• Journal of the Korea Institute of Building Construction
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• v.22 no.5
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• pp.425-430
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• 2022

Concrete used for the foundation of high-rise buildings is often placed through in an integrated pouring to ensure construction efficiency and quality. However, if concrete is placed integrally, there is a high risk of temperature cracking during the hydration reaction, and it is necessary to determine the optimal mixing design of high-performance, high-durable concrete through the replacement of the admixture. In this study, experiments on salt damage, carbonation, and sulfate were conducted on the specimen manufactured from the optimal high-performance low-heating concrete combination determined in the author's previous study. The resistance of the cement matrix to chlorine ion diffusion coefficient, carbonation coefficient, and sulfate was quantitatively evaluated. In the terms of compression strength, it was measured as 141% compared to the structural design standard of KCI at 91 days. Excellent durability was expressed in carbonation and chlorine ion diffusivity performance evaluation. In particular, the chlorine ion diffusion coefficient, which should be considered the most strictly in the marine environment, was measured at a value of 4.09×E-12m²/y(1.2898×E-10m²/s), and is expected to be used as a material property value in salt damage durability analysis. These results confirmed that the latent hydroponics were due to mixing of the admixture and high resistance was due to the pozzolane reaction.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.4
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• pp.235-250
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• 2017

In this study, we monitored 4 volatile organic compounds (VOCs) such as chloroform, dichloromethane, 1,2-dichloroethane, and tetrachloromethane in groundwater samples to determine the detection frequency and their concentrations and evaluated the health risk level considering ingestion, inhalation, and skin contact. 75 groundwater wells were selected. 24 wells were from monitoring background groundwater quality level and 51 wells were from monitoring groundwater quality level in industrial or contamination source area. In the results, the detection frequency for chloroform, dichloromethane, 1,2-dichloroethane, and tetrachloromethane was 42.3%, 8.1%, 6.0%, and 3.4%, respectively. The average concentrations of VOCs were high in the order of chloroform ($1.7{\mu}g\;L^{-1}$), dichloromethane ($0.08{\mu}g\;L^{-1}$), tetrachloromethane ($0.05{\mu}g\;L^{-1}$), and 1,2-dichloroethane ($0.05{\mu}g\;L^{-1}$). Chloroform had the highest detection frequency and average detection concentration. In the contaminated groundwater, the detection frequency of VOCs was high in the order of chloroform, dichloromethane, 1,2-dchloroethane, and tetrachloromethane. The average concentrations for chloroform, dichloromethane, 1,2-dichloroethane, and tetrachloromethane were $2.23{\mu}g\;L^{-1}$, $0.08{\mu}g\;L^{-1}$, $0.07{\mu}g\;L^{-1}$, and $0.06{\mu}g\;L^{-1}$, respectively. All the 4 compounds were detected at industrial complex and storage tank area. The maximum concentration of chloroform, dichloromethane, and 1,2-dichloroethane was detected at industrial complex area. Especially, the maximum concentration of chloroform and dichloromethane was detected at a chemical factory area. In the uncontaminated groundwater, the detection frequency of VOCs was high in the order of chloroform, dichloromethane, and 1,2-dchloroethane and tetrachloromethane was not detected. The average concentrations for chloroform, dichloromethane, and 1,2-dichloroethane were $0.57{\mu}g\;L^{-1}$, $0.07{\mu}g\;L^{-1}$, and $0.03{\mu}g\;L^{-1}$, respectively. Although chloroform in the uncontaminated groundwater was detected the most, the concentration of chloroform was not exceeding water quality standards. By land use, the maximum detection frequency of 1,2-dichloroethane was found near a traffic area. For human risk assessment, the cancer risk for the 4 VOCs was $10^{-6}{\sim}10^{-9}$, while the non-cancer risk (HQ value) for the 4 VOCs is $10^{-2}{\sim}10^{-3}$.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.419-431
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• 2007

The track and rail surface geometry is of prime importance on the requirement for track dynamic stiffness, particularly for the speed of 350 km/h, for which both the requirement for fatigue and tensile strength limits require a lower stiffness than 100 kN/mm, which is near the value for ballasted track. However, the track quality has been considered as being the same for 350 km/h as that for 300 km/h, and based on ballasted track, and the track geometry may be kept in better condition with a slab track(probably more similar to the medium quality track geometry of ballasted track). In conclusion, under the condition that the track geometry quality provided by the concrete slab system is fairly good, and that the required maintenance is applied to the rail surface, there would be no safety risk if the fastening system point stiffness reaches 160 kN/mm for 300 km/h operation, and 110 N/mm at 350 km/h.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.18
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• pp.8293-8298
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• 2016

