• 한국지진공학회논문집
• /
• 제10권4호
• /
• pp.15-24
• /
• 2006

본 연구는 각종 매설관의 경계조건에 따른 동적 거동에 대한 연구이다. 축방향 및 축직각방향에 대한 거동을 조사하였다. 매설관은 탄성기초 위에 놓인 보요소로 모형화하였고, 지진파는 정현파 형태의 지반 변위로 적용하였다. 매설관의 고유진동수와 모드 형태 그리고 매개변수의 영향을 조사하기 위해 자유 진동에 대한 해석을 수행했다. 그리고 지반진동에 대한 거동을 조사하기 위해 자유진동 해석을 통해 얻어진 고유진동수와 모드 형태를 이용하여 강제 진동에 대한수식을 유도하였다. 자유 진동시 매설관의 고유진동수에 가장 큰 영향을 미치는 것은 지반 강성과 매설관의 길이였다. 지반진동의 전파방향과 전파속도 그리고 진동수에 대한 콘크리트관, 강관, FRP관의 동적거동을 연구하였고 그 결과를 비교하였으며 다양한 단부경계조건에 대한 동적거동해석을 통해 매설관의 종류와 단부경계조건에 따른 최대 변형률 발생지점을 산정하였다.

• 대한치과교정학회지
• /
• 제46권1호
• /
• pp.42-54
• /
• 2016

The aim of this clinical report is to describe the complex treatment of an adult Class III malocclusion patient who was disappointed with the outcome of a previous oral rehabilitation. Interdisciplinary treatment planning was performed with a primary indication for implant removal because of marginal bone loss and gingival recession, followed by orthodontic and surgical procedures to correct the esthetics and skeletal malocclusion. The comprehensive treatment approach included: (1) implant removal in the area of the central incisors; (2) combined orthodontic decompensation with mesial displacement and forced extrusion of the lateral incisors; (3) extraction of the lateral incisors and placement of new implants corresponding to the central incisors, which received provisional crowns; (4) orthognathic surgery for maxillary advancement to improve occlusal and facial relationships; and finally, (5) orthodontic refinement followed by definitive prosthetic rehabilitation of the maxillary central incisors and reshaping of the adjacent teeth. At the three-year follow-up, clinical and radiographic examinations showed successful replacement of the central incisors and improved skeletal and esthetic appearances. Moreover, a Class II molar relationship was obtained with an ideal overbite, overjet, and intercuspation. In conclusion, we report the successful esthetic anterior rehabilitation of a complex case in which interdisciplinary treatment planning improved facial harmony, provided gingival architecture with sufficient width and thickness, and improved smile esthetics, resulting in enhanced patient comfort and satisfaction. This clinical case report might be useful to improve facial esthetics and occlusion in patients with dentoalveolar and skeletal defects.

• 한국안전학회지
• /
• 제23권4호
• /
• pp.13-18
• /
• 2008

This study deals with finish roll forming by forced displacement can be conceived as a method of eliminating errors in conventional form rolling under constant loads. This method produces a high-precision tooth profile by low-speed form rolling when a high rigid screw or cam is used at the pressurized section. Tooth profile is decided in the beginning of roll forming and ${\delta}_{max}$ mainly increases if the number of roll forming process is increased. Gear class is improved by one or two class after roll forming if the gear has convex type error and pressure angle error in KS 4 class. If the gear have concave type error and pressure angle error and pressure angle error, gear class is not improved in theory, but improved a little in practice. In the finishing roll forming, it inevitably yields both the concaving of tooth profile and plastic deflection of addendum of teeth. Experiments show that the concaving and the plastic deflection are successfully reduced, the accuracy of tooth profile reaches to KS 0 class.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
• /
• pp.833-841
• /
• 2008

Recently, the upheaval generation in the road which is under service had been reported. Due to the upheaval generation, total 4 lanes were forced to curtail to 3 lanes, and traffic was delayed. In normal situation of cut-slopes in korea, that condition is hard to detect since most cut-slopes contain discontinuous material, that is rock. Common collapses in rock-slopes is wedge failure, plane failure and toppling failure which is all individual mechanism of discontinuous rock mass. In contrast, such upheaval in the road in front of cut-slope can be generated only when circular movement is triggered within the cut-slope. In this sense, rock-slopes barely show any kind of movement in the road locates at the front of them. Numerical analysis is general method in simulation of slope displacement and evaluation of safety. However, numerical analysis programs which are related with rock-slopes are not able to simulate such upheaval movement because that programs are based on discontinuous modeling mechanism. In addition, although numerical analysis programs which are based on FEM/FDM and thus utilize continuous modeling mechanism are able to simulate circular movement and upheaval situation, they have weakness in reflecting discontinuities of rock-slope itself. In this study, detailed in-site investigation and numerical analysis based on in-site condition were performed in order to expect upheaval movement in the road. In this procedure, the FLAC program which uses continuous modeling method was utilized, and new approach reflecting discontinuity developed toward the road with a ubiquitous joint model was tried to derive reliable analysis result.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.1148-1158
• /
• 2005

