• Title/Summary/Keyword: 후보소재

Search Result 84, Processing Time 0.027 seconds

Effect of shield gas on weld quality in narrow gap TIG welding of alloy 617 (Alloy 617 내로갭 TIG용접에서 실드가스가 용접품질에 미치는 영향)

  • Ham, Hyo-Sik;Kim, Nam-Gyu;Kim, Beom-Jun;Kim, Mun-Gi;Bae, Dong-Ho;Cho, Sang-Myung
    • Proceedings of the KWS Conference
    • /
    • 2010.05a
    • /
    • pp.66-66
    • /
    • 2010
  • 국내 화력발전의 $CO_2$배출량을 크게 줄이고, 친환경, 그린 화력발전시스템을 위한 가장 효과적인 수단은 발전효율을 획기적으로 증대시키는 것이기 때문에 이를 목표로 한 기술개발은 경제적으로나 산업적으로 파급효과가 매우 크다. 발전효율 증대를 위한 핵심기술은 증기터빈의 성능향상이다. 현재 일본, 미국, EU 등 각국이 가장 관심을 가지고 기술개발에 심혈을 쏟고 있는 초내열, 내식 합금소재는 $700^{\circ}C$이상에서 기계적 성능을 보장할 수 있는 Ni기 합금개발이고, 현재까지 상당한 기술수준에 이르고 있는 것으로 파악되고 있다. 국내의 경우는 관련기술개발을 위해 연구가 진행되고 있으나, 기술적으로 아직 미흡한 수준이다. Ni기 초내열, 내식합금을 개발해서 그것을 화력발전용 증기터빈 부품, 특히 초내열합금 용접형 터빈로터 소재로 이용하기 위해서는 체계적이고 실용적인 연구를 통하여 용접형로타의 내구성과 신뢰성이 보장되는 최적 수준의 접합기술 개발이 선행되어야 한다. 따라서 본 연구는 선행연구로 $700^{\circ}C$이상 초내열/내식 Ni기 합금소재의 용접기술 개발을 위한 후보 소재 Alloy 617의 동종재료 용접 기술 개발을 목표로 한다. 본 연구는 Alloy617 12.6t 맞대기 이음으로 U그루브 내로갭 TIG용접을 하였다. 1pass 1layer 방식으로 총 8pass 8layer로 용접하였다. 전류 및 용접속도는 동일하게 두고 실드가스를 Ar 또는 Ar-$H_2$ 가스로 변경하여 시험하였다. Ar가스 TIG용접은 비드표면에 산화스케일이 생기고, 비드면이 거칠며 전체적으로 산화되었다. 반면에 Ar-$H_2$가스 TIG용접은 비드표면에 산화스케일이 없으며 표면이 미려하고 산화되지 않았다. 실드가스에 수소가스 첨가시 환원성가스로 역할을 하게 되고 이에 따라 용융지 표면에 산화피막을 제거하여 용접비드를 청정하게 하는 효과를 가진다.

