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Human activities, including walking, generate an airflow, commonly known as the slipstream, which can disperse contaminants indoors and transmit infection to other individuals. It is important to understand the characteristics of airflow to prevent the dissemination of contaminants such as viruses. A cylinder of diameter 500 mm, which is the average shoulder width of an adult male, was installed in a motorcar and moved at a velocity of 1.2 m/s, which is the walking speed of an adult male. The velocity profile of the slipstream generated during this movement was measured by locating the sensor support at 0.15–2.0 m behind the cylinder. The wind velocity was set to 1.2 m/s to conduct the numerical analysis. The measurement data revealed the velocity profile of the space behind the cylinder, and a comparison of the numerical analysis and the measurement results indicate very similar u (measured velocity)/U (moving velocity) results, with a maximum difference of 0.066, confirming that the measured values were correctly estimated from the results of the numerical analysis.

The inactivation of viruses that retain their infectivity when transmitted through the air is challenging. To address this issue, this study used a non-contact ultrasound transducer (NCUT) to generate shock waves in the air at specific distances, input voltages, and exposure durations, targeting bacteriophage virus aerosols captured on to H14 HEPA filters. Initially, a frequency of 27.56 kHz (50V) at 25-mm distance was used, which yielded an inactivation efficiency of up to 32.69 ± 12.10%. Other frequencies at shorter distances were investigated, where 29.10 kHz had the highest inactivation efficiency (up to 81.95 ± 9.79% at 8.5-mm distance and 100 V). Longer exposure times also influenced virus inactivation, but the results were inconclusive because the NCUT overheated with time. Overall, NCUT appears to be a promising method for inactivating virus aerosols that may be safer than other forms of inactivation, which can cause genetic mutations or produce dangerous by-products.

In this study, measurements were carried out to identify the generation characteristics of wear particles emitted under a subway cabin during operation. Along with a fast mobility particle sizer, probes were installed under a subway cabin and in a subway tunnel to measure the size distributions of nanoparticles at 1-s intervals. Based on the particle density measured under the cabin minus that measured in the tunnel, the size distribution of wear particles generated under the cabin during deceleration was estimated to be bimodal at 165.5 nm and 6.98 nm. These particles were most likely generated from wheel-rail contact, as the train utilized electric braking (no mechanical force applied). In addition, a change in the wear mechanism appears to have arisen due to the increased temperature of the wheel-rail contact while nanoparticles were being emitted, leading to an initial generation of 165.5-nm particles followed by 6.98-nm particles 1 s later.

Emission reduction is one of the most efficient control measures in fuel-powered locomotives. The purpose of this study was to determine the reduction in particulate matter (PM) and black carbon (BC) emissions following the installation of a fuel activation device (FAD). The FAD was developed to enhance fuel combustion by atomizing fuel and to increase the surface area per unit volume of injected fuel. Emission reduction by the FAD was evaluated by installing a FAD in an operating diesel locomotive in Mongolia. The test was conducted on a train operating on a round-trip 238-km route between Ulaanbaatar and Choir stations in Mongolia. The fuel consumption rate was slightly reduced following the FAD installation. The FAD installation decreased PM and BC emissions in the diesel locomotive, especially coarse PM. The PM10 reductions achieved after FAD installation were 58.0, 69.7, and 34.2% for the constant velocity, stopping, and acceleration stages of the train's operation, respectively. The BC reduction rates were 29.5, 52.8, and 27.4% for the constant velocity, stopping, and acceleration stages, respectively.

According to the increasing concern about particulate matter (PM) pollution at subway systems, particularly its potentially severe effects on human health, this study investigated the constituents, characteristics, and toxicity of PM collected at underground subway stations in Seoul, Korea. It was found that α/γ-Fe

In this study, we describe a novel peroxidase-like activity of Co-aminoclay [CoAC] present at pH ~5.0 and its application to fluorescent biosensor for the determination of H2O2 and glucose. It is synthesized with aminoclays (ACs) entrapping cationic metals such as Fe, Cu, Al, Co., Ce, Ni, Mn, and Zn to find enzyme mimicking ACs by sol–gel ambient conditions. Through the screening of catalytic activities by the typical colorimetric reaction employing 2,2′-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid)diammonium salt (ABTS) as a substrate with or without H2O2, Fe, Cu, and CoACs are found to exhibit peroxidase-like activity, as well as oxidase-like activity was observed from Ce and MnACs. Among them, CoAC shows exceptionally high peroxidase-like activity, presumably due to its ability to induce electron transfer between substrates and H2O2. CoAC is then used to catalyze the oxidation of Amplex® UltraRed (AUR) into a fluorescent end product, which enables a sensitive fluorescent detection of H2O2. Moreover, a highly sensitive and selective glucose biosensing strategy is developed, based on enzyme cascade reaction between glucose oxidase (GOx) and CoAC. Using this strategy, a highly linear fluorescence enhancement is verified when the concentration of glucose is increased in a wide range from 10 μM to 1 mM with a lower detection limit of 5 μM. The practical diagnostic capability of the assay system is also verified by its use to detect glucose in human blood serum. Based on these results, it is anticipated that CoAC can serve as potent peroxidase mimetics for the detection of clinically important target molecules.

