• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.269-274
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• 2008

In this study we successfully altered the structural characteristics of the mica surface and were able to control oil-absorption by using the microwave enhanced etching (MEE) technique, which has originally been used in semiconductor industry. When microwave energy is applied to the mica, the surface of the mica is etched in a few minutes. As the result of etching, oil-absorption of the mica was enhanced and surface whiteness was improved by modifying the silicon dioxide layer. Additionally, the high whiteness was maintained even though the etched mica absorbed the sebum or sweat. The surface modification of mica was performed by microwave irradiation after the treatment of hydrofluoric acid. The degree of etching was regulated by acid concentration, irradiation time, the amount of energy and slurry concentration. The surface morphology of the etched mica appears to be the shape of the 'Moon'. The characteristics of surface area and roughness were examined by Brunauer-Emmett-Teller (BET) surface area analysis, atomic force microscopy (AFM), scanning electron microscopy (SEM), spectrophotometer and goniophotometer.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.2
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• pp.350-361
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• 1996

The objectives of this study mere 1) to investigate whether the different nonwoven fabric types influenced on the objective and subjective wear performances of the experimental pesticide protective pants, 2) to detect whether the different finishes treated to the nonwoven fabrics influenced on the objective and subjective wear performances of the experimental pants, and 3) to detect the relationships between objective wear performances and subjective wear sensation. Three types of nonwoven fabrics (T (Tyvek$\textregistered$), 5 (Sontara$\textregistered$) and K (Kimlon$\textregistered$)) were used as test specimens. By pad-dry.cure method, each of the specimen was treated with fluorocarbon compound for water-oil repellent finish (Tw, Sw, Kw). And each of specimen was treated with organic silicon quarternary ammonium salts and then treated with fluorocabon compound for dual functional finish (76, 50, Kd). Using the three water-oil repellent finished fabrics and the three dual functional finished fabrics, six experimental protective pants (Cl (Tw), C2 (Sw), C3 (Kw), C4 (76), C5 (56), C6 (Kd)) were made according to the same pattern suggested by the Rual Guidance Office. The wear trials of experimental pesticide protective pants were performed in a conditioned vinyl plastic hothouse ($30\pm1^{\circ}C$, $70\pm5%$R.H., 0.25m/sec air velocity). The measurements of skin temperature, microclimate temperature and humidity on the subjects were obtained by the themohygromenter. The subjective wear sensations were measured using previously developed thermal, humidity and overall comfort scales. The results obtained from this study were as follows: 1) There were siginificant differences among nonwoven fabric types on the objective and subjective wear performances, therefore, the skin temperature, microclimate temperature and humidity of subjects who wore the experimental pants made with Sontara were siginificantly lower than those who wore the others. And, the experimental pants made with Sontara were assessed as more comfortable than the others in terms of the subjective thermal, humidity and overall wear sensations. 2) There were no significant differences between two finish types on the objective and subjective wear Performances. 3) The microclimate humidity on the thigh was highly correlated with the overall subjective comfort sensations and the next highly correlated one was the mean skin temperature. That is, the higher the microclimate humidity and the mean skin temperature, the higher the overall subjective comfort sensation ratings which mean the overall subjective sensation was very uncomfortable.

• Journal of the Korean Magnetics Society
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• v.3 no.1
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• pp.34-40
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• 1993

Nylon 6 based magnetic pellets for injection molding were produced using plasma arc melt-spun $Nd_{10.5}Fe_{79}Co_{2}Zr_{1.5}B_{7}$ powders. Two sorts of bonded magnets made of two different sizes of particles ($38~75\;\mu\textrm{m}$ and $75~150\;\mu\textrm{m}$) were prepared to determine critical volume fraction of magnet powders, and the magnetic prop erties of the magnets were discussed as a function of density. For the nylon fi based Nd-Fe-Co-Zr-B pellets made of $38~75\;\mu\textrm{m}$ particles, the critical volume fraction of powders 0.7 was obtained with the pellet density which is 90% of theoretical density while the magnets of $75~150\;\mu\textrm{m}$ showed the density of 87% of the theoretical value with the same volume fraction. The nylon (i magnets with the addition of 0.5 wt. % silicon oil only exhibited the best magnetic properties to have $_{i}H_{c}=8.8\;kOe,\;B_{r}=5.1\;kG$ and $(BH)_{max}=5.2\;MGOe$ which are of world class. An empirical relationship in predicting the magnet density with a known fraction ($V_s$) of loading powders was obtained such as ${\rho}(g/cm^{3})=1.1+K.V_{s}$ where the K ranges over 5.3~5.6 be ing dependent upon the particle size loaded.

• Journal of Adhesion and Interface
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• v.25 no.2
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• pp.63-68
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• 2024

In this study, the contamination of gold(Au) wire according to the types of rinse applied for surface treatment in the wire bonding process is investigated and confirmed. For the surface treatment, rinses containing silicon(Si) or those based on organic materials are mainly employed. To identify their effects, surface treatment is conducted on Au wire using two types of rinse at a 1.0 wt% concentration, referred to as Si-including and Oil-based rinse-coated Au wire. Subsequently, a simulation experiment is performed to verify the reactivity of dust containing Si components that could occur in the semiconductor process. Through optical microscopy (OM) and scanning electron microscopy(SEM) analysis, it is observed that a larger amount of dust is adsorbed on the surface of Si-including rinse-coated Au wire compared with the Oil-based rinse-coated Au wire. This is attributed that the rinse containing Si components is relatively polar, causing polar interactions with dust, which also has polarity. Therefore, it is expected that using a rinse without Si components can reduce contamination caused by dust, thereby decreasing the defect rate in the practical wire bonding process.

