• Journal of the Korean Institute of Landscape Architecture
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• v.17 no.3
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• pp.21-34
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• 1990

Trail and campground deteriorations and their environmental changes of soil and vegetation were studied in Tonghwa -Sa district of Mt. Palgong Natural Park through 1988 into 1989. The results are summarized as follows : 1. The bare width of trail as one of the trail condition factor was significantly greater on the more heavily used trail. Deterioration types of trail which had higher frequency for a total of 45 observations were rock exposure(42%), trail deepening(40%) and root exposure(18%) in the high order. And also sound type on which the trail was not deteriorated at all amounted to 33% of all observations. 2. Ecological changes of soil and vegatation of trailsides were not found at a uniform tendency except that soil hardness was slightly decreased from trail edge to the forest, but they could be grouped by the type of user\`s behavior and site conditions. Use impacts on the natural environment of trailside in Mt. Palgong are still far from the severe harmulness. 3. Worse damages to compground condition were appeared in Bawi-gol than Susu-gol campsite. Types of mechanically damaged trees were tree with exposed root(63% ), scared tree(43% ), mutilated tree(30 % ) and felled tree in highly frequent order. And diameter increments of trees in campsites were oppressed by the campers. 4. Tree damage types and their frequencies could be basic as a means of which grasp the bounds of user's impacts. User's disturbance on campsite extended to the distance of 70∼90m from the core of campsite at Pawi-gol and 20∼30m at Susu-gol respectively. As the tolerant trees to use impact, Lespedeza maximowiczii, Rhus trichocarpa, Acer palmatum, Rubus crataegifolius and Celastrus orbiculatus were considered.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.48-52
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• 2008

According to extremely industrial growth, gas facilities, equipments and chemical plants are gradually increased due to incremental demands of annual amount of gases. The safety management of gases, however, is still far from their requirements. Methane, the principal ingredient of natural gas, is inflammable and explosive and is much used in factories and houses. Therefore, these gas safety management is essential. So, we, with a program of the gas safety management, hope to develop the detection system of methane gas leak using mid-infrared ray LED and PD with $3.2\;{\mu}m$. The cryogenic cooling device is indispensible at laser but needless at LED driven on the room temperature if manufacturing optical sensor with $3.2\;{\mu}m$. It, consequently, is not only possible to implement for subminiature and portable type but also able to speedily detect methane of extremely small quantities because the $CH_4$ absorption intensity at $3.2\;{\mu}m$ is stronger than that at $1.67\;{\mu}m$. Our objective of research is to prevent gas leak accidents from occurring previously and to minimize the extent of damage from them.

• Korean Journal of Heritage: History & Science
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• v.43 no.3
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• pp.122-143
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• 2010

The Shilla Stone Monument in Jungseongri was found during the road-construction in Pohang. It has approximately two hundreds of letters inscribed on the surface of one side, and it is estimated to be older than Shilla Stone Monument in Naengsuri which had been known for the oldest stele in Shilla Period. This monument is made of fine to medium-grained biotite granite, while the Shilla Stone Monument in Naengsuri is made of fine-grained granodioritic porphyry bearing feldspar and amphibole phenocrysts. Both rock types of the monuments are interpreted to be cognate with biotite granite in Shinkwangmyeon, and with granodioritic porphyry in Gigyemyeon. They are characterized by xenolith and miarolitic cavity. Damage aspects in both monuments are discoloring, cracking and breaking. These damages do not cause structural instability of the monuments, but attenuate aesthetic value. Black and brown discoloring contaminants on the surface of the Jungseongri Monument contain a high amount of manganese and iron. As a result of ultrasonic test, both monuments were evaluated to be medium-weathered (MW), although the velocity of the Shilla Monument in Jungseongri was slightly lower than the Shilla Monument in Naengsuri. This is because the Monument in Juengseongri had been exposed to outdoor environment for long time until the discovery. It is necessary for Shilla Monuments to be protected by appropriately environmental control and management.

