• Journal of the Korean Geosynthetics Society
• /
• v.18 no.4
• /
• pp.299-306
• /
• 2019

In this study, a model experiment that simulates the behaviour of the ground composed of several compacted layer was intended to measure the loosened area in the event of a ground cavity through a LAD (Loosened area detector). It was confirmed that the size of the cone diameter was affected by the ground composed of fine grain + granulated soil layered through the model soil. In order to select the appropriate cone type, a scale effect experiment was conducted. From the test results, a micro-cone was chosen for the most suitable indoor model experiment. In the case of applying LAD in this study, the loosening condition of the ground was determined by the rapid change in penetration resistance caused by the difference in the boundary surface and relative density due to the compaction of the ground for indoor model testing. The range of loosened area occurring in the cavity was estimated through the penetration resistance characteristics on the ground, and the failure area was identified through the reduction rate of penetration resistance in the loosening area.

• Geomechanics and Engineering
• /
• v.35 no.2
• /
• pp.109-119
• /
• 2023

Ground subsidence in urban areas due to excessive development and degraded underground facilities is a serious problem. Geophysical surveys have been conducted to estimate the distribution and scale of cavities and subsidence. In this study, electrical resistivity tomography (ERT) was performed near an area of road subsidence in an urban area. The subsidence arose due to groundwater leakage that carried soil into a neighboring excavation site. The ERT survey line was located between the main subsidence area and an excavation site. Because ERT data are affected by rapid topographic changes and surrounding structures, the influence of the excavation site on the data was analyzed through field-scale numerical modeling. The effect of an excavation should be considered when interpreting ERT data because it can lead to wrong anomalous results. A method for performing 2D inversion after correcting resistivity data for the effect of the excavation site was proposed. This method was initially tested using a field-scale numerical model that included the excavation site and subsurface anomaly, which was a loosened zone, and was then applied to field data. In addition, ERT data were interpreted using an existing in-house 3D algorithm, which considered the effect of excavation sites. The inversion results demonstrated that conductive anomalies in the loosened zone were greater compared to the inversion that did not consider the effects of excavation.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.7 no.2
• /
• pp.119-131
• /
• 2005

The two dimensional behaviors of the existing upper tunnel and the ground at crossed area due to the excavation of a lower tunnel were studied experimentally, The model tests were conducted by changing the relative location of the existing upper tunnel and the lower tunnel. The results of the study show that a vertical earth pressure outside the loosened area was increased due to longitudinal arching effect same as a single tunnel. In case vertical distance between the upper and lower tunnel is 0.7 H and 1.0 H respectively (H is a height of the lower tunnel), vertical earth pressure increased in the loosened area behind the tunnel face. But when a vertical distance is 1, 3 H, ground behaviors appeared similarly to a single tunnel.

• Journal of the Korean Applied Science and Technology
• /
• v.14 no.2
• /
• pp.35-40
• /
• 1997

The organization of phospholipid monolayers and their monolayers mixed with fatty acid containing azobenzene on the water surface was investigated by means of the displacement current measurement method. The phase transition from the gaseous phase to the gaseous-fluid phase which accompanies the polar ordering of phospholipid molecules was detected in the range of immeasurably low surface pressure. The molecular area which gives the onset of the transition was determined for phospholipid monolayers. The Maxwell displacement current(MDC) pulses were generated across mixed monolayers due to the photoisomerization of fatty acid containing azobenzene by alternating irradiation of ultraviolet and visible light, because the condensation of pure azobenzene monolayers was loosened by the introduction of phospholipids into the monolayers. The displacement currents generated during light irradiation were also investgated in connection with monolayer compression cycles. It was found that the maximum of MDC appeared at the molecular area just before the initial rise of surface pressure in compression cycles.

• Tunnel and Underground Space
• /
• v.8 no.1
• /
• pp.46-52
• /
• 1998

The author conducted new back analysis method using monitoring data to a landslide which occurred around portal. In this case, because the tunnel being located under the sliding plane of the landslide, calculated value from the ordinary back analysis in which considered only stress release by the tunnel excavation didn't fit the measured value. Then, in the new method, a body force as the movement of the landslide mass was added to the ordinary back analysis and good results were obtained. Furthermore, the author carried out stability analysis of the landslide with the data of the back analysis and examined the loosened area and decreasing og the sliding plane strength due to the tunnel excavation.

• Fashion & Textile Research Journal
• /
• v.8 no.2
• /
• pp.203-208
• /
• 2006

The purpose of this study is to examine the ergonomic working uniform. Developing a prototype uniform will be the first stage in aiming to create a working uniform in the construction field. This study was conducted using a questionnaire in the construction field of Daegu city, and the data was gathered from 121 questionnaires. Some of the questions that were asked, were about the case of putting on and removing the uniform and if any areas of uniform caused discomfort. The areas of the uniform that caused problems were the waist, knee, shoulder, arm and neck regions. The free range of movement of these regions were restricted and caused the person to feel cramped. The results of the questionnaire called for improvements to the knee, waist, shoulder and crotch area. The prototype that was developed offered more range of movement in the knee and crotch area, while not causing the uniform to be cramped too much during motion. The prototype also improved comfort by raising the waist line of back part, and by having the ability of the uniform to be tightened or loosened with zipper according to the persons preference. The upper area of the uniform was improved by dropping the shoulder seam line which enhanced comfort and also allowed a better fit for the elbow and wrist. The prototypes additional feature included a slit zipper in the sides of the trousers and a gusset in the under arm area to improve breathability and sweat elimination.

