• Restorative Dentistry and Endodontics
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• 제22권1호
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• pp.396-412
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• 1997

The purpose of this study is to observe the corrosion characteristics of five dental amalgams(CAULK FINE CUT, OPTALLOY II, DISPERSALLOY, TYTIN, and VALIANT) in the solutions with fluoride compound through the anodic polarization curve obtained by using a potentiostat. After each amalgam alloy and Hg being triturated, the triturated mass was inserted into the cylindrical metal mold, and condensed by hydraulic pressure(160 kg/$cm^2$). Each specimen was removed from the metal mold. Specimens were polished with the silicone carbide grinding paper 24 hours after condensation and stored at room temperature for 1 week. The anodic polarization curves were employed to compare the corrosion behaviours of the amalgams in 0.9 % saline solution and in the saline solutions with 2.2 ppm, 0.05 %, 2 % NaF, and 8 % $SnF_2$ at $37^{\circ}C$ with 3-electrode potentiostat. After the immersion of specimen in electrolyte for 30 minutes, the potential scan was begun. The potential scan range was -1500m V to + 800m V(vs. S.C.E.) in the working electrode and the scan rate was 50 mV/sec. The results were as follows, 1. The corrosion potential, the potential of anodic current peak, and transpassive potential in the saline solutions with NaF shifted to lower direction than those in normal saline solution, and the current density in the saline solutions with NaF was higher than that in normal saline solution. The differences were increased as the concentrations of NaF became higher. 2. The corrosion potential and transpassive potential in the saline solution with $SnF_2$ shifted to higher direction than those in normal saline solution, and the current density in the saline solution with $SnF_2$ was higher than that in normal saline solution after the corrosion potential. The anodic polarization curves in the saline solution with $SnF_2$ had no outstanding anodic current peak. 3. The corrosion potentials for high-copper amalgams were much higher than those for CAULK FINE CUT and OPTALLOY II in normal saline solution, but, as the concentrations of fluoride compound became higher, the differences in corrosion potentials between them were decreased. The corrosion potentials had the similarity in the saline solution with 2% NaF or 8% $SnF_2$. 4. The current density for TYTIN was the lowest among the others in normal saline solution and in the saline solution with 2.2 ppm or 0.05 % NaF. 5. There was no significant difference in current density between Pd-enriched VALIANT and other high-copper amalgams.

• 식물병연구
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• 제15권3호
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• pp.217-221
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• 2009

Fludioxonil은 미국 EPA에 의해 저독성(reduced-risk) 살균제로 분류되었으며, 이 살균제는 Pseudomonas pyrrocinia가 생산하는 항균 물질인 pyrrolnitrin을 선도 물질로 하여 합성하였다. 본 연구에서는 상추 품종, 기주 식물의 생육 시기, Botrytis cinerea 포자농도, 접종원의 영양분 농도 등의 발병 조건에 따른 fludioxonil의 상추 잿빛곰팡이병에 대한 방제효과를 온실에서 실험하였다. 상추의 생육시기에 따른 fludioxonil 방제효과를 실험한 결과, 2 ${\mu}g$/ml 처리구는 어린 유묘에서 잿빛곰팡이병 방제효과가 더 높았으나, 10 ${\mu}g$/ml 이상 농도에서는 생육 시기에 따른 방제효과의 차이는 거의 없었다. 또한 fludioxonil 10 ${\mu}g$/ml 이상 농도 처리구는 B. cinerea의 포자 농도(2.5$\times$10개/ml 부터 $2{\times}10^6$ 개/ml까지)에 관계없이 모두 우수한 방제효과를 나타냈다. 반면에 fludioxonil 2 ${\mu}g$/ml은 접종원의 포자농도가 높을수록 낮은 방제효과를 보였다. 그리고 영양분농도에 따른 fludioxonil의 잿빛곰팡이병 방제효과를 실험한 결과, potato dextrose broth의 농도가 낮을수록 fludioxonil은 상추 잿빛곰팡이병에 대한 높은 방제효과를 나타냈다. 이상의 결과로부터 살균제 fludioxonil은 상추 잿빛곰팡이병에 대한 효과적인 살균제임을 알 수 있었으며, 다만 낮은 농도에서는 발병 조건에 따라 다소 낮은 방제효과를 나타낼 수 있을 것이다.

• 한국재료학회지
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• 제14권5호
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• pp.322-327
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• 2004

Copper-based leadframe sheets were oxidized in two kinds of hot alkaline solutions to form brown-oxide or black-oxide layer on the surface. The oxide coated leadframe sheets were molded with epoxy molding compound (EMC). After post mold curing, the oxide-coated EMC-leadframe joints were machined to form sandwiched Brazil-nut (SBN) specimens. The SBN specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under mixed-mode (mode I + mode II) loading conditions. Fracture surfaces were analyzed by various equipment to investigate failure path. The results revealed that the failure paths were strongly dependent on the oxide type. In case of brown oxide, hackle-type failure was observed and failure path lay near the EMC/CuO interface with a little inclining to CuO at all case. On the other hand, in case of black oxide, quite different failure path was observed with respect to the distance from the tip of pre-crack and phase angle. Different failures occurred with oxide type is presumed to be due to the difference in microstructure of the oxides.

