• 대한전자공학회논문지
• /
• 제23권1호
• /
• pp.65-73
• /
• 1986

Experiment have been conducted about thin oxide characteristics according to O2/N2 ratio needed for EEPROM cell fabrication. As a result, we think that there is no problem even if we grow oxide layer with large O2/N2 ratio and short exidation time and when the water is implated by As before oxidation, the oxide breakdown field is about IMV/cm lower than that is not implanted. Especially, the thin oxide characteristic seems to be affected largely by wafer cleaning and oxidation in air. On the basis of these, tunnel type EEPROM cell is fabricated by 3um CMOS process and its characteristic is studied. Tunnel oxide thickness(100\ulcorner is chosen to allow Fowler-Nordheim tunneling to charge the floating gate at the desired programming voltage and tunnel area(2x2um\ulcorneris chosen to increase capacitive coupling ratio. For program operation, high voltage (20-22V) is applied to the control gate, while both drain and source are gdrounded. The drain voltage for erase is 16V. It is shown that charge retention characteristics is not limited by leakage in the oxide and program/erase endurance is over 10E4 cycles of program erase operation.

• 원예과학기술지
• /
• 제31권3호
• /
• pp.289-298
• /
• 2013

마의 수확 후 관리기술 최적화 일환으로 3년에 걸쳐 단계적으로 치유 처리 및 저장온도에 따른 품질변화를 분석하였다. 마 괴근은 11월 초 중순에 수확하였고 수확후처리로서 상온과 $29^{\circ}C$ 열풍 조건에 따라 기간을 달리하는 치유과정을 거쳤다. 치유처리 후 저장온도는 저온장해 발생여부 판단과 저장 기간 최적화를 위해 $0.5-7.5^{\circ}C$ 범위에서 검증과정을 거쳤고 저장기간은 4개월에서 7개월까지 점진적으로 연장하였다. 저장 후 유통품질 유지를 위한 처리로는 단시간 $60^{\circ}C$ 열풍처리 후 $20^{\circ}C$ 상온유통과 $7^{\circ}C$ 저온유통 효과를 비교하였다. 수확 후 치유처리는 마의 호흡속도를 감소시켰고 상온치유보다는 3-5일 열풍치유가 장기저장 후 경도를 유지하고 중량감소를 낮춤으로써 품질유지에 보다 효과적이었다. 다양한 저장온도를 설정한 장기 저장 실험결과, $0.5^{\circ}C$에 저장된 마는 유통과정에서 저온장해 현상으로 판단되는 호흡속도의 증가와 조직붕괴 및 연화현상으로 인한 상품성의 저하가 빠르게 진행되었다. 적정 저장온도로는 저온장해 현상을 보이지 않으면서 품질 저하를 최소화하는 $3-4^{\circ}C$ 범위인 것으로 조사되었다. 장기저장 후 유통과정에서는 발근과 부패 억제 등 품질유지를 위해 저온유통이 필요한 것으로 나타났다. 연구결과를 종합해 볼 때, 마는 수확 후 열풍치유와 $3-4^{\circ}C$ 저장 및 저장 후 저온유통 과정으로 구성되는 최적화 프로그램 적용을 통해 7개월 이상 저장 후까지 품질유지가 가능한 것으로 판단되었다.

• 한국산학기술학회논문지
• /
• 제18권6호
• /
• pp.37-43
• /
• 2017

본 논문에서는 고출력 전자기파 (Electromagnetic pulses, EMP) 영향에 의해 발생하는 반도체 부품의 물리적 상호작용에 대한 원리와 고장 발생 메커니즘의 연구를 위해 선행된 연구 내용을 고찰하였다. 반도체 부품에서의 전자기파 전이 과정은 3층 (공기/유전체/도체) 구조로 설명할 수 있으며, 복소반사계수에 의하여 이론적으로 흡수되는 에너지를 예상할 수 있다. 반도체 부품에 전달된 과도한 고출력 전자기파로 인한 반도체 부품의 주요 고장 원인은 전자기파 커플링에 의한 부품 소재의 줄 열에너지의 발생이다. 전기장에 의한 유전가열과 자기장에 의한 맴돌이손실에 의해 반도체 칩의 P-N 접합 파괴, 회로패턴의 burn-out과 리드 프레임과 칩을 연결하는 와이어의 손상 등이 발생한다. 즉, 반도체 부품에 전달된 전자기파는 반도체 내부 물질과 상호작용을 하며, 쌍극자분극과 이온 전도도 현상이 동시에 발생하여, 칩 내부의 P-N 접합 부분에 과도한 역전압이 형성되어 P-N 접합 파괴를 유발한다. 향후 고 신뢰성을 요구하는 전기전자시스템에 대한 EMP 내성을 향상하기 위한 반도체 부품 수준의 연구가 필요하다.

