• Journal of Electrical Engineering and Technology
• /
• 제10권1호
• /
• pp.355-363
• /
• 2015

HVDC technology has become popular as an economic mode of bulk power transmission over very long distances. Polymeric insulators in HVDC power transmission lines are affected by surface tracking and erosion problems due to contamination deposit, which pose a greater challenge in maintaining the reliability of the HVDC system. In addition, polymeric insulators are also naturally affected by aging due to various environmental stresses, which in turn accelerates the surface tracking and erosion problems. Research works towards the improvement of tracking and erosion resistance of polymeric insulators by adding nano-sized fillers in the base material are being carried out worldwide. However, surface tracking and erosion performance of nano-filled aged polymeric insulators for HVDC applications are not well reported. Hence, in the present work, tracking and erosion resistance of the nano $Al(OH)_3$ filled silicone rubber insulation material has been evaluated under DC voltages at different filler concentrations and aged conditions, as per IEC 60587 test procedures. Leakage current and contact angle measurements were carried out to understand the surface hydrophobicity. Moving average technique was used to analyze the trend followed by leakage current. Water aged specimen shows less tracking resistance when compared with thermal aged specimen. It is observed that nano-filler concentration of 5% is even sufficient to get better tracking/erosion resistance under DC voltages.

• 동아시아식생활학회지
• /
• 제22권5호
• /
• pp.613-623
• /
• 2012

In this study, the quality characteristics of salad dressing prepared with mulberry, Schisandra chinensis, and Discorea powder were evaluated. Salad dressing was prepared with salad base (plain yogurt : mayonnaise : fresh cream = 8:1:1), mulberry, Schisandra chinensis for acidity, and Discorea powder for viscosity (4:4:6:1 or 4:4:6:3). Discorea powder was added at levels of 0, 7, and 18% to the salad dressing. As the concentration of Discorea powder increased, the pH level increased, and acidity decreased. Hunter's color L (lightness) value of salad dressing decreased as the amount of Discorea powder increased. Viscosity increased according to the amount of Discorea powder. Moreover, total phenolic content increased according to the amount of Discorea powder. Further, DPPH antioxidant and hydroxyl radical activity of mulberry salad dressing increased as the amount of Discorea powder increased. Sensory preference test results showed that the salad dressing added with Discorea powder had higher scores for color, flavor, taste, and texture than the control. Regarding overall preference, salad dressing containing 7% Discorea powder had the highest scores among the treatments. From these results, salad dressing containing mulberry, Schisandra chinensis for acidity, and Discorea powder for viscosity could be a functional salad dressing with high antioxidant activity.

• 한국조경학회지
• /
• 제30권1호
• /
• pp.61-74
• /
• 2002

The purpose of this study is to propose vegetation management devices through analyzing the actual vegetation, flora, plant community structure and soil chemical concentrations in Weolmi urban nature park, Incheon. The actual vegetation of Weolmi Park in various areas is composed of urbanization area(2 types, 25.9%), landscape planting area(4 types, 16.1%), grass and marsh area(5 types, 7.6%) and mountain forest areal(14 types, 50.4%). The flora is composed of 295 taxa with 80 families, 253 species, 35 varieties and 7 formas, and among them there are 16 naturalized plant families, 39 species, 3 varieties. In reflection of size, the number of the species seems high but most of the them are under influence of human disturbance. Nine survey plots of plant community structure are classified into two groups. One is the semi-natural plant community(Prunus sargentii-Acer palmatum, Quercus accutissma-Prunus sargentii, Quercus serrata-Quercus accutissma-Prunus sargentii, Prunus sargentii, and Zelkova serrata-Prunus sargentii) that migrated finn the planting forest to the natural forest and the other is planting forest(Pinus koraienssis-Pinus thunbergii-Abies holophylla-Chamaectparis obtusa, Prunus sargentii, Pinus thunbergii-Alnus firma, Zelkova serrata). The average pH is 4.65 which means the soil acidity is quite high. The concentration of K, Ca, Mg and base saturation is very low. It seems that the environmental pollutants from Incheon Port and industrial plants near by survey site and long-distance transport of air pollutants from China made the soil condition worse. On the basis of the results above, six vegetation management devices are suggested: 1) removing the hazard plants(Pueraia thunbergiana and Humulus japonica), 2) natural landscape management of the middle and long term, 3) increasing species diversity, 4) Robinia pseudoacacia management, 5) keeping the naturalized plants from being distributed any further inside the mountain forest, 6) improving soil acidification.