• Korean Journal of Heritage: History & Science
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• v.45 no.2
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• pp.100-113
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• 2012

The tombstone of Yi Chungmugong in the Joseon Dynasty located Namhae, Gyeongnam is consisted of sandstone. The Bisin and Bijwa of the tombstone have narrow range of magnetic value less than $0.2({\times}10^{-3}SI\;unit)$ and the Isu covered pigment on surface also has same magnetic susceptibility range. Therefore, the composition of all tombstone have similar lithological characteristics. The side of the tombstone appeared fine-grained sandstone to coarse-grained graywacke boundary clearly and back of tombstone observed lamination. Especially deterioration type is concentrated in front and back of the tombstone blistering (8.2% of back), scaling (10.2% of back), granular disintegration (28.1% of back) and discoloration (53.5% of front). Results of contaminants analysis, the front of the Bisin separated in 3 type of surface - granular disintegration-scaling. Among this area, surface detected Ca, S and Cl in high density, but these contaminants elements have more lower detect density from surface to granular disintegration. By contrast, on scaling area, these components are almost not detected, but Fe, K consisted of rock forming elements are detected. It is necessary to conservation and treatment of Yi Chungmugong tombstone in continuously, and salt cleaning on surface also needed. So through activity of conservation and restoration, epigraph preserved for their worth.

• Journal of the Korean Geotechnical Society
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• v.37 no.1
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• pp.29-41
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• 2021

Although underground works are essential to use underground spaces in urban areas efficiently, various damages caused by constructions have often occurred, making them major social problems. Since 2018, it is stipulated in the Special Act on Underground Safety Management that appropriate construction methods must be used in the design stage to prevent various damage cases. This Special Act includes establishing an area subject to underground safety impact assessment, analysis of ground and geological status, review of effects caused by changes in groundwater, review of ground safety, and establishment of measures to secure underground safety. This study area consists of various strata in order of landfill, sedimentary silt, sedimentary sand, sedimentary gravel, weathering zone, and foundation rock. Also, the slurry wall, a highly rigid underground continuous wall, was chosen as a construction method to consider high water table distribution and minimize the influence of the surroundings in this area. However, ground subsidence occurred on the road nearby in December 2019 due to the inflow of loosening soil to the construction area. Thus, several types of site investigations were conducted to suggest an appropriate analysis method and to find out loosed ground behavior and its area for the subsided site. As a result, new design soil properties were re-calculated, and the reinforcement measures were proposed through analytical verification.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.4
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• pp.320-329
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• 2022

Physiological wear of occlusal surface is inevitable throughout the lifetime, and considered to be normal. Pathologic wear, however, may cause fatal damage to the occlusal surface and destroy esthetics and proper anterior guidance. In such cases, rehabilitation of occlusal wear should be followed by thorough evaluation and diagnosis. In this present case, severe occlusal wear was found in the labial surfaces of mandibular anterior teeth and palatal surfaces of maxillary anterior teeth. Occlusal vertical dimension was evaluated and decided to be regained due to insufficient amount of restorative space. After determining new occlusal vertical dimension, diagnostic wax-up is usually performed to continue prosthodontic treatment. In this case with collapsed occlusion and loss of occlusal vertical dimension, conventional diagnostic wax-up was replaced with various digital devices. Diagnostic wax-up was digitally performed in the software and provisional prosthesis was fabricated with digital tools. With verification with provisional prosthesis, the entire dentition was rehabilitated with newly set occlusal vertical dimension and proper anterior guidance.

• Nuclear Engineering and Technology
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• v.55 no.8
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• pp.2773-2784
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• 2023

It is essential to evaluate the blasting-enhanced permeability (BEP) feasibility of a low-permeability sandstone-type uranium deposit. In this work, the mineral composition, reservoir physical properties and rock mechanical properties of samples from sandstone-type uranium deposits were first measured. Then, the reformability evaluation method was established by the analytic hierarchy process-entropy weight method (AHP-EWM) and the fuzzy mathematics method. Finally, evaluation results were verified by the split Hopkinson Pressure Bar (SHPB) experiment and permeability test. Results show that medium sandstone, argillaceous sandstone and siltstone exhibit excellent reformability, followed by coarse sandstone and fine sandstone, while the reformability of sandy mudstone is poor and is not able to accept BEP reservoir stimulation. The permeability improvement and the distribution of damage fractures before and after the SHPB experiment confirm the correctness of evaluation results. This research provides a reformability evaluation method for the BEP of the low-permeability sandstone-type uranium deposit, which contributes to the selection of the appropriate regional and stratigraphic horizon of the BEP and the enhanced ISL of the low-permeability sandstone-type uranium deposit.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.405-417
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• 2010

