• Tunnel and Underground Space
• /
• v.22 no.5
• /
• pp.297-309
• /
• 2012

The stability assessment of abandoned gangway for the purpose of services was performed. Among the many factors that affect the stability of openings, the span of the opening in a given rock mass condition provides an important element of design. In this paper, the stability of gangway was assessed by the critical span curves proposed by Lang, the modified Mathews'stability graph method and using support measures of the Q system. In the evaluation of stability as a whole the gangway is considered as stable. But the rockfalls of wedge-shaped blocks were expected in the area in which the horizontal joints of low angle appear. The support measures such as local rock bolts are required to use for commercial purposes of the abandoned gangway. And entrance section may require the particular attention as unstable section. Since there are so many spalling due to bad blasting in the roof and sidewall of gangway, the scaling operations should be followed primarily.

• Journal of the Korean Geotechnical Society
• /
• v.20 no.9
• /
• pp.91-103
• /
• 2004

A series of shaking table model tests were performed to verify the validity of similitude law, which is suggested by lai (1989) to simulate the dynamic behavior of soil-fluid-structure system for is shaking table tests. In the tests, the similitude law suggested by lai was applied to determine the length and the time scaling factors. Also, the steady state concept was used in determining the density of model backfill soil, which is a key factor in simulating the development of excess pore pressure during shaking. The similitude law was verified by checking whether three different sizes of quay walls show the identical behavior or not. The similar responses of acceleration, excess pore pressure and horizontal displacement of walls were obtained far the small and large models. However, the medium model showed larger responses than those of the small and large models because of the resonance between the frequency of input acceleration and the natural frequency of the wall system. In addition, the vertical displacement and rotational angle of the walls became larger with the increase of model size.

• Journal of Periodontal and Implant Science
• /
• v.48 no.6
• /
• pp.395-404
• /
• 2018

Purpose: The purpose of this study was to propose a technique for periodontal biotype modification through thickening of the entire facial aspect using a volume-stable collagen matrix and autogenous subepithelial connective tissue graft (CTG) for the treatment of gingival recession. Methods: Four systemically healthy patients showing Miller class I or class II gingival recession in the mandibular incisor area were included in this study. Full-mouth scaling and root planing procedures were performed at least 4 weeks prior to periodontal plastic surgery. A split-thickness flap with a horizontal intrasulcular incision and 2 vertical incisions was used in cases 1-3, and the modified tunnel technique was used in case 4 for coronal advancement of the mucogingival complex. After the exposed root surfaces were debrided thoroughly, double-layered volume-stable collagen matrix was placed on the apical part of the recession and a subepithelial CTG harvested from the palatal area was placed on the coronal part. The amount of root coverage at 3 months postoperatively was evaluated in cases 1-3, and facio-lingual volumetric changes were analyzed in cases 1 and 2. Results: Healing was uneventful in all 4 cases and complete root coverage was shown in cases 1-3. In case 4, reduction of gingival recession was observed at 3 months after surgery. In cases 1 and 2, a comparison of stereolithographic files from the preoperative and postoperative time points demonstrated that the entire facio-lingual volume had increased. Conclusions: The surgical technique suggested herein, using a volume-stable collagen matrix and autogenous subepithelial CTG, may be an effective method for periodontal biotype modification through thickening of the entire facial aspect for the treatment of gingival recession.

• Journal of the Korean Geotechnical Society
• /
• v.22 no.1
• /
• pp.53-61
• /
• 2006

Soil liquefaction occurs by complex dynamic interaction between soil particles and pore fluid. Therefore, experimental researches have been widely performed to analyze liquefaction phenomena. In this research, centrifuge tests were performed to analyze the liquefaction behavior of horizontal sand ground. Centrifugal acceleration was 40g and the thickness of model ground was 25cm, which simulates 10m thickness in prototype scale. Viscous fluid was used as pore fluid to remove the time scaling difference between dissipation and dynamic shaking. Test results showed that the dissipation of excess pore pressure is the combined behavior of solidification and consolidation. In addition, the solidification rate, the ground acceleration amplitude, and the dynamic permeability during solidification were influenced by the confining pressure.

