• Journal of the Korean Wood Science and Technology
• /
• v.38 no.6
• /
• pp.532-540
• /
• 2010

The strength properties of wooden model retaining wall made of pitch pine (Pinus rigida Miller) was evaluated. Three different types of wooden model retaining wall were made of the 11cm square timber treated with CUAZ-2 (Copper Azole). The retaining wall was made into the 4 layers of crossbar and the 3 layers of vertical-bar, of which the size was 86 cm high, 200 cm long and 96 cm wide. Type I was control and in Type II 20 cm vertical-bars and 93 cm vertical-bars were arranged alternately to decrease wood usage. TypeIII was similar to TypeII except that the connection between crossbars was reinforced with the wooden armature. In each type, the strength properties of retaining wall were investigated by horizontal loading test and the deformation of structure by image processing (AICON 3D DPA-PRO system). In horizontal loading test of Type I, Type II and Type III was 63.17, 57.80, and 60.97 kN/m, respectively. The deformation of the top layer in Type II was 1.5 times larger than in Type I and Type III. Consequently, the economic efficiency and strength performance were better in Type III than in Type I and Type II.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.38 no.1
• /
• pp.51-61
• /
• 2018

Foundation of tower structures such as wind turbine, pylon, and chimney have to resist considerably large overturning moment due to long distance from foundations to load point and large horizontal load. Pile foundations subjected to uplift force are needed to economically support such structure even in the case of rock layer. Therefore, this research performed the laboratory model tests with the variables, W/C ratio and sand proportion, to evaluate the effect of the mix proportion of grouting material on shaft resistance. In the case of cement paste, maximum and residual shaft resistance were distributed in uniform range irrespective of the changes of W/C ratio. However in the case of mortar, they were decreased with increasing W/C ratio, while they were increased and then decreased with increasing sand proportion. In the case of no sand, the maximum shaft resistance was about 540~560kPa regardless of the W/C ratio. When the sand proportion was 40%, it was about 770~870kPa depending on W/C ratio, which was about 40~50% higher than that without sand. The optimum proportion found in this research was around 40% of sand proportion and 80~100% of W/C ratio.

• Korean Journal of Environment and Ecology
• /
• v.27 no.4
• /
• pp.462-472
• /
• 2013

This study was carried out to provide a basic data for preservation of Pinus desiflora forest as cultural landscape forest by analyzing characteristics of plant community of P. desiflora forest in Geumjeongsan(mountatin) in Busan city. In order to analyze plant community of P. densiflora in Geumjeongsan, we set up 10 study plots inside and 8 plots outside of Geumjeongsansung(mountain fortress, hereinafter 'Sansung')(unit area: $400m^2$), a total of 18 plots. TWINSPAN analysis divided these 18 study plots into 6 communities which are Querqus serrata-P. desiflora community, P. desiflora community, P. desiflora-Q. serrata community, P. thunbergii-P. densiflora community, P. densiflora-P. thubergii-Q. acutissima community, and P. densiflora-Platycarya strobilacea community. Importance Percentage (I.P.) of each area and DBH class distribution of main species showed that P. densiflora community would succeed to Q. serrata community or C. tschonoskii community. Analysis on tree age found out that communities in the Sansung were 32~37 years old and those outside the Sansung were 44~57 years old. Shannon's species diversity index ranged from 0.4826 to 1.2499. Regarding correlation between species, P. densiflora had negative correlation with Styrax japonica. Based on abovementioned result we expected ecological succession from P. densiflora community to Q. serrata community inside of the Sansung. Outside the Sansung, succession from P. densiflora-P. thunbergii community to C. tschonoskii-Q. serrata community was expected. In order to manage P. densiflora forest as cultural landscape forest, Q. spp in the understory and shrub layer and deciduous broad-leaved arboreal trees should be managed. Tree crown management of deciduous broad-leaved trees in competition with P. desiflora, is also required.

