• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.4 no.4
• /
• pp.341-345
• /
• 2003

ZnWO$_4$shows excellent frequency selectivity due to its high quality factor(Q${\times}$f) at microwave frequencies. However, in order to use ZnWO$_4$as multilayered wireless communication components, its other properties such as sintering temperature(105$0^{\circ}C$). $$\tau$_f$(-70ppm/$^{\circ}C$) and $$\varepsilon$_r$(15.5) should be modified. In present study, TiO$_2$and LiF were used to improve the microwave dielectric and sintering properties of ZnWO$_4$. TiO$_2$ additions to ZnWO$_4$changed $\tau$$_{f}$ from negative to positive value, and also increased $$\varepsilon$_r$, due to its high $$\tau$_f$(＋400ppm$^{\circ}C$) and $$\varepsilon$_r$(100). At 20 mol% TiO$_2$ addition, $$\tau$_f$was controlled to near zero ppm/$^{\circ}C$ with $$\varepsilon$_r$=19.4 and Q${\times}$ f=50000GHz. However, the sintering temperature was 110$0^{\circ}C$. LiF addition to the ZnWO$_4$＋TiO$_2$ mixture greatly reduced the sintering temperature from 110$0^{\circ}C$ to 85$0^{\circ}C$ due to liquid phase formation. Also LiF addition decreased the $$\tau$_f$value due to its high negative $$\tau$_f$ value. Therefore, by controlling the TiO$_2$and LiF amount. temperature stable LTCC(Low Temperature Cofired Ceramics) material with low loss in the ZnWO$_4$-TiO$_2$-LiF system could be fabricated.d.d.

• Journal of Biomedical Engineering Research
• /
• v.19 no.3
• /
• pp.251-260
• /
• 1998

The Holter monitoring system is a widely used noninvasive diagnostic tool for ambulatory patient who may be at risk from latent life-threatening cardiac abnormalities. In this paper, we design a high performance intelligent holter monitoring system which is characterized by the small-sized and the low-power consumption. The system hardware consists of one-chip microcontroller(68HC11E9), ECG preprocessing circuit, and flash memory card. ECG preprocessing circuit is made of ECG preamplifier with gain of 250, 500 and 1000, the bandpass filter with bandwidth of 0.05-100Hz, the auto-balancing circuit and the saturation-calibrating circuit to eliminate baseline wandering, ECG signal sampled at 240 samples/sec is converted to the digital signal. We use a linear recursive filter and preprocessing algorithm to detect the ECG parameters which are QRS complex, and Q-R-T points, ST-level, HR, QT interval. The long-term acquired ECG signals and diagnostic parameters are compressed by the MFan(Modified Fan) and the delta modulation method. To easily interface with the PC based analyzer program which is operated in DOS and Windows, the compressed data, that are compatible to FFS(flash file system) format, are stored at the flash memory card with SBF(symmetric block format).

• Geophysics and Geophysical Exploration
• /
• v.13 no.4
• /
• pp.307-314
• /
• 2010

Although conventional seismic data processing is based on the assumption that the media are isotropic, the subsurface is often anisotropy in shale formation or carbonate with cracks and fractures. This paper presents the anisotropic parameter and seismic modeling in transversely isotropic media with a vertical symmetry axis using seismic physical modeling. The experiment was successfully carried out with VTI media, laminated bakelite material, using contact transducer of p and s-wave transmission. The variation of velocities with angle of incidence was clearly shown in anisotropic material. Comparing these velocities with the calculated phase velocities, the (P) and (S)-wave velocity observed in anisotropic material was a very good agreement with the calculated values. Anisotropic parameter ${\varepsilon}$, ${\delta}$, ${\gamma}$ was estimated by using Lame's constant calculated from the observed velocity. For the purpose of testing (S)-wave polarization, a birefringence experiment was carried out. The higher velocity was associated with the polarization parallel to the fracture, and the lower velocity was associated with the polarization perpendicular to the fracture.

• Korean Journal of Remote Sensing
• /
• v.37 no.2
• /
• pp.199-209
• /
• 2021

By removing the increasing trend that long-term time series average of rice yield due to technological advancement of rice variety and cultivation management, we tried to improve the rice yield estimation model which developed earlier using MODIS NDVI and meteorological data. A multiple linear regression analysis was carried out by using the NDVI derived from MYD13Q1 and weather data from 2002 to 2019. The model was improved by analyzing the increasing trend of rime-series rice yield and removing it. After detrending, the accuracy of the model was evaluated through the correlation analysis between the estimated rice yield and the yield statistics using the improved model. It was found that the rice yield predicted by the improved model from which the trend was removed showed good agreement with the annual change of yield statistics. Compared with the model before the trend removal, the correlation coefficient and the coefficient of determination were also higher. It was indicated that the trend removal method effectively corrects the rice yield estimation model.

