• 제목/요약/키워드: step heat treatment

검색결과 235건 처리시간 0.022초

가시광 활성을 위한 N-doped Na2Ti6O13@TiO2 복합체 제조 및 특성 연구 (Preparation and Characterization of N-doped Na2Ti6O13@TiO2 Composites for Visible Light Activity)

  • 이덕희;박경수
    • 한국분말재료학회지
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    • 제29권6호
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    • pp.492-498
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    • 2022
  • N-doped Na2Ti6O13@TiO2 (denoted as N-NTO@TiO2) composites are successfully synthesized using a simple two-step process: 1) ball-milling of TiO2 with Na2CO3 followed by heat treatment at 900℃; 2) mixing of the prepared Na2Ti6O13 with titanium isopropoxide and calcining with urea at 500℃. The prepared composites are characterized using XRD, SEM, TEM, FTIR, and BET. The N-NTO@TiO2 composites exhibit well-defined crystalline and anatase TiO2 with exposed {101} facets on the external surface. Moreover, dopant N atoms are uniformly distributed over a relatively large area in the lattice of the composites. Under visible light irradiation, ~51% of the aqueous methylene blue is photodegraded by N-NTO@TiO2 composites, which is higher than the values shown by other samples because of the coupling effects of the hybridization of NTO and TiO2, N-doping, and presence of anatase TiO2 with exposed {101} facets.

카본 코팅된 니켈-코발트 황화물의 요크쉘 입자 제조 및 소듐 이온 배터리의 음극 소재 적용 (Synthesis of Carbon Coated Nickel Cobalt Sulfide Yolk-shell Microsphere and Their Application as Anode Materials for Sodium Ion Batteries )

  • 서효영;박기대
    • 한국분말재료학회지
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    • 제30권5호
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    • pp.387-393
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    • 2023
  • Transition metal chalcogenides are promising cathode materials for next-generation battery systems, particularly sodium-ion batteries. Ni3Co6S8-pitch-derived carbon composite microspheres with a yolk-shell structure (Ni3Co6S8@C-YS) were synthesized through a three-step process: spray pyrolysis, pitch coating, and post-heat treatment process. Ni3Co6S8@C-YS exhibited an impressive reversible capacity of 525.2 mA h g-1 at a current density of 0.5 A g-1 over 50 cycles when employed as an anode material for sodium-ion batteries. However, Ni3Co6S8 yolk shell nanopowder (Ni3Co6S8-YS) without pitch-derived carbon demonstrated a continuous decrease in capacity during charging and discharging. The superior sodium-ion storage properties of Ni3Co6S8@C-YS were attributed to the pitch-derived carbon, which effectively adjusted the size and distribution of nanocrystals. The carbon-coated yolk-shell microspheres proposed here hold potential for various metal chalcogenide compounds and can be applied to various fields, including the energy storage field.

RF 열플라즈마를 이용한 Y2O3:Eu3+ 적색 나노 형광체 분말 합성 (Synthesis and characterization of Y2O3 : Eu3+ red nano phosphor powders using RF thermal plasma)

  • 이승용;구상만;황광택;김진호;한규성
    • 한국결정성장학회지
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    • 제25권6호
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    • pp.272-279
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    • 2015
  • $Y_2O_3:Eu^{3+}$는 우수한 적색 발광 특성을 가지고 있는 형광체로 최근 고화질 디스플레이에 대한 수요가 증가함에 따라 관련 연구가 활발히 진행되고 있다. 본 연구에서는 RF 열플라즈마 합성법과 고상법을 이용하여 $Y_2O_3:Eu^{3+}$ 적색 형광체를 합성하였으며, 합성 방법에 따른 $Y_2O_3:Eu^{3+}$ 적색 형광체의 결정 구조, 미세 구조, 발광 특성의 차이를 XRD, TEM, PL 분석을 통해 비교하였다. 고상법으로 합성된 $Y_2O_3:Eu^{3+}$ 적색 형광체의 입자는 약 $10{\sim}20{\mu}m$ 크기를 가지는 반면, RF 열플라즈마 합성법을 통해 합성된 적색 형광체는 반응부는 약 100 nm, 필터부는 약 30 nm의 크기를 갖는 나노 형광체로 확인되었다. 합성된 모든 분말들은 PL 측정결과 611 nm($^5D_0{\rightarrow}^7F_2$)에서 발광하는 것을 확인하였으며, 결정 크기와 입도가 증가할수록 PL intensity가 증가하였다. 또한, 추가 열처리 공정이 필요 없는 one-step 공정의 RF 열플라즈마 공정을 통해 합성된 $Y_2O_3:Eu^{3+}$ 적색 나노 형광체는 고상법으로 합성된 적색 형광체와 비슷한 발광 특성을 보이는 것을 확인할 수 있었다.