• Korean Journal of Heritage: History & Science
• /
• v.51 no.4
• /
• pp.192-207
• /
• 2018

The Hyangwonjeong and Chwihyanggyo located in the back garden of Gyeongbokgung Palace have mainly been investigated by referring to historical records about the reign of King Gojong and various drawings thought to have been made in the late Joseon period. Because the current Chwihyanggyo was rebuilt temporarily after being burned to the ground during the Korean War, its form and the location of its reconstruction are not grounded on any accurate historical investigation. Although there are some photos of the Chwihyanggyo that were taken between the end of the Joseon period and the Japanese colonial era, there is no information about the photographer or when they were taken, and it is hard to see which photos show the original Chwihyanggyo Bridge with them. The Cultural Heritage Administration, which is currently promoting the restoration of the Chwihyanggyo, has recognized this problem and initiated research on the matter. In 2017, an excavation survey successfully identified the original location of the Chwihyanggyo, as well as that of Hyangwonji Gado (假島), and the shape of the first foundation stone in the pier. With these findings it was possible to infer the ways in which the Chwihyanggyo has changed over the years. Moreover, by measuring the AMS (Accelerator Mass Spectrometer) of the samples collected in the mounding layer of the Gado where the Hyangwonjeong is located, it was discovered that the Hyangwonjeong was constructed sometime after the Imjin waeran (Japanese Invasion of Korea in 1592), which means that the theory that 'the late Joseon Hyangwonjeong was not the former early Josenn Chwirojeong' is groundless. Judging by the materials found to date, we can reasonably assume that the Chwihyanggyo and Hyangwonjeong must have been built around the same time that Geoncheonggung Palace was founded in the late Joseon period.

• Journal of Digital Convergence
• /
• v.17 no.1
• /
• pp.209-217
• /
• 2019

In this paper, the purpose of this paper is to lay the foundation for the search system by using and building an online search engine suitable for the search domain and enabling search, conversion, integration and sharing of information. It is to use the ontology to infer hierarchical relationships, deduce objects based on that layer, and extract attributes to search areas that are relevant to the data that the user wants. In order to search for information in this way, the information search system was implemented by entering key words related to 'qualifications'. The implemented system arranged the meaning and relationship of each attribute online so that the general public can search information quickly, easily, and accurately. In addition, the implementation results were compared with two different search engines. Comparable search engines are Naver and Daum, the two major search engines. The search engine of this study, which was built using an ontology suitable for the search domain to perform searches using the semantic web, was evaluated to have excellent results. However, it is thought that a more formalized online location is necessary to increase the accuracy and reliability of search engines and to include more comprehensive categories of search terms.

• 한국노년학
• /
• v.40 no.1
• /
• pp.33-49
• /
• 2020

This study was conducted to examine the latent classes in social exclusion and to analyse empirically the effects on the economic instability of old age by this type. And it also sought to look at whether the influence of old age anxiety varies with the subjective class consciousness of the elderly. Using the 14th data from the Korea General Social Survey (KGSS) in 2016, 1,041 adult males and females aged 18 years old were analyzed at the time of the survey. T-test, potential layer analysis (LCA), and multinomantic analysis of potential groups were conducted using the STATA14 and MPLUS 7 statistical programs. Finally, multi-regression analysis was performed to identify the moderate effect and effects among variables. According to the research, the types of social exclusion were three groups, followed by social exclusion group (49.3%), Multi-dimensional exclusion group (30.9%), and active social participation group (19.7%). The social exclusion group has the lowest possibility of economic, employment, and health exclusion, but the exclusion of formal and informal social activities seem to prominent, and the multi-dimensional exclusion group is more than 50% likely to experience exclusion in all areas. Active social participation are characterized by very active participation in informal social activities. By conducting multinominal logistic regression, it was observed that the social exclusion group included more young people than other groups, and that the multi-dimensional exclusion group included many elderly women without spouses. Finally, multiple regression analysis showed that social exclusion type interacts with subjective class consciousness and affects economic anxiety of old age.

• Journal of the Korean GEO-environmental Society
• /
• v.23 no.6
• /
• pp.5-17
• /
• 2022

The performance of the relief wells installed for the purpose of controlling seepage of the dam embankment is affected by various parameters such as diameter, spacing, penetration rate, permeability coefficient of the ground, thickness of the foundation layer. Therefore, when the relief wells are adopted for the purpose of reducing seepage pressure, these parameters should be sufficiently reviewed to determine the installation specifications of the relief wells. This study evaluated the effect of the length of the geosynthetics blanket on the performance of the relief wells installed in the downstream part of the dam embankment with blankets in the upstream and downstream part of the dam embankment as countermeasure methods to control seepage of the dam embankment. In the relationship between the length of the upstream and downstream blanket and the discharge, the discharge of the relief wells decreases as the length of the upstream blanket increases, and on the other hand, the discharge of the relief wells decreases as the length of the downstream blanket increases. In the upper and lower blanket length-spacing relationship, as the length of the upstream blanket increases, the spacing of the relief wells increases and as the length of the downstream blanket increases, the spacing of the relief wells decreases. Therefore, when installing the relief wells in parallel with the blanket, it was found that increasing the length of the upstream blanket is more efficient than increasing the length of the downstream blanket in order to minimize the discharge of seepage discharge and to ensure economic feasibility by wider installation of the relief wells.