• Corrosion Science and Technology
• /
• 제12권6호
• /
• pp.274-279
• /
• 2013

Flow accelerated corrosion (FAC) of the carbon steel piping in nuclear power plants (NPPs) has been major issue in nuclear industry. During the FAC, a protective oxide layer on carbon steel dissolves into flowing water leading to a thinning of the oxide layer and accelerating corrosion of base material. As a result, severe failures may occur in the piping and equipment of NPPs. Effect of alloying elements on FAC of pipe materials was studied with rotating cylinder FAC test facility at $150^{\circ}C$ and at flow velocity of 4m/s. The facility is equipped with on line monitoring of pH, conductivity, dissolved oxygen(DO) and temperature. Test solution was the demineralized water, and DO concentration was less than 1 ppb. Surface appearance of A 106 Gr. B which is used widely in secondary pipe in NPPs showed orange peel appearance, typical appearance of FAC. The materials with Cr content higher than 0.17wt.% showed pit. The pit is thought to early degradation mode of FAC. The corrosion product within the pit was enriched with Cr, Mo, Cu, Ni and S. But S was not detected in SA336 F22V with 2.25wt.% Cr. The enrichment of Cr and Mo seemed to be related with low, solubility of Cr and Mo compared to Fe. Measured FAC rate was compared with Ducreaux's relationship and showed slightly lower FAC rate than Ducreaux's relationship.

• 생물환경조절학회지
• /
• 제4권1호
• /
• pp.43-49
• /
• 1995

양액재배에서 제주송이가 다른 배지와 비교하여 방울토마토의 수량 및 품질에 미치는 영향과 양액성분 변화를 조사하여 제주송이를 양액재배용 고형배지로 실용화하기 위하여 시험한 결과는 다음과 같다. 1. 건엽비, 건과비, 당산비는 1익㉣ 1회 1시간 담액후에 완전 배액한 구에서 높았다. 2. 방울토마토 생과중은 상위 화방으로 갈수록 암면구와 담액수경구는 작아졌으나, 송이구와 일향토구, 펄라이트구 등 고형배지경에서 무거웠다. 3. 방울토마토의 생육이 왕성한 시기에 양액성분중 다량원소를 분석한 결과는 송이 재배구에서 인산과 칼륨 농도가 낮았다. 4. 방울토마토의 수량과 당도는 암면과 일향토구에서 높은 경향을 보였다. 5. 일반적으로 양액재배에서는 수분의 증발과 식물의 수분 흡수 증산작용으로 비료염의 농도가 높아가는데 송이구도 다른 고형배지경과 비슷한 결과를 보였다. 6. 제주 송이 양액재배용 고형배지로 손쉽게 이용할 수 있는 가벼운 자재로 가공개발 연구가 있어야 할 것으로 본다.

• The Plant Pathology Journal
• /
• 제32권2호
• /
• pp.85-94
• /
• 2016

Studies were conducted to determine the role of 3-methylthioproprionic acid (MTPA) in the pathogenicity of potato stem canker, Rhizoctonia solani, and the concentrations required to inhibit growth of R. solani under laboratory and plant house-based conditions. The experiments were laid out in a completely randomized design with five treatments and five replications. The treatments were 0, 1, 2, 4, and 8 mM concentrations of MTPA. The purified toxin exhibited maximal activity at pH 2.5 and $30^{\circ}C$. MTPA at 1, 2, 4, and 8 mM levels reduced plant height, chlorophyll content, haulm fresh weight, number of stolons, canopy development, and tuber weight of potato plants, as compared to the control. MTPA significantly affected mycelial growth with 8 mM causing the highest infection. The potato seedlings treated with MTPA concentrations of 1.0-8.0 mM induced necrosis of up to 80% of root system area. Cankers were resulted from the injection of potato seedling stems with 8.0 mM MTPA. The results showed the disappearance of cell membrane, rough mitochondrial and cell walls, change of the shape of chloroplasts, and swollen endoplasmic reticulum. Seventy-six (76) hours after toxin treatment, cell contents were completely broken, cytoplasm dissolved, and more chromatin were seen in the nucleus. The results suggested that high levels of the toxin concentration caused cell membrane and cytoplasm fracture. The integrity of cellular structure was destroyed by the phytotoxin. The concentrations of the phytotoxin were significantly correlated with pathogenicity and caused damage to the cell membrane of potato stem base tissue.

• Restorative Dentistry and Endodontics
• /
• 제16권1호
• /
• pp.87-105
• /
• 1991

The purpose of this experiment was to measure the leaking and solubility of commonly used dental restorative materials - Silux plus (CS), Hi-pol (CH), Clearfil F-II, Fissureseal (FS), Glass-Ionomer cement Fuji Type II (GI), Amalgam Cavex 68 (AM), Zinc Phosphate Cement (ZP) and gutta-percha (GP) and investigate the relation between the solubility and marginal leakage. Disc-shape specimens were fabricated with each material and dipped into deionized water, 0.01M lactic acid and 0.005M KOH solution, thus the total ionic concentrations in each solution was measured with ion chromatograph after 1, 3, and 7 days, respectively. For the solubility test, each specimen was immersed in 0.001M and 0.01M lactic acid for 24 hours, respectively and total weight loss was calculated. Also, Zn leaking through the margin of restorations was measured. The obtained results were as follows: 1. The amounts of eluted ion from the eight materials were most in 0.01M lactic acid and least in deionized water. 2. Of the eight materials, the fluoride release was greatest for glass ionomer cement (GI) in 0.01 M lactic acid after 7 days. 3. In analysis of the divalent cation, Mg was eluted most for zinc phosphate cement (ZP) and Ca for Clearfil F-II (CF) in 0.01M lactic acid after 7 days. 4. In analysis of transition metals, Cu and Zn were detected only. 5. The solubility rate of eight materials was greater in 0.01M lactic acid than in 0.001M for 24 hours, for zinc phosphate cement (ZP) the rate was greatest (5.4%) in 0.001M lactic acid, and amalgam least (0.01%). 6. The Zn concentration of restorative material with Z.P.C base was greater in 0.01M lactic acid than in 0.001M lactic acid.

