• Title/Summary/Keyword: Inclination angles

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Analysis of Groundwater Level Reduction Effects to Burial Angle of Slope Reinforcement Materials (비탈면 보강재의 매설각에 따른 지하수위 저감효과 분석)

  • Hyeonjun Yoon;Sungyeol Lee;Wonjin Baek;Jaemo Kang;Jinyoung Kim;Hwabin, Ko
    • Journal of the Korean GEO-environmental Society
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    • v.24 no.8
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    • pp.5-11
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    • 2023
  • Due to frequent occurrences of concentrated heavy rainfall caused by abnormal climate conditions in recent years, collapses of steep slopes have been occurring frequently due to surface erosion and increased pore water pressure. Various methods are being applied to prevent slope collapses, such as increasing the resistance to movement and reducing pore water pressure. Research on these methods has been consistently conducted as they provide an efficient response to slope collapses by satisfying both the conditions of resistance to movement and pore water pressure simultaneously. Therefore, in this study, we propose an upward slope reinforcement method by burying drainage materials with an upward slope inclination, instead of the conventional horizontal application. This approach aims to satisfy both slope reinforcement and drainage functions effectively, offering a comprehensive solution for slope stabilization. Furthermore, to determine the optimal burial angle that exhibits the most effective reinforcement and drainage effects of the proposed method, we investigated the reinforcement and drainage effects under conditions where the horizontal drainage materials were set at angles ranging from 0° to 60° in increments of 10° on a representative cross-section. Additionally, indoor model experiments were conducted under the conditions of 40°, which showed the most outstanding drainage effect, and 20°, which exhibited the highest safety factor, to validate the numerical analysis results. The results showed that the burial angle of 40° exhibits a relatively higher drainage effect as with the numerical analysis results, while the angle of 20° results in inadequate drainage and observed slope collapse.

Environmental characteristics on habitats of Viola diamantiaca Nakai and its RAPD analysis (금강제비꽃(Viola diamantiaca Nakai) 자생지의 환경특성과 RAPD 분석)

  • Seo, Won-Bok;Yoo, Ki-Oug
    • Korean Journal of Plant Taxonomy
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    • v.41 no.1
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    • pp.66-80
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    • 2011
  • This study investigated the environmental factors and conducted a RAPD analysis for a better understanding of the environmental characteristics and regional genetic variation in samples from 18 different areas of Viola diamantiaca. The habitats are mostly located on the slopes of mountains facing north at an altitude ranging from 614 m to 1,462 m above sea level with angles of inclination ranging from 3 degrees to 30 degrees. A total of 268 vascular plant taxa are identified in 35 quadrates of 18 habitats. The importance value of V. diamantiaca is 11.58%, and four highly ranked species, Sasa borealis (5.61%), Meehania urticifolia (5.21%), Ainsliaea acerifolia (3.62%), Pseudostellaria palibiniana (3.60%) are considered to have an affinity with V. diamantiaca in their habitats. The degree of their average species diversity is 1.36, while this metric for their evenness and dominance are 0.89 and 0.07, respectively. The average field capacity of the soil is 25.99%, with organic matter at 17.47%, and the pH is 5.19. The soil texture was confirmed as sandy loam of eleven and loam of seven. The result of the RAPD analysis, among 78 bands amplified with a primer, 64 (84.6%) showed polymorphism. Eighteen populations could be classified into five groups with similarity coefficient values ranging from 0.53 to 0.86. The Mt. Jiri population, which is geographically segregated, shows basal branching within the 18 populations. Five populations, including two in the southern district in Gangwon-do and three in Chungcheongbuk-do, form a distinct clade. Four populations in the central district of Gangwon-do and Mt. Bohyeon in the Gyeongsangbuk-do clade form a sister to the clade containing two populations in Gyeonggi-do and five populations of the northern district in Gangwon-do. The Mt. Gariwang population is placed between the southern district and the central district in the Gangwon-do clades.

