• Journal of the Korean Geotechnical Society
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• v.32 no.1
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• pp.35-43
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• 2016

The time distribution of rainfall is one of the most important considerations for evaluating soil slope stability. In order to study the rainfall-induced slope failure, the rainfall pattern has generally been assumed as uniform rainfall intensity for rainfall duration. However, it should be noted that the time distribution of the design rainfall method has a significant effect on the soil slope instability. The study implemented Mononobe, Huff, and uniform method as three types of time distribution method of the design rainfall to estimate the factor of safety of soil slopes by rainfall duration. As a result, the difference of soil suction and unsaturated hydraulic properties in a soil by rainfall pattern was found through the application of an appropriate time distribution method to numerical simulation for rainfall-induced slope stability.

• International Journal of Concrete Structures and Materials
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• v.9 no.2
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• pp.159-172
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• 2015

Estimation of the residual strength of corroded reinforced concrete beams has been studied from experimental and theoretical perspectives. The former is arduous as it involves casting beams of various sizes, which are then subjected to various degrees of corrosion damage. The latter are static; hence cannot be generalized as new coefficients need to be re-generated for new cases. This calls for dynamic models that are adaptive to new cases and offer efficient generalization capability. Computational intelligence techniques have been applied in Construction Engineering modeling problems. However, these techniques have not been adequately applied to the problem addressed in this paper. This study extends the empirical model proposed by Azad et al. (Mag Concr Res 62(6):405-414, 2010), which considered all the adverse effects of corrosion on steel. We proposed four artificial neural networks (ANN) models to predict the residual flexural strength of corroded RC beams using the same data from Azad et al. (2010). We employed two modes of prediction: through the correction factor ($C_f$) and through the residual strength ($M_{res}$). For each mode, we studied the effect of fixed and random data stratification on the performance of the models. The results of the ANN models were found to be in good agreement with experimental values. When compared with the results of Azad et al. (2010), the ANN model with randomized data stratification gave a $C_f$-based prediction with up to 49 % improvement in correlation coefficient and 92 % error reduction. This confirms the reliability of ANN over the empirical models.

• Korean Journal of Occupational Health Nursing
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• v.22 no.3
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• pp.228-239
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• 2013

Purpose: This study aims to assess the effects of psychosocial work environment and self-efficacy on stress, depression, and burn-out among office workers. Methods: Survey data were collected from 331 office workers who worked in one workplace from April 10 to 30, 2012. The impact of psychosocial work environment and self-efficacy on stress, depression, and burn-out was analyzed with hierarchical multiple regression using SAS version 9.3. Results: Work-family conflicts and emotional demands were identified as main factors influencing mental health. Other work environment factors influencing mental health were role clarity for stress, possibilities for development, meaning-of work, social support-from supervisors and job insecurity for depression, and social community at work for burn-out. Self-efficacy was correlated with most psychosocial work environment and factor with independent influence on stress and depression. The final models including general characteristics, psychosocial work environment, and self-efficacy accounted for 34%, 44%, and 36% for stress, depression, and burn-out respectively. Conclusion: To promote mental health in office workers, there is a need to decrease work-family conflicts and emotional demands and to improve work organization and job contents, social support, and self-efficacy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.4
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• pp.393-400
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• 2020

Axial and lateral behavior of helical piles is generally influenced by number, diameter, helix pitch, and locations of helices. In this study, axial and horizontal behavior of helical piles with three helices was investigated varying helices' locations, diameter, and pitch. Especially, due to the spiral shapes of helices, the effect of lateral load directions at pile heads on their lateral behavior was investigated. Axial load test of small-scale helical pile was conducted in laboratory, and its results were compared with numerical analysis results of the same model for cross check of validity of both results. Furthermore, diverse numerical analyses were performed for different shapes of helical piles. Consequently, it was found that, for the given analysis conditions, the helix diameter was the most influential factor on the horizontal and vertical behavior of helical piles.

• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2002.06a
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• pp.123-135
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• 2002

Being in era of the digital economy, the influence of IT that effects on our economy is getting greater. Along with this effect, IT becomes origin of predominance of competition in every category of industry. Regarding new trends in industry, how companies mutate their IT skill become important factor. Every industry has their own color and environment of IT and uncertainty is different. For a company, It is most important to plan own strategy with strategic view on industrial environment. The idea of this study is to find the difference of Skill Requirement and Job Requirement in every category of industry by find what are the most important jobs and skills of IT in every industry and to analyze the results. The second idea is to find what kinds of skill are required in every sector of job. Base on the analyzed data, we classified the uncertainty in every industry by Duncan′s "classification of environment", and extracted some pattern within the skill and job in industry that found in our study by applying OIP model. We set skills by categorized curriculum of specialized IT education center, then with IT specialist, checked and retouched the results and surveyed with IT people in every industry on skill set and job of IT. The summery of this study is as follow : 1. Importance of IT skill is differentiated in each industry. It shows that IT skills, which requested in a field are differentiated by uncertainty of environment that comes from the character of industry. 2. Importance of IT job differs by the fields of industry. It shows as IT skills are differentiated, the importance of job that apply these skills is differentiated. 3. As the character of each job that work on is diversified, the importance of skills are diversified in each field of jobs. The Result of this study can give the idea to who designs curriculum and builds educational contentsthat would fulfill the need of fields. Also this study would be meaningful that it opens the field of study of skill requirement in Korea.

• Journal of the Korean Society of Food Culture
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• v.26 no.4
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• pp.331-343
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• 2011

A survey of consumer awareness and attitudes was conducted about genetically modified (GM) foods and the labeling regulations. The questionnaires were distributed to 4,620 consumers who lived in a variety of areas in Korea, and 4,076 people responded. The consumers were asked about knowledge, labeling information, and the source of obtaining information about GM foods. More than 11.5% of the consumers had never heard about GM foods and 86.9% of consumers had less than a normal level of knowledge about GM foods. No statistically significant relationship was found between genders, but the teachers group had moderate knowledge (p<0.001). In total, 28.4% of consumers did not know the GMO labeling regulations. They answered that the reason to buy GM food was do not know>nothing wrong>create benefit>think as safe>inexpensive. The answers to the question of what was the first benefit were: solve food shortage>functional and nutritious food>cultivate in bad condition>nothing>various cultivars. They answered that the worst factor was the next generation effect>environmental disruption. Regarding the development of GM food in Korea, males answered do not know>stronglyrecommend>defer>strongly suppress. Female answered: don't know>defer>strongly recommend>strongly suppress. More than half of the respondents did not have much information about GM foods; 88.3% of respondents answered they did not have educational experience about GM food.

• Toxicological Research
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• v.34 no.1
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• pp.7-12
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• 2018

Laboratory animal models have been developed to investigate preventive or therapeutic effect of medicinal products, or occurrence or progression mechanism of atopic dermatitis (AD), a pruritic and persistent inflammatory skin disease. The murine model with immunologic phenomena resembling human AD was introduced, which demonstrated skewedness toward predominance of type-2 helper T cell reactivity and pathophysiological changes similar as human AD following 2,4-dinitrochlorobenzene (DNCB) sensitization and challenge. Molecular mechanism on the DNCB-mediated AD was further evaluated. Skin tissues were collected from mice treated with DNCB, and each tissue was equally divided into two sections; one for protein and the other for mRNA analysis. Expression of filaggrin, an important protein for keratinocyte integrity, was evaluated through SDS-PAGE. Level of mRNA expression for cytokines was determined through semi-quantitative reverse transcriptase polymerase chain reaction. Expression of filaggrin protein was significantly enhanced in the mice treated with DNCB compared with the vehicle (acetone : olive oil = 4 : 1 mixture) treatment group or the normal group without any treatment. Level of tumor necrosis factor-alpha and interleukin-18 mRNA expression, cytokines involved in activity of type-1 helper T ($T_H1$) cell, was significantly downregulated in the AD group compared with other control groups. These results suggest that suppression of $T_H1$ cell-mediated immune response could be reflected into the skin tissue of mice treated with DNCB for AD induction, and disturbance of keratinocyte integrity might evoke a compensatory mechanism.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1560-1565
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• 2011