• Clinical and Experimental Reproductive Medicine
• /
• 제31권3호
• /
• pp.155-168
• /
• 2004

Objective: Melatonin, which is secreted by pineal gland play an important role in the regulation of ovarian function via seasonal rhythm and sleep in most mammals. It also has a role in the protection of cells by removing toxic oxygen free radicals brought about by metabolism. In the present study, effects of melatonin on the mouse oocyte maturation were examined using two different culture conditions provided with 5% or 21% oxygen concentration. Material and Method: Immature mouse oocytes were obtained from the ovarian follicles of $3{\sim}4$ weeks old ICR strain mice intraperitoneally injected with 5 I.U. PMSG 44 hour before. Under stereomicroscope, morphologically healthy oocytes with distinct germinal vesicle (GV) were liberated from the graafian follicles and collected using mouth-controlled micropipette. They were then cultured for 17 hour at $37^{circ}C$, 5% $CO_2$ and 21% $O_2$ (95% air) or 5% $CO_2$, 5% $O_2$ and 90% $N_2$. New modified Hank's balanced salt solution (New MHBS) was used as a culture medium throughout the experiments. Effects of melatonin were examined at a concentration of $0.0001{\mu}M$, $0.01{\mu}M$ or $1.0{\mu}M$. For the prevention of spontaneous maturation of immature oocytes during culture, dibutyryl cyclic AMP (dbcAMP) and/or hypoxanthine were included in the medium. Results: Under 21% oxygen condition, oocytes cultured in the presence of $0.01{\mu}M$ melatonin showed a significantly higher maturation rates, in terms of germinal vesicle breakdown (95.0% vs 89.0%) and polar body formation (88.1% vs 75.4%), compared to those cultured with $0.0001{\mu}M$ or $1.0{\mu}M$ melatonin. However, no difference was observed in oocytes cultured under 5% oxygen whether they were treated with melatonin or not. In the presence of $0.01{\mu}M$ melatonin, oocytes either cultured under 21% or 5% oxygen exhibited no difference in the polar body formation (85.6% vs 86.7%). However, in the absence of melatonin, oocytes cultured under 21% oxygen exhibited lower polar body formation (74.7%). When oocytes were cultured in the presence of dbcAMP alone or with varying concentrations of melatonin, those treated with both compounds always showed better maturation, i.e., germinal vesicle breakdown and polar body formation, compared to those cultured with dbcAMP alone. At the same concentration of melatonin, however, oocytes exposed to 21% oxygen showed poor maturation than those to 5% oxygen. Similar results were obtained from the experiments using hypoxanthine instead of dbcAMP. Conclusion: Based upon these results, it is suggested that melatonin could enhance the meiotic maturation of mouse oocytes under 21% oxygen concentration, and release oocytes from the meiotic arrest by dbcAMP or hypoxanthine regardless of the concentration of oxygen, probably via the removal of oxygen free radicals.

