• Corrosion Science and Technology
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• 제18권6호
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• pp.258-266
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• 2019

The objective of this study was to evaluate corrosion resistance of additive manufactured 316L stainless steel and alloy 625 powders widely used in corrosion resistance alloys of marine industry in comparison with cast alloys. Directed Energy Deposition (DED) method was used in this work for sample production. DED parameter adjustment was also studied for optimum manufacturing and for minimizing the influence of defects on corrosion property. Additive manufactured alloys showed lower corrosion resistance in seawater compared to cast alloys. The reason for the degradation of anti-corrosion property was speculated to be due to loss of microstructural integrity intrinsic to the additive manufacturing process. Application of heat treatment with various conditions after DED was attempted. The effect of heat treatments was analyzed with a microstructure study. It was found that 316L and alloy 625 produced by the DED process could recover their expected corrosion resistance when heat treated at 1200 ℃.

• 소성∙가공
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• 제24권4호
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• pp.287-292
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• 2015

The possibility of chemical precipitation for recycled ammonium paratungstate (APT) was studied. WO₃ particles were synthesized by chemical precipitation method using a 1:2 weight ratio of APT:DI-water. At the 500℃ sintering temperature, the X-ray diffraction results showed that APT completely decomposed to WO₃. For the granulated powder WC-Co, vacuum heat treatment at proper temperatures increases tap density and flow-ability. Hardness of the WC-Co thermal spray coating layer was measured in the range HV 831~1266. Spray conditions for the best characteristic values were an oxygen flow rate=1500 scfh, a fuel flow rate = 5.25gph and a gun distance = 320mm.

• 한국표면공학회지
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• 제37권3호
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• pp.152-157
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• 2004

Ti-Al-N ($Ti_{75}$ $Al_{25}$ N) and Ti-Al-Si-N ($Ti_{69}$ $Al_{23}$ $Si_{8}$N) coatings synthesized by a DC magnetron sputtering technique were studied comparatively with respect to phase characterization and high-temperature oxidation behavior. $Ti_{69}$ $Al_{23}$ $Si_{ 8}$N coating had a nanocomposite microstructure consisting of nanosized(Ti,Al,Si)N crystallites and amorphous $Si_3$$N_4$, with smooth surface morphology. Ti-Al-N coating of which surface $Al_2$$O_3$ layer formed during oxidation suppressed further oxidation. It was sufficiently stable against oxidation up to about $700^{\circ}C$. Ti-Al-Si-N coating showed better oxidation resistance because both surface Ab03 and near-surface $SiO_2$ layers suppressed further oxidation. XRD, GDOES, XPS, and scratch tests were performed.

• 펄프종이기술
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• 제46권5호
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• pp.1-8
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• 2014

In this study, the influence of the physical properties of ink such as ink dispersity and emulsified amount on the printability of a coated paper was investigated with seven kinds of cyan inks. In addition, two kinds of coating formulations were tested to evaluate the effect of coating structure on the coated paper printability. It was found that the cyan ink with $2{\mu}m$ pigment size had the best dispersibility and hence the ink showed a best ink density on the two kinds of coated papers. When the emulsified ink A with IPA 20 wt% had a lower viscosity than emulsified ink B with IPA 10 wt%, the emulsified ink A showed relatively high value of the ink transfer rate in comparison with emulsified ink B. Despite the high value of ink transfer rate, the coated paper did not show a good printability because those inks with low viscosity due to a strong emulsification were easy to make print mottle on the coated paper.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.937-946
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• 1996

A Far Infrared Ray (FIR) dryer was designed , constructed and tested for red pepper , lycium chinese, and mushroom (Cortiellus shiitake ) drying , and the results were compared to the heated air dryer at the same condition. In the FIR dryer, three different panel materials , galvanized, copper and stainless steel, were used and no ceramic coating and those with ceramic coating (three panels) were 58% , 56%, 64%, and 88% , respectively. The drying times of lycium chinese and mushroom were shortened in FIR dryer by 6 hrs and 4 hrs compared to the heated air drying, respectively. while to remarkable difference in the drying times was found in the red pepper drying . The quality of products was better in FIR dryer where more red color value for red pepper and lycium chinese and more brightness for mushroom . The drying performance of a FIR dryer was superior in terms of total cost of 80,800 WON /100kg of lycium chinese , reduced by 25% compared to the heated air drying.

