• 대한기계학회논문집B
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• 제28권6호
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• pp.713-725
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• 2004

The two-dimensional motion of a freely falling circular cylinder in an infinite fluid is investigated numerically using combined formulation. The effect of vortex shedding on the motion of a freely falling cylinder is clearly seen: as the streamwise velocity of the cylinder increases due to gravity, the periodic vortex shedding induces a periodic motion of the cylinder. This motion in turn affects the flow field, which is manifested by the generation of the angular velocity vector of the cylinder parallel to the cross product of the gravitational acceleration vector and the transverse velocity vector of the cylinder. A correlation of St-Re relationship for a freely falling circular cylinder is drawn from the present results. The Strouhal number for a freely falling circular cylinder is found to be smaller than that for a fixed circular cylinder when the two Reynolds numbers based on the streamwise terminal velocity of a freely failing circular cylinder and the free stream velocity of a fixed one are the same. From "thought experiments", it is shown that the transverse motion of the cylinder plays a crucial role in reducing the Strouhal number and has an effect of reducing the Reynolds number from the viewpoint of the pressure coefficient. The mechanism of this reduction in the Strouhal number is revealed by the fact that the freely falling cylinder experiences a smaller lift force than the fixed one due to the transverse motion resulting in the retardation of the vortex shedding.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.69-79
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• 2000

Falling film rectification involves simultaneous heat and mass transfer between vapor and solution film. In the present work, the adiabatic rectification process of ammonia-water vapor by the falling solution film on the vertical plate was investigated. The continuity momentum, energy and diffusion equations for the solution film and the vapor mixture were formulated in integral forms and solved numerically, The model could predict the film thickness, the pressure gradient, and the mass transfer rate. The effects of Reynolds number and ammonia concentration of solution and vapor mixture, rectifier length, and the enhancement of mass transfer coefficient in each phases were investigated. The stripping of water in vapor mixture occurred near the entrance of ammonia solution, which imposed the proper size of an adiabatic rectifier. Rectifier efficiency increased as film Reynolds number increased and as vapor mixture Reynolds number decreased. The improvement of rectifier efficiency was significant with the enhancement of mass transfer coefficient in falling film.

• 혜화의학회지
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• 제21권2호
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• pp.113-120
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• 2013

The object of this study was to investigate the relation between variables that is related to the general characteristics, fear of falling and falls efficacy. Data were collected from a convenience sample of 105 elders. Fear of falling and falls efficacy are measured structured questionnaires each. This study analyzed by SAS program. There was a significant difference of fear of falling according to education level(p=.003), body mass index(p=.016). There was a significant difference of falls efficacy according to gender(p<.001), education level(p=.047), body mass index(p=.019), number of chronic disease(p=.021). Fear of falling and age(r=0.23, p=.018) had significant positive correlations in the elders. Falls efficacy and number of chronic disease(r=-0.26, p=.010) had significant negative correlations in the elders. Fear of falling and falls efficacy are mutually contradictious concept. Also, both are important for the health of elderly. This result can be used for the elderly care and development of the program for the improvement of the falling efficacy.

• PNF and Movement
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• 제12권4호
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• pp.259-266
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• 2014

Purpose: The purpose of this study is to describe the effects of proprioceptive neuromuscular facilitation (PNF) on gait speed and genu recurvatum episodes in stroke patients. Methods: The patient is a 58-year-old woman with left hemiplegia who presented with genu recurvatum while walking. Each week the patient received two sessions of PNF that each lasted 45 minutes. During a six-week interval the patient underwent therapeutic exercises and occupational therapy five times a week between the two PNF treatments. During each treatment a preand post-test (a 4 m walk test) was conducted, the patient described their fear of falling down (10-point visual analogue scale), and the number of genu recurvatum episodes was recorded. Results: After the first PNF treatment, the fear of falling down was decreased from 8 points to 7 points, and the number of genu recurvatum episodes decreased from 11 to 6. After the second PNF treatment, the fear of falling down decreased from 6 points to 5 points, and the number of genu recurvatum episodes decreased from 5 to 1. The 4 m walking test time also decreased from 30 seconds to 24 seconds. Conclusion: The PNF treatment is beneficial for reducing the fear of falling down, reducing the number of genu recurvatum episodes, and improving the gait speed of stroke patients.

• 대한간호학회지
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• 제37권7호
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• pp.1184-1192
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• 2007

Purpose: The purpose of this study was to examine the relationship among fear of falling, pain, anxiety and depression, and to identify influencing factors in elderly women patients with degenerative arthritis living in the community. Method: The subjects of this study were 297 elderly women patients with degenerative arthritis. Data was collected by personal interviews using questionnaires. Data was analyzed by the SPSS(version 12.0) computer program, and it included descriptive statistics, one-way ANOVA, Pearson correlation coefficient, and Stepwise multiple regression. Results: There was a significant difference (p= .000) in fear of falling according to the level of pain, anxiety, and depression. There was a significant positive correlation among fear of falling, pain, anxiety and depression. Depression, pain, number of medication, age, and anxiety showed significant predictors (43.5%) for fear of falling. Conclusion: This study suggested that thoroughly assessing predictors making an impact on fear of falling in the initial nursing assessment is the most important for falls prevention of elderly women patients with degenerative arthritis in the community.

