• 한국정밀공학회지
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• 제25권9호
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• pp.116-125
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• 2008

Inkjet printing technology with a drop-on-demand (DOD) inkget head technology has been recognized as one of versatile and low cost manufacturing tools in the electronics industry. Concerned with control of driving signal, however, general strategy to optimize jetting stability has not been understood well, because of the inherent complex multi-physics nature in inkjet phenomena. Motivated by this, present study investigates the effect of driving waveforms of piezoelectric head on jetting characteristics of DOD inkjet system focused on jetting stability with phase matching of pressure waves in the print head. The results show that velocities and volumes of the ink jetted droplets were linear relations with the driving signal's maximum voltage, while periodic behaviors are observed with the driving signal's pulse widths.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1444-1449
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• 2007

Inkjet printing technology with a drop-on-demand (DOD) inkjet head technology has been recognized as one of versatile and low cost manufacturing tools in the electronics industry. Concerned with control of driving signal, however, general strategy to optimize jetting stability has not been understood well, because of the inherent complex multi-physics nature in inkjet phenomena. Motivated by this, present study investigates the effect of driving waveforms of piezoelectric head on jetting characteristics of DOD inkjet system focused on jetting stability with phase matching of pressure waves in the print head. The results show that velocities and volumes of the ink jetted droplets were linear relations with the driving signal's maximum voltage, while periodic behaviors are observed with the driving signal's pulse widths.

• 동력기계공학회지
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• 제1권1호
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• pp.106-123
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• 1997

In this study, vehicle directional stability is investigated for limit driving for crash avoidance maneuver using a full vehicle dynamic model. The model was analytically validated using typical step steering and lane change simulation. Limit driving condition for the vehicle model was quoted from research results of references. It was demonstrated that instable vehicle motion was caused by not only road conditions but also driving conditions. Also, the simulation showed that braking combined with steering caused very hazardous situation in crash avoidance maneuver. Finally, phase plane plot approach was used to evaluate the dynamic instability.

• 한국CDE학회논문집
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• 제3권1호
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• pp.40-47
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• 1998

Recently, the various driving simulator have been used widely to analyze the handling performance of vehicle and to verify the motion control algorithm of vehicle. In this study, a virtual driving simulator based on the 20-DOF vehicle model is realized to estimate the handling performance and stability of a 4WS (Four-wheel-steering) and/or 4n(Four-wheel-driving) vehicle. Especially the DC motor controlled 4WS actuator is modelled in order to reflect the effect of the responsiveness of actuator on the handling performance and stability. And the realized simulator can be applied to develope a real time simulation system for designing and testing the real vehicles.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.1005-1009
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• 2001

The application of the ultrasonic nozzle has been extended because it is possible atomization of liquid material. In this study, the driving characteristics of the ultrasonic nozzle on the driving circuit were investigated. And the characteristics of the ceramic oscillator were investigated for the temperature stability. The ceramic oscillator were made the Pb[(Sb$\sub$1/2/,Nb$\sub$1/2/)$\sub$0.035/-(Mn$\sub$1/3/Nb$\sub$2/3/)$\sub$0.065/- (Zr$\sub$x/Ti$\sub$l-x/)$\sub$0.9/]O$_3$with mole ratio of Zr/Ti. The ceramis oscillator were need the curie temperature of the over 300[$^{\circ}C$] for the temperature stability. When the Zr/Ti ratio was 49/51, it's curie temperature is 322[$^{\circ}C$] and the electromechanical coupling factor(k$\sub$p/) and mechanical quality factor(Q$\sub$m/) showed the values of 0.555, 1,214, respectively The resonance frequency of ceramic oscillator were from 40KHz to 45KHz. So that, the driving circuit were made a possibility that the frequency are variable. The driving current of ultrasonic nozzle showed the value of maximum 80[mA]. Also, The surface temperature of ceramic oscillator showed 80[$^{\circ}C$] at driving time 10[min]. We knew that the ultrasonic nozzle had stabile driving above 10[min.].

• 감성과학
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• 제22권3호
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• pp.47-54
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• 2019

