• 한국지반환경공학회 논문집
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• 제15권4호
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• pp.13-27
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• 2014

Catchments soil erosion, one of the most serious problems in the mountainous environment of the world, consists of a complex phenomenon involving the detachment of individual soil particles from the soil mass and their transport, storage and overland flow of rainfall, and infiltration. Sediment size distribution during erosion processes appear to depend on many factors such as rainfall characteristics, vegetation cover, hydraulic flow, soil properties and slope. This study involved laboratory flume experiments carried out under simulated rainfall in a 3.0 m long ${\times}$ 0.8 m wide ${\times}$ 0.7 m deep flume, set at $17^{\circ}$ slope. Five experimental cases, consisting of twelve experiments using three different sediments with two different rainfall conditions, are reported. The experiments consisted of detailed observations of particle size distribution of the out-flow sediment. Sediment water mixture out-flow hydrograph and sediment mass out-flow rate over time, moisture profiles at different points within the soil domain, and seepage outflow were also reported. Moisture profiles, seepage outflow, and movement of overland flow were clearly found to be controlled by water retention function and hydraulic function of the soil. The difference of grain size distribution of original soil bed and the out-flow sediment was found to be insignificant in the cases of uniform sediment used experiments. However, in the cases of non-uniform sediment used experiments the outflow sediment was found to be coarser than the original soil domain. The results indicated that the sediment transport mechanism is the combination of particle segregation, suspension/saltation and rolling along the travel distance.

• 대한기계학회논문집A
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• 제41권10호
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• pp.905-913
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• 2017

본 연구에서는 형상 정보가 주어지지 않은 부품과 형상 정보가 주어진 부품으로 구성된 봉의 고유 주파수를 최대화하는 치수 최적화 방법을 제시한다. 두 부품으로 구성된 봉의 진동 특성을, 각 부품의 형상 대신, 두 부품의 주파수 응답 함수들로부터 예측한다. 이를 위해, 실험 모달 해석 방법을 이용하여 각 부품의 등가 진동계를 구하고, 두 등가 진동계의 질량 행렬과 강성 행렬들로부터, 두 부품이 결합된 봉의 등가 질량 행렬과 강성 행렬을 도출한다. 몇 가지 수치 예제에서, 제시한 방법으로 얻어진 봉의 등가 진동계의 주파수 응답 함수를 실제 봉의 주파수 응답 함수와 비교하여, 등가 진동계를 이용한 고유 주파수 예측 방법의 유효성을 검증한다. 검증된 방법으로 얻어진 등가 진동계를 이용하여, 봉의 1차 고유 주파수를 최대화하기 위한 치수 최적화 문제를 정식화하고, 최적화 알고리즘을 사용하여 봉의 구조를 최적화한다.

• 한국수자원학회논문집
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• 제41권3호
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• pp.265-276
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• 2008

수공구조물의 설계를 위해서는 충분한 기간의 관측자료가 필요하지만, 우리나라의 수문자료는 대부분 충분한 수의 관측자료를 보유하고 있지 못하는 실정이다. 따라서 본 연구에서는 핵밀도함수를 이용한 비동질성 Markov 모형을 통해 시간강수량 자료를 모의하였다. 첫 번째로 시간강수량 자료에 변동핵밀도함수를 이용하여 천이확률을 산정하였으며, 두 번째로 난수와 천이확률을 통해 강수가 발생하는 시간을 결정하였다. 세 번째로 강수가 발생한 시간의 강수량의 크기를 핵밀도함수를 통해 추정하였다. 분석결과에서 모의된 시간강수량은 관측시간강수량과 비슷한 통계적 특성을 보이고 있는 것으로 나타났다. 또한, 시간강수량의 모의발생을 위하여 산정한 천이확률을 이용해 강수의 무차원시간분포곡선을 유도하였다.

• 대한원격탐사학회지
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• 제20권6호
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• pp.419-425
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• 2004

본 연구에서는 Dempster-Shafer evidence theory에 기반하여 Gaussian 질량 함수를 사용하는 융합 기법을 제안하고 있다. Dempster-Shafer 융합은 비정확성과 불확실성 measures를 각각 belief 함수와 plausibility 함수로 나타내며 이 두 함수 값 사이의 간격을 나타내는 "belief interval"에 의해 불확실성의 정도가 표현된다. 이러한 Dempster-Shafer 융합기술을 이용하여 서로 다른 센서에서 수집된 영상 자료를 융합하여 사용하여 분류 결과의 정확성을 높이고 특히 분류를 위한 매개변수를 추정하는 훈련과정에서 복합 클래스를 설정할 수 있어 단순 클래스 설정으로 인한 훈련과정이 어려움을 피할 수 있다. 이 연구에서는 경기도 용인/능평 지역에서 관측 된 KOMPSAT EOC의 범색 영상 자료와 LANDSAT ETM+의 식생지수 자료에 대해 제안된 Dempster-Shafer 융합기술을 이용하여 분류 실험을 수행하였고 분류 결과는 서로 다른 센서간의 영상자료 융합을 위한 제안된 기법의 잠재적 효과성을 보여주고 있다.

