• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.4
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• pp.487-493
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• 2010

Most structural analyses are concerned with the deformations and stresses in a body subjected to external loads. However, in many fields, inverse problems have to be interpreted to determine surface tractions or internal stresses from displacements measured on a remote surface. In this study, the inverse processes are studied by using the finite element method for the evaluation of internal stresses. Small errors in the measured displacements often result in a substantial loss of stability of an inverse system. In order to improve the stability of the inverse system, the displacements on a section near the region of the unknown tractions are predicted by using orthogonal basis functions. We use the Gram-Schmidt orthogonal technique to determine two bases for the displacements on a section near the region of the unknown tractions. Advantages over previous methods are discussed by using numerical examples.

• Journal of Korean Society of Forest Science
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• v.97 no.3
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• pp.255-265
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• 2008

This study is aiming at providing the useful information for successful implementation of the forest resource promotion policy through analyzing the impacting factors and their relationships on policy accomplishment and policy effectiveness in executing the forest resource promotion policy. Interview survey was conducted on the stake-holders such as government officers and civilians who have direct or indirect influences on the establishment and execution of the forest resource promotion policy. The forest resource promotion policy was heuristically analyzed by using the LISREL (Linear Structural RELations) Model. The policy accomplishments of forest resource promotion significantly showed the positive relations with the suitability of problem recognition, the suitability of policy decision-making and rationality of policy execution, while the degree of policy support and the policy accomplishments were having significant impacts upon the policy effectiveness. Since the path coefficients between the latent variables and observed variables and among the latent variables mostly showed the positive relations significantly, the forest resource promotion policy was evaluated very successful in terms of policy accomplishments and policy effectiveness.

• Journal of Navigation and Port Research
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• v.34 no.6
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• pp.405-415
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• 2010

To assess the possible collision risk between Mokpo Harbour Bridge, which is under construction, and passing vessels, we proposed Real-Time Bridge-Vessel Collision Model (RT-BVCM) in this paper. The mathematical model of RT-BVCM consists of the causation probability by the vessel aberrancy due to navigation environments, the geometric probability by the structural feature of a bridge relative to a ship size and, the failure probability by the ship collision track and the stopping distance which is not to come to a stop before hitting the obstacles. Then, the probabilistic mathematical model represented as risk index with the risk level from 1 to 5. The merit of the proposed model to the collision model proposed by AASHTO (American Association of State Highway and Transportation Officials) is that it can provide enough time to take adequate collision avoiding action. Through the simulation tests to the two kinds of test ships, 3,000 GT and 10,000 GT, it is cleary found that the proposed model can be used as a collision evaluation model to the passing vessel and Mokpo Harbour Bridge.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1996.12a
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• pp.63-63
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• 1996

We performed chromosomal aberration assay in Chinese Hamster Lung (CHL) cells in vitro to evaluate theclastogenicity of 11 synthetic chemicals which were listed in Toxicity Evaluation Program of Ministry of Environment of Republic of Korea in 1996. All of the chemicals were carried out MTT assay to determine the 50% cell growth inhibition concentration. All compounds were tested with and without metabolic activation system. Benzoyl chloride revealed positive result at $43\;\mu\textrm{g}/m{\ell}$ in the presence of metabolic activation system, and at 30.8, 61.5 and $123\;\mu\textrm{g}/m{\ell}$ in the absence of metabolic activation system. And p-phenoxy ethanol was observed as positive with the metabolic activation system, but negative without metabolic activation system. Especially 2-propyn-l-ol showed high frequency of pulverization and showed critical difference of cytotoxicity between with and without S9 mixture. Pulverizatiuon is not included in the frequency of structural aberration in our criteria. Dicyclopentadiene, methacrylic acid, aa-dimethylbenzyl hydroperoxide, benzylbutyl phthalate, and p-chlorophenal were revealed negative results.esults.

• Korean Journal of Digital Imaging in Medicine
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• v.11 no.2
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• pp.85-92
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• 2009

This study, "The study about performance evaluations of mobile cover for X-ray's diffusion and distribution in mobile radiation" is based on the rules of mobile defense apparatus for radiation producer in 2006. To use the mobile cover for X-ray for diagnosis has been compulsory in common wards except operation rooms, emergency rooms and intensive care units. we have confirmed the effect in arbitrary shielding material after Qualitiy Control was carried out for accuracy in an experiment of mobile photographing equipment. The performance evaluation was conducted with the fabrics of selenium, 0.2 mmPb, 0.1 mmPb and aluminiums. Considering the result, we choosed 0.1 mmPb and attached cover to mobile photographing equipment. We have finished making the cover after drew up the draft to attach cover to mobile photographing equipment through the modeling and the structural analysis. the process of the study is that we assembled the manufactured structures and carried out the practical experiment to take the photograph after attaching the fabric of 0.1 mmPb to mobile photographing equipment. It is need of additional thesises hereafter that we compare the result between the part to improve for safety besides convenience in photographic experiment about clinical radiation and the effect of covering the diffusion in condition attached the cover.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.2
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• pp.156-164
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• 2003

