• Journal of the Korean Geotechnical Society
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• v.25 no.9
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• pp.45-55
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• 2009

The quality of railroad trackbed fills has been controlled by field measurements of density and bearing resistance of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. To overcome the defect, the compressional wave velocity was adopted as a control measure, in parallel with the advent of the new design procedure, and its measurement technique was proposed in the preliminary investigation. The key concept of the quality control procedure is that the target value for field compaction control is the compressional wave velocity determined at optimum moisture content using modified compaction test, and direct-arrival method is used for the field measurements during construction, which is simple and reliable enough for practice engineers to access. This direct-arrival method is well-suited for such a shallow and homogeneous fill lift in terms of applicability and cost effectiveness. The sensitivity of direct-arrival test results according to the compaction quality was demonstrated at a test site, and it was concluded that compressional wave velocity can be effectively used as quality control measure. The experimental background far the companion study (Park et al., 2009) was established through field and laboratory measurements of the compressional wave velocity.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.1
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• pp.71-83
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• 2009

Shotcrete is an important primary support for tunnelling in rock. The quality control of shotcrete is a core issue in the safe construction and maintenance of tunnels. Although shotcrete may be applied well initially onto excavated rock surfaces, it is affected by blasting, rock deformation and shrinkage and can debond from the excavated surface, causing problems such as corrosion, buckling, fracturing and the creation of internal voids. This study suggests an effective non-destructive evaluation method of the tunnel shotcrete bonding state applied onto hard rocks using the impact-echo (IE) method and ground penetration radar (GPR). To verify previous numerical simulation results, experimental study carried out. Generally, the bonding state of shotcrete can be classified into void, debonded, and fully bonded. In the laboratory, three different bonding conditions were modeled. The signals obtained from the experimental IE tests were analyzed at the time domain, frequency domain, and time-frequency domain (i.e., the Short- Time Fourier transform). For all cases in the analyses, the experimental test results were in good agreement with the previous numerical simulation results, verifying this approach. Both the numerical and experimental results suggest that the bonding state of shotcrete can be evaluated through changes in the resonance frequency and geometric damping ratio in a frequency domain analysis, and through changes in the contour shape and correlation coefficient in a time-frequency analysis: as the bonding state worsens in hard rock condition, the autospectral density increases, the geometric damping ratio decreases, and the contour shape in the time-frequency domain has a long tail parallel to the time axis. The correlation coefficient can be effectively applied for a quantitative evaluation of bonding state of tunnel shotcrete. Finally, the bonding state of shotcrete can be successfully evaluated based on the process suggested in this study.

• Korean Journal of Heritage: History & Science
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• v.49 no.3
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• pp.78-103
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• 2016

This research is a study on the side framework structure of the hipped and gable roof of Muryangsujeon at Buseoksa Temple. There is a record that Muryangsujeon was deconstructed and repaired in the period of Japanese Occupancy, and its authenticity has continuously been called into question because the structure of the hipped and gable side roofs, and the bonding of the rafters and eaves were not in good order and very different from those of Joseon Dynasty. Scholars date it differently. It is either dated at 13th century or 12th century. This study compares the non-planar configuration of the middle and front proportions of Muryangsujeon's hipped-and-gable-roof framework with those of the Tang(唐) and Song(宋) Dynasties in China. It concludes that the hipped-and-gable-roof framework of those architecture were built with the same technique. The style of architecture that side rafters directly touch the internal security (梁), like in Muryangsujeon, is not usual even among the hipped and garble roofs of the Tang(唐) and Song(宋) Dynasties. The technique of constructing the hipped roofs developed much further after the Tang Dynasty because they began to use garble eaves to build the side structure. The technique seems to have developed greatly by the period of Ming and Qing Dynasties. It also seems that the parallel-flat (平行輻射椽) rafter, which is the form of rafters used between the parallelrafter period and the half-flat-rafter period is very similar to the construction style of the current rafters of Muryangsujeon. However, the Muryangsujeon's eaves do not touch the corner rafter from the middle part. This seems to be a unique style, which is not common in China. In conclusion, the style of the side roof framework of Muryangsujeon at Buseoksa Temple is not of the China's southern regions, but of the northern regions of Tang(唐), Song(宋) and Liao(遼) Dynasties. And when considering the construction year and proportions of the middle front and side front on the same flat, this must be an ancient technique of the northeastern regions of Asia. Since it is likely that the structure of the side roof framework of Muryangsujeon at Buseoksa Temple has not been altered but is a unique style of hipped and gable roofs, this roof can serve as a good guide to restoring the hipped and garble roofs of the pre-Goyreo Dynasty period.

