• Archives of Plastic Surgery
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• v.51 no.1
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• pp.14-19
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• 2024

Background Hyaluronic acid fillers can be manufactured using various processes. They have multiple properties, including their concentration, degree of modification, and rheological data. Cohesion is one such property to evaluate gel integrity; however, there is no standardized method for calculating this parameter. This study aimed to evaluate different tests for calculating hyaluronic acid cohesion and discuss the importance of hyaluronic acid cohesion as a consideration when selecting fillers. Methods The cohesion levels of five different hyaluronic acid fillers with different rheological properties were evaluated and compared using the drop weight, compression, tack, and dispersion time tests. Results The cohesion tests yielded different results in the samples. Samples 2 and 4 showed approximately two times the number of droplets when compared with Sample 5 in drop weight test. Samples 1, 2, 3, and 4 were superior to Sample 5 in tack test. Samples 1, 2, and 3 showed cohesive appearances at 95 seconds in most cases in dispersion test. Rheological test results did not reflect the measures of cohesion. Conclusion Although there are no definite standardized tests to evaluate the cohesion of hyaluronic acid fillers, our proposed tests showed similar results for different hyaluronic acid filler products. Further studies are needed to evaluate the cohesion of hyaluronic acid fillers and determine the clinical use of this distinguishing characteristic for clinicians selecting the product of choice. Level of evidence statement: These data are Level IV evidence.

• Journal of the Korean Data and Information Science Society
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• v.9 no.2
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• pp.357-363
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• 1998

In this paper we propose a nonparametric lack of fit test based on the bootstrap method for testing the null parametric linear model by using linear smoothers. Most of existing nonparametric test statistics are based on the residuals. Our test is based on the centered bootstrap residuals. Power performance of proposed bootstrap lack of fit test is investigated via Monte carlo simulation.

• Applied Chemistry for Engineering
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• v.18 no.2
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• pp.121-125
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• 2007

Siloxane monomer and oligomer were introduced to n-butyl acrylate and methyl methacrylate copolymer for improvement of water resistance and tactile sensation of acryl-type emulsion. Terpolymerimerization of n-butylacrylate, methyl methacrylate and siloxane monomer or oligomer was carried out in aqueous solution. The glass transition temperature (Tg) of terpolymer decreased with increasing siloxane monomer, however, the Tg of terpolymer increased with increasing siloxane oligomer due to the crosslinking of acrylated end group. The adhesion property and surface energy of the obtained terpolymer decreased with introducing siloxane monomer or oligomer in terpolymer. Decrement of tack and surface energy means the enhancement of water resistance and tactile sensation of the emulsion.

• Journal of the Korean Wood Science and Technology
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• v.35 no.4
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• pp.38-44
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• 2007

As environmental issues is important thing, our study aims to develop natural adhesives made by rosin instead of synthesis adhesive with the formaldehyde emission. Natural adhesives were formulated to enhance curing speed and adhesion performances with various drying agent contents. Adhesion performances were evaluated with tack values measured by texture analyzer and shear strengths determined by single lap shear test. The adhesion performances of nature adhesives developed in this study and compared with those of overseas natural adhesives made by AURO, BioFa, Livos. Optimum drying agent formulation was Co 0.7 part, Zr 1.0 part, Ca 0.5 part, and Activ8 0.1 part. Shear strength of the adhesives manufactured by the optimum drying agent formulation was $93.2{\pm}19.1N/cm^2$.

• Journal of Adhesion and Interface
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• v.6 no.3
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• pp.19-25
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• 2005

Synthetic rubber based pressure-sensitive adhesives (PSAs) usually containing SIS or SBS block copolymer, tackifier, plasticizer, and other additives are now widely used on various applications. As these PSAs are physically crosslinked and can be applied without the use of solvent, they are thermally processable and environmentally friendly. However these PSAs cannot be used in high temperature applications and in applications where solvent and chemical resistance properties are required. We developed the PSA adding UV curable system, such as thiol-ene system, to increase adhesion properties at elevated temperature. The adhesion properties such as probe tack, peel strength, shear adhesion failure temperature (SAFT) were evaluated. The probe tack test was conducted with varying probe materials and coating thickness of PSAs. Using the contact angle, the surface property of the cured PSAs was also observed.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.05a
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• pp.299.2-299.2
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• 2004

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1021-1027
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• 2004

