• 한국대기환경학회지
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• 제15권3호
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• pp.281-289
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• 1999

A new E-$\varepsilon$ turbulence numerical model is proposed for analysing the turbulent air flow field within are urban street canyon. In this model the equations of eddy viscosity and energy dissipation ae reformed by considering the Kolmogorov time scale and streamline curvature effect. Application results of the new E-$\varepsilon$ model have been compared with those of standard E-$\varepsilon$ model and Yang and Shih's one, which are commonly used ones in engineering fields, and with field experiment results of DePaul and Sheih. The new model appears to be generally superior to other both models in the prediction of an air flow field within street canyon.

• 한국연소학회지
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• 제14권3호
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• pp.29-36
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• 2009

Simulation is performed to analyze the characteristics of turbulent spray combustion in a diesel engine condition. An extended Conditional Moment Closure (CMC) model is employed to resolve coupling between chemistry and turbulence. Relevant time and length scales and dimensionless numbers are estimated at the tip and the mid spray region during spray development and combustion. The liquid volume fractions are small enough to support validity of droplets assumed as point sources in two-phase flow. The mean scalar dissipation rates (SDR) are lower than the extinction limit to show flame stability throughout the combustion period. The Kolmogorov scales remain relatively constant, while the integral scales increase with decay of turbulence. The chemical time scale decreases abruptly to a small value as ignition occurs with subsequent heat release. The Da and Ka show opposite trends due to variation in the chemical time scale. More work is in progress to identify the spray combustion regimes.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2396-2400
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• 2008

The motion of small heavy particles in homogeneous isotropic turbulence in the present of gravity is investigated using Direct Numerical Simulations (DNS) at moderate Reynolds number. The Lagrangian velocity and acceleration statistics of particles and of flow for a wide range of Stokes number, defined as the ratio of the particle response time to Kolmogorov time scale of turbulence, were obtained for the direction of the gravity and normal direction, respectively. It is found that particles lose their correction faster than the case without gravity. Then, a significant increase in the average settling velocity was observed for a certain range of Stokes number. Our focus is placed on gravitational effect on very small particles. Our simulations show that as the Stokes number reduces to zero, their mean settling velocity approaches the terminal velocity in still fluid.

• Journal of Biosystems Engineering
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• 제11권1호
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• pp.76-85
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• 1986

This study was intended to examine the failure characteristics and breakdowns of the head-fed type combines generally used on farms. The failure distribution was assumed to follow Weibull distribution function and the Weibull parameters of the major parts, units and combine as whole were estimated by using the data collected in a survey. A computer program for the estimation of the Weibull parameter was developed. Monte Carlo method was used in predicting the time between failures. The results of study may be summarized as follows: 1. The number of failures per combine was 4.83 times per year and 0.3 times per hectare of combines of different ages. 2. According to the Kolmogorov-Smirnov test method, it was proved that the Weibull distribution function is well fitted to the characteristics of the failure and breakdowns of combines. 3. Weibull parameters of failure distribution of the combine as a whole were estimated to give the shape parameter ${\beta}$=1.3089 and the scale parameter ${\alpha}$=105.2409. The combining area with 80% reliability was 1.1 ha, and the probability of operating the combine without any failure for a year, was $2.76{\times}10^{-4}$. 4. The mean time between failures (MTBF) of the combines was predicted to be 3.2 ha of operation, which corresponds to 32 hours of operation.

• 성인간호학회지
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• 제25권4호
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• pp.473-482
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• 2013

Purpose: The purpose of this study was to investigate the effects of a structured preoperative instruction upon anxiety and postoperative self-care compliance. Methods: A randomized control group pre-post design was used. Sixty subjects undergoing cataract surgery were randomly assigned to one of two groups. The instruction consisted of cataract surgery procedure, sensory information, deep breathing, use of eye drop, and post op self-care regimen and was provided to the experimental group with control group receiving an usual treatment. State anxiety NRS, pulse, BP, and self-care compliance scale developed by Cho & Rho were used. Data were collected at two time periods: on the day of surgery in the clinic and prior to anesthesia in the operating room. The postoperative self-care compliance scores were measured at their second visits to the hospital after surgery. Data were analyzed using Kolmogorov Smirnov test, t-test, and Mann-Whitney U test. Results: There were significant differences between the two groups in the postoperative state anxiety (t=-3.57, p=.001) and the postoperative self-care compliance score (t=3.92, p<.001). There were no significant difference between the two groups in the postoperative blood pressure and pulse rate. Conclusion: The results of this study suggest that the structured preoperative instruction could be a nursing intervention for cataract surgery patients.