  • PDF

점진적인 굴절률 변화를 갖는 투명전도 산화막이 실리콘 태양전지의 특성에 미치는 영향

  • O, Gyu-Jin;Kim, Eun-Gyu
    • Proceedings of the Korean Vacuum Society Conference
    • /
    • 2013.08a
    • /
    • pp.225.2-225.2
    • /
    • 2013
  • 실리콘기반의 광전변환 소자는 소자공정의 편의성, 소자 신뢰성, 화학적 안정성, 그리고 저가경쟁력 등의 이점 때문에 수 십 년간 널리 연구되어 왔다. 그러나, 실리콘 재료의 경우 높은 굴절률로 인해 표면에서 높은 광 반사도를 가지고 있다. 일반적으로, 태양전지의 광전변환 효율은 빛이 서로 다른 유전율을 가진 계를 통과할 때 발생하는 계면반사로 인한 물리적인 한계를 가진다. Indium Tin Oxide (ITO)는 발광 다이오드, 태양전지, 그리고 광 검출기 등의 광소자에 적용하기 위해 수 년간 투명전도 산화막 재료로서 연구되어 왔다. ITO의 뛰어난 광학적, 전기적 특성은 높은 투과도와 낮은 전기 전도도를 요구하는 소자 응용에 대해 유망한 후보로 거듭나게 했다. 게다가, ITO의 굴절률은 대략 2정도이다. 그 결과, ITO는 반도체 기반 태양전지의 무반사 코팅 소재로서도 장점을 가지고 있다. 본 연구는 전자빔 증착법으로 경사입사 증착을 하여 실리콘 기반 태양전지에 증착될 ITO 박막의 굴절률을 조절한다. 여기서, 실리콘의 굴절률은 대략 3.5정도이다. 그러므로, 더 나은 광학적 특성을 가지기 위해 다층으로 올려진 ITO 박막이 점진적인 굴절률 변화를 가지는 것을 필요로 한다. 점진적 굴절률 변화를 가진 무반사 박막이 실리콘 태양전지의 특성에 미치는 영향을 평가하기 위해 광전변환 효율을 측정하였다. 증착된 박막의 굴절률과 표면형상은 각각 타원편광분석과 Atomic Force Microscopy (AFM)을 통해 분석되었다. 또한, 소자의 단면형상은 Scanning Electron Microscopy (SEM)으로 측정되었다.

  • PDF

The Effect of Graphene on the Electrical Properties of a Stretchable Carbon Electrode (그래핀 첨가에 따른 신축성 카본전극의 전기적 특성 변화)

  • Lee, T.W.;Park, H.H.
    • Journal of the Microelectronics and Packaging Society
    • /
    • v.21 no.4
    • /
    • pp.77-82
    • /
    • 2014
  • Stretchable electrodes are focused due to many demands for soft electronics. One of the candidates, carbon black composites have advantages of low cost, easy processing and decreasing resistivity in a certain range during stretching. However, the electrical conductivity of carbon black composites is not enough for electronic devices. Graphene is 2-dimensional nanostructured carbon based material which shows good electrical properties and flexibility. They may help to improve electrical conductivity of the carbon black composites. In this study, graphene was added to a carbon black electrode to enhance electrical properties and investigated. Electrical resistivity of graphene added carbon electrode decreased comparing with that of carbon black electrode because graphene bridged non-contacting carbon black aggregates to strengthen the conductive network. Also graphene reduced an increase in the resistance of the carbon black electrode applied to strain because they connected gap of separated carbon black aggregates and aligned along the stretching direction at the same time. In conclusion, an addition of graphene to carbon black gives two benefits on the electrical properties of carbon black composite as a stretchable electrode.

