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Jihun Kang(Jihun Kang),Taeyun Kim(Taeyun Kim),Kyung-Do Han(Kyung-Do Han),Jin-Hyung Jung(Jin-Hyung Jung),Su-Min Jeong(Su-Min Jeong),Yo Hwan Yeo(Yo Hwan Yeo),Kyuwon Jung(Kyuwon Jung),Hyun Lee(Hyun Lee) 한국역학회 2023 Epidemiology and Health Vol.45 No.-
OBJECTIVES: We examined the associations of socioeconomic factors, health behaviors, and comorbidities with early-onset lung cancer. METHODS: The study included 6,794,287 individuals aged 20-39 years who participated in a Korean national health check-up program from 2009 to 2012. During the follow-up period, 4,684 participants developed lung cancer. Multivariable Cox regression analysis was used to estimate the independent associations of potential risk factors with incident lung cancer. RESULTS: Older age (multivariable hazard ratio [mHR], 1.13; 95% confidence interval [CI], 1.12 to 1.14) and female sex (mHR, 1.62; 95% CI, 1.49 to 1.75) were associated with increased lung cancer risk. Current smoking was also associated with elevated risk (<10 pack-years: mHR, 1.12; 95% CI, 1.01 to 1.24; ≥10 pack-years: mHR, 1.30; 95% CI, 1.18 to 1.45), but past smoking was not. Although mild alcohol consumption (<10 g/day) was associated with lower lung cancer risk (mHR, 0.92; 95% CI, 0.86 to 0.99), heavier alcohol consumption (≥10 g/day) was not. Higher income (highest vs. lowest quartile: mHR, 0.86; 95% CI, 0.78 to 0.94), physical activity for at least 1,500 metabolic equivalent of task-min/wk (vs. non-exercisers: mHR, 0.83; 95% CI, 0.69 to 0.99) and obesity (vs. normal weight: mHR, 0.89; 95% CI, 0.83 to 0.96) were associated with lower lung cancer risk, whereas metabolic syndrome was associated with increased risk (mHR, 1.13; 95% CI, 1.03 to 1.24). CONCLUSIONS: In young adults, age, female sex, smoking, and metabolic syndrome were risk factors for early-onset lung cancer, while high income, physical activity, and obesity displayed protective effects.
Han, Jihun,Kum, Dongsuk,Park, Youngjin IEEE 2017 IEEE Transactions on Vehicular Technology VT Vol.66 No.7
<P>Previously, an equivalent consumption minimization strategy (ECMS) was developed that provides near-optimal performance of hybrid vehicles based on an adaptation of equivalence factor from state of charge feedback. However, under real-world driving conditions with uncertainties, such as hilly roads, ECMS requires a predictive scheme utilizing future driving information in order to prevent a loss of optimality. In this paper, we synthesize predictive ECMS in a feedforward way to adjust the equivalence factor based on its theoretical connection with future driving statistics, in a systematic manner. First, a useful noncausal adaptation strategy is extracted from dynamic programming results. Then, the inverse problem is formulated and solved to derive an explicit representation of the constant optimal equivalence factor with justified assumptions. Finally, a causal, predictive adaptation strategy using this closed-form solution is synthesized to mimic the noncausal one, and its effectiveness is evaluated for fuel cell hybrid electric vehicles. Results show that if the predicted statistical information reflects well the future driving conditions, the proposed strategy accurately estimates the constant optimal equivalence factor, including the jump behavior, thereby yielding less than 1.5% loss of fuel optimality. Moreover, this approach is extendible to other configurations.</P>
도로의 경사도 정보를 이용한 하이브리드 연료 전지 자동차의 적응 룰 기반 전력 분배 전략
한지훈(Jihun Han),박영진(Youngjin Park),유성필(Seongpil Ryu) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
Fuel cell is being considered as an alternative power source, which can replace the conventional combustion engine. However it has some drawbacks such as low power density and inability of energy recovery. Therefore Fuel cell hybrid electric vehicle (FCHEV) technology has been widely studied in recent years in order to overcome these drawbacks of fuel cell vehicle (FCV). In a FCHEV, the fuel cell stack is assisted by one or more energy storage systems such as battery and super-capacitor. Power distribution between fuel cell and battery is most important for both improving the fuel economy and maintenance of battery’s state of charge (SoC) at reasonable level. In this paper, Adaptive rule-based controller for power distribution of FCHEV is proposed. Simple rule-based controller with constant thresholds can’t guarantee the performance for unexpected terrain (uphill, downhill) because the battery needs to provide relative large amount of power. Therefore proposed adaptive rule-based controller uses road slope information to vary threshold in order to distribute the propulsive power for battery. To verify the improvement in vehicle fuel economy and maintenance of SoC, optimal vehicle fuel economy and target trajectory of SoC by using dynamic programming is used.
