• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.61-68
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• 2008

Of the seven base units of the international system of units, only the kilogram is still defined in terms of a material artifact. One of the experimental approaches opening the way to a new definition of the kilogram is the watt balance To improve the performance of the NPL watt balance, we need to quantify and reduce hysteresis effects in the balance knives. In this paper, we discuss the mechanical characteristics of the knife edges used in the NPL watt balance. The hysteresis mechanism is analyzed using the finite element method. It is found that the cause of hysteresis is not normal stress but shear, and the deformation of the flat, rather than the knife, is an important factor in the hysteresis mechanism. The study presented here, using finite element analysis, suggests that parameters such as material property, tip radius and knife straightness can be more important than others, such as friction coefficient, tip angle, etc.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.2
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• pp.354-363
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• 2004

PCDD/F (Polychlorinated dibenzo-p-dioxins and dibenzofurans) in both of treated fabric and untreated fabric for working clothes of a municipal waste incineration were determinated. The treated fabric for working clothes was developed for less exposure of PCDD/F in municipal waste incinerations. The total concentrations of PCDD/F in some parts such as surface, middle layer, inside for treated and untreated fabric were investigated. The I-TEQ value of surface was 0.23370ng TEQ/g for treated fabric, 0.15355ng $.$ TEQ/g for non-treated fabric. On the other hand, the value of middle layer was 0.00077ng $.$ TEQ/g, 0.00177ng $.$ TEQ/g, respectively. The surface of the treated fabric containing high levels PCDD/F was caused by absorption of them. Therefore, PCDD/F of the treated fabric in middle layer was less I-TEQ value than that of the untreated fabric. The treated fabric makes effect on preventing PCDD/F from permeating into human body.

• Analytical Science and Technology
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• v.24 no.1
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• pp.15-23
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• 2011

An accurate mass and isotope ratio were determined using a gas chromatography/time of flight mass spectrometer in CI positive mode for the identification of unknown metabolites. High mass tune was used to improve the ion intensity of $[M+H]^+$. Chromatographic resolution and dynamic range enhancement were performed to obtain more reliable accurate masses and correct isotope abundance ratios. Average absolute errors of mass and isotope ratios for 24 reference metabolite -TMS (trimethylsilyl) derivatives were 6.8 ppm, 1.5% of (M+1/M ratio) and 1.7% of (M+2/M ratio), respectively. The correct formulas of twenty one compound were retrieved within top-2 hit from the heuristic algorithm for elemental composition using each accurate mass and isotope abundance ratio.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.250-257
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• 2002

A centrifugal compressor for HFC-l34a has been newly designed and developed. Flow analysis using commertial programs was used to evaluate performance and internal flow of the impeller, inlet guide vane and diffuser etc. and design software was developed. The compressor for HFC-l34a was also investigated experimentally to check compression performance. The calculated data coincide the test results of compressor. The data obtained in the present study are useful for design of HFC-l34a centrifugal compressors.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.1
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• pp.165-171
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• 2004

The analytical method of toxic heavy metals in disposable diapers was developed. Disposable diapers obtained from Korea, Japan, America and German were determinated and quantified. Sample treatment (Total Digestion) was wet chemical acid digestion for extraction of nine hazardous inorganic elements (Sb, As, Pb, Cd, Cr, Co, Cu, Ni, Hg) in disposable diapers. Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) have been used for analyzing nine hazardous inorganic elements. The results were as follows : The concentration of extractable Sb which was treated for 3 hours with artificial urine and disposable diapers was higher than those of 6 hours and 24 hours. The concentration of extractable Cr was same as Sb. On the other hands, the behavior of Cu and Ni were different from Sb and Cr. Concentrations of extractable Cu and Ni increased as increasing the reaction time between artificial urine and disposable diapers.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.465-475
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• 2010

