• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.105-110
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• 2001

Autoclave curing using the vacuum bagging method is widely used for the manufacture of advanced composite prepreg airframe structures. Due to increasing use of advanced composites, specific techniques have been developed to repair damaged composite structures. In order to repair the damaged part, it is required that the damaged areas be removed, such as skin and/or honeycomb core, by utilizing the proper method and then repairing the area by laying up prepreg (and core) then curing under vacuum using the vacuum bagging materials. It shall be cured either in an oven or autoclave per the original specification requirements. Delamination can be observed in the sound areas during and/or after a couple times exposure to the elevated curing temperature due to the repeated repair condition. This study was conducted for checking the degree of degradation of properties of the cured parts and delamination between skin prepreg and honeycomb core. Specimens with glass honeycomb sandwich construction and glass/epoxy prepreg were prepared. The specimens were cured 1 to 5 times at $260^{circ}F$ in an autoclave and each additionally exposed 50, 100 and 150 hours in the $260^{circ}F$ oven. Each specimen was tested for tensile strength, compressive strength, flatwise tensile strength and interlaminar shear strength. To monitor the characteristics of the resin itself, the cured resin was tested using DMA and DSC. As a results, the decrease of Tg value were observed in the specific specimen which is exposed over 50 hrs at $260^{circ}F$. This means the change or degradative of resin properties is also related to the decrease of flatwise tensile properties. Accordingly, minimal exposure on the curing temperature is recommended for parts in order to prevent the delation and maintain the better condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.827-832
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• 2005

Dual band internal antennas were fabricated with Ag conducting paste of various preparation conditions and different print thickness by silk screen print. We have investigated microwave properties were compared Ag conducting paste antenna with copperplate antenna at 800 MHz and 1,800 MHz. Gain of Ag conducting paste antenna was improved when preparation conditions were the single size Ag particle, using dry type resin and high Ag containing percent. However, it was lower than that of copperplate antenna within $0.1\~2.0dBi$ at 800MHz. In addition, it was improved at 800MHz when thickness of Ag conducting paste was printed more than skin depth but it was held after critical print thickness. On the other hand, it was reached level of copperplate antenna at 1,800MHz.

• CELLMED
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• v.10 no.4
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• pp.26.1-26.7
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• 2020

Sahdevi is an Indian herb commonly found in all part of the country in rainy season. It is adopted by Arabs due to its easy availability and various important pharmacological actions and uses. It is known by different vernaculars in different parts of the country such as Mahabala in Marathi, Sadodi in Gujrati, Kukseem in Bengali and in English it is called ash-colour fleabane or purple fleabane. The herb contains β-amyrin, lupeol, β-sitosterol, stigmasterol, α-spinasterol, phenolic resin and potassium chloride etc. It contains Dafi'-i Hummiyat (antipyretic) Muqawwi-i Badan (general tonic) and Musaffī-i-Dam (blood purifier) actions and used for management of many disease conditions. It has been used for the management of chronic fevers like fever associated with tuberculosis. It is a priceless herb with important pharmacological action and can be used effectively in place of costly drugs.

• Proceedings of the SCSK Conference
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• 1992.09a
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• pp.5-26
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• 1992

Many methods of in vitro SPF evaluation have been developed in order to measure SPF of sunscreen products. In this study, we compared two spectrophotometric in vitro measurements using the skin cast made of Luviset CAP- $X^{R}$ resin and Transpor $e^{R}$ tape as substrate with two in vivo measurements using guinea pig and human. And we also observed the radiation reaching on the earth's surface in Seoul for one year and the change of the primary skin irritancy along the change of SPF value. According to the our research, the first, in vivo measurement using guinea pig had the close agreement with SPF measurement using human and showed the tendancy that guinea pig SPF was lower than human SPF. The second, there was the good relationship between in vitro SPF by using Transpor $e^{R}$ tape and in vivo SPF, and it is possible to predict human SPF from Protection Index(PI) by using tape. The third, it is thought that SPE 20 is reasonable value because of UV intensity in Seoul and the primary skin irritancy of higher SPF than 25. So we propose that it is important to distinguish the sunscreen product having higher than approximate 25 from the category of general cosmetics including lower SPF sunscreen product.oduct.

