• 건설안전기술
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• 통권47호
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• pp.56-62
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• 2008

In order to apply the Limit Equilibrium Method generally used for the slope stability analysis to the vertical excavation walls reinforced by soil-nailing, in this study, the Limit Equilibrium Method for the temporary shoring facilities reinforced by soil-nailing was proposed, which is based on the stability for the horizontal displacement. In this study, the relation of the internal friction angles of the ground and the vertical excavation depths was arranged, which is satisfying the stability on the horizontal displacement by using the verification of the Limit Equilibrium Method. And then, the rational reinforcing length of soil-nailing was proposed for the critical areas. In addition, the modified safety ratio satisfying the stability on the horizontal displacement was proposed, when the Limit Equilibrium Method was applied to the vertical excavation walls reinforced by soil-nailing.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제31권5호
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• pp.422-426
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• 2005

Purpose : The purpose of this study was to investigate the vertical stability after BSSRO surgery in skeletal class III malocclusion patients with mild anterior open bite and to present a method to increase the stability. Materials and methods : 36 patients, 11 male and 25 female, who received BSSRO surgery with the diagnosis of skeletal class III with anterior open bite at the Department of Oral and Maxillofacial Surgery in Samsung Medical Center, from January 2002 to August 2003, were selected for this study. The patients were between 18 to 45 years of age. Preoperative and postoperative (immediate, 6 months, and 1 year after operation) lateral cephalograms were compared to evaluate the vertical stability by measuring the distance of nasion-menton, mandibular plane angle, and overbite. Results : The nasion-menton distance decreased by 1.65mm immediately after the operation in comparison to the preoperative value. This distance further decreased by 0.60 mm at 6 months and 1.06mm at 1 year after the operation. The mandibular plane angle increased after the operation and further increased at 6 months and 1 year. The amount of overbite increased by the operation was 2.34mm and an additional increase of 0.70mm at 6 months and 0.94mm at 1 year were shown. Conclusion : Clinically, none of the patients showed relapse of anterior open bite and the vertical stability is highly influenced by orthodontic treatment after the operation. In this study, BSSRO surgery is considered to be a rather reliable procedure that restores stability to skeletal class III malocclusion patients with slight anterior open bite.

• 대한기계학회논문집A
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• 제27권10호
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• pp.1728-1737
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• 2003

The vertical lathe is a very popular machine tool in modem manufacturing industries because of its small area of installation. The small installation area is highly desirable for the flexibility improvement of the manufacturing systems such as FMS, CIM, and IMS. The vertical lathe, however, has much taller height compared to the traditional horizontal lathe, and consequently more severe vibrations. In this study, the structure of a vertical lathe is analyzed to investigate the dynamic properties and further to establish some ideas of the design alteration for the improved dynamic stability even at the higher operating speed. The simulation model is implemented to apply those design alterations for the optimization. The result of this study is not only prosperous but also ready to be applied to the optimum design of various machine tool structures for the improved stability.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2007년 추계학술발표대회 개요집
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• pp.36-38
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• 2007

The instability of the arc in the $CO_2$ arc welding affects the quality of the weld in the automotive industry. This paper evaluates the effects of the arc stability in $CO_2$ arc welding with respect to vertical welding positions. In this experiment, galva-annealed steel sheets(CA) were used as specimens, and these materials were welded by adopting new Cold Metal Transfer (CMT) process. For each sample, fillet joint welding trials were carried out using the same conditions. Each part of welding joints was welded with vertical-up, vertical-down position at $45^{\circ},\;90^{\circ}\;and\;135^{\circ}$ degrees. A high speed camera and a welding signal monitoring system were used for monitoring fluid-flow phenomena in weld pools and frequency measurements, respectively. Through this study, the welding position were found to be key factors mainly to influence the arc stability in $CO_2$ welding moreover and that the arc stability in the vertical-up welding position was observed to be more stable than the vertical-down welding position below $90^{\circ}$.

• 한국항공우주학회지
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• 제31권6호
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• pp.45-51
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• 2003

본 논문에서는 소형 커나드 항공기인 Velocity-173의 가로안정성을 향상시키기 위한 방법에 대하여 연구하였다. Velocity-173의 세로안정성은 매우 우수한 반면, 가로안정성은 상대적으로 나쁘다. 가로안정성을 향상시키기 위해 수직미익의 면적을 증가시키는 작은 패널을 설계 및 제작하였다. 패널 설계 과정에서 AAA를 이용하여 패널 부착으로 인한 가로안정성의 변화를 예측하였다. 패널 부착 효과를 검증하기 위해 비행시험이 수행되었다. 또한, 비행시험 데이터로부터 안정/조종 미계수를 추출하기 위하여 최대공산추정법을 이용하였다. 본 연구를 통해 수직미익 아래에 부착된 패널의 효과를 확인할 수 있었다.

