• 한국안광학회지
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• 제9권1호
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• pp.173-180
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• 2004

콘택트렌즈 관리용액으로 사용되는 합성보존제로서 대표적인 $H_2O_2$와 천연보존제인 자몽씨 추출물(DF-100)이 결막세포에 미치는 저해효과를 비교 조사하기 위하여 본 연구를 시행하였다. 자몽씨 추출물의 주성분은 Narigin이며, 이는 항산화를 일으키는 Flavonoid의 구성성분중 하나이다. $H_2O_2$와 자몽씨 추출물(DF-100)의 세포는 MTT assay에 의해 측정하였고, DNA 손상은 Comet assay 측정으로 분석하였다. 5%의 자몽씨 추출물은 과산화수소에 의해 손상된 세포를 회복시켜주는 효과를 나타내었으며, 또한 배양 결막세포주에 과산화수소 및 자몽씨 추출물을 농도별로 동시 처리하여 24시간 뒤 LDH leakage assay용 이용한 세포독성을 측정하여 분석하였다. 자몽씨 추출물은 과산화수소의 세포증식 저해와 apoptosis를 현저하게 억제해 주었다. 또한 자몽씨 추출물은 bioflavonoids의 구성성분이며 이는 음식으로써도 제공된다. 이 연구는 자몽씨 추출물이 anti-oxidant와 anti-apoptopic activity로 천연보존제로 유용하게 사용될 수 있는 것을 보여준다.

• 한국재료학회지
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• 제28권2호
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• pp.118-123
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• 2018

5 nm-thick $SiO_2$ layers formed by plasma-enhanced chemical vapor deposition (PECVD) are densified to improve the electrical and interface properties by using nitric acid oxidation of Si (NAOS) method at a low temperature of $121^{\circ}C$. The physical and electrical properties are clearly investigated according to NAOS times and post-metallization annealing (PMA) at $250^{\circ}C$ for 10 min in 5 vol% hydrogen atmosphere. The leakage current density is significantly decreased about three orders of magnitude from $3.110{\times}10^{-5}A/cm^2$ after NAOS 5 hours with PMA treatment, although the $SiO_2$ layers are not changed. These dramatically decreases of leakage current density are resulted from improvement of the interface properties. Concentration of suboxide species ($Si^{1+}$, $Si^{2+}$ and $Si^{3+}$) in $SiO_x$ transition layers as well as the interface state density ($D_{it}$) in $SiO_2/Si$ interface region are critically decreased about 1/3 and one order of magnitude, respectively. The decrease in leakage current density is attributed to improvement of interface properties though chemical method of NAOS with PMA treatment which can perform the oxidation and remove the OH species and dangling bond.

• Weed & Turfgrass Science
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• 제4권4호
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• pp.360-367
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• 2015

This study was performed to determine the effects of silicon on zoysiagrass after the application of drought stress. The daily amount of water or scilicon solution was 150 ml per a pot. For 14 days, plants were treated with 0.1 and 1.0 mM silicon (Si) and with distilled water for control and the drought only-treatment. Afterward, the plants in Si and drought treatment were exposed to a 21-day under drought stress condition but the plants in control received water. The results indicated that the growth and the moisture and chlorophyll contents decreased in the drought only-treatment and 0.1 mM Si compared to the control. However, 1.0 mM Si showed an increase in the growth with a significant increase of water and chlorophyll contents. The MDA and $H_2O_2$ concentrations and electrolyte leakage decreased, while the radical scavenging capacity increased in 1.0 mM Si. 1.0 mM Si showed little to no differences in the growth and no differences in water and chlorophyll contents, electrolyte leakage, MDA and $H_2O_2$ concentrations and antioxidant capacity compared to the control. These results suggested that application of silicon is useful for drought tolerance improvement of zoysiagrass under drought that is occurring in turf fields.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 추계학술대회
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• pp.158-159
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• 2022

기후위기로 인해 온실가스 감축을 비롯한 다양한 환경규제가 발효되고 있다. 이는 어느 특정 산업분야에 그치지 않고, 전세계적인고산업 전반에 영향을 미치고 있다. 이러한 이유로 IMO와 각국 정부에서는 조선·해운산업관련한 전략과 정책을 발표하고 있는 상황이다. 현행규정은 기존 화석연료를 사용하면서 스크러버와 같은 부가설비를 통해 일정부분 해결가능하겠지만, 궁극적으로는 에너지 전환을 통해 선박에서 발생하는 배출가스에서 이산화탄소(CO₂)와 같은 온실가스의 배출을 제한해야 한다. 이를 위해서는 전통연료인 기름과 천연가스를 대체할 수 있는 연료를 개발해야한다. 그중에서 수소는 연료로 사용할 때 오염물질을 배출하지않는 청정에너지로써 주목을 받고 있다. 하지만, 수소를 폭발범위가 넓고 확산속도가 빨라 이에대한 연구가 필요하다. 따라서, 본 논문에서는 수소추진선박의 연료준비실내에서 수소 누출이 발생하였을 때 그 경향을 분석하고 환기특성을 알아보고자 하였다.

• 한국안전학회지
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• 제30권1호
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• pp.14-20
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• 2015

A Large Eddy Simulation(LES) was performed for the prediction of unsteady dispersion behavior of hydrogen fluoride (HF). The HF leakage accident occurred at the Gumi fourth industrial complex was numerically investigated using the Fire Dynamics Simulator (FDS) based on the LES. The accident area was modeled three-dimensionally and time-varying boundary conditions for wind were adopted in the simulation for considering the realistic accident conditions. The Message Passing Interface (MPI) parallel computation technique was used to reduce the computational time. As a result, it was found that the present LES simulation could predict the unsteady dispersion features of HF near the accident area effectively. The dispersion behaviors of the leaked HF was much affected by the unsteady wind direction. The LES could predict the time variation of the HF concentration reasonably and give an useful information for the risk analysis while the prediction with the time-averaging concept of HF concentration had a limitation for the amount of HF concentration at specific location point. It was identified that the LES is very useful to predict the dispersion characteristics of hazardous chemicals.