• Wind and Structures
• /
• v.34 no.2
• /
• pp.231-257
• /
• 2022

Transmission lines systems are important components of the electrical power infrastructure. However, these systems are vulnerable to damage from high wind events such as hurricanes. This study presents the results from a 1:50 scale aeroelastic model of a multi-span transmission lines system subjected to simulated hurricane winds. The transmission lines system considered in this study consists of three lattice towers, four spans of conductors and two end-frames. The aeroelastic tests were conducted at the NSF NHERI Wall of Wind Experimental Facility (WOW EF) at the Florida International University (FIU). A horizontal distortion scaling technique was used in order to fit the entire model on the WOW turntable. The system was tested at various wind speeds ranging from 35 m/s to 78 m/s (equivalent full-scale speeds) for varying wind directions. A system identification (SID) technique was used to evaluate experimental-based along-wind aerodynamic damping coefficients and compare with their theoretical counterparts. Comparisons were done for two aeroelastic models: (i) a self-supported lattice tower, and (ii) a multi-span transmission lines system. A buffeting analysis was conducted to estimate the response of the conductors and compare it to measured experimental values. The responses of the single lattice tower and the multi-span transmission lines system were compared. The coupling effects seem to drastically change the aerodynamic damping of the system, compared to the single lattice tower case. The estimation of the drag forces on the conductors are in good agreement with their experimental counterparts. The incorporation of the change in turbulence intensity along the height of the towers appears to better estimate the response of the transmission tower, in comparison with previous methods which assumed constant turbulence intensity. Dynamic amplification factors and gust effect factors were computed, and comparisons were made with code specific values. The resonance contribution is shown to reach a maximum of 18% and 30% of the peak response of the stand-alone tower and entire system, respectively.

• Journal of dental hygiene science
• /
• v.7 no.3
• /
• pp.141-146
• /
• 2007

A questionnaire survey of patients for practical training of dental hygiene department of E college was conducted from August 28th 2006 to December 8th 2006. Before scaling, the purpose of the study and the questionnaires were fully explained and the patients were requested to complete the questions personally. The survey were conducted under their consent and 256 copies were collected and used for the analysis. The survey shows the patients' habit for oral health care according to the gender and age and their standards for the quality of life. 1. For gender, male occupied 117(45.7%) and female occupied 139(54.3%). For age, 158 of the patients were in their twenties(61.7%) and 60 of them were aged from 10 to 19(23,4%). 16 patients were aged from 40 to 49(6.3%) and 11 patients were aged from 30 to 39(4.3%) and the number of patients who are older than 50 was 11(4.3%). 2. For the mouth health care, according to gender, 37.6% of male answered that they had scaling and 46.8% of female patients answered that they had scaling experiences. Without distinction of gender, most patients answered they brushed their teeth twice a day. For 91.5% of male patients and 89.9% of female patients answered that they brushed their teeth after meals. Also, 41% of male patients and 53.2% of female patients use rolling method. For using mouth aids, 68.4% of male patients and 65.5% of female patients do not use any aids. 3. For brushing way, most teenagers and patients in their twenties use rolling method and patients older than thirty use vertical and horizontal method. The frequency of brushing shows that most of the respondents brush their teeth twice a day after meals. 4. The standard of quality of life according to gender, under 'clear pronunciation' head, male patients mark 4.42 points and female patients mark 4.17 points. Under 'every day going out' head, male patients mark 4.53 points and female patients mark 4.29 points. Under 'maintenance of emotion' male patients mark 4.27 points and female patients mark 4.27 points. 5. The standard of quality of life according to age, teenage patients show 4.28 points under 'having meals' and under 'clear pronunciation' head, patients in their forties mark 4.44 points. Under 'keeping teeth or denture clean' head, patients in their thirties mark 4.55 points. Patients in their fifties show the lowest grades in most questionnaires.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.38 no.2
• /
• pp.53-63
• /
• 2010

