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ManJae Kwon,Seung Hyun Kang,Yun Seong Hwang,Byoung Kuk Lee 전력전자학회 2023 ICPE(ISPE)논문집 Vol.2023 No.-
This paper proposes a variable DC-link voltage control method (VDC) for domestic induction cooktop using PFC rectifier. Conventional frequency control method (FCM) has a disadvantage that switching loss (Psw) of resonant inverter increases as a power of system decreases. When the proposed (VDC) is applied, the power level can be controlled without varying switching frequency (fsw), resulting higher efficiency of power conversion system (PCS) up to 2%. Through mathematical analysis results, losses of PCS according to control method are compared to verify the validity of proposed VDC. Finally, the feasibility of VDC proposed in this paper is verified by experimental results.
Mental Health Problems During COVID-19 and Attitudes Toward Digital Therapeutics
Manjae Kwon,Young-Chul Jung,Deokjong Lee,Jaeun Ahn 대한신경정신의학회 2023 PSYCHIATRY INVESTIGATION Vol.20 No.1
Objective We aimed to elucidate public mental health problems and associated factors during the coronavirus disease-2019 (COVID-19). Furthermore, we evaluated people’s attitudes toward digital therapeutics during the pandemic. Methods Data was collected online from participants, aged between 20–50 without any history of mental illness, from June 1st to June 30th 2021. The survey consisted of questions regarding demographics, changes during pandemic and attitude towards digital therapeutics, and mental health measures. Results Among the total of 445 participants, 49.2% reported significant level of stress and 13.5% and 7.0% met the screening criteria for major depressive disorder and generalized anxiety disorder, respectively. Significant predictive factors for mental health problems were-younger age group, female sex, currently being treated for medical or surgical disease, change in the amount of time spent on mobile device or computer after pandemic, change in household income, and change in work environment due to pandemic. Furthermore, 35.1% of participants, considered psychiatric consultation, at least slightly, but were hesitant to receive it due to the fear of contacting COVID-19 at the clinics. Instead, 54.4% of them preferred using digital therapeutics as an alternative to visiting offline clinics. Conclusion We demonstrated that COVID-19 increased mental health problems along with access problems and identified their predictive factors. Digital therapeutics emerged as a viable solution to mental health problems and it was well-received by those in need of psychiatric consultation. Therefore, development and implementation of digital therapeutics should be considered to improve the mental health of people.
CR X-선 영상기법을 이용한 DPF 파손여부에 대한 비파괴 측정 타당성 연구
권만재(Manjae Kwon),박기영(Giyoung Park),김성준(Sungjoon Kim),한태호(Taeho Han),김정민(Jungmin Kim),이성욱(Seangwock Lee) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.10
Diesel vehicles are equipped with after-treatment devices, such as DPF. Meanwhile, DPF is damaged by a combination of regenerative processes and unclear factors. If the DPF substrate is damaged, the filtration performance will deteriorate, thereby resulting in excessive levels of fine dust being emitted while driving. In this study, CR X-ray techniques were used in order to determine whether a DPF was damaged without prior removal. In order to verify the technological feasibility, an X-ray imaging of the DPF removed from the driving vehicle was conducted by using an X-ray generator, as well as an IP reader and a CR reader. Optimal irradiation conditions were established for each DPF size. Verification of images acquired under optimal irradiation conditions confirmed the possibility of diagnosis for damages, such as crack, melting, and hollow damage.
CR X-선 영상기법을 이용한 DPF 파손여부에 대한 비파괴 측정 타당성 연구
권만재(Manjae Kwon),박기영(Giyoung Park),김성준(Sungjoon Kim),한태호(Taeho Han),김정민(Jungmin Kim),이성욱(Seangwock Lee) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.9
Diesel vehicles are equipped with after-treatment devices, such as DPF. Meanwhile, DPF is damaged by a combination of regenerative processes and unclear factors. If the DPF substrate is damaged, the filtration performance will deteriorate, thereby resulting in excessive levels of fine dust being emitted while driving. In this study, CR X-ray techniques were used in order to determine whether a DPF was damaged without prior removal. In order to verify the technological feasibility, an X-ray imaging of the DPF removed from the driving vehicle was conducted by using an X-ray generator, as well as an IP reader and a CR reader. Optimal irradiation conditions were established for each DPF size. Verification of images acquired under optimal irradiation conditions confirmed the possibility of diagnosis for damages, such as crack, melting, and hollow damage.
