• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.306-311
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• 2004

The sliding wear characteristics of the crane sheave were investigated using a pin-on-disk rig tester The experiment was conducted using a high carbon steel wire that was upper material, also carbon steel castings and carbon steel for machine structural use that was disk material. There are various operating conditions in this work. At the room temperature, we carried out the wear test under a grease lubrication. The results of wear test showed that carbon steel for machine structural use have lower wear volume, also the wear curves are linearly increased with increasing of sliding velocity The wear mechanism of a disk is the abrasive, adhesion, and fatigue wear under lubrication.

• Tribology and Lubricants
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• 제19권4호
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• pp.223-229
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• 2003

The sliding wear characteristics of the crane sheave were investigated using a pin-on-disk rig tester. The experiment was conducted using a high carbon steel wire that was upper material, also carbon steel castings that was disk material. There are various operating conditions in this work. At the room temperature, we carried out the wear test under a grease lubrication and dry condition. The results of wear test showed that an annealed-casted have lower, also the wear curves are linearly increased with increasing of sliding distance. For the specific wear rate of annealed-casted, the wear resistance was increased with decreasing diameter of wire. The wear of a wire and a disk have a different mechanism, the one is the abrasive wear due to fatigue wear under lubrication, another is the adhesion wear under dry condition.

• 한국지반공학회지:지반
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• 제7권1호
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• pp.53-68
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• 1991

이 논문은 강우가 시작된 후 시간의 경과에 따른 불구화 지반에서의 여러가지 침투거동을 밝혀서, 서면 불안정의 구체적인 머케니즘을 이해하려는데 목적이 있다. 이를 위해 강우장치를 만들어 권쬐요면에 대해 여러가지 강도의 강우를 재현하고 침투거동을 측정하는 한편, 실험에서 사용한 동일한 수치권을 가지고 수치 해석을 하였다. 두가지 모델시 험 의 결과로부터 만윤전선이 진행되는 과정,지반으로 침투되는 한계강우량의 존재,지표류출의 영향,시간의 경과에 따른 간극수압의 변화 등을 밝혀서 이들 인자들이 사면 불안정에 어떻게 영향을 끼치는가를 자세히 언급하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.125-130
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• 2004

This study proposes a development for the l-kW class small wind turbine system, which is applicable to relatively low wind speed region like Korea and has the variable pitch control mechanism. In the aerodynamic design of the wind turbine blade, parametric studies were carried out to determine an optimum aerodynamic configuration which is not only more efficient at low wind speed but whose diameter is not much larger than similar class other blades. A light composite structure, which can endure effectively various loads, was newly designed. In order to evaluate the structural design of the composite blade, the structural analysis was performed by the finite element method. Moreover both structural safety and aerodynamic performance were verified through the prototype test.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년도 춘계 학술대회 개요집
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• pp.21-23
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• 2006

The microstructural investigation and thermo-mechanical reliability evaluation of the Sn-3.0Ag-0.5Cu solder bumped flip chip package were carried out during the thermal shock test of the package. In the initial reaction, the reaction product between the solder and Cu mini bump of chip side was Cu6Sn5 layer, while the two phases which were (Cu,Ni)6Sn5 and (Ni,Cu)3Sn4 were formed between the solder and Ni-P layer of the package side. The cracks were occurred at the corner solder joints after the thermal shocks of 400 cycles. The primary failure mechanism of the solder joints in this type of package was confirmed to be thermally activated solder fatigue failure.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.422-428
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• 2005

In this paper, the contact force between two colliding bodies is modeled by using Hertz's force-displacement law and nonlinear damping function. In order to verify the appropriateness of the proposed contact force model, the drop type impact test is carried out for different impact velocities and different materials of the impacting body, such as rubber, plastic and steel. In the drop type impact experiment, six photo interrupters in series close to the collision location are installed to measure the velocity before impact more accurately. The characteristics of contact force model are investigated through experiments. The parameters of the contact force model are estimated using the optimization technique. Finally the estimated parameters are used to predict the impact force between two colliding bodies in opening action of the magnetic contactor, a kind of switch mechanism for switching electric circuits.

• 대한기계학회논문집A
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• 제27권11호
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• pp.1873-1880
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• 2003

The sliding wear characteristics of the crane sheave were investigated using a pin on disk rig tester. The experiment was conducted using a high carbon steel wire that was upper material, also carbon steel castings that was disk material. There are various operating conditions in this work. At the room temperature, we carried out the wear test under a grease lubrication and dry condition. The results of wear test showed that an annealed-casted have lower, also the wear curves are linearly increased with increasing of sliding distance. For the specific wear rate of annealed-casted, the wear resistance was increased with decreasing diameter of wire. The wear of a wire and a disk have a different mechanism, the one is the abrasive wear due to fatigue wear under lubrication, another is the adhesion wear under dry condition.

• 토지주택연구
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• 제9권2호
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• pp.51-57
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• 2018

The causes of landslides are dependant on rainfall events and the soil characteristics of a slope. For the conventional slope stability, the slope stability analysis has been carried out assuming the saturated soil theory. But, in order to clearly explain a proper soil slope condition by rainfall, the research should be performed using the unsaturated soil mechanism suitable for a soil slope in the field. In the study, by using two major categories of soils in Korea, such as granite and gneiss weathered soils, landslide model test and finite element method have been compared with the difference of seepage and soil stability analysis. The hydraulic conductivity of gneiss weathered soil is slower than that of granite weathered soil, and the gneiss weathered soil contains much finer soils than the granite weathered soil. It was confirmed that the instability of the slope was progressing slowly due to the slow rate of volumetric water content of the surface layer.

• 전기학회논문지
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• 제63권11호
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• pp.1545-1550
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• 2014

Fault detection and diagnosis (FDD) of photovoltaic (PV) power systems is one of significant techniques for reducing economic loss due to abnormality occurred in PV modules. This paper presents a new FDD method against PV power systems by using statistical comparison. This comparative approach includes deviation signals between the outputs of two neighboring PV modules. We first define a binary hypothesis testing under such deviation and make use of a generalized likelihood ratio testing (GLRT) theory to derive its FDD algorithm. Additionally, a recursive computational mechanism for our proposed FDD algorithm is presented for improving a computational effectiveness in practice. We carry out a real-time experiment to test reliability of the proposed FDD algorithm by utilizing a lab based PV test-bed system.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제44회 KOSCO SYMPOSIUM 초록집
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• pp.247-248
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• 2012

Unidentified self-ignitions were reported when the high-pressure hydrogen gas suddenly leaked out. This paper presents a flow visualization study to investigate the self-ignition mechanism in a test tube how the ignition process is initiated and the flame propagates with measurement of a number of pressure and light sensors installed in the tube supported the analysis of the self-ignition. The test result showed the location of the self-ignition taken place and critical static pressure at the boundary layer for self-ignition.