• Polymer(Korea)
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• v.37 no.1
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• pp.86-93
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• 2013

In this work, the thermal, antibiotic properties and far-infrared emissivity of fluorinated illite embedded polypropylene non-woven fibers (f-illite/PP fibers) were investigated in the presence of 0, 1, 3, 5 and 7 wt% illite powders. The thermal properties of f-illite/PP fibers were studied by thermogravimetric analysis (TGA). Their antibiotic properties were examined by Staphylococcus aureus and Klebsiella pneumoniae test. Their far-infrared emissivity was also investigated by Fourier transform infrared spectroscopy. From the experimental results, thermal, antibiotic properties and far-infrared emissivity of f-illite/PP fibers were improved by increasing fluorinated illite contents and the property values of 5 wt% f-illite/PP fibers were increased remarkably by about 10.3, 41.2 and 9.8% respectively in comparison with PP non-woven fibers having no fluorinated illite additive. This result was interpreted as the development of interfacial adhesion force between the polymer chains due to the fluorination of illite power.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.293-301
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• 2017

A Sub-kWe small-scale experimental test loop was manufactured to investigate characteristics of the supercritical carbon dioxide power cycle. A high-speed turbo-generator was also designed and manufactured. The designed rotational speed of this turbo-generator was 200,000 rpm. Because of the low expansion ratio through the turbine and low mass flowrate, the rotational speed of the turbo-generator was high. Therefore, it was difficult to select the rotating parts and design the turbine wheel, axial force balance and rotor dynamics in the lab-scale experimental test loop. Using only one channel of the nozzle, the partial admission method was adapted to reduce the rotational speed of the rotor. This was the world's first approach to the supercritical carbon dioxide turbo-generator. A cold-run test using nitrogen gas under an atmospheric condition was conducted to observe the effect of the partial admission nozzle on the rotor dynamics. The vibration level of the rotor was obtained using a gap sensor, and the results showed that the effect of the partial admission nozzle on the rotor dynamics was allowable.

• Polymer(Korea)
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• v.39 no.1
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• pp.88-98
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• 2015

4-Amino-N-hexadecylbenzamide-graphene sheets (AHB-GSs), used in the preparation of the polyimide (PI) nanocomposite films, were synthesized by mixing a dispersion of graphite oxide with a solution of the ammonium salt of AHB. The atomic force microscope image of functionalized-GS on mica and a profile plot revealed the average thickness of AHB-GS to be ~3.21 nm. PI films were synthesized by reacting 4,4'-biphthalic anhydride and bis(4-aminophenyl) sulfide. PI nanocomposite films containing various contents of AHB-GS over the range of 0-10 wt% were synthesized using the solution intercalation method. The PI nanocomposite films under different thermal imidization temperatures, 250 and $350^{\circ}C$, were examined. The graphenes, for the most part, were well dispersed in the polymer matrix despite some agglomeration. However, micrometer-scale particles were not detected. The average thickness of the particles was <10 nm, as revealed from the transmission electron microscope images. Only a small amount of AHB-GS was required to improve the gas barrier, and electrical conductivity. In contrast, the glass transition and initial decomposition temperatures of the PI hybrid films continued to decrease with increasing content of AHB-GS up to 10 wt%. In general, the properties of the PI hybrid films heat treated at $350^{\circ}C$ were better than those of films heat treated at $250^{\circ}C$.

• The korean journal of orthodontics
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• v.28 no.1 s.66
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• pp.29-41
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• 1998

Despite orthodontic treatment(tooth moving) is dynamic act many orthodontists have used mainly static evaluation method for evaluating effectiveness of the orthodontic appliances. They want to find which is better appliance, especially in the treatment results and treatment period when they chose one appliance from sugessted appliances for obtaining same treatment goal. The author and colleagues invented and manufactured new machine for getting information about the relative effectiveness from many suggested orthodontic appliances and we named it Calorific machine. We used this Calorinc machine to find the relative differences about tooth moving mechanism and tooth moving time between the Burstone's PLA(single force mechanism) and Molar-up's PLA(couple mechanism) for correcting the posterior cross bite. We measured the distance of tooth moving on the occlusal X-ray film and recorded the moving time of the anchored(control elctro-thermal tooth) and lingually tipped lower second molars(experimental electro-thermal tooth) and then processed paired t-est by SAS program. The results were as follows. 1. Molar-up's PLA showed more extrusive and horizontal movement than Burstone's PLA at the lingually tipped molar(p=0.0000). 2. There is no finding of tooth movement by Molar-up's PLA at the uprighted molar(p=o.3475) but Burstone's PLA showed a little change(0.2 m) at the same molar(p=0.0001). 3. Burstone's PLA took 17.8 minutes for tooth moving but Molar-up's PLA took only 3.8 minutes(p=0.0001)

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1026-1029
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• 2005

The feasibility of graphoepitaxial growth of compound semiconductors has been studied. Two kinds of substrates were prepared; one is smooth substrate, the other one is a periodic structured substrate. ZnO film was formed on both substrates by thermal evaporation of elemental Zn and natural oxidation of the deposited Zn. Thermal treatment was performed to improve the crystal quality and to investigate the effect of the periodic structure. Atomic force microscopy (AFM) and photoluminescence (PL) were used to characterize the samples. As a result, the improvement of crystallinity as annealing temperature increase, has been observed from both samples. The samples, annealed at 800 $^{\circ}$C, show the best crystal quality in terms of PL linewidth. Also the sample grown on grating structure shows better crystal quality than the sample grown on flat substrate. It implies that the periodic structure affects the crystallinity of the films, and the graphoepitaxy of compound semiconductors is possible by using appropriate surface structure.

