• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1581-1589
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• 2013

The aim of this study is to suggest a methodology for calculating the peak-hour ratio of passengers at urban railway stations by reflecting the characteristics of passenger demand patterns and the land use inventory of stations. To achieve this, urban railway stations in Seoul are divided into three groups by using factor analysis and cluster analysis. For each station group, we calculate five and four variables related to the passenger demand patterns and the land use inventory of stations, respectively, as well as the peak-hour ratios of passengers. Among these nine variables, average daily passengers and the location quotient (LQ) index for business services are selected as the classification criteria for station groups based on statistical tests. Using the two variables, a group allocation process is suggested to estimate the peak-hour ratio of passengers for a newly-constructed station. Evaluation results based on thirteen stations show that the proposed methodology produces lower errors than the currently-used guideline does. The results of this study contribute to establishing efficiently construction and operation plans for newly-constructed stations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1073-1082
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• 2015

The behavior of the unsaturated soil slope can be influenced by the various factors such as the hydraulic characteristics, the mechanical characteristics, the coefficient of conductivity, the stratifications, the rainfall conditions i.e. the rainfall intensity, the rainfall pattern, the duration time of the rainfall and the antecedent rainfall etc. It is known that the slope failure is influenced greatly by the antecedent rainfall rather than the rainfall condition at the failure time, so the antecedent rainfall is supposed to be a very important factor in slope stability analysis among these factors. To predict and to prevent the slope failure by the rainfall, the distribution of the matric suction by the antecedent rainfall must be considered first of all and the slope stability analysis should be carried out by considering the successive rainfall characteristics. In this research, 3 samples with different quantity (5%, 10%, 20%) of silts were prepared and the SWCC (Soil-water characteristic curve) tests were carried out and the associated parameters were analyzed. After analyzing the distribution of the matric suction and the change of the mechanical characteristics such as the stress and the strength when applying the antecedent rainfall for one month and the successive intensive rainfall for 12 hours, the slope stability analyses were carried out numerically. And the influence of the antecedent rainfall for one month and the SWCC on the stability of a slope were compared and analyzed.

• Environmental and Resource Economics Review
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• v.22 no.1
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• pp.99-125
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• 2013

Renewable energy industry not only has a promising future but also has more risk than conventional energy industry because of its characteristics. Therefore, in this study, an analysis of domestic renewable energy company risk has been performed. The risk of domestic wind and photovoltaic energy companies has been analyzed by using time varying beta model. The model has been constructed based on risk factors like firm size, firm diversification index, domestic installation, and so on. The principal result of analysis can be summarized as follows. First, risk factors affect domestic renewable energy companies have been discovered. Variables like firm size, growth rate of debt ratio, firm diversification index are statistically significant. I found that large firms are less riskier than small firms. It is also confirmed that companies with high diversification index and high debt ratio have high risk. Second, I got the result that policy factors like domestic renewable energy installation and government R&D expenditure could decrease risk of domestic renewable energy company. Third, relative sensitivity of each risk factor have been discovered. The effect of each variable gets bigger in this order: growth rate of domestic installation, firm size or diversification index, growth rate of debt ratio, growth rate of government R&D expenditure.

• Korean Journal of Construction Engineering and Management
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• v.9 no.5
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• pp.75-85
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• 2008

The construction industry has been leading the growth of the nation's economy not only by providing with various infrastructure projects but also by positively impaction related industries such as crating numerous job opportunities. Relevant statistics show the production amount of construction taking about 17.5% of the GDP (Gross Domestic Product). In spite of its positive impacts on the economy, image of Korea construction industry is generally reflected as negative mainly because of its environmental disruption, low payment, bribe, fraudulent work and inefficiency. It brings students to be reluctant choosing the construction industry as their carrier path and governmental and principal research status. Therefore it has been difficult to recruit highly qualitied human resources to the industry while the morale of the whole industry has gradually become demoralized. To improve this stand, many domestic researchers carried out research projects for improving the image of Korea Construction Industry. This study also sympathizes with necessity of improving the negative image of construction industry to remain as one of the leading industry in the 21st century. Especially, this study focused on finding important factors which have significant influences on the image of the industry. Through out the research, image influence factors was identified by rigorous literature review and interviews as industrial and academic experts. Factors, then, categorized and used as the main framework for the survey which designed to fine the degree of impacts on the image of the construction industry. In analyzing the survey results, various statistical techniques was employed including factor analysis, Chi-Square-Test, Correlation Analysis and Multiple Linear Regression. Identified as the most influent factors to the image of the construction industry include morale of construction employee, and prospects the industry which of the judgement by payment, impacts on nation's economy, future of the industry, etc.

