• 한국지구물리탐사학회:학술대회논문집
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• 2005.05a
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• pp.15-20
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• 2005

Defects of dam body which can be induced in seepage or leakage procedure can directly affect dam safety. Therefore, a proper inspection method should be carried out in the first place to find out their positions and sizes, After that, some reinforcement works such as grouting and the corresponding assessment could be taken in a proper way. The dam(center core type earth dam) issued in this study has been in need for intensive diagnosis and reinforcement work, because a lot of slumps similar to cracks, seepage and some boggy area have been observed on the downstream slope. High resolution seismic reflection method was performed on the crest profile twice before and after grouting work(Aug. 2001 and Nov. 2004) aimed at the dam inspection and the assessment of grouting efficiency as well. To enhance the data resolution, P-beam energy radiation technique which can reduce the surface waves and hence to reinforce the reflection events was used. Strong reflection events were recognized in the stack section before grouting work, It seems that the events would be caused by e.g. horizontal cracks with a considerable aperture, Meanwhile such strong reflection events were not observed in the section after grouting. That is, the grouting work was dear able to reinforce the defects of dam body. Hence, the section showed an well arranged picture of dam inner structure. In this sense, seismic reflection method will be a desirable technique for dam inspection and for monitoring dam inner structure as well.

• Journal of the Korean Geophysical Society
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• v.8 no.1
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• pp.1-6
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• 2005

Defects of dam body which can be induced in seepage or leakage procedure can directly affect dam safety. Therefore, a proper inspection method should be carried out in the first place to find out their positions and sizes. After that, some reinforcement works such as grouting and the corresponding assessment could be taken in a proper way. The dam(center core type earth dam) issued in this study has been in need for intensive diagnosis and reinforcement work, because a lot of slumps similar to cracks, seepage and some boggy area have been observed on the downstream slope. High resolution seismic reflection method was performed on the crest profile twice before and after grouting work(Aug. 2001 and Nov. 2004) aimed at the dam inspection and the assessment of grouting efficiency as well. To enhance the data resolution, P-beam energy radiation technique which can reduce the surface waves and hence to reinforce the reflection events was used. Strong reflection events were recognized in the stack section before grouting work, It seems that the events would be caused by e.g. horizontal cracks with a considerable aperture. Meanwhile such strong reflection events were not observed in the section after grouting. That is, the grouting work was dear able to reinforce the defects of dam body. Hence, the section showed an well arranged picture of dam inner structure. In this sense, seismic reflection method will be a desirable technique for dam inspection and for monitoring dam inner structure as well.

• Journal of the Korean Geophysical Society
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• v.9 no.4
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• pp.443-453
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• 2006

Using seismic profiles obtained in the Antarctic Peninsula continental margin around Smith Island located at the southwestern end of the South Shetland Islands, we investigated sediments distribution, sedimentation, continental shelf formation, and tectonic evolution history. The study area is a very unique area that has two tectonic provinces with a tectonic boundary near Smith Island just the landward projection of the Hero Fracture Zone (HFZ). To the southwest of the Island, the margin became inactive margin after the collision of the ridge crest of the Antarctic-Phoenix ridge and trench, whereas to the northeast the margin is still apparently active margin with the spreading center and trench morphology in the sea. Generally the northeastern margin has the shelf sedimentary basins wth thick sedimentary layers, well-developed forearc basin, broad continental slope and distinct trench morphology, and the southwestern margin is characterized by steep and narrow continental slope and localized shelf basins. the mid-shelf basement high structures are distinct in the southwestern margin, which are thought to be formed by thermal effect caused by the subducted spreading centers. The high is observed in the area just northeast of the Island, implying that the tectonic boundary along the landward projection of the HFZ is not sharply defined.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.206-214
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• 2009

Statement of problem: There are common clinical cases in which the mandibular first and second molars are missing unilaterally. Purpose: This study was designed to compare and evaluate the magnitude and distribution of stress produced by four kinds of mandibular unilateral free-end removable partial dentures that could be applied clinically in Kennedy class II cases. Material and methods: Four unilateral free-end removable partial dentures using clasp, Konus crown, resilient attachment, and flexible resin were fabricated on the photoelastic models of the Kennedy class II cases. The vertical load of 6㎏ was applied on the central fossa of the first molar of every removable partial denture in the stress freezing furnace and the photoelastic models were frozen according to the stress freezing cycle. After these models were sliced mesio-distally to a thickness of 6mm, the photoelastic isochromatic white and black lines of the sliced specimens were examined with the transparent photoelastic experiment device and photographs were taken with a digital camera. The fringe order numbers at eight measuring points in the photograph were measured with the naked eye. Results: The maximum fringe order number of each sliced specimen and the fringe order number at the residual ridge just below the loading point were in the decreasing order of the unilateral removable partial dentures using flexible resin followed by clasp, resilient attachment, and Konus crown. The fringe order number at the root apex of the second premolar was in the decreasing order of the unilateral removable partial dentures using clasp followed by flexible resin, Konus crown, and resilient attachment. Conclusion: The removable partial denture using Konus crown showed the most equalized stress distribution to the supporting alveolar bone of abutment teeth and residual ridge under the vertical loads. The removable partial denture using flexible resin can be applied to the case that has a better state of residual ridge than abutment teeth.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.04a
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• pp.299-302
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• 2002

침하지반의 지하구조 해석을 위한 방법으로 전기비저항, 지하투과레이더, 굴절법 탄성파탐사를 실시하였다. 침하가 발생한 지점을 중심으로 조사를 실시하여 보강을 위한 경계를 설정하였으며 그라우팅 보강공사가 이후에 재차 시행되었다. 지반의 침하는 원지반 상부 연약지반에서 발생하였으며 침하량은 최대 50cm 정도이다. 침하의 원인은 해수 유입에 따근 지지력의 감소가 주된 원인으로 추정되며 보강공사 후 상부 연약지반의 전기비저항은 원지반과 거의 같은 크기를 보여준다.

