• Journal of Welding and Joining
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• v.32 no.2
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• pp.63-69
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• 2014

Dual laser heat sources were used for polymer based material joining. An infrared camera and thermocouple DAQ system were used to correlate the temperature distribution to computer simulation. A 50 degree tilted pre-heating laser source was acting as a heating source to promote the temperature to minimize thermal shock by the following a welding heat source. Based on the experimental result, the skin depth was empirically estimated for computer simulation. The offsets of 3mm, 5mm and 10mm split by weld and preheat were effectively used to control the temperature distribution for the optimal laser joining process. The closer offset resulted in an excessive melting or burning caused by sudden temperature rising. The laser power was split by 50%, 75% and 100% of the weld power, and the best results were found at 50% of preheating. To accurately simulate the physical laser beam absorption and joining optical properties were experimentally measured for the computer FEM simulation. The simulation results showed close correlation between theoretical and experimental results. The developed dual laser process is expected to increase productivity and minimize the cost for the final products.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.04a
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• pp.11-15
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• 1995

Polysulfone (PS) membranes were prepared by the phase inversion process using water or isopropanol as nonsolvent. The Flory-Huggins theory for a ternary system nonsolvent/solvent/polymer is applied to describe the thermodynamic equilibria of the components. The calculated ternary phase equilibria show that demixing of a PS binary solution with n-methylpyrrolidone (NMP) will be fast in a water coagulation bath and will be delayed in an isopropanol bath. The prepared membranes were characterized by SEM, gas adsorption-desorption measurement, and permeability test. The membrane, which is precipitated by fast demixing in a water bath, has nodular structures in the skin region and includes finger-like cavities in the sublayer. The membrane coagulated by isopropanol has a very dense and thick skin structure, which is formed by delayed demixing. The membrane coagulated by isopropanol showed considerably lower pore volume and surface area compared to that observed with water coagulation method. With dimethylformamide (DMF) as solvent and 2-3 wt% of water, the solution can show the liquid-liquid phase separation due to agglomation of the polymer-lean phase from the homogeneous solution. The membranes, which were coagulated near an equilibrium state, show the large (micron size) round pores in the whole membranes. The pores do not contribute the permeation characteristics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1083-1084
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• 2011

• Journal of the Korean Applied Science and Technology
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• v.31 no.3
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• pp.367-374
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• 2014

In this study, skin permeation enhancement was confirmed by designing it to have a structure and composition similarity to the intercellular lipids that improve miscibility with skin by cross-linked lipids poloxamer. The cross-linked lipids poloxamer was synthesized and analyzed by 1H NMR that structure dose had conjugated pluronic with ceramide3. Active component is released by modification of liquid crystal structure because PPO part, large-scale molecule block of pluronic, has hydrophobic nature at skin temperature of $35^{\circ}C$. Conjugated pluronic with ceramide3 was synthesized using Pluronic F127 and p-NPC (4-nitrophenyl chloroformate) at room temperature yielded 89%. Pluronic(Ceramide 3-conjugated Pluronic) was synthesized by reaction of p-NP-Pluronic with Ceramide3 and DMAP. The yield was 51%. This cross-linked lipids poloxamer was blended and dissolved at isotropic state with skin surface lipids, phospholipid, ceramide, cholesterol and anhydrous additive solvent. Next step was preceded by ${\alpha}$-Transition at low temperature for making the structure of Meso-Phase Lamella, and non-hydrous skin analogue liquid crystal using thermo-sensitivity smart sensor, lamellar liquid crystal structure through aging time. For confirmation of conjugation thermo-sensitivity smart sensor and non-hydrous skin analogue liquid crystal, structural observation and stability test were performed using XRD(Xray Diffraction), DSC(Differential Scanning Calorimetry), PM (Polarized Microscope) And C-SEM (Cryo-Scanning Electron Microscope). Thermo-sensitivity observation by Franz cell revealed that synthesized smart sensor shown skin permeation effect over 75% than normal liquid crystal. Furthermore, normal non-hydrous skin analogue liquid crystal that not applied smart sensor shown similar results below $35^{\circ}C$ of skin temperature, but its effects has increased more than 30% above $35^{\circ}C$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.295-298
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• 2004

Automobile door-handle is assembled with three parts that are base, skin and cover. Over-molding processing makes assembly of the base and skin. The skin part that was made by PVC polymer has various thickness. Plastic injection molding simulation of part including significant changed thickness as skin is an inaccuracy comparing with real injection molding. To solve this problem, two commercial flow prediction software that are Moldflow MPI and MAPS 3D were used in this study. Simulations were conducted for three types mesh. Taguchi method was applied for simulation experiments. It will be need to compare with simulation results and real over-molding behavior in the near future.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.2
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• pp.121-128
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• 2010

