• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.17-22
• /
• 1997

ASME SA508 Class 3 원자로압력용기강을 대상으로, 용접열영향부(heat affected zone, HAZ)의 최고온도(peak temperature) 등온분포도(isothermal diagram)를 작성 및 해석하였고, 재현(simulated) 열영향부 시험편을 제작하여 미세조직검사 및 기계적특성 시험을 실시하였다. 그 결과, 최고온도 등온분포도를 이용하여, 미소열영향부(subzone of HAZ)의 미세조직(microstructure)에 미치는 예열(preheat)온도와 용접입열량(weld heat input)의 크기 효과를 예측할 수 있었다. 또한, 재현 HAZ 의 기계적특성 시험결과, 용접용융선(fusion line) + 1 mm 이내의 위치로 대표되는 열 cycle 조건에서는 모재보다 양호한 강도와 인성을 보였고, 용접용융선 + 2~3mm부근에서 가장 미세한 조직(fine tempered lower bainite)과 우수한 충격인성을 나타냈다. 한편, 용접용융선 + 약 5mm 위치에서의 열 cycle 을 재현한 시험편에서는 미세조직의 변화(spheroidization of carbides)와 함께 인성 및 기계적 특성이 저하하여 모재보다 낮은 값을 보이는 것을 발견할 수 있었다.

• Journal of the Korean Society of Radiology
• /
• v.11 no.7
• /
• pp.663-669
• /
• 2017

In diagnostic medical imaging, it is essential to reduce the scattered radiation for the high medical image quality and low patient dose. Therefore, in this study, the influence of the scattered radiation on medical images was analyzed as the tube voltage increases. For this purpose, ANSI chest phantom was used to measure the scattering ratio, and the scattering effect on the image quality was investigated by RMS evaluation, RSD and NPS analysis. It was found that the scattering ratio with increasing x-ray tube voltage gradually increased to 48.8% at 73 kV tube voltage and to 80.1% at 93 kV tube voltage. As a result of RMS analysis for evaluating the image quality, RMS value according to increase of tube voltage was increased, resulting in low image quality. Also, the NPS value at 2.5 lp/mm spatial frequency was increased by 20% when the tube voltage was increased by 93 kV compared to the tube voltage of 73 kV. From this study, it can be seen that the scattering radiation have a significant effect on the image quality according to the increase of x-ray tube voltage. The results of this study can be used as basic data for the improvement of medical imaging quality.

• Journal of Korean Electronics
• /
• v.16 no.10
• /
• pp.38-49
• /
• 1996

• Proceedings of the Korean Magnestics Society Conference
• /
• 2002.04a
• /
• pp.166-167
• /
• 2002

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2005.11a
• /
• pp.285-288
• /
• 2005

A Stratospheric airship should stay long to achieve its original mission. Meanwhile, to obtain what the solar radiation and heat transfer have an effect on Stratospheric condition, heat analysis has been done. For this work, Stratospheric heat condition's been examined and for the numerical analysis, by using Gridgen, grids of airship have been generated. And by using STAR-CD, the study about heat characteristic of airship model was carried out. Especially, with changing the position of the Sun, the temperature change of the airship body was focused on. With this background, the possibility of realizing the simulation of the effects solar radiation have on the Stratospheric airship.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.11 no.2
• /
• pp.234-241
• /
• 2000

During the EFT immunity test, the fast transient voltage is injected to the power or signal line. The radiated noise from these lines influences the near-by EUT, and consequently, the reliability of the test result can be jeopardized. The measured data of the field strength and wave shape of the noise were compared with the result of the mathematical analysis using transmission line model. When the tests were performed by the conditions the same as stated in IEC 61000-4-4, the results showed that the magnitude of the radiated electric field strength was about 2.4KV/m, and it can cause severe interference to the intended operation of EUT.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.46 no.5
• /
• pp.581-591
• /
• 2017

The purpose of this study was to examine the biological activities of gamma-irradiated Teucrium veronicoides. In photostimulated luminescence analysis, non-irradiated sample showed lower than 700 photon counts (PCs), whereas irradiated (5 and 10 kGy) samples showed higher than 700 PCs. The thermoluminescence ratio of non-irradiated samples was less than 0.1, whereas the values of irradiated samples were greater than 0.1. Electron spin resonance analysis was performed confirmed for irradiation identification. The total phenolic contents of hot-water and 50% ethanol extracts were higher than those values after irradiation at 10 kGy. Regarding 1,1-diphenyl-2-picrylhydrazyl radical inhibitory activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity, antioxidant protection factor, thiobarbituric acid reactive substance inhibitory activity as antioxidant test and xanthine oxidase inhibitory activity, the effect of gamma irradiation had on significant effects. On the other hand, ${\alpha}-amylase$ inhibitory activity of 10 kGy-irradiated hot-water extract was 23.6% higher than that of the non-irradiated sample. Thus, gamma irradiation could be used for the long-term storage of Teucrium veronicoides.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.4 no.3
• /
• pp.235-245
• /
• 2002

The purpose of this study is to figure out the tendency of tunnel convergence during excavation and to present a methodology for the prediction of a fault zone ahead of a tunnel face by analyzing three dimensional displacements in various ways. 3-D numerical analysis was performed to investigate changes of tunnel convergence vectors near a fault zone and to propose a flow chart for predicting fault zones. Results of the site investigation and results of trend line analysis of in-situ data were compared to verify the usefulness of a trend line analysis. It is concluded that the orientation of faults can be predicted by using stereonets and the direction of initial stresses can be predicted from the arm length of a displacement vector as a tunnel approaches fault zones. The results of the trend line analysis coincided with those of the site investigation, and a methodology for the prediction of a fault zone was proposed.

• Journal of Korea Port Economic Association
• /
• v.33 no.1
• /
• pp.89-110
• /
• 2017

The organization of the shipping conference -an international cartel, was approved by countries that recognized it for stabilizing routes as well as preventing excessive competition among liner shipping companies and recognized the characteristic of the liner service that is regularly repeated in the international liner shipping market. However, due to competition in bulk transportation and development of multimodal transport through new entrants, power expansion and vessel enlargement of non-aligned shipping companies; the shipping conference started collapsing, and was eventually abolished. As the shipping conference played an important role in the liner shipping market, there were changes in the competition structure of the liner shipping market, and this accordingly drove research on the effects of the abolition of the shipping conference on the liner shipping market. The effects of abolition of the shipping conference on the liner shipping market was analyzed after surveying the factors related to abolition of the shipping conference, and through the use of correlation and multiple regression analyses. Subsequent to the abolition of the shipping conference, the liner shipping companies increased global containership bottoms. Consequently, this led to fierce competition of freight charges. As a result, profitability of shipping companies diminished. However, shipping companies with a dominating cost structure recorded profits, while shipping companies with an inferior cost structure started recording a loss.

• Korean Journal of Food Science and Technology
• /
• v.31 no.3
• /
• pp.665-671
• /
• 1999

Post mortem bovine muscle. semitendinosus was used to investigate the effects of gamma irradiation on physicochemical properties. The muscle was cut into pieces of 2 cm in thickness and packaged with 2 different methods; vacuum-packaged and air-packaged. The packaged samples were irradiated at designated doses of 0, 1, 3 and 5 kGy by Cobalt-60 irradiator. Muscle protein solubility, purge loss, composition and contents of free amino acids, and shear force were observed during storage at $4^{\circ}C$. We found no significant differences in the purge loss and the contents of free amino acids. Muscle protein solubility slightly increased depending upon the increase of the dose. The decrease of shear force by gamma irradiation was observed. Therefore, it is considered that meat quality can be improved by gamma irradiation.