Development of PM2.5 management strategy in the industrial city of Ulsan : A comprehensive approach to understanding the risk and sources of PM2.5

Sang-Jin Lee Ulsan National Institute of Science and Technology 2024 국내박사

Differences in Public Perception of Geothermal Energy in Korea : National vs. Local

Hae-In Baek Ulsan National Institute of Science and Technology 2021 국내석사

This study investigates the public perception differences in geothermal power generation at the national and local levels through media content analysis and survey analysis. Media content analysis results indicated that the previously positive media framing for environment and technology drastically changed to a negative framing of risk after the Pohang earthquake, and there were no significant differences between national and local coverage. However, survey data showed that the local perception of geothermal energy was significantly more negative than that at the national level. The proximity to the earthquake epicenter was negatively correlated with the perception of geothermal energy. Regarding energy source preferences among local residents, geothermal power plants and nuclear power plants were placed in the same category. Pohang residents seemed to associate geothermal power plants with nuclear power plants in terms of risk discourse. They viewed several similarities, i.e., high risks, between the two technologies. As a result of the Pohang earthquakes being byproducts of geothermal power generation, geothermal energy is recognized as a threat or potential danger rather than a risk-free and environment-friendly renewable energy source. To reduce the renewable energy perception gap between the national public opinion and the locals’ view, sufficient and carefully planned communications with local residents are required. Before introducing renewable energy to a region, a strategically planned science/technology education outreach venture accompanied by an honest risk assessment for the locals is essential.

Factors Influencing the Public Acceptance of the Floating Offshore Wind Farm Development in Ulsan

Seonghee Yang Ulsan National Institute of Science and Technology 2022 국내석사

This thesis investigates the determinants of the public acceptance of the floating offshore wind farm development in Ulsan, highlighting the role of the community profit-sharing schemes. The Ulsan project is currently the largest floating offshore wind farm plan in the world and aims to install a total capacity of 9GW by 2030. As many cases at home and abroad demonstrated, public acceptance is a key success factor of large-scale renewable projects. Although there are many factors influencing public acceptance, profit-sharing schemes for local communities have recently drawn a significant attention from local residents and policy-makers alike. This thesis examines the individual effects of profit-sharing schemes and further their joint effects with other factors such as prior knowledge, trust, distributive and procedural justice, perceived risks and perceived costs, and perceived benefits. We collected data from a survey of 500 individuals who live in Ulsan and analyzed the data using OLS. The theoretical and policy implications of our empirical findings are discussed.

Social Construction of the ESS Fires in Korea : Focusing on Social Context Changes and the Stakeholders’ Experiences

Dong-Hyeon Im Ulsan National Institute of Science and Technology 2021 국내박사

Secondary Organic Aerosol and Ozone Formation Potential from Anthropogenic and Biogenic Volatile Organic Compounds in Ulsan, South Korea, in Summer

