• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.503-511
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• 1998

In this study, the stress distribution for different tibial components was observed In order to Investigate the load transfer and potential failure mechanism of the tibial components subjected to dynamic impact loading and also to evacuate the effect of bone-implant bonding conditions on the implant system. The 3-dimensional finite element models included an intact tibia, cemented metal-backed tibial component, uncemented metal-blocked tibial component, cemented all-polyethylene tibial component, and metal-backed component with a debonded bone/stem interface. The results showed that the cemented metal-hocked component Induced slightly higher peak stress at stem tip than the uncemented component. The peak stress of the all-polyethylene tibia1 component at stem trip showed about half thats of metal-backed tibial components. The all-polyethylene component showed a similar dynamic response to intact tibia. In case of debonded bone/stem interface, the peak stress below the metal tray was three times Higher than that of the fully bonded interface and unstable stress distribution at the stem tip was observed with time, which causes another adverse bone apposition and implant loosening. Thus, the all-polyethylene tibial component bonded fully to the surrounding bone might be most desirable system under an impact loading.

• Journal of Biomedical Engineering Research
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• v.27 no.6
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• pp.418-426
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• 2006

In the artificial heart application, productivity and hemodynamic properties of artificial heart valves are crucial in successiful application to long term in vivo trials. This paper is about manufacture and assessment of trileaflet polymer heart valves using vacuum forming process(VFP). The VFP has many advantages such as reduced fabrication time, reproducibility due to relatively easy and simple process for manufacturing. Prior to VFP of trileaflet polymer heart valves, polyurethane(Pellethane 2363 80AE, Dow Chemical) sheet was prepared by extrusion. The sheets were heated and formed to mold shape by vacuum pressure. The vacuum formed trileaflet polymer heart valves fabrication is composed of two step method, first, leaflet forming and second, conduit forming. This two-step forming process made the leaflet-conduit bonding stable with any organic solvents. Hydrodynamic properties and hemocompatibility of the vacuum formed trileaflet polymer heart valves was compared with sorin bicarbon bileaflet heart valve. The percent effective orifice area of vacuum formed trileaflet polymer heart valves was inferior to bileaflet heart valve, but the increase of plasma free hemoglobin level which reflect blood damage was superior in vacuum formed trileaflet polymer heart valves Vacuum formed trileaflet polymer heart valves has high productivity, and superior hemodynamic property than bileaflet heart valves. Low manufacturing cost and blood compatible trileaflet polymer heart valves shows the advantages of vacuum forming process, and these results give feasibility in in vivo animal trials in near future, and the clinical artificial heart development program.

• Tunnel and Underground Space
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• v.22 no.1
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• pp.69-76
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• 2012

Theoretical backgrounds on the experimental methods of explosive welding, explosive forming and shock consolidation of powders are introduced. Explosive welding experiments of titanium (Ti) and stainless steel (SUS 304) plate were carried out. It was revealed that a series of waves of metal jet are generated in the contact surface between both materials; and that the optimal collision velocity and collision angle is about 2,100~2,800 m/s and $15{\sim}20^{\circ}$, respectively. Also, explosive forming experiments of Al plate were performed and compared to a conventional press forming method. The results confirmed that the shock-loaded Al plate has a larger curvature deformation than those made using conventional press forming. For shock consolidation of powders, the propagation behaviors of a detonation wave and underwater shock wave generated by explosion of an explosive are investigated by means of numerical calculation. The results revealed that the generation and convergence of reflected waves occur at the wall and center position of water column, and also the peak pressure of the converged reflected waves was 20 GPa which exceeds the detonation pressure. As results from the consolidation experiments of metal/ceramic powders ($Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$), shock-consolidated $Fe_{11.2}La_2O_3Co_{0.7}Si_{1.1}$ bulk without cracks was successfully obtained by adapting the suggested water container and strong bonding between powder particles was confirmed through microscopic observations.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.98-103
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• 2013

In this work, we investigated the enhanced performance of IZO-based TFTs with $HfSiO_x$ gate insulators. Four types of $HfSiO_x$ gate insulators using different diposition powers were deposited by co-sputtering $HfO_2$ and Si target. To simplify the processing sequences, all of the layers composing of TFTs were deposited by rf-magnetron sputtering method using patterned shadow-masks without any intentional heating of substrate and subsequent thermal annealing. The four different $HfSiO_x$ structural properties were investigated x-ray diffraction(XRD), atomic force microscopy(AFM) and also analyzed the electrical characteristics. There were some noticeable differences depending on the composition of the $HfO_2$ and Si combination. The TFT based on $HfSiO_x$ gate insulator with $HfO_2$(100W)-Si(100W) showed the best results with a field effect mobility of 2.0[$cm^2/V{\cdot}s$], a threshold voltage of -0.5[V], an on/off ratio of 5.89E+05 and RMS of 0.26[nm]. This show that the composition of the $HfO_2$ and Si is an important factor in an $HfSiO_x$ insulator. In addition, the effective bonding of $HfO_2$ and Si reduced the defects in the insulator bulk and also improved the interface quality between the channel and the gate insulator.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3348-3354
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• 2011