고출력 LED 패키지용 고밀도 W-20wt%Cu 나노복합체 제조에 관한 연구

  • Ryu, Seong-Su;Park, Hae-Ryong;Kim, Hyeong-Tae;Lee, Byeong-Ho;Lee, Hyeok;Kim, Jin-U;Kim, Yeong-Do
    • Proceedings of the Materials Research Society of Korea Conference
    • /
    • 2010.05a
    • /
    • pp.26.2-26.2
    • /
    • 2010
  • 최근에는 차세대 조명용 후보광원인 고출력 백색 LED를 개발하기 위한 경쟁이 치열하며, 이를 위해 업체가 고심하고 있는 가장 큰 문제 중의 하나가 칩에서 발생하는 열을 어떻게 관리하는가 하는 방열의 문제이다. 따라서, LED의 가장 큰 특징인 장수명을 손해보지 않기 위해서는 칩에서 발생되고 있는 열을 외부에 확산시키기 위한 기술 개발이 필수적이다. 다양한 방열소재 중 W-Cu 복합재는 W의 낮은 열팽창계수와 Cu의 높은 열전도도로 인해 방열소재로써 유망한 소재로 주목받고 있으나, 우수한 열적 특성을 발현하기 위해서는 고치밀화를 갖는 W-Cu 복합재 제조가 우선적으로 필요하다. W-Cu 복합체는 일반적으로 액상소결법을 통해 균일한 미세조직을 얻을 수 있으나, 열팽창계수를 낮추기 위해 Cu 함량이 적어지게 되면 치밀화가 어려우며 이를 해결하기 위해 나노입자를 갖는 분말을 이용하고자 하는 연구가 많이 진행되고 있다. 본 연구에서는 W과 Cu 산화물을 이용하는 것이 구성성분끼리의 편석이 발생하지 않으며, 소결성도 우수하여 양산화에 가장 접근한 방법으로 알려져 있다. 그러나, 지금까지의 얻어진 W-Cu 복합체의 경우, 분말상태에서의 얻어진 나노입자가 승온시에 마이크로 크기로 과도한 입자성장이 일어나기 때문에 소결 후에도 나노크기를 유지하기 어려울 뿐만 아니라, 구성상끼리의 응집체가 형성된다. 본 연구에서는 액상소결후에 W 입자가 Cu 기지내에 균일하게 분산되는 동시에 나노크기의 입자를 가지는 고분산 W-Cu 소결체를 얻고자 하였다. 이를 위해 금속산화물 분말의 분쇄를 위해 효과적인 방법으로 알려진 습식상태에서의 고에너지 볼밀링을 통하여 혼합된 텅스텐과 구리 산화물 분말의 수소환원공정을 통해 얻어진 100nm 이하의 입자를 가지는 W-20wt%Cu 나노복합분말을 출발분말로 사용하였다. W-20wt%Cu 나노복합분말의 성형체를 $1050^{\circ}C-1250^{\circ}C$의 온도범위에서 소결거동을 조사하였다. 그 결과, $1100^{\circ}C$ 온도에서 이론밀도에 가까운 소결밀도를 나타내었으며, 이는 기존에 비해 $100^{\circ}C$ 정도 치밀화 온도를 낮추는 결과이다. 소결체의 미세구조 관찰결과, 소결 후 약 200nm의 텅스텐 입자가 Cu내에 균일하게 분산되어 있었다. 제조된 W-Cu 시편에 대해서는 LED 응용성을 조사하기 위해 열전도도와 열팽창계수 등을 평가하였다.

  • PDF

Efficacy of callus induced from Ullengdo niche plants for skin protection (식물세포배양기술을 이용한 울릉도 자생식물의 세포주 개발 및 피부세포 효능)

  • Choi, Yun Hui;Jung, Hae Soo;Cho, Moon Jin;Song, Mi Young;Seo, Hyo Hyun;Moh, Sang Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.15 no.8
    • /
    • pp.5070-5077
    • /
    • 2014
  • Many countries in the world have protected their native plants and utilized them as industrial materials in each country. In this aspect, it is increasingly important to develop cosmetics materials using native plants in Korea. Cosmetic materials have been developed with niche plants, such as Campanula takesimana Nakai, Dianthus superbus, Aster spathulifolius in Ullengdo, in which a specific plant distribution by distinct climate and environment was present. Water and ethanol extractions were performed from the calluses of Campanula takesimana Nakai, Dianthus superbus, Aster spathulifolius. HPLC analysis revealed different compositions and functions of effective elements in each ethanol extract. For example, all types of ethanol extracts showed an ability to heal wounds. In particular, the expression of the inflammation-related gene, COX-2, was decreased in response to the ethanol extracts of Dianthus superbus. These results indicate that the ethanol extracts from niche plants' calluses in Ullengdo are natural and environmentally-friendly compounds, and can be used as medical supplies associated with anti-inflammation and wound healing.

Anti-arthritic Activity of Artemisia princeps Pampanini on Complete Freund's Adjuvant-induced Arthritis (Artemisia princeps Pampanini의 complete freund's adjuvant 유발 관절염에 대한 개선 효과)

