• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.159-162
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• 2009

In temperature controlled batch reactor, the effect of temperature and contact metals on the thermal stability of Exo-tricyclo[$5.2.1.0^{2,6}$]decane (tricyclodecane, exo-THDCP) were investigated by use of GC/MS. And the characteristic of metal in contact with tricyclodecane were analyzed by SEM-EDX. In fuel temperature variation test, thermal decomposition of exo-THDCP was occurred at $350^{\circ}C$. In case of fuel contact metals, Titanium was less effective to decomposition of exo-THDCP than stainless steel 304, 316.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.10
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• pp.1676-1685
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• 2003

Tensile and low cycle fatigue tests on prior cold worked 3l6L stainless steel were carried out at various temperatures ftom room temperature to 650$^{\circ}C$. Fatigue resistance was decreased with increasing temperature and decreasing strain rate. Cyclic plastic deformation, creep, oxidation and interactions with each other are thought to be responsible for the reduction in fatigue resistance. Currently favored life prediction models were examined and it was found that it is important to select a proper life prediction parameter since stress-strain relation strongly depends on temperature. A phenomenological life prediction model was proposed to account for the influence of temperature on fatigue life and assessed by comparing with experimental result. LCF failure mechanism was investigated by observing fracture surfaces of LCF failed specimens with SEM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.390-395
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• 2003

This study examined the effects of the testing temperature on the mechanical properties of the stainless steels (STS301CSP-3/4H and STS301CSP-H) for flat spring. Hardness test and fatigue test were performed at room temperature (2$0^{\circ}C$ Tensile testandcreeptestwere performed attemperature range 2$0^{\circ}C$~10$0^{\circ}C$. The micro-victors hardness values of STS301CSP-3/4H and STS301CSP-H were HV=443 and HV=488. respectively. The Elastic modulus, tensile strength, yield strength and strain of these materials were decreased with increasing testing temperature. respectively. The maximum creep strain for 100hr atcreep temperature (10$0^{\circ}C$~20$0^{\circ}C$ and creep stress (Tensile strength$\times$50%) of these materials were 0.53％~0.58%. The fatigue limit of STS301CSP-3/4H and STS301CSP-H were 64.5Kgf/mm$^2$ and 67.4Kgf/mm$^2$, respectively.

• Fire Science and Engineering
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• v.24 no.6
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• pp.89-97
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• 2010

In recent fire protection system, the pipings should be light weighted, seismic proof and wrought with non-welding method. The light weighted stainless steel pipes and fittings, satisfying these requirements, are already used as a fire protection system in Germany, Netherland, Taiwan, Australia, United States and Japan. Accordingly, performance evaluation tests were carried out to determine whether or not the fittings can be used in the pipings. As the performance evaluation tests, we conducted vibration test, water hammering test, bending test and fire test. With the results of the tests, we concluded that the fittings can be used in the fire protection system, and that the life expectancy of the fittings exceeds that of buildings.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.12
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• pp.1171-1176
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• 2014

Oil retention experiments were conducted and the performance was characterized for electrochemically etched stainless steels. The 304 stainless steels were electrochemically etched in dilute Aqua Regia to form porous structures. The structures were also hierarchical, which provides very large area for oils to adhere. Also the structures had deep valleys, which act as reservoir and are able to resist against oil-detaching forces. Several commercial oils were dispensed to characterize oil retention properties via rotating disk experiment method. The results showed that the etched surfaces have superior oil retention performance in every conditions. Also the retention enhancement ratio went particularly higher as the environments became more severe. This surface modification technique could be applied to other steel products for pretreatments of various kinds of coatings.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.94-100
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• 2010

Grounding system insures a reference potential point for electric devices and also provides a low impedance path for fault currents or transient currents in the earth. The ground impedance as function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. In this paper, the grounding resistance, grounding impedance and transient grounding impedance are measured by using 3-point fall-of-potential method in order to analyse grounding characteristics of the stainless-steel plate grounding electrode. An equivalent transfer function model of the grounding impedance and transient grounding impedance are identified from the measured values by using ARMA method and evaluated by comparing conventional grounding impedances.

• Fire Science and Engineering
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• v.31 no.4
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• pp.65-70
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• 2017

The seismic performance of press fittings is studied, which is one of the weldless joints of stainless steel pipe used in the water piping of recent fire protection system. The piping of this study was constructed based on the piping connection reference of NFPA 13. The permissible displacement of the piping was set as the allowed amount which is given in the Building Structure Standard, and the measurements were repeated 10 times. The Von-mises stress of the piping was 2.48 and 1.25 times of the allowed amount of stress, which was less than the standard, noted three times on the NPPs Allowable Stress for Level D service loading. Therefore, the press fittings shows enough seismic performance.

• Composites Research
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• v.22 no.3
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• pp.29-34
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• 2009

In this paper, finite element analyses were used to estimate the strain distribution at the fracture site of a tibia bone. A stainless steel bone plate and various composite bone plates were considered to find out the best conditions for callus generation while bone fracture was cured for 16 weeks. Through this research, the appropriate load condition which makes the strains between the appropriate range($2{\sim}10%$) was sought. From this analysis, it was found that lower level of external load is needed for the appropriate strain for the case of composite bone plate application and it was also found that the composite bone plate had potential advantages for effective bone fracture healing relieved stress shielding effect.

• Composites Research
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• v.20 no.5
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• pp.7-12
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• 2007

This paper aims to enhance the efficiency of bone fracture healing with bone plate made of fiber reinforced composite materials. The composite bone plate was designed as the same dimension and shape as the existing stainless steel bone plate. To find out the appropriate stacking sequence of the composite bone plate the variations of strain distributions were calculated using FE analysis when the bone plates were applied to the fracture site. From the analysis result it was found that the composite bone plate whose Young's modulus is lower than that of metal bone plate gave more uniform strain distribution and provided appropriate condition for callus formation and its development.

• Journal of radiological science and technology
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• v.47 no.2
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• pp.97-105
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• 2024

The examination needle used in ultrasound biopsy is a medical device used to determine whether there is an abnormality in the tissue. Typically, stainless steel is the standard material used for such needles; however, this study wanted to identify a material that could better enhance sound compared to traditional stainless steel. In this study, six types of needle materials available with the biopsy gun were inserted into pork and ultrasound images according to the curved probe and linear probe were evaluated using ultrasound equipment. The findings revealed significant improvements in ultrasound acoustic enhancement with alternative materials compared to stainless steel (p<0.05). The results regarding the depth of each ultrasound image using the curved probe showed that tungsten and brass had high sound enhancement(p<0.05), while with the linear probe, sound enhancement was high in brass, pla, aluminum, and copper(p<0.05). Due to these results, the previously used stainless needle showed lower ultrasound acoustic enhancement than the five types of materials being compared. Consequently, the outcomes of this study provide valuable insights for the development of new needle technologies aimed at minimizing patient risks and improving diagnostic accuracy.