• Genomics & Informatics
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• v.8 no.3
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• pp.108-115
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• 2010

Hypertension is the most prevalent disease worldwide and is itself a risk factor for cerebral, cardiac, and renal diseases. The inconsistency of candidate genes suggested by previous genomewide association studies (GWASs) may be due to not only differences in study design and genetic or environmental background but also the difference in the power of analysis between continuous traits and discrete traits. We analyzed 352,228 single nucleotide polymorphisms (SNPs) in 8842 unrelated Koreans obtained from Ansan and Ansung cohorts. We performed a series of GWA analyses using three different phenotype models; young hypertensive cases (278 subjects) versus elderly normotensive controls (680 subjects); the upper 25% (2211 hypertensive cases) versus the lower 25% of the SBP distribution (2211 hypotensive controls); and finally SBP and DBP as continuous traits (8842 subjects). The numbers of young hypertensive cases and elderly normotensive controls were not large enough to achieve genomewide significance. The model comparing the upper 25% subjects to the lower 25% of subjects showed a power that was approximate to that of QTL analysis. Two neighboring SNPs of the ATP2B1 gene, rs17249754 (SBP, p=$2.53^{-10}$; DBP, p=$1.28{\times}10^{-8}$) and rs7136259 (SBP, p=$1.30{\times}10^{-9}$; DBP, p=$6.41{\times}10^{-8}$), were associated with both SBP and DBP. Interestingly, a SNP of the RPL6 gene, rs11066280, revealed a significant genomewide association with SBP in men only (p=$3.85{\times}10^{-8}$), and four SNPs located near the MAN2A1 gene showed a strong association with DBP only in elderly men aged 60-70 years (e.g., rs6421827, p=$4.86{\times}10^{-8}$). However, we did not observe any gene variant attaining genomewide significance consistently in the three phenotype models except for the ATP2B1 gene variants. In general, the association signal with blood pressure was stronger in women than in men. Genes identified in GWASs are expected to open the way for prevention, early diagnosis, and personalized treatment of hypertension.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.189-199
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• 2006

This paper presents a field study of the stability of slope collapsed during road construction and proposes a reasonable countermeasure if the current slope is unstable. As a result of slope investigation, it was found that the slope includes five tension cracks and the sliding surface is started from the tension crack and propagated the surface soil layer through weathered rock layer. The slope stability analyses are conducted in case of dry and rainfall seasons. The results indicate that the slope is unstable status. A reinforcement method of slope failure should be selected according to the scale of failure. That is, the scale of slope failure, which is classified small, middle and large size determines the reinforcement method of slope. Since the slope interested in this study is large size failure slope, the reinforcement method to control slope failure is selected stabilizing piles, and seed spray and drainage of surface waterare also selected to remain the factor of safety. The SLOPILE (Ver. 3.0) program is applied in order to do stability analysis of slope reinforced by piles. As the result of analysis, the slope reinforced by a row of piles shows the stable state. It is clearly confirmed that the stabilizing of piles can improve the stability of slope.

