• ETRI Journal
• /
• 제38권2호
• /
• pp.235-243
• /
• 2016

A low-noise readout integrated circuit (ROIC) for a microelectromechanical systems (MEMS) microphone is presented in this paper. A positive feedback signal amplification technique is applied at the front-end of the ROIC to minimize the effect of the output buffer noise. A feedback scheme in the source follower prevents degradation of the noise performance caused by both the noise of the input reference current and the noise of the power supply. A voltage booster adopts noise filters to cut out the noise of the sensor bias voltage. The prototype ROIC achieves an input referred noise (A-weighted) of -114.2 dBV over an audio bandwidth of 20 Hz to 20 kHz with a $136{\mu}A$ current consumption. The chip is occupied with an active area of $0.35mm^2$ and a chip area of $0.54mm^2$.

• Journal of Magnetics
• /
• 제17권1호
• /
• pp.36-41
• /
• 2012

The transcranial magnetic stimulation recharges the energy storing condenser, and sends the stored energy in the condenser to the pulse shaping circuit, which then delivers it to the stimulating coil. The previous types of transcranial magnetic stimulation required a booster transformer, secondary rectifier for high voltages and a condenser for smooth type. The energy storing condenser is recharged by switching the high-voltage direct current power. Loss occurs due to the resistance in the recharging circuit, and the single-pulse output energy in the transcranial magnetic stimulation can be changed because the recharging voltage cannot be adjusted. In this study a booster transformer, which decreases the volume and weight, was not used. Instead, a current resonance inverter was applied to cut down the switching loss. A transcranial magnetic stimulation, which can simultaneously alter the recharging voltage and pulse repeats, was used to examine the output characteristics.

• 항공우주시스템공학회지
• /
• 제10권2호
• /
• pp.14-21
• /
• 2016

In this study, we proposed a water rocket CULV-1 (Chosun University Launch Vehicle-1). Unlike a conventional water rocket, CULV-1 can perform the booster rocket, fairing, and payload separation like an actual launch vehicle and also the imaging data acquisition. The conceptual and critical design of the proposed CULV-1 have been performed considering the operation characteristics. The verification tests have been performed from subsystem to system level in accordance with the established test specifications and verification procedures. Through the final launch test of the flight model, we have verified the design effectiveness of the proposed separation mechanisms for water rocket applications and the mission requirements of the CULV-1 also have been complied.

• 전기학회논문지
• /
• 제58권1호
• /
• pp.86-92
• /
• 2009

This paper presents development of 6kw ZVS(Zero Voltage Switching) boost converter by 4-parallel operation. To realize a high capacity converter with 6 kw, 4-parallel operation of 1.5kW unit module is proposed in this paper. To meet high ratio input to output voltage, isolated type booster converter is designed. To achieve ZVS operation of 4-switches of full bridge and protect a voltage overshoot caused by switch turn-off, simple active-clamp circuit is applied to the primary side. For parallel operation of 4-modules, master-slave control method is proposed to achieve input current sharing of 4-unit converter modules accurately. For performance tests, simulation is carried out. Also, load and experimental tests of the developed booster converter, 230Vdc/6kW, are carried out under various conditions. For field tests, the developed converter is applied for boosting a battery power to high DC_link voltage for a VSI inverter which starts a micro-turbine(MT) installed in vehicle and it's performance is verified through high speed motoring a MT up to tens of thousands of rpm.

• Asian-Australasian Journal of Animal Sciences
• /
• 제14권4호
• /
• pp.559-563
• /
• 2001

The effects of feeding a mannan oligosaccharide (Bio-Mos) from 0 to 3 g/kg diet and vaccination program on 1- to 35-day performance (growth and feed efficiency), metabolizable energy, nitrogen utilization and carcass composition of meat chickens were investigated. A general vaccination program was used against IB, IBD and ND with half of the birds per diet receiving a booster dose of IB and ND vaccines at 12 days of age. Dietary supplementation of Bio-Mos (BM) did not influence body weight gain, feed efficiency and nutrient utilization. The highest dietary BM (3 versus 1.5 or 0 g/kg) increased carcass abdominal fat and reduced the proportion of drumstick in the carcass of meat chickens. The booster dose reduced the performance of birds. It was concluded that the addition of BM to the diet of chickens did not significantly influence the performance and nutrient utilization of meat chickens.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2002년도 춘계 학술대회논문집
• /
• pp.47-52
• /
• 2002

The supersonic flow around multi-stage rocket system is analyzed using 3-D compressible unsteady flow solver. A Chimera overset grid technique is used for the calculation of present configuration and grid around the core rocket is composed of 3 zones to represent fins in the core rocket. Flow solver is parallelized to reduce the computation time, and an efficient parallelization algorithm for Chimera grid technique is proposed. AUSMPW+ scheme is used for the spatial discretization and LU-SGS for the time integration. The flow field around multi-stage rocket was analyzed using this developed solver, and the results were compared with that of a sequential solver The speed-up ratio and the efficiency were measured in several processors. As a result, the computing speed with 12 processors was about 10 times faster than that of a sequential solver. Developed flow solver is used to predict the trajectory of booster in separation stage. From the analyses, booster collides against core rocket in free separation case. So, additional jettisoning forces and moments needed for a safe separation are examined.

