• Title/Summary/Keyword: 열분석적 특성

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An Experimental Study on the Quality Properties of the Expansive for Dry-Shrinkage Compensation of the On-Dol Floor Mortar (온돌바닥 모르터의 건조수축 보상을 위한 팽창재의 품질특성에 관한 실험연구)

  • 이종열;이웅종;정성철
    • Journal of the Korea Concrete Institute
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    • v.13 no.4
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    • pp.314-320
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    • 2001
  • In this paper, the properties of an expansive agent (CaO-CaS $O_4$) for dry shrinkage compensation were investigated by a series of experimental program, which might be used at On-Dol heating system as mortar type. The expansion principle of the CaO-CaS $O_4$ was mainly verified. As a result of this study, the correlation between the content of the expansive agent and the compressive strength was obtained in the form of exponential function(Y = A $e^{-x}$), showing that as the content of expansive agent increased as the expansion performance with the compressive strength increased by only a certain amount. Also, as a results of the analysis of a correlation between the expansive performance and the chemical properties which generally accompanied a part of quality management in manufacturing the expensive cement, the expansive performance was relative to only the contents of the F-CaO among chemical properties(Blaine, +44$\mu\textrm{m}$R, F-CaO, S $O_3$,L.O.I). And it was clarified that the results were relative to the second order function, showing that if the contents of the F-CaO increased the expansive performance Increased.d.

Synthesis and Characterization of 4-Component Polyimide Films with Various Diamine and Dianhydride Compositions (다양한 조성 변화에 따른 4성분계 폴리이미드 필름 제조와 물성분석)

  • Park, Yun Jun;Yu, Duk Man;Choi, Jong Ho;Ahn, Jeong-Ho;Hong, Young Taik
    • Applied Chemistry for Engineering
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    • v.22 no.6
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    • pp.623-626
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    • 2011
  • Various poly(amic acid)s were synthesized from PMDA/BPDA/p-PDA/ODA with different mole ratios and effectively converted into 4-component polyimide films by thermal imidization. The chemical structures and thermo-mechanical properties of polyimide films were examined using Fourier transform infrared spectroscopy (FT-IR), thermo-gravimetric analyzer (TGA), thermo-mechanical analyzer (TMA), dynamic mechanical analyzer (DMA) and universal tensile machine (UTM). The tensile strength, modulus, and thermal properties of polyimides films increased with the amount of rigid PMDA and p-PDA, while the elongation and moisture absorption of polyimide films increased with the amount of flexible BPDA and ODA. One of 4-component polyimide films exhibited a similar coefficient of thermal expansion (CTE) value to that of copper when it was composed of PMDA : BPDA : p-PDA : ODA with the ratio of 5 : 5 : 4 : 6. Thus, this polyimide film could be useful for a base film for flexible copper clad laminates (FCCL) of flexible printed circuit boards.

Material Characteristics of White Wares from Yeongdong Province, Gangwon-do: Gangneung and Donghae Kiln Sites (강원 영동지역 백자의 재료과학적 특성 연구: 강릉 남양리 백자가마터와 동해 발한동2(사문동) 가마터를 중심으로)

  • Lee, Byeong Hoon;So, Myoung-Gi
    • Journal of Conservation Science
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    • v.31 no.3
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    • pp.181-192
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    • 2015
  • This study aims to examine production technique of twelve white wares from the Gangneung Namyang-ri and Donghae Balhan-dong2(Samun-dong) kiln sites, Kangwon Province and characteristics of the used materials, and to find a correlation among materials of the excavated white wares. X-ray fluorescence sequential spectroscopy(XRF), X-ray diffraction(XRD), Dilatometer and Inductively coupled plasma mass spectrometry(ICP-MS), Inductively coupled plasma automic emission spectrometer(ICP-AES) were applied to determine the chemical composition, crystalline phase of samples, firing temperatures, trace elements and rare earth elements. When analyzing body crystalline phases of the white wares using the XRD method, quartz and mullite were extracted from all the samples. Though firing temperature of each sample was different, they were mostly fired at a temperature below $1200^{\circ}C$. Analyzing the excavated white wares using the Seger formula, compositional properties of white wares in Gangneung Namyang-ri kiln showed diffrently from the Donghae Balhan-dong2(Samun-dong) kiln. The body of white wares from Gangneung Namyang-ri kiln have higher raito of $RO_2$ and $RO+R_2O$ than of white wares from Donghae Balhan-dong2(Samun-dong) kiln site. The white wares from Gangneung Namyang-ri kiln and Donghae Balhan-dong2(Samun-dong) kiln were made of host rocks of the different geological origin, according to the result of rare earth elements analysis.

