• Design & Manufacturing
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• v.18 no.3
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• pp.15-21
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• 2024

This study investigates the causes of wrinkle defects in PA12-insulated busbars used in electric vehicles and proposes an improvement method to address these issues. Busbars, essential components for efficient current transmission in electric vehicle battery modules, require complex three-dimensional bending to optimize internal layouts. For this study, oxygen-free copper busbars with a 0.8 mm PA12 insulation coating were subjected to three types of bending tests: flat bending, edge bending, and torsional bending. Experimental results showed that wrinkle defects only occurred during edge bending, while flat and torsional bending modes exhibited no significant issues. Cross-sectional analysis revealed that the PA12 insulation layer's thickness was uneven, with thinner sections on flat areas and thicker accumulation at the comers. This uneven distribution led to poor adhesion between the insulation and copper layers, resulting in the formation of wrinkles, particularly in areas with air gaps ranging from 75 to 250 ㎛. To further analyze the issue, finite element analysis (FEA) of the bending process was performed under adhesive and non-adhesive conditions. The results confirmed that wrinkles formed when the adhesion between the copper and PA12 coating was insufficient. Improved adhesion conditions, achieved through a heat treatment process at 120℃ for 2 hours, significantly reduced the occurrence of wrinkles during edge bending. This study demonstrates that optimizing the adhesion between the insulation coating and the copper busbar, through controlled heat treatment, can prevent wrinkle defects. The findings provide a pathway for enhancing the durability and performance of insulated busbars in electric vehicle applications.

• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.441-447
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• 2023

Lead(Pb), which is currently mainly used for shielding purposes in the medical radiation, has excellent radiation shielding functions, but is continuously exposed to radiation directly or indirectly due to the harmfulness of lead itself to the human body and the inconvenience caused by its heavy weight. Research on shielding materials that are human-friendly, lightweight, and convenient to use that can block risks and replace lead is continuously being conducted. In this study, based on the commonly used polyethylene terephthalate (PET) film and the fabric material used in actual radiation protective clothing, a multi-layer thin film was realized through sputtering and vacuum deposition of bismuth, tungsten, and tin, which are metal materials that can shield radiation. Thus, a shielding film was produced and its applicability as a radiation shielding material was evaluated. The radiation shielding film was manufactured by establishing the optimized conditions for each shielding material while controlling the applied voltage, roll driving speed, and gas supply amount to manufacture the shielding film. The adhesion between the parent material and the shielding metal thin film was confirmed by Cross-cut 100/100, and the stability of the thin film was confirmed through a hot water test for 1 hour to measure the change of the thin film over time. The shielding performance of the finally realized shielding film was measured by the Korea association for radiation application (KARA), and the test conditions (inverse wide beam, tube voltage 50 kV, half layer 1.828 mmAl) were set to obtain an attenuation ratio of 16.4 (initial value 0.300 mGy/s, measured value 0.018 mGy/s) and damping ratio 4.31 (initial value 0.300 mGy/s, measured value 0.069 mGy/s) were obtained. by securing process efficiency for future commercialization, light and shielding films and fabrics were used to lay the foundation for the application of films to radiation protective clothing or construction materials with shielding functions.

• Journal of the Korean Wood Science and Technology
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• v.13 no.1
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• pp.3-18
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• 1985

