• Journal of the Korea Institute of Building Construction
• /
• v.19 no.6
• /
• pp.495-501
• /
• 2019

Recently, research has been carried out into the use of carbon fiber reinforced polymer (CFRP), which has good tensile strength and corrosion resistance, as an alternative to rebar. But as of yet, the research into fatigue failure of CFRP is insufficient. In this paper, an analysis was performed of the mechanical behavior and failure patterns of CFRP reinforced concrete beams according to static and cyclic loads, in order to evaluate the safety and validity of CFRP rebar as an alternative material for rebar. The cyclic load ranged from 10 % to 70% of the ultimate load, and was loaded at a speed of 3Hz using a sine wave in the form of a three-point loading method. Through the static load test, the maximum load or stiffness of the beam was found to increase remarkably with the increase of the reinforcement, but the fatigue test showed that the number of repetitions decreased and the amount of deflection increased with the increase of the reinforcement.

• Korean Journal of Community Nutrition
• /
• v.15 no.1
• /
• pp.27-35
• /
• 2010

This study was done to investigate the association of blood clinical parameters and dietary intakes with serum adiponectin level. Athropometric measurement, dietary intakes, serum lipids and adiponectin levels were examined in 160 overweight and obese women. The subjects were divided into 5 groups by quintile according to serum adiponectin level. Weight, BMI, waist circumferences and waist/hip ratio of the highest quintile group were significantly lower than those of the lowest quintile group. Serum lipid analysis showed a significant higher level of TG, LDL-cholesterol, LDL/HDL ratio, AI, and serum hs-CRP in the lowest quintile group. Similarly, correlation data also showed that serum adiponectin level was positively correlated with serum HDL-cholesterol level (p < 0.01) and was negatively correlated with BMI (p < 0.01), waist circumferences (p < 0.01), waist/hip ratio (p<0.01), systolic (p < 0.01) and diastolic blood pressure (p < 0.05), TG (p < 0.01), LDL-cholesterol (p < 0.05), LDL/HDL ratio (p < 0.05), AI (p < 0.01), Homa-IR (p < 0.01), hs-CRP (p < 0.05) and leptin (p < 0.05). Dietary intake data showed that protein intake was significantly lower in the highest quintile group compared to the lower quintile groups while intakes of vitamin C was significantly higher in highest quintile group after adjustment by BMI, waist and energy intake, In addition, the highest quintile group had higher fiber intakes than the lower quintile groups. These results might suggest that a diet high in fiber and vitamin C and low in protein for obese patients would better be recommended to improve adiponectin level. However, further research is needed to elucidate the association of dietary intakes or dietary patterns and serum adiponectin level.

• Korean Journal of Community Nutrition
• /
• v.13 no.5
• /
• pp.701-712
• /
• 2008

The purpose of the present study was aimed to identify dish items applicable in developing dish?based food frequency questionnaire (DFFQ) for a hypertension study of Koreans. The 24-hour recall data of 4,401 subjects aged $20{\sim}65$ years from the 2001 Korean National Health and Nutrition Examination Survey were used for the analysis. Logistic regression model was used to identify the nutrient related with hypertension. Energy, fiber, sodium, calcium, carotene, vitamin B1 and vitamin C were associated with hypertension. Selection the top 30 dish items for these seven nutrients was performed based on their degree of contribution in supplying nutrients in terms of the cumulative percent contribution (cPC), as well as on their degree of explanation for between?person variation, in terms of the cumulative regression coefficient (cMRC). Rice supplied 43% of total energy consumption. Korean cabbage and radish kimchi were two major sources of sodium and it also covered the 27% of between person variation of sodium intake. Soybean paste soup and single item of orange?colored fruits supplied 43% of total vitamin C intake for Koreans and it covered the almost 79% of between person variation among the Korean population. Korean cabbage kimchi was the major source of fiber, calcium, sodium, carotene, and vitamin C for Koreans. In summary, the top 30 selected dish items supplying the 78% to 89% of the 7 nutrients. Those items also covered the 79% to 94% of between person variation of the 7 nutrients consumption. Therefore, the selected 30 dish items in each categories of nutrient could be applicable in developing dish based food frequency questionnaire for hypertension study.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.34 no.4
• /
• pp.277-282
• /
• 2014