The Study on the Crystalline Structure and Corrosion Property of the Zn-Mg Coatings as a function of Deposition Temperature (합성 온도에 따른 Zn-Mg 박막의 결정구조, 내식특성에 관한 연구)

  • Ra, Jeong-Hyeon;Bae, Gi-Tae;Lee, Sang-Yul
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2016.11a
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    • pp.178-178
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    • 2016
  • 최근 Zn-Mg 합금 박막은 고내식성의 합금상 형성, 치밀한 부식생성물의 부식억제 등으로 인해 순수한 Zn 박막 및 기타 Zn 계 합금 박막 대비 우수한 내식성을 나타난다고 보고되고 있다. 그러나 여러 문헌에서 보고된 Zn-Mg 박막 각기 다른 결정구조, 미세조직을 나타내며, 이는 Zn-Mg 박막이 낮은 융점을 나타내기 때문에 박막 합성 공정 중에 발생하는 열량에 따라 Zn-Mg 박막의 결정구조, 미세조직 등이 변화한 것으로 판단된다. 본 연구에서는 Zn-Mg 박막의 결정구조에 따른 내식특성을 평가하기 위하여 비대칭 마그네트론 스퍼터링 공정 중 합성온도를 제어하며 Zn-Mg 박막을 합성하였으며 그에 따른 박막의 결정구조, 내식성에 관해 연구하였다. Zn-Mg 박막은 10wt.% Mg 합금 타겟을 사용하였으며, 합성 온도는 상온에서 최고 $150^{\circ}C$로 제어하였다. Zn-Mg 박막의 결정구조, 미세조직은 X선 회절 분석기 (XRD)와 전계방출형 주사전자현미경 (FE-SEM)을 사용하여 분석하였으며, 동전위 분극시험을 통해 결정구조에 따른 Zn-Mg 박막의 내식성을 분석하였다. 상온에서 합성한 Zn-Mg 박막은 비정질의 결정구조가 형성되었으며, 상온이상 $50^{\circ}C$이하에서는 결정질의 Zn 상과 비정질상이 공존하는 Zn-Mg 박막이 합성되었다. 또한 $100^{\circ}C$이상에서는 Zn, $Mg_2Zn_{11}$, $MgZn_2$ 상이 공존하는 결정질의 Zn-Mg 박막이 합성되었다. 상온에서 합성된 Zn-Mg 박막의 경우 급냉이 이루어지는 스퍼터링 공정의 특성상 비정질의 결정구조가 형성되었으나, Zn는 융점이 낮아 상온부근에서도 재결정이 이루어지기 때문에 $50^{\circ}C$ 이하의 낮은 온도에서 합성하여도 결정질의 Zn 상이 형성되었다. $Mg_2Zn_{11}$, $MgZn_2$ 과 같은 Zn와 Mg의 합금상의 경우 형성과정에서 일정 수준의 열이 요구되기 때문에 낮은 온도에서는 형성이 억제되고 일정 이상의 온도에서 형성되었다. FE-SEM 분석 결과를 통하여 $50^{\circ}C$ 이하의 낮은 온도에서 합성한 Zn-Mg 박막은 치밀한 미세구조를 나타내었으며, $100^{\circ}C$이상에서 합성한 Zn-Mg 박막의 미세구조는 밀도가 비교적 낮은 구조임을 확인하였다. 3.5% NaCl 수용액에서의 동전위 분극시험 결과 낮은 온도에서 합성한 Zn-Mg 박막이 고온에서 합성한 Zn-Mg 박막 대비 치밀한 구조가 형성되었기 때문에 우수한 내식성을 나타내었다.

