Solution combustion synthesis and surface properties of LaFeO3 powders

황연,Dae Sik Kang,Mi Hye Park 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.3

LaFeO3 powders were prepared by solution combustion synthesis (SCS) using citric acid as a fuel and metal nitrate as an oxidizer. By a simple procedure the mixed solution was held at 400 oC for 10 minutes, and single-phase perovskite-type LaFeO3oxide powders with good crystallinity were obtained for lean fuel compositions where the fuel–oxidizer ratio (φ) was less than 1.0. Two species of oxygen, namely lattice oxygen and adsorbed oxygen, appeared in the deconvolution of O 1s photoelectrons measured by X-ray photoelectron spectroscopy (XPS). It was found that the activation energy for the soot combustion of the synthesized LaFeO3 powders was closely related to the ratio of the two oxygen states. The best catalytic activity for soot combustion was obtained for LaFeO3 powders synthesized from the φ = 0.6-0.7 compositions where the ratio of adsorbed oxygen-to-lattice oxygen was a maximum.

Recent Advances in the Powder Processing by Mechanical Alloying

황연,이태근,박병규,Hwang, Yeon,Lee, Tae-Kun,Park, Byung-Kyu Korea Crystallographic Association 1999 韓國結晶學會誌 Vol.10 No.2

고분해능 전자에너지손실 및 자외선광전자 분광법을 이용한 NbC(111)면의 산소흡착 연구

황연,박순자,아이자와 타카시,하야미 와타루,오타니 시게키,이시자와 요시오,Hwang, Yeon,Park, Soon-Ja,Aizawa, Takashi,Hayami, Wataru,Otani, Shigeki,Ishizawa, Yoshio 한국재료학회 1992 한국재료학회지 Vol.2 No.4

고분해능 전자에너지손실 및 자외선광전자 분광법을 사용하여 단결정 NbC(111)면의 산소횹착을 연구하였다. NbC(111) 표면에는 산소가 원자 및 분자상태로 흡착되었다. 산소원자는 3-fold hollow site에 흡착되며 진동수는 548c$m^{-1}$이었다. 산소분자의 신축진동수는 968c$m^{-1}$로서 기체상태인 산소분자의 진동수보다 크게 낮았으며, 산소분자의 흡착으로 일함수가 증가하였다. 이는 NbC(111) 기판으로부터 산소분자의 2p${pi}_g$ 궤도로 전자가 이동하였음을 보여주는 증거이다. Oxygen adsorption on the single crystal NbC(111) surface was studied by high-resolution electron energy loss and ultraviolet photoelectron spectroscopy. On the NbC(111) surface, oxygen molecules as well as oxygen atoms were adsorbed. Oxygen atoms were located at the 3-fold hollow site of the NbC(111) surface with the frequency of 548c$m^{-1}$. It was found that oxygen molecules had vibrational frequency of 968c$m^{-1}$which was much lower than that of the free oxygen molecule. Also the work function of the NbC(111) surface has increased by adsorption of oxygen molecule. These suggest electron tranfer from the NbC(111) substrate to the 2p${pi}_g$ substrate of the oxygen molecule.

붕사 및 유리분말을 첨가한 석탄회로부터 저밀도 세라믹 담체의 제조

황연,이효숙,이우철,배광현,정용대,이원권,Hwang, Yeon,Lee, Hyo-Sook,Lee, Woo-Chul,Bae, Kwang-Hyun,Jeong, Yong-Dae,Lee, Won-Kwon 한국자원리싸이클링학회 2000 資源 리싸이클링 Vol.9 No.2

석탄회를 출발물질로 사용하고 봉사 및 유리를 첨가하여 저밀도 세라믹 담체를 제조하였다. 또한 성형체의 초기 기공율을 높이기 위하여 밀가루를 30wt% 첨가하였다. 봉사를 첨가함에 따라 겉보기 밀도 및 벌크 밀도가 낮아졌고, 석탄회에 대하여 15wt%의 붕사를 첨가한 결과 $1160^{\circ}C$에서 15분 소결하여 벌크 밀도 $0.79g/\textrm{cm}^3$, 겉보기 밀도 $1.10g/\textrm{cm}^3$인 담체를 얻을 수 있었다. 판유리를 분쇄한 후 212 이하로 체가름한 유리 분말을 첨가하면 붕사와 마찬가지로 밀도가 낮아졌으며, 12wt% 첨가하여 $1280^{\circ}C$에서 10분간 소결한 결과 벌크 밀도 $0.90g/\textrm{cm}^3$, 겉보기 밀도 $1.00g/\textrm{cm}^3$를 얻을 수 있었다. Low density ceramic supporter was prepared by using fly ash as a starting mterial with borax or glass powders. Also the wheat powders were used by 30 wt% to increase the initial porosity of the supporter. The density of the supporter decreased as the amount of borax increased. The bulk density of $0.79g/\textrm{cm}^3$ and the apparent density of $1.10g/\textrm{cm}^3$ were obtained when the fly ash with 15% of borax was sintered at $1160^{\circ}C$ for 15 minutes. The density also decreased as the plate glass powders past through $212\mu\textrm{m}$ size were mixed. When the fly ash with 12% of glass powder was sintered at $1280^{\circ}C$ for 10 minutes, the bulk and apparent density were $0.90g/\textrm{cm}^3$ and $1.00g/\textrm{cm}^3$, respectively.