Characteristic of Wave Diffraction and Reflection for Irregular Waves in SWASH Model Around Small Port Structures (소규모 항만 구조물 주변에서 불규칙파에 대한 SWASH 모형의 반사 및 회절)

  • Kwon, Kyong Hwan;Park, Chang Wook;Park, Il Heum;Kim, Jong Hoon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.6
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    • pp.468-477
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    • 2019
  • The numerical model of Boussinesq approximation, which is mainly used for evaluating the port calmness due to the irregular waves, has a limit of applicability of lattice size in ports such as marinas with narrow port openings of around 30m. The SWASH model controls the partial reflection according to the depth, porosity coefficient and structure size when applying the reflected wave incident on the structure and terrain. In this study, the partial reflection evaluation at the front of the structure according to the bottom shape and the shape of the structure are examined. In order to evaluate the reproducibility of the model due to the diffraction waves entering the term, the area of incidence at right angles and inclination of the structure is constructed and compared with the diffraction theory suggested by Goda et al. (1978). The experimental results of the sectional structure reflectances calculated as the depth mean show reflectances similar to the approximate values of the reflectances presented by Stelling and Ahrens (1981). It is considered that the reflected wave is well reproduced according to the control of the reflected wave at the boundary and the shape and topography of the structure. Compared with previous studies to examine the diffraction of the wave incident from the breakwater opening, the wave incidence angle and the shape of the diffraction wave are very similar to the theoretical values, but both oblique and rectangular incidence In the case where the direction concentration is small, the diffraction degree is underestimated in some sections with the crest ratio of 0.5 to 0.6.

Shear Strength and Erosion Resistance Characteristics of Stabilized Green Soils (토양안정재를 혼합한 녹생토의 전단강도 및 침식저항특성)

  • Oh, Sewook;Jeon, Jinchul;Kim, Donggeun;Lee, Heonho;Kwon, Youngcheul
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.12
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    • pp.45-52
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    • 2015
  • With the rising interest in the environment, more attention on ecological restoration for damaged slope surface to restore its original state has been drawn. Generally, the most useful method is vegetation based spray work. This method uses green soil including sewage sludge, sawdust, paper sludge, and weathered granite soil. However, because there are neither accurate information nor test values about green soil, green soil is often lost by environmental factors such as rainfalls and strong winds. To solve the problem of green soil, it is necessary to prepare design standards about green soil, and conduct studies to deal with green soil loss in consideration of various variables including basic material property, soil quality of slope surface, and weather. This study was conducted in the mixture of green soil and eco-friendly soil stabilizer. With green soil, basic material property test and compaction test were conducted for the analysis on the basic characteristics of green soil. In the mixture with soil stabilizer at a certain ratio, we conducted shear strength test depending on the ratio in order to analyze the maximum shear strength, cohesion and the change in internal friction angles. Furthermore, in the mixture ratio of green soil and soil stabilizer, which is the same as the ratio in the shear strength test, an inclination of slope surface was made in laboratory for the analysis on erosion and germination rate. Finally, this study evaluated the most effective and economic mixing ratio of soil stabilizer to cope with neighboring environmental factors. According to the test, the shear strength of green soil increased up to 51% rely onto the mixing ratio of and a curing period, and its cohesion and internal friction angle also gradually increases. It is judged that the mixture of soil stabilizer was effective in improving shear strength and thereby increased the stability of green soil.

The Measurement of Normal Talus in Korean Cadaver (한국인 사체에서의 정상 거골의 실측)