활성탄에 의한 Acid Fuchsin 염료의 흡착에 대한 등온선, 동력학 및 열역학 특성치에 대한 해석 (Analysis on Isotherm, Kinetic and Thermodynamic Properties for Adsorption of Acid Fuchsin Dye by Activated Carbon)

  • 이종집
    • Korean Chemical Engineering Research
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    • 제58권3호
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    • pp.458-465
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    • 2020
  • 활성탄에 의한 acid fuchsin (AF) 염료의 흡착에 대한 등온선, 동력학 및 열역학적 특성치를 흡착제의 양, pH, 초기 농도, 접촉시간 및 온도를 변수로 하여 수행하였다. 활성탄을 사용한 AF의 흡착에 대한 pH의 영향은 산성(pH 8)에서 흡착백분율이 높은 욕조 현상을 나타냈다. 등온흡착 데이터는 Freundlich, Langmuir, Dubinin-Radushkevich 등온흡착식에 맞춰 보았다. Freundlich 식이 가장 높은 일치도를 나타냈으며, 흡착메카니즘이 다분자층 흡착임을 알았다. 흡착용량은 온도증가와 함께 증가하였다. Freundlich의 분리계수는 이 흡착공정이 적합한 처리공정임을 나타냈다. Dubinin-Radushkevich 등온흡착식에 의해 평가된 흡착 에너지는 활성탄에 의한 AF의 흡착이 물리 흡착임을 확인시켰다. 흡착동력학은 유사이차반응속도식에 잘 맞았다. 입자내 확산 모델에 의해 흡착점에서의 표면 확산이 율속단계로 평가되었다. 흡착공정의 활성화 에너지와 엔탈피 변화는 각각 21.19 kJ/mol, 23.05 kJ/mol 이었다. Gibbs 자유 에너지 변화는 흡착반응이 온도가 높아질수록 자발성이 더 진다는 것을 알려주었다. 양의 엔트로피는 이공정이 비가역적이라는 것을 나타냈다. 등량 흡착열은 본질덕으로 물리흡착임을 나타냈다.

여성노인의 낙상실태 및 충격보호팬츠 개발을 위한 기초 연구 (Basic Study on the Development of Impact Protective Pants and Falls of Elderly Women)

  • 이진숙;박정현;이정란
    • 한국의류산업학회지
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    • 제16권6호
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    • pp.945-953
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    • 2014
  • This study aims to develop protective pants to relieve impact from falls and to present basic data for the development. The survey results are as follows; First, 45% of the respondents were in their 60s and 55% of them were in their over 70s and older. Also, 64% of them have fallen once for the past year and 36% of them have fallen twice or more. The older they were, the more there were those who have fallen twice or more. This indicated the older people has experienced more fall accidents again after a initial fall accident. Second, as per accident situations, the survey showed that fall accidents happened the most in the winter and in the afternoon (12-18 pm). Also, it happened on a street mostly and they were wearing sneakers or hiking boots when they got a hurt slipped in a front or side by missing their step in a walk. The injury areas are mostly knee and ankle. They had the bruises or a sprain in their knee and ankle mostly. The rate of bone fracture was 19.5%. Therefore, the protection area to falls in lower body is the knee. But hip and hip joint should be protected with knee as well because those are usually be broken when it is damaged. Third, approximately 80% of those who were hospitalized for treatment had surgery. Patients who had surgery were rather in their over 70s than in their 60s. The older they were, the more serious their fracture was. The period of hospital or outpatient treatment is more than three weeks in many cases. They responded their health got worse after falls. Aftereffects of accidents were physical discomfort, anxiety and medical costs. Falls to the old makes physical damage, psychological damage, which cause reduced physical activity and the increased cost of health care with economic losses. So it results on a negative impact on the life of the old. Fourth, elderly females were rarely aware of impact protective clothing and they have never purchased such clothing. For impact protective pants, the major consideration was suitable design for their body types. They liked casual style with front or side pockets and simple designs without any patterns or decorations. As per pants materials, they responded that they need functionality, activity and elasticity. Among the functional points, insulation of cloths are considered importantly, so the heat reservance of material in the impact protective pants should be considered carefully.

