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Stacked Interleaved 방식의 50㎒ 스위칭 주파수의 벅 변환기
김영재(Youngjae Kim),남현석(Hyunseok Nam),안영국(Youngkook Ahn),노정진(Jeongjin Roh) 대한전자공학회 2009 電子工學會論文誌-SD (Semiconductor and devices) Vol.46 No.6
본 논문에서는 인덕터와 커패시터를 집적화한 DC-DC 벅 변환기를 설계하였다. 출력전압의 리플크기를 줄이기 위해 stacked interleaved 방식을 이용하였고 변환기의 제어부는 전압모드 방식의 제어방법을 사용하여 설계하였다. 설계한 DC-DC 벅 변환기는 표준 0.5㎛ CMOS 공정으로 제작 중이며 전체면적은 9㎟이다. 설계된 회로는 3V∼5V의 입력전압에서 동작하며 LC 필터의 크기를 줄이기 위해 50㎒의 주파수로 동작하였다. 최대 250㎃의 부하전류 구동이 가능하며 최대 71%의 전력변환 효율을 가졌다. In this paper, DC-DC buck converter with on-chip filter inductor and capacitor is presented. By operating at high switching frequency of 50㎒ with stacked interleaved topology, we reduced inductor and capacitor sizes compared to previously published DC-DC buck converters. The proposed circuit is designed in a standard 0.5㎛ CMOS process, and chip area is 9㎟. This circuit operated at the input voltage of 3∼5V range, the maximum load current of 250㎃, and the maximum efficiency of 71%.
PET/CT 영상의 부분체적효과와 장기의 움직임으로 인해 감소된 SUV의 보정을 위한 회복계수의 비교
김영재(Youngjae Kim),박훈희(Hoon-Hee Park),이주영(Joo-Young Lee),소영(Young So),이정우(Jeong-Woo Lee) 대한방사선과학회(구 대한방사선기술학회) 2022 방사선기술과학 Vol.45 No.3
In this study, a recovery coefficient (RC) calculation was conducted that can correct the underestimation of the standardized uptake value (SUV) due to the partial volume effect (PVE) through phantom measurements and formulas. The experiment was conducted using a dynamic phantom capable of implement cranio-caudal movement at a respiratory rate of 15 times per minute along with the measured phantom experiment of the stopped state, and the RC of the moving state is calculated and compared. Ingenuity TF (Philips Healthcare, Netherland) was used as a positron emission tomography/ computed tomography (PET/CT) device. PET-CT Phantom (Biodex Medical System, USA) was used as a phantom for measurement. A phantom image in a stationary state was acquired, and a moving phantom image was acquired using the AZ-733V Respiratory Phantom (Anzai Medical Co, Japan) capable of breathing movement in the cranio-caudal direction under the same acquisition parameters. For RC calculation, the sphere maximum radioactivity concentration and the background mean radioactivity concentration of the acquired images were measured, and the initially determined sphere and background radioactivity concentrations were calculated. The calculated RC was 0.08 to 0.72. The size of sphere smaller, it was confirmed that the RC reduced. And the RC in the moving state reduced than in the stationary state. As a result of this study, the change of the RC was confirmed according to the size of spheres and the phantom moving. Using the RC derived by implement movement of breathing with the respiratory phantom, it is possible to considering correction of underestimated SUV by the partial volume effect of PET images and the patient movements.
