• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.1
• /
• pp.13-24
• /
• 2021

Tunnel boring machine (TBM) is widely used for tunnel excavation in hard rock and soft ground. In the perspective of TBM-based tunneling, one of the main challenges is to drive the machine optimally according to varying geological conditions, which could significantly lead to saving highly expensive costs by reducing the total operation time. Generally, drilling investigations are conducted to survey the geological ground before the TBM tunneling. However, it is difficult to provide the precise ground information over the whole tunnel path to operators because it acquires insufficient samples around the path sparsely and irregularly. To overcome this issue, in this study, we proposed a geological type classification system using the TBM operating data recorded in a 5 s sampling rate. We first categorized the various geological conditions (here, we limit to granite) as three geological types (i.e., rock, soil, and mixed type). Then, we applied the preprocessing methods including outlier rejection, normalization, and extracting input features, etc. We adopted a deep neural network (DNN), which has 6 hidden layers, to classify the geological types based on TBM operating data. We evaluated the classification system using the 10-fold cross-validation. Average classification accuracy presents the 75.4% (here, the total number of data were 388,639 samples). Our experimental results still need to improve accuracy but show that geology information classification technique based on TBM operating data could be utilized in the real environment to complement the sparse ground information.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.50 no.3
• /
• pp.1-18
• /
• 2022

Prior studies have shown positive effects of outdoor activities on the elderly's physical, mental and social health. 'Active aging' and 'age-friendly' neighborhood can be created by modifying the experiences and perceptions of the outdoor environment. This study aims to investigate the outdoor activities of the elderly living in a low-income elderly concentrated area and their perception of the neighborhood environment. We also explored the context of interactions between the facilitators and inhibitors of outdoor activities on the basis of temporal, spatial, and social conditions. We used a mixed method approach by collecting two different types of qualitative GIS data : observation maps of the main places and individual cognitive maps with in-depth interviews. The observational map analysis indicated that the preferred places and activity patterns differ by age, gender, and size of the group. The cognitive map and interviews demonstrated that the elderly's activity goals and perception of the landscape differ by places such as forests, parks, streams, open-spaces, vegetable gardens, and alleys. The elderly's desire for outdoor activities can be better fulfilled when their front doors and alleys are well-connected to an open-sight pleasant space. Familiarity is an important factor for the elderly, therefore it is important to remove the psychological and physical barriers by increasing the legibility and accessibility of places. In addition, social interactions and conflicts can have a significant influence on the elderly's occupation of space in the neighborhood environment.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.5
• /
• pp.355-374
• /
• 2022

Soil conditioning improves the performance of EPB (earth pressure balance) shield TBMs (tunnel boring machines) by reducing shear strength, enhancing workability of the excavated soil, and supporting the tunnel face during EPB tunnelling. The mechanical and rheological behavior of the excavated muck mixed with additives should be properly evaluated to determine the optimal additive injection condition corresponding to each ground type. In this study, the laboratory pressurized vane test apparatus equipped with a vane-shaped rheometer was developed to reproduce the pressurized condition in the TBM chamber and quantitively evaluate rheological properties of the soil specimens. A series of the pressurized vane tests were performed for an artificial sand soil by changing foam injection ratio (FIR) and polymer injection ratio (PIR), which are the injection parameters of the foam and the polymer, respectively. In addition, the workability of the conditioned soil was evaluated through the slump test. The peak and yield stresses of the conditioned soil with respect to the injection parameters were evaluated through the rheogram, which was derived from the measured torque data in the pressurized vane test. As FIR increased or PIR decreased, the workability of the conditioned soil increased, and the maximum torque, peak stress, and yield stress decreased. The peak stress and yield stress of the specimen from the laboratory pressurized vane test correspond to the workability evaluated by the slump tests, which implies the applicability of the proposed test for evaluating the rheological properties of excavated soil.