• Journal of dental hygiene science
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• v.11 no.3
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• pp.285-292
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• 2011

The purpose of this study was to analyze and investigate temporomandibular disorders(TMD) and dental clinic outpatients by food intake ability to improve the quality of life. A survey of questionnaires with 208 subjects visiting a dental clinics located in Daejeon city from January to September in 2010 was performed. Analysis were performed with survey results, in which a symptoms of TMD, parafunctional habits and abnormal functions, food intake ability : 1. The main symptoms of TMD showed pain on TMJ(45.7%), pain on joint sound(45.2%), pain during chewing(41.3%), pain during mouth opening(38.0%), pain during non chewing(19.7%) and pain on joint dislocation(13.0%) in turn. 2. The symptoms of TMD by gender showed joint dislocation of 18.0% for male and 8.3% for female(p=0.038); pain on chewing of 49.0% for male and 34.3% for female(p=0.031), which were statistically significant. 3. The parafunctional habits and abnormal functions by gender showed clenching habit of 35.0% for male and 22.0% for female; bruxism of 21.0% for male and 9.3% for female, which were statistically significant. 4. The symptoms of TMD by age showed 52.8% of 27.8% for often and 25.0% for sometimes of 21-30 age in pain on TMJ, which were statistically significant(p=0.001). 5. The parafunctional habits and abnormal functions by age showed over 31 age of 48.3%, which were statistically significant(p=0.003). 6. The food intake ability by symptoms of TMD showed no joint sound(p=0.000), no pain on chewing(p=0.000) and without pain on TMJ(p=0.000), which were statistically significant. 7. The food intake ability by parafunctional habits and abnormal functions showed no clenching habit(p=0.000), no bruxism(p=0.000) and no headache, which were statistically significant. 8. The distribution type of operation by symptoms of TMD showed 30.8% of rest, 24.0% of physical medicine and 16.4% of pharmacotherapy. The pain on chewing showed 36.0% of pharmacotherapy; 52.4% of pain on TMJ for often and 40.5% for sometimes, in which pharmacotherapy and physical medicine were statistically significant(p=0.000). These results showed that management run parallel with survey for multiple factors in TMD we consider aspect of physical, social, physiology to enhance quality of life to increase food intake, construction of program for treatment and prevention because the individual differences need to be multifaceted, further research is suggested to continue.

• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.551-560
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• 2013

Environmental factors and epilithic diatom communities in the lower streams near the harbor region of South Korean peninsula were examined during no monsoon period in May 2013. The sampling of water and epilithic diatoms was conducted at both streams, 19 regulated streams (RS) that there are one or several dams constructed in the river system, and 19 un-regulated streams (US) that there are no dams within the river. A cluster analysis based on the number of species and abundance of epilithic diatoms through the stations, divided into three groups such as groups I (mainly US), II (mixed with US and RS) and III (mainly RS), respectively. Group I showed that water quality is good and high diversity of diatom, while Group II and III was water quality is relatively poor, but not differed in biomass of diatom from Group I. In addition, Group II that had high conductivity, nitrogen and phosphorus, was the lowest in diatom diversity among them. Dominant species were Nitzschia palea (17%) and Navicula seminuloides (11%) in Group I, Nitzschia inconspicua (19%) and Navicula perminuta (9%) in Group II, and Nitzschia inconspicua (15%) and Nitzschia palea (14%) in Group III, respectively. These taxa were widely distributed in brackish water, and not closely related with specific water quality, like eutrophic water. However, the groups II and III belonged to RS, had not only little biomass, but bad water quality such as high concentrations of nutrient and chlorophyll-a. Therefore, to determine the effect of dam construction on the lower water ecosystem, the planktonic algae, which can occur algal bloom in the estuary, also was considered to be a parallel investigation.