  • Kim, Ha-Rim;Kim, Sol;Kim, Seon-Young
    • Journal of Life Science
    • /
    • v.31 no.8
    • /
    • pp.736-744
    • /
    • 2021
  • Artemisia princeps Pampanini is an herbal medicine widely used to immune function-related diseases, such as anti-oxidative, anti-inflammatory, and antibacterial agents. In this study, we investigated the anti-inflammatory effects of AP extract and underlying mechanisms were evaluated in RAW 264.7 cells. The effects of AP extract were also studied in a complete Freund's adjuvant (CFA)-induced arthritis and lipopolysaccharide (LPS)-induced inflammation mouse model. In RAW 264.7 cells, AP extracts significantly inhibited the LPS-induced nitric oxide (NO) production and inducible NO synthase and cyclooxygenase-2 protein expression. The LPS-induced phosphorylation of mitogen-activated protein kinases and nuclear factor-κB was also significantly blocked by AP extract in RAW 264.7 cells. Oral administration of AP extract suppressed the increase in mouse paw edema and spleen index compared to CFA-treated mice group. Histologically, the infiltration of inflammatory cells was increased in cartilage and synovium in the CFA-treated mouse group, whereas it was suppressed in the AP extract-administered group. Furthermore, AP extract treatment significantly reduced the inflammatory cytokine, tumor necrosis factor-α, levels in CFA and LPS-treated mouse. In conclusion, the anti-inflammatory and anti-arthritis effect of AP extract was confirmed in both in vitro and in vivo models, suggesting that Artemisia princeps Pampanini may be a candidate material for arthritis treatment.

Case Study on Determination of the Level of New RoHS II Substances in Domestic Electronic and Electrical Equipments (국내 전기전자 제품에 함유된 신규 RoHS II 물질 검출 사례 연구)

  • Song, Moon-Hwan;Son, Seung-Hwan;Cho, Young-Dal;Choe, Eun-Kyung
    • Clean Technology
    • /
    • v.17 no.2
    • /
    • pp.124-133
    • /
    • 2011
  • In addition to six substances regulated in EU RoHS including lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls (PBB) and polybrominated diphenyl ethers (PBDE), priority substances are identified in new RoHS II as hexabromocyclododecane (HBCDD), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP) and diethylhexyl phthalate (DEHP). In this study, 20 plastic samples were collected from 12 domestic electrotechnical companies and levels of four restricted substances were determined by gas chromatography-mass spectrometry, Among 20 parts that compose washer, refrigerator or microwave oven, HBCDD was detected in three samples of NBR material with the amount of 42~381 mg/kg while DBP and BBP was not detected in any samples collected respectively, implying that these substance may not be used widely in plastic materials for EEE. However, DEHP was detected in all samples of NBR, PP, PBT, EPDM and PVC materials with the amount of 42 up to 59,400 mg/kg that exceeds the limit value of 0.1 wt% (1,000 mg/kg). Presence of a restricted substance in polymer material makes a great negative influence on a number of final product. To cope with coming RoHS II as well as REACH, action not to use DEHP in plastic material or the relevant notification in case of REACH seems to be needed. Screening test of Arsenic compounds such as diarsenic pentaoxide, diarsenic trioxide, lead hydrogen arsenate, triethyl arsenate that are included in REACH SVHC was done by ICP measurement Arsenium was detected in four samples made of NBR and PBT materials in the level of 15~700 mg/kg. By considering the screening method used in this study, the amount of arsenium compounds in the thermistor made of PBT material has a high chance of exceeding the regulated limit value.

Antibacterial and Anti-inflammatory Effects of Medicinal Plants Against Acne-inducing Bacteria (천연 약용식물 추출물의 여드름 원인균에 대한 항균 및 항염증 효과)

