• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.6
• /
• pp.193-198
• /
• 2021

In this study, the rheological characteristics and of 3D printing composite materials and the compressive strength characteristics according to the lamination patterns were evaluated. As a result of rheology test, rapid material change was observed after 60 minutes of extrusion, yielding stress 1.4 times higher than immediately after mixing, and plastic viscosity was 14.94-25.62% lower. The compressive strength of the specimens manufactured in the mold and the laminated specimens were compared, and the lamination pattern of the laminated specimens were 0°, 45°, and 90° as variables. The compressive strength of the mold casting specimen and the laminated specimen from 1 to 28 days of age showed similar performance regardless of the lamination pattern. In particular, at the age of 28 days, the modulus of elasticity, maximum compressive strength, and strain at maximum stress of all specimens were almost the same. In order to analyze the interface of the laminated specimens, X-ray CT analysis of the specimen whose compressive strength were measured was performed. Through CT analysis, it was confirmed that cracks did not occur at the lamination interface, which can be judged that the interface in the laminated specimen behaved in an integrated manner.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.6
• /
• pp.73-81
• /
• 2022

Recently, as the service life of structures increased, the load-carrying capacity of deteriorated reinforced concrete, where corrosion of reinforcing bars occurs due to various causes, is frequently decreased. In order to address this problem, many studies on the bond characteristic of FRP (Fiber Reinforced Polymer) bars with corrosion resistance, light weight and high tensile strength have been conducted, however there are not many studies on the bond characteristic of grid-typed CFRP embedded in concrete. Therefore, in order to evaluate the bond characteristics of grid-typed CFRP and its usability as a substitute for steel rebar, a pull-out test is performed using the longitudinal bond length and transverse grid length of the grid-typed CFRP as variables. Through the pull-out test, the bond load-slip curve of the grid-typed CFRP is derived, and the bond behavior is analyzed. The total bond load equation is proposed as the sum of the bond force of the longitudinal bond length and the shear force of the grid in the transverse direction. Also, expressing the area of the bond load-slip curve as total work, the change in dissipated energy with respect to the slip is analyzed to examine the effect of the tranverse grid on the bond force.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.1
• /
• pp.119-129
• /
• 2023

In many cases, trauma is overcome in a short periodtime, but for some, trauma results in long-term mental health issues such as in the form of post-traumatic stress disorder (PTSD). Natural disasters cause different types and extent of damage, meaning the degree of stress experienced also varies. In the case of damage to a house, the impact can be considerable. Therefore, this study examined the trauma experienced by households whose homes were damaged by natural disasters and to confirm the characteristics of psychological trauma. It was confirmed that traumas was greater when a house was damaged, compared with damage to other types of items. In addition, even in the case of trauma occurring, factors that affect the pattern of change to someone's mental state vary depending on the state's classification. And In addition, health services is significantly analyzed in all variables, and it was considered that the provision of basic services related to safety after a disaster is paramount. However, while psychological counseling has a positive effect on short-term traumas that manifests as anxiety and depression, it has an adverse effect on PTSD because of the depth and complexity of the suffering in PTSD, meaning the type of psychological support needs changing.

• 한국노년학
• /
• v.25 no.2
• /
• pp.53-71
• /
• 2005

Objectives: The purposes of this study were to investigate CHPs' knowledge, attitude, and practice regarding UI, and to identify predictors of their UI related practice. Methods: A descriptive-correlational study using self-administered questionnaire was conducted. A total of 330 members of the local Korean Association of CHPs were included in this study. A mailed survey was conducted to collect data. Findings: Of CHPs surveyed, 170(51.5%) returned completed questionnaire. Educational preparation of CHPs regarding UI was limited. The mean correct score of knowledge scale was 68.96%. Overall, CHPs exhibited positive attitudes toward UI. CHPs in this study were not actively participate UI related practice. Contrary to expectation, knowledge was not significantly related to CHPs' practice regarding UI. In the final analysis, CHPs' practice regarding UI was predicted by attitude toward the care of UI clients and educational needs for UI and these two variables explained 9% of variance of UI related practice. Conclusion: The results of this study suggest the importance of attitude and educational needs in shaping UI related practice among CHPs. To facilitate UI related practice among CHPs, efforts for attitudinal change related to UI among CHPs are needed. Moreover, continuing educational program for UI management should be developed, applied and evaluated.