Geunwoo Lee Ulsan National Institute of Science and Technology 2021 국내석사

A large quantity of anthropogenic and biogenic volatile organic compounds (VOCs) is emitted in Ulsan because Ulsan has huge multi-industrial complexes in its eastern coastal area and high mountainous regions in the western hinterland. Some of the VOCs are oxidized and form tropospheric ozone and secondary organic aerosol (SOA) in the atmosphere. Not only high temperature and radiation but also the transport of VOCs from their sources could aggravate the photochemical oxidation reactions in the atmosphere in Ulsan in summer. Despite the environmental importance of photochemical reactions of VOCs, few studies on photochemical VOCs in Ulsan have been carried out. The objectives of this study are to investigate the spatial concentration levels of photochemical VOCs, estimate the formation potentials of ozone and SOA, and propose further research to figure out how much VOCs have contributed to high tropospheric ozone and particulate matter episodes in Ulsan, South Korea, in summer. Hybrid VOC monitoring was conducted with diffusive passive samplers (Radiello, Instituti Clinici Scientifici Maugeri, Itay) and active pumped adsorbent tube samplers (Sequential tube sampler-25, PerkinElmer, UK) at 17 sites (5 industrial, 6 rural, 6 urban sites) and three sites (1 control, 1 industrial, 1 rural site), respectively, in Ulsan from May to August 2020. Through the hybrid VOC sampling, the temporal and spatial resolution of Ulsan VOC monitoring was highly improved. The target VOCs were selected as photochemical assessment monitoring stations (PAMS) ozone precursor 53 VOCs (36 aliphatics and 17 aromatics). Both anthropogenic VOCs like benzene, toluene, ethylbenzene, and o,m,p-xylene (BTEX) and a biogenic VOC, isoprene, were included. All 240 VOC adsorbent samples were analyzed with a thermal desorber-coupled gas chromatography/mass spectrometer (TD-GC/MS, UNITY series 2, Markes, UK-7890B/5977A, Agilent, USA). Every sampling trip had field blank samples to track any contaminations from the whole analytical process. A 3:1 signal to noise ratio was applied to the quantification of VOCs. The concentration spatiotemporal distribution of the VOCs was comprehensively interpreted with the data of 16 meteorological observation stations in Ulsan, considering the physicochemical properties of the 53 VOCs. From May to August, the atmospheric temperature in Ulsan increased except for in July because July is the rainy period. Heavy rain was observed in July, causing relatively low temperatures and radiation. Due to the land-sea breeze in Ulsan, the transport of VOCs from industrial areas to highly urbanized areas occurred in the daytime while transport of VOCs from mountainous areas to the urban region occurred in the nighttime. Criteria air pollutants (CAPs) in rural and industrial sites were compared. Although the concentration of fine particulate matter (PM2.5) did not show statistically significant differences between the sites, NO2 was higher, and O3 was lower in the industrial site than in the rural sites. Also, O3 and the fine particulate matter to coarse particulate matter (PM10) ratio, whose change could indicate the secondary aerosol formation, showed strong diurnal variations in the rural sites but not in the industrial site. These differences in the concentration levels of NO2 and O3 and the diurnal variation between industrial and rural sites need to be contemplated in a further SOA and O3 formation study in Ulsan. Total VOCs (TVOCs), BTEX, and aliphatics exhibited significantly higher concentrations in industrial sites than in rural and urban sites. However, isoprene, a well known biogenic VOC (BVOC), showed a higher concentration in rural sites than in industrial and urban sites. This was obvious due to the BVOCs being emitted from the vegetation. In addition, isoprene concentrations had strong diurnal cycles depending on temperature and solar radiation. In order to identify the source and aging status of BTEX in each site, diagnostic ratios were applied to the BTEX concentration in each sampling site. Toluene to benzene ratio and m,p-xylene to ethylbenzene ratio were used as indicators for traffic emission and aging, respectively. BTEX in automobile and shipbuilding industrial areas were highly affected by fresh and non-traffic sources while BTEX in the harborside petrochemical industrial area were mostly influenced by fresh and traffic sources. Most rural and urban sites were affected by aged both traffic and non-traffic BTEX sources. The top 5 VOC contributors of ozone and SOA formation potentials (OFP and SOAFP) in different sites were compared in this study. In urban and rural sites, toluene, ethylbenzene, and xylenes (TEX) were dominant in the top 5 OFP contributors. In addition to TEX, n-octane and 3-methylpentane significantly contributed to OFP in industrial sites. Regardless of the sites, TEX made the biggest contribution to SOAFP. OFP and SOAFP from VOCs were highest in petrochemical and automobile industrial areas, respectively, in this study. However, the estimated formation potential of O3 and SOA could not explain the spatiotemporal variations of O3 and SOA based on the observed data. To improve the accuracy of the estimations, more VOCs, especially BVOCs, should be included in VOC monitoring and a better methodology to calculate formation potential with meteorological conditions needs to be developed. In conclusion, TEX largely influenced OFP and SOAFP in Ulsan in the summer. While controls for TEX over the Ulsan need to be enhanced to reduce photochemical oxidation reactions forming O3 and SOA, the study on BVOCs such as isoprenes and terpenes, is also needed due to the lack of understanding BVOCs in Ulsan. In order to improve the estimation of O3 and SOA formation, the key factors, such as meteorological conditions and atmospheric composition, should be investigated and considered in a non-linear way like through a machine learning approach.

