to the existing model, validating the effectiveness of the proposed structural details. The improved pull-out strength test of anchor diameter M12 showed an increase of 1.25 times in normal-strength concrete and 1.28 times in high-strength concrete, with an embedded depth of 50 mm. The improved pull-out strength test of anchor diameter M16 showed that the pull-out strength increased by 1.42 times for normal-strength concrete and about 1.33 times for high-strength concrete. This research proposes a modified equation that reflects changes in the effective embedded depth and diameter. A comparison of the proposed equation with that of European Technical Approval Guideline (ETAG) showed that the correlation coefficient changed from 0.908 to 0.962, and the coefficient of variation changed from 18.9 to 10.4%, meaning that the proposed equation reflected the actual experimental values more accurately.

In the winter of 2009–2010, frequent and long‐lasting cold weather affected Korea. Four major cold surges and several heavy snowfall events were observed, including a record‐breaking event on 4 January 2010. These four cold surges had distinct properties with regard to their relationships to the phases of the Arctic Oscillation (AO) and the Madden‐Julian Oscillation (MJO), suggesting the possible influences of the AO and MJO on the cold surges and heavy snowfalls. The four cold surges were of two distinct types: the wave train type and the blocking type, which were differentiated by their mechanisms. With regard to the relationships of the cold surges to the AO, three cold surges occurred during a strongly negative AO period, which lasted for more than 1 month. The Siberian High expanded from the Arctic high‐pressure region to East Asia during the negative AO period. A cold surge occurred during a positive AO, with the expansion of the Siberian High across the Eurasian continent. An MJO‐induced circulation, corresponding to strong tropical convection over the tropical Indian Ocean, seems to have reinforced the cold surges over East Asia. In addition, the active local Hadley circulation modulated by a convection center over the Indian Ocean tends to enhance midlatitude synoptic disturbances across East Asia and provides favorable conditions for upward motion over the region. In short, the effects of the AO and MJO, along with the existing low‐level moisture supply, contributed to heavy snowfalls associated with strong cold surges over Korea during the winter of 2009–2010.

This study investigates the changes in winter cold extreme events over East Asia in the present and future climates. Two distinct terms to indicate cold extreme events are analyzed: “cold day,” which describes a temperature below a certain threshold value (e.g., simply cold weather), and “cold surge,” which describes an abrupt temperature drop (e.g., relatively colder weather than a previous day). We analyze both observations and long‐term climate simulations from 13 atmospheric and oceanic coupled global climate models (CGCMs). The geographical distribution of sea level pressure corresponding to a cold day (cold surge) is represented by a dipole (wave train) feature. Although cold day and cold surge show similar patterns of surface air temperature, they are induced by the out‐of‐phase sea level pressures. From the results of our analysis of a series of future projections for the mid and late twenty‐first century using the 13 CGCMs, cold day occurrences clearly decrease with an increasing mean temperature (a correlation coefficient of −0.49), but the correlation between cold surge occurrences and the mean temperature is insignificant (a correlation coefficient of 0.08), which is supported by the same results in recent observation periods (1980–2006). Thus, it is anticipated that cold surge occurrences will remain frequent even in future warmer climate. This deduction is based on the future projections in which the change in the day‐to‐day temperature variability is insignificant, although the mean temperature shows significant increase. The present results suggest that living things in the future, having acclimatized to a warmer climate, would suffer the strong impact of cold surges, and hence the issue of vulnerability to cold surges should be treated seriously in the future. Key Points Comparison of changes in cold day and cold surge frequency over East Asia Suggestion of still frequent occurrences of cold surge in future warm climate

This study analyses the regional characteristics of heat extremes (hot days and tropical nights) in the Honam area of South Korea during the recent 23 years (1997–2019) by using weather station data. The results based on the binary classifications of stations, that is, inland versus coastal and urban versus rural, show hot days in inland regions are climatologically more frequent, and present higher interannual variability and more evident increasing trend than coastal regions. On the other hand, inland regions are exposed to less active tropical nights. The thermal characteristics associated with the oceanic (or continental) climate at which the station is located are responsible for the inland–coastal dependency of frequencies in hot days and tropical nights. The noticeable discrimination between urban and rural stations, categorized by population, appears only in tropical night occurrences, while hot days are independent of urban–rural contrast. In urban stations, tropical night occurrences are climatologically higher, interannually more active, and recently more frequent. Regarding the urban heat island, the additional nocturnal heat leads to the urban concentrated activity of tropical nights. Our analyses suggest that for accurate forecasts of hot days and tropical nights, different regional environments must be considered. The binary classification and the indices‐based analysis indicate clear regional contrasts for the occurrences of heat extremes, depending on the continental/oceanic climate, and the city size. In inland stations, hot days occur more frequent in climatology and accompany larger interannual variation and long‐term trends, compared to those in coastal stations. In the urban stations, tropical nights do so, compared to those in rural stations.

Story-added type apartments have recently been introduced as an option to resolve the housing supply shortage in areas that are undergoing rapid industrialization and urbanization. However, the infrastructure of old apartment buildings (>20 years old) makes it difficult to introduce convenient facilities and recent technologies such as those involving the Internet of Things and augmented realities. Applying housing technologies to existing older apartments can increase housing supply and potentially address the aforementioned issues. However, story-added building remodeling increases the weight of existing buildings, necessitating seismic reinforcement, which is the major obstacle when performing vertical building extensions. This study presents methods for lowering seismic loads associated with vertical augmentation of buildings while improving the seismic performance. A model of a vertically extended building with three additional stories constructed on top of an existing 15-story apartment building was used. The applied seismic isolation system decreased the maximum response acceleration on top of the remodeled building by approximately 70% and 65% in the X-direction and Y-direction, respectively, while decreasing the base shear plane by approximately 30% in both the X- and Y-directions in comparison with forces on a non-seismically isolated building. These results demonstrate that the use of a seismic isolation system can significantly reduce seismic loads.