• Title/Summary/Keyword: rigidity

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Estimation of Undrained Shear Strength Using Piezocone Test (피에조 콘 시험을 이용한 점성토의 비배수 강도 추정)

  • 박용원;구남실;이상익
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.169-179
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    • 2003
  • Undrained shear strength of clay deposit is one of the most important properties in the design of geotechnical structures. The use of piezocone test is rapidly growing due to its merit that can measure the in-situ undrained shear strength continuously with less error. The reliability of the shear strength from piezocone test depends upon the cone factor applied. Many researchers have suggested different ranges of values for the factors. This study performs to find out the validity of the suggested values in Korea and their charateristics related to the mechanical properties of clay. Piezocone tests were performed at the site of pilot project of ground improvement at Yangsan-Mulgeum Gyeongnam to investigate the charateristics of piezocone factors. The piezocone fators$(N_{kt}, N_{ke}, N_{\Delta u})$ based on the undrained shear strength from quick triaxial compression test are generally within the suggested range. And there appears considerable relations between undrained shear strength and $(N_{kt}, N_{ke}, N_{\Delta u})$ and between preconsolidation pressure and $(N_{kt}, N_{ke})$, while plasticity index, rigidity index and friction ratio do not show any relations with cone factors. The results also reveal that factor $(N_{\Delta u})$ shows higher reliability than factors $(N_{kt} and N_{ke})$, which show smaller standard deviation, breadth of change and scattering.

A Study on the Evaluation of Smear Zone by In-situ Tests (현장시험에 의한 Smear Zone의 평가)

  • 이장덕;구자갑
    • Journal of the Korean Geotechnical Society
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    • v.19 no.6
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    • pp.207-216
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    • 2003
  • To evaluate the smear zone caused by the drain installation, 10 piezometers were installed in the typical soft ground in the western coastal area of Korea. The dynamic pore water pressure developed during the drain installation was monitored using piezometers installed at a distance of 10cm, 20cm, 30cm, 40cm and 50cm from the location of the drain. The decay of pore pressure with time after pushing piezometers to depths of 5 meters and 7 meters during the drain installation was monitored to assess flow and consolidation characteristics of the soil after disturbance of the soil due to the drain installation. The drain installation results in shear strain and displacement of the soil and it decreases the permeability of the soil. Hence, the comparison between dissipation of the pore water pressure process in 10 pieszometers before as well as after installation of the drain indicated the diameter of disturbance zone and smear zone, which is related to the cross-sectional dimension of the mandrel. In addition, Cone-pressuremeter(CPM) tests were performed to obtain rigidity index of the soil for an interpretation of the dissipation processes. It has been evaluated by in-situ tests that the smear zone is from 3.0 to 3.6 times of the cross-sectional dimension of the mandrel. The hydraulic conductivity expressed in terms of the coefficient of consolidation after the drain installation was calculated from 3 to 8 times decrease evaluated by Teh & Houlsby equation and CPM test results.

Crossplot Interpretation of Electrical Resistivity and Seismic Velocity Values for Mapping Weak Zones in Levees (제방의 취약구간 파악을 위한 전기비저항과 탄성파속도의 교차출력 해석)

  • Cho, Kyoung-Seo;Kim, Jeong-In;Kim, Jong-Woo;Kim, Ji-Soo
    • The Journal of Engineering Geology
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    • v.31 no.4
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    • pp.507-522
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    • 2021
  • Specific survey objectives often cannot be met using only one geophysical method, as each method's results are influenced by the specific physical properties of subsurface materials. In particular, areas susceptible to geological hazards require investigation using more than one method in order to reduce risks to life and property. Instead of analyzing the results from each method separately, this work develops a four-quadrant criterion for classifying areas of levees as safe or weak. The assessment is based on statistically determined thresholds of seismic velocity (P-wave velocity from seismic refraction and S-wave velocity from multichannel analysis of surface waves) and electrical resistivity. Thresholds are determined by subtracting the standard deviation from the mean during performance testing of this correlation technique applied to model data of four horizontal and inclined fracture zones. Compared with results from the crossplot of resistivity and P-wave velocity, crossplot analysis using resistivity and S-wave velocity data provides more reliable information on the soil type, ground stiffness, and lithological characteristics of the levee system. A loose and sandy zone (represented by low S-wave velocity and high resistivity) falling within the second quadrant is interpreted to be a weak zone. This interpretation is well supported by the N values from standard penetrating test for the central core.

