• Korean Journal of Ecology and Environment
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• v.38 no.1 s.110
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• pp.30-44
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• 2005

To investigate the flora and vegetation structure of vascular plants in the littoral zone of Paldang Reservoir, from April, 2003 to April 2004, nine sampling sites were selected. Along the Paldang Reservoir, 128 taxa, consisted of 51 families and 96 genera, were identified, among them, hydrophytes were confirmed as 38 taxa, which was comprised 29.7% to total taxa, whereas hygrophytes were 44 taxa and terrestrial plants were 46 taxa. Emergent hydrophytes consists of 21 taxa, including Phragmites australis and Typha angustifolia, and next, submerged hydrophytes were 8 taxa. However, the kinds and vegetation area of submerged hydorphytes were reduced compared to previous studies. In the littoral zone of Paldang Reservoir, the aquatic vegetation was widely developed near Dumulmori, Yangsuri, and Kwangdong Bridge, downstream of Kyungancheon. The average number of hydrophyte per sampling sites were 2.7 taxa, whereas hygrophytes were 2.5, and land plants were 1.8. In addition, the hydrophytes in the littoral zone of Paldang Reservoir showed the typical vertical zonation pattern like a natural swamp. These results mean that the littoral zone of Paldang Reservoir has the typical characteristics of aquatic plant ecosystem.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.102-102
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• 2018

Electronic industry had required the finer size and the higher performance of the device. Therefore, 3-D die stacking technology such as TSV (through silicon via) and micro-bump had been used. Moreover, by the development of the 3-D die stacking technology, 3-D structure such as chip to chip (c2c) and chip to wafer (c2w) had become practicable. These technologies led to the appearance of HBM (high bandwidth memory). HBM was type of the memory, which is composed of several stacked layers of the memory chips. Each memory chips were connected by TSV and micro-bump. Thus, HBM had lower RC delay and higher performance of data processing than the conventional memory. Moreover, due to the development of the IT industry such as, AI (artificial intelligence), IOT (internet of things), and VR (virtual reality), the lower pitch size and the higher density were required to micro-electronics. Particularly, to obtain the fine pitch, some of the method such as copper pillar, nickel diffusion barrier, and tin-silver or tin-silver-copper based bump had been utillized. TCB (thermal compression bonding) and reflow process (thermal aging) were conventional method to bond between tin-silver or tin-silver-copper caps in the temperature range of 200 to 300 degrees. However, because of tin overflow which caused by higher operating temperature than melting point of Tin ($232^{\circ}C$), there would be the danger of bump bridge failure in fine-pitch bonding. Furthermore, regulating the phase of IMC (intermetallic compound) which was located between nickel diffusion barrier and bump, had a lot of problems. For example, an excess of kirkendall void which provides site of brittle fracture occurs at IMC layer after reflow process. The essential solution to reduce the difficulty of bump bonding process is copper to copper direct bonding below $300^{\circ}C$. In this study, in order to improve the problem of bump bonding process, copper to copper direct bonding was performed below $300^{\circ}C$. The driving force of bonding was the self-annealing properties of electrodeposited Cu with high defect density. The self-annealing property originated in high defect density and non-equilibrium grain boundaries at the triple junction. The electrodeposited Cu at high current density and low bath temperature was fabricated by electroplating on copper deposited silicon wafer. The copper-copper bonding experiments was conducted using thermal pressing machine. The condition of investigation such as thermal parameter and pressure parameter were varied to acquire proper bonded specimens. The bonded interface was characterized by SEM (scanning electron microscope) and OM (optical microscope). The density of grain boundary and defects were examined by TEM (transmission electron microscopy).

• 한국균학회소식:학술대회논문집
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• 2014.10a
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• pp.11-11
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• 2014

