• Title/Summary/Keyword: Circuits

Search Result 4,520, Processing Time 0.034 seconds

A 13b 100MS/s 0.70㎟ 45nm CMOS ADC for IF-Domain Signal Processing Systems (IF 대역 신호처리 시스템 응용을 위한 13비트 100MS/s 0.70㎟ 45nm CMOS ADC)

  • Park, Jun-Sang;An, Tai-Ji;Ahn, Gil-Cho;Lee, Mun-Kyo;Go, Min-Ho;Lee, Seung-Hoon
    • Journal of the Institute of Electronics and Information Engineers
    • /
    • v.53 no.3
    • /
    • pp.46-55
    • /
    • 2016
  • This work proposes a 13b 100MS/s 45nm CMOS ADC with a high dynamic performance for IF-domain high-speed signal processing systems based on a four-step pipeline architecture to optimize operating specifications. The SHA employs a wideband high-speed sampling network properly to process high-frequency input signals exceeding a sampling frequency. The SHA and MDACs adopt a two-stage amplifier with a gain-boosting technique to obtain the required high DC gain and the wide signal-swing range, while the amplifier and bias circuits use the same unit-size devices repeatedly to minimize device mismatch. Furthermore, a separate analog power supply voltage for on-chip current and voltage references minimizes performance degradation caused by the undesired noise and interference from adjacent functional blocks during high-speed operation. The proposed ADC occupies an active die area of $0.70mm^2$, based on various process-insensitive layout techniques to minimize the physical process imperfection effects. The prototype ADC in a 45nm CMOS demonstrates a measured DNL and INL within 0.77LSB and 1.57LSB, with a maximum SNDR and SFDR of 64.2dB and 78.4dB at 100MS/s, respectively. The ADC is implemented with long-channel devices rather than minimum channel-length devices available in this CMOS technology to process a wide input range of $2.0V_{PP}$ for the required system and to obtain a high dynamic performance at IF-domain input signal bands. The ADC consumes 425.0mW with a single analog voltage of 2.5V and two digital voltages of 2.5V and 1.1V.

An Analysis on the Suicide Concept, its Religious Circuit and Construction Way: Focused on the cases of the Korean Catholic and Protestant Churches (자살 관념의 종교적 회로와 구성 방식에 관한 분석: 한국 가톨릭교회와 개신교를 중심으로)

  • Park, Sang Un
    • The Critical Review of Religion and Culture
    • /
    • no.31
    • /
    • pp.255-287
    • /
    • 2017
  • This paper analyzes the religious circuit of suicidal concept based on verbal expression and ritual acts, which are found in the suicide discourse of Korean Catholic Church and Protestant Church. In the relationship of suicide and religion, it is easily overlooked the religious circuit and its construction that forms the concept of suicide among the religious laymen. It is assumed that the belief system of traditional religions prohibits suicide and the laymen accordingly construct a perception or concept of suicide along with this belief system. Various studies on this subject have proved it. However, in order to understand the religious way of constructing the concept of suicide on a personal level, it is necessary to pay attention to the religious environment in which the concepts and emotions of suicide circulate. The laymen do not passively and perfectly accept the finely established suicide concept provided by the doctrine or the theology. Rather, the laymen tend to collect the pieces of concept over the suicide that are drifting in the religious environment of his/her daily routine life and to make an concept of suicide in an incomplete form. We can find the unstable and imperfect traits of such a suicide concept through the experience of suicide survivors who have a religious background. For the suicide survivors with religious beliefs, they resist the formal doctrinal and theological provisions to suicide, or try to understand the notion of suicide in their own contexts. In terms of linguistic expressions and ritual acts relating to suicide, the attentions are differently directed in the public and the private domain among the religious groups. Considering on the high rates of suicide in Korean society, the Korean Catholic Churches are increasingly tolerant over the suicide and accept it in the public sphere. It is unlikely when comparing to the negative attitudes of the suicide in the past. However, such tolerance does not go beyond the doctrinal and ethical judgment that defines suicide as a serious sin. The once-committed lay believer's speech and gestures usually contain the various emotions, such as sadness, grief, anxiety, regretfulness, eagerness, and pain in the private spheres. The language and gestures with these emotions have been activated in the religious circuits of suicide, being extended to the religious apparatus for the person who died of suicide. In case of Protestantism, the institutional organizations, such as the particular denominations and the individual-churchism of the Korean Protestant Churches, and their own interpretations of the Bible have in the private sphere strongly effected on the linguistic expressions and the rituals related to the suicide. The religious-ethical judgment of the suicide is varied how the suicide is interpreted by the theologians and the pastors. And the ritual acts for healing the complex feelings and the psychological wounds of the suicide survivors are not actively explored and adopted yet. It makes harder to approach and heal the protestant followers since they emphasize the innermost belief and the salvation assurance faith.

