• Journal of Korean Neurosurgical Society
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• v.59 no.4
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• pp.368-373
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• 2016

Objective : Delayed hinge fracture (HF) that develops after cervical open door laminoplasty can be a source of postoperative complications such as axial pain. However, risk factors related to this complication remain unclear. We performed a retrospective clinical series to determine risk factors for delayed HF following plate-only open-door cervical laminoplasty. Methods : Patients who underwent plate-only open-door laminoplasty and had available postoperative computed tomography (CT) scans (80 patients with 270 laminae) were enrolled. Hinge status, hinge gutter location, open location, hinge width, number of screws used, operation level, and open angle were observed in the CT to determine radiographic outcome. Demographic data were collected as well. Radiographic and clinical parameters were analyzed using univariate and multivariate logistic regression analysis to determine the risk factors for HF. Results : Univariate logistic regression analysis results indicated poor initial hinge status, medially placed hinge gutter, double screw fixation on the elevated lamina, upper surgical level, and wide open angle as predictors for HF (p<0.05). Initial hinge status seemed to be the most powerful risk factor for HF (p=0.000) and thus was collinear with other variables. Therefore, multivariate logistic regression analysis was performed excluding initial hinge status, and the results indicated that medially placed hinge gutter, double screw fixation on the elevated lamina, and upper surgical level were risk factors for HF after adjustment for other confounding factors. Conclusion : To prevent HF and to draw a successful postoperative outcome after cervical laminoplasty, surgical and clinical precautions should be considered.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.432-437
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• 2010

A new device injecting secondary fuel behind flameholder was invented and tested in order to reduce low frequency combustion instability of combustor using V-gutter flameholder. Specially designed combustion device could make large combustion instability up to 180 dB successfully, and newly invented device made a success to reduce 110~120Hz low frequency pressure pulsation up to 84%. It was found that the fuel flow rate of secondary fuel supplying behind flameholder was the only parameter which dominates reduction of instability. It is considered that stabilized flame with sufficient secondary fuel can lead to break the connection between combustion system and acoustic system due to independence of flame from fluctuation of main fuel resulted from synchronization with acoustic wave.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.961-968
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• 2006

Curbs and L-type gutters installed at the edge of a road are very important structures to protect pedestrians from traffic accidents and to restraint slip of cars due to rain. However, existing construction method where great parts of the construction progress are done by human power has many problems in workability, quality and cost etc. In this paper, a new construction method for improvement in workability and quality for curbs and L-type gutters is developed. In order to investigate the structural safety and quality of curbs and gutters installed by the new method, tensile and lateral load tests are performed on curbs installed by existing and new methods and uniaxial compression tests are also performed on concrete samples of gutters constructed by existing and new methods. The test results show that the alignment of curbs and the strength of gutter concrete are very much improved by applying the new method. The tensile and lateral load capacities of the curbs installed by the new method are 10.7 and 2.5 times higher than those of curbs by existing method, respectively.

• Ecology and Resilient Infrastructure
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• v.8 no.4
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• pp.223-232
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• 2021

In general, stormwater flows to the road surface, especially in urban areas, and it is discharged through the drainage grate inlets on roads. The appropriate evaluation of the road drainage capacity is essential not only in the design of roads and inlets but also in the design of sewer systems. However, the method of road surface flow analysis that reflects the topographical and hydraulic conditions might not be fully developed. Therefore, the enhanced method of road surface flow analysis should be presented by investigating the existing analysis method such as the flow analysis module (uniform; varied) and the flow travel time (critical; fixed). In this study, the algorithm based on varied and uniform flow analysis was developed to analyze the flow pattern of road surface. The numerical analysis applied the uniform and varied flow analysis module and travel time as parameters were conducted to estimate the characteristics of rainfall-runoff in various road conditions using the developed algorithm. The width of the road (two-lane (6 m)) and the slope of the road (longitudinal slope of road 1 - 10%, transverse slope of road 2%, and transverse slope of gutter 2 - 10%) was considered. In addition, the flow of the road surface is collected from the gutter along the road slope and drained through the gutter in the downstream part, and the width of the gutter was selected to be 0.5 m. The simulation results were revealed that the runoff characteristics were affected by the road slope conditions, and it was found that the varied flow analysis module adequately reflected the gutter flow which is changed along the downstream caused by collecting of road surface flow at the gutter. The varied flow analysis module simulated 11.80% longer flow travel time on average (max. 23.66%) and 4.73% larger total road surface discharge on average (max. 9.50%) than the uniform flow analysis module. In order to accurately estimate the amount of runoff from the road, it was appropriate to perform flow analysis by applying the critical duration and the varied flow analysis module. The developed algorithm was expected to be able to be used in the design of road drainage because it was accurately simulated the runoff characteristics on the road surface.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.5
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• pp.53-58
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• 2008

This study presented a design model optimizing a distance of inlet with drainage pipe laid under the gutter in road. When the distance of inlet changed, a basin for the gutter divided by the distance of inlet and the inflow coming into the gutter would be changed. In this case, the change of inlet distance causes the change of a diameter of drainage pipe and slope because of the change of capacity. Therefore, the optimization is needed to design the combination of them for the distance of inlet. Genetic Algorithm is used to determine the optimal combination of them. The conditions of road and the precipitation were assumed like a real and the range of inlet distance adopted $10{\sim}30\;m$ which has been introduced in domestic. This model presented the optimal distance of inlet and the combination of pipe and slope through the minimum cost. The result of the study is that the optimal distance of inlet is different from each slope of road and it can reduce about 20% of total cost for the distance of inlet.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.6A
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• pp.525-534
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• 2010

A road curbstone is a structure installed at the boundary of the sidewalk and the street with the objectives of road drainage, drawing attention and such. The current general construction method of curbstones places foundation concrete for the curbstones first, waits until the concrete reaches the strength to support the curbstones, places the curbstones on top, and then places the gutter and rear filling concrete. Such method has the issues of poor compaction and weakened bond strength of concrete due to split placing of concrete, and causes the curbstones to easily separate due to vehicle impact or earth pressure, in turn creating maintenance costs and spoiling the aesthetics. To improve such conventional construction methods, an all-in-one method was developed using formwork rail and jig where both the curbstones and gutter can be worked at the same time, and to evaluate the structural performance, static tests of lateral loading test, pullout test, and bending test were executed, and dynamic tests such as pendulum test and actual vehicle impact test were executed. In all tests, the all-in-one construction method using formwork rail and jig was shown to be superior to the conventional construction method by the increase of construction quality and bond strength of concrete.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.305-306
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• 2007

• Magazine of RCR
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• v.4 no.3
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• pp.41-44
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• 2009

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.237-240
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• 2015

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.83-87
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• 2009

Ramjet engine is weak for low frequency combustion instability because of their long air flow passage. A model combustor which has fuel injector and V-gutter shaped flame holder was designed and fabricated in order to simulate a combustion mechanism of ramjet engine, and it could demonstrate combustion instability which might occur in ramjet combustor. The frequency of the instability was very similar to that of acoustic resonance frequency of combustor, and it proved that a typical combustion instability by thermo-acoustic coupling occurred.