• Steel and Composite Structures
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• v.26 no.2
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• pp.227-239
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• 2018

Integral abutment bridges (IABs) have no joint across the length of bridge and are therefore also known as jointless bridges. IABs have many advantages, such as structural integrity, efficiency, and stability. More importantly, IABs have proven to be have both low maintenance and construction costs. However, due to the restraints at both ends of the girder due to the absence of a gap (joint), special design considerations are required. For example, while replacing the deck slabs to extend the service life of the IAB, the buckling strength of the steel girder without a deck slab could be much smaller than the case with deck slab in place. With no deck slab, the addition of thermal expansion in the steel girders generates passive earth pressure from the abutment and if the applied axial force is greater than the buckling strength of the steel girders, buckling failure can occur. In this study, numerical simulations were performed to estimate the buckling strength of typical steel girders in IABs. The effects of girder length, the width of flange and thickness of flange, imperfection due to fabrication and construction errors on the buckling strengths of multiple and single girders in IABs are studied. The effect of girder spacing, span length ratio (for a three span girder) and self-weight effects on the buckling strength are also studied. For estimation of the reaction force of the abutment generated by the passive earth pressure of the soil, BA 42/96 (2003), PennDOT DM4 (2015) and the LTI proposed equations (2009) were used and the results obtained are compared with the buckling strength of the steel girders. Using the selected design equations and the results obtained from the numerical analysis, equations for preventing the buckling failure of steel girders during deck replacement for maintenance are presented.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.3
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• pp.51-56
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• 2016

The most widely used glue in a corrugator is starch, which is a natural polymer. This material needs thermal energy to achieve a binding force, so a heating section is installed in a corrugator. However, this heating section can cause quality problems in linerboards and corrugating medium and increase the production cost because of the high cost of fossil resources. Therefore, a new adhesive that provides the binding force at lower temperatures than the conventional one must be developed. In this study, SB-latex was selected as a co-adhesive and added to the starch solution. The addition of the SB-latex was determined based on the viscosity of the new adhesive. The adhesive strength and the drying energy reduction of a corrugated board were measured to evaluate the functionalities of the new adhesive. The addition of SB-latex was determined to be under 20% of the oven-dried starch based on the viscosity of the new adhesive. The adhesive strength was improved and the drying energy was reduced by applying the new adhesive.

• Archives of Pharmacal Research
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• v.28 no.6
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• pp.736-742
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• 2005

Xyloglucan (XG), which exhibits thermal sol to gel transition, non-toxicity, and low gelation concentration, is of interest in the development of sustained release carriers for drug delivery. Drug-loaded XG beads were prepared by extruding dropwise a dispersion of indomethacin in aqueous XG solution (2 wt.-$\%$) through a syringe into corn oil. Enteric coating of XG bead was performed using Eudragit L 100 to improve the stability of XG bead in gastrointestinal (GI) track and to achieve gastroresistant drug release. Release behavior of indomethacin from XG beads in vitro was investigated as a function of loading content of drug, pH of release medium, and concentration of coating agent. Adhesive force of XG was also measured using the tensile test. Uniform-sized spherical beads with particle diameters ranging from 692 $\pm$ 30 to 819 $\pm$ 50 $\mu$m were obtained. The effect of drug content on the release of indomethacin from XG beads depended on the medium pH. Release of indomethacin from XG beads was retarded by coating with Eudragit and increased rapidly with the change in medium pH from 1.2 to 7.4. Adhesive force of XG was stronger than that of Carbopol 943 P, a well-known commercial mucoadhesive polymer, in wet state. Results indicate the enteric-coated XG beads may be suitable as a carrier for oral drug delivery of irritant drug in the stomach.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.269-276
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• 2009

South Korea having military power within the $10^{th}$ in world ranking is the biggest single institution among public institutions in Korea and comprises force of over seven hundred thousand soldiers. However, outworn equipments and efficiency problem have issued. So, this study is to search the distribution state of new-renewable energy and to analyze application plan on the basis of interview with a official in charge in military. Analysis process is the first, classify surveyed military facilities into troops and the geographical factor. Second, classify a scale and type of facilities that new-renewable energy is supplied. Third, find consideration facts on the basis of interview with a official in charge. On the results of the survey, new-renewable energy applied to the military facility is photovoltaic, solar heat, wind power and geo-thermal energy. Also, divide military into the army, navy, air force and marine, visit 14 units and analyze the official's opinion. This study will deduce LCCA(Life cycle cost analysis) considered expenses for the installation and maintenance, and will be basic research that suggest an appropriate new-renewable energy model in military.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1031-1039
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• 2015

Present guided missiles are equipped with infrared seeker to find the infrared sources radiating from target plane and then chase, which results in an improvement of the hitting success rate when in striking target objects. To interrupt the chases from the guided missile, the target plane spreads the flare, avoiding the missile attracts. Our research is to develop a 2-color infrared identification technique to discern the flare and real thermal source from target plane. Considering flare radiation properties and EM atmosphere transmission rates, two channels were selected, in which main channel (MC) was in a range of 3.7 μm∼4.8 μm and auxiliary channel (AC) in 1.7 μm∼2.3 μm. A 2500K heat source was used for an artificial flare source, while a 570K heat source was utilized for airplane infrared source in experimental testing. Two infrared sensors detectable only at each chanel were employed in order to measure the voltage ratio from two channels, identifying the flare and real target plane via comparison the voltage ratio. Several experimental conditions were imported in order to prove that our proposed 2-color infrared identification technique is very efficient way to discern heat sources from aircraft and flare, demonstrating that our proposed technique is very promising means for our force’s InfraRed Counter Counter Measure (IRCCM) in order to countermeasure opposite force’s InfraRed Counter Measures (IRCM).