• 한국신뢰성학회지:신뢰성응용연구
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• 제16권3호
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• pp.202-207
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• 2016

Purpose: The purpose of this study is main factors (environmental conditions, pattern spacing, pattern material) that effect the ion-migration of PCB. Methods: Recently, the electronic components are becoming more high density of electronic device, so that electronic circuits have smaller pitches between the patten and more vulnerable to insulation failure. so the reliability of electric insulation of device has become an ever important issue as device contact pitches of pattern. Usually, ion-migration occurs in high temperature and high humidity environment as voltage is applied to the circuit. Under high temperature and high humidity, voltage applied electronic components respond to applied voltages by metals's electrochemical ionization and a conducting filament forms between the anode and cathode across a nonmetallic medium. This leads to short-circuit failure of the electronic component. Results: we studied ion-migration that occurs in accordance with the main factors (environmental conditions, pitches, pattern material). The PCB pattern material was made by two different types of material (free solder, OSP) for this research and pitches of pattern is 0.15mm, 0.3mm, 0.5mm. PCB was experimented in the environmental conditions (high temperature $120^{\circ}C$, high temperature and high humidity $85^{\circ}C$, 85%RH) and was analyzed for ion-migration through the experiment results. Conclusion: We confirmed that environmental condition, pitches of pattern, pattern material had effect on ion-migration of PCB.

• 한국포장학회지
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• 제8권1호
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• pp.1-10
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• 2002

각 국가 권역별 이행실험방법에 따라 지방성 및 고온가열 식품 포장재에서의 시뮬란트별 항산화제와 DEHA의 특정이행량을 비교하였다. 고온 가열용 식품 포장재의 경우 일부 두께가 두꺼운 필름, 예를 들어 PP 필름에서는 각 국가 권역별 시뮬란트 종류와 온도 조건의 차이에 따른 항산화제의 이행량의 차이가 나타났다. 미국이나 유럽연합에서 지방성 식품의 시뮬란트를 이용하여 얻어진 실험치에 $2{\sim}5$의 reduction factor가 계산되는 것을 감안한다면 아시아 조건하에서의 이행치가 유의적으로 높아지는 결과를 초래하게 된다. 아시아의 이행 실험 조건은 해당포장재의 온도 노출 조건에 따라 다양하게 설정될 필요성이 제기되었다.

• Tribology and Lubricants
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• 제15권4호
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• pp.335-342
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• 1999

Corrosion of the disk has been an ongoing concern for the manufacturers of hard disk drives. With the advent of magnetoresistive (MR) head, very low levels of corrosion and contamination become more critical since the raised defects and corrosion products on the disk surface-anything that heats the MR sensor due to the contact-can distort the output signal of the head. This phenomenon is called as thermal asperity. In this paper, the effect of corrosion as a form of Co migration on the occurrence of thermal asperity in MR drives was investigated. The corrosion test at high temperature (60$^{\circ}C$) and high relative humidity (80%) was emphasized in this study and the testing results at ambient condition were compared. The corrosion on the disks was characterized as the amount of Co ion migration using an ion chromatography (IC) and a time-of-flight secondary ion mass spectroscopy (TOF-SIMS). It is proved that corrosion on the disk surface after storage testing is closely correlated to the amount of Co ions migration from the magnetic layer to disk surfaces and higher Co migration causes more thermal asperities in the drive. In order to reduce Co migration, several methods such as burnishing process and structure of the carbon overcoat were investigated. It is found that the hydrogenated carbon overcoat shows the least Co migration among different types of overcoat layer. However, the most effective way to reduce Co migration is the application of Cr layer between the overcoat and the magnetic alloy layer.

