• International Journal of Ocean System Engineering
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• 제2권3호
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• pp.170-175
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• 2012

Currently, most logistics use containers. The construction of new port and high speed medium size container ship for the transportation of merchandise have become very important. The problem of ship stability is also important because of its direct influence on the loss of human life, ships, and merchandise. The stability of a container ship during its operation is not a large problem because it is well considered in the design process. However, the assessment of ship stability during container loading/unloading in port still depends on the expertise of experienced personnel. In this paper, a model based simulation system is introduced, which is able to assess ship stability during container loading/unloading, using ENVISION, a general purpose simulation system.

• Coupled systems mechanics
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• 제7권2호
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• pp.141-162
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• 2018

This work presents a novel model for analysis of the loading rate influence onto structure response. The model is based on the principles of nonlinear system dynamics, i.e., consists of a system of nonlinear differential equations. In contrast to classical linearized models, this one comprises mass and loading as integral parts of the model. Application of the Kelvin and the Maxwell material models relates the novel formulation to the existing material formulations. All the analysis is performed on a proprietary computer program based on Wolfram Mathematica. This work can be considered as an extended proof of concept for the application of the nonlinear solid model in material response to dynamic loading.

• KIEAE Journal
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• 제7권5호
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• pp.143-148
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• 2007

The application of metal deck floor system is increasing gradually and especially for office buildings. In the cases of large parking structures and storage structures, the construction period and the cost can be reduced. Also the steel deck system can prevent the crack of a floor and reduce the retrofit expenses. However, the floor should stand for the repeated truck load which is relatively heavier repeated loading. The mechanical behavior of a slab under repeated load is also different from the static loading state. An evaluation of a structural capacity was performed in this study through the dynamic capacity evaluation experiment for an application of a composite deck floor system as a parking structure slab. The period of repeated loadings were set up as 25years and 960,000 times monotone cyclic loads were applied at the center of the specimens. The tension crack propagation and patterns at the center of specimens were examined.

• 대한기계학회논문집A
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• 제31권10호
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• pp.1031-1038
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• 2007

A study on the development of control loading system for a pilot command in the helicopter flight training device is performed. The key issue of the device is how to provide closely the real feeling of the stick forces to the trainer during the flight training. Focusing on this proviso and considering the suitable approach than the complexity of the hydraulic system, we adopt the AC servo motor system although its inherent disadvantages such as the torque ripple and the stick-slip friction effect at a low control force. However, we overcome these detrimental effects by introducing the appropriate control device and the robust structural design of the actuating system, thereby the feasibility and applicability to the system can be obtained by showing good performance, meeting the required specification.

• 한국농공학회논문집
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• 제46권5호
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• pp.131-139
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• 2004

In this study, on-site sewage treatment tests were conducted using the Absorbent Biofilter System (ABS) under different hydraulic loading rates to examine its treatment characteristics and efficiencies and to determine its feasibility as a small on-site sewage treatment system in a rural area. Results showed that the removal rates of BOD and SS were satisfactory at hydraulic loading rates of 100~150 cm/day, meeting the Korean effluent water quality standards for the riparian zone (10 mg/L). In the case of nutrients (N, P), however, the system did not perform well, necessitating further improvement for nutrient removal. A comparative analysis indicated that as a small on-site sewage treatment system, the ABS would be more suitable than other treatment systems in terms of performance stability, maintenance requirement, and cost-effectiveness and could be applied as an alternative treatment system in Korean rural areas.

• 한국항해항만학회지
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• 제29권4호
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• pp.305-312
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• 2005

Pick-up/delivery of consumer goods to offices, shops, and restaurants in order to support urban lives is one of the most vital activities in a city. With economic growth and technological innovation, a greater variety of goods have come to be supplied, and pick-up/delivery of consumer goods has become more complex. Efficient urban goods movement in Central Business District(CBD} starts with an efficient system for loading/unloading, and pick-up/delivery activities. Loading/unloading activity may be carried out on-street, or on especially designated space inside or outside buildings. Therefore, purpose of this study is to clarity the efficient urban goods movement in CBD(also called the pick-up/delivery activity) from the three different types of loading/unloading facilities. For this purpose, the differences in loading/unloading and truck-trip activity time of each loading/unloading facility was compared by performing the simulation analysis.