• 한국전기전자재료학회논문지
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• 제18권4호
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• pp.327-329
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• 2005

Pb(Zr/sub 0.52/Ti/sub 0.48/)O₃(PZT) thin films were deposited by using a pulsed laser deposition method on a Pt/Ti/SiO₂/Si substrate with (Pb/sub 0.72/La/sub 0.28/)Ti/sub 0.93/O₃ (PLT) buffer and on a Pt/Ti/SiO₂/Si substrate without buffer. These films were annealed in H₂-contained ambient for 30 minutes at the substrate temperature of 400。C to evaluate the forming gas annealing effects. The comparative studies on the ferroelectric properties of these two films were carried out, which are shown that ferroelectric properties, such as remanent polarization didn't change in the case of PLT buffered PZT film while remanent polarization value of PZT film degraded from 20.8 C/㎠ to 7.3 C/㎠. The leakage current became higher in both cases, but that of the more-oriented PZT film had the moderate value of the 10/sup -6/ order of A/㎠. This is mainly because the hydrogen atoms which make the degradation of PZT films cannot infiltrate into the more -oriented PZT film as well as the less-oriented PZT film.

• 한국토양비료학회지
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• 제49권6호
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• pp.651-654
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• 2016

A number of accidents relating to highly toxic hydrogen fluoride (HF) or hydrofluoric acid (HA) release have occurred over fast few decades in Korea. Thus, this study was conducted to investigate the fluoride (F) concentrations in paddy soil and brown rice from 2 different areas where the soils were exposed to HF and HA. In the first case, the HF leakage accident that occurred in 2012 affected the surrounding soils and crops and consequently, crops (rice) affected by HF were unavailable for forage even though F did not accumulate in the soil. For example, at the time of accident, F concentrations in brown rice samples were $33.0-1,395mg\;kg^{-1}$, while F concentrations in soil samples were $155-295mg\;kg^{-1}$ which were less than the Korean standard guideline values of $400mg\;kg^{-1}$. However, after a year, F concentrations in brown rice were observed below the detection limit ($1mg\;kg^{-1}$), although F concentrations in soils were similar with those in 2012. Also, large amounts of wastewater discharges containing HA occurred in 2013 and some agricultural soils exceeded the Korean standard guideline values for F ($400mg\;kg^{-1}$), but soil-plant F transfer was not observed. In conclusion, it was observed that soil to plant transfer of F is unlikely although HF and HA as gas or liquid form can cause direct damage to plants.

• 한국수소및신에너지학회논문집
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• 제22권4호
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• pp.488-494
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• 2011

Gasket plays an important role on sealing of the polymer electrolyte membrane fuel cell (PEMFC) stack. Stack requires gaskets in each cell to keep the hydrogen and air/oxygen within their respective regions. The failure of the gasket creates the problems of fuel leakage, mixing, damage on parts and can be a direct reason for the degrading the efficiency of fuel cell. The purpose of this paper researches on how mechanical properties of EPDM gasket in PEMFC are changed after long-term operations. The EPDM (ethylenepropylene-diene monomer) gaskets are obtained from the stack after long-term operations. DMA (dynamic mechanical analysis) is conducted to access the change of mechanical properties of the EPDM gasket. SEM/EDS (scanning electron microscope/energy dispersive spectroscopy) was used to show the surface topography and chemical characterization on the sample surface.

• Transactions on Electrical and Electronic Materials
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• 제9권1호
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• pp.6-11
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• 2008

In this study, we investigated effects of hydrogen annealing (HA) and plasma nitridation (PN) applied in order to improve $Si/SiO_2$ interface characteristics of TiN metal gate. In result, HA and PN showed a positive effect decreasing number of interface state $(N_{it})$ respectively. After FN stress for verifying reliability, however, we identified rapid increase of $N_{it}$ for TiN gate with HA, which is attributed to hydrogen related to a change of $Si/SiO_2$ interface characteristic. In contrast to HA, PN showed an improved Nit and gate oxide leakage characteristic due to several possible effects, such as blocking of Chlorine (Cl) diffusion and prevention of thermal reaction between TiN and $SiO_2$.

• 한국안전학회지
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• 제24권3호
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• pp.54-58
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• 2009

화석연료의 고갈과 환경문제로 인해 대체에너지 개발의 필요성이 대두되고 있다. 이에 거론되고 있는 대체에너지 중에서 물로부터 수소를 생산하는 기술은 탄소발생이 없는 매우 장래가 유망한 기술이다. IS 열화학적 물분해 공정은 거론되는 방법 중 매우 유망한 기술로 에너지원으로 900$^{\circ}C$ 이상의 열을 공급할 수 있는 고온가스냉각로(HTGR)를 시용하여 매우 능률적으로 수소를 생산할 수 있는 방법이다. 본 연구에서는 IS공정 의 초기사건을 도출하기 위해 주논리도(MLD)방법이 사용되어 화학물질의 유출을 야기할 수 있는 초기사건 9가지가 도출되었다. 또한 도출된 9가지 초기사건 중 6가지를 선정, 사건수목을 이용하여 정량화하였다.