• Journal of the Korean GEO-environmental Society
• /
• v.22 no.12
• /
• pp.15-24
• /
• 2021

In Korea, which is mostly mountainous, the proportion of tunnel and underground space development are increasing. Although the ground is reinforced by applying the ground improvement method during underground space development, accidents still occur frequently in Korea. In the grouting method, a representative ground reinforcement method, the effect was judged by comparing the total amount of injection material with the amount of injection material used during the actual grouting construction. However, it is difficult to determine whether the ground reinforcement is properly performed during construction or within the target ground. In order to solve this problem, it is necessary to study a new method for quality control during or after construction by measuring electrical resistivity after performing grouting by mixing carbon fiber, which is a conductive material, and microcement, which is a grout material. In this study, as a basic study, a cement specimen mix ed with 0%, 3%, 5%, 7% of carbon fiber was prepared to evaluate the performance of the grout material mixed with carbon fiber, which is a conductive material. The prepared specimens were wet curing for 3 days, 7 days, and 28 days under 99% humidity, and then compression wave velocity and shear wave velocity were measured. As a result of the compression wave velocity and shear wave velocity measurement, it showed a tendency to increase with the increase in the compounding ratio of carbon fibers and the number of days of age, and it was confirmed that the elastic modulus and shear modulus, which are the stiffness of the material, also increased.

• Korean Journal of Crystallography
• /
• v.16 no.2
• /
• pp.75-80
• /
• 2005

[ $LiK_{1-x}Rb_{x}SO_{4}(x=0.1,\;0.2)$ ] crystals were grown by means of aqueous solution growth technique at 313 K. Structure analysis of them was carried out with space group $P6_{3}(#173)$ by X-ray diffraction. In these compounds, the Li and $SO_{4}^{2-}$ ions lying on the three-fold axes formed infinite three-dimensional network and K and Rb atoms located on the six-fold axes are coordinated by twelve and fifteen O atoms respectively. The most suitable stabilization was achieved when the occupancy factors of K and Rb atoms are (0.91 : 0.09), (0.77 : 0.23) respectively.

• Journal of the Korean Society of Costume
• /
• v.55 no.7 s.98
• /
• pp.114-130
• /
• 2005

In postmodernism, the sublime that reaches ecstasy overcoming terror or pain is described as the most expressive phenomenon. The purpose of this study is to understand the sublime expressed in contemporary fashion. for this purpose, 1 investigated the theories of the sublime, categorized the definition and modes, then applied those categories for contemporary fashion. Documentary studies were conducted through aesthetic, design and fashion books and the demonstrative studies were processed by analyzing photos from fashion magazines. In the history of aesthetics, the sublime is explained as the ambivalent feeling mixed with pain and pleasure, terror and delight or negation and affirmation. In this study, the sublime could be defined as the aesthetic pleasure through the transcendence of the pain and terror and classified into 3 categories, the tragic, the initiative, and the deconstructive. The tragic sublime that includes the terrific, the disgusting and the religious character is expressed through the image of death or the physical torture, the satanic image or disgusting object and the ascetic image and religious sign or icons. The limitless sublime that includes the giant and the dynamic character is accomplished by consist of the elongation or the enlargement and the powerful authority. The deconsturctive sublime that includes the negative, the indeterminate and the complex character is associated with the deconstruction in style, the reversal of image and the destruction of the space of the body. Analysis on the sublime expressed in contemporary fashion may provide an excellent way for understanding human aesthetic consciousness in dress.

• Asian-Australasian Journal of Animal Sciences
• /
• v.8 no.3
• /
• pp.275-280
• /
• 1995

The effect of supplemented high protein diet intake on renal urea regulation in swamp buffalo was carried out in the present experiment Five swamp buffalo heifers weighing between 208-284 kg were used for this study. The animals were fed with a supplementary high protein diet and renal function and kinetic parameters for urea excretion were measured. This was compared to a control period where the same animals had been fed only with paragrass and water hyacinth. For 2 months the same animals were fed a mixed of paragrass, water hyacinth plus 2 kgs of a high protein supplement (protein 18.2% DM basis) per head per day. In comparison to the control period, there were no differences in the rate of urine flow, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), plasma urea concentration and filtered urea. In animals supplemented with high protein intake mean values of urea clearance, excretion rate and the urea urine/plasma concentration ratio markedly increased (p < 0.05) while renal urea reabsorption significantly decreased from 40% to 26% of the quantity filtered. In this same study group urea space distribution and urea pool size increased which coincided with an increase in plasma volume (p < 0.05). Plasma protein decreased while plasma osmolarity increased (p < 0.05). Both urea turnover rate and biological half-life of $^{14}C$-urea were not affected by a supplementary high protein intake. The results suggest that animals supplemented with high protein diets are in a state of dynamic equilibrium of urea which is well balanced between urea excreted into the urine and the amount synthesized. The limitation for renal tubular urea reabsorption would be a change in extra-renal factors with an elevation of the total pool size of nitrogenous substance.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.6
• /
• pp.1656-1662
• /
• 2013

