• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.307-310
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• 2007

We describe effects of ionic and neutral additives on phase and structural behavior of the lyotropic chromonic liquid crystals used in preparation of optical elements such as polarizers and compensators.

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2044-2050
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• 2013

A series of poly(glycerol-succinic acid) dithiocarbamate and 1,3,4-thiadiazole dendrimers, which have potential as anti-wear oil additives, were synthesized. Their anti-wear properties in three different oils (100N, DB-51, and soybean) were evaluated using a four-ball wear tester. The results indicated that thiocarbamate dendrimers have moderate anti-wear properties in DB-51 oil, and 1,3,4-thiadiazole dendrimers exhibited good anti-wear properties in 100N and DB-51 oils. However, dithiocarbamate and 1,3,4-thiadiazole dendrimers were not effective anti-wear additives in soybean oil.

• Elastomers and Composites
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• 제54권3호
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• pp.188-200
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• 2019

Rubber articles contain various organic additives such as antidegradants, curing agents, and processing aids. It is important to extract and analyze these organic additives. In this paper, various extraction methods of organic additives present in rubber composites were introduced (solvent extraction, Soxhlet extraction, headspace extraction, and solid-phase microextraction), and the extracts were characterized using gas chromatography/mass spectrometry (GC/MS). Solvent and Soxhlet extractions are easy-to-perform and commonly used methods. Efficiency of solvent extraction varies according to the type of solvent used and the extraction conditions. Soxhlet extraction requires a large volume of solvent. Headspace sampling is suitable for extracting volatile organic compounds, while solid-phase extraction is suitable for extracting specific chemicals. GC/MS is generally used for characterizing the extract of a rubber composite because most components of the extract are volatile and have low molecular weights. Identification methods of chemical structures of the components separated by GC column were also introduced.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.272-277
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• 2004

The primary aim of this study is to investigate new semi-abrasive free slurry including acid colloidal silica and hydrogen peroxide for copper chemical-mechanical planarization (CMP). In general, slurry for copper CMP consists of colloidal silica as an abrasive, organic acid as a complex-forming agent, hydrogen peroxide as an oxidizing agent, a film forming agent, a pH control agent and several additives. We developed new semi-abrasive free slurry (SAFS) including below 0.5％ acid colloidal silica. We evaluated additives as stabilizers for hydrogen peroxide as well as accelerators in tantalum nitride CMP process. We also estimated dispersion stability and Zeta potential of the acid colloidal silica with additives. The extent of enhancement in tantalum nitride CMP was verified through anelectrochemical test. This approach may be useful for the application of single and first step copper CMP slurry with one package system.

• 한국구조물진단유지관리공학회 논문집
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• 제6권1호
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• pp.159-169
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• 2002

This study is intended to discuss the application of expansive additives for concrete to improve the durability of precast concrete box culvert by inducing the chemical prestress. The precast concrete box culvert using expansive cement are tested to verify the effect of expansive additives. The results show that the initial cracking load and yielding load of the expansive cement numbers are increased when they are compared with those of the normal concrete. In the prototype precast concrete box culvert experiment, initial crack control effect and strength of joint are increased, but the deflection is decreased by expansive cement. Brides, reinforcement ratio is decreased about 14.6 percent in compering with the case of using normal cement. If can be the concluded that the use of expansive additives to induce the chemical prestress was improve the durability in concrete box culvert.

• 한국환경과학회지
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• 제19권11호
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• pp.1385-1390
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• 2010

Repeated additions of untreated slurry to soil affected ecology and caused high levels of heavy metal in soil and ground water. The objective of this study was to evaluate heavy metal from hanwoo slurry with ferrous sulfate ($FeSO_4{\cdot}7H_2O$), aluminum sulfate [$Al_2(SO_4)_3{\cdot}14H_2O$, alum] and aluminum chloride ($AlCl_3{\cdot}6H_2O$) as a way to improve environmental management in hanwoo industry. The treatment rates, which were incorporated totally within the hanwoo slurry, were 1.0 g and 1.5 g of ferrous sulfate, alum and aluminum chloride/25 g of hanwoo slurry. The various rates of chemical additives significantly increased dry matter (9.98~13.94%) and decreased pH (3.48~6.52) compared with the controls. The use of chemical additives decreased Fe (11~29%), Al (7~12%), Zn (13~36%), and Cu (4~32%) contents, except for Fe in hanwoo slurry with ferrous sulfate and Al in hanwoo slurry with alum and aluminum chloride. In addition, the reduction in heavy metal should be associated with reduction in pH. In conclusion, the results of this study suggest that alum and aluminum chloride additives at rate of 1.5 g were cost-effective management practice that significantly reduces heavy metal from hanwoo slurry, while it may be improved environmental management.