Green Light-Emitting Phosphor, Ba2xCaMgSi2O8:Eux

  • Kim, Jeong-Seog;Piao, Ji-Zhe;Choi, Jin-Ho;Cheon, Chae-Il;Park, Joo-Suk
    • 한국세라믹학회지
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    • 제42권3호
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    • pp.145-149
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    • 2005
  • [ $Eu^{2+}$ ]-activated barium magnesium silicate phosphor, $(Ba,Ca)_{3}MgSi_{2}O_{8}:Eu_{x}$, has been known to emit blue-green light. In this study we report the manufacturing processes for producing either pure green or pure blue light-emitting phosphor from the same composition of $Ba_{2-x}Ca_{2}CaMgSi_{2}O_{8}:Eu_{x}$ (0 < x < 1) by controlling heat treatment conditions. Green light emitting phosphor of $Ba_{1.9}CaMgSi_{2}O_{8}:Eu_{0.1}$ can be produced under the sample preparation condition of highly reducing atmosphere of $23\%\;H_2/77\%\;N_2$, while blue or blue-green light emitting phosphor under reducing atmosphere of $5\~20\%\;H_2\;/\;95\~80\%$ N_2. The green light-emitting phosphors are prepared in two steps: firing at $800\~1000^{\circ}C$ for $2\~5$ h in air then at $1100\~1350^{\circ}C$ for 2-5 h under reducing atmo­sphere $23\%$ $H_2/77\%\;N_2$. The excitation spectrum of the green light-emitting phosphor shows a broadband of $300\~410$ nm. The emission spectrum has a maximum intensity at the wavelength of about 501 nm. The CIE value of green light emission is (0.162, 0.528). The pure blue light-emitting phosphors can be produced using the $Ba{2_x}CaMgSi_{2}O_{8}:Eu_{x}$ by introducing additional firing step at $1150\~1300^{\circ}C$ in air before the final reducing treatment. The XRD analysis shows that the green light-emitting phosphor mainly consisted of $Ba_{1.31}Ca_{0.69}SiO_{4}$ (JCPDS $\#$ 36-1449) and other minor phases i.e., $MgSiO_3$ (JCPDS $\#$ 22-0714) and $Ca_{2}BaMgSi_{2}O_{8}$ (JCPDS $\#$ 31-0128). The blue light-emitting phosphor mainly consisted of $Ca_{2}BaMgSi_{2}O_{8}$ phase.

이산화탄소 광물고정화 효율 증가를 위한 사문석의 화학적 전처리에 관한 연구 (Evaluation of Chemical Pre-treatment for the Optimization of CO2 Fixatiom Using by Carbonation Reaction with Serpentine)

  • 장나형;심현민;허려화;김형택
    • 공업화학
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    • 제19권5호
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    • pp.526-532
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    • 2008
  • 이산화탄소는 산업의 발달과 더불어 배출이 증가되고 있는 온실가스 중에 하나로 발생되는 이산화탄소의 일부는 탄소순환과정에 의해 자연계로 순환되지만, 순환될 수 있는 범위를 넘어선 이산화탄소는 적절한 포획과 처리가 필요하다. 이산화탄소 처리 기술 중 광물고정화 방법은 영구적으로 이산화탄소를 처리할 수 있는 방법으로 인식되고 있다. 본 연구에서는 광물고정화의 효율을 높이기 위해, 화학적전처리법을 사용하였다. 화학적전처리법(leaching)은 규산염광물의 알칼리토금속성분(Mg, Ca)이 이산화탄소와 탄산염광물화 반응을 통해 광물고정화가 진행되는 방법임에 착안하여, 산(acid)을 이용해 알칼리토금속성분을 추출해 내 이산화탄소와의 반응 양을 증가시켜 고정화 효율을 높이는 방법이다. 다양한 농도(2 M, 4 M, 6 M)의 황산을 사문석과 반응온도(25, 50, $75^{\circ}C$)와 반응시간(1, 3, 5, 24 h)을 변화시켜 추출된 알칼리토금속성분(Mg, Ca)을 ICP-AES를 이용해 분석하였고 SEM과 BET를 이용하여 황산이 사문석 표면에 미치는 영향에 대해 알아보았는데, 사문석이 황산과 반응하여 표면이 거칠어지며, 비표면적이 $11.1209m^2/g$에서 $98.7903m^2/g$로 증가함을 알 수 있었다. 또 세 변수 모두 증가할수록 추출량도 증가하는 것으로 나타났으며, 특히 $75^{\circ}C$의 경우에는 반응 시간이 1 h 이후에는 시간과 관계없이 포화 추출점에 이르는 것을 확인하였다. 화학적 전처리의 결과 고정화 효율이 23.24%에서 46.30%까지 향상됨을 확인 하였다.

