• Journal of Korean Society for Atmospheric Environment
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• v.17 no.5
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• pp.385-393
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• 2001

We have developed a Differential Absortion LIDAR (DIAL) method for the measurement of lower tropospheric ozone concentration. We used two laser beams from quadrupled Nd:YAG (266 nm) for the resonance wavelength and dye lasers (299.5 nm) for non -resonance wavelength. Aerosol extinction coefficients in the lower troposphere was computed by both Klett and Slope methods. To correct the SIN (Signal -Induced Noise) effect caused by photo detector, we subtracted a new-fitted baseline on the background part of a LIDAR signal, after the subtraction of the DC level. This is because SIN can be treated as an exponentially decaying tail. Using theme results, ozone profiles were obtained approximately 2km at daytime and 3km at nighttime. We compared the results derided by the Slope method with those measured by UV spectrometer. The computed results are in mostly good agreement with experimental results. In the measurement of the vertical layer, we observed the variation of the ozone profiles around the top mixed layer.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.113.3-113
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• 2001

In this paper, we have designed the VHDL module of DS/SS QPSK wireless modem processor for digital data communication. The spread spectrum method is used for modern processor, because this method guarantees good frequency efficiency and higher security. Also, it guarantees good performance in digital communication system under multi-path interferences. The differential encoder and decoder are used for simple circuit composition in the signal detection. For the synchronization of receiver, matched filter and power detector are used. And the IF modulation/demodulation of QPSK method is used in the digital level. The transmitter of VHDL modem processor consists of differential encoder, PN code generator, and QPSK ...

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1996.09a
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• pp.31-36
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• 1996

It is important to measure the vehicle flow in controlling the traffic system. This report deals with a traffic flow measurement system using the differential spatial filters. This system can measure the velocity the length and height profile of the vehicle. The detector is located above the traffic lane. This provides the system with the following advantages : one is that each lane can be monitored without an influence of the other lanes the other is that the system construction is simple and can be set easily.

• Proceedings of the Korea Contents Association Conference
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• 2003.11a
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• pp.281-284
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• 2003

In this study, we have proposed the method of moving area detection as the preprocessing step of moving object tracking system. First, we catch the two frames which are different at time in image sequence. We obtain the moving area by using their binary differential image. In differential image, the object area of previous and current frame is present. In the tracking system, the background is changed by camera motion. So, in this case we have to decide which moving area of object is current at time. We obtain the binary edge image of current frame by applying a threshold to the output of an edge detector. Then we performed logical AND operation between the edge image and differential image. As a result of this work moving area of object can be detected.

• Nuclear Engineering and Technology
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• v.4 no.4
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• pp.280-293
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• 1972

The differential fast neutron spectra above 0.5 Mev at particular spatial positions in tile reactor(TRIGA MARK-II) core has been determined experimentally using several threshold activation detectors. The series expansion technique utilizing the concept of least squares optimization was used to obtain an approximate solution to the set of integral equations which are defined by the experimentally determined activation data. The influence of use of different weighting functions in the solution was analyzed in each measurement. To carry out the necessary mathematical calculations, a computer code for the UNIVAC 1106 digital computer has been prepared. Good agreement was achieved between the differential fast neutron spectra determined in this work and the computed flux determined independently using space-independent multigroup transport theory.

• Journal of Advanced Navigation Technology
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• v.15 no.5
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• pp.833-838
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• 2011

X-ray device used in the diagnosis has made possible to have more effective and accurate diagnosis, powered by the development of various devices. Based on this, X-ray device has become the most basic and essential diagnostic equipment in clinical medicine. At present, in the image acquisition field using X-ray, the use of Digital radiography which is useful in the acquisition time reduction and transfer of images and is possible to have the dose reduction has expanded. With the structure using one detector, this DR device has disadvantages in that it needs structural changes unlike existing X-ray and the detector should be moved to the desired position depending on the shooting location. Therefore, in this study, using BLDC(Brushless direct current) motor and PID(Proportional integral differential) control method, the automatic control system of 3-axis which is upward and downward, left and right and rotation of detector where having the most movement in DR was designed and produced and its performance was evaluated.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.31-37
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• 2009

This paper presents an efficient frame synchronization strategy with the identification of modulation type for Digital Video Broadcasting-Satellite second generation (DVB-S2). To detect the Start Of Frame (SOF) and identify a modulation mode at low SNR, we propose a new correlator structure and a low complexity Automatic Gain Controller (AGC). The proposed frame synchronization architecture can reduce about 93% multipliers and 89% adders compared with the direct implementation of the Differential - Generalized Post Detection Integration (D-GPDI) algorithm which is very complex and the proposed a low complexity AGC consists of only 5 multipliers and 3 adders. The proposed architecture has been thoroughly verified on the Xilinx Virtex II FPGA board.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.97-103
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• 2019

In this paper, we designed and fabricated a receiving modem that can be applied to guided weapons can change real-time targets with little effect of fading. The designed modem consists of synchronous detector, timing error estimator, timing recovery, differential decoder and viterbi decoder, and it's implemented in FPGA so that it can be redesigned and modified according to requirements. The modem board was directly converted from IF frequency to baseband and converted into digital data through ADC. It is confirmed that it is applicable to the guided weapons that changing real-time targets through simulations, measurements and test.

• Journal of the Society of Disaster Information
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• v.11 no.2
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• pp.203-209
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• 2015

The heat detector detects heat in the fire and is an important core element of the automatic fire alarm system used generally for every fire prevention objects. The heat detector is distinguished in spot type and spread type and in spot type, there are differential and thermistor types. These heat detectors give a great influence on the loss of people and property according to the sensitivity of response such as operation time and operation temperature in actual fire and in overseas people apply it for the development of products that can be operated in the early stage of fire including certification, quality management, and comparison standard by introducing response time index through the theory of heat balance that considers the heat loss and ventilation tests. In Korea, the response time index is introduced and used in the head of sprinkler products, but it is not applied to the heat detector at present. It is necessary to introduce the response time index that shows the sensitivity of response of the heat detector the installation standard for the heat detector that the response time index is applied should be different according to the fire weight, danger degree of fire, and shape of buildings. Through this study, it tries to help reduce lives and property of people through the swift warning by installing detectors suitable for the building structure.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.301-306
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• 2014

We proposed a new PCB-type 'common-mode current($I_c$) and differential-mode current($I_d$) detector' working for fast detection of $I_c$ and $I_d$ from the differential-mode signaling, with miniaturization effect and possibility of cheaper fabrication. In order to realize this device, we suggest a branch-line-coupler balun having a composite right- and left-handed(CRLH) one-layer microstrip phase-shifting line as compact as roughly ${\lambda}_g/14$. The presented balun obviously is different from the conventional bent-&-folded delay lines or slits on the ground for coupling the lines on the top and bottom dielectrics. As we connect the suggested balun output ports of the differential-mode signal lines via the through-port named U and coupled-port named L, $I_c$ and $I_d$ will appear at port ${\Delta}$ and port ${\Sigma}$ of the present device, in order. The validity of the design scheme is verified by the circuit-and numerical electromagnetic analyses, and the dispersion curve proving the metamaterial characteristics of the geometry. Besides, the examples of the $I_c$ and $I_d$ indicator are observed as the even and odd modes in differential-mode signal feeding. Also, the proposed device is shown to be very compact, compared with the conventional structure.