본 연구는 운전 중 외부 소음으로 유발된 스트레스를 줄이기 위한 방법으로 심박변화율의 상관관계 분석의 선행연구와 음원의 주파수에서 운전자로 하여금 안정상태를 유발하는 음악과 소음 발생 시 심전도의 변화 가 있는 지의 여부를 규명하기 위한 목적이다. 매년 자동차의 증가로 인하여 운전자 및 동승자가 외부 소음으로부터 스트레스가 증가하는 추세이다. 자동차 운전 시 외부 소음에 의한 스트레스는 불안, 면역약화, 우울, 심장 질환 등 여러 가지 질병을 일으키고 있다. 따라서 외부 소음으로부터 스트레스를 줄이기 위한 자동차 시뮬레이터를 실시하여 여러 가지 청각 자극을 주어 운전자가 반응하는 연구를 진행하였다. RM-ANOVA (Repeated Measures-ANOVA) 통계분석 결과, 집단별 유의차가 인정되었다(ρ<0.05). 사후 검정을 통해 어떤 요인 간의 차이가 발생하는지를 알아보았다. 사후검정 결과는 요인1(안정)과 요인2(시뮬레이션운전), 요인1(안정)과 요인3(운전+경찰사이렌), 요인1(안정)과 요인4(운전+경찰사이렌+음악)에서 유의한 차이를 발견할 수 있었다. 또한, 교감신경계 활성도가 가장 높은 집단은 운전+경찰사이렌+음악을 실시한 요인 4이며, 다음으로 운전+경찰사이렌인 요인 3이며, 다음으로 운전을 실시한 요인 2, 마지막으로 안정기 순으로 나타났다. 결론적으로 운전 중 경찰 사이렌 소리를 들려주어도 심전도의 변화는 유의차가 인정되지 않았다. 또한, 사이렌 소리에 안정된 주파수의 음악을 들려주어도 심전도의 변화에 차이가 발생하지 않았다(ρ<0.01). 향후 연구에서는 운전 중 심전도의 안정을 찾을 수 있는 여러 가지 음악을 들려주어서 심전도가 안정화되는 음악을 찾는 연구방법이 선행되어야 할 것이다.

• 자동차안전학회지
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• 제5권1호
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• pp.62-68
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• 2013

This paper describes development of 4 Wheel Drive (4WD) Electric Vehicle (EV) based driving control algorithm for severe driving situation such as icy road or disturbance. The proposed control algorithm consists three parts : a supervisory controller, an upper-level controller and optimal torque vectoring controller. The supervisory controller determines desired dynamics with cornering stiffness estimator using recursive least square. The upper-level controller determines longitudinal force and yaw moment using sliding mode control. The yaw moment, particularly, is calculated by integration of a side-slip angle and yaw rate for the performance and robustness benefits. The optimal torque vectoring controller determines the optimal torques each wheel using control allocation method. The numerical simulation studies have been conducted to evaluated the proposed driving control algorithm. It has been shown from simulation studies that vehicle maneuverability and lateral stability performance can be significantly improved by the proposed driving controller in severe driving situations.

• 대한기계학회논문집A
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• 제35권8호
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• pp.905-912
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• 2011

견마로봇이 야지 노면에서 주행할 때 로봇에 설치되어 있는 각종 장비의 보호를 위하여 주행 안정성을 높이는 것이 중요하다. 견마로봇의 주행 안정성을 평가하는 데에 있어서 차체의 수직 가속도, 롤 각가속도, 피치 각가속도의 영향이 지배적이다. 가속도가 발생한다는 의미는 차체에 그만큼의 힘이 가해진다는 것을 의미한다. 따라서 차체에 작용하는 힘의 크기를 조절함으로써 차량의 안정성을 향상시킬 수 있다. 차량의 안정성을 높이기 위한 하나의 방법으로 MR 댐퍼와 스카이 훅 제어기법을 적용할 수 있다. 본 연구에서는 $6{\times}6$ 견마로봇에 대하여 MR 댐퍼에 스카이 훅 제어기법을 적용하였으며, 수직 가속도 및 롤, 피치 각가속도를 줄이는 방향으로 제어하여 차량의 주행 안정성을 향상시켰다.

• 대한임베디드공학회논문지
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• 제17권5호
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• pp.257-263
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• 2022

Active stabilizers use signals such as steering angle, yaw rate, and lateral acceleration to vary the roll stiffness of the front and rear suspension depending on the vehicle's driving conditions, and are attracting attention as RSC (Roll Stability Control) system that suppresses roll when turning and improves ride comfort when going straight. Various studies have been conducted in relation to active stabilizer bars and RSC systems. However, accurate modeling of passive stabilizer model and active stabilizer model and vehicle dynamics analysis result verification are insufficient, and performance result analysis related to vehicle roll angle estimation and electric motor control is insufficient. Therefore, in this study, an accurate vehicle dynamics model was constructed by measuring the passive/active stabilizer bar model and component parameters. Based on this, the analysis result with high reliability was derived by comparing the roll angle estimation algorithm based on the lateral acceleration and suspension of the vehicle with the actual vehicle driving test result. In addition, it was intended to accurately analyze the motor torque characteristics and roll reduction effects of the electric motor-driven RSC system.

• 전기학회논문지
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• 제58권6호
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• pp.1157-1165
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• 2009

In AC-PDP, it is necessary to achieve high luminance efficiency, high luminance and high definition by adopting technologies such as high xenon concentration, MgO doping, and long gap. However, it is very difficult to apply above technologies because they make the driving voltage margin reduced. Especially, high Xe concentration technology for high efficacy makes not only the driving voltage margin reduced but also the stability of reset discharge decreased at low temperature. In this paper, we studied temperature and voltage dependent stability of reset discharge and present the experimental results of the discharge characteristics at low temperature. In addition, we suggested the mechanism of bright noise and black noise at low temperature. Finally, we proposed double reset waveform to improve the bright noise and descending scan time method to improve the black noise.