• Restorative Dentistry and Endodontics
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• v.8 no.1
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• pp.161-166
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• 1982

The purpose of this study was to examine the influence of canal preparation on the property of apical seal. Seventy canals from extracted human maxillary and mandibular teeth were randomly selected and divided into two groups: conventional group and step-back group. Thirty five canals in one group were enlarged with a, conventional preparation method and thirty five canals in the other group were instrumented in a step-back method with K-file. After instrumentation sixty canals were obturated by lateral condensation of gutta percha and zinc oxide eugenol cement, and five canals in each group were not filled and used as control. All the specimens were immersed in 2% methylene blue dye solution and the depth of dye penetration into the canals were observed by macroscope at the intervals of 1 day, 2 days, and 7 days. The following results were obtained. 1. All the canals experimented showed varying degrees of dye penetration. 2. There was no significant difference between conventional method and step-back method in the depth of dye penetration and the degree of dye penetration tended to increase with time passage in both groups. 3, In conventional preparation group the mean dye penetration was 3.6mm at 1 day, 4.8mm at 2 days. and 6.5mm at 7 days. 4. In step-back prepareation group, the specimens exposed to the dye for 1 day showed mean dye penetration of 4.1mm, and the specimens immersed in the dye for 2 days and 7 days revealed mean dye penetration of 4.6mm and 6.2mm respectively.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.335-340
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• 2010

This paper is about a projection method to check existence of radius groove penetration of screw after distal radius fracture operation using the T-type plate. Angle of Radius groove was analyzed by fifty one CT images that contains patients' wrist and twenty cases of radius specimens. After making radius phantom by plaster, we set the screw so that it penetrated 2.4 mm depth of radius groove. Then, we projected the phantom by X-ray in change of the elevation and supination angle of distal radius by 5 degree interval on 0~30 degree. The average value of groove angle in the wrist CT images was 14.4 degree and the radius specimens was 16.3 degree. Screws penetrating radius groove of the phantom have different lengths according to elevation angle and supination angle. Consequently, in order to confirm existence and nonexistence of radius groove penetration of the screw in tangential projection after distal radius fracture operation using the T-type plate, we recommend 5 degree of elevation angle and 20 degree of supination angle.

• Clinical and Experimental Reproductive Medicine
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• v.19 no.2
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• pp.153-162
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• 1992

To solve the logistical problems of the sperm penetration assay (SPA) to provide just a sufficient number of hamster ova exactly when they are needed, a new method to cryopreserve the ova has been devised (1-step dehydration and 2-step thawing). After freezing & thawing of zona-intact (ZI) and zona-free (ZF) hamster ova according to this new method, the frozen-thawed ova were compared with fresh, control ova (FO) in terms of the degree of sperm penetration in SPA using semen samples from fertile donors, subfertile, and infertile male. Each sperm sample was capacitated for 42 hours inTEST-Yolk Buffer before insemination in SPA. In fertile doner, both the penetration rate and penetration index were lower in SPA using frozen ova (ZI; 92.4%, 6.2, ZF; 63.7%, 3.9) than those of SPA using fresh ova (99.3%, 8.4). There was a significant correlation between the penetration index of SPA using FO and ZI (p<0.001), and between those of SPA using FO and ZF and ova (p<0.001). In subfertile patient, both the penetration rate and penetration index were lowered in frozen ova (ZI; 62.3%, 1.3, ZF; 21.8%, 0.4) than those of fresh ova (74.8%, 1.8). There were significant correlation between the penetration rate and penetration index in ZI ova (p<0.05 and p<0.001, respectively). In infertile patient, both the penetration rate and penetration index were ZI; 3.1%, 0.0, ZF;0.0%, 0.0, respectively. There were significant correlation between the penetration rate and penetration index in ZI ova (p<0.05).

• KOREAN JOURNAL OF CROP SCIENCE
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• v.39 no.3
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• pp.205-210
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• 1994

This experiment was conducted to investigate of soil hardening degree before sowing, furrow depth at sowing and flooding time after sowing at furrowing in flooded rice paddy field that many people have an interest in as direct sowing method most recently. As hardening period was increased, the percentage of seedling stand and seed floating at flooding were increased slightly, while buried depth of stem at maximum tillering stage and cone penetration depth were decreased, respectively. Therefore, optimum degree of soil hardening was about 3 days after draining, at this time, cone penetration degree was about 6~7cm. According to furrow depth was more and more deep, buried depth of stem was increased gradually, but percentage of seedling stand was decreased considerbly. Also, root distribution ratio on surpace horizon and lodging degree were increased gradually according to furrow depth become more and more shallow. As flooding time after sowing was late, percentage of seedling stand and panicle number per $m^2$ were decreased slightly. These results apparently indicated that sowing after 3 days hardening when cone penetration degree was 6~7cm, furrow depth 3~4cm degree and flooding time just after sowing the best method to good establish of seedling stand.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.720-728
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• 2009

