• Title/Summary/Keyword: Urban Architecture

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Computer vision-based remote displacement monitoring system for in-situ bridge bearings robust to large displacement induced by temperature change

  • Kim, Byunghyun;Lee, Junhwa;Sim, Sung-Han;Cho, Soojin;Park, Byung Ho
    • Smart Structures and Systems
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    • v.30 no.5
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    • pp.521-535
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    • 2022
  • Efficient management of deteriorating civil infrastructure is one of the most important research topics in many developed countries. In particular, the remote displacement measurement of bridges using linear variable differential transformers, global positioning systems, laser Doppler vibrometers, and computer vision technologies has been attempted extensively. This paper proposes a remote displacement measurement system using closed-circuit televisions (CCTVs) and a computer-vision-based method for in-situ bridge bearings having relatively large displacement due to temperature change in long term. The hardware of the system is composed of a reference target for displacement measurement, a CCTV to capture target images, a gateway to transmit images via a mobile network, and a central server to store and process transmitted images. The usage of CCTV capable of night vision capture and wireless data communication enable long-term 24-hour monitoring on wide range of bridge area. The computer vision algorithm to estimate displacement from the images involves image preprocessing for enhancing the circular features of the target, circular Hough transformation for detecting circles on the target in the whole field-of-view (FOV), and homography transformation for converting the movement of the target in the images into an actual expansion displacement. The simple target design and robust circle detection algorithm help to measure displacement using target images where the targets are far apart from each other. The proposed system is installed at the Tancheon Overpass located in Seoul, and field experiments are performed to evaluate the accuracy of circle detection and displacement measurements. The circle detection accuracy is evaluated using 28,542 images captured from 71 CCTVs installed at the testbed, and only 48 images (0.168%) fail to detect the circles on the target because of subpar imaging conditions. The accuracy of displacement measurement is evaluated using images captured for 17 days from three CCTVs; the average and root-mean-square errors are 0.10 and 0.131 mm, respectively, compared with a similar displacement measurement. The long-term operation of the system, as evaluated using 8-month data, shows high accuracy and stability of the proposed system.

Impact of personal characteristics on learning performance in virtual reality-based construction safety training - Using machine learning and SHAP - (가상현실 기반 건설안전교육에서 개인특성이 학습성과에 미치는 영향 - 머신러닝과 SHAP을 활용하여 -)

  • Choi, Dajeong;Koo, Choongwan
    • Korean Journal of Construction Engineering and Management
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    • v.24 no.6
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    • pp.3-11
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    • 2023
  • To address the high accident rate in the construction industry, there is a growing interest in implementing virtual reality (VR)-based construction safety training. However, existing training approaches often failed to consider learners' individual characteristics, resulting in inadequate training for some individuals. This study aimed to investigate the impact of personal characteristics on learning performance in VR-based construction safety training using machine learning and SHAP (SHAPley Additional exPlanations). This study revealed that age exerted the greatest influence on learning performance, while work experience had the least impact. Furthermore, age exhibited a negative relationship with learning performance, indicating that the introduction of VR-based construction safety training can be effective for younger individuals. On the other hand, academic degree, qualifications, and work experience exhibited a positive relationship. To enhance learning performance for individuals with lower academic degree, it is necessary to provide content that is easier to understand. The lower qualifications and work experience have minimal impact on learning performance, so it is important to consider other learners' characteristics so as to provide appropriate educational content. This study confirmed that personal characteristics can significantly affect learning performance in VR-based construction safety training, highlighting the potential for leveraging these findings to provide effective safety training for construction workers.

Managerial Implication of Trails in the Teabaeksan National Park Derived from the Analysis of Visitors Behaviors Using Automatic Visitor Counter Data (탐방객 자동 계수기 데이터를 활용한 태백산국립공원 탐방로 탐방 행태 분석 및 관리 방안 제언)

