• 터널과지하공간
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• 제10권3호
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• pp.410-417
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• 2000

절리가 발달한 암반의 거동 특성을 효율적으로 모델링 할 수 있는 수치해석 방법으로서 널리 알려진 개별요소법은 서로 다튼 알고리즘에 기초하여 개발된 두 가지 형태의 수치해석 방법으로 발전해 왔다. 본 논문에서는 Plesha 등에 의해 개발된 implicit 알고리즘에 기초한 NURBM과 저자에 의해 개발된 explicit 알고리즘에 기초한 CBLOCK을 이용하여 불연속체 암반의 기초적인 거동 특성을 수치해석적으로 고찰하고 모델링상의 문제점들을 비교 분석하였다. CBLOCK 계산 결과에 의하면 절리의 수직 및 접선 강성비는 절리 분포에 따라 불연속체 암반의 안정성을 좌우하는 중요한 지수로서 사용될 수 있는 것으로 나타나고 있으나 NURBM 계산은 상이한 결과를 보였다. 또한 구조물의 안정성과 국부적인 파괴 거동의 해석에서 두 방법이 상이한 결과를 가져올 수 있는 것으로 나타났고 이는 수치해석적 모델링의 제약적 요소로 작용할 수 있음을 보여주었다.

• Journal of Korean Neurosurgical Society
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• 제56권3호
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• pp.206-210
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• 2014

Objective : Lumbar spinal stenosis is a common degenerative spine disease that requires surgical intervention. Currently, there is interest in minimally invasive surgery and various technical modifications of decompressive lumbar laminectomy without fusion. The purpose of this study was to present the author's surgical technique and results for decompression of spinal stenosis. Methods : The author performed surgery in 57 patients with lumbar spinal stenosis between 2006 and 2010. Data were gathered retrospectively via outpatient interviews and telephone questionnaires. The operation used in this study was named central decompressive laminoplasty (CDL), which allows thorough decompression of the lumbar spinal canal and proximal two foraminal nerve roots by undercutting the lamina and facet joint. Kyphotic prone positioning on elevated curvature of the frame or occasional use of an interlaminar spreader enables sufficient interlaminar working space. Pain was measured with a visual analogue scale (VAS). Surgical outcome was analyzed with the Oswestry Disability Index (ODI). Data were analyzed preoperatively and six months postoperatively. Results : The interlaminar window provided by this technique allowed for unhindered access to the central canal, lateral recess, and upper/lower foraminal zone, with near-total sparing of the facet joint. The VAS scores and ODI were significantly improved at six-month follow-up compared to preoperative levels (p<0.001, respectively). Excellent pain relief (>75% of initial VAS score) of back/buttock and leg was observed in 75.0% and 76.2% of patients, respectively. Conclusion : CDL is easily applied, allows good field visualization and decompression, maintains stability by sparing ligament and bony structures, and shows excellent early surgical results.

• Journal of Oral Medicine and Pain
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• 제48권3호
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• pp.123-130
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• 2023

This case report describes the orthodontic treatment of a patient with severe anterior open bite and skeletal class II malocclusion with temporomandibular joint (TMJ) osteoarthritis (OA) of the left condyle. The 21-year-old male patient had open-bite malocclusion, mild crowding, and protrusion of the anterior teeth. Mild erosive changes were detected in the anterior part of the left mandibular condyle on cone-beam computed tomography; however, because no clinical symptoms were present, orthodontic treatment was performed. It is imperative to consider the potential implications of orthodontic treatment on the stability of the TMJ throughout the duration of treatment, as any instability can exacerbate TMJ OA. Hence, it is crucial to opt for the least invasive treatment modality available. In this regard, orthodontic treatment using a skeletal anchorage system as an alternative to conventional orthognathic surgery for patients with open bite holds great promise, as it not only ensures mandibular stability but also significantly ameliorates the open-bite condition.

• 자원환경지질
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• 제33권1호
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• pp.51-59
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• 2000

As a part of natural hazard assessment, regional slope stability analysis was conducted using Geoscientific Information System (GIS) in the northern area of Chungju Lake. Selected factors which affect the slope stability in the study area were lithology, soil, density of lineament, groundwater level, dip of slope, aspect of slope, and geological engineering properties. Geological structural domains were determined by collected data of joint orientation from about 200 sites in order to produce a slope instability map. Potential type of failure and its direction could be expected through the domains. And a slope instability map was produced, comparing the representative orientations of the domains with the orientations of the slopes which were made through TIN module in ARC/INFO. Under the consideration of environmental geological characteristics of the study area, rating and weighting of each factor of slope stability analysis were decided and spatial analysis of regional slope stability was couducted through overlaying technique of GIS. The result of areal distribution of slope stability showed that the most unstable area was the area between Mt. Pudae and Mt. Jubong, and the northern area of the railway station, Samtan.

