• Journal of Periodontal and Implant Science
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• v.43 no.3
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• pp.130-135
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• 2013

Purpose: The purpose of this study was to evaluate the tensile strength of surgical synthetic absorbable sutures over a period of 14 days under simulated oral conditions. Methods: Three suture materials (polyglycolic acid [PGA], polyglactin [PG] 910, and poly (glycolide-co-${\epsilon}$-caprolactone) [PGC]) were used in 4-0 and 5-0 gauges. 210 suture samples (35 of each material and gauge) were used. All of the samples were tested preimmersion and 1 hour and 1, 3, 7, 10, and 14 days postimmersion. The tensile strength of each suture material and gauge was assessed. The point of breakage and the resorption pattern of the sutures were also assessed. Results: During the first 24 hours of immersion, all 4-0 and 5-0 samples of PGA, PG 910, and PGC maintained their initial tensile strength. At baseline (preimmersion), there was a statistically significant (P<0.001) difference in the tensile strengths between the 4-0 and 5-0 gauge of PGA, PG 910, and PGC. PGA 4-0 showed the highest tensile strength until day 10. At 7 days, all the 4-0 sutures of the three materials had maintained their tensile strength with PGA 4-0 having significantly greater (P=0.003) tensile strength compared to PG. Conclusions: 4-0 sutures are stronger and have greater tensile strength than 5-0 sutures. The PGA 4-0 suture showed the highest tensile strength at the end of day 10.

• Corrosion Science and Technology
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• v.2 no.4
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• pp.202-206
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• 2003

Fusion Bonded Epoxy(FBE) systems have been widely used to protect pipelines for over 30 years. Numerous attempts have so far been made to improve the properties of FBE coatings such as chemical resistance, adhesion, water resistance, cathodic disbondment resistance, impact resistance, and flexibility to protect pipelines at a wet and a high temperature condition. But these attempts have not been successful in reducing some weakness, for instance, in pipeline operating at high temperature due to poor hot water resistance and cathodic protection. The purpose here is to build a basis for getting better corrosion resistance of FBE systems. Cresol-novolac epoxy coating systems were studied compared to bisphenol A type epoxy systems. After the immersion of the film in water at a high temperature for a long period, good adhesion to metal substrate and excellent cathodic disbond resistance were observed in the cresol-novolac epoxy resin systems. It is well known that the adhesion of organic coatings to metal substrate might be decreased due to the disruption of a chemical bond across the film and metal interface induced by water molecules. A high crosslinking density might decrease water permeability and improve cathodic disbonding protection in the coatings. Other factors are studied to understand anti-corrosion mechanism of Cresol-novolac epoxy coatings. In addition, the water absorption rate and the effect of cure temperature on the adhesion and cathodic disbonding resistance ofthe films were studied in different epoxy coatings and the effect of substrate was evaluated. The results of field application are proved that the Cresol-novolac epoxy coating system developed recently is one of the most suitable coatings for protection of pipelines.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.5
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• pp.1-7
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• 2008

A study of new materials that are light-weight, high in strength has become vital to the machinery of auto industries. But then, there are a lot of problems with developing such materials that require expensive tools, and a great deal of time and effort. Therefore, the improvement of fatigue strength and fatigue life are mainly focused on by adopting residual stress. And Influence of corrosive condition for corrosion fatigue crack was investigated, after immersing in 3.5%NaCl, $10%HNO_3$+3.5%HF, $6%FeCl_3$. The immersion period was performed for 365days. The compressive residual stress was imposed on the surface according to each shot velocity based on shot peening, which is the method of improving fatigue life and strength. Fatigue life shows more improvement in the shot peened material than in the un peened material in corrosion conditions. The threshold stress intensity factor range was decreased in corrosion environments over ambient. Compressive residual stress of surface on the Shot-peen processed operate resistance force of fatigue crack propagation. The fatigue crack growth rate of the Shot-peened material was lower than that of the un peened material. Also m, fatigue crack growth exponent and number of cycle of the shot peened material was higher than that of the un peened material. That is concluded from effect of da/dN.

• Journal of the Korean Society of Food Science and Nutrition
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• v.8 no.1
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• pp.43-50
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• 1979

This experiment was designed to investigate the changes of cadmium content of different foods during cooking. 1. By addition of standard cadmium to different foods, recovery percentage was 98.3% by Dithizone Method and 97.9% by APDC. 2. At various pH levels the highest cadmium was extracted at pH 1.0. 3. Cadmium was contaminated at first to six hours of immersion and did not increased after this period. 4. About 2/3 of added cadmium was extracted by different concentrations of acetic acid.

• Smart Media Journal
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• v.11 no.7
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• pp.52-60
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• 2022

Due to global warming and changes in the natural environment, flood damage to agricultural land due to wind and flood damage continues. Although disaster prevention projects have been continuously carried out since the founding of the country, progress has been insufficient compared to the sustained period, and huge costs are still being consumed. Therefore, it is necessary to use predictive simulation for pre-emptive response to inundation of farmland. In this paper, a case of immersion analysis simulation using a GIS(Geospatial Information System) based SWMM model was introduced, and the validity was confirmed through the error rate between our simulation result and the results of other models in the US and Korea. In addition, in the direction of using the simulation for agricultural land inundation, we presented various utilization methods to supplement the current agricultural land inundation-based information policy, such as the creation of flood traces. If simulation results from more regions are accumulated in the form of the flood analysis maps in the future, it is expected that they will be able to be utilized in various applications for preemptive response to and prevention of water disasters at the national level.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.157-162
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• 2024

This study was conducted to implement Joseon Dynasty conversational style using the ChatGPT API to enhance the immersion of games set in the Joseon era. The research focuses on interactions between middle-class players and other classes. Two methods were employed: learning the dialogues from historical dramas set in the Joseon Dynasty and learning the sentence endings typical of the period. The method of learning sentence endings was rated higher based on self-evaluation criteria. Reflecting this, prompts were constructed to represent NPC dialogues in the game settings of the Joseon era. Additionally, a method was proposed for creating various NPC prompts using prompt combination techniques. This study can serve as a reference for NPC dialogue creation in games set in the Joseon Dynasty.

