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Comparison of shear bond strength according to porcelain build-up methods (도재 축성 방법에 따른 금속 도재관의 전단결합강도 비교)

  • Lee, Ha-Young;Cho, Jin-Hyun;Lee, Cheong-Hee
    • Journal of Dental Rehabilitation and Applied Science
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    • v.30 no.2
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    • pp.112-120
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    • 2014
  • Purpose: This study compared the shear bond strength of heat pressed and feldspathic porcelain to metal. Through thermocycling, the clinical aspect of heat pressed porcelain fused metal was estimated. Materials and Methods: 90 non-precious metal specimens were made ($4{\times}4{\times}8 mm$) and divided to three groups. All spicimens were treated and built-up with the porcelain ($4{\times}4{\times}3 mm$) by 2 different methods according to group: Group I: $Inspiration^{(R)}$, Group II: Ivoclar, IPS $Inline^{(R)}PoM$, Group III: GC Initial IQ-One $Body^{(R)}PoM$. The half of each group's specimens were thermocycled. All specimens' shear bond strength were measured by Instron universal testing machine. Exact measuring point was far 1 mm from porcelain/metal interface to the porcelain side. For the statistical analysis, 2-way ANOVA was used. Results: In no-thermocycling specimens, the shear bond strength showed no statistical significance between each group (P > 0.05). In comparison between nothermocycling and thermocycling specimens in each group, the shear bond strength was decreased according to thermocycling, but there was no statistical significance (P > 0.05). In thermocycling specimens, there was no statistical significance between each group (P > 0.05). Conclusion: In feldspathic porcelain and other two types heat pressed porcelain, there was no statistical difference in the shear bond strength of porcelain to metal. The heat pressed porcelain seems to be clinically useful for the aspect of the shear bond strength.

Microscopic Anatomy of Male Reproductive Organ in the Long Arm Octopus Octopus minor (Cephalopoda: Octopodidae) (낙지 Octopus minor 수컷 생식기관의 미세해부학적 구조)

  • Seong Jin Kim;Hyeon Jin Kim;So Ryung Shin;Myeong Gyo Seo;Pyeong Woo Kim;Eun Ha Kim;Jung Sick Lee
    • Journal of Marine Life Science
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    • v.8 no.2
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    • pp.178-185
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    • 2023
  • This study was described the microscopic anatomy of male reproductive organs and spermatophore necessary for understanding the reproductive ecology of the long arm octopus Octopus minor. The long arm octopus was a species that has sexual dimorphism that can distinguish between sex based on the presence of hectocotylus. Male reproductive organs consisted of testis, primary spermatic duct, spermatic gland, secondary spermatic duct, spermatophoric gland and spermatophoric sac. Histologically, the testis was testicular tubule type and male germ cells showed a layered arrangement. The primary spermatic duct was a tube connecting the testis and spermatic gland, and consisted with epithelial layer and connective tissue. The spermatic gland was located between the primary and secondary spermatic duct, and the epithelial layer was composed of epithelial cells and mucous cells. Mucous cells reacted blue in the AB-PAS (pH 2.5) reaction and purple in the AF-AB (pH 2.5) reaction. The secondary spermatic duct was a short tube connecting spermatic gland and spermatophoric gland, and folds were developed in lumen. The spermatophoric gland consisted of numerous tubular glands and secretory cells had eosinophilic granules. The spermatophoric sac was shape of pouch, folds were developed in lumen, and vacuolar secretory cells were present in the epithelial layer. The spermatophore was 83.5 mm long and consisted of cap thread in anterior portion, ejaculatory apparatus and cement body in medial portion, sperm mass in posterior portion.

