• 설비공학논문집
• /
• 제9권3호
• /
• pp.323-332
• /
• 1997

It was reported by some researchers that two-stage parallel-plate ESPs, commonly called electronic air cleaners, show decreasing behavior of collection efficiency as particle size decreases below about $0.03{\mu}m$. This phenomenon is attributed to partial particle charging characteristics, where some of incoming particles are not charged in the charging cell of 2-stage parallel-plate ESP. One way to improve the decreasing collection efficieny in that particle size range is to enforce particle charging quantity in the charging cell. In the present study, in order to do this a 2-wire series-type charging cell modified from a 1-wire normal-type one was suggested and investigated theoretically and experimentally concerning improvement of the collection efficiency. It was confirmed from the experimental and theoretical works that the collection efficiency was apparently improved.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
• /
• pp.444-447
• /
• 2004

A heart diagnosis system adopts hundreds of Superconducting Quantum Interface Device(SQUID) sensors for precision MCG(Magnetocardiogram) or MEG(Magnetoencephalogram) signal acquisitions. This system requires correct and real-time data acquisition from the sensors in a required sampling interval, i.e., 1 mili-second. This paper presents our hardware design and test results, to acquire data from 256 channel analog signal with 1-ksample/sec speed, using 12-bit 8-channel ADC devices, SPI interfaces, parallel interfaces, and 8-bit microprocessors. We chose to implement parallel data transfer between microprocessors as an effective way of achieving such data collection. Our result concludes that the data collection can be done in 250 ${\mu}sec$ time-interval.

• 한국의학물리학회:학술대회논문집
• /
• 한국의학물리학회 2002년도 Proceedings
• /
• pp.311-313
• /
• 2002

We are under development of a 3D PET scanner with depth of interaction (DOI) capable of high sensitivity and high resolution. In this scanner, a maximum data transfer rate of coincidence pair's event information is 10 Mcps and one event is a 64-bit data format. This maximum data transfer rate corresponds by 10 times a conventional PET scanner. A data acquisition system, which fulfills the specification of this scanner, is considered for parallel collection with banks including several coincidence units. Data transfer rate is improved by optimizing parameters of a message size, and so on.

• 설비공학논문집
• /
• 제6권3호
• /
• pp.237-246
• /
• 1994

Experimental data are reported for charging and collection of NaCl aerosols in the 0.03- to $0.2{\mu}m$-geometric-mean-diameter range in 2-stage parallel-plate electrostatic precipitators. The NaCl aerosols are generated with geometric standard deviation of about 1.74 and particle generation rate of about 10^9 particles/see by the constant output atomizer and injected into the air flow in the clean wind-tunnel. The 2-stage parallel-plate electrostatic precipitator installed in the test section of the wind-tunnel is operated with a positive corona discharge. The NaCl aerosols in the channel flow are sampled and transported to the aerosol particle number concentration measurement system by using the isoaxial sampling and transport system constructed based on the Okazaki and Willeke design. The aerosol particle number concentration measurement system measures the size distribution of submicrometer aerosols by an electrical mobility detection technique. It is confirmed from comparing the measured collection efficiencies in this study and the predicted ones by our previous theoretical analysis that the predicted collection efficiencies agree well with the experimental ones. It is also found from the comparison that below about $0.02{\mu}m$ all particles are not charged and the uncharged particles are not collected, and consequently 2-stage parallel-plate electrostatic precipitators are not suitable for that particle size range.

• 대한기계학회논문집
• /
• 제18권2호
• /
• pp.432-445
• /
• 1994

From a theoretical analysis point of view, the 2-stage precipitator is decomposed into two units: charging cell and collecting cell. Collection efficiency predictions of the two-stage parallel-plate electrostatic precipitator have been performed theoretically incorporating with the charging and the collecting cells. Particle trajectorise passing the charging cell have been modeled as a simple one. Particle charge distribution at the outlet of the charging cell is calculated through integration of the present unipolar combined charging rate along the entire particle trajectory, and average charge of particles at the outlet of the charging cell is obtained from the particle charge distribution. As for the collecting cell, the diminution of particle concentration along the longitudinal direction of the collecting cell is investigated considering the conventional Deutsch's theory and the laminar theory. One should note that the collection efficiency formula derived is based on monodisperse aerosols. It has been confirmed through the analysis that predictions of particle charge by applying White's unipolar diffusion charging theory overpredict actual cases in the continuum regime, while predictions by Fuch's unipolar diffusion charging theory indicate the reasonable result in the same regime. Theoretical predictions of collection efficiency are also compared with the available experimental results. Comparisons show that the experimental results are consistently located in the collection efficiency region bounded by the two limits, the Deutsch and the laminar collection efficiencies. Finally design parameters of the 2-stage electrostatic precipitator have been investigated systematically through the one-variable-at-a-time method in terms of collection efficiency. Applied voltages on the corona wire of the charging cell and the plate of the collecting cell, and the average air velocity have been selected as the design parameters.