• Korean Journal of Environment and Ecology
• /
• v.32 no.5
• /
• pp.469-477
• /
• 2018

Hanabusaya asiatica is an endemic species whose distribution is limited in the mid-eastern part of the Korean peninsula. Due to its narrow range and small population, it is necessary to protect its habitats by identifying it as Key Biodiversity Areas (KBAs) adopted by the International Union for Conservation of Nature (IUCN). In this paper, we estimated potential natural habitats for H. asiatica using maximum entropy model (MaxEnt) and identified candidate sites for KBA based on the model results. MaxEnt is a machine learning algorithm that can predict habitats for species of interest unbiasedly with presence-only data. This property is particularly useful for the study area where data collection via a field survey is unavailable. We trained MaxEnt using 38 locations of H. asiatica and 11 environmental variables that measured climate, topography, and vegetation status of the study area which encompassed all locations of the border region between South and North Korea. Results showed that the potential habitats where the occurrence probabilities of H. asiatica exceeded 0.5 were $778km^2$, and the KBA candidate area identified by taking into account existing protected areas was $1,321km^2$. Of 11 environmental variables, elevation, annual average precipitation, average precipitation in growing seasons, and the average temperature in the coldest month had impacts on habitat selection, indicating that H. asiatica prefers cool regions at a relatively high elevation. These results can be used not only for identifying KBAs but also for the reference to a protection plan for H. asiatica in preparation of Korean reunification and climate change.

• Journal of Oral Medicine and Pain
• /
• v.38 no.2
• /
• pp.203-213
• /
• 2013

Objecives : The purpose of the study was to evaluate treatment outcome of mandibular advancement device(MAD) in obstructive sleep apnea (OSA) patients using full night polysomnography and cephalometry. Methods : Twenty-seven OSA patients were confirmed by full night, lab-attended polysomnography. Cephalometric examinations were conducted to obtain SNA, ANB, $AH{\bot}MP$, AH-C3, SPT, PNS-U, NAS, SOAS, MOAS, and HAS. Mandibular advancement devices (MADs) were fabricated and delivered for all subjects. After acclimation period of MAD, the second polysomnographic examinations were conducted in the same manner. Polysomnographic variables were compared between before and after MAD placement. Also, correlation coefficients were calculated between apnea-hypopnea index (AHI) and each item of cephalometric parameters. Results : There were significant improvements in total AHI, lowest $SpO_2$, and total arousal index after MAD therapy. Also, there were significant improvements in NREM $SpO_2$ and NREM AHI, but not in REM $SpO_2$ and REM AHI with MAD. Stratifying the sleep stage, there were significant decrease in stage I and significant increases in stage II and REM, but change in stage III was not significant. SNA and SOAS were significantly correlated with total AHI and NAS was significantly correlated with supine AHI. ANB was significantly associate with the effect of MAD. Conclusions : MAD is an effective treatment in OSA patients comparing polysomnographic variables before and after treatment. Cephalometric examination can be useful to evaluate OSA patients and predict treatment outcome of MAD.

• Journal of Energy Engineering
• /
• v.22 no.4
• /
• pp.370-375
• /
• 2013

This paper attempts to estimate the city gas demand function in Korea over the period 1981-2012. As the city gas demand function provides us information on the pattern of consumer's city gas consumption, it can be usefully utilized in predicting the impact of policy variables such as city gas price and forecasting the demand for city gas. We apply lagged dependent variable model and ordinary least square method as a robust approach to estimating the parameters of the city gas demand function. The results show that short-run price and income elasticities of the city gas demand are estimated to be -0.522 and 0.874, respectively. They are statistically significant at the 1% level. The short-run price and income elasticities portray that demand for city gas is price- and income-inelastic. This implies that the city gas is indispensable goods to human-being's life, thus the city gas demand would not be promptly adjusted to responding to price and/or income change. However, long-run price and income elasticities reveal that the demand for city gas is price- and income-elastic in the long-run.