• The Journal of Korean Physical Therapy
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• 제35권4호
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• pp.111-116
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• 2023

Purpose: Pneumoconiosis is a chronic lung disease in which the lungs become hardened due to the accumulation of fine mineral dust that has been breathed in at industrial sites. The lungs are unable to function properly, resulting in complications of several respiratory diseases. Methods: The subjects were 36 elderly adults (pneumoconiosis patients 18, healthy elderly 18) over the age of 65 years. The respiratory function was assessed using a spirometer to measure forced vital capacity (FVC), first second of forced expiration (FEV1), FEV1/FVC, and peak expiratory flow n(PEF). The static balance function test was determined by the center of mass (COM), ankle angle range, hip angle range, sway parameters, and reciprocal compensatory index (RCI). Cognitive function was measured by applying MoCA-k. Results: Comparison of respiration functions between the two groups showed statistically significant differences in FVC, FEV1, FEV1/FVC, and PEFs (p<0.05). Cognitive abilities showed statistically significant differences due to higher cognitive skills in the control group as compared to the patient group (p<0.05). Most results of the static balance capability measurements showed statistically significant differences between the groups (p<0.05). However, no statistically significant differences were obtained for COM AP Range, Angle AP Range, RCI ML Range, and AP Range (p>0.05). Conclusion: The results of the current study indicate that patients suffering from pneumoconiosis have less cognitive ability and balance function as compared to healthy elderly people. Therefore, we expect an improvement in the balance ability and cognitive function through systematic management and strengthening lung function training to improve the quality of life of pneumoconiosis patients.

• Clinical and Experimental Pediatrics
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• 제57권5호
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• pp.232-239
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• 2014

Purpose: Mitochondrial disease (MD) and Duchenne muscular dystrophy (DMD) are often associated with cardiomyopathy, but the myocardial variability has not been isolated to a specific characteristic. We evaluated the left ventricular (LV) mass by echocardiography to identify the general distribution and functional changes of the myocardium in patients with MD or DMD. Methods: We retrospectively evaluated the echocardiographic data of 90 children with MD and 42 with DMD. Using two-dimensional echocardiography, including time-motion (M) mode and Doppler measurements, we estimated the LV mass, ratio of early to late mitral filling velocities (E/A), ratio of early mitral filling velocity to early diastolic mitral annular velocity (E/Ea), stroke volume, and cardiac output. A "z score" was generated using the lambda-mu-sigma method to standardize the LV mass with respect to body size. Results: The LV mass-for-height z scores were significantly below normal in children with MD ($-1.02{\pm}1.52$, P<0.001) or DMD ($-0.82{\pm}1.61$, P =0.002), as were the LV mass-for-lean body-mass z scores. The body mass index (BMI)-for-age z scores were far below normal and were directly proportional to the LV mass-for-height z scores in both patients with MD (R =0.377, P<0.001) and those with DMD (R =0.330, P=0.033). The LV mass-for-height z score correlated positively with the stroke volume index (R =0.462, P<0.001) and cardiac index (R =0.358, P<0.001). Conclusion: LV myocardial atrophy is present in patients with MD and those with DMD and may be closely associated with low BMI. The insufficient LV mass for body size might indicate deterioration of systolic function in these patients.

• Tuberculosis and Respiratory Diseases
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• 제72권2호
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• pp.163-168
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• 2012

Background: Cigarette smoke induced release of iron could alter iron metabolism in the lungs of chronic smokers and contribute to the increase in the total oxidative burden on the lungs of smokers. In previous studies, ferritin levels of bronchoalveolar lavage fluid in smokers were elevated. The aim of the present study was to investigate the relationship between serum ferritin concentration, smoking and lung function in Korean people. Methods: This study was based on the data acquired in the second year (2008) of the Forth National Health and Nutrition Examination Survey that was conducted from 2007 to 2009. The analysis included 2,244 subjects who were older than 20 years and had complete data from both lung function test and serum ferritin concentration. Among participants, 1,076 were male and 1,168 were female. Results: Mean serum ferritin concentrations in males were $120.3{\pm}80.1{\mu}g/L$ and $47.9{\pm}39.8{\mu}g/L$ in females. There were no differences in serum ferritin concentrations between non-smokers and smokers after adjusting for age, body mass index, and amounts of alcohol. Serum ferritin concentrations were associated with smoking amounts by simple linear regression but not associated with smoking amounts after adjustment with age, body mass index, and amounts of alcohol in both males and females. Lung function was not associated with serum ferritin concentrations. Conclusion: Our data suggested that serum ferritin concentrations are not related with smoking and lung function.

