• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.88-93
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• 2021

SAW (Submerged Arc Welding) is often used for ship construction or welding pressure vessels and involves spraying a flux in a powder form to a welding site to a certain thickness and continuously supplying electrode wires therein. This welding method enables high current welding up to 1,500 to 3,000 A. Arc efficiency is higher than 95% and the technique allows clean work as it creates less welding fume, which is composed of fine metal oxide particles, and the arc beam is not exposed. In this study, SM490C-TMC thick plates were heterogeneously welded by SAW. Mechanical properties of welds were measured, and welds were assessed macroscopically and for adhering magnetic particles. The following conclusions were drawn. Bending tests showed no spots exploded on sample surfaces or any other defect, and plastic deformation testing confirmed sufficient weld toughness. These results showed the 1F welding method has no shortcomings in terms of bending performance.

• Journal of Urban Science
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• v.10 no.1
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• pp.29-37
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• 2021

The number of old buildings older than 30 years in Korea continues to increase from 29.9% in 2005 to 38.8% in 2020. Considering the growing urban regeneration projects, urban maintenance projects, the suppression of urban expansion, and the lack of idle land in the city, the dismantling of old buildings is expected to increase further in the future. As major accidents at building dismantling sites continue to occur, related agencies are also strengthening safety management of building dismantling works. While physical safety management such as collapse and fall is strengthened, there is a relative lack of interest in the health of workers at dismantling sites due to environmental hazards. Since relevant laws stipulate that construction waste should be separated and discharged, old buildings need to be considered for environmental hazards such as fine dust, floating bacteria, and floating molds when dismantling. In this study, we intend to find important safety management elements in the management of building dismantling sites, measure environmental factors harmful to dismantling workers, and present basic data for the management of dismantling sites in the future. "Safety management" was the highest priority, followed by "dust," "vibration," "noise," "bacteria," and "smell." The perception of the importance of "physical damage prevention" with workers working on dismantling and managers managing the site came out similar, but the perception of "work efficiency" and "health disorder prevention" through environmental hazard management showed different priorities. In the process of dismantling, floating bacteria and floating mold were collected, cultured, and measured the concentration in the indoor air. The measurement was measured by dividing it into pre-dismantling and during dismantling.

• The Transactions of the Korea Information Processing Society
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• v.13 no.9
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• pp.468-473
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• 2024

Excavation work in urban areas can induce ground deformation, which may damage nearby infrastructure. Such ground deformation can result in displacement of paving blocks near the construction site. Accurate measurement of these displacements can serve as an indicator for assessing the potential risks associated with ground deformation. This paper proposes a robust and efficient method for paving block displacement measurement using a 3D laser line sensor mounted on an Unmanned Ground Vehicle (UGV). The proposed method consists of two stages: 2D projection based object detection and measurement through the CPLF algorithm. Experimental results demonstrate that the CPLF algorithm is more efficient compared to the PLF algorithm, achieving an error of 1.36 mm and a processing time of 10.76 ms, confirming that the proposed method ensures robust online measurements with high accuracy in real-world environments with various types of paving blocks and environmental factors using a 3D laser line sensor on a UGV.

• Korean Journal of Heritage: History & Science
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• v.56 no.3
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• pp.234-252
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• 2023