CATTS를 이용한 복숭아순나방 사과 수확 후 방제 기술 (A Postharvest Control Technique of the Oriental Fruit Moth, Grapholita molesta, Infesting Apples Using CATTS)

  • 정충렬;권기면;김용균
    • 한국응용곤충학회지
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    • 제53권1호
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    • pp.73-80
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    • 2014
  • 수확 후 해충방제가 국내 수요 농산물은 물론이고 검역 문제를 해결하기 위한 수출용 농산물에 대해서 요구되고 있다. 특별히 유기 농산물 또는 환경친화형 재배 농산물에 대해서 메틸브로마이드와 같은 화합물을 이용한 기존의 수확 후 처리기술은 의미를 잃게 되었다. 대체 기술로서 CATTS (환경조절열처리기술)라 명명된 물리적 처리기술이 개발되어 사과와 여러 핵과류 과실을 가해하는 곤충과 응애에 적용되고 있다. 본 연구는 국내 사과 수출을 위해 수입국에서 규제하는 복숭아순나방(Grapholita molesta)을 대상으로 CATTS 처리 조건을 결정하는 데 목표를 두었다. 이 해충에 CATTS를 적용하기 위해 사과 과실에 잔류하면서 열에 높은 내성을 보이는 발육시기를 분석하였다. 열처리 조건($44^{\circ}C$, 20분)에서 5령 유충이 가장 높은 내성을 보였다. 환경조건(15% $CO_2$, 1% $O_2$)에서 기기 내부 온도가 $25^{\circ}C$에서 $46^{\circ}C$까지 증가하는 시기를 CATTS 가열단계로 볼 때, 이 가열 속도가 빠를수록 CATTS 해충 방제 효과가 높았다. 또한 가열단계 후 CATTS 처리 시간이 길수록 CATTS 효율이 증가했다. 특히 가열단계에서 과실 내부온도가 $44^{\circ}C$로 이르게 하는 것이 CATTS 효율을 높이는 데 결정적이었다. 이러한 조건들을 종합하여 CATTS 표준 처리기술을 결정하였으며, 이 기술은 2,104 마리의 5령을 포함한 4,378 마리 복숭아순나방 유충 피해를 받은 사과에 대해서 100% 방제 효과를 나타냈다.

동병하치 확산을 위한 전략적 방향과 이행방안 (Strategic Direction and Road Map of Expanding Prevention of Winter Disease in the Summer)