• Journal of the Korean Society of Radiology
• /
• v.16 no.1
• /
• pp.1-6
• /
• 2022

Deep learning is a collection of algorithms that enable learning by summarizing the key contents of large amounts of data; it is being developed to diagnose lesions in the medical imaging field. To evaluate the accuracy of the cerebral hemorrhage diagnosis, we used a convolutional neural network (CNN) to derive the diagnostic accuracy of cerebral parenchyma computed tomography (CT) images and the cerebral parenchyma CT images of areas where cerebral hemorrhages are suspected of having occurred. We compared the accuracy of CNN with different numbers of hidden layers and discovered that CNN with more hidden layers resulted in higher accuracy. The analysis results of the derived CT images used in this study to determine the presence of cerebral hemorrhages are expected to be used as foundation data in studies related to the application of artificial intelligence in the medical imaging industry.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.27 no.1
• /
• pp.25-35
• /
• 2023

Considering the non-linear behavior of structure and soil when evaluating a nuclear power plant's seismic safety under a beyond-design basis earthquake is essential. In order to obtain the nonlinear response of a nuclear power plant structure, a time-domain SSI analysis method that considers the nonlinearity of soil and structure and the nonlinear Soil-Structure Interaction (SSI) effect is necessary. The Boundary Reaction Method (BRM) is a time-domain SSI analysis method. The BRM can be applied effectively with a Perfectly Matched Layer (PML), which is an effective energy absorbing boundary condition. The BRM has a characteristic that the magnitude of the response in far-field soil increases as the boundary interface of the effective seismic load moves outward. In addition, the PML has poor absorption performance of low-frequency waves. For this reason, the accuracy of the low-frequency response may be degraded when analyzing the combination of the BRM and the PML. In this study, the accuracy of the analysis response was improved by adjusting the PML input parameters to improve this problem. The accuracy of the response was evaluated by using the analysis response using KIESSI-3D, a frequency domain SSI analysis program, as a reference solution. As a result of the analysis applying the optimal PML parameter, the average error rate of the acceleration response spectrum for 9 degrees of freedom of the structure was 3.40%, which was highly similar to the reference result. In addition, time-domain nonlinear SSI analysis was performed with the soil's nonlinearity to show this study's applicability. As a result of nonlinear SSI analysis, plastic deformation was concentrated in the soil around the foundation. The analysis results found that the analysis method combining BRM and PML can be effectively applied to the seismic response analysis of nuclear power plant structures.

• Journal of the Korean Institute of Traditional Landscape Architecture
• /
• v.41 no.1
• /
• pp.21-34
• /
• 2023

This study identified the materials and construction methods of 'Old Wall' in 13 villages which were designated as National Registered Cultural Heritage at the time of designation and examined the their structural changes based on field survey. The results are as follows: First, the 'Old Wall' consisted of 10 Soil-Stone Wall and 5 Stone Wall. At the time of designation, Stone Wall, which was built irregularly by dry-construction of natural stones, is similar in shape, but Soil-Stone Wall showed difference by the construction method of making used stones, joints, and faces. Second, the study extracted the changes of 'Old Wall' by repair and examined the changes of construction methods as well as the substitution and addition of materials of structure. The wall-roof was built with cement roof-tile and asbestos slate which have the advantage improve durability and cost-effectiveness. In addition, tile-mouth soil was added to korean traditional roof-tile to prevent rainwater from flowing in. Besides, to improve constructional convenience, the natural stone of the wall-body was replaced with blast stone, float stone and cut stone. Cement block, cement brick and cement mortar were frequently used to repair as well. As Soil-Stone Wall was transformed from irregular pattern-construction to comb pattern-construction and wet-construction was changed to dry-construction, it caused landscape and structural problems. Also, the layer of cement mortar applied to wall-foundation blocked the flow of rainwater that was induced by dry-construction of natural stones. Third, the study regarded that the problem with the repair of 'Old Wall' may occur as it is located in living space, because the owner of the wall could repair for the minor damages without technical knowledge. In addition, it is difficult for repair companies in charge of maintenance of Cultural Heritage to supply local materials, and it is differential construction specifications are not applied.