• Journal of the korean academy of Pediatric Dentistry
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• v.31 no.3
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• pp.355-361
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• 2004

Impaction is generally defined as the lack of eruption of a tooth after the normal age for the eruption. An impacted tooth may appear blocked by another tooth, bone, or soft tissue, but cause of tooth impaction is often unknown. The clinician should consider the various treatment options available : (a) No treatment and observation, (b) surgical exposure and orthodontic traction (c) auto transplantation (d) extraction. These cases were about the patients with delayed eruption of maxillary central incisor. We surgically exposed impacted tooth and guided it into normal position by the orthodontic traction. Especially, in case 1, #21 was ectopic impacted state with root dilaceration. It is required to examine further root development and alignment of dentition serially.

• The korean journal of orthodontics
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• v.35 no.5 s.112
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• pp.381-387
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• 2005

The aim of this study was to compare the clinical performance of 4 types of orthodontic wires, indicated for initial tooth alignment: stainless steel, multistranded steel, superelastic and thermoactivated nickel-titanium. A prospective randomized clinical trial was conducted on a sample of 45 patients, at the Dental School of the State University of Rio do Janeiro, Brazil. Fixed appliances were fitted and study casts were obtained from each patient. Randomly, the wires were allocated as follows: 26 dental arches for superelastic NiTi wires, 22 for stainless steel, 22 for multistranded and 20 for thermoactivated archwires. After 8 weeks, the archwires were removed and impressions for study casts were taken again. Using a 3D digitization technique of defined anatomical points on the study cast crowns, a Dental Irregularity Index (DII) was created for each study cast. The difference between DII before and after the archwire insertion expressed the aligning effect of the wires. ANOVA tests were employed to evaluate the anatomical point approximation (positive DII) and separation (negative DII), for each area of the dental arches: upper and lower whole arch and anterior arch. Results showed no significant difference between the different archwires.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.171-179
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• 2013

Arginine kinase (ArK) is known to play an important role in most invertebrates the level of ATP by phosphorylation of phosphagens in cell and immuninty in living organisms. ArK has been identified in many kinds of organisms ranging from invertebrate to vertebrate. However, no ArK gene has been cloned and investigated from N. samarangae. This leads us to identify ArK cDNA (NsArK) from the expressed sequence tag (EST) sequencing of N. samarangae. Sequence analysis indicated that the coding region of 1,065 bp contains 355 amino acid residues. Molecular phylogenetic analysis shows that NsArK had very high similarities with mollusca and arthropoda. In an attempt to investigate a potential role of NsArK in the digestive gland of N. samarangae, expression patterns were analyzed. RT-PCR analsysis shows that NsArK mRNA is induced in the rane of 1.2 fold at 6 hr by laminarin when compared with the control. The immunnologial and physiological role of NsArK remains to be further investigated in N. samarangae.

• Journal of the Society of Naval Architects of Korea
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• v.55 no.1
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• pp.66-74
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• 2018

In order to evaluate the precision degree of the blocks on the dock, the shipyards recently started to use the point cloud approaches using the 3D scanners. However, they hesitate to use it due to the limited time, cost, and elaborative effects for the post-works. Although it is somewhat traditional instead, they have still used the electro-optical wave devices which have a characteristic of having less dense point set (usually 1 point per meter) around the contact section of two blocks. This paper tried to expand the usage of point sets. Our approach can estimate the rework time to weld between the Pre-Erected(PE) Block and Erected(ER) block as well as the precision of block construction. In detail, two algorithms were applied to increase the efficiency of estimation process. The first one is K-mean clustering algorithm which is used to separate only the related contact point set from others not related with welding sections. The second one is the Concave hull algorithm which also separates the inner point of the contact section used for the delayed outfitting and stiffeners section, and constructs the concave outline of contact section as the primary objects to estimate the rework time of welding. The main purpose of this paper is that the rework cost for welding is able to be obtained easily and precisely with the defective point set. The point set on the blocks' outline are challenging to get the approximated mathematical curves, owing to the lots of orthogonal parts and lack of number of point. To solve this problems we compared the Radial based function-Multi-Layer(RBF-ML) and Akima interpolation method. Collecting the proposed methods, the paper suggested the noble point matching method for minimizing the rework time of block-welding on the dock, differently the previous approach which had paid the attention of only the degree of accuracy.

• Korean Journal of Cognitive Science
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• v.10 no.3
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• pp.51-66
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• 1999

Selective attention induces perceptual distortions. ranging from repulsion of objects located near the attended area(Suzuki & Cavanagh. 1997) to magnification of the u unattended objects (Tsal & Shalev. 1996). Two hypothetical mechanisms have been p postulated: a shift of receptive fields' positions away from the locus of attention(receptive-field-recruitment hypothesis) or the enlargement of perceived space around the a attended location(space-enlargement hypothesis). The present study distinguished between these hypotheses by investigating the spatial and temporal properties of attention-induced d distortions. Perceptual judgements on vernier alignment. line tilt. line length were used to measure attention-induced changes in perception. Attention was induced exogenously(by blinking a specific set of dots around the test stimuli} or endogenously(by instructing the subject to selectively attend the dots). After inducing attention. the test stimuli were briefly flashed. A staircase method was used to measure the attentional effect. A vertical line was perceived as repelled from the locus of attention. and a line segment appeared longer when attention was given to its vicinity. The effects decreased as the distance between the locus of attention or the time between the onset of attention and the stimulus presentation increased. The results imply that the space-enlargement hypothesis provides a better explanation for the attention-induced changes in perception than the receptive-field-recruitment hypothesis.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.

