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2017-10 02 Headline News

[Academics][Researcher of the Month] Producing Energy Through a Single Thread

'Lack of energy’ is an issue the whole world is focusing on. Various countries are searching for effective renewable energy and new materials that could replace the current energy sources. Professor Kim Seon-jeong (Department of Biomedical Engineering) discovered a new material every researcher was looking for. Kim's paper, “Harvesting electrical energy from carbon nanotube yarn twist” introduces the world’s first new material, which can produce energy through slight movements. Kim explains the concept of his new material Professor Kim’s research team started its first project in 2006 on artificial muscle. However, after his research, Kim realized its limitations as they were only able to move through an external energy source. Therefore, he thought of a new idea that the muscle would be more effective when it is able to produce energy by itself. Carbon nanotube is a new material which is a type of conductor and has a diameter of only a few nanometers. This material was made as a thread in the artificial muscle. However, when these threads were finely twisted into one direction, they were able to produce energy by itself through its contraction and relaxation without an applied voltage. Being made into a spring, their length can be changed as much as 30 percent on average. This new material, named as ‘twistron harvester yarn’, allowed a chance for the muscle to move by itself without a separate power source. This twistron harvester yarn looks and acts as if it were an ordinary thread. This states that making clothes out of this material is possible. Once this comes into realization, this would give a boost in making wearable devices, as producing electricity without an energy source is possible. Moreover, this thread is possible to use inside water, giving another possibility of an effective alternative energy. This has already been tested in the East Sea of Korea. Kim’s research team made a model consisting of a glass bottle connected with an electrode, the thread, a balloon, and an equipment that could measure electricity. As the twistron harvester yarn contracted and relaxed, electrical energy was verified from the ocean. Kim showed great passion in the research he was conducting. This research on the twistron harvester yarn was his fourth research. He has been working on artificial muscles for the past nine years before he started this research. “I didn’t start this research solely to find the twistron harvester yarn. I felt the limitations within the research I conducted earlier and was seeking for development,” reminisced Kim. He explained that he wasn’t the only person who conducted the research. Eight teams from three different countries worked on this new material for two years to deduct a better result. “We had a meeting through Skype every week, along with frequent visits to each team. Everyone had great passion and interest towards this research, and I believe that shows the firmness of this research,” said Kim. "Reach towards your own interest!" Kim also emphasized the attitudes Hanyangians should have towards their life. Even though he mainly teaches graduate school students, he wished all students could find what they truly wish to do. “Find something unique of your own. Find something you enjoy, and then you will be able to continue on with whatever you are doing. There are countless routes for all students. I wish students would keep challenging themselves to make the greatest results of their own,” wished Kim. Just as his words, Kim will continue with his work with great passion, for even better convenience for global citizens. On Jung-yun jessica0818@hanyang.ac.kr Photos by Kim Youn-soo

