• Restorative Dentistry and Endodontics
• /
• v.21 no.1
• /
• pp.136-149
• /
• 1996

The effects of various All-Etching Agents (10% phosphoric acid, 10% maleic acid and 10 % citric acid) and 32 % phosphoric acid and varied etching time were evaluated by observing the morphology of the etched enamel surfaces using Scanning electron microscopy and by measuring the shear bond strength of a composite resin to human enamel. A total of 156 extracted premolar and molar teeth free of irregularities were employed in this study. Specimens for the observation of enamel morphology were divided into 12 groups of 3 teeth each, based on the type of etchant used and application time. After exposure to the etching agent specimens were washed air-dried and then glued to aluminum stubs and coated with a layer of gold for examination in the scanning electron microscope. Specimens for the evaluation of bond strength were divided into 12 groups of 10 teeth each also based on the type of etchant used and application time. After exposure to the etching agent the specimens were washed, air-dried and a thin layer of bonding agent was applied using a brush. Z 100 composite resin was light cured to the surface and stored at $37^{\circ}C$, 100% humidity for 7 days. An Instron Universal Testing Machine was used to apply a shearing force at $90^{\circ}$ angle from the enamel surface. It is concluded from this study that commercial All-etching agents can be used with a 15-second etching without adversely affecting retention of dental resin materials. At the same time, the acid concentration is probably a suitable compromise regarding the acid's function as a dentin demineralizing all-etch conditioning agent. The following results were obtained. 1. Specimens etched with 10 % citric acid showed a random superficial etching pattern which could not be related to prism morphology. 2. Specimens etched with 10 % and 32 % phosphoric acid and 10 % maleic acid showed a type I pattern in which core material was preferentially removed leaving the prism peripheries relatively intact or a type II pattern in which prism peripheries were preferentially removed. This delineation became more distinguished as etching time was increased. 3. All-Etching Agents and 32 % phosphoric acid showed a statistically significant higher shear bond strength at 15 seconds etching time.(p<0.05) 4. 10 % maleic acid and 32 % phosphoric acid exhibited a statistically significant higher shear bond strength than 10 % phosphoric and citric acid at 15 seconds etching time.(p<0.05).

• Journal of Korean Society of Steel Construction
• /
• v.17 no.5 s.78
• /
• pp.561-568
• /
• 2005

The object of this paper is to determine appropriateness for use of high-strength tensile bar as a tension web member. The gap K-joint of tensile bar types were compared with gap K-joint of square hollow section (SHS) types. For the same width-to-thickness ratio ($2{\gamma}=33.3$ ), tests were performed on four specimens of the SHS type and eight specimens of the tensile bar type. The comparison of capacity with the experimental results showed a capacity of the SHS type joint to be higher than that of the tensile bartype joint for the same brace-to-chord width ratio. Moreover, the capacity of the SHS type joints increased proportionally to the width ratio ${\beta}$), while tensile bar type joints increased as the tension width ratio (${\beta}2$). In failure mode, SHS-type specimens showed local buckling of the compression brace and plastic failure was observed between the tension brace and chord face, and with the tensile bar type specimens there appeared punching shear failure of the chord face at the toe of the connection plate. It is, therefore, concluded that width-to-thickness ratio should be lower than that of the hollow-section type and the relation between tension and compression width ratio should be considered.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.1
• /
• pp.1-5
• /
• 2018

The present study investigated the characteristics of vertical sagging down of high temperature in chamber and characteristics of vertical sagging down in the outdoor asphalt sheet and asphalt seal under korea ltimate condition using asphalt seal products of solvent based type, solventless type, water dispersion type, and heat melting type, which are currently applied in Korea. Prior to the investigation of outdoor vertical sagging down characteristics, the assessment of sagging down performance of single use of sealing products at $20^{\circ}C$, $40^{\circ}C$, $60^{\circ}C$ was conducted and the result showed that sagging down did not occur at $20^{\circ}C$ but some solventless type, water dispersion type specimens at $40^{\circ}C$ had sagging down up to 10 mm. In addition, some solventless type, water dispersion type specimens had sagging down up to 55 mm at $60^{\circ}C$. For specimens to which asphalt seal and renovated asphalt sheet were layered over the outdoor concrete vertical surface, sheet sagging and sagging down occurred up to 50 mm in water dispersion specimens after three month later since the construction in summer.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.5
• /
• pp.3005-3010
• /
• 2013

