• 한국군사과학기술학회지
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• 제11권4호
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• pp.20-28
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• 2008

Missile operating at supersonic conditions experiences considerable high temperature environments that is caused by aerodynamic heating as a result of the temperature gradient through boundary layer that surrounds it. This is one of important problems to the designer due to temperature limitation of structural materials. Because prediction of aerodynamic heating on missile needs unsteady calculation according to a flight trajectory, approximate method approach is efficient at design stage. In this paper, improved aerodynamic heating analysis scheme is introduced, which calculates heat flow and temperature by simple pressure field prediction on a missile body and fin. The prediction results are compared with measured data and MINIVER codes results.

• 대한치과의사협회지
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• 제19권4호통권143호
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• pp.347-352
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• 1981

This experiment was performed to estimate the changes on blood flow of the oral structures in hemorrhagic shock. Rabbits were anesthetized by intravenous injection of nembutal(30mg/kg). The Femoral artery was exposed and cannulated with polyethylene tubing filled with heparinized saline. Hypovolemic shock was induced by collecting the bloos of which amount was equaled as 2 % of body weight through arterial cannula for about 30 minutes. During hemorrhage, arterial blood pressure was recorded on recorder. In hypovolemic shock, arterial blood pressure decreased from 116.2±4.1 mmHg to 62.6±4.0 mmHg. Distribution of blood flow in oral tissues decreased to 30-50 % of control group. But blood flow of the masseter muscle was increased and the mandibular angle was not changed.

• 동력기계공학회지
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• 제2권2호
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• pp.81-86
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• 1998

The dynamic response characteristics of Tension Leg Platforms(TLPs) in waves are examined for presenting the basic data for design of TLPs. The numerical approach is based on a combination of the three dimensional source distribution method and the dynamic response analysis method, in which the superstructure of TLP is assumed to be flexible instead of rigid. Restoring forces by hydrostatic pressure on the submerged surface of a TLP have been accurately calculated by excluding the assumption of the slender body theory. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in the motion and structural analysis. Numerical results are compared with the experimental ones, which are obtained in the literature, concerning the motion and tension responses of a TLP in waves. The results of comparison confirmed the validity of the proposed approach.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2000년도 춘계 학술대회논문집
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• pp.166-171
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• 2000

A two-dimensional/axisymmetric CSCM upwind flux difference splitting Wavier-Stokes method has been developed to study the finite rate chemically react-ing invisicd and viscous hypersonic flows over blunt-body. A upwind method was chosen due to its robustness in capturing the strong bow shock waves. For the nonequilibrium chemically reacting air, NS-I species conservation equations were strongly coupled with flowfield equations through convection and species production terms. The nonequilibrium wall pressure and heat transfer rate distributions along the vehicle were compared with those from equilibrium and perfect gas calculations. The nonequilibrium species distribution shows the reduced concentrations of O and N species when compared with equilibrium species distribution. The solutions resolved strong bow shock waves md heat transfer rate very accurately when compared with central difference schemes.

• 대한환경공학회지
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• 제37권11호
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• pp.607-618
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• 2015

본 연구에서는 CFD 모사와 PIV 기법을 이용하여 실규모의 사이드 스트림 방식의 막 모듈을 대상으로 유입부의 수리구조를 개선하여 모듈로 유입되는 유입 유량을 수직으로 균등하게 분포시킬 수 있는 방안을 제시하고 이를 실험적으로 검증하고자 하였다. 사이드 스트림 방식의 막 모듈을 대상으로 유입 유량을 수직으로 균등하게 분포시킬 수 있는 방안을 CFD로 설계한 결과, 내부 유입 수리구조에 유공 격벽을 설치함으로써 모듈내로의 유입유량은 표준편차 기준으로 약 40% 정도 감소됨을 확인하였다. 또한 CFD 결과를 검증하고 사이드 스트림 막 모듈의 편중된 오염의 원인을 조사하기 위해 수행된 입자영상유속 측정 결과로부터 유입구 반대편 유공에서 막 모듈 내부로 들어오는 수체의 유속이 상대적으로 커 수체의 모멘텀이 유입구 측벽에 강한 전단력을 발생하지만 유입구 반대 측벽에서는 사류가 형성됨을 확인하였다.

• 대한의용생체공학회:의공학회지
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• 제42권5호
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• pp.225-231
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• 2021

The purpose of this study was to investigate the effect on the activity of the upper trapezius and erector spinae according to the length difference of the backpack using electromyogram (EMG). We also conducted a study comparing the center of pressure (COP) and weight distribution before and after using Wii® balance board. Thirty individuals were randomly assigned to the experimental group (n=14) wearing a backpack with a short right strap length and a control group (n=16) wearing a backpack with the same strap length. Data were collected by dividing into groups, carring a 15% weight backpack and walking for 20 minutes on a treadmill. As a result of analyzing the EMG data, there was no significant change in the upper extremity muscle activity of the control group, but it was significantly decreased in the right upper trapezius activity of the experimental group (p<0.05). In addition, there was a significant change of COP in the experimental group (p<0.05), but there was no significant difference of the weight distribution in both groups. Recognizing mechanical changes in the body that may occur due to the asymmetry of the strap length is thought to be helpful for systematic ergonomic intervention according to changes in the external environment in the future.