• 한국식품과학회지
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• 제37권5호
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• pp.763-767
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• 2005

본 연구에서는 곰팡이과 세균에서 유래된 ${\alpha}-amylase$와 유화제인 monogrlyceride(MG), sodium stearoyl-2-laclylate(SSL) 및 diacetyltartaric acid ester of monol and diglycerides(DATEM)을 첨가하여 반죽을 제조하고, 제빵 반죽의 물리적 특성인 falling number, farinogram, alvogram 및 RVA를 이용한 호화특성을 살펴보았다. ${\alpha}-amylase$의 전분분해로 인하여 falling number는 감소하였으나, MG를 혼합한 반죽의 경우 전분과 높은 결합력으로 falling number가 높게 나타났다. Farinogram 특성에서는 곰팡이와 세균에서 유래된 ${\alpha}-amylase$와 유화제가 반죽의 점탄성과 흡수율, 탄력도를 감소시키고, 흡수시간은 증가시켰다. 다만 유화세로 SSL+MG를 사용하였을 때, 대조구와 유사하거나 탄력도와 흡수시간이 더 높게 나타났다. Alveogram 특성에서는 farinogram과 유사하게 $P_{max}$ 값을 감소시켜 탄력도를 감소시켰으며, 신장성, 팽창성 및 탄력에 대한 저항성을 감소시켰다. 반죽의 호화특성에서는 호화개시온도에서는 ${\alpha}-amylase$와 유화제가 영향을 주지 않았으나, ${\alpha}-amylase$의 전분 분해로 인하여 반죽의 점도를 낮추는 경향을 보여주었다.

• 설비공학논문집
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• 제11권3호
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• pp.414-421
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• 1999

Falling film rectification involves simultaneous heat and mass transfer between vapor and liquid interface. In the present work, the adiabatic rectification process of ammonia-water vapor on the vertical plate was investigated. The continuity, momentum, energy and diffusion equations for the solution film and vapor mixture were formulated in integral forms and solved numerically. The model could predict the film thickness, the pressure gradient, and the mass transfer rate. The effects of Reynolds number and ammonia concentration of solution and vapor mixture, rectifier length, and the enhancement of mass transfer in each phases were investigated. The stripping of water in vapor mixture occurred new the entrance of ammonia solution, which imposed the proper size of an adiabatic rectifier. Rectifier efficiency increased as film Reynolds number increased and as vapor mixture Reynolds number decreased. The improvement of rectifier efficiency was significant with the enhancement of mass transfer in falling film.

• 설비공학논문집
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• 제13권4호
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• pp.225-232
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• 2001

An experimental study is carried out to investigate the characteristics of heat transfer of outside helical tubes. The main heat exchanger consists of twelve curved columns with each 300mm diameter and the total length of 1.2m copper tube having an outer diameter of 19.05mm with 1.5mm thickness. Water flows down the outside of helical tube, where flow patterns are the vertical film falling flow, immerged flow, and mixed-flow which is the combination of film falling flow and immerged flow. Refrigerant 11 flow the inside of the tube countercurrently. The experimental range of inside flow rate is 1.7~3.2$\ell$/min and outside flow rate is 21-33$\ell$/min. The results are presented as Nusselt number with corresponding Reynolds number for variety of outside and inside flow rates. The heat transfer rates of the mixed flow are 8 to 56% higher than those of film falling flow or immerged flow only. Interpretation of the results is given on the basis of physical reasoning and the correlation equations.

• Journal of Mechanical Science and Technology
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• 제17권4호
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• pp.581-589
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• 2003

Film absorption involves simultaneous heat and mass transfer in the gas-liquid system. While the non-absorbable gas does not participate directly In the absorption process. its pretence does affect the overall heat and mass transfer. An experimental study was performed to investigate the heat and mass transfer characteristics of LiBr-H$_2$O solution flow ing over 6-row horizontal tubes with the water vapor absorption in the pretence of non-absorbable gases. The volumetric concentration of non-absorbable gas, air, was varied from 0.17 to 10.0%. The combined effects of the solution flow rate and its concentration on the heat and mass transfer coefficients were also examined. The presence of 2％ volumetric concentration of air resulted in a 25% reduction in the Nusselt number and 41% reduction in the Sherwood number Optimum film Reynolds number was found to exist at which the heat and mass transfer reach their maximum value independent of air contents. Reduced Nusselt and Sherwood numbers. defined as the ratio of Nusselt and Sherwood numbers at given non-absorbable gas content to that with pure water vapor, were correlated to account for the reduction in the heat and mass transfer due to non-absorbable gases in a falling film absorption process.

• 한국식품영양과학회지
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• 제46권1호
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• pp.146-151
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• 2017

2011년에서 2013년까지 국산 원맥 443점과 수입 원맥 160점의 품질 특성을 비교하였다. 수분 함량은 국산 원맥이 10.90~13.90%, 수입 원맥은 8.0~12.6%로 나타났다. 단백질 함량은 국산 원맥이 9.34~16.1%, 수입 원맥은 9.0~14.6% 범위에 있었다. 회분 함량은 국산 원맥이 1.28~1.89%, 수입 원맥은 1.19~1.74%였으며, 원맥의 단위 밀도는 국산 원맥이 512~859 g/L, 수입 원맥이 789~853 g/L로 수입 원맥의 범위가 더 좁게 나타났다. 국산 원맥의 falling number는 147~822 s로 통상적인 고품질 밀가루의 범위인 300~600 s를 벗어난 300 s 미만의 낮은 품질의 원맥이 존재함을 보여주었다. 반면에 수입 원맥의 falling number는 모두 300 s 이상이며 최대치는 516 s로 모든 원맥이 고품질 범위에 있었다. 피해립과 이물질 함량에서는 국산 원맥이 수입 원맥보다 평균적으로 높은 수치를 보여주었으나, 국산 원맥의 피해립과 이물질 함량은 2011년에서 2013년으로 갈수록 수치가 점차 줄어드는 경향성을 보여주어 지속적인 품질 개선이 이루어지고 있음을 보여주었다.