Effects of Vibration Stimulation Therapy on Neglect of Stroke Patients (진동감각 자극치료가 뇌졸중 환자의 편측무시에 미치는 영향)

  • Jeon, So-Hyun
    • Journal of Society of Occupational Therapy for the Aged and Dementia
    • /
    • v.12 no.2
    • /
    • pp.87-95
    • /
    • 2018
  • Objective : Vibration stimulators are easier to obtain in clinical settings than other treatment tools, and it is advantageous that the arm activation training can be performed passively. Despite the following advantages, recent studies on vibration sense have not been activated yet. The purpose of this study was to investigate the effect of vibration sensation on the hands of the affected upper limb on unilateral reduction of stroke patients. Method : Patients with unilateral neglect due to stroke were enrolled in this study for about 3 weeks from October 19, 2018 to November 7, The research design used ABA design among the single-subject experimental research design, and a total of 18 circuits (4 baseline, 6 intervention, 3 baseline regression) were performed once a day on weekdays Respectively. MMES-K was used to select the subjects. Line bisection test (LBT), Albert's test and Star Cancellation Test (SCT) were used as unilateral neglect test. For the analysis, the baseline and intervention period measurements were visually analyzed using graphs and mean values were used. Result : All three evaluations showed that the number of errors missed during the training period was lower than the baseline period, and this decrease remained after training. The error was reduced by an average of $2{\pm}1.2$ omissions and an average omissions of $0.6{\pm}0.5$ omitting an average of $4.5{\pm}1$ omissions in the line break test. As a result of the Albert test, the average error decreased by $22.5{\pm}1.9$ omissions and $8{\pm}7.3$ omissions and $0.3{\pm}0.5$ omissions, respectively. In the star clearance test, the average error decreased from $26{\pm}4.6$ to $21.8{\pm}1.7$ and $20{\pm}0$, respectively. Conclusion : In this study, vibrotactile stimulation therapy showed a continuous effect on improving unilateral neglect. Based on these findings, further research should be conducted in order to improve objectivity in future studies. Further research on various arbitration methods that maximize the effect of intervention will be needed.

A Study on the twelve earthly branches' Yin Yang, Five elements, Six Qi, viscera combination, Mutual collision and Mutual combination. (십이지지(十二地支)의 음양(陰陽) 오행(五行) 육기(六氣) 장부(臟腑)의 배합(配合) 및 상충(相沖) 상합(相合)에 관한(關) 연구(硏究))

