• BMB Reports
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• v.50 no.5
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• pp.237-246
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• 2017

Synapse is the basic structural and functional component for neural communication in the brain. The presynaptic terminal is the structural and functionally essential area that initiates communication and maintains the continuous functional neural information flow. It contains synaptic vesicles (SV) filled with neurotransmitters, an active zone for release, and numerous proteins for SV fusion and retrieval. The structural and functional synaptic plasticity is a representative characteristic; however, it is highly vulnerable to various pathological conditions. In fact, synaptic alteration is thought to be central to neural disease processes. In particular, the alteration of the structural and functional phenotype of the presynaptic terminal is a highly significant evidence for neural diseases. In this review, we specifically describe structural and functional alteration of nerve terminals in several neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD).

• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.12
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• pp.27-37
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• 1991

In this paper, the novel PLD (Preceding Layer Driven) MLP (Multi Layer Perceptron) neural network model and its learning algorithm is described. This learning algorithm is different from the conventional. This integer weights and hard limit function are used for synaptic weight values and activation function, respectively. The entire learning process is performed by layer-by-layer method. the number of layers can be varied with difficulty of training data. Since the synaptic weight values are integers, the synapse circuit can be easily implemented with CMOS. PLD MLP neural network was applied to English Characters, arbitrary waveform generation and spiral problem.

• The Korean Journal of Zoology
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• v.39 no.2
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• pp.223-230
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• 1996

Fine structure of the neuromuscular junction in the venomous organ of the spider, Agelena li'mbutq, was studied using high magnification electron microscope. The motor nerve endings at neuromuscular contact area composed of neurons and neuroslial cells were located between musculature and extracellular sheath of the venom gBand. At the synaptic contact between a motor axon and a muscle fiber in the musculature, spherical synaptic vesicles were prominent in the nerve terminal. The sarcoplasm beneath the neuromuscular synapse has a granular appearance and lacks mvofilaments. And the main axon gives off a branch between the muscle fibers. The synaptic regions of this organ are located close to the myofilaments unlike to other chelicerate classes. Moreover the postsvnaptic complex of vesicles and membrane invasinations present in other synaptic legions are absent from these legions in this venomous organ.

• Molecules and Cells
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• v.41 no.7
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• pp.622-630
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• 2018

Leukocyte common antigen-related protein tyrosine phosphatases (LAR-RPTPs) are cellular receptors of heparan sulfate (HS) and chondroitin sulfate (CS) proteoglycans that regulate neurite outgrowth and neuronal regeneration. LAR-RPTPs have also received particular attention as the major presynaptic hubs for synapse organization through selective binding to numerous postsynaptic adhesion partners. Recent structural studies on LAR-RPTP-mediated trans-synaptic adhesion complexes have provided significant insight into the molecular basis of their specific interactions, the key codes for their selective binding, as well as the higher-order clustering of LAR-RPTPs necessary for synaptogenic activity. In this review, we summarize the structures of LAR-RPTPs in complex with various postsynaptic adhesion partners and discuss the molecular mechanisms underlying LAR-RPTP-mediated synaptogenesis.

• Applied Microscopy
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• v.46 no.4
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• pp.171-175
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• 2016

A distinctive neuronal network in the brain is believed to make us unique individuals. Electron microscopy is a valuable tool for examining ultrastructural characteristics of neurons, synapses, and subcellular organelles. A recent technological breakthrough in volume electron microscopy allows large-scale circuit reconstruction of the nervous system with unprecedented detail. Serial-section electron microscopy-previously the domain of specialists-became automated with the advent of innovative systems such as the focused ion beam and serial block-face scanning electron microscopes and the automated tape-collecting ultramicrotome. Further advances in microscopic design and instrumentation are also available, which allow the reconstruction of unprecedentedly large volumes of brain tissue at high speed. The recent introduction of correlative light and electron microscopy will help to identify specific neural circuits associated with behavioral characteristics and revolutionize our understanding of how the brain works.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.4
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• pp.869-874
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• 2000