A Gene-Centric Perspective of Scientific and Technological Innovations

Woochul Jung Ulsan National Institute of Science and Technology 2023 국내석사

유전자와 유전자 산물에 대한 연구는 현대 생명공학의 기초가 되며, 의학, 농업, 식량산업, 에너지 공급, 환경 정화 등 여러 분야로 응용이 가능한 것으로 알려져 있다. 이러한 과학적 발견들과 기술 혁신을 유전자 중심의 관점에서 거시적으로 조사하고자, 본 논문에서는 연구 논문과 특허에 대한 대규모 선별이 진행되었다. 각 유전자가 갖는 과학적 파급력을 보기 위해서 PubMed에서 접근 가능한 연구 논문 중 제목과 초록에 유전자 또는 유전자 산물이 언급된 자료들을 수집하였다. 기술 혁신 부분에 대응하는 자료로는 미국특허청(USPTO)에서 공개된 특허 출판물이 수집되었다. 문헌 자료 선별과 함께, 유럽 생물정보학 연구소에서 관리하는 UniProt 협의체 데이터베이스 중 선별·제공되는 일부 항목들의 유전자-단백질 명칭을 수집하였고, 이는 이후 유전자 간에 지나치게 중복된 명칭이나 두문자어로 인한 혼동을 방지하기 위해 원소가 공유되지 않는 집합들로 일관되게 군집되었다. 결과적으로 제목/초록에 이러한 유전자 항목을 언급한 논문과 특허들의 연도별 수치를 바탕으로 인간 유전체 프로젝트가 시작된 이후의 추세를 보고하였다. 각 유전자 인용 추세는 연구 논문에서와 비교할 때 발명 문헌에서 변동이 더 큰 것으로 보였고, 두 부문 모두 의료 분야에서 유전자 인용에 대한 기여가 두드러졌다. 지금까지 유전자를 인용한 문헌들은 증가 추세였으나 제목이나 초록에 새롭게 언급되는 유전자의 수는 최근들어 감소하였다. 반면, 이미 연구된 유전자들의 새로운 조합들이 활발히 탐구되는 것으로 보이며, 이러한 조합에 자주 포함된 유전자일수록 단순 인용 횟수의 상위권 유전자보다 생명공학의 발전을 잘 설명히는 것으로 보인다. Research on genes and gene products is a foundation of modern biotechnology, and recognized for its applicability in medicine, agriculture, food industry, energy supply, environmental remediation, and many others. To investigate a macroscopic and gene-centric perspective of scientific discoveries and technological innovations, we employed a large-scale curation of research papers and patents. As a raw data to represent the scientific impact of each gene, we collected the entire set of research articles available on PubMed, that have the names of genes or gene products in their title or abstract. The more dedicated literature source, the United States Patent and Trademark Office (USPTO) patent publication, was retrieved as a source data to represent the counterpart in technological innovations. In parallel with this literature curation, the gene symbols were collected from curated subset of UniProt consortium database maintained by European Bioinformatics Institute, and then clustered into the non-overlapping standardized sets to eliminate the overwhelming duplicates and possible contamination by common acronyms. Based on the annual counts of papers or patents whose titles/abstracts include a given gene, we show the overall trends of genetic research since the launch of the Human Genome Project. The gene citation fluctuated more in inventive activity compared to those in the research, while both sides were largely contributed by medicinal discipline. The volume of publications mentioning genes has been increased while the debut of new genes on titles and abstracts has been deflated. In contrast, new combinations of previously-studied genes kept actively explored, and their frequently adopted genes informed biotechnology innovations rather than sheerly top-studied genes.

Development of decision support systems for technology and business opportunity analysis

Gyumin Lee Ulsan National Institute of Science and Technology 2023 국내박사

Research on the Induction Heating Technology using Load Temperature Estimation and High-Voltage Output