  • Kim, hung Joo;Jeon, yun ju;Yun, Chang-Yeol
    • Journal of Haehwa Medicine
    • /
    • v.27 no.1
    • /
    • pp.9-20
    • /
    • 2018
  • Objectives : Ten heavenly stems(10天干) and Twelve earthly branches(12地支) are symbols exposing change order in heaven and earth, and are a very important sign in studying oriental philosophy and oriental medicine. Especially, 10 heavenly stems(10天干) and 12 earthly branches(12地支) are indispensable for the study of Five Circuits And Six Qi(오운육기), and a deep study is needed. Methods : I have examined Yin Yang combination(음양배합), Five elements combination(오행배합), Six Qi 3Yin 3Yang combination(육기삼음삼양배합), viscera combination(장부배합), Mutual collision(상충), Six combination(육합), Three combination(삼합), etc. of 12 earthly branches(12지지) by referring to books such as "Yellow Emperor Internal Classic" ("黃帝內經") and "Principle of universe change" ("우주변화의 원리"). Results & Conclusions : Zi Yin Chen Wu Shen Xu(子 寅 辰 午 申 戌) become Yang(陽), Chou Mao Si Wei You Hai(丑 卯 巳 未 酉 亥) become Yin(陰), Zi Si Yin Mao Chen Si(子 丑 寅 卯 辰 巳) become Yang, and Wu Wei Shen You Xu Hai(午 未 申 酉 戌 亥) become Yin. Twelve earthly branches can be divided into five movements by its original meaning, where YinMao(인묘) is tree, SiWu(사오) is a fire, ShenYou(신유) is a gold, HaiZi(해자) is water, and ChenXuChouWei(진술축미) mediate in the middle of four movements So they become soil(土). SiHai(巳亥) is JueYin Wind Tree(궐음 풍목), ZiWu(子午) is ShaoYin Monarch Fire(소음 군화), ChouWei(丑未) is TaiYin Humid Soil(태음 습토), YinShen(寅申) is ShaoYang Ministerial Fire(소양 상화), MaoYou(卯酉) is YangMing Dry Gold(양명 조금), and ChenXu(辰戌) is TaiYang Cold Water(태양 한수). Viscera combination(장부배합) combines Zi(子) and Bile(膽), Chou(丑) and Liver(肝), Yin(寅) and Lung(肺), Mao(卯) and Large intestine(大腸), Chen(辰) and Stomach(胃), Si(巳) and Spleen(脾), Wu(午) and Heart(心), Wei(未) and Small intestine(小腸), Shen(申) and Bladder(膀胱), You(酉) and Kidney(腎), Xu(戌) and Pericardium(心包), Hai(亥) and Tri-energizer(三焦), Which means that the function of the viscera and channels is the most active at that time. Twelve earthly branches mutual collisions collide with Zi(子) and Wu(午), Chou(丑) and Wei(未), Yin(寅) and Shen(申), Mao(卯) and You(酉), Chen(辰) and Xu(戌), and Si(巳) and Hai(亥). The two colliding earthly branches are on opposite sides, facing each other and restricting each other by the relation of Yin-Yin and Yang-Yang it rejects each other so a collision occurs. Six Correspondences(六合) coincide with Zi(子) and Chou(丑), Yin(寅) and Hai (亥), Mao(卯) and Xu(戌), Chen(辰) and You(酉) and Si(巳) and Shen(申) Wu(午) and Wei(未). Three combination(三合) is composed of ShenZiChen(申子辰), SiYouChou(巳酉丑), YinWuXu(寅午戌), and HaiMaoWei(亥卯未). Three combination(三合) is composed of ShenZiChen(申子辰), SiYouChou(巳酉丑), YinWuXu(寅午戌), and HaiMaoWei(亥卯未). This is because the time Six Qi(六氣) shifts in these three years are the same.

Implementation of Passive Elements Applied LTCC Substrate for 24-GHz Frequency Band (24 GHz 대역을 위한 LTCC 기판 적용된 수동소자 구현)

