http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
서정원(Jungwon Seo),노승진(Seungjin Noh),최영수(Youngsoo Choi) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This paper aims to explain the effect of steering performance on vehicle pull. It is well know that vehicle pull characteristics is affected by road slope, tire PRAT/conicity, cross camber, cross caster and delta front corner weight.. This study focuses on the steering performance by influencing pulling performance since the steering characteristics can be tuned during vehicle development. In order to define steering characteristics on vehicle pull, several cars are used for objective measurement. The on-center handling test was conducted and good correlation was obtained between methodology of pulling sensitivity and actual test result. With the study of effect of steering performance on vehicle pull, it is results in required STG balancing for maximizing steering performance and minimizing vehicle pull.
심장과 뇌 발달에서 GATA6 유전자 발현 감소가 미치는 영향
서정원(Jungwon Seo) 한국생명과학회 2015 생명과학회지 Vol.25 No.11
GATA binding protein 6 (GATA6)는 초기 배반포 단계에서 발현이 시작되어, 심장, 췌장, 장 등의 분화와 발달에 중요한 유전자 발현을 조절하는 전사인자이다. 본 연구에서는 GATA6의 세포 분화와 개체 발달 과정에서의 역할을 마우스 배아줄기세포와 zebrafish를 이용하여 확인하였다. 먼저, 마우스 배아줄기세포를 박동하는 pacemaker 심근세포로 분화 유도하였다. RT-PCR을 실시하여 심근세포 분화 과정에서 GATA6 유전자 발현 변화를 확인한 결과, Gata6의 발현이 분화 4일째부터 증가함을 확인하였다. GATA6 유전자의 발현 증가는 심장 발달에 필수적인 전사인자인 NK2 homeobox 5 (Nkx2.5)나 myocyte enhancer factor 2C (MEF2C)의 발현 증가에 앞서 나타났다. GATA6 유전자가 발달 과정에 미치는 영향을 확인하기 위하여 GATA6의 morpholino를 zebrafish 배아에 microinjection하여 발생 변화를 관찰하였다. GATA6의 발현을 knockdown시킨 zebrafish의 심장은 크기가 감소하였고, 심박동률 또한 감소하였다. 한편, 뇌에서는 전체적인 뇌 퇴행이 관찰되었는데, acridine orange로 염색한 결과, 뇌 전체에서의 세포사멸의 증가를 나타내었다. 흥미롭게도, GATA6의 발현 감소는 초기 bud 단계에서는 오히려 세포사멸을 감소시켰다. 본 연구는 심장과 뇌 발달에서의 GATA6 유전자의 중요성을 시사한다. GATA binding protein 6 (GATA6) is a transcription factor that is expressed in the early blastocyst stage and controls the expression of important genes in the differentiation and development of the heart, pancreas, and intestine. This study confirmed the role of GATA6 in cell differentiation and organ development using mouse embryonic stem cells and zebrafish, respectively. First, the mouse embryonic stem cells were differentiated into pacemaker cardiomyocytes. An RT-PCR analysis revealed that the expression of the GATA6 gene was greatly increased from day 4 of differentiation. The expression of GATA6 was upregulated prior to increased expression of NK2 homeobox 5 (Nkx2.5) and myocyte enhancer factor 2C (MEF2C), which are critical transcription factors involved in regulating heart formation. To examine the role of GATA6 in development, GATA6 morpholino was microinjected into zebrafish embryos. Knockdown of GATA6 expression significantly decreased the heart size and heart rate in the zebrafish compared to a control. In addition, the brains were degenerated in the GATA6 morpholino-injected zebrafish. Acridine orange staining showed that knockdown of GATA6 expression increased apoptotic cells in the brain. Interestingly, knockdown of GATA6 expression decreased apoptotic cells in the early bud stage. This study points to the importance of the GATA6 gene in heart and brain development.
소형차량에서 LCA Bush Stiffness 변화에 따른 차량의 운동성능 및 승차감 고찰
서정원(Jungwon Seo),전영운(Youngwoon Chun),이철훈(Chulhoon Lee),원영섭(Youngsub Won) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4
This paper aims to explain both ride trend and the effect of elastomeric bushing stiffness of lower control ann to be applied in a small car. Even though many car companies apply hydraulic lower control arm bush as an enabler for better ride comfort over the mid size car., most of small car is fitted with elastomertic bush of lower control arm. It is very difficult to fulfill the good ride and handling performance with elastomeric lower control arm bushing of a small car. So it is necessary to understand relationship between vehicle performance and bush stiffness change of lower control arm. All the results are shown in this paper not only by subjective evaluation but also objective measurement. Also this paper explains which is proper rear bush stiffness of lower control with minimize degradation on Vehicle Dynamics area in the small car. Vehicle performances are also affected both suspension type and characteristics of many suspension components. But those factors are not considered in the paper in order to focus on rear bush stiffness of lower control arm.
