• 한국재료학회지
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• 제17권7호
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• pp.358-360
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• 2007

Cobalt subtitution on NiSi is investigated by using an ab-initio calculation. Firstly, a relaxed NiSi structure is calculated and the calculated lattice parameters are compared with experimentally determined lattice parameters. The calculated values are smaller than the experimental values by about 2%. As the calculation is based on 0 K, and the experimental measurement is performed at room temperature, those values are in good agreement. Next, a Co atom substitutes a Ni and Si site, respectively, to evaluate the preferable site between them. Co prefers Ni site to Si site. The calculated total energy also indicates that the Co substitution to Ni site stabilizes the NiSi structure. Therefore, the thermal stability of NiSi with Co addition can be achieved by the structure stabilization of NiSi by Co substitution into Ni site of NiSi.

• 대한한방내과학회지
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• 제15권1호
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• pp.165-175
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• 1994

Effects of moxibution at the Gwanweon, Jungwan and Joksamlee on the blood picture in rat with transportation stress were determined. Counts of RBC showed a tendency to increase from 6 hours to 12 hours after transportation stress, however in the moxibution group, showed no changes in counts of RBC after transportation stress and the tendency of fluctuation was similiar to those of none stress group. The changes in Hb after transportation stress showed no difference among moxibution group and none moxibution group, however the changes in PCV showed a tendency to increase from 3 hours to 6 hours after transportation stress in two stress group. In the mean values of erythrocytic blood during experimental times, counts of RBC showed a high values (P<.05) in the stress only group, however in the other groups, these values showed no difference (P>.05) among treatment and the values of Hb and PCV showed no difference among 4 treatment groups. In the two stress groups, counts of WBC and Neutrophils showed a tendency to decrease after transportation stress, however the moxibution group was recovered to normal Leukocytes condition on short time compared with those of none moxibution group. In the mean values of Leukocytes during experimental times, counts of WBC and Neutrophils showed a high values and Lymphocytes showed a low values in the stress only group compared with those of other groups, however the stress group with moxibution showed no difference in Leukocytes values compared with those of normal condition group. Monocytes, Basophils and Eosinophils showed no difference among 4 treatment groups(P>.05). Results from this study indicate that the moxibution can tolerate the effects of transportation stress in rat.

• 한국식품영양학회지
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• 제4권1호
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• pp.21-34
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• 1991

The purposes of this studies were to investigate the effect of dietry Se levels and alcohol administration on the lipid hyperoxidation and the lipid metabolism in the rat. Seventy two male rats of Sprague-Dawley Strain weighting about 58~629 were divided into 12groups. The dietary Se levels were 10, 0.4 and Omg, and the dietary a-tocopherol levels were 150 and 0mg per kg diet, respectively. Alcohol-administrated groups received drinking water solution containing 10% of ethanol from the 3-weeks of experimental periods. The obtained experimental results are summarized as follows. 1. Food intake, body weight gain and food efficiency ratio were significantly lower in H-, L-and alcohol administrated groups(-A) by administrated Se and alcohol in diet. The weight of liver and spleen tended to be greater in H- and alcohol administrated groups. 2. The glutathione values in liver tend to be lower in alcohol or Vit. E administrated groups than nonadministrated groups. Also there were higher in H- and L- than C-groups, but the increasing range decreased due to administrated alcohol. The lipid peroxide values In liver were significantly higher in alcohol groups, and L- and tocopherol groups were higher values. Specially the increasing of lipid peroxide values were significantly effected by alcohol in low Se and Vit. E groups. 3. The contents of total glyceride in plasma were higher in alcohol groups, there were significantly higher values in alcohol administrated groups under low Se and Vit. E groups. The contents of total cholesterol and HDL-cholesterol In plasma were significantly higher in alcohol groups. 4. The contents of total lipid in liver were higher alcohol groups, and slightly higher values in low Se groups(L-groups) than other groups, also higher values in low Vit. E groups. Those of total glyceride in liver were significantly higher in alcohol groups, appeared highest values when alcohol was administrated in low Se and Vit. E groups. The increasing of total glyceride content was significantly effected by alcohol in low Se groups than that in C-groups.

