• Journal of Trauma and Injury
• /
• v.24 no.1
• /
• pp.12-17
• /
• 2011

Purpose: A rib fracture secondary to blunt thoracic trauma continues to be an important injury with significant complications. Unfortunately, there are no definite treatment guidelines for severe multiple rib fractures. The purpose of this study was to evaluate the result of early operative stabilization and to find the risk factors of surgical fixation in patients with bilateral multiple rib fractures or flail segments. Methods: From December 2005 to December 2008, the medical records of all patients who underwent operative stabilization of ribs for severe multiple rib fractures were reviewed. We investigated patients' demographics, preoperative comorbidities, underlying lung disease, chest trauma, other associated injuries, number of surgical rib fixation, combined operations, perioperative ventilator support, and postoperative complications to find the factors affecting the mortality after surgical treatment. Results: The mean age of the 96 patients who underwent surgical stabilization for bilateral multiple rib fractures or flail segments was 56.7 years (range: 22 to 82 years), and the male-to-female ratio was 3.6:1. Among the 96 patients, 16 patients (16.7%) underwent reoperation under general or epidural anesthesia due to remaining fracture with severe displacement. The surgical mortality of severe multiple rib fractures was 8.3% (8/96), 7 of those 8 patients (87.5%) dying from acute respiratory distress syndrome or sepsis. And the other one patient expired from acute myocardial infarction. The risk factors affecting mortality were liver cirrhosis, chronic obstructive pulmonary disease, concomitant severe head or abdominal injuries, perioperative ventilator care, postoperative bleeding or pneumonia, and tracheostomy. However, age, number of fractured ribs, lung parenchymal injury, pulmonary contusion and combined operations were not significantly related to mortality. Conclusion: In the present study, surgical fixation of ribs could be carried out as a first-line therapeutic option for bilateral rib fractures or flail segments without significant complications if the risk factors associated with mortality were carefully considered. Furthermore, with a view of restoring pulmonary function, as well as chest wall configuration, early operative stabilization of the ribs is more helpful than conventional treatment for patients with severe multiple rib fractures.

• Journal of Broadcast Engineering
• /
• v.14 no.3
• /
• pp.322-331
• /
• 2009

This paper proposes an efficient data representation of stereo images using edge-based mesh optimization. Mash-based two dimensional warping for stereo images mainly depends on the performance of a node selection and a disparity estimation of selected nodes. Therefore, the proposed method first of all constructs the feature map which consists of both strong edges and boundary lines of objects for node selection and then generates a grid-based mesh structure using initial nodes. The displacement of each nodal position is iteratively estimated by minimizing the predicted errors between target image and predicted image after two dimensional warping for local area. Generally, iterative two dimensional warping for optimized nodal position required a high time complexity. To overcome this problem, we assume that input stereo images are only horizontal disparity and that optimal nodal position is located on the edge include object boundary lines. Therefore, proposed iterative warping method performs searching process to find optimal nodal position only on edge lines along the horizontal lines. In the experiments, we compare our proposed method with the other mesh-based methods with respect to the quality by using Peak Signal to Noise Ratio (PSNR) according to the number of nodes. Furthermore, computational complexity for an optimal mesh generation is also estimated. Therefore, we have the results that our proposed method provides an efficient stereo image representation not only fast optimal mesh generation but also decreasing of quality deterioration in spite of a small number of nodes through our experiments.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.15 no.5
• /
• pp.11-24
• /
• 2011

A real-time hybrid test of a 3 story-3 bay reinforced concrete frame which is divided into numerical and physical substructure models under uniaxial earthquake excitation was run using a fixed iteration implicit HHT time integration method. The first story inner non-ductile column was selected as the physical substructure model, and uniaxial earthquake excitation was applied to the numerical model until the specimen failed due to severe damage. A finite-element analysis program, Mercury, was newly developed and optimized for a real-time hybrid test. The drift ratio based on the top horizontal displacement of the physical substructure model was compared with the result of a numerical simulation by OpenSees and the result of a shaking table test. The experiment in this paper is one of the most complex real-time hybrid tests, and the description of the hardware, algorithm and models is presented in detail. If there is an improvement in the numerical model, the evaluation of the tangent stiffness matrix of the physical substructure model in the finite element analysis program and better software to reduce the computational time of the element state determination for the force-based beam-column element, then the comparison with the results of the real-time hybrid test and the shaking table test deserves to make a recommendation. In addition, for the goal of a "Numerical simulation of the complex structures under dynamic loading", the real time hybrid test has enough merit as an alternative to dynamic experiments of large and complex structures.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.12
• /
• pp.3795-3799
• /
• 2013