Background: To present the overall clinical and histological perspective of benign and malignant prostatic disease as seen in our practice in the Section of Histopathology, Department of Pathology and Microbiology, Aga Khan University Hospital, Karachi, Pakistan. Materials and Methods: All consecutive prostate specimens (transurethral resection or TUR, enucleation, needle biopsies) received between July 1, 2012 and December 31, 2012 were included in the study. Results: Of the total of 785 cases, 621 (79.1%) were TUR specimens, 80 (10.2%) enucleation specimens, and 84 (10.7%) needle biopsies. Some 595 (75.8%) were benign, while 190 (24.2%) were malignant. Mean weight of BPH specimens was 19 grams and 43 grams for TUR and enucleation specimens respectively. Almost 67% of adenocarcinomas were detected on TUR or enucleation specimens. Of the above cases, 41.7% were clinically benign while 58.3% were clinically malignant. The average volume of carcinoma in all cases ranged between 60 to 65%. The average number of cores involved in needle biopsies was 5. In general, higher Gleason scores were seen in TUR/enucleation specimens than in needle biopsies. Overall, in all types of specimens, commonest Gleason score was 7, seen in 74 (38.9%) cases, followed by Gleason score 9 seen in 47 (24.7%) cases. Out of the 63 needle biopsies with carcinoma, radical prostatectomy was performed in 16 cases (25.4%). Conclusions: Benign prostatic hyperplasia (BPH) is extremely common and constitutes the bulk of prostate specimens. TMajority of prostatic carcinomas are still diagnosed on TUR or enucleation specimens. These included both clinically benign and clinically malignant cases. The volume of carcinoma in these specimens was quite high indicating extensive disease. Gleason scores were also generally high compared with scores from needle biopsies. Commonest Gleason score in all type of specimens was 7. Pathologic staging was possible in very few cases since radical prostatectomies are rarely performed.

• Journal of Korean Neurosurgical Society
• /
• v.40 no.6
• /
• pp.445-449
• /
• 2006

Objective : The accurate anatomy of the facial nerve is essential for successful surgical outcome. The purpose of the present study is to know such information on the facial nerve from a series of specimens. Methods : This study is based on cadaveric dissection of 41 Korean fetus and stillborn infant and describes anatomical variations of the peripheral branches of the facial nerve that pose a importance in a number of neruosurgical procedure. Results : The branching patterns were classified into six types according to modified Davis classification : the frequencies of occurrence were : type I, 4.9%; type II, 24.4%; type III, 34.1%; type IV, 19.5%; type V, 12.2%; and type VI, 4.9%. Types II, III and IV together accounted for almost 80% of the specimens. Conclusion : Compared to previous adult and western stillborn fetus cadaveric studies, there was no significant difference in the percentage of the types between the subjects in the present study, similar pattern and anatomic distribution.

• Corrosion Science and Technology
• /
• v.7 no.3
• /
• pp.168-172
• /
• 2008

A new type of electrochemical random signal (electrochemical noise) analysis technique was applied to localized corrosion of anodic oxide film formed 1100 aluminum alloy in $0.5kmol/m^3$ $H_3BO_4/0.05kmol/m^3$ $Na_2B_4O_7$ with $0.01kmol/m^3$ NaCl. The effect of anodic oxide film structure, barrier type, porous type, and composite type on galvanic corrosion resistance was also examined. Before localized corrosion started, incubation period for pitting corrosion, both current and potential slightly change as initial value with time. The incubation period of porous type anodic oxide specimens are longer than that of barrier type anodic oxide specimens. While pitting corrosion, the current and potential were changed with fluctuations and the potential and the current fluctuations show a good correlation. The records of the current and potential were processed by calculating the power spectrum density (PSD) by the Fast Fourier Transform (FFT) method. The potential and current PSD decrease with increasing frequency, and the slopes are steeper than or equal to minus one (-1). This technique allows observation of electrochemical impedance changes during localized corrosion.

