• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.3
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• pp.379-389
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• 2022

The number of public transportation users has dropped drastically due to COVID-19. In this work, my survey was conducted to uncover the factors that influence citizens' travel patterns. Data were collected and logistic regression analysis on the shifts in transportation was undertaken. Additionally, an importance-performance analysis was carried out to investigate how to effectively operate public transportation systems and improve facilities. The main research findings were as follows: First, the more individuals were concerned about COVID-19 (+) and being infected when using public transportation (+), the greater the tendency to switch to private transportation modes. Secondly, when it came to personal traits, respondents who could drive a car (+) or owned a car (+)or did more online shopping (+) or used public transportation for trips (+) tended to switch over, compared with respondents who could not drive or did not own a caror used public transportation to commute. In addition, respondents who were vaccinated (-) or had more household members tended not to switch transportation modes, compared with those who were not vaccinated or had fewer household members. Third, it is important to continue the following efforts to safeguardhygiene linked to public transportation: wearing masks, disinfecting hands, controlling diseases, and general cleaning. The conclusion was that it is important to put traffic congestion and ventilation issues first, especially in regards public transportation, which was not rated as satisfactory enough compared to its importance. The research findings can provide useful basic data when establishing countermeasures to the current COVID-19 circumstances in the areas of public transportation operation and management and in the event of an infectious disease outbreak in the future.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.2
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• pp.157-173
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• 2023

Although this site is designed with a non-vibration excavation method for a section of 265 m, there are concerns about decline of constructability and economic feasibility. For this reason, the low-vibration electronic detonator blasting method was suggested. To evaluate the applicability of the low-vibration electronic detonator blasting method, the damage range of blasting vibration of low-vibration electronic detonator blasting applied just before the site (suggestion I) and low-vibration electronic detonator blasting constructed close range the subway like this site (suggestion II) was analyzed. As a result of comparing the blasting vibration damage ranges of the two suggestions, the damage range of suggestion II was calculated more conservatively. Considering the specificity of the close range of this site, suggestion II was selected for design change for safer construction. As a result, it is predicted that there will be no damage to the structure even if the 72 m section out of the non-vibration excavation 265 m section is changed to the Low-vibration electronic detonator blasting. And it is evaluated that high economic benefits can be obtained because the total expected excavation period can be reduced by 144 days from 662.5 days.

• The Journal of the Acoustical Society of Korea
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• v.42 no.2
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• pp.152-160
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• 2023

Sound barrier walls are the most basic way to cope with noise problems in urban residential environments. The most important acoustic function of sound insulation board is represented by sound transmission loss and sound absorption coefficient. However, Korea has not yet established a standard for measuring the sound absorption rate of sound insulation boards. In addition, even in the European standard, where the overall acoustic standard of soundproofing boards has already been established, the sound absorption rate is applied only to the standard for measuring the sound absorption rate of general building finishing materials, and a separate measurement method considering the characteristics of soundproof walls and soundproofing boards is not presented. The sound absorption coefficient should be evaluated by summing up the energy absorbed into the material as well as the energy transmitted through the material, but the current European standard has a problem in that the transmitted sound energy is not taken into account. In this paper, we reviewed the sound absorption coefficient measurement standards of sound insulation boards currently being presented, and verified the difference between the results and the new measurement method considering transmission sound for sound insulation boards actually used in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4D
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• pp.467-472
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• 2009

Even if Seoul City administration improved its public transportation service, transportation model share in seoul has not been increased. Subway user is also decreasing. Therefore, policy transition into TOD(Transit Oriented Development) should be applied in oder to enhance subway modal share. This paper develops a influencing model by using variables of transportation demand and supply. In addition, it provides major influencing factors for users in subway station area and level of transportation supply based on the analysis results. The results show that: first, cluster analysis presents that traffic pattern is proved to be different according to land use characteristics(residence, non-residence); second, main transportation variables such as transferring distance, the number of bus stop, the number of short distant bus lines, and the number of bicycle are more supplied in residential area compared to non-residential areas; third, the number of lines, bus dispatching interval, operating time, and distance between subway stations are more supplied in non-residential areas than residential areas. All in all, the results will be useful for providing priority of considerations in case of decision-making on public transportation policy in subway station area.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.5D
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• pp.709-716
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• 2006