• Journal of Nutrition and Health
• /
• v.49 no.4
• /
• pp.247-257
• /
• 2016

Purpose: The aim of this study was to investigate the relationship between instant noodle intake and metabolic factors in Korean adults. Methods: Study subjects were 5,894 (male 2,293, female 3,601) aged 19~64 years who participated in the 2013~2014 KNHANES. Information on frequency and consumption of instant noodles was obtained by the food frequency questionnaires method in KNHANES (Korean National Health and Nutrition Examination Survey), and subjects were classified according to age, sex, and instant noodle consumption (INC). Results: The frequency and consumption of instant noodles was 1.2 times/week and 1.2 servings in subjects. High INC group (${\geq}1$ serving/week) was significantly younger in age compared with the low INC group (< 1 serving/week). However, the high INC group had significantly higher waist circumference, metabolic factors (triglyceride, cholesterol, and HDL-cholesterol), and dietary intake (energy intake, fat, and sodium density) compared with the low INC group. Hyperglycemia showed association with higher risk of highest quartile of INC after adjustments for multiple confounding factors, including age, gender, household income, education, smoking, and alcohol compared with the lowest quartile (OR: 1.4, 95% CI: 1.1-1.8). In female, abdominal obesity showed association with higher risk of highest quartile of INC after adjustments for multiple confounding factors compared with the lowest quartile (OR: 1.6, 95% CI: 1.2-2.2). Conclusion: Consumption of instant noodles was associated with increased prevalence of abdominal obesity and hyperglycemia in women. These findings suggest an association of instant noodle consumption status with metabolic risk.

• Journal of agricultural medicine and community health
• /
• v.29 no.2
• /
• pp.265-285
• /
• 2004

Objectives: The acute toxic effects of pesticide are well known. Concern has also been expressed that long-term exposure may result in damage to the central nervous system. This study was conducted to test the hypothesis that central nervous system symptoms might occur due to pesticide exposure. Methods: In a cross-sectional study, first, cumulative exposure index (CEI) was estimated. Neurologic symptoms (Q-16 questionnaire) for 541 farmers (exposed to pesticides) were compared with 119 non-exposed persons in spraying season nine rural areas in Korea. Results: The pesticides poisoning rates for last 3 months were 67.2% for orchard farmers, 55.3%for dry field farmers, and 20.5% for husbandry farmers, respectively, showing significant difference (p<0.001). Compared with non-exposure group, exposure groups (especially, orchard farmers) reported significantly more neurologic symptoms and had a higher overall neurological symptoms score (p<0.001). Factors related to the positive neurological symptoms (answers "yes" to six or more of Q-16 questionnaire) adjusted for age, sex, education level, smoking and alcohol drinking were type of farming (OR 3.08, 95% CI 1.50-6.30 in orchard farmers vs non-exposure group), CEI (OR 2.75, 95% CI 1.12-6.78 in Q3 vs Q1), past poisoning (OR 1.97, 95% CI 1.21-3.20 vs normal), current mild poisoning (OR 3.03, 9500 CI 1.47-6.22 vs normal) and current moderate poisoning (OR 6.34, 95% CI 3.03-13.25 vs normal), respectively. Conclusions: These results suggest that long-term exposure to pesticides appears to be associated with subtle changes in the central nervous system.