• Journal of the Korean Geosynthetics Society
• /
• v.17 no.3
• /
• pp.19-32
• /
• 2018

Gravel Compaction Pile (GCP) method is currently being designed and constructed by empirical method because quantitative design method has not been developed, leading to various types of and frequent destruction such as expansion failure and shear failure and difficulties in establishing clear cause and developing measure to prevent destruction. In addition, despite the difference with domestic construction equipment and material characteristics, the methods applied to the overseas ground is applied to the domestic as it is, leading to remarkable difference between applied values and measured values in variables such as bearing capacity and the settlement amount. The purpose of this study was, therefore, to propose a reasonable and safe design method of GCP method by analyzing the settlement and stress behavior characteristics according to ground strength change under GCP method applied to domestic clay ground. For the purpose, settlement amount of composite ground, stress concentration ratio, and maximum horizontal displacement and expected location of GCP were analyzed using ABAQUS. The results of analysis showed that the settlement and Settlement reduction rate of composite ground decreased by more than 60% under replacement ratio of 30% or more, that the maximum horizontal displacement of GCP occurred at the depth 2.6 times pile diameter, and that the difference in horizontal displacement is slight under replacement ratio of 30%.

• Journal of Korea Water Resources Association
• /
• v.45 no.8
• /
• pp.827-837
• /
• 2012

The estimation of the rainfall quantile is of great importance in designing hydrologic structures. Conventionally, the rainfall quantile is estimated by univariate frequency analysis with an appropriate probability distribution. There is a limitation in which duration of rainfall is restrictive. To overcome this limitation, bivariate frequency analysis by using 3 copula models is performed in this study. Annual maximum rainfall events in 5 stations are used for frequency analysis and rainfall depth and duration are used as random variables. Gumbel (GUM), generalized logistic (GLO) distributions are applied for rainfall depth and generalized extreme value (GEV), GUM, GLO distributions are applied for rainfall duration. Copula models used in this study are Frank, Joe, and Gumbel-Hougaard models. Maximum pseudo-likelihood estimation method is used to estimate the parameter of copula, and the method of probability weighted moments is used to estimate the parameters of marginal distributions. Rainfall quantile from this procedure is compared with various marginal distributions and copula models. As a result, in change of marginal distribution, distribution of duration does not significantly affect on rainfall quantile. There are slight differences depending on the distribution of rainfall depth. In the case which the marginal distribution of rainfall depth is GUM, there is more significantly increasing along the return period than GLO. Comparing with rainfall quantiles from each copula model, Joe and Gumbel-Hougaard models show similar trend while Frank model shows rapidly increasing trend with increment of return period.

• Journal of Internet Computing and Services
• /
• v.10 no.1
• /
• pp.145-158
• /
• 2009

No other change in Kora has offered gredter chalenges and opportunities than the emergence of the Internet and its related Information Technology. In the technology for accessing the ever growing wave of information. The quality of the silver generation is increasingly difficult to achieve because of the complexities of life in today's ICT(Information & Comunication Technology) dependent society, Life is more interesting when one knows what is going on, what opportunities exist, and when alternatives to current practices can be discovered and utilized with ease. The purpose of this study is to identify the determinants of attitude and planned behavior toward using internent for the quality of life. This study employ the intention to use internet, perceived ease of use, perceived usefuiness, self-efficacy, stress factor, generation gap, and income as major research variables, and collected 288 survey responses from senior citizen over 55. The results indicate that the perceived usefuiness and ease of use influence the intention to use internet, and that the self-efficacy, the ease of use and generation gap has some impact on the attitude, but the stree factor and the income level do not appear significant to the attitude. It was also found that the self-efficacy and the income level determine the level of ease of use. In addition, some useful suggestions concerning the continuing education program for silver generations are presented.