• Computational Structural Engineering
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• v.10 no.4
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• pp.303-313
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• 1997

Though many techniques for the damage assessment of structures have been studied recently, most of them can be only applied to simple structures. Therefore, practical damage assessment techniques that evaluate the damage location and the damage state for large structures need to be developed. In this study, a damage assessment technique using a neural network is developed, in which the bilevel damage assessment procedure is proposed to evaluate the damage of a large structure from the limited monitoring data. The procedure is as follows ; first, for the rational selection of damage critical members, the members that affect the probability of failure or unusual structural behavior are selected by sensitivity analysis. Secondly, the monitoring points and the number of sensors that are sensitive to the damage severity of the selected members are also selected through the sensitivity analysis with a proposed sensitivity measurement format. The validity and applicability of the developed technique are demonstrated by various examples, and it has been shown that the practical information on the damage state of the selected critical members can be assessed even though the limited monitoring data have been used.

• Structural Engineering and Mechanics
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• v.31 no.2
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• pp.137-152
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• 2009

Mechanic behavior of Y-shape thin-walled box girder bridge structure is complex, so one can not exactly hold the mechanical behavior of the Y-shape thin-walled box girder bridge structure through general calculation theory and analytical method. To hold the mechanical behavior better, based on elementary beam theory, by increasing the degree of freedom analytical method, taking account of restrained torsiondistortion angledistortion warp and shearing lag effect at the same time, authors obtain a thin-walled box beam analytical element of 10 degrees of freedom of every node, derive stiffness matrix of the element, and code a finite element procedure. In addition, authors combine the obtained procedure with spatial grillage analytical method, meanwhile, they build a new analytical method that is the spatial thin-walled box girder element grillage analysis method. In order to validate the precision of the obtained analysis method, authors analyze a type Y-shape thin-walled box girder bridge structure according to the elementary beam theory analytical method, the shell theory analytical method and the spatial thin-walled box girder element grillage analysis method respectively. At last, authors test a type Y-shape thin-walled box girder bridge structure. Comparisons of the results of theory analysis with the experimental text show that the spatial thin-walled box girder element grillage analysis method is simple and exact. The research results are helpful for the knowledge of the mechanics property of these Y-shape thin-walled box girder bridge structures.

• Smart Structures and Systems
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• v.25 no.6
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• pp.719-732
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• 2020

Real-time hybrid simulation (RTHS) which combines physical experiment with numerical simulation is an advanced method to investigate dynamic responses of structures subjected to earthquake excitation. The desired displacement computed from the numerical substructure is applied to the experimental substructure by a servo-hydraulic actuator in real time. However, the magnitude decay and phase delay resulted from the dynamics of the servo-hydraulic system affect the accuracy and stability of a RTHS. In this study, a robust stability analysis procedure for a general single-degree-of-freedom structure is proposed which considers the uncertainty of servo-hydraulic system dynamics. For discussion purposes, the experimental substructure is a portion of the entire structure in terms of a ratio of stiffness, mass, and damping, respectively. The dynamics of the servo-hydraulic system is represented by a multiplicative uncertainty model which is based on a nominal system and a weight function. The nominal system can be obtained by conducting system identification prior to the RTHS. A first-order weight function formulation is proposed which needs to cover the worst possible uncertainty envelope over the frequency range of interest. Then, the Nyquist plot of the perturbed system is adopted to determine the robust stability margin of the RTHS. In addition, three common delay compensation methods are applied to the RTHS loop to investigate the effect of delay compensation on the robust stability. Numerical simulation and experimental validation results indicate that the proposed procedure is able to obtain a robust stability margin in terms of mass, damping, and stiffness ratio which provides a simple and conservative approach to assess the stability of a RTHS before it is conducted.