The rapid changes of family structure such as singles, working couples and so on have effects on a travel behaviour. One of the characteristics from this is the increasing portion of trip-chain, in which plural activities were conducted in a "single outgoing" travel. Therefore travel must be considered as location change to conduct various activities instead of pursuing single travel purpose. This paper specifies a behavioral homogeneous person group by a job, a possession of cars. Based on this classification of person groups and their activity diary, the sequence, time and travel mode of activities in a day can be verified. As a case study household survey was conducted in city Kongju. The survey result shows that the classification of behavioral homogeneous person group based on criteria like employment status and car ownership bring a good result to forecast trip generation in traffic zone.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.95-103
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• 2006

One of the main functions of the 4D system includes visualizing numerical schedule data in construction. The existing 4D tools have an excellent function for simulating building projects that all activities are progressed according to vertical work zone. However, it is not easy to implement all of it in the civil engineering project because the construction activities of highway and railway projects are progressed on the horizontal work zone and the 4D simulation for those projects should include earthwork objects that depend on the natural ground condition. This study suggests a new methodology for improving those limitations of 4D system for the civil engineering project and develops a new system by the suggested methodology. To verify the developed system, this study attempts to simulate 4D object for horizontal elements such as earthwork, paving work and tunneling work. The morphing and multi-texturing techniques developed in the study can be new approaches to simulate 4D object for the earthwork such as cutting and banking whose activities are progressed on the natural ground condition. The research results can be expected as a draft function for improving the application of 4D system in civil engineering projects.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.6 s.58
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• pp.192-203
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• 2009

In the new Seoul-Busan high speed railroad construction specially in area of city center passage the roadbed establishment is recommended the staibility for the existing subway tunnel segments of Busan subway 1st and 2nd lines regarding the appearance condition, a quality condition and the durability of the objective facility, and it evaluates the numerical analysis using MIDAS/GTS which leads the stability of the objective facility and investigatesd tunnels. Fundamental issues in tunneling under high groundwater table are discussed and the effect of groundwater on tunnel excavation was examined using a 3D stress-pore pressure coupled Finite-Element Method. Based on the results the interaction mechanism between the tunnelling and groundwater is identified. In the both of 1st and 2nd Line the maximum sinkage, unequal sinkage and the lining stress from numerical analysis are within permission and the damage degree is appearing to be disregarded. But it enforces necessary Pre-grouting in order to minimize an actual tunnel face conduct and when the tunnel is excavated it is also necessary to minimize the outflow possibility.

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.4
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• pp.15-26
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• 2015

The Daegu Metropolitan Transit Corporation Advisory Committee has chosen 5 styles of bridge-pier designs, including coating, graphic, planting, billboard and safety-facility style, based on the results of landscape simulations from a previous study. This study was conducted to investigate citizen's preferences and emotional images for each style of bridge-pier design, by aiming at the pilot urban landscape improvement section from Daebong Bridge in Suseong Gu to the crossroads near Dongseong Elementary School in Daegu Metropolitan City. The questionnaire was drawn up regarding the urban landscape improvement plans applied to the research area, and the questions were about citizens' perception of bridge-pier structures generated by constructing a light rail transit, important factors to consider when designing bridge piers, preferences for each style of bridge-pier design and emotional impact. 60.4% of the survey participants were found to perceive bridge-pier structures as unattractive, so it was necessary to improve them aesthetically. Regarding visual factors of bridge-pier designs, color was most important at 5.81, followed by form at 5.57. Regarding aesthetic component factors, harmony was most important at 6.07, followed by amenity at 6.00. In the survey participants' preference for each bridge-pier design, the graphic style was preferred most at 4.14, followed by the planting style. In emotional adjectives used for each bridge-pier design, the coating style, the safety-facility style and the non-treatment style showed similar results, and all of these styles were evaluated as artificial, lifeless and desolate. The graphic style and the billboard style showed different tendencies, depending on visual factors and aesthetic component factors applied to the graphic design used for these two bridge-pier styles. Since natural materials were used for the planting style, however, it showed high preference for such emotional images as natural and lively. The emotional adjective 'amiable' was found to affect citizens' preferences for each bridge-pier aesthetic improvement plan most, and it was also analyzed to have an effect on all the styles of bridge-pier designs. To improve the landscape of a light rail transit being constructed inside the urban area, this study quantitatively extracted citizens' preferences and emotional adjective for every style of bridge-pier design applied to the pilot urban landscape improvement section, and it is expected that the results of this study will be used as basic data to improve the landscape of bridge piers.