• 대한한의학회지
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• 제31권1호
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• pp.23-29
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• 2010

Objective: The aim of this prospective, case-controlled study was to assess the difference of the amount of tongue coating between halitosis and non-halitosis patients using a digital tongue diagnosis system (DTDS). Methods: Sixty-five patients complaining of oral malodor were recruited for the study. The level of volatile sulfur compounds (VSC) in the oral cavity of the patients was measured by a portable gas chromatography. All patients were then divided into two groups, the halitosis group ($H_2S{\geq}1.5ng$/10ml, or $CH_3SH{\geq}0.5ng$/10ml) and the non-halitosis group ($H_2S$<1.5ng/10ml and $CH_3SH$<0.5ng/10ml), according to the VSC level criteria published by Tonzetich. Tongue images of the two groups were acquired and analyzed by DTDS, followed by the analysis of the tongue coating scores. Results: The tongue coating scores of the halitosis group were significantly higher than of the non-halitosis group (P=0.033). Furthermore, the difference of the posterior tongue coating between the two groups was more significant (P=0.000). Conclusions: Halitosis patients were shown to have a thicker tongue coating than those in the non-halitosis group. Moreover, the posterior dorsum of the tongue should be observed more cautiously when dealing with halitosis patients. Also, the progress and state of the patient's symptom of halitosis as diagnosed objectively by the portable gas chromatography could also possibly be analyzed instead by the DTDS tongue coating score.

• 한국표면공학회지
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• 제40권6호
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• pp.254-257
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• 2007

TiN coating on tool steel has been widely used for the improvement of durability of tools. In this work, radical nitriding(RN) is carried out on SKD61 at $450^{\circ}C$ for 5 hours in the ammonia gas pressure $2.7{\times}10^3\;Pa$. The TiN coating is carried out by arc ion plating(AIP) with the process parameters: arc power 150 A, bias voltage -50V, coating time 40 minutes and nitrogen gas pressure $4{\times}10^3\;Pa$. Hardness, elastic modulus, friction coefficient and adhesion of TiN coating on substrates of both TiN/SKD61 and TiN/RN SKD61 coatings are investigated comparatively. The primary crystalline faces of TiN surface are(200) and(111) for TiN/SKD61 and TiN/RN SKD61 respectively. In addition to the primary phase, Fe phase exists in TiN/SKD61 coating, but not in TIN/RN SKD61. The hardness of TiN/RN SKD61 is about 700 Hv, 250 Hv(56%) higher than that of TiN/SKD61 at the near interface of TiN and substrates. At the TiN surface, hardness of TiN/RN SKD61 is 2,149 Hv, 71 Hv(3%) higher than that of TiN/SKD61. The elastic modulus of TiN coating is improved to 26.7 GPa(6%) by radical nitriding. The adhesion is improved by the RN coating showing no spalling. buckling and chipping on the scratch test track which are shown on the non-RN TiN/SKD61.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.414-414
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• 2012

차세대 플렉시블 디스플레이 소재로서, 탄소나노뷰브(CNT) 기반의 투명전도막은 기존의 ITO 박막보다 우수한 유연성을 갖기 때문에 많은 관심을 모으고 있다. 특히 낮은 저항과 투과도를 유지하면서 투명 전도막의 내구성을 향상시키는 연구는 상업화에 가장 필요한 연구 분야이다. 본 연구에서는 다층벽 탄소나노튜브(MWCNT)를 이용하여 제작된 투명 전도막의 내구성을 개선하기 위하여 오버 코팅을 통한 물성 개선을 연구하였다. 투명전도막은 PET기판 위에 스프레이 방식을 이용하여 균일하게 코팅하였다. 오버 코팅 물질로는 실리콘계 유무기하이브리드 투명하드 코팅을 적용하였다. 연구결과 오버 코팅층과 CNT 코팅층과의 젖음성이 물성 향상에 가장 많은 영향을 끼치는 것을 관찰하였고, 특히 젖음성이 증가할수록 투과도와 전기전도도가 향상되는 것을 확인하였다. 또한 고온 고습 환경에서 240시간 이상 내구성 테스트 결과, 저항률 변화가 1.1 이하인 것을 확인하였다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 춘계학술발표논문집
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• pp.152-157
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• 2006

Printing mottle of coated paper is one of the most common and the most difficult problems in offset printing. For a high quality printing, development of new paper coating technologies to prevent print mottle is required. This research focused on improvement of printing mottle. Effects of base paper properties, coating color composition and printing conditions such as printing pressure and printing speed on printing mottle were investigated with RI tester and IGT tester.

• The Korean Journal of Ceramics
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• 제3권4호
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• pp.249-252
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• 1997

Highly oriented ZnO thin films were fabricated by dip-coating technique using zinc acetate 2-methoxyethanol 2-aminoethanol solution as starting materials, and effects of substrates on the film's orientation were investigated. Product films were obtained by prefiring at 300, 400, 500 and 550℃ for 10 min, followed by final heat-treatment at the same temperatures as prefiring for 1h. c-axis oriented films on glass substrates were prepared by heat treatment of prefiring films at 300-550℃, while films on alumina showed polycrystalline structure. Films with c-axis orientation exhibited lower specific resistivities than those of polycrystalline films with partial crack and pore.