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Numerical Study of Combustion Characteristics by Pressure and Oxygen Concentration in Counter-Flow Diffusion Flame Model (대향류 확산 화염 모델에서의 압력 및 산소분율에 따른 연소 특성 변화에 관한 수치해석 연구)

  • Park, Jinje;Lee, Youngjae
    • Clean Technology
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    • v.27 no.1
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    • pp.93-103
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    • 2021
  • As the seriousness and necessity of responding to climate change and reducing carbon emissions increases, countries around the world are continuing their efforts to reduce greenhouse gases. Among various efforts, research on CCUS, capturing and utilizing carbon dioxide generated when using carbon-based fuels, is actively being conducted. Studies on pressurized oxy-fuel combustion (POFC) that can be used with CCUS are also being conducted by many researchers. The purpose of this study is to analyze basic information related to the flame structure and pollutant emissions of pressurized oxy-fuel combustion. For this, a counter-flow diffusion flame model was used to analyze the combustion characteristics according to pressure and oxygen concentration. As the pressure increased, the flame temperature increased and the flame thickness decreased due to a reaction rate improvement caused by the activation of the chemical reaction. As oxygen concentration increased, both the flame temperature and the flame thickness increased due to an improvement to the reaction rate and diffusion because of a change in oxidizer momentum. Analyzing the related heat release reaction by dividing it into three sections as the oxygen concentration increased showed that the chemical reaction from the oxidizer side was subdivided into two regions according to the mixture fraction. In addition, the emission index of NO classified according to the NO formation mechanism was analyzed. The formation trend of NO according to each analysis condition was presented.

Development and Verification of Smart Greenhouse Internal Temperature Prediction Model Using Machine Learning Algorithm (기계학습 알고리즘을 이용한 스마트 온실 내부온도 예측 모델 개발 및 검증)

  • Oh, Kwang Cheol;Kim, Seok Jun;Park, Sun Yong;Lee, Chung Geon;Cho, La Hoon;Jeon, Young Kwang;Kim, Dae Hyun
    • Journal of Bio-Environment Control
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    • v.31 no.3
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    • pp.152-162
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    • 2022
  • This study developed simulation model for predicting the greenhouse interior environment using artificial intelligence machine learning techniques. Various methods have been studied to predict the internal environment of the greenhouse system. But the traditional simulation analysis method has a problem of low precision due to extraneous variables. In order to solve this problem, we developed a model for predicting the temperature inside the greenhouse using machine learning. Machine learning models are developed through data collection, characteristic analysis, and learning, and the accuracy of the model varies greatly depending on parameters and learning methods. Therefore, an optimal model derivation method according to data characteristics is required. As a result of the model development, the model accuracy increased as the parameters of the hidden unit increased. Optimal model was derived from the GRU algorithm and hidden unit 6 (r2 = 0.9848 and RMSE = 0.5857℃). Through this study, it was confirmed that it is possible to develop a predictive model for the temperature inside the greenhouse using data outside the greenhouse. In addition, it was confirmed that application and comparative analysis were necessary for various greenhouse data. It is necessary that research for development environmental control system by improving the developed model to the forecasting stage.

Nutritional Characteristics of Ice Cream Added with Citron(Citrus junos Sieb ex Tanaka) Juice (유자 착즙액 첨가 아이스크림의 영양학적 특성)

