수학적 모델을 이용한 순열과 조합 단원의 실생활 문제해결에 관한 연구

강유빈,김용구 全南大學校 師範大學 科學敎育硏究所 2017 科學敎育硏究誌 Vol.41 No.1

This study aims for a mathematical modeling for korean students, who lack not only the problem solving skill for real-life problems because they are accustomed to formal curricula but also the interest because mathematics is considered to be too abstract and not related to everyday real life. Especially, the students rely heavily on the application of formulas when they do routine problems in the ‘Permutation and Combination’ chapter. Thus students have a difficulty in problems that require modification of the formulas. By solving real-life problems in the ‘Permutation and Combination’ chapter with mathematical modeling, students are expected to gain a better understanding of the mathematical concepts and the ability to grasp the essence of the problems. For this purpose, the following study objectives were established: 1. Real life problems on ‘Permutation and Combination’ are classified into categories according to the problem types. 2. Real life problems on ‘Permutation and Combination’ are presented to the students through mathematical models after problems are transformed mutually among the different problem types. Among the ‘Permutation and Combination’ real life problems, distribution problems were the most common (36.1%), followed by selection (33.3%), selection + distribution (19.4%) and division (11.1%) problems. This process can help the students recognize the usefulness of mathematics and appreciate the appeal and utility of the subject. Moreover, converting practice into another types will help students to develop grasping ability of the essence of the problems related to ‘Permutation and Combination’ without the dependence on mathematical formulas.

표면전하를 이용한 SiO₂/PMMA 분말의 분산 제어 및 평가

강유빈,손수정,이근재,Kang, Yubin,Son, Soojung,Lee, Kun-Jae 한국분말야금학회 2015 한국분말재료학회지 (KPMI) Vol.22 No.6

Poly-methylmetacrylate (PMMA) is mainly applied in the plastic manufacturing industry, but PMMA is weak and gradually got discolor. The strength of PMMA can be improved through organic-inorganic hybrid nano composites with inorganic nano particles such as, $SiO_2$ or ZrO. However, inorganic nano particles are mostly agglomerated spontaneously. In this study, the zeta potential is controlled using different types of organic solvent with different concentrations, dispersibillity of $SiO_2$ nano particles on the PMMA particle are analyzed. When 3 M acetic acid is used, absolute value of the zeta potential is higher, $SiO_2$ nano particle is well attached, and dispersed on the PMMA particle surface. Results indicate that the absolute value of the zeta potential affects the stability of $SiO_2$ dispersion.

폐 LCD 유리 재활용을 위한 용매 별 유기물 제거 효율에 대한 연구

강유빈,최진주,박재량,이찬기 한국자원리싸이클링학회 2020 資源 리싸이클링 Vol.29 No.6

In this study, removal of OCA and organic impurities for recycling LCD touch panel glass was conducted by mechanical and chemical dissolution methode. Cut mill and oscillation mill were used for mechanical crushing of touch panel, and water, ethanol, dichloromethane were used to remove OCA and organic impurities. As a result of TGA, when applied only dicloromethane in the process, the efficiency of organic removal was to be best. In addition, removal effect of organic impurities increased as the cleaning temperature increased. As a result of zeta potential analysis to confirm the dispersion degree of touch panel glass in the solvent, the absolute value of the zeta potenial of water with the lowest cleaning effect was lower than other solvents, and it was confirmed that efficiency of organic removal is affected not only by the chemical dissolution properties but also the physical dispersion properties in the solvent. 본 연구에서는 LCD 터치 패널 유리의 재활용을 위해 기계적 방법과 화학적 용해법을 혼용하여 OCA 및 유기 불순물을 제거하는 실험을 진행하였다. 터치 패널의 기계적 파분쇄를 위해 cut mill과 oscillation mill을 이용하였으며, OCA와 유기 불순물의 제거를 위해 물, 에탄올, 디클로로메탄을 이용하여 터치 패널 파쇄물을 세정하였다. 세정 이후 TGA를 통해 유기 불순물의 제거 효율을 평가한 결과 디클로로메탄 단일 용매를 사용한 경우 세정 효과가 가장 뛰어났으며, 세정 온도가 증가함에 따라 유기 불순물의 제거 효과가 증가함을 확인하였다. 제타 전위 측정을 통해 터치 패널 유리 파쇄물의 용매 내 분산도를 평가한 결과, 세정 효과가 가장 낮은 물의 제타 전위 절대값이 타용매에 비해 낮았으며, 유기물의 제거 효과는 화학적인 용해 특성뿐 아니라 용매 내 물리적인 분산 특성에 의해서도 영향을 받을 수 있음을 확인하였다.

