• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.9 no.1
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• pp.25-30
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• 2013

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

• Journal of Nutrition and Health
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• v.22 no.6
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• pp.547-556
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• 1989

This survey was carried out to investigate the nutritional status of 102 rural pregnant women after the 2nd trimester and the effect of pregnant nutritional status on newborn infant's anthropometric measurements. 102 rural pregant women's age was distributed 20 to 34. Pregnant height and prepregnant weight were 157.7$\pm$3.2cm and 50.7$\pm$5.4kg, respectively, which were similar to Korean standard, and pregnant weight gain per week after the 2nd trimester was 0.35$\pm$0.13kg, which was showed normal weight gain. Pregnant blood pressure were 112.6$\pm$12.7mmHg (systolic pressure) and 71.8$\pm$10.6(diastolic pressure), and energy and protein intake were 83.8$\pm$34.3% and 72.2$\pm$24.2% of RDA, respectively. Hemoglobin and blood protein level of 17 pregnant women who selected among total pregnant women were 11.8$\pm$1.0g / dl, 6.5$\pm$0.9g / dl, respectively. Height, weight, and head circumference of 17 newborn infants who delivered from 17 pregnant women were 50.1$\pm$1.9cm, 3.4$\pm$0.6kg, and 31.4$\pm$1.2cm, respectively, which were similar to Korean standard. Infant height, weight, and head circumference at birth were significantly correlated with pregnant higher than dietary intakes and weight gain per week during midpregnancy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1211-1212
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• 2011

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.1
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• pp.13-17
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• 2007

The brake gain adaptive wheel slip controller for a vehicle is designed in this paper. The brake gain from braking pressure to braking torque defined by friction coefficient, friction area and effective friction radius is estimated by the adaptive law based on the wheel slip dynamics. And the wheel slip controller is designed based on the estimated brake gain. The robustness of the designed controller is analyzed using Lyapunov function and the convergence of brake gain is verified. Proposed wheel slip controller is verified via CarSim simulation with two kinds of desired wheel slip ratio.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.5
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• pp.246-254
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• 2022

The high-temperature oxidation behavior of Cr-Mo steel AISI 4115 in air at different temperatures (600, 850, 950℃) for 120 min was studied by mass gain analysis, phase analysis (optical microscopy, electron probe micro-analysis, x-ray diffraction) and hardness measurement of each iron oxide-phase. The oxidation scales that formed on oxidation process consisted outer layer (Hematite), middle layer (Magnetite) and the inner layer (Chromite). In the case of 850 and 950℃, the oxidation mass gain per unit area of AISI 4115 steel increased according to the logarithmic rate as atmospheric pressure increased. Especially, It has been observed that with an increase in the atmospheric pressure at 600℃, the oxidation mass gain per unit area changed from a linear to logarithmic relationship.

• Journal of Preventive Medicine and Public Health
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• v.32 no.3
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• pp.415-420
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• 1999

Objectives: We investigated the effects of changes in obesity and life style factors, such as cigarette smoking, alcohol drinking, and exercise, on the changes in blood pressure and serum cholesterol among Korean men. Methods: This study included 7,205 healthy male employees in the steel manufacturing industry. Each subject underwent health examination in 1994 and was re-examined in 1997. The study subjects were classified into four categories, according to changes in body mass index (BMI) (loss; stable; mild gain: severe gain), cigarette smoking (quitter; nor-smoker; smoker continued; smoker started), alcohol drinking (quitter; non-drinker; drinker continued; drinker started) and exercise (more exercise; continuous regular exercise; continuous irregular or no exercise; less exercise), respectively. We evaluated the relationship between the categories of change in those independent variables and the changes in blood pressure and serum cholesterol, adjusted for BMI in 1994 and age by analysis of variance. Results: The change in systolic blood pressure was positively associated with the changes in BMI (p<0.001) and drinking (p=0,001), but negatively with smoking (p=0,004), compared to the first category of each independent variables. The systolic blood pressure was significantly less increased in the continuous smoking group than quitter or hon-smoker. The changes in diastolic blood pressure and serum cholesterol appeared to have statistically significant linear relationships only with the change in BMI. The change in exercise showed a marginal significance with diastolic blood pressure (p=0.088). Conclusions: These prospective data emphasize the importance of obesity as a determinant of the changes in blood pressure and serum cholesterol. In addition, the changes in smoking and drinking habits can affect systolic blood pressure.

