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조영진(Youngjin Cho),장래혁(Naehyuck Chang) 大韓電子工學會 2009 電子工學會論文誌-SD (Semiconductor and devices) Vol.46 No.12
일반적인 동적 전압 조절(dynamic voltage scaling)의 가정과는 다르게 실제 시스템에 있어서는 응용 프로그램의 성능이 프로세서의 동작 속도에 정비례하지 않는다. 본 연구에서는 응용 프로그램의 성능과 동작 속도의 관계를 실측을 통하여 수치화 하여 응용 프로그램의 특성을 모델링하고 각기 다른 응용 프로그램 특성 계수를 갖는 태스크 집합에 적합한 스케줄링 기법을 제시하였다. 또한, 모든 태스크의 단위 수행시간 변화에 따른 에너지의 변화량이 동일해야 에너지 최적이 된다는 해석적인 정리를 제시하였다. 본 연구에서 제시하는 스케줄링 기법은 이러한 해석적 정리에 기반을 두기 때문에 항상 각 태스크에 시스템에너지 최적이 되는 조절비를 제시한다. 합성 태스크 집합을 이용한 실험결과에서 기존 연구 대비 약 7%의 추가적인 에너지절감 효과를 얻을 수 있었다. In the real system environments, the performance of the application is not linearly proportional to the clock frequency of the microprocessor, in contrast to the general assumption of conventional dynamic voltage scaling. In this paper, we analytically model the relation between the performance of the application and the clock frequency of the microprocessor, and introduce the energy-optimal scheduling algorithm for a task set with distinct application characteristics. In addition, we present a theorem for the energy-optimal scheduling, which the derivative of the energy consumption with respect to the execution time should be the same for all the tasks. The proposed scheduling algorithm always generates the energy-optimal scaling factor thanks to the theorem for energy-optimal scheduling. We achieved about 7% additional energy reduction in the experiments using synthetic task sets.
RCAR 후방 저속 충돌을 위한 Rear bumper system 설계에 관한 연구
조영진(Youngjin Cho),김동석(Dongseok Kim),방용식(Yongsik Bang) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5
The repair cost in a low speed crash could be reduced by establishing energy absorbing element such as a crash box. The rear structure of an auto-body should be designed to reduce the repair cost in a low speed crash accident. In this paper, 6 crash box designs are evaluated to maximize energy efficiency with 2 types of rear bumper beams an optimized round beam pattern showed the best performance and an open section bumper beam absorbed more energy than a closed section bumper beam did because of more room for a crash box.
조영진(Youngjin Cho),원준희(Junhee Won),박준영(Junyoung Park),강승천(Sungchun Kang),이동인(Dongin Lee) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
It is well known that two representative method to satisfy the EURO4 emission regulation. The one is the EGR system that reduces NOx in an engine by using EGR and PM by OPF. But this system has disadvantages of fuel efficiency and requirement for larger engine cooling capacity. The other is SCR system that reduces NOx in exhaust gas by dosing reagent (urea water solution) into exhaust gas. And the SCR system needs to decrease PM by optimization of fuel combustion. The SCR system has advantages of fuel efficiency and good durability of engine. Recently as the price of oil (diesel) goes up, the commercial vehicle drivers are more concerned about the fuel economy. So the European major manufacturer of commercial vehicle adopted the SCR system because of the above mentioned advantages. And this study focused on the development of EURO4 engine and commercial vehicle equipped with SCR system.
조영진(Youngjin Cho),원준희(Junhee Won),김상호(Sangho Kim),이동인(Dongin Lee) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
It is well known that two representative method to satisfy Tier4 interim emission regulation. The first method is the reduction of NOx in an engine by using EGR and the elimination of PM by DPF but this system has disadvantages of fuel efficiency and requirement for larger engine cooling capacity. The second method is the reduction of PM in an engine by high combustion efficiency and NOx is removed by SCR system. This system has disadvantages of reagent refill and after-treatment system complexity. In case of off road vehicle, in many cases, there is no method to refill reagent for SCR system therefore most off road vehicle manufacturers have adopted DPF system for Tier4 engine and this study focused on the development of Tier4 interim engine and off road vehicle equipped with DPF system.
RCAR 후방 저속 충돌을 위한 Rear Crash Box 설계에 관한 연구
조영진(Youngjin Cho),김동석(Dongseok Kim) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The research committee for automobile repairs (RCAR) an international body of insurance research centers, has adopted the typical low speed crash test based on an average damage level in crash accidents to estimate the damageability and safety. The repair cost in a low speed crash could be reduced by establishing energy absorbing element such as a crash box. The rear structure of an auto-body should be designed to reduce the repair cost in a low aped crash accident.
조영진(Youngjin Cho),장건희(Gunhee Jang),정동하(Dongha Jung) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
Balls rotating along the race in the Automatic Ball-Balancer (ABB) are used to reduce the vibration due to unbalanced mass of the rotating system during steady-state rotating motion. However, they increase the transient vibration due to mass imbalance of balls. We propose a ball control method in such a way to hold balls utilizing magnetic force in transient state to reduce the transient vibration of the rotating system. The vibration of ABB with the proposed method was compared with that of the ABB with the conventional method by using ADAMS. We showed that the ABB with the proposed ball control method reduces transient vibration as well as steady-state vibration of the rotating system in comparison with the conventional method.
조영진(YoungJin Cho),전종수(JongSoo Jeon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
In this study, we try to find the root cause of water condensing failures in a headlamp using chemical and mechanical analysis. Through the surface inspection by OM, SEM and CT, it was found that water infiltrate into the headlamp through hotmelt adhesive debonding part caused by adhesion force degradation and poor quality. IR spectra shows that adhesion force degradation are characterized by increase of some functional group(1742, 1710, 1649, 1016). Through the ESPI measurement, it is turned out that bonding structural change by thermal expansion and degradation of adhesive can be the cause of void generation. So it is recommended that cooling passage and the bonding part should be redesigned to give a guarantee of less thermal stress and high adhesion quality.
스로틀 바디 제어신호 전달용 커넥터의 이상전압 강하 현상 원인 규명
조영진(YoungJin Cho),장석원(SeogWeon Chang) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
This paper try to find root-cause of failure in a connector used in transmitting signals for throttle body control in automotives by analyzing possible failure causes and performing experiments to simulate the cable failure in field. The connector comprises fins, wires, and case moldings. The failure is due to degradation of initial clamping force required fixing fins and wires in the connector. Expansion and compression of the case molding material surrounding fins would cause the degradation. Investigations of strict initial claming force and control of thermal expansion property of the molding are required to prevent the failure.
EGR의 유입 위치에 따른 실린더별 분포와 엔진 및 배기 성능에 관한 연구
조영진(Youngjin Cho),박재용(Chaiyong Park),박심수(Simsoo Park),이창훈(Chang-Hoon Lee),이현우(Hyun-Woo Lee) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
In recent years the needs for development of high performance, better fuel-economy, and low emission<br/> gasoline engine increase. To meet the current and future stringent emission regulations, EGR(Exhaust Gas<br/> Recirculation) that prevent knocking, improves fuel economy and reduce NOx emission is needed. In<br/> particular, E-EGR(Eletronic Exhaust Gas Recirculation) is required to apply EGR to direct injection engine<br/> and lean combustion engine.<br/> In this paper EGR distribution in each cylinder(four cylinder 1.5L, SI engine), engine performance and<br/> exhaust emissions according to EGR supply position are investigated.