• Journal of the Korean Applied Science and Technology
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• v.32 no.2
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• pp.339-347
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• 2015

This study is to evaluate moisturizing effect and durability of UV A/B blocking activity with multiple (W/O/W) emulsion system. Most of the sun protective products come to be hot issue having both high SPF and long-lasting activity as using special products when is going out, mountain climbing and sports. Also, many consumers prefer the products which have the excellent waterproofing activity of sun care cosmetics as well as the non-sticky feeling that carried out the study of the sensorial science and texture preference. Therefore, development of the specific formulation using this multiple (W/O/W) emulsion technology, it has O/W type hydro skin feel having soft and moist texture when it is treated on the skin. Finally, this formulation is instantly changed to W/O type feel after adsorbed into the skin. The purpose of this study is to get high SPF lasting effect having high water resistance tactivity with high functional multiple (W/O/W) emulsion cream. We used major ingredients, UV-B absorbers were selected with ethylhexyl methoxycinnamate, isoamyl-p-methoxycinnamate, ethylhexylsalicylate, and octocrylene, UV-A absorbers were selected with butylmethoxydibenzoylmethane, bis-ethylhexyloxyphenol methoxy phenyltriazine. SPF effect of O/W type cream was 34.1. SPF effect of W/O/W type cream was 40.6 (increased about 19%). Water resistance effect after 4 hours, SPF effect of O/W type cream was 3.6 (quickly drop down). SPF effect of W/O/W type cream having 81.0 % waterproofing effect was 32.7 (decreased about SPF 7.9). Moisturizing effect of O/W cream at first was superior comparing multiple emulsion. But after 3 hours quickly was drop-down. Moisturizing effect of multiple emulsion was high comparing O/W type and other sun block creams after 4 hours was constantly maintaining water-content.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.619-630
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• 2022

The concrete mix design and compressive strength evaluation are used as basic data for the durability of sustainable structures. However, the recent diversification of mixing factors has created difficulties in calculating the correct mixing factor or setting the reference value concrete mixing design. The purpose of this study is to design a predictive model of bidirectional analysis that calculates the mixing elements of ternary concrete using deep learning, one of the artificial intelligence techniques. For the DNN-based predictive model for calculating the concrete mixing factor, performance evaluation and comparison were performed using a total of 8 models with the number of layers and the number of hidden neurons as variables. The combination calculation result was output. As a result of the model's performance evaluation, an average error rate of about 1.423% for the concrete compressive strength factor was achieved. and an average MAPE error of 8.22% for the prediction of the ternary concrete mixing factor was satisfied. Through comparing the performance evaluation for each structure of the DNN model, the DNN5L-2048 model showed the highest performance for all compounding factors. Using the learned DNN model, the prediction of the ternary concrete formulation table with the required compressive strength of 30 and 50 MPa was carried out. The verification process through the expansion of the data set for learning and a comparison between the actual concrete mix table and the DNN model output concrete mix table is necessary.

• Journal of the Korean Geosynthetics Society
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• v.22 no.4
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• pp.17-26
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• 2023

To consider the risk of damage and fracture of P.C strands, the existing post-maintenance system alone has the limitations, hence it is necessary to quantitatively evaluate and predict the deterioration, durability and safety of facilities and establish a reasonable maintenance system considering the asset value of facilities. Therefore, it is worth considering a preventive maintenance plan that allows proactive measures to be taken before a major defect occurs in the temporary anchor. This study devised a preventive over tension method, reviewed its effectiveness through design and field tests, by calculating the resistance factors by performing a reliability-based optimization design. At this time, the over tension anchor method was evaluated using the ratio of the residual tension force after the fracture of P.C strands to the effective tension force before the fracture of P.C strand, followed by the resistance factor calculated by the optimal solution for each random variables using Excel solver and applying it to the limit state equations. As a result of the study, if the over tension ratio is 125% to 130%, the remaining strands showed a high resistance effect even after the fracture of P.C strand. As a result of the optimization design, it was found that it is appropriate to apply the load factor (γ) of 1.25, and the resistance factors of Φ₁, Φ₂, Φ₃ as 0.7, 0.5, 0.6.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.4960-4968
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• 2015

