The impact of regional emissions (e.g., domestic and international) on surface particulate matter (PM) concentrations in the Seoul metropolitan area (SMA), South Korea, and its sensitivities to ...meteorology and emissions inventories are quantitatively estimated for 2014 using regional air quality modeling systems. Located on the downwind side of strong sources of anthropogenic emissions, South Korea bears the full impact of the regional transport of pollutants and their precursors. However, the impact of foreign emissions sources has not yet been fully documented. We utilized two regional air quality simulation systems: (1) a Weather Research and Forecasting and Community Multi-Scale Air Quality (CMAQ) system and (2) a United Kingdom Met Office Unified Model and CMAQ system. The following combinations of emissions inventories are used: the Intercontinental Chemical Transport Experiment-Phase B, the Inter-comparison Study for Asia 2010, and the National Institute of Environment Research Clean Air Policy Support System. Partial contributions of domestic and foreign emissions are estimated using a brute force approach, adjusting South Korean emissions to 50 %. Results show that foreign emissions contributed ∼ 60 % of SMA surface PM concentration in 2014. Estimated contributions display clear seasonal variation, with foreign emissions having a higher impact during the cold season (fall to spring), reaching ∼ 70 % in March, and making lower contributions in the summer, ∼ 45 % in September. We also found that simulated surface PM concentration is sensitive to meteorology, but estimated contributions are mostly consistent. Regional contributions are also found to be sensitive to the choice of emissions inventories.
Advancements in convolutional neural network (CNN) have resulted in remarkable success in various computing fields. However, the need to protect data against external security attacks has become ...increasingly important because inference process in CNNs exploit sensitive data. Secure Memory is a hardware-based protection technique that can protect the sensitive data of CNNs. However, naively applying secure memory to a CNN application causes significant performance and energy overhead. Furthermore, ensuring secure memory becomes more difficult in environments that require area efficiency and low-power execution, such as the Internet of Things (IoT). In this paper, we investigated memory access patterns for CNN workloads and analyzed their effects on secure memory performance. According to our observations, most CNN workloads intensively write to narrow memory regions, which can cause a considerable number of counter overflows. On average, 87.6% of total writes occur in 6.8% of the allocated memory space; in the extreme case, 93.9% of total writes occur in 1.4% of the allocated memory space. Based on our observations, we propose an efficient integrity-tree structure called Countermark-tree that is suitable for CNN workloads. The proposed technique reduces overall energy consumption by 48%, shows a performance improvement of 11.2% compared to VAULT-128, and requires a similar integrity-tree size to VAULT-64, a state-of-the-art technique.
This study identified the key chemical components based on an analysis of the seasonal variations of ground level PM2.5 concentrations and its major chemical constituents (sulfate, nitrate, ammonium, ...organic carbon, and elemental carbon) in the Seoul Metropolitan Area (SMA), over a period of five years, ranging from 2012 to 2016. It was found that the mean PM2.5 concentration in the SMA was 33.7 μg/m3, while inorganic ions accounted for 53% of the total mass concentration. The component ratio of inorganic ions increased by up to 61%–63% as the daily mean PM2.5 concentration increased. In spring, nitrate was the dominant component of PM2.5, accounting for 17%–32% of the monthly mean PM2.5 concentrations. In order to quantify the impact of long-range transport on the SMA PM2.5, a set of sensitivity simulations with the community multiscale air-quality model was performed. Results show that the annual averaged impact of Chinese emissions on SMA PM2.5 concentrations ranged from 41% to 44% during the five years. Chinese emissions’ impact on SMA nitrate ranged from 50% (winter) to 67% (spring). This result exhibits that reductions in SO2 and NOX emissions are crucial to alleviate the PM2.5 concentration. It is expected that NOX emission reduction efforts in China will help decrease PM2.5 concentrations in the SMA.
