• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 추계학술대회 논문집 학회본부
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• pp.189-192
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• 1991

This paper presents a modular structure design of analog Hopfield neural network. Each multiplier consists of four MOS transistors which are connected to an op-amp at the front end of a neuron. A pair of MOS transistor is used in order to maintain linear operation of the synapse and can produce positive or negative synaptic weight. This architecture can be expandable to any size neural network by forming tree structure. By altering the connections, other nework paradigms can also be implemented using this basic modules. The stength of this approach is the expandability and the general applicability. The layout design of a four-neuron fully connected feedback neural network is presented and is simulated using SPICE. The network shows correct retrival of distorted patterns.

• Applied Microscopy
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• 제17권2호
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• pp.41-54
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• 1987

This experiment was performed to investigate the acute and chronic effects of lead on cerebral cortex. In acute treatment, mouse were injected with lead acetate at dose of 0.3 mmole/kg body weight, and in chronic treatment, mouse were supplied 0.03 M lead acetate sol. in the place of water. After treatment, mouse were sacrificed at time intervals of 24, 48, 72, and 96 hours in acute treatment and at time intervals of 4 weeks and 8 weeks in chronic treatment. In acute treatment, acetylcholinesterase activity is reduced at 72 hours and recovered at 96 hours in homogenate, and reduced at 24 hours and recovered at 72 hours in crude synaptosomes. In chronic treatment, acetylcholinesterase activity is increased in young mouse but reduced in mother mouse. Ultrastructural changes were composed of swelling of Golgi apparatus, nerve terminals with diminished synaptic vesicles, and vacuolated myeline lamellae of myelinated axon.

• 대한수의학회지
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• 제11권1호
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• pp.59-63
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• 1971

Current interest in ${\gamma}$-aminobutyric acid (GABA) has arisen from the convergence of several independent line of investigation leading to the demonstration that this and related substances are normal products of brain metabolism and that GABA has an important physiological action upon brain function as well as upon certain peripheral nervous structures. The interest for neurophysiologists has been enhanced by the importance of the discovery for the role of humoral mediator of synaptic transmission or regulator of neuronal activity in the central nervous system, particularly if it may shed some elight upon the nature of central inhibitory processes. In accordance with such an interest and importance, this work was performed in order to standardize the normal content as a preliminary investigation of so-called night active and daytime active animals GABA content in their brains when they are exposed to light and darkness. The method, through which the estimation has made in this work, was paper chromatographic method developed by Maynert and Klingman for the estimation of GABA content in animal tissues. The results obtained are summerized as follows: 1) GABA content in the cerebral cortex of house rat ranged from 90 to $310{\mu}g/gm$ of wet weight. 2) The content of GAGA ranging from 130 to $510{\mu}g/gm$ of wet weight was occurred from midbrain of the rat. 3) GABA content was ranged from 30 to $150 {\mu}g/gm$ of wet weight of the rat cerebellum. 4) The contents of fowl cerebral cortex, midbrain, and cerebellum are estimated as ranging 230-590, 250-620, $50-280{\mu}g/gm$ of wet weight, respectively. As a result, it may be concluded that among three brain tissues of both animals the midbrain is the highest region in GABA content. Fowl brain, on the other side, contains more higher GABA content than the house rat brain does.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권3호
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• pp.356-363
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• 2014

In this paper, we propose a new memristor-based crossbar array architecture, where a single memristor array and constant-term circuit are used to represent both plus-polarity and minus-polarity matrices. This is different from the previous crossbar array architecture which has two memristor arrays to represent plus-polarity and minus-polarity connection matrices, respectively. The proposed crossbar architecture is tested and verified to have the same performance with the previous crossbar architecture for applications of character recognition. For areal density, however, the proposed crossbar architecture is twice better than the previous architecture, because only single memristor array is used instead of two crossbar arrays. Moreover, the power consumption of the proposed architecture can be smaller by 48% than the previous one because the number of memristors in the proposed crossbar architecture is reduced to half compared to the previous crossbar architecture. From the high areal density and high energy efficiency, we can know that this newly proposed crossbar array architecture is very suitable to various applications of analog neuromorphic computing that demand high areal density and low energy consumption.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.254-257
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• 1993