We investigated the effects of skin hydration and composition analysis of proteoglycan (chia seed polymer) produced from chia (Salvia hispanica) seed. The result showed that proteoglycan of chia seeds is composed of galactose (46.8 %), glucuronic acid (27.1 %), rhamnose (8.7 %), xylose (7.6 %), glucose (4.9 %), fructose (2.3 %), mannose (1.8 %), arabinose (0.9 %) and the amount of proteins contained is 31.3 mg/g with the constituent amino acid compositions (mg/g) of Asp (1.9), Glu (3.6), Ser (0.9), Gly (3.6), Thr (0.8), Arg (1.0), Ala (2.0), Tyr (0.4), Cys (4.8), Val (1.1), Phe (0.5), Ile (0.6), Leu (0.9). The molecular weight of the proteoglycan measured by GPC (Gel Permeation Chromatography) is the range of 100,000~250,000 Da and the average molecular weight is 170,000 Da. The moisturizing effects and trans-epidermal water loss (TEWL) of chia seed polymer in cosmetic products (O/W emulsion) were studied in vivo. Chia seed polymer showed good skin hydration effects when compared with sodium hyaluronate which is a common moisturizer. Taken all together, chia seed polymer should be a very useful cosmetic ingredient as a moisturizer and a protecting agent from various skin irritations.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 1997.06a
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• pp.159-169
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• 1997

ABA-type(or AB) block copolymers composed of poly(${\gamma}$-alkyl L-glutamate) (PALG)[or poly(L-leucine)] as the A component and polyether[or poly (N-isopropy1 acrylamide) as the B component were synthesized by polymerization of (${\gamma}$-alkyl L-glutamate N-carboxyanhydride initiated by primary amined located at both(or one) ends of the polymer chains. Structural studies of the block copolymers were performed in the solution and solid state. Also, artificial skin, drug delivery system of the block copolymers and cell attachment onto the copolymer were carried out for biomedical applications.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2009.03a
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• pp.14-20
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• 2009

Atmospheric pressure air plasma was applied for treatment of different kinds of natural bamboo fiber to improve their mechanical properties and surface characteristics, which are suitable for adhesion and dyeing. The tensile strength and Young modulus of bamboo fiber were significantly improved; SEM and AFM study show that the surface of fiber became cleaner and rougher after plasma treatment. Plasma treatment caused the cracking, removing of the protective skin of alkali-untreated fiber and etching to form a cleaner and rougher surface. The dyeability of both groups of bamboo fiber which are used for composite and textile purposes is significantly enhanced after treatment.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.1
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• pp.108-112
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• 2001

Heart sound contains rich information regarding the dynamics of the heart and the auscultation has been a first choice of routine procedures for diagnosis of the heart. However, heart sounds captured using a conventional stethoscope are not often loud or clear enough for doctors to precisely classify their characteristics, especially, under the noisy environments of the hospital. A simple auscultation device that removed shortcomings of the conventional stethoscope was constructed in the study. The device employed a polymer based adherent differential output sensor which was on contact with skin through a coupling medium and appropriated electronic circuits for signal amplification and conditioning An ordinary headphone is taken to hear the captured heart sounds and the volume can be adjusted to hear well. It is also possible that the device sends the captured heart sound signals to a PC where the signals are further processed and viualized.

• Textile Coloration and Finishing
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• v.30 no.2
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• pp.141-149
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• 2018

This study aimed to investigate the efficacy of eco-friendly leather dyeing by utilizing food wastes. Natural dyeing of eel skin was attempted using onion peels which have been used commonly for natural dyeing of textile fabrics. Eel skin is a by-product from fishery processing and is used mainly for making leather products. The colorant was extracted from onion peels in boiling water, concentrated, and freeze-dried. Dyeing of eel skin was carried out to study the effects of dyeing conditions, mordant type and mordanting method on dye uptake, color change, drape stiffness and colorfastness. The optimum dyeing conditions were $60^{\circ}C$ of dyeing temperature, 60min of dyeing time at 1:100($H_2O$ 90%: ethanol 10%) of bath ratio. The onion peels produced yellowish color on eel skin. The pre-mordanting was effective than the post-mordanting. As a result of the drape stiffness measurement, the Fe-mordanted sample was somewhat stiffer comparing to other mordanted samples. The light fastness of the non-mordant dye was excellent in 3-4 grade. Drycleaning fastness and rubbing fastness showed excellent results, but fastness was not significantly improved by mordanting.