Background: Urinary stones are known predisposing factors for upper urinary tract carcinoma (UUTC) which are commonly detected at advanced stage with poor outcome because of rarity and lack of specific criteria for early detection. Aims and objectives: The main aim was to evaluate the impact of age, gender andstone characteristics on risk of developing UUTC in patients with chronic nephrolithiasis. We also discuss the role of aberrant angiogenesis (AA) and immunohistochemical expression of p53, p16INK4a, CK20 and Ki-67 in diagnosis of pelvicalyceal neoplastic (NL) and pre-neoplastic lesions (PNL) in these patients. Materials and Methods: Retrospective analysis of pelvicalyceal urothelial lesions from 88 nephrectomy specimens were carried out in a tertiary care centre from June 2012 to December 2014. Immunohistochemistry (IHC) was performed on 37 selected cases. Computed image analysis was performed to analyse aberrant angiogenesis. Results: All UUTC (5.7%) and metaplastic lesions were found to be associated with stones. Some 60% were pure squamous cell carcinoma and 40% were transitional cell carcinoma. Odd ratios for developing NL and PNL lesions in presence of renal stone, impacted stones, multiple and large stag horn stones were 9.39 (95% CI 1.15-76.39, p value 0.05), 6.28 (95% CI 1.59-24.85, p value 0.000) and 7.4 (95% CI, 2.29-23.94, p value 0.001) respectively. When patient age was ${\geq}55$, the odds ratio for developing NL was 3.43 (95% CI 1.19-9.88, p value 0.019). IHC analysis showed that mean Ki-67 indices were $3.15{\pm}3.63%$ for non-neoplastic lesions, $10.0{\pm}9.45%$ for PNL and $28.0{\pm}18.4%$ for NL. Sensitivity and specificity of CK20, p53, p16INK4a, AA were 76% and 95.9%; 100% and 27.5%; 100% and 26.5%; 92.3 % and 78.8% respectively. Conclusions: Age ${\geq}55years$, large stag horn stones, multiple stones and impacted stones are found to be associated with increased risk of NL and PNL in UUT. For flat lesions, a panel of markers, Ki 67 index >10 and presence of aberrant angiogenesis were more useful than individual markers.

• Asia pacific journal of information systems
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• v.30 no.1
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• pp.31-52
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• 2020

Stock markets are popular investment avenues to people who plan to receive premium returns compared to other financial instruments, but they are highly volatile and risky due to the complex financial dynamics and poor understanding of the market forces involved in the price determination. A system that can forecast, predict the stock prices and automatically create a portfolio of top performing stocks is of great value to individual investors who do not have sufficient knowledge to understand the complex dynamics involved in evaluating and predicting stock prices. In this paper the authors propose a Stock prediction, Portfolio Generation and Selection model based on Machine learning algorithms, Artificial neural networks (ANNs) are used for stock price prediction, Mathematical and Statistical techniques are used for Portfolio generation and Un-Supervised Machine learning based on K-Means Clustering algorithms are used for Portfolio Evaluation and Selection which take in to account the Portfolio Return and Risk in to consideration. The model presented here is limited to predicting stock prices on a long term basis as the inputs to the model are based on fundamental attributes and intrinsic value of the stock. The results of this study are quite encouraging as the stock prediction models are able predict stock prices at least a financial quarter in advance with an accuracy of around 90 percent and the portfolio selection classifiers are giving returns in excess of average market returns.

• Magazine of the Korean Society of Agricultural Engineers
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• v.27 no.2
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• pp.23-37
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• 1985

This studies were carried out to get characteristics of frequency distribution, probable flood flows according to the return periods, and the correlation between return periods and those length of records affect the Risk of failure in the annual maximum series of the main river systems in Korea. Especially, Risk analysis according to the levels were emphasized in relation to the design frequency factors for the different watersheds. Twelve watersheds along Han, Geum, Nak Dong, Yeong San and Seom Jin river basin were selected as studying basins. The results were analyzed and summarized as follows. 1. Type 1 extremal distribution was newly confirmed as a good fitted distribution at selected watersheds along Geum and Yeong San river basin. Three parameter lognormal Seom Jin river basin. Consequently, characteristics of frequency distribution for the extreme value series could be changed in connection with the watershed location even the same river system judging from the results so far obtained by author. 2. Evaluation of parameters for Type 1 extremal and three parameter lognormal distribution based on the method of moment by using an electronic computer. 3. Formulas for the probable flood flows were derived for the three parameter lognormal and Type 1 extremal distribution. 4. Equations for the risk to failure could be simplified as $\frac{n}{N+n}$ and $\frac{n}{T}$ under the condition of non-parametric method and the longer return period than the life of project, respectively. 5. Formulas for the return periods in relation to frequency factors were derived by the least square method for the three parameter lognormal and Type 1 extremal distribution. 6. The more the length of records, the lesser the risk of failure, and it was appeared that the risk of failure was increasing in propotion to the length of return periods even same length of records. 7. Empirical formulas for design frequency factors were derived from under the condition of the return periods identify with the life of Hydraulic structure in relation to the risk level. 8. Design frequency factor was appeared to be increased in propotion to the return periods while it is in inverse proportion to the levels of the risk of failure. 9. Derivation of design flood including the risk of failure could be accomplished by using of emprical formulas for the design frequency factor for each watershed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.4
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• pp.729-738
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• 2017

