• Journal of Power System Engineering
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• v.3 no.2
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• pp.51-56
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• 1999

Fatigue crack propagation rates and characteristics of the SA516-70 steel which is used for the low temperature pressure vessels, were studied in the room temperature of $10^{\circ}C$ and low temperature ranges of $-10^{\circ}C,\;-30^{\circ}C,\;-50^{\circ}C,\;and\;-70^{\circ}C$ with stress ratio of R=0.05. The obtained experimental results are as follows; 1) In the logarithmic relationship between the fatigue crack propagation rate(da/dN) and stress intensity factor K, the linear relationship was obtained up to da/dN > $8{\times}10^3$ mm/cycle in the same of room temperature, but in low temperature case, the relationship was extended to the range of low crack propagation rate. 2) The lower limit stress intensity factor of SA516-70 ${\Delta}K_{th}\;was\;23MPa\sqrt{m}$ and in the case of low temperature $-50^{\circ}C\;and\;-70^{\circ}C$, the crack propagation rate da/dN which showed a linear relation, reached rapidly to the ${\Delta}K_{th}$. As the results, the crack propagation rates of $-50^{\circ}C\;and\;-70^{\circ}C$ were lower than that of room temperature and according to the testing temperature the rates were decreased rapidly to the ${\Delta}K_{th}$. 3) On the relationship between the stress intensity factor ${\Delta}K$ and the track propagation cycle, the stress intensity factors of low cycle region was rapidly increased at low temperature, but ${\Delta}K$ was increased rapidly at room temperature of high cycle. 4) On the relationship between the fatigue crack propagation rate and cycle, the fatigue crack propagation rate showed higher gradient in the room temperature than the low temperature due to the increment in ductility at low temperature.

• Applied Biological Chemistry
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• v.32 no.4
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• pp.357-361
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• 1989

Wheat Doenjang was manufactured by mixing various ratio of the soymilk residue with wheat Koji. As the result, the content of reducing sugar was increased till 50 days and decreased thereafter during aging of the mash. As the combination ratio of soymilk residue was increased, the content of reducing sugar was decreased and amino nitrogen content was increased prominently till 50 days in all testing samples but thereafter the increasing ratio was slowdowned. At the beginning of the aging the content of the amino nitrogen was higher in the testing sample which had higher combination ratio of soymilk residue but at the end of the aging the result was reversed. The content of the total acids was increased prominently till 40 days but thereafter the increasing ratio was slowdowned, and in each testing samples the difference in total acid content was extremely slight. In the color of each testing samples aged 80 days as the combination ratio of soymilk residue was increased, the lightness was increased, and the redness was decreased but the yellowness was increased. From the result of sensory evaluation test of wheat Doenjang aged 90 days, soy sprout Doenjang soup showed the best taste in control and as the combination ratio of soymilk residue was increased, the taste was dropped slightly but no significant differences was obtained among the testing sample A,B and C but between control and testing sample D there was significant difference. In the original taste of Doenjang, the control was the best and as the combination ratio of soymilk residue increased, the point was dropped but there were no significant differences between control and testing sample A and testing sample B and C.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.285-299
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• 2004

The purpose of this study is to identify female 500m sprint start motion by the center of gravity position in short track speed skating. The center of gravity position ratio was divided into three type(type A front : 80%-back : 20%, type B front : 70%-back 30%, type C front: 50%-back : 50%). Three video cameras were used for 3D motion analysis with DLT method and the results were as follows: The elapsed time in starting motion was appeared that type B was the shortest and type A was the longest. It was appear that the stroke length of type A was longer than that type B and C during starting phase. This result was similar to displacement of center of gravity. It was appeared that skill type of center of gravity position ratio type B' ankle and knee joint angle were lower than that of type A and C. Observing these results it was conclusion that skill type B of center of gravity position ratio was more faster than that of type A and C. But it is important that these skill type needed to verifying more subjects.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.6
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• pp.538-543
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• 2006

A packed bed reactor (PBR) was fed with nitrate containing synthetic wastewater or effluent from a sequencing batch reactor used for nitrification. The C source introduced into the PBR consisted of volatile fatty acids (VFAs) produced from anaerobic acidogenesis of food wastes. When nitrate loading rates ranged from $0.50\;to\;1.01\;kg\;N/m^{3}{\cdot}d$, the PBR exhibited $100{\sim}98.8%\;NO_{3}^{-}-N$ removal efficiencies and nitrite concentrations in the effluent ranged from $0\;to\;0.6\;NO_{2}^{-}-N\;mg/L$. When the PBR was further investigated to determine nitrate removal activity along the bed height using a nitrate loading rate less than $1.01\;kg\;N/m^{3}{\cdot}d$, 100% nitrate removal efficiency was observed. Approximately 83.2% nitrate removal efficiency was observed in the lower 50% of the packed-bed height. When reactor performance at a C/N ratio of 4 and a C/N ratio of 5 was compared, the PBR showed better removal efficiency (96.5%) of nitrate and less nitrite concentration in the effluent at the C/N ratio of 5. VFAs were found to be a good alternative to methanol as a carbon source for denitrification of a municipal wastewater containing 40 mg-N/L.