• The Journal of Korean Academy of Prosthodontics
• /
• v.40 no.1
• /
• pp.53-67
• /
• 2002

This study was aimed to analyze the stress distribution of implant and supporting tissue in single tooth implant restoration using Branemark $system^{(R)}$(Nobel Biocare, Gothenberg, Sweden) and Bicon system(Bicon Dental Implants, Boston, MA). Two dimensional finite element analysis model was made at mandibular first premolar area As a crown materials porcelain, ceromer, ADA type III gold alloy were used. Tests have been performed at 25Kgf vertical load on central fossa of crown portion and at 10Kgf load with $45^{\circ}$ lateral direction on cusp inclination. The displacement and stresses of implant and supporting structures were analyzed to investigate the influence of the crown material and the type of implant systems by finite element analysis. The results were obtained as follows : 1. The type of crown material influenced the stress distribution of superstructure, but did not influence that of the supporting alveolar bone. 2. The stress distribution of ceromer and type III gold alloy and porcelain is similar. 3. Stress under lateral load was about twice higher than that of vertical load in all occlusal restorative materials. 4. In Bicon system, stress concentration is similar in supporting bone area but CerOne system generated about 1.5times eater stress more in superstructure material. 5. In Branemark models, if severe occlusal overload is loaded in superstvucture. gold screw or abutment will be fractured or loosened to buffer the occlusal overload but in Bicon models such buffering effect is not expected, so in Bicon model, load can be concentrated in alveolar bone area.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.26 no.2
• /
• pp.194-206
• /
• 1998

In 1977, Local governments' planting regulations for the development projects were established in accordance with the revised building law in Korea. A landscaped area, planting densities of trees and shrubs, a percentage of evergreen plants, minimum tree size and species were prescribed in the planting regulations. But the clauses for an excessive planting density and a high ratio of evergreen trees that the regulations includes, have been gradually in the way to a creative planting design, and raise a problem of poor growth of trees an a disordered planting landscape. Therefore, in this study the present planting regulations of 124 local governments throughout the country were analyzed and compared with 13 foreign local governments' of 4 countries ; Japan, the United States of America, Canada and Singapore. And the linitations and characteristics of the regulations are drawn as follows ; 1. The regulations focus on controlling the green spaces and plantings by quantitative methods such as controlling the number of trees and the landscaped area, which are inadequate for estimating the crown coverage of mature trees, and which areinadequate for estimating the crown coverage of mature trees, and implementing the function of polantings and the use of green spaces. 2. Minimums of tree densities are higher than those of foreign countries, especially higher about 10 times to 100 times than those of the United States of America. 3.Excessive number of evergreen trees and fruit trees should be planted under the present planting regulations, that results in constricting the creativity in planting design. 4. An article for using specific tree size, 2.0ms over in height makes it difficult to use a wide variety of different sizes of trees. And there is no incentive measures when larger trees are planted. To enhance the quality of green spaces and plantings, it is needed that the function and locating of green spaces and plantings have to be emphasized, and the planting density should be concerned about the mature tree size. The incentive measure to use various sizes of trees is also needed, and the regulations to use excessive number of evergreen trees or fruit trees should be loosened.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.57 no.4
• /
• pp.430-435
• /
• 2012

Low silage corn yield due to bad soil physical properties in the paddy field converted to upland condition is the chief obstacles to expanding the area for silage maize production. The effect of subsoiling (subsoiling to depth 40 cm) on soil physical properties and silage corn yield were investigated in the first year of paddy field converted to upland condition in 2010 and 2011, respectively. Soil compaction was loosened much particularly at depth 25~35cm as much as 1~1.5 MPa and soil bulk density and porosity at depth 15~30 cm are improved by subsoiling. Maize growth was increased by subsoiling, particularly in kernel number per ear which increased ear weight. Total digestible nutrients (TDN) yield of silage maize was increased as much as 19 and 39% in 2010 and 2011, respectively showing that yield increase according to subsoiling was higher when maize growth was prohibited much by excess-moisture injury due to heavy rain in 2011.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.18 no.5
• /
• pp.499-509
• /
• 2016

In recent years, the use of underground spaces becomes more frequent and the demands for urban tunnels are rapidly increasing. The urban tunnels constructed in the ground with a shallow and soft cover might be deformed in various forms on the face, which would lead, the tunnels to behavior 3-dimensionally, which may have a great impact on the longitudinal load transfer. The tunnel face might deform in various forms depending on the construction method, overburden and the heterogeneity of the ground. And accordingly, the type and size of the distribution of the load transferred to the ground adjacent to the tunnel face as well as the form of the loosened ground may appear in various ways depending on the deformation form of the tunnel face. Therefore, in this study was conducted model tests by idealizing the deformation behavior of the tunnel face, that were constant deformation, the maximum deformation on the top and the maximum deformation on the bottom. And the test results were analyzed focusing on the deformation of the face and the longitudinal load transfer at the ground above the tunnel. As results, it turned out that the size and the distribution type of the load, which was transferred to the tunnel as well as the earth pressure on the face were affected by the deformation type of the face. The largest load was transferred to the tunnel when the deformation was in a constant form. Less load was transferred when the maximum deformation on the bottom, and the least load was transferred when the maximum deformation on the top. In addition, it turned out that, if the cover became more shallow, a longitudinal load transfer in the tunnel would limited to the region close to the face; however, if the cover became higher than a certain value, the area of the load transfer would become wider.