• The Korean Journal of Zoology
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• v.31 no.4
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• pp.334-343
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• 1988

Five types of synaPses were differentiated in the antennal lobe or Pieris rapoe. aev are in general axo-dendritic synapses and have symmetrical contacts. The type I synapses contain the uniformly round vesicles of medium size, and consist of the 11% of all synapses in the antennal lobe. The type synapses are filled with the small flat and densely arranged (19%). The type III synapses possess medium-sized round vesicles and dense core ones(24%). The type IV synapses are characterized by such three kinds of vesicles as small round, small flat and dense core vesicles(33%). The type V synapses exhibit the presence of medium-sized round, large round and dense core vesicles(13%). The removal of the left antenna on its proximal portion caused the type IV boutons of the above ave types in ipsilateral antennal lobe to turn into dark or semidark degenerative changes. Therefore, it was concluded that many of the antennal receptor cells projected into the brain terminate in the antennal lobe to form type IV synapses together with the dendrites. 배추회나비 뇌의 촉각엽에 있는 신경세포들은 5가지의 신경연접을 형성하는 것으로 관찰되었다. 이 신경연접들은 모두 축색과 수상돌기간의 연접으로 대칭연접이었다. 제1형 신경연접은 축색종말내에 중등도크기의 단형 연접소포를 가지고 있었고, 촉각엽에 있는 5가지의 신경연접중 11%의 출현빈도수로 관찰되었다. 제2형 신경연접의 축색종말에는 장형과 도형의 2가지 연접소포가 포함되어 있었는데, 모두 소형이었으며 이같은 연접소포들이 축색 종말내에서 조밀하게 관찰되었다. 제2형 신경연접의 출현 빈도수는 19%이었다. 제3형 신경연접은 축색 종말내에 중등도크기의 도형 연접소포와 DENSE CORE VESICLE을 포함하고 있었고 그 출현빈도수는 24%이었다. 제4형 신경연접은 축색총말내에 소형의 도형, 소형의 장형 연접소포 및 DENSE CORE VESICLE의 3가지 연접소포를 가지고 있었고 출현빈도수는 촉각엽에서 가장 큰 33%이었다. 제5형 신경연접은 축색종말내에 중등도크기의 원형, 대형의 원형연접소포 및 DENSE CORE VESICLE을 포함하였고 13%의 출현빈도수로 관찰되었다. 배추횐나비의 촉각에 있는 지각신경세포가 뇌의 촉각엽으로 뻗어 들어가 위의 5가지 신경연접중 어느 형을 형성하는지를 관찰하기 위하여 좌측 촉각의 기부를 제거하여 지각신경세포를 절단하였는데 그 결과, 좌측 촉각엽에서 제4형의 신경연접이 퇴행성 변화를 나타내었다. 그러므로 촉각의 지각신경세포는 뇌의 같은 족 촉각엽에 뻗어와 제4형 신경연접을 형성한다고 결론되었다.

• Journal of Oral Medicine and Pain
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• v.30 no.1
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• pp.87-106
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• 2005

In order to evaluate the mechanism of transmission as well as processing of sensory information originating from low-threshold mechanoreceptor in oral and maxillofacial region at primary synaptic region of trigeminal nervous system, vibrissa afferent fibers of adult cat were labeled with intra-axonal HRP injection. Serial sections containing labeled boutons were obtained from the piece of trigeminal interpolar nucleus. Under electron microscope, total 30 labeled boutons were observed, and ultrastructural characteristics, frequency of occurence, synaptic organizations of vibrissa afferent terminals were analysed. The results were as follows: 1. Labeled boutons contained clear, spherical synaptic vesicles with diameter of 45$\sim$55nm. They formed asymmetrical synapse with dendrites showing definite postsynaptic density, larger synaptic cleft, multiple synaptic structures at various regions. With unlabeled axon terminals(p-ending) containing polymorphic synaptic vesicles, they formed symmetrical synapse showing indefinite postsynaptic density and narrower synaptic area. 2. Each labeled bouton formed 1 to 15 synapses, the average of 4.77$\pm$3.37 contacts per labeled bouton, with adjacent neuronal profiles. Relatively complex synaptic organization, which formed synapses with more than 5 neuronal profiles, was observed in a large number(46.7%, n=14) of labeled boutons. 3. Axo-somatic synapse was not observed. The number of axo-dendritic synapse was 1.83$\pm$1.37 per labeled bouton. Majority(85.0%) of axo-dendritic synapses were formed with dendritic shafts, nonprimary dendrites(n=47, 1.57$\pm$1.38/1 bouton), however, synapses formed with primary dendrites(n=6, 0.20$\pm$0.41/1 bouton) or dendritic spines(n=2, 0.07$\pm$0.25/1 bouton) were rare. 4. 76.7%(n=23) of labeled boutons formed axo-axonic synapse (2.93$\pm$2.36/1 bouton) with p-endings containing pleomorphic vesicles. Synaptic triad, in which p-endings formed synapses with labeled boutons and dendrites adjacent to the labeled boutons simultaneoulsy, were also observed in 60.0%(n=18) of labeled boutons. From the above results, vibrissa afferent terminals of adult cat showed distinctive synaptic organization in the trigeminal interpolar nucleus, thus, suggests their correlation with the function of the trigeminal interpolaris nucleus, which participates in processing of complex sensory information such as two-point discrimination and motivational-affective action. Further studies on physiologic functions such as quantitative analysis on ultrastructures of afferent terminals and nerve transmitters participating in presynaptic inhibition are required.