• The Korean Journal of Rheology
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• v.4 no.1
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• pp.46-51
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• 1992

본 연구에서는 열가소성고무를 중심으로 한 스티렌 공중합체의 유변학적 특성을 Couette 보정치를 사용하여 해석하였다. 실험재료로는 SBS(Styrene-Butadiene-Styrene), SEBS(Styrene-Ethylene/Buthylene-Styrene), SIS(Styrene-Isoprene-Styrene)을 사용하였고 탄성체의 성격을 비교하기 위하여SBS(Styrene-Butadiene Rubber)와 IR(Isoprene Rubber)를 사용하였다, 실험결과 Couette 보정치는 온도가 증가할수록 감소하였다. 또한 열가소성 고부 (SBS, SEBS, SIS)의 보정치는 거의 비슷한 값을 나타내었으며 고무(IR, SBR)의 보정치는 열가소성고무에서보다 다소 높은 값을 나타내었다. 충진제를 첨가하였을 경우 충진제의 양 이 증가할수록 Couette 보정치는 감소하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10c
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• pp.600-602
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• 1998

본 논문은 정면과 측면 얼굴 이미지의 특성을 살린 3차원 개인 아바타 합성에 관한 연구이다. 표준 얼굴 메쉬를 얼굴 이미지의 특징점에 맞추려는 힘을 특징점 이외의 점들까지의 거리에 대한 가우스 분포를 따라 부드럽게 전달시켜 매쉬를 탄성있게 변형하는 힘으로 작용시켜 메쉬를 얼굴 이미지의 윤곽선을 중심으로 매칭시키고, 매칭된 메쉬가 매칭 이전의 메쉬의 기하학적 특성을 유지할 수 있도록 메쉬에 동적 피부 모델을 적용한다. 이렇게 생성한 3차원 메쉬에 이미지를 텍스춰 매핑하여 개인 특성을 살린 3차원 개인 아바타를 생성한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.1
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• pp.1-12
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• 2021

In this paper, a new algorithm is proposed to estimate the damage location in the composite panel by extracting the elastic wave signal reflected from the damaged area. The guided elastic wave is generated by a piezoelectric actuator and sensed by a piezoelectric sensor. The proposed algorithm adopts a diagnostic approach. It compares the non-damaged signal with the damaged signal, and extract damage information along with sensor network and lamb wave group velocity estimated by signal correlation. However, it is difficult to clearly distinguish the damage location due to the nonlinear properties of lamb wave and complex information composed of various signals. To overcome this difficulty, the cumulative summation feature vector algorithm(CSFV) and a visualization technique are newly proposed in this paper. CSFV algorithm finds the center position of the damage by converting the signals reflected from the damage to the area of distance at which signals reach, and visualization technique is applied that expresses feature vectors by multiplying damage indexes. Experiments are performed for a composite panel and comparative study with the existing algorithms is carried out. From the results, it is confirmed that the damage location can be detected by the proposed algorithm with more reliable accuracy.

• Journal of Korean Society of Steel Construction
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• v.21 no.1
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• pp.63-70
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• 2009

Failure modes result in fracture or tearing, which may cause deterioration of resistance and reduction of inelastic deformation capacity. The potential failure modes for Special Concentrically Braced Frames (SCBFs) include fracture or tearing of the brace, net section fracture of the brace or gusset plate, fracture of the gusset plate welds, shear fracture of the bolts, block shear, excessive bolt bearing deformation, and buckling of the gusset plate. HSS tubular braces are commonly used in SCBFs, and net section fracture of the tubular brace may also occur through the brace net section at the end of the slot cut into the tube to slip over the gusset plate. This failure mode is categorized as a tension failure mode, and may cause dramatic loss of resistance and brittle behavior. Net section reinforcement is required according to AISC design specifications (AISC 2001). In this paper, the need to reinforce the net section area was discussed. Initially, the results of the net section fracture tests done by the University of California in Berkeley were presented with the modeling of these tests using FE models. To investigate the possibility of net section fracture in an actual frame, the slot end hole model was adapted to the frame FE model, and alternate near-fault histories were applied with tension-dominated cycles, since previous analyses showed that loading history was the most critical factor in net section fracture. The need for this reinforcement (cover plate) and the tension-dominated near-fault history were investigated.

• Geotechnical Engineering
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• v.6 no.1
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• pp.35-42
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• 1990

Over the years, most pavement designs based on soil strength and permanent strain are almost independent of soil elasticity. However, it was found that plasticity and elasticity of soil have both effected on the failure of pavement structures. The elasticity of soil, hence, using the resilient modulus is reflected for recent pavement design. Although the current AASHTO specifications(1986) for pavement design had changed the soil support value to the resilient modulus, triaxial devices conducting the resilient modulus test have not been fully equipped in a great majority of laboratories. Thus, in the present work, such a resilient modulus is usually derived(from CBR, K values, etc.) by estimating equations. The purpose of this study is to evaluate the resilient modulus of weathered granite soils sampled from 4 points of the central region of Korea by means of AASHTO T 274-82. According to this, some empirical equations for predicting that of the weathered granite soil are proposed and then, the relationship to convert CBR into the resilient modulus is developed.