• Economic and Environmental Geology
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• v.48 no.5
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• pp.409-420
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• 2015

The Sangdae-ri riverside around Musimcheon stream, flowing through Gadeok-myon of Cheongju City, is one of the representative strawberry fields employing water curtain cultivation (WCC) in Korea. In this area, annual groundwater use for WCC has been calculated by a few methods. On the assumption that all the water flowing through the final ditch may be mostly composed of groundwater, the discharge rate in it can be used as a good proxy for assessing the groundwater use. However, in the study area, the final ditch was set up in an unpaved state near and parallel to Musimcheon stream. Under such circumstances, the drainwater is likely to be influenced by infiltration and/or inflow of nearby stream. Hence, we examined whether or not stream water has influenced water flowing out through the final ditch in respect of ion concentrations or field parameters such as T, pH and electrical conductivity (EC) values. The period of measuring field parameters and sample collection was from February 2012 through February 2015. The drainwater in the final ditch did not show the average quality of groundwater, but similar quality of stream water in respect of pH, EC, ion contents and water type. From this, it is suggested that measuring the flow rate of the final ditch should not be directly used for assessing groundwater use in the study area. In addition, because of its sensitivity to ambient temperature, water temperature proved not to be appropriate for estimating the interaction between ditch and stream. For accuracy, additional methods will be needed to calculate mixing ratios between stream and ground water within drainage system.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.157-165
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• 2010

This study was carried out to suggest the basic data of planting method for construction of buffer green space based on the land use in case of reclaimed land by analyzing land structure, planting concept, and planting structure in buffer green space, Rokko Island, Kobe, Japan. Rokko Island(total area: 580ha) is divided into port and logistics industry area and urban area by constructing the box type large-scale buffer green space. The land structure of buffer green space were biased mounding type, parallel mounding type, and complex mounding type. The width of buffer green space was 50meters in case of northern area, from 28 to 32meters in case of eastern area, and 37.5meters in case of western area, and the slope of that was from 18 to 25 degrees and the height of that was from 2 to 15meters. There were applied landscape and buffer planting concept on the sea side area of northern buffer green space, on the other hand landscape and shade planting concept on the Inner city side area of that. According to the result of planting structure analysis of northern buffer green space, the main woody species were those of deciduous-evergreen species grow in warm-temperate forest zone such as Quercus glauca, Cinnamomum camphora, Machilus thunbergii, Elaeagnus maritima. The results of maximum number of species and planting density by $100mm^2$ was that 9 species 22 individuals in canopy layer, 9 species 15 individuals in understory layer, 3 species 67 individuals in shrub layer, and 14 species 104 individuals in total. The plant coverage of northern buffer green space based on the ecological planting method was from 69 to 139% in case of canopy layer, from 26 to 38% in case of understory layer, from 6 to 7% in case of shrub layer, and from 101 to 184% in total. Index of plant crown volume of northern buffer green space based on the ecological planting method was from 1.40 to $3.12m^3/m^2$ in case of canopy layer, from 0.43 to $0.55m^3/m^2$ in case of understory layer, $0.06m^3/m^2$ in case of shrub layer, and from 1.89 to $3.73m^3/m^2$ in total.

• Journal of the Korean Geotechnical Society
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• v.15 no.2
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• pp.43-71
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• 1999