In Korea, a study on the anatomical features of pitch pine (pinus rigida Miller) branch wood through photo-microscopical method was reported in 1972 by Lee. Therefore, as a further study of Lee's on the anatomical features in branch wood of pinus rigida miller that grows in Korea, compression wood, opposite wood, and side wood were selected and treated for the purpose of comparing their structures revealed on cross and radial surface through scanning electron microscope in this study. The obtained results in this study were summarized as follows; 1. The trachied transition from earlywood to late wood is very gradual and the tracheids are nearly regular in both arrangement and size in compression wood but this transition in opposite wood and side wood is abrupt and the tracheids in opposite wood and side wood are less regular than those in compression wood. Also, the annual ring width of opposite wood is narrower than that of compression wood or side wood and the rays revealed on cross surface of side wood are more distinct than compression wood and opposite wood rays. 2. The tracheids of compression wood show roundish trends especially in earlywood but those of opposite wood and side wood show some angular trends. And intercellular space, helical cavity, and spiral check are present in both earlywood and latewood of compression wood but not present in opposite wood and side wood irrespective of earlywood and latewood. 3. The wall thickness of latewood tracheid is similar to that of earlywood tracheid in compression wood whereas the wall thickness of latewood tracheid is by far thicker than that of earlywood tracheid in opposite wood and side wood and the S3 layer of secondary wall is lack in compression wood tracheid unlike opposite wood and side wood tracheid. 4. The tracheids in compression wood are often distorted at their tips unlike those in opposite wood and side wood and the bordered pit in compression wood tracheid is located at the bottom of helical groove unlike that in opposite wood and side wood tracheid. 5. The bordered pits in radial wall of opposite wood and side wood tracheids are oval in shape but those of compression wood tracheids show some modified oval shape. 6. In earlywood of side wood, the small apertures of cross-field pits are roundish triangle to rectangle and the large one are fenestriform through the coalition of two small ones. However, the small apertures of cross-field pits are upright oval and the large ones are procumbent oval shape in earlywood of opposite wood and the apertures of cross-field pits in compression wood are tilted bifacial convex lens shape in earlywood and slit in late wood because of the border on tracheid side.

• Restorative Dentistry and Endodontics
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• v.33 no.2
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• pp.148-161
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• 2008

The purpose of this study was to evaluate the effect of chlorhexidine (CHX) on microtensile bond strength (${\mu}TBS$) of dentin bonding systems. Dentin collagenolytic and gelatinolytic activities can be suppressed by protease inhibitors, indicating that MMPs (Matrix metalloproteinases) inhibition could be beneficial in the preservation of hybrid layers. Chlorhexidine (CHX) is known as an inhibitor of MMPs activity in vitro. The experiment was proceeded as follows: At first, flat occlusal surfaces were prepared on mid-coronal dentin of extracted third molars. GI (Glass Ionomer) group was treated with dentin conditioner, and then, applied with 2 % CHX. Both SM (Scotchbond Multipurpose) and SB (Single Bond) group were applied with CHX after acid-etched with 37% phosphoric acid. TS (Clearfil Tri-S) group was applied with CHX, and then, with adhesives. Hybrid composite Z-250 and resin-modified glass ionomer Fuji-II LC was built up on experimental dentin surfaces. Half of them were subjected to 10,000 thermocycle, while the others were tested immediately. With the resulting data, statistically two-way ANOVA was performed to assess the ${\mu}TBS$ before and after thermo cycling and the effect of CHX. All statistical tests were carried out at the 95 % level of confidence. The failure mode of the testing samples was observed under a scanning electron microscopy (SEM). Within limited results, the results of this study were as follows; 1. In all experimental groups applied with 2 % chlorhexidine, the microtensile bond strength increased, and thermo cycling decreased the micro tensile bond strength (P > 0.05). 2. Compared to the thermocycling groups without chlorhexidine, those with both thermocycling and chlorhexidine showed higher microtensile bond strength, and there was significant difference especially in GI and TS groups. 3. SEM analysis of failure mode distribution revealed the adhesive failure at hybrid layer in most of the specimen. and the shift of the failure site from bottom to top of the hybrid layer with chlorhexidine groups. 2 % chlorhexidine application after acid-etching proved to preserve the durability of the hybrid layer and microtensile bond strength of dentin bonding systems.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.100-112
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• 2005