• 대한조선학회지
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• 제9권1호
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• pp.1-6
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• 1972

To contribute towards more accurate estimation of the virtual coefficient for the vertical vibration of the chine-type ship, experimentally obtained three-dimensional correction factors, J, of added mass of prismatic beams having cross section shape of hypotrocoid characters, slightly concaved Lewis form and elliptic form are investigated in connection with the applicability of an approximate analytical calculation method compared to that proposed by T. Kumai[6] for the Lewis form cylinders, and synthetically in compared with the experimental works on various cross section shapes of the other type by L.C. Burril et al[8] and the analytical works on the ellipsoid of revolution by F.M. Lewis[1] and J.L. Taylor[2]. The experimental results show that the aforementioned analytical method gives, unlike that for the Lewis form cylinders, considerably larger J-values for the chine-type cylinders, and that the influence of the character of the cross section shape on J-values is not remarkable in practical sense. Finally, considering in synthesis the experimental results on prismatic beams, the Burril's works on palabolic plan form and elliptic plan form, and that the chine-type ship usually has a hull form of transom stern, it is fairly safe to say, at the present stage, that adoptation of the Taylor's J-values will not results in any large error in estimation of the virtual inertia coefficients of the chine-type ships.

• Journal of the Korean Wood Science and Technology
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• 제20권3호
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• pp.21-27
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• 1992

The amount of moisture transmitted under four different humidity conditions was measured in earlywood and latewood for Cryptomeria japonica(LT specimens). The results obtained are summarized as follows. The vapor permeability in eariywood was about three times larger than that of latewood. The vapor permeabilities in earlywood and late wood depended on the average moisture content of the wood. This indicates that moisture transmission is influenced by vapor permeability or vapor-transmission resistance, but the values obtained by experiments do not have great adaptability for practical situations because of changes in the experimental conditions. There fore, it is necessary to know the moisture content along the flow direction in order to explain the moisture transmission of wood. The vapor permeability was calculated using the density in air dried wood. These were then compared with the experimental values. The vapor permeabilities calculated with this density in the radial direction(LR specimen) had a good tendency to agree with the experimental values, but not so in tangential direction(LT specimen).

• 한국해양공학회지
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• 제2권2호
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• pp.96-103
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• 1988

The stress distribution in the vicinity of the crack tip in the fracture mechanics is ordenarily indicated by the stress intensity factor. In the analysis of stress intensity factors, there are many theoretical and experimental methods. The stress analysis in photoelastic technique is usually made by using the difference of the principal stress of isochromatic fringe patterns. In this paper, the teflon molding technique is adopted to make a test specimen with a circular arc-crack, and that upgraded the accuracy of experiment. As the result, the experimental values of the stress intensity factors for the circular disk with a straight crack are coincided with the theoretical values. But, there is quite a difference between this expermental results on the finite plate for circular arc-crack and its theoretical values on the infinite one. Therefore, a boundary condition with regard to the loading condition on finite disk must be considered.

• 대한치과기공학회지
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• 제35권4호
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• pp.333-341
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• 2013

Purpose: The purpose of this study was to evaluate the flexural strength of indirect composite resins with different polymerization conditions. Methods: Ten specimens ($2mm{\times}2mm{\times}25mm$) of each composite resins (Tescera (T), Gradia (S) and Sinfony (S)) were fabricated by two polymerization methods : manufacturers's and light heat pressure. Composite resins polymerized by manufacturers's method and light heat pressure served as control (TS, GS and SS) and experimental groups (TE, GE and SE), respectively. The composite resins were tested for flexural strength and the surface of composite resins were observed with scanning electron microscope (SEM) under X1,000 magnification. Results: The flexural strength values of cured composite resin decreased in the following order: TE (195.4MPa), TS (179.8MPa), GE (169.9MPa), SE (137.7MPa), SS (111.1MPa) and GS (100.9MPa) groups. Conclusion: The flexural strength values between the control and the experimental groups were not significantly different although experimental groups showed higher flexural strength values than control groups.