유무기 하이브리드 티타늄 착화합물을 이용한 티타니아의 제조 방법 및 성장 거동에 대한 연구

강유빈,최진주,권남훈,김대근,이근재,Kang, Yubin,Choi, Jin-Ju,Kwon, Nam Hun,Kim, Dae-Guen,Lee, Kun-Jae 한국분말야금학회 2019 한국분말재료학회지 (KPMI) Vol.26 No.6

Titanium dioxide (TiO₂) is a typical inorganic material that has an excellent photocatalytic property and a high refractive index. It is used in water/air purifiers, solar cells, white pigments, refractory materials, semiconductors, etc.; its demand is continuously increasing. In this study, anatase and rutile phase titanium dioxide is prepared using hydroxyl and carboxyl; the titanium complex and its mechanism are investigated. As a result of analyzing the phase transition characteristics by a heat treatment temperature using a titanium complex having a hydroxyl group and a carboxyl group, it is confirmed that the material properties were different from each other and that the anatase and rutile phase contents can be controlled. The titanium complexes prepared in this study show different characteristics from the titania-formation temperatures of the known anatase and rutile phases. It is inferred that this is due to the change of electrostatic adsorption behavior due to the complexing function of the oxygen sharing point, which crystals of the TiO₆ structure share.

BaTiO3 첨가에 따른 Bi1/2Na1/2TiO3-SrTiO3 무연 압전 세라믹스의 전기적 특성 및 상전이 거동 연구

강유빈,박재영,무클리사 아이샤 데비타,즈엉 짱 안,안창원,김병우,한형수,이재신 한국전기전자재료학회 2022 전기전자재료학회논문지 Vol.35 No.5

We investigated the microstructure, crystal structure, dielectric, and elecromechanical strain properties of lead-free BaTiO3 (BT)-modified (Bi1/2Na1/2)TiO3-SrTiO3 (BNT-ST) piezoelectric ceramics. Samples were prepared by a conventional ceramic processing route. Temperature dependent dielectric properties confirmed that a phase transition from a nonergodic relaxor to an ergodic relaxor was induced when the BT concentration reached 1.5 mol%, interestingly, where the average grain size reached a maximum value of 4.5 μm. At the same time, enhanced electromechanical strain (Smax/Emax = 600 pm/V) was obtained. It is suggested that the induced ferroelectric-relaxor phase transition by the BT modification is responsible for the enhancement of electromechanical strain in 1.5 mol% BT-modified BNT-ST ceramics.

알루미늄 블랙드로스로부터 유가자원 회수를 위한 재활용 공정 연구

강유빈,임병용,김대근,이찬기,안병두,김용환,이만승,Kang, Yubin,Im, Byoungyong,Kim, Dae-Guen,Lee, Chan Gi,Ahn, Byung-Doo,Kim, Yong Hwan,Lee, Man Seung 한국자원리싸이클링학회 2018 資源 리싸이클링 Vol.27 No.5