Soil temperature was measured from the surface to 40 cm depth at three stations with different heights in tidal flat of Gomso Bay, west coast of Korea, for one month in every season 2004 to examine the thermal structure and the variation. Mean temperature in surface layer was higher in summer and lower in winter than in lower layer, reflecting the seasonal variation of vertically propagating structure of temperature by heating and cooling from the tidal flat surface. Standard deviation of temperature decreased from the surface to lower layer. Periodic variations of solar radiation energy and tide mainly caused short term variation of soil temperature, which was also intermittently influenced by precipitation and wind. Time series analysis showed the power spectral energy peaks at the periods of 24, 12 and 8 hours, and the strongest peak appeared at 24 hour period. These peaks can be interpreted as temperature waves forced by variations of solar radiation, diurnal tide and interaction of both variations, respectively. EOF analysis showed that the first and the second modes resolved 96% of variation of vertical temperature structure. The first mode was interpreted as the heating antl cooling from tidal flat surface and the second mode as the effect of phase lag produced by temperature wave propagation in the soil. The phase of heat transfer by 24 hour period wave, analyzed by cross spectrum, showed that mean phase difference of the temperature wave increased almost linearly with the soil depth. The time lags by the phase difference from surface to 10, 20 and 40cm were 3.2,6.5 and 9.8 hours, respectively. Vertical thermal diffusivity of temperature wave of 24 hour period was estimated using one dimensional thermal diffusion model. Average diffusivity over the soil depths and seasons resulted in $0.70{\times}10^{-6}m^2/s$ at the middle station and $0.57{\times}10^{-6}m^2/s$ at the lowest station. The depth-averaged diffusivity was large in spring and small in summer and the seasonal mean diffusivity vertically increased from 2 cm to 10 cm and decreased from 10 cm to 40 cm. Thermal propagation speeds were estimated by $8.75{\times}10^{-4}cm/s,\;3.8{\times}10{-4}cm/s,\;and\;1.7{\times}10^{-4}cm/s$ from 2 cm to 10 cm, 20 cm and 40 cm, respectively, indicating the speed reduction with depth increasing from the surface.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.427-430
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• 2001

We prepared 10cm-diameter Si(100)/500 $\AA$-Si$_3$N$_4$/Si(100) wafer Pairs adopting 500 $\AA$ -thick Si$_3$N$_4$layer as insulating layer between single crystal Si wafers. Si3N, is superior to conventional SiO$_2$ in insulating. We premated a p-type(100) Si wafer and 500 $\AA$ -thick LPCVD Si$_3$N$_4$∥Si (100) wafer in a class 100 clean room. The cremated wafers are separated in two groups. One group is treated to have hydrophobic surface and the other to have hydrophilic. We employed a FLA(fast linear annealing) bonder to enhance the bond strength of cremated wafers at the scan velocity of 0.1mm/sec with varying the heat input at the range of 400~1125W. We measured bonded area using a infrared camera and bonding strength by the razor blade crack opening method. We used high resolution transmission electron microscopy(HRTEM) to probe cross sectional view of bonded wafers. The bonded area of two groups was about 75%. The bonding strength of samples which have hydrophobic surface increased with heat input up to 1577mJ/$m^2$ However, bonding strength of samples which have hydrophilic surface was above 2000mJ/$m^2$regardless of heat input. The HRTEM results showed that the hydrophilic samples have about 25 $\AA$ -thick SiO layer between Si and Si$_3$N$_4$/Si and that maybe lead to increase of bonding strength.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.310-321
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• 1999