• Journal of Nutrition and Health
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• v.18 no.3
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• pp.194-200
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• 1985

The purpose of this study was to investigate sodium intake and protein metabolism for pregnant women in Korea. The relationship between salt consumption and hypertension, electrolyte changes in pregnancy, and the tendency of weight gain of pregnant women were also examined. The dietary survey and twelve or twenty-four hour's urine collection was performed in this study. The subjects were pregnant women who came to gynecology clinic for prenatal care from July to August in 1984. The results were as follows: 1) Intakes of calorie and iron of Korean pregnant women were 2,036 Kcal and 16mg per day per person. The calorie composition consists of 65% carbohydrate, 16% protein, and 19% lipids. The average level of all nutrients was about 87% of Korean Recommended Dietary Allowances. 2) The sodium intakes in pregnant women estimated by dietary survey was 318.6 mEq Na (7,966 mg Na), which is equivalent to 20.2 g NaCl. 3) Daily sodium excretion was 112.5 mEq per liter, that is equal to 147.4 mEq. Potassium excretion was 24.95 mEq per liter and creatinine excretion was 594.0 mg per day. 4) There were statistically significant correlations between sodium intake and the excretions of sodium, potassium and creatinine. The blood pressure was positively correlated with sodium intakes. As sodium and potassium ratio was increased, systolic blood pressure and diastolic blood pressure were also significantly increased 5) Urinary nitrogen and creatinine ratio known to be reliable index for nutritional status of protein was 5.5 : 1. These values were comparable to the values in American pregnant women. 6) The weight gain during the pregnancy was examined. There was little weight gain during the first trimester, because of nausea, vomit and decrease of appetite. The weight gain during the second trimester was 4.9Kg, and 11.1Kg for third trimester.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.8
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• pp.38-48
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• 2014

In this paper, a design of Signal Processing Analog Front-End IC for Automotive Piezo-Resistive Type Pressure Sensor is presented. In modern society, as the car turns to go from mechanical to electronic technology, the accuracy and reliability of electronic parts required importantly. In order to improve these points, Programmable Gain Amplifier (PGA) amplifies the received signal in accordance with gain for increasing the accuracy after PRT Sensor is operated to change physical pressure signals to electrical signals. The signal amplified from PGA is processed by Digital blocks like ADC, CMC and DAC. After going through this process, it is possible to determine the electrical signal to physical pressure signal. As processing analog signal to digital signal, reliability and accuracy in Analog Front-End IC is increased. The current consumption of IC is 5.32mA. The die area of the fabricated IC is $1.94mm{\times}1.94mm$.

• Journal of the Korean Solar Energy Society
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• v.36 no.3
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• pp.53-61
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• 2016

Solar assisted heat pump system uses solar thermal energy as a heat source of evaporator of heat pump. So, COP can be enhanced as well as collector efficiency. For improving performance of this system, some research about hybrid solar collector that has fin-and-tube heat exchanger has been conducted. This collector can get a thermal energy from ambient air for liquid heating, so heated liquid can be used as a heat source of evaporator in heat pump even the solar radiation is not enough. In this study, numerical analysis was conducted for confirming heat gain of liquid according to fin height and pitch of fin-and-tube heat exchanger in collector. As a result, higher heat gain was obtained on lower fin height and narrow fin pitch, but the pressure drop also increased with increment of heat gain. Thus the JF factor considering both heat transfer enhancement and pressure drop was investigated and the maximum value was shown when the fin height and pitch were 40mm and 45mm. So it is considered that this installation condition has a highest heat transfer improvement when comparing with pressure drop. However heat gain of liquid at this condition was less than the other installation conditions of fin pitch on same height. Then, after establishing a proper minimum heat gain of liquid, actual production and experiment of collector will be conducted with fin height and pitch showing maximum JF factor and satisfying selected minimum heat gain of liquid on the basis of results of this study.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.3
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• pp.34-40
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• 2012

A pressure control law to regulate pressure of gas generator is suggested. To design a model based control law, the governing equation which consists of Robert and conservation equation is built and verified through the ground burning test. PID and nonlinear adaptive control laws are designed to analyze the loop response characteristics under the system which has varying eigen properties arisen from combustion volume change. It is suggested that new approach, gain scheduling design, is required to overcome the defects identified from numerical simulation results of the two control laws. The newly suggested scheme shows good control performance even under disturbances and measurement noise.