Several studies have indicated that densely populated urban environments and the heavy dependence on traffic could increase the potential spread of COVID-19. This study investigated the association between changes in traffic volume and the spread of COVID-19 in South Korea. Methods: This study analyzed the daily national traffic and traffic trend for 3 months from January 1, 2020. Traffic data were measured using 6307 vehicle detection system (VDS). This study analyzed the difference in traffic levels between 2019 and 2020. Non-linear regression was performed to analyze the change in traffic trend in 2020. The relationship between traffic and confirmed COVID-19 cases was analyzed using single linear regression. Results: The mean daily nationwide level of traffic for the first 3 months of 2020 was 143 655 563 vehicles, which was 9.7% lower than the same period in 2019 (159 044 566 vehicles). All regions showed a decreasing trend in traffic in February, which shifted to an increasing trend from March. In Incheon there was a positive, but insignificant, linear relationship between increasing numbers of newly confirmed cases and increasing traffic (β = 43 146; p = 0.056). Conclusions: Numbers of newly confirmed COVID-19 patients have been decreasing since March, while the traffic has been increasing. The fact that traffic is increasing indicates greater contact between people, which in turn increases the risk of further COVID-19 spread. Therefore, the government will need to devise suitable policies, such as total social distancing.

No abstract

Mobile DRAM is widely employed in portable electronic devices due to its feature of low power consumption. Recently, as the market trend renders integration of various features in one chip, mobile DRAM is required to have not only low power consumption but also high capacity and high speed. To attain these goals in mobile DRAM, we designed a 1Gb single data rate (SDR) Wide-I/O mobile SDRAM with 4 channels and 512 DQ pins, featuring 12.8GB/s data bandwidth. Figure 28.5.1 shows the chip architecture with 4-channels and 16 segmented 64Mb arrays. The whole chip is made up of 4 partitions which are symmetric with respect to the chip center, and each partition consists of 4×64Mb arrays, peripheral circuits and microbumps. Each channel has its own input pins while external power pins and internal voltage generators are shared with the other channels. In a single channel, 128 data lines are controlled to feed 128 DQs. Four 64Mb arrays in 1-channel can be configured in 4 banks with bank addresses BA [0:1] and row addresses RA [0:11], or in 2 banks with BA [0] and RA [0:12]. In a 4-bank structure, each bank has 4k row depth and 8k page depth.To reduce power consumption in 512b I/O operations and to support high data bandwidth, I/O driver loading is reduced by adoption of 44×6 microbump pads per channel, which are located in the middle of the chip. Figure 28.5.1 also shows a SEM image of the fabricated microbumps with 20×17μm 2 size and max 50μm pitch. To detect bump connection failure with other devices, a simple boundary scan test mode is implemented. It is a subset of IEEE Standard 1149.1 [1] in pin configurations and in operational modes to reduce chip size burden. Each channel has its own scan chain and scan clock input. To reduce the number of ballouts, this mode scans parallel data I/O and the scanned data propagates through the dedicated pins. Normal device operation is performed after the boundary scan test is finished. Figure 28.5.2 shows boundary scan block and AC timing diagram. This boundary scan chain is enabled when /SEN, scan enable pin, is low. The data input from the pad is captured when /SSH, scan shift pin, is low, and it is shifted along the chain when /SSH is high. SDI, SDO and SCK pins are for scan input, output and clock, respectively.We also adopt typical metal pads for test purposes since it is difficult to probe small microbumps directly. These pads are aligned in vertical direction at the chip center to allow precise correlation with microbumps and to reduce skews between channels. With test pads, this DRAM is handled as SDR×16, but internally as SDR×128 per channel. Selections of 16 out of 512 data can be done with column addresses, which are for the read-out of result data through test pads. Figure 28.5.3 shows correlation scheme between microbumps and test pads in data write/read operations. Through test pads, 9.3ns delayed outputs of microbumps, 2ns for clock propagation from pad and 7.3ns for data transfer from microbump to pad, are measured. Because we redirect outputs from microbumps and i...

Background The World Health Organization (WHO) declared coronavirus disease (COVID-19) a pandemic on March 11, 2020. Previous studies of infectious diseases showed that infectious diseases not only cause physical damage to infected individuals but also damage to the mental health of the public. Therefore this study aims to analyze the factors that affected depression in the public during the COVID-19 pandemic to provide evidence for COVID-19-related mental health policies and to emphasize the need to prepare for mental health issues related to potential infectious disease outbreaks in the future. Results This study performed the following statistical analyses to analyze the factors that influence depression in the public during the COVID-19 pandemic. First, to confirm the level of depression in the public in each country, the participants’ depression was plotted on a Boxplot graph for analysis. Second, to confirm personal and national factors that influence depression in individuals, a multi-level analysis was conducted. As a result, the median Patient Health Questionnaire-9 (PHQ-9) score for all participants was 6. The median was higher than the overall median for the Philippines, Indonesia, and Paraguay, suggesting a higher level of depression. In personal variables, depression was higher in females than in males, and higher in participants who had experienced discrimination due to COVID-19 than those who had not. In contrast, depression was lower in older participants, those with good subjective health, and those who practiced personal hygiene for prevention. In national variables, depression was higher when the Government Response Stringency Index score was higher, when life expectancy was higher, and when social capital was higher. In contrast, depression was lower when literacy rates were higher. Conclusions Our study reveals that depression was higher in participants living in countries with higher stringency index scores than in participants living in other countries. Maintaining a high level of vigilance for safety cannot be criticized. However, in the current situation, where coexisting with COVID-19 has become inevitable, inflexible and stringent policies not only increase depression in the public, but may also decrease resilience to COVID-19 and compromise preparations for coexistence with COVID-19. Accordingly, when establishing policies such as social distancing and quarantine, each country should consider the context of their own country.

In a recent report, the British Broadcasting Company (BBC) introduced South Korea’s measures to manage COVID-19 as role model for the world. Screening centers serve as frontiers for preventing community transmission of infectious diseases. COVID-19 screening centers in Korea operate 24 h a day, always open for individuals with suspected COVID-19 symptoms. South Korea concentrated COVID-19 screening centers around cities with high population density. Advanced screening centers (models C, D, and E) proved more effective and efficient in the prevention of COVID-19 than the traditional screening centers (models A and B). Particularly, screening centers at Incheon Airport in South Korea prevent transmission through imported cases effectively. It will be important elsewhere, as in South Korea, to establish an infectious disease delivery system that can lead to 'Test-Treat-Track' using an adequate model of screening centers.