실험실에서의 발코니창호 차음성능 평가

김태희(Namwook Kim),신일섭(ILseop Shin),조창근(Changeun Cho),오진균(Jinkyun Oh),김남욱(Namwook Kim) 한국소음진동공학회 2007 한국소음진동공학회 학술대회논문집 Vol.2007 No.3

Adaptive Energy Management Strategy for a Plug-In Hybrid Electric Vehicle with Pontryagin's Minimum Principle Based on Daily Driving Patterns

Namwook Kim,Jongryeol Jeong,Chunhua Zheng 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.6 No.3

Optimal control ideas based on Pontryagin’s Minimum Principle (PMP) have become mature techniques for maximizing the fuel efficiency of Hybrid Electric Vehicles (HEVs) and Plug-in Hybrid Electric Vehicles (PHEVs). The outstanding performance of this control concept has already been verified in many studies, in which the PMP-based control produces optimal solutions that are very close to the global optimal solution obtained by Dynamic Programming (DP). However, the drawback of the control concept is that the PMP-based control will not guarantee optimality if no information about the future driving condition is given. This is not just a drawback of the PMP-based control, but it is an unavoidable limitation in most optimal control concepts. Therefore, previous studies have been focused on finding an optimal costate when the future driving conditions are given or predicted prior to driving. In this study, a methodology that analyzes the past driving pattern and updates the control parameters is proposed by assuming that vehicles are operated under repeated driving conditions. A control parameter, or a costate in the PMP-based control, can be estimated from two parameters that characterize the driving conditions, and the correlation between the costates and the energy consumption patterns is used to update the control parameter. Based on this control concept, the final State of Charge (SOC) at the end of each drive gets gradually closer to the desired value as the driving cycle is repeated. The methodology can be used for vehicles operated under repeated driving patterns, such as commuting buses, parcel delivery vehicles, or refuse collection trucks.

Half-metallic ferromagnetism and metal–insulator transition in Sn-doped SrRuO₃ perovskite oxides

Kim, Namwook,Kim, Rokyeon,Yu, Jaejun Elsevier 2018 Journal of magnetism and magnetic materials Vol.460 No.-

<P><B>Abstract</B></P> <P>We investigate the electronic and magnetic properties of <SUB> SrRu 1 - x </SUB> <SUB> Sn x </SUB> <SUB> O 3 </SUB> by carrying out density-functional-theory calculations to show that a half-metallic ferromagnetic ground state emerges for the Sn doping of x ≳ 0.5 . To examine the effect of on-site Coulomb interactions for the Ru <I>d</I> orbitals, which was suggested to enhance the half-metallicity in SrRuO<SUB>3</SUB>, we employed both the local spin-density approximation (LSDA) as well as the LSDA + <I>U</I> method. For all the possible configurations of Sn doping for x = 1 / 8 , 1 / 4 , 1 / 2 , 5 / 8 , 3 / 4 , and 7 / 8 within the 2 × 2 × 2 unit cell, we monitor the Ru <SUB> t 2 g </SUB> bandwidth as well as the valence band maximum in the majority-spin channel and demonstrate that the Ru <I>d</I> electron hopping is blocked by the Sn-substituted sites so that the Ru <SUB> t 2 g </SUB> bandwidth becomes reduced as the doping <I>x</I> increases. For x < 0.5 , the valence band maximum still touches the Fermi level so that <SUB> SrRu 1 - x </SUB> <SUB> Sn x </SUB> <SUB> O 3 </SUB> remains as a usual ferromagnetic metal. A further reduction of the Ru <SUB> t 2 g </SUB> bandwidth for the range of 0.5 ≲ x ≲ 0.7 turns it into a half-metallic ferromagnet. As for x > 0.7 , the Ru <SUB> t 2 g </SUB> bandwidth gets so narrow that even a small on-site Coulomb interaction, e.g., <SUB> U eff </SUB> = 1.0 eV induces a band-gap, which indeed corresponds to a gap of the Ru impurity bands in the SrSnO<SUB>3</SUB> oxide semiconductor.</P>

