• Magazine of the Korean Society of Agricultural Engineers
• /
• v.35 no.3
• /
• pp.36-46
• /
• 1993

The purposes of this study are to develop three-layered Green-Ampt infiltration model considering temporal variation of physical properties of soil and to evaluate the model with field experiment on bare-tilled and soybean-growing soil plots under natural rainfalls. Infiltration tests were conducted on a sandy loam soil. The model has three-layered soil profile including a surface crust, a tilled layer, a subsoil and considers temporal variation of porosity, hydraulic conductivity, capillary pressure head on a tilled layer by natural rainfalls and canopy density variation of crop. Field measurement of porosity, average hydraulic conductivity and average capillary presure head on a tilled layer were conducted by soil sampler and air-entry permeameter at regular intervals-after tillage. It was found that temporal variation of porosity and average hydraulic conductivity might be expressed as a function of cumulative rainfall energy and average capillary pressure head might be expressed as a function of porosity of a tilled soil. The model was calibrated by an optimization technique, Hooke and Jeeves method using hourly surface runoff data. With the calibrated parameters, the model was verified satisfactorily.

• Nuclear Engineering and Technology
• /
• v.31 no.1
• /
• pp.29-48
• /
• 1999

Local two-phase flow parameters of subcooled flow boiling in inclined annulus were measured to investigate the effect of inclination on the internal flow structure. Two-conductivity probe technique was applied to measure local gas phasic parameters, including void fraction, vapor bubble frequency, chord length, vapor bubble velocity and interfacial area concentration. Local liquid velocity was measured by Pilot tube. Experiments were conducted for three angles of inclination; 0$^{\circ}$(vertical), 30$^{\circ}$, 60$^{\circ}$. The system pressure was maintained at atmospheric pressure. The range of average void fraction was up to 10% and the average liquid superficial velocities were less than 1.3 m/sec. The results of experiments showed that the distributions of two-phase How parameters were influenced by the angle of channel inclination. Especially, the void fraction and chord length distributions were strongly affected by the increase of inclination angle, and flow pattern transition to slug flow was observed depending on the How conditions. The profiles of vapor velocity, liquid velocity and interfacial area concentration were found to be affected by the non-symmetric bubble size distribution in inclined channel. Using the measured distributions of local phasic parameters, an analysis for predicting average void fraction was performed based on the drift flux model and flowing volumetric concentration. And it was demonstrated that the average void fraction can be more appropriately presented in terms of flowing volumetric concentration.

• 유체기계공업학회:학술대회논문집
• /
• 2002.12a
• /
• pp.273-278
• /
• 2002

The characteristics of tip vortex within a blade tip region were examined experimentally in various flow coefficients by the way of changing tip clearance and blade stagger angle in an axial Low Speed Research Compressor(LSRC). The objective was to identify the unsteady pressure distribution in the blade passage by ensemble average technique acquired from high-frequency response pressure transducers and the tip vortex by root mean square value(RMS value). Data were reduced statistically using phase-lock technique for detailed pressure distributions.

• Geophysics and Geophysical Exploration
• /
• v.15 no.4
• /
• pp.163-176
• /
• 2012

Effective porosity has been measured for cement specimen as a function of vacuum time and pressure in the vacuum saturation process. Six cement specimen are used; three of them are made of the same ratio of cement and sand, the other three are 100% cement mortar, of which average porosity is about 25% and 40%, respectively. Using the 6 samples, measured effective porosities are compared and examined with 5 different vacuum pressures (2, 4, 6, 8, 10 torr) and times (20, 40, 60, 80, 100 minute), respectively. Comparing measured effective porosity from experiments when vacuum time varies from 100 minute to 20 minute with 20 minute step and vacuum pressure is fixed to 10, 6, and 2 torr, average deviation decreases as 0.6, 0.5, and 0.2% respectively. Comparing measured effective porosity from experiments when vacuum pressure varies from 2 torr to 10 torr with 2 torr step and vacuum time is fixed to 100, 60, and 20 minute, average deviation increases as vacuum time decreases. These results can be a background of suggested method of ISRM that describes the vacuum time longer than 60 minute and vacuum pressure higher than 6 torr. In this study, only qualitative discussion can be possible for the effects on the effective porosity by decreasing 20 minute vacuuming time at the same pressure or by decreasing 2 torr of vacuum pressure at the same vacuum time. This is because the sample could not reached to perfectly dried condition even though the sample were dried at $105^{\circ}C$ and following the ISRM suggested method, so that initial water content could not be the same at each experiment.