Oleanolic acid (OA) as template molecule, polyamide-6 (PA6) as basement membrane and poly(styrene-comaleic acid) (PSMA) were used to prepare PA6/PSMA-OA molecularly imprinted composite membranes by phase inversion method in supercritical $CO_2$ ($ScCO_2$). The template molecule (OA), [poly(styrene-co-maleic anhydride) (PSMAH), PSMA, molecularly imprinted membranes (MIMs) imprinting OA and MIMs after elution were all characterized by Fourier transform infrared spectroscopy (FTIR). The conditions that were the mass ratio between PSMA and OA from 3:1 to 8:1, temperature of $ScCO_2$ from $35^{\circ}C$ to $50^{\circ}C$ and pressure of $ScCO_2$ 12 MPa to 17 MPa were studied. It was obtained the largest adsorption rate and purity of OA after adsorption of the resultant MIMs, 50.41% and 96.15% respectively. After using PA6 film and non-woven fabrics as basement membrane respectively, it was found that smaller aperture of PA6 was used as basement membrane, a higher adsorption rate and a higher purity of OA after adsorption of the MIMs were obtained, and so were the stability and reproducibility of the resultant MIMs. After template molecules being removed, the MIMs had effective selectivity hydrogen bonding to separately bind in the binary components to the template molecules-oleanolic acid.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.125-136
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• 2006

Statement of problem. The success of the bonding between electroforming gold and resin is dependent on the surface-conditioning technique but its effective technique has net been studied widely. Purpose. The purpose of the study was to evaluate the bond strength between the electroforming gold and resin with varying the surface-conditioning technique. Materials and methods. Sixty rectangular shaped metal specimens were made and one side of each specimen were gold hard plated. The sand-blasted specimens were divided into four experimental groups with fifteen specimens in each group and were treated as follows. Group 1: Silicoating (Rocatec, 3M ESPE)+ Sinfony (3M ESPE), Group 2: SR Link+ SR Adoro (Ivoclar Vivadent), Group 3: Tin plating (Microtin, Danville Engineering)+ SR Link+ SR Adoro, Group 4: Tin plating (Micro tin, Danville Engineering)+ Silicoating (Rocatec)+ Sinfony. Shear bond strength at metal-resin interface were measured using universal testing machine. Energy Dispersive x-ray analysis was done and scanning electron microscope images were taken and observed. Results and Conclusion. The following conclusions were drawn. 1. The mean shear bond strength values in order were 11.69MPa (Group 2), 22.35MPa (Group 3), 22.40MPa (Group 1) and 27.71MPa (Group 4). There was no significant difference in Group 1, Group 3 and Group 4(P>0.05). 2. In the EDX line analysis, the Au was detected on the surface of all specimen. $SnO_2$ showed on the surface of Group 2 and $SiO_2$ was detected on the surface of Group 1. 3. Increasing of roughness by sandblasting(Group 2), formation of micro-irregularities and tin crystals by electrolytic tin plating(Group 3) and formation of surface irregularities and $SiO_2$ layer(Group 1,4) were observed in SEM photo. 4. Tin plating(Group 3) and Rocatec treatment(Group 1) showed clinically effective shear bond strength(>20MPa), but when the two surface conditioning method were used together higher bond strength were achieved.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.3
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• pp.253-265
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• 2011

When restoring endodontically treated teeth is the mismatch between fiber post size and post space diameter, the resin cement layer is excessively thick in post space and voids are likely to form in it, thus predisposing to de-bonding. The method to overcome this problem is to reline the fiber post with composite resin. This individual anatomic post improves the adaptation of post to root walls and decreases the resin cement thickness. The purpose of this in vivo study was to evaluate the push-out bond strength of fiber post according to relining procedure and luting agents type used for simplicity of clinical procedure. Forty-two extracted teeth were divides into six groups.(n=7) A1: relined fiber post cemented with Luxacore/all-bons 2, A2: non-relined fiber post cemented with Luxacore/all-bond2, B1: relinind fiber post cemented with Calibra/XP-bond, B2: non-relined fiber post cemented with Calibra/XP-bond, C1: relined fiber post cemented with RelyX Unicem, C2: non-relined fiber post cemented with RelyX Unicem Push-out bond strength was affected by interaction between relining procedure and luting agent type. Relined fiber post presented higher push-out bond strength value than non-relined fiber post and statically significant differences(p<0.05) Cementation with RelyX Unicem showed significantly higher bond strength than other luting agents(p<0.05).

