• 한국대기환경학회지
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• 제17권4호
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• pp.321-329
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• 2001

This study included three experiments to evaluate in-vehicle exposures to PM10 and CO: 1) evaluation of in-passenger car exposures, 2) evaluation of in-public bus exposures, and 3) simultaneous evaluation of in-passenger car and in -university bus exposures. The tests of four factors (transportation mode, passenger-car type, commute period, and commute season were focused. A total of 40 actual passenger car commuters, 20 public bus commuters, and four university buses were recruited or surveyed. The same commuters ware participated in both the summer and winter studied. Two factory such as transportation mode and passenger-car type were found to have little effect on the in-vehicle levels of PM10 and CO. Commute period was found to have little effect on the in-vehicle CO levels. Conversely, the other factor, commuting season was found to influence on the in-vehicle levels of PM10 and CO. The present study also confirmed that under the Korean commute conditions, vehicle interiors are an important microenvironment for exposure to PM10 and CO. This was supported by finding that the in-vehicle Air levels were much higher than ambient air levels reported by several previous studies. The mean in -vehicle PM10 concentrations were 114 and 103$\mu\textrm{g}$/m$^3$for passenger cars and public buses, respectively. For CO, the mean in-vehicle concentrations were 2.9 and 2.6 ppm for passenger cars and public louses, respectively.

• 한국멀티미디어학회논문지
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• 제21권6호
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• pp.649-658
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• 2018

In this paper, we propose a mechanical contact inner tap inspection system that can inspect the defect of the inner tap immediately after inner tap is processed within the machining center. The inspection module has the collet chuck structure, so it can mounted on the main spindle of the machining center during inspection. It was developed with a focus on inspection for tap having 20 mm depth which is primarily fabricated in automotive parts and has a double sided PCB-type control system including sensing function based on Zigbee module, micom and IR sensor for wireless transmission of measured data with low power operation, and also a battery for supplying electric power. The current consumption is 46.8mA in the inspection operation mode and 0.0268mA in the power saving mode for 3.7V of the applied power source, so that 30,000 times or more inspection can be performed with assumed 5 seconds inspection time for one tap. Experiments in test jig system and actual machining center confirm that the proposed inner tap inspection system can be applied to the batch process of simultaneous inspection after tapping in the machining center.

• 대한토목학회논문집
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• 제34권4호
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• pp.1043-1052
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• 2014

이 연구는 마제형 원호 아치의 면내 저유진동에 관한 연구이다. 마제형 아치의 면내 자유진동을 지배하는 연립 상미분방정식을 곡률중심 및 접선 방향의 변위에 대하여 유도하였다. 특히 지배미분방정식은 반원보다 큰 중심각을 갖는 마제형 아치에 적용하기 위하여 각좌표보다는 곡선거리 좌표에 관한 미분방정식으로 유도하였다. 미분방정식을 수치해석하여 고유진동수와 진동형을 산출하였다. 변수연구를 통하여 회전관성, 세장비, 곡선길이비가 무차원 고유진동수에 미치는 영향을 분석하였다.

• Smart Structures and Systems
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• 제14권1호
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• pp.55-70
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• 2014

The paper presents a multi-objective optimization strategy for a multi-type sensor placement for Structural Health Monitoring (SHM) of long span bridges. The problem is formulated for simultaneous placement of strain sensors and accelerometers (heterogeneous network) based on application demands for SHM system. Modal Identification (MI) and Accurate Mode Shape Expansion (AMSE) were chosen as the application demands for SHM. The optimization problem is solved through the use of integer Genetic Algorithm (GA) to maximize a common metric to ensure adequate MI and AMSE. The performance of the joint optimization problem solved by GA is compared with other established methods for homogenous sensor placement. The results indicate that the use of a multi-type sensor system can improve the quality of SHM. It has also been demonstrated that use of GA improves the overall quality of the sensor placement compared to other methods for optimization of sensor placement.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2006년도 학술대회
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• pp.187-190
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• 2006

In this paper, we describe a new 1/4 rate robust modulation techniques for Enhanced-x VSB system which is fully backward compatible with ATSC 8-VSB standard. 1/4 rate mode Enhanced-xVSB system provides broadcasters with a wide choice of trade-offs of data rate vs amount of robustness of enhanced data for pedestrian/mobile services. Lab test results of proposed Enhanced-xVSB 1/4 rate mode robust stream are a significantly improved multipath as well as AWGN reception performance for Enhanced-xVSB receiver. We suggest an Enhanced-xVSB terrestrial broadcasting system for ATSC HDTV and pedestrian/portable TV simultaneous broadcasting service providing.