  • 송호섭
    • Journal of Acupuncture Research
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    • 제27권3호
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    • pp.147-157
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    • 2010
  • Objectives : The purpose of this study was to propose appropriate strategic directions and road maps for successful achievement of programs preventing winter disease in the summer. Methods : Details on programs preventing winter disease in the summer such as clear concept, theoretical basis, current status, intervention or available prescriptions and indication/contraindication/caution were prepared through the related journal review, upon which an observational study was devised and done for simulation to find out even a trivial problem and to guarantee the safety beforehand. The experimental group was divided into 5 groups by the size of pill and the way ginger is treated; 1cm pill with ginger group, 3cm pill group without ginger, 3cm pill group dipped into ginger, 3cm pill group applying ginger to acupoints and 3cm pill group with ginger Results 1. program preventing winter disease in the summer was defined as representative winter diseases such as common cold, influenza, chronic asthma, chronic bronchitis, allergic rhinitis, emphysema, chronic gastritis and rheumatoid arthritis, and preventive care in the summer, reinforcing deficient yang qi of five viscera by using exuberant yang qi from summer heat. 2. It was based upon historically established theories which is 'nourishing yang qi in the spring and summer', 'long summer, namely rainy spell in the summer overwhelms the winter, because of earth winning water according to the five phases theory' and 'To replenish yang qi is major principle to treat winter diseases, which can be most appropriately and timely applied to the patient with deficient yang qi of five viscera inherently, especially in the three dog days of the summer, because of exuberant exterior yang qi and deficient interior yang qi in the five viscera'. 3. In the adjacent China and Taiwan, acupoint applying method in the three dog days named 'San Fu Tie' have been stirring a boom throughout the nation, in which Xiaochuan Gao was used as a basic prescription and it mainly was applied at bilateral $BL_{13}$, $_{15}$ and $_{17}$ for about 4 hours. As far as domestic current status, the necessity of adopting the above method prior to Herbal formula was also recognised, because not a few koreans have apprehension for the safety of it including medicinal herbs and are reluctant to take it any more due to negative advertisement of narrow minded doctors' association. 4. Indication of acupoint applying method in the three dog days included most of winter diseases such as common cold, influenza, chronic asthma, chronic bronchitis, allergic rhinitis, emphysema, chronic gastritis. contraindication was pregnant woman and the weak such as infants and the old. More attention was paid to grasp firmly the normal reaction following the treatment for preventing side effect and teasing blister. recommendation was also given to abstain from food inducing phlegm and dampness such as meat, shrimp and crab as well as cold drinks and foods 5. In the simulation observational study based upon the above findings following review the related articles, no blister was shown on the acupoints icluding bilateral $BL_{13}$, $_{15}$ and $_{17}$ in every experimental group during 24hr observation following the acupoint applying treatment with pills made by modified and devised prescription. At 4 hr, the effectiveness of it reached a peak showing redness and mild tenderness and there is little difference between groups 3cm pills groups regardless of the way ginger was treated. abdominal distention and growling was found in all the volunteers during the treatment at CV 8. Strategic directions and road maps : Through successful fulfillment of the program preventing winter disease in the summer, Korean traditional medicine should be integrated into mainstream national health care services. Cultural access was thought to be as important as Scientific EBM approach. First of all, To evoke potential cultural homogeneity from campaigns and press advertisement was needed for promoting public awareness about preventing winter disease in the summer by enhancing immunity via acupoint applying treatment in the three dog days, and then indigenous name as Sambokcheop, protocol, Clinical Research Form for data collection of it should be developed and prepared. Once the first step was taken this summer, through a thorough data collection and scrutinized scientific evaluation, drawbacks should be compensted for and the efficacy and safety should be substantiated.

일축가압/스크린인쇄 공정에 의해 제조된 음극지지형 SOFC의 출력특성 (Power Generating Characteristics of Anode-Supported SOFC fabricated by Uni-Axial Pressing and Screen Printing)

  • 정화영;노태욱;김주선;이해원;고행진;이기춘;이종호
    • 한국세라믹학회지
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    • 제41권6호
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    • pp.456-463
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    • 2004
  • 음극지지형 SOFC의 성능을 향상시키기 위해 단전지 제조공정을 개선하고 그 출력특성을 평가하였다. 액상응결 공정(Liquid Condensation Process : LCP)과 일축가압성형공정을 통하여 NiO/YSZ 복합체 음극기판을 제조하고 위에 YSZ 전해질을 스크린 인쇄한 후 140$0^{\circ}C$에서 3시간동안 동시소결하여 음극/전해질 기판을 제조하였다. 또한 LSM/YSZ 양극층은 임피던스 분석을 통해 분극저항이 최소가 되는 조성 및 열처리 조건을 선택하여 스크린 인쇄법을 이용해 구성하였고 이러한 적층공정을 거쳐 최종적으로 5${\times}$5와 l0${\times}$10 $\textrm{cm}^2$ 크기의 단전지를 제조하였다. 제조된 단전지의 출력특성을 측정한 결과 5${\times}$5와 10${\times}$10 단전지는 80$0^{\circ}C$에서 약 0.45W/$\textrm{cm}^2$ 와 0.22 W/$\textrm{cm}^2$의 최대출력밀도를 각각 나타내어 선행연구에서 기존공정으로 제조된 단전지에 비해 2배 이상 향상된 좋은 성능을 나타내었다.