• 상하수도학회지
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• 제21권2호
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• pp.151-164
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• 2007

Criteria for rehabilitation priority are discussed to evaluate structural stability of deteriorated water transport and transmission pipes, in this study. For the purposes, safety factor is introduced and estimated by measuring tensile strength and by analyzing stress caused by the internal-external loads working on buried pipe body. Related informations are surveyed and collected under various conditions in the fields by digging out and the structural stability is assessed. In the evaluation results of structural safety, it is shown that steel pipe is more affected by external load than internal load. The average external load is estimated as $53.7kg/cm^2$ and total hoop stress is estimated by $2676.5kg/cm^2$. Also, Poisson effect into longitudinal direction due to internal and external loads is most influential on hoop stress. The calculated safety factors of hoop stress are ranged from 0.7 to 5.2 with average value of 2.1, considering a bending stress to longitudinal direction. The decision of rehabilitation priority by safety factors show that structural safety of CIP sample 1(S1) was assessed at the lowest order with safety factor value, 0.7 and that of DI sample 15(S15) was evaluated as the most stable in structural aspect.

• 한국방재학회 논문집
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• 제8권5호
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• pp.147-153
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• 2008

저수호안에 작용하는 외력들 중에서 유수에 의한 소류력과 항행하는 선박에 의한 항주파는 호안의 안정성에 가장 큰 영향을 미칠 수 있는 항목들이다. 본 연구에서는 이러한 외력들에 대해 호안의 안정성을 분석하였다. 분석대상지역은 서울시의 한강인공호안을 생태녹지공간으로 조성하는 시험시공구간이다. RMA-2모형을 이용하여 계산된 유속을 사용하여 소류력을 산정하고, 안정성은 대상구간에 대해 계산한 계산소류력과 호안재료의 허용소류력을 비교하여 분석하였다. 분석결과 측점 93의 200년빈도 계산소류력이 허용소류력을 초과하여 이 지점은 수리적안정성이 확보되지 않는 지점으로 판단할 수 있었다. 2007년 8월 10일의 강우에 대해서는 전구간에서 계산소류력이 허용소류력보다 작게 모의되었다. 따라서 소류력에 대해서는 안정하다고 판단할 수 있으나 부분적으로 호안이 침수된 부분에 세굴이 발생한 이유는 시공후 식생이 활착할 시간이 부족한 상태에서 작은 소류력에 대해서도 세굴이 발생하였으며, 항주파 등의 다른 외력과 중첩되어 발생하였다고 생각된다. 한강을 운행하는 한강유람선과 수상택시에 의해 발생하는 항주파를 계산하였으며 이를 이용하여 호안에 미치는 파력을 산정하여 호안재료에 따른 지지력과 비교하였다. 그 결과 한강을 운항하는 선박들이 호안에 미치는 외력은 허용지지력보다 매우 작은 값으로 판단되므로 호안은 항주파에 대해서는 안정하다고 판단할 수 있으나 소류력 등의 다른 외력과 동시에 작용할 경우소류력 등의 다른 외력과 동시에 작용할 경우에는 복합적인 외력을 고려해야 할 것이다.

• 한국농공학회논문집
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• 제56권6호
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• pp.75-84
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• 2014

This study aims to develop the program for design of a reinforced earth retaining wall. For this purpose, the external stability such as overturning, sliding and bearing capacity and the internal stability such as pull-out failure and tensile rupture of the reinforced earth retaining wall with the reinforcement spacing and the backfill inclination were examined. In addition, the calculated results from the developed program were verified by comparing with the simulated results based on the three-dimensional finite element analysis. It is expected that this program contributes to effective design of the reinforced earth retaining wall.

• 대한치과보철학회지
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• 제42권1호
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• pp.83-93
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• 2004

Statement of problem : Since the concept of osseointegrated dental implant by $Br{\aa}nemark$ et al was first applied to mandibular full edentulous patients. Recently it is considerated the first treatment option on missing teeth. A common problem associated with dental implant restorations is loosening of screws that retain the prosthesis to the abutment and the abutment to the implant fixture. Purpose : This study is to examine the influence on screw loosening of implant-abutment designs. Material and methods : External hex, cone screw, beveled hex, cam cylinder, cylinder hex by means of evaluating the loosening torques, with respect to a range of tightening torques after repeated loading. Result : 1. Cone screw, beveled hex groups are the highest initial tightening rate and cylinder hex, external hex groups are the lowest initial tightening rate (p < 0.05). 2. Cone screw groups are the highest after repeated loading tightening rate and cylinder hex groups are lowest after repeated loading tightening rate(p < 0.05). 3. Cone screw groups have the highest initial stability and anal stability. 4. All groups are decreased tightening rate after repeated loading.

• 천문학회지
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• 제37권4호
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• pp.249-255
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• 2004

Here we present a linear stability analysis and an MHD 2D model for the Parker-Jeans instability in the Galactic gaseous disk. The magnetic field is assumed parallel to a Galactic spiral arm, and the gaseous disk is modelled as a multi-component, magnetized, and isothermal gas layer. The model employs the observed vertical stratifications for the gas density and the gravitational acceleration in the Solar neighborhood, and the self-gravity of the gas is also included. By solving Poisson's equation for the gas density stratification, we determine the vertical acceleration due to self-gravity as a function of z. Subtracting it from the observed gravitational acceleration, we separate the total acceleration into self and external gravities. The linear stability analysis provides the corresponding dispersion relations. The time and length scales of the fastest growing mode of the Parker-Jeans instability are about 40 Myr and 3.3 kpc, respectively. In order to confirm the linear stability analysis, we have performed two-dimensional MHD simulations. These show that the Parker-Jeans instability under the self and external gravities evolves into a quasi-equilibrium state, creating condensations on the northern and southern sides of the plane, in an alternate manner.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2001년도 춘계학술대회 논문집
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• pp.254-259
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• 2001