The environmental pollution caused by green-house gases such as $CO_2$ and $SF_6$ has been becoming the main issue of industrial society. Many developed countries are making efforts to minimize the amount of $CO_2$ emission come from the operation of high voltage electrical apparatuses. As a part of these efforts, 180 countries signed the Kyoto Protocol in 1997 to cut back on their green-house gas emissions. Nowadays, the study on the development of dry air insulated switchgear (DAIS) which is known as an eco-friendly electrical apparatus is in progress. A DAIS is advantageous for minimizing the effect of impurities and enhancing the dielectric characteristics over an air insulated switchgear (AIS) by applying constant pressure to an enclosed cubicle. Therefore, a study on the electrical insulation performance of dry air as a gaseous insulation medium is conducted in this paper to substitute a gas insulated switchgear (GIS) for DAIS. As results, it is verified that the AC dielectric characteristics of dry air are similar to those of air and the lightning impulse dielectric characteristics of dry air are superior to those of air at 1bar pressure condition. However, dry air is of inferior dielectric characteristics to $SF_6$ at 4bar pressure condition. Finally, it is suggested that the internal pressure of DAIS should be over 4bar pressure to develop a high voltage switchgear which has similar electrical performance to a conventional GIS. Also, the empirical formulae on calculating the maximum electric field intensity at sparkover of dry air are deduced by experiments according to pressures. It is expected that these results are helpful to design and develop a high voltage electrical apparatus.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.1
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• pp.18-27
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• 2020

Objectives: For testing asbestos stabilizer products which are used for the maintenance and management of asbestos-containing materials, durability assessment should accompany the evaluation of basic properties and performance. Therefore, in this study we designed a testing method and constructed a database of durability performance, thereby providing basic data for reliability studies of asbestos stabilizer. Methods: Since the ceiling materials targeted in this study are interior materials, test conditions of 95% relative humidity and 60℃ temperature were designed in consideration of the effect of high relative humidity in summer and seasonal indoor temperatures. Plate-shaped specimens treated with asbestos stabilizers were maintained in a thermo-hygrostat for 5, 10, and 20 days, and then the asbestos scattering prevention rate was measured by air erosion testing. Results: The scattering concentration tended to increase with time under the single humidity condition, and exceeded the indoor air quality standard of 0.01 f/cc, during the 20 days of maintenance. On the other hand, there was little change according to the temperature condition. In the case of a complex condition with temperature and humidity, the results were similar to the humidity test, but the scattering concentration increased more sharply at 20 days. Conclusions: The main deterioration factor that affects the durability of asbestos stabilizer is humidity, and the deterioration is caused by a mechanism in which the stabilizer coated on the surface is re-dissolved by moisture and evaporates or the coating layer is peeled off, which is accelerated by high temperatures.

• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.437-443
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• 2003

Bioremediation technologies were applied to experimental microcosms, simulating an oil spill in a lower intertidal area. Three treatments (oil only, oil plus nutrients, and oil plus nutrients and microbial inocula) were applied, and each microcosm was repeatedly filled and eluted with seawater every 12 h to simulate tidal cycles. To minimize washing-out of the inoculum by the tidal cycles, microbial cells were primarily immobilized on diatomaceous earth before they were applied to the oiled sand. Oil degradation was monitored by gravimetric measurements, thin layer chromatography/flame ionization detector (TLC/FID) analysis, and gas chromatography (GC) analysis, and the loss of oil content was normalized to sand mass or nor-hopane. When the data were normalized to sand mass, no consistent differences were detected between nutrient-amended and nutrient/inoculum-amended microcosms, although both differed from the oil-only microcosm in respect of oil removal rate by a factor of 4 to 14. However, the data relative to nor-hopane showed a significant treatment difference between the nutrient-amended and nutrient/inoculum-treated microcosms, especially in the early phase of the treatment. The accelerating effect of inoculum treatment has hardly been reported in studies of oil bioremediation in the Tower intertidal area. The inoculum immobilized on diatomaceous earth seemed to be a very effective formulation for retaining microbial cells in association with the sand. Results of this study also suggest that interpretation of the effectiveness of bioremediation could be dependent on the selection of monitoring methods, and consequently the application of various analytical methods in combination could be a solution to overcome the limitations of oil bioremediation monitoring.