알루미늄 드로스는 알루미늄 용해 공정에서 용탕 표면에 발생하는 산화물 덩어리로서, Salt 유무에 따라 화이트드로스와 블랙드로스로 구분된다. 화이트드로스의 경우 금속 함량이 높아 용해 공정으로 재활용 되지만, 블랙드로스는 금속 함량이 낮고 성분 분리가 어려워 대부분 매립 처리되며, 물과 반응하면 가스와 발열 반응이 일어나 토양오염의 원인으로 작용한다. 하지만 블랙드로스에는 NaCl과 KCl과 같은 Salt 성분과, $Al_2O_3$, MgO와 같은 무기소재가 포함되어 있어 이러한 유가자원을 회수하고 소재화하는 기술 연구가 필요하다. 본 연구에서는 알루미늄 블랙드로스를 재활용하기 위한 공정을 제시하였다. 파쇄-용해(Dissolution)-고액분리-감압증발을 거치는 공정을 통하여 블랙드로스에 존재하는 무기물과 용해성 물질을 분리하였다. 물과 블랙드로스 함량을 제어하여 조건에 따라 분리물의 회수율을 최적화하였으며, 블랙드로스:물 비율이 1:9 일 때 91 wt.%의 Salt flux 회수율을 보임을 확인하였다. 추가적으로, 회수된 무기물을 이용한 제올라이트의 합성을 통하여 블랙드로스의 소재화 가능성을 확인하였다.

폐리튬이차전지에서 회수한 탄산리튬으로부터 2-step 침전공정을 이용한 고순도 수산화리튬 분말 제조 연구

주소영,강유빈,심현우,변석현,김용환,이찬기,김대근,Joo, Soyeong,Kang, Yubin,Shim, Hyun-Woo,Byun, Suk-Hyun,Kim, Yong Hwan,Lee, Chan-Gi,Kim, Dae-Guen 한국자원리싸이클링학회 2019 資源 리싸이클링 Vol.28 No.5

금속 폐기물로부터의 유가금속 회수는 관련 원료의 수입 혹은 안정적 원료 수급을 위해서 매우 중요하다. 특히 폐리튬이차전지(LIBs)로부터 회수가 가능한 금속(Li, Co, Ni, Mn 등)의 재사용뿐만 아니라 폐리튬이차전지의 재활용 연구가 필수적이다. 폐리튬이차전지에서 회수된 수산화리튬($LiOH{\cdot}xH_2O$)은 촉매, 이산화탄소 흡수제 및 양극재의 전구체로 재사용이 가능하다. 본 연구에서는 폐리튬이차전지로부터 회수된 탄산리튬 전구체를 사용하였으며, 침전공정을 이용한 선택적인 리튬 분리를 통해 고순도 수산화리튬 분말의 제조 및 최적화 연구를 진행하였다. 수산화리튬 제조 조건으로는 교반을 기반으로 반응온도 $90^{\circ}C$, 반응시간 3 시간, 탄산리튬과 수산화칼슘의 비율 1:1의 조건에서 수행하였으며, 순도 향상을 위해 2-step 수산화리튬 제조 공정을 추가적으로 진행하여 최종적으로 고순도의 수산화리튬 제일수화물($LiOH{\cdot}xH_2O$)을 제조하였다.

