• 한국세라믹학회지
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• 제38권3호
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• pp.207-211
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• 2001

The effects of the sintering atmosphere and Ni content on t도 densification of TiB$_2$-Ni have been investigated. TiB$_2$powder compacts containing 10, 20, and 30 wt% Ni were liquid-phase sintered at 1500-1$700^{\circ}C$ in vacuum or in flowing Ar. The densification was enhanced as Ni content increased. For a given Ni content, the densification was faster in compacts in compacts with larger grain size. These densification behaviors agree well with the prediction of the recently developed pore-filling theory. For samples containing high Ni contents, 80TiB$_2$-20Ni and 70TiB$_2$-30Ni, the densification was faster in vacuum than in Ar. In particular, 70TiB$_2$-30Ni was fully densified at 1$700^{\circ}C$ for 60min in vacuum. The suppressed densification in Ar was due to the entrapped Ar in the isolated pores. On the other hand, for 90TiB$_2$-10Ni, the Ar-sintering resulted in higher densification than did the vacuum-sintering. This result was attributed to the suppression of Ni volatilization by the Ar in the furnace and a retarded isolation of pores due to the limited amount of liquid in the sample. Therefore, vacuum sintering is recommended for the preparation of TiB$_2$-Ni with a high Ni content while Ar sintering is recommended for the preparation of TiB$_2$-Ni with a low Ni content.

• 한국식품저장유통학회지
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• 제4권3호
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• pp.259-264
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• 1997

To improve freshness of onion(Allium cepa), it was packed with various packaging films and stored at 5$^{\circ}C$ until 52 days. During the storage, internal gas composition, weight loss, spout ratio, decay ratio, surface color were determined. The used packaging films are two-perforated LDPE (control), LDPE, CPP/OPP/PE, Nylon/PE and Ag-zirconium filled LDPE. Onions were prepared by peeling or dipping in GFSE(grape fruit seed extract) and packed under vacuum or atmosphere with the selective films. Anaerobic condition was shown in the Nylon/PE package after 4 days and, thus weight loss, sprout ratio and color were considerably poor. All onions in the vacuum package after 15 days were spouted. Onions in CPP/OPP/PE and functional film(Ag-zirconium filled LDPE) package showed aerobic respiration until 52 days. Thus, the quality of onions in these packages was superior to the control.

• 한국세라믹학회지
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• 제28권6호
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• pp.437-442
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• 1991

Temperature and atmosphere dependence of electrical conduction of the metal Cu, Ag, Au films, vaccum evaporated on glass, was investigated. The structural changes of the metal films were examined by SEM and high temperature XRD. The electrical resistance slightly increased with initial temperature increase up to the inflection point and decreased to minimum value, after this rapidly increased with further temperature increased below minimum. These phenomena were caused by the thermally induced film failure as a result of the mass transport. The temperature for the film failure increased in the order of O2, Air, Vacuum, N2, Ar in Cu, Ag films and Air, Vacuum, N2, Ar in Au film. The increase of resistance at the lower temperature range was attributed to the lattice distortion by disordered crystal structure, while the decreasing resistance was attributed to the removal of structural defects and film densification.

• 대한치과기공학회지
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• 제32권4호
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• pp.337-340
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• 2010

Purpose: This study was performed to compare sintering conditions for fabrication of porous Ti implant. Methods: The porous Ti implant samples were fabricated by sintering of spherical Ti powders in vacuum and atmosphere conditions. Surface morphology, composition and phase were analyzed by FE-SEM, EDX and XRD. Results: Sintered Ti implant in the vacuum consisted of particles connected in three dimensions by clear necking without excessive oxide layers. However, sintered Ti implant in atmosphere was formed excessive oxide layers with non-stoichiometric compounds. Conclusion: The porous Ti implant can be sintered in vacuum condition preferably.