• 한방재활의학과학회지
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• 제24권4호
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• pp.61-70
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• 2014

Objectives The purpose of this study was to investigate the characteristics in obesity classification group of college students having health checkup by analyzing their BMI and blood test and determine the association between factors contributing to obesity and obesity according to BMI. Methods A group of 2992 test subjects took their medical examination and their body composition, height, weight, blood pressure were measured and blood test was done. With these results we diagnosed obesity, and analysed relationship between obesity and cholesterol, triglyceride, LDL (low density lipoprotein)-cholesterol, HDL (high density lipoprotein)-cholesterol, liver function, renal function and blood pressure. Results 1. Overweight individuals showed high total cholesterol, LDL-cholesterol, triglyceride, GOT (glutamic oxalacetic transaminase), GPT (glutamic pyruvate transaminase), Urea-nitrogen, Creatinine and low HDL-cholesterol. 2. BMI showed a significant association with other factors. BMI has a negative correlation with sex and HDL-cholesterol. BMI had positive correlations with other factors. 3. There was no relation between BMI and sex. Those six factors, liver function, cholesterol, blood pressure, kidney function, neutral fat, and blood sugar were related to BMI. Conclusions There was a significant relation between college students' BMI and their liver function, cholesterol, blood pressure, kidney function, neutral fat, and blood sugar. The diseases related to liver function, cholesterol, blood pressure, kidney function, neutral fat, and blood sugar were clearly associated with obesity.

• 한국지진공학회논문집
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• 제3권1호
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• pp.103-112
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• 1999

본 연구는 두 지점간의 진동수 응답함수를 이용하여 시간 및 진동수 영역에서의 원심펌프(20Hp. 50Hp) 가진력을 추정하기 위한 것이다. 진동수 응답함수는 실수부와 허수부에 대한 신호정보를 가지고 있으며 응답함수 역시 실수부와 허수부에 대한 신호정보를 가지고 있다 따라서 이들 진동수 응답함수 및 응답함숴의 복소수 계산으로부터 가진력을 실험적으로 구하였으며 이론적인 방법에 의하여 구한 가진력과 실험적으로 구한 값을 비교함으로서 펌프에 의한 주진동수 성분의 크기는 펌프 및 모터중량의 10-25% 정도가 됨을 제시하였다. 가진력 산정을 위한 시간영역에서의 불평형질량의 크기는 펌프 및 모터중량의 약 30-60%임을 알수 있었다 한편 펌프회전에 의한 진동은 주진동수 이외에도 주진동수의 2-3배의 크기를 갖는 성분이 있음을 알 수 있었으며 대상 콘크리트 슬래브의 고유진동수와의 가진진도수비를 달리함에 따라 정확한 진동전달률을 조절하는데 활용할 수 있다.

• 대한의생명과학회지
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• 제17권2호
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• pp.141-149
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• 2011

The purpose of this study was to find out any difference and correlation between the cardiac structure and its function according to the level of obesity as evaluated by waist measurement and BMI (body mass index) in healthy adults. For research subjects, the study selected a final 519 subjects excluding 198 subjects aged 55 or over out of 717 subjects who received echocardiography through a medical checkup at J General Hospital. For the criteria for obesity, men were defined as being obese in case their waist measurement was over 90 cm, whereas women were defined as being obese in case their waist measurement was over 80 cm. Also, regarding the BMI criteria, in case a person's BMI was 30 kg/$m^2$, the subject was classified as belonging to an obese group, and in case a person's BMI was between 25 kg/$m^2$ and 30 kg/$m^2$, the subject was classified as belonging to an overweight group. Concerning the evaluation of cardiac structure and function, they were evaluated using two-dimensional, M-mode, doppler echocardiography. According to the stage of obesity in accordance with waist measurement and BMI, the cardiac structure showed both eccentric and centripetal changes, and the cardiac function was also discovered to show differences according to the stage of obesity. In addition, also in the overweight group, which is a prior stage to obesity, out of the criteria for obesity classification according to BMI, there were differences in the cardiac structure and function. Also, both the waist measurement and BMI were found to have a correlation with cardiac structure and diastolic function. Consequently, cardiac structure and function are correlated with BMI and waist measurement, which are anthropometrical variables, and obesity is assumed to induce not only structural change but also functional change of the heart.