Energy-Saving Strategy for Speed Cruise Control Using Pulse and Glide Driving

Tacksu Kim,Woong Lee,Dohyun Park,Jaekwang Jung,Namwook Kim 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.6

As an effective way to reduce greenhouse gas emissions, automotive manufacturers have made significant efforts to lower carbon-related usage by improving the fuel efficiency of vehicles. For example, driving assistance or automated vehicle technology can improve efficiency because undesirable driving intentions or behaviors of human drivers can be removed, while the controller can maximize efficiency by utilizing the information of the powertrain characteristics. In this study, control concepts for cruise driving, such as Constant Speed (CS), Pulse and Glide with fuel-cut (PnG-FC), or Pulse and Glide with idling (PnG-ID) are investigated to improve fuel efficiency under different vehicle speeds and road grades. A mode decision map selecting the best control mode is obtained based on the analyzed results. For instance, PnG control is better than the Constant Speed when the vehicle is driving with an average speed of 100 km/h, where PnG-FC is preferred to the PnG-ID under the glide mode, which improves the fuel efficiency by 3.36%, compared to CS. The comparative study will be helpful for engineers to enhance their understanding of the control problem, and, as a result, the mode decision map provides very practical information that can be used to develop a real-world application.

CNG 탱크 내 연료 계측을 위한 초음파 센서의 압전소자 개수 변경에 따른 영향 분석

김남욱(Namwook Kim),윤태준(Taejun Yoon),최두석(Dooseuk Choi),정인호(Inho Jeong) 한국자동차공학회 2017 한국자동차공학회 학술대회 및 전시회 Vol.2017 No.11

철도 차량의 연결용 완충기의 충돌 시뮬레이션

김남욱(Namwook Kim),양시우(Siu Yang),김기남(Kinam Kim),장현목(Hyeonmog Jang),박영일(Yeong-il Park) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Coupler systems of trains are composed of buffer or hydraulic elements. These coupler systems can protect the train against the collision because the systems absorb the impact of the collision. The dynamic behavior of the coupler systems depends on the number of the cars which compose the train and stiffness of the cars. To analyze the dynamic behavior of the coupler systems, simulator is introduced in this paper, by which maximum force of the coupler systems and velocity of the cars can be calculated. In general, the first coupler which is attached at the front of the train gets the maximum force at simulation, and the maximum force of the first coupler doesn't relate to the number of the train when the number is bigger than three. The maximum force of the first coupler, however, increases along the stiffness of the cars because the maximum force increases as the period of the impact is shorten. The period approximately can be acquired from the stiffness of the coupler systems and the stiffness of the cars, so the maximum force, which affects the life time of the coupler systems, can be optimized if the coupler system is well designed.