• 한국분말재료학회지
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• 제5권4호
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• pp.265-272
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• 1998

For the purpose of investigating the effect of sintering atmosphere and carbon addition on sintered density and microstructural characteristics, the M3/2 grade high speed steel powders with the addition of carbon are sintered in vacuum and $20%H_2/79%N_2/l%CH_4$ gas atmosphere. With the addition of 0 wt%C, 0.45wt%C and 1.15 wt%C the optimum sintering temperatures decrease down to $1260^{\circ}C$, $1210^{\circ}C$ and $1150^{\circ}C$ respectively for the vacuum sintered specimen, and also decrease down to $1130^{\circ}C$, $1120^{\circ}C$ and $1115^{\circ}C$ for the gas sintered specimen. The threshold temperatures for full densification decrease steeply with increasing carbon content of the sintered specimen, while this temperatures are slowly decreased at high carbon content. The vacuum sintered specimen shows the primary carbides of MC and $M_6C$ type at the optimum sintering temperature, and eutectic carbides of $M_2C$ and Fe-Cr type are produced in the oversintered specimen. The gas sintered specimen exhibits M6C and Fe-Cr type primary carbides at the optimum sintering temperature. The eutectic carbides of $M_6C$ and Fe-Cr type and MX type carbonitride are shown for the oversintered specimen in the gas atmosphere. The hardness of gas sintered specimen shows high value of 830-860 Hv due to the increment of carbide precipitation.

• 한국해양공학회지
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• 제27권2호
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• pp.69-74
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• 2013

In this study, the crack healing effects of $Al_2O_3$ ceramics based on the heat treatment conditions were investigated. The influence of the additive amounts of SiC nanoparticles and the cycling process of indentation-heat treatment on the crack healing effect of $Al_2O_3$ ceramics were also examined. Three-point bending tests were carried out and the morphological changes in the fracture surface were observed by using FE-SEM. As a result, heat-treated samples in a vacuum or air atmosphere showed improved bending strengths compared to un-heat treated samples. This means that cracked specimens can be healed by heat treatment in a vacuum or air atmosphere. The crack healing effect of $Al_2O_3$ ceramics that were heat treated in an air atmosphere was much higher than that of those heat treated in a vacuum. After heat treatment, the $Al_2O_3$ ceramics with 30 wt% SiC nanoparticles showed a higher bending strength than those with 15 wt% SiC. The cyclic indentation and heat treatment did not remarkably affect the crack healing effect. The SEM images showed that the median crack, indenter mark on the surface, and pores in the fracture surface of a specimen almost disappeared after being heat treated in an air atmosphere.

• 마이크로전자및패키징학회지
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• 제7권1호
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• pp.7-12
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• 2000

유리 프릿과 유리 튜브를 사용하지 않고 FED, VFD와 PDP를 봉입할 수 있는 기반 기술로서, 진공 내에서 두 장의 sodalite유리 기판들을 정전 열 접합하는 공정을 연구하였으며, 대기 중에서 정전 열 접합한 기판 쌍들과 비교하여 접합 특성을 비교.분석하였다. 진공 분위기 내에서 비정질 실리콘 interlayer를 이용하여 접합된 유리 기판 쌍의 경우, 대기압의 경우와 비교할 때 동일한 접합 온도와 전압에서 접합 강도가 상대적으로 낮은 것으로 측정되었으며, 산소 분위기의 경우 접합 강도가 증가하였음을 확인하였다. XPS와 SIMS를 통한 비정질 실리콘 표면 및 유리기판 표면의 조성 변화 분석으로부터, 진공내에서 산소가 부족함으로써 정전 열 접합 과정에서 부가적으로 수반되는 실리콘 산화막이 불완전하게 형성된 것으로 해석 할 수 있다.

• 농업과학연구
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• 제35권2호
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• pp.183-191
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• 2008

마늘을 이용한 기능성 잼을 제조하기 위하여 마늘에 당, 산, 펙틴을 첨가하고 평압과 감압에서 농축하여 마늘잼을 제조한 후 색도, 조직특성을 조사하고 $30^{\circ}C$에서 저장하면서 색도, 조직의 변화, 비타민 C의 변화를 측정한 결과는 다음과 같다. 원료마늘의 일반성분은 수분 57.2%, 탄수화물 23.6%, 조단백 1.9%, 조지방 0.75%, 회분 0.93%이었고 비타민 C는 8.4 mg/100g이었다. 명도는 진공농축한 것이 평압농축한 것보다 높았고 적색도와 황색도는 평압의 것이 높았다. 저장기간에 따라 명도는 모두 감소하였으나 평압에서 농축한 것이 감압보다 크게 감소하였으며 갈변화가 저장 8주에는 심하게 나타났다. 마늘잼의 조직특성은 hardness, chewiness, gumminess는 평압농축이 감압농축에 비하여 높았고 springiness, cohesiveness는 평압농축이 낮았다. 마늘잼의 기호성은 딸기잼에 비하여 떨어지지만 기능성을 감안할 때 시장성이 매우 높을 것으로 판단한다.