GeunWook Kim Ulsan National Institute of Science and Technology 2022 국내석사

The induction heater directly applies electrical energy to the target and heats it by thermal energy conversion, unlike the conventional heating method. There are advantages of heating performance, high efficiency, and cleanliness through this. Unlike the existing fossil fuel combustion type, a current of AC frequency is generated through a coil to generate a magnetic field. This magnetic field forms an eddy current at the target, and heat is generated in the part where the current inside the target is generated. This operation procedure is different from making carbon gas such as coal and petroleum LPG as by-products. It has the advantage of not making flames and by-products accordingly, and safe heating is possible through electrical control. Application is roughly divided into domestic and industrial applications, and the research directions of the two fields are different. First of all, home applications focus on user convenience technology. For example, various studies have been conducted, such as a technology that enables operation in all-metal containers, a technology that reduces EMC emission caused by high frequency during operation, and estimating the temperature of the load. Among them, measuring the impedance of the load and estimating the temperature based on the impedance has expectations for automatic cooking in the future. Automatic cooking is a technique that informs the user of the recipe for the desired food and helps put the right ingredients at the right time. Estimating load impedance in the domestic cooker IH field to predict the state or temperature of cooking will serve as the basis for automatic cooking technology. In addition, it can be applied to secure safety by creating an alarm that informs water boiling alarm or overheating of the contents. In this thesis, user convenience technology has been studied for home applications by applying the above research direction. In industrial applications, research is being conducted to increase output power and speed up the heating of loads. The industry is demanding a method of increasing the temperature of the load by increasing output power rather than user convenience technology. To achieve a high output IH, an output voltage should be increased, and a device capable of operating at a constant frequency should be used. When a full-bridge inverter is implemented using a MOSFET device, there is a limitation in manufacturing high-power IH due to manufacturing a withstand voltage protection circuit and an increase in the unit price of a switching device. Using more switching elements, it is difficult to reconstruct a system suitable for the output power to expand the output capacity. This thesis proposes a method of stabilizing the system and easily extending the output by manufacturing an induction heating inverter in a modular manner and connecting input-parallel output-series. In this thesis, this study would like to present a design method for analyzing and producing induction heaters used as home cooking containers in the industry. In addition, for home cooking containers, user convenience technology was studied by adding impedance estimation technology. Industrial induction heaters constructed a modular inverter and increased the output voltage to study how to quickly heat and increase the range of operations that can be output. The above study was verified by simulation and experiment through a 2kW class induction heater.

Spatial-temporal variations and source identification of volatile organic compounds and their potential for O3 and SOA formation in the urban and industrial areas