Studies on the Charge-transfer Complex including Aflatoxin $B_1$ -Part I. Charge-transfer Complex with Benzene- (Aflatoxin $B_1$ Charge-transfer Complex에 관(關)한 연구(硏究) -제1보(第一報) Benzene과의 Charge-transfer Complex-)

  • Noh, Ick-Sam;Lee, Kang-Heup
    • Applied Biological Chemistry
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    • v.17 no.2
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    • pp.143-148
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    • 1974
  • The interaction of the carcinogenic mycotoxin, Aflatoxin $B_1$, with the electron-donating molecule, benzene, was studied spectrophotometrically. The formation of charge-transfer complex between Aflatoxin $B_1$ and benzene in the presence of zinc chloride was observed and the apparent equilibrium constant of this charge-transfer complex was found to be 0.198 (liter $mole^{-1}$). It is assumed that, as the result of this study, some charge-transfer complexes could be formed between the weak electron-accepting Aflatoxin $B_1$ and strong electron-donating molecules, and the spectral changes occurred in the binding of Aflatoxin $B_1$ with proteins or DNA is attributed to the existence of charge-transfer type interaction.

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Comparison of Bonding Strength by Cleaning Method of Pediatric Zirconia Crown Contaminated with Saliva or Blood (타액 및 혈액오염 시 유치 지르코니아 기성관 내면의 세척 방법에 따른 결합강도의 비교)

  • Kim, Jaeyong;Park, Howon;Lee, Juhyun;Seo, Hyunwoo
    • Journal of the korean academy of Pediatric Dentistry
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    • v.45 no.2
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    • pp.185-194
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    • 2018
  • The objective of this study was to compare the shear bonding strength of zirconia after cleaning the crown contaminated by saliva or blood and determine the effect of thermocycling. 180 specimens were embedded in acrylic resin. 20 Specimens in the positive control group were bonded with resin cement without contamination. 20 Specimens in the negative control group were washed with water for 20 seconds and then dried for 10 seconds. 120 Specimens contaminated by saliva or blood were cleaned by using three cleaning methods: 37% phosphoric acid gel, commercial cleanse, and 2.5% NaOCl. All samples were bonded with resin cement and divided into two subgroups: One was not aged, and the other was tested with 30,000 thermocycling. In both groups contamination by saliva and blood, no statistically significant difference was not found in control, groups cleansed by commercial cleanser and 2.5% NaOCl. When the groups cleansed with water and 37% phosphate gel were compared with the control, significantly low shear bond strength was shown. Thermocycling group showed statistically significantly low shear bond stress compared to the groups without thermocycling. When zirconia was contaminated by saliva or blood, its original shear bond strength could be obtained if it was cleaned with commercial cleanser or 2.5% NaOCl.

Revision of Geography National Curriculum in UK and Debates about Knowledge (영국 국가지리교육과정 개정과 지식 논쟁)

  • Cho, Chul-Ki
    • Journal of the Korean Geographical Society
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    • v.49 no.3
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    • pp.456-471
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    • 2014
  • Recent educational policy by coalition government in UK is called knowledge turn. A core competency-based curriculum based on the relative knowledge of the social constructivism and postmodernism has been strongly endorsed by the previous new labor government. The view of knowledge regards knowledge as constructed socially, and emphasizes personal everyday knowledge. But the knowledge-based curriculum based on absolutism is strongly endorsed by the current coalition government. It emphasizes objectivity of knowledge. Social realism criticizes both absolutism and relativism on knowledge. Social realism places disciplinary knowledge above everyday knowledge, and considers disciplinary knowledge as powerful knowledge. But it doesn't mean that social realism neglects everyday knowledge. Rather, social realism empathizes relating disciplinary knowledge to everyday knowledge. Recent Living Geography and YPG(Young People's Geographies) project by the Geographical Association is based on the social realism. The aims of the project is to connect academic geography related to young people's geographies with student's everyday geographies, and academic geographers as mentors, tutors and students together are to make school geography curriculum through conversation.