여가 체험척도 개발 및 타당화 검증 : Pine & Gilmore의 체험중심 이론을 기반으로
김영재(Kim, YoungJae) 한국여가문화학회 2021 여가학연구 Vol.19 No.3
본 연구는 여가활동 참여에 따른 긍정적인 심리적 효과성을 규명하기 위해 여가체험 측정 요인과 문항을 탐색하여 측정 도구를 제시하는 데 목적이 있다. 본 연구 참여자 모집은 2번에 걸쳐 진행되었다. 연구1에서는 문항검증과 요인도출을 위해 937명이 선정되었고, 연구2에서는 요인의 모형검증과 타당화 검증을 위해 총 405명이 선정되었다. 본 연구의 통계처리는 신뢰도 검증으로 문항특성을 위해 문항 평균과 표준편차, 문항 범위를 구하였고, 신뢰도 검사, 탐색적 요인분석과 확인적 요인분석을 하였다. 본 연구 결과 여가체험과 관련된 측정 요인과 문항에 대한 전문가 자문, 탐색적 요인분석을 통해 최종 4개 요인(재미, 예술, 정보, 새로운 경험) 16개 문항이 도출되었다. 또한, 성별에 따라 다집단 확인적 요인분석을 한 결과 척도의 유효성이 검증되었다. 본 연구에서 제시한 여가체험척도를 다른 학문적 영역과 공동으로 연구하기 위해서는 앞으로 좀 더 다양한 대상과 다른 사회 심리적 측정 요인들을 사용한 관계성 연구를 진행해야 한다. 또한, 다양한 사회 및 문화적 상황에서 결과 비교분석을 통한 연구가 진행되어야 할 것이다. The purpose of this study is to examine leisure experience measurement factors and questions and suggest it to verify the psychological effectiveness on leisure activity participants by participating in the activities. The research participants were recruited twice. In research 1, 937 participants were selected to verify the questions and derive the factors, and in research 2, 405 participants were selected for model verification and validation of the factors. For the statistical process of this study, reliability verification was used to find the question item average and standard deviation, and the question item range, and reliability test, exploratory factor analysis, and confirmatory factor analysis were conducted. As a result, through the expert s advice and exploratory factor analysis about the factors and question items of the measurement tool related to the leisure experience, final 4 factors (fun, art, information, new experience) and 16 question items were deduced. In addition, the effectiveness of the scale was verified by conducting multiple group confirmatory factor analysis. In order to carry out research about the leisure experience scale suggested in this study jointly with other academic fields, relationship test should be conducted with a wider range of targets and psychosocial measurement factors and a research should be conducted through findings from various social and cultural situations and also through comparative analysis.
1.6L GDI 차량에서 EURO 6 입자상 물질 규제를 만족하기 위한 PN 저감에 관한 연구
김영재(Youngjae Kim),전상열(Sangyoul Jun),김용하(Yongha Kim),류승현(Seunghyun Rew),이동현(DongHyeon Lee),최관희(Kwanhee Choi),박심수(Simsoo Park) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
Recently, the alternative to reduce CO₂ and improve fuel efficiency owing to rising oil price and green house gas emission regulation is GDI vehicle that is expected to be a dominant technology for quite a long time. However, unlike PFI engine GDI engine that sprays fuel inside of cylinder emits soot like diesel engine as all you know. We called it is PM. (Particular matter) PM of less than 2.5μm which is very, very tiny material leads to fatal consequences in human body by accumulating at lungs without filtering through respiratory system. Therefore, particle emission will be added for European automobile emission regulation in 2014. The disputed result is currently 4.5mg/km for particle mass and 6<SUP>*</SUP>10<SUP>11</SUP>#/km for particle number in case of EURO Ⅵ diesel vehicle. In case of EURO Ⅵ gasoline vehicle, particle mass is 4.5mg/km and particle number is under the discussion stage. In this study, present level of 1.6L GDI vehicle is measured and is figured out correlation between PM and PN through engine test. A cause of PM and PN formation is divided into several types of reason; however, this paper describes the optimization of engine control parameter without hardware change like combustion chamber, cylinder shape, injector type and injection target position. Same amount of CO₂, reduction of existing exhaust gas and 87% PN in contradistinction to the base in NEDC mode test is attained. As a result, 60% level of provisional PN limit is accomplished and this result will contribute to vehicle cost reduction by decreasing after-treatment cost. Based on this study, if it is expanded to different displacement vehicles, a standard of vehicle development to satisfy PN limit will be prepared.