On the afternoon of the 24th, due to the smog carried by the westerly winds, the concentration of fine dust across the country indicated 'bad.' The same was true near Seodaejeon Intersection Station in Seo-gu, Daejeon, where most people walking in the gray sky were wearing masks.
As the chill of winter withdrew, fine dust arrived in Korea faster than the spring atmosphere. Fine dust mixed with yellow dust and smog adversely affects not only the environment but also human health. This is why the development of technology to prevent fine dust is urgent.
The Korea Institute of Machinery and Materials unveiled a fine dust reduction device that can be used in subway stations. This new device does not require filter replacement, making maintenance easy, and has improved the fine dust reduction rate compared to existing devices.
The new device developed by the Korea Institute of Machinery and Materials is currently operating at three stations, including Seodaejeon Intersection Station. Entering the underground air conditioning room at Seodaejeon Intersection Station that afternoon, we could see the fine dust reduction device in operation. As this 2-meter wide and tall device started to function, the fine dust levels on the monitor dropped sharply within 10 seconds with a grand noise. The levels that were previously 'bad' (46㎍/㎥) quickly fell to a 'good' level of 3㎍/㎥.
This device, developed by the Korea Institute of Machinery and Materials, was initiated in 2021 following a proposal from the Daejeon Transportation Corporation. In response to calls for low-cost and eco-friendly fine dust reduction technology for subways, the Ministry of Science and ICT delegated the Korea Institute of Machinery and Materials to carry out the project as a public R&D task. At that time, the fine dust reduction device distribution rate in Daejeon was low compared to Seoul (20%) and Daegu (50%), and existing devices consumed a lot of power and required metal plates to be washed with water, resulting in numerous maintenance issues.
Lead researcher Kim Hak-jun from the Korea Institute of Machinery and Materials noted, 'Previously, we developed technology first and created R&D demand; however, this time, a public institution first presented the need, and we led the demonstration and commercialization accordingly.'
Existing fine dust reduction devices for subways were filter-based. However, as time passed, dust accumulated on the filter, obstructing air flow, and there were issues with rising maintenance expenses, such as filter cleaning. To replace this, static electricity methods were introduced, but this led to side effects such as excessive ozone generation due to the use of high voltage.
To address this, the Korea Institute of Machinery and Materials introduced a technology using ultra-thin microfibers as electrodes. A current flows through micrometer-level (㎛, 1㎛ is 1-millionth of a meter) electrodes thinner than a hair to generate negative ions, which attach to the fine dust, and positively charged collection plates attract them. Approximately 300 electrodes are densely arranged on the collection plate, which has an area of about 4㎡. While previous electrodes required high voltage due to their thickness being in millimeter units, the newly applied technology uses ultra-fine electrodes and thus consumes less power.
The cleaning method is also simple. Previously, a large amount of water was used for washing, followed by a lengthy drying period, which was common for wet methods. This new device adopts a dry method that blows air from the opposite side to dislodge dust, enabling easy cleaning during nighttime.
Having undergone a year-long demonstration phase, this device is now installed in three stations, including Seodaejeon Intersection Station, and is currently in operation. The fine dust emissions in the tunnel have decreased by 73%, and the indoor air quality has improved by 22%. The Korea Institute of Machinery and Materials explained that if the reduction devices are expanded across all stations, the reduction rates will further increase. Additionally, the ozone generation rate is at 4 parts per billion (ppb), significantly lower than the general atmospheric level of about 30 ppb.
The Korea Institute of Machinery and Materials is transferring related technology to KC Cottrell, YT Systems, and SeGi. Researcher Kim explained, 'KC Cottrell handles large-scale facilities, while YT Systems is commercializing small devices together with SeGi.'
The Korea Institute of Machinery and Materials is reviewing ways to apply this technology in schools, department stores, industrial facilities, and semiconductor processes. In particular, the application of technology in schools is expected to have a significant ripple effect. The filter replacement expense of air purifiers currently used in 300,000 classrooms nationwide reaches 30 billion won annually. If a filter-free air purifier is introduced, significant cost savings are anticipated.
Ryu Seok-hyun, president of the Korea Institute of Machinery and Materials, stated, 'We have developed a world-class fine dust reduction technology after over 20 years of research into electrostatic technology at the Korea Institute of Machinery and Materials, and we have proven its stability and effectiveness through two years of demonstration. We will continue to expand its application to more public facilities to contribute to the health of the public.'