This work reports results of our study on the dynamic responses of the buried pipelines both along the axial and the transverse directions under various boundary end conditions. We have considered three cases, i.e., the free ends, the fixed ends, and the fixed-free ends. We have studied the seismic responses of the buried pipelines with the various boundary end conditions both along the axial and the transverse direction. We have considered three cases, i.e., the free ends, the fixed ends, and the fixed-free ends for the axial direction, and three more cases including the guided ends, the simply supported ends, and the supported-guided ends for the transverse direction. The buried pipelines are modeled as beams on elastic foundation while the seismic waves as a ground displacement in the form of a sinusoidal wave. The natural frequency and its mode, and the effect of parameters have been interpreted in terms of free vibration. The natural frequency varies most significantly by the soil stiffness and the length of the buried pipelines in the case of free vibration, which increases with increasing soil stiffness and decreases with increasing length of the buried pipeline. Such a behavior appears most prominently along the axial rather than the transverse direction of the buried pipelines. The resulting frequencies and the mode shapes obtained from the free vibration for the various boundary end conditions of the pipelines have been utilized to derive the mathematical formulae for the displacements and the strains along the axial direction, and the displacements and the bending strains along the transverse direction in case of the forced vibration. The negligibly small difference of 6.2% between our result and that of Ogawa et. al. (2001) for the axial strain with a one second period confirms the accuracy of our approach in this study.

• 한국임상수의학회지
• /
• 제11권1호
• /
• pp.369-376
• /
• 1994

The purpose of this report Is to discribe the radiological findings of traumatic elbow luxation and subluxation of carpal joint which were caused by being hit by a wild animal and forced hyperextension of carpus in two hunting dogs. In case 1, carniocaudal and mediolateral radiographic examination of the elbow joint revealed that the radius that the radius and ulna were completely luxated laterally. The lateral projection showed the humeral condyles overlying the radial head with an absent joint space, but displacement is apparent on the craniocaudal projection. Incidence of collateral ligament rupture in conjunction with elbow luxation was not recognized on physical examination of the limb after closed reduction. Radiographic examination of the elbow made 5 months after closed reduction revealed only mild degenerative joint disease. Radiographic examination of the carpus in case 2 demonstrated palmar subluxation of most carpal joints including antebrachiocarpal, mediocarpal carpometacarpal joints, and some intercarpal joints, and avulsion fracture of the palmar surface of the accessory carpal bone. However, the mediocarpal and carpometacarpal joints were most severely affected by tensile forces of hyperextension, and it was concluded that the ligaments of the middle ca,pal joints and carpometacarpal joints as well as the palmar fibrocartilage were ruptured based on clinical and radiographic findings. In elbow luxation and subluxation of carpal Joints of the dog, differentiation of the joint or joints involved, and ligamentous structures damaged is important in determining whether surgery Is necessary and which procedure is most appropriate. And the radiographic findings of these conditions would be of help to practitioners.

• 영어영문학
• /
• 제55권6호
• /
• pp.1035-1056
• /
• 2009

Korean adoptee narratives have proliferated over the last ten years as adopted Koreans have begun to represent their own experiences of violent dislocation, displacement and loss in various forms of literary and artistic works, including poems, autobiographical works, novels, documentaries and films. These narratives by Korean adoptees have intervened in the current diaspora discourse to question further the traditional categories of race, ethnicity, culture and nation by representing the unique experiences of the forced and involuntary migration of adopted Koreans. For a long time, the adoption discourse has been mostly constructed from the perspectives of adoptive parents. Therefore the voice of adoptees as well as that of the birth mothers have not been properly heard or represented in adoption discourse. According to Hosu Kim, the U. S. adoption discourse, feeling pressured to deal with the stigma of the commodification of children, changed from viewing the adoptees as children who had been rescued from poverty and abandonment to considering them as a gift from the birth mothers. With the emergence of the gift rhetoric in transnational adoption, the birth mothers erased from adoption discourse have begun to be acknowledged as one of the central characters in the adoption triad. If Korean adoptees are the "the ghostly children of Korean history," the birth mothers are their "ghostly doubles" who "bear the mark of a repressed national trauma." Somebody's Daughter represents the female experiences of becoming an adopted child and of being a birth mother. In particular, the novel makes a birth mother, the forgotten presence in adoptee narratives, into a central figure in the triangular relationship created by international adoption. The novel historicizes the experiences of a Korean adoptee growing up in America as well as those of a mother who had suffered silently from feelings of unbearable loss, guilt, grief and from unforgettable memories. In addition, narrating the birth mother's story is a way to give humanity back to these forgotten women in Korean adoption history. Revisiting the site of loss both for a mother and a daughter through the novel is an act of collective mourning. The narratives about and by Korean adoptees force Korean intellectuals to reflect seriously upon Korean society and its underlying ideology which prevents a woman from mothering her own baby, and to take an ethical and political stand on this current social and political issue.

