• Journal of the Korean Society of Visualization
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• v.5 no.2
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• pp.20-25
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• 2007

The geometry of a commercial passenger airplane is realized based on a Boeing 747-400 model through the photographic scanning and reverse engineering. The each element consisting of the plane such as fuselage, wing, vertical fin, stabilizer and engines, is individually generated and then the whole body is assembled by the photomodeler. The maximum error in the realized airplane is about 1.4% comparing with the real one. The three-dimensional inviscid steady compressible governing equations are solved in the unstructured tetrahedron grid system, and in a finite volume method using STAR-CD when the airplane flies at the cruise condition. The pressure distribution on the surface and the wing-tip vortices are visualized, and in addition to the aerodynamics coefficients, lift and drag are estimated.

• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.81-84
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• 2002

Dispersion of coolant jets in a film cooling flow field is the result of a highly complex interaction between the film cooling jets and the mainstream. In order to investigate the effect of blowing ratios on the film cooling of turbine blade, cylindrical body model was used. Mainstream Reynolds number based on the cylinder diameter was $7.1\;\times\;10^4$. The free-stream turbulence intensity kept at $5.0\%$ by using turbulence grid. The effect of coolant flow rates was studied for blowing ratios of 0.9, 1.3 and 1.6, respectively. The temperature distribution of the cylindrical model surface is visualized by infrared thermography (IRT). Results show that the film-cooling performance may be significantly improved by controlling the blowing ratio. As blowing ratio increases, the adiabatic film cooling effectiveness is more broadly distributed and the area protected by coolant increases. The mass flow rate of the coolant through the first-row holes is less than that through the second-row holes due to the pressure variation around the cylinder surface.

• Korean Journal of Community Nutrition
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• v.4 no.4
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• pp.521-528
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• 1999

Cardiovascular disease is very prevalent in Korea, and many risk factors, if properly identified are possibly corrected. However, the study results on prevalence and distribution of risk factors may not be reliable while the risk factors of disease are always issued on health promotion projects conducted recently in a community. The subjects of this study were 854 adults who participated in the health and nutrition survey in a community. They were aged between 20 and 69 and sampled representatively. This study intended to estimate the prevalence and the distribution of risk factors of cardiovascular disease such as hypertension, diabetes mellitus, hypercholesterolemia, and obesity. Systolic blood pressure and diastolic blood pressure levels were estimated at $123.9{\pm}2.2mgHg(men)$, $117.9{\pm}1.7mgHg$(women), and $80.4{\pm}1.5mg(men)$, $74.9{\pm}1.1mgHg(women)$, respectively. Glucose level was estimated at $99.1{\pm}2.3mg/dl$ in men, and $95.7{\pm}1.7mg/dl$ in women. The estimated level of total cholesterol and HDL-cholesterol were $183.4{\pm}3.8mg/dl(men)$, $181.7{\pm}3.1mg/dl(men)$, and $122.0{\pm}4.5mg/dl(women)$, and body mass index was estimated at $24.0{\pm}0.4kg/m^2$ in men and $23.9{\pm}0.4kg/m^2$ in men and $23.9{\pm}0.3kg/m^2$ in women. The prevalence of hypertension was 20.5% for men, and 14.4% for women. The prevalence of diabetes mellitus was estimated to 6.9% for men, and 6.1% for women. The estimated prevalence of hypercholesterolemia was 3.8%(men), 3.9%(women). The rate of obesity was estimated to 28.5%(men), 28.4% (women), respectively. The levels of blood pressure, glucose, and cholesterol were higher in men than in women in almost all the almost ate groups. The prevalence of hypertension for men is about 20%. It was found that the prevalence of diabetes mellitus for males aged between 40 and 59 was rapidly increased. The risk factor with highest prevalence was obesity, and hypertension and diabetes mellitus were the second and third most prevalent.

• Journal of agricultural medicine and community health
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• v.18 no.1
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• pp.43-54
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• 1993