Nutritive value analysis of feed is very important for the growth of livestock, and ensures the efficiency of feeds as well as economic status. However, general laboratory analyses require considerable time and high cost. Near-infrared reflectance spectroscopy (NIRS) is a spectroscopic technique used to analyze the nutritive values of seeds. It is very effective and less costly than the conventional method. The sample used in this study was a corn kernel and the partial least square regression method was used for evaluating nutrient composition, digestibility, and energy value based on the calibration equation. The evaluation methods employed were the coefficient of determination ($R^2$) and the root mean squared error of prediction (RMSEP). The results showed the moisture content ($R^2_{val}=0.97$, RMSEP=0.109), crude protein content ($R^2_{val}=0.94$, RMSEP=0.212), neutral detergent fiber content ($R^2_{val}=0.96$, RMSEP=0.763), acid detergent fiber content ($R^2_{val}=0.96$, RMSEP=0.142), gross energy ($R^2_{val}=0.82$, RMSEP=23.249), in vitro dry matter digestibility ($R^2_{val}=0.68$, RMSEP=1.69), and metabolizable energy (approximately $R^2_{val}$ >0.80). This study confirmed that the nutritive components of corn kernels can be predicted using near-infrared reflectance spectroscopy.

• Analytical Science and Technology
• /
• v.25 no.6
• /
• pp.370-374
• /
• 2012

As for quality evaluation of paper records, it is very important to measure acidity and moisture in paper. In the case important paper records, it should be measured directly in field. But ISO standard analytical method would be limited to measure directly in field for quality evaluation of paper records until now. Therefore it could be to use mobile small NIR spectrometer for being analyzed by direct and non-invasive method in field. The wavelength range of small spectrometer has from 900 to 1700 nm, and the surface of paper could be measured by diffused reflected optical fiber probe. Thus, the acidity and moisture could be analyzed on the paper record with from 1970 to 2003. As the result, it could be confirmed to have each more than 0.9 as the correlation of acidity and moisture. Thus, it will be possible to develope the evaluation system of paper record with mobile small NIR spectrometer and optical fiber by the result.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.8 no.2
• /
• pp.254-263
• /
• 1998

A worker employed in a serpentine mine was found developed mesothelioma as the first case of Korea in 1997. Asbestos was known as a causative agent for mesothelioma. Thus, asbestos contamination in mines could be a big health threat to those workers who were unknowingly exposed. However, there was no report that any minerals found in Korea contained asbestos. This study was carried out to find the presence of any asbestiform fibers in minerals which could be obtained in Korean mines. We examined fifteen minerals from 44 mines which were suspected contaminated with asbestiform fibers. Asbestiform analysis was done with high resolution transmission electron microscope(TEM), with energy dispersive X-ray spectroscope(EDX) and X-ray diffraction(XRD) analyses. Among asbestiform fibers, chrysotile was found in chrysotile, serpentine, talc and pyrophylite specimens from 11 mines. Tremolite was found in tremolite and talc specimens from three mines. Mordenite was found in zeolite specimens from two mines. Wallastonite and sepiolite were found in wallastonite and sepiolite specimens respectively. Crocidolite, antigorite and actinolite were found from talc specimens. But no asbestiform fiber contaminants were found in doromite, vermiculite, limestone, marble, gypsum, kaolin, and clary specimens. Thus, these asbestiform fibers such as such as chrysotile, tremolite, mordenite, crocidolite, antigorite and actinolite could be the responsible agents for the health hazards such as mesothelioma and other cancers.