This study looked at the modification of major gardens while making Deoksugung Palace (德壽宮) a park in the Japanese colonial era. This is because landscaping work was carried out in various places from 1932 to 1933 to open Deoksugung Palace, which used to be an imperial palace, as a public recreation space. In particular, major gardens such as the front yard of Seokjojeon Hall (石造殿), the back yard of Hamnyeongjeon Hall (咸寧殿), and the back yard of Jeukjodang Hall (卽阼堂) were greatly transformed into different shapes from the original. During the first phase of construction in 1932, a water tank was installed in Seokjojeon Hall Garden, creating the first water space. This water tank was originally a structure installed in the front yard of Injeongjeon Hall (仁政殿) of Changdeokgung Palace (昌德宮). Around 1909, a water tank installed in the front yard of Injeongjeon Hall was relocated to Seokjojeon Garden in the process of turning Deoksugung Palace into a park. The water tank moved from the front yard of Injeongjeon Hall was a factor that transformed the central area of Seokjojeon Garden into a water space, and a fountain installed to replace the water tank remains to this day. The backyard of Hamnyeongjeon Hall was also renovated into a new shape during the first phase of construction. Originally, there was a terraced flowerbed called Hwagye (花階) in the backyard of Hamyujae Hall (咸有齋) and Hamnyeongjeon Hall, and it was restored from the construction that took place after the Great Fire of Deoksugung Palace. In the process of turning Deoksugung Palace into a park, a three-stage stonework was built in the front yard of Jeonggwanheon Pavilion (靜觀軒) which renovated the Hwagye in the backyard of Hamyujae Hall and Hamnyeongjeon Halll. The stonework built at that time was used as a peony garden to provide visitors with attractions after the opening of Deoksugung Palace, and it remains today with the name Jeonggwanheon's Hwagye. The backyard of the Jeukjodang Hall area is a case of damage in the second phase of construction in 1933. Like the backyard of Hamnyeongjeon Hall, the backyard of Jeukjodang Hall, where the Hwagye was originally built, was converted into a Japanese-style garden in the process of turning Deoksugung Palace into a park. The site where the Hwagye was demolished was decorated with a Japanese-style garden centered on mounding, small roads, and landscaping stones, as well as topographic control and planting work. Although there have been minor changes since liberation, the backyard of the Jeukjodang Hall area is still based on a Japanese-style garden created by turning Deoksugung Palace into a park.

• Journal of the Korea Concrete Institute
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• v.25 no.3
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• pp.339-345
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• 2013

This study is to derive from the required performances and the optimum mix proportion of the roof concrete placed in the in-ground LNG storage tank with a capacity of 200000 $m^3$, and propose the actual data for site concrete work. The concrete placing work without sliding and segregation in the fresh concrete condition is very important because the slope of domed roof is varied in the large range by its curvature. Also the control of hydration heat and the strength development at test ages are classified with massive section about 1.4 m thick and considered to the pre-stressing work and removal of air support after concrete placing work. Considering above condition, slump range is selected $100{\pm}25$ mm under the slope $20^{\circ}$ and $150{\pm}25$ mm over the slope $20^{\circ}$ s until 60 minutes of elapsed time. Also, the roof concrete is satisfied with compressive strength range including design strength at 91 days (30 MPa), pre-stressing work at 7 days (10 MPa), air support removal work at 21 days (14 MPa). Replacement ratio of limestone powder is determined by confined water ratio test and main design factors include water-cement ratio (W/C), sand-aggregate ratio and dosage of admixture. As test results, the optimum mix proportion of the roof concrete used low heat cement is as followings. 1) Replacement ratio of limestone powder 25% by confined water ratio test 2) Water-cement ratio 57.8% 3) Sand-aggregate ratio 42.0%. Also, test results for the adiabatic temperature rising test is satisfied with its criteria and shown the lower value compared to preceding storage tank (TK-13, 14). These required performances and the optimum mix proportion is to apply the actual construction work.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.6
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• pp.599-614
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• 2014

