• E2M - 전기 전자와 첨단 소재
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• 제10권2호
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• pp.141-149
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• 1997

L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ powders were prepared by both GNP(Glycine-Nitrate Process) and solid state reaction method in various of calcination temperature(800-1000.deg. C) and time in air. Also, L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ cathode contacts on YSZ(Yttria-Stabilized Zirconia) substrate were prepared by screen printing and sintering method as a function of sintering temperature(1100-1450.deg. C) in air. Sintering behaviors have been investigated by SEM(Scanning Electron Microscope) and porosity measurement. Compositional and structural characterization were carried out by X-ray diffractometer and ICP AES(Inductively Coupled Plasma-Atomic Emission Spectrometry) analysis. Electrical characterization was carried out by the electrical conductivity with linear 4 point probe method. As the calcination period increased in solid state reaction method, L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ phase increased. Although L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ single phase was obtained only for 48hrs at 1000.deg. C, in GNP method it was easy to get single and ultra-fine L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ powders with submicron particle size at 650.deg. C for 30min. The particle size and thickness of L $a_{0.7}$S $r_{0.3}$Mn $O_{3}$ cathode contact by solid state reaction method did not change during the heat treatment, while those by GNP method showed good sintering characteristics because initial powder size fabricated from GNP method is smaller than that fabricated from solid state reaction method. Based on enthalpy change from thermodynamic data and ICP-AES analysis, it was suggested to make cathode contact in composition of (L $a_{0.7}$S $r_{0.3}$)$_{0.91}$ Mn $O_{3}$ which have little second phase (L $a_{2}$Z $r_{2}$ $O_{7}$) for high efficient solid oxide fuel cells applications. As (L $a_{0.7}$S $r_{0.3}$)$_{0.91}$Mn $O_{3}$ cathode contact on YSZ substrate was sintering at 1250.deg. C the temperature that liquid phase sintering did not occur. It was possible to obtain proper cathode contacts with electrical conductivity of 150(S/cm) and porosity content of 30-40%.m) and porosity content of 30-40%.

• The Journal of Korean Physical Therapy
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• 제34권6호
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• pp.283-291
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• 2022

Purpose: The purpose of this study was to compare and analyze the method of measuring the angle of the trunk rotation using a smartphone with 3D smartphone holder compared to a scoliometer, which is a measuring tool used as a method for diagnosing scoliosis in scoliosis patients. Methods: Angle of trunk rotation was measured in 21 subjects diagnosed with scoliosis. scoliometer measurement method, a smartphone measurement method with a 3D smartphone holder, a smartphone blind measurement method with a 3D smartphone holder, a smartphone measurement method without a smartphone holder, a smartphone blind measurement method without a smartphone holder, and a total of five measurement methods were repeated three times for comparison and analysis. Results: The smartphone measurement method with a 3D smartphone holder has excellent intra-rater reliability of angle of trunk rotation (Rater A; ICC3, 2≥0.993, Rater B; ICC3, 2≥0.992). The smartphone blind measurement method with a 3D smartphone holder has excellent inter-rater reliability of angle of trunk rotation (ICC2, 2≥0.968). The scoliometer measurement method had the highest validity (r=0.976) with the smartphone measurement method with a 3D smartphone holder, and the blind measurement method without a smartphone holder had the lowest validity (r=0.886). Conclusion: These findings, the angle of trunk rotation measured by the smartphone measurement method with a 3D smartphone holder in scoliosis patients showed high reliability and validity compared to the scoliometer measurement method.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.603-609
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• 2013

In this paper, we describe the analysis of inkjet-printed silver (Ag) patterns on epoxy-coated substrates according to several reliability evaluation test method guidelines for conventional printed circuit boards (PCB). To prepare patterns for the reliability analysis, various regular test patterns were created by Ag inkjet printing on flame retardant 4 (FR4) and polyimide (PI) substrates coated with epoxy for each test method. We coated the substrates with an epoxy primer layer to control the surface energy during printing of the patterns. The contact angle of the ink to the coated epoxy primer was $69^{\circ}$, and its surface energy was 18.6 $mJ/m^2$. Also, the substrate temperature was set at $70^{\circ}C$. We were able to obtain continuous line patterns by inkjet printing with a droplet spacing of $60{\mu}m$. The reliability evaluation tests included the dielectric withstanding voltage, adhesive strength, thermal shock, pressure cooker, bending, uniformity of line-width and spacing, and high-frequency transmission loss tests.