The ternary phase $EuZn_xIn_{4-x}$ has been identified as the main product of reactions of Eu, Zn, and In by using the In-flux method and characterized by both powder and single-crystal X-ray diffraction. The structure belongs to the common $BaAl_4$-type (tetragonal space group I4/mmm, Pearson code tI10) with lattice parameters of a = 4.5610(9) ${\AA}$, c = 12.049(3) ${\AA}$ for composition $EuZn_{1.10(12)}In_{2.90}$ and a = 4.5463(3) ${\AA}$, c = 12.028(2) ${\AA}$ for composition $EuZn_{1.18(2)}In_{2.82}$, respectively. In this structure, the Eu atoms are situated at the center of 18-vertex Fedorov polyhedra made of Zn and In atoms, where the 4d site is preferentially occupied by In and the 4e site is occupied by randomly mixed Zn and In atoms. Theoretical investigations using tight-binding linear muffintin orbital (TB-LMTO) method provide rationale for the observed site preferences and suggest potentially wider homogeneity range than the experimentally established for $EuZn_xIn_{4-x}$ ($x{\approx}1.1$).

• Journal of The Korean Society of Agricultural Engineers
• /
• v.57 no.4
• /
• pp.11-19
• /
• 2015

The important properties of EVA (ethylene vinyl acetate) redispersible polymer was waterproof, densification of internal pore space of concrete and ball bearing and micro filler. Also, the significant role of polypropylene(PP) fiber was crack control and blockade of movement for deterioration factors. The most studies for EVA were limited in the field of mortar and PP fiber reinforced concrete had been studied in the state of being restricted unit water content, rich mix and mixing much of the fiber without considering construction site. Therefore, the control mix design were applied in ready mixed concrete using 10 % fly ash of total cement weight used in batch plant. On the basis of control mix design, EVA contents ranging from 0 % to 10 % of total cement weight and PP fiber contents ranging from 0 % to 0.5 % of EVA concrete volume were used in the mix designs. The results showed the maximum compressive strength value was measured at EVA 5.0 % and PP fiber 0.1 %, the minimum water absorption ratio was at EVA 10 % and PP fiber 0 %, the durability factor for freezing and thawing resistance was at EVA 5.0 % and PP fiber 0.3 % and the minimum weight reduction ratio of resistance to sulfuric acid attack was at EVA 10 % and PP fiber 0.5 % after curing age 42days. Meanwhile, From these results, PP fiber reinforced EVA concrete would be very benefit, if each optimal mix types were used in hydraulic structures, underground utilities and agricultural structures.

• Journal of the Korean Geosynthetics Society
• /
• v.18 no.4
• /
• pp.243-252
• /
• 2019

Recently, as the utilization of underground space increases, the demand for underground excavation increases. In this study, the concrete mixture with a new material was used to develop and evaluate the stability of the CS-H wall that can greatly minimize the problems of existing wall and minimize the impact of ground depression and surrounding ground that may occur in the future for excavation of over 30 m deep in urban areas. The fiber reinforcement formulation of steel fibers, synthetic fibers, and glass fibers, along with fine aggregate parts of PS-ball and ferronickel, were mixed. The Mixture ratios were determined by conducting slump test compresive strength test, modulus of elastic test, flexural strength test, splitting tensile strength test and conductivity test. As a result of the test, the steel fiber mixture showed very good results compared to other reference values in all items, and it is considered to be the most suitable for the CS-H wall to be developed.