2017-09 11

[Academics]Making a Better Environment to Live In

Until the 21st century, the world has gone through excessive amounts of civilization. People were able to make various visible developments while failing to keep the environment without pollution. Professor Kim Ki-hyun of the Department of Civil and Environmental Engineering, therefore, focused on the environmental problems through his paper, “Biochar as a Catalyst”. Through the paper, he introduced a new material that could better purify various impurities. Biochar is a compound word of ‘bio’ and ‘char’, which is biology and charcoal. This material is a type of waste that is produced when you burn any biological materials that possess carbon. Just as charcoal is made when you burn trees, biochar is made when you burn biological materials. Through this not-so-helpful looking waste, people can purify the environment. When soil is polluted with something, such as oil, pesticides or heavy metal, biochar can be effectively used to absorb these contaminations. They combine well with toxic substances; therefore, it allows purification of soil only though scattering these materials in the soil and skimming them out again. The picture of the process of making biochar. (Photo courtesy of Kim) Kim introduced his overall research related to biochar. He studies various metal organic frameworks, which are much like biochars, used to purify polluted environments. “There are over 20 thousand types of metal organic frameworks, and I am currently working on which framework will be the most effective when purifying pollution,” explained Kim. Moreover, he talked about electronic cigarettes which are a relatively newly introduced invention. As there isn’t a proven result of the components within the electronic cigarette, Kim is working on the methods to discover the dangers of them. Kim said, “There isn’t a precise database related to electronic cigarettes. They could also consist of numerous cancer-causing agents and harm, just as original cigarettes does. I intend on discovering these substances and, furthermore, purify them.” Kim, however, does not solely research on this one material. He pays attention to the general issues within the society. His main interest lies on various aerial issues such as air pollution, fine dust, indoor pollution and stenches. Kim said, “There, indeed, are a lot of problems regarding pollution related issues. However, there are also a lot of methods that can be used to solve these problems. My goal is to make effective solutions through comprehensive research.” He explained that the biochar mentioned in his paper is only a small example of his overall goal. He intends to research on more new materials and solve various social issues. Kim hopes people could have correct information on the environment. Kim hopes that people would have a better understanding of environmental pollution. “When the dust level exceeds 100 microgram per 1 cubic meter, the Ministry of Environment suggests to refrain from going out. However, when people wear masks right after they smoke to protect themselves from fine dust, they breathe in eight hundred to nine hundred micrograms of dust. Due to excessive amounts of information, people sometimes make contradictory actions,” explained Kim. He wished that more environmental education would be made in the pursuit of proper knowledge. He added that Hanyang University students should give more interest towards the environment. “Let’s keep the air clean, with correct information!” On Jung-yun jessica0818@hanyang.ac.kr Photos by Park Young-min

2017-07 23

[Academics]Vitalization in Detecting NO2 in Daily Life

As environmental pollution is deteriorating, various hazardous gas face people unrecognizably in their daily lives. Professor Kim Hyoun-woo of the Division of Material Science and Engineering is an active researcher in various sensors that could help identify various gas, humidity, or even radiation. His recent paper “Enhancement of gas sensing properties by the functionalization of ZnO-branched SnO2 nanowires with Cr2O3 nanoparticles” proposes another effective method of detecting a particular gas, NO2. Kim expaining the nanostructure of his paper. His research aimed for an effective NO2 detecting nanostructure, which is a structure made from molecules. NO2, also called as nitrogen dioxide, is required to be detected since it can be found relatively easily through the atmosphere even when it is a toxic, air-contaminant gas. Kim mentioned “Once a practical method through this nanostructure is constructed, I wish people can be easily detect this toxic gas.” This nanostructure is composed of three different substances. First of all, a SnO2 (tin oxide) nanowire is required. A nanowire is a nanostructure of an extreme, fine line which has a diameter of one nanometer (10−9 meters). Next, ZnO (zinc oxide) nanowires are branched on the SnO2 nanowire. Then the last substance, which are Cr2O3 (chromium oxide) nanoparticles, would grow on the ZnO nanowires. With a completed nanostructure, detecting NO2 become possible. An illustration of Cr2O3 -functionalized ZnO branched SnO2 nanowires. (photo courtesy of Kim) This nanostructure mentioned in his paper is highly sensitive, which makes it a significant structure. A current always flows within a structure, and a resistance is made whenever there is a current. However, the resistance differs when there is an inflow of another gas. The external gas takes away the electron in the structure, therefore heightening the resistance of the structure. The sensitivity is determined through resistance within the sensor. When the sensitivity is elevated, a structure can perceive more NO2 than the one with low sensitivity even when there’s a same amount in the air. The nanostructure mentioned in the paper is indeed a unique technology. However, Kim also mentioned the insufficiency of this nanostructure. In order to detect NO2, this gas needs to be heated in an extremely high temperature; in the case of the paper, 300’C. Therefore, there is a difficulty for people to sense the gas in the current stance. Kim mentioned that he wants to improve this difficulty through further research. He is currently working on methods that could allow this nanostructure to detect NO2 in a room temperature. Kim wishes to develop a practical nanostructure. Kim is an enthusiastic researcher. He constantly works on structures that could benefit people in their daily lives. He is striving for extreme-high sensitivity in his structures so that people could quickly recognize and react to the contamination. Kim mentioned “I want to make a structure that can be commercialized. A lot of the inventions disappear due to the lack of cost competency or efficiency. I wish to contribute to the promotion of mankind welfare.” On Jung-yun jessica0818@hanyang.ac.kr Photos by Kim Youn-soo