• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.75-84
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• 2013

In this study, the patterns and characteristics according to gait cycle were analyzed using to EMG signals during walking, and analyzed in the time domain and frequency domain. The experiments was performed divide to level-ground walking and stair walking, and gait cycle was analysis by stance and swing. In the sagittal plane by using the tilt sensor measures the angle of the lower leg, and EMG was measured from the quadriceps and biceps femoris. The tilt of the lower leg was showed the biggest tilt at HS, and showed lowest value at TO. All in walking according to the gait cycle IEMG showed a specific pattern, and is expected useful to determine the gait cycle and kind. In the frequency domain analysis was using STFT on able to frequency analysis according to time, and using the tilt sensor was identify gait cycle. We analyzed also spectrum of the results of the STFT in all gait types, and recognized that stance had broad bandwidth than that of swing. Through this study, it was confirmed the possibility of judgment and analysis of the gait cycle using EMG and the tilt in the sagittal plane of the lower leg. When used it, can improve the quality of life of amputation patients

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.11
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• pp.51-62
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• 2003

This paper presents a novel survivor memeory management and decoding techniques with sequential backward state transition control in the trace back Viterbi decoder. The Viterbi algorithm is an maximum likelihood decoding scheme to estimate the likelihood of encoder state for channel error detection and correction. This scheme is applied to a broad range of digital communication such as intersymbol interference removing and channel equalization. In order to achieve the area-efficiency VLSI chip design with high throughput in the Viterbi decoder in which recursive operation is implied, more research is required to obtain a simple systematic parallel ACS architecture and surviver memory management. As a method of solution to the problem, this paper addresses a progressive decoding algorithm with sequential backward state transition control in the trace back Viterbi decoder. Compared to the conventional trace back decoding techniques, the required total memory can be greatly reduced in the proposed method. Furthermore, the proposed method can be implemented with a simple pipelined structure with systolic array type architecture. The implementation of the peripheral logic circuit for the control of memory access is not required, and memory access bandwidth can be reduced Therefore, the proposed method has characteristics of high area-efficiency and low power consumption with high throughput. Finally, the examples of decoding results for the received data with channel noise and application result are provided to evaluate the efficiency of the proposed method.

• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.347-355
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• 2002

We have constructed a high efficiency and broad tunable cw Ti:sapphire laser with a four-mirror symmetric Z-type laser cavity to increase the laser usability. From theoretical analyses and experimental data for a symmetric Z-type laser cavity containing a Kerr medium, the cavity mode size and the Kerr-lens mode-locking (KLM) strength for KLM lasers can be confirmed as function of the position in the cavity, the intracavity laser power, and the stability parameter. As a result, the slope efficiency and the maximum average output power of cw Ti:sapphire laser at 5 W pumping power of Ar-ion laser were 31.3% and 1420 ㎽ respectively. The tunablility was ranged from 730 ㎚ to 908 ㎚ with average output power above 700 ㎽. We obtained the KLM operation easily by self-aperturing effect in the Kerr medium and the slope efficiency and the maximum average output power of KLM Ti:sapphire laser was 16% and 550 ㎽ respectively. The spectral bandwidth was 33 ㎚ at the center wavelength of 807 ㎚ and the pulse width was 27 fs with a repetition rate of 82 ㎒.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.1032-1032
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• 2001