• Applied Biological Chemistry
• /
• 제50권1호
• /
• pp.48-52
• /
• 2007

마늘 분말을 첨가한 호상 요구르트를 개발하기 위하여 탈지분유에 마늘 분말을 혼합하고 Lactobacillus acidophilus, Bifidobacterium longum, Streptococcus thermophilus를 혼합 균주를 접종하여 마늘 분말의 첨가가 유산균의 생육에 미치는 영향과 품질특성 및 관능적 특성을 검토하였다. 마늘 분말을 0.2-1.0%(w/v) 첨가한 결과 산의 생성과 젖산균의 증식이 마늘 분말을 첨가하지 않은 대조군보다 감소되었으며, 18시간 발효시킨 요구르트의 적정 산도는 대조구의 1.35%에서 마늘분말을 1.0% 첨가한 경우 1.08%로 20% 감소하였다. 마늘 분말의 첨가로 요구르트의 점도는 약2배 증가하였으나, 색도는 거의 일정하였다. 요구르트에 설탕을 10% 첨가하고 관능적 특성을 조사한 결과 마늘 분말을 0.5% 이상 첨가한 경우 마늘 향과 맛이 강하게 감지되어 요구르트의 기호도는 낮게 평가되었다. 그러므로 마늘 분말의 첨가량은 0.2% 수준이 적당한 것으로 나타났다.

• 대한원격탐사학회:학술대회논문집
• /
• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
• /
• pp.654-655
• /
• 2003

Korea has experienced 10 a Cochlodinium polykrikoides red tide outbreaks during the last 10 years (1993-2002). The monitoring activities at National Fisheries Research and Development Institute (NFRDI) in Korea have been extended to all the coastal waters after the worst of fish killing by C. polykrikoides blooms in 1995. NFRDI is looking forward to finding out the feasibility of red tide detection around Korean waters using satellite remote sensing of NOAA/AVHRR, Orbview-2/SeaWiFS, IRS-P4/OCM and Terra/MODIS on real time base. In this study, we used several alternative methods including climatological analysis, spectral and optical methods which may offer a potential detection of the major species of red tide in Korean waters. The relationship between the distribution of SST and C. polykrikoides bloom areas was studied. In climatological analysis, NOAA, SeaWiFS, OCM satellite data in 20th and 26th August 2001 were chosen using the known C. polykrikoides red tide bloom area mapped by helicopter reconnaissance and ground observation. The 26th August, 2001 SeaWiFS chlorophyll a anomaly imageries against the imageries of non-occurring red tide for August 20, 2001 showed the areas C. polykrikoides occurred. The anomalies of chlorophyll a concentration from satellite data between before and after red tide outbreaks showed the similar distribution of C. polykrikoides red tide in 26th August, 2001. The distribution of the difference in SST between daytime and nighttime also showed the possibility of red tide detection. We used corrected vegetation index (CVI) to detect floating vegetation and submerged vegetation containing algal blooms. The simple result of optical absorption from C. polykrikoides showed that if we use the optical characteristics of each red tide we will be able to get the feasibility of the red tide detection.

• 한국토양비료학회지
• /
• 제44권4호
• /
• pp.559-564
• /
• 2011

Soil microbial functions are considered to be effective in assessing the severity of heavy metal pollution. Therefore, this study was carried out to examine the effect of heavy metals on nitrogen mineralization by measuring the releasing pattern of inorganic nitrogen ($NH_4^+$-N and $NO_3^-$-N) in a soil treated with heavy metals. A factorial combination of two heavy metals (Zn and Cd) treated with three concentrations (50, 100 and $150{\mu}mol\;g^{-1}$ soils) was used in a laboratory incubation. Nitrogen mineralization was determined at 3, 7, 14, 21, 28, 42 and 56 days after the treatments replicated four times. Soil sample free from heavy metals was served as the control. The amount of nitrogen mineralization from heavy metal treated soils was found to be decreased at an increasing rate during the first 21 days of incubation. However, as the incubation progressed, nitrogen mineralization was found to be decreased at decreasing rates. Furthermore, during this period, nitrogen mineralization in Cd treated soils was significantly lower ($P{\leq}0.05$) than that of the control. Soils treated with Cd at the concentration of $150{\mu}mol\;g^{-1}$ showed the lowest N mineralization throughout the incubation. Nitrogen mineralization in Zn treated soils ($50{\mu}mol\;g^{-1}$) was found to be higher than the other heavy metal treated soils. On the base of present findings, nitrogen mineralization of soil could be considered as a viable assessment of the degree of heavy metal pollution.