• Journal of Dental Rehabilitation and Applied Science
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• v.16 no.2
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• pp.123-132
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• 2000

The field of maxillofacial prosthetics is concerned with the prosthetic reconstruction of missing head and neck tissue. Currently, facial prostheses are usually applied in cases of defects caused by the surgical removal of tumors or congenital defects. While silicone has been most widely used for the reconstruction of missing maxillofacial defects, it does not have ideal physical properties. Therefore, bonding a thin polyurethane sheet to silicone prostheses was recommended. In this case skin adhesives were used for the retention of maxillofacial prostheses. But retention of devices has always been problematic. The contributions of implants can be made to solve these problems. Implants have reduced the need for adhesive use, simplifying cleaning procedures and thus extending the life of the prostheses. For implant-retained prostheses, retentive matrix is necessary to hold attachments and/or magnets. The retentive matrix is usually fabricated with autopolymerizing acrylic resin or visible light- polymerized resin. The purpose of this study was to compare the adhesion-in-peel force of silicone adhesive to autopolymerizing acrylic resin and polyurethane sheet with two different surface textures : pumice polish only or retention groove, and three surface primers : Dow corning 1205 primer or Dow corning S-2260 primer or FactorII A-304 primer, and two polymerization methods : room temperature or dry heat oven. The t-peel bond strength of specimens was determined as described in ASTM Standard D1876-72. The results were statistically analyzed using the ANOVA test, multiple range test and t-test The results were as follows. 1. The t-peel bond strength of A-304 primer was the highest and statistically higher than that of S-2260(p<0.05). 2. The t-peel bond strength of specimens with retention groove was statistically higher than that of specimens polished with pumice(p<0.05). 3. The t-peel bond strength of specimens polymerized in dry heat oven was statistically higher than that of specimens in room temperature(p<0.01).

• The Korea Journal of Herbology
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• v.35 no.2
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• pp.1-6
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• 2020

Objectives : Heating process is the traditional processing method that has been applied to reduce the toxicity of dried resin of Toxicodendron vernicifluum (Anacardiacea) used as Geon-chil (乾漆, Lacca Rhois Exsiccata or Toxicodendri Resina). Urushiol, which is found in the plants of Toxicodendron genus, is a toxic compound that is absorbed into the skin and induces allergic dermatitis by being contacted. Hence, the reduction of urushiol level by heating processing of Geon-chil is crucial method for its medicinal application. Methods : Due to lack of Geon-chil processing-related articles, the articles researching the processing of lacquer (漆), as a coating material, were collected and analyzed to investigate the chemical change of urushiol during heating process. Results : The results demonstrate that the resin which was collected from the sap of T. vernicifluum tree was dried under warm and humid conditions repeatedly. During primary drying process, the laccase, a copper-containing enzyme in the resin, participated in the formation of urushiol polymers and thereafter urushiol-related toxicity could be reduced by making a lacquer harder and more stable. Moreover, heating a lacquer over 200℃ could cause thermo-degradation of urushiol polymers, and vaporized thermally degraded urushiol monomers and their by-products, which were determined using pyrolysis/GC-MS. Conclusions : These results support that heating process being performed over 200 ℃, such as stir-frying (炒) or calcination (煅), reduces the urushiol content in Geon-chil and hence, its medicinal use can be more stable without urushiol-related allergic reactions.

• The Korean Journal of Nuclear Medicine
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• v.12 no.2
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• pp.23-31
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• 1978