This paper presents a new method to implement Hebbian learning method on artificial neural network. In hebbian learning algorithm, complexity in terms of multiplications is high. To save the chip area, we consider a new learning circuit. By calculating similarity, or correlation between $X_i$ and $O_i$, large portion of circuits commonly used in conventional neural networks is not necessary for this new hebbian learning circuit named COR. The output signals of COR is applied to weight storage capacitors for direct control the voltages of the capacitors. The weighted sum, ${\Sigma}W_{ij}O_j$, is realized by multipliers, whose output currents are summed up in one line which goes to learning circuit or output circuit. The drain current of the multiplier can produce positive or negative synaptic weights. The pass transistor selects eight learning mode or recall mode. The layout of an learnable six-neuron fully connected Hopfield neural network is designed, and is simulated using PSPICE. The network memorizes, and retrieves the patterns correctly under the existence of minor noises.

• 대한후두음성언어의학회지
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• 제23권2호
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• pp.93-98
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• 2012

Botulinum toxins are the most potent toxins known to mankind. Botulinum toxin acts by blocking the cholinergic neuromuscular or the cholinergic autonomic innervation of exocrine glands and smooth muscles. Seven distinct antigenic botulinum toxins (A, B, C, D, E, F and G) produced by different strains of Clostridium botulinum have been described and only A and B type of botulinum toxins were clinically used. Toxins were consisted of a heavy chain with a molecular weight of 100 kD and a light chain with a molecular weight of 50 kD. Toxins are bound with an astounding selectivity to glycoprotein structures located on the cholinergic nerve terminal. Subsequently light chain of toxin is internalized and cleaves different proteins of the acetylcholine transport protein cascade transporting the acetylcholine vesicle from the intracellular space into the synaptic cleft. After a decade of therapeutic application of the toxin, no anaphylaxis or deaths have been reported and systemic adverse effects have not been reported so far. However the toxin's immunologic properties can lead to the stimulation of antibody production, potentially rendering further treatments ineffective. Botulinum toxin is a safe and effective treatment. Use of botulinum toxin in clinical medicine has grown exponentially in recent years, and many parts of the human body are now being targeted for therapeutic purposes.

• 전자공학회논문지
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• 제52권8호
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• pp.49-58
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• 2015

본 연구에서는 $TiO_2$멤리스터와 동일한 동작특성을 갖는 멤리스터 에뮬레이터 회로를 비접지형 회로로 개발하였다. 대부분의 기존 멤리스터 에뮬레이터는 다른 멤리스터나 소자들과의 연결성을 고려하지 않은 접지 식으로 개발된 것들이다. 본 연구에서 개발한 멤리스터 에뮬레이터는 비접지식으로서, 출력 단을 접지할 필요가 없기 때문에 다른 소자들과 연결이 가능하여, 다양한 회로들과의 연결하여 동작을 확인하는데 사용할 수 있다. 개발한 멤리스터 에뮬레이터의 기능을 확인하기 위해서 저항과 직렬로 연결한 회로와 4개의 멤리스터 에뮬레이터를 직렬 및 병렬로 연결한 휘트스톤 브리지 회로를 구성하였다. 또한 이브리지 회로가 신경망 시냅스의 가중치 연산이 가능함을 보였다.