• Journal of Korean Society of Forest Science
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• v.101 no.3
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• pp.387-394
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• 2012

The study was conducted to develop an effective forest resources use models for an alternate use of abandoned quarry by an attitude survey. According to the result of survey, a pessimistic view due to dust, noise pollution, and forest damage was 5% higher than an affirmative view by economic benefits from the development of quarry. The 42% of the respondents preferred the alternate use of abandoned quarry and the 25% of the respondents wanted an art and cultural space. The optimum size of alternate use was 5-10 ha (43%) with the requirement of nearby residents (32%). According to the SWOT analysis for abandoned quarry, the strength factors were an effective use of land, the content development of modern industrial inheritance + cultural and art fusion, attraction for nearby city and visitors, a harmony of beauty landscape and clean environment, and a sustainable increase of domestic and foreign visitors with the 5-day-work week. The opportunity factors were the improvement of traffic networks through KTX and local highway, the creation of the new growth engines with the establishment of artistic creation belts, the providing of unique cultural and art space through grafting of tour and education, the creation of local income through stone processed goods, and the vitalization of local development through eco-city. The weakness factors were a psychological remoteness and backwardness, and the weakness of staying tour infra. The threat factors were a poor financial support for sustainable development in nearby quarry and a modify of legal and institutional system for the alternated use of abandoned quarry. The developed restoration models for the alternate use in abandoned quarry are classified to a sculpture park, a waterfall and lake park, a rock-climbing, a sports park + forest park, a native botanical garden, a culture and art park, a complex park, a water storage site, a water storage site to extinguish forest fire, a geriatric hospital, an agricultural facility, and a school site types etc. The results suggest that the alternate use in the abandoned soil and stone quarry is needed to establish facility use models with consideration of user's preference.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.15-22
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• 2002

Transportation project appraisal should be precise in order to increase the social welfare and efficiency, and it has been evaluated by only a single criterion analysis such as benefit/cost analysis. However, this method cannot assess some qualitative items, and cannot get a proper solution for the clash of interests among various groups. Therefore, the multi-criteria analysis, which can control these problems, is needed, and then Saaty has developed one of these methods, AHP(Analytic Hierarchy Process) method. In AHP, the project is evaluated through weighted score of the criteria and the alternatives, which is surveyed by a questionnaire of specialists. It is based on some strict suppositions such as reciprocal comparison, homogeneity, expectation, independence relationship between multi-criteria, but supposing that each criterion has independence relation with others is too difficult in two reasons. First, in real situation, there cannot be perfect independence relationship between standards. Second, individuals, even though they are specialists of that area, do not feel the degree of independence relation as same as others. This paper develops a modified AHP method for solving this dependence relationship between multi-criteria. First of all. in this method, the degree of dependence relationship between multi-criteria that the specialist feels is surveyed and included to the weighted score of multi-criteria This study supposes three methods to implement this idea. The first model products the degree of dependence relationship in the first step for calculating the weighted score, and the others adjust the result of weighted score from the basic AHP method to the dependence relationship. One of the second methods distributes the cross weighted score to each standard by constant ratio, and the other splits them using Fuzzy measure such as Bel and Pl. Finally, in order to validate these methods, this paper applies them to evaluate the alternatives which can control public resentments against Korean rail path in a city area.