Artificial Neural Network (ANN) calibration techniques have been used commercially for agricultural applications since the mid-nineties. Global models, based on transmission data from 850 to 1050 nm, are used routinely to measure protein and moisture in wheat and barley and also moisture in triticale, rye, and oats. These models are currently used commercially in approx. 15 countries throughout the world. Results concerning earlier European ANN models are being published elsewhere. Some of the findings from that study will be discussed here. ANN models have also been developed for coarsely ground samples of compound feed and feed ingredients, again measured in transmission mode from 850 to 1050 nm. The performance of models for pig- and poultry feed will be discussed briefly. These models were developed from a very large data set (more than 20,000 records), and cover a very broad range of finished products. The prediction curves are linear over the entire range for protein, fat moisture, fibre, and starch (measured only on poultry feed), and accuracy is in line with the performance of smaller models based on Partial Least Squares (PLS). A simple bias adjustment is sufficient for calibration transfer across instruments. Recently, we have investigated the possible use of ANN for a different type of NIR spectrometer, based on reflectance data from 1100 to 2500 nm. In one study, based on data for protein, fat, and moisture measured on unground compound feed samples, dedicated ANN models for specific product classes (cattle feed, pig feed, broiler feed, and layers feed) gave moderately better Standard Errors of Prediction (SEP) compared to modified PLS (MPLS). However, if the four product classes were combined into one general calibration model, the performance of the ANN model deteriorated only slightly compared to the class-specific models, while the SEP values for the MPLS predictions doubled. Brix value in molasses is a measure of sugar content. Even with a huge dataset, PLS models were not sufficiently accurate for commercial use. In contrast an ANN model based on the same data improved the accuracy considerably and straightened out non-linearity in the prediction plot. The work of Mr. David Funk (GIPSA, U. S. Department of Agriculture) who has studied the influence of various types of spectral distortions on ANN- and PLS models, thereby providing comparative information on the robustness of these models towards instrument differences, will be discussed. This study was based on data from different classes of North American wheat measured in transmission from 850 to 1050 nm. The distortions studied included the effect of absorbance offset pathlength variation, presence of stray light bandwidth, and wavelength stretch and offset (either individually or combined). It was shown that a global ANN model was much less sensitive to most perturbations than class-specific GIPSA PLS calibrations. It is concluded that ANN models based on large data sets offer substantial advantages over PLS models with respect to accuracy, range of materials that can be handled by a single calibration, stability, transferability, and sensitivity to perturbations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1071-1078
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• 2003

In this paper, the planar, compact, and broadband phased array antenna system for IMT-2000 applications has been investigated. Two methods far designing a low-cost and low-complex beam-farming network are proposed. First, a new compact and broadband phase shifter with continuously controlled phase bits is designed by using parallel coupled lines. Second, its equivalent phase delay line is suggested to be capable of replacing the complex phase shifter with a reference phase bit on a phased array antenna. For the purpose of achieving the broadband system, in addition to the broadband phase shifter, a wide-slot antenna with a ground reflector is utilized as an element antenna. Therefore, the phased array antenna system has achieved compact size, broad bandwidth, and wide steering angle, although it has low complexity and low fabrication cost. The 3${\times}$1 phased array antenna system has a compact size of 1.6 λ${\times}$ l.6 λ, which is the sufficient ground plane of the wide-slot antenna. Experimental results present that the S$\_$11/ has less than 15 dB within the band and its radiation patterns on an E-plane have the capability of steering an antenna beam from -29$^{\circ}$to +30$^{\circ}$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.7
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• pp.778-784
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• 2008

In this paper, a chip antenna using multi-layer configuration for multi-band operation, such as GSM, DCS, pcs, WCDMA, and Mobile WiMAX for 2.3 GHz is proposed. This proposed antenna is a PIFA structure with multi-layer configuration fabricated on R04003 substrate(${\varepsilon}_r=3.4$) and its size is $22{\times}5.5{\times}4.0\;mm^3$. Multi-layer structure can effectively reduce the size of an antenna from a reuse of air-space and can achieve broad bandwidth due to decrement of parallel capacitances from the insertion air-gap to the middle layer. The proposed antenna has a broadband operation by the high order resonance modes and the resonance at the top layer. The measured bandwidths with over 45 % radiation efficiency are 80 MHz($880{\sim}960\;MHz$) at the lower band and 690 MHz($1,710{\sim}2,400\;MHz$) at the higher band.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.881-890
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• 2005