In this in vitro study, confocal laser scanning microscopic morphology of dentin-resin interface and its relationship to shear bond strength were investigated after the exposed dentin surfaces were treated with 3 different kinds of dentin adhesive systems[three-step; Scotchbond Multi-Purpose Plus(SMPP), self-priming bonding resin; Single Bond(SB), self-etching primer; Clearfil Liner Bond 2(LB2)]. 52 extracted human molar teeth without caries and/or restorations. The experimental teeth were randomly divided into three groups of seventeen teeth each. In five teeth of each group, class V cavities(depth: 1.5mm) with 900 cavosurface angles were prepared at the cementoenamel junction on buccal and lingual surfaces. Bonding resins of each dentin adhesive system were mixed with rhodamine B. Primer of SMPP was mixed with fluorescein. In group 1. the exposed dentin was conditioned with etchant, applied with above primer and bonding resin of SMPP. In group 2, with etchant and self-priming bonding agent of SB. In group 3, with self-etching primer and bonding agent of LB2. After treatment with dentin adhesive systems, composite resin were applied and photocured. The experimental teeth were cut longitudinally through the center line of restoration and grounded so that about $90{\mu}m$-thick wafers of buccolingually orientated dentin were obtained. And, $70{\sim}80{\mu}m$-thick wafers sectioned horizontally, thus presenting a dentinal tubules at 900 to the cut surface of a remaining tooth, were obtained. Primer of SMPP mixed with rhodamine B was applied to these wafers. Confocal laser scanning microscopic investigations of these wafers were done within of 24 hours after treatment. To measure shear bond strength, the remaining twelve teeth of each group were grounded horizontally below the dentinoenamel junction, so that no enamel remained. After applying dentin adhesive systems on the dentin surface, composite was applied in the shape of cylinder. The cylinder was 5mm in diameter, and 2mm in thickness. Shear bond strength was measured using Instron with a cross-head speed of 0.5mm/min. It was concluded as follows ; 1. Hybrid layer of SMPP(mean: $4.56{\mu}m$) was thicker than that of any other groups. This value was not statistically significant thicker than that of SB(mean: $3.41{\mu}m$, p>0.05), and significant thicker than that of LB2(mean: $1.56{\mu}m$, p<0.05). There was a statistical difference between SB and LB2(p<0.05). 2. Although there were variations in the length of resin tag even in a sample, and in a group, most samples in SMPP and SB showed resin tags extending above $20{\mu}m$. But samples in LB2 showed resin tags of $10{\mu}m$ at best. 3. Besides primer's infiltration into demineralized peritubular dentin and dentinal tubules, fluorophore of primer was detected in the lateral branches of dentinal tubules. 4. All groups demonstrated statistically significant differences from one another(p<0.05), with shear bond strengths given in descending order as follows: SMPP(18.3MPa), SB(16.0MPa) and LB2(12.4MPa). 5. LB2 having thinnest hybrid layer($1.56{\mu}m$) showed the lowest shear bond strength(12.4MPa).

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.141-161
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• 1998

The depth and patterns of demineralization according to the difference in concentration and application time of phosphoric acid were observed through the transmission electron microscope, and shear bond strengths to the acid -conditioned dentin were then measured and compared with the TEM results. To investigate the influence of polymer addition into the phosphoric acid and the effect of difference in concentration and application time of the acid, the specimens were randomly divided into 9 groups. Among the specimens, the exposed dentin surfaces were acid-conditioned with 10% polymer-thickened phosphoric acid(All Bond 2, Bisco, U.S.A.) and aqueous 10%, 20%, 30%, 40% phosphoric acid for 20 seconds, The rest of the specimens were acid-conditioned with 10% phosphoric acid for 15s, 30s, 60s, 120s respectively. The specimens were immersed in 4% glutaraldehyde in 0.1M sodium cacodylate buffer and postfixed with 1 % osmium tetroxide without decalcification and then observed under a JEOL Transmission Electron Microscope(JEM 1200 EX II, Japan). After the specimens were acid-conditioned as the above, primer and adhesive resin were applied to blot-dried dentin and shear bond strengths were then measured and analysed. The results were as follows : 1. The intertubular demineralization depth of 4.0-$5.0{\mu}m$ in 10% polymer-thickened phosphoric acid gels was similar or slightly deeper than that of 4.0-$4.5{\mu}m$ in aqueous 10% phosphoric acid solution. 2. The intertubular demineralization depth of aqueous 20%, 30% and 40% phosphoric acid solution was 6.5-$7.0{\mu}m$, 6.5-$7.5{\mu}m$ and 9.0-$15.0{\mu}m$ respectively. It showed that the depth of dentin demineralization is partly related to the concentration of phosphoric acid solution. 3. The intertubular demineralization depth of aqueous 10% phosphoric acid solution in application time for 15s, 30s, 60s and 120s was 2.5-$3.0{\mu}m$, 4.0-$6.0{\mu}m$, 6.5-$7.0{\mu}m$ and 8.5-$14.0{\mu}m$ respectively. It showed that the depth of dentin demineralization is directly related to the application time of phosphoric acid solution. 4. The partially demineralized dentin layer between demineralized collagen layer and unaffected dentin was showed to a width of 0.5-$1.0{\mu}m$ in lower concentration groups treated with aqueous 10% phosphoric acid for 20s, 60s, 120s and 20% phosphoric acid for 20s. 5. The demineralization effect at the border of intertubular-peritubular junction was less evident than that in the peritubular and intertubular dentin. The collagen fibers in the intertubular dentin had a random orientation, whereas those that lined the tubules were circumferentially aligned. The cross-linkage of dentinal collagen in demineralized collagen layer was clearly seen. 6. A statistically significant difference of bond strengths according to the difference in phosphoric acid concentration did not exist among the groups treated with 10%, 20%, 30% and 40% acid solution (P>0.05). However, bond strengths to the treated dentin with 10% phosphoric acid solution for 30s were significantly higher than that for 120s (P<0.05).