The second-order rate constants ($k_N$) have been measured spectrophotometrically for nucleophilic substitution reactions of Y-substituted-phenyl 2-methylbenzoates (6a-e) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. Comparison of the $k_N$ values for the reactions of 4-nitrophenyl 2-methylbenzoate (6d) with those reported previously for the corresponding reactions of 4-nitrophenyl 2-methoxybenzoate (5) reveals that 6d is significantly less reactive than 5, indicating that modification of 2-MeO in the benzoyl moiety of 5 by 2-Me (i.e., $5{\rightarrow}6d$) causes a significant decrease in reactivity. This supports our previous report that aminolysis of 5 proceeds through a six-membered cyclic intermediate, which is highly stabilized through intramolecular H-bonding interactions. The Br${\o}$nsted-type plot for the reactions of 6d with a series of cyclic secondary amines is linear with ${\beta}_{nuc}=0.71$, which appears to be a lower limit of ${\beta}_{nuc}$ for a stepwise mechanism with breakdown of an intermediate ($T^{\pm}$) being rate-determining step (RDS). The Br${\o}$nsted-type plot for the reactions of 6a-e with piperidine is curved, i.e., the slope of Br${\o}$nsted-type plot (${\beta}_{lg}$) decreases from -1.05 to -0.41 as the leaving-group basicity decreases. The nonlinear Br${\o}$nsted-type plot has been taken as evidence for a stepwise mechanism with a change in RDS (e.g., from the $k_2$ step to the $k_1$ process as the leaving-group basicity decreases). Dissection of $k_N$ into the microscopic rate constants associated with the reactions of 6a-e with piperidine (e.g., $k_1$ and $k_2/k_{-1}$ ratio) also supports the proposed mechanism.

• Journal of the Korea Concrete Institute
• /
• v.28 no.2
• /
• pp.177-185
• /
• 2016

This paper concerns the flexural behavior of steel fiber-reinforced ultra-high-performance concrete (UHPC) beams with compressive strength of 150 MPa. It presents experimental research results of hybrid steel fiber-reinforced UHPC beams with steel fiber content of 1.5% by volume and steel reinforcement ratio of less than 0.02. This study aims at investigating of compressive and tensile behavior of UHPC to perform a reasonable prediction for flexural capacity of UHPC beams. Tensile behavior modeling was performed using load-crack mouth opening displacement relationship obtained from bending test. The experimental results show that steel fiber-reinforced UHPC is in favor of cracking resistance and ductility of beams. The ductility indices range from 1.6 to 3.0, which means high ductility of hybrid steel fiber-reinforced UHPC. Test results and numerical analysis results for the moment-curvature relationship are compared. Though the numerical analysis results for the bending capacity of the UHPC beam without rebar is larger than test result, the overall comparative results show that the bending capacity of steel fiber-reinforced UHPC beams with compressive strength of 150 MPa can be predicted by using the established method in this paper.

• Journal of Korean Association for Spatial Structures
• /
• v.8 no.4
• /
• pp.47-55
• /
• 2008

This paper deals with basic theories and some numerical results on structural optimization for geodesic dome. First of all, the space efficiency of geodesic dome is investigated by using the ratio of icosahedron's surface area to the internal volume enclosed by it. The procedure how to create the geodesic dome is also provided in systematic way and implemented and utilized into the design optimization code ISADO-OPT. The mathematical programming technique is introduced to find out the optimum pattern of member size of geodesic dome against a point load. In this study, total weight of structure is considered as the objective function to be minimized and the displacement occurred at loading point and member stresses of geodesic dome are used as the constraint functions. The finite difference method is used to calculate the design sensitivity of objective function with respect to design variables. The SLP, SQP and MFDM available in the optimizer DoT is used to search optimum member size patterns of geodesic dome. It is found to be that the optimum member size pattern can be efficiently obtained by using the proposed design optimization technique and numerical results can be used as benchmark test as a basic reference solution for design optimization of dome structures.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• v.22 no.2
• /
• pp.217-232
• /
• 2000