• Electrical & Electronic Materials
• /
• v.9 no.10
• /
• pp.1053-1059
• /
• 1996

The pulse-echo response of the piezoceramics PZT-polymer 3-3 type composite transducers with various PVA additions were investigated. The PZT powder was prepared by the molten salt synthesis method. The porous PZT specimens will be used as a filler to make 3-3 type comosite were prepared from a mixture of PZT and polyvinylalcohol(PVA) sphere by utilizing BURPS(Bumout Plastic Sphere) technique. It was shown that the transmitting and receiving sensitivity of 3-3 type piezoelectric composite transducers could be improved than that of solid PZT transducers. The reason is that 3-3 type piezoelectric composite have low dielectric constant, density and acoustic impedance. The distance between transducer and reflector was in good agreement with the distance calculated from the longitudinal velocity of the specimens and receiving time observed pulse-echo responses on the ultrasonic transducer analyzer.

• Journal of Species Research
• /
• v.9 no.4
• /
• pp.375-376
• /
• 2020

A type specimen is the specimen originally used to name a new species; thus, it is one of the most significant materials for taxonomic study. In our study on the inventory and management of endemic species in Korea, we checked the type materials for Pseudolysimachion pusanensis (Y. Lee) Y. Lee, combination name Veronica pusanensis Y. Lee, recorded as deposited at the herbaria of the Ewha Womans University and the National Institute of Biological Resources, and failed to find any specimens. Thus, we concluded that all type specimens of V. pusanensis have since been misplaced. According to articles 9.11 and 9.13 of the International Code of Nomenclature for algae, fungi, and plants, it is necessary to select a neotype if the holotype is missing and no other original material exists. Therefore, we designate the neotype maintained in the herbarium of the National Institute of Biological Resources of the Republic of Korea.

• Journal of the Semiconductor & Display Technology
• /
• v.11 no.3
• /
• pp.63-67
• /
• 2012

The films were deposited at evaporator system and were annealed at heat treatment. The films had a dense microstructure with fine grains. The electrical properties of the films were dramatically controlled with annealing. Samples Preparation were analyzed in term of positive temperature coefficient of Resistivity Samples were made in the substrate tempera-true of $400^{\circ}C$ deposition time of 10 hours, and forward power of 210watt. R-T(resistivity-temperature) Characteristics of the samples were investigated as a function of the substrate type and the ambient temperature. The resistivity of the thin film specimens was compared with that of the bulk type specimens. By using RF/DC magnetron sputtering system, we obtained lower resistivity in the thermistor with thin $BaTiO_3$ film than that in the bulk type thermistor.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.22-23
• /
• 2017

The purpose of this study is to ascertain self-healing function on microcracks in bisphenol F-type epoxy-modified mortars using expansive admixtures. The specimens are prepared with various polymer-binder ratios of 0, 5, 10, 20%, expansive admixture contents of 0% and 10%, a sodium carbonate content of 0.25%, and subjected to exposure conditions of CR1, CR2, CR3 and CR4. The specimens are tested for self-healing effect, porosity and FE-SEM analysis. As a result, self-healing effects of bisphenol F-type EPMMs with expansive admixtures are visible in all of the outdoor exposure conditions. In particular, exposure conditions of CR3 and CR4 are most noticeable. And the porosity of EPMMs is reduced with an increase in the polymer-binder ratio, and is considerably smaller than that of unmodified mortar.