Seong-Joon Kim Ulsan National Institute of Science and Technology 2021 국내박사

Volatile organic compounds (VOCs) have a critical impact on human health and the environment, and they are commonly emitted from a variety of sources, such as anthropogenic and biogenic sources. Also, VOCs are currently a big headache in the world due to their secondary formation for ozone (O3) and secondary organic aerosol (SOA) in the atmosphere. Seoul, one of the largest cities in Northeast Asia, is the capital city of South Korea with 9.8 million inhabitants and 3.1 million vehicles, and Ulsan located in the southeast of the Korean Peninsula with 1.1 million inhabitants is the largest industrial city, including automobile, heavy-shipbuilding, petrochemical, and non-ferrous industrial complexes in South Korea. Therefore, Seoul and Ulsan could have a significant impact on the VOC pollution from human (e.g., gasoline/diesel vehicular exhausts and printing/painting solvents) and industrial activities (e.g., solvent usage and production/combustion processes). Nevertheless, studies on the atmospheric VOCs and their potential for the O3 and SOA formation have been rarely conducted from now on. The integrated monitoring of atmospheric VOCs in this study was divided into (1) primary monitoring of VOCs in the urban city using passive air samplers (PASs), (2) subsequent monitoring of VOCs in the urban city using an active air sampler (AAS), and (3) simultaneous monitoring of air pollutants in the industrial city using the PAS. Finally, the implication for the control strategy of VOCs, SOA, and O3 was suggested. In the primary monitoring, PASs were seasonally deployed to measure 50 VOCs at 26 urban, 4 road, and 6 background sites in Seoul. Among the target compounds, toluene (summer: 8.72 μg/m3; winter: 5.47 μg/m3), ethyl acetate (summer: 2.36 μg/m3; winter: 3.51 μg/m3), and ethylbenzene (summer: 1.72 μg/m3; winter: 0.88 μg/m3) exhibited higher mean concentrations than other compounds. Printing offices and industrial facilities seem to have strong influences on the VOC levels in the center and southwest of Seoul, respectively. Diagnostic ratios indicated that the main sources of VOCs were related to local volatilization in summer and vehicular exhaust and transport from other areas in winter. Positive matrix factorization (PMF) suggested four major sources of VOCs: residential/commercial solvents for printing and painting (Factor 1); transport from other areas (Factor 2); industrial solvents for painting, manufacturing, and cleaning (Factor 3); and gasoline/diesel vehicular exhausts (Factor 4). Factors 1 and 3 were dominant in summer, and Factors 2 and 4 were dominant in winter. In conclusion, the seasonal meteorological conditions (e.g., temperature and wind patterns) were found to play an important role in the spatial distribution of VOCs in Seoul, and solvent use was a predominant source. In the subsequent monitoring, a sequential tube sampler (STS-25) was used to automatically collect 24 air samples for a day every month at an urban site in Seoul. The annual mean concentration of toluene (9.08 ± 8.99 μg/m3) was the highest, followed by ethyl acetate (5.55 ± 9.09 μg/m3), m,p-xylenes (2.79 ± 4.57 μg/m3), benzene (2.37 ± 1.55 μg/m3), ethylbenzene (1.81 ± 2.27 μg/m3), and o-xylene (0.91 ± 1.47 μg/m3), indicating that they accounted for 77.8–85.6% in four seasons. The Σ60 VOC concentrations in spring and winter were statistically higher compared to in summer and fall due to the location of sampling sites/periods, wind patterns, and major sources in the surrounding area. Overall, the concentrations of individual VOCs were higher during the time in the presence of sunlight than at late night and dawn due to human activities. From conditional bivariate probability function (CBPF) and concentration weighted trajectory (CWT) analysis, domestic effects, such as vehicular exhaust and solvents in Seoul seemed to be dominant; however, sometimes higher concentration events of VOCs might occur from China, North Korea, and industrial facilities nearby Seoul. Benzene, toluene, ethylbenzene, m,p,o-xylenes (BTEX) were the most abundant compounds for the secondary organic aerosol formation potential (SOAFP), which accounted for 5–29% of the PM2.5 concentration during the four seasons. The cancer and non-cancer risks for targeted VOCs were the safety level below the tolerable level (1 × 10-4) and the acceptable safe level (Hazard quotient: HQ < 1), respectively in this study area. Although the levels of the risk and the SOAFP for individual VOCs were not severe, human activities inner-Seoul were a predominant source and the transported effect was identified. In the simultaneous monitoring, PASs for VOCs, O3, NO2, and SO2 were deployed during four seasons 2019–2020 at 6 industrial and 10 urban sites in Ulsan. During the whole sampling periods, the concentration of toluene (mean: 8.75 μg/m3) was the highest among 50 VOCs, followed by m,p-xylenes (4.52 μg/m3), ethylbenzene (4.48 μg/m3), 3-methylpentane (4.40 μg/m3), n-octane (4.26 μg/m3). The seasonal variation of total VOC concentration was not statistically different, indicating that a large amount of VOCs is emitted to the atmosphere throughout a year as a characteristic of the industrial city. On the other hand, the concentrations of O3, NO2, and SO2 had a seasonal characteristic due to meteorological conditions and different sources. The spatial distributions of total VOCs, NO2, and SO2 showed that industrial complexes were major sources, while higher concentrations of O3 were observed in the outskirts of the sampling sites. From the PMF model, five major sources (Factor 1: production processes in the petrochemical industries and gasoline/diesel vehicular exhausts; Factor 2: solvent usage in automobile and ship manufacturing; Factor 3: production processes in the petrochemical/non-ferrous industries and ship emission; Factor 4: gasoline evaporation and combustion in the petrochemical/non-ferrous industries; and Factor 5: industrial solvent usage and secondary formation) were identified. Finally, aromatic compounds, such as m,p,o-xylenes, toluene, and 1,2,4-trimethylbenzene were determined as the most reactive compounds for the O3 formation; therefore, decreasing in the emission amount of these species can be more effective than reducing in that of NO2 in terms of the O3 reduction in the case of this study area. In conclusion, in comparison with the main sources between Seoul and Ulsan, the mean contribution of the main sources of VOCs was totally different. As expected, the effects from atmospheric VOCs primarily emitted from industrial activities were substantial in Ulsan, while human activities, such as printing/painting solvents and gasoline/diesel vehicular exhausts were dominant in Seoul. Therefore, different types of reduction strategy in the emission amount of VOCs should be applied according to a characteristic of the cities. Furthermore, three steps of the procedure applied in this study are suggested; (1) Measurement & analysis: level of VOCs and spatial-temporal variations are identified using the PAS and AAS, (2) Main sources: the most important thing is to look for the source origin using several advanced tools, such as diagnostic ratio, CBPF, CWT, and PMF, and (3) Secondary formation: the relationship between VOCs, SOA, and O3 should be revealed. In the future, the emission aspect, composition, reactivity, and concentration of precursors for the SOA and O3 formation, such as VOCs will be continuously changed. Therefore, integrated monitoring for air pollutants should be periodically conducted for the control strategy of VOCs, SOA, and O3, and this study will be helpful for the improvement of air quality. Also, this monitoring approach can be explored in the urbanized and industrialized cities in the world.

Measuring Public Life Through Digital Technologies: Investigating the Use of WiFi Sensing for Enhancing Public Space

Juhyeon Park Ulsan National Institute of Science and Technology 2022 국내박사