• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.253-261
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• 2002

Vibrational properties of ferrocyanide complex ion, $[Fe(CN)_6]^{4-}$ , have been studied based on the force constants obtained from the density functional calculations at B3LYP/$6-31G^{\ast\ast}$ level by means of the normal mode analysis using new bond angle and linear angle internal coordinates recently developed. Vibrations of ferrocyanide were manipulated by twenty-three symmetry force constants. The angled bending deformations of C-Fe-C, the linear bending deformations of Fe-C${\equiv}$N and the stretching vibrations of Fe-C have been quantitatively assigned to the calculated frequencies. The force constants in the internal coordinates employed in the modified Urey-Bradley type potential were evaluated on the density functional force field applied, and better interaction force constants in the internal coordinates have been proposed. The valence force constants in the general quadratic valence force field were also given. The stretch-stretch interaction and stretch-bending interaction constants are not sensitive to the geometrical displacement in the valence force field.

• Journal of the Korean institute of surface engineering
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• v.35 no.2
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• pp.129-137
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• 2002

The purpose of solderability assessment is to predict the effectiveness of soldering process. It is important for companies pursuing zero defects manufacturing because poor solderability is the major cause of two third of soldering failures. The most versatile solderability method is wetting balance method. However, there exist so many indices for wettability in the wetting balance test e.g. time to reach 2/3 values of maximum wetting force, tine to reach zero wetting force, maximum withdrawal force. In this study, three solderability assessment methods, which were the maximum withdrawal force, the wetting balance and the dynamic contact angle (DCA), were evaluated by comparing each other. The wetting balance technique measures the solderability by recording the forces exerted from the specimen after being dipped into the molten solder. Then the force at equilibrium state can be used to calculate a contact angle, which is known as static contact angles. The DCA measures contact angles occurred during advancing and withdrawing of the specimen and the contact angles are known as dynamic contact angles. The maximum withdrawal force uses the maximum force during withdrawal movement and then a contact angle can be calculated. In this study, the maximum withdrawal force method was found to be an objective index for measuring the solderability and the experiment results indicated good agreement between the maximum withdrawal force and the wetting balance method.

• YAKHAK HOEJI
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• v.42 no.3
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• pp.290-295
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• 1998

To optimize the formulation of acetaminophen liquid suppository, the effect of additives on the physicochemical properties of liquid suppository base was investigated. The physi cochemical properties of P 407/P 188 (15/15%) (abbreviated in 15/15) and P 407/P l88 (15/20%) (abbreviated in 15/20) were measured after the addition of following additives; 2.5% acetaminophen as an active ingredient, vehicle components (5% ethanol, 5% propylene glycol, 5% glycerin), preservatives (0.1% sodium benzoate, 0,1% methylparahydroxybenzoate, 0.1% propylparahydroxybenzoate) and 1% of sodium chloride as an ionic strength controlling agent. Poloxamer gel was prepared with three different buffer solutions (pH 1.2, 4.0 and 6.8) and the physicochemical properties, gelation temperature, gel strength and bioadhesive force, were determined. In the results, the effect of additives on the physicochemical properties was dependent on their bonding capacities including hydrogen bonding and cross-linking bonding. Because the hydrogen-bonding capacities of acetaminophen, ethanol and propylene glycol were smaller than that of poloxamer, the binding force of poloxamer gel became weak by their putting in between poloxamer gel. Therefore, the gelation temperature (15/15, $35.7^{\circ}C$ vs 37.0, 39.4 $38.2^{\circ}C$; 15/20, $29.2^{\circ}C$ vs 31.2, 32.0, $30.3^{\circ}C$) increased, and gel strength (15/15, 4.03 see vs 2.72, 2.08, 3.12sec; 15/20, 300g vs 50, 50, 200g) and bioadhesive force (15/15, $6.8{\times}10^2\;dyne/cm^2$ vs 3.2, 6.0, $6.0{\times}10^2\;dyne/cm^2$; 15/20, $97.3{\times}10^2\;dyne/cm^2$ vs 11.1, 89.5, $92.0{\times}10^2\;dyne/cm^2$) decreased. Furthermore, the binding force of poloxamer gel became strong due to the hydrogen-bonding capacities of glycerin and the cross-liking bonding of sodium salt. Then, the gelation temperature (15/15, 35.0, $32.1^{\circ}C$; 15/20, 26.0, $21.0^{\circ}C$) decreased, and gel strength (15/15, 6.51 see, 300g; 15/20, 500, 650g) and bioadhesive force (15/15, 7.2, $81.6{\times}10^2\;dyne/cm^2$; 15/20, 112.3, $309.2{\times}10^2\;dyne/cm^2$) increased. The effect of pH on the physicochemical properties of poloxamer gel was dependent on the ingredients with which the buffer solutions were prepared. Poloxamer gels prepared with pH 1.2 and 4.0 buffer solutions had the increasing gelation temperature (15/15, 37.5, $38.1^{\circ}C$; 15/20, 33.1, $34.0^{\circ}C$) and the decreasing gel strength (15/15, 2.98, 3.81sec; 15/20, 200, 200g) and bioadhesive force (15/15, $7.0{\times}10^2dyne/cm^2$; 15/20, $74.0{\sim}88.1{\times}10^2dyne/cm^2$) owing to HCl. Poloxamer gel prepared with pH 6.8 buffer solutions had the decreasing gelation temperature (15/15, $27.2^{\circ}C$; 15/20, $22.3^{\circ}C$) and the increasing gel strength (15/15, 400g; 15/20, 550g) and bioadhesive force (15/15, $207.0{\times}10^2dyne/cm^2$; 15/20, $215.0{\times}10^2dyne/cm^2$) due to the cross-linking bonding of $NaH_2PO_4\;and\;K_2HPO_4$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.471-474
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• 2004