There are advantages in the installation of dual subsea pipelines over two separate single lines. In many case it can reduce the cost for trench, back-filling and installation. However the installation of dual pipelines often requires technical challenges. Dual Pipelines should be placed to be stable to external loading not only during the installation but also in the design life. Dual pipelines in trench can reduce the influence of external forces. To investigate applied forces as slope changes, number of experiments are conducted with PIV (Particle Image Velocimetry) in a circulating water channel. Numerical approaches are also made to compare with experimental results. The velocity fields around dual pipelines in trench are investigated and analysed. Comparison of both results show similar pattern of flow around dual pipelines. it is proved that the trench slope affects the pipeline stability significantly. The results can be applied in the stability design of dual pipelines in trench section. The complex flow patterns can be referenced effectively linked in the understanding of fluid around circular bodies in trench.

• 한국전문물리치료학회지
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• 제27권4호
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• pp.257-263
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• 2020

Background: The hip muscle plays various roles. Several types of functional performance tests are used for the assessment of patients with various lower extremity injuries. Hip muscle functions are important to test the performance of maintaining the spine, pelvic, and leg during bridging exercise. We designed a novel functional performance test tool, which we named close kinetic chain dynamic lower extremity stability (CKCLE) test to assess hip muscle functions. Objects: The purpose of this study was to determine the relationship between CKCLE test and hip extensor, external rotator, and abductor strengths. Methods: Twenty-two subjects were recruited in the present study (13 males and 9 females). The hip extensor, external rotator, and abductor muscle strengths were measured using a Smart KEMA strength sensor. When the examiner said "Go", the subject performed the CKCLE test by moving one leg from the floor and touching the opposite knee and then return to the floor while maintaining the bridging position. The subjects attempted as many "touches" as possible in the allotted time (20 seconds) during the maximal tests. The correlation between the hip muscle (extensor, external rotator, and abductor) strength of the supporting leg and the number of CKCLE tests performed in 20 seconds was determined using the Pearson correlation. Results: Hip extensor (r = 0.626, p < 0.05), hip external rotator (r = 0.616, p < 0.05), and hip abductor muscle strengths (r = 0.475, p < 0.05) positively correlated with the number of CKCLE tests performed. Conclusion: We designed a CKCLE test and found that performance in the test correlated with hip extensor, external rotator, and abductor muscle strengths. The result suggests that the CKCLE test can be applied as a performance test to assess the functions of the hip extensor, external rotator, and hip abductor muscles.

• 대한구순구개열학회지
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• 제16권1호
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• pp.9-18
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• 2013

Distraction osteogenesis is useful treatment which the gradual separation of cut bone edges results in the generation of new bone. It is effective treatment for correcting maxillofacial deformities. Patients with cleft lip and palate usually have maxillary hypoplasia due to scarring of lip and palate. To correct these deformities, we chose to use a 2-jaw orthognathic surgery or distraction osteogenesis. But despite improvements in surgical techniques for maxillofacial deformities, postoperative stability still leaves the question of when relapse may occur. This case report describes the Relapse after treatment of maxillary hypoplasia with cleft lip and palate by Rigid External distraction system over a 2-year treatment and follow-up period. In addition, we reviewed related articles about the influence of the occlusal stability on postoperative stability in patients with cleft lip and palate correction with Distraction osteogenesis.

• 대한물리의학회지
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• 제10권4호
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• pp.33-38
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• 2015

PURPOSE: Although the abdominal drawing-in maneuver is commonly used in clinical training for trunk stability, performing this procedure in stroke patients is difficult; instead, maximal expiration can be much easily performed in stroke patients. In the present study, we first aimed to demonstrate the effects of the abdominal drawing-in maneuver and maximal expiration on trunk stability in stroke patients. Moreover, we compared the thickness of the transverse abdominal, internal oblique, and external oblique muscles on the paretic and non-paretic sides. METHODS: We used ultrasonography to measure the change in the thickness of the transverse abdominal, internal oblique, and external oblique muscles on the paretic and non-paretic sides at rest, while performing the abdominal drawing-in maneuver, and while performing maximal expiration in 23 stroke patients. The ratio of muscle thickness between different conditions was estimated and included in the data analysis (abdominal drawing-in maneuver / at rest and, maximal expiration / at rest). RESULTS: The ratio of the thickness of the transverse abdominal, internal oblique and external oblique muscles during maximal expiration was significantly different on the paretic side (p < 0.05). The ratio of muscle thicknesses on the non-paretic side was greater during maximal expiration than during the abdominal drawing-in maneuver, although this difference was not significant (p > 0.05). CONCLUSION: Our results suggest that maximal expiration more effectively increased the abdominal muscle thickness on the paretic side. Hence, we recommend the application of maximal expiration in clinical trunk stability training on the paretic side of stroke patients.

• 제어로봇시스템학회논문지
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• 제15권11호
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• pp.1071-1075
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• 2009

This article describes a robust control method by using peak control of a sensitivity function in the state-feedback control systems. This method apparently reduces the peak, and as a result makes closed loop systems more stable. The designed closed loop systems also make the response to an external step disturbance more fast with a lower undershoot. At the conclusion, it is verified that the proposed method enhances robust stability and robust performance to parametric uncertainties through $\mu$-plot.