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.341-349
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• 2017

Blood decontamination is an important factor in success of the orthodontic bracket. The purpose of this study is to evaluate the shear bond strength affected by blood decontamination. The shear bond strength was measured on blood decontamination before and after primer photopolymerization. And the adhesive remnants type and surface patterns was evaluated under scanning electron microscopy. A total of 50 human premolars were prepared. Group I was attached using conventional resin-acid etching method as control group. Group II and III were blood contaminated before curing primer and groups IV and V were blood contaminated after curing primer. Group II and IV were treated only with cotton pellet and Groups III and V were treated with cotton pellet after water washing. The mean shear bond strengths were in the order of groups I, V, III, II, and IV. In scanning electron micrographs group III and V showed more uniform surface than group II and IV. The ARI was significantly different between the control group and the experimental groups (p <0.05).

• Women's Health Nursing
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• v.6 no.2
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• pp.269-290
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• 2000

This study was conducted to inquire about the view on childrearing of university women for the purpose of building up the positive parent- child relationship and setting up preliminary parenting education program. The subjects were 137 university women who were freshmen to junior in one women's university in Seoul. Using the self-report questionnaire, data were collected from December in 1998 to March in 1999 and the contents which subjects wrote down were categorized by content analysis method. The results were as followed: 1. The age range of subjects were 20-22 years and main rearer was her mother(71.5%) 2. The view of subjects were revealed by 374 statements and then tied together 34 themes: 'exemplary parent model as a guider'(8.6%), 'determination for oneself' (8.0%), 'expression of love'(6.2%), 'humanity education'(4.8%), 'carrot and stick'(4.5%), 'respect of personality'(4.3%), 'sound living habit'(4.1%), 'conversation'(3.7%), 'regulation of greediness' (3.7%), 'supply of live experience'(3.7%), 'supply of broad and substantial vision'(3.5%), 'free choice'(3.5%), 'broad-mindedness'(3.5%), 'consideration'(3.0%), 'doing together'(3.0%), 'propriety education' (2.4%), 'pursuit of naturalness'(2.4%), 'looking for one's life'(2.4%), 'confidence'(2.1%), 'rearing by oneself'(2.1%), 'encouragement'(2.1%), 'cultivation of right sexual senses'(2.1%), 'desirable home environment'(1.9%), 'doing one's best'(1.9%), 'understanding'(1.6%), 'psychological intimacy'(1.6%), 'treat fair'(1.6%), 'pursuit of physical, psychological health' (1.6%), 'concerning'(1.3%), 'religious life'(1.3%), 'respect of individuality'(1.3%), 'cooperation' (1.1%), 'often-minded family'(0.8%), 'positive attitude'(0.8%). 34 themes were categorized by 12 categories once more: 'mature parenthood'(15.5%), 'acceptance' (11.5%), 'autonomy'(11.5%), 'pursuit of healthy life style'(9.4%), 'eagerness'(9.1%), 'making efforts'(8.8%), 'education'(8.8%), 'emotional bonding' (7.8%), 'respect'(7.2%), 'corporal punishment' (4.5%), 'supporting'(3.2%), 'composition of environment'(2.7%). In conclusion, we could expect that university women had a democratic view on childrearing with love and autonomy for a base. So we need to offer them nursing implementations such as preliminary parenting programs and parenting consulting in order to promote positive and interactional parent-child relationship by strengthening their desirable view on childrearing.

• Journal of the Korean Magnetics Society
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• v.3 no.2
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• pp.94-100
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• 1993

Electronic and magnetic properties of the novel rare-earth permanent magnet, $Sm_{2}Fe_{17}N_{3}$, are investigated by performing self-consistent local density functional electronic structure calculations. Employing the LMTO(Linearized Muffin-Tin Orbital) band method, we have obtained the electronic band structures for both paramag-netic and ferromagnetic phases of $Sm_{2}Fe_{17}N_{3}$. Based on the energy band structures, we have studied bonding ef-fects among Sm, Fe, and N atom as well as electronic and magnetic structures. It is found that the N atom sub-stantially reduces the magnetic moment of neighboring Fe atoms through the hybridization interaction and also plays a role in stabilizing the structure. the average magnetic moment of Fe atoms in the ferromagnetic phase of $Sm_{2}Fe_{17}N_{3}$ is estimated to be $2.33{\mu}_B$, which is ~8% larger than the magnetic moment of $Sm_{2}Fe_{17}$, $2.16{\mu}_B$. The Fe I (c) atom, which is located farthest from the N atom and surrounded by 12 Fe nearest neighbors, has the largest magnetic moment ($2.65{\mu}_B$), while the Fe III (f), whose hybridization interaction with N atom is very strong, has the smallest magnetic moment($1.96{\mu}_B$).