• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.1
• /
• pp.123-130
• /
• 2006

The duties of the restorative materials are to bear up against stress and to protect reinforcement corrosion. So the restorative materials are estimated by various kinds of strength, permeability and etc, But, in case of existing performance evaluation of restorative materials, because various deterioration factors are separately acted, the system of performance evaluation is different from that of combined deterioration of real structure and it is difficult to evaluate the exact performance of restorative materials. In this study, to evaluate Performance of restorative materials, we compare their korea standard properties in terms of compressive and bending strength and permeability of water and air with real durability for carbonation, salt damage and actual reinforcement corrosion like ratio of corrosion area. weight reduction and corrosion velocity of steel bar under environment of combined deterioration. The results showed that strength and permeability of restorative materials are similar but their resistance to carbonation, salt damage and actual reinforcement corrosion are very different.

• Journal of People, Plants, and Environment
• /
• v.22 no.6
• /
• pp.691-698
• /
• 2019

This study is to examine the effect of improving the forest therapy program for adolescents using forest healing resources (focused on improving index of greenness for adolescents). The participants were 30 students from in the control group that participated in the 2018 program, and 51 students in experimental group that participated in the improved program in 2019. The questionnaire, developed by Korea Forest Welfare Institute, was comprised of items on general matters, index of greenness, restorative environment, positive emotion, negative emotion, facial expression and psychological assessment. The control group had 30 and the experimental group had 49 valid copies of the questionnaires. As a result of the paired sample t-test for each group, the control group showed a significant increase in all categories except restorative environment. In the experimental group, all categories significantly improved to a higher level (p <.01). An independent sample t-test (one-tailed test) was performed to test the effect of the forest therapy program with improved index of greenness. As a result, the index of greenness increased by 0.73 points(t=2.555, p <.01) and restorative environment by 1.01 points (t=2.567, p <.01), showing statistical significance. Negative emotion increased by 0.04 points (t=0.183, p >.05), which was not significant. On the other hand, positive emotion decreased by 0.42 points (t=-1.918, p <.05), facial expression by 0.57 points (t=-1.775, p <.05), and psychological assessment by 0.29 points (t=-0.981, p >.05), showing significance in positive emotion and facial expression. However, all the decreased items showed significant improvements between the pretest and posttest scores of the experimental group.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.41 no.4
• /
• pp.68-76
• /
• 2013

Effortful directed attention becomes fatigued if it is demanded by environment. Kaplan and Kaplan's Attention Restoration Theory (ART) proposes that the fatigued directed attention can be restored by a restorative landscape. The four restorative components are being away, fascination, extent, and compatibility. The restorative effect of landscape has been mainly investigated in terms of nature vs. urban dichotomy, although ART acknowledges that various types of landscapes can induce restorative effect. The purpose of this study is to examine whether sense of place of landscape has an influence on the restorative effect, and how the effect relates to the visiting experience. This study was performed in An-Ap-Ji with 200 Korean visitors who participated in the questionnaire survey. Hartig et al.'s PRS (Perceived Restorativeness Scale) was used as the research instrument to measure the restorative quality. The Analysis results are summarized as: 1) PRS was a very reliable measurement for Koreans' assessment of traditional landscape. Especially, the factor analysis produced four restorative components which fully supported ART. 2) The sense of place of landscape was found to have a positive influence on the restorative effect. 3) Landscape beauty was also discovered to be influential in the restoration even though the effect of beauty was lower than that of the sense of place. 4) Among the four restorative components, three components (fascination, escape, compatibility) influenced both visiting satisfaction and revisit intention, where the order of the relevant importance was fascination, escape, and compatibility. Based on the results, it was suggested that PRS should be used in landscape restoration research in Korea in order to re-examine its' reliability. It was also proposed that more research should be directed to investigate the relationship between the sense of place and the restorative effect of landscape.

• Journal of Ecology and Environment
• /
• v.30 no.1
• /
• pp.75-80
• /
• 2007

This study evaluated the effects of rehabilitation of existing coal mining spoils on species composition and species diversity. The species composition of most rehabilitated stands differed from that of the reference stands, and thus did not suggest successful rehabilitation. However, stands subjected to restorative treatment many years ago showed higher species diversity than the reference stands and thereby met the goals of rehabilitation. Our results demonstrate that restorative treatments practiced in the past created a heterogeneous ecological space with regard to the surrounding areas. Therefore, even though species diversity increased several years after rehabilitation, this does not indicate that the treatment achieved true rehabilitation success. The treatment did result in temporary stability through increased species diversity, but it could not be described as successful rehabilitation in terms of biological integrity with the surrounding ecosystems.

