• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.317-329
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• 2001

서울지하철 터널의 상당 구간이 막장면이 풍화토에서 풍화암까지 변화하는 복합화강토지반에 건설되어 왔다. 화강암풍화지반은 심도에 따라 강도의 변화가 크며, 수위가 높고 투수성 지반인 특징을 갖는다. 터널은 주로 비원형 배수터널로 설계되고 NATM 공법으로 시공되었다. 이와 같은 여건의 터널현장에서 발생하였던 붕괴사례를 조사한 결과, 대부분의 붕괴가 터널 어깨 부근으로부터 시작되었고, 구조적으로 완전하지 않은 라이닝, 그리고 지하수와의 연관성 등의 공통적 특징이 확인되었다. 이러한 터널문제는 지반조건, 시공조건, 터널형상 등 경계조건이 복잡하여 한계평형 해석과 같은 종래의 해석적 방법으로 터널안정을 검토하기가 용이하지 않다. 그 가장 큰 이유중의 하나는 터널의 파괴메카니즘에 대한 분명한 정보를 알 수 없는데 있다. 파괴메카니즘의 조사에는 전통적으로 원심모형시험법이 많이 사용되어 왔다. 그러나 화강토지반내의 터널처럼 복잡한 경계조건을 갖는 터널문제에는 적용하기 어렵다. 따라서 이에 대한 하나의 대안으로서 본 논문에서는 지반거동의 비선형성을 고려하는 Coupled 수치해석법을 이용하여 파괴메카니즘을 조사하였다. 수치해석결과의 증분변위벡터, 누적소성편차변형률 그리고 속도특성치(velocity characteristics)의 분석을 통해 실제 붕괴사례와 잘 일치하는 명확한 파괴메카니즘을 파악할 수 있었다. 이로부터 복잡한 경계조건을 갖는 터널 문제의 안정해석을 위한 파괴메카니즘을 조사하는 수치해석적 접근방법을 제시하였다.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.792-795
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• 2008

AGT system is a kind of light railway train. AGT system use of concrete track and rubber tire, so it can be reduce the noise and vibration, compare to the normal train system. And, the dynamic responses of normal bridge are influenced by the dynamic characteristics of bridge, the speed of vehicle and the surface roughness of railway. But the AGT system bridge is influenced not only the above facts but also the guiderail unevenness, because, AGT vehicle steered by guiderail. So, in this study, optimized service condition is suggested for the design and operation of AGT system, by the means of experimental study. The experiments are executed for PSC bridge with length of 30m, at the AGT test line in Kyongsan. The test results are compared and investigated according to the prominence. In the test result, the guiderail prominence influenced on the dynamic response of bridge. It shows a increase as compared with no guiderail prominence in the dynamic response value acceleration, displacement, stain.

• The Journal of the Acoustical Society of Korea
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• v.33 no.4
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• pp.248-254
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• 2014

Among acoustic signal analysis tasks, acoustic context awareness is one of the most formidable tasks in terms of complexity since it requires sophisticated understanding of individual acoustic events. In conventional context awareness methods, individual acoustic event detection or recognition is employed to generate a relevant decision on the impending context. However this approach may produce poorly performing decision results in practical situations due to the possibility of events occurring simultaneously or the acoustically similar events that are difficult to distinguish with each other. Particularly, the babble noise acoustic event occurring at a bus or subway environment may create confusion to context awareness task since babbling is similar in any environment. Therefore in this paper, a frequency-cepstral feature vector is proposed to mitigate the confusion problem during the situation awareness task of binary decisions: bus or metro. By employing the Support Vector Machine (SVM) as the classifier, the proposed feature vector scheme is shown to produce better performance than the conventional scheme.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.216-224
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• 2008

In general, based on criteria of subway law, radius 500m from subway station is defined as SIA(Subway Station Influence Area). Therefore, in this paper, selection models of SIA are developed to identify appropriate SIA for recently developed 4 new towns based based on CART analysis. As a result, following outputs are obtained; (1) walking distance from subway station is the most influential factor to define SIA (2) SIAs vary with new towns (i.e., bundang city: 856m, ilsan sanbon city 508m, pyungchon city 495m), and (3) walking distance from subway station is influential to land price of SIA. In addition, bundang and pyungchon new town are more affected in land price and walking distance. Therefore, it is desirable for current definition of SIA (radius 500m from subway station) to reflect characteristics of land use and walking distance in the new towns.

• Journal of the Economic Geographical Society of Korea
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• v.21 no.4
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• pp.335-349
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• 2018

This study analyzes the effect of the changes in traffic environments such as transportation speeds on the time-distance accessibility for the public transportation passengers. To do this, we use passenger transaction databases of the Seoul metropolitan public transportation system: one week for each of the three years (2011, 2013, and 2015). These big data contain the information about time and space on the traffic trajectories of every passenger. In this study, the time-distances of links between subway stations and bus stops of the public transportation system at each time are calculated based on the actual travel time extracted from the traffic-card transaction database. The changes in the time-distance accessibility of the integrated transportation network from the experimental results can be summarized in two aspects. First, the accessibility tends to decline as the year goes by. This is because the transportation network becomes more complicated and then the average moving speed of the vehicles is lowered. Second, the accessibility tends to increase on the weekend in the analysis of accessibility changes by day. This tendency is because the bus speeds on bus routes on the weekend are faster than other days. In order to analyze the accessibility changes, we illustrate graphs of the vehicle speeds and the numbers of passengers by year and day.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.4
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• pp.86-99
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• 2016