알루미늄 재활용 소재를 이용한 내화재용 Mayenite 합성 연구

임병용,강유빈,주소영,이찬기 한국자원리싸이클링학회 2020 資源 리싸이클링 Vol.29 No.6

Black dross is a dark gray dross generated during the aluminum recycling process that uses flux, and contains NaCl, KCl, Al2O3, MgO, etc. Black dross is separated into soluble substances (NaCl, KCl) and insoluble substances (Al2O4, MgO) through the dissolution process. Soluble materials can be reused as salt flux, and Al2O3 and MgO can be upcycled to various ceramic materials through the synthesis process. In this study, Mayenite was synthesized using Al2O3 and MgO recovered from black dross, and the synthesis was performed according to the mixing ratio and reaction temperature. It was confirmed that when Mayenite was synthesized using black dross (spinel) and CaCO3, precursors were changed to Mg0.4Al2.4O4 and CaO at 700 ℃, and to Ca12Al14O33 (Mayenite) after 800 ℃. In the mixing conditions experiment, it was confirmed that the Mayenite XRD peak increased with increase of the CaCO3 content, and the Mg0.4Al2.4O4 XRD peak decreased. As a result of the BET analysis of the synthesized powder, the surface area decreased as the fine particles were grown and agglomerated in the process of generating mayenite. 요약블랙 드로스는 알루미늄을 재활용하는 과정 중에 플럭스 사용에 의해 발생되는 짙은 회색의 드로스로서, NaCl, KCl, Al2O3, MgO 등이 포함되어 있다. 블랙 드로스는 용해(dissolution) 공정을 통하여 용해성 물질(NaCl, KCl)과 불용해성 물질(Al2O4, MgO)로 분리가 가능하다. 이중 용해성 물질의 경우 Salt flux로 재활용이 가능하며, Al2O3, MgO의 경우 합성 공정을 통하여 다양한 세라믹 소재로 업사이클링이 가능하다. 본 연구에서는 블랙 드로스로부터 회수한 Al2O3, MgO를 이용하여 Mayenite를 합성 하였으며, 배합 비율 및 반응 온도조건에 따른 합성을 실시하였다. 블랙 드로스(spinel)와 CaCO3를 이용하여 Mayenite를 합성할 시 700 ℃에서 Mg0.4Al2.4O4, CaO로 변하며, 800 ℃ 이후부터 Ca12Al14O33(Mayenite)으로 변하는 것을 확인하였다. 배합 조건에는 CaCO3 함량이 증가함에 따라 Mayenite XRD 피크가 증가하며, Mg0.4Al2.4O4 XRD 피크는 감소하는 것을 확인하였다. 합성된 분말의 BET 분석 결과 Mayenite가 생성되는 과정에서 미세한 입자가 성장되고 응집됨에 따라 비표면적은 감소하는 거동을 보였다.

한국 소재 대학교에 재학 중인 재외국민대학생의 문화지능과 학습참여도가 우울에 미치는 영향

강보미,강유빈,고미영,김찬송,남의정,박소은,박정연,백도윤,이혜린,한보혜,신주현,손지희 이화여자대학교 간호과학대학 2019 이화간호학회지 Vol.- No.53

Purpose: This study aims to identify the impact that cultural intelligence and learning engagement of Korean overseas students in Korea have in depression, also, to propose direction for further research, and to suggest a nursing intervention program that aims to the reduction of depression in overseas students. Methods:. The selected participants of the present study were Korean Overseas University Students enrolled in a special admission for overseas students. Data were obtained through the use of SPSS Window 25 and analyzed using descriptive statistics, t-test, ANOVA, Scheffe test, Pearsons correlation coefficient, and multiple linear regression analysis. Results: Depression in Korean overseas university students is influenced by the education system(ß=-.193, p=.046) and continent of residency(ß=0.197, p=.03). It is necessary to take into account the differences of education systems as well as the cultural differences from where they come from for the purpose of reducing depression rates in overseas Koreans. Conclusion: The results of this study show that depression in Korean overseas students is related to the differences in continents of residency and the education systems. Consequently, the development and implementation of a nursing intervention program considering both factors, the continent and education system, has become a necessity that relates to the reduction of depression in Korean overseas students.

LTCC 전극공정부산물 침출 용액으로부터 은 회수 및 은 나노입자 제조

유주연,강유빈,박진주,류호진,윤진호,이근재,Yoo, Juyeon,Kang, Yubin,Park, Jinju,Ryu, Hojin,Yoon, Jin-Ho,Lee, Kun-Jae 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.4

There has been much interest in recycling electronic wastes in order to mitigate environmental problems and to recover the large amount of constituent metals. Silver recovery from electronic waste is extensively studied because of environmental and economic benefits and the use of silver in fabricating nanodevices. Hydrometallurgical processing is often used for silver recovery because it has the advantages of low cost and ease of control. Research on synthesis recovered silver into nanoparticles is needed for application to transistors and solar cells. In this study, silver is selectively recovered from the by-product of electrodes. Silver precursors are prepared using the dissolution characteristics of the leaching solution. In the liquid reduction process, silver nanoparticles are synthesized under various surfactant conditions and then analyzed. The purity of the recovered silver is 99.24%, and the average particle size of the silver nanoparticles is 68 nm.