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.4
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• pp.357-362
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• 2011

Purpose: The narrow-band pass color-filters with a 500 nm central wavelength and 12 nm FWHM using $Ti_3O_5/SiO_2$ mutilayer were fabricated, and their characteristics and structures were studied. Methods: the optical constants, n and k, of the $Ti_3O_5$ and $SiO_2$ thin films were obtained from the transmittances of their thin film. The narrow-band pass color-filters were designed with these optical constants and the AR coating of the filter was also designed. $Ti_3O_5/SiO_2$ multilayer filters were made by electron beam evaporation apparatus and the transmittaces of the filters were measured by spectrophotometer. the number of layers and the thicknesses of filters were calculated from the cross section of filters by SEM image and the composition of filters was analysed by XPS analysis. Results: The optimization of AR coating for the narrow-band pass color-filter was [air$|SiO_2(90)|Ti_3O_5(36)|SiO_2(5)|Ti_3O_5(73)|SiO_2(30)|Ti_3O_5(15)|$ glass], and the optimization of filter layer for the color filter was [air$|SiO_2(192)|Ti_3O_5(64)|SiO_2(102)|Ti_3O_5(66)|SiO_2(112)|Ti_3O_5(74)|SiO_2(120)|Ti_3O_5(68)|SiO_2(123)|Ti_3O_5(80)|SiO_2(109)|Ti_3O_5(70)|SiO_2(105)|Ti_3O_5(62)|SiO_2(99)|Ti_3O_5(63)|SiO_2(98)|Ti_3O_5(51)|SiO_2(60)|Ti_3O_5(42)|SiO_2(113)|Ti_3O_5(88)|SiO_2(116)|Ti_3O_5(68)|SiO_2(89)|Ti_3O_5(49)|SiO_2(77)|Ti_3O_5(48)|SiO_2(84)|Ti_3O_5(51)|SiO_2(85)|Ti_3O_5(48)|SiO_2(59)|Ti_3O_5(34)|SiO_2(71)|Ti_3O_5(44)|SiO_2(65)|Ti_3O_5(45)|SiO_2(81)|Ti_3O_5(52)|SiO_2(88)|$ glass]. It was known that the color-filters fabricated by the simulation data were composed of 41 layers by SEM image and the top layer of filters was $SiO_2$ layer and the filters were composed of $SiO_2$/$Ti_3O_5$ multilayer by XPS analysis. It was also known that the mixed thin film of TiO2 and $Ti_3O_5$ was made during the deposition of the $Ti_3O_5$ material. Conclusions: The narrow-band pass color-filters with a 500 nm central wavelength and 12 nm FWHM using $Ti_3O_5/SiO_2$ mutilayer of 41 layer were fabricated, and it was known that the mixed form of TiO2 and $Ti_3O_5$ thin film was made during the deposition of the $Ti_3O_5$ material.

