• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.135-142
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• 2022

Purpose. This study aims to evaluate the combined effect of reduced thickness in different regions on the fracture resistance of monolithic zirconia crowns. Materials and methods. Seven nickel-chromium dies were generated from a 3D model of mandibular first molar using the digital scanner with the following geometries: 1.5 mm occlusal reduction, 1.0 mm deep chamfer. Based on the abutment model, Zirconia blocks (Luxen Zirconia) were selected to fabricate Sixty-three zirconia crowns with occlusal thicknesses of 0.3 mm, 0.5 mm, and 1.5 mm, and different axial thicknesses of 0.3 mm, 0.5 mm, and 1.0 mm. All crowns were cemented by resin cement. Next, the crowns were subjected to load-to-fracture test until fracture using an electronic universal testing machine. In addition, fracture patterns were observed with a scanning electron microscope (SEM). Two-way ANOVA and the Tuckey HSD test for post hoc analysis were used for statistical analysis (P < .05). Results. The mean values of fracture resistancerecorded was higher than the average biting force in the posterior region. The two-way ANOVA showed that the occlusal and axial thickness affected the fracture resistance significantly (P < .05). However, the effect of axial thickness on fracture resistance did not show a statistical difference when thicker than 0.5 mm. The observed failure modes were partial or complete fracture depending on the severity of crack propagation. Conclusion. Within the limitations of the present study, the CAD-CAM monolithic zirconia crown with extremely reduced thickness showed adequate fracture resistance to withstand occlusal load in molar regions. In addition, both occlusal and axial thickness affected the fracture resistance of the zirconia crown and showed different results as combined.

• Journal of Popular Narrative
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• v.27 no.3
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• pp.95-124
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• 2021

As the symbolic images of girls besides its definition have varied according to the age and society, a posthuman girl character recently appears in the digital cinema. This study aims to analyze its cinematic representations and the social contexts in which they are created. For this purpose, the study focuses on what extent the society allows its imagined figurations as a future female body and the meanings revolving around the image of 'technologically body-enhanced female fighter'. Current digital visualization technology has developed to the extent any imaged future humans can be represented, but posthuman girls' representations have its limitation that only a human-like figuration can be allowed in accord with the traditionally idolized image of girls. It is because of the representation logic in which digital cinema is visualized based on perceptual realism that values audiences' experiences. Despite such less critical figuration which does not dare to cross the boundary between the image of human and inhuman, the posthuman girl characters create a new category of the 'dangerous girls' who are both void of sexual femininity and independent of motherhood and heterosexual romance narrative. Of course, they support the modern human-centered belief that humans can take entire control of technology with their moral behaviors and dispel the fear about the negative impact the nature of technology may have on society at large by showing their child-like figuration protecting ethical values. However, the new character of 'unruly girl' exerts her subversive act that seeks to fight against the human-centered liberal humanistic values and melancholic feeling and vulnerability that the neoliberalism and technocracy enforce. When posthuman girl characters are considered to be a marker through which we can see how different social forces are intervening and competing each other in the upcoming posthuman age, the limited figuration of the posthuman girl characters in South Korean movies illustrates the opinionated thoughts toward the instrumentalism in technology but their bloodshed struggles reveal how the corporate or state-governed techno-biopower has oppressively treated and appropriated the human body as the technology-object and also provide a meaningful opportunity to rethink its unethical violence.

• Journal of Popular Narrative
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• v.26 no.4
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• pp.43-76
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• 2020

After comparing three video dramas based on Yoon Sim-duk and Kim Woo-jin, this paper intensively explores the movie Praise of Death(1991), which has the most meaningful traits in embodying the characters, focusing on the relationship with the previous works of the director or an actress. The movie Yoon Sim-duk(1969) focuses on meiodramatic narrative around the issue like love triangle or a relationship between out-of-wedlock woman and the wife of one man. The TV drama Praise of Death(2018) is pursuing ideal youth genre between attractive two lovers adorning even the suffering of the Japanese occupation with customary visual image. In comparison, the movie Praise of Death(1991) focuses on visual beauty, while overlaps the agony of two characters as pioneering artists with frustrated love narrative. In the process, this film reveals two-sided characteristics, especially the heroine, compared to the other two. She shows a rift between the passivity for the salvation of man and the activity of choosing even the fall of her own life. In order to examine this trait, we have to explore the other works which affect the movie Praise of Death. This came from the tendency director Kim Ho-sun and actress Jang Mi-hee had built in 1970s films. It also relates in the movies Jang Mi-hee had worked with director bae Chang-ho in the 1980s. The tendency to show a pursuit of classical cultures in the field of popular movies, and to overlap the problems of desire, including sexuality, with mental and intellectual issues, continues from the previous films to the movie Praise of Death for shaping a main female character. This study results in examining the movie Praise of Death in two contexts. One is the context of three video dramas having same materials, Yoon Sim-duk and Kim Woo-jin. And other is the context of the works that director Kim Ho-sun and actress Jang Mi-hee have continued together, or the works that Jang Mi-hee have continued with director Bae Chang-ho. Until now, Yoon Sim-duk and Kim Woo-jin has been used as a material for cultural contents in the various genres over and over again. Under this circumstance, by looking at this movie, one of representative case dealing with Yoon and Kim, in the complex context, it can reaffirm the effect and difficulty in fictionalisation of them as a subject matter.