  • 김성현;최덕주;신정혜;이준열;성낙주
    • The Korean Journal of Food And Nutrition
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    • v.17 no.2
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    • pp.212-219
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    • 2004
  • In this study, we compared that sensory characteristics and nutritional components of ice cream supplements with various levels(1, 2, 3%) raw and frozen citron juice. Vitamin C was not detected in frozen citron juice 1% added group. The content of vitamin C was 4.7 mg/100g in raw citron juice 3% added group. But it detected 1.0 mg/100g in 3% frozen citron juice added group. Free sugars were detected sucrose, lactose and maltose. Those amounts of all samples were lower than control group and were lower goes to citron juice added ratio higher. Organic acids in ice creams were detected oxalic acid, malonic acid, malic acid and citric acid. The citric acid content was higher than other organic acid. Especially, citric acid content was the highest in raw citron juice 3% added group (6.3 mg/100g). But it's content was low in all frozen citron juice added groups (0.5-0.6 mg/100g). Mineral contents of ice creams were highest in raw citron juice 3% added group (3399.96 mg/100g). The results of sensory test, citron aroma and citron taste were the highest in raw citron juice 3% added group. Overall acceptability was the highest in frozen citron juice 2% added group.

Physicochemical Quality and Luminescence Characteristics of Gamma-irradiated Dried Fish Products (감마선 조사에 따른 건포류의 이화학적 품질 및 발광 특성)

  • Park, Eun-Joo;Jang, Han-Na;Jo, Deokjo;Kim, Gui-Ran;Kwon, Joong-Ho
    • Korean Journal of Food Science and Technology
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    • v.45 no.2
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    • pp.167-173
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    • 2013
  • Dried fish products, such as seasoned cuttlefish, anchovy, and filefish, were analyzed to investigate the physicochemical quality and luminescence properties following gamma-irradiation. The overall color difference slightly increased in all irradiated samples, showing significant changes in Hunter's L, a, and b color values. Cuttlefish and filefish showed higher values in hydrophilic browning, whereas anchovy showed a higher value in lipophilic browning. The brown color intensity of filefish showed a dose-dependent increase. The thiobarbituric acid (TBA) value significantly increased in irradiated samples of cuttlefish and anchovy, which have relatively high lipid contents. Irradiated samples, except anchovy, were not suitable for screening using photostimulated luminescence (PSL) because only negative or intermediate values were observed. Thermoluminescence (TL) measurements were suitable for all fish samples, i.e., irradiation-specific glow curves were obtained, signal intensity increased, and the TL ratio fulfilled the criterion. There was no significant difference among the irradiated samples with regard to the sensory properties.

Analysis on Reflection Characteristics of the Key Competencies Proposed by the OECD Education 2030 in the 2015 Revised Home Economics Curriculum (OECD Education 2030에서 제안된 핵심역량의 2015 개정 가정과 교육과정 반영 특성 분석)

  • Yang, Ji Sun;Yoo, Taemyung
    • Journal of Korean Home Economics Education Association
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    • v.31 no.2
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    • pp.113-135
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    • 2019
  • The purpose of this study was to analyze the characteristics reflected in the 2015 revised home economics curriculum for the key competencies presented in the OECD education 2030 project. The results indicate that first, in general, about 46.5% of the competencies could be classified into the skill, attitude and value category; 17% into the learning concept framework category; 24.2% into the competency development cycle category; and 12.5% into the complex competency category. Overall, the competencies of the OECD learning framework are found to be reflected primarily in the achievement standards(59%), followed by characteristics(16.1%), teaching-learning and assessments orientation(9.4%), content system(8%), and goals(7.6%). Second, the key competencies were reflected in the middle school curriculum, more often in the descending order of action, problem-solving, communication, respect, creative thinking, conflict resolution, empathy, critical thinking, self-regulation, and student agency. In the high school curriculum, the competencies were reflected more often in the descending order of action, empathy, problem-solving, anticipation, global competence, self-regulation, student agency, literacy for sustainable development, reflection, and critical thinking. Third, the heat map shows that the competencies corresponding to the third and fourth levels are most frequently reflected in the curriculum. Therefore, it is advisable to develop effective plans to execute and support the reflection of key competencies in the curriculum. Through this study, home economics educators are expected to understand the inter-connectivity between the key competencies emphasized by the OECD learning framework and the competencies of home economics as a practical subject, and to scrutinize how to help individual students develop their overall competencies and be prepared for the future.