토션빔 현가 장치를 가진 차량의 현가계 특성 변화에 따른 Floor SRS 개선 방안 연구
서정원(Jungwon Seo),김상진(Sangjin Kim),노승진(Seungjin Noh),황준효(Junhwyo Hwang),박수용(Sooyong Park) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
This paper aims to explain the effect of suspension characteristics for improving the Floor Smooth Road Shake (SRS) performance which is one of the most important ride metrics in modern vehicles. The SRS Metric is formed by two driver interfaces: steering hands lateral, SHY, and Floor Pan Vibrations caused by tire imbalance forces. Even though the floor pan longitudinal and vertical vibrations are much smaller than the steering wheel lateral vibration, this study focuses on the floor SRS since drivers get affected by floor SRS. We performed the fundamental dynamics simulation of SRS by using ADAMS solver based on Motionview with in-house templates and objective measurement. Also this paper explains the dominant factor for enhancing the floor smooth road shake performance and design recommendations.
서정원(Jungwon Seo),최영수(Youngsoo Choi),신상하(Sangha Shin) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5
This paper aims to explain the most influencing control factor on vehicle pull with Monte Carlo Simulation. It is well known that vehicle pull characteristics is affected by Spindle Length, KPI, Steer Arm Length, STG, Tire SLR, road slope, tire PRAT, cross camber, cross caster and delta front corner weight.. This study focuses on robust control factor to the noise factor. Here, cross camber, cross caster, delta weight, road slope is defined as a noise factor which is mostly affected by production tolerance and road environmental. The Monte Carlo Simulation was conducted and good simulation has been obtained. With the study on the Vehicle Pull Improvement using Monte Carlo Simulation, it shows that Steering Torque Gradient is the most influencing factor which is required balancing for maximizing steering performance and minimizing vehicle pull and Steer Arm Length, Tire PRAT Sensitivity is second and third influencing factor.
Local Body Stiffness 변화에 따른 조향특성 연구
서정원(Jungwon Seo),노승진(Seungjin Noh),이준희(Junhee Lee),정현욱(Hyunwook Jeong),신상하(Sangha Shin),오정용(Jungyoung Oh) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
This paper aims to explain the steering characteristics by changing local body stiffness. It is well know that body characteristics affect the quality of the dynamics of vehicles, such as handling performance, ride comfort and noise and vibration. This study focuses on the steering performance by changing local body stiffness since the steering characteristics are much affected by local body stiffness. In order to define local body stiffness effect, strut bar and reinforce shock tower are used for objective and subjective evaluation. The on-center handling test was conducted and good correlation was obtained between objective on center handling and subjective evaluation. With the study of on center handling test for local body stiffness, this paper explains the local body stiffness factor for enhancing steering performance.
서정원(Jungwon Seo),석창성(Changsung Suk),김영진(Yongjin Kim) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.8
Railway wheel and axle are the most critical components in railway system. A wheel and axle failure can cause a derailment with its attendant loss of life and property. The service conditions of railway vehicles have become severe in recent years due to a general increase in operating speeds. Therefore, more precise evaluation of wheelset strength and safety has been desired. Damages of railway wheel are a spalling by wheel/rail contact and thermal crack by braking heat etc. One of the main source of damage is a residual stress. therefore it is important to evaluate exactly. A Residual stress of wheel is formed at the process of heat treatment when manufacturing. it is changed by contact stress developed by wheel/rail contact and thermal stress from heat induced in braking. The objective of this paper is to estimate the variation and magnitude of the residual stress of railway wheel. Consequently, residual stress after heat treatment process was about -370㎫, changed to tensile stress according to braking conditions
맥퍼슨 현가 장치를 가진 차량의 Lower Control Arm Bush 특성과 Steering Wheel PMI 변화에 따른 SRS 개선 연구
서정원(Jungwon Seo),이준희(Junhee Lee),이철훈(Chulhoon Lee),김인동(Indong Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
This paper aims to explain the effect of elastomeric rear bushing characteristics of lower control arm and steering wheel PMI for improving the Smooth Road Shake (SRS) performance which is one of the most important ride metrics in modern vehicles. Even though the SRS Metric is formed by two driver interfaces: steering hands lateral, SHY, and Floor Pan vibrations caused by tire imbalance forces, this study focuses on the steering wheel lateral vibration since the floor pan longitudinal and vertical vibrations are much smaller than the steering wheel lateral vibration. The results are shown in this paper by objective measurement. Also this paper explains how much LCA rear bush characteristics of lower control arm and steering wheel PMI influences minimizing smooth road shake of steering wheel.
소형차량에서 On Center Handling 시험에 따른 조향특성 고찰
서정원(Jungwon Seo),신상하(Sangha Shin),김상진(Sangjin Kim),최영수(Youngsoo Choi) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
This paper aims to explain the steering characteristics by on-center handling test on a small car. The on-center handling test is the one of the most popular objective test method for expressing steering characteristics. This is not a perfect test, but extremely useful. The on-center handling test has been developed as a means of quantifying control quality in the low lateral acceleration regime typical of expressway driving. The tests consists of a low frequency(0.2㎐) sinusoidal steer angle input at constant velocity, typically at 100㎞/h. The steering input magnitude is limited so that lateral acceleration does not exceed 0.2g. We performed many of benchmarking test for objective on center handling and subjective evaluation. With the study of on center handling test for small car, this paper explains the dominant factor for enhancing best steering performance.