• The Korean Journal of Malacology
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• v.14 no.2
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• pp.75-83
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• 1998

아프리키 왕달팽이(Achatina fulica) 외투막(mantle edge) 내 근육 속의 신경근연접에 관한 미세구조 연구결과는 다음과 같았다. 신경근연접종말의 형태는 방추형이거나 불규칙형이었으며, 연접막과 근형질막상이 연접간극(synaptic cleft)의 넓이는 30mm 정도로 나타났다. 연접강속에는 전자밀도가 높은 둥근 과립(직경 100mm)과 중등도는 과립(직경 70mm)그리고 전자밀도가 낮은 소포(직경70mm)등 3종류가 관찰되었으며, 연접종말의 외측에는 0.2 - 0.4$\mu\textrm{m}$ 정도크기의 전자밀도가 높은 둥근 과립들이 존재하였다. 전자밀도가 중등도인 둥근 과립 중 일부는 연접막 밖으로 배출(exocytosis) 되었으며, 근형질막과 연접막이 합체되는 현상도 관찰되었다. 근형질(sarcoplasm)내에서 수축성단백질인 액틴과 미오신섬유의 배열은 불규칙하였으며, 세포질성 치밀체(cytoplasmic dense body)도 관찰되었다.

• Applied Microscopy
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• v.34 no.4
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• pp.223-230
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• 2004

To identify the structural basis of mutations that affect synaptic transmission we have begun quantitative ultrastructural descriptions of synapses in cultured Drosophila embryonic neurons. In wild-type cultures, synapses are distinguished by the parallel arrangement of a thickened pre- and post synaptic membrane separated by a synaptic cleft. The presynaptic active zones and postsynaptic densities are defined by electron dense material close to the membrane. Presynaptic regions are also characterized by the presence of one or more electron dense regions, presynaptic densities, around which a variable number of small, clear core synaptic vesicles (mean $35.1{\pm}1.44$ nm in diameter) are clustered. Subsets of these vesicles are in direct contact with either the presynaptic density or the membrane and are considered morphologically docked. A small number of larger, dense core vesicles are also observed in most presynaptic profiles.

• Applied Microscopy
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• v.38 no.4
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• pp.375-382
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• 2008

In order to investigate shape of synaptic vesicles of the tooth pulp afferent boutons and their presynaptic endings (p-endings), and the neuroactive substance of the p-endings in the trigeminal nucleus principalis, rat incisor tooth pulp afferents were labeled by the horseradish peroxidase (HRP) and quantitative ultrastructural analysis and postembedding immunogold labeling were performed. Labeled tooth pulp afferent boutons contained clear, spherical synaptic vesicles (diameter: $45{\sim}55\;nm$) and occasionally dense core vesicles(diameter: $80{\sim}120\;nm$). They formed symmetrical synapses with unlabeled axon terminals (p-endings) containing pleomorphic synaptic vesicles. The ratio of short to long diameter (form factor) of synaptic vesicles of pulp afferent boutons was 0.6 to 0.99, whereas that of p-endings was 0.25 to 0.99. In addition, most of the p-endings showed GABA-like immunoreactivity. These results indicate that the shape of synaptic vesicles is quite different between the tooth pulp afferent boutons and p-endings, and the p-endings may contain GABA as a neuroactive substance in the trigeminal nucleus principalis.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.9
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• pp.366-372
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• 2003

Multilevel coded modulation (MCM) with serial concatenated convolutional code (SCCC) is proposed and the performance is analyzed in this paper. Both high coding gain and bandwidth efficiency can be obtained if SCCC is adopted as a component code at the first level of MCM. Simulation results show that the performance of MCM with Ambroze's SCCC is saturated like that of MCM with PCCC. But MCM with Benedetto's SCCC shows no performance saturation and better performance than MCM with PCCC or Ambroze's SCCC. Thus MCM with Benedetto's SCCC may be a good choice for high quality system with limited bandwidth.