In this paper, a NURBS surface interpolator is proposed which can deal with shapes defined from CAD/CAM programs on a surface basis and can improve contour accuracy. The proposed interpolator is based on newly defined G-codes and includes online tool-path planning suitable for NURBS surface machining. The real-time interpolation algorithm, considering an effective machining method for each machining process and minimum machining time, is executed in an online manner. The proposed interpolator is implemented on a PC-based 3-axis CNC milling system and evaluated through actual machining in terms of machining time and regulation of feedrate and cutting force in comparison with the existing method.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.5 no.4
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• pp.98-107
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• 1996

In order to predict analytically torque, thrust force, tool life and chip formation in drilling, cutting models for chisel edge with various tool-chip contact length were developed in this type. Also, the experimental tests are run with various pilot holes. The following conclusions were obtained from the analysis. \circled1 It's also found experimentally that thrust force(Fz) decreases as pilot hole diameter increases. \circled2 Surface roughness for material(G) is larger that for material(J). The difference over two materials in roughness value about 0.5$mu extrm{m}$. \circled3 Flank wear of the drill in cutting material of G less than any other kinds of materials(F, G, H, I, J). \circled4 In drilling a deep hole on a workpiece over SM45C either twist drill. The chip was conical helix type at the fist suspensely change the two segment type and than two a long pitch helix style.

• Journal of Korean Port Research
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• v.10 no.1
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• pp.15-23
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• 1996

In this paper, the numerical model to analyze the wave absorbing performance of upright perforated plates is developed under the linear potential theory. If the drag force is dominent to the inertia force in passing perforated plate, the characteristics of perforated plates are determined by a nondimensionlized real-value of G or a length scaled real-value of a. The parameters (G,a), which depend on the drag coefficient, porosity and local shape of plates, can be readily obtained by simple experiments. We investigated the reflection coefficients over a wide frequency range according to the arrays of perforated plates with different values of G and a. We found that the wave absorbing system using the arrays of upright perforated plates is sufficient to install in the ocean engineering basin.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.2
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• pp.109-123
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• 2009

The aim of the study was to assess the influence of insertion torque of bone quality and to compare axial force, moment and von Mises stress using finite element analysis of plastoelastic property for bone stress and strain by dividing bone quality to its thickness of cortical bone, density of trabecular bone and existence of lower cortical bone when implant inserted to mandibular premolar region. The $Br{\aa}nemark$ MKIII. RP implant and cylindrical bone finite model were designed as cortical bone at upper border and trabecular bone below the cortical bone. 7 models were made according to thickness of cortical bone, density of trabecular bone and bicortical anchorage and von Mises stress, axial force and moment were compared by running time. Dividing the insertion time, it seemed 300msec that inferior border of implant flange impinged the upper border of bone, 550msec that implant flange placed in middle of upper border and 800msec that superior border of implant flange was at the same level as bone surface. The maximum axial force peak was at about 500msec, and maximum moment peak was at about 800msec. The correlation of von Mises stress distribution was seen at both peak level. The following findings were appeared by the study which compared the axial force by its each area. The axial force was measured highest when $Br{\aa}nemark$ MKIII implant flange inserts the cortical bone. And maximal moment was measured highest after axial force suddenly decreased when the flange impinged at upper border and the concentration of von Mises stress distribution was at the same site. When implant was placed, the axial force and moment was measured high as the cortical bone got thicker and the force concentrated at the cortical bone site. The influence of density in trabecular bone to axial force was less when cortical bone was 1.5 mm thick but it might be more affected when the thickness was 0.5 mm. The total axial force with bicortical anchorage, was similar when upper border thickness was the same. But at the lower border the axial force of bicortical model was higher than that of monocortical model. Within the limitation of this FEA study, the insertion torque was most affected by the thickness of cortical bone when it was placed the $Br{\aa}nemark$ MKIII implant in premolar region of mandible.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.9
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• pp.1227-1231
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• 2004