• 한국지구과학회지
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• 제40권4호
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• pp.414-427
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• 2019

In East Asia, the long-range transport of dust storms originating from Mongolia and northern China affects airborne dust loadings over downwind areas in the southern Korean Peninsula. Since 1997, dust loading cases caused by dust storms have been observed using the thresholds of total suspended particles (TSP, ${\geq}250{\mu}g\;m^{-3}\;hr^{-1}$) and particulate matter less than $10{\mu}g$ ($PM_{10}$, ${\geq}190{\mu}g\;m^{-3}\;hr^{-1}$) in the central-southern Korean Peninsula. There were two dust loading cases that exceeded these thresholds in 2016 and three in 2017, which reflects the downward trend of the last twenty-one years in the central-southern Korean Peninsula. Furthermore, five other dust loading cases with mass concentrations lower than the thresholds were observed from 2016 to 2017. In the moderate dust loading cases exceeding the thresholds, a descending motion of cut-off lows below $45^{\circ}N$ and a southward trough at 500 hPa gpm isopleths intensified at the western ridge, and largely extended the surface high-pressure system over southeast China. Airborne dust loadings following pronounced north-westerlies in the forward side of the high-pressure system were transported to the surface of the central-southern Korean Peninsula. However, in slight dust loading cases lower than the thresholds, the restricted descending motion of cut-off lows over $45^{\circ}N$ and the southwestward trough at 500 hPa gpm isopleths intensified the zonal flow over the Korean Peninsula. Surface high- and low-pressure systems moved eastward from the source compared to moderate dust loading cases. Due to the zonal movement of dust storms traversing eastern China, slight dust loading cases were observed with relatively higher ratios of $PM_{2.5}/TSP$ and carbon monoxide (CO) in the central-southern Korean Peninsula.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.124-130
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• 2003

Many structural evaluation procedures of road and airfield pavements use the Falling Weight Deflectometer (FWD) as a critical element of non-destructive deflection testing. FWD is a trailer mounted device that provides accurate data on pavement response to dynamic wheel loads. A dynamic load is generated by dropping a mass from a variable height onto a loading plate. The magnitude of the load and the pavement deflection are measured by a load celt and geophones. And database concerning pavement damage should be enhanced to analyze loss of thickness asphalt layer caused from the plastic deformation of pavement structure, such as cracking or rutting. The prototype FWD is developed, which consists of chassis system, hydraulic loading system, data acquisition and analysis system. This system subsequently merged to from automation management system and is then validated and updated to produce a working FWD which can actually be used in the field.

• 대한전기학회논문지
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• 제41권7호
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• pp.712-722
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• 1992

Several voltage instability/collapse problems that have occurred in the electric utility industry worldwide have gained the attention of engineers and researchers of electric power systems. This paper proposes an effective calculation scheme of the extreme loading point and nose curves(P-V curves) using modified Newton-Raphson(N-R) load flow method and the Continuation Method. This method provides detail and visual information of the power system voltage profile and operating margin ro operators and planners. In this paper, a modified load flow claculation method for ill-conditioned power systems is introduced for the purpose of seeking more precise load flow solutions and nose curves, and the Continuation Method is also used as a part of the solution algorithm for the calculation of extreme loading point and nose curves. The conventional polar coordinate based N-R load flow program is modified to avoid numerical difficulties caused by the singularity of the Jacobian matrix occuring in the vicinity of extreme loading point of heavily loaded systems. Application results of the proposed method to Klos-Kerner 11-bus system and modified IEE-30-bus system are presented to assure the usefulness of the approach.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.484-487
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• 2005

In order to get the surface characteristics of the HDI of HDD, the surface damage mechanisms must be totally understood. Particle contamination in hard disk drives is a big concern in today's magnetic recording industry since they are major sources of reliability problems. Namely upon contact with the slider or a contaminant particle, the disk may be scratched or the particles may be embedded into the disk surface. In this work, comparison of scratches was made between those found on actual hard disks and those created using a scratch tester. It was found that ramp loading method is an effective way to make similar scratches as the actual ones. From the ramp loading condition, the relationship between the pressure and the scratch track width could be identified.