In order to find the factors associated with the death of hypertensives, 12 year follow-up study for 267 hypertensives whose average blood pressure were 140/90 mmHg or above during their first health screening in 1979-1980 at YongJin Township, Wanju Country, North Cholla Province by the Community Health Team of Chonju Presbyterian Medical Center. The study results are as follows : 1. Initial general characteristics of hypertensives were studied. The age distribution of studied hypertensives showed 27.3% in 40-49 years, 25.8% in 50-59 years, 29.6% in 60-69 years and 17.2% In 70 + years old group. Marital status showed that 82.8% of hypertensives had their wife or husband. 74. 5% were employed on agriculture. 56.5% of hypertensives were illiterate. 2. Among the hypertensives, 91.6% of male and 22.8% of female reported that they were smokers. 82.6% of hypertensives had body mass index lower than 25 Kg/$m^2$. 46.8% of average systolic blood pressure were 160mmHg or above and 54.3% of average diastolic blood pressure were 95mmHg or above. 3. Twenty percent of hypertensives reported that they were treating hypertension at the beginning of follow up, while 68.5% reported that they were not treated. 28.1% reported that they were treating hypertension within 6 months before last follow-up. but 69.3% reported that they were not treated for hypertension within Ii months before last follow up. So 50.6% were classified as never treated group and 41.2% as treated group. 4. Average blood pressure for initial 3 years were calculated. The change of average systolic blood pressure was observed as $161.3{\pm}19.4mmHg$ at the first year, $145.6{\pm}28.0mmHg$ at the second year and $141.4{\pm}37.2mmHg$ at the third year. Average diastolic blood pressure were changed from $96.2{\pm}14.4mmHg$ at the first year to $90.6{\pm}18.6mmHg$ at the second year and $86.4{\pm}22.9mmHg$ at the third year. 5. By the follow-up of hypertensives, 54 hypertensives (46.2%) among 117 male hypertensives and 50 hypertensives (33.3%) among 150 female hypertensives died for 12 years. 42.6% of male death and 52.0% of female death were caused by cerebrovascular diseases. 6. Through univariate statistical test about the association between general characteristics or cardiovascular risk factors of hypertensives and mortality for 12 years, age variable among male and among female age, marital status, occupation. educational level. systolic blood pressure and treatment status were shown as significant variable to influence upon the mortality. 7. By multiple logistic regression analysis, among male age and systolic blood pressure were selected as significant variable to be associated with the total mortality for 12 years. Among female age, systolic blood pressure and treatment status were selected as statistically significant variable to be associated with the total mortality for 12 years.

• Geotechnical Engineering
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• v.12 no.6
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• pp.65-78
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• 1996

The Chungpyung Dam is a 16 yearn old rock-fill dam for a Pumped storage hydro-Power plant, located in the middle of the Korean Peninsula. Since the dam is subjected to the daily water level fluctuation, such as rapid drawdown and refill, thus inducing a structural impact on the behavior of dam body, it draws attention of many engineering concerns. Traditionally, steady-state analysis was employed to investigate the seepage in the dam body, but in this study the seepage analysis was numerically performed by 2-D FEM thansient analysis. As a boundary condition for an analysis, the water level fluctuation was incorporated to simulate the daily change. As a res41t, the various seepage phenomena such as hydraulic gradient, seepage vector, and pore water pressure distribution were quantified at the corresponding time of interest as the water level rises and recedes. The seepage flux was also estimated and compared with the measured data which were both acceptable considering design criteria. The result proves that there is no sign of hazardous sources contributing to the possibility of piping, internal erosion and excess leakage through the dam body.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.1
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• pp.82-90
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• 2000

An experimental study has been carried out at circulating water channel to investigate the non-breaking and breaking waves generated by a submerged circular cylinder steadily moving under the free surface. Free surface profiles and pressure distributions on cylinder surface were measured at various submerged depths of cylinder. They were complemented by the measurements of velocities, head losses and turbulence intensities in the wakes of body and "breaker". Part 1 of this three-part paper describes the experimental arrangement and the patterns of wave profile and pressure distribution at various depths of submergence. These databank contributions are of special interest in traditional ship hydrodynamics. In Part 2, special focuses are made to elucidate the viscous and turbulent aspects of flow field. Finally Part 3 will deal with the visualization of instantaneous vortical flow to study the mutual interaction between vorticies shedded from the free-surface and the cylinder using a Particle Image Velocimetry.

• Wind and Structures
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• v.20 no.4
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• pp.579-607
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• 2015

A Combination Random Flow Generation (CRFG) technique for obtaining the fluctuating inflow boundary conditions for Large Eddy Simulation (LES) is proposed. The CRFG technique was developed by combining the typical RFG technique with a novel calculation of k and ${\varepsilon}$ to estimate the length- and time-scales (l, ${\tau}$) of the target fluctuating turbulence field used as the inflow boundary conditions. Through comparatively analyzing the CRFG technique and other existing numerical/experimental results, the CRFG technique was verified for the generation of turbulent wind velocity fields with prescribed turbulent statistics. Using the turbulent velocity fluctuations generated by the CRFG technique, a series of LESs were conducted to investigate the wind flow around S-, R-, L- and U-shaped building models. As the pressures of the models were also measured in wind tunnel tests, the validity of the LES, and the effectiveness of the inflow boundary generated by the CRFG techniques were evaluated through comparing the simulation results to the wind tunnel measurements. The comparison showed that the LES accurately and reliably simulates the wind-induced pressure distributions on the building surfaces, which indirectly validates the CRFG technique in generating realistic fluctuating wind velocities for use in the LES. In addition to the pressure distribution, the LES results were investigated in terms of wind velocity profiles around the building models to reveal the wind flow dynamics around bluff bodies. The LES results quantitatively showed the decay of the bluff body influence when the flow moves away from the building model.