• Journal of the Ergonomics Society of Korea
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• v.28 no.4
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• pp.117-124
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• 2009

To inspect the quality of data collected from a large-scale body measurement and investigation project, it is necessary to establish a proper data editing process. The three-dimensional body measurement may have measuring errors caused from measurer's proficiency or changes in the subject's posture. And it may also have errors caused in the process of algorithm expressing the information obtained from the three-dimensional scanner into numerical values, and in the course of data-processing dealing with numerous data for individuals. When those errors are found, the quality of the measured data is deteriorated, and they consequently reduce the quality of statistics which was conducted on the basis of it. Therefore this study intends to suggest a new way to improve the quality of the data collected from the three-dimensional body measurement by proposing a working procedure identifying data errors and correcting them from the whole data processing procedure-collecting, processing, and analyzing- of the 2004 Size Korea Three-dimensional Body Measurement Project. This study was carried out into three stages: Firstly, we detected erroneous data by examining of logical relations among variables under each edit rule. Secondly, we detected suspicious data through independent examination of individual variable value by sex and age. Finally, we examined scatter-plot matrix of many variables to consider the relationships among them. This simple graphical tool helps us to find out whether some suspicious data exist in the data set or not. As a result of this study, we detected some erroneous data included in the raw data. We figured out that the main errors are not because of the system errors that the three-dimensional body measurement system has but because of the subject's original three-dimensional shape data. Therefore by correcting some erroneous data, we have enhanced data quality.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.4
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• pp.515-525
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• 1994

Impression taking is a very important procedure in complete denture fabrication for reproduction of the tissue surface from which obtain retention and support of denture base. Therefore, we can not construct retentive denture without precise impression taking. Retention in complete denture can be obtained by the closest contact between denture base and underlying tissue, maximum coverage and proper displacement of the border tissue for peripheral sealing. Therefore, it is very important to take impression of the border tissue displaced properly. Nowadays, impression of the border tissue is mainly taken by the border molding techniques by means of manual muscle trimming, but due to various muscle trimming methods as clinicians, it is difficult to select proper method. This technique is also bodersome to do and time-consuming procedure. Retention is also likely reduced, because of the recording excessive muscle movement than actural physiological border tissue movement. Therefore, the impression technique that records actual physiologic functional muscle movement is helpful to increase denture retention and easy to do. We named this technique a functional border molding technique. This technique is originally introduced by D. J. Neill and R. I. Nairn in 1968. We tried to fabricate complete denture by the impression by means of functional border molding technique for better retention and the convenience, and obtained good results.

• Analytical Science and Technology
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• v.17 no.4
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• pp.302-307
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• 2004

Determination of actinides in the environmental sample requires separation of each element. This procedure is tedious and time consuming. And also, the detection limits of some nuclides using alpha spectrometry are rather higher. To overcome the lower detection limit and complicated separation procedure, a simple analytical technique for the determination of actinide isotopes in the environmental samples was developed and applied to IAEA and NIST reference sediment samples. For the separation of actinides from matrix, anion exchange resin and TRU-spec extraction chromatography resin were used and chemical yields were obtained using natural uranium, thorium, $^{242}Pu$ and $^{243}Am$ tracers. For overcoming the higher detection limits of U and Th in alpha spectrometry, neutron activation analysis was applied. Using combined method, the detection limit was increased about 10 times. The activity values of each isotope were consistent with the reference values reported by IAEA and NIST.

• Nuclear Engineering and Technology
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• v.5 no.3
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• pp.202-213
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• 1973

In a continuation of the 1st series of these studies, a separation of the components in organic phases obtained from Szilard Chalmer reactions of aromatic chloro derivatives was attempted to clarify the conditions of isolating the main component. Though it was unable to isolate all constituents of organic phases, the main component was well isolated by means of a simple distillation or a thin layer chromatography. It was identified that the main component was a recombined product of the recoiled $^{38}$ Cl atom with the original sample. In cases of solid samples the main component amounted about 80-60% of the radio activity of the organic phase, whereas the main component from liquid samples gave less than 70% of the radio activity of the organic phase. A prolonged irradiation could increase the yield of a main component, but it was, in case of a radiation senintive compound, decreased as the irradiation is extended. The number of aide produets separated from an organic phase of a liquid sample was greater than that of a solid sample, and hence the main component of a solid sample was isolated easier. The overall fields of the labelled main products of 22 kinds of compounds were listed and a procedure of the separation of the main component by a thin layer chromatograply was proposed and evaluated. The feasibility of the present procedure for labelling purpose was also reviewed with respects to the chemical structure of a compound.

