• Journal of Periodontal and Implant Science
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• 제43권5호
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• pp.227-232
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• 2013

Purpose: The receptor activator of nuclear factor kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) system plays a significant role in osteoclastogenesis, activation of osteoclasts, and regulation of bone resorption. This study aimed to evaluate the use of the salivary soluble RANKL (sRANKL)/OPG ratio as a diagnostic marker for periodontitis in nonsmokers. Methods: Twenty-five patients with chronic periodontitis and 25 individuals with a healthy periodontium were enrolled in this study. Samples containing 5 mL of unstimulated saliva were obtained from each subject. Salivary sRANKL and OPG concentrations were determined using a standard enzyme-linked immunosorbent assay. Statistical analysis was performed using SPSS ver. 18.0. Results: The levels of sRANKL and OPG were detectable in all of the samples. Positive relationships were found between the plaque index and clinical attachment level and both the salivary concentration of sRANKL and the salivary sRANKL/OPG ratio (P<0.05). The salivary concentration of sRANKL and the sRANKL/OPG ratio were significantly higher in the periodontitis group than in the healthy group (P=0.004 and P=0.001, respectively). In contrast, the OPG concentration showed no significant differences between the groups (P=0.455). Conclusions: These findings suggest that the salivary sRANKL/OPG ratio may be helpful in the screening and diagnosis of periodontitis. However, longitudinal studies with larger populations are needed to confirm these results.

• 소성∙가공
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• 제18권7호
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• pp.550-555
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• 2009

In the multi-pass shape drawing process, the pass schedule that includes the determination of reduction ratio and intermediate die shape is very important. This study used the equal reduction, equal load, and electric field analysis method for pass schedule of the multi-pass shape drawing. The reduction ratio was calculated by the equal reduction and equal load method. And the intermediate die shape was determined by the result of the electric field analysis and the calculated reduction ratio. The proposed pass schedule method was applied to a shape drawing for producing cross roller guide. Finally, FE-analysis and shape drawing experiment were performed to verify the effectiveness of the proposed method.

• 소성∙가공
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• 제19권3호
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• pp.179-184
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• 2010

The present study is focused on the deep drawability and product qualities of ultra thin beryllium copper sheet metal. The goal of this research is to investigate the limit drawing ratio in deep drawing of ultra thin beryllium copper metal. For the experiment, beryllium copper(C1720, $50{\mu}m$ in thickness) is used. Tensile test are also carried out to find out the material properties. Deep drawing experiments are carried out in Universal Testing Machine(UTM) to obtain limit drawing ratio. Deep drawing tests are carried out for various specimen sizes. Teflon film is used as a lubricant and constant blank holding force is imposed. Sheet thickness and surface hardness are measured along radial direction after deep drawing. Thickness is measured using optical microscope. For beryllium copper(C1720), the maximum LDR of 2.4 is obtained when the die shoulder radius is 20 or 30 times of sheet thickness.

• Nutritional Sciences
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• 제4권1호
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• pp.20-25
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• 2001

The dietary vitamin $B_6$ intake of 218 Korean young women (aged 20-26y), who had no health problems, and their sources were estimated using a modified Korean vitamin $B_6$ database. The average daily vitamin $B_6$ intake was 0.987 mg for the subjects. About 87.2% of the subjects consumed less than the Korean Recommended Dietary Allowance (RDA) of vitamin $B_6$. The average ratio of vitamin $B_6$ intake to daily protein intake was 0.014 mg/g protein, and approximately 91% of subjects consumed 〈 0.02 mg/g protein. Vitamin $B_6$ intake was significantly (p〈.01 -p〈.001) positively correlated to the intakes of all other nutrients. Between animal and vegetable protein, animal protein had a stronger positive correlation with vitamin $B_6$. Major dietary sources of vitamin $B_6$, the top 10 foods provided nearly 64% of total vitamin $B_6$, and dietary contributors of vitamin $B_6$ for Koreans are less varied than those for Americans.

• 한국소음진동공학회논문집
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• 제19권9호
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• pp.960-966
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• 2009

The World Health Organization(WHO) has reported the sleep disturbance as one of the adverse effects of noise. And the effect of combined noise sources on human have been investigated because community noises are seldom heard and are concurrent. Therefore, the effects of combined noise source and its S/N ratio on sleep disturbance were investigated; as a single noise source, road traffic noise was selected, and construction and movie noise were combined with road traffic noise. Tests for sleep disturbance were conducted in bedrooms and the effect on each subjects' sleep was evaluated by questionnaire. The results showed that the rate of awakening increased slightly only when the SPL of construction noise was 10 dB higher than that of road traffic noise. It was also found that the sleep disturbance was affected by the type of combined noise sources and its S/N ratio.

• International Journal of Concrete Structures and Materials
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• 제7권4호
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• pp.287-293
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• 2013

Strength and some durability properties of concrete containing rice husk ash (RHA) predominantly composed of amorphous silica at a specific surface of 235 $m^2/kg$ produced using a charcoal incinerator were determined. The maximum ordinary Portland cement (OPC) replacement with the RHA increased with increase in water/binder (w/b) ratio of the concrete mixes. The results show that 15 % OPC could be substituted by the RHAwithout strength loss at w/b ratio of 0.50. The split tensile strength generally increased with increase in RHA content for the mixes.