• The Korean Journal of Rheology
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• v.11 no.2
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• pp.97-104
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• 1999

This paper presents vibration control of a drive feeding system consisting of a new type of CD-ROM(compact discread only memory) mount using electro-rheologocal(ER) fluid. Chemically treated starch particles and silicon oil are used for ER fluid. and its field-dependent yield stresses are experimentally distilled under both the shear and the flow modes. On the basis of the yield stress, an appropriate size of ER CD-ROM mount adapted to conventional feeding system is designed and manufactured. Vibration isolation performance of the proposed mount is evaluated in the frequency domain and compared with that of conventional rubber mount. The ER CD-ROM mount is then installed to the drive feeding system and the system equation of motion is derived. Following the formulating the sky-hook controller, computer simulation is undertaken in order to evaluate vibration suppression of the feeding system subjected to various disturbances(excitations).

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.279-282
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• 2000

The effect of three antifoam agents: PPG(polypropylene glycol), PEG(polyethylene glycol) and CA-110(aquous emulsion with 16% silicon oil component), was examined on the lincomycin production during cultivation of S. lincolnensis. Both PEG and PPG were effective in foam depressing during the flask cultures. As a result, the lincomycin production was enhanced upto about 400 mg/L in a optimized medium (OP-1) containing PEG or PPG. In contrast, the effect of antifoam agents in flasks was not remarkable for the various initial concentrations ranging from 0.5 g/L to 5 g/L with the basic medium(UP-1). But the lincomycin production in small fermentor showed the great different results in comparison with that in flasks under the same conditions. The lincomycin productions in small fermentor were 325 mg/L and 130 mg/L respectively for the following initial PPG concentrations, 0.5 g/L and 1 g/L.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.229-234
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• 2003

As electrorheological fluid(ER fluid) has a characteristic that apparent viscosity varies when electric field applied, so rheological characteristic(yield stress & viscosity) changes in proportion to the electric field applied and the response time is very short within a few miliseconds . In case of using ER fluid for journal bearing as lubricant, it is estimated that it's possible to realize very effective journal bearing system that is not complicate and has a very quick response time. It is necessary to examine the influence of rheological characteristic that varies with electric field applied on bearing characteristic to apply ER fluid to journal bearing, however there are few studies for about that. As for the journal bearing, it comes under high shear flow mode that has shear rate range of $10^3\~10^4s^{-1}$ because rotational speed is very high and clearance is small. But most of the studies for about ER fluid issued until now is about the range of $10\~10^2s^{-1}$. So, there are a lot of difficulties to understand the characteristic offish shear flow mode and furthermore it is restricted to make an experiment for about the characteristic of ER fluid because of the limitation of experimental equipment. The equipment was prepared to make an experiment lot high shear flow mode that has the range of $10^3\~10^4s^{-1}$ using ER fluid that is composed of silicon oil with dispersed particle of starch. Using the above system, the fluid characteristic of ER fluid was studied.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.51-56
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• 2015

The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.

• Korean Journal of Materials Research
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• v.24 no.8
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• pp.434-442
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• 2014

Serious environmental problems have been caused by the greenhouse effect due to carbon dioxide($CO_2$) or nitrogen oxides($NO_x$) generated by the use of fossil fuels, including oil and liquefied natural gas. Many countries, including our own, the United States, those of the European Union and other developed countries around the world; have shown growing interest in clean energy, and have been concentrating on the development of new energy-saving materials and devices. Typical non-fossil-fuel sources include solar cells, wind power, tidal power, nuclear power, and fuel cells. In particular, organic solar cells(OSCs) have relatively low power-conversion efficiency(PCE) in comparison with inorganic(silicon) based solar cells, compound semiconductor solar cells and the CIGS [$Cu(In_{1-x}Ga_x)Se_2$] thin film solar cells. Recently, organic cell efficiencies greater than 10 % have been obtained by means of the development of new organic semiconducting materials, which feature improvements in crystalline properties, as well as in the quantum-dot nano-structure of the active layers. In this paper, a brief overview of solar cells in general is presented. In particular, the current development status of the next-generation OSCs including their operation principle, device-manufacturing processes, and improvements in the PCE are described.

• Tuberculosis and Respiratory Diseases
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• v.40 no.5
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• pp.610-615
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• 1993

Silicone (polydimethylsiloxane) has widely been used in breast augmentation and other cosmetic procedures. Despite the stability of its chemical nature, local and systemic adverse reactions associated with silicone have been reported. There were several patients who suffered from pulmonary embolism associated with injection of silicone. Silicone-induced pneumonitis and sudden death after subcutaneous injection of silicone has been also described. However, there is no case in the literature of clinically diagnosed silicone-induced pulmonary embolism in Korea. We experienced 2 women who developed respiratory symptoms after illicit subcutaneous injection of silicone for the purpose of colporrhaphy. One patient was admitted because of dyspnea, chest pain, hemoptysis and bilateral pulmonary infiltration after repeated injection of silicone. Pulmonary function test initially showed severe restrictive pattern and transbronchial lung biopsy disclosed numerous oil-like material filling the alveolar septal capillaries and macrophages. High resolution C. T., bronchoalveolar lavage, transbronchial lung biopsy and pulmonary angiogram disclosed abnormalities compatible with silicone fluid-induced pulmonary embolism. The other patient expired shortly after arrival in the emergency room. It is suggested that illicit injecion of silicone fluid carries serious respiratory problems and can induce pulmonary embolism followed by acute respiratory failure.