• 한국포장학회지
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• 제5권2호
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• pp.42-58
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• 1999

Packaging materials and articles that are used in food contact applications can transfer constituents in the foodstuffs. This kind of risk of possible health hazards to consumers has been generally recognized for a long time with the consequence of establishing corresponding food regulations in most developed countries. However, the language of these laws, their interpretation, and their level of enforcement vary from country to country. Accordingly, the actual migrating levels from packaging materials can be varied depending on the migration testing methods as prescribed in the national legislation in each countries. Therefore, there are needs of elimination of non-tariff trade barriers raised by sanitary and phytosanitary or technical measures under the Final Act of the UR Agreement. In this connection, the EU and USA are currently in an ongoing process of legislation harmonization to overcome potential barriers to free trade. In general, regulations governing component transfer in the USA are more complicated and comprehensive than similar regulations in Europe. In future, standard migration testing procedures for microwave heat susceptor materials and for the use of fatty food simulant should be established and also harmonized among countries. The objective of this investigation is to compare the current regulations for migration testing for plastic containers and packaging materials in USA, EU and Korea or Japan. For those regulations, Korean standards are required to be kept up with the international standards. By doing this, the related Korean regulation could be amended along with the worldwide progress for harmonization.

• 한국식품위생안전성학회지
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• 제33권4호
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• pp.229-239
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• 2018

현재 국내 용기포장재 안전성 평가를 위한 용출시험에서 액체 시뮬란트를 사용하는 경우 실제와 다른 이행량 결과를 나타내는 상황과 고온가열 및 건조식품용 포장재, 그리고 종이 판지의 경우 액체 시뮬란트를 사용할 수 없는 문제점들을 감안한다면 유럽연합과 같이 고체건조 시뮬란트의 도입이 필수불가결해 보인다. $Tenax^{(R)}$를 건조식품용 시뮬란트로 사용하여 얻어진 실험 결과치가 실제 식품에서보다 높을 경우 $Tenax^{(R)}$에 대한 기준치를 설정하여 안전성 평가 여부를 판단할 수 있을 것이라는 전제가 성립한다. 지금까지 많은 연구결과들이 이러한 전제를 입증하고 있다. 그러나, 아직까지도 $Tenax^{(R)}$를 이용한 실험 방법이 완전하게 틀을 잡고 있지 못하다고 판단된다. 이는 $Tenax^{(R)}$로 포집되어 측정되는 물질의 물리화학적 특성들이 매우 다양할 수 있는데, 이를 포장재로부터 또는 이행된 식품으로부터 추출분석하기 위한 용매, 추출방법, 추출시간, 오염표준물질들의 종류에 따른 추출 및 분석 방법, $Tenax^{(R)}$의 상태에 따른 분석 재현성 등에 대한 자료들이 부족한 것이 사실이다. 국내에서 유통되는 다양한 식품종류를 감안한다면 $Tenax^{(R)}$를 국내 식품포장재의 안전성 평가를 위한 고체건조 시뮬란트로 공식적으로 도입하기 위해서는 추가 연구들이 필요할 것으로 판단된다.

• Tissue Engineering and Regenerative Medicine
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• 제15권6호
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• pp.721-733
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• 2018

BACKGROUND: Because three-dimensional (3D) models more closely mimic native tissues, one of the goals of 3D in vitro tissue models is to aid in the development and toxicity screening of new drug therapies. In this study, a 3D skin wound healing model comprising of a collagen type I construct with fibrin-filled defects was developed. METHODS: Optical imaging was used to measure keratinocyte migration in the presence of fibroblasts over 7 days onto the fibrin-filled defects. Additionally, cell viability and growth of fibroblasts and keratinocytes was measured using the $alamarBlue^{(R)}$ assay and changes in the mechanical stiffness of the 3D construct was monitored using compressive indentation testing. RESULTS: Keratinocyte migration rate was significantly increased in the presence of fibroblasts with the cells reaching the center of the defect as early as day 3 in the co-culture constructs compared to day 7 for the control keratinocyte monoculture constructs. Additionally, constructs with the greatest rate of keratinocyte migration had reduced cell growth. When fibroblasts were cultured alone in the wound healing construct, there was a 1.3 to 3.4-fold increase in cell growth and a 1.2 to 1.4-fold increase in cell growth for keratinocyte monocultures. However, co-culture constructs exhibited no significant growth over 7 days. Finally, mechanical testing showed that fibroblasts and keratinocytes had varying effects on matrix stiffness with fibroblasts degrading the constructs while keratinocytes increased the construct's stiffness. CONCLUSION: This 3D in vitro wound healing model is a step towards developing a mimetic construct that recapitulates the complex microenvironment of healing wounds and could aid in the early studies of novel therapeutics that promote migration and proliferation of epithelial cells.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문 발표회
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3~4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2003년도 학술.기술논문발표회
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• pp.43-48
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• 2003