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Buckling Load and Mode Analysis of Symmetric Multi-laminated Cylinders with Elliptical Cross-section (다층 대칭배열된 타원형 적층관의 좌굴하중 및 모드해석)

  • Chun, Kyoung Sik;Son, Byung Jik;Ji, Hyo Seon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.3A
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    • pp.457-464
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    • 2006
  • Fiber-reinforced composite materials due to their high specific strength, high stiffness and light weight are becoming increasingly used in many engineering industry, especially in the aerospace, marin and civil, etc. In this paper, the buckling load and mode shapes of composite laminates with elliptical cross-section including transverse shear deformations are analyzed. For solving this problems, a versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. Also, an improved shell element has been established by the combined use of the addition of enhanced assumed strain and the substitute shear strain fields. The combined influence of shell geometry and elliptical cross-sectional parameter, fiber angle, and lay-up on the buckling loads of elliptical cylinder is examined. The critical buckling loads and mode shapes analyzed here may serve as a benchmark for future investigations.

Electron Microscopic Study on the Rabbit Inferior Lacrimal Glands (토끼 아래눈물샘의 미세구조에 관한 전자현미경적 연구)

  • Park, Young-Hee;Ahn, E-Tay;Ko, Jeong-Sik;Park, Dae-Kyoon;Kim, Myeong-Soo;Park, Kyung-Ho
    • Applied Microscopy
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    • v.37 no.1
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    • pp.23-33
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    • 2007
  • The lacrimal gland are compound tubule-acinar glands. The main lacrimal function is the production of the aqueous layer, the thickest and major constituent of the precorneal tear film. The lacrimal gland also has an important function in the defense system of the ocular surface, forming a part of the conjunctival-associated hymphoid tissue. The ultrastructural characteristics of the lacrimal gland of the rabbit were described. The lacrimal tissues of rabbits were processed through the conventional techniques for transmission electron microscopy. The secretory portions consisted of three cell types: 1. Serous cells with electron dense secretory granules. 2. Seromucous cells containing variable moderately electron dense secretory granules with flocculent material. 3. Mucous rolls containing mucous secretory granules. The serous cells were situated at the basal portion of acini, and they contained electron dense granules of variable densities and sizes. The seromucous cells contained a few protein secretory granules and more mucous secretory granules. The mucous cells contained even fewer protein secretory granules and exclusively mucous secretory granules. The epithelium of the intralobular ducts showed secretory granules, junctional complexes, and large basolateral intercellular spaces with lateral folds. These study might be helpful in determining inter-relationships, similarities and differences among the orbital glands of various physiological or pathological conditions.

Histopathological changes in fingerlings of Japanese flounder, Paralichthys olivaceus, with severe scuticociliatosis (스쿠지카섬모충에 중감염된 넙치 (Paralichthys olivaceus) 치어에 대한 병리조직학적 관찰)

  • Lee, Nam-Sil;Park, Jeong-Hee;Han, Kyu-Sik;Huh, Min-Do
    • Journal of fish pathology
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    • v.7 no.2
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    • pp.151-160
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    • 1994
  • In order to elucidate the patterns of tissue damage evoked by the scuticociliatids, eighteen fingerlings of Japanese flounder, Paralichthys olivaceus, heavily infected with an unidentified scuticociliatid were histopathologically examined. Skin layer with the underlying musculature were severely necrotized due to the infestation of the ciliates. However in the early lesions, both dermis and myofibres remained relatively intact compared with other surrounding loose connective tissues. Mild damages were found in more dense tissues. One or more scuticociliatids were recognized in the blood and lymph vessels of the loose connective tissues with or without destructive changes. Many of nerve trunks or ganglia were also parasitized with less marked histological damage in the parenchyma. Dura and its adjacent tissues in the spinal cord were severely necrotized with massive accumulation of the ciliates in subdural space. The parasitic invasion in the central nervous system was usually confined to the cortical region. In the gill, variable degenerative changes were occurred due to the invasion of the ciliates recognized in the blood vessels of branchial arches or primary filaments. From these results, it was strongly suggested that the scuticociliatids are very actively penetrated into the deep tissues mainly through the severe destruction of the loose connective tissue components and that the vascular system could play a role in the rapid distribution of the ciliates to the remote tissues or organs.

