• 동력기계공학회지
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• 제11권1호
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• pp.51-55
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• 2007

A study on combustion characteristics using emulsified fuel in a diesel engine were performed experimentally. In this paper, the experiments were performed at engine speed 1800rpm, emulsion ratios were 0%, 10%, 20%, and main measured items were specific fuel consumption, cylinder pressure, rate of pressure rise, rate of heat release etc. The obtained conclusions were as follows. 1) Specific fuel consumption increased maximum by 19.8% at low load, but was not affected at full load. 2) Rate of pressure rise and rate of heat release were about the same in the case of 10% and 20% of emulsion ratio. 3) Cylinder Pressure increased 9.6%, rate of pressure rise increased 53.4% in case of emulsion ratio 20% at full load. 4) Rate of heat release increased 72.4% in case of emulsion ratio 20% at full load.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 C
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• pp.899-901
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• 1998

Continuation power flow is a tool that can trace the path of the solution from the base stable solution. However, the base stable solution cannot be calculated when the initial system load is too large to operate at a stable operating point. This case is called as unsolvable case. This paper presents implementation of the optimal load shedding algorithm on continuation power flow. It performs steady-state analysis of power systems at unsolvable case that can occur in contingency analysis. Numerical simulation on 20-bus test system demonstrates that the continuation power flow applying the optimal load shedding algorithm is robust at solvable and unsolvable cases.

• 한국습지학회지
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• 제5권1호
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• pp.67-78
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• 2003

The unsteady 2D convection and diffusion equation is solved numerically for the real-time simulation of suspended load propagation. The streamlined upwind scheme efficiently reduces numerical oscillations due to the high Peclet number in the convection dominant flow. By using the mixed boundary condition to express the external source terms or externally induced suspended load as a function of time in the algorithm, the model is capable of handling not only continuous load cases but also non-continuous suspended load influx. The suspended load transport modelwas verified using a case study for which an analytical exact solution is available and was applied to the real-time simulation of a suspended load influx case on the Mississippi River. The model algorithm can provide a framework upon which water quality as well as contaminant transport models can be built.

• Steel and Composite Structures
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• 제20권1호
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• pp.91-106
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• 2016

Two-dimensional elastoplastic finite element formulation is employed to investigate the load- carrying capacity degradation of reinforced concrete piers wrapped with steel plates due to occurrence of corrosion at the pier base. By comparing with experimental results, the employed finite element analysis method is verified to be accurate. After that, a series of parametric studies are conducted to investigate the effect of corrosion ratio and corrosion mode of steel plates located near the base of in-service pier P2 on load-carrying capacity of the piers. It is observed that the load-carrying capacity of the piers decreases with the increase in corrosion ratio of steel plates. There exists an obvious linear relationship between the load-carrying capacity and the corrosion ratio in the case of even corrosion mode. The degradation of load-carrying capacity resulted from the web's uneven corrosion mode is more serious than that under even corrosion mode, and the former case is more liable to occur than the latter case in actual engineering application. Finally, the failure modes of the piers under different corrosion state are discussed. It is found that the principal tensile strain of concrete and yield range of steel plates are distributed within a wide range in the case of slight corrosion, and they are concentrated on the column base when complete corrosion occurs. The findings obtained from the present study can provide a useful reference for the maintenance and strengthening of the in-service piers.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 가을 학술발표회 논문집
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• pp.441-448
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• 1999

The load distribution in a ground anchor is very complex because it involves three different materials(soil, grout, and steel), which sometimes act as composite sections (bonded length) or separately (unbounded length). Therefore it is very hard to understand load transfer mechanism on the anchor. In order to understand the load transfer, it is essential to consider the load distribution In the three different materials. On these purposes, full scale anchor test is planned on the geotechnical site at Sunkyunkwan University Prior to the test, modeling and analyses of the load transfer mechanism were performed on the data from the case histories.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1997년도 가을 학술발표회 논문집
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• pp.357-364
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• 1997

• 한국산학기술학회논문지
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• 제15권7호
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• pp.4588-4594
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• 2014

