• 펄프종이기술
• /
• 제37권4호통권112호
• /
• pp.8-17
• /
• 2005

WCT (Wet compaction test) is a new fiber evaluation method developed recently by Seo and its test results can be used as a predictor for pulp quality and its paper property Bleached chemical pulps (SwBKP, HwBKP), recycled pulp (OCC), and mechanical pulp (BCTMP) were used for the furnishes to be tested by WCT We compared the WCT results to conventional fiber evaluation tests such as WRV (Water Retention Value), free ness, and fiber length in this study, and found that WCT always gave better regression coefficients in relation to pulp quality (drainage), and paper properties (density, tensile, tear, and burst strength). WCT may be used on-line in papermachine.

• 한국세라믹학회지
• /
• 제42권10호
• /
• pp.645-648
• /
• 2005

To fabricate a (100) silicon hard master, we used anisotropic wet etching for the embossing. The etching chemical for the sili­con wafer was a TMAH 25$\%$ solution. The anisotropic wet etching produces a smooth sidewall surface inclined at 54.7°, and the surface roughness of the fabricated master is about 1 nm. After spin coating an organic-inorganic sol-gel hybrid resin on a silicon substrate, we used the fabricated master to form patterns on the silicon substrate. Thus, we successfully obtained patterns via the hot embossing technique with the (100) silicon hard master. Moreover, by using a single hydrophobic surface treatment of the master, we succeeded in achieving uniform surface roughness of the embossed patterns for more than ten embossments.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.366-366
• /
• 2016

Nanoscale observation of attachment systems of animals has revealed various exquisite multiscale architectures for essential functions such as gecko's locomotion, beetles' wing fixation, octopuses' sucking and crawling. In particular, the hierarchical 3-dimensional hexanonal nano-architectures in the tree frog's adhesion is known to have the capability of the enhancement of adhesion forces on the wet or rough surfaces due to the conformal contacts against rough surfaces and water-drainable micro channels. Here, we report that tree frog-inspired patches using unique artificial 3-dimensional hexagonal structures can be exploited to form reversibly enhanced adhesion against various highly curved and rough surfaces in dry and wet condition. To investigate the adhesion effect of micro-channels, we changed the arrangement of microstructure and spacing gaps between micro-channels. In addition, we introduced the 3-dimensional hexagonal hierarchical architectures to artificial patches to enhance to conformal contacts on the various rough surfaces such as skin and organs. Using the robust adhesion properties, we demonstrated the self-drainable and comfortable skin-attachable devices which can measure EKG (electrokardiogramme) for in-vitro diagnostics. As a result, bio-inspired programmable nano-architectures can be applied in versatile devices such as, medical patches, skin-attachable electronics etc., which would shed light on future smart, directional and reversible adhesion systems.

• Elastomers and Composites
• /
• 제55권3호
• /
• pp.167-175
• /
• 2020

Various studies have been conducted to improve silica dispersion of silica filled tire tread compounds; among them, silica wet masterbatch (WMB) technology is known to be suitable for manufacturing silica filled compounds that have high silica content and high dispersibility. Till now, the WMB study is focused on the natural rubber (NR) or emulsion styrene-butadiene rubber (ESBR) that does not have a silica-affinity functional group, and a study of NR or ESBR having a silica-affinity functional group is still not well known. Unlike the dry masterbatch technology, the WMB technology can solve the problems associated with the high Mooney viscosity when applied to silica-friendly rubber. However, a coagulant suitable for each functional group has not yet been determined. Therefore, in this study, different coagulant applied silica WMB was prepared by applying calcium chloride, sulfuric acid, acetic acid, and propionic acid by using a carboxyl group functionalized reversible addition fragmentation chain transfer ESBR. The evaluation of the WMB compounds revealed that the calcium chloride added WMB compound showed excellent silica dispersion, abrasion resistance, and rolling resistance.

• Bulletin of the Korean Chemical Society
• /
• 제32권1호
• /
• pp.225-228
• /
• 2011

Poly(4-vinylpyridine)-supported $Br{\phi}nsted$ acids (P4VP-HX) were prepared by wet impregnation technique. These supported acids were found as efficient heterogeneous green catalysts for acetylation of alcohol, amine and phenol with different catalytic activities. The wide application of P4VP-HX as reusable solid acid catalyst in organic reactions is possible because of its simple preparation and handling, stability, simple work up procedure.

• 분석과학
• /
• 제16권2호
• /
• pp.117-124
• /
• 2003

고온 건식공정의 사용후핵연료 산화분말 ($U_3O_8$)과 경 중수로 연계 핵연료 제조공정의 $UO_2$ 소결체 물성 이해에 필요한 Oxygen/Metal 비를 습식 및 건식 분석방법으로 측정하였다. $UO_2$ 분말에 핵분열생성물 원소의 산화물을 일정량 첨가하고 $1,700^{\circ}C$의 수소분위기에서 소결시켜 20,000~60,000 MWd/MtU 연소도 범위의 사용후핵연료와 화학조성이 유사한 모의 사용후핵연료를 제조하였다. 습식법에 의한 O/M 비 측정을 위하여 혼합산 (10 M HCl : 8 M $HNO_3$, 2.5:1 V/V)에 의한 가압산분해법으로 모의 사용후핵연료를 용해하고 우라늄과 핵분열생성물 원소를 추출 크로마토그래피로 분리한 후 금속원소의 총량을 유도결합플라스마 원자방출분광분석법으로 결정하였다. 또한 $UO_2$가 산화될 때의 무게변화를 열중량 무게분석법 (thermogravimetric)으로 측정하여 O/M비를 계산하고 습식법으로 얻은 결과와 비교하였다. $Mo_{0.4}-Ru_{0.4}-Rh_{0.1}-Pd_{0.1}$ 합금이 O/M비 측정에 미치는 영향을 조사하였다.