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Investigation of the Shear Bond Strength of Orthodontic Buttons by Light Curing Using an Extended Optic Fiber (광섬유를 이용한 광중합에 따른 교정용 버튼의 전단결합강도에 관한 연구)

  • Yoon, Garam;Lee, Nanyoung;Lee, Sangho;Jih, Myeongkwan;Choi, Wonseok;Sung, Minah
    • Journal of the korean academy of Pediatric Dentistry
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    • v.48 no.1
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    • pp.105-114
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    • 2021
  • The objective of this study is to analyze the shear bond strength of orthodontic buttons according to light tip distance and optic fiber diameter when an extended optic fiber was applied to the tip of a curing light unit. In this study, 315 extracted premolar teeth were divided into 3 groups. Orthodontic buttons were attached using no optic fibers (Group I), 3.0 mm diameter optic fibers (Group II), or 5.0 mm diameter optic fibers (Group III). Each group was divided into subgroups A - C (5.0, 10.0, and 15.0 mm light tip distance), respectively. Shear bond strength was then measured while varying the light tip distance. In group I, shear bond strength significantly decreased as the light tip distance increased. When the shear bond strength was evaluated according to the optic fiber diameter, no statistical significance was observed in group of 5.0 mm light tip distance. Compared with group IB, group IIIB showed significantly greater shear bond strength. Compared with group IC, all groups using 3.0 or 5.0 mm diameter optic fibers showed significantly greater shear bond strength. Therefore, when a curing light unit has poor accessibility, optic fibers with a large diameter should be considered.

Bundled Discounting of Healthcare Services and Restraint of Competition (의료서비스의 결합판매와 경쟁제한성의 판단 - Cascade Health 사건을 중심으로 -)

  • Jeong, Jae Hun
    • The Korean Society of Law and Medicine
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    • v.20 no.3
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    • pp.175-209
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    • 2019
  • The bundled discounting which the dominant undertakings engage in is problematic in terms of competition restraint. Bundled discounts generally benefit not only buyers but also sellers. Specifically, bundled discounts usually costs a firm less to sell multiple products. In addition, Bundled discounts always provide some immediate consumer benefit in the form of lower prices. Therefore, competition authorities and courts should not be too quick to condemn bundled discounts and apply the neutral and objective standard in bundled discounting cases. Cascade Health v. Peacehealth decision starts ruling from this prerequisite. This decision pointed out that the dominant undertaking can exclude rivals through bundled discounting without pricing its products below its cost when rivals do not sell as great a number of product lines. So bundled discounting may have the anticompetitive impact by excluding less diversified but more efficient producers. This decision did not adopt Lepage case's standard which does not require the court to consider whether the competitor was at least as efficient of a producer as the bundled discounter. Instead of that, based on cost based approach, this decision said that the exclusionary element can not be satisfied unless the discounts result in prices that are below an appropriate measures of the defendant's costs. By adopting a discount attribution standard, this decision said that the full amount of the discounts should be allocated to the competitive products. As the seller can easily ascertain its own prices and costs of production and calculate whether its discounting practices exclude competitors, not the competitor's costs but the dominant undertaking's costs should be considered in applying discount attribution standard. This case deals with bundled discounting practice of multiple healthcare services by the dominant undertaking in healthcare market. Under the Korean healthcare system and public health insurance system, the price competition primarily exists in non-medical care benefits because public healthcare insurance in Korea is in combination with the compulsory medical care institution system. The cases that Monopoly Regulation and Fair Trade Law deals with, such as cartel and the abuse of monopoly power, also mainly exist in non-medical care benefits. The dominant undertaking's exclusionary bundled discounting in Korean healthcare markets may be practiced in the contracts between the dominant undertaking and private insurance companies with regards to non-medical care benefits.