This thesis is results of numerical analyses about test results of discharge capacity apparatus using penetration method. Applicability of numerical approach with FEM technique, using Cam-clay model, was confirmed by analyzing the results of standard consolidation test before analyzing test results of discharge capacity apparatus using penetration method. Thus, input parameters for the model was convinced to be appropriate. For numerical analyses about test results of discharge capacity apparatus using penetration method, identical initial and loading conditions during tests were applied to simulate test results correctly. Effects of ground disturbance resulted from installment of vertical drains on the behaviors of consolidation were also simulated. Applicability of numerical approach was investigated by comparing test results with numerical ones. As results of them, both of consolidation settlement were found to be in good agreements so that its applicability was confirmed. As results of numerical estimation, degree of consolidation with the condition of considering smear zone was found to be delayed, compared with results without smear zone. On the other hands, parametric numerical analyses of changing parameters related to smear zone such as permeability and size of smear zone and permeability of vertical drain were also carried out.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.1
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• pp.61-68
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• 2008

It is essential to analyze and classify the physical characteristics of weathered granite for engineering purposes. This paper is to suggest a physical method to determine the degree of weathering of weathered soils. A new classification method for determining the degree of weathering is suggested, based upon the results from laboratory tests including fall cone test. According to the proposed physical method using fall cone apparatus, the measured values of the samples from the same area show distinctive difference of weathering. The water content tends to increase with increasing the degree of weathering at the same penetration in fall cone test. And relationship between CWI and water content are expressed one equation in Hwaseong area and Ilsan area.

• Journal of the Korean Wood Science and Technology
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• v.46 no.3
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• pp.253-259
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• 2018

To determine the depth of preservative penetration in ACQ treated wood, the degree of penetration of Cu was measured. In this study, we developed a DDAC coloring method to investigate the penetration depth of DDAC, which is one of the active ingredient of ACQ, into wood. The following conclusions were obtained. The DDAC component reacts with a 2', 7'-dichlorofluorescein indicator and results in a deep orange color. This orange coloring reaction appears not only in DDAC solutions but also in ACQ treated wood tissues in which DDAC is present. It is possible to visually verify that DDAC has better wood penetration than Cu in the spruce, which is an refractory wood species, by the DDAC coloring method developed this study. In addition to the results, it is necessary to investigate the difference in penetration of Cu and DDAC for other wood species with poor preservative penetration.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.15-22
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• 2010

Chloride-induced corrosion of steel bars in concrete exposed to marine environments has become one of the major causes of deterioration in many important facilities made of reinforced concrete. A study on chloride penetration in concrete has developed through long period exposure test along seawater, assesment of chloride ion diffusion by electrochemical techniques and so on. However, reasonable and exclusive chloride penetration model considering concrete material properties with mixture, degree of hydration, binding capacity has not been established. Therefore, in this paper, chloride penetration analysis of non-steady state is accomplished with material properties of concrete. Comparing with the results of analysis and chloride ponding test, we could accept the effect of binding capacity on chloride penetration in concrete and these results could be applied to a service life prediction of R.C. structures submerged in seawater. Therefore, there are 20~40% differences of service life to SHRP prediction.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1434-1439
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• 2004

CFRP composite materials have wide application in structure materials of airplane, ships, and aero space vehicles because of their high strength and stiffness. This paper is to study the effects of curvature and orientation angle on the penetration characteristics of CFRP laminate shell. They are staked with 8 Ply specimens [0$_2$/90$_2$]$_{s}$, [0/90$_2$/0]$_{s}$ and the stacked of outer plates degree with 12 Ply specimens [0$_3$/90$_3$]$_{s}$, [0$_2$/90$_2$/0]$_{s}$ and [90$_3$/0$_3$], [90$_2$/0$_2$/90]S. They are manufactured to varied curvature radius (R=100,150,200mm and $\infty$). They are cured by heating to the appropriate harding temperature(13$0^{\circ}C$) by mean of a heater at the vaccum bag of the autoclave. Test specimens were prepared with dimensions 100mm$\times$140mm. When the specimen is subjected to transverse impact by a steel ball, the velocity of the steel ball was measured both before and after impact by determining the time for it to pass two ballistic-screen sensor located a known distance apart. In general, kinetic energy after impact-kinetic energy before impact rised in all specimens. This study observed a fracture mode inside the specimen after a penetration test using a digital camera and it examined a fracture mode and a penetration mode to stack of outer orientation angle and curvature.rvature.

• Proceedings of the KSR Conference
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• 2001.05a
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• pp.451-458
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• 2001

The purpose of this study was to evaluate shear parameters on cutting slope of weathered granite soils by using small dynamic cone penetration test on the very moment of its cutting. The results were : On the relations among N$\_$c/, Li, and CEC, the condition of Li＞6%, CEC＞14(meq/100g) corresponds to that of N$\_$c/ values of 2∼30, and 3＜CEC＜14(meq/100g) to N$\_$c/=30∼50. Comparing the smallest penetration depth from two small dynamic cone penetration tests done at 5m below from the top of the slope on April 15th, October 31t. there was a l0cm difference. So we could find out the degree of weathering on the slope. And dividing the difference by 190 days (the whole testing time), we could know it's being weathered 0.052mm each day. The more N. value increases, the more shear parameters(internal friction angle ; $\phi$, cohesion : c) increase at a standard pressure($\sigma$＞32㎪). So the condition of N$\_$c/=2∼50 corresponds to that of $\phi$=27∼50, c=12∼49㎪. From the above testing results, the N$\_$c/ values more correspond to $\phi$ values than c values. In conclusion, this study suggests that on small dynamic cone penetration test a penetration boundary line of 5 centimeters is decided at around Li=4%, CEC=3(meq/100g) which is classified as a strong weathering soil. It also shows that as Li increases CEC increases as well, while N$\_$c/ decreases.