• 한국식품조리과학회지
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• 제23권5호
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• pp.626-634
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• 2007

카로티노이드의 우수급원인 파프리카를 생 파프리카(Fresh paprika; FP)와 동결건조 파프리카(freeze-dried paprika; FDP) 분말의 형태로 조리돈육패티(30% 돈지 함유)에 첨가하여 가열조리 후 저장기간 동안 포장방법(함기포장, 진공포장)과 저장온도($4^{\circ}C,\;-26^{\circ}C$)에 따라 파프리카의 지방산화 및 WOF 생성 억제효과를 비교해 보고자 하였다. FDP 5% 첨가 분쇄 조리 돈육은 함기포장과 진공포장 모두에서 냉장, 냉동 저장 중 POV와 TBA 값의 변화가 거의 없었으며, 냉동저장하는 동안 불포화지방산 파괴정도도 낮아 분쇄조리돈육 지방산화에 대해 매우 우수한 항산화제로 작용하였다. 반면에 FP 3% 첨가 분쇄 조리 돈육은 저장기간 동안 과산화물이 다량 생성되어 항산화작용이 거의 나타나지 않았다. 포장재가 분쇄조리돈육의 지방 산화 억제에 미치는 효과는 진공포장이 함기포장보다 우수한 것으로 나타났다. 따라서 지방산화 억제력은 냉장저장에서는 포장방법에 관계없이 FP보다는 FDP가 효과적이었으며, 냉동 진공포장 저장에서는 FP와 FDP가 거의 유사한 효과를 나타내었다. 동결건조 파프리카 분말 5% 첨가하여 제조한 분쇄조리돈육을 진공포장 후 냉장에서는 7일, 냉동에서는 3개월까지 WOF 발생을 지연시킬 수 있었으며, 진공포장하여 $-26^{\circ}C$에서 저장한 시료들에서 TBA 값과 WOF간에 가장 높은 양의 상관성(r = 0.88, p<0.05)을 나타내었다. 조리 돈육의 지질산화 안정성은 진공포장의 동결건조 파프리카 분말 첨가군이 가장 우수하였으므로 1차 가공 처리된 동결건조 파프리카 분말은 우수한 항산화제로서 다양한 식품에 활용이 가능할 것으로 보인다.

• Journal of Korean Vacuum Science & Technology
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• 제4권4호
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• pp.97-101
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• 2000

In this study, two kinds of barium strontium titanate (BST) samples were prepared. One is a conventional BST film that is sputtered in a mixture of argon and oxygen. The other is a nitrogen-incorporated BST film that is sputtered in a mixture of oxygen and intentionally added nitrogen instead of argon gas. The structural properties of both of the BST films had not changed significantly with the species of sputtering gas. However, the leakage current of BST films sputtered at ($N_2$+O$_2$) atmosphere was lower than those sputtered at (Ar +O$_2$) atmosphere: 1.9$\times$10$^{-8}$ A/cm$^2$ at 2V for the films prepared at (Ar +O$_2$) atmosphere and 8.6$\times$10$^{-9}$ A/cm$^2$ for the films at ($N_2$+O$_2$) atmosphere. From an XPS analysis, it has been found that nitrogen atoms are incorporated in BST films with a concentration of 1.92 at% and form a certain oxynitride phase. It is proposed that nitrogen atoms are able to fill the oxygen vacancies of BST films during sputtering process, and then the leakage current reduces due to a decrease in the vacancies. The BST films sputtered at ($N_2$+O$_2$) atmosphere have superior electrical properties to the films sputtered at (Ar +O$_2$), without any significant structural changes.