• Bulletin of the Korean Chemical Society
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• 제31권6호
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• pp.1583-1588
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• 2010

A single step fabrication process of carbon nanotube/Prussian Blue (CNT/PB) paste electrodes based on screen printing technology has been studied as an amperometric sensor for the determination of hydrogen peroxide and free chlorine. Compared to the classical carbon paste (CP) electrode, the CNT paste electrode greatly enhanced the response in the presence of hydrogen peroxide due to the electrocatalytic activity of the CNT. Based on the CNT/binder paste, PB was also incorporated into a network of CNT paste and characterized. The best electroanalytical properties of PB-mixed sensors to hydrogen peroxide were obtained with PB ratio of 10 wt % composition, which showed fast response time ($t_{90}{\leq}5$ s; 0.2 - 0.3 mM), low detection limit of 1.0 ${\mu}M$, good linear response in the range from $5.0{\times}10^{-5}$ - $1.0{\times}10^{-3}$ mol $L^{-1}$ ($r^2$ = 0.9998), and high sensitivity of -8.21 ${\mu}AmM^{-1}$. In order to confirm the enhanced electrochemical properties of CNT/PB electrode, the sensor was further applied for the determination of chlorine in water, which exhibited a linear response behavior in the range of 50 - 2000 ppb for chlorine with a slope of 1.10 ${\mu}Appm^{-1}$ ($r^2$ = 9971).

• Journal of Preventive Medicine and Public Health
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• 제20권2호
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• pp.228-235
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• 1987

유기용제 사업장의 그라비아 인쇄부에 근무하는 근로자 101명과 유기용제에 노출되지 않은 72명을 선택하여 뇨중 마뇨산량과 사업장의 공기중 톨루엔 농도를 측정하여 상관성을 구하였으며 설문조사를 통한 자각증상 호소율을 조사하여 다음과 같은 결론을 얻었다. 1) 작업부서별 공기중 톨루엔 농도는 유기용제를 혼합하면서 인쇄하는 부서에서 평균 $544.13{\pm}7.75ppm$으로 가장 높았으며 유기용제 혼합부서에서 $463.27{\pm}5.24ppm$ 인쇄 (1)부서 에서 $393.56{\pm}45.69ppm$ 인쇄 (2)부서에서 $248.38{\pm}45.16ppm$ 인쇄(3)부서 $159.38{\pm}18.51ppm$이었다. 2) 작업부서별 뇨중 마뇨산량은 유기용제를 혼합하면서 인쇄하는 부서의 근로자에서 평균 $6034.84{\pm}1298.35mg/l$로 가장 높았으며 유기용제 혼합부서의 근로자에서 $4798.44{\pm}784.53mg/l$ 인쇄(1)부서의 근로자에서 $2883.06{\pm}701.90mg/l$ 인쇄(2)부서 의 근로자에서 $1449.98{\pm}905.19mg/l$ 인쇄(3)부서의 근로자에서 $598.52{\pm}299.43mg/l$였다. 3) 작업 장 공기중 톨루엔 농도와 마뇨산량과의 상관계수는 r=0.868(p<0.01)으로 정상관 관계를 나타냈다 (Y=7,18X+349.57) 4) 실험군이 대조군보다 더 많은 자각증상을 호소하였다.