This research is an experimental work of developing a construction material using municipal wastewater sludge as liner and cover materials for waste disposal landfill. Weathered granite soil and flyash, produced as a by-product in the power plant, were used as the primary additives to improve geotechnical engineering properties of sludge. For secondary additives, bentonite and cement were mixed with sludge to decrease the permeability and to increase the shear strength, respectively. Various laboratory test required to evaluate the design criteria for liner and cover materials, were carried out by changing the mixing ratio of sludge with the additives. Basic soil properties such as specific gravity, grain size distribution, liquid and plastic limits were measured to analyze their effects on permeability, compaction, compressibility and shear strength properties of mixtures. Laboratory compaction tests were conducted to find the maximum dry densities and the optimum moisture contents of mixtures, and their effectiveness of compaction in field was consequently evaluated. Permeability tests of variable heads with compacted samples, and the stress-controlled consolidation tests with measuring permeabilities of samples during consolidation process were performed to obtain permeability, and to find the compressibility as well as consolidational coefficients of mixtures, respectively. To evaluate the long term stability of sludges, creep tests were also conducted in parallel with permeability tests of variable heads. On the other hand, for the compacted sludge decomposed for a month, permeability tests were carried out to investigate the effect of decomposition of organic matters in sludges on its permeability. Direct shear tests were performed to evaluate the shear strength parameters of mixed sludge with weathered granite, flyash and bentonite. For the mixture of sludge with cement, unconfined compression tests were carried out to find their strength with varying mixing ratio and curing time. On the other hand, CBR tests for compacted specimen were also conducted to evaluate the trafficability of mixtures. Various test results with mixtures were assessed to evaluate whether their properties meet the requirements as liner and cover materials in waste disposal landfill.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.1
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• pp.65-73
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• 2019

The MODIS (Moderate Resolution Imaging Spectroradiometer) data in Hierarchical Data Format (HDF) have been processed using the Geospatial Data Abstraction Library (GDAL). Because of a relatively large data size, it would be preferable to build and install the data analysis tool with greater computing performance, which would differ by operating system and the form of distribution, e.g., source code or binary package. The objective of this study was to examine the performance of the GDAL for processing the HDF files, which would guide construction of a computer system for remote sensing data analysis. The differences in execution time were compared between environments under which the GDAL was installed. The wall clock time was measured after extracting data for each variable in the MODIS data file using a tool built lining against GDAL under a combination of operating systems (Ubuntu and openSUSE), compilers (GNU and Intel), and distribution forms. The MOD07 product, which contains atmosphere data, were processed for eight 2-D variables and two 3-D variables. The GDAL compiled with Intel compiler under Ubuntu had the shortest computation time. For openSUSE, the GDAL compiled using GNU and intel compilers had greater performance for 2-D and 3-D variables, respectively. It was found that the wall clock time was considerably long for the GDAL complied with "--with-hdf4=no" configuration option or RPM package manager under openSUSE. These results indicated that the choice of the environments under which the GDAL is installed, e.g., operation system or compiler, would have a considerable impact on the performance of a system for processing remote sensing data. Application of parallel computing approaches would improve the performance of the data processing for the HDF files, which merits further evaluation of these computational methods.

• Korea Science and Art Forum
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• v.19
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• pp.293-305
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• 2015

At the same time the unique cultural traits of each country are valued, it has become an essential element to establish the cultural identity of a country. This study is aimed at comparing the residence architectural cultures in East-Asia and thus identifying Korea's own unique traits by determining the application characteristics of traditional architectures of Korea, China and Japan through practical investigation of materials, a basic element of architectural shaping. Literature survey and field study were conducted in parallel for this study, and architectural buildings under investigation included Mucheomdang House in Korea, Prince Gong Mansion in China and Dokyudo Building in Japan. Construction materials in Korea, China and Japan include natural materials such as wood, stone and clay, and artificial materials such as metals, paper, roof tiles, plug and glass. and the buildings were constructed with the combination of these materials. This commonality can be often found in the architectural composition. However, in the interior composition, the choice and application of different materials were clear between three countries, which were shown to be different depending on climates, processing methods and living culture of each country. First of all, since each country selected materials under the influence of its own vegetation and climates, living environment of each country could be seen via its residence. Also, it could be seen that while Korea and Japan show a certain similarity such as the traits of standing-sitting culture and the finish of paper in the interior, China is clearly different. In particular, regarding the material processing, the artificial processing was minimized in Korea, which mainly gave rough and crude feelings while due to the use of straight timbers, the architectural representation with organized and refined feelings was made in Japan. China showed the highest percentage of artificial processing of materials among three countries, which was highly associated with the coloring culture of China. Also, it could be seen that technology related to fine architectural materials such as bricks and glass was greatly advanced in China. Thus, how immaterial elements such as natural characteristics, functionality and aesthetics were applied in relation to residence in Korea, Japan and China could be determined through the comparison of architectural materials.