• Journal of the Korean Mathematical Society
• /
• v.52 no.3
• /
• pp.503-522
• /
• 2015

In this paper, we consider the problem of testing for a parameter change in nonlinear time series models with GARCH type errors. We introduce two types of cumulative sum (CUSUM) tests: estimates-based and residual-based tests. It is shown that under regularity conditions, their limiting null distributions are the sup of independent Brownian bridges. A simulation study is conducted for illustration.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.3
• /
• pp.855-868
• /
• 1991

본 연구에서는 위에서 언급한바와 같은 제반사항들에 대해 이론적인 해석을 행하고, 그 결과를 이용하여 설계된 모델이 생체내에 이식될 수 있는 가능성의 여부를 판단하며 생체내에 이식 되었을 때의 성능과 생체에 미치는 영향등을 예측하고자 한다.

• Journal of the Korean Institute of Gas
• /
• v.20 no.5
• /
• pp.112-117
• /
• 2016

The standard(KS D 3631) should be obey for using fuel gas pipe in Korea and a carbon steel pipe is coated with synthetic resine for protecting the corrosion. The coating is just performed for anti-corrosion, and actual strength of pipe is given by the carbon steel pipe when the fuel gas is transported. When the flaws are occurred in the steel pipe, the estimation method which is used for residual strength is necessary. But the suitable method is not exist for applying the fuel gas pipe. Eventually, the residual strength is estimated by overseas regulation such as ASME B31G or DNV RP F101. But the method based on the relative regulations are not sufficiently valid and it can not estimate the 85% over even. Therefore, the test was performed for validation with pipe specimen. The specimen was made with artificial flaw. The test results showed the certain differences according to flaw depth and DNV RP F101 is suitable to estimate the residual strength in Korea. The results in this paper contain in case of the severe flaw depth and suitable mode for Korea, so the result can be expected as valuable and widely used in various field.

• The Korean Journal of Pesticide Science
• /
• v.16 no.4
• /
• pp.302-307
• /
• 2012

This study was carried out to elucidate residual characteristics of environment friendly agricultural material rotenone in chilli pepper and calculate processing factors by drying. The test material was sprayed twice onto chilli peppers at an interval of seven days and then the chilli peppers were harvested at 0, 1, 3, 5 and 7 days after final spray. Limits of quantitation (LOQs) of rotenone in fresh and dried chilli peppers were 0.03 and 0.07 mg/kg, respectively. Recoveries of the test material in fresh and dried chilli peppers ranged from 89.52 to 97.86% and from 85.76 to 91.61%, respectively. As a results of residual material analysis, amounts of rotenone in fresh and dried chilli peppers ranged from 0.03 to 0.39 mg/kg and from 0.07 to 0.75 mg/kg, respectively, representing that the residual amounts of rotenone decreased time-coursely. Processing factors of rotenone in fresh chilli pepper by drying were found to be from 2.03 to 3.13, indicating that the residual concentration of rotenone in dried chilli pepper increased from two to three times by drying. However, the reduction factor of rotenone in fresh chilli pepper by drying ranged from 0.38 to 0.59, representing that some of rotenone in fresh chilli pepper disappeared during the drying process.

• Elastomers and Composites
• /
• v.47 no.4
• /
• pp.336-340
• /
• 2012

Residual stress in the injection molded part is originated from thermal shrinkage and shear stress during injection molding process. There are many measurement methods of residual stress in the plastic part. Residual stress in opaque products can be measured by chemical cracking test. This method enables the solvent and specimen to react and to cause cracks. Cracks developed according to the level of residual stress. Thus the stresses in plastic part can be quantitatively measured by counting the number of cracks or measuring the size of cracks. Relationship between stress and number of cracks in a plastic specimen has been investigated in this study. Bergen jig was used to give a strain in the specimens those were molded using PC/PBT and PC/ABS. Solvent for the chemical cracking test was prepared using tetrahydrofuran and methyl alcol with the ratio of 1 to 3. Stresses in the specimen can be calculated by strains those were imposed by Bergen jig. Cracks were developed for stress higher than certain level. The number of cracks increased by second order function for stress.