When tunnelling with TBM (Tunnel Boring Machine), accessibility to tunnel face is very limited because tunnel face is mostly occupied by a bunch of machines. Existing techniques that can predict ground condition ahead of TBM tunnel are extremely limited. In this study, the TBM Resistivity Prediction (TRP) system has been developed for predicting anomalous zone ahead of tunnel face utilizing electrical resistivity. The applicability and prediction accuracy of the developed system has been verified by performing field tests at subway tunnel construction site in which an EPB (Earth Pressure Balanced) shield TBM was used for tunnelling work. The TRP system is able to predicts the location, thickness and electrical properties of anomalous zone by performing inverse analysis using measured resistivity of the ground. To make field tests possible, an apparatus was devised to attach electrode to tunnel face through the chamber. The electrode can be advanced from the chamber to the tunnel face to fully touch the ground in front of the tunnel face. In the 1st field test, none of the anomalous zone was predicted, because the rock around the tunnel face has the same resistivity and permittivity with the rock ahead of tunnel face. In the 2nd field test, 5 m thick anomalous zone was predicted with lower permittivity than that of the rock around the tunnel face. The test results match well with the ground condition predicted, respectively, from geophysical exploration, or directly obtained either from drilling boreholes or from daily observed muck condition.

• The Korean Journal of Ecology
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• v.25 no.1
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• pp.9-17
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• 2002

Human activities greatly affect the environment causing its degradation. Urban development and road networks construction cause main impacts on ecosystems and particularly on vegetation cover: road constructions induce complete degradation of the vegetation cover and often leaves a hare land, sometimes without even a soil cover. Reconstitution of vegetation cover is necessary to limit superficial erosion and land slipping on the road, towards a reintegration of the site in the neighbouring landscape. Many approaches have been studied over the last 30 years aiming at this reconstitution of vegetation cover. At frost, the main purpose of land reclamation was to create a new ecosystem. At this time, the environment created was rather a "garden" with a new soil adapted to the plantation of "decorative" species. Then, in early 90′s many studies on the restoration ecology concept rather focused on adapting the vegetation to the existing conditions on the site, as in a side road embankment for example. Nowadays, we notice a large tendency towards the use of such adapted native species instead of industrially produced seeds. In southern France, our team have led research on the potentials of those local species for their use in revegetation processes with hydro-seeding. We therefore developed an approach combining the use of different types of species: Industrially produced, native and wild cultivated species. This method integrates the benefits of using available low costing seeds that are already used on large scale projects with better adapted species, issued form the cultivation of native species and seed production for their use on smaller scale and more costly but more effective results. The use of wild cultivated species seeds was developed in order to limit the cost and reduce harsh natural seed withdrawal in the natural environment In the case of the use of native species. Besides, the use of such seeds allowed a larger geographical scale of use than with local native seeds. In addition, our team began two years ago a research project in Lebanon aiming at the Introduction and development of the revegetation techniques in Lebanon. In fact, this country bared since 20 years the consequences of urban pressure on its environment especially by the development of quarries and road networks. Therefore, pioneer work is necessary to aim at the adaptation of these techniques to the local environment.

• Journal of Environmental Policy
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• v.9 no.1
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• pp.83-107
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• 2010

Urbanized environments are constructed to estimate peak flow and cost savings in response to possible BMP allocation at a watershed scale. The main goal is to explore the proper allocation of sub-watershed level BMPs for peak flow attenuation at a watershed scale. Since several individual site scale BMPs work as a form of aggregated BMPs at a sub-watershed scale, it is a question as to how to properly allocate the sub-watershed level BMPs at a watershed scale. The Hydrological Simulation Program-FORTRAN (HSPF) is set up for a hypothetically urbanized watershed. A peak flow is determined to be the primary variable of interest and targeted to characterize the spatial distribution of aggregated BMPs. Construction cost of a regional pond forms the basis of the economic valuation. The results indicate that when total size of BMPs is constant in the entire watershed, (1) it is most effective to have aggregated BMPs in some upper sub-watersheds while the BMPs in either the mainstem sub-watershed or a single sub-watershed are the least effective choices for peak flow attenuation at a watershed scale; (2) savings exist between allocation differences and reduced peak flow increases cost savings. The largest saving is found in the strategy of aggregated BMPs in some upper sub-watersheds. These findings, however, call for follow-up site specific case studies revisiting the watershed scale impacts of BMP allocation. Then, it will be argued that location and extent of decentralization are considerable policy variables for an alternative stormwater management policy at a watershed scale.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.59-66
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• 2008