• Journal of the Korea Concrete Institute
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• v.21 no.3
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• pp.377-386
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• 2009

A reference diffusion coefficient model from ACI life-365 is drawn from test results by NT build 443. This test method gives a time-averaged diffusion coefficient during immersion period, thus the ACI model uses the time-averaged diffusion coefficient as a reference value. ACI model needs to be revised, considering the difference between the time-average value and reference value at specified time. In this study, firstly the analytic solutions of diffusion equation are derived considering the initiation time and period of exposure to chloride, and secondly the time-averaged diffusion coefficient from NT build 443 is converted into the diffusion coefficient at reference time. From this study, the reference diffusion coefficient of ACI model should be modified to be about 10% larger values than those of present ACI model. For convenient design of service life, previous relationship between the chloride diffusion coefficient from NT build 443 and that from NT build 492 is also modified. To compare the chloride diffusion coefficients of ACI and JCI models, the reference chloride diffusion coefficient with respect to the JCI model is drawn in the similar form of ACI model's, and service life prediction by ACI life-365 method is confirmed to give a conservative result.

• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.6-15
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• 1991

The purpose of this study was to observe in vitro chloride corrosion behavior from 5 kinds of amalgam (Caulk spheracal, Amalcap, Dispersalloy, Tytin, Sybralloy) as a function of time after tritruration by using potentiostat. After each amalgam alloy and Hg was triturated as the direction of the manufacturer by the mechanical amalgamator, the triturated mass was inserted the cyrindrical matal mold ($12{\times}10mm$) and was condensed by using routine manner. The specimen was removed from the mold and was stored at room temperature for 1 week, 1 month and 3 months, and standard surface preparation was routine carried out. The 0.9% saline solution was used as electrolyte in pH 6.8~7.0 at $30{\pm}0.5.^{\circ}C$. The open circuit potential was determined after 30 minutes' immersion of 1 week, 1 month and 3 month old specimens. The scan rate was 1 mV/sec and the surface area of amalgam exposed to the solution was $0.65\;Cm^2$ for each specimen. All potentials reported are with respect to a silver / silver chloride electrode (SSE). The following result was obtained. 1. All amalgam specimens became more noble corrosion potentials which represent the improved corrosion resistance as the time elapsed. 2. Three kinds of high copper amalgam always exhibited more noble potential than low copper amalgam at 1 week, 1 month and 3 months. 3. Two kinds of low copper amalgam had the similar polarization curve pattern with 3 current peaks at each time period and current densities associated with these peaks were decreased as aging especially in caulk spherical amalgam. 4. All kinds of high copper amalgam had the similar polarization curve pattern with absence of prominent current peak at each time period, but the polarization curve of D amalgam had one apparent current peak at 1 week.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.11-21
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• 2019

It has been about 20 years since the English subject was formally taught in public elementary schools in Korea. The present research aims to analyze the studies regarding 'primary English' implemented in Korea during the time period. I have investigated 6,467 theses or research papers in total that were published in Korea with the help of the corpus programs Utagger and WordSmith Tools. The results show that for the last 20 years the number of overall studies appears to have increased since the year 1997, although the recent trend seems to be in recession. The research scope ranges from 'teaching-learning interaction' to 'curriculum' and 'assessment', which have been steadily investigated for 20 years. Furthermore, researchers sometimes appear to have followed the English education policy by conducting particular investigations like 'immersion program' or 'native English speaking teachers' in a certain time period. Recently, researchers started to have interest in the cutting-edge ICT. In conclusion, the academic field of 'primary English' in Korea has grown in quantity, and the spectrum of research areas has been expanded for the past 20 years. It is hoped that the results of this research will help set a new direction for future research.

• Journal of fish pathology
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• v.26 no.2
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• pp.117-121
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• 2013

Three commercial exfoliating reagents, product A (main components: citric acid and vitamin C), B (herb) and C (nicotinamide), were used to study their exfoliation effect on abalone, Haliotis discus hannai from the substrate. The exfoliating reagents A, B, C and oxytetracycline (OTC, control) of 6-31.25 g/L and 12-37.5 g/L exfoliated 81.2-84.8% and 90.3-95% of abalone, respectively. Post-treatment recovery time for the abalone was similar for all the reagents except product C. Recovery period for the abalone immersed in OTC for 5-20 second was slightly shorter than the reagents A, B and C; however, no mortality was observed in any group except with the reagents B (concentration: 20 g/L, immersion time: 5 sec) and C (12 g/L, 10 and 20 sec) that showed negligible mortality of 3.3%. Higher concentration and longer treatment with the reagents resulted in longer recovery time of the detached abalone. Although abalone exposed to the reagents needs slightly longer time to recover than that to OTC, the exfoliation effect is much similar. These results indicate that the commercial exfoliating reagents can replace OTC to detach abalone, though they need to be cautiously handled.