• Nuclear Engineering and Technology
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• 제27권5호
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• pp.784-791
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• 1995

방사선계측에서는 방사선검출기(detector)로부터 나오는 pulse를 처리하는 데 있어서 pulse의 counting 손실이 발생한다. 이 손실을 최소화하거나 보상하기 위한 여러가지 방법들이 제시되어 왔으나, 아직도 절대적인 해답이 확립되지 않은 실정이다. 본 연구에서는 기 제시된 보상알고리즘들을 그 기능을 구현하는 전자회로와 함께 기술하고 특징을 분석하였다. 또한 본 연구를 통해 pulse의 counting손실을 보상하는 한가지 알고리즘 개선방향을 제시하였다.

• 한국산업보건학회지
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• 제18권3호
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• pp.189-203
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• 2008

Cylindrical bag filter system with pulse jet cleaning has been the most common device to control particle laden exhaust gas from the various industrial processes. But, it has many shortcomings due to particle reattachment and frequent bag rupture. In recent years, rectangular type bag filter system has been developed to overcome the problems associated with the cylindrical system. However, not many studies about the rectangular system were not done, compared to the cylindrical system. In this study, the optimum pulse jet cleaning conditions were thus tested by the series of experiments. The factors tested in this study are pulse distance, pulse pressure, pulse duration, the number of holes for pulsing and bag materials. A single bag ($1,500mmL{\times}50mmW{\times}300mmH$) system and a multi-bags (3 bags in a row) were tested separately. The highest removal efficiency with a single bag system was found at the conditions with pulse distance of 10cm, pulse pressure of $3kg/cm^2$, pulse duration of 0.3s, pulse jet number of 6 and Polyester bag. With the multi-bags system, the best cleaning conditions were found at the bag interval of 20cm with the simultaneous pulsing and the bag interval of 15cm with the serial pulsing.

• 치과방사선
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• 제20권2호
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• pp.187-198
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• 1990

Examinations of the temporomandibular joints were performed on a 1.5 Tesla magnetic resonance (MR) system. An MR surface receiver coil 3 inch in diameter was placed on plastic frame, the patient's head being placed in the frame so that the coil was pressed against the temporal region. In taking advantage of the magnetic resonance imaging that has been studied briskly till now, author obtained the images of parasagittal and paracoronal planes about the temporomandibular joint by using MPGR (Multi-Planar Gradient Recalled), GRASS (Gradient Recalled Acquisition in the Steady State), and CSMEMP (Contiguous Slice Multiple Echo, Multi-Planar), that differ from the Spin Echo pulse sequence which the previous authors used. Five subjects with no symptoms of temporomandibular joint pain and dysfunction were studied. The plane images obtained by these methods were compared with those by Spin Echo pulse sequence. The results were as follows: 1. The optimal repetition times (TR) and echo times (TE) for T.M.J. image were; a. 400 msec and 18 msec in PMGR pulse sequence. b. 40 msec and 12 msec in GRASS pulse sequence. c. 700 msec and 30 msec in CSMEMP pulse sequence. d. 500 msec and 20 msec in Spin Echo pulse sequence. 2. When the MPGR pulse sequence was using, T2-weighted image was obtained in very short time. On the image of the paracoronal plane by GRASS pulse sequence, meniscus showed the moderate signal intensity, and the meniscus and its anteromedial, posterolateral attachments were observed definitely with gray color. 4. The signal intensity of Spin Echo pulse sequence was equal to that of CSMEMP pulse sequence, but the image by CSMEMP pulse sequence showed relatively lower level in its resolution.

• 한국위성정보통신학회논문지
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• 제8권4호
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• pp.159-163
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• 2013

본 논문에서는 전자정보시스템을 사용하여 펄스 레이더에서 송신되는 다단 스태거(stagger) PRI(pulse repetition interval) 신호를 정확하게 분석하는 새로운 방법을 제안하였다. 기존의 PRI 신호분석 방법은 레이더 펄스신호 하드웨어 추적기(tracker)를 이용하여 신호도착시간(time of arrival)의 1차 차분을 이용하여 PRI 패턴을 분석하였으나 본 논문에서는 펄스신호들의 도착시간(TOA)의 1차 차분, 2차 차분과 PRI 히스토그램을 이용하여 다단 스태거 PRI 신호를 분석하는 알고리즘을 개발하였다. 본 연구는 펄스 레이더의 다단 스태거 PRI 신호식별에 매우 유용하게 사용할 수 있을 것으로 판단된다.