  • Sung, Chan Yong;Cho, Woo;Kim, Jong-Sub
    • Korean Journal of Environment and Ecology
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    • v.34 no.5
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    • pp.446-453
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    • 2020
  • This study built a model to predict the daily number of visitors to 18 trails in the Taebaeksan National Park using the auto-counter system data to analyze the factors affecting the daily number of visitors to each trail and classified the trails by visitors' behaviors. Results of the multiple regression models with the daily number of visitors of the 18 trails indicated that the events, such as the National Foundation Day celebration of Snow Festival, affected the number of visitors of all of the 18 trails and were the most critical factor that determined the daily number of visitors to the Taebaeksan National Park. The long-holidays of three days or longer and other national holidays also affected the daily number of visitors to the trails. Precipitation had a negative impact on the number of visitors of trails where the intention of most visitors was for sightseeing or camping instead of hiking, whereas had no significant impacts on the number of visitors of trails where many visitors intended for hiking. It indicated that visitors who intended for hiking went ahead hiking even if the weather was poor. The effects of temperature had a positive effect on the number of visitors who intended for hiking but a negative effect on the number of visitor to the trails near Danggol Plaza where the Snow Festival was held in each winter, suggesting that the impact of the Snow Festival was the deterministic factor for trail management. Results of K-mean clustering showed that the 18 trails of the Taekbaeksan National Park could be classified into three types: those affected by the Snow Festival (type 1), those that have sightseeing points and so were visited mostly by non-hikers (type 2), and those visited mostly by hikers (type 3). Since visitor behaviors and illegal actions differ according to the trail type, this study's results can be used to prepare a trail management plan based on the trail characteristics.

Vegetational Structure and the Density of Thinning for the Inducement of the Ecological Succession in Artificial Forest, National Parks - In Case of Chiaksan, Songnisan, Deogyusan, and Naejangsan - (국립공원 인공림 식생구조 및 생태적 천이 유도를 위한 간벌 밀도 연구 - 치악산, 속리산, 덕유산, 내장산을 사례로 -)

  • Kim, Jong-Yup;Lee, Kyong-Jae
    • Korean Journal of Environment and Ecology
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    • v.26 no.4
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    • pp.604-619
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    • 2012
  • According to the concept of woodland aesthetic in Germany and forest design in United Kingdom, artificial forest should be restore ecologically step by step in National Park, Korea. This study was carried out to provide the density criterion of thinning for the inducement of the ecological succession by analysing of vegetational structure in Artificial Forest, National Parks. Eleven plots(size is $20m{\times}20m$) were set up in the artificial forest such as Pinus koraiensis forest, Abies holophylla forest, Chamaecyparis obtusa forest, Populus tomentiglandulosa forest, and Larix kaempferi forest and in the natural forest such as Pinus densiflora community, Pinus densiflora-Quercus serrata community, and Quercus serrata community in Chiaksan, Songnisan, Deogyusan, and Naejangsan National Parks, Korea. We classified the artificial forest into undeveloped type of succession, type of alien young trees developing, and early phase type of succession based on the vegetational structure. According to the index of Shnnon's diversity(unit: $400m^2$), undeveloped type of succession was ranged from 0.9681 to 1.1323, type of alien young trees developing was ranged from 1.0192 to 1.1870, early phase type of succession was ranged from 1.3071 to 1.3892, and natural vegetation was ranged from 1.2202 to 1.3428, therefore early phase type of succession forest and natural vegetation are more higher than simple-layered artificial forest with one needle leaf tree species. The limit for the step-by-step thinning was in the range of 30~60%. In case of undeveloped type of succession, we should thin out from large trees throughout three phases, because alien species dominated high value 88~90% in canopy layer. In case of type of alien young trees developing, we should thin out from alien young trees such as Populus tomentiglandulosa throughout one or two phases, because alien species dominated high value 60~97% and young trees with saplings growing up in understory and shrub layer. In case of early phase type of succession, we should thin out from alien trees that compete with native species throughout one or two phases, because alien species dominated less than value 30%.

The Efficiency and Improvement of the Highway Wild-Life Fences for Decrease of Mammals Road-kill - In Case of Manjong~Hongchun Section on Jungang Highway - (포유류 로드킬 저감을 위한 고속도로 유도울타리 효율성 및 개선방안 연구 - 중앙고속도로 만종~홍천 구간을 사례로 -)