This research analyzed dynamic responses of the preflex railroad bridge. Vertical deflection and acceleration induced by operating train loads and test train loads were measured. Deflection of bridge by train traveling satisfies deflection limitation regulation (L/800) about the concrete bridge, but compare with UIC standard, vibration acceleration happened fairly greatly. Also test result show that acceleration receives greatly effect about the speed than deflection. It must discuss about vibration acceleration problems for speed elevation hereafter.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.42.2-42.2
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• 2018

신도시 및 대규모 도시 개발이 진행됨에 따라 안정적이고 효율적인 전력 공급을 위해 다수의 지상 배전함이 설치되고 있으며, 이에 따라 불법 광고물 및 스티커의 부착으로 인한 문제가 발생하고 있다. 이를 해결하기 위하여 여러 기관 및 산업체에서는 부착 방지용 코팅 도료 및 시트에 대하여 다양한 연구개발을 진행하고 있으며, 현장에 적용 된 다수의 제품이 존재한다. 하지만 현재 대부분의 제품들은 약 1년 정도의 시간이 지나면 부착 방지 기능을 상실하며, 도료와 기판 또는 시트와 기판 사이의 박리가 일어나 도시의 미관을 더욱 해치는 결과를 초래하고 있다. 이러한 원인으로는 부착력(Peel resistance, N/cm)을 측정하는 기존의 제시된 방법(KS T 1028, Peel test)으로는 정확한 측정이 어렵기 때문에 제품 선별에 어려움이 있다. 일반 기판의 경우 규격에서 요구하는 각도($90^{\circ}$, $180^{\circ}$)가 잘 유지되어 정밀한 부착력 측정이 가능하지만, 저점착 기능성 코팅소재(Anti-adhesion coating)의 경우 부착 자체가 어렵기 때문에 요구 각도를 유지하기 어려워 정밀한 측정을 할 수 없다. 이러한 문제점들을 해결하고자 압입자(Probe)를 이용한 새로운 평가 장치와 방법(Tack test)을 개발 및 제시하였다. 평가 지표로는 최대 점착력(Adhesive force, N), 최대 점착력일 때 점착제가 늘어난 총 길이(Extension of adhesive, mm), 탈착 에너지(Energy, J)가 있으며, 인가하는 힘(N)이 커질수록, 탈착 속도(Velocity)가 빨라질수록 평가 지표 모두 값이 상승하는 경향성을 보인다. 각 시험방법(Peel test, Tack test)에 대한 테이프류 점착제와 기판과의 결합이 끊어지는(Debonding, 탈착) 메커니즘(Mechanism)은 점착제 기공(Cavity)의 형성, 결합이 끊어지는 힘(Debonding force, N), 힘의 평형(Force balance)로 설명 가능하며, 상호간의 관계성을 도출한다. 이와 같은 평가 지표를 활용하여 저점착 기능성 코팅소재에 대해 정밀한 평가를 하는 것으로, 향후 개발될 다양한 제품에 대한 성능 분별력을 높이고, 현장에 적용 될 제품들의 성능을 끌어 올려 기존에 발생한 다양한 문제점들을 해결 할 수 있다.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.523-531
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• 2007

The research for the improvement of the aptitude test system in the field of railroad is progressing actively in advanced countries. Our government is also promoting some systematic supplementation for railroad safety on the basis of the Railroad Safety Act. In this paper, we focus our attention on an improvement of the present aptitude test system which will lead to the improvement of the safety supervision of Korean railroad. For this purpose, we perform a comparative analysis of domestic and foreign aptitude test systems for train drivers. We provide useful information that is needed to derive desirable aptitude test systems.

• Korean Journal of Veterinary Research
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• v.9 no.2
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• pp.55-59
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• 1969

For the establishment of simpler and more reliable methods for the diagnosis of Brucellosis, diagnostic antigen for Milk Ring Test (M.R.T.) was prepared according to working document recommended by Ministry of Agriculture U.S.A., and applied in the field for the test of its's applicability. The results are summarized as follows. 1. Of fifty two dairy cattle ranches in the vicinity of Seoul, five ranges were shown positive reaction to M.R.T. 2. Even though one volume of positive milk was mixed with five to ten volumes of negative milk, the positive reactions were also observed. 3. Antigenicity of the antigen was maintained without deteriolation for 13 months at $5^{\circ}C$ and three months at both $22^{\circ}C$ and $37^{\circ}C$. 4. Three positive cows to M.R.T. were also shown suspective reaction by Serum Agglutination Test.