In the construction site, to improve the man-dependent form work, non-stripping form has been studied but the developed non-stripping form was hard to applied with respect to the cost, form size and performance. This study is for evaluating the adaptability of the developed non-stripping form named as high performance permanent form (HPPF). To do this, the analytical approach and parametric study were performed based on the research for fundamental material characteristic of the HPPF. The target concrete structure is a wall structure because of its effectiveness of HPPF. To evaluate the structural efficiency of the HPPF applied wall structure, FEM analysis was performed to decide the maximum placing height at one time then it was applied to design the wall structure. In the result of the analysis, the HPPF applied wall structure showed the lots of advantages that it can reduce the cost resulted from reducing concrete and steel rebar even if it has same structural performance to the conventional concrete wall structure with same dimension. With this analysis result, it can be evaluated that the HPPF applied concrete structure can be a concrete structure with the long term durability in site.

• Korean Journal of Heritage: History & Science
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• v.47 no.1
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• pp.66-81
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• 2014

Burnt down during the Imjin War(壬辰倭亂) of 1592, Gyeongbokgung Palace(景福宮) remained in ruins until 1865, when in the second year of King Gojong's(高宗) reign, reconstruction work began. At the time, a royal protocol(uigwe, 儀軌) for the reconstruction was not produced. Instead, the Gyeongbokgung Palace Construction Diary(Gyeongbokgung yeonggeon ilgi, 景福宮營建日記) records the reconstruction process from June to September of 1865. The contents of this diary reveal that the stone used in the construction was obtained from Ganghwa(江華), the Yeongpung field(映楓亭) just beyond Dongdaemun, and Samcheongdong(三淸洞), among other sites. In addition, selected stone remaining from the original Gyeongbokgung Palace site - such as that from the palace astronomical observatory(ganuidae, 簡儀臺) - as reused, while a number of buildings and stonework from Gyeonghuigung Palace(慶熙宮) were moved to Gyeongbokgung Palace. As a result, a number of $17^{th}$ and $18^{th}$ century stonework are currently located at Gyeongbokgung Palace. The Gyeongbokgung Palace Construction Diary contains a record indicating that the bronze dragon(靑銅龍) excavated from the lotus pond at the palace's Gyeonghoeru Pavilion(慶會樓) was created by special technician byeolganyeok(別看役) Kim Jae-su(金在洙) in 1865 for the symbolic purpose of protecting the palace from fire. The diary also reveals that among Kim Jae-su and the other special technicians(byeolganyeok) tasked with the installation and oversight of the palace stonework was Lee Se-ok(李世玉) - aid to have created the haechi statue at Gwanghwamun Gate. This indicates that there were men of court painter(hwawon, 畵員) background among the construction special technicians(byeolganyeok). Moreover, the diary records the names of the stoneworkers(seokjang, 石匠) who worked under these special technicians to actually carve the stonework. These included Jang Seong-bok(張聖福), who participated in the creation of the Geunjeongjeon Hall(勤政殿); and Kim Jin-myeong(金振明), who took part in the construction of Gwanghwamun Gate(光化門). Based on these results, it is possible to identify a number of special iconographic features of the scale-covered animal form(insuhyeong, 鱗獸形) auspicious animal statues at Gyeongbokgung Palace. These include a protruding mouth and large nose, formalized ears, and a mane along the back. Comparing these iconographic features with those found in the stonework of Joseon tombs makes it clear that these palace statues were created in the latter half of the $19^{th}$ century - the period corresponding to Gojong's palace reconstruction. This study was able to confirm that this iconography was taken up by the Gyeongbokgung Palace construction special technicians(byeolganyeok) and stoneworkers(seokjang) as they worked on tomb stonework earlier in their careers.