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TRUCK CAB 전착 도장 시 부력 방지용 HOLE 영향 평가
임정환(Junghwan Lim) 한국자동차공학회 2004 한국 자동차공학회논문집 Vol.12 No.4
When a truck cab is conveyed at a constant speed by a hanger and immersed into the painting reservoir, it may fall off from the hanger by buoyancy. In order to reduce the buoyancy, on the bottom of a cab panel are holes placed, which allow paint to flow into the inside of a cab. In this study, a differential equation is derived which can be solved numerically by using 4th-Order Runge-Kutta method to calculate transient behavior of the buoyant force with sizes and locations of the holes given. The solution is utilized to optimally determine sizes and locations of the holes.
국종영(Jongyoung Kuk),임정환(Junghwan Lim) 한국자동차공학회 2008 한국 자동차공학회논문집 Vol.16 No.4
The vibration of a vehicle, which is caused by and transmitted from the engine, has significant effect on the ride comfort and the dynamic characteristics of the engine mount system have direct influence on the vibration and noise of the vehicle. This paper examines the body shake caused by the engine excitation force on engine key on/off of a medium truck by experiment and simulation. The analysis model consists of the engine, a body including the frame, front and rear suspensions and tires. The force element between the body and the suspension is modeled as a combination of a suspension spring and a damper. The engine shake obtained from the experiment was compared with the result of the computer simulation, and by using the verified computer model, parametric study of the body shake on engine key on/off is performed with changing the stiffness of an engine mount rubber, the engine mount angle, and the position of engine mounts.
삼화 원탄과 무회분탄의 촉매(K₂CO₃) 가스화 반응성 비교 연구
공용진(Yongjin Kong),임정환(Junghwan Lim),임영준(Youngjoon Rhim),전동혁(Donghyuk Chun),이시훈(Sihyun Lee),유지호(Jiho Yoo),이영우(Young-Woo Rhee) 한국청정기술학회 2014 청정기술 Vol.20 No.3
석탄의 가스화는 촉매 도입 시 온순 조건에서 가능하나, 석탄 내 회분에 의한 비활성화에 의해 반복적인 촉매 활용이 힘들다. 이에 본 연구에서는 삼화 원탄에서 회분을 제거하여 삼화 무회분탄(ash-free coal, AFC)을 제조한 후 가스화 반응성을 원탄과 비교하여 알아보았다. 우선 원탄을 대상으로 고정층 반응기에서 수증기 공급량, 공간 속도(space velocity), 온도 및 촉매를 변수로서 가스화 조건을 결정하였다. 고체상 혼합법으로 다양한 촉매 도입 시, 유동성을 갖는 K₂CO₃가 가장 높은 활성을 보였다. 무회분탄은 원탄보다 낮은 반응성을 보였으며, 이는 용매(1-methylnaphthalene, 1-MN)를 이용한 고온 추출 및 건조 공정 중에 소모된 산소 기능기 함량과 증가된 탄화도(carbonization)에 기인한다. K₂CO₃ 가 혼합된 무회분탄의 반응성은 급격히 증가하여 낮은 온도 (700 ℃)에서도 높은 전환율을 보였다. 이때 H₂/CO와 CO₂/CO 비율도 증가하는데, 이는 촉매에 의해 수성가스전환(water-gas shift) 반응이 활성화됨에 기인한다. 본 연구에서는 무회분탄의 저온 촉매 가스화 반응을 통해 석탄 가스화 공정의 경제성이 개선될 수 있음을 확인하였다. Catalytic gasification of raw coals at mild condition is not realized yet mainly due to deactivation of catalysts via their irreversible interaction with mineral matters in coal. In this work, the gasification behavior of ash-free coal (AFC) was compared with that of the parent raw coal. In order to modify the gasification conditions, the raw coal gasified with fixed variables (water supply, space velocity, temperature, catalysts) in a fixed bed reactor. When catalysts are added by physical mixing method with coal, K₂CO₃ was the most effective additives for steam gasification of coal. However, the activity of ash-free coal (AFC) was much less reactive than raw coal due to high temperature extraction in a 1-methylnaphthalene under 30bar at 370 ℃ for 1 h, almost removed oxygen functional groups, and increased carbonization. The addition of K₂CO₃ in AFC achieved higher conversion rate at low temperature (700 ℃). At that time, the molar ratio of gases (H₂/CO and CO₂/CO) was increased because of water-gas shift reaction (WGSR) by addition of catalysts. This shows that catalytic steam gasification of AFCs is achievable for economic improvement of gasification process at mild temperature.