This study was for analyzing the external environment and internal space structure and improving the way of use efficiency in waterfront through the Dragon boat festival to utilize waterfront actively. Through from the four target area, Hongkong, Busan, Incheon and Daejeon, this study was for an importance and satisfaction analysis for users about the element effect on the waterfront use efficiency and the contribution to cultural contents revitalization of waterfront by giving basic data. The result is as follows. First, in the importance analysis about 12 items, modern cultural infra around the waterfront was ranked highest, 8.26 and waterfront landscape, square & openspaces, convenience facilities, transport, green area, quality of viewing space, historic resources, pedestrian, suitability of width, wave, depth, water quality, berth & mooring were ranked in descending order. Second, waterfront landscape was interpreted by rather the external environmental impact according to city size than the matter of spatial structure in target area and judged as an important factor effect on site selection for waterfront. In the analysis of waterfront landscape, the reason of the high satisfaction about domestic target area was that riverside parks were recently made considering their waterfront activities. Viewing space was major infra where people could experience the pleasant waterfront and watch dynamic water leisure sports like Dragon boat three dimensionally and was thought to be improved for the use efficiency. Third, tourism resources were very important element that affect the use efficiency of waterfront, so waterfront users react sensitively to modern tourism resources rather than to historic resources. This meant that tourism infrastructure for shopping and leisure of the young affected the use efficiency of waterfront, so Hongkong and Busan were in a better position in terms of using waterfront that was near the tourism infrastructure. Fourth, in the analysis of traffic accessibility, both Hongkong and Busan were high evaluated in terms of excellent traffic accessibility by subway. Daejeon was low rated in terms of the satisfaction of use efficiency, because of the relative lower place awareness compared with transportation infrastructure. In Hongkong, waterfront was connected with downtown and in Busan, housing complex and shopping centers were located in the place for users in an easily accessible on foot, so the satisfaction was high-pitched. Finally, in the importance of water surface width and the analysis of satisfaction, except Incheon, all the three were over 200m in width of water surface and this meant the surface width above certain level was interpreted to interrupt the concentration of enjoying the water leisure sports. In the analysis of surface condition such as water quality, water depth and wave, through a survey, Busan had a problem with water quality and Gapcheon in Daejeon had a problem with optimal water depth by the festival participants.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.727-729
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• 2017

According to the National Statistical Office and the Ministry of Health and Welfare Family Department, Korea has already estimated that the proportion of the elderly population aged 65 or over is estimated to be higher than the global average, and has already entered the "Aging Society". Moreover, it is estimated that the quality of life of the people improved by reaching the information society earlier than expected. However, unlike young people, elderly people show clear differences in access and use of information that is difficult to access new machines easily and cause intergenerational digital divide phenomenon. In order to solve such a phenomenon, we implemented a speech recognition based smart mirror system for elderly people. The installed system can provide lighting control, weather forecast and subway time information search service of the using voice recognition. Through the implemented system, it is expected that the elderly will have accessibility to new machines, information that gives a feeling of participating in the change of the new era will be obtained and the effect of living convenience will be expected.

• The KIPS Transactions:PartA
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• v.17A no.1
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• pp.19-26
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• 2010

As standard of living is higher and aging society is coming, it is needed to develop transportation that is easy to use for weak person. To comply with the demands, it is started to make Bi-modal Tram that is on KRRI(Korea Railroad Research Institute)'s hands. This tram has to have good accessibility like bus, be low level from ground like subway, and park accurately so wheel chair's or passenger's foot can't fall into the gap. But Bi-modal Tram have long length, so it need development of All Wheel Steering System. The Bi-modal Tram that have all wheel steering system steer not only the first axle but also the second and third axle from the first axle or articulation angle, and velocity, and so on. At this study, we discuss AWS ECU's development process.

• Journal of Korean Society of Transportation
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• v.27 no.6
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• pp.89-96
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• 2009

The present study is performed to identify the relationship between apartment prices and distances from freeway interchanges. To collect consistent data and to simplify the sphere of the influence, the Seoul beltway was selected as the target road. Two sides of the Seoul beltway such as the inner side and the outer side are partitioned following the whole beltway line. The maximum distance to be taken care of in data collection was 6.0km from freeway interchanges. Results show that there exist consistent patterns between apartment prices and distances from freeway interchanges. In detail, if the apartment is located on the sphere of the influence, it is shown that a) the prices are increased overall b) the prices are low at very near of interchanges c) the prices are increasing up to the points of about 2.0~4.0km from interchanges d) the prices are decreasing after the points. Additionally, it is shown the pattern observed was following approximately a quadratic curve which is different from the liner curve obtained from the similar study over the sphere of the influence in railway(Subway).

• Journal of the Korean Regional Science Association
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• v.38 no.3
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• pp.51-63
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• 2022

COVID-19 has had a detrimental effect on urban vibrancy, particularly in urban commercial districts. Against this backdrop, the goal of this study is to examine the changes in social and economic vitality in Seoul's commercial area before and after the COVID-19 outbreak, and to identify influential factors for the changes in vitality using multinomial logistic analysis. The following are the key findings derived from the study. First, an examination of the changes in the vitality of commercial districts by type revealed that the decline in economic vitality was greater than the decline in social vitality. Second, the greater the residential ratio, the less harmful the impact of COVID-19 on urban vibrancy. Third, unlike other types of commercial districts, traditional markets had a minor increase in credit card sales even though the floating population fell during the COVID-19 pandemic. Fourth, the accessibility of the subway did not play a positive role in reversing the decline in social and economic vitality caused by the pandemic in the commercial district of Seoul; rather, the accessibility of private automobiles contributed to the increase in social and economic vitality. These results imply that the development and activation of commercial areas accessible by non-motorized modes in the residential neighborhood are becoming crucial in the post pandemic era.