  • Lee, Eung-Ji;Bae, Seong-Yun;NamKung, Woo;Lee, Yong-Hwa
    • Journal of the Society of Cosmetic Scientists of Korea
    • /
    • v.36 no.1
    • /
    • pp.57-63
    • /
    • 2010
  • To develop natural therapeutic agents for acne vulgaris, we investigated antibacterial and anti-inflammatory effects of various medicinal plant extracts. Among candidate extracts, we selected Psoralea corylifolia L. extract (AC-1) and Magnoliae officinalis extract (AC-2) which showed the relatively high antibacterial effects, and Inula helenium L. extract (ACF-1) and Chrysanthemum zawadskii var. latilobum extract (ACF-2) which showed the relatively high anti-inflammatory effects for further investigations. All of them did not show cytotoxic effects below the concentration of $50{\mu}g/mL$. The antibacterial effects of AC-1, AC-2 and extract complex (AC) against P. acnes were 2.8, 2.5 and 3.2 times higher than that of 10 % salicylic acid respectively. And the antibacterial effect of AC-2 and extract complex against S. aureus were 1.4 and 1.5 times higher than that of 10 % methylparaben respectively. Also, it was shown that ACF-1, ACF-2 and extract complex had anti-inflammatory effects. All of them exhibited inhibitory effects for the secretion of IL-8 and TNF-$\alpha$ from THP-1 cells activated by heat-killed P. acnes. They reduced about 27 %, 38 %, 44 % of IL-8 secretion and 90 %, 88 %, 90 % of TNF-$\alpha$ secretion at concentration of $50{\mu}g/mL$ respectively. These results showed that the complex of medicinal plant extracts, AC-1. AC-2, ACF-1, and ACF-2, had therapeutic effects to acne vulgaris through antibacterial and anti-inflammatory effects. Therefore, we suggest that extract complex of AC-1, AC-2, ACF-1 and ACF-2 may be used as a useful agent for development of natural cosmetics which have therapeutic effects to acne vulgaris.

A Study on Changes of Confidence in Core Basic Nursing Skill by Each Period of Clinical Practicum of Nursing Students (간호대학생의 임상실습 시기별 핵심기본간호술 수행자신감의 변화양상)

  • Choi, Mi-Suk;Dong, Hwa-Jin
    • Journal of Digital Convergence
    • /
    • v.16 no.9
    • /
    • pp.329-338
    • /
    • 2018
  • The purpose of this longitudinal study was to investigate confidence in core basic nursing skill each period of clinical practicum and discover the changes, depending on characteristics of periods. The data was collected for 94 nursing students attending a university located in J-do from Mar. 9 to Dec. 16 2016 for 4 times in total. For data analysis, the frequency analysis, descriptive statistics and paired t-test were used. The research findings showed that confidence in core basic nursing skill by each period of clinical practicum was lowest before clinical practicum in general but gradually increased depending on lapse of time and experience of clinical practicum. However, it decreased in all items after having first clinical practicum in the $2^{nd}$ semester, compared to after first clinical practicum in the $1^{st}$ semester. In addition, the difference of confidence in core basic nursing skill between clinical practicum periods was higher after the first clinical practicum in the $1^{st}$ semester and after clinical practicum at the end of school year, compared to before clinical practicum and after the first clinical practicum in the $2^{nd}$ semester respectively. Therefore, this study suggested that it's necessary to have efficient and systematic clinical practicum education strategy, reflecting the characteristics of periods in clinical practicum in order to improve the confidence in core basic nursing skill of nursing students.

Effect of Extracts for Herbal Medicines on the Inhibition of Whole Blood Aggregation (한약재 추출물에 대한 전혈응집억제 효능 검색)

  • Jeon, Won-Kyung;Yoo, Bo-Kyung;Kim, Yeong-Eun;Park, Sun-Ok;Park, Sun-Min;Ko, Byoung-Seob
    • Applied Biological Chemistry
    • /
    • v.50 no.4
    • /
    • pp.352-357
    • /
    • 2007
  • For a correlation to study the five tastes and efficacies in oriental medicine concepts, we used herbal medicines with bitter taste character in traditionally effective and experimental methods. In this study, we tested the in vitro effect of 20 typical kinds of herbal medicines with bitter taste on platelet aggregation induced by collagen in human whole blood using the impedance method of aggregometry. Among them, 3 kinds of hot water extracts and 2 kinds of 70% ethanol extracts showed the significant inhibiting effect on whole blood aggregation $(^{***}p<0.001)$. In particular, Coptidis Rhizoma (Coptis chinensis) extracts were selected as the most effective candidate with a strong grade of bitter taste through the sensory test of trained panels. The results from this experiment provide pharmacological evidence for the traditional use of bitter tasting herbs with traditional medicine theory, suggesting that strong bitter taste herbs could be help problems of blood circulation more than mild bitter tasting herbs.