• Bulletin of the Korean Chemical Society
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• 제15권3호
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• pp.221-227
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• 1994

The barrier heights of the internal rotations for ethyl halides calculated by ab initio methods differ from those of experiments by more than 0.2 kcal/mol. The use of basis sets larger than the $6-31G^{\ast}$ set and the inclusion of correlation do not improve the agreement between the calculated and experimental values. The zero-point vibration corrections are substantial in the HF calculations with $6-31G^{\ast}$ basis sets, but become negligible in the MP2 calculations with $6-311G^{{\ast}{\ast}}$ basis sets for $C_2H_5F\;and\;C_2H_5Cl$. It is shown that the rigid rotor approximation and the assumed shape of the potential curve as a cos2${\theta}$ curve could also be the sources of discrepancies between calculated and experimental values. Higher order perturbation corrections narrow the gap between experimental and theoretical values, but there still remains about 10% overestimate of 0.3 kcal/mol. Optimized geometries from the HF and MP2 calculations are in good agreement with those from experiments. Dipole moments calculated from the MP2 densities show slightly better agreement with experiments than those from the HF densities.

• 대한치과교정학회지
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• 제19권2호
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• pp.7-24
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• 1989

The physical properties of seven sizes of control groups and experimental group in stainless steel orthodontic wires were studied in tension, hardness, bending, torsion and observation of microstructure. The wires (0.40-0.90mm dia.) of round type were tested in the as-received condition. The wires of control groups were TRU-CHROME and REMANIUM, and experimental group was SK wire which was developed by ourselves and made in Korea. The results were as follows; 1. The chemical compositions of control groups and experimental group were austenite stainless steel wires of SOS 304. 2. Higher values of tensile and yield strength in tension were control group I, experimental group, control group II. Maximum tensile and yield strength of experimental group were $203.63{\pm}1.41kg/mm^2$ in 0.70mm diameter and $148.96{\pm}4.88kg/mm^2$ in 0.60mm diameter, and maximum elongation was $5.20{\pm}0.57%$ in 0.45mm diameter. 3. Hardness values of experimental group were similar to control groups. Maximum hardness values were $596.2{\pm}13.66Hv$ in 0.45mm diameter wire of control group I, $590.5{\pm}20.08Hv$ in 0.50mm diameter wire of control group II, and $563.6{\pm}5.35Hv$ in 0.70mm diameter wire of experimental group. 4. Torsion properties of experimental group were similar to control group I and more than control group II. Maximum torsion cycles were $31.8{\pm}2.48$ in 0.45mm diameter of control group I, $17.4{\pm}4.84$ in 0.60mm diameter of control group II, and $24.6{\pm}3.04$ in 0.45mm diameter of experimental group. 5. Maximum bending cycles of experimental group were smaller than control groups. Maximum bending cycles were $9.00{\pm}0.00$ in 0.50mm diameter wire of control group I, $10.0{\pm}0.82$ in 0.40mm diameter wire of control group II, and $8.0{\pm}1.26$ in 0.50mm diameter wire of experimental group. 6. Microstructures of experimental and control groups co-existed with martensited austenite structure and elongated austenite structure. 7. The direction of wire fracture was propagated parallel to torsion direction typically and there was no probability showing wire fracture at inclusions and surface scratches. 8. The type of wire fracture was brittle fracture at initiation site and ductile fracture at core.

• Journal of Mechanical Science and Technology
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• 제20권9호
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• pp.1492-1501
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• 2006

A transportation system of single wafer has been developed to be applied to semiconductor manufacturing process of the next generation. In this study, the experimental apparatus consists of two kinds of track, one is for propelling a wafer, so called control track, the other is for generating an air film to transfer a wafer, so called transfer track. The wafer transportation speed has been evaluated by the numerical and the experimental methods for three types of nozzle position a..ay (i.e., the front-, face- and rear-array) in an air levitation system. Test facility for 300mm wafer has been equipped with two control tracks and one transfer track of 1500mm length from the starting point to the stopping point. From the present results, it is found that the experimental values of the wafer transportation speed are well in agreement with the computed ones. Namely, the computed values of the maximum wafer transportation speed $V_{max}$ are slightly higher than the experimental ones by about $15{\times}20%$. The disparities in $V_{max}$ between the numerical and the experimental results become smaller as the air velocity increases. Also, at the same air flow rate, the order of wafer transportation speeds is : $V_{max}$ for the front-array > $V_{max}$ for the face-array > $V_{max}$ for the rear-array. However, the face-array is rather more stable than any other type of nozzle array to ensure safe transportation of a wafer.