It constitutes a very important preliminary step to analyze how city image is assessed in order to determine the direction towards a desirable city image in planning on an urban landscape for future city image. This study aims to quantify the recognition and evaluation of a city image on the part of citizens, using multidimensional scaling and correspondence analysis. Furthermore, this study hopes to contribute to the quantified policy-making for improving city image by understanding how professionals and civil servants in the related field tend to recognize such image. The results from the study are as follow: 1. The image of Daejon City tends to be assessed strongly in the light of its history, dynamics, and size. While the City is recognized as new and changing in general, the civil servants consider the city as modest, and the professionals as mediocre. Therefore, the City should strive to conceive its own unique identity, which would lessen the current image of modest and mediocre. 2. Gap river, Dunsan New Town, and the Daeduk Reseach Complex turn out to be the symbolic representative venues of Daejon City, inspiring the city’s image. In contrast, Yoosung Springs, the original town, and the Expo Park do not fit the image of the City. The need to renovate these places presents itself. 3. As for the questions using “like” and “not-like”, citizens and professionals show the tendency of not liking the city’s image, whereas civil servants like it. It follows that the City needs to highlight its “modern and high-technological” image, illuminated by Dunsan New Town and Daeduk Reseach Complex. 4. An image positioning drawn from a correspondence analysis shows that the City of Daejeon can be classified as an administrative and horizontal city. As opposed to the prior simplistic analyses of city image, this study attempts to diagnose it accurately, so as to help with the gearing towards city images in the future.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.16 no.1
• /
• pp.1-12
• /
• 2012

In this paper, the reduction factors to calculate the site coefficients of an embedded foundation are estimated, considering the effect of a poor backfill for the seismic design of a building built on an embedded foundation. This is determined by utilizing in-house finite element software, P3DASS, which has the capability of horizontal pseudo 3D seismic analysis with nonlinear soil. The 30m thick soil on stiff rock was assumed to be homogeneous, elastic, viscous and isotropic, and equivalent circular rigid foundations with radii of 10-70m were assumed to be embedded 0, 10, 20, and 30 m in the soil. Seismic analyses were performed with 7 bedrock earthquake records de-convoluted from the outcrop records; the scaling of the peak ground accelerations were to 0.1 g. The study results show that the site coefficients of a poor-backfilled foundation are gradually reduced as the foundation embedment ratio increases, except in the case of a small foundation embedded deeply in the weak soft soil. In addition, it was found that the deviation of the site coefficients due to the foundation size was not significant. Therefore, the typical reduction factors of an embedded foundation with poor backfill are proposed in terms of the shear wave velocity and site class. This is in order to find the site coefficients of an embedded foundation by multiplying the reduction factor by a site coefficient of a surface foundation specified in the design code. They can then be interpolated to determine the intermediate shear wave velocity.

• The KIPS Transactions:PartB
• /
• v.10B no.2
• /
• pp.151-156
• /
• 2003

The vergence control method is presented for a parallel-axls stereo camera (PASC) using a signal processing technique such as shift, (rotation), and scaling. The PASC is considered as the simplest one of binocular stereo cameras. However, its major limitation lies in the controllability of vergence since its left and right imaging sensors of CCDs are fixed. On the other hand, a horizontal-moving-axis stereo camera (HMASC) with movable imaging sensors is able to control the vergence by moving its CCDs horizontally. In spite of its vergence controllability, there is a major drawback in the implementation because of complicated mechanical structure and the additional cost. To overcome the vergence control problem of the PASC, an operational principle of the HMASC is applied to the PASC. To be specific, without any additional hardware the vergence control problem of the PASC is solved with the signal processing technique. Assuming the virtual displacement between CCD's, a disappearing part of acquired images is removed and the original image site is recovered via interpolation. Experimental results show that the vergence control between stereo images captured by the PASC it possible with an acceptable degradation of the image quality defending on the virtual displacement of CCDs.

• Korean Journal of Cognitive Science
• /
• v.13 no.3
• /
• pp.1-10
• /
• 2002

This study was performed to analyze the physical attributes of the faces and affective words on the fares. For analyzing physical attributes inside of a face, 36 facial features were selected and almost of them were the lengths or distance values. For analyzing facial contour 14 points were selected and the lengths from nose-end to them were measured. The values of these features except ratio values normalized by facial vortical length or facial horizontal length because the face size of each person is different. The principal component analysis (PCA) was performed and four major factors were extracted: 'facial contour' component, 'vortical length of eye' component, 'facial width' component, 'eyebrow region' component. We supposed the five-dimensional imaginary space of faces using factor scores of PCA, and selected representative faces evenly in this space. On the other hand, the affective words on faces were collected from magazines and through surveys. The factor analysis and multidimensional scaling method were performed and two orthogonal dimensions for the affections on faces were suggested: babyish-mature and sharp-soft.