골프장에 관한 지방세 과세제도의 합리화 방안

김남욱(Kim NamWook) 한국토지공법학회 2016 土地公法硏究 Vol.73 No.1

고도의 경제성장과 산업발달, 주5일근무로 인한 여가생활 증대로 스포츠문화에 관심이 증대되고 있다. 특히 저출산·고령화로 인한 지방자치단체의 복지수요증대와 열악한 지방재정의 건전성 확보와 더불어 지방세제를 지속가능한 과세체계를 마련하는 것이 쟁점 사안으로 부각되고 있다. 골프장에 대하여 1970년대 사치성 재산으로 분류하여 소비를 억제하고 검소한 생활을 진작하고자 하였다. 21세기의 오늘날에도 골프장에 대한 재산세와 취득세의 중과세제도가 유효한지를 일본의 입법례와 우리나라 판례 및 법리를 비교법적으로 고찰한다. 골프장의 지방세 중과세제도를 조세법률주의, 과잉과세금지원칙, 공평과세원칙의 관점에서 사치재산의 중과세 위헌성문제를 다루고, 골프장의 외부불경제효과와 지방세의 응능성 원칙에 부합하도록 국세인 개별소비세의 지방세로 이양하여 골프장이용세의 도입을 강구한다. 또한 취득세민 부과되고 있는 골프회원권에 대하여 다른 자산과 형평성을 고려하여 재산세부과방안을 모색하고, 골프장 토지에 대한 종합합산과세, 별도합산과세, 분리과세제도를 검토하여 분리과세방안을 제시한다. High economic growth and the development of industry, to sports culture interest has increased to the improvement of leisure life by five days a week work. In particular, in addition to ensuring the growth and of poor local financial soundness of welfare demand of local governments by the declining birthrate and aging population, has emerged in the issue is the provision of a possible taxation system sustain the local tax system. For golf, to suppress the consumption is classified in the 1970s luxury properties, he tried to lift a frugal life. 21 century of whether taxation of the golf course of the fixed asset tax and acquisition tax today is valid, to compare legal consideration of the Japan of legislation examples and our country of precedent and doctrine. Local tax heavy taxation system the tax law principle of the golf course, excessive taxation prohibition of principle, from the point of view of fair taxation principles, dealing with problems taxation constitutionality of the luxury property, external economical effect and the Yeah possibility of local tax of golf of principle to to fit, take the introduction of golf course use tax and transfer to the local tax of individual consumption tax is a national tax. In addition, the golf membership rights that have been imposed acquisition tax Min, taking into account the fairness other assets, to seek the imposition method of fixed asset tax, total sum taxation of the golf course land, separately sum taxation, separation consider the tax system to present a separate taxation proposal.

실시간 에이전트 모니터링 시스템

김남욱(Namwook Kim),권택수(Taeksoo Kwon),박준영(Junyoung Park),박지혜(Jihye Park) 한국정보과학회 2014 한국정보과학회 학술발표논문집 Vol.2014 No.6

Pontryagin’s Minimum Principle (PMP)를 이용한 하이브리드 전기차의 주행 제어 최적화

김남욱(Namwook Kim),임원식(Wonsik Lim),오창은(Chang Eun Oh),변상민(Sangmin Byun),차석원(Suk Won Cha) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4

Several optimal control ideas for Hybrid Electric Vehicles (HEVs) were proposed in the literature. The representative optimal concept based on the bellman’s optimality, Dynamic Programming, guarantees a global optimal solution which could be obtained from an optimal field. In this paper, we suggest the Pontryagin’s minimum principle as an optimal control concept, in which the principle produces necessary conditions that the optimal control trajectory must satisfy. From a static model, the optimal results solved from PMP show that the results are really close to the results solved from DP, which should be supposed to be a global optimal solution. The differences between the results solved from PMP and the results solved from DP are only under 1 %. By the optimal control concept, PMP, we could build a real-time optimal controller because the technique is fundamentally based on an instantaneous optimal concept, which means that the control idea based on PMP is very useful if we have an intelligent model to approximate the costate in real-time driving.

듀얼 모드 하이브리드 시스템의 구성

김남욱(Namwook Kim),양시우(Siu Yang),양호림(Horim Yang),조성태(Sungtae Cho),임원식(Wonsik Lim),차석원(Suk won Cha) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

Dual mode hybrid systems are composed of few combined planetary gear sets. One planetary gear set has two DOF(degree of freedom) and the DOF increases when planetary gear sets are added, so it is complicate to analyze the systems. Methodologies of combining the planetary gear sets can be various methods, but it is needed that the methodologies have consistency. To the consistency, the equivalent parameters, α', β', R'a, R'b are introduced in this paper, and the arbitrary system, E-IVT(Electric Infinitely Variable Transmission) developed by Renault, is converted to the equivalent system with these parameters. Furthermore, the system efficiency can be represented by these parameters at hybrid mode, and the strategies of controlling the compound split can be improved by the analysis of the compound splits in this paper.