A Study on Stress and Deformation through Finite Element Analysis of 2NC Head Processing Controlling AC Axis during 5-Axis Cutting Machine Training in the 4th Industrial Revolution of Machine Tool System (공작기계의 4차 산업혁명에서 5축 절삭가공기 교육 중 AC축을 제어하는 2NC 헤드 가공상의 유한요소 해석으로 응력 및 변형에 관한 연구)

  • Lee, Ji Woong
    • Journal of Practical Engineering Education
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    • v.13 no.2
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    • pp.327-332
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    • 2021
  • Materials used for education include SM20C, Al6061, and acrylic. SM20C materials are used a lot in certification tests and functional competitions as carbon steel, but they are also used in industrial sites. Al6061 is said to be a material that produces a lot of tools because it has lower hardness than carbon steel and is highly flexible. When practical guidance is given to students using acrylic materials, it is a material that causes vibration and tool damage due to excessive cutting. In this process, we examine how impact on the 5-axis equipment 2NC head can affect precision control. The weakest part of a five-axis equipment is the head that controls the AC axis. In the event of precision and cumulative tolerances in this area, the precision of all products is reduced. Thus, a key part of the 2NC head, the spindle housing was carried out using Al7075 T6 (U.S. Alcoasa) material and the entire body using FCD450 (spherical graphite cast iron). In the vibration and cutting process acting on these two materials, the analysis was carried out to determine the value of applying the force as a finite element analysis under extreme conditions. We hope that using these analytical data will help students see and understand the structure of 5-axis machining rather than 5-axis cutting.

A Case Report of Non-Motor Symptoms Evaluated Using the Non-Motor Symptom Scale in a Patient with Secondary Parkinsonism Presumed to be Probable Lewy Body Dementia and Improved with Combined Treatment with Herbal Medicine and Acupuncture (루이소체 치매로 추정되는 이차성 파킨슨증 환자의 Non-Motor Symptom Scale(NMSS)로 평가한 비운동성 증상을 한약과 침의 복합치료로 호전시킨 증례보고 1례)

  • Roh, Min-yeong;Lee, Ji-hyun;Han, Yang-hee;Leem, Jung-tae
    • The Journal of Internal Korean Medicine
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    • v.42 no.5
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    • pp.833-845
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    • 2021
  • Parkinson's syndrome is a degenerative brain disease that presents characteristic motor symptoms of tremor, rigidity, and gait disturbance. In addition to these motor symptoms, Parkinson's syndrome also presents non-motor symptoms (NMSs) such as sleep disturbance and cognitive decline. NMSs reduce patient's quality of life and psychosocial functioning and cause economic burden on the patient, so appropriate evaluation and treatment are required. Lewy body dementia is one of the several diseases belonging to Parkinson's syndrome. Its symptoms such as cognitive function, memory impairment, and hallucinations occur with Parkinsonism. Although drug therapy is being used with drug treatment to treat non-motor symptoms, it has limitations such as side effects, which stimulated interest in other complementary treatment methods such as oriental medicine treatment, dance, and yoga. The patient in this case complained of tremor in the right upper extremity, muscle hypertension and pain, and persistent vision, memory, and cognitive decline. The patient was diagnosed with probable Lewy body dementia. The patient was hospitalized for 4 months and received acupuncture and herbal medicines. After treatment, the patient's NMS scale scores decreased from 90 to 63, and the Unified Parkinson's Disease Rating Scale scores (summed I, II, and III) decreased from 17 points to 8 points. The Beck Depression Inventory score decreased from 22 points to 13 points. In addition, the patient's subjective evaluation revealed improvement. In this case, a patient diagnosed with probable Lewy body dementia who did not respond to the standard treatment and did not want to take medications showed improvement in not only motor symptoms but also NMSs after integrative Korean medicine treatment.