Previous studies have already shown that mouthguard is effective in protecting jaw bone, teeth and oral tissue against sports trauma. However, other than severe trauma, repetitive force, such as disorders like clenching, cause teeth or oral tissue damage. These kinds of disorders usually present pathologic attrition in the posterior teeth, resorption in alveolar bone, loss of teeth and destruction of occlusion. Wearing a mouthguard is believed to be effective in preventing these disorders. But its effect is not examined thoroughly enough. The purpose of this study is to identify whether mouthguard is effective in reducing strain caused by clenching. Mandibular first molars in the normal occlusal relationship without any history of dental treatment were chosen. Biaxial type strain gauge was placed on the buccal surface of the tooth. Having maximum occlusal force, measured by load cell, as a standard, clenching intensity were divided into three stages; moment of slightly tooth contact, medium bite force (50% of maximum bite force), maximum bite force. Strain occurring in dentition in each stage with and without mouthguard was measured. Changes in strain (on dentition) between each stage and difference in strain, between with or without mouthguard were recorded by PCD-300 analyzer and PCD-30 soft ware. The data was statistically analyzed by Wilcoxon signed rank test. The following results were drawn; Without mouthguard, strain given on dentition increased as the clenching force increased. With mouthguard, strain given on dentition also increased as the clenching force increased. With mouthguard, strain decreased, in all cases of clenching force stages. Data on the moment of slightly tooth contact stage, had no statistical significance. However, with mouthguard, 50-90% of decrease in strain could be obtained in maximum occlusal force, compared to the group without mouthguard. Mouthguard decreased the strain on the dentition, caused by clenching. Therefore, mouthguard seems to be effective in preventing damage on dentition, by acting against clenching, which occurs both consciously and unconsciously during sports activities.

• Journal of the Korean Institute of Landscape Architecture
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• v.38 no.3
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• pp.33-40
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• 2010

Many trails have been built and utilized in each sub-basin of Apsan Park. This study focused on the conditions and the present flora of several overused trails within three basins called Kun-Gol, Anjiroung-Gol, and Meaja-Gol in Apsan Park. There are two purposes for this study. The first is to make a plan for restoration by classifying the type of damage to these overused trails. The second is to provide preliminary data for reestablishing a more pleasant urban nature park. As a result of the survey, the average length of these trails is 9.0km and mean width is 2.0 to 2.6m. 2,108m of the sections studied(23.4% of the total) had exposed root, 3,199m of the sections studied (35.5% of the total) had exposed rock, 3,270m of the sections studied(36.6% of the total) displayed damaged pathways, and 4,841m of the sections studied (53.8% of the total) had higher soil hardness. Eighty-three areas of deterioration were found and there has been extensive property destruction. As an indication of human disturbances, the Naturalization Index and Urbanization Index appeared as: Kun-Gol, 7.0%, 5.5%; Anjiroung-Gol, 8.3%, 4.5%; Meaja-Gol 8.6%, 6.2%; in total, 7.8%, 8.3%. As a method of checking the level and extent of the damage process, an impact rating classification was used at each point on the trails. Kun-Gol had the highest rating and Anjiroung-Gol had the lowest rating in impact rating classification. With the impact rating classification, it was found that each trail would continue to worsen, meaning that roots and rocks are more likely to be further exposed and the trail width will continue to widen through overuse. An actual plan for reparations and restoration of the trails is needed through further study.

• Clinical and Experimental Reproductive Medicine
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• v.37 no.1
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• pp.13-23
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• 2010

Objective: The present study was carried out to induce differentiation of human embryonic stem cells (hESCs) into germ cells and to establish a culture condition for single hESCs dissociated by enzyme. Methods: Embryonic body (EB) was formed by hanging drop culture for 3 days from hESCs colony. The EBs were cultured in the medium supplemented with retionic acid (RA) or/and bone morphogenetic protein-4 (BMP4) for 14 days to differentiate into germ cells. Germ cell specific markers, c-kit and VASA were used for immunohistochemistry of EB. Human ESCs colonies were dissociated into single cells by Collagenase, Tryple and Accutase, and then colony formation rate of the single cells was examined. Rho-associated kinase inhibitor (ROCK inhibitor, Y27632) was added into the culture medium of single cells to reduce the apoptotic damage during the dissociation. Results: Single cells dissociated with Tryple or Accutase showed higher colony formation rates compared to the cells dissociated with Collagenase. Seeding of $5{\times}10^3$ cells/well (4 well dish) was efficient to obtain high colony formation rate compared to other concentrations of seeding cell. Addition of Y27632 significantly increased the colony formation rate of the single cells dissociated by Tryple. Immunohistochemistry of EB with c-kit and VASA markers showed a weak fluorescence signals compared to the signals from the testicular tissue. Conclusion: Dissociation with Tryple was useful to obtain healthy single cells and addition of Y27632 was beneficial for survival and colony formation of the single cells. Unlike other studies, we just observed a dim fluorescence staining of the germ cell markers, probably caused by the short-term culture for the differentiation of EB compared to other studies.