구조물의 손상을 평가하기 위한 적용되는 태핑 테스트를 효과적이고, 정확하게 사용하기 위하여 적층판의 충격 시 발생하는 현상을 수치적인 방법을 이용하여 해석하였다. 구조물의 진동에 의해 방사되는 음은 구조물의 거동과 직접적으로 연관되므로 충격응답해석이 수행되어야 한다. 본 논문에서는 층간분리가 존재하는 적층판의 해석을 위하여 층간분리 모델을 사용하였으며, 해머 형상의 충격체를 모사할 수 있는 효과적인 스프링-질량모델을 제시하였다. 또한 태핑 테스트 시 방사되는 음압을 Rayleigh 적분식을 이용하여 해석하였다. 예측된 음압이력과 시험결과와 비교하였으며, 음압이력과 충격하중이력에 손상이 주는 영향을 검토하였다. 방사되는 음압과 충격하중이력은 적층판에 존재하는 손상에 영향을 받는 것을 보였다. 결과적으로 제안된 음을 이용한 태핑실험은 복합재에 존재하는 손상을 검출하는데 신뢰성 있는 방법임을 알 수 있었다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.3
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• pp.139-148
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• 2010

A centrifugal compressor for HFC-134a has been newly designed and developed. Flow analysis using commercial programs was used to evaluate performance and internal flow of the impeller, inlet guide vane and diffuser etc. The purpose of this study is to establish the design theory necessary to the development of HFC-134a centrifugal compressors and to supply basic data related to design by reviewing design values and experimental values through the performance test. The compressor for HFC-134a was also investigated experimentally to check compression performance. The calculated data coincide the test results of compressor. The data obtained in the present study are useful for design of HFC-134a centrifugal compressors.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.6
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• pp.814-824
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• 2005

This study analyzed and standardized the harmful substances of organic compounds(dioxins) in disposable diapers for infant's clothing. Commercial samples obtained from Korea, Japan, America and German were determined by HRGC/HRMS. Experimental Methods were consisted of comparision of extracting solvent, analysis of PCDD/Fs, and analysis of PCDD/Fs of extraction in disposable diaper. The results were as follows. No high TEQ values in TCDD(1), PCDD(0.5) and HxCDD(0.1) were found for commercial disposable diapers from country Korea, Japan, U.S.A and German. In extraction for 6hrs experiments, HpCDD and OCDD were detected in disposable diapers of U1, U2 and G2, respectively. In extraction fur 24hrs experiments, HpCDD, OCDD and OCDF were detected in disposable diapers of J3, U1, U2 and U3. So we need to set standards of measurement for harmful materials contained in textile goods. This will make a safe and comfortable clothing environment for all users, regardless of age.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.6
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• pp.853-859
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• 2009

Endometriosis becomes the most common cause of pelvic pain and infertility women. The cause of endometriosis has ever been entirely proven. However, an increased use of commercial feminine hygiene products such as tampons and sanitary napkins was considered one of the major affect. Harmful substances in feminine hygiene products was analyzed and evaluated. Samples of commercial products obtained from Korea, Japan, America, Germany, and China were analyzed for six hazardous inorganic elements (chromium, cobalt, nickel, copper, cadmium and lead). In the extractable heavy metals of napkins, Cr, Ni and Cu were found in all of the samples, while Cd was detected only in two samples. In the tampons, Cr, Ni and Cu were found in all of the samples. The presence of Co and Cd was not detected in all samples The concentrations of extractable heavy metals in the tampons were lower than those in the sanitary napkins. The content of extractable heavy metals in the sanitary products was compared with the criteria of the 100 $\ddot{O}KO$ TEX Standard. It was confirmed that the level of heavy metals in the sanitary products posed no serious risk to health, based on the human-ecological criteria defined by the 100 $\ddot{O}KO$ TEX Standard.

• Membrane Journal
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• v.16 no.1
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• pp.16-24
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• 2006

We report on the preparation and characterization of sulfonated polymer membranes containing perfluorocyclobutane (PFCB) units and fluorene units. The polymers were prepared through three synthetic steps, that is, the synthesis of a trifluorovinylether-terminated monomer, its thermal polymerization, and post-sulfonation using chlorosulfonic acid. A series of sulfonated polymers with different ion exchange capacity (IEC) were prepared by changing the content of chlorosulfonic acid during the post-sulfonation reaction. All the synthesized compounds were characterized by FT-IR, $^{1}H-NMR,\;^{19}F-NMR$, and Mass spectroscopy. As the content of chlorosulfonic acid increased, the SD, IEC, water uptake, and ion conductivity of the sulfonated polymer membranes increased. The sulfonated polymer 4 showed higher values of ion conductivity than the Nafion-$115^{\circledR}$ in a wide range of temperatures ($25{\sim}80^{\circ}C$).