With the signing of the Paris Agreement, which is the new climate change agreement at the end of 2015, it will have a great impact on Korea environmental policy. The construction industry, which accounts for 42% of Korea's total $CO_2$ emissions, has been implementing various policies to improve the environmental problems. However, it is only applying passively to other projects except eco-friendly building certification. This is because most of the eco-related systems are based on building facilities. Therefore, there is a need for a new eco - friendly design evaluation model that can be widely applied not only to architecture but also to civil engineering facilities. In this study, a new model is developed based on the existing VE model, which adds new factors to evaluate the environmental friendliness, potential environmental pollution concept and environmental risk of facilities. This model is an eco-friendly design evaluation model that enables decision makers to effectively select alternative environmental criteria at the design stage. As a result of the case analysis of the block retaining wall and the alternative retaining wall, the value of the eco - friendly value of the alternative was 1.026 times higher than the original one. If this model is used at the design stage, it is expected to contribute not only to the construction of environmentally friendly facilities but also to the reduction of carbon emissions.

• Journal of Biosystems Engineering
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• v.33 no.3
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• pp.151-156
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• 2008

This study was conducted to evaluate ride vibrations experienced by tractor operators during plowing, rotovating, and transporting operations in Korea. Field data of ride vibrations were taken at the operator-seat interface from 49 tractors and analyzed on the basis of ISO 2631-1 and EU Directive 2002/44. Of the measured ride vibrations 15.4% in the plowing and 12.5% in farm road transport exceeded the 8-hour fatigue decreased proficiency boundary in the fore and aft directions at frequencies from 1 to 5 Hz. 93.9% exceeded the 8-hour potential health risk of ISO 2631-1. The ride vibrations exceeding the 8-hour exposure limit were 38.5% in plowing, 31.6% in rotovating, 100% in farm road transport and 88.9% in concrete road transport. Although most tractor operators were not exposed to ride vibrations greater than the 8-hour exposure limit value (ELV) of EU Directive 2002/44, 7.7% of the operators in the plowing experienced greater vibrations than the ELV in the fore-aft direction. Farm road transport produced greater vibrations than any other operations. Concrete road transport, plowing and rotovating operations followed next. Limit criteria for ride vibration exposure differ depending upon the guidelines. Exposure limit of the health guidance caution zone of ISO 2631-1 is lowest among its kinds.

• Korean Journal of Community Nutrition
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• v.23 no.4
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• pp.277-288
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• 2018

Objectives: This study was performed to verify the validity and judgment criteria setting of a health status assessment tool based on dietary patterns for middle-aged women. Methods: A total of 474 middle-aged women who visited the Comprehensive Medical Examination Center at Hanmaeum Hospital in Changwon were enrolled (IRB 2013-0005). The validity was verified using clinical indicators for the diagnosis of metabolic syndrome (MS), and it was used to set the criteria for the tool. A logistic regression analysis was performed for validation. The area under-receiver operation (AUC), sensitivity, specificity, and Youden Index were calculated through ROC curve analysis. Statistical analysis was performed by SPSS 21, and p value <0.05 was considered to be statistically significant. Results: The mean score of the group with no MS (73.3 points) was significantly higher compared to the group with MS (65.7 points) (p<0.001). An analysis of the association between the tool scores and risk of MS showed a 0.15-fold reduction in the risk of MS every time the tool's score increased by one point. As the result of the ROC curve analysis, the assessment reference point was set to 71 points, indicating 77.0% sensitivity and 61.0% specificity. Risk of MS was significantly higher in the group with a score of less than 71.0 than a group with more than 71 points (OR=5.28, p<0.001). Conclusions: This study was the first attempt to develop a health status assessment tool based on the dietary patterns for middle-aged women, and this tool has proven its usefulness as an MS assessment tool through the application of middle-aged women in the field of health screening.

• Journal of Environmental Policy
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• v.13 no.4
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• pp.135-159
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• 2014

Industrial insect is defined as the insect utilized in industries that creates added value. Most of the industrial insects used in Korea are exotic species that are introduced through artificial means. Despite the rapid expansion of market for industrial insects, the system for risk assessment of industrial insects is not being adequately conducted. Although Korea carries out a risk assessment for the species designated as disease and insect pest by Animal and Plant Quarantine Agency, far too little consideration is being given to overall ecosystem, as the control system is covered in the Plant Quarantine Law. To solve this problem, we analyzed the Korean risk assessment system and looked at systems in other countries. The results show that it is essential for stakeholders to reach an agreement to set up fundamental directions for the system. Unless the integration system of taxonomical and ecological information is prepared, the ecological risk assessment should be conservative to protect ecosystems and should also follow the precautionary principle. It also requires cooperation among the ministries. In addition, the results indicated that a differentiation between risk assessment and screening is urgent. Several solutions such as setting up clear objectives in both assessment and screening stages, target species, steering organization and assessment criteria assessment systems from were proposed as practical institutional strategies. Among many foreign countries the assessment system from Ireland equally considers various factors such as economical, ecological safety and management aspects, It is also based on precautionary principle to fulfil its original purpose. It was suggested that the Ireland system would be the best reference that can be modified and applied into the Korean system by considering distinct characteristics of the industrial insects.