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전자기 리니어 액츄에이터의 집중매개변수 모델링 및 해석
장재환(Jae-Hwan Jang),조성진(Seong-Jin Cho),김진호(Jin Ho Kim) 한국기계가공학회 2016 한국기계가공학회지 Vol.15 No.5
An electromagnetic linear actuator is controlled precisely and securely and is useful in devices that require linear motion. The most commonly used method in the performance verification process for an electromagnetic actuator is finite element analysis that utilizes CAE. However, finite element analysis has the disadvantage that modeling and analysis consume a lot of time. Accordingly, lumped parameter analysis can be an alternative approach to the finite element method because of its computation iteration capability with fair accuracy. In this paper, the lumped parameter model and simulation results are presented. In addition, the results of the lumped parameter analysis are compared with those obtained from finite element analysis for verification.
이중 연료 분사구조를 갖는 희박-예혼합 버너의 연소특성 연구
장재환(Jae Hwan Jang),조주형(Ju Hyeong Cho),김한석(Han Seok Kim),이상민(Sang Min Lee),김민국(Min Kuk Kim),안국영(Kook Young Ahn) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.1
본 연구에서는 가스터빈 연소기에 적용하기 위한 예혼합 스월버너의 배기가스 및 화염안정성 최적화를 위하여 버너의 구조변경에 따른 연소특성을 실험적으로 분석하였다. 버너의 연료분사구조에 따른 배기가스 배출 특성을 파악하고자 단일연료분사구조와 이중연료분사구조를 갖는 예혼합 버너의 연소특성을 비교 분석하였으며 이중연료분사구조 적용 시 연료/공기 혼합특성이 향상되어 CO와 NOx의 배출농도가 감소하는 경향을 나타내었다. 또한, 노즐출구와 라이너의 지름 비(confined ratio)에 따른 연소부하 및 배기가스 특성을 분석한 결과 confined ratio 감소 시 연소부하 감소로 인해 NOx 배출농도가 감소되었으며, 체류시간의 증가로 인해 CO의 산화 반응이 증가하여 CO 배출농도가 감소하였다. 노즐분출속도는 30 ㎧에서 배기가스특성이 우수하며, 속도 증가(40 ㎧) 시 배가스특성이 저하되고 속도 감소(20 ㎧) 시 화염안정성이 저하되었다. This study aims to experimentally investigate the combustion characteristics of a lean premixed swirl-stabilized burner with dual-stage fuel injection arrays. The results show that a variation in the fuel distribution to fuel stages 1 (upstream) and 2 (downstream) produces a noticeable change in the NOx and CO emissions. Reducing the confined ratio, defined as the ratio of the nozzle exit diameter to the liner diameter, may reduce NOx and CO emissions owing to reduced combustion loading and longer residence time, respectively. A nozzle exit velocity of 30 ㎧ shows the optimum characteristics in terms of NOx and CO emissions and flame stability: increasing or decreasing the nozzle exit velocity leads to a degradation in emissions or flame stability, respectively.
장재환(Jae-hwan Jang),김진호(Jin-ho Kim),이수정(Su-jeong Lee) 한국자기학회 2015 韓國磁氣學會誌 Vol.25 No.3
This paper reports the design of solenoid in a coilgun for high velocity of projectile in a coilgun system, according to diameter of coil. Coilgun using a magnetic force means a mechanism that can control the magnetic material. When momentarily supply a large current to the solenoid instantaneous magnetic field is created around the coil, the projectile is fired by receiving a magnetic force towards the center of the coil, based on the right-hand rule of Fleming. The velocity of projectile is proportional to the magnetic force generated by the electromagnetic coil. The current affects the life of the coil and the current limit exists. Therefore, the coilgun design, which does not exceed the current limit and the magnetic forces are at the maximum, is required. In this paper, whether it is possible fire looking for the optimal number of turns according to the diameter of the coil from AWG #6 to AWG #18 for the design of the solenoid coil, and comparative analysis firing rate associated with it.
장재환(Jae-Hwan Jang),김진호(Jin-Ho Kim) 한국기계가공학회 2015 한국기계가공학회지 Vol.14 No.5
In this paper, we study the optimal design for improved rotation latch system performance. The factors affecting the Torque generated in the armature were chosen as design variables. Utilizing the vertical matrix, the orthogonal array table was created to predict the results through minimal analysis. To confirm the Torque generation amount, by utilizing the commercial electromagnetic analysis software MAXWELL, finite element analysis was performed. The approximation method and experimental design through the commercial PIDO tool PIAnO for optimal design and calculations were utilized to perform experiments using an optimization method with evolutionary algorithms. Using the approximation model, design factors were determined that can maximize the torque generated in the armature, and the simulation was performed.
HiperLAN/2 시스템에서 가변적인 RCH 채널 할당방안
장순건(Jang soon-gun),장재환(Jang jae-hwan),임석구(Lim seog-ku) 한국콘텐츠학회 2009 한국콘텐츠학회 종합학술대회 논문집 Vol.7 No.1
HiperLAN/2(High performance radio Local Area Network)에서의 MAC(Media Access Control)프로토콜은 TDMA/TDD(Time Division Multiple Access/Time Division Duplex)기반으로 동작하며, 단말은 RCH(Random CHannel) 구간을 통해 채널 경쟁에서 성공함으로써 데이터 전송 기회를 획득한다. 그러므로 AP(Access Point)는 각 RCH에서 단말들의 채널요청메시지의 성공 및 충돌수에 따라, 다음 프레임에서 최적의 RCH 개수를 동적으로 할당할 수 있어야 한다. 본 논문에서는 HiperLAN/2에서의 성능향상을 위해 충돌과 성공을 고려하여 RCH(Random CHannel)수를 고정적인 값만큼 증감하는 방법을 제안하였다. 제안한 방법의 효율성을 입증하기 위해 시뮬레이션을 수행하였으며, 처리율과 접속지연 관점에서 분석하였다. The MAC protocol of HiperLAN/2 is based on TDMA/TDD. Mobile terminal acquires a data transmission opportunity as successfulness in channel competition through RCH(Random CHannel) phase. Therefore, AP (Access Point) be able to dynamically assign optimum RCH at next frame according to the number of success and collision. In this paper, we suggest scheme that fluctuate RCH (Random CHannel) number as fixed value considering success and collision for improvement of performance in HiperLAN/2. To prove efficiency of proposed scheme, a lots of simulations are conducted and analyzed in view of throughput and access delay.
부력의 영향을 포함한 점탄성 유체의 열전달에 관한 수치해석
손창현,안성태,장재환,Sohn, Chang-Hyun,Ahn, Seong-Tae,Jang, Jae-Hwan 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.4
The present numerical study investigates flow characteristics and heat transfer enhancement of the viscoelastic non-Newtonian fluid in a 2:1 rectangular duct. The combined effect of temperature-dependent viscosity, buoyancy and secondary flow caused by second normal stress difference are all considered. The Reiner-Rivlin model is used as a viscoelastic fluid model to simulate the secondary flow and temperature-dependent viscosity model is adopted. Three types of thermal boundary conditions involving different combinations of heated walls and adiabatic walls are considered in this study. Calculated Nusselt numbers are in good agreement with experimental results in both the thermal developing and thermally developed regions. The heat transfer enhancement can be explained by the combined viscoelasticity-driven secondary flow, buoyancy-induced secondary flow and temperature-dependent viscosity.