• KCI Concrete Journal
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• 제13권1호
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• pp.43-51
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• 2001

Although portland cement concrete is one of the most universal construction materials, it has some disadvantage such as shrinkage, which is an inherent characteristic. Because of this shrinkage, combined with the low tensile strength of the material, cracks of varying sizes can be found in every reinforced concrete. To prevent this cracking, keeping the concrete in compression by mechanical prestress has been used. This study discusses application of expansive additives for concrete to improve the serviceability of precast concrete box culvert by inducing chemical prestress. For this purpose, both expansive concrete slabs and normal concrete slabs are tested to verify the effect of expansive additives. Then the failure tests of the fullscale precast box culverts were carried out and the critical aspects of the structural behavior were investigated. The result of the material testis shows that the optimal proportion of expansive additives is 13 percent of cement weight, and the properties of expansive concrete are the same as those of normal concrete in that proportion. Both the experimental cracking load and service load of the expansive concrete members are increased in comparison with those of the normal concrete, but the ultimate load is decreased slightly. In addition to the above results, the deformation of expansive concrete member is lets than that of normal concrete member, and permanent strain which results from cyclic load is decreased. It can be concluded that the use of expansive additives to induce chemical prestress in precast concrete box culvert greatly improves the serviceability.

• KSBB Journal
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• 제22권4호
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• pp.213-217
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• 2007

첨가제가 단백질 약물 방출 속도 및 약물 제제 제조 및 구조에 미치는 영향을 고찰하였다. 친수성 첨가제인 D-sorbitol의 경우 친유성 첨가제보다 단백질 약물 방출 속도를 감소시킬 수 있었으며 최적의 농도는 3% (w/v)로 나타났다. 또한 제제 제조시 점도를 낮게 유지할 뿐 아니라 상분리 없는 균일한 pluronic 용액상태를 유지하여 약물이 첨가될 경우에 균일한 약물제제를 만들 수 있었다. 한편 D-sorbitol은 pluronic 수용액의 CMC를 낮추고 마이셀 표면에 작용하여 구조를 강화하는 역할을 수행하는 것으로 보인다. 따라서 pluronic 제제에 D-sorbitol을 첨가하여 단백질 약물의 안정성을 향상시키고 효과적인 약물전달 시스템을 설계할 수 있었다.

• Korean Chemical Engineering Research
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• 제54권6호
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• pp.723-733
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• 2016

반도체 배선 미세화에 의한 한계를 극복하기 위해 실리콘 관통 비아(through silicon via, TSV)를 사용한 소자의 3차원 적층에 대한 연구가 진행되고 있다. TSV 내부는 전해도금을 통해 구리로 채우며, 소자의 신뢰성을 확보하기 위해 결함 없는 TSV의 채움이 요구된다. TSV 입구와 벽면에서는 구리 전착을 억제하고, TSV 바닥에서 선택적으로 구리 전착을 유도하는 바닥 차오름을 통해 무결함 채움이 가능하다. 전해 도금액에 포함되는 유기 첨가제는 TSV 위치에 따라 국부적으로 구리 전착 속도를 결정하여 무결함 채움을 가능하게 한다. TSV의 채움 메커니즘은 첨가제의 거동에 기반하여 규명되므로 첨가제의 특성을 이해하는 연구가 선행되어야 한다. 본 총설에서는 첨가제의 작용기작을 바탕으로 하는 다양한 채움 메커니즘, TSV 채움 효율을 개선하기 위한 평탄제의 개발과 3-첨가제 시스템에서의 연구, 첨가제 작용기와 도금 방법의 수정을 통한 채움 특성의 향상에 관한 연구를 소개한다.

• Journal of Pharmaceutical Investigation
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• 제26권4호
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• pp.281-289
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• 1996

In our previous work, we have studied the effect of lactose and sodium alginate (SA) on the rate of release of 5-fluorouracil (5-FU) from ethylene-vinyl acetate (EVA) matrix. These hydrophilic additives promoted the rate of 5-FU release and the increase in rate was larger when SA was used. Both additives showed better ability to increase the rate than 5-FU itself. In this paper, we extended our study to another hydrophilic additive, Carbopol 940 (CP). Compared to SA or lactose, CP increased the rate of 5-FU release markedly. Release rate increased as the loading amount and the pH of the release medium increased. After release experiment, matrix volume increased up to 15 times of that before release experiment, depending on the amount of CP dispersed in the matrix and the pH of the release medium. On the other hand, the volume of the matrix containing lactose or SA decreased. The weight changes of the dry matrix before and after release experiment imply that CP is not released out of the matrix, to the contrary of lactose and SA. Scanning electron microscope study clearly showed that large cavities and pores are generated on the surface and the inside of the matrix. These results indicate that the mechanism by which CP increases the release rate is quite different from that of monomeric additives such as lactose or SA.