• Journal of Technologic Dentistry
• /
• v.31 no.1
• /
• pp.63-74
• /
• 2009

Partial or complete prosthesis is needed when teeth are lost due to various kinds of reason. Artificial teeth recover occlusion instead of natural teeth. Artificial teeth are required of esthetics, fragile resistance and abrasive resistance. Artificial tooth is made of acrylic resin or porcelain. Nowadays, acrylic resin artificial teeth are mainly used. Acrylic resin teeth are occluded with natural teeth, gold alloy, Ni-Cr alloy or porcelain etc. Acrylic resin teeth have similar translucency, gloss of natural teeth. And it has good chemical bond with denture base material, but it has low wear resistance. The aim of this study is to compare wear resistance among several denture teeth(Endura, SR-orthosit-PE, Planustar) and between artificial resin denture teeth and opposing 3 restorative materials(gold, Ni-Cr alloy, porcelain). Wear tests were conducted with a rotating wear testing apparatus(pin-on-disk type wear tester) under conditions of rpm 180, 75 minutes and constant loading of 50N. The upper part was the cusp of maxillary first molar and the lower part was a disk type restorative materials. To make similar oral environment, water was supplied continually. The acrylic resin teeth wear was determined by weighing the cusp each 5 minutes during 75 minutes test. Vicker's hardness tester was used to evaluate the surface hardness of test specimens. The SEM was used to evaluate the wear surfaces. The results were as follows: 1. Wear rates of acrylic resin teeth opposing to the restorative materials were high in order of Porcelain, Gold, Ni-Cr alloy (p<.05). 2. Wear resistance rate opposing to the Porcelain disk, was shown in order of Endura, SR-orthosit-PE, Planustar. The wear rate of opposing to porcelain disk was above two times more than that of other groups (p<.05). 3. Wear resistance rates opposing to the Gold, Ni-Cr alloy disk, was shown in order of Endura, SR-orthosit-PE, Planustar (p<.05). 4. A degree of the surface hardness is directly proportional to the degree of wear resistance. There are statistically significant differences between each groups (p<.05).

• Structural Engineering and Mechanics
• /
• v.64 no.6
• /
• pp.819-826
• /
• 2017

The effects of thermocycling procedure and material shade on the mechanical properties and wear resistance of resin-based dental restorative materials are investigated. The modulus of elasticity, hardness, plasticity index and wear resistance are determined for the conventional composite, the nanohybrid composite and the nanofilled dental composites. Disc-shape samples are prepared from each material to investigate the effects of thermocycling procedure on the mechanical properties and wear resistance of different types of dental restorative materials. In this respect, a group of samples is thermocycled and the other group is stored in ambient conditions. Then nano-indentation and nano-scratch tests are performed on the samples to measure their mechanical properties and wear resistance. Results show that the A1E shade of the dental nanocomposite possesses higher modulus of elasticity and hardness values compared to the two other shades. According to the experimental results, the mean values for the modulus of elasticity and hardness of the A1E shade of the nanocomposite are 13.71 GPa and 1.08 GPa, respectively. The modulus of elasticity and hardness of the conventional dental composite increase around 30 percent in the oral environment due to the moisture and temperature changes. The wear resistance of the dental composites is also significantly affected by moisture and temperature changes in the oral conditions. It is observed that thermocycling has no significant effect on the hardness, plasticity index and wear resistance of the nanohybrid composite and the nanocomposite dental materials.

• KIEE International Transactions on Power Engineering
• /
• v.3A no.3
• /
• pp.155-160
• /
• 2003

Reliability assessment of power systems has been an important topic for the past several decades. It is becoming even more important nowadays as the power market moves toward a new competitive environment. This paper deals with two topics on reliability assessment. The first is how to select probability distributions and determine their parameters to model the probabilistic events in a power system. The second is how to consider restorative actions in the assessment, which directly influence reliability indices. This paper proposes simple but convincing alternative solutions on the two topics. In the case study, this paper shows the influences of the probability distributions that are used in power system modeling.