Pig oocytes contain high levels of lipids in the ooplasm, which reduces the visibility of the germinal vesicle (GV) under microscopic examination. Therefore, the purposes of this study were to investigate the effects of relative centrifugation force (RCF) on the visibility and maturation rates of the GV stage oocytes after centrifugation. In Experiment 1, cumulus-oocyte-complexes (COCs) were collected from slaughterhouse ovaries and randomly allocated to different RCFs (3,000 rpm: 970 g; 6,000 rpm: 3,900 g; or 10,000 rpm: 10,840 g) for 10 or 20 min. Percentages of visible GV were 76-79% in the oocytes centrifuged with 10,000 rpm, which were significantly higher (p<0.01) than those with 3,000 and 6,000 rpm. No significant differences in GV visibility were observed among oocytes with different lengths of centrifugation (p<0.05) regardless of the RCFs. In esperiment 2, the maturation rate of the oocyte was found significantly lower in the 20 min than in the 10 min group received 10,840 g of RCF (30 vs. 75%, p<0.05). In conclusion, the GV of porcine oocytes can be clearly visible by centrifugation at 10,840 g for 10 min without compromising their subsequent maturation rates and a longer centrifugation time (20 min) had no beneficial influence on the visibility of GV stage pig oocytes.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.53-58
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• 2001

This paper presents a high resolution capacitive microaccelerometer for applications to personal information systems. We reduce the mechanical noise level of the microaccelerometer by increasing the proof-mass based on deep RIE process. We reduce the electrical noise level by increasing the amplitude of an AC sense voltage. The high sense voltage is obtained by DC-to-DC voltage multiplier. In order to solve the nonlinearity problem caused by the high sense voltage, we modify the conventional comb electrode of straight finger type into that of branched finger type, resulting in self force-balancing effects for enhanced detection linearity. The proposed branched finger capacitive microaccelerometer was fabricated by the deep RIE process of an SOI wafer. The fabricated microaccelerometer reduces the electrical noise at the level of $2.4{\mu}g/\sqrt{Hz}$ for the sense voltage of l6.5V, which is 10.1 times smaller than the electrical noise level of $24.3{\mu}g/\sqrt{Hz}$ at 0.9V. For the sense voltage higher than 2V, the electrical noise level of the microaccelerometer became smaller than the constant mechanical noise level of $11{\mu}g/\sqrt{Hz}$. Total noise level, including the electrical noise and the mechanical noise, has been measured as $9{\mu}g/\sqrt{Hz}$ for the sense voltage of 16.5V, which is 3.2 times smaller than the total noise of $28.6{\mu}g/\sqrt{Hz}$ for the sense voltage of 0.9V. The self force-balancing effect results in the increased stiffness of 1.98 N/m at the sense voltage of 17.8V, compared to the stiffness of 1.35 N/m at 0V, thereby generating the additional stiffness at the rate of $0.002N/m/V^{2}$.

• Journal of Periodontal and Implant Science
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• v.42 no.6
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• pp.243-247
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• 2012

Purpose: The effects of magnetostrictive and piezoelectric devices on tooth surfaces seem to differ with regard to the root surface roughness they produce. This study aimed to compare the results of scaling using magnetostrictive and piezoelectric devices on extracted teeth. Methods: Forty-four human extracted teeth were assigned to four study groups (n=11). In two groups (C100 and C200), the teeth were scaled using a magnetostrictive device and two different lateral forces: 100 g and 200 g, respectively. In the other two groups (P100 and P200), the teeth were scaled with a piezoelectric device with 100 g and 200 g of lateral force, respectively. The teeth were scaled and the data on the duration of scaling and the amount of surface were collected and analyzed using the t-test. Results: The mean time needed for instrumentation for the piezoelectric and magnetostrictive devices was 50:54 and 41:10, respectively, but their difference was not statistically significant (P=0.171). For root surface roughness, we only found a statistically significantly poorer result for the C200 group in comparison to the P200 group (P=0.033). Conclusions: This study revealed that applying a piezoelectric scaler with 200 g of lateral force leaves smoother surfaces than a magnetostrictive device with the same lateral force.