Fungal pathogens have huge impact on health and economic wellbeing of human by causing life-threatening mycoses in immune-compromised patients or by destroying crop plants. A key determinant of fungal pathogenesis is their ability to undergo developmental change in response to host or environmental factors. Genetic pathways that regulate such morphological transitions and adaptation are therefore extensively studied during the last few decades. Given that epigenetic as well as genetic components play pivotal roles in development of plants and mammals, contribution of microbial epigenetic counterparts to this morphogenetic process is intriguing yet nearly unappreciated question to date. To bridge this gap in our knowledge, we set out to investigate histone modifications among epigenetic mechanisms that possibly regulate fungal adaptation and processes involved in pathogenesis of a model plant pathogenic fungus, Magnaporthe oryzae. M. oryzae is a causal agent of rice blast disease, which destroys 10 to 30% of the rice crop annually. Since the rice is the staple food for more than half of human population, the disease is a major threat to global food security. In addition to the socioeconomic impact of the disease it causes, the fungus is genetically tractable and can undergo well-defined morphological transitions including asexual spore production and appressorium (a specialized infection structure) formation in vitro, making it a model to study fungal development and pathogenicity. For functional and comparative analysis of histone modifications, a web-based database (dbHiMo) was constructed to archive and analyze histone modifying enzymes from eukaryotic species whose genome sequences are available. Histone modifying enzymes were identified applying a search pipeline built upon profile hidden Markov model (HMM) to proteomes. The database incorporates 22,169 histone-modifying enzymes identified from 342 species including 214 fungal, 33 plants, and 77 metazoan species. The dbHiMo provides users with web-based personalized data browsing and analysis tools, supporting comparative and evolutionary genomics. Based on the database entries, functional analysis of genes encoding histone acetyltransferases and histone demethylases is under way. Here I provide examples of such analyses that show how histone acetylation and methylation is implicated in regulating important aspects of fungal pathogenesis. Current analysis of histone modifying enzymes will be followed by ChIP-Seq and RNA-seq experiments to pinpoint the genes that are controlled by particular histone modifications. We anticipate that our work will provide not only the significant advances in our understanding of epigenetic mechanisms operating in microbial eukaryotes but also basis to expand our perspective on regulation of development in fungal pathogens.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.6
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• pp.131-138
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• 2014

The steel structure fabrication plant certification program was enacted as a part of the construction technology management act, article 24-3, to improve the quality of steel construction after the decay falling accident of Seongsu Bridge in 1994. However, the national certification program for structural precast concrete that is a prefabricated construction products produced by casting concrete in plant is not implemented yet. So, to introduce the proper certification system for precast concrete, the quality certification programs of North America, Europe and Japan are surveyed. In North America, the organizations that manage the plant certification programs are PCI, NPCA, CPCI and so on. Sales of precast concrete elements in Europe are governed by the construction products regulation 305/2011. Therefore, CE marking is mandatory from July 2013 for all construction products including precast concrete. In Japan, precast concrete products used in civil engineering are certificated by JIS mark, product certification system and plants for manufacturing precast concrete building elements are audited by Japan Prefabricated Construction Suppliers and Manufacturers Association. Based on these survey studies, in this paper is described an adaptation of precast concrete plant certification to comport with the certification system in Korea.

• Spatial Information Research
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• v.22 no.5
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• pp.27-41
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• 2014

Recently, BIM(Building Information Modeling) has been applied to the infrastructure such as road and bridge, and information about the outside environment of buildings is needed for maintaining and managing the large urban facilities. In addition, the convergence between spatial information and Big-data has a large potentiality, in respect that considerable profits and developments in other application problems such as various simulations and urban plans, national land security, may be brought about on the basis of the interoperability of information between BIM and GIS. Therefore, this study attempted to suggest the development direction of a model integrating building for spatial information analysis and city on the subject by comparing and analyzing difference between information system and shape expression of IFC, CityGML and LandXML to efficiently link information between IFC as a standard model of BIM and CityGML as a standard model in the GIS sector and to prepare a basic fusion strategy and a method of utilization between BIM and GIS. The result of the study are as follow. Firstly, contents and structure of IFC, CityGML and LandXML are compared and analyzed. Secondly, the development direction of iBUM(Integrated Building and Urban Model) suggested, which is based on convergence technology for analysis of space information. Finally, a strategy and method of the BIM and GIS are proposed in the iBUM environment.

• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.543-549
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• 2004

Chitosan has been widely researched as bone substitution materials and membranes in orthopedic/periodontal applications. Chitosan nanofiber membrane was fabricated by chitosan nanofiber using electrospinning technique. The structure of the membrane is nonwoven, three-dimensional, porous, and nanoscale fiber-based matrix. The aim of this study was to evaluate the biocompatibility of chitosan nanofiber membrane and to evaluate its capacity of bone regeneration in rabbit calvarial defect. Ten mm diameter round cranial defects were made and covered by 2 kinds of membranes (Gore-Tex membrane, chitosan nanofiber membrane) in rabbits. Animals were sacrificed at 4 weeks after surgery. Decalcified specimens were prepared and observed by microscope. Chitosan nanofiber membrane maintained its shape and space at 4 weeks. No inflammatory cells were seen on the surface of the membrane. In calvarial defects, new bone bridges were formed at all defect areas and fused to original old bone. No distortion and resorption was observed in the grafted chitosan nanofiber membrane. However bone bridge formation and new bone formation at the center of the defect could not be seen in Gore-Tex membranes. It is concluded that the novel membrane made of chitosan nanofiber by electrospinning technique may be used as a possible tool for guided bone regeneration.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.4
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• pp.324-329
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• 2012