• Tribology and Lubricants
• /
• v.20 no.5
• /
• pp.284-291
• /
• 2004

We present a three-dimensional average flow model considering elastic deformation of pad asperities for chemical mechanical planarization. To consider the contact deformation of pad asperities in the calculation of the flow factor, three-dimensional contact analysis of a semi-infinite solid based on the use of influence functions is conducted from computer generated three dimensional roughness data. The average Reynolds equation and the boundary condition of both force and momentum balance are used to investigate the effect of pad roughness and external pressure conditions on film thickness and wafer position angle.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.1
• /
• pp.57-63
• /
• 2012

In this study, numerical analyses were performed on pressure drop and heat transfer characteristics in a rectangular horizontal channel with dimple and protrusion arrays of different height. The dimples/protrusions were installed at both top and bottom walls of the rectangular channel. The dimple and protrusion depths are 0.125, 0.2, 0.25, 0.3, and 0.375 times diameter. In case of the dimple, the highest Nusselt number occurred at the rear side of the dimple, and the average Nusselt number tended to decrease slightly with increase of depth. In case of protrusion, on the other hand, the highest Nusselt number occurred at the front side of the protrusion, and the average Nusselt number was increased with the increase of height. In both dimple and protrusion, the average Nusselt number and pressure drop were increased with the increase of velocity. Performance factor was decreased with the increase of velocity, and it was found that the best performance factor was obtained in the low velocity region.

• Journal of Nutrition and Health
• /
• v.34 no.3
• /
• pp.313-321
• /
• 2001

The purpose of this study is to verify the relation between vegetarian diet and the risk factors of cardiovascular disease. To do the present study the vegetarians were selected;245 Buddhist nuns(age: 23-79yrs). For control subjects, 235 healthy female adults(age: 23-79yrs) were selected. They were the teachers, the nurses and the housekeepers living in Chinju Gyeongsang Namdoo Province. Study period was from October 1996 to February 1997. The contents are consist of survey, anthropometric measurement, and clinical examination. The average ages of the subjects were 44.20yrs for vegetarians and 40.52yrs for non-vegetarians respectively. Average body mass indice(BMI) of vegetarians and non-vegetarians were 22.47 and 21.08, WHR was 0.85 and 0.84, percentage of body fat was 28.79 and 26.55 and the average duration of vegetarian diet of the vegetarians was 13.16 years. On the nutrient related lipid, fat, the energy ratio of fat, saturated fatty acid, total fatty acid, monounsaturated fatty acid and total-cholesterol were significantly lower(p<0.01) but the ratio of p/s was significantly higher(p<0.01) in vegetarians than non-vegetarians. The vegetarians were significantly higher than the non-vegetarians in intake of fiber, vitamin C. In vegetarians, variables that significant negative correlation with fiber were total-cholesterol, AI, blood sugar. In non-vegetarians, variables that significant negative correlation with fiber were TG, total-cholesterol, blood sugar, systolic blood pressure. In both subjects, the serum lipid concentration and the blood pressure were getting lower with fiber intakes. Consequently, vegetable diet can be considerably effective in making the level of the risk factors causing in cardiovascular disease lower. (Korean J Nutrition 34(3) : 313∼321, 2001)