• 한국수산과학회지
• /
• 제26권5호
• /
• pp.403-408
• /
• 1993

횟감으로 많이 소비되고 있는 넙치를 시료로 치사 방법(즉살, 고민사, 마취사 및 전기 자극사)을 달리하여 치사시킨 후에 $5^{\circ}C$에 저장하면서 사후 조기의 생화학적 변화에 대하여 검토한 결과는 다음과 같다. 1. 치사 직후의 어육중의 ATP 함량은 고민사에서 가장 낮았고 마취사에서 가장 높았으며, 치사후 저장중의 ATP 분해 속도는 전기 자극사, 고민사,즉살, 그리고 마취사의 순서였으며 각각 11시간, 15시간, 32시간, 그리고 40시간후에 ATP가 완전히 분해되었다 또, 분해 속도 상수는 각각 $0.429h^{-1},\;0.224h^{-1},\;0.195h^{-1}$, 그리고 $0.167h^{-1}$였다. 2. IMP의 최대 축적 시간과 함량은 전기 자극사 11시간과 $6.99{\mu}mole/g$, 고민사 20시간과 $6.12{\mu}mole/g$, 즉살 31.5시간과 $6.30{\mu}mole/g$, 그리고 마취사에서 40시간과 $6.40{\mu}mole/g$으로, 전기 자극사에서 IMP 생성이 가장 빨랐으며 그 함량도 높았다. 또, 반응 속도 상수는 각각 $0.591h^{-1},\;0.248h^{-1},\;0.165h^{-1}$, 그리고 $0.161h^{-1}$였다. 3. 어육중의 유산량의 변화는 치사 직후에 즉살에서 가장 낮았으며 저장중의 최대 축적량도 가장 낮은 $38.84{\mu}mole/g$이었지만, 전기 자극사와 고민사에서는 치사 직후에 어육중의 유산 축적량이 높았으며, 저장중의 최대 축적량도 가장 높은 값을 나타내었다. 또, 반응 속도 상수는 전기 자극사 $2.256h^{-1}$, 고민사 $1.123h^{-1}$, 즉살 $0.534h^{-1}$, 그리고 마취사 $0.526h^{-1}$였다.

• 한국표면공학회지
• /
• 제48권2호
• /
• pp.33-37
• /
• 2015

High efficiency LED device is being concerned due to its high heat loss, and such heat loss will cause a shorter lifespan and lower efficiency. Since there is a demand for the materials that can release heat quickly into the external air, the organic insulating layer was required to be replaced with high thermal conductive materials such as metal or ceramics. Through anodizing the upper layer of Al, the Breakdown Voltage of 3kV was obtained by using an uniform thickness of $60{\mu}M$ aluminum oxide($Al_2O_3$) and was carried out to determine the optimum process conditions when thermal cracking does not occur. Two Ni layers were formed above the layer of $Al_2O_3$ by sputtering deposition and electroplating process, and saccharin was added for the purpose of minimizing the remain stress in electroplating process. The results presented that the 3-layer film including the Ni layer has an adhesive force of 10N and the thermal conductivity for heat dissipation is achieved by 150W/mK level, and leads to improvement about 7 times or above in thermal conductivity, as opposed to the organic insulation layer.

• 신재생에너지
• /
• 제7권3호
• /
• pp.17-28
• /
• 2011

Biogas production and utilization are an emerging alternative energy technology. Biogas is produced from the biological breakdown of organic matter through anaerobic digestion. Biogas can be utilized for various energy sectors such as space heating, electricity generation and vehicle fuel. Especially, to be utilized as vehicle fuel, raw biogas needs to be upgraded that is mainly the removal of carbon dioxide to increase the methane content up to more than 95 ~ 97 vol% in some cases, similar to the composition of fossil-based natural gas. Usage of Biogas as a fuel of vehicles have an effect of reducing $CO_2$ emission compared to fossil fuels. Biomethane which is produced by upgrading of biogas is regarded as a good alternative energy and usage of clean energy is encouraged to deal with air pollution and waste management as well as production of clean energy. Recently, biogas projects for vehicle fuel are newly being launched and Korea government have also announced a plan for investment to develop biogas as a transport fuel. In this study, it is aimed to examine the potential feasibility of biomethane as a transport fuel. As a results, the status of biomethane, quality standard, quality characteristics, and upgrading technology of biogas were investigated to evaluate of biogas as a vehicle fuel of transportation.