• Structural Engineering and Mechanics
• /
• 제78권2호
• /
• pp.125-134
• /
• 2021

In this paper, the effects of Tuned Mass dampers (TMDs) on the reduction of the vertical vibrations of a real horizontally curved steel box-girder bridge due to different traffic loads are numerically investigated. The performance of TMDs to reduce the bridge vibrations can be affected by the parameters such as dynamic characteristics of TMDs, the location of TMDs, the speed and weight of vehicles. In the first part of this study, the effects of mass ratio, damping percentage, frequency ratio, and location of TMDs on the performance of TMDs to decrease vertical vibrations of different sections of bridge deck are evaluated. In the second part, the performance of TMD is investigated for different speeds and weights of traffic loads. Results show that the mass ratio of TMDs is the more effective parameter in reducing imposed vertical vibration in comparison with the damping ratio. Furthermore, it is found that TMD is very sensitive to its tuned frequency, i.e., with a little deviation from a suitable frequency, the expected performance of TMD significantly decreased. TMDs have a positive and considerable performance at certain vehicle speeds and this performance declines when the weight of traffic loads is increased. Besides, the results reveal that the highest impact of TMD on the reduction of the vertical vibrations is when free vibrations occur for the bridge deck. In that case, maximum reductions of 24% and 59% are reported in the vertical acceleration of the bridge deck for the forced and free vibration amplitudes, respectively. The maximum reduction of 13% is also obtained for the maximum displacement of the bridge deck. The results are mainly related to the resonance condition.

• 예술인문사회 융합 멀티미디어 논문지
• /
• 제8권3호
• /
• pp.589-596
• /
• 2018

현대 사회에서 의식주 중에서 구조물이나 운송수단은 중요한 역할을 가진다. 만약 구조물이나 운송수단에 작은 크랙이라도 생기고 크랙이 진전되면 그 부품들이 파괴되어 큰 사고를 야기할 수 있다. 이러한 상황을 방지하기 위한 본 연구에서는 크랙의 진전에 따른 파손 경향을 조사하기 위하여 시험편을 이용하였다. CT 시험편의 재질로는 요즘 각광받는 복합재료인 단방향 탄소섬유 강화플라스틱을 사용하였다. 시험편 모델은 단방향성 섬유로서 적층각도를 주었고 적층각도는 [60/-60/60/-60]순으로 지정하였다. 해석 조건으로는 하단부의 홀을 고정시킨후 상단부 홀을 15mm의 강제 변위를 가하였다. 본 연구 결과로는 구조용 강, 구리, 티타늄, 알루미늄 순으로 등가응력과 전단응력이 높게 나왔다. 이러한 결과는 이종재료로 만들어진 CT 시험편의 파손을 검증하는 데 유용하게 사용될 수 있다고 사료된다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2005년도 춘계 학술발표회 논문집
• /
• pp.328-337
• /
• 2005

This work reports results of our study on the dynamic responses of the buried pipelines both along the axial and the transverse directions under various boundary end conditions. We have considered three cases, i.e., the free ends, the fixed ends, and the fixed-free ends for the axial direction, and three more cases including the guided ends, the simply supported ends, and the supported-guided ends for the transverse direction. In order to investigate the effect of the boundary end conditions for the dynamic responses of the buried pipeline, we have devised a computer program to find the solutions of the formulae on the dynamic responses (displacements, axial strains, and bending strains) under the various boundary end conditions considered in this study. The dynamic behavior of the buried pipelines for the forced vibration is found to exhibit two different forms, a transient response and a steady state response, depending on the time before and after the transfer of a seismic wave on the end of the buried pipeline. The former is identified by a slight change in its behavior before the sinusoidal-shaped seismic wave travels along the whole length of the pipeline whereas the latter by the complete form of a sinusoidal wave when the wave travels throughout the pipeline. The transient response becomes insignificant as the wave speed increases. We have observed a resonance when the mode wavelength matches the wavelength of the seismic wave, where the mode number(k) of resonance for the axial direction is found to be $\overline{\omega}/{\pi}V+1/2$ for the fixed-free ends, $\overline{\omega}/{\pi}V+1$ for the free ends, and $\overline{\omega}/{\pi}V$ for the fixed ends, respectively. By adding 10 more modes to the mode number(k) of resonance, we were able to study all the dynamic responses of the buried pipeline for the axial direction. On the other hand, we have not been able to observe a resonance in the analysis for the transverse direction, because the dynamic responses are found to vanish after the seventh mode. From the results of the dynamic responses at the many points of the pipeline, we have found that the responses appeared to be dependent critically on the boundary end conditions. Such effects are found to be most prominent especially for the maximum values of the displacement and the strain and its position.