• 한국식품저장유통학회지
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• 제15권6호
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• pp.791-795
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• 2008

아황산가스 발생제를 자가 제조하여 포도의 저장 중 병해발생 방지에 이용하는 방법을 확립하기 위하여 sulfite 화합물의 아황산가스 발생 정도와 지속 기간을 측정하고 아황산가스 발생 조절 및 간이 검출 방법을 개발하였다. 포도의 저장 중 잿빛곰팡이병을 일으키는 B. cinerea의 포자 발아와 균사생장은 각각 400 ppm과 3200 ppm의 아황산가스 농도 조건에서 억제되었다. 5종류의 sulfite 및 bisulfite 화합물 중 sodium hydrosulfite는 아황산가스 발생량이 가장 높았으며 이를 비닐 포장하여 포장의 pinhole수를 조절하거나 산 또는 알카리의 pH 조절제를 혼합하면 가스 발생량과 발생 지속 기간을 조절할 수 있었다. Malachite green 용액은 아황산가스에 의해 정량적으로 탈색되어 아황산가스 검출에 이용할 수 있었으며 여과지에 흡수하여 건조할 경우 아황산가스 검출지로 활용할 수 있었다. MBA 포도를 속효성과 지효성의 아황산가스 발생제를 동시에 처리하여 저온 저장할 경우 병해 발생을 감소시킬 수 있었다.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.2993-2999
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• 2015

강 제조 회사들은 연속주조금형의 표면을 보호하기 위해 Ni-B 또는 Ni-Co 합금 도금을 적용하고 있으며, 도금 층에 균열이 생기게 하는 황을 함유한 사카린 윤활제를 사용하고 있다. 균열 및 인장 응력을 유발하는 것은 Ni-S 화합물로 여겨진다. Ni-Mn-B 삼원합금은 Ni-S 화합물이 형성되기 이전에 Mn-S 화합물을 형성하여 균열을 억제하기 위해서 개발되었으나, Ni-Mn-B 합금 도금에 관한 국내나 해외 기준이 없다. 그리하여 새로이 개발된 Ni-Mn-B 도금을 평가하기 위한 신뢰성 평가기준을 개정하려한다. 가속수명시험을 개발하기 위해 FMEA(고장형태 영향분석)가 사용되어 도금의 주요 파괴 원인을 분석하였다. Ni-Mn-B 신뢰성 기준은 가속수명시험 방법을 포함하였고, 기본 성능 시험과 환경시험, 가속수명시험으로 분류되었으며, 80% 신뢰수준으로 B10수명 1 000시간을 보장하도록 고안되었다.

• 한국기계가공학회지
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• 제14권2호
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• pp.87-92
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• 2015

The injection molding process is widely used in the production of most plastic products. In order to make metal-colored plastic products like those found in modern luxury home alliances, metallic pigments are mixed with a basic resin material for injection molding. However, process control for metal-colored plastic products is extremely difficult due to the non-uniform melt flow of the metallic resin pigments. In this study, the effect of process parameters on the quality of a metal-colored plastic product is evaluated. A rapid mold cooling method using a compressed cryogenic fluid is also proposed to decrease the content of undesired compounds within the plastic product.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 A
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• pp.303-305
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• 1997

The advantage of application polymer instead of conventional porcelain as the housing material for arrester is that light weight, shorter section length of arrester would be possible due to the use of an insulated hanger (mold compound). also, polymer arrester has very good characteristics in design versatility as well as excellent resistance to moist ingress and pollution performance. The finite element method is widely used to calculate for electromagnetic devices. In this paper, we perform the each conditional analysis of PC with an advanced graphical user interface(GUI) using the vector fields simulator. And we try to analyze electromagnetic fields through the conventional two dimensional analysis in case of high voltage contamination on the electrode of a arrester.

• 한국재료학회지
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• 제18권4호
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• pp.181-186
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• 2008

In this study, tantalum (Ta) compacts were fabricated in a spark plasma sintering (SPS) process and their microstructure and mechanical properties were investigated. Ta compacts with a density of 99% were successfully fabricated by controlling the sintering conditions of the current and the temperature. The density and hardness were increased as the sintering temperature increased. The $Ta_2C$ compound was observed at the surface of the compacts due to the contact between the Ta powder and graphite mold during the sintering process. The main fracture mode showed a mixed type with intergranular and transgranular modes having some roughness.

• 마이크로전자및패키징학회지
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• 제9권4호
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• pp.31-34
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• 2002

For the mold die sticking mechanism, the major explanation is that the silica as a filler in EMC (epoxy molding compound) wears die surface to be roughened, which results in increase of adhesion strength. As the sticking behavior, however, showed strong dependency on the EMC models based on the experimental results from different semiconductor manufacturers, chemisorption or acid-base interaction is apt to be also functioning as major mechanisms. In this investigation, the plasma source ion implantation (PSII) using $O_2, N_2$, and $CF_4$ modifies sample surface to form a new dense layer and improve surface hardness, and change metal surface condition from hydrophilic to hydrophobic or vice versa. Through surface energy quantification by measuring contact angle and surface ion coupling state analysis by Auger, major governing mechanism for sticking issue was figured out to be a complex of mechanical and chemical factors.

• 한국재료학회지
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• 제15권1호
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• pp.1-5
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• 2005

Copper-based leadframe sheets were immersed in two kinds of hot alkaline solutions to form brown-oxide or black-oxide layer on the surface. The oxide-coated leadframe sheets were molded with epoxy molding compound (EMC). After post mold curing, the oxide-coated EMC-leadframe joints were machined to form sandwiched double-cantilever beam (SDCB) specimens. The SDCB specimens were used to measure the fracture toughness of the EMC/leadframe interfaces under quasi-Mode I loading conditions. Fracture surfaces were analyzed by various equipment to investigate failure path. The present paper deals with the failure path, and the cause of the failure path formation with an adhesion model will be treated in the succeeding paper.