• Journal of the Korean Wood Science and Technology
• /
• v.44 no.6
• /
• pp.828-841
• /
• 2016

Relatively little information is available regarding the correlation between wood and veneer quality, especially for Samama wood, an endemic wood species in eastern Indonesia. This study addresses the quality of 8 years old Samama wood and its effect on the veneer quality. Samama wood quality was determined by evaluating its specific gravity, moisture content, fiber dimensions, and microfibril angle from pith toward bark. Meanwhile, veneer quality was assessed by examining veneer thickness and lathe check characteristics. Geometry factor model was constructed to elaborate the quantities of lathe check from pith toward bark. Results show that fair variations of veneer thickness, ranging from 1.5 mm to 3.0 mm, could be obtained from Samama wood. The quantity, depth, and length of lathe check were noticeably decreasing toward bark. Further, in the same manufacturing process, geometry factor was determined as the dominant factor over other wood properties in affecting the frequency of lathe checks from pith towards bark. These facts should be put into consideration in producing veneer from Samama wood. Moreover, these results enlighten the potential of Samama wood as plywood and other excellent veneer-based products.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.37 no.3
• /
• pp.23-32
• /
• 2005

A change of z-directional structural and surface properties by calendering has a great influence on liquid penetration into a sheet. It could be also important for multi-ply sheet because it contacts liquid dunhg coating or converting process. Therefore, this study was aimed to evaluate of a change of z-directional structure in multi-ply sheet by calendering. To do this, multi-ply sheets were prepared with various raw materials and calendered at the different pressure and temperature conditions. In multi-ply sheet which consisted of one kind of pulp fiber, thickness reductions were higher in top and bottom plies than in middle plies. And in the case of soft nip calender treatment with high temperature, top layer which was in contact with heating roll showed the highest reduction of thickness. Hard nip calender treatment showed U-shaped density profile in z-direction, but compression profile by SNC treatment was dependent on calendering condition. To examine z-directional structure of multi-ply sheet which was composed of different raw material for each layer, CLSM (Confocal Laser Scanning Microscopy) analyses were carried out on cross direction of sheet. It turned out to be a useful tool for investigating z-directional analysis. As a result, variation of thickness reduction in z-direction is dependent on ply structure, compressibility of pulp fiber, and calendering condition.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
• /
• 2001.06a
• /
• pp.4103-4103
• /
• 2001

The aim of this study was to examine whether near infrared spectroscopy (NIRS) is an acceptable tool to determine cholesterol and collagen in human atherosclerotic plaque without destruction of the analyzed areas and without danger the endothelial cells - three preconditions for the development of a NIR-heart-catheter. The questions were: Can the cholesterol and collagen content of the arterial intima be estimated with acceptable precision in vitro by NIRS despite the matrix inhomogeneity of the plaques and their anatomic variability\ulcorner How deep can such NIR radiation penetrate into arterial tissue without danger for endothelial cells\ulcorner Is this penetration sufficient for information on the lipid and collagen accumulation\ulcorner Using NIRS, cholesterol and collagen can be determined with acceptable precision in model mixtures and human aortic specimens (r=0,896 to 0,957). The chemical reference method was HPLC. The energy dose was 71 mW/$cm^{-2}$ using a fiber optic strand with a length of 1.5m and an optical window of d=4mm. This dose appears to be not dangerous for endothelial cells, It will be attenuated to 50% by a arterial tissue of about 170-$200\mu\textrm{m}$ thickness. The results are also acceptable using a thin coronary catheter-like fiber optic strand (d=1mm).

• Journal of Korean Society for Atmospheric Environment
• /
• v.19 no.6
• /
• pp.639-646
• /
• 2003

In this study, we evaluated genotoxicity of heavy metals among particulates with Tradescantia-micronucleus (Trad-MCN) assay in the various working environment. In a synthetic fiber factory and a rubber factory, chromium concentration was higher than any other heavy metals. On the other hand, nickel concentration was the highest in a semi-conductor factory. The difference in genotoxicity among the working environment was statistically significant as Trad-MCN frequencies were 4.07 $\pm$0.35 MCN/100 tetrads (p< 0.01) for the synthetic fiber factory,5.73 $\pm$0.81 MCN/100 tetrads (p< 0.01) for the rubber factory, and 15.60$\pm$2.58 (p< 0.01) (p< 0.001) for the semi -conductor factory. As a result, heavy metals among particulates in the working environment can be considered to have hazardous potential to human health, although they cannot directly induce DNA damage to the workers in the working environments.