• Journal of Popular Narrative
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• v.27 no.2
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• pp.143-177
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• 2021

In the history of Korean literature, evaluations on 『Jirisan』 (Lee Byeong-ju) are bisected. Some evaluate it as a novel of authentic records which reproduces the history before and after the emancipation objectively while others say it takes advantage of anti-communistic ideology. This study analyzes that difference is resulted not from the distinction of perspectives but from cracks in the text. This is associated with the process of 『Jirisan』's publication. 『Jirisan』 was published serially in 『Sedae』 from 1972, and then, part of the manuscript was published in 1978 and the whole edition published in a series came to be republished in 1981. After that, in 1981 and 1985, part of the follow-up story was printed on the magazine, and then, with the memoirs of those two years as materials, the sixth and seventh volumes were again published through 'revision'. In other words, the publication of 『Jirisan』 is divided into that of the edition published in a series and that of the edition published in 1985 including the contents of revision. The theme of the work, 『Jirisan』 differs according to the point of its completion you may think of. This researcher pays attention to the difference of perspectives between the contents up to the fifth volume and those of the sixth and seventh volumes. Particularly, his evaluation on 'partisans' seems to have changed. In the edition published in a series, he extended 'partisans' into the independence movement in the Japanese colonial era under the Revitalizing Reforms system and adopted the representation of 'partisans' three-dimensionally whereas in the sixth and seventh volumes, he reproduced 'partisans' as beings that were the 'doctrinaire' and 'vicious' 'Reds' and had to be punished. In brief, with 『Jirisan』, he represented 'partisans' in the background of history before and after the emancipation and segmented the discourse, representation and ideology of the Cold War system, but in the process of revision, he stitched up 'partisans' as beings that were evil and losers. Consequently, with 『Jirisan』, he revealed the process of division and contention that proceeded around anti-communism/capitalism within the abyss of the 1970's to 80's and reproduced 'partisans' as beings that were either 'hostile (the Reds)' or 'unknown (losers)

• Journal of Korean Society of Disaster and Security
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• v.14 no.4
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• pp.47-60
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• 2021

Recently, as the occurrence frequency of sudden floods due to climate variability increased, the damage of aging chuteway slabs of spillway are on the rise. Accordingly, a wide array of field survey, hydraulic experiment and numerical simulation have been conducted to find the cause of damage on chuteway slabs. However, these studies generally reviewed the flow characteristics and distribution of pressure on chuteway slabs. Therefore the derivation of damage on chuteway slabs was relatively insufficient in the literature. In this study, the cavitation erosion and hydraulic jacking were assumed to be the causes of damage on chuteway slabs, and the phenomena were reproduced using 3D numerical models, FLOW-3D and COMSOL Multiphysics. In addition, the cavitation index was calculated and the von Mises stress by uplift pressure distribution was compared with tensile and bending strength of concrete to evaluate the possibility of cavitation erosion and hydraulic jacking. As a result of numerical simulation on cavitation erosion and hydraulic jacking under various flow conditions with complete opening gate, the cavitation index in the downstream of spillway was less than 0.3, and the von Mises stress on concrete was 4.6 to 5.0 MPa. When von Mises stress was compared with tensile and bending strength of concrete, the fatigue failure caused by continuous pressure fluctuation occurred on chuteway slabs. Therefore, the cavitation erosion and hydraulic jacking caused by high speed flow were one of the main causes of damage to the chuteway slabs in spillway. However, this study has limitations in that the various shape conditions of damage(cavity and crack) and flow conditions were not considered and Fluid-Structure Interaction (FSI) was not simulated. If these limitations are supplemented and reviewed, it is expected to derive more efficient utilization of the maintenance plan on spillway in the future.