• 대한환경공학회지
• /
• 제39권6호
• /
• pp.371-376
• /
• 2017

선회류 약화기(vortex finder)의 구조와 치수를 변형한 7종류의 cyclone을 제작해 PM-10 집진효율 자료를 도출하였고 CFD 분석을 통한 사이클론 입구 속도를 계산하였다. 입구속도는 normal, P, A type 사이클론의 경우 15.48 m/sec, 16.03 m/sec 그리고 15.90 m/sec로 계산되었고 PM-10 집진효율 실험결과는 P tpye과 A type의 사이클론의 경우 normal 사이클론에 비해 4%와 7%의 집진효율이 증가하였다. 또한 평행부의 길이가 증가함에 따라 PM-10의 집진효율은 증가하다 감소하여 집진효율을 최대화 할 수 있는 길이가 존재함을 보여주었다.

• 제어로봇시스템학회논문지
• /
• 제10권7호
• /
• pp.590-596
• /
• 2004

A passivity-based dynamic output feedback controller design is considered for a finite collection of non-square linear systems. Design of a single controller for a set of plants i.e. simultaneous stabilization is an important issue in the area of robust control design. We first determine a squaring gain matrix and an additional dynamics that is connected to the systems in a feedforward way, then a static passivating control law is designed. Consequently, the actual feedback controller will be the static control law combined with the feedforward dynamics. A necessary and sufficient condition for the existence of the parallel feedforward compensator is given by the static output feedback formulation. In contrast to the previous result [1], a technical condition for constructing the parallel feedforward compensator is removed by proposing a new type of the parallel compensator.

• International Journal of Internet, Broadcasting and Communication
• /
• 제4권1호
• /
• pp.13-17
• /
• 2012

Indexing allows converting raw document collection into easily searchable representation. Web searching by Google or Yahoo provides subsecond response time which is made possible by efficient indexing of web-pages over the entire Web. Indexing process gets challenging when the scale gets bigger. Parallel techniques, such as MapReduce framework can assist in efficient large-scale indexing process. In this paper we propose PDFindexer, system for indexing scientific papers in PDF using MapReduce programming model. Unlike Web search engines, our target domain is scientific papers, which has pre-defined structure, such as title, abstract, sections, references. Our proposed system enables parsing scientific papers in PDF recreating their structure and performing efficient distributed indexing with MapReduce framework in a cluster of nodes. We provide the overview of the system, their components and interactions among them. We discuss some issues related with the design of the system and usage of MapReduce in parsing and indexing of large document collection.

• 대한설비공학회지:설비저널
• /
• 제6권4호
• /
• pp.255-261
• /
• 1977

This study was concerned with the performance of solar air heater using parallel channels. Heat transmission model was developed and fabricated to increase the economic feasibility for solar heating system by using the cheap zinc plate. The prformance was discussed as a function of mass flow rate, and plate, inlet and outlet temperatures. Experimental results show that heat transmission model is sufficient for the analysis of thermal characteristics of air heater and collection efficiency is better than the domestic water heater, as the range 32-49 percent. Collection efficiency in the 2 layers of glass cover is better than that in 1 layer, so it is considered better to use the 2 layers of glass cover during the cold winter season in Korea.

• 한국산업융합학회 논문집
• /
• 제23권1호
• /
• pp.101-106
• /
• 2020

Along with dust collection efficiency, pressure loss is a very important cyclone operation factor. A severe rise in pressure loss causes the problem of cost. To solve the problem, the method connecting axial-vane type cyclones in parallel is suggested recently. The axial vane type cyclone dust collector applied in this study is a small portable type. Multiple cyclones are installed in a round type. The basic performance test on the axial vane type cyclone dust collector was conducted. As a result, the cut size reduced along with a rise in the wind velocity of the cyclone dust collector inlet. According to the test on dust collection efficiency, the effect of dust collection began to appear in the range of 3㎛ and dust collection efficiency was greatly improved at 5 ㎛. The noise of the cyclone dust collector well met the fan sound power level of KSB 6361.