Over for the past 10 years, the increase in geometric progression for the internet traffic, has allowed the IP protocol framework to be the most important network technology. In addition, the internet service is being developed as a service mode differentiated, aiming to support the new-mode real-time multimedia services such as internet phone, video conference, cyber reality, and internet game, focusing on offering a latest service. These days, aiming to solve the need for broad bandwidth along with guaranteeing QoS, the WDM technology of offering multiple gigabit wavelengths is emerging as the core technology of next-generation optical internet backbone network. In the next-generation optical internet backbone network based on WDM, the QoS framework is one of fore subjects aiming to offer a service of guaranteeing QoS This study analyzes the requirements of performance related to QoS framework in IP Subnet and in WDM optical backbone network, and suggests optical QoS service framework differentiated. in order to guarantee end-to-end QoS through the next-generation optical internet backbone network, using GMPLS control protocol.

• The KIPS Transactions:PartC
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• v.11C no.1
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• pp.141-148
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• 2004

Recently, the demand of broadband communications such as high-speed internet, HDTV, 3D-HDTV and ATM backbone network has been increased drastically. For transmitting the broad-bandwidth data using wireless network, it is needed to use ka-band frequency. However, the use of this ka-band frequency is seriously affected to the received data performance by rain fading and atmospheric propagation loss at the Ka-band satellite communication link. So, we need adaptive MODEM to endure the degraded performance by channel environment. In this paper, we will present the structure and design of the 155Mbps adaptive Modem adaptively compensated against channel environment. In order to compensate the rain attenuation over the ka-band wireless channel link, the adaptive coding schemes with variable coding rates and the multiple modulation schemes such as trellis coded 8-PSK, QPSK, and BPSK are adopted. And the blind demodulation scheme is proposed to demodulate without Information of modulation mode at the multi-mode demodulator, and the fast phase ambiguity resolving scheme is proposed. The design and simulation results of adaptive Modem by SPW model are provided. This 155Mbps adaptive MODEM was designed and implemented by single ASIC chip with the $0.25\mu{m}$ CMOS standard cell technology and 950 thousand gates.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.9
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• pp.1248-1256
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• 1993

The propagation and delay properties in opical fiber are particularly attractive because digital signal processing and conventional analog signal processing techniques such as those using surface acoustic wave devices are limited In their usefulness for signal bandwidth exceeding one or two GHz, although they are very effective at lower frequencies. Since an accurate, low loss and short time delay elements can be obtained by using such an optical fiber, optical signal precessing has attracted much attention for high speed and broad-band signal precessing in particular channel separation filtering for optical FDM signals. In this paper, we consider a coherent optical lattice filter, which uses coherent light sources and consists of directional couplers and optical fiber delay elemnts. The optical fiber fitters are more restricted than the usual digital filters. The reasons are as follows. 1) the coupling coefficients of directional couplers are restricted to the number between 0 and 1. 2) optical signal E(complex amplitude) is divided into J If-$\boxUl$ and J L/7$\div$$\boxUl$ at the directional coupler. Considering these restrictions and in this case all the coupling coefficients of summing and branching elements are set to be equal, we have given design formulae for optical lattice filter, which make the best use of optical signal energy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.678-685
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• 2013

In this paper, we propose a design of dual-band patch antennas for Global Positioning System(GPS) applications, and the designed antenna is used as an individual element of GPS arrays. A low distortion and a high isolation of the array are achieved by adjusting rotating angles of each array element. The antenna consists of two radiating patches that operate in the GPS $L_1$ and $L_2$ bands, and the two ports feeding network with a hybrid chip coupler is adopted to achieve a broad circular polarization(CP) bandwidth. The rotating angles of each antenna element are varied with four directions(${\phi}=0^{\circ}$, ${\phi}=90^{\circ}$, ${\phi}=180^{\circ}$, ${\phi}=270^{\circ}$) in order to minimize the pattern distortion and maximize the isolation among array elements. The measurement shows bore-sight gains of 0.3 dBic($L_1$) and -1.0 dBic($L_2$) for the center element. Bore-sight gains of 1.6 dBic($L_1$) and 1.0 dBic($L_2$) are observed for the edge element. This results demonstrate that the proposed antenna is suitable for GPS array applications.