• Economic and Environmental Geology
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• v.55 no.4
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• pp.317-338
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• 2022

Physicochemical characteristics and evaluation were studied by subdividing the concretes, bricks and earth pipes on the site of the Japanese Ministry of General Affairs in Joseon Dynasty, known as modern architecture, into three periods. Concretes showed similar specific gravity and absorption ratio, and large amounts of aggregates, quartz, feldspar, calcite and portlandite were detected. Porosity of the 1907 bricks were higher than those of 1910 and 1950 bricks. All earthen pipe is similar, but the earlier one was found to be more dense. Bricks and earthen pipes are dark red to brown in color within many cracks and pores, but the matrix of the earthen pipe is relatively homogeneous. Quartz, feldspar and hematite are detected in bricks, and mullite is confirmed with quartz and feldspar in earthen pipes, so it is interpreted that the materials have a firing temperature about 1,000 to 1,100℃. Concretes showed similar CaO content, but brick and earthen pipe had low SiO₂ and high Al₂O₃ in the 1907 specimen. However, the materials have high genetic homogeneity based on similar geochemical behaviors. Ultrasonic velocity and rebound hardness of the concrete foundation differed due to the residual state, but indicated relatively weak physical properties. Converting the unconfined compressive strength, the 1st extended area had the highest mean values of 45.30 and 46.33 kgf/cm², and the 2nd extended area showed the lowest mean values (20.05 and 24.76 kgf/cm²). In particular, the low CaO content and absorption ratio, the higher ultrasonic velocity and rebound hardness. It seems that the concrete used in the constructions of the Japanese Ministry of General Affairs in Joseon Dynasty had similar mixing characteristics and relatively constant specifications for each year. It is interpreted that the bricks and earthen pipes were through a similar manufacturing process using almost the same raw materials.

• The Journal of Engineering Geology
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• v.33 no.3
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• pp.371-388
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• 2023

A stratum with a complex composition and a distributed low-permeability soil layer is difficult to remediate quickly because the soil remediation does not proceed easily. For efficient purification, the permeability should be improved and the soil remediation agent (H₂O₂) should be injected into the contaminated section to make sufficient contact with the TPH (Total petroleum hydrocarbons). This study analyzed a method for crack formation and effective delivery of the soil remediation agent based on pneumatic fracturing, plasma blasting, and vacuum suction (the PPV method) and compared its improvement effect relative to chemical oxidation. A demonstration test confirmed the effective delivery of the soil remediation agent to a site contaminated with TPH. The injection amount and injection time were monitored to calculate the delivery characteristics and the range of influence, and electrical resistivity surveying qualitatively confirmed changes in the underground environment. Permeability tests also evaluated and compared the permeability changes for each method. The amount of soil remediation agent injected was increased by about 4.74 to 7.48 times in the experimental group (PPV method) compared with the control group (chemical oxidation); the PPV method allowed injection rates per unit time (L/min) about 5.00 to 7.54 times quicker than the control method. Electrical resistivity measurements assessed that in the PPV method, the diffusion of H₂O₂2 and other fluids to the surface soil layer reduced the low resistivity change ratio: the horizontal change ratio between the injection well and the extraction well decreased the resistivity by about 1.12 to 2.38 times. Quantitative evaluation of hydraulic conductivity at the end of the test found that the control group had 21.1% of the original hydraulic conductivity and the experimental group retained 81.3% of the initial value, close to the initial permeability coefficient. Calculated radii of influence based on the survey results showed that the results of the PPV method were improved by 220% on average compared with those of the control group.

• Journal of the Daesoon Academy of Sciences
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• v.44
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• pp.141-175
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• 2023