• 한국산업보건학회지
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• 제11권2호
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• pp.135-144
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• 2001

This study was performed to measure airborne dimethylformamide(DMF), methyl ethyl ketone(MEK) and toluene and their urinary metabolites concentrations and to determine the relationship between airborne and urinary concentration. Airborne samples and their urinary metabolites were measured 98 male workers who work for 8 synthetic leather factories in a portion of Kyoung-In area. Urine samples were collected at end-of-shift to estimate the exposure levels. 1. The concentration of airborne DMF by process was 8.81 ppm for wet-mixing, 15.05 ppm for wet-coating, 6.03 ppm for dry-mixing, 5.58 ppm for dry-coating, 5.37 ppm for printing, and 9.03 ppm for total. There was statistically significant difference by process. Urinary NMF concentrations of wet-mixing, wet-coating, dry-mixing, dry-coating and printing were $90.55mg/{\ell}$, $79.80mg/{\ell}$, $39.86mg/{\ell}$, $25.23mg/{\ell}$, and $38.15mg/{\ell}$, respectively, and total geometric mean was $56.24mg/{\ell}$. There was significant difference by process. 2. The concentration of airborne MEK by process was 1.89 ppm for wet-mixing, 1.96 ppm for wet-coating, 10.33 ppm for dry-mixing, 29.24 ppm for dry-coating, 14.98 ppm for printing, and 4.87 ppm for total. There was statistically significant difference by process. Urinary MEK concentrations of wetmixing, wet-coating, dry-mixing, dry-coating and printing were $0.93mg/{\ell}$, $0.70mg/{\ell}$, $3.29mg/{\ell}$, $3.29mg/{\ell}$, and $1.06mg/{\ell}$, respectively, and total geometric mean was $1.25mg/{\ell}$. There was statistically significant difference by process. Urinary MEK 3. The concentration of airborne toluene by process was 0.35ppm for wet-mixing, 0.42ppm for wet-coating, 2.95ppm for dry-mixing, 11.67ppm for dry-coating, 4.88ppm for printing, 1.24ppm for total. There was statistically significant difference by process. Urinary hippuric acid concentrations of wet-mixing, wet-coating, dry-mixing, dry-coating and printing were 0.24g/g creatinine, 0.21g/g creatinine, 0.34g/g creatinine, 0.52g/g creatinine, and 0.29g/g creatinine, respctively and total geometric mean was 0.28g/g creatinine. There was statistically significant difference by process. 4. No. of exceeded KPEL was 40 workers(40.8%) for DMF(10ppm), 1 worker(1.0%) for MEK(200ppm), and no worker for toluene(100ppm). No. of exceeded KBEI was 62 workers(63.3%) for urinary NMF($40mg/{\ell}$), 29 workers(29.6%) for urinary MEK, 1 worker(1.0%) for urinary hippuric acid. 5. The regression equations were Log(NMF)=0.4094*Log(DMF)+1.3587(r=0.4516) for DMF, Log(MEKU)=0.1859*Log(MEK)-0.0324(r=0.3303) for MEK, Log(HA)=0.2106*Log(Toluene)-0.5685(r=0.4497) for toluene. Synthetic leather factory workers expose to 3 kinds of organic solvents which are DMF, MEK and toluene. Their urinary NMF and MEK levels were higher than their concentration levels through respiratory. It seems that the urinary levels were affected skin absorption for working habit and alcohol intake.

• Toxicological Research
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• 제32권4호
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• pp.337-343
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• 2016

We determined the toxicity of mixtures of ethyl acetate (EA), isopropyl alcohol (IPA), methyl ethyl ketone (MEK), toluene (TOL) and xylene (XYL) with half-maximal effective concentration ($EC_{50}$) values obtained using human hepatocytes cells. According to these data, quantitative property-activity relationships (QPAR) models were successfully proposed to predict the toxicity of mixtures by multiple linear regressions (MLR). The leave-one-out cross validation method was used to find the best subsets of descriptors in the learning methods. Significant differences in physico-chemical properties such as boiling point (BP), specific gravity (SG), Reid vapor pressure (rVP) and flash point (FP) were observed between the single substances and the mixtures. The $EC_{50}$ of the mixture of EA and IPA was significantly lower than that of contained TOL and XYL. The mixture toxicity was related to the mixing ratio of MEK, TOL and XYL (MLR equation $EC_{50}=3.3081-2.5018{\times}TOL-3.2595{\times}XYL-12.6596{\times}MEK{\times}XYL$), as well as to BP, SG, VP and FP (MLR equation $EC_{50}=1.3424+6.2250{\times}FP-7.1198{\times}SG{\times}FP-0.03013{\times}rVP{\times}FP$). These results suggest that QPAR-based models could accurately predict the toxicity of polar and nonpolar mixtures used in rotogravure printing industries.

