• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.173-181
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• 2000

Depending upon the method of the surface generation and the quality of the boundary curves provided, the resulting surfaces may have global or local irregularities in many cases. Thus it would be necessary for the designer to evaluate the surface quality and to modify the surface. This capability is very important because the defect of the surface requires the rework of the dies that causes a big loss in cost and delivery time. To simulate the reflection line test in the actual production line, a faster generation algorithm is presented. Among., various surface interrogation methods using reflection lines, Blinn-Newell type of reflection mapping is applied to generate reflection lines on the trimmed NURBS surface. The generation of reflection lines is formulated as a surface-plane intersection problem, and solved by surface-contouring techniques. In addition, a modified reflection map is proposed to eliminate the discontinuity of reflection lines due to the configuration of the reflection map. A fast reflection line algorithm is developed utilizing an efficient traced contouring technique, and proved to be well suited for real-time quality-assessment task.

• Journal of the Korea Institute of Military Science and Technology
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• v.4 no.1
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• pp.246-254
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• 2001

The breech system can be considered as a pressure vessel with an internal plug under high explosive pressure. The system consists of a breech block(internal plug) whose front surface subjects to pressure, and a breech ring(pressure vessel). There is the geometric discontinuity around roots of connection parts and then stress concentration is introduced due to pressure, where contact effect may be ignored because contact plane between two equipments is parallel ideally, Generally high stress concentration phenomena shorten the life cycle of the mechanical system. It is well known that shock load is much more harmful on safety of the system than static load. In this present paper, several geometric design variables which may affect stress condition on the system are chosen and the parametric study on the design variables is carried using commercial FEM codes. Finally, the obtained results in the single lug breech system are applied to design the 3 lugs breech system. The 3 lugs breech system can reduce the maximum stress level.

• Journal of Mechanical Science and Technology
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• v.15 no.2
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• pp.160-171
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• 2001

Depending upon the method of the surface generation and the quality of the designed boundary curves, the resulting surfaces may have global or local irregularities in many cases. Thus, it would be necessary for the designer to evaluate the surface quality and to modify the surface. This is very important because the defect of the surface causes the rework of the dies, increasing cost and delivery time significantly. To simulate the reflection line test in the actual production line, a faster algorithm for generating reflection lines is presented. In this paper, among various surface interrogation methods using reflection lines, Blinn-Newell type of reflection mapping is applied to generate the reflection lines on the trimmed NURBS surfaces. The derivation of reflection lines is formulated as a surface-plane intersection problem (Jung 1994) and is solved by surface-contouring techniques. Also, for eliminating the discontinuity of reflection lines due to the configuration of reflection map, a modified reflection map is proposed. An efficient traced contouring technique is utilized for the computational efficiency and proves to be well suited for the real-time quality-assessment task.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.865-872
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• 2006

Recently, many apartment buildings in the shear wall system often has pilotis in the lower story to meet the architectural needs. If the lateral force resisting system consists of shear walls supported by columns and beams. the discontinuity at the lowest level with pilotis results in the vertical irregularity with strength and stiffness. So, there are needs to be considered tile analysis and design about column and beam bellow shear walls and the behavior and stress condition of structure by stiffness change being generated at shear walls. The purpose of this paper is to investigate the behavior of shear wall structures with pilotis using the floors modeled as rigid diaphragm or semi rigid diaphragm. Through analyses, after estimating values of the story drift, natural period, stress condition of shear walls and the forces of column, we inferred how the behavior of shear wall structures with pilotis was influenced by the floor stiffness.

• Computers and Concrete
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• v.17 no.6
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• pp.723-737
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• 2016

In this paper an approach was described for determination of direction of sliding block in rock slopes containing planar non-persistent open joints. For this study, several gypsum blocks containing planar non-persistent open joints with dimensions of $15{\times}15{\times}15cm$ were build. The rock bridges occupy 45, 90 and $135cm^2$ of total shear surface ($225cm^2$), and their configuration in shear plane were different. From each model, two similar blocks were prepared and were subjected to shearing under normal stresses of 3.33 and $7.77kg/cm^{-2}$. Based on the change in the configuration of rock-bridges, a factor called the Effective Joint Coefficient (EJC) was formulated, that is the ratio of the effective joint surface that is in front of the rock-bridge and the total shear surface. In general, the failure pattern is influenced by the EJC while shear strength is closely related to the failure pattern. It is observed that the propagation of wing tensile cracks or shear cracks depends on the EJC and the coalescence of wing cracks or shear cracks dominates the eventual failure pattern and determines the peak shear load of the rock specimens. So the EJC is a key factor to determine the sliding direction in rock slopes containing planar non-persistent open joints.

• Archives of Craniofacial Surgery
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• v.20 no.3
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• pp.181-185
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• 2019

Intraosseous hemangioma is a rare, slow-growing, benign tumor of blood vessels. Primary hemangioma of the skull is a benign lesion that may appear as a palpable mass or accidentally detected during image evaluation. Simple radiography is the most commonly used technique to localize a lesion and computed tomography (CT) may help determine the effect of a lesion. We report a case of multifocal intraosseous calvarial hemangioma developed in the subgaleal plane of an elderly male patient. Ultrasonography examination revealed hyperechoic striated septae parallel to the skin and discontinuity of the focal cortex, however, the underlying bone cortex appeared relatively intact. No significant flow is observed on Doppler ultrasonography. Based on these evaluations, the mass was interpreted by a radiologist as a subgaleal lipoma. This case highlights the importance of additional CT examination in a patient presenting with a scalloping sign of the underlying calvarium. Clinicians also should be aware of the possibility of intraosseous calvarial hemangiomas in lesion. Furthermore, the proper choice of congenital vascular malformation term is still quite confusing with misconception present in the literature.