  • Song, Jeong-Seok;Lee, Kyong-Jae;Ki, Kyong-Seok;Jun, Ik-Yo
    • Korean Journal of Environment and Ecology
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    • v.25 no.5
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    • pp.649-657
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    • 2011
  • This study had targeted the Manjong Junction~Hongchun interchange section of Jungang highway in order to analyze the efficiency and improvement of the highway wild-life fences. Being analyzed wild-life fence as an effective facility for the prevention of road-kill, it had founded that the wild animals did not jump over even the two layer guardrail, concrete barrier and noise barrier, fence for rock fall. For the section with high road-kill decrease effect after installing the wild-life fence, the effect was higher at wild-life fence with the height of 1.0m where the door had not been installed and the well connected points of road facility than the area with fence height of 1.5m. The road-kill decrease effect was also high at the well managed areas even if the door has not been installed. Also, road-kill had occurred by concentrating around the end of wild-life fence after installing the fence, Moreover road-kill had also occurred around the cutting section. The door of wild-life fence had higher amount of road-kill occurrence as the installation interval was closer. it was analyzed that the door management has a lot of effect on road-kill decrease. The fence for rock fall, two layer guardrail and concrete barrier having the effect of wild-life fence installed on the road would have to be installed by connecting with wild-life fences through proper facility improvement. Although the door should not be installed if possible, it should be installed as automatic door or gravity door to prevent the door from leaving the door open. An escape route has to be formed for the prompt escape away from the road for the animals entered through the ending section of the fence. The eco-corridor has to be made by restoring the soil layer of dual purpose eco-corridor forming a planting area. Also, the dead body after the accident has to be disposed to the outer section of the road immediately in order to prevent the secondary road-kill by the predator from the road-kill. The fence has to be installed as 500m or longer in both ways, in other words 1,000m or longer, from the targeted spot of minimum accident prevention while connecting up to the bridge or box culvert, etc that are next road facilities if possible to guide wild animals safely to the eco-corridor.

Vegetation Distribution Status and Change for Twenty Four Years(1986~2010) of Seunghwanglim(Forest), Wonju (원주시 성황림(城隍林) 식생분포 현황 및 24년간(1986~2010년) 변화분석)

  • Han, Bong-Ho;Choi, Jin-Woo;Noh, Tai-Hwan;Kim, Ji-Suk
    • Korean Journal of Environment and Ecology
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    • v.26 no.5
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    • pp.741-757
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    • 2012
  • This study had targeted the Seunghwanglim of Wonju in order to understand the forest vegetation's present condition. And then we compared the change in vegetation of Seunghwanglim for 24years. It was intended to provide basic data for conservation and management. Actual vegetation as a result of investigation, a total area of $56,231m^2$ Quercus serrata forest(7.02%), Acer triflorum forest(5.71%), and Deciduous Broad-Leaved Forest and Pinus densiflora forest(6.4%) were distributed variously. Present condition of the plains forest has 34 kinds of canopy species, 65 kinds of understory species, 70 species of shrubs species, 88 species of total species. And the plains forest has 500 individuals of canopy layer, 1,102 individuals of understory layer. Mean importance percentage of the major species showed Ulmus davidiana var. japonica(15.6%), Acer triflorum(15.2%), Pinus densiflora(11.1%), Quercus serrata(9.8%). Acer triflorum diameter at Ulmus davidiana var. japonica were a relatively wide range. Results of change for 24 years, vegetation of Seunghwanglim was changed from Quercus serrata-Acer triflorum to Ulmus davidiana var. japonica-Acer triflorum. Big trees over than DBH 30cm were surveyed total 18 species, 166 individuals. Increased over than the past 63 individuals. Seunghwanglim was destroyed by reckless past. Since 1990, the outer perimeter fence was installed to control human access. After that, understory layer and shrub layer were developed. And big tree was increased. Which is considered to restore damaged ecosystems. In order to conservation and protection of Seunghwanglim, people have to management and monitor about exotic species such as Robinia pseudo-acacia, Populus tomentiglandulosa, Castanea crenata, Pueraria lobata, etc.

Policies for Improving Thermal Environment Using Vulnerability Assessment - A Case Study of Daegu, Korea - (열취약성 평가를 통한 열환경 개선 정책 제시 - 대구광역시를 사례로 -)