본 연구에서는 연약지반에서의 경량콘크리트포장을 적용할 때의 안전성 평가를 위해 실제 포장체 사이즈의 1/30으로 축소한 모형을 이용하여 모래지반에서 실험을 실시하였다. 모형토조를 이용하여 지반을 조성하였고, 표준 말뚝재하시험(완속재하시험방법)을 이용하였다. 수직하중이 적용되는 말뚝기초의 슬래브의 중심에서 가까운 순으로 Case A, Case B, Case C로 구분하였고, 각각의 말뚝의 간격은 8cm로 하였다. 말뚝기초 모형시험결과 사질토지반에서 수직하중을 1.5kg에서 12kg로 증가시킬 때 포장체가 전체적으로 침하하였고, 최대 침하량은 0.4mm로 측정되었다. Case A의 경우 압축력을 받는 것으로 나타났으며, Case B는 수직하중이 증가함에 따라 말뚝에 압축력과 함께 인장력도 같이 받는 것으로 보이며, Case C는 하중단계가 증가할수록 인장변형이 증가하는 경향을 나타내었다.

• 한국안전학회지
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• 제9권4호
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• pp.3-10
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• 1994

This study examines fracture characteristics of wire rope of 6$\times$37+FC 14mm B degree, Which has been widely used for the strength support for machinery, cranes and shipping. The examination Is based on the fellowing experimental conditions. Firstly, this study analyzes the effect of the strength of wlre rope. When number of broken wires is occuring at the level of 5%, 10% and 15% degree respectively in the following two cases：1) Case of broken down to each strand equally. 2) Case of broken down to one strand only. Secondly, this study analyzes the effect of corrosion on the strength of wire rope. Corrosion times are 72hours, 144hours and 216hours corrosion respectively under following conditions. 1) Case of only a corrosion without wire breaking. 2) Case of corrosion after 5% degree wire breaking to each strand equally. Some outcomes of these experiment are as follows. 1) From the of tension test, We can find that the ratio of strength reduction case of wire broke down to one strand concentrically is greater than that ratio case of broke down to each strand equally. 2) From the corrosion test, We can also find that the ratio of strength reduction case of corroded after 5% degree wire breaking to each strand equally Is greater than that ratio case of corroded without wire breaking. 3) After comparing theoretical fracture load of wires with experimental fracture load of wires, we can find the fracture load of the case of broken down to each strand equally is most similar to theoretical fracture load. 4) It is proposed that safety rules on wire rope in the Industrial safety and healthy labor of law have to change “breaking over 10% of number of wires in one strand of wire rope(excluded filler wire )”has to be replaced by“breaking over 10% of number of all wires in all strand of wire rope(excluded filler wire)”

• 농촌계획
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• 제23권4호
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• pp.39-48
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• 2017

National Institute of Environmental Research (NIER) has proposed new methodology for estimating unit load in order to overcome the limitations of past unit load based on short-term and local area based data. In the case of agricultural land, however, the results presented by NIER are still limited because of various agricultural activities and farmland characteristics. In this study, liquid manure treated paddy field and organic farming upland were selected for considering agricultural diversity. Four different methods for evaluating unit load were used for comparing previous research results. The results of different methods presented various trends compared with those of existing studies. Paddy field treated liquid manure was 1.3 times higher for T-N load and 3.1 times for T-P load than conventional paddy field. Conventional upland was 4.4 times higher for T-N load and 1.8 times higher for T-P load than organic farming upland. In the case of non-conventional farmland, this study showed different values with the unit loads presented by NIER. This implies that it is necessary to review and apply the unit loads considering various agricultural conditions when establishing environmental policy and rural planning.

• 한국군사과학기술학회지
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• 제10권1호
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• pp.144-149
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• 2007

Behaviour of a thread joint of a rocket motor case show complex structural characteristics. Pre-torque must be applied to the threads to prevent the loosening of the interface from the additional pressure load. During the pressurization of the rocket motor case, the jointing face may be opened if the pre-torque were not set properly or the structure may be failed if the local concentrated stress exceeds the strength of the material. In this paper, the structural behaviour of a thread joint of a rocket motor case were analyzed by the finite element method and the results were compared to the experimental ones. A method to set a pre-torque for a thread joint were proposed to ensure the structural safety.