The evolution of mobile communication technology has brought about significant changes in the way people communicate. However, the lack of nonverbal cues in computer-mediated communication can make ...the accurate interpretation of emotions difficult. This study proposes a novel approach for using emotions as active input in mobile systems. This approach combines psychological and neuroscientific principles to accurately and comprehensively assess an individual's emotions for use as input in mobile systems. The proposed technique combines facial and heart rate information to recognize users' five prime emotions, which can be implemented on mobile devices using a front camera and a heart rate sensor. A user evaluation was conducted to verify the efficacy and feasibility of the proposed technique, and the results showed that users could express emotions faster and more accurately, with average recognition accuracies of 90% and 82% for induced and intended emotional expression, respectively. The proposed technique has the potential to enhance the user experience and provide more personalized and dynamic interaction with mobile systems.
Conventional error correcting codes (ECC) for caches are applied to all cache lines and stored in dedicated SRAM storage, which incurs both space and energy overheads. In contrast, we propose a Smart ...ECC Allocation (SEA) cache that utilizes cache data space for low-cost error protection of last-level caches. SEA cache avoids the requirement for dedicated storage for ECC check bits, which are stored in cache lines as data. To effectively utilize cache space, we group several cache sets and manage them according to program behavior. SEA cache eliminates the considerable space overheads of conventional ECC schemes without noticeable reliability and performance degradation.
Recent changes of surface particulate matter (PM) concentration in the Seoul Metropolitan Area (SMA), South Korea, are puzzling. The long-term trend of surface PM concentration in the SMA declined in ...the 2000s, but since 2012 its concentrations have tended to incline, which is coincident with frequent severe hazes in South Korea. This increase puts the Korean government's emission reduction efforts in jeopardy. This study reports that interannual variation of surface PM concentration in South Korea is closely linked with the interannual variations of wind speed. A 12-year (2004-2015) regional air quality simulation was conducted over East Asia (27-km) and over South Korea (9-km) to assess the impact of meteorology under constant anthropogenic emissions. Simulated PM concentrations show a strong negative correlation (i.e. R = -0.86) with regional wind speed, implying that reduced regional ventilation is likely associated with more stagnant conditions that cause severe pollutant episodes in South Korea. We conclude that the current PM concentration trend in South Korea is a combination of long-term decline by emission control efforts and short-term fluctuation of regional wind speed interannual variability. When the meteorology-driven variations are removed, PM concentrations in South Korea have declined continuously even after 2012.
Due to increasing concern about various errors, current processors adopt error protection mechanisms for their on-chip components. Especially, protecting caches in current processors incurs as much ...as 12.5 percent area overhead due to error-correcting codes (ECCs). Considering large L2/L3 caches employed in current high-performance processors, the area overhead is very high, consuming a large number of on-chip transistors. As an attempt to reduce that overhead, this paper proposes an area-efficient error protection architecture for large L2/L3 caches. First, it selectively applies ECC to only dirty cache lines, and other clean cache lines are protected by using simple parity check codes. Second, the dirty cache lines are periodically cleaned by exploiting the generational behavior of cache lines in order not to increase traffic to the off-chip main memory. Experimental results show that the cleaning technique effectively reduces the average number of dirty cache lines per cycle. The ECCs of the reduced dirty cache lines can be confined in a small ECC array or ECC cache. Our proposed error protection architecture has been shown to reduce the area overhead of a 1-Mbyte L2 cache for error protection by 59 percent with less than 1 percent performance degradation, on the average, using SPEC2000 benchmarks running on a typical four-issue superscalar processor. A dirty cache line cleaning scheme is also beneficial for reducing the vulnerability of tag arrays to soft errors.
•We evaluated the association between chronic PM2.5 exposure and COPD development in elderly.•A retrospective cohort based on health insurance data and time-varying COX model were used.•We followed ...687,940 elderly subjects residing metropolitan cities in Korea for 6 years (2011 to 2016)•A 10 μg/m3 increase in 60-month moving average PM2.5 was associated with 9% increase in COPD development.•Long-term PM2.5 exposure showed positive association with COPD development.
Studies evaluating the role of long-term exposure to fine particulate matter (PM2.5) on chronic obstructive pulmonary disease (COPD) development showed inconsistent results and were limited to Western countries. We aimed to determine the association between long-term exposure to PM2.5 and COPD development in metropolitan cities in Korea, which have higher PM2.5 levels than those in Western country studies.