아홉 개의 계층구조 형태의 뉴런을 LINUX를 기초로 한 GENESIS를 이용하여 입력전류에 대한 각 뉴런의 신경전달 메카니즘을 분석하였고 마지막 뉴런에 미치는 활성전위 영향을 시뮬레이션을 해 보았다. 본 연 구에서는 다른 뉴런과 연결해주며 신호를 전달해주는 시냅스의 웨이트를 중간계층 뉴런에서 적게 연결하여 비정상 상태의 뉴런을 만들어 보았다. 시뮬레이션 결과 신경세포를 전기회로 적인 모델을 기준으로 설계한 뉴런은 미세한 자극의 변화해 매우 민감하게 반응 하였고, 마지막 뉴런 에서는 활성전위 간격이 정상상태의 다른 세포와 비교해 보았으며, 결과적으로 뉴런의 시냅스 웨이트가 적으면 신경전달에 이상 이 발생하여 세 포가 손상됨을 알 수 있었다.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.05b
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• pp.536-540
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• 2003

최근에 개인의 경험을 통해 얻어지는 외부의 물리적 자극에 대한 복합적인 감성을 측성 및 분석하여 공학적으로 처리함으로서 인간이 보다 편리하고 안락한 생활을 영위하도록 하는 연구가 활발히 진행되고 있다. 본 논문에서는 색채 심리를 바탕으로 한 감성을 인식할 수 있는 생리학적 퍼지 신경망은 제안하였다. 본 논문에서 제안한 생리학적 퍼지 뉴런 구조를 기반으로 하여 입력층, 퍼지 귀속 시넵스(Fuzzy Membership Synapse) 및 출력층으로 구성되며 지도 학습(supervised learning)으로 동작된다. 제안된 생리학적 퍼지 신경망을 단일 색상 정보에 따른 감성 인식에 적용한 결과, 단일 색상 정보에 따른 감성 인식에 있어서 효율적임을 확인 할 수 있었다.

• Proceedings of the Korean Society for Information Management Conference
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• 2013.08a
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• pp.67-70
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• 2013

국내 전자학술지에서 현재 논문 보조자료를 제공하고 있는 학술지는 총 1640종 중 52종이며, 학문 분야별로는 의약학 분야가 35종(21.6%), 자연과학 분야가 12종(12.8%), 공학 4종(2%) 순으로 나타났다. 보조자료 보유 종수의 대부분을 차지하는 의약학 분야, 특히 Synapse에서 서비스되고 있는 논문 보조자료 최근 5년간 현황을 살펴보면, 총 41종의 학술지, 총 109건의 논문에서 논문 보조자료를 보유하고 있었다. 보조자료의 자료 유형은 pdf 형식이 59%로 절반 이상을 차지하고 있었고, 이어서 동영상 파일 유형이 28%를 차지하고 있었다. 본 연구는 국내 전자학술지 현황을 조사 분석한 기초 연구이다. 이를 바탕으로 향후 국내 전자학술지 논문 보조자료를 원활하게 활용할 수 있는 실질적인 방안 모색이 강구되어야 할 것이다.

• BMB Reports
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• v.54 no.3
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• pp.149-156
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• 2021

The well-known second messenger cyclic adenosine monophosphate (cAMP) regulates the morphology and physiology of neurons and thus higher cognitive brain functions. The discovery of exchange protein activated by cAMP (Epac) as a guanine nucleotide exchange factor for Rap GTPases has shed light on protein kinase A (PKA)-independent functions of cAMP signaling in neural tissues. Studies of cAMP-Epac-mediated signaling in neurons under normal and disease conditions also revealed its diverse contributions to neurodevelopment, synaptic remodeling, and neurotransmitter release, as well as learning, memory, and emotion. In this mini-review, the various roles of Epac isoforms, including Epac1 and Epac2, highly expressed in neural tissues are summarized, and controversies or issues are highlighted that need to be resolved to uncover the critical functions of Epac in neural tissues and the potential for a new therapeutic target of mental disorders.

• Molecules and Cells
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• v.45 no.1
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• pp.16-25
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• 2022

Mechanical forces play pivotal roles in regulating cell shape, function, and fate. Key players that govern the mechanobiological interplay are the mechanosensitive proteins found on cell membranes and in cytoskeleton. Their unique nanomechanics can be interrogated using single-molecule tweezers, which can apply controlled forces to the proteins and simultaneously measure the ensuing structural changes. Breakthroughs in high-resolution tweezers have enabled the routine monitoring of nanometer-scale, millisecond dynamics as a function of force. Undoubtedly, the advancement of structural biology will be further fueled by integrating static atomic-resolution structures and their dynamic changes and interactions observed with the force application techniques. In this minireview, we will introduce the general principles of single-molecule tweezers and their recent applications to the studies of force-bearing proteins, including the synaptic proteins that need to be categorized as mechanosensitive in a broad sense. We anticipate that the impact of nano-precision approaches in mechanobiology research will continue to grow in the future.