• 한국진공학회지
• /
• 제17권1호
• /
• pp.73-79
• /
• 2008

투명 전도성 산화물 전극(transparent conductive oxide electrodes)에 적용하기 위하여 RF 마그네트론 스퍼터링 방법에 의해 유리 기판 위에 산화아연 박막을 증착하였다. 투명 전극으로써 응용되기 위한 최적의 조건으로 기판온도를 상온으로 유지하고 RF power 200 W, 타겟과 기판사이의 거리(Dts)가 30 mm일 때 증착된 산화아연 박막으로부터 가장 낮은 비 저항값($7.4{\times}10^{-3}{\Omega}cm$)을 얻어 낼 수 있었으며, 85% 이상의 높은 투과율을 만족하는 박막을 얻을 수 있었다. 실질적인 소자로써의 응용을 위해 photo lithography를 통한 pattern을 형성, 습식 식각을 통하여 그 특성을 알아보고자 하였다. 습식 식각에서 사용된 식각용액(etchant)으로는 다양한 산 용액(황산, 옥살산, 인산)을 사용하였으며, 산의 농도 변화에 따른 식각특성과 식각시간 및 식각 이미지(표면형상)의 변화를 알아보았다. 결과적으로 산화아연의 습식식각은 산의 종류와 무관하게 산 용액의 농도(즉, pH)에 크게 의존하며, pH가 증가함에 따라 식각율이 지수함수적으로 감소하고 아울러 다양한 식각 이미지가 나타남을 최초로 고찰할 수 있었다.

• Korean Chemical Engineering Research
• /
• 제58권3호
• /
• pp.474-479
• /
• 2020

유리기판의 박막화를 위한 식각액을 제조하였고, 습식 식각액의 주성분으로 HF를 사용하였다. HF를 기본으로 한 식각액에 HCl, HNO₃, H₂SO₄와 같은 강산과 구연산과 같은 카르복실산 그리고 여러 종류의 아미노산을 첨가물로 각각 사용한 식각액으로 유리의 식각속도와 표면형상의 변화를 측정하였다. 강산의 종류와 상관없이 첨가량이 증가함에 따라 선형적으로 유리의 식각속도가 증가하였으며 유리표면의 슬러지 제거효과도 나타내었다. HCl이 함유된 식각액이 식각속도의 증가율과 슬러지 제거 효과에서 다른 강산보다 효율적인 결과를 보였다. 카르복실산의 첨가는 식각속도에 영향을 크게 주지 않으나 슬러지 제거효과를 보였다. 하지만 아미노산을 첨가한 경우에는 식각속도의 변화와 슬러지 제거 효과가 크지 않았다.

• 콘크리트학회지
• /
• 제9권1호
• /
• pp.143-151
• /
• 1997

전기로 집진 분진상의 중금속(Pb, $Cr^{6+}$, Cu, Cd, Zn)을 함침시킨 규조토를 열처리방법($750^{\circ}C$-30분)으로 활성화하였다. 활성규조토로 일반시멘트 모르터의 시멘트양을 중량비로 0%, 2.5%, 5.0%, 10%, 20%까지 대체하고 압축강도와 화학저항성을 조사하였다. 화학저항성 조사에는 습윤건조반복실험(Wetting /Drying Cycle)과 화학침식저항성($H_2SO_4,\; CaCl_2,\; MgSO_4$)이 포함되었다. 결과에 의하면 일반시멘트 모르터에 활성규조토를 시멘트에 10%까지 치환하여 갈수록 압축강도(28일)는 증가하였다. 최고의 압축강도는 활성규조토가 10%까지 치환하였을 때 $496kgf/cm^2$이었으며, 활성규조토가 전혀 혼합되지 아니한 시멘트 모르터의 압축강도($391kgf/cm^2$)보다 약 275까지 증가되었다. 이때 중금속들은 99% 이상의 고정율을 보였으며 Wet/Dry cycle 및 화학침식저항성에서도 활성규조토가 혼합된 시멘트 모르터가 일반 시멘트 모르터보다 훨씬 높은 저항성을 보였다.

• Bulletin of the Korean Chemical Society
• /
• 제24권3호
• /
• pp.363-368
• /
• 2003

The major ionic components of precipitation collected at the 1100 Site of Mt. Halla and Jeju city have been determined. The reliability of the analytical data was verified by the comparison of ion balances, electric conductivities and acid fractions; all of their correlation coefficients were above 0.94. Ionic strengths lower than $10^{-4}$ M were found in 53% of the 1100 Site samples and 28% of the Jeju city samples. Compared with other inland areas, the wet deposition of $Na^+,\;Cl^-\;and\;Mg^{2+}$ was relatively larger, but that of $NH_4^+,\;nss-SO_4^{2-}$(non-sea salt sulfate) and $NO_3^-$ was lower. Especially the wet deposition increase of $Ca^{2+}$ in the spring season supports the possibility of the Asian Dust effect. The acidification of precipitation was caused mostly by $SO_4^{2-}\;and\;NO_3^-$ in the Jeju area, and the organic acids have contributed only about 7% to the acidity. The neutralization factors by NH₃were 0.47 and 0.48, and that of CaCO₃was 0.31 and 0.25 at the 1100 Site and Jeju city, respectively. Investigation into major influencing sources on precipitation components by factor analysis showed that the precipitation at the 1100 Site had been influenced mostly by an anthropogenic source, followed by soil and seawater sources. The precipitation at Jeju city was mainly influenced by oceanic sources, followed by anthropogenic and soil sources.