• Geomechanics and Engineering
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• v.28 no.3
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• pp.265-281
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• 2022

A set of slurry shield test system capable of cutter cutting and slurry automatic circulation is used to investigate the deformation characteristics, the evolution characteristics of support resistance and the distribution and evolution process of earth pressure during excavating and collapsing of slurry shield tunneling in circular-gravel layer. The influence of cover-span ratio on surface subsidence, support resistance and failure mode of excavation face is also discussed. Three-dimensional numerical calculations are performed to verify the reliability of the test results. The results show that, with the decrease of the supporting force of the excavation face, the surface subsidence goes through four stages: insensitivity, slow growth, rapid growth and stability. The influence of shield excavation on the axial earth pressure of the front soil is greater than that of the vertical earth pressure. When the support resistance of the excavation face decreases to the critical value, the soil in front of the excavation face collapses. The shape of the collapse is similar to that of a bucket. The ultimate support resistance increase with the increase of the cover-span ratio, however, the angle between the bottom of the collapsed body and the direction of the tunnel excavation axis when the excavation face is damaged increase first and then becomes stable. The surface settlement value and the range of settlement trough decrease with the increase of cover-span ratio. The numerical results are basically consistent with the model test results.

• The Korean Journal of Pain
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• v.35 no.3
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• pp.240-249
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• 2022

Background: Widespread pain partially depends upon sensitization of central pain mechanisms. However, mechanisms controlling pain distribution are not completely known. The present study sought to assess skin temperature variations in the area of experimentally-induced pain and potential sex differences. Methods: Pressure-pain thresholds (PPTs) were measured on the right infraspinatus muscle. At the end of Day 0, all participants performed an eccentric exercise of the shoulder external rotators to induce muscle soreness 24 hours after. On Day 1, participants indicated on a body chart the area of pain induced by 60 seconds of suprathreshold pressure stimulation (STPS; PPT + 20%) on the right infraspinatus muscle. Skin temperature variations in the area of referred pain were recorded with an infrared thermography camera, immediately before and after the STPS. Results: Twenty healthy, pain-free individuals (10 females) participated. On Day 0, the pre-STPS temperature was higher than the post-STPS temperature on the arm (P = 0.001) and forearm (P = 0.003). On Day 1, the pre-STPS temperature was higher than the post-STPS temperature on the shoulder (P = 0.015), arm (P = 0.001), and forearm (P = 0.010). On Day 0, the temperature decrease after STPS in females was greater than in males on the forearm (P = 0.039). On Day 1, a greater temperature decrease was found amongst females compared with males at the shoulder (P = 0.018), arm (P = 0.046), and forearm (P = 0.005). Conclusions: These findings indicate that sympathetic vasomotor responses contribute to expand pressure-induced referred pain, especially among females.

• Korean Journal of Applied Biomechanics
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• v.26 no.1
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• pp.115-126
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• 2016

Objective: The purpose of this study was to investigate plantar foot pressure and static balance according to the type of insole in the elderly. Methods: Thirteen elderly (mean age: $67.08{\pm}2.25years$, mean height: $159.63{\pm}9.64cm$, mean body weight: $61.48{\pm}9.06kg$) who had no previous injury experience in the lower limbs and a normal gait pattern participated in this study. Three models of insoles of the normal, 3D, and triangle types were selected for the test. The Pedar-X system and Pedar-X insoles, 3.3 km/h of walking speed, and a compilation of 20 steps walking stages were used to analyze foot-pressure distribution. Static balance test was conducted using Gaitview AFA-50, and balance (opening eyes, closing eyes) was inspected for 20 s. One-way ANOVA was conducted to test the significance of the results with the three insoles. p-value of less than .05 was considered statistically significant. Results: The mean foot pressure under the forefoot regions was the lowest with the 3D insole during treadmill walking (p<.05). The mean value under the midfoot was the highest with the 3D insole (left: p<.05, right: p<.01). The mean value under the rearfoot was the lowest with the 3D insole (p<.001). The maximum foot pressure value under the foot regions was the lowest on both sides of the forefoot with the 3D insole. A statistically significant difference was seen only in the left foot (p<.01). The maximum value under the midfoot was the highest with the 3D insole (p<.001). No statistically significant difference was detected on the values under the rearfoot. In the case of vertical ground reaction force (GRF), statistically significant difference was seen only in the left side rearfoot (p<.01). However, static balance values (ENV, REC, RMS, Total Length, Sway velocity, and Length/ENV) did not show significant differences by the type of insole. Conclusion: These results show that functional insoles can decrease plantar pressure and GRF under the forefoot and rearfoot. Moreover, functional insoles can dislodge the overload of the rearfoot and forefoot to the midfoot. However, functional insoles do not affect the static balance in the elderly.