• Journal of Ocean Engineering and Technology
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• v.15 no.3
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• pp.100-106
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• 2001

In this study, CT specimens were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ${\Delta}K_{th}$ in the early stage of fatigue crack growth (Region I) and stress intensity factor range ${\Delta}K$ in the stable of fatigue crack growth (Region II) was increased in proportion to descent temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN $-{\Delta}K$ in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate da/dN in proportion to descending temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• ETRI Journal
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• v.42 no.5
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• pp.773-780
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• 2020

A 40 nm complementary metal oxide semiconductor carrier-aggregated drive amplifier with high linearity is presented for sub-GHz Internet of Things applications. The proposed drive amplifier consists of two high linear amplifiers, which are composed of five differential cascode cells. Carrier aggregation can be achieved by switching on both the driver amplifiers simultaneously and combining the two independent signals in the current mode. The common gate bias of the cascode cells is selected to maximize the output 1 dB compression point (P1dB) to support high-linear wideband applications, and is used for the local supply voltage of digital circuitry for gain control. The proposed circuit achieved an output P1dB of 10.7 dBm with over 22.8 dBm of output 3rd-order intercept point up to 0.9 GHz and demonstrated a 55 dBc adjacent channel leakage ratio (ACLR) for the 802.11af with -5 dBm channel power. To the best of our knowledge, this is the first demonstration of the wideband carrier-aggregated drive amplifier that achieves the highest ACLR performance.

• Journal of the Korean Society of Safety
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• v.13 no.3
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• pp.45-50
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• 1998

The low grade domestic kaoline, such as pink-C and white-D, was converted to metakaoline, which has pozzolanic reactivity by heat treatment in the temperature range of $600^{\circ}C$ to 100$0^{\circ}C$ for preparing the spacer. The spacer was used for supporting the reinforced steel rod during construction to improve the safety of architecture. Pink-C and white-D were completely dehydroxylated when burnt at 80$0^{\circ}C$ for 1 hour and converted to metakaoline. The compressive strengths of specimens added calcined pink-C were lower than those of press molding mortar products inspite of calcining conditions. When white-D with calcined 80$0^{\circ}C$ and 100$0^{\circ}C$ for 1 hour was mixed 30% in the weight ratio of cement, the specimens cured 28 days had 338 $kg/cm^2$ and 347 $kg/cm^2$ of compressive strengths, respectively.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.609-610
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• 2008

In this paper, a 110 dB, 1.024 MHz fourth-order single-loop Delta-Sigma sigma modulator has been presented with an over-sampling ratio of 128 and an overload factor of -6 dB for a bandwidth of 4 kHz. In particular, this ${\Sigma}-{\Delta}$ modulator is well suited for high accuracy measure systems. The whole modulator consumes only 3-mW from a single 3.3V supply in a $0.35-{\mu}m$ CMOS technology.

• Applied Biological Chemistry
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• v.32 no.2
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• pp.98-103
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• 1989

For the effective use of soymilk residue (SR), by-product of soymilk production, rice Doenjang was manufactured. As the results, the contents of reducing sugar were increased till $40{\sim}50days$ in all samples and decreased thereafter during aging of the mash. The contents of amino nitrogen were prominently increased till 50days, but increasing ratio was slightly slowdowned thereafter. The higher mixing ratio of SR, the less were the contents of reducing sugar and amino nitrogen. The contents of total acid were also prominently increased till 30days, but were slowdowned thereafter and the differences among all treatments were small. As the mixing ratio of SR was increased, the lightness and the yellowness were increased and the redness was decreased in 80days aged samples. In sensory evaluation of 90days aged samples, control was the best in soy sprout Doenjang soup. As the mixing ratio of SR was increased, the taste was dropped slightly but no significant differences were obtained between control and sample A (rice koji 100, soybean 75, SR 25), and among A,B(rice koji 100, soybean 50, SR 50). C(rice koji 100, soybean 25, SR 75) and D(rice koji 100, soybean 0, SR100). In the original taste of Doenjang, the control was the best and as the mixing ratio of SR was increased, the point was dropped but there were no significant differences between control and A, and among A, B and C, and among B, C and D.

• Journal of radiological science and technology
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• v.32 no.1
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• pp.25-32
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• 2009

To find out proper photographing conditions in the chest DR imaging, the evaluation of images using the C-D phantom was carried out on relationship of identification capability, graininess, and exposure ratio. The conclusions were obtained as follows. 1. The patient's entrance skin Exposure (ESE) was decreased as tube voltage was increased. 2. According to the tube voltage change, the C-D phantom's identification capability of the exposure conditions was most visible at 110 kVp. 3. The identification capability according to the exposure ratio (mAs) change was most visible at 90 kVp for 0.5 times of low exposure ratio and at 110 kVp for 1.5 times. Therefore, it is known that the images were able to be better identified at a high exposure than a low exposure. 4. The graininess according to the exposure ratio at tube voltage of 110 kVp resulted in the best thing at 1.5 times of ratio when the exposure ratio was 1.5 times increased and the tube voltage was changed, the graininess showed the best result at 110 kVp. Therefore, the patient's exposure dose was low when kVp was increased and the adequate kVp was found to be 110. The image was better identified when exposure ratio was 1.5 times compared to 1.0 times. The graininess was also good when the exposure ratio became 1.5 times. The tube voltage was good at 110 kVp. However, once the exposure ratio is increased, the amount of radiation dose that the patients received get increased, so that the exposure condition has to be thoroughly considered.