The level of particulate matter of less than 10 μm diameter (PM10) at subway platforms can be significantly reduced by installing a platform screen-door system. However, both workers and passengers might be exposed to higher PM10 levels while the cars are within the tunnel because it is a more confined environment. This study determined the PM10 levels in a subway tunnel, and identified the sources of PM10 using elemental analysis and receptor modeling. Forty-four PM10 samples were collected in the tunnel between the Gireum and Mia stations on Line 4 in metropolitan Seoul and analyzed using inductively coupled plasma-atomic emission spectrometry and ion chromatography. The major PM10 sources were identified using positive matrix factorization (PMF). The average PM10 concentration in the tunnels was 200.8 ± 22.0 μg/m3. Elemental analysis indicated that the PM10 consisted of 40.4% inorganic species, 9.1% anions, 4.9% cations, and 45.6% other materials. Iron was the most abundant element, with an average concentration of 72.5 ± 10.4 μg/m3. The PM10 sources characterized by PMF included rail, wheel, and brake wear (59.6%), soil combustion (17.0%), secondary aerosols (10.0%), electric cable wear (8.1%), and soil and road dust (5.4%). Internal sources comprising rail, wheel, brake, and electric cable wear made the greatest contribution to the PM10 (67.7%) in tunnel air. Implications: With installation of a platform screen door, PM10 levels in subway tunnels were higher than those on platforms. Tunnel PM10 levels exceeded 150 µg/m3 of the Korean standard for subway platform. Elemental analysis of PM10 in a tunnel showed that Fe was the most abundant element. Five PM10 sources in tunnel were identified by positive matrix factorization. Railroad-related sources contributed 68% of PM10 in the subway tunnel.

Perceived service quality (PSQ) has been shown to influence satisfaction, loyalty, and other important outcomes, specifically in a competitive environment and is also one of the foremost reasons for choosing an airline. The purpose of this study is to evaluate the difference in PSQ between full service carriers (FSCs) and low cost carriers (LCCs) in the South Korean domestic airline market, which has become more competitive due to the emergence of multiple LCCs. The results showed that PSQ of LCCs is lower than FSCs in terms of the rank of dimension although the trend was surprisingly similar. Moreover, the relationships between service quality dimensions and demographic factors were significantly different between the two types of carriers. These results suggest that new entrants in South Korea should have their own distinguishable service strategy from the FSC.

공공영역에서 디자인의 역할에 대한 비중이 높아지면서 디지털 매체를 통해 기능성을 가진 디지털콘텐츠가 많은 분야에서 이슈가 되고 있다. 이를 통한 디지털콘텐츠는 공공장소에서 디지털 커뮤니티 공간을 형성함에 따라서 사용자에게 즐거움과 다양한 정보를 제공해 주는 커뮤니케이션 콘텐츠들이 생겨나면서 큰 인기를 얻고 있다. 이는 대표적인 정보미디어 기기인 인포메이션 키오스크에서 제공하고 있는 디지털콘텐츠는 사용자에게 정보를 획득할 수 있는 편의성을 제공하고 있다. 국내의 경우에는 서울역 ‘아트 쉘터’와 서울 지하철의 ‘다음 디지털 뷰’등에 설치되어 사용자에게 흥미와 실시간 검색을 할 수 있는 공간으로 자리 잡고 있다. 이처럼 다양한 정보 제공하고 있는 키오스크에서 디지털콘텐츠의 유형을 통하여 콘텐츠의 특성 및 각 유형을 고려한 콘텐츠는 사용자에게 정보 제공뿐만 아니라 다양한 경험을 할 수 있는 화려한 인터페이스와 인터랙션이 가능한 콘텐츠로 개발이 이루어지고 있다. 이에 본 연구에서는 공공서비스를 제공하는 정보미디어 디스플레이 기기인 인포메이션 키오스크와 디지털콘텐츠의 역할에 대하여 알아보고, 사례분석을 통한 정보유형 도출하여 미래에 공공서비스에서 활용되어질 디지털콘텐츠에 대하여 고찰하고자 한다.

The part-feeding system at an assembly shop controls the feeding of parts from the warehouse to workstations of the assembly shop in accordance with the production of vehicles. The part-feeding system plays a crucial role in determining the level of the inventory and stockout rate at the automotive assembly line. In this study, we propose a dynamic part-feeding system for an automotive assembly plant which estimates the part consumption amounts dynamically considering the actual production progress and directs the feeding orders dynamically to feeders. The results of a simulation show that the proposed dynamic feeding system produces better results than a static feeding system.

This paper analyzes how the vegetable production region in Yachiyo Town has developed, clarifies the basis on which it is sustained and discusses the sustainability of rental fallow land use. The settlement of Osaki, which specializes in vegetable production, is selected as the study area in Yachiyo Town.Until about 1960, the main form of agriculture in Yachiyo Town was wheat and barley. A method of cultivation for water melons and Chinese cabbages was introduced by a regional leader in the early 1950s. The introduction of this method of cultivation is related to changes in the economic environment-for example, the importation of wheat after World War 2. The vegetable production region in Yachiyo Town is categorized in two stages based on the type of selling: The first stage in which the requirements of farm groups is sought, and the second stage in which the marketing of the individual farm is sought. The market, which is organized privately in the surrounding area, was established in the early 1960s. Most of the Chinese cabbages are shipped to the Tohoku and Hokkaido regions through these markets. As a result, Yachiyo Town is devoted to growing Chinese cabbage and occupied the first rank in Japan in the late 1960s.However, its productivity declined due to the repeated mono-cultivation of melons and Chinese cabbages. Vegetable production in vinyl plastic hothouses was introduced in the early 1970s, but this was not developed into the dominant agricultural form. The farmhouse has managed a large amount of rental fallow farmland both within and outside the area of the town. Internal factors, including social relationships between landlord and tenant farmer have influenced the farmer's decision-making with implications for the development and sustainability of the vegetable production region.