Excessive tooth wear causes loss of tooth structure, disharmony of occlusal plane, functional and esthetic problems. Although the decrease of occlusal vertical dimension may be compensated by growth of alveolar bone, if the length of tooth is not enough for the retention of restoration, minimum increase of occlusal vertical dimension is required without discomfort of the patient. In this case, 33-year-old woman drinks more than 1 liter of soft drinks a day and has bruxism in night time, visited in Seoul National University Dental Hospital with chief complaint of generalized tooth wear and related esthetic and functional problems. It was considered as a loss of occlusal vertical dimension based on the accelerated tooth wear caused by erosion and bruxism and facial appearance, phonetic, esthetic, functional evaluations. It was planned to raise occlusal vertical dimension by provisional restoration two times for patient's adaptation, 3 mm and 2 mm each, total 5 mm. Confirming no discomfort and clinical symptom during total 16 weeks after restoration with provisional fixed restoration, it was restored with porcelain fused to gold crown and bridge. Because the patient was young woman, anterior teeth were restored with collarless porcelain fused to gold crown. This case presents that satisfactory esthetic and functional result by full mouth rehabilitation with increase of occlusal vertical dimension.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1115-1123
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• 2008

When constructing projects such as road embankments, bridge approaches, dikes or buildings on soft, compressible soils, significant settlements may occur due to the consolidation of these soils under the superimposed loads. The compressibility of the soil skeleton of a soft clay is influenced by such factors as structure and fabric, stress path, temperature and loading rate. Although it is possible to determine appropriate relations and the corresponding material parameters in the laboratory, it is well known that sample disturbance due to stress release, temperature change and moisture content change can have a profound effect on the compressibility of a clay. The early research of Tezaghi and Casagrande has had a lasting influence on our interpretation of consolidation data. The 24 hour, incremental load, oedometer test has become, more or less, the standard procedure for determining the one-dimensional, stress-strain behavior of clays. An important notion relates to the interpretation of the data is the ore-consolidation pressure ${\sigma}_p$, which is located approximately at the break in the slope on the curve. From a practical point of view, this pressure is usually viewed as corresponding to the maximum past effective stress supported by the soil. Researchers have shown, however, that the value of ${\sigma}_p$ depends on the test procedure. furthermore, owing to sampling disturbance, the results of the laboratory consolidation test must be corrected to better capture the in-situ compressibility characteristics. The corrections apply, strictly speaking, to soils where the relation between strain and effective stress is time independent. An important assumption in Terzaghi's one-dimensional theory of consolidation is that the soil skeleton behaves elastically. On the other hand, Buisman recognized that creep deformations in settlement analysis can be important. this has led to extensions to Terzaghi's theory by various investigators, including the applicant and coworkers. The main object of this study is to suggestion the modified compression index value to predict settlements by back calculating the $C_c$ from different numerical models, which are giving best prediction settlements for multi layers including very thick soft clay.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.61-71
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• 2010

The attributes related to the health condition of RC deck slabs are analyzed to help us identify and rate the safety level of the bridges in this study. According to the related reports the state assessment for the outward aspects of bridges is the important and critical part for rating the overall structural safety. In this respect, the careful identification for the various state attributes make the field inspection and structural diagnosis very effective. This study analyzes the influence of the state attributes on evaluation classes and the relationship of them by the inductive reasoning, which raise the understanding and performance for evaluation work, and support the logical approach for the state assessment. ID3 algorithm applied to the case set which is constructed from the field reports indicates the main attributes and the precedence governing the assessment, and derives the decision hierarchy for the state assessment.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.335-343
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• 2005

Inorganic bovine bone mineral has been widely researched as bone substitution materials in orthopedic and oral and maxillofacial application. OCS-B(NIBEC, Korea) is newly-developed inorganic bovine bone mineral. The aim of this study is to evaluate the safety and efficacy of bovine bone-derived bone graft material(OCS-B). Micro-structure of newly-developed inorganic bovine bone mineral(OCS-B) was analyzed by scanning electron microscope(SEM). Round cranial defects with eight mm diameter were made and filled with OCS-B in rabbits. OCS-B was inserted into femoral quadrant muscle in mouse. In scanning electron microscope, OCS-B was equal to natural hydroxyapatite. Rabbits were sacrificed at 2 weeks and 4 weeks after surgery and mice were sacrificed at 1 week and 2 weeks after surgery. Decalcified specimens were prepared and observed by microscope. In calvarial defects, osteoid and new bone were formed in the neighborhood of OCS-B at 2 weeks after surgery. And at 4 weeks after surgery osteoid and new bone bridge formed flourishingly. No inflammatory cells were seen on the surface of OCS-B at 1 week and 2 weeks in mouse experimental group. It is concluded that newly-developed inorganic bovine bone mineral(OCS-B) is a flourishing bone-forming material and biocompatible material.