• Clinical and Experimental Reproductive Medicine
• /
• 제28권1호
• /
• pp.1-12
• /
• 2001

Objective: The present study was done to clarify the effects of nicotine and nicotine tartrate on the mouse oocyte maturation in vitro. Methods: GV (germinal vesicle) oocytes were isolated from Graafian follicle of ovaries with sharp needles under a stereomicroscope from female mouse of ICR strain (4 weeks old). Collected oocytes were cultured for 17 hours at $37^{\circ}C$, 5% $CO_2$ in air and 100% humidified condition in incubator. New MHBS was the basic medium used in which nicotine, nicotine tartrate, and mecamylamine (antagonist of nicotinic acetylcholine receptor) were added depending on the experimental group. GV oocytes were cultured in one of these media. Results: Nicotine ($300{\mu}M{\sim}5mM$) had no effects on GVBD (germinal vesicle breakdown) compared to the control, but increasing concentration of nicotine led to an decrease in the first polar body formation. However, nicotine ($10{\sim}500{\mu}M$) induced GVBD in a dose-dependent manner of GV oocytes in a medium containing dbcAMP. Nicotine tartrate ($50{\mu}M{\sim}5mM$) had no effects on GVBD compared to the control but, increasing concentration of nicotine tartrate led to an decrease in the first polar body formation. Mecamylamine $10{\mu}M$ added to the medium containing nicotine ($300{\mu}M{\sim}5mM$) showed higher percentage of the first polar body formation compared to the nicotine ($300{\mu}M{\sim}5mM$) treatment group. Mecamylamine $10{\mu}M$ added to the medium containing nicotine tartrate ($50{\mu}M{\sim}5mM$) showed higher percentage of the first polar body formation compared to the nicotine tartrate ($50{\mu}M{\sim}5mM$) treatment group. Conclusion: The present study suggest that nicotine and nicotine tartrate have the harmful effects on the meiotic maturation of the mouse oocytes in vitro. However, mecamylamine block harmful effects of nicotine and nictine tartrate.

• 한국초전도ㆍ저온공학회논문지
• /
• 제15권4호
• /
• pp.53-58
• /
• 2013

KSTAR in-vessel cryo-pump has been installed in the vacuum vessel top and bottom side with up-down symmetry for the better plasma density control in the D-shape H-mode. The cryogenic helium lines of the in-vessel cryo-pump are located at the vertical positions from the vacuum vessel torus center 2,000 mm. The inductive electrical potential has been optimized to reduce risk of electrical breakdown during plasma disruption. In-vessel cryo-pump consists of three parts of coaxial circular shape components; cryo-panel, thermal shield and particle shield. The cryo-panel is cooled down to below 4.5 K. The cryo-panel and thermal shields were made by Inconel 625 tube for higher mechanical strength. The thermal shields and their cooling tubes were annealed in air environment to improve the thermal radiation emissivity on the surface. Surface of cryo-panel was electro-polished to minimize the thermal radiation heat load. The in-vessel cryo-pump was pre-assembled on a test bed in 180 degree segment base. The leak test was carried out after the thermal shock between room temperature to $LN_2$ one before installing them into vacuum vessel. Two segments were welded together in the vacuum vessel and final leak test was performed after the thermal shock. Commissioning of the in-vessel cryo-pump was carried out using a temporary liquid helium supply system.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
• /
• pp.47-52
• /
• 2002

A processing method is developed for preparing sol-gel derived $Pb(Zr_{1-x}Ti_x)O_3$ (x=0.5) thin films on Pt-Ir($Pt_{80}Ir_{20}$)-alloy substrates. The as-deposited layer was dried on a plate in air at $70^{\circ}C$. And then it was baked at $1500^{\circ}C$, annealed at $450^{\circ}C$ and finally annealed for crystallization at various temperatures ranging from $580^{\circ}C$ to $700^{\circ}C$ for 1hour in a tube furnace. The thickness of the annealed film with three layers was $0.3{\mu}m$. Crystalline properties and surface morphology were examined using X-ray diffractometer (XRD). Electrical properties of the films such as dielectric constant, C-V, leakage current density were measured under different annealing temperature. The PZT thin film which was crystallized at $600^{\circ}C$ for 60minutes showed the best structural and electrical dielectric constant is 577. C-V measurement show that $700^{\circ}C$ sample has window memory volt of 2.5V and good capacitance for bias volts. Leakage current density of every sample show $10^{-8}A/cm^2$ r below and breakdown voltage(Vb) is that 25volts.