• Laser Solutions
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• v.11 no.3
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• pp.5-9
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• 2008

The effect of a laser peening on the surface residual stress of SUS 304 was investigated using a second harmonic Nd:YAG laser beam. The energy density and the diameter of the laser beam were $400mJ/mm^2$ and about 1mm, respectively. According to the test results, the effect of a laser peening for improving the surface residual stress was not big enough to induce a high compressive stress on the SUS 304 surface. This is thought to be attributed to the small radius of the laser beam used in this study, even though its energy density is big enough. From this study, it can be concluded that to induce a recognizably high compressive stress on a metal surface, the energy density as well as the size (diameter) of the laser beam should be large enough to generate surface plasma with a high energy to have a big impact to a metal surface.

• Journal of Power System Engineering
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• v.5 no.4
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• pp.67-73
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• 2001

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to know the influence on fatigue properties by two cases of two-stage shot peening iud single-stage shot peening for two kinds of spring steel(SUP7, SAE9254). This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from decreasing the surface roughness unchanging the surface hardness increasing the compressive residual stress. Results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.11a
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• pp.71-79
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• 2001

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to know the influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, three kinds of spring steel(JISG4081-SUP ,SAE 9254, DIN 50CrV4, ) are made. This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) Decreasing the surface roughness (2) Unchanging the surface hardness (3) Increasing the compressive residual stress But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.127-131
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• 2002

The surge protector is crucial power apparatus to guarantee the safe operation of power transmission of underground cable which can effectively restrain the overvoltage and inductive lightning stroke in power system. The surge protector is crucial power apparatus to guarantee the safe operation of power transmission of underground cable which can effectively restrain the overvoltage and inductive lightning stroke in power system. This paper described the results of a study on the performance for surge protector for underground cable. And, the performance of surge protector was evaluated through such as measurement of the reference voltage, residual voltage and impulse current etc. In results of surge protector, reference and residual voltage of ZnO element is 4.75 kV, 9.86 kV respectively. Also, In the impulse current test, thermal properties are good, despite of that polymeric housing of surge protector has thick structure. Therefore the developed surge protector is thought to apply for underground cable.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.519-528
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• 1994

Degradation problem due to long term service in machine or structure is now one of important problems in whole industrial field. In this study, pressure vessel steel, Cr-Mo steel, which was used more than 60,000 hours, was surface-modified by laser beam radiation for the improvement of fatigue strength. To find out optimum radiation condition, hardness, residual stress measurement and fatigue tests were carried out with the specimen of different radiation conditions. Experimental results show that micro-hardness values on the surface of the radiated specimens were approximately 2.2 times higher than those of un-radiated ones. In the depth direction of the specimen, hardness on the surface showed maximum value and was decreased at the inside the specimen. Different hardness values are due to the energy density Q which was absorbed by the specimen. Fatigue tests show that fatigue life was improved by the compressive residual stress after laser beam radiation. However, some specimens with differednt conditions show the shorter fatigue life. It means that laser beam radiation with optimum parameter can improve thae fatigue strength.

• Korean Journal of Veterinary Service
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• v.22 no.1
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• pp.93-101
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• 1999

This test process on screening method for the detection of residual antibiotics in milk is simple, economic, sensitive to residual antibiotics and was given approval international organs. Thus, this study was carried out the comparison of Disk assay method and TTC-II method for sensitivity and minimum detectable range of antibiotics in raw milk. The results of this study was summarized as follows ; 1. The number of samples requested for treatment of mastitis was 198 samples. Comparison or analytical results among the methods of TTC-II, disk assay and Delve sp was that TTC-II 37 samples(18.6% ), Disk assay 125samples(63.1%), Delve SP 130 samples(65.7% ) reacted positively. Conformity rate of Delve SP and Disk assay was 70%. 2. Detectable limits of disk assay method in some antibiotics were more sensitive than those of official method(0.05-0.0025ppm in the $\beta$-lactams, 1ppm in two aminoglycoside, 0.2 ppm in one tetracycline, similar in one macrolide) 3. For sensitivity of residual sulfonamides TTC-II was much more sensitive than disk assay. Detectable limits of sulfamethazine and sulfadimethoxine were 30 to 50ppm levels. 4. The best medium preservation period is 1-2 days. 5. Concentration of brome cresol purple related to resistance for B stearothermophilus culture was 24ppm/ml. These results show that disk assay method for screening detection of antibiotics residuces in milk is worthy of use.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.5
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• pp.496-503
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• 2007

Although weld-induced deformation is inevitable in shipbuilding, it is important to reduce it as low as possible during fabrication for a more efficient production of ships' blocks. The weld-induced deformation is more serious in thin plates than in thick plates because heat affect zone of thin plates is wider than that of thick plates, and in addition internal and external constraints much more influence upon weld-induced deformation of thin plates. This paper deals with the application of the mechanical tensioning method to butt weld of thin plates to reduce the transverse and longitudinal deformation. in order to investigate the quantitative effect of tensioning method upon the reduction of angular deformation and shrinkage in longitudinal and transverse direction of weld line, butt welding test have been carried out for several thin plate specimens with varying plate thickness and magnitude of tensile load. Numerical simulation has been also carried out to compare the weld-induced deformation and residual stress. From the present study, it has been found that the tensioning method is very effective on reduction of weld-induced residual stress as well as weld-induced deformation.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.185-192
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• 2003

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to Dow the influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, three kinds of spring steel (JISG4081-SUP7, SAE 9254, DON 50CrV4) are made. This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) Decreasing the surface roughness (2) Unchanging the surface hardness (3) Increasing the compressive residual stress. But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of hish hardness.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.366-372
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• 2002

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface deject as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to know tile influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, three kinds of spring steel (JISG4081-SUP7,SAE 9254, DIN 50CrV4, ) are made. This study shows the outstanding improvement of fatigue properties at tire case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) Decreasing the surface roughness (2) Unchanging the surface hardness (3) Increasing the compressive residual stress But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.4
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• pp.539-544
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• 2011

The relative focus about phosphorus (P) which causes eutrophication characterized by increased growth of undesirable algae has increased in recent years. Phosphorus forms in soil and water include both organic and inorganic forms. There are also a large number of soil P determination methods that have been designed to account for various types of P and mechanisms controlling the chemistry of P in soil, water, and residual materials for environmentally relevant forms of P. However, phosphorus forms in soil, water, and residual materials are also difficult to standardize with any reasonable consensus, due to the number of different disciplines involved. Hence, it is essential to accurately define how P can be measured in soil, water, or residual material samples to avoid potential misinterpretations or inappropriate recommendations in determining amount and types of P. Therefore, we reviewed the testing methods which have appeared in the scientific literature to provide an overview of the soil test P most commonly used.