  • KIM, Kwon;EUM, Jeong-Hee
    • Journal of the Korean Association of Geographic Information Studies
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    • v.21 no.2
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    • pp.1-23
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    • 2018
  • This study aims to propose a way for evaluating thermal environment vulnerability associated with policy to improve thermal environment. For this purpose, a variety of indices concerning thermal vulnerability assessment and adaptation policies for climate change applied to 17 Korean cities were reviewed and examined. Finally, 15 indices associated with policies for improving thermal environment were selected. The selected indices for thermal vulnerability assessment were applied to Daegu Metropolitan City of South Korea as a case study. As results, 15 vulnerability maps based on the standardized indices were established, and a comprehensive map with four grades of thermal vulnerability were established for Daegu Metropolitan City. As results, the area with the highest rated area in the first-grade(most vulnerable to heat) was Dong-gu, followed by Dalseo-gu and Buk-gu, and the highest area ratio of the first-grade regions was Ansim-1-dong in Dong-gu. Based on the standardized indices, the causes of the thermal environment vulnerability of Ansim-1-dong were accounted for the number of basic livelihood security recipients, the number of cardiovascular disease deaths, heat index, and Earth's surface temperature. To improve the thermal environment vulnerability of Ansim-1-dong, active policy implementation is required in expansion and maintenance of heat wave shelters, establishment of database for the population with diseases susceptible to high temperature environments, expansion of shade areas and so on. This study shows the applicability of the vulnerability assessment method linked with the policies and is expected to contribute to the strategic and effective establishment of thermal environment policies in urban master district plans.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

A Visual Image Analysis of Byungsan-seowon by an Attribute of View (조망지향 속성에 따른 병산서원의 경관이미지 특성)

  • Huh, Joon
    • Journal of the Korean Institute of Landscape Architecture
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    • v.37 no.4
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    • pp.86-93
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    • 2009
  • This study analyzes the systematic visual images and factors in and outside of the main courtyard in Byungsan-seowon. The results are as follows; In terms of space distribution, Ip-kyo-dang is located at an elevation of 85m and the distance to Byung-san is 365m. Byung-san with the mean gradient over $50^{\circ}$ looked so stiff, and the east side of that cliff is higher than west. In terms of the angle of elevation relationship between Man-dae-ru and Byung-san draw 10.5 degree and it suits with human scale. The D/H ratio of 1:3 makes the given place very spacious but the linear stiff shape of Byung-san may cause the feeling of closeness. The results of the visual image analysis of the main yard facing Byung-san is very positive with a score of 1.70 in openness, 1.78 in wideness, 1.96 in beauty, 1.96 in harmony for the spacious arrangement which overall, makes the seowon beautiful with many open spaces. There are 4 main implicated factors analyzed which are uniqueness, aesthetic, openness and nature. Out of the total variables, these factors' descriptive ability is 55.90% and the remaining 44.10% is error and peculiarities variables. The factor which contributed most to Byungsan-seowon's main yard's visual preference was the 'aesthetic' with B-values of 0.661 and 0.455 in the nature category.

Changes of Physical Structure of Hangang(Riv.) in Seoul City Area (서울시 구간 한강의 물리적 구조 변화에 관한 연구)

  • Hong, Sukhwan;Yeum, Junghun;Han, Bongho
    • Journal of Wetlands Research
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    • v.19 no.4
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    • pp.403-408
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    • 2017
  • This study aims to set up the basic data to manage the waterfowl habitat through the analysis of the changes of physical structure according to the time series of Hangang(Riv.) as water birds' habitat. Study area was 41.5km in length from Paldang bridge to Hangju bridge. during total length of 497.52km and horizontal boundary was based on the protected lowland in year 1975. As the analysis result of land use from the center of water to adjacent road to the river, ratio of year 1975 was in order of sedimentary land(22.7%), surface water(20.7%), built-up area(16.9%), field(16.2%), paddy field(15.9%), and afterwards most of the areas were changed through the construction of arterial highway and submerged weir in order to use Hangang(Riv.). In year 1985, the area ratio of protected lowland(57.8%) and surface water(32.8%) dramatically increased. After construction of river bank the recreational areas continually increased and relatively natural areas decreased. In year 2005, the area ratio of protected lowland was enlarged to 57.6% and surface water also to 33.3%. While the length of both riversides and naturalness decreased by 10.9%, 91.5% respectively in year 2005 compared to year 1975, the depth of water increased by 1.46m. Comprehensively, the flow of changes by physical structure in Hangang(Riv.) for 30 years was divided into two periods. The main characteristics in the first period were decrease of riverside area and enlargement of the surface water through the massive construction before middle of year 1980, and afterwards revetments were intensively artificialized with changes of land use for amusement area. In terms of water fowl habitat, Hangang(Riv.) which previously had various types of habitat condition was changed into simplified habitat for few of species, and the active improvement apporach was needed for habitat diversity.