• Journal of Community Nutrition
• /
• v.8 no.2
• /
• pp.63-68
• /
• 2006

This research analyzed the hematological index and health related habits such as alcohol drinking, smoking and exercise, by classifying 539 middle-aged men (age: 40 - 59) into a normal weight group, an overweight group and an obese group, according to BMI (body mass index). As a result, 33.6% (n = 181) of subjects had a BMI of 23 or less and 30.2% (n = 163) were overweight and 36.2% (n = 195) were obese (BMI > 25). The average systolic/diastolic blood pressures of total subjects were 130.96mmHg and 80.38mmHg, respectively. And the average pressure of normal subjects was 126.85/77.57mmHg, which was significantly lower than in overweight and obese subjects. Diastolic blood pressure shows significant differences among the three groups. The overall average cholesterol level of normal subjects was 193.81mg/dl, which was significantly lower than those in overweight subjects. Those in obese subjects were significantly higher than in overweight subjects. The GOT (glutamic oxaloacetic transaminase), GPT (glutamic pyrutic transaminase), ${\gamma}$-GTP (gamma-glutamyl transpeptidase) levels of obese subjects were significantly higher than in the overweight subjects. Frequency of alcohol drinking showed no significant difference among the groups. The smoking ratio in the obese group was higher than in the normal and overweight groups. The ratio of smokers was 53.1 %, and the alcohol drinking ratio was 81.0% of the total subjects. The frequency of drinking showed significant correlations with systolic blood pressure (p < 0.05) and diastolic blood pressures (p < 0.01) and ${\gamma}$-GTP (p < 0.01). The duration of smoking showed a negative correlation (p < 0.01) with diastolic blood pressure, total cholesterol and ${\gamma}$-GTP. On the other hand, exercising frequency showed negative correlations with blood glucose, ${\gamma}$-GTP and GPT(p < 0.01). These hematological indices were correlated with health related habits such as alcohol drinking, smoking and lack of exercise, and to be the cause of chronic diseases. Therefore, proper nutritional education is needed to establish advisable health related habits to maintain proper body weight. (J Community Nutrition 8(2): 63-68, 2006)

• Journal of Community Nutrition
• /
• v.7 no.3
• /
• pp.130-134
• /
• 2005

This study was conducted by surveying 616 male workers living in Ulsan City regarding their health status based on lifestyles such as alcohol consumption, smoking and exercising as well as physical measurements and biochemical tests. The average height, weight and BMI(body mass index, $kg/m^2$) of the subjects was 170.9cm, 70.2kg and 24.2, respectively. The rate of drinking was $80.9\%$ and the rate of smoking was $53.4\%$. Seventy four percent of subjects responded that they exercise regularly. The results of the blood biochemical tests revealed that the average hemoglobin concentration was 14.7g/dl, and the levels of GPT(glutamic pyruvic transaminase) and GOT (glutamic oxaloacetic transaminase) were 32.74unit/l, 26.99 unit/l, respectively. The average hemoglobin concentration for the subjects aged in the 50s was 14.39g/dl, which was significantly lower than those in the 20s(14.81g/dl), 30s(14.69g/dl) and 40s(14.73g/dl). The blood glucose level and the cholesterol level also increased with age. Also investigated was the blood pressure of the subjects increased with age,. and there was a significant increase(p < 0.05) for the subjects in the 50s compared to those in the 20s. The frequency of alcoholic beverages was significantly correlated with systolic/ diastolic blood pressure(p < 0.05) and $\gamma-GTP(gamma\;glutamyl\; transpeptidase)$(p<0.01). The duration of smoking showed a negative correlation(p < 0.05) with the hemoglobin and positive correlations with diastolic blood pressure, cholesterol and $\gamma-GTP(p<0.01)$. The study shows that blood pressure, blood glucose level, cholesterol level, GOT, GPT and $\gamma­GTP$ level, increase with age, which indicates higher possibility of degenerative diseases, calling for nutritional education in terms of advisable lifestyles regarding eating habits, alcohol consumption, smoking and regular exercise.

• Journal of Korean Academy of Nursing
• /
• v.31 no.4
• /
• pp.631-640
• /
• 2001

Purpose: The purpose was to investigate the physiological parameters and health perception of adults in Kyungi province area, and the correlation between these variables. The subjects were 95 adults who participated voluntarily in the health examination program. Methods: The instruments for this study were physiological parameters, which were composed of blood pressure, blood sugar, and body fat. The health perception scale developed by Ware (1976), and the health practice performance scale developed by Chang et al. (1999). Results: The average blood pressure was 137/85mmHg, the average blood sugar was 108.56mg/dl, and the average body fat arm sunt was 27.08% in males, and 30.07% in females. There were significant negative correlation between health perception and blood sugar (r=-2.36, p=.01), and body fat (r= -2.77, p=.001). There were significant positive correlations between blood pressure and health behavior (r=2.76, p=.001). However a significant correlation between health perception and health behavior was not found. Of the sociodemographic characteristics, sex (F=5.42, p=.01), and marital status (F=3.29, p=.04) were related to blood pressure. Also sex (F=4.17, p=.04) was related to body fat, and sex (t=4.04, p=.03) was related to health perception and disease status (t=4.33, p=.040). Thus having a relationship with health behavior. Conclusion: It is suggested that health perception provide important information about health status. However, this study has not shown a correlation between health perception and health behavior. Therefore further research is needed to find the other variables related to health behavior.