• Journal of the Korean Ceramic Society
• /
• v.17 no.4
• /
• pp.188-196
• /
• 1980

To investigate the corrosion behavior of the clay-bonded kaolin chamotte by molten aluminum, the mixture of 20 wt% fire clay and 80 wt% kaolin chamotte was prepared and fired in the temperature range 900~120$0^{\circ}C$. The specimens fired at each temperature were reacted with molten aluminum at 90$0^{\circ}C$. The results obtained in this experiment are as followed. 1) It was confirmed through X-ray diffraction analysis that the clay-bonded kaolin chamotte exposed to molten aluminum suffered penetration by the reaction of aluminum with silica forming alumina and metallic silicon. 2) Penetration was independent whether the silica existed as free or one component of mullite. 3) Penetration of the specimen fired at 90$0^{\circ}C$ was negligible while the others fired above 100$0^{\circ}C$ showed remarkable penetration. 4) Penetration rate at 90$0^{\circ}C$ was parabolically increased with the holding time as in the case of metal oxidation.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.4 no.2
• /
• pp.189-201
• /
• 2001

For a design of multi-layer armor, the extensive full scale or sub-scale penetration test data are required. In generally, the collection of penetration data is in need of time-consuming and expensive processes. However, the application of numerical or analytical method is very limited due to poor understanding about penetration mechanics. In this paper, we have developed a neural network analyzer which can be used as a design tool for a new armor. Calculation results show that the developed neural network analyzer can predict relatively exact penetration depth of a new armor through the effective analysis of the pre-existing penetration database.

• Journal of the Korean GEO-environmental Society
• /
• v.2 no.3
• /
• pp.89-99
• /
• 2001

In this study, the numerical analysis of piezocone penetration and dissipation tests has been conducted using the Modified Cam-Clay model, which is generally used in soil mechanics. The Modified Cam-Clay model and related mathematical equations in finite element derivation have been formulated in the Updated Lagrangian reference frame to take the large displacement and finite strain nature of piezocone penetration into consideration. The cone tip resistance, the pore water pressure, and the dissipation curve obtained from the finite element analysis have been compared and investigated with the experimental results from piezocone penetration test performed in Yangsan site. The numerical results showed good agreement with the experimental results; however, the better numerical simulation of the continuous and deep penetration needs further research.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.4
• /
• pp.671-678
• /
• 2006

Vibratory pile driving has an advantage of reduced noise pollutions compared to impact pile driving and it has been very widely used in the installation of sheet piles. However, very little has been known about the driveability characteristics of sheet pile under vibratory driving. So, the proper sheet piles and vibratory hammer for an given soil profile and depth are determined on a empirical basis. In this study. the driveability of U-type sheet piles are analytically estimated using the commercial WEAP(Wave Equation Analysis of Piles) program. The WEAP analysis shows that penetration rate of sheet pile decreases as N value increases. And if penetration length is not over 20 meters, the rate of penetration decreases as the sectional area of sheet pile increases.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.13 no.1
• /
• pp.23-29
• /
• 2014

The purpose of this paper is to assess the structural integrity of piping penetrations for nuclear power plants. A piping qualification analysis describes loads due to deadweight, pressure difference acts normal to the plate, thermal transients, and earthquakes, among other events, on piping penetrations that have been modeled as an anchor. Amodel was analyzed using a commercial finite element program. Apiping penetration analysis model was constructed with an assembly of pipe, head fittings and sleeves. Normally, the design load, thus obtained, will consist of three moments and three forces, referred to a Cartesian coordinate system. When comparing the stress analysis results from each required cutting position, the general membrane stress intensities and local membrane plus bending stress intensities during a structural evaluation cannot exceed the allowable amount of stress for the design loads. Therefore, the piping penetration design satisfies the code requirements.

• Journal of Electrical Engineering and Technology
• /
• v.10 no.3
• /
• pp.859-864
• /
• 2015

This paper analyzes the impact of Plug-in Electric vehicles(PEVs) on power demand and voltage change when PEVs are connected to the domestic distribution system. Specifically, it assesses PEVs charging load by charging method in accordance with PEVs penetration scenarios, its percentage of total load, and voltage range under load conditions. Concretely, we develop EMTDC modelling to perform a voltage distribution analysis when the PEVs charging system by their charging scenario was connected to the distribution system under the load condition. Furthermore we present evaluation algorithm to determine whether it is possible to adjust it such that it is in the allowed range by applying ULTC when the voltage change rate by PEVs charging scenario exceed its allowed range. Also, detailed analysis of the impact of PEVs on power distribution system was carried out by calculating existing electric power load and additional PEVs charge load by each scenario on new-town in Korea to estimate total load increases, and also by interpreting the subsequent voltage range for system circuits and demonstrating conditions for countermeasures. It was concluded that total loads including PEVs charging load on new-town distribution system in Korea by PEVs penetration scenario increase significantly, and the voltage range when considering ULTC, is allowable in terms of voltage tolerance range up to a PEVs penetration of 20% by scenario. Finally, we propose the charging capacity of PEVs that can delay the reinforcement of power distribution system while satisfying the permitted voltage change rate conditions when PEVs charging load is connected to the power distribution system by their charging penetration scenario.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.23 no.2
• /
• pp.401-414
• /
• 1996