• The Korean Journal of Zoology
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• v.26 no.4
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• pp.253-270
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• 1983

Electron microscopic degeneration studies were carried out on the rat's interpeduncular nucleus following lesion on both habenular nuclei to clarify the morphological nature of their presynaptic endings involved in the habenulo-interpeduncular pathway. Two distinct types of interpeduncular neurons were observed: 30% of large neurons and 70% of small ones. Four types of boutons with many characteristics could be differentiated; small spherical vesicle-containing boutons (40%), large spherical vesicle-containing boutons (18%), pleomorphic vesicle-containing boutons (33%), and elongated vesicle-containg boutons (9%). Vesicle containing dendrites were observed as dendro-dendritic synapses and axo-axonal synapses were also found, though rarely. Two to four days after the lesion on both habenular nuclei, the small spherical vesicle-containing boutons were found almost exclusively in the process of degeneration, while the other types were entirely free of degeneration. Therefore, it is inferred that habenural neurons terminate in the interpeduncular nucleus as small spherical vesicle-containing boutons. The neuronal origin of the other bouton types is discussed.

• Applied Microscopy
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• v.30 no.2
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• pp.121-139
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• 2000

The morphogenesis of neuroblasts and plexiform layers, and establishment of its synapses were studied by electron microscopy in human embryos and fetuses ranging from 10 mm to 260 mm crown-rump length ($5\sim30$ weeks of gestational age). At 30 mm fetus the developing retina was composed of outer and inner neuroblastic layers . Cell division of outer neuroblast was occurred until 90 mm fetus. The transient layer of Chievitz was formed by 30 mm fetus, inner plexiform layer by 50 mm fetus, and outer plexiform layer by 150 mm fetus. The cytoplasm of differentiating ganglion cells contained ribosomes, rough endoplasmic reticula, Golgi complexes, microtubules and dense bodies. The processes of $M\ddot{u}ller$ cell penetrated between groups of ganglion cell axons, and formed the cellular component of the inner limiting membrane at 30 mm fetus. At 90 mm fetus radial fibers of M ller cells contained extensive smooth endoplasmic reticula and microtubules. In each specimen , apposing paired membrane specializations were classified as junctions without synaptic vesicles, conventional synapses and ribbon synapses. At 50 mm fetus the processes of neuroblasts in inner plexiform layer were interconnected by junctions without synaptic vesicles. Conventional synapses developed by addition of synaptic vesicles to initially vesicle-free junctions at 90 mm fetus. At 150 mm fetus ribbon synapses were first recognized by the inclusion of a prominent electron-dense material associated with synaptic vesicles. By 260 mm fetus conventional and ribbon synapses and junctions without synaptic vesicles formed similar to those found in the adult.

• Applied Microscopy
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• v.36 no.2
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• pp.83-91
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• 2006

The number and structure of synapses are dynamically changed in response to diverse physiological and pathological conditions. Since strength of synaptic transmission is closely related to the synaptic density on a neuron, both synaptogenesis and synapse loss may play important roles in controlling neuronal activity. Thus it is essential to estimate the number of synapses using an accurate quantitative method for better understanding of the numerical alteration of synapses under terrain experimental conditions. We applied physical disector principle to estimating the number of synapses per neuron in the dentate gyrus of adult mice. First, we measured the numerical density of granule cells using the physical disector principle. Second, the density of medial perforant path to granule cell synapses was estimated using the bidirectional physical disector. Then, the volume ratio of molecular layer to granule cell layer was measured. With these numerial values, we successfully calculated the number of synapses per neuron. Individual granule cells have approximately 6500 synapses in the dentate gyrus of adult mice $(6,545{\pm}330)$, which are comparable to those of other researchers. Our results showed that the estimation of synapse numbers per neuron using the physical disector principle would provide accurate and precise information on the numerical alteration of synapses in diverse physiological and pathological conditions. Following analyses of synapse numbers using this method will contribute to the better understanding of structural synaptic plasticity in a variety of experimental animal models.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.3
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• pp.125-131
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• 2002

In this paper, a new concatenation scheme of serial concatenated convolutional codes is proposed and the performance analyzed. In the proposed scheme, each of information and parity bits of outer code is entered into inner code through interleaver and deinterleaver. Therefore, the interleaver size is same as the length of input frame. Since the interleaver size of proposed type is reduced to half of the conventional Benedetto type, the interleaver delay time required for iterative decoding is reduced. In addition the multiplexer and demultiplexer are not used in the decoder of the proposed type, the complexity of decoder can be also reduced. As results of simulation, the performance of proposed type shows the better error performance as compared to that of the conventional Benedetto type in case of the same interleaver size. And it can be observed that the difference of BER performance is increased with the increase of Eb/No. In case of the same length of input frame, the proposed type shows almost same performance with Benedetto type despite that the interleaver size is reduced by half.