• Polymer(Korea)
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• v.25 no.4
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• pp.476-485
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• 2001

In this study, we tried to design and synthesize using natural polymers (hyaluronic acid and sodium alginate) and also to make some kinds of scaffolds as sponge type for reducing the burst effect of loaded drug from them. Photo-dimerizable group was incorporated to hyaluronic acid and degradable hydrogel was prepared by the UV radiation of the polymer. The pore size and its distribution of scaffold were controlled by changing microsphere production conditions such as solution concentration and spraying pressure. It was found that drug release behavior from synthesized scaffolds was affected by hybridization of two naturally originated polymers (cinnamoylated tetrabutylammonium hyaluronate: CHT and cinnamolylated sodium alginate: CSA) and the obtained scaffolds were degraded in fairly long time (about 2 months) under in vitro environment. Therefore, we expect that obtained scaffolds can be applicable for the tissue regeneration scaffolds in the fields of orthopaedic surgery.

• Korean Journal of Ichthyology
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• v.26 no.4
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• pp.274-280
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• 2014

The spermatozoa of Platichthys stellatus is relatively simple cells composed of a spherical head, a short midpiece, and a tail, as in most Pleuronectiformes. The ultrastructure is characterized by the following features: a round nucleus with a deep nuclear fossa, the centriolar complex located at a right angle to each other, a short midpiece, a tail with paired lateral ribbon and no acrosome. However there are some minor morphological differences, including the appearance and number of the mitochondria, the shape and size of the nuclear fossa and the structure of the basal body. Especially the basal body structure consisting of a basal foot, a rootlet and nine alar sheets structures varies considerably in different species. It can be used as indicator of relationships in Pleuronectiformes because minute morphological differences might have functional and evolutionary significance. In conclusion, the spermatozoa of P. stellatus show a certain structural homogeneity and provide support for the concept that ultrastructural features of spermatozoa can be useful in taxonomic studies of Pleuronectiformes.

• Korean Journal of Ichthyology
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• v.31 no.4
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• pp.208-213
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• 2019

Spermatozoa of Aphyocypris chinensis was studied by transmission electron microscopy. The investiation revaled that, spermatozoa display a round head, a small midpiece and a long tail region. In the spermatozoa, the nucleus contains highly condensed homogeneous chromation with small electron lucent areas. The base of the nucleus is slightly invaginated laterally by the nuclear fossa which contains the proximal centriole. The two centrioles orientated at an obtus angle (130°) to each other. The midpiece encircles the flagellum and is completely separated from it by the cytoplasmic channel. The midpiece contains more than 12 mitochondria. The mitochondria are arranged in 4~5 layer and are asymmetrically distributed in the postnuclear cytoplasm. The mitochondria surround the proximal part of the flagellum. The flagellum has classical 9+2 axoneme and no lateral fins. The spermatozoa of A. chinensis are similar to those of other cyprinids having a spherical head with a shallow nuclear fossa, a short midpiece including the asymmetrical arrangement of mitochondria and the lateral insertion of flagellum. However, there are some differences in the orientation of centrioles and the number of the mitochondria.

• Journal of the korean academy of Pediatric Dentistry
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• v.30 no.4
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• pp.715-721
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• 2003

Dental injuries with crown fracture occur frequently, especially in young patient Reattachment of the crown fragment has been shown to yield good esthetic results in that original tooth anatomy is restored with a material that abrades at a rate indntical to that of the adjacent tooth substance and at the same time permits continual monitoring of pulpal status through the fragment. Case 1 was complicated crown fracture with pin-point bleed ing, that was treated by direct pulp capping with calcium hydroxide and fragment reattachment. Case 2 was in trusive luxation with complicated crown fracture and was treated by pulp treatment and fragment reattachment. Case 3 was uncomplicated crown fracture, and fracture line involved slightly biologic width and treated by reattachment of the crown fragment.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.3
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• pp.383-387
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• 2000

Fusion is defined as union of two separate tooth buds at some stage in their development with confluence of dentin and characterized by separate root canal and large single crown, while gemination is defined as an attempt of the single tooth bud to incompletely divide and usually result in a single root with one root canal and two completely or incompletely separated crowns. It is sometimes difficult to decide whether an abnormally large tooth is the result of fusion of a normal and a supernumerary tooth, or of gemination; use of the term 'Double tooth' may make the clinicians avoid this difficulty(Brook & Winter). Commonly there are no symptoms, but the problems associated with these anomalies include esthetics, possible loss of arch length and delayed or ectopic eruption of the permanent teeth, caries along the line of demarcation, and periodontal disease. Commonly, it dose not need to be treated in primary dentition but in case of permanent dentition, it may be requested to be treated due to esthetics and other problems. In our case, a 8 years old girl showed a Double tooth, we attained the favorable results by performing hemisection with apexification.