회생 제동 에너지 회수율 최대화 및 차량 안전성 보장을 위한 하이브리드 연료 전지 자동차의 회생 제동 협조 제어
한지훈(Jihun Han),박영진(Youngjin Park),박윤식(Youn-sik Park),유성필(Seongpil Ryu),최서호(Seo-ho Choi) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
One of the most important control problems to improve fuel economy in fuel cell hybrid electric vehicle is cooperative regenerative braking control strategy because the electric motor can convert the kinetic or potential energy into electric energy that can be stored in super-capacitor and reused. In this study, an electric motor for regenerative braking is directly connected to the front drive axle only because front-wheel drive vehicle is common for passenger vehicle. Vehicle stability can be lost in case regenerative braking torque is applied only to front wheels for maximum braking energy recovery, i.e., FCHEV might get into an unstable motion called lock-up and understeer. Therefore, we propose systematic controller guaranteeing the vehicle stability while guaranteeing maximum regenerative braking energy recovery. Upper controller generates the desired yaw moment calculated by using LQR method for following the desired the yaw rate and side slip angle. And lower controller applies optimal regenerative braking torque and mechanical braking torque independently within equality constraints (the required total longitudinal force and yaw moment) and inequality constraints (friction circle) for optimal regenerative braking energy recovery. Carsim™ computer simulation is used to verify the effectiveness of the proposed controller.
하이브리드 연료 전지 자동차의 배터리 충전량 변화량을 고려한 가상 연비 평가 방법 분석
한지훈(Jihun Han),박영진(Youngjin Park),유성필(Seongpil Ryu) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
Virtual fuel economy evaluation method using equivalent energy concept is proposed to consider final SoC of battery in case that final SoC is different from initial SoC. In a FCHEV, the fuel cell stack is assisted by one or more energy storage systems such as battery and super-capacitor. Several supervisory control strategies to improve the fuel economy can’t satisfy the objective that each of the final SoC is perfectly same as initial SoC. Therefore it is necessary to consider final SoC in order to compare fuel economy fairly. In this paper, equivalent energy concept is used to convert the used battery energy into the hydrogen energy for specific driving mode. The equivalent energy relationship between battery energy and hydrogen energy is only obtained from iterative search in off-line as the ratio of required power to battery power is increased. By using this relationship, virtual fuel economy can be calculated by compensation of additional hydrogen energy. And SAE J1711 is used to compare the results of the proposed method.
리튬 이온 배터리 수명을 고려한 하이브리드 연료전지 자동차의 최적 에너지 관리 전략 분석
한지훈(Jihun Han),박영진(Youngjin Park),금동석(Dongsuk Kum),유성필(Seongpil Ryu),박윤식(Youn-sik Park) 한국자동차공학회 2013 한국자동차공학회 부문종합 학술대회 Vol.2013 No.5
This study analyzes an optimal energy management strategy for fuel cell hybrid electric vehicle (FCHEV) when lithium-ion battery lifetime is considered. First, a simplified FCHEV model is developed to describe power and energy flows throughout the powertrain and evaluate hydrogen consumption. Then, lifetime prediction model for lithium-ion is used to formulate an optimal control problem considering lithium-ion battery lifetime. In order to find the globally optimal energy management strategy of FCHEV over driving cycles, Dynamic Programming, a dynamic optimization method, is used, and their results are analyzed to find out how to operate the lithium-ion battery for improving the lifetime. The results show that the optimal energy management strategy considering lithium-ion battery lifetime tends to discharge the battery beforehand and also penalize the battery power at appropriate moderate magnitude. For this reason, the battery is operated in lower voltage and lower temperature. In conclusion, if the battery lifetime is more emphasized, the battery capacity fade is more reduced, on the other hand, hydrogen consumption is more increased.
Jihun Kim,Byongjun Lee,Sangwook Han,Jeong-Hoon Shin,Taekyun Kim,Sangtae Kim,Younghwan Moon IEEE 2013 IEEE transactions on smart grid Vol.4 No.1
<P>Recent technological achievement in areas of distributed computing, networking, high speed communications and digital control, as well as the availability of accurate GPS time source, are rapidly becoming the enabling factors for the development of a new generation of real time power grid monitoring tools. KDN (Korea electric power Date Network Co.) R&D department with KERI, Korea University and LSIS has embarked on long term research and development work in the field of wide area systems specifically applied to the power transmission grid in Korea. Primary focus will be on wide area measurement and monitoring, analysis, assessment technique and tools aimed at preventing the propagation of power grid instabilities. Of special interest are voltage stability and small signal stability. This project aligns with KEPCO (the Korea Electric Power Company). In this paper, case studies performed with the use of the developed system are presented.</P>