Stiffness Improvement of Timing Belt in Power Transmission (동력전달용 타이밍벨트의 강성 개선)

  • Lee, Kyeong-Yeon;Byun, Kyung-Seok
    • Journal of the Institute of Convergence Signal Processing
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    • v.23 no.1
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    • pp.1-7
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    • 2022
  • As a power transmission element, the timing belt is a toothed transmission belt that takes advantages of V-belts and gears. It has characteristics of non-slip and low noise. It is used as a power transmission device when transmitting power from a rotating shaft or linear motion in a mechanism. Rotation can be accurately transmitted through a belt pulley with grooves like a gear and a timing belt with grooves to precisely match with the belt pulley. In particular, in the mechanism in which the timing belt is used for the output shaft, the dynamic characteristics including the rigidity of the timing belt determine the transmission characteristics of the system, so its importance increases. In this paper, a stiffness reinforced belt that can be applied to a timing belt with a limited range of motion to increase its stiffness is proposed. To study the dynamic characteristics of the stiffness reinforced belt, the equation of motion for the stiffness reinforced belt was established, and a simulation model for the stiffness reinforced belt was created and analyzed. In order to confirm the analysis results of the motion equation and simulation model, a 1-axis rotation experimental equipment using a stiffness reinforcing belt was developed and the experiment was conducted. Through motion equations, simulation models, and experiment results, it was confirmed that the stiffness and dynamic characteristics of the timing belt could be improved by applying the proposed stiffness reinforcement belt.

Collision Behavior Comparison of Offshore Wind Tower as Type of Support Structure (지지구조의 형식에 따른 해상풍력타워의 선박충돌거동비교)

  • Lee, Gye-Hee;Kwag, Dae-Jin
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.35 no.2
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    • pp.93-100
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    • 2022
  • The collision behaviors of the tripod and jacket structures, which are considered as support structures for offshore wind towers at the Southwest sea of Korea, were compared by nonlinear dynamic analysis. These structures, designed for the 3 MW capacity of the wind towers, were modeled using shell elements with nonlinear behaviors, and the tower structure including the nacelle, was modeled by beam and mass elements with elastic materials. The mass of the tripod structure was approximately 1.66 times that of the jacket structure. A barge and commercial ship were modeled as the collision vessel. To consider the tidal conditions in the region, the collision levels were varied from -3.5 m to 3.5 m of the mean sea level. In addition, the collision behaviors were evaluated as increasing the minimum collision energy at the collision speed (=2.6 m/s) of each vessel by four times, respectively. Accordingly, the plastic energy dissipation ratios of the vessel were increased as the stiffness of collision region. The deformations in the wind tower occurred from vibration to collapse of conditions. The tripod structure demonstrated more collision resistance than the jacket structure. This is considered to be due to the concentrated centralized rigidity and amount of steel utilized.

Speech Evaluation Tasks Related to Subthalamic Nucleus Deep Brain Stimulation in Idiopathic Parkinson's Disease: A Review (특발성 파킨슨병의 시상밑부핵 심부뇌자극술 관련 말 평가 과제에 대한 문헌연구)

  • Kim, Sun Woo;Kim, Hyang Hee
    • 재활복지
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    • v.18 no.4
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    • pp.237-255
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    • 2014
  • Idiopathic Parkinson disease(IPD) is an neurodegenerative disease caused by the loss of dopamine cells in the substantia nigra, a region of midbrain. Its major symptoms are muscular rigidity, bradykinesia, resting tremor, and postural instability. An estimated 70~90% of patients with IPD also have hypokinetic dysarthria. Subthalamic nucleus deep brain stimulation (STN-DBS) has been reported to be successful in relieving the core motor symptoms of IPD in the advanced stages of the disease. However, data on the effects of STN-DBS on speech performance are inconsistent. A medline literature search was done to retrieve articles published from 1987 to 2012. The results were narrowed down to focus on speech performance under STN-DBS based perceptual, acoustic, and/or aerodynamic analyses. Among the 32 publications which dealt with speech performance after STN-DBS indicated improvement(42%), deterioration(29%), mixed results(26%), or no change(3%). The most favorite method was found to be based upon acoustic analysis by using a vowel prolongation and Unified Parkinson's Disease Rating Scale(UPDRS). For the purpose of verifying the effect of the STN-DBS, speech evaluation should be undertaken on all speech components such as articulation, resonance, phonation, respiration, and prosody by using a contextual speech task.