  • Ha, Dong-Jun;Gwak, Heui-Chul;Kim, Jeon-Gyo;Kim, Jung-Han;Lee, Chang-Rak;Kim, Young-Jun;Lee, Jeong-Han;Ha, Byung-Ho;Kim, Ui-Cheol
    • Journal of Korean Foot and Ankle Society
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    • v.20 no.4
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    • pp.163-169
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    • 2016
  • Purpose: To investigate the measured values of the talus in Koreans. Materials and Methods: We measured 88 tali from 44 cadavers that have been donated between December 2012 and December 2015. Of the cadavers, 27 were male and 17 were female. Their mean age was 73 years. The length and width of the talus were measured using a digital goniometer and vernier caliper. Results: The values of cadaveric measurement, mean maximal width and length, width and length of the dome anterior, width and length of the posterior facet, height and length of the trochlear medial facet, and height and length of the trochlear lateral facet were $43.6{\pm}2.6mm$, $56.5{\pm}3.3mm$, $32.5{\pm}2.0mm$, $42.2{\pm}2.7mm$, $22.2{\pm}2.2mm$, $34.7{\pm}2.0mm$, $15.3{\pm}1.3mm$, $33.3{\pm}2.9mm$, $25.3{\pm}3.3mm$, and $30.8{\pm}2.4mm$ for men and $38.9{\pm}1.6mm$, $53.6{\pm}2.4mm$, $27.9{\pm}2.1mm$, $37.4{\pm}3.2mm$, $20.6{\pm}0.8mm$, $31.9{\pm}1.2mm$, $13.6{\pm}2.6mm$, $28.4{\pm}2.5mm$, $24.9{\pm}2.1mm$, and $28.9{\pm}1.4mm$ for women, respectively. The size of the talus showed an accuracy of 86% when anteroposterior diameter was greater than 59 mm. A difference in the size of the right and left talus was not observed. The mean inclination and declination angles were $24.4^{\circ}{\pm}4.2^{\circ}$ and $28.2^{\circ}{\pm}5.4^{\circ}$ for men, and $24.6^{\circ}{\pm}3.6^{\circ}$ and $24.7^{\circ}{\pm}6.7^{\circ}$ for women (p=0.980, p=0.018), respectively, at least $15^{\circ}$, which showed a big difference for every object up to $37^{\circ}$. Conclusion: This paper, to the best of our knowledge, is the first study to measure the talus in Koreans. There were differences by gender and ethnicity in the in measured talus values. The measurements were smaller than European-Americans and greater than Japanese.

Location Environment and Vegetation Structure of the Aconitum austrokoreense Habitat (세뿔투구꽃 서식지의 입지환경 및 식생구조)

  • Cho, Seon-Hee;Lee, Kye-Han
    • Journal of Korean Society of Forest Science
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    • v.110 no.2
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    • pp.165-178
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    • 2021
  • Owing to the lack of consistent research on endangered plant species in Korea, there are insufficient data to preservespecies and expand habitats. This study analyzed the preferred habitat and threats to the survival of Aconitum austrokoreense, found on Baekwun Mountain in Gurye-gun, Gwangyang-si, Jeollanam-do Province, and classified as a level two endangered wild plant by the Ministry of Environment, by investigating major environmental factors such as climate, location, soil, and stand structure. By examining five selected sites inhabited by Aconitum austrokoreense on BaekwunMountain, this study found that the habitat had an altitude of 420 to 675 m above sea level and showed a northeast tendency, spreading over a range of inclination angles between 15° and 37°. The average number of plants across the five sites was 156. Site 4 (550 m) had the highest density of 372 plants, with an average height of 0.6 m. The average soil moisture and relative light intensity were 20.48% and 7.34%, respectively. Layer soil was presumed to be sandy loam, characterized by high sand content and good drainage. The habitat had average soil pH of 5.2, average organic matter of 16.46%, average nitrogen of 0.86%, average available phosphate of 11.86 mg/kg, average electrical conductivity of 0.44 dS/m, and average cation exchange capacity of 37.04 cmolc/kg. The total carbon in soil averaged 10.68%. From the analysis of the vegetation structure of sites inhabited by Aconitum austrokoreense, the dominant populations were Pinus koraiensis and Lindera erythrocarpa in Site 1, Magnolia obovata and Carpinus laxiflora in Site 2, Zelkova serrate and Quercus variabilis in Site 3, Staphylea bumalda and Lindera erythrocarpa in Site 4, and Morus bombycis,Styrax japonicus, and Carpinus laxiflora in Site 5. With most habitats located near trails and sap collection sites of Acer pictum, the species were exposed to artificial damage and interference threats.