We constructed a retrospective cohort (elderly aged over 65 years who resided in 7 metropolitan cities in 2008) using Korea health insurance data. A total of 687,940 elderlies who had not visited hospitals due to COPD for 3 years (from 2008 to 2010) were followed-up from 2011 to 2016. The first hospital visit due to COPD during the follow-up period was regarded as COPD development. Daily district-level PM2.5 concentrations were estimated by chemical transport model and 60-month moving average PM2.5 were assigned to each subject in time-varying Cox proportional hazard model.
The mean concentration of modelled PM2.5 in 7 metropolitan cities during the study period (from 2006 to 2016) was 28.0 μg/m3 and 259,700 subjects newly visited the hospital due to COPD. COPD hospital visit hazard ratio for a 10 μg/m3 increase in 60-month moving average PM2.5 concentration was 1.09 (95% confidence interval: 1.07, 1.11). Risks remained unchanged following different PM2.5 exposure levels (48-month moving average, and average PM2.5 concentrations for 2008 and 2008–2010) and in subgroup analysis by subject characteristics (sex, age, and income groups).
By following-up 687,940 elderly subjects who resided in metropolitan cities in Korea for 6 years, long-term PM2.5 exposure showed association with COPD development.
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We propose a method to adjust contributions from upwind emissions to downwind PM2.5 concentrations to account for the differences between observed and simulated PM2.5 concentrations ...in an upwind area. Emissions inventories (EI) typically have a time lag between the inventory year and the release year. In addition, traditional emission control policies and social issues such as the COVID-19 pandemic cause steady or unexpected changes in anthropogenic emissions. These uncertainties could result in overestimation of the emission impacts of upwind areas on downwind areas if emissions used in modeling for the upwind areas were larger than the reality. In this study, South Korea was defined as the downwind area while other regions in Northeast Asia including China were defined as the upwind areas to evaluate applicability of the proposed adjustment method. We estimated the contribution of emissions released from the upwind areas to PM2.5 concentrations in South Korea from 2015 to 2020 using a three-dimensional photochemical model with two EIs. In these two simulations for 2015–2020, the annual mean foreign contributions differed by 4.1–5.5 µg/m3. However, after adjustment, the differences decreased to 0.4–1.1 µg/m3. The adjusted annual mean foreign contributions were 12.7 and 8.8 µg/m3 during 2015–2017 and 2018–2020, respectively. Finally, we applied the adjustment method to the COVID-19 pandemic period to evaluate the applicability for short-term episodes. The foreign contribution of PM2.5 during the lockdown period in China decreased by 30% after adjustment and the PM2.5 normalized mean bias in South Korea improved from 15% to −4%. This result suggests that the upwind contribution adjustment can be used to alleviate the uncertainty of the emissions inventory used in air quality simulations. We believe that the proposed upwind contribution adjustment method can help to correctly understand the contributions of local and upwind emissions to PM2.5 concentrations in downwind areas.
We estimated long-term foreign contributions to the particulate matter of 2.5 μm or less in diameter (PM2.5) concentrations in South Korea with a set of air quality simulations. The Weather Research ...and Forecasting (WRF)-Sparse Matrix Operator Kernel Emissions (SMOKE)-Community Multiscale Air Quality (CMAQ) modeling system was used to simulate the base and sensitivity case after a 50% reduction of foreign emissions. The effects of horizontal modeling grid resolutions (27- and 9-km) was also investigated. For this study, we chose PM2.5 in South Korea during 2010–2017 for the case study and emissions from China as a representative foreign source. The 9-km simulation results show that the 8-year average contribution of the Chinese emissions in 17 provinces ranged from 40–65%, which is ~4% lower than that from the 27-km simulation for the high-tier government segments (particularly prominent in coastal areas). However, for the same comparison for low-tier government segments (i.e., 250 prefectures), the 9-km simulation presented lowered the foreign contribution by up to 10% compared to that from the 27-km simulation. Based on our study results, we recommend using high-resolution modeling results for regional contribution analyses to develop an air quality action plan as the receptor coverage decreases.
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