STS316L had been used as the structural material for energy environmental facilities, because austenite stainless steels like 316L have superior mechanical properties of which toughness, ductility, corrosion resistant and etc. However, those welded structures are receiving severe damage due to increasing of the aged degradation. Most studies until now have been carried out against fatigue behaviors of weldments, and were not well studied on nondestructive evaluation methods. In this study, the fatigue crack propagation behavior of STS316L weldment usually used for vessels of the nuclear power plant was investigated. Also, the degradation characteristics of 316L stainless steel weldments were evaluated by the ultrasonic parameter such as ultrasonic velocity, attenuation factor and time-frequency analysis. The results of this study can be used as a basic data for the prediction of the fatigue crack life of weldments structures without disjointing or stopping service of structures in service.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.83-92
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• 2005

An electromagnetic acoustic transducer (EMAT) is a unique probe that does not require a couplant or gel and also can usually generate or detect an ultrasonic wave into specimens across a small gap. It, therefore can be applied in a noncontact mode with a high degree of reproducibility. Especially stiffness of composites depends on layup sequence of CFRP(carbon fiber reinforced plastics) laminates. It is very important to evaluate the layup errors in prepreg laminates. A nondestructive technique can therefore serve as a useful measurement for detecting layup errors. This shear wave for detecting the presence of the errors is very sensitive. A decomposition model has been used in the interpretation and prediction of test results. Test results have been com pared with model data. It is found that the high probability shows between tests and the model utilized in characterizing cured layups of the laminates. Also a C-scan method was used for detecting layup of the laminates because of extracting fiber orientation information from the ultrasonic reflection caused by structural imperfections in the laminates. Therefore, it was found that interface C-scan images show the fiber orientation information by using two-dimensional fast Fourier transform (2-D FFT).

• Imaging Science in Dentistry
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• v.37 no.1
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• pp.53-59
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• 2007

Purpose : Bone mineral density (BMD) and bone microarchitecture are important determinants for bone strength. Recently micro-CT have provided possibilities for measuring a variety of structural indices to characterize bone microarchitecture. The objective of this study was to compare the BMD and micro-CT parameters with Young's modulus calculated by finite element analysis (FEA) for the evaluation of bone strength. Materials and Methods Bone specimens were obtained from the 18 female rabbits aged 16 weeks. Of those, 36 samples (right and left femur) were selected for 3D micro-CT analysis $(ANT^{TM},\;SKYSCAN,\;Belgium)$ and BMD by PIXlmus 2 (GE Lunar Co. USA). Five microstructural parameters of micro-CT, such as trabecular thickness (Tb.Th), bone specific surface (BS/BV), percent bone volume (BV/TV), structure model index (SMI) and degree of anisotropy (DOA) were studied. Young's modulus was obtained by software program (ANSYS 9.0, ANSYS Inc, Canonsburg, PA) based on micro-CT three dimensional images. Results : Young's modulus assessed by FEA correlated significantly with Tb.Th, BV/TV, BS/BV and SMI respectively. Young's modulus showed higher correlation with these rnicrostructural parameters of micro-CT than BMD. Microstructural parameters except DOA showed significant correlations within the examined group. Conclusion The microarchitectural parameters o( micro-CT and BMD represented some informations in the evaluation of bone strength assessed by FEA.

• Structural Engineering and Mechanics
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• v.66 no.2
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• pp.203-215
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• 2018

A large body of experiments have been conducted to date to evaluate the punching shear strength of flat slab-column connections, but it is noted that only a few of them have been considered for the development of the ACI Code provisions. The limited test results used for the development of the code provisions fall short of predicting accurately the punching shear strength of such connections. In an effort to address this shortfall and to gain an insight into the factors that control the punching shear strength of flat slab-column connections, we report a qualified database of 650 punching shear test results in this article. All slabs examined in this database were tested under gravity loading and do not contain shear reinforcement. In order to justify including any test result for evaluation punching shear database, we have developed an approved set of criteria. Carefully established set of criteria represent the actual characteristics of structures that include minimum compressive strength, effective depths of slab, flexural and compression reinforcement ratio and column size. The key parameters that significantly affect the punching shear strength of flat slab-column connections are then examined using ACI 318-14 expression. The results reported here have paramount significance on the range of applicability of the ACI Code provision and seem to indicate that the ACI provisions do not sufficiently capture many trends identified through regression of the principal parameters, and fall on the unsafe side for the prediction of the punching shear strength of flat slab-column connections.

• Journal of the Korean Ceramic Society
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• v.36 no.7
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• pp.762-766
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• 1999

The crystal structure of A2+(Mg1/3Nb2/3)O3,(A2+=Sr2+ and Ca2+)ceramics was studied usig X-ray diffraction (XRD) and high resolution transmission electrion microscopy(HRTEM). Ba(Mg1/3Nb2/3)O3 (SMN) has the 1:2 ordered monoclinic structure which has the anti-phase tilt of octahedra. The type of tilting in SMN was considered to be a$^{\circ}$a$^{\circ}$c- or a­a­c$^{\circ}$ Ca(Mg1/3Nb2/3)O3 (CMN) also has the 1:2 ordered monoclinic structure which was distorted by the anti-phase tilt or in-phsae tilt of octahedra. A unit cell containing both the in-phase tilt axis and anti-phase tilt axis was not observed in the CMN. Therefore CMN has the mixed phase consisting of the 1:2 ordered monoclinic phase with anti-phase tilt of octahedra and the one with in -phase tilt of ocatahedra,. The anti-parallel shift of cation was also observed in the CMN.