• 한국수자원학회논문집
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• 제55권11호
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• pp.955-967
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• 2022

기존의 입자추적모델에서 입자의 연직방향 변위 예측은 정지 수체에서의 최종침강속도를 바탕으로 계산되었다. 그러나 난류 수체에서의 침강속도에 관한 선행 연구들은 난류가 입자의 침강속도에 영향을 미치는 것으로 보고하고 있다. 본 연구에서는 난류에 따른 침강속도의 변화 특성을 규명하고자 개수로 흐름에서 입자의 침강 실험을 수행하였다. 입자의 침강속도와 난류 특성은 각각 PTV, PIV 기법을 통해 측정하였고, 측정된 침강속도 증가율과 입자 및 난류 특성에 따른 난류 수체에서의 침강속도의 변화 특성을 분석하였다. 그 결과, 입자 직경이 Kolmogorov 길이 스케일의 1~2배가 될 때, 침강속도 증가율이 커지기 시작하였다. 본 실험 결과를 선행 연구들과 비교하였을 때, Stokes 수와 침강속도 증가율의 그래프가 입자의 밀도에 따라 각각 최댓값을 보이는 곡선 형태를 가지는 것으로 나타났다. 결론적으로, 입자의 침강속도는 개수로 흐름에서 정지 수체에서보다 빠르기 때문에, 기존의 정지 수체에서의 침강속도를 이용한 입자추적모델은 연직방향으로 바닥에 도달하는 시간을 과대산정하게 될 수 있다. 이러한 측면에서 본 연구의 결과는 입자추적모델의 성능 개선에 도움을 줄 것으로 기대된다.

• 기본간호학회지
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• 제13권3호
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• pp.401-408
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• 2006

Purpose: The purpose of this study was to determine the effects of a lower extremity exercise program on muscle strength and flexibility in women with knee osteoarthritis. Method: This study was conducted using a non-equivalent control group pretest-posttest design. The participants were 35 women with knee osteoarthritis. The experimental group performed the lower extremity exercise program, which was an adapted BeHaS exercise program developed by Kim(2006). It consisted of approximately 65-130 minutes per one session, two days a week, for twelve weeks. Lower extremity muscle strength was measured by the Seated Leg Press Machine (TY-H2217, made in Korea), back muscle strength by back muscle strength scale (TKK 5402, made in Japan) and flexibility, by Sit and Reach tester (01285, U.S.A). Data were gathered from September 2005 to March 2006. Frequency, $X^2$ test and t-test were used to analyze the data. SPSS Win 11.0 was used to assist analysis. For normal distribution of data, Kolmogorov-Smirnov test was done. Results: There were statistical differences in the mean strength of both legs together, strength in leg with more pain(p=.044; p=.046), sit and standing time (p=.007), and back strength (p=.021). Conclusion: Based on these results, it can be concluded that a lower extremity exercise program can help improve lower extremity muscle strength in women with osteoarthritis.

• 국제물리치료학회지
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• 제10권2호
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• pp.1750-1755
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• 2019

Background: Most of the previous researches on the abnormality of breathing pattern have focused on the silence of functional movements owing to such abnormality, however, have not been clearly identified the relationship between the abnormal breathing pattern on one hand and kinesiophobia and flexion relaxation phenomenon (FRP) on the other hand. Objective: To compare patients with chronic low back pain (CLBP) and healthy person in the abnormality of breathing pattern, kinesiophobia, and FRP during flexion and extension of the trunk. Design: Case-control study. Methods: The research subjects consisted of a group of 15 healthy adults and another group of 15 patients with CLBP. Capnography was used to measure the endtidal $CO_2$ ($EtCO_2$) and respiratory quotient (RQ). The muscle activity of multifidus and erector spinae of the subjects was measured during flexion and extension of the trunk to identify their FRP. The Nijmegen Questionnaire (NQ) and Tampa Scale of Kinesiophobia (TSK) were utilized to measure their breathing patterns and kinesiophobia, respectively. The Kolmogorov-Smirnov (K-S) test was conducted in order to analyze the normal distribution of the measured data. Their general characteristics were identified by the descriptive statistics and the independent t-test was performed to identify the differences between the two groups in terms of abnormality of breathing pattern, kinesiophobia, and FRP. The level of significance was set at ${\alpha}=.05$. Results: The patients with CLBP had significantly less $EtCO_2$ and shorter breathing hold time (BHT) than normal healthy person (p<.05). The patient with CLBP also had significantly greater kinesiophobia than healthy person (p<.05), and had less FRP than the healthy person (p<.01). Conclusions: These results suggest that the CLBP had greater abnormality of breathing pattern and kinesiophobia with less FRP than healthy person.