In this study to improve the chloride durability of the shotcrete structure depending on types and contents of mineral admixture chloride resistance was evaluated by NT BUILD 492 of european test standards. It was also evaluated with the mechanical properties such as static strength and chloride penetration resistance. For shotcrete mixed crushed stone aggregate of the maximum size 10mm of coarse aggregates was produced. Based on 28days compression strength the variable mixed with 15% silica fume showed the highest strength in 67.55MPa. As the content of fly ash and blast furnace slag increased, the strength lowered. In the chloride penetration resistance test, OPC showed "high grade" and In the case of admixture, the penetration resistance tended to increase in all variables except the fly ash. In order to evaluate the service life, the accelerated chloride penetration test was conducted by the standards of KCL, ACI, FIB. Test results were obtained with the lowest spreading factor in a variable mixed with silica fume of 15%. At the KCI standards, It was found to have a service life of about 65 years and at the FIB standards, It was found to have a service life of 131 years. Among standards, the service life of KCI standard in all of the variables was evaluated as the lowest.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.3
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• pp.41-47
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• 2009

Post-tensioned concrete pavement(PTCP) was developed to built long-span concrete pavement(120 m span) and to maintain long-term service life(over 40 years) of concrete pavement. In the present study, research for high-durable concrete was conducted to utilize the advantage of PTCP construction method efficiently. First of all, 20% of fly ash(by binder weight) was replaced to control alkali silica reaction. Second, silica fume was applied to improve the water-permeability and early-age strength. Results of tests for mechanical properties, water-permeability resistance, and surface-scaling resistance of ternary blended cement concrete showed that the early-age strength was improved significantly with addition of silica fume. The water-permeability resistance was improved from "Low" to "Very Low"(ASTM C 1202). However, surface-scaling resistance was decreased with an increase of silica fume, therefore, content of silica fume should be kept in less than 5%(by binder weight) to assure field application considering durability. The results of air-void analysis showed that durability factors were improved since spacing factors were estimated as 250$\pm$15 micron in adjusted mixtures.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.424-429
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• 2018

In this study, an expansion joint that is susceptible to waterhammer was tested for its vibration durability. The operation data for the hydraulic actuator was the expansion length of the expansion joint when the waterhammer occurred. In the case of the vibration durability test, the internal temperature status of the expansion joint was assumed to be a stress factor and a lifespan prediction model was assumed to follow the Arrhenius model. A test was carried out by increasing the internal temperature status at $30^{\circ}C$, $50^{\circ}C$, and $65^{\circ}C$. By a linear transformation of the lifespan data for each temperature, a constant value and activation energy coefficient was induced for the Arrhenius equation and verified by comparing the value of a lifetime prediction model with the experimental value at $85^{\circ}C$. The failure modes of the ongoing or finished test were leakage, bellows separation, and internal deformation. In the future, a composite lifespan prediction model, including two more stress factors, will be developed.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.3
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• pp.475-484
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• 2000

The purpose of this study was to develop model for estimating biodegrability of organic sludge (sewage and papermill) in various environmental conditions. to assume degradable degree with operating time of SRB reactor. and evaluate duratior of organic sludge as carbon source. Average TCOD was 28.7~63.2mg/L in effluent. organic sludge did not much supply carbon source for experimental period. But in point of durability. it seemed that organic sludge was efficient because it was not consumed by degradation of much organic matter within short period. With increasing $SO_4{^{2-}}$ reduction rate. Pb and Fe was removed 77~82% and 33~59%. respectively. Because Al was precipitated as a hydroxide. its removal rate wa,. about $54{\pm}2%$ in R-l~R-3 maintaining low pH but about 78% in R-4 maintaining high pH. Because Mn was large in solubility. it showed to be much lower than other heavy metals. Considering supportable capacity or durability of orgainc matter for initial SRB mixing ratio of sewage/papermill 0.5 was regarded as appropriate substituting material and at this time. it estimated that carbon source continued about 3.08 year but safety factor must apply to be thought over. because various factors had an effect on degradation of organic sludge.