• Journal of the Microelectronics and Packaging Society
• /
• v.16 no.2
• /
• pp.33-42
• /
• 2009

A polymer-based flexible neural probe was fabricated for monitoring of neural activities from a brain. To improve the insertion stiffness, a 5 ${\mu}m$ thick biocompatible Au layer was electroplated between the top and bottom polymer layers. The developed neural probe penetrated a gel whose elastic modulus is similar to that of a live brain tissue without any fracture, To minimize mechanical residual stress and bending from the probe, two new methods were employed: (1) use of a thermal annealing process after completing the device and (2) incorporation of multiple different layers to compensate the residual stress between top and bottom layers. Mechanical bending around the probe tip was clearly removed after employing the two processes. In electrical test, the developed probe showed a proper impedance value to record neural signals from a brain and the result remained the same for 72 hours. In simple in-vitro probe characterization, the probe showed a great removal of residual stress and an excellent recording performance. The in-vitro recording results did not change even after 1 week, suggesting that this electrode has the potential for great recording from neuron firing and long-term implant performance.

• Journal of Soil and Groundwater Environment
• /
• v.19 no.3
• /
• pp.25-32
• /
• 2014

The amount of TPH contaminated soil treated at off-site remediation facilities is ever increasing. For the recycle of the treated-soil on farmlands, it is necessary to restore biological and physico-chemical soil characteristics and to remove residual TPH in the soil by an economic polishing treatment method such as phytoremediation. In this study, a series of experiments was performed to select suitable plant species and to devise a proper planting method for the phyto-restoration of TPH-treated soil. Rye (Secale cereale) was selected as test species through a germination test, among 5 other plants. Five 7-day-old rye seedlings were planted in a plastic pot, 20 cm in height and 15 cm in diameter. The pot was filled with TPH-treated soil (residual TPH of 1,118 mg/kg) up to 15 cm, and upper 5 cm was filled with horticulture soil to prevent TPH toxic effects and to act as root growth zone. The planted pot was cultivated in a greenhouse for 38 days along with the control that rye planted in a normal soil and the blank with no plants. After 38 days, the above-ground biomass of rye in the TPH-treated soil was 30.6% less than that in the control, however, the photosynthetic activity of the leaf remained equal on both treatments. Soil DHA (dehydrogenase activity) increased 186 times in the rye treatment compared to 10.8 times in the blank. The gross TPH removal (%) in the planted soil and the blank soil was 34.5% and 18.4%, respectively, resulting in 16.1% increase of net TPH removal. Promotion of microbial activity by root exudate, increase in soil permeability and air ventilation as well as direct uptake and degradation by planted rye may have contributed to the higher TPH removal rate. Therefore, planting rye on the TPH-treated soil with the root growth zone method showed both the potential of restoring biological soil properties and the possibility of residual TPH removal that may allow the recycle of the treated soil to farmlands.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2009.10a
• /
• pp.379-380
• /
• 2009

• Communications for Statistical Applications and Methods
• /
• v.3 no.1
• /
• pp.61-71
• /
• 1996

Kim and Song(1995)과 Kim and Lee(1996)는 하나의 이지공변량(binary covariate)을 갖는 가산위험모형(additive risk model)의 적합도검정법(goodness-of-fit test)을 제안했다. 전자는 모수의 가중추정량들의 차에 기초한 검정법이며 후자는 마팅게일잔차(martingale residual)에 기초한 검정법이다. 본 논문에서는 모의실험을 통하여 두 검정법을 비교하였다.

• Korean Journal of Materials Research
• /
• v.22 no.2
• /
• pp.82-85
• /
• 2012

The effect of the alloy systems Al-Mg alloy and Al-Si alloy in this study on the characteristics of die-casting were investigated using solidification simulation software (MAGMAsoft). Generally, it is well known that the casting characteristics of Al-Mg based alloys, such as the fluidity, feedability and die soldering behaviors, are inferior to those of Al-Si based alloys. However, the simulation results of this study showed that the filling pattern behaviors of both the Al-Mg and Al-Si alloys were found to be very similar, whereas the Al-Mg alloy had higher residual stress and greater distortion as generated due to solidification with a larger amount of volumetric shrinkage compared to the Al-Si alloy. The Al-Mg alloy exhibited very high relative numbers of stress-concentrated regions, especially near the rib areas. Owing to the residual stress and distortion, defects were evident in the Al-Mg alloy in the areas predicted by the simulation. However, there were no visible defects observed in the Al-Si alloy. This suggests that an adequate die temperature and casting process optimization are necessary to control and minimize defects when die casting the Al-Mg alloy. A Tatur test was conducted to observe the shrinkage characteristics of the aluminum alloys. The result showed that hot tearing or hot cracking occurred during the solidification of the Al-Mg alloy due to the large amount of shrinkage.