  • Lee, Jiyeon;Ryu, Jongin;Choi, Sehwan;Lee, Jaeyoung
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.28 no.2
    • /
    • pp.81-88
    • /
    • 2021
  • In this paper, by applying LTCC substrate, the library of the passive elements is implemented. And it can be used in 24 GHz circuits. Depending on how to use it to the circuit, it is required large value by designing the basic structures such as electrode capacitor and spiral inductor. However they are not available in high-frequency domain, because their SRF(Self-Resonant Frequency) is lower than the frequency of 24-GHz. By solving the limit, this paper devised passive elements classified for the DC and the high-frequency domain. The basic structure is suitable for low frequency under 1~2 GHz like DC. The microstrip λ/8 length stub structure is proposed to use for high-frequency like 24-GHz. The open and short stub structure operate as a capacitor and inductor respectively, also they have their impedances. Through their impedances, we can extract the value with the impedance-related equation. In this paper, the proposed passive elements are produced with the permittivity 7.5 LTCC substrate, the basic structure which are available in the DC constituted a library of capacitance of 2.35 to 30.44 pF and inductance of 0.75 to 5.45 nH, measured respectively. The stub structure available in the high-frequency domain were built libraries of capacitance of 0.44 to 2.89 pF and inductance of 0.71 to 1.56 nH, calculated respectively. The measurements have proven how to diversify value, so libraries can be built more variously. It will be an alternative to the passive elements that it is possible to integrate with the operation circuit of radar module for the frequency 24-GHz.

Implementation of Capacitor and Inductor Applied LCP Substrate for 35-GHz frequency band (35 GHz 대역을 위한 LCP 기판 적용된 커패시터 및 인덕터 구현)

  • Lee, Jiyeon;Ryu, Jongin;Choi, Sehwan;Lee, Jaeyoung
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.27 no.4
    • /
    • pp.67-75
    • /
    • 2020
  • In this paper, by applying LCP substrate, the capacitor and inductor are implemented with a variety of value that can be used in 35 GHz circuits. Depending on how to apply it to the circuit, it is required high value by designing the basic structures such as electrode capacitor and spiral inductor. However they are not available in high-frequency domain, because their SRF(Self-Resonant Frequency) is lower than the frequency of 35-GHz. By finding the limit, this paper devised classifying passive devices for the DC and the high-frequency domain. The basic structure is suitable for DC and microstrip λ/8 length stub structure can be used for high-frequency. The open and short stub structure operate as a capacitor and inductor respectively in the frequency of 35 GHz. If their impedance is known, it is possible to extract the value through the impedance-related equation. By producing with the permittivity 2.9 LCP substrate, the basic structure which are available in the DC constituted a library of capacitance of 1.12 to 13.9 pF and inductance of 0.96 to 4.69 nH, measured respectively. The stub structure available in the high-frequency domain were built libraries of capacitance of 0.07 to 2.88 pF and inductance of 0.34 to 1.27 nH, calculated respectively. The measurements have proven how to diversify value, so libraries can be built more variously. It is possible to integrate with the operation circuit of TRM(Transmit-Receive Module) for the frequency 35-GHz, it will be an alternative to the passive devices that can be properly utilized in the circuit.

The Continuous Measurement of CO2 Efflux from the Forest Soil Surface by Multi-Channel Automated Chamber Systems (다중채널 자동챔버시스템에 의한 삼림토양의 이산화탄소 유출량의 연속측정)

  • Joo, Seung Jin;Yim, Myeong Hui;Ju, Jae-Won;Won, Ho-yeon;Jin, Seon Deok
    • Ecology and Resilient Infrastructure
    • /
    • v.8 no.1
    • /
    • pp.32-43
    • /
    • 2021
  • Multichannel automated chamber systems (MCACs) were developed for the continuous monitoring of soil CO2 efflux in forest ecosystems. The MCACs mainly consisted of four modules: eight soil chambers with lids that automatically open and close, an infrared CO2 analyzer equipped with eight multichannel gas samplers, an electronic controller with time-relay circuits, and a programmable logic datalogger. To examine the stability and reliability of the developed MCACs in the field during all seasons with a high temporal resolution, as well as the effects of temperature and soil water content on soil CO2 efflux rates, we continuously measured the soil CO2 efflux rates and micrometeorological factors at the Nam-san experimental site in a Quercus mongolica forest floor using the MCACs from January to December 2010. The diurnal and seasonal variations in soil CO2 efflux rates markedly followed the patterns of changes in temperature factors. During the entire experimental period, the soil CO2 efflux rates were strongly correlated with the temperature at a soil depth of 5 cm (r2 = 0.92) but were weakly correlated with the soil water content (r2 = 0.27). The annual sensitivity of soil CO2 efflux to temperature (Q10) in this forest ranged from 2.23 to 3.0, which was in agreement with other studies on temperate deciduous forests. The annual mean soil CO2 efflux measured by the MCACs was approximately 11.1 g CO2 m-2 day-1. These results indicate that the MCACs can be used for the continuous long-term measurements of soil CO2 efflux in the field and for simultaneously determining the impacts of micrometeorological factors.