Hyperthyroidism may be defined as those clinical conditions which result from an increase in the circulating levels of one or both thyroid hormones. Hyperthyroidism in broad sense could be classified with toxic diffuse goiter, toxic adenomatous goiter, and toxic multinodular goiter on the basis of the circulating thyroid hormone levels. For this study, the subject included 94 cases with hyperthyroidism were presented in 77 with toxic diffuse goiter, 8 with toxic adenomatous goiter, and 9 with toxic multinodular goiter on the levels of $^{125}IT_3$ resin uptake rate and serum thyroxine ($T_4$). The observed results were as follows: 1) In the cases of hyperthyroidism including toxic diffuse goiter, toxic adenomatous goiter, and toxic multinodular goiter, 20.21% of the patients were male and 79.79% female. The majority of the patients were in 2nd to 4th decades of their lives. 2) There were objective signs clearly manifested in hyperthyroidism including toxic diffuse goiter and toxic adenomatous goiter which were rare in the multinodular goiter. The clinical signs in toxic diffuse and toxic adenomatous goiter included wide pulse pressure, tachycardia, systolic murmur, exophthalmos, tremor and warm skin etc. (Table 3.) 3) The most freauent complaints of the patients with hyperthyroidism were palpitation, weight loss, increased appetite, perspiration, heat intolerance, nervousness, exertional dyspnea, and menstrual disturbance etc. (Table 4.) There was no clear difference in the incidence of symptoms between toxic diffuse goiter and toxic adenomatous goiter, but there was clear difference between toxic multinodular goiter. 4) Considering of results of $^{125}IT_3$ resin uptake rate and serum $T_4$ level in toxic diffuse goiter, toxic adenomatous goiter and toxic multinodular goiter, $^{125}I\;T_3$ resin uptake rate was $49.15{\pm}9.94%$ (mean) and serum $T_4\;21.29{\pm}7.04ug/dl$ (mean) in toxic diffuse goiter. In toxic multinodular goiter, $^{125}I\;T_3$ resin uptake rate was $32.47{\pm}6.74%$ (mean) and serum $T_4$ level $11.03{\pm}5.0ug/dl$, and then there was clear difference in the results of $^{125}I\;T_3$ resin uptake rate and serum $T_4$ between toxic diffuse goiter and toxic multinodular goiter. The levels of $^{125}I\;T_3$ resin uptake rate and serum $T_4$ in toxic adenomatous goiter were $40.32{\pm}13.08%$ (mean), $15.47{\pm}8.25ug/dl$ (mean) respectively, so there was no clear difference between toxic diffuse goiter and toxic adenomatous goiter. 5) There was no significant differnece in length and width performed with thyroid scanning in toxic diffuse goiter, toxic adenomatous goiter, and toxic multinodular goiter.

• Korean Journal of Microbiology
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• v.55 no.1
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• pp.46-51
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• 2019

This study was carried out to evaluate antimicrobial effects of a mixture of resin fractionated ethanol extract of Eucalyptus globulus, Yucca recurvifolia, and tea tree (Melaleuca alternifolia). The plant fraction mixture showed low minimum inhibitory concentration (0.24~3.32 mg/ml) against several bacteria and yeast that usually used as the target skin microbes in a cosmetic industry, and it was more effective than antibiotics, triclosan and ampicillin. In a time-kill assay the plant fraction mixture reduced more than 92% of microbial populations during 4 h, and significantly increased leakage of nucleotides from all microorganisms tested. Antimicrobial effect of the plant fraction mixture was not affected by divalent cation ($Mg^{2+}$ and $Ca^{2+}$). These results suggest that the fraction mixture of ethanol extracts of E. globulus, Y. recurvifolia, and M. alternifolia may be utilized as an efficient preservative in cosmetics to prevent contamination by human skin microbes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1334-1340
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• 2017

In this paper, a tie-plate shape is optimized by using the numerical technique to reduce the stray load loss of the tie-plate which is a mechanical structure for assembling and supporting of the transformer core. The eddy current loss of the structure is calculated by an electromagnetic field FEM program and the results are compared with 4 different shapes of tie-plates. Since the thickness of the tie-plate is very thin, and the skin depth is very small, the number of FE elements for 3-D transformer model is too big to solve. So, the surface impedance boundary condition (SIBC) is used to reduce the system matrix size and its computing time. To verify the method a 2.5 MVA 22,900/380V distribution transformer is simulated using one objective function and three design variables with some constraints. The final optimized tie-plate has three slots of 6 mm width and 23 mm gap, and the loss is reduced by 75 %. Consequently, the proposed algorithm seems to be considerably applicable to electric machinery as well as power transformer.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.875-880
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• 2016

In this study, we proposed an effective and simple way to directly generate wrinkle patterns on a curved surface. A curved surface was prepared using a 3D printer and an UV (Ultraviolet)-lighting system was utilized to weakly polymerize the UV-curable thin resin layer coated on the surface, resulting in a gradient of material properties in the layer thickness. Subsequently, a thermal curing process was conducted to generate microscale wrinkles by compressive forces that were generated during complete curing. Wrinkle shapes from 5, 15, 25 sec of UV-light exposure were compared. With increasing UV-exposure, the line-width of wrinkles became thicker due to much higher strength of skin zone. The results indicated that the proposed fabrication process could be utilized for surface modification in diverse research fields.