• 대한수의학회지
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• 제40권4호
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• pp.755-762
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• 2000

The aim of this investigation was to examine the effects of osteocalcin, bone-specific alkaline phophatase, estrogen, insulin-like growth factor-I (IGF-I), Ca, P and bone mineral density on osteoporosis induced by ovariectomy in rats. Female Sprague-Dawley 30 rats of three-forth's birth, weighing $215{\pm}10g$, were divided into two groups including the sham operation group(5 heads) and ovariectomy group(25 heads). They were fed normal diets for 2 weeks before the experimental operation and for 8 more weeks after operation. The level of osteocalcin, TALP, BALP, estrogen, bone mineral density and IGF-I were increased in experimental group, but a little increased in sham operation group at same period. The change of rates of osteocalcin, TALP, BALP, estrogen, bone mineral density and IGF-I were significantly higher in experimental group than sham operation group. $Ca^{2+}$ was not changed between two groups and P was significantly decreased in experimental group and Ca/P ratio was higher in experimental group than sham operation group. Body weights were increased in all two groups and growth rate per day was higher in experimental group than sham operation group. However, femur weight I body weight ratio was lower in experimental group than sham operation group.

• Nutrition Research and Practice
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• 제7권4호
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• pp.309-314
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• 2013

This study was conducted to investigate the relationship among the current status of calcium intake from milk and milk products, physical growth and bone mineral density in 664 male and female middle school and high school students aged 15-17 years. In the study, the current status of calcium intake from milk and milk products was analyzed, and the height, body composition, and bone mineral density of the right heel bone (calcaneus) were measured. The daily calcium intake of milk and milk products was calculated as the 'dairy equivalent of calcium', which is the calcium content in 200 mL of white milk. The cutoffs of tertiles of the dairy equivalent of calcium were calculated and then the subjects were categorized into 3 groups according to the tertiles, Q1 group (lower intake group), Q2 group (middle intake group) and Q3 group (upper intake group). The daily calcium intake of milk and milk products in Q1, Q2 and Q3 groups was 16.2 mg, 99.7 mg, and 284.0 mg, respectively, and the ratio of milk and milk product consumption to the daily total calcium intake was 5.4%, 27.4%, and 49.7%, respectively. The ratio of total calcium intake to the daily recommended intake in study subjects was 30.5% in Q1, 42.3% in Q2, and 60.7% in Q3, with significant differences (P < 0.05). Height, body weight, BMI, and % of body fat in three tertile groups (Q1, Q2 and Q3) were not significantly different. However, the T scores for bone mineral density in female students in three tertile groups (Q1, Q2 and Q3) was significantly different (P < 0.05). The study showed that the intake of milk and milk products in adolescents, particularly in girls, can improve the bone mineral density without increasing body weight, and thus confirmed that milk intake is important in adolescence.

• 공업화학
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• 제34권3호
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• pp.272-278
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• 2023

이 연구에서는 전류밀도와 전기삼투 현상이 전기투석(electrodialysis, ED)의 탈염성능에 미치는 영향을 분석하였다. 농축액의 농도를 10~200 g/L로 변화시키면서 정전압 조건에서 ED 실험을 진행하였다. ED 운전과정에서 스택에 공급되는 전류밀도와 전하량, 희석액과 농축액의 농도, 그리고 전기삼투에 의한 물 이동량을 측정하여 탈염성능을 분석하였다. 농축액의 농도가 증가함에 따라 이온교환막의 선택성이 감소하여 전류효율이 감소하였다. 또한 전류효율은 스택에 공급되는 전류밀도에 영향을 받는 것으로 나타났다. 전류밀도가 15 mA/cm² 이상에서는 역 확산이 억제되어 전류효율이 증가하였다. ED 운전과정에서 전기삼투에 의한 물 이동량을 분석하였다. 물 이동량은 농축액과 희석액의 농도비에 비례하여 증가하는 것을 알 수 있었다. 농도비가 100 이상에서는 삼투압에 의한 물 이동량이 급격히 증가하여 200 g/L 이상의 농축액을 얻는데 한계가 있는 것으로 나타났다.