• The Korean Journal of Elementary Counseling
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• v.9 no.1
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• pp.95-110
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• 2010

The purpose of this research is to investigate how the Peer-Praise Activity program influence the Elementary School Students' Peer-Relationship and Class Cohesiveness. 2 Classes from the 5th grade of J elementary school in Seoul were selected as experimental group and control group. After the Peer-Praise Activity program was applied to experimental group, a post-test was given to verify the effects of the program. After one month, follow up-test was conducted to check the effect of durability on program. The program was applied to experimental group to check the inadequency and problem. Contrastively, control group had no application of the program. The results of this study are as follows : Compared to control group, experimental group that participated in the Peer-Praise Activity program showed significant improvement(p<.05) in Peer-Relationship and Class Cohesiveness. To supplement the results of quantitative analysis, opinion documents and qualitative analysis were executed. It shows that children had help of having confident school life by improving friendship and having a sense of unity and community spirit. In follow up-test result, it is known that the effect of Peer-Praise Activity Program is continued in Peer-Relationship and Class Cohesiveness and its all sub-factors except Communal life with friends which is one of the sub-factor in Peer-Relationship. The results above prove that Peer-Praise Activity Program has a positive effect on the Peer-Relationship and Class Cohesiveness for elementary school students. But it is needed to study long-term conducted program to improve durability effect. And curriculums and subjects which is able to connected with program should be studied continually.

• Journal of the Korean Electrochemical Society
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• v.12 no.2
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• pp.181-188
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• 2009

Pt catalyst was adsorbed on Carbon nanofiber (CNF) by modified polyol method after acid treatment of the carbon support with $HNO_3$ and $H_{2}SO_{4}$. As the time for acid treatment increases, more oxygen functional groups on carbon surface were produced which improve the loading amount and dispersion of Pt catalyst on carbon supports. In order to inspect the effect of CNF acid treatment time on electrochemical corrosion, constant potential of 1.4 V was applied to a single cell for 30 min and the amount of $CO_2$ emitted was monitored with on-line mass spectrometry. According to the results of our experiment, more $CO_2$ was produced with Pt/ oxidized-CNF catalyst in compared to that with unoxidized-CNF. Increasing acid treatment time also induces the more $CO_2$ emission. Besides, performance degradation after corrosion test expanded with severer carbon corrosion. From the observed results, it can be concluded that the acid treatment of CNF is beneficial to catalyst loading, but it also is a significant factor declining the fuel cell durability by accelerating electrochemical oxidation of carbon support.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.51-60
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• 2011

In this study, structural safety capacity analysis of the overpass railway bridge between Konkuk Univ. and Guui station railroad has been performed. The overpass is expected to have suffered durability reduction by deterioration. The weight reduction of the overpass has been implemented to prevent further durability reduction and to improve performance capacity. To reduce the weight, 3 procedures of replacing concrete soundproofing wall to light-weight soundproofing wall, replacing gravel ballast to concrete ballast, and reducing the weight of trough have been performed. The analysis of static/dynamic behaviors and improved capacity of the light-weighted overpass bridge has been performed. The structural safety verification of the improved structure has been implemented by using rating factors of load carrying capacity of PSC I girder. The results have shown that the deflection has been reduced by 2.6mm and tensile strength has been improved by 1.07MPa, which indicate that the structural capacity has effectively been improved. Also, the natural frequency has improved by approximately 30% where vibration reduction and dynamic behavior improvement have been achieved. Moreover, in the rating factor evaluation based on analysis and test results, an improvement from 1.82 to 1.93 has been observed. Therefore, weight reduction method for the overpass is effective considering overall results.