• Journal of People, Plants, and Environment
• /
• v.23 no.3
• /
• pp.277-291
• /
• 2020

Background and objective: The purpose of this study is to investigate the effects of visitors' positive emotions on satisfaction and loyalty with the perception of restorative environment of a healing garden created in an urban agriculture expo. Methods: The psychological indicators to the images of the healing garden were analyzed by the visitors' demographic variables and the three factors of plant cultivation activity level: plant cultivation experience, plant preference, and plant-related event. Results: Between age groups and occupational groups, significant differences were found statistically. The Perceived Restorativeness Scale(PRS) showed significantly differences between age groups in repose, fascination and legibility. The Positive Affect & Negative Affect Schedule(PANAS) showed statistically significant differences between age groups in positive emotions. In addition, we investigated the correlation between the PANAS and the three factors of plant cultivation experience level, the four factors of the PRS, satisfaction and loyalty. The three factors of plant cultivation experience level, the four factors of the PRS, satisfaction and loyalty showed a positive correlation with positive emotions and were inversely correlated with negative emotions significantly. Multiple regression analysis with dummy variables was conducted to examine the effects of plant cultivation activity level, attention restoration, and the PANAS on healing garden visitors' satisfaction and loyalty. As a result, among the four factors of the PRS, fascination and positive affectivity were significant variables that affect healing garden visitors' satisfaction and loyalty. Conclusion: The results indicated that the higher the attention restoration of visitors due to the fascination of the healing garden and the higher their positive affectivity and the more they have plant-related memories, the higher their impact on healing garden visitors' satisfaction and loyalty. Therefore, fascinating natural environments or greenery landscapes like healing gardens where people can contact plants would reduce negative emotions such as anger and sadness but to increase positive emotions such as pleasure, joy and satisfaction.

• Water Engineering Research
• /
• v.6 no.3
• /
• pp.131-147
• /
• 2005

Today, a trend that tries to return the artificial space of a river to a natural one is expanding. But in Korea, which lies in the monsoon climate zone, rivers endure flood damage every year. Moreover, climatic change from global warming causes severe variations in precipitation patterns. Until recently, river restoration practices in Korea have followed partial restoration. These restorative treatments transformed artificial structures of the stream to natural ones and introduced natural vegetation by imitating natural or semi-natural streams. Treatment transformed the riparian structure and increased the diversity of micro-topography and vegetation. Furthermore, restoration recovered species composition, increased species diversity, and inhibited the establishment of exotic species. In particular, the Suip stream, which was left to its natural process for approximately 50 years, recovered its natural features almost completely through passive restoration. An urban stream, the Yangjae, and a rural stream, the Dongmoon, were restored partially by applying ecological principles. On the contrary, technological treatment applied to recover flood damage induced species composition far from the natural vegetation and decreased species diversity. Additionally, this treatment increased exotic species. The same results were found also in benthic invertebrate and fish fauna. The above-mentioned results reflect the importance of ecological considerations in river management.

• Restorative Dentistry and Endodontics
• /
• v.40 no.2
• /
• pp.104-112
• /
• 2015

Objectives: This study was performed to investigate the effects of different intracanal medicaments on chemical structure and microhardness of dentin. Materials and Methods: Fifty human dentin discs were obtained from intact third molars and randomly assigned into two control groups and three treatment groups. The first control group received no treatment. The second control group (no medicament group) was irrigated with sodium hypochlorite (NaOCl), stored in humid environment for four weeks and then irrigated with ethylenediaminetetraacetic acid (EDTA). The three treatment groups were irrigated with NaOCl, treated for four weeks with either 1 g/mL triple antibiotic paste (TAP), 1 mg/mL methylcellulose-based triple antibiotic paste (DTAP), or calcium hydroxide [$Ca(OH)_2$] and finally irrigated with EDTA. After treatment, one half of each dentin disc was subjected to Vickers microhardness (n = 10 per group) and the other half was used to evaluate the chemical structure (phosphate/amide I ratio) of treated dentin utilizing attenuated total reflection Fourier transform infrared spectroscopy (n = 5 per group). One-way ANOVA followed by Fisher's least significant difference were used for statistical analyses. Results: Dentin discs treated with different intracanal medicaments and those treated with NaOCl + EDTA showed significant reduction in microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.05) compared to no treatment control dentin. Furthermore, dentin discs treated with TAP had significantly lower microhardness (p < 0.0001) and phosphate/amide I ratio (p < 0.0001) compared to all other groups. Conclusions: The use of DTAP or $Ca(OH)_2$ medicaments during endodontic regeneration may cause significantly less microhardness reduction and superficial demineralization of dentin compared to the use of TAP.