• 대한기계학회논문집
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• 제14권1호
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• pp.214-224
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• 1990

본 연구에서는 현 저자의 이전의 연구를 확장하여 균일한 열유속을 갖는 2상 기체-고체입자 위 방정식에서 축 방향의 열전달은 반경 방향의 열전달보다 작아 무시 하였으며, 복사 열전달은 기체와 입자 사이의 온도 차이가 적어 무시하였다. 방정식 중 $F_{px}$ 와 $F_{pr}$ 은 2상 사이의 상호작용에 의한 단위부피당 축방향과 반경방향 의 저항력이며, 수직관의 열전달 특성을 부하도와 상대 입자 크기 $d_{p}$/D를 변화시 켜 가면서 조사하는 것이다.다.

• 한국보건간호학회지
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• 제31권2호
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• pp.376-388
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• 2017

Purpose: The triglyceride-to-high-density lipoprotein-cholesterol (TG/HDL-C) ratio is one of the main predictive indices for cardiovascular disease. This study was examined the relationship between TG/HDL-C ratio and metabolic syndrome (MetS) in male office workers. Methods: Secondary analysis was conducted to determine the risk between the TG/HDL-C ratio and MetS in male office workers. A total of 765 people underwent the 'regular workplace health checkups in 2014'. Among the subjects who were male and responded to the questionnaire and health lifestyle survey, 470 (61.4%) excluding those with missing and/or abnormal values were analyzed. The association between MetS, MetS components, and the TG/HDL-C ratio was examined by a Chi-square test, One-way ANOVA, Turkey post-hoc test and Logistic regression analysis. Results: The number of males with MetS was 70 (14.9%) and the number of MetS components increased with increasing TG/HDL-C ratio (p<.001). Logistic regression analysis with an adjustment for potential confounders revealed a 31.8 times higher odds ratio of the Quartile4 group for MetS than that of the Quartile1 group (p<.001). Conclusion: These results show that the likelihood of MetS, particularly the risk of MetS in the Quartile4, increases with increasing TG/HDL-C ratio.

• Journal of Forest and Environmental Science
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• 제31권2호
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• pp.119-125
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• 2015

This study examined the effects of rice straw steaming time and mixing ratio between rice straw and wood particle on the properties of mixed particle board from Acacia mangium Willd wood and rice straw. Rice straw and Acacia mangium Willd wood were collected in Hanoi, Vietnam. The particle board was three-layer particle board with the structural ratio of 1:3:1. The thickness, density and board size of the particle board were 18 mm, $0.7g/cm^3$, and $800{\times}800{\times}18$ (mm, including trimming), respectively. A resin mixture between commercial Urea-formaldehyde (U-F) adhesive and methylene diphenyl isocyanate (MDI) adhesive was used with a dosage of 12% for the core layer and 14% for the surface layer. In this experimental design, the steaming time for rice straw was 15, 30, 45, 60, and 75 minutes at $100^{\circ}C$. The rice straw-wood mixing ratio was 10, 20, 30, 40, and 50%. The results showed that both mixing ratio and steaming time affect the properties of the particleboard, but the mixing ratio has a stronger impact. A higher mixing ratio and a longer steaming time resulted in a better quality of particleboard. The optimal steaming time for rice straw was 46.12 minutes with the straw-wood mixing ratio of 29.85% with the following characteristics of the particle board: the modulus of rupture (MOR) of 14.64 MPa, internal bond strength (IB) of 0.382 MPa, thickness swelling (TS) of 8.83%, and board density of $0.7-0.7g/cm^3$.