• 접착 및 계면
• /
• 제3권1호
• /
• pp.37-42
• /
• 2002

Adhesives are becoming increasingly accepted for advanced engineering/boding tasks. Therefore the understanding of the basic principles and the benefits of elastic bonding and structural bonding respectively is of utmost importance. Structural bonding means adhesive performance in load-bearing environments. Furthermore. the time to achieve handling strength has an impact on the economics of an assembly line. The paper gives briefly a summary about the fundamentals of elastic bonding and discusses different adhesive systems in the context of handling strength. Hereby the focus lies on the Warm Melt Technology, and its potential is compared to standard adhesives (l-part, 2-part and Booster Technology, a special 2-C system). Examples illustrate their economical benefits. Main Points : ${\bullet}$ The basic principles and benefits of elastic bonding ${\bullet}$ Warm-melt Technology in comparison with standard adhesives ${\bullet}$ Handling strength an economic issue ${\bullet}$ Combination with Booster-Technology, a special 2-C PUR system ${\bullet}$ Presentation of real world applications Learning Objectives: ${\bullet}$ Fundamentals of elastic bonding ${\bullet}$ Warm-melt Technology: correlation between chain length and cristallinity ${\bullet}$ Handling strength and curing speed of various systems in comparison ${\bullet}$ Real world applications illustrate the potential of the Warm-melt Technology.

• International Journal of Automotive Technology
• /
• 제8권2호
• /
• pp.185-191
• /
• 2007

The new FMVSS 208, 213, 225 regulations include automatic suppression of airbags to prevent low-risk airbag deployment and the use of child seats with a rigid-bar anchor system. The regulations mean that children must sit in the rear seat, but do not include other specific safety measures for their protection. In the rear, restraint equipment consists of three-point shoulder/lap belts for the outside seats and a static two-point lap belt in the middle, with no additional devices such as pretensioners or load limiters; this is far from optimal for children. This study investigated injury rates using a 3-year-old-child dummy. ECE R44 sled tests used a booster, a speed of 48 km/h, and a 26- to 32-g rectangular deceleration pulse. While seated on a booster, the dummies were restrained by an adult shoulder/lap three-point belt. HIC_15 msec, Chest G and Nij were somewhat lower with an emergency locking retractor (ELR)+pretensioner+load limiter than with only an ELR or with ELR+pretensioner. However, the current seat-belt system results in injury rates that exceed the limit for OOP performance under the new FMVSS 208 regulations.

• 한국물환경학회지
• /
• 제23권4호
• /
• pp.543-550
• /
• 2007

In this study, combined sewer overflows (CSOs) from five independent rainfall events in rural city area were collected and investigated. First flush effect in sewage pumping station located near the WWTP was retarded 30 to 60 minutes from booster pumping station. The ratios between SS, COD and TP concentrations prior to rainfall and peak concentrations during the period of rainfall were highly increased but nitrogen was relatively constant, which indicates that it is not associated with particles washed off from the surface of watershed. Mass balance results show that 30% of CSO was generated from booster pump station and 66.5% of CSO was from the whole runoff area. In the area of newly constructed sewer system, CSO problem was related with pump and sewer capacities, but in other old sewer system equipped area, it was due to the collection efficiency. Finally, Log-Log pollutant rating equations were suggested.

• 한국추진공학회지
• /
• 제25권2호
• /
• pp.79-87
• /
• 2021

본 연구에서 축 방향으로 충전 된 이종 추진제를 적용 이중 추력 추진기관의 성능 예측/해석 방법을 개발하였다. 부스터로부터 서스테이너 단계로 천이될 때 계면에서 성능에 관한 과도현상이 발생하였는데, 그 과도현상의 원인과 특성을 연소시험 결과와 함께 비교하여 조사하였다. 성능과도 현상은 추진제 물성이 서로 다른 추진제 사이 형상설계뿐만 아니라, 추진제 경화 수축에 따른 제작상 오차에 의해 민감하게 발생되고 있음을 확인되었다.