• 대한전기학회논문지
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• 제36권11호
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• pp.806-812
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• 1987

The ozone generation characteristics are reported for a sawtooth disk to cylinger geometry using positive and negative pulse corona. A series of parametric studies was carried out to obtain optimum values for the pulse repetition frequency as well as the shape and dimensions of the discharge disk and the discharge spacing. Two types of ozonizers were studied: the single disk and the multi-disk. The results of the single disk ozonizer showed that positive corona produced a singificantly higher ozone yield than negative(7ppm/peak watt or 3.5 times larger). However the negative corona produced a much more controllable output which enabled the ozone generation to be directly controlled by adjusting the value of the peak pulse voltage. This results showed that the single disk ozonizer is ideally suited for applications requiring very small controlled quantities of ozone whereas the multi-disk unit can be designed to provide varying outputs depending upon the number of disk electrodes used.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1852-1854
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• 2003

In manufacturing processes, various and suitable pulse shapes are required for the purpose of material processing. In order to make various pulse shapes with variable pulse length and high duty cycle, We have fabricated the power supply consisting 6 SCRs and the Pulse Forming Network(PFN) with the precise delay time control. So our control system has three switching circuits, 3 mesh PFN, and simmer circuit. In addition, we have designed and fabricated the PIC one-chip microprocessor(16F877) to control the delay time of sequential switching.

• 한국전기전자재료학회논문지
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• 제25권6호
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• pp.409-413
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• 2012

In this study, a substrate-bias assisted 2-step pulse programming method is proposed for realizing 4-bit/1-cell operation of the SONOS memory. The programming voltage and time are considerably reduced by this programming method than a gate-bias assisted 2-step pulse programming method and CHEI method. It is confirmed that the difference of 4-states in the threshold voltage is maintained to more than 0.5 V at least for 10-year for the multi-level characteristics.

• Journal of Power Electronics
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• 제12권5호
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• pp.787-799
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• 2012

Real and reactive power flows on a transmission line interact inherently. This situation degrades power flow controller performance when independent real and reactive power flow regulation is required. In this study, a quasi multi-pulse interline power flow controller (IPFC), consisting of eight six-pulse voltage source converters (VSC) switched at the fundamental frequency is proposed to control real and reactive power flows dynamically on a transmission line in response to a sequence of set-point changes formed by unit-step reference values. It is shown that the proposed hybrid fuzzy-PI commanded IPFC shows better decoupling performance than the parameter optimized PI controllers with analytically calculated feed-forward gains for decoupling. Comparative simulation studies are carried out on a 4-machine 4-bus test power system through a number of case studies. While only the fuzzy inference of the proposed control scheme has been modeled in MATLAB, the power system, converter power circuit, control and calculation blocks have been simulated in PSCAD/EMTDC by interfacing these two packages on-line.

• Journal of Power Electronics
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• 제18권1호
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• pp.266-276
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• 2018

This paper presents a new step-up and step-down multi-pulse auto-transformer rectifier unit (ATRU) topology. This structure can achieve a wide range of output voltages, which solves the problem of auto-transformer output voltage being difficult to regulate. Adding middle taps to the primary winding and reasonably setting the number of auto-transformer windings, constituted two groups of three-phase output voltages with a $30^{\circ}$ phase difference. Multi-pulse output DC voltage is obtained after a three-phase output voltage across two rectifier bridges and inter-phase reactor. Thus, the output DC voltage is related to the number and configuration of the auto-transformer winding. In this paper, the relationship between the voltage ratio of the auto-transformer and the ratio of winding, input current and auto-transformer kilovoltampere rating are deduced and validated by simulations. On this basis, the output voltage range is optimized. An experiment on two different voltage ratio principle prototypes was carried out to verify the correctness of the analysis design.

• 한국통신학회논문지
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• 제28권12C호
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• pp.1192-1199
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• 2003

본 논문에서는 다중경로 채널 환경에서 펄스 반복 빈도 (pulse repetition frequency, PRF)와 슬롯 시간이 UWB (ultra wide band) 무선 통신 시스템의 데이터 전송율 (throughput) 성능에 미치는 영향을 조사하고 이를 기반하여 유효 데이터 전송율이 최대화되도록 하는 PRF와 슬롯 시간을 이용한 전송율 제어를 제안한다. 최근에 UWB 시스템이 갖고 있는 장점으로 인하여 근거리 고속 무선 데이터 전송과 관련하여 관심이 고조되고 있다. UWB 시스템에서는 데이터 전송율을 결정짓는 파라미터로는 펄스를 반복하는 펄스 반복 회수와 펄스간의 간격을 결정짓는 슬롯 시간을 들 수 있다. AWGN이 존재하는 다중경로 채널 하에 있는 UWB 시스템은 펄스간의 간섭(inter-pulse interference, IPI)과 잡음에 의하여 시스템 성능이 저하된다. UWB 시스템은 이 두 파라미터의 조정을 통하여 시스템의 성능을 유지 또는 개선할 수 있다. 본 논문에서는 두 파라미터의 변화가 다양한 채널 환경에서 데이터 전송율에 미치는 영향을 모의실험을 통하여 관측하고 이를 기반하여 설계된 가변 전송율을 사용하는 것이 비가변적인 방법에 비하여 유효 데이터 전송율 측면에서 우수함을 모의실험을 통하여 검증하였다.