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저 조도에서 동작하는 전류거울 회로를 사용한 CMOS 이미지 센서 픽셀
남주현(Juhyun Nam),조경록(Kyoungrok Cho) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.6
Since the conventional pixel has a deficit that it could not sense a thing under low light level environment, the novel architecture that CIS which includes current mirror circuit at photo-diode node is proposed. The amount of current flow by the photo-charge is amplified by utilizing the current mirror in order to improve output performance at the same light level, when comparing with the conventional ones. The proposed pixel in the paper is simulated with Hynix standard 0.18 um CMOS process. Under the light intensity of 0.01 lx, which causes photocurrent of 10 pA, the proposed architecture denotes slope of 200 mV/ms at output.
나사산의 형상에 따른 Self-Tapping Screw의 체결 거동 분석
남주현(Juhyun Nam),오제훈(Je Hoon Oh) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
The metal tapping screws are mainly used to fasten polymer materials. Since the polymer clamped parts are weaker than the metal screw, the joint performance is mainly affected by the material properties and shapes of clamped part. However, it is not simple to change the material. Therefore, research have been conducted to improve the performance of joints by varying the thread shape. Though, it is not efficient to manufacture the designed screw to evaluate the joint performance because of the cost. In this study, we suggest an efficient way to comparing the fastening performance with respect to different materials and thread shapes via finite element analysis (FEA). The experiments were also conducted to validate the FEA. The calculated stripping torque via FEA shows only ±5% error compared to the experimental results. Additionally, we compared the fastening behavior and the joint performance with respect to the five threads of different shapes.
압력 제어 방식 CVT의 모델 기준 변속비 제어 알고리즘
남주현(Juhyun Nam),류완식(Wansik Ryu),김현석(Hyunsuk Kim),최병대(Byungdae Choi),이용준(Yongjun Lee),김현수(Hyunsoo Kim) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, model based control algorithms of the pressure regulating type CVT ratio control system are developed. It is found from the experiments that the linear controller can be applied in pressure control type CVT with satisfactory tracking performance and robustness while nonlinear control algorithm is required for the flow control type CVT. In addition, model based ratio control algorithms are suggested based on the steady state characteristics of the CVT ratio control system. The experiments show reduced under/overshoot shift characteristics. It is also found that the primary pressure control can be achieved by the model based control to prevent the belt-pulley slip. However, the increased primary pressure causes slower downshift response, which requires compromise between the safety and the performance.
남주현(Juhyun Nam),류완식(Wansik Ryu),김현석(Hyunsuk Kim),김현수(Hyunsoo Kim) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, a model based control algorithm for pressure control type CVT has been developed. Model based controller was designed based on Kpsi map and steady state primary pressure model for a ratio control valve. It was found from the experiments thai the model based controller has similar tracking performance compared with the PID controller. However, model based controller showed superior robustness to the PID controller especially for the overdrive range. It is expected that the model based controller can be used to prevent the belt slippage and improve the shift speed.<br/>
류완식(Wansik Ryu),남주현(Juhyun Nam),이희라(Heera Lee),김현석(Hyunsuk Kim),이진희(Jinhee Lee),이용준(Yongjun Lee),김현수(Hyunsoo Kim) 한국자동차공학회 2002 한국자동차공학회 Symposium Vol.2002 No.11
CVT ratio control can be achieved by either flow control or pressure control. Since the pressure control method is able to control the pulley thrust. it has many advantages such as keeping the belt from slippage. In developing the ratio control valve. steady state and dynamic characteristics of metal belt CVT should be considered. In this paper. 2 types of ratio control valves are developed: type(l) with line pressure area on the ratio control valve spool and type(lI) without line pressure area. In addition. Kpsi line concept is introduced. which can be used to predict shift performance by the pressure margin to the boundary point. Simulation results show that the type(I) gives faster shifting response in downshift compared to that of the type(II), which is due to the residual pressure in the primary actuator. It is found from the simulation and experimental results that the ratio control valve(l) and (II) have advantages and disadvantages in shift speed while satisfying the design specification for the steady state and the dynamic characteristics.