• Korean Chemical Engineering Research
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• v.51 no.5
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• pp.597-601
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• 2013

In this study, we present simple microfluidic approach for the synthesis of monodisperse microcapsules by using droplet-based system. We generate double emulsion through single step in the microfluidic device having single junction while conventional approaches are limited in surface treatment for the generation of double emulsion. First, we have injected disperse fluid containing FC-77 oil and photocurable ethoxylated trimethylolpropane triacrylate (ETPTA) and water containing 3 wt% poly(vinyl alcohol) (PVA) as continuous phase into microfluidic device. Under the condition, we easily generate double emulsion with high monodispersity by using flow focusing. The double emulsion droplets are transformed into microcapsules under the UV irradiation via photopolymerization. In addition, we control thickness of double emulsion's shell by controlling flow rate of ETPTA. We also show that the size of double emulsions can be controlled by manipulation of flow rate of continuous phase. Furthermore, we synthesize microcapsules encapsulating various materials for the application of drug delivery systems.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.2
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• pp.127-132
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• 2013

Traumatic injuries to immature permanent teeth are common and the results can be destructive. Although Hertwig's epithelial root sheath is usually sensitive to trauma, it may resist damage from trauma thereby retaining its vitality and continuing to calcify a root under favorable conditions. This case report describes two cases of trauma to immature permanent incisors. The first case presents an avulsed maxillary central incisor which has been replanted. The other case shows completely avulsed mandibular central incisors which have not been replanted. However, both cases subsequently show continued growing roots separated from the main roots. This report highlights the ability of the immature pulp tissue to continue to form dentin and the robustness of Hertwig's epithelial root sheath to initiate root development despite a traumatic injury.

• Applied Microscopy
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• v.29 no.2
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• pp.223-230
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• 1999

The epithelium of the rectum in the mosquito larvae, Culex pipiens pallens: Culicidae, was observed with electron microscope. The rectum of posterior hindgut was composed of epithelial tissue which were covered with cuticular intima on the luminal side, connective tissue and muscular tissue. The rectal epithelial cells were squamous absorptive cells, and apical plasma membranes were highly folded to form apical infoldings with mitochondria inserted them. The lateral plasma membranes were irregularly infolded and well developed mitochondria were found closely associated with infoldings . And intercellular spaces (or channels) were formed between the epithelial cells, whereas speptate junction was found near the apical zone between them. Also basal plasma membrane were infolded which made basal infoldings ('basal labyrinth'), and were covered with thin basal lamina. Rcetal epithelium was surrounded by the connective tissue which was contained axon and tracheole cells. Connective tissue was covered with the bundles of circular and longitudinal muscles.

• The Korean Journal of Malacology
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• v.8 no.1
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• pp.61-71
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• 1992

동양달팽이 (Nesiohelix samarangae)는 동양달팽이속(Nesiohelix)에 속하는 종으로 한국에서 동양？팽이속으로는 유일하게 발견되는 종이다. 본 실험에서는 동양달팽이의 웅성생식기관의 각 부분 즉, 난정소(ovotestis), 양성관(hermaphrodite duct), 수정실(fertilization chamber), 전립선(prostate), 수정관(vas deferens), 상음경(epiphallus), 음경(penis)등의 배열 상태를 관찰하고 이들에 대한 광학현미경적 관찰을 위해 Hematoxylin- Eosin염색과 Mallory 염색을 실시하였다. 난정소(ovotestis)는 많은 수의 선포(acini)로 이루어져 있으며 각 선포는 배상피세포층(germinal epithelial cell layer)과 영양세포(nurse cell), 생식세포(gamete cell)들로 이루어져 있었다. 선포(acini)는 원주상피로 덮여있었다. 양성관(hermaphrodite duct)은 가늘고 긴 관으로 내벽은 섬모입방상피세포와 얇은 결합조직층으로 이루어져 있었으며 내강은 농축된 정자로 가득 차 있었다 . 수정관(fertilization chamber)은 3개의 도관이 결합조직에 의해 둘러싸인 형태로 이루어져 있었다. 도관의 상피세포는 뚜렷한 위중층섬모원주세포로 되어 있었다. 전립선(prostaoe)은 분비기능을 가진 것으로 사료되는 세포들과 실제 분비가 일어나는 실(chamber)로 이루어져 있었으나 다른 염색법 또는 전자현미경적 관찰에 의해 다른 구조들의 존재유무를 확인 해야할 것으로 사료된다. 실(chamber)은 분비포로 보이는 세포들과 접해 있었다. 수정관(vas deferens)은 결합조직으로 이루어진 근육질의 두꺼운 벽을 가지고 있었으며 내강은 돌출부위에 의해 4부분으로 갈라져 있었다. 내강에 연한 상피는 원주세포로 되어 있었다. 상음경(epiphallus)의 벽은 근섬유 다발은 벽의 외곽으로 갈수록 밀도가 높아졌다. 상부에 내강과 연결되는 함입구조(groove)를 가지며, 내강에 연한 상피는 섬모가 없는 원주세포로 이루어져 있었다. 음경(penis)은 근섬유가 산재된 두꺼운 벽을 가졌으며 상음경보다 굵은 원통형이었다. 내강은 많은 돌출부에 의해 복잡하게 나뉘어 있으며 상피세포는 원주 세포로 이루어져 있었고 섬모는 관찰되지 않았다. 내강 내의 분비물과 세포의 형태로 보아 내강상피세포는 분비기능을 가진 것으로 사료된다.

• Journal of the korean academy of Pediatric Dentistry
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• v.48 no.1
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• pp.115-121
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• 2021

Dilacerations generally involve central incisors; most often maxillary incisors rather than their mandibular counterparts. The clinical features of dilaceration include non-eruption of the responsible tooth or prolonged retention of the deciduous predecessor tooth. In Case 1, the tooth showed a dilaceration at the boundary between the crown and the root, more laterally rather than labiolingually. In Case 2, the dilacerated tooth showed a crown dilaceration with a relatively normal orientation of the dental root. In both cases, no significant space losses for eruption were observed. Moreover, it seems that unlike the maxilla with the palate, the mandibular anterior teeth are limited to show severe displacement. From these cases, it is suggested that if a mandibular permanent incisor shows a crown dilaceration or lateral dilaceration at the boundary between the crown and the root, there is a relatively high probability of spontaneous eruption of the dilacerated tooth.