• Computers and Concrete
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• 제32권3호
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• pp.247-261
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• 2023

Due to the non-uniform distribution of meso-structure, the diffusion of chloride ions in concrete show the characteristics of characteristics of randomness and fuzziness, which leads to the non-uniform distribution of chloride ions and the non-uniform corrosion of steel rebar in concrete. This phenomenon is supposed as the main reason causing the uncertainty of the bearing capacity deterioration of reinforced concrete structures. In order to analyze and predict the durability of reinforced concrete structures under chloride environment, the random features of chloride ions transport in concrete were studied in this research from in situ meso-structure of concrete. Based on X-ray CT technology, the spatial distribution of coarse aggregates and pores were recognized and extracted from a cylinder concrete specimen. In considering the influence of ITZ, the in situ mesostructure of concrete specimen was reconstructed to conduct a numerical simulation on the diffusion of chloride ions in concrete, which was verified through electronic microprobe technology. Then a stochastic study was performed to investigate the distribution of chloride ions concentration in space and time. The research indicates that the influence of coarse aggregate on chloride ions diffusion is the synthetic action of tortuosity and ITZ effect. The spatial distribution of coarse aggregates and pores is the main reason leading to the non-uniform distribution of chloride ions both in spatial and time scale. The chloride ions concentration under a certain time and the time under a certain concentration both satisfy the Lognormal distribution, which are accepted by Kolmogorov-Smirnov test and Chi-square test. This research provides an efficient method for obtain mass stochastic data from limited but representative samples, which lays a solid foundation for the investigation on the service properties of reinforced concrete structures.

• Journal of Trauma and Injury
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• 제25권2호
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• pp.49-56
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• 2012

Purpose: For determining the prognosis of critically injured patients, transporting patients to medical facilities capable of providing proper assessment and management, running rapid assessment and making rapid decisions, and providing aggressive resuscitation is vital. Considering the high mortality and morbidity rates in critically injured patients, various studies have been conducted in efforts to reduce those rates. However, studies related to diagnostic factors for predicting severity in critically injured patients are still lacking. Furthermore, patients showing stable vital signs and alert mental status, who are injured via a severe trauma mechanism, may be at a risk of not receiving rapid assessment and management. Thus, this study investigates diagnostic factors, including physical examination and laboratory results, that may help predict severity in trauma patients injured via a severe trauma mechanism, but showing stable vital signs. Methods: From March 2010 to December 2011, all trauma patients who fit into a diagnostic category that activated a major trauma team in CHA Bundang Medical Center were analyzed retrospectively. The retrospective analysis was based on prospective medical records completed at the time of arrival in the emergency department and on sequential laboratory test results. PASW statistics 18(SPSS Inc., Chicago, IL, USA) was used for the statistical analysis. Patients with relatively stable vital signs and alert mental status were selected based on a revised trauma score of more than 7 points. The final diagnosis of major trauma was made based on an injury severity score of greater than 16 points. Diagnostic variables include systolic blood pressure and respiratory rate, glasgow coma scale, initial result from focused abdominal sonography for trauma, and laboratory results from blood tests and urine analyses. To confirm the true significance of the measured values, we applied the Kolmogorov-Smirnov one sample test and the Shapiro-Wilk test. When significance was confirmed, the Student's t-test was used for comparison; when significance was not confirmed, the Mann-Whitney u-test was used. The results of focused abdominal sonography for trauma (FAST) and factors of urine analysis were analyzed using the Chi-square test or Fisher's exact test. Variables with statistical significance were selected as prognostics factors, and they were analyzed using a multivariate logistics regression model. Results: A total of 269 patients activated the major trauma team. Excluding 91 patients who scored a revised trauma score of less than 7 points, 178 patients were subdivided by injury severity score to determine the final major trauma patients. Twenty-one(21) patients from 106 major trauma patients and 9 patients from 72 minor trauma patients were also excluded due to missing medical records or untested blood and urine analysis. The investigated variables with p-values less than 0.05 include the glasgow coma scale, respiratory rate, white blood cell count (WBC), serum AST and ALT, serum creatinine, blood in spot urine, and protein in spot urine. These variables could, thus, be prognostic factors in major trauma patients. A multivariate logistics regression analysis on those 8 variables showed the respiratory rate (p=0.034), WBC (p=0.005) and blood in spot urine (p=0.041) to be independent prognostic factors for predicting the clinical course of major trauma patients. Conclusion: In trauma patients injured via a severe trauma mechanism, but showing stable vital signs and alert mental status, the respiratory rate, WBC count and blood in the urine can be used as predictable factors for severity. Using those laboratory results, rapid assessment of major trauma patients may shorten the time to diagnosis and the time for management.