• Journal of Nutrition and Health
• /
• v.51 no.6
• /
• pp.556-566
• /
• 2018

Purpose: This study was designed to determine the relationship between health behaviors and high levels of low-density lipoprotein-cholesterol (LDL-cholesterol) according to cardiovascular risk factors among Korean adults. Methods: This cross-sectional study was based on the sixth Korea national health and nutrition examination survey (KNHANES VI). Participants were 13,841 adults aged 19 years and older. Cardiovascular risk factors were stroke, myocardial infarction or angina, diabetes mellitus, smoking, hypertension, aging, high density lipoprotein-cholesterol (HDL-cholesterol) under 40 mg/dL and HDL-cholesterol over 60 mg/dL. Cardiovascular risk groups were classified as very high risk (stroke, myocardial infarction or angina), high risk (diabetes mellitus), moderate risk (over 2 risk factors), and low risk (below 1 risk factor). The prevalence of high LDL-cholesterol was calculated using the LDL-cholesterol target level according to cardiovascular risk group. Results: The prevalence of high LDL-cholesterol was 25.5% in males and 21.7% in females. Complex sample cross tabulation demonstrated that the high LDL-cholesterol and normal groups differed significantly according to age, education, body mass index, percentage of energy from carbohydrate, fat, saturated fat and n-6 in males and females. These two groups were also significantly different according to smoking in males and the percentage of energy from n-3 in females. Complex sample multiple logistic regression analysis adjusted for multiple confounding factors demonstrated that the probability of high LDL-cholesterol was significantly associated with current smoking (OR: 1.66, 95% CI: 1.40-1.99), obesity (OR: 1.95, 95% CI: 1.64-2.31) in males, and current smoking (OR: 1.73, 95% CI: 1.19-2.52), obesity (OR: 1.63, 95% CI: 1.39-1.90), percentage of energy from n-3 (quartile 1 vs. quartile 2; OR: 0.77, 95% CI: 0.62-0.96; quartile 1 vs. quartile 3; OR: 0.73, 95% CI: 0.56-0.94; quartile 1 vs. quartile 4: OR: 0.67, 95% CI: 0.51-0.87) in females. Conclusion: This study reveals the impact of smoking, obesity, energy percentage of nutrient intake on LDL-cholesterol.

• The Journal of Korean Society for Radiation Therapy
• /
• v.13 no.1
• /
• pp.38-46
• /
• 2001

Purpose : The aim of this study is to investigate the effect of tissue inhomogeneities when appling to contrast medium among Homogeneous, Batho and ETAR dose calculation method in RTP system. Method and Material : We made customized heterogeneous phantom it filled with water or contrast medium slab. Phantom scan data have taken PQ 5000 (CT scanner, Marconi, USA) and then dose was calculated in 3D RTP (AcQ-Plan, Marconi, USA) depends on dose calculation algorithm (Homogeneous, Batho, ETAR). The dose comparisons were described in terms of 2D isodose distribution, percent depth dose data, effective path length and monitor unit. Also dose distributions were calculated with homogeneous and inhomogeneous correction algorithm, Batho and ETAR, in each patients with different clinical sites. Results : Result indicated that Batho and ETAR method gave rise to percent depth dose deviation $1.5{\sim}2.7\%,\;2.3{\sim}3.5\%$ (6MV, field size $10{\times}10cm^2$) in each status with and without contrast medium. Also show that effective path lengths were more increase in contrast status (23.14 cm) than Non-contrast (22.07 cm) about $4.9\%$ or 10.7 mm (In case Hounsfield Unit 270) and these results were similary showned in each patient with different clinical site that was lung. prostate, liver and brain region. Concliusion : In conclusion we shown that the use of inhomogeneity correction algorithm for dose calculation in status of injected contrast medium can not represent exact dose at GTV region. These results mean that patients will be more irradiated photon beam during radiation therapy.

• Geotechnical Engineering
• /
• v.13 no.6
• /
• pp.95-106
• /
• 1997

A pressuremeter is an expandable tube which is placed in the soil, and then expanded under controlled condition against the soil. From this test a pressure expansion curve of the soil can be obtained. However soil disturbance during the test has significant influence on the results of tests. A general governing equation for pressuremeter test can be theoretically derived on the basis of the hyperbolic soil model and the cavity expansion theory. The curve fitting technique was used to establish the pressure-strain curve without disturbance of soil during testing. This interpretation makes use of both the loading and unloading portions of the test. An interpretation methodology is described and illustrated with pressuremeter test data carried out in the weathered granitic soil to estimate initial shear modulus. Standard penetration test is a very common site investigation technique in Korea. Therefore the blow counts of standard penetration test are discussed by comparing them with initial shear modulus.

• Journal of the Korea Institute of Building Construction
• /
• v.19 no.6
• /
• pp.521-527
• /
• 2019

Quantity takeoff and cost estimates in Korea are carried out in practice without any clear standards or standards. Especially, quantity takeoff of Reinforcing bar and BoQ documentation process is very complex using 2D drawings. In this study, 10 case sites were analyzed for the status of inefficient quantity takeoff and how the statement was prepared. In order to solve this problem, this study presented a method for calculating the quantity of rebars through the ratio of concrete volume for schools, offices, and apartment buildings, and analyzed the accuracy of results. In the future, it is expected that the error range can be reduced by defining the factors affecting the results and calculating the correction value for them.