• The Korean Journal of Physiology and Pharmacology
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• 제14권2호
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• pp.113-118
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• 2010

The sensory system is developed and optimized by experiences given in the early phase of life in association with other regions of the nervous system. To date, many studies have revealed that deprivation of specific sensory experiences can modify the structure and function of the central nervous system; however, the effects of sensory overload remains unclear. Here we studied the effect of overloading the taste sense in the early period of life on the synaptic plasticity of rat hippocampus and somatosensory cortex. We prepared male and female Sprague Dawley rats with ad libitum access to a 0.1% saccharin solution for 2 hrs per day for three weeks after weaning on postnatal day 22. Saccharin consumption was slightly increased in males compared with females; however, saccharin intake did not affect chow intake or weight gain either in male or in female rats. We examined the effect of saccharin-intake on long term potentiation (LTP) formation in hippocampal Schaffer collateral pathway and somatosensory cortex layer IV - II/III pathways in the 6-week old saccharin-fed rats. There was no significant difference in LTP formation in the hippocampus between the control group and saccharin-treated group in both male and female rats. Also in the somatosensory cortex, we did not see a significant difference in LTP among the groups. Therefore, we conclude that saccharin-intake during 3~6 weeks may not affect the development of physiological function of the cortical and hippocampal synapses in rats.

• 전자공학회논문지
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• 제52권4호
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• pp.80-87
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• 2015

멤리스터는 인가된 전하의 크기에 따라 저항의 크기가 변화하고, 외부 전원이 끊겨도 이전의 저항 상태를 계속 기억하는 새로운 형태의 메모리소자이다. 일반적인 멤리스터는 직류 전압을 인가할 경우, 시간에 대해서 저항의 크기가 비선형적으로 프로그램밍되는 특성을 갖고 있다. 멤리스터에 대한 용이한 프로그램을 위해서는 시간에 대해서 저항의 크기가 선형적으로 증가 혹은 감소하는 것이 바람직하다. 본 연구팀은 과거 +, - 및 0 에 대한 가중치 프로그램이 가능한 멤리스터 브릿지 회로 구조를 제안한 바 있다. 멤리스터 브릿지 회로에서 두 개의 멤리스터는 서로 다른 극성으로 직렬 연결되고, 반대 극성의 멤리스터들 간의 상호 보완 관계에 의해 강력한 선형화 효과를 갖는다. 본 논문에서는 브릿지 회로의 시간에 대한 멤리스터의 선형적 프로그램 특성을 연구하였고, HP 사의 $TiO_2$ 멤리스터와 윈도우 기반 비선형성 멤리스터 모델을 사용하여 선형화 효과를 검증하였다. 멤리스터 브릿지 회로는 멤리스터를 이용한 시냅스 회로에서 시냅스의 가중치 프로그램을 수행할 경우, 유용하게 사용될 것으로 전망된다.

• Journal of Microbiology and Biotechnology
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• 제28권5호
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• pp.679-687
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• 2018

Korean red pine (Pinus densiflora) is one of the major Pinus species in Korea. Red pine bark is removed prior to the chipping process in the wood industry and discarded as waste. However, red pine bark contains a considerable amount of naturally occurring phenolics, including flavonoids, and therefore may have a variety of biological effects. In this study, we investigated if Korean red pine bark extract (KRPBE) could protect neuronal PC-12 cells from oxidative stress and inhibit cholinesterase activity. Analysis of reversed-phase high-performance liquid chromatography results revealed four phenolics in KRPBE: vanillin, protocatechuic acid, catechin, and taxifolin. The total phenolic and flavonoid contents of KRPBE were 397.9 mg gallic acid equivalents/g dry weight (DW) and 248.7 mg catechin equivalents/g DW, respectively. The antioxidant capacities of KRPBE measured using ABTS, DPPH, and ORAC assays were 697.3, 521.8, and 2,627.7 mg vitamin C equivalents/g DW, respectively. KRPBE and its identified phenolics protected against $H_2O_2$-induced oxidative cell death in a dose-dependent manner. Acetylcholinesterase and butyrylcholinesterase, which degrade the neurotransmitter acetylcholine to terminate neurotransmission in synaptic clefts, were inhibited by treatment with KRPBE and its identified phenolics. Taken together, these results suggest that KRPBE and its constituent antioxidative phenolics are potent neuroprotective agents that can maintain cell viability under oxidative stress and inhibit cholinesterase activity.