김용일(Yongil Kim),김기태(Gitae Kim),임정환(Junghwan Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The requirements of truck customers have been increased to transport their precious and fragile freights safely with rising industry volume of high-price and fragile goods. Air suspension trucks are liable to decrease the amplitude of vibrations by using its own characteristics of air spring. These air spring characteristics also have a benefit of keeping low natural frequency under load variations. Moreover. air suspension trucks are capable of having relatively constant vehicle height by controlling the air pressure under kerb and G.V.W load conditions. In this paper, the influences of an air suspension system on freight protection have been studied. To analyze those effects, vertical acceleration at the frame of the air suspension vehicle and the leaf suspension vehicle have been measured and compared.
대형버스의 루프 진동에 영향을 미치는 인자에 관한 연구
국종영(Jongyoung Kuk),박종찬(Jongchan Park),임정환(Junghwan Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
If the vibration is occurred at large-sized bus roof, it makes people annoying and complaining the quality of vehicle. In design stage, it must be considered. To assess vibration at roof which is equipped with air conditioner in design stage, FE-model is constructed. Computer simulation analysis and test is performed. The dynamic characteristics of bus are found by using eigenvalue method. It is related with dynamic behavior. The running conditions of bus are velocity and road condition which followed test condition. And the frequency response of vehicle is well correlated with analysis result. Modal participation method is used for finding major modes at each peak. Front and rear suspension spring, engine mounting stiffness are selected for modal contribution. To reduce vibration level of front and rear suspension spring, engine mounting stiffness are properly combined. From this study, the vibration level is lowered at roof.
문일동(Ildong Moon),김기태(Gitae Kim),임정환(Junghwan Lim),현상학(Sanghak Hyun),오재윤(Chaeyoun Oh) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The steering feel is one of the major handling performance of the vehicle. This paper develops a computational model for objective steering feel assessment of a commercial vehicle. In order to validate the reliability of the developed computation model, tests with a real vehicle are performed. Simulation results performed with the developed computational model shows a good correlation with test results performed with a real vehicle. The developed model is used for analyzing the influence of the characteristic of a steering system and tire on steering feel. That is, a study is performed to analyze the influence of the major parameters which significantly affect on the characteristic of the steering system and tire on steering feel with the developed model.
유연체 판스프링 모델을 이용한 서스펜션 지오메트리 연구
김기태(Gitae Kim),문일동(Ildong Moon),임정환(Junghwan Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper proposes a modeling technique which is able to not only reliably and easily represent the wheel rate but also analyze the suspension characteristics. The flexible body model of the leaf spring is developed by interfacing the finite element model and computation model of the leaf spring. The SPMD test of the vehicle is conducted for the validation of the reliability of the flexible body model of the leaf spring developed in this paper. The SPMD test is started at an constraint state of frame using the jig with the excitation amplitude of 1-2㎜/sec. The simulation is conducted with the same condition as the SPMD test. Then, the simulations are conducted with bump mode and roll mode. The diagram of wheel rate and wheel alignment from the SPMD test is compared with the ones from the simulation for the validation of the reliability of the model. The flexible body of the leaf spring is compared with the rigid body of the leaf spring. The sensitivity analysis of the front suspension and steering system is also conducted with the developed flexible body model under a bump mode of K&C analysis.
국종영(Jongyoung Kuk),박종찬(Jongchan Park),임정환(Junghwan Lim) 한국자동차공학회 2010 한국 자동차공학회논문집 Vol.18 No.6
If the vibration is occurred in a large-sized bus roof, it makes people annoying and complaining the quality of a large-sized bus. So in design stage, it must be considered. To assess vibration at the roof which is equipped with air conditioner in design stage, finite element model is constructed. Computer simulation analysis and experimental method are performed. The dynamic characteristics of the large-sized bus are found by using eigenvalue method. It is related with dynamic behavior. The running conditions of a large-sized bus are velocity and road condition which followed experimental conditions. And the frequency response of a large-sized bus is well correlated with analysis result. Modal participation method is used for finding major modes at each peak. Using this method, we found that front and rear suspension system, engine mounting system and roof structure are the major reasons of the roof vibration. To reduce vibration level of roof in a large-sized bus, spring stiffness of front and rear suspension system, spring stiffness of engine mounting system and roof structure are properly combined. From this study, the vibration characteristics of the roof structure of a large-sized bus can be to a satisfactory level.
수치해석을 이용한 HVAC Blower의 소음특성 고찰
양기영(Keeyoung Yang),조봉래(Bonglae Cho),임정환(Junghwan Lim) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this study, the noise characteristics of HVAC system was approached by CFD and Computational Aeroacoustics. Two operating point, estimated optimum point and free delivery point, of HVAC system was estimated using CFD at the early development stage of HVAC system. The flowrate and acoustics is calculated about the two different shaped model. The calculated result has same tendency with experimental result. The region of BPF noise source is founded by the visualization of acoustic sources.