Immunohistochemical Localization of NMDA Receptor in the Auditory Brain Stem of Postnatal 7, 16 Circling Mouse (생후 7일, 16일된 circling mouse 청각 뇌줄기에서 N-메틸-D 아스파르트산염 수용체(NMDA receptor)에 대한 면역염색학적 분포)

  • Choi, In-Young;Park, Ki-Sup;Kim, Hye-Jin;Maskey, Dhiraj;Kim, Myeung-Ju
    • Applied Microscopy
    • /
    • v.40 no.2
    • /
    • pp.53-64
    • /
    • 2010
  • Glutamate receptors may play a critical role in the refinement of developing synapses. The lateral superior olivary nucleus (LSO)-medial nucleus of trapezoid body (MNTB) synaptic transmission in the mammalian auditory brain stem mediate many excitatory transmitters such as glutamate, which is a useful model to study excitatory synaptic development. Hearing deficits are often accompanied by changes in the synaptic organization such as excitatory or inhibitory circuits as well as anatomical changes. Owing to this, circling mouse whose cochlea degenerates spontaneously after birth, is an excellent animal model to study deafness pathophysiology. However, little is known about the development regulation of the subunits composing these receptors in circling mouse. Thus, we used immunohistochemical method to compare the N-Methyl-D-aspartate receptor (NMDA receptor) NR1, NR2A, NR2B distribution in the LSO which project glutamergic excitatory input into the auditory brainstem, in circling mouse of postnatal (p) 7 and 16, which have spontaneous mutation in the inner ear, with wild-type mouse. The relative NMDAR1 immunoreactive density of the LSO in circling mouse p7 was $128.67\pm8.87$ in wild-type, $111.06\pm8.04$ in heterozygote, and $108.09\pm5.94$ in homozygote. The density of p16 circling mouse was $43.83\pm10.49$ in wild-type, $40\pm13.88$ in heterozygote, and $55.96\pm17.35$ in homozygote. The relative NMDAR2A immunoreactive density of LSO in circling mouse p7 was $97.97\pm9.71$ in wild-type, $102.87\pm9.30$ in heterozygote, and $106.85\pm5.79$ in homozygote. The density of LSO in p16 circling was $47.4\pm20.6$ in wild-type, $43.9\pm17.5$ in heterozygote, and $49.2\pm20.1$ in homozygote. The relative NMDAR2B immunoreactive density of LSO in circling mouse p7 was $109.04\pm6.77$ in wild-type, $106.43\pm10.24$ in heterozygote, and $105.98\pm4.10$ in homozygote. the density of LSO in p16 circling mouse was $101.47\pm11.5$ in wild-type, $91.47\pm14.81$ in heterozygote, and $93.93\pm15.71$ in homozygote. These results reveal alteration of NMDAR immunoreactivity in LSO of p7 and p16 circling mouse. The results of the present study are likely to be relevant to understand the central change underlying human hereditary deafness.