박기영(Giyoung Park),권만재(Manjae Kwon),정주영(Juyeong Jung),송호영(Hoyoung Song),김기호(Kiho Kim),이성욱(Seangwock Lee) 한국자동차공학회 2019 한국 자동차공학회논문집 Vol.27 No.5
In this study, 6-litre displacement, a commercial vehicle engine that meets the EURO-5 regulation, was used to evaluate the durability and performance deterioration of the SCR system mounted on a heavy-duty diesel vehicle. Meanwhile, ND-13 and ETC modes were used for the emission test. The characteristics of emissions by SCR catalyst deterioration were investigated by using mileage vehicles of 0 km, 120,000 km, and 360,000 km. The energy dispersive X-ray spectroscopy(EDS) of the CT scan to the catalyst carrier and EDS for PM filters were carried out in order to investigate the status of the catalyst at each mileage. As a result, it was found that NOX emissions, NH3 slip, and PM due to unreacted ammonia and urea increased as the mileage of the catalyst increased.
전상우,권만재,안호순,Jeon, Sangwoo,Kwon, Manjae,An, Hosoon 한국자동차안전학회 2021 자동차안전학회지 Vol.13 No.4
This paper is the result of a research on hybrid tuning technology developed to improve the actual fuel efficiency and reduce emissions of in-use light-duty diesel trucks. In this study, a hybrid powertrain was constructed by inserting an electric motor between the diesel engine and manual transmission of an internal combustion engine vehicle and installing a battery. To verify the safety, a test was conducted based on the Korean tuning regulations. In particular, since there has been no case of tuning an internal combustion engine vehicle into a hybrid vehicle in Korea, it was necessary to carry out all procedures to receive tuning approval. The approval process consists of a technical review, safety verification test, and application for tuning approval. As a result, the test vehicle was approved for tuning because both the technical review and vehicle test results were suitable. Therefore, this study confirmed the safety of diesel hybrid tuning technology, and laid the foundation for the research and development of technologies to tune into an eco-friendly vehicle as well as the activation of related industries.
철산화 박테리아의 생장 및 활성 억제를 통한 산성광산배수의 발생 저감
박영태(Park, Youngtae),양중석(Yang, Jungseok),권만재(Kwon, Manjae),윤현식(Yun, Hyunshik),지민규(Ji, Minkyu),지은도(Jee, Eundo),이우람(Lee, Wooram),지원현(Ji, Wonhyun),권현호(Kwon, Hyunho),최재영(Choi, Jaeyoung) 한국지반환경공학회 2012 한국지반환경공학회논문집 Vol.13 No.4
폐광산의 산성배수(AMD)는 황철석을 비롯한 다른 금속 황화물의 산화를 통해 발생한 폐광산의 산성배수는 환경오염의 원인 중 하나이다. 본 연구에서는 이러한 폐광산의 산성배수가 생성되는 과정에서 산화미생물의 관여 정도를 알아보고, 이를 억제할 수 있는 방법에 대해여 살펴보았다. 산성배수 발생에 영향을 미치는 산화미생물로 Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans을 선정하였으며, 이 산화미생물의 활성 및 생장 속도를 측정하였으며, 이산화염소(ClO₂), NaCl, 그리고 계면활성제(ASOR-770) 를 산발생 억제제로 이용하여 실험을 진행하였다. 실험 결과 10ppm 이산화염소가 가장 효과적인 억제제였으며, 산화미생물의 활성도와 생장도를 20% 까지 감소시켜주었다. Acid mine drainage (AMD) is one of the most severe environmental problem that results from the oxidation of pyrite (FeS₂) and various other metal sulfides. In this study, the influence of microorganism was tested on the process where AMD was released and the method to inhibit AMD generated by microorganisms at abandoned mine area. The activity and growth rate of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans, common microorganisms affecting AMD occurrence, were measured. Chlorine dioxide (ClO₂), NaCl, or surfactant (ASOR-770) was used as an inhibitor for working on activity and growth of microorganism. Among the three inhibitors, 10ppm of chlorine dioxide was the most effective inhibitor for AMD control due to the reduced the activity and growth of microorganisms by 20%.