• Journal of Power Electronics
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• 제9권4호
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• pp.654-666
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• 2009

Direct torque control (DTC) of induction machines (IM) is a well-known strategy of these drives control which has a fast dynamic and a good tracking response. In this paper a nonlinear DTC of speed sensorless IM drives is presented which is based on input-output feedback linearization control theory. The IM model includes iron losses using a speed dependent shunt resistance which is determined through some effective experiments. A stator flux vector is estimated through a simple integrator based on stator voltage equations in the stationary frame. A novel method is introduced for DC offset compensation which is a major problem of AC machines, especially at low speeds. Rotor speed is also determined using a rotor flux sliding-mode (SM) observer which is capable of rotor flux space vector and rotor speed simultaneous estimation. In addition, stator and rotor resistances are estimated using a simple but effective recursive least squares (RLS) method combined with the so-called SM observer. The proposed control idea is experimentally implemented in real time using a FPGA board synchronized with a personal computer (PC). Simulation and experimental results are presented to show the capability and validity of the proposed control method.

• 한국통신학회논문지
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• 제37A권12호
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• pp.1133-1139
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• 2012

본 논문에서는 연계 빔형성과 비연계 빔형성 방법이 동시에 가능한 하이브리드 모드 빔형성 (HMB) 방법을 제안한다. HMB는 점근적으로 합 전송 증가율에 있어서 최적의 빔형성 방법임을 증명한다. 다양한 모의 실험을 통해서 HMB는 대칭 간섭 채널 환경에서 연계 빔형성 방법과 거의 동일한 성능을 달성함을 보인다. 또한, 보다 현실적인 비대칭적 간섭 채널 환경에서는 비대칭 채널 환경에서 연계 빔형성의 전력 비효율성으로 인한 성능의 저하를 갖지만, 연계 빔형성 방법보다는 우수한 성능을 갖는다는 것을 보인다.

• Mass Spectrometry Letters
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• 제13권4호
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• pp.158-165
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• 2022

Many therapeutic class drugs such as beta-blocker, corticosteroids, NSAIDs, etc are prohibited substances in the horse racing industry. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology makes it possible to isolate drugs from interference, enables various drug analyses in complex biological samples due to its sensitive sensitivity, and has been successfully applied to doping control. In this paper, we describe a rapid and sensitive method based on solid-phase extraction (SPE) using solid phase cartridge and LC-MS/MS to screen for different class's 35 drug targets in equine plasma. Plasma samples were pretreated by SPE with the NEXUS cartridge consisted non-polar carbon resin and minimum buffer solvent. Chromatographic separation of the analytes was performed on ACQUITY HSS C18 column (2.1 × 150 mm, 1.8 ㎛). The elution gradient was conducted with 5 mM ammonium formate (pH 3.0) in distilled water and 0.1% formic acid in acetonitrile at a flow rate of 0.25 mL/min. The selected reaction monitoring (SRM) mode was used for drug screening with multiple transitions in the positive ionization mode. The specificity, limit of detection, recovery, and stability was evaluated for validation. The method was found to be sensitive and reproducible for drug screening. The method was applied to plasma sample analysis for the proficiency test from the Association of Racing Chemist.

• ETRI Journal
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• 제45권2호
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• pp.254-266
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• 2023

This paper investigates the effect of hardware impairments (HIs) and imperfect channel state information (ICSI) on a SWIPT-assisted adaptive nonorthogonal multiple access (NOMA)/orthogonal multiple access (OMA) system over independent and nonidentical Rayleigh fading channels. In the NOMA mode, the energy-constrained near users act as a relay to improve the performance for the far users. The OMA transmission mode is adopted to avoid a complete outage when NOMA is infeasible. The best user selection scheme is considered to maximize the energy harvested and avoid error propagation. To characterize the performance of the proposed systems, closed-form and asymptotic expressions of the outage probability for both near and far users are studied. Moreover, exact and approximate expressions of the ergodic rate for near and far users are investigated. Simulation results are provided to verify our theoretical analysis and confirm the superiority of the proposed NOMA/OMA scheme in comparison with the conventional NOMA and OMA protocol with/without HIs and ICSI.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권2호
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• pp.128-133
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• 2008

Phase-change random access memory (PRAM) chip cell phase of amorphous state is rapidly changed to crystal state above 160 Celsius degree within several seconds during Infrared (IR) reflow. Thus, on-board programming method is considered for PRAM chip programming. We demonstrated the functional 512Mb PRAM with 90nm technology using several novel core circuits, such as metal-2 line based global row decoding scheme, PN-diode cells based BL discharge (BLDIS) scheme, and PMOS switch based column decoding scheme. The reverse-state standby current of each PRAM cell is near 10 pA range. The total leak current of 512Mb PRAM chip in standby mode on discharging state can be more than 5 mA. Thus in the proposed BLDIS control, all bitlines (BLs) are in floating state in standby mode, then in active mode, the activated BLs are discharged to low level in the early timing of the active period by the short pulse BLDIS control timing operation. In the conventional sense amplifier, the simultaneous switching activation timing operation invokes the large coupling noise between the VSAREF node and the inner amplification nodes of the sense amplifiers. The coupling noise at VSAREF degrades the sensing voltage margin of the conventional sense amplifier. The merit of the proposed sense amplifier is almost removing the coupling noise at VSAREF from sharing with other sense amplifiers.