• Journal of Sericultural and Entomological Science
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• v.27 no.2
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• pp.7-19
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• 1985

The genetic variances and combinding ability of some useful characters were analyzd on sixty four combinations in the 8$\times$8 diallel cross using the four Japanese races(Jam 107, Jam 113, Jam 117 and Jam 119) and the four Chinese races(Jam 108, Jam 114, Jam 118 and Jam 120). The eight quantitative characters were the total larval stage period(TP), the fifth larval instar period(FP), the female cocoon total weight(FW), the male cocoon total weight(MW), the female cocoon layer weight(FL), the male cocoon layer weight(ML), the female cocoon layer ratio(FR), and the male cocoon layer ratio(MR). The results were as follows: The analysis of the genetic variance and the combining ability in the TP and the FP. In TP and FP, h2N was less than h2B. The GCA, SCA and RCA were at a high significant level. Hl/D and (Hl/D)1/2 ere large. The heterosis were small minus. E and D were large. The r was in the positive direction, because the recessive genes were mainly expressed as a short rearing periods. The regressions of the characters were passed below 0 point, because the characters in the TP and the FP were appeared overdominant. The order of the dominance in the TP of the parents were in the order of Jam 119>Jam 113>Jam 117>Jam 108>Jam 120>Jam 114>Jam 107>Jam 118, and that in the FP of the parents were followed in the orders of Jam 117>Jam 113>Jam 108>Jam 114>Jam 119>Jam 107>Jam 120>Jam 118. The analysis of the genetic variance and the combining ability of the FW and the MW. In the FW and the Mw, h2N was less the h2B. The GCA and SCA were large but RCA was little. Hl/D and (Hl/D)1/2 in the parents were large. Heterosis was large. E was appeared large in the FW, and small in the MW. D was small. The r was of the minus direction, because the dominance genes were less expressed. The regression of the these characters were padded below 0 point, because the characters in FW and MW were appeared overdominant. The orders of the dominance in the FW of the parents were as the order of Jam 107>Jam 108>Jam 119>Jam 113>Jam 114>Jam 120>Jam 117>Jam 118, and in the MW of them in the order of Jam 114>Jam 120>Jam 108>Jam 113>Jam 107>Jam 119>Jam 117>Jam 118. The analysis of the genetic variance and the combining ability of the FL and ML. In the FL and the ML, h2N was less than h2B. GCA and SCA were large. RCA was little. Hl/D and (Hl/D)1/2 ere large. Heterosis was large. The r was in the negative direction, because the dominance genes were less expressed. The regression of the characters of FL and ML were appeared overdominant. The dominance in the FL of parents ere in the order of Jam 120>Jam 114>Jam 119>Jam 119>Jam 118>Jam 107>Jam 117>Jam 113, and the ML of them in the order of Jam 114>Jam 108>Jam 120>Jam 117>Jam 118>Jam 107>Jam 119>Jam 113. The analysis of the genetic variance and combining ability of the FR and the MR. In the FR and the Mr, h2N was less than h2B. GCA was large. The SCA and RCA were little. In the FW, Hl/D was large but (Hl/D)1/2 was a little. In MR, Hl/D and (Hl/D)1/2 both were a littel. Heterosis was a little. E in the FR was in the negative direction, because the dominance genes were less expressed but that in the MR was the positive direction because the recessive genes were mainly expressed. The order of the dominance in the FR of the parents were in the order of Jam 117>Jam 114>Jam 108>Jam 120>Jam 118>Jam 119>Jam 107>Jam 113 and that in the MR these were in the order of Jam 114>Jam 117>Jam 108>Jam 118>Jam 107>Jam 119>Jam 120.