• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.5
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• pp.352-360
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• 2015

Squeal noise is a harsh, high-pitched sound that occurs when railways are running at sharp curve tracks. The cause of squeal noise is known to be the transient lateral traction force between wheel and rail. Field measurements are too difficult to control the parameters. Thus, the scaled test rig should have been made in order to investigate the generating mechanism of squeal noise. The unique feature of our test rig, HSTR(Hongik Squeal Testing Rig), is that DOFs of its wheelset are as close to as those of the real railway. The attack angle and running speed of the rail roller are controlled in real time for simulating a transient characteristic of driving curve. The environment conditions, such as given axle load, running speed, and wheel's yaw angle have been identified for generating squeal noise and the squeal noise itself has been measured. The relation between wheel creepage and creep force in lateral direction and the criteria for squeal noise have been investigated, which results has been verified by finite element method.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.1
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• pp.79-83
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• 2002

The growth and immune responses to endotoxin lipopolysaccharide (LPS) challenge ( $20{\mu}g/kg$) of piglets with and without a iron dextran injection (Fe, 200 mg/head) two days after birth are compared. Sixty-four newborn piglets from eight litters were allocated randomly to one of four treatments. The control received no iron dextran and only saline (Sal) injection on the second and fifteenth day after birth (Sal-Sal). The remaining three groups received Fe-Sal, Sal-LPS, Fe-LPS treatments respectively. On fifteen days of age, blood samples of piglets were taken at 0 h, 1 h, 2 h and 4 d after saline or LPS injection to determine immune functions and blood characteristics. The trial terminated when the pig reached 56 days and the average daily gain of piglets was then measured. Daily gain, serum immunoglobulin G (IgG) concentration and red blood cell counts did not vary significantly among the four groups at any measuring times. Serum tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$) concentration increased sharply 1 h after LPS injection. However, iron injection did not change TNF-${\alpha}$ concentration responds to LPS injection. White blood cell counts of two LPS injection groups were significantly lowered 1 h following the injection. In contrast, serum lactoferrin concentration had increased significantly 1 and 2 h postinjection. Furthermore, iron injection produced no further effects on these two criteria. Iron injection increased the hemoglobin (Hb) concentration of piglets at any measuring time, and LPS injection lowered Hb concentration. In conclusion, a 200 mg/head of iron dextran injection on the second day after birth increased Hb concentration, had no detrimental effect on the immune responses and growth of piglets. Moreover, if creep feed (175 mg Fe/kg feed) is provided from d 7 after birth, the Fe-injection does not contribute to overall performance of piglets and may not be a necessity in practice.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.25 no.4 s.34
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• pp.123-131
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• 1999

Liquid crystal known as a rheological barrier to coalescence of oil droplets, increases emulsion stability, water-holding capacity and promotes active material penetration to skin. Some investigation for its rheological characteristics have been reported but its relations to consumer perception have been rarely published. In this study, oil/water emulsion and oil/liquid crystal/water systems were manufactured using the same composition or Behenyltrimethylammonium chloride/Cetostearyl alcohol/Lanolin oil. and rheological properties or each system were investigated with Cone and Plate rheometer. The formation of liquid crystalline phase was observed with polarized microscope and Differential Scanning Calorimeter. Continuous shear experiment, creep, yield and water holding capacity were measured for oil/water and oil/liquid crystal/water systems. The results were compared with sensory evaluations. Oil/liquid crystal/water system showed higher,viscosity at the same shear rate. higher viscoelasticity and higher yield stress than oil/water system. These properties were expected to show good spreadability and excellent richness without waxiness in hair can: products of creme type. This expectation was consistent with the results of sensory experiments. Water-holding capacity was evaluated by measuring residual water of specimens at specific temperature and relative humidity. Oil/liquid crystal/water system was proved to have higher ability to hold water in comparison with oil/water system. The results indicated that oil/liquid crystal/water system was of benefit to rheological properties creme type hair care products.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1064-1072
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• 2001

It is very important to evaluate material degradation like temper and carbide embrittlements to secure the reliable and efficient operational conditions and to prevent brittle failure in service. The extent of material deterioration can be accurately evaluated by mechanical test such as impact test or creep test. But it is almost impossible to sample a large specimen from in-service plants. Thus, the material degradation evaluation by a non-destructive method is earnestly required. Recently the non-destructive test technique which uses the grain boundary etching characteristics owing to the variation of material structures has been proposed. However the program for material degradation evaluation using the grain boundary etching method(GEM) in Windows 98 domain doesnt be developed now. The aims of this paper are to develop the program and to complete the new master curve equations for the evaluation of material degradation on in-serviced high temperature components.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.2 s.25
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• pp.35-44
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• 2007

Plowable fill is generally a mixture of sand, fly ash, a small amount of cement and water. Sand is the major component of most flowable fill mixes. Marine dredged soil was adopted for flowable fill instead of fly ash. Natural sea sand and in-situ soil were used for comparison. The flow behavior, hardening characteristics, and ultimate strength behavior of flowable fill were investigated. The unconfined compression test necessary to sustain walkability as the fresh flowble fill hardens was determined and the strength at 3-days appeared to correlate well with the water-to-cement ratio. The strength parameters, like cohesion and internal friction angle, was determined along the curing time. The creep test for settlement potential was conducted. Also, potable falling weight deflectometer(PFWD) test has been carried out for elastic modulus of each controlled low strength materials(CLSM). The data presented show that marine dredged soil and in-situ soil can be successfully used in CLSM.