Determination of Minimal Pressure Support Level During Weaning from Pressure Support Ventilation (압력보조 환기법으로 기계호흡 이탈시 최소압력보조(Minimal Pressure Support) 수준의 결정)

  • Jung, Bock-Hyun;Koh, Youn-Suck;Lim, Chae-Man;Lee, Sang-Do;Kim, Woo-Sung;Kim, Dong-Soon;Kim, Won-Dong
    • Tuberculosis and Respiratory Diseases
    • /
    • v.45 no.2
    • /
    • pp.380-387
    • /
    • 1998
  • Background: Minimal pressure support(PSmin) is a level of pressure support which offset the imposed work of breathing(WOBimp) developed by endotracheal tube and ventilator circuits in pressure support ventilation While the lower applied level of pressure support compared to PSmin could induce respiratory muscle fatigue, the higher level than PSmin could keep respiratory muscle rest resulting in prolongation of weaning period during weaning from mechanical ventilation PSmin has been usually applied in the level of 5~10 cm$H_2O$, but the accurate level of PSmin is difficult to be determinated in individual cases. PSmin is known to be calculated by using the equation of "PSmin = peak inspiratory flow rate during spontaneus ventilation$\times$total ventilatory system resistance", but correlation of calculated PSmin and measured PSmin has not been known. The objects of this study were firstly to assess whether customarily applied pressure support level of 5~10 cm$H_2O$ would be appropriate to offset the imposed work of breathing among the patients under weaning process, and secondly to estimate the correlation between the measured PSmin and calculated PSmin. Method : 1) Measurement of PSmin : Intratracheal pressure changes were measured through Hi-Lo jet tracheal tube (8mm in diameter, Mallinckroft, USA) by using pulmonary monitor(CP-100 pulmonary monitor, Bicore, USA), and then pressure support level of mechanical ventilator were increased until WOBimp was reached to 0.01 J/L or less. Measured PSmin was defined as the lowest pressure to make WOBimp 0.01 J/L or less. 2) Calculation of PSmin : Peak airway pressure(Ppeak), plateau airway pressure(Pplat) and mean inspiratory flow rate of the subjects were measured on volume control mode of mechanical ventilation after sedation. Spontaneous peak inspiratory flow rates were measured on CPAP mode(O cm$H_2O$). Thereafter PSmin was calculated by using the equation "PSmin = peak inspiratory flow rate$\times$R, R = (Ppeak-Pplat)/mean inspiratory flow rate during volume control mode on mechanical ventilation". Results: Sixteen patients who were considered as the candidate for weaning from mechanical ventilation were included in the study. Mean age was 64(${\pm}14$) years, and the mean of total ventilation times was 9(${\pm}4$) days. All patients except one were males. The measured PSmin of the subjects ranged 4.0~12.5cm$H_2O$ in 14 patients. The mean level of PSmin was 7.6(${\pm}2.5\;cmH_2O$) in measured PSmin, 8.6 (${\pm}3.25\;cmH_2O$) in calculated PSmin Correlation between the measured PSmin and the calculated PSmin is significantly high(n=9, r=0.88, p=0.002). The calculated PSmin show a tendancy to be higher than the corresponding measured PSmin in 8 out of 9 subjects(p=0.09). The ratio of measured PSmin/calculated PSmin was 0.81(${\pm}0.05$). Conclusion: Minimal pressure support levels were different in individual cases in the range from 4 to 12.5 cm$H_2O$. Because the equation-driven calculated PSmin showed a good correlation with measured PSmin, the application of equation-driven PSmin would be then appropriate compared with conventional application of 5~10 cm$H_2O$ in patients under difficult weaning process with pressure support ventilation.

  • PDF

Memory Organization for a Fuzzy Controller.

