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$Eu_{1-x}Sr_xCoO_{3-y}$계의 비화학량론과 자기적 특성
류광현,민지영,여철현,Ryu, Kwang Hyun,Min, Ji Young,Yo, Chul Hyun 대한화학회 1995 대한화학회지 Vol.39 No.7
$Eu_{1-x}Sr_xCoO_{3-y}$계에 대한 각 조성의 시료를 1150$^{\circ}C$ 대기압하에서 일정량의 반응혼합물을 가열하여 합성하였고 X-선 회절분석을 통하여 고용체가 합성되었음을 확인하였다. X-선 회절분석 결과 x=0.00과 0.25 조성의 화합물은 뒤틀린 orthoferrite형의 사방정계이고 x=0.50과 0.75는 단순 입방정계이고 x=1.00은 brownmillerite형의 사방정계이다. $Co^{4+}$ 이온의 양(${\tau}$값)은 x=0.50에서 최대가 되고 산소공위는 x값이 증가함에 따라 증가한다. 합성된 화합물에 대한$Co^{4+}$ 이온의 몰비와 산소 비화학량을 결정함으로서 합성된 각 조성의 화합물에 대한 비화학량론적 화학식을 결정하였다. 페롭스카이트 구조의 팔면체자리에 존재하는 $Co^{3+}$ 이온은 온도가 증가함에 따라 낮은 스핀상태에서 높은 스핀상태로의 전이가 일어난다. 이에 따라 자기측정 결과 각 시료는 온도가 상승함에 따라 유효자기모멘트가 증가한다. $EuCoO_{3.00}$의 경우 팔면체자리에 존재하는 $Co^{3+}$ 이온은 산소이온을 매개로 하여 이웃한 $Co^{3+}$ 이온과 반강자성 간접상호작용을 한다. ${\tau}$값이 증가하면 $Co^{3+}-O^2-Co^{4+}$의 강자성 상호작용에 의해 {\theta}_p$의 절대값이 감소하고, 결국 x=0.50에서는 양의 {\theta}_p$값을 갖는다. A series of samples in the $Eu_{1-x}Sr_xCoO_{3-y}$ system has been prepared by heating the proper amount of reactant mixture to 1150$^{\circ}C$ under an ambient atmosphere, and the solid solutions are identified by X-ray powder diffraction analysis. The crystal system of samples for the compositions of x=0.00 and 0.25 are found to be orthorhombic whose local symmetry is similiar to the distorted octahedra with orthoferrite type one, whereas those of x=0.50 and 0.75 to be the cubic system, and that of x=1.00 to the orthorhombic similiar to be the brownmillerite type. The amount of $Co^{4+}$ ion (${\tau}$ value) is maximized at the composition of x=0.50, and the oxygen vacancies increase with the x value. The nonstoichiometric chemical formula of each compound could be determined from the mole ratio of $Co^{4+}$ ion and oxygen vacancies. The $Co^{3+}$ ion located in octahedral site has spin transition from low spin to high spin states with increasing temperature. Therefore, the effective magnetic moment of each samples obtained from the magnetic measurement is increased with the increasing temperature. The $EuCoO_{3.00}$ has strong antiferromagnetic interaction between the neighboring $Co^{3+}$ ions through the intermediate oxygen ions. With the increasing ${\tau}$ value, the absolute {\theta}_p$ value is decreased by the ferromagnetic interaction of $Co^{3+}-O^2-Co^{4+}$ and thus the {\theta}_p$ has positive value at x=0.50.
류광현,조지현,김현중 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
As environmental pollution caused by the indiscriminate use and disposal of non-degradable plastics increases, the need for biodegradable materials has been increasing in the adhesive field. Hot-melt adhesives are used in the packaging field because it has the advantage of quick bonding and easy to handle, but its main components are EVA (ethylene vinyl acetate) and PO (polyolefin) which are non-degradable materials. In this study, a biodegradable hot melt adhesives were prepared using PBS (polybutylene succinate) and naturally derived rosins. The adhesion of hot-melt adhesives applied by various rosins (maleic modified, dehydrogenated, esterifircated) was evaluated for LDPE film.
Adhesion Properties of Poly(butylene succinate)/Rosin Types in Hot-Melt Adhesives
류광현,조지현,이태형,신재호,김현중 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.2
As the environmental pollution caused by the indiscriminate use and disposal of non-degradable plastics has become an internationally-surged problem, the urging needs of biodegradable materialsalso arise in the adhesive field. In particular, Hot melt adhesives have been widely used in the adhesive field due to their eco-friendly, fast curing speed, and prompt adhesion characteristic advantages. However, the main materials for hot melt adhesives used in packaging areaare comprised of poly(ethylene vinyl acetate) (EVA) and poly olefin (PO), which are not biodegradable; hence they ultimately accrete the environmental burden. In this study, PBS hot-melt adhesives was prepared by melt compounding of a PBS with gum rosin, dehydrogenated rosin, and dehyrogenated rosin ester. The adhesive strength of was confirmed through the peel test. The causes of the adhesion were analyzed in terms of rheological, surface properties, and crystallization behavior.
현훈을 동반한 편타성 손상 환자에 대한 판상근 아시혈 침치료 중심의 한방복합치료 치험 3례
류광현,주아라,박미소,추원정,최요섭,문영주,최효정 대한한방내과학회 2020 大韓韓方內科學會誌 Vol.41 No.6
Objective: The purpose of this study was to report the effect of acupuncture on the splenius muscle and the effect of combined Korean medicine treatment on acute dizziness in patients due to whiplash injury. Methods: Three patients with acute dizziness were treated with acupuncture of the splenius muscle and combined Korean medicine. A numeric rating scale (NRS) and the Korean dizziness handicap inventory (K-DHI) were checked every day from admission to discharge to confirm symptom improvements. Results: In the acute stage of dizziness caused by whiplash injury, acupuncture of the splenius muscle and combined Korean medicine improved the NRS and K-DHI scores. Conclusions: For patients with acute dizziness caused by whiplash injury, a combination of acupuncture on the splenius muscle and Korean medicine treatment may be a solution.