The author studied on the 128 cases of benign odontogenic tumors which had been diagnosed with biopsy during the period of Jan. 1989 to Dec. 1998 at the Kyungpook National University Hospital, Yeungnam University Medical Center, Keimyung University Dongsan Medical Center, and Taegu Catholic Medical Center. This study contained the clinicostatistical analysis of the frequency in relation to sex, age, locations, chief complaints, duration, radiographic findings, recurrence, teeth, and treatment methods. The results were as follow : 1. Of a total of 128 benign odontogenic tumors, ameloblastomas(57 cases; 44.5%) and odontomas (44 cases ; 34.4%) mostly occupied. The other types of lesions were 8 calcifying odontogenic cysts, 7 benign cementoblastomas, 4 myxomas, 3 adenomatoid odontogenic tumors, 2 calcifying epithelial odontogenic tumors, 2 ameloblastic fibro-odontomas, and 1 odontogenic fibroma. 2. In age and sex distribution, benign odontogenic tumors occured slightly more often in males(53.9%) than females(46.1%) and the majority of cases(79.7%) were found during 2nd, 3rd, and 4th decade. 3. There was a predilection for mandibular lesions(mandible-maxilla ratio, 2.6 : 1). 4. The most common chief complaint was swelling(29.7%) and in respect to duration, the cases less than 1 year(50.0%) mainly appeared. 5. There were 7 cases(13.0%) of recurrence on ameloblastoma and there was no recurrence in the others. 6. In Ameloblastoma It commonly occured during 3rd and 4th decade(59.6%) and mean age was 30.2 years. The majority of cases were occurred in mandible(96.5%) , especially mandibular molar and angle area(71.9%). The most common chief complaint was swelling(47.4%) and in respect to duration, the cases less than 1 year(52.6%) mainly appeared. In relation to teeth, there were resorption of root(52.6%), displacement of teeth(31.6%), and in relation to impacted teeth(43.9%). There was higher recurrence rate in the cases by conservative treatment(14.7%) than radical treatment(10.0%). As regards radiographic findings, conservative treatments were prevalent in the cases of unilocular type(85.7%) as compared with multilocular type(48.5%). and there was higherrecurrence rate in the cases of multilocular type(18.2%) than unilocular type(4.8%). As regards the type of treatment in relation to age, conservative treatments were prevalent in patients younger than 20 years of age. 7. In Odontomas It commonly occured during 2nd decade(50.0%) and in maxillary anterior teeth(40.9%). The most common chief complaint was delayed retention and permanent impaction of teeth(72.7%), and most frequently associated with impacted teeth(79.5%).

• Journal of the Korea Concrete Institute
• /
• v.15 no.4
• /
• pp.513-521
• /
• 2003

Existing tests results have shown that confining the concrete compression region with closed stirrups improves the ductility and load-carrying capacity of beams. However, only few researchers have attempted to utilize the beneficial effects of the presence of these stirrups in design. This paper presents the result of experimental studies on the load-deflection behavior and the strengthening effect of laterally confined structural high-strength concrete beam members in which confinement stirrups have been introduced into the compression regions. Fifteen tests were conducted on full-scale beam specimens having concrete compressive strength of 41 MPa and 61 MPa. Different spacing of stirrups(0.25∼1.0d) and amount of tension steel($0.55{\sim}0.7{\rho}_b$) as major variables were investigated. And also, this study present an appropriate shear equation for decision of ultimate failure modes of high-strength concrete beams according to stirrup spacing. The equation is based on interaction between shear strength and displacement ductility. Prediction of failure mode from presented method and comparison with test results are also presenteded

• Journal of the Korea Concrete Institute
• /
• v.25 no.3
• /
• pp.261-269
• /
• 2013

In this study, it was developed eco-friendly inorganic binding material concrete using ground granulated blast furnace slag and alkali activator (water glass, sodium hydroxides). Eight reinforced concrete beam using inoganic binding material concrete were constructed and tested under monotonic loading. The major variables were mixture ratio of alkali activator, type of admixture and admixture. Experimental programs were carried out to improve and evaluate the flexural performance of such test specimens, such as the load-displacement, the failure mode, the maximum load carrying capacity, and ductility capacity. All the specimens were modeled in scale-down size. The eco-friendly concrete using inorganic binding material encouraged alkali activation reaction was rapidly hardening speed and showed possibility as a high strength concrete. Also, the RC beams using new materials showed similar behavior and failed similarly with RC beam used portland cement. It is thought that eco-friendly inorganic binding material concrete can be used with construction material and product as a basic research to replace cement concrete. If there is application to structures in PC member as well as production of 2nd concrete product, it could be improved the productivity and reduction of construction duration etc.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.5
• /
• pp.397-403
• /
• 2016

During the rapid economic growth in Korea since the 1970s, many underground facilities were constructed such as under passes and railways. Seismic design has been mandated in 1988, but the structures built before 1988 were not reflected on the seismic design. Accordingly, these underground structures require effective seismic reinforcing methods to ensure safety when the earthquake happens. By these reasons, in this study, using the proposed pre-flexed members, RC box structure was analyzed for seismic reinforcement of the corner. This method is based on a principle that enlarging the resistance against the external force by installing the pre-flexed member to the box structure corner. To evaluate validity, a newly developed member with CornerSafe was compared with traditional type reinforcement using experiments and finite element analysis. In finite element mode, nonlinearity of steel was modeled based on J2 plasticity model and concrete was based on CEB FIP MODEL CODE 1990. Also, composite ratios of box and pre-flexed member were computed for design application. The reinforcement and box structure were analyzed under the bond condition completely attached by the tie, and the results of experiment and finite element analysis were same in the force-displacement curve.