• 대한기계학회논문집B
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• 제33권4호
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• pp.215-224
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• 2009

Analysis for various driven nozzle position changes. The analysis was done for different Reynolds number in entrance region of jet-pump and for several diameter ratios of driven nozzle. (1) The largest absorption energy was found at the point s=1 in condition of diameter ratio 1:3.21 and point s=0.5 in condition of diameter ratio 1:2.25. (2) The absorption energy was not related to the change of entrance velocity and the driven nozzle position having the largest absorption energy was function for cross section ratio. (3) As the position of driven nozzle moves to the downstream, the absorption energy gets weaker. Because the energy from swirl was lost at the cross section gets smaller. (4) As the position of driven nozzle moves to the downstream, the injection energy leans to the upper direction wall and as the Reynolds number increase, the lean phenomenon is more distinct. (5) The flow quantity of driven nozzle, the diameter ratio 1:3.21, was 32% higher than that of 1 : 2.25 and as the inlet velocity gets faster the efficiency decreased. And as the cross section of the driven nozzle increases.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.391-395
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• 2000

In this study, the temperature coefficient of resonant frequency(TC $F_{r}$), dielectric and piezoelectric properties of Pb[(S $b_{1}$2/N $b_{1}$2/)$_{0.0035}$-(M $n_{1}$3/N $b_{2}$3/)$_{0.0065}$-(Z $r_{x}$ $Ti_{1-x}$ )$_{0.90}$] $O_3$ceramics is investigated with Zr/Ti ratio. The dielectric constant and electromechanical coupling factor( $k_{p}$) showed the highest values of 1257, 0.562 respectively when the Zr/Ti ratio is 49.5/50.5. The mechanical quality factor( $Q_{m}$) is the lowest value of 713 when the Zr/Ti ratio is 49.5/50.5, and increased with the decrease of the Zr/Ti ratio. The temperature coefficient of resonant frequency(TC $F_{r}$) change abruptly at the morphotropic phase boundary(MPB), which is between the rhombohedral phase with highly negative TC $F_{r}$ of -106ppm/$^{\circ}C$ and the tetragonal phase with highly positive TC $F_{r}$ of +64pp $m^{\circ}C$ as Zr/Ti ratio changes from 50/50 to 49.5/50.5.50.5..5.50.5.5.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.645-646
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• 2011

• 전기의세계
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• 제28권4호
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• pp.53-63
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• 1979

Interface recombination velocity in $Al_{x}$G $a_{1-x}$ As-GaAs and $Al_{0.85}$, G $a_{0.15}$ As-GaA $s_{1-y}$S $b_{y}$ heterojunction systems is studied as a function of lattice mismatch. The results are applied to the design of highly efficient III-V heterojunction solar cells. A horizontal liquid-phase epitaxial growth system was used to prepare p-p-p and p-p-n $Al_{x}$G $a_{1-x}$ As-GaA $s_{1-y}$S $b_{y}$-A $l_{x}$G $a_{1-x}$ As double heterojunction test samples with specified values of x and y. Samples were grown at each composition, with different GaAs and GaAs Sb layer thicknesses. A method was developed to obtain the lattice mismatch and lattice constants in mixed single crystals grown on (100) and (111)B oriented GaAs substrates. In the AlGaAs system, elastic lattice deformation with effective Poisson ratios .mu.$_{eff}$ (100=0.312 and .mu.$_{eff}$ (111B) =0.190 was observed. The lattice constant $a_{0}$ (A $l_{x}$G $a_{1-x}$ As)=5.6532+0.0084x.angs. was obtained at 300K which is in good Agreement with Vegard's law. In the GaAsSb system, although elastic lattice deformation was observed in (111) B-oriented crystals, misfit dislocations reduced the Poisson ratio to zero in (100)-oriented samples. When $a_{0}$ (GaSb)=6.0959 .angs. was assumed at 300K, both (100) and (111)B oriented GaAsSb layers deviated only slightly from Vegard's law. Both (100) and (111)B zero-mismatch $Al_{0.85}$ G $a_{0.15}$As-GaA $s_{1-y}$S $b_{y}$ layers were grown from melts with a weight ratio of $W_{sb}$ / $W_{Ga}$ =0.13 and a growth temperature of 840 to 820 .deg.C. The corresponding Sb compositions were y=0.015 and 0.024 on (100) and (111)B orientations, respectively. This occurs because of a fortuitous in the Sb distribution coefficient with orientation. Interface recombination velocity was estimated from the dependence of the effective minority carrier lifetime on double-heterojunction spacing, using either optical phase-shift or electroluminescence timedecay techniques. The recombination velocity at a (100) interface was reduced from (2 to 3)*10$^{4}$ for y=0 to (6 to 7)*10$^{3}$ cm/sec for lattice-matched $Al_{0.85}$G $a_{0.15}$As-GaA $s_{0.985}$S $b_{0.015}$ Although this reduction is slightly less than that expected from the exponential relationship between interface recombination velocity and lattice mismatch as found in the AlGaAs-GaAs system, solar cells constructed from such a combination of materials should have an excellent spectral response to photons with energies over the full range from 1.4 to 2.6 eV. Similar measurements on a (111) B oriented lattice-matched heterojunction produced some-what larger interface recombination velocities.ities.ities.s.