• Tunnel and Underground Space
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• v.18 no.1
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• pp.20-32
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• 2008

The study shows a method called a square-inventory method, which is a better and faster method than scanline survey and window method for an analysis of slope stability. The study area is located in the Changri area, Boeun-Gun, Chungbuk, and consists of many formations of the Okcheon Supergroup. Various types of failure are observed from the phyllite including the rocks in the study area. The physical properties of meta-sedimentary rocks are that minerals of the rocks are composed of microcrystalline quartz and sericite, which are arranged parallel to bedding (or schistosity) and crenulation cleavage. Therefore, such properties affect geotechnical ones of the rock. The slope stability are analyzed by selecting 3 areas, each of which are divided into 2 or 3 slopes of $1m{\times}1m$ area that represent each of 3 investigation sites. The possibility of wedge and toppling failure is very high in all 3 areas by using square-inventory method. Although possibility of plane failure is weak in the investigation site 2, the plane failures are frequently found from the slope of site 2. The bedding (or schistosity) plane and cleavage, another types of discontinuity coexist in meta-sedimentary rocks uulike igneous rocks, and therefore are important factors to be considered together with joint structures in th ε analysis of slope stability.

• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.111-120
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• 2008

The characteristic of induced anisotropy is investigated in this study for the Pohang mudstone involving the cut plane discontinuity. The uniaxial and triaxial compression tests are performed for anisotropic rocks with artificial joint to look into anisotropic strength characteristics. Both the uniaxial compressive strength and triaxial compressive strength show the lowest value at the angle of cut plane, ${\beta}=30^{\circ}$ and the shoulder type of anisotropy is obtained. Anisotropy ratio (Rc) in uniaxial compression measures 9.0, whereas Rc=1.29-1.98 in triaxial compression is appeared. A series of analyses are made with the test results to derive the suitable parameter values when it is applied to the Ramamurthy (1985) failure criterion. The result of uniaxial compression test is analyzed by introducing the n-index into Ramamurthy failure criterion. The result shows that, n=l is suitable for ${\beta}=0^{\circ}{\sim}30^{\circ}$ and n=3 is suitable for ${\beta}=30^{\circ}{\sim}90^{\circ}$. To analyze the result of triaxial compression test by Ramamurthy failure criterion, anisotropy ratio in uniaxial compression test is added to Ramamurthy's equation and material constants are estimated by modified Ramamurthy's equation. When these values are applied back to Ramamurthy failure criterion, the predicted values are well fitted to the test results. And strength anisotropy for failure criteria of Jaeger (1960), McLamore & Gray (1967) and Hoek & Brown (1980) are also investigated.

• Journal of Conservation Science
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• v.26 no.3
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• pp.277-294
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• 2010

The Seosanmaaesamjonbulsang (National Treasure No. 84) consists of light gray and coarse to mediumgrained biotite granite with partly developed pegmatite and quartz vein. The host rock is divided into dozens of rock blocks with various shape along irregular discontinuity plane. The evaluation results of discontinuity systems reveal that the host rock were exposed to instable sloping environments. Results of deterioration diagnosis show that the degree of damage has been made worse by physical weathering and surface discoloration laying stress on part that vertical and horizontal joints are massed. Generally, deterioration rate of the triad Buddha surface cover with 42.7%, however, the rate of physical weathering and surface discoloration are subdivided to 9.6% and 33.1%, respectively. Ultrasonic measurements indicate that the triad Buddha was reached highly weathered grade in general. And the rock material was weaken to show low velocity zone of 1,000m/s along irregular joint systems. Indoor and outdoor mean relative humidity of the shelter was recorded more than 70% during every season, and high frequency appears in high relative humidity range over 95%. Such environments seem to have produced dew condensation on the rock surface with rainfall and supply water, promoted physical, chemical and biological weathering along crack and joint, resulting in high permeation of water and percentage of water content. Therefore, it is judged that for scientific conservation of the triad Buddha it needs environment control through persistent preservation environment monitoring including water problem.

• 한국문화재보존과학회:학술대회논문집
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• 2004.10a
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• pp.81-91
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• 2004

The host rock of standing sculptured Buddha in the Yongamsa temple was macular biotite granite, which has gone through mechanical and chemical weathering. The principal rock-forming minerals are quartz, plagioclase, alkali feldspar, and biotite, the last two of which have been transformed into clay minerals and chlorite due to weathering processes. The bed rock around the Buddha statue is busily scattered with steep inclinations that are almost vertical and discontinuous planes with the strikes of $N8^{\circ}E$. The major joints have the strikes of N4 to $52^{\circ}W$ and N6 to $88^{\circ}E$ and the dips of 42 to $89^{\circ}$. Especially thee development of the joints that cross the major joints causes tile structural instability of the rock. The host rock of the Buddha image is separated into many different rock masses because of the also many different discontinuity, which group accounts for about $12{\%}$ of the rock. Thus it's estimated that the bed rock has not only plane and toppling failure but also wedge failure in all the sides. Since the earth pressure and the inclination pressure are imposed on the body of the Buddha in the basement rock, it's urgent to give a treatment of geotechnical engineering for the sake of its structural stability. The parts where serious fractures are seen should receive the hardening process using the fillers for stones. It's also necessary to introduce a landfill liner system in order to reduce the ground humidity. The rock surface of the Buddha statue are partly contaminated by lichens and bryophyte. The joints have turned into earth, which promotes the growth of weeds and plant roots. Thus biochemical treatments should also be considered to get rid of the vegetation along the discontinuous planes and prevent further biological damages.