• Journal of the Korean Institute of Landscape Architecture
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• v.46 no.4
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• pp.11-20
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• 2018

This paper deals with Post Occupancy Evaluation (POE) of 2.28 Memorial Park in Daegu. The park is located in center of the city. The results and discussions could be used as basic data for urban park planning and design, in CBD. A questionnaire was conducted for 15 days from May 11, to May 26, 2016, and a sample group consisting of 230 on site users. The behavior, satisfaction, and preference of space image, were surveyed. The behavior analysis, satisfaction, and image evaluation questionnaire were derived using previous studies, and reliability, factor analysis and multiple regression analysis were conducted using SPSS. As a result, the items were very reliable, causal factors were extracted, and the variables that affect satisfaction and image preference were able to be identified. In the 2.28 Memorial Park, user satisfaction and image evaluation value were very high in most items. As a result of the assessment, the green-water landscape factors and cleanness factors, which have the greatest influence on satisfaction and preference, should be continuously maintained. Due to the characteristics of the city center parks, the users of the parks also felt environmental problems in the urban areas, so the users assessed noise levels, plant species, and air quality at a low level. Therefore, to solve this, plans such as noise abatement and extension of green space should be ongoing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.314-321
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• 2016

After the 1980s, as the economy was growing rapidly and the real estate market was active, a large increase in population was supplied to the city. Accordingly, the national apartment housing market is located in the form of Urban Housing Culture. On the other hand, with time, the supply apartment houses became superannuated and the residential environment became poor. Therefore, the environment of old apartment houses has been changed to improve by reconstruction. Despite this, reconstruction incurred not only a lot of construction waste, but also problems of environmental degradation, noise, traffic congestion, increasing number of households, and so on. Recently, the housing law has changed, and vertical extension remodeling focused on Small/Medium Town House is underway. This has been changed in response to the demand. This is one of essential parts in the remodeling field for the future, even though it has some problems in how uses existing buildings. Therefore, this study analyzed occurrence risk factor for each type through research materials and case analysis regarding the vertical extension remodeling of apartment housing. In addition, the relative importance was determined through questionnaires and interviews from constructors, designers, and experts in the field.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.5
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• pp.657-665
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• 2019

The domestic railway parts and equipment manufacturing industry is mainly focused on SMEs, and the majority of them are suffering from profitability because they cannot build economies of scale. Besides, they have survived in the form of importing technology products from overseas advanced countries and delivering them to domestic railway operators rather than having in-house technology. Therefore it is necessary to study whether the problems of the current railway industry can be identified and improved and at the same time, whether the government's railway industry development policy is properly reflected. literature studies related to technology commercialization, and conduct surveys of AHP questionnaires on the experts of the manufacturing industry of SMEs, academics / research institutes of the railway industry. After that, the Level 3 activation method AHP analysis was additionally performed on the important factors of Level 2 that have the highest importance and priority in Level 1. As a result of the AHP analysis, 'Technical Connectivity' was the most important method in the technical factor, and SME experts and academic and research institute experts were highly evaluated for 'commercialization ability' Competence in terms of importance. As for external support factors, it was analyzed that SME experts "support for manpower development" was important, while the other two group experts research and development support was important. In this study, the priority of the government support and policy priorities are suggested according to the capabilities of the railway manufacturing SMEs before the future R&D support.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.5
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• pp.513-522
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• 2021

A smartphone (SMP) includes a MEMS sensor that can record 3-components motions and has a wireless network device to transmit data in live. These features and relatively low maintenance costs are the advantage of using SMPs as an auxiliary seismic observation network. Currently, 279 SMPs are monitoring seismic motions. In this study, we compare the SMP records with the seismic station (SS) records to validate SMP records. The data used for comparison are records for five earthquakes that occurred in 2019, which are 321 SS data recorded by the Korea Meteorological Administration and the Korea Institute of Geoscience and Mineral Resources and 145 recorded by SMPs. The analysis shows that the event-term corrected average residual of the SMP MEMS sensor records is 0.59 which indicating that the peak horizontal acceleration by SMP is 1.8 factor bigger than the peak ground acceleration by SS. In addition, the residuals tend to decrease as the installation floor of the smartphone MEMS sensor increases, which is the similar trend with response spectra from SS.