• 한국연소학회지
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• 제9권3호
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• pp.10-18
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• 2004

An experimental study of the effect of operating conditions on the behavior of a lean premixed laboratory combustor operating on natural gas has been conducted. Measurements were made characterizing the pressure fluctuations in the combustor and the flame structure over a range of inlet temperatures, inlet velocities and equivalence ratios. In addition the fuel distribution at the inlet to the combustor was varied such that it was an independent parameter in the experiment. Inlet temperature, inlet velocity and equivalence ratio were all found to have an effect on the stability characteristics of the combustor. The nature of this effect, however, depended on the fuel distribution. For example, with one fuel distribution the combustor would become unstable when the temperature was increased, whereas with a different fuel distribution the combustor would become unstable when the temperature was decreased. Similarly, the operating conditions had an effect on the flame structure. For example the intensity-weighted center of mass of the flame was found to move closer to the center body as either the temperature or equivalence ratio increased. It was interesting and somewhat surprising to note, however, that as the location of the center of mass changed with operating conditions it did so by moving along a line of constant flame angle.

• 한국전문물리치료학회지
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• 제15권4호
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• pp.1-9
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• 2008

The purpose of this study was to assess the peak plantar pressure distribution under foot areas according to the height of heel lifts in obese adults and non-obese adults during walking. Thirty-one participants volunteered for this experiment. The average body mass index (BMI) value of the fourteen subjects in the obese group was $26.5{\pm}1.4kg/m^2$ (from 25.1 to 29.3 $kg/m^2$), and of seventeen subjects in the non-obese group was $20.0{\pm}1.1kg/m^2$ (from 18.7 to 22.7 $kg/m^2$). The subject ambulated while walking in the sneakers, walking with 2 cm heel lifts, and walking with 4 cm heel lifts in the shoes. We measured the peak plantar pressure under the hallux, 1st, 2nd, 3~4th, and 5th metatarsal head (MTH), mi foot, and heel using F-scan system. The obese group had significantly higher peak plantar pressure under all foot areas than the non-obese group regardless of the height of heel lifts (p<.05). The peak plantar pressure under the 5th MTH and heel was significantly decreased, also the peak plantar pressure under hallux, 1st, and 2nd MTH was significantly increased according to the height of heel lifts in the obese group and non-obese group (p<.05), We proposed that individuals with heel lifts in shoes should be careful, as there is high plantar pressure under the forefoot.

• 구강회복응용과학지
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• 제19권2호
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• pp.57-67
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• 2003

Suppose that dental occlusion is related to body posture. We want to find out that improving occlusal balance may affect vibration and distribution of C.O.P. in which way, by measuring change of posture and center of gravity (center of pressure, C.O.P.) which plays important role in measuring balance sensation. Total 11 students at Kyung Hee dental college students, 4 females and 9 males (age: 23-30) participated in this test, who have normal occlusion (Angle's classification I), no TMJ problems. All of the participants have no tooth loss except 3rd molar, no prosthesis over single tooth restoration, no orthopedic problems which affect balance sensation, and no otorhinolaryngological problems. First, we registrated bite by centric relation, and then fabricated stabilization splint that is increased 3.5mm vertical dimension around premolar region. By F-scan (Tekscan Inc., Boston, Mass), we measured discrepancy of average contact pressure of left and right foot. And we also measured discrepancy of vibration of C.O.P(center of pressure). before setting stabilization splint and after wearing stabilization splint at intervals of 1 week, 2 weeks, 3 weeks after. In normal human beings, improved occlusal balance by stabilization splint leads to decrease of vibration of C.O.P. (P<0.05). One week after wearing stabilization splint, vibration of C.O.P. decreased reliably (P<0.05), two weeks after wearing stabilization splint, vibration of C.O.P. decreased similarly comparing to before wearing and one week after wearing. (P<0.05) After two weeks and three weeks, however, it was hard to find reliability. (P>0.05) Difference between average contact pressure of right and left foot also decreased. (P<0.05) We could find decrease after one week of wearing stabilization splint (P<0.05) and two weeks after, the decrease was more reliable than one week after. (P<0.05) After two weeks and three weeks, however, it was hard to find reliability. Improvement of occlusal balance leads to decrease of vibration of C.O.P. and decrease of difference between right and left average contact pressure.

• Journal of Nutrition and Health
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• 제36권1호
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• pp.64-74
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• 2003

The purpose of this study was to investigate the distribution patterns of serum triglyceride and cholesterol levels and the influence of environmental and dietary factors in 201 healthy male subjects. The subjects were found to be 53.7% for the normal, 15.4% for the TC, 17.4% for TG and 13.5% for TC.TG group, respectively. Among general characteristics, smoking significantly affected serum lipid levels of subjects (p < 0.05). Among anthropometric factors, body weight, BMI and PIBW significantly influenced the blood lipid patterns. Body weight of TG group was significantly higher than that of normal group (p < 0.05). BMI and PIBW of TG group and TC.TG group were significantly higher than those of normal group (p < 0.05) . In addition, diastolic blood pressure of TG group was significantly higher than that of normal group (p < 0.05). For the food intake, average intake of fruit was significantly higher in normal group than that of TG group (p < 0.05). For nutrient intake, calcium intake was significantly higher in TC group than those of normal and TC.TG group (p <0.05). Intakes of vitamin $B_2$ and C were significantly higher in TC group than those of in TG group (p < 0.05). Serum HDL-cholesterol level was negatively related to meat, poultry, and their products (p <0.05), but serum total cholesterol level positively related to animal lipids (p < 0.05). The results of this study suggest that it is crucial for maintaining adequate serum lipid levels to reduce smoking, blood pressure and to lose body weight. As far as food intake concerned, fruit intake was important in maintaining serum triglyceride level normal, while animal food intake affected serum total cholesterol level adversely. (Korean J Nutrition 36(1): 64-74, 2003)