This paper investigate that the effect of the concrete containing mineral admixtures(pozzaolanic materials such as fly-ash, ground granulated blast-furnace slag, silica fume and meta kaolin) on the resistance properties to chloride ion invasion. The purposed testing procedure was applied to the concrete added mineral admixtures for 3∼4 replacement ratios under W/B ratios ranged from 0.40 to 0.55. For the electrical migration test, Tang and Nilsson's method was used to estimate the migration coefficient of chloride ion. As a results, the W/B ratios, kinds of admixture and replacement ratios, water curing periods had a great effect on the migration coefficient of chloride ion, and the optimal replacement ratios of admixture had a limitation for each admixtures. Also, the addition of mineral admixtures by mass(replacement of OPC) enhanced the resistance of the mixture to chloride penetration compared with the plain concrete. The amount of acid soluble chloride ions and water soluble chloride ions were varied with the kinds of mineral admixtures. The compressive strength was shown related to the migration coefficient of chloride ion, the compressive strength increased with the decreasing migration coefficient of chloride ion. Below the 50MPa, the variation of migration coefficient of concrete added mineral admixtures was bigger than plain concrete.

• 한국식품위생안전성학회지
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• 제22권1호
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• pp.52-56
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• 2007

본 연구는 국내 유통 중인 프라이팬, 냄비, 주전자, 불판 등 금속제 주방기구 총 71품목을 대상으로 안전성 및 오염 정도에 대한 기초 자료를 제공하고자 실시되었다. 현행 식품공전 금속제의 재질 규격은 Pb 10%, Sb 5%이하이며 용출 규격은 Pb 1.0 mg/L이하이다. 알루미늄, 스테인리스 및 주철 총 71품목의 금속제 주방기구에 대한 재질시험 결과 Pb은 0.06% 이하로 검출되었으나 기준이하였으며 Sb은 모든 제품에서 검출되지 않았다. 또한 이들 주방기구의 용출시험 결과에서도 기준치이하인 0.41mg/L의 Pb이 검출되어 국내 유통 중인 금속제 주방기구는 기준규격에 적합한 것으로 나타났다.

• 한국식품위생안전성학회지
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• 제16권4호
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• pp.333-341
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• 2001

각 국가 권역별 이행실험방법에 따라 고온가열 식품 포장재와 용기의 simulants별 이행량을 측정하여 비교하였다. 고온가열 식품에 대한 총이행량을 비교해 본 결과 비지방성 simulant로 증류수와 10% ethanol수용액을 사용한 경우 일반적으로 121$^{\circ}C$의 2시간 조건에서의 CPA와 PA 6,6 필름을 제외하고는 2.5 mg/dm$^2$ 보다 낮았다. 지방성 simulant 에서 soybean oil로의 총이행량은 다른 simulan에 비해 높게 나타나는 경향을 보였다. 실험된 필름들 중 PVC wrap에서의 총이행량은 23.9~54.6 mg/dm$^2$로서 다른 필름들에 비해 높은 값을 나타내었다. 비지방성보다는 지방성 식품의 simulant에서 그리고 온도가 높은 조건하에서 이행량이 증가되는 경향을 보였다. 유사한 실험 온도와 시간 조건하에서는 PA계의 극성 필름은 극성 simulants에서, 그리고 PO계와 같은 비극성 필름은 비극성 simulants에서 이행량이 증가되는 경향을 보였다. 일부 필름에서 국가 권역별 이행실험 방법 및 조건의 상이함으로 인한 이행량의 차이가 확인되었다는 것은 주목할 만할 사실이다.