• International Journal of Highway Engineering
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• v.4 no.1 s.11
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• pp.135-147
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• 2002

Application of the foamed asphalt techniques in recycling the waste asphalt shows that large quantify of waste asphalt(60$\sim$70% of the total mix) can be used comparing with hot mix asphalt techniques and also is environmentally safe. However, the constant quality of the recycling foamed asphalt mixtures is not readily achieved and can not be applied to the heavy traffic road due to the characteristics of the conventional foamed asphalt mixtures. The semi-hot technique that the RAP and the aggregate is heated below $100^{\circ}C$ is adopted in this study and expected to solve the problems of conventional foamed asphalt mixtures. This study presents the viability of the semi-hot foamed asphalt mixtures when using the RAP. The semi-hot recycling foamed mixtures are tested and evaluated in the laboratory. The test results including coating rates, creep tests, resilient modulus tests, indirect tensile tests and the Marshall stability tests showed significant improvement.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.483-487
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• 2014

In this study, joining methods with SiC powder as the joining adhesives were studied in order to avoid the residual stresses coming from CTE (Coefficient of Thermal Expansion) mismatch between substrate and joining layer. The shear strength and microstructure of joined material between SiC substrates are investigated. The commercial Hexoloy-SA (Saint-Gobain Ceramics, USA) used in this work as substrate material. The fine ${\beta}$-SiC nano-powder which the average particle size is below 30 nm, $Al_2O_3$, $Y_2O_3$, and $SiO_2$ were used as joining adhesives. The specimens were joined with 20MPa and $1400-1900^{\circ}C$ by hot pressing in argon atmosphere. The shear test was performed to investigate the bonding strength. The cross-section of the joint was characterized by using an optical microscope and scanning electron microscopy (SEM).

• Journal of Korean Society of societal Security
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• v.1 no.3
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• pp.51-57
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• 2008

The long-term behaviors of prestressed concrete cable-stayed bridges are considerably influenced by the time dependant material characteristics such as creep and shrinkage. This study investigated the influences of the change of relative humidity by application of the CEB-FIP model and ACI model, which are generally used in the prediction of long-term behavior of concrete structures. In case of the moment of girder, CEB-FIP model predicted a bigger effect of relative humidity change than the ACI model. Furthermore, the effect was significant. Also, the long-term behaviors between these models were different each other even under the same material condition. Therefore, the prediction of the long-term behavior should be compensated after comparative analysis with the results of material tests of each construction site and between the different models.

• Proceedings of the SCSK Conference
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• 1999.10a
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• pp.123-131
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• 1999

Liquid crystal known as a rheological barrier to coaleseence of oil dorplets. increases. emulsion stability, water-holding capacity and promotes active material penetration to skin. Some investigation for its rheological characteristics have been reported but its relations to consumer perception have been rarely published. In this study oil/water emulsion and oil/liquid crystal/water systems were manufactured using the same composition of Behenyltrimethylammonium chloride/Cetostearyl alcohol/Lanolin oil. and rheological properties of each system were investigated with Cone and Plate rheometer. The formation of liquid crystalline phase was observed with polarized microscope and Differential Scanning Calorimeter. Continuous shear experiment, creep yield and water holding capacity were measured for oil/water and oil/liquid crystal/water systems. The results were compared with sensory evaluations. Oil/liquid crystal/water system showed higher viscosity at the same shear rate, higher viscoelasticity and higher yield stress than oil/water system. These properties were expected to show good spreadability and excellent richness without waxiness I hair care products of creme type. This expectation was consistent with the results of sensory experiments. Water-holding capacity was evaluated by measuring residual water of specimens at specific temperature and relative humidity, Oil/liquid crystal/water system was proved to have ability to hold water in comparison with oil/water system. The results indicated that oil/liquid crystal/water system was of benefit to rheological properties creme type hair care products.

• Journal of the Speleological Society of Korea
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• no.72
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• pp.19-30
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• 2006

The purpose of this study is to clarified the geology and geomorphic characteristics of the Hantan River Basin. In this area, some kind of landforms are developed such as pre-land forms, lava plateau, and present landforms etc. Some river terraces are peculiar features in the area. Some conclusions are as follows : The vicinity of the Hantan River is lava plateau formed from the volcanic activity. Some steptoes are located in the lava plateau. Baekeuiri formation means the river bed boulder beneath the lava formation. The development of drainage patterns are unstable and the bifurcation ratio, the ratio of mean length of the river are lower than the other rivers. The relative height of the terraces is about $5{\sim}25m$ and the terraces are alluvial terraces. In the Jiktang Fall area, bedrock is granite and basalt plateau covered the bedrock. In that point, the old erosion surface is relatively steeper than the horizontal-basalt plateau. Vertical columnar joints are developed and weathering materials creep on the valley wall. The cross section of the landform of the Kosukjung vicinities are somewhat different from the landforms of Jiktang Fall. The bedrock near the Kosukjung is granite that is the same with the Jiktang Fall. But the cross section shows a asymmetrical curve from each side.