  • Jee, K.D.S.;Poluzzi, R.;Russo, B.
    • Proceedings of the Korean Institute of Intelligent Systems Conference
    • /
    • 1993.06a
    • /
    • pp.1041-1043
    • /
    • 1993
  • Fuzzy logic based Control Theory has gained much interest in the industrial world, thanks to its ability to formalize and solve in a very natural way many problems that are very difficult to quantify at an analytical level. This paper shows a solution for treating membership function inside hardware circuits. The proposed hardware structure optimizes the memoried size by using particular form of the vectorial representation. The process of memorizing fuzzy sets, i.e. their membership function, has always been one of the more problematic issues for the hardware implementation, due to the quite large memory space that is needed. To simplify such an implementation, it is commonly [1,2,8,9,10,11] used to limit the membership functions either to those having triangular or trapezoidal shape, or pre-definite shape. These kinds of functions are able to cover a large spectrum of applications with a limited usage of memory, since they can be memorized by specifying very few parameters ( ight, base, critical points, etc.). This however results in a loss of computational power due to computation on the medium points. A solution to this problem is obtained by discretizing the universe of discourse U, i.e. by fixing a finite number of points and memorizing the value of the membership functions on such points [3,10,14,15]. Such a solution provides a satisfying computational speed, a very high precision of definitions and gives the users the opportunity to choose membership functions of any shape. However, a significant memory waste can as well be registered. It is indeed possible that for each of the given fuzzy sets many elements of the universe of discourse have a membership value equal to zero. It has also been noticed that almost in all cases common points among fuzzy sets, i.e. points with non null membership values are very few. More specifically, in many applications, for each element u of U, there exists at most three fuzzy sets for which the membership value is ot null [3,5,6,7,12,13]. Our proposal is based on such hypotheses. Moreover, we use a technique that even though it does not restrict the shapes of membership functions, it reduces strongly the computational time for the membership values and optimizes the function memorization. In figure 1 it is represented a term set whose characteristics are common for fuzzy controllers and to which we will refer in the following. The above term set has a universe of discourse with 128 elements (so to have a good resolution), 8 fuzzy sets that describe the term set, 32 levels of discretization for the membership values. Clearly, the number of bits necessary for the given specifications are 5 for 32 truth levels, 3 for 8 membership functions and 7 for 128 levels of resolution. The memory depth is given by the dimension of the universe of the discourse (128 in our case) and it will be represented by the memory rows. The length of a world of memory is defined by: Length = nem (dm(m)+dm(fm) Where: fm is the maximum number of non null values in every element of the universe of the discourse, dm(m) is the dimension of the values of the membership function m, dm(fm) is the dimension of the word to represent the index of the highest membership function. In our case then Length=24. The memory dimension is therefore 128*24 bits. If we had chosen to memorize all values of the membership functions we would have needed to memorize on each memory row the membership value of each element. Fuzzy sets word dimension is 8*5 bits. Therefore, the dimension of the memory would have been 128*40 bits. Coherently with our hypothesis, in fig. 1 each element of universe of the discourse has a non null membership value on at most three fuzzy sets. Focusing on the elements 32,64,96 of the universe of discourse, they will be memorized as follows: The computation of the rule weights is done by comparing those bits that represent the index of the membership function, with the word of the program memor . The output bus of the Program Memory (μCOD), is given as input a comparator (Combinatory Net). If the index is equal to the bus value then one of the non null weight derives from the rule and it is produced as output, otherwise the output is zero (fig. 2). It is clear, that the memory dimension of the antecedent is in this way reduced since only non null values are memorized. Moreover, the time performance of the system is equivalent to the performance of a system using vectorial memorization of all weights. The dimensioning of the word is influenced by some parameters of the input variable. The most important parameter is the maximum number membership functions (nfm) having a non null value in each element of the universe of discourse. From our study in the field of fuzzy system, we see that typically nfm 3 and there are at most 16 membership function. At any rate, such a value can be increased up to the physical dimensional limit of the antecedent memory. A less important role n the optimization process of the word dimension is played by the number of membership functions defined for each linguistic term. The table below shows the request word dimension as a function of such parameters and compares our proposed method with the method of vectorial memorization[10]. Summing up, the characteristics of our method are: Users are not restricted to membership functions with specific shapes. The number of the fuzzy sets and the resolution of the vertical axis have a very small influence in increasing memory space. Weight computations are done by combinatorial network and therefore the time performance of the system is equivalent to the one of the vectorial method. The number of non null membership values on any element of the universe of discourse is limited. Such a constraint is usually non very restrictive since many controllers obtain a good precision with only three non null weights. The method here briefly described has been adopted by our group in the design of an optimized version of the coprocessor described in [10].

  • PDF