• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.5
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• pp.604-610
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• 2018

Recently, due to the rapid growth of the leisure industry, demand for small-scale flotation and mooring pontoon platforms has been increasing rapidly. Standard rules for the design and structural safety of such structures have become necessary. This paper provides criteria that can be referenced when designing pontoon platforms, and also introduces structural safety evaluation procedures. In this study, the structural safety and stability of a 15-meter pontoon platform were investigated through structural design and finite element analysis. For platforms of less than 10 meters in length, a simple structural calculation can be used, but for platforms over 10 meters, a detailed structural strength review must be considered to meet safety guidelines defined in existing regulations. The structural strength of the initial design was examined and its structural safety was verified. For future research, it is an evaluative system was developed that can be used to examine the various loading conditions during design.

• The Journal of Engineering Geology
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• v.18 no.4
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• pp.433-437
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• 2008

It's essential to build an earth retaining structure at the beginning and end point of a tunnel constructed in a colluvium area. A large scale of colluvial soil may cause a problem to the stability of the excavation ground. An excavation in colluvium has different behavior characteristics from those in a sandy soil due to unstable elements and needs counter measures for it. There are few systematic research efforts on the behavior characteristics of an earth retaining structure installed in colluvial soil. Thus this study set out to collect measuring data from an excavation site at the tunnel pit mouth in colluvium and set quantitative criteria for the safety of an earth retaining structure. After comparing and analyzing the theoretical and empirical earth pressure from the measuring data, the lateral earth pressure distribution acted on the earth retaining wall was suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.188-200
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• 2019

The purpose of this study is to extend the research on the development of the performance indicators for the Education Welfare Priority Support Project and to secure the content validity for the application to the school site. The performance index of the Education Welfare Priority Support Project used in this study was originally consisted of 6 area, 33 sub-area, and 233 items. Two expert meetings were held for five doctoral professionals in the field of educational welfare. Delphi surveys were conducted for a group of 99 educational welfare workers who worked at the site for more than five years. The item selection criteria ($CVR{\geq}.29$, $CVI{\geq}.80$, convergence <.50, agreement ${\geq}.05$, stability ${\leq}.80$, $M{\geq}3.00$, SD <.80, reliability ${\geq}.6$) were applied. The 6 area, 23 sub-areas, and 93 items were verified and finally 90 items were selected from removing 3 items with low level of reliability. Providing suggestions and follow-up studies for the better use of the performance indicators for the Education Welfare Priority Support Project in the field.

• Journal of the Korean Geotechnical Society
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• v.24 no.10
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• pp.105-111
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• 2008

To improve the stability of levee structure, it is required to use good quality fill materials, intensive management, appropriate hydraulic structure and construction of cut-off wall. In particular, the most important factor of levee construction technology is to use bed sediment for its safety. In this study, seepage model test and numerical analysis were performed based on a standard section of levee recommended in the river design standard of korea (2005). The results of test and analysis show that most of the bed soil is a sand (SP in USCS), which does not satisfy the permeability criteria for levee materials ($< k=10^{-3}cm/sec$), thus for the safety of levee it is required to adopt a stabilizing method such as good quality soil mixing, water content control.

• International Journal of Highway Engineering
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• v.10 no.1
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• pp.1-9
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• 2008

Five bases for of highways are sight distance, vehicle stability, driver comfort, drainage and aesthetics. Among these bases, the sight distance is the most critical one in the highway alignment design. It is certain that highways and drivers' observation actions are 3-dimensional in nature. But, the highway alignment design and the sight distance analysis have been performed on 2-dimensional planes because of various constraints and complexity of calculating 3-dimensional sight distance. The purpose of this study is to derive a model for determining exact available sight distance in 3-D combined horizontal and vertical alignments. Application of the model is illustrated using numerical examples. The proposed model should be useful in quantifying the criteria for 3-D highway alignments.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.75-82
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• 1987

It is the objective of this study to estimate J-integral by numerical analysis, in which J-integral as aparameters in fracture mechanics can be used to evaluate unstable ductile fracture which is a important problem with respect to structural stability when the scope is beyond small scale yielding criteria. For this, 8-node isoparametric singular element as crack tip element of a cracked material was used to solve plastic blunting phenomenon at crack tip, and crack opening was forced to start when J-value was exceeding fracture toughness $J_{IC}$ of the material. And crack propagation behaviour was treated by using crack opening angle. From this study, it was shown that crack opening, stable propagation and unstable opening point of the cracked material found by using J-value obtained from this study were accord with the other study, so think, J-value obtained from this study can be directly used as a parameter in fracture mechanics to deal with the problem of stable propagation of crack and unstable ductile fracture.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.175-181
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• 2016