• Korean Journal of Poultry Science
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• v.50 no.4
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• pp.231-240
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• 2023

Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive disease in young chickens, and causes considerable economic losses to the poultry industry. More than 30 years ago, an antigenic variant IBDV (avIBDV) was reported in chicken farms in the United States. Recently, a novel avIBDV exhibited clear differences in molecular characteristics compared with previous variant strains. This study investigated the molecular characteristics of recently isolated avIBDV strains in Korea. Strains of avIBDV were confirmed by reverse transcription PCR (RT-PCR) and were propagated in 10-day-old specific-pathogen-free (SPF) embryonated chicken eggs through chorioallantoic membrane (CAM) inoculation. Multiple sequence alignment and phylogenetic analyses of hypervariable regions VP2 gene revealed that the strains originated from two different avIBDV lineages (G2a and G2d). In our results, we confirmed the co-existence and prevalence of avIBDV genogroup G2a and G2d in chicken farms. It is necessary to study the protective efficacy of current vaccines against avIBDVs.

• The Korean Journal of Malacology
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• v.24 no.1
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• pp.73-80
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• 2008

Numerous morphological studies on N. samarangae have been well conducted over the last ten years. In this context, we have attemtped to do molecular phylogenetic analysis by using metallothionein (MT) gene from N. samarangae. To this end, we cloned the full length cDNA of MT from cDNA library of N. samarangae. The complete cDNA sequences were obtained from the expressed sequence tag (EST) sequencing project of N. samarangae, The coding region of 195 bp gives an amino acid sequence of 65 residues including methionine. There are 5' (61 bp) and 3' (48 bp) untranslated region at both ends of the Ns-MT cDNA sequence. The combined results from BLAST analyses, multiple sequence alignment and molecular phylogenetic study of Ns-MT cDNA indicate that N. samarangae has similarity to land snails such as Helix pomatia, Helix aspersa and Arianta arbustorum.

• The Korean Journal of Malacology
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• v.25 no.2
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• pp.153-160
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• 2009

Pisidium (Neopisidium) coreanum is a freshwater snail and lives in spring water near mountain areas. Interestingly, this snail has been traditionally regarded as medicinal food, and thus has been used as folk remedies for healing broken bones. Recently, alpha classification on Pisidium (Neopisidium) coreanum through redescription has been conducted. However, not much attention has been made in beta classification. In this study, we performed the beta classification based on metallothionein (MT) genes found from various organisms. To this end, the complete cDNA sequences were obtained from the Expressed Sequence Tag (EST) sequencing project of Pisidium (Neopisidium) coreanum. The coding region (315 bp) encoded an amino acid sequence of 105 residues. The combined results from BLAST analyses, multiple sequence alignment and molecular phylogenetic study of Pc-MT gene indicate that Pisidium (Neopisidium) coreanum has similarity to freshwater bivalve such as Dreissena polymorpha (zebra mussel), Unio tumidus (swollen river mussel) and Crassostrea ariakensis (suminoe oyster).

• Radiation Oncology Journal
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• v.14 no.1
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• pp.77-85
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• 1996

Purpose : Multileaf collimator(MLC) is very suitable tool for conformal radio-therapy and commissioning measurements for a multileaf collimator installed on a dual energy accelerator with 6 and 10MV photons are required, For modeling the collimator with treament planning software, detailed dosimetric characterization of the multileaf collimator including the penumbra width, leaf transmission between leaf leakage and localization of the leaf ends and sides is an essential requirement. materials and Methods : Measurement of characteristic data of the MLC with 26 pair block leaves installed on CLINAC 2100C linear accelerator was performed. Low sensitive radiographic film(X-omatV) was used for the penumbra measurement and separate experiments using radiographic film and thermoluminescent dosimeters were performed to verify the dose distribution, Measured films were analized with a photodensitometer of WP700i scanner. Results : For 6 & 10 MV x-ray energies, approximately $2.0\%$ of photons incident on the multileaf collimator were transmitted and an additional $0.5\%$ leakage occurs between the leaves. Localizing the physical end of the leaves showed less than 1mm deviation from the $50\%$ decrement line and this difference is attributed to the curved shaped end on the leaves One side of a sin히e leaf corresponded to the $50\%$ decrement line, but the opposite face was aligned with a lower value. This difference is due to the tongue and groove used to decrease between leaf leakage. Alignment of the leaves to form a straight edge resulted larger penumbra at far position from isocenter as compare with divergent alloy blocks. When the MLC edge is stepped by sloping field, the isodose lines follow the leaf pattern and Produce scalloping isodose curves in tissue. The effective penumbra by 45 degree stepped MLC is about 10mm at 10cm depth for 6MV x-ray. The difference of effective penumbra in deep tissue between MLC and divergent alloy blocks is small (5mm). Conclusion : Using the characteristic data of MLC, the MLC has the clinlical acceptability and suitability for 3-D conformal radiotherapy except small field size.