• 한국산학기술학회논문지
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• 제15권2호
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• pp.666-671
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• 2014

최근 디젤 차량과 같은 내연기관의 고효율화에 따라, 보조난방 열원으로서 PTC 히터의 사용이 증가하는 추세이다. 디젤 차량의 시동 초기에는 냉각수의 온도가 난방으로 직접 사용하기에 충분히 높지 않으므로, 동절기 난방을 위해 보조난방 열원은 필수적이다. 본 연구에서는 스크린 인쇄 전극공정을 바탕으로 한 PTC 소자를 제작하였고, 이를 활용한 PTC 소자 모듈 및 히터를 설계 및 제작하였다. PTC 소자 모듈의 방열핀 접촉형상 및 전열소자의 크기 변경에 따른 난방성능 변화를 열유동 해석을 통해 분석하였고, 난방성능 실험을 수행하여 PTC 히터의 난방성능 및 효율 특성을 살펴보았다. PTC 히터 시작품의 경우, 기존 PTC 히터와 동등한 수준 이상의 난방성능 및 효율을 나타내었으며, 향후 이를 바탕으로 PTC 소자와 히터에 대한 공정개선 및 성능증대 연구를 수행할 계획이다.

• 한국의류산업학회지
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• 제23권6호
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• pp.810-825
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• 2021

This study measured and analyzed clothing pressure at each measurement part of commercial body shapers to provide basic information for product design and clothing pressure standard and level. This study used five body shaper. Clothing pressure measurements were taken at 18points: Anterior area 8points, lateral area 5points, posterior area 5points. The findings of this study were as follows. As a result of measuring the clothing pressure, the body shaper 1 showed the highest pressure, and body shaper 5 showed the lowest pressure at almost of the measurement points of the three body types. In some cases, body shapers 2, 3, and 4 showed different orders of pressure depending on the measurement point. The highest measured values in most body shapers were the P1 shoulder area and the P2 bust area. The lowest measurement area differed by body type, but mainly P3 underbust area, P4 thorax area and P9 axillary area, P11 waist lateral area, P13 hip lateral area. These body shapers showed different results depending on the the manufacturers and body type of middle-aged women, and because there was no standard for the pressure value. Therefore, it is necessary to design a body shaper sizing system after accurately setting the clothing pressure value for each body part of the consumer.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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• pp.82-82
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• 2015

Industrial crystalline silicon (c-Si) solar cells with using a screen printing technology share the global market over 90% and they will continue to be the same for at least the next decade. It seems that the $2^{nd}$ generation and the $3^{rd}$ generation technologies have not yet demonstrated competitiveness in terms of performance and cost. In 2014, new world record efficiency 25.6% (Area-$143.7cm^2$, Voc-0.740V, $Jsc-41.8mA/cm^2$, FF-0.827) was announced from Panasonic and its cell structure is Back Contact $HIT^*$ c-Si solar cell. Here, amorphous silicon passivated contacts were newly applied to back contact solar cell. On the other hand, 24.9% $TOPCon^{**}$ cell was announced from Fraunhofer ISE and its key technology is an excellent passivation quality applying tunnel oxide (<2 nm) between metal and silicon or emitter and base. As a result, to realize high efficiency, high functional technologies are quite required to overcome a theoretical limitation of c-Si solar cell efficiency. In this presentation, Si solar cell technology summarized in the International Technology Roadmap for Photovoltaics ($^{***}ITRPV$ 2014) is introduced, and the present status of R&D associated with various c-Si solar cell technologies will be reviewed. In addition, national R&D projects of c-Si solar cells to be performed by Korea University are shown briefly.