Treatment of Textile Wastewater by Membrane-Bioreactor Process (막-생물반응조 공정을 이용한 염색폐수의 처리)

  • 강민수;김성수;황규대;강종림
    • Proceedings of the Membrane Society of Korea Conference
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    • 1996.10a
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    • pp.60-61
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    • 1996
  • 염색폐수를 처리하기 위하여, 일반적으로 물리.화학적 공정과 호기성 생물학적 공정을 조합한 방법들을 사용하고 있다. 하지만 호기성 생물학적 공정은 난분해성 물질의 제거능력이 낮고, 염색폐수의 주된 오염원인 염료분자가 호기성 미생물에 대한 에너지원으로 적합하지 않아 분해되기 어려우며, 물리.화학적 공정을 이용한 처리방법으로도 높은 처리효율을 얻을 수가 없다. 이러한 문제점을 극복하기 위하여 염색폐수 처리에 혐기-호기공정을 이용하며, 혐기성 공정에서 생물학적으로 분해되기 어려운 고분자 물질들을 가수분해하여 생물학적으로 분해가능한 저분자물질로 전환시키고, 호기성 공정에서 저분자 물질을 효과적으로 처라할 수 있기때문에 기존의 염색폐수 처리공정에 비하여 훨씬 높은 처리효율을 얻을 수 있다. 특히, 혐기성 미생물은 호기성 미생물에 비하여 난분해성 물질에 대한 분해력이 높고, 생물독성 물질에 대한 내성이 강하기 때문에 수중생물에 유해한 염료를 함유한 염색폐수의 색도제거에 효과적인 것으로 기대된다. 또한, 막분리 공정은 유기물 및 미생물이 막표면에 축적, 증식함으로써 막세공에 막힘현상을 초래하여 역세척 등의 물리적인 방법이나 화학약품을 이용한 화학적 세척 방법으로도 투과플럭스의 회복이 불가능한 상태를 유발함으로 막의 수명을 단축시키는 원인이 된다. 따라서, 혐기-호기공정과 조합하면 색도성분 제거 및 막 오염의 원인이 되는 유기물 및 용존성 고형물을 제거하고, 막 오염의 억제를 통한 후 수염의 연장은 물론, 처리수의 수질향상에 활용될 수 있을 것으로 사료된다.1로 강구와 함께 공구강 vial에 장입 후, Spex mixer/mill을 이용하여 기계적 합금화 하였다. 기계적 합금화 공정으로 제조한 분말에 대한 X-선 회절분석과 시차 열분석으로 합금화 정도를 분석하였다. (Bi1-xSbx)2Te3 및 Bi2(Te1-ySey)3 합금분말을 10-5 torr의 진공중에서 300℃∼550℃의 온도로 30분간 가압소결하였다. 가압소결체의 파단면에서의 미세구조를 주사전자현미경으로 관찰하였으며, 상온에서 가압소결체의 열전특성을 측정하였다. (Bi1-xSbx)2Te3의 기계적 합금화에 요구되는 공정시간은 Sb2Te3 함량에 따라 증가하여 x=0.5 조성에서는 4 시간 45분, x=0.75 조성에서는 5 시간, x=1 조성에서는 6 시간 45분의 vibro 밀링이 요구되었다. n형 Bi2(Te1-ySey)3 합금분말의 제조에 요구되는 밀링시간 역시 Bi2Se3 함량 증가에 따라 증가하였으며 Bi2(Te0.95Se0.05)3 합금분말의 제조에는 2시간, Bi2(Te0.9Se0.1)3 및 Bi2(Te0.85Se0.15)3 합금분말의 형성에는 3시간의 bivro 밀링이 요구되었다. 기계적 합금화로 제조한 p형 (Bi0.2Sb0.8)2Te3 및 n형 Bi2(Te0.9Se0.1)3 가압 소결체는 각기 2.9x10-3/K 및 2.1x10-3/K 의 우수한 성능지수를 나타내었다.ering)가 필수적이다. 그러나 침전법에서 얻게 되는 분말은 매우 미세하여 colloid를 형성하게 되며, 이러한 colloid 상태의 미세한 침전입자가 filte

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