• 터널과지하공간
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• 제11권2호
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• pp.109-119
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• 2001

우리나라의 양수발전소는 지금까지 단일공동을 굴착하였다. 그러나 양양 양수발전소는 두 개의 대공동 즉, 발전소와 주 변전소로 구성된다. 이 경우 공동 구조물의 안정성, 특히 두 공동사이에 형성되는 암주를 영구적으로 안전하게 유지할 수 있도록 보장되어야 한다. 본 연구에서는 개별요소법을 이용하여 두 공동과 암주의 구조적 안정성을 평가하였으며, 구성모델로 Barton-Bandis의 절리모델을 이용하였다. 현지 암반의 초기응력, 자연절리면의 거칠기계수, 불연속면의 공간적 분포 특성과 같은 중요한 요인들은 현지 조사를 통하여 구하였다. 이외에 두가지 경우 즉, 무보강과 보강의 경우 지보시스템의 최적화를 분석하였으며, 또한 보강효과를 검토하였다. 연구결과 보강의 경우 수평변위와 절리의 전단변위가 감소되었으며 암주내 이완영역 역시 감소됨을 확인하였다. 두 공동사이에 있는 약 36 m 두께의 암주에 적절한 보강조치를 취하여 안정성을 확보할 수 있었다.

• Structural Engineering and Mechanics
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• 제11권5호
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• pp.565-574
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• 2001

Experimental investigation into the behaviour of half-scale brick masonry panels were conducted under cyclic loading normal to the bed joint and parallel to the bed joint. For each cycle, full reloading was performed with the cycle peaks coinciding approximately with the envelope curve. Unloading, however, was carried out fully to zero stress level and partially to two different stress levels of 25 percent and 50 percent of peak stress. Stability point limit exhibits a unique stress-strain curve for full unloading but it could not be established for partial unloading. Common point limit was established for all unloading-reloading patterns considered, but its location depends on the stress level at which unloading is carried to. Common point curves were found to follow an exponential formula, while residual strains versus envelope strains can be expressed by a polynomial function of a single term. The relation between residual strain and envelope strain can be used to determine the stress level at which deterioration due to cyclic loading began.

• 산업기술연구
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• 제21권B호
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• pp.51-58
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• 2001

The Distinct Element Method (DEM) was used to analyze the stability of jointed rock slope, of which dimension are about 200m(length), 60m(height), $55^{\circ}$ dip. The Barton-Bandis joint model was used, as a constitutive model. The parameters such as JRC and spatial distribution characteristics of discontinuities were acquired through field investigation. Three different cases such as $51^{\circ}$, $45^{\circ}$ and $38^{\circ}$ in angle of rock slope were analyzed to decide a stable slope. To keep the jointed rock slope safely, it is proposed to reduce the height of slope from 60m to 48m and to reduce the angle of the from $55^{\circ}$ to $38^{\circ}$ too.

• 한국기계가공학회지
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• 제10권4호
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• pp.50-56
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• 2011

Injection molding process is one of the popular manufacturing methods to produce plastic parts with high efficiency and low cost. Ball seat for automobile suspension is made by an injection molding process as a part to support pivot function of ball joint consisted of ball stud and housing. It is necessary for a ball seat to have a dimensional stability in the three dimensional inner area to be contacted with ball stud. In this paper, the dimensional stability of inner surface is indirectly analyzed by checking the difference of inner diameter around the circumferential direction and the thickness variation at the top part of ball seat. Measurement was performed by using the coordinate measuring machine and the fixture to hold ball seat. Optimization of injection molding processes such as injection time, cooling time and temperatures of cylinder barrel was derived to reduce the difference of inner diameter and the thickness variation at the top part of ball seat based on the Taguchi method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2132-2137
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• 2005

This paper is concerned with computer simulations of a biped robot walking in dynamic gaits. To this end, a three-dimensional robot is considered possessing a torso and two identical legs of a kinematically ingenious design. Specific walking patterns are off-line generated meeting stability based on the ZMP condition. Subsequently, to verify whether the robot can walk as planned, a multi-body dynamics CAE code has been applied to the corresponding joint motions determined by inverse kinematics. In this manner, complex mass effects could be accurately evaluated for the robot model. As a result, key parameters to successful gaits are identified including inherent characteristics as well. Also, joint actuator capacities are found required to carry out those gaits.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.781-787
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• 2004

Where the track is continuously welded over a bridge, the longitudinal force is interacted between the track and the sub-structure. Due to this respect, the expansion joint is used to decrease this force. But the expansion joint has several problems related to passenger comfort and maintenance etc. In this study, it is analysed about how the stability of the track is affected as the span length becomes longer in case of 2-span continuos bridge. It is found that there is no problem of an stability unless the span length is longer than 90m when the elastic shoe is used. And several parametric studies were also implemented.