Safety Factor of Rigid Sewer Pipe by Different Types of Foundation and Backfill (기초형식 및 뒤채움재 종류별 강성관용 하수관거의 안전율)

  • Lee, Kwan-Ho;Kim, Seong-Kyum
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.4
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    • pp.606-612
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    • 2019
  • The main causes of subsidence and sinkholes in the lower part of urban roads are sewage line foundation and inadequate compaction of backfill material. This leads to many problems, such as the breakage of joints in sewer pipes, poor connection, pipe breakage, and cracks. To solve this problem, the support factor related to the sewer foundation and the safety factor according to the excavation depth were evaluated. For the foundation of rigidity tolerance, crushed stone foundation, and abandoned concrete foundation, a recently newly developed site assembly-type lightweight plastic foundation were used. Backfill materials were applied on site (sandy soil and clayey soil) and fluid backfill was recycled onsite. To evaluate the depth of excavation and the safety factor of each sewer pipe foundation, the design load considering the load factor and the support factor was evaluated. The support coefficients were 0.377 for a crushed stone foundation, 0.243 and 0.220 for an abandoned concrete foundation ($180^{\circ}$ and $120^{\circ}$), and 0.231 for a lightweight plastic foundation and fluid backfill. Overall, the safety factor was low when using the crushed stone foundation, and the safety rate was the highest when the foreclosed concrete foundation ($180^{\circ}$) was used. In addition, when the combination of lightweight plastic and fluid backfill materials was used, the safety factor was higher than that of abandoned concrete foundation ($120^{\circ}$), which means that the newly developed lightweight plastic foundation can be used as another alternative base of a steel pipe.

Protective Effects of Quercetin-3-O-glucuronide against 1-methyl-4-phenylpyridinium-induced Neurotoxicity (1-methyl-4-phenylpyridinium으로 유도된 신경 손상에 대한 quercetin-3-O-glucuronide의 보호 효과)

  • Pariyar, Ramesh;Bastola, Tonking;Seo, Jungwon
    • Journal of Life Science
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    • v.29 no.2
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    • pp.191-197
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    • 2019
  • Parkinson's disease (PD) is a progressive neurodegenerative disease that mainly affects motor system with clinical features such as bradykinesia, rigidity, tremor and abnormal posture. PD is characterized by the death of dopaminergic neurons in the substantia nigra pars compacta, which is associated with accumulation of oxidative stress and dysregulation of intracellular signaling pathway. Quercetin-3-O-glucuronide (Q3GA), a major metabolite of quercetin, has been reported to have neuroprotective effects. In this study, we examined the neuroprotective effect of Q3GA against 1-methyl-4-phenyl pyridinium ($MPP^+$)-induced neurotoxicity of PD and the underlying molecular mechanisms in SH-SY5Y cells. MTT and LDH assay showed that Q3GA significantly decreased $MPP^+$-induced cell death, which is accompanied by a reduction in poly (ADP-ribose) polymerase (PARP) cleavage. Furthermore, it attenuated $MPP^+$-induced intracellular reactive oxygen species (ROS) with the reduction of Bax/ Bcl-2 ratio. Moreover, Q3GA significantly increased the phosphorylation of Akt and cAMP response element binding protein (CREB), but it has no effects on the phosphorylation of extracellular signal-regulated kinase (ERK). Taken together, these results demonstrate that Q3GA significantly attenuates $MPP^+$-induced neurotoxicity through ROS reduction and Akt/CREB signaling pathway in SH-SY5Y cells. Our findings suggest that Q3GA might be one of the potential candidates for the prevention and/or treatment of PD.