• 대한의용생체공학회:의공학회지
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• 제22권5호
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• pp.431-438
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• 2001

동맥혈액의 총 혈색소 농도와 산화 혈색소 농도의 비율로 정의되는 산소포화도를 비관혈적으로 측정하는 펄스 옥시메터는 주위환경 요인과 피측정자의 호흡 및 움직임에 의한 영향을 받는다. 특히 환자가 움직였을 때 동잡음 신호는 주파수영역에서 정상적인 수신광 신호와 중첩 또는 인접하게 나타나 잡음제거가 어렵다 이러한 문제점을 개선하기 위해 본 논문에서는 필터뱅크와 정합필터를 이용하여 동잡음을 제거하기 위한 방법을 제안한다. 그리고 제안된 방법으로 실험한 결과. ratio의 평균 변화율이 이동평균필터(11.2%)와 적응필터(39.7%)를 이용하였을 때 보다 변화 폭이 4.1%로 나타나 환자의 움직임에서도 보다 안정적인 산소포화도를 측정이 가능할 것으로 사료된다.

• 한국안전학회지
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• 제14권2호
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• pp.83-89
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• 1999

The electrical properties due to mixture ratio of linear low density polyethylene(LLDPE) and ethylene vinyl acetate(EVA) films are studied. An experimental specimen is selected as LLDPE/EVA of thickness 200${\mu}{\textrm}{m}$ produced by mixture ratio of 50 : 50, 60 : 40, 70 : 30 and 80 : 2 wt%. In temperature range from $25^{\circ}C$ to 12$0^{\circ}C$, the measurement of volume resistivity using a highmegohm meter is performed within 10 minutes since each voltage of DC 100 V, 250 V, 500 V and 1000 V is applied, according to the step voltage method. From FT-IR spectrum for an analysis of physical properties, it can be confirmed that LLDPE blended with EVA shows an absence of carbonyl groups(1735 $cm^{-1}$, C=0) and ether groups(1242 $cm^{-1}$, C-O). The peak of LLDPE and EVA made of mixture ratio of 70 : 30 at 2$\theta$ =21.4$^{\circ}$ in the results of XRD is higher than the others. In the experiment for volume resistivity characteristics in order to investigate the electrical properties of specimen, it is confirmed that volume resistivity is decreased with the increase of the molecular motion and temperature.

• 한국농공학회논문집
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• 제62권2호
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• pp.1-15
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• 2020

In this study, the characteristics of crop damage area by flooding for 113 middle range watersheds during 2000-2016 were analyzed and future crop damage area by flooding were analyzed using 13 GCM outputs such as hourly maximum rainfall, 10-min maximum rainfall, number of days of 80 mm/day, daily rainfall maximum, annual rainfall amount associated with RCP 4.5 and RCP 8.5 scenarios and watershed characteristic data such as DEM, urbanization ratio, population density, asset density, road improvement ratio, river improvement ratio, drainage system improvement ratio, pumping capacity, detention basin capacity, and crop damage area by flooding. A constrained multiple linear regression model was used to construct the relationships between the crop damage area by flooding and other variables. Future flood index related to crop damage may mainly increase in the Mankyung watershed, Southwest part of Youngsan and Sumjin river basin and Southern part of Nackdong river basin. Results are useful to identify watersheds which need to establish strategies for responding to future flood damage.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.1108-1117
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• 2005

RAP(rammed aggregate pier) method which is intermediate foundation of deep and shallow foundation is used to improve the ground with high compaction energy. This method is widely spread around the world, but there are few examples and systemic researches for failure mechanism and bearing capacity of this method are not organized yet. In this paper, soil laboratory tests were carried out to evaluate the applicability of RAP method as the foundation of a structure. And the bearing capacity and the failure mechanism of RAP method were studied with respect to various relative densities(35%, 65%, 90%), diameters(45mm, 60mm) and lengths(20cm, 30cm, 40cm). As results, stress concentration ratio decreased as diameter of RAP was increasing or length of RAP was decreased or relative density was decreased. however these results were not always constant. because systematic interaction between relative density and diameter and length of RAP can affect stress concentration ratio, more studies on stress concentration ratio are needed throughout laboratory and field tests.