This comparative study combines the methodologies of comparative research and literature review to examine Daesoon Thought. Comparative religious analysis in the social sciences, does not presuppose an a priori framework of the essence of religion because it targets various aspects of religion which are revealed within a historical field. However, it does not decompose and return to psychological or social phenomena like social sciences. In addition, with the emergence of religious pluralism, the climate of focusing on similarities between religions has already been accomplished to some degree. Furthermore, it is worth noting that many spiritual movements in modern spirituality reveal mixed or amorphous characteristics without being restricted by specific religious membership. It is time to overcome instrumentation and restore the transcendence of its original appearance even in secular humanist reasoning. It can be said that this reveals the perception that the ills and crises of modern civilization should be overcome in connection with the opening of the acquired world of Daesoon Thought. It could further be said that the main culprit of evil behavior is instrumental reason or degenerated reason rather than spirituality. Religion is the intellectual crystalline body of humankind and aims at human perfection and salvation. However, extremists in previous times amplified conflicts between religions and formed ideas suitable for their specific regions through different experiences. This generated mental rifts that proved greatly influential. At the time of initial inception, each religion confronted and fought other ideologies, but when the era of religious pluralism began, the necessity for inter-spiritual communication became urgent. It could be said that happiness is the realization of human spirituality by exploring the vision of humanism. In that case, the combined methodologies of comparative research and literature review reveal that the spirituality of Daesoon Thought would enable a humanism based on human dignity. This would be a path for seeking spirituality through human life and living as a true human being. Spiritual humanism as discussed through this study aims to share the problems of modern civilization and provide a critical view of modern civilization that shows the roots of prevailing thought are stuck in a Cartesian dualistic view of humanity and the world. The type of spiritual humanism to examined here focuses on a cosmotheandric vision by considering the spiritual return to Daoism via Daesoon Thought. This would treat human beings like heaven in alignment with Donghak ideology and honor the human dignity proposed by Daesoon Thought. It would also deliver sentient beings from suffering and to bliss in accordance with the aims of faith in Maitreya Buddha, and it would implement the Resolution of Grievances for Mutual Beneficence in fulfillment of Daesoon Thought.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.491-501
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• 2022

Bentonite has been proposed as a buffer and backfill material for high-level radioactive waste repository. Under such repository environment conditions, bentonite is subjected to combined thermal, hydrological, mechanical, and chemical processes. This study evaluates the feasibility of applying X-ray CT technology on the characterization of bentonite under hydration conditions using a newly developed testing cell. The cylindrical cell is made of platic material, with a removable cap to place the sample, enabling to apply vertical pressure on the sample and to measure swelling pressure. The hydration test was carried out with a sample made of Gyeonju bentonite, with a dry density of 1.4 g/cm³, and a water content of 20%. The sample had a diameter of 27.5 mm and a height of 34 mm. During the test, water was injected at a constant pressure of 0.207 MPa, and lasted for 7 days. After one day of hydration, bentonite swelled and filled out the space inside the cell. Moreover, CT histograms showed how the hydration process induced an initial increase and later progressive decrease on the density of the sample. Detailed profiles of the mean CT value, CT standard deviation, and CT gradient provided more details on the hydration process of the sample and showed how the bottom and top regions exhibited a decrease on density while the middle region showed an increase, especially during the first two days of hydration. Later, the differences in CT values with respect to the initial state decreased, and were small at the end of testing. The formation and later reduction of cracks was also characterized through CT scanning.

• The Journal of Engineering Geology
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• v.32 no.1
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• pp.113-126
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• 2022

The tectonic history of the Chukchi Abyssal Plain in the Amerasia Basin, Arctic Ocean, has not been fully explored due to the harsh conditions of sea ice preventing detailed observation. Existing models of the tectonic history of the region provide contrasting interpretation of the timing of formation of the crust (Mesozoic to Cenozoic), crust type (from hyper-extended continental crust to oceanic crust), and formation process (from parallel/fan-shaped rifting to transformation faulting). To help determine the age of the oceanic crust, the geothermal gradient was measured at three stations in the south of abyssal plain at depth of 2,160-2,250 m below sea level. Heat flow measurement stations were located perpendicular to the spreading axis over a 40 km-long transect. In-situ thermal conductivity measurement, corrected by the laboratory test, gave observed marine heat flows of 55 to 61 mW/m². All measurements were taken during Arctic expeditions in 2018 (ARA09C expedition) and 2021 (ARA12C expedition) by the Korean ice-breaking research vessel (IBRV) Araon. Given the assumption of oceanic crust, the results correspond to formation in the Late Cretaceous (Mesozoic). The inferred age supports the hypothesis of formation activated by the opening of the Makarov Basin during the Late Mesozoic-Cenozoic. This would make it contemporaneous with rifting of the Chukchi Border Land immediately east of the abyssal plain. The heat flow data indicate the base of the gas hydrate stability zone is located 332-367 m below the seafloor, this will help to identify the gas hydrate-related bottom simulating reflector in the future seismic survey, as already identified on the Chukchi Plateau. Further geophysical surveys, including heat flow measurements, are required to increase our understanding of the formation process and thermal mantle structure of the abyssal plain.