• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.6
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• pp.113-118
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• 1999

In order to evaluate strength of spot welded joint, at first it is importent that we should know strain distribution near nugget zone. During loading, in HAZ, compressive strain increase with Increase of load, but in nugget zone tensile strain increase. During unloading, on the other hand, even through the decreases, the strain variation is not almost appeared in nugget zone and HAZ. In nugget boundary zone, the strain range increases continuously along with load increase on outer surface, but the strain increases continunously and decreases rapidly beyond yield strength on inner surface. In this paper, strain distribution are measured in inner and outer surface with variation of thickness and load under tensile-shear load. Tensile-shear strength increased as with increase of specimen thickness. As for thickness increase rates are 25%, 50%, 100%, and 150%, tensile-shear strength in crease rates are 40%, 81%, 130% and 228%.

• Journal of Technologic Dentistry
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• v.34 no.1
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• pp.1-9
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• 2012

Purpose: The purpose of this study was to investigate the transmittance differences of pressable ceramic core due to thickness within the visible light spectrum. Methods: 36 specimens were divided into 2 groups (0.6mm, 0.8mm) which have each 3 specimens. The size of specimens was 10mm high and 10mm wide. The transmittance of specimens are measured by spectrophotometer Model Cary 500 that can measure infrared-ray, visible wave and ultraviolet-ray. Results: The results shows that there was no significant difference between specimen's thickness(0.6mm, 0.8mm) and transmittance. Conclusion: The individual's color perception is personal and there are numerous factors that influence on it. In general, human eye can perceive the color of thing only within visible light spectrum but in this experiment through spectrophotometer there was no big difference between specimen's thickness(0.6mm, 0.8mm) and transmittance. To sum up, The most important factors were a layed porcelain structure and its thickness rather than core thickness in the porcelain crown. Also, When making all ceramic core with dead pulp (nervous treatment tooth) when used as a restorative esthetic think is more efficient to improve.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.604-607
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• 2000

All of rubber tubes for force pump are imported from aboard there for locallization of these tubes is make a great contribution of Korean industry In this study compare with existing product of japan and designed the new one that is for our actual circumstances. Experimental work was performed to two kinds of specimen and compression test is performed for them. As a result specimen type A has a better restoration than other and minimum thickness is must over 12mm.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.1
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• pp.213-221
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• 2002

This paper presents the experimental result of Reinforced Concrete column-steel beam joint connected by Band Plates(BP). Main parameters in the test are the shape of BP and thickness of plate. Ten interior and exterior RC column-steel beam joint specimens are designed. Cyclic loads are applied to the beam end of eight specimens (four interior specimens and four exterior specimens). To evaluate the cyclic effect, monotonic loads are acted for two specimens. All specimen showed similar failure pattern such as the plate of BP get torn after the large deformation. Even though the specimen with double cross type BP has lower strength than the specimen with single cross type BP, the energy dissipation capacity of the specimen turned out high. Thus, provided the strength of joint with double cross type to be designed to have suitable strength by increasing the thickness of plate, the joint system may show higher seismic capacity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1382-1385
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• 2003

Deformation on shapes of the hydrogen absorption metal in this paper was investigated on hydrogen absorption-desorption cycling. In order to study this problem, the cold rolled palladium plate and the cold extrusion palladium bar as specimens had been used. By using the electrochemical method, the palladium specimens were cyclically hydrogenated in the 0.1 mol H$_2$SO$_4$ electrolyte. As results, it is noted that the thickness of the plate specimen gradually increased in increasing hydrogenation cycles whereas the width and the length decreased. But both the diameter and the length of the bar specimen increased with increasing hydrogenation cycles. Also, grains in the plate specimen were greatly deformed after hydrogenation cycling whereas internal grains in the bar specimen were pulverized. And deterioration of the hydrogen absorption rate of the bar specimen was lager than the plate specimen.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.587-598
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• 2005