• 산업기술연구
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• 제24권A호
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• pp.139-155
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• 2004

A room and pillar mining method has been adopting at the Jeungsun limestone mine. To check stability of pillar with multiple and irregular openings, the size, shape and spacing of rib pillar were first designed using some empirical suggestions. The Finite Difference Method(FDM)was used to analyze the pillar stability. Twelve different cases with the variation of K(horizontal/vertical stress)values, different height and different spacing of pillar were used in this study. Finally Mohr-Coulomb criterion was adopted to calculate the safety factors. Horizontal and vertical displacement, maximum and minimum principal stresses, range of plastic zone and safety factors were calculated at each case. As a result of analysis, the size of one block is 160m long, 70m wide, 40m high with 20m wide rib pillar and 20m square column pillar. The overall recovery at this case can be estimated about 40%.

• 한국해양학회지
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• 제10권2호
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• pp.57-66
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• 1975

Structure of thermocline, characteristics of stability and intensity of vertical transfer have been studied with hourly oceanographic data in each layers on Line 207 from 1968 to 1969. It is found that a typical thermocline is formed at depths of 10 to 50 meters in summer and early autumn and its core is located near depths of 25 meters. The maximum diffusion coefficient of vertical turbulent is found to be 140$\textrm{cm}^2$/sec at the surface layer(i.e., 0-10 meters), while the minimum is 5$\textrm{cm}^2$/sec at depths of 25 meters, consistent with characteristics of stability and structure of thermocline layers. Our computed diffusion coefficient and stability indicate that the mixing hardly takes place below depths of 80 meters during summer and early autumn, but for the rest of the season mixing could move up to the depth of 50 meters. It appears that the Western Channel of the Korea Strait consist of three different water masses during summer and autumn, and for the rest of the season, two kinds are present.

• 한국소음진동공학회논문집
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• 제12권12호
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• pp.979-985
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• 2002

The paper presents the dynamic stability of a vertical cantilevered pipe conveying fluid and haying translational linear spring supports. Real pipe systems may have some elastic hanger supports or other mechanical attached parts. which can be regarded as attached spring supports. Governing equations are derived by energy expressions, and numerical technique using Galerkin's method is applied to the equations of small motion of the pipe. Effects of spring supports on the dynamic stability of a vortical cantilevered pipe conveying fluid are fully investigated for various locations and spring constants of elastic supports.

• 한국운동역학회지
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• 제28권2호
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• pp.135-141
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• 2018

Objective: The purpose of this study was to investigate the effect of functional ankle instability (FAI) and surgical treatment (ST) on postural stability and leg stiffness during vertical-drop landing. Method: A total of 21 men participated in this study (normal [NOR]: 7, FAI: 7, ST: 7). We estimated dimensionless leg stiffness as the ratio of the peak vertical ground reaction force and the change in stance-phase leg length. Leg length was calculated as the distance from the center of the pelvis to the center of pressure under the foot. Furthermore, the analyzed variables included the loading rate and the dynamic postural stability index (DPSI; medial-lateral [ML], anterior-posterior [AP], and vertical [V]) in the initial contact phase. Results: The dimensionless leg stiffness in the FAI group was higher than that of the NOR group and the ST group (p = .018). This result may be due to a smaller change in stance-phase leg length (p = .001). DPSI (ML, AP, and V) and loading rate did not show differences according to the types of ankle instability during drop landing (p > .05). Conclusion: This study suggested that the dimensionless leg stiffness was within the normal range in the ST group, whereas it was increased by the stiffness of the legs rather than the peak vertical force during vertical-drop landing in the FAI group. Identifying these potential differences may enable clinicians to assess ankle instability and design rehabilitation protocols specific for the impairment.

• Journal of Radiation Protection and Research
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• 제41권3호
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• pp.260-267
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• 2016

Background: This study analyzes the differences in the annual averaged atmospheric dispersion factor and ground deposition factor produced using two classification methods of atmospheric stability, which are based on a vertical temperature difference and the standard deviation of horizontal wind direction fluctuation. Materials and Methods: Daedeok and Wolsong nuclear sites were chosen for an assessment, and the meteorological data at 10 m were applied to the evaluation of atmospheric stability. The XOQDOQ software program was used to calculate atmospheric dispersion factors and ground deposition factors. The calculated distances were chosen at 400 m, 800 m, 1,200 m, 1,600 m, 2,400 m, and 3,200 m away from the radioactive material release points. Results and Discussion: All of the atmospheric dispersion factors generated using the atmospheric stability based on the vertical temperature difference were shown to be higher than those from the standard deviation of horizontal wind direction fluctuation. On the other hand, the ground deposition factors were shown to be same regardless of the classification method, as they were based on the graph obtained from empirical data presented in the Nuclear Regulatory Commission's Regulatory Guide 1.111, which is unrelated to the atmospheric stability for the ground level release. Conclusion: These results are based on the meteorological data collected over the course of one year at the specified sites; however, the classification method of atmospheric stability using the vertical temperature difference is expected to be more conservative.