The purpose of this study was to compare the marginal leakage of resin liner which was used as a liner to amalgam restoration. Control group composed of no liner group, copalite group and experimental group composed of All-bond 2, Vitrebond, Superbond D-liner applied groups were evaluated. Cl.V preparation with a size of $3{\times}2{\times}1.5mm$ on 70 extracted primary molars were made and applied appropriate liners for each groups. After amalgam filling and polishing, polished specimens underwent temperature changed from $5^{\circ}C\;to\;55^{\circ}C$ a thousand times. After thermocycling, specimens were placed in 2% methylene blue dye solution for 72 hours in an incubator set at $37^{\circ}C$. The teeth were sectioned buccolingually and the degree of dye penetration was observed with a spectroscopy. (${\times}30$) The following results were obtained. 1. Vitrebond, All-bond 2, Superbond D-liner group exhibited a statistically significant lower degree of dye penetration than no liner and copalite group. (Kruskal-Wallis analysis, P<0.05) 2. No liner group and copalite group exhibited a similar degree of dye penetration. (Mann-Whitney analysis, P>0.05) 3. All-bond 2 group exhibited a statistically significant lower degree of dye penetration than Vitrebond group, (Mann-Whitney analysis, P<0.05) Superbond D-liner group also exhibited a lower degree of dye penetration than Vitrebond group but was statistically insignificant. (Mann-Whitney analysis, P>0.05)

• Korean Journal of Otorhinolaryngology-Head and Neck Surgery
• /
• v.60 no.9
• /
• pp.454-462
• /
• 2017

Background and Objectives The present study aimed to investigate the effects of penetration/aspiration (P/A) on voice acoustic parameters. Subjects and Method Twenty-seven patients were analyzed with the videofluoroscopic swallowing study (VFSS) and then divided into two groups based on the modified Penetration and Aspiration Scale results. Ten patients (5 males and 5 females) were included in the Non-P/A group, and 17 patients (12 males and 5 females) in the P/A group. Stroke was the major cause of swallowing disorders. Three sustained /a/ vowels recorded in pre- and post-VFSS were analyzed. Mann-Whitney U-test was used to compare acoustic values before and after VFSS, and the receiver operating characteristics (ROC) curve with combination of significant parameters was also conducted. Results Among acoustic parameters, the length of analyzed sample (p=0.010), number of segments computed (p=0.018), total number detected pitch periods (p=0.017), and second formant (p=0.013) in pre- and post-VFSS were significantly different between Non-P/A and P/A groups. In the P/A group after VFSS, the means of these significant parameters decreased. According to ROC combined with four significant parameters, the probability of predicting P/A condition was 84% (p=0.005), the sensitivity was 80%, and the specificity was 80%. Conclusion Voice acoustic analysis can reflect voice changes by penetration/aspiration and the combination of significant parameters can also detect swallowing disorders. Therefore, voice analysis can be a reliable screening tool for patients with swallowing disorders.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.45 no.3
• /
• pp.73-83
• /
• 2003

Methods of fuzzy C-means have been used to characterize geotechnical information from static cone penetration data. As contrary with traditional classification methods such as Robertson classification chart, the FCM expresses classes not conclusiveness but fuzzy. The results show that the FCM is useful to characterize ground information that can not be easily found by using normal classification chart. But optimal number of classes may not be easily defined. So, the optimal number of classes should be determined considering not only technical measures but engineering aspects.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.11 no.6
• /
• pp.164-171
• /
• 2008

A modified generalized particle algorithm, MGPA, was suggested to improve the computational efficiency of standard SPH method in numerical analysis of high speed impact behavior. This method uses a numerical failure mechanism than material failure models to describe the target penetration. MGPA algorithm was more effective to describe the impact phenomena and new boundaries produced during the calculation process were well recognized and treated in the target penetration problem of a bullet. When bullet perforation problems were analyzed by this method, MGPA algorithm calculation gives the stable numerical solution and stress oscillation or particle penetration phenomena were not shown. The error range in ballistic velocity limit is less than $2{\sim}13%$ for various target thickness.