Statement of problem: Ceramic restorations should be made of porcelain layers of different opacity, shade, and thickness in order to provide a natural appearance. Lithium disilicate glass-ceramic system has superior color reproducibility, because it uses the ceramic ingot which is similar to teeth shade and uses the staining technique and layering technique. However, staining technique has a fault of discoloration. Also, porcelain is divided core and dentin layer, it is not enough to study about the influence of porcelain layer thickness and shade on the shade of ceramic restorations. Purpose: The purpose of this study was to evaluate the influence of porcelain layer thickness and color on the final shade of ceramic restorations. Materials and method: The CIE $L^*a^*b^*$(CIELAB) values of 72 assembled specimens, each consisting of 3 discs (enamel porcelain 0.2 mm/dentin porcelain -1.2, 0.9, 0.7, 0.5 or 0.3 mm/ceramic core -0.3, 0.5, 0.7, 0.9 or 1.2 mm, diameter is 1.0 mm) were evaluated with a spectrophotometer (Model Chromaview 300, Spectron Tech Co, Korea) for the shade A1, A2, A3 and A4. Distilled water (refractive index: 1.7) was used to attain optical contact between the layers. White, white gray, and white brown backgrounds were used to assess the influence of the background on the final shade. And the mean color difference value$({\Delta}E)$ was calculated. Results and conclusion: The results obtained from this study were as follows. 1. There was a significant correlation between the thickness ratio of the ceramic core/dentin porcelain system and $L^*,\;a^*\;and\;b^*$ values when the total thickness of specimen combination was smaller than 1.4 mm(P<0.05). 2. The specimen which the ceramic core thickness was more than 0.7 mm had the best masking effect against background colors. 3. The mean color difference value$({\Delta}E)$ is smaller than 2 $({\Delta}E<2)$ when the ceramic core thickness was larger than 0.7 mm and the total thickness of specimen was more than 1.4 mm.

• Korean Journal of Metals and Materials
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• v.48 no.8
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• pp.705-716
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• 2010

Effects of specimen thickness and notch shape on fracture mode appearing in drop weight tear test (DWTT) specimens of API X70 and X80 linepipe steels were investigated. Detailed microstructural analysis of fractured DWTT specimens showed that the fractures were initiated in normal cleavage mode near the specimen notch, and that some separations were observed at the center of the fracture surfaces. The Chevron-notch (CN) DWTT specimens had broader normal cleavage surfaces than the pressed-notch (PN) DWTT specimens. Larger inverse fracture surfaces appeared in the PN DWTT specimens because of the higher fracture initiation energy at the notch and the higher strain hardening in the hammer-impacted region. The number and length of separations were larger in the CN DWTT specimens than in the PN DWTT specimens, and increased with increasing specimen thickness due to the plane strain condition effect. As the test temperature decreased, the tendency to separations increased, but separations were not found when the cleavage fracture prevailed at very low temperatures. The DWTT test results, such as upper shelf energy and energy transition temperature, were discussed in relation with microstructures and fracture modes including cleavage fracture, shear fracture, inverse fracture, and separations.

• Journal of the Korean institute of surface engineering
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• v.53 no.1
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• pp.29-35
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• 2020

In this study, five different specimen preparation methods were introduced and their advantages and disadvantages were presented. One of them, an epoxy mounting method has advantages of constant exposure area, ease of surface preparation without touching the specimen surface during polishing or cleaning, use of small amount of material and ease of specimen reuse by polishing or etching. However, in order to eliminate unexpected errors resulting from preferable reaction at the specimen/epoxy interface and contact resistance between the specimen and copper conducting line for electrical connection, it is recommended to cover the wall side of the specimen with porous anodic oxide films and to remain the contact resistance lower than 1 ohm. The increased contact resistance between the specimen and Cu conducting line appeared to result in increases of anodizing voltage and solution temperature during anodizing by which thickness and hardness of anodizing film on Al2024 alloy were drastically decreased and color of the films became more brightened.

• Korean Journal of Materials Research
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• v.29 no.8
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• pp.497-504
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• 2019

In this study, the correlation between microstructure and Charpy impact properties of FCAW(Flux cored arc welding) HAZ(Heat affected zone) of thick steel plates for offshore platforms was investigated. The 1/4 thickness(1/4t) location HAZ specimen had a higher volume fraction of bainite and finer grain size of acicular ferrite than those of the 1/2 thickness (1/2t) location HAZ specimen because of the post heat effect during the continuous FCAW process. The Charpy impact energy at $-20^{\circ}C$ of the 1/4t location HAZ specimen was lower than that of the 1/2t location HAZ specimen because of the high volume fraction of coarse bainite. The Charpy impact energy at -40 and $-60^{\circ}C$ of the 1/2t location HAZ specimen were higher than those of the 1/2t location HAZ specimen because the ductile fracture occurred in the fine acicular ferrite and martensite regions. In the ductile fracture mode, the deformed regions were observed in fine acicular ferrite and martensite regions. In the brittle fracture mode, long crack propagation path was observed in bainite regions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1561-1567
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• 1990

Recently, some reports of experimental research on the distribution of fatigue crack propagation rate have been published, and the reliability evaluation using the results of research for the mechanical structure has been executed. Since the thicknesses of specimens used in the published reports are limited to the thin ones, the applicability of the results into the mechanical structure with another thickness seems to be doubtful. That is, not only the quantitative evaluation, but also qualitative evaluation of the effect of specimen thickness has not been executed. In this study, an experimental investigation has been done by using the new type automated multi-stage fatigue testing machine which was developed by the author. The influence of specimen thickness for the distribution of fatigue crack propagation rate with the results is discussed.