In this paper, the liquid air was selected as the refrigerant in artificial ground freezing to be used for rapid ground freezing and to reduce the risk of suffocation and the applicability of liquid air was verified. In order to evaluate the stability of the liquid air, the oxygen concentration of mixtures with liquid nitrogen and liquid oxygen was experimentally examined to meet the oxygen concentration criteria in the Occupational Safety and Health Act. In addition, the effects of the mixture ratio of liquid nitrogen and liquid oxygen, pressure and flow rate change in the storage vessel on the oxygen concentration in the liquid air were investigated. As a result, the ratio of liquid nitrogen and liquid oxygen 8: 2 was shown to meet the oxygen concentration standards. Pressure and flow rate change in the storage vessel did not have significant effects on the oxygen concentration in the liquid air.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.313-336
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• 2007

Unlike a conventional railway system, a high-speed rail system experiences various aerodynamic problems in tunnel sections. Trains running at a high speed in a small tunnel, when compared with the open field, face significant air pressure, resulting in reduced operating stability and fast change in pressure inside the tunnel. These phenomena further cause some unexpected problems such as the passengers onboard feeling an aural discomfort and an impulsive noise at the tunnel exit. To solve these problems, this paper introduces analysis of aerodynamic characteristics for determination of tunnel cross section. The optimum cross-section that satisfies the criteria of aural discomfort was reviewed through lots of numerical simulation analysis. Also, the pressure inside the passenger car of a train operating on Kyungbu HSR line was measured, and the pressure inside the tunnel and the micro-pressure waves at tunnel exit were measured at Hwashin 5 Tunnel. At the same time, a test of train operation model was performed and then the measurement results and test results were compared to verify that various parameters used as input conditions for the numerical simulations were appropriate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.1
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• pp.73-80
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• 2019

Traffic Safety and efficient Road Traffic Policy of Traffic management came into effect over the certain size of the road like main road. Comparatively, Safety for Living street is deteriorated. Especially, Vehicle are usually priority to the life-zone street, even though Safety for the Passengers are essential to the life-zone street in the residential area. Improvement for the Living street has not been achieved In this study, To suggest Intersection Notifications standard of installation in Living Street, We execute on-site survey in priority to Gwangju Metropolitan City. Furthermore, After We suggest experimental value for the Intersection Notifications' standard of installation Prediction model in the Living street, Intersection Notifications compare & veritfy experimental value to the installation point's value to suggest the standard of installation in the living street. As a result, We can prevent frequent traffic accident in the Living Street. Furthermore, We are judged by installation of intersection Notifications considering stability and convenience to the passengers who are using the living street.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.7
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• pp.2257-2285
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• 2022

Cyber-physical systems (CPS) have been growing exponentially due to improved cloud-datacenter infrastructure-as-a-service (CDIaaS). Incremental expandability (scalability), Quality of Service (QoS) performance, and reliability are currently the automation focus on healthy Tier 4 CDIaaS. However, stable QoS is yet to be fully addressed in Cyber-physical data centers (CP-DCS). Also, balanced agility and flexibility for the application workloads need urgent attention. There is a need for a resilient and fault-tolerance scheme in terms of CPS routing service including Pod cluster reliability analytics that meets QoS requirements. Motivated by these concerns, our contributions are fourfold. First, a Distributed Non-Recursive Cloud Model (DNRCM) is proposed to support cyber-physical workloads for remote lab activities. Second, an efficient QoS stability model with Routh-Hurwitz criteria is established. Third, an evaluation of the CDIaaS DCN topology is validated for handling large-scale, traffic workloads. Network Function Virtualization (NFV) with Floodlight SDN controllers was adopted for the implementation of DNRCM with embedded rule-base in Open vSwitch engines. Fourth, QoS evaluation is carried out experimentally. Considering the non-recursive queuing delays with SDN isolation (logical), a lower queuing delay (19.65%) is observed. Without logical isolation, the average queuing delay is 80.34%. Without logical resource isolation, the fault tolerance yields 33.55%, while with logical isolation, it yields 66.44%. In terms of throughput, DNRCM, recursive BCube, and DCell offered 38.30%, 36.37%, and 25.53% respectively. Similarly, the DNRCM had an improved incremental scalability profile of 40.00%, while BCube and Recursive DCell had 33.33%, and 26.67% respectively. In terms of service availability, the DNRCM offered 52.10% compared with recursive BCube and DCell which yielded 34.72% and 13.18% respectively. The average delays obtained for DNRCM, recursive BCube, and DCell are 32.81%, 33.44%, and 33.75% respectively. Finally, workload utilization for DNRCM, recursive BCube, and DCell yielded 50.28%, 27.93%, and 21.79% respectively.