• Archives of Plastic Surgery
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• v.32 no.5
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• pp.555-560
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• 2005

The nose is shaped as a pyramid and is the most prominent portion of the face. Nasal bone fractures are thus more frequent than those of the maxilla and zygoma. Whether the nasal bone fractures are corrected or not due to unnecessity of surgical treatment, the incidence of posttraumatic deformity occurs frequently. In Asian patients, even the corrected noses look low-lying and flat. To resolve these problems, we corrected the posttraumatic deformity of the nose with a combined procedure of nasal ostectomy and augmentation rhinoplasty. From 2000 to 2004, this procedure was performed in fifteen patients with posttraumatic nasal deformity. There were four female and eleven male patients with an average age of 32 years(range 19 to 52 years). All patients had previous trauma history. Of these, closed reduction was performed on 13 patients and no treatment was 2 patients. The deformed noses were corrected through lower columellar incision, by ostectomy or osteomy, and augmentation with silicone implant. We gained satisfactory results of correcting the deformed noses, except one case with implant deviation. Our method for the correction of traumatic nasal deformity proves to be simple and safe. The camouflage effect with silicone implant overcomes an unsatisfactory correction and brings a excellent cosmetic results.

• Archives of Reconstructive Microsurgery
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• v.19 no.2
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• pp.81-87
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• 2010

In surgical treatment of the malignant melanoma, radical resection and a sentinel lymph node biopsy are essential procedures to eradicate the tumor and to minimize the risk of local recurrence. For the reconstruction of skin defect after tumor resection, a skin graft has been generally performed procedure. However, if tendon or bone is exposed after tumor resection, simple skin graft is not enough for the coverage of the defect and additional procedure is mandatory. In this study, we reviewed the clinical results of 16 patients, who had been diagnosed with malignant melanoma of the limb and underwent surgical resection and reconstruction of the defect with various methods. The sentinel lymph node dissection was performed in all patients combined with radical excision of the tumor. In 11 cases of positive sentinel lymph nodes, further elective lymph node dissections were performed. The mean tumor invasion depth was 4.54 mm (2~10 mm), and AJCC stage II was most common (9 cases). The pedicled flaps were performed in 10 cases for the reconstruction of defects. All flaps were successfully survived without significant complications until the last follow up. In conclusion, a pedicled flap coverage is very useful reconstruction strategy for the soft tissue defects after radical resection of malignant melanoma.

• Archives of Craniofacial Surgery
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• v.14 no.1
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• pp.16-23
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• 2013

Background: Even though degrees of deformation of microform cleft lip are not high, it has to be corrected with various procedures upon conditions and areas since it has various expressions. Many studies have focused on the classifications and procedures, but there are only a few studies on how much these procedures are performed in the actual field. This study aims to analyze the utilization of various procedures upon major correction points. Methods: A total of 52 patients who had been corrected by one surgeon from 1995 to 2011 were enrolled as subjects. Based on the medical records, it was checked whether the incision was made or not along with the correction procedures for alar base and philtral column, Cupid's bow, and vermillion free margin. Results: In case of an incision, full incision (42 times) was conducted most frequently. For alar base and philtral column, muscle re-approximation (25 times) was performed most frequently. However, recently, it was shown that excision on only the affected area and correction with dermis were more likely to be used. For Cupid's bow and vermilion free margin, elliptical excision on the only affected area followed by re-approximation was performed most frequently for 46 times (Cupid's bow) and 44 times (vermilion free margin), respectively. Conclusion: For the correction of microform cleft lip, less invasive procedures are preferred. However, in the actual field, if needed, aggressive procedures consisting of incisions have been conducted to correction. These trends are somewhat changed to utilization of a simple procedure, such as excision on the modified area, followed by a re-approximation rather than complicated procedures using the muscle.