문화재 복원용 무기계 수지의 합성 및 특성

황연,황선도,강대식,박미혜 한국문화재보존과학회 2009 보존과학회지 Vol.25 No.1

무기계 수지를 합성하여 압축강도 및 색도 변화에 대하여 조사하여 문화재 복원재료로서의 활용 가능성을 조사하였다. 무기계 수지로서 카올린을 750℃에서 6시간 동안 하소한 메타카올린을 사용하였는데, 하소 후 카올린은 비정질 상으로 변화하였다. 메타카올린에 NaOH 수용액 및 물유리를 중축합 개시제로 사용하여 무기계 수지를 합성하고, 압축강도 및 색도 등의 특성을 측정하였다. NaOH 수용액의 농도 및 물유리의 농도가 높을수록 압축강도가 증가하였다. 알루미나의 첨가는 적은 양의 치환에는 압축강도가 감소하였으나 첨가량이 더욱 증가하면 강도는 증가하였다. 8일에서 100일 간의 태양광에 의한 노출실험 결과 대부분의 조성에서 색도는 식별 불가능한 범위 내에서 변화하였다. 그러나 유기 안료의 첨가는 메타카올린의 색도 변화를 증가시켰다. 이와 같은 무기계 수지의 색도 변화는 에폭시 수지에 비하여 매우 우수한 것으로 나타났다.

비행시간형 직층돌 이온산란 분광법을 사용한 MgO(001) 면에 성장된 TiO막의 구조해석

황연,이태근,박병규,Hwang, Yeon,Lee, Tae-Kun,Park, Byung-Kyu 한국결정학회 2002 韓國結晶學會誌 Vol.13 No.2

Time-of-flight impact-collision ion scattering spectroscopy (TOF-ICISS) was applied to study the geometrical structure of epitaxially grown TiO layers on a MgO(001) surface. The hetero-epitaxial TiO layer was deposited by thermal evaporation of titanium onto the MgO(001) surface and subsequent exposure to oxygen at 400℃. The well-ordered TiO structure was confirmed with the 1×1 RHEED pattern. TOF-ICISS results revealed that the TiO layer was formed at the on-top sites of the MgO(001) substrate and that the lateral lattice constant of TiO layer was the same as that of the MgO substrate. The surface of the deposited epitaxial TiO layer was smooth without the three dimensional islands. MgO(001)면 위에 Ti 금속을 증착시킨 후 400℃에서 산소에 노출시킴으로써 헤테로 에피탁시 TiO 막을 성장시켰다. 성장된 TiO막의 원자구조를 비행시간형 직충돌 이온산란 분광법을 사용하여 해석하였다. MgO(001)면에 성장된 에피탁시 TiO막은 다음과 같은 구조를 갖고 있음이 밝혀졌다. Ti및 O 원자가 MgO 원자의 위에 위치하여 면내방향의 격자상수는 MgO의 격자상수와 일치하고, TiO막의 표면은 3차원적 섬 형상이 없는 평활한 구조를 가지고 있다.

《三國志》中“于”和“於”的用法研究

黃娟 경성대학교 한국한자연구소 2022 한자연구 Vol.- No.32

“Yu (于)” and “Yu (於)” both exist in The History of the Three Kingdoms, while the frequency of usages are different, with same and different usages. This paper takes The History of the Three Kingdoms During Shaoxi Period of Song Dynasty (The Twenty-Four Histories in Collection of Various Editions) as the research material, and investigates the usages of the words “Yu (于)” and “Yu (於)” in it, also referring to the other three editions of The History of the Three Kingdoms and checking each other to clarify the words and usages. In The History of the Three Kingdoms, “Yu (於)” appears 4544 times, “Yu (于)” appears 861 times, and the usage ratio is 5.28:1. “Yu (於)” is more widely and frequently used than “Yu (于)”. These two words are used most abundantly as prepositions. The prepositions “Yu (于)” and “Yu (於)” can both guide the complements of time and place, as well as elicit action objects and express passiveness. Additionally, in the three pairs of common phrases, the usages and meanings of the corresponding words are same. The difference is that the preposition “Yu (於)” has more plentiful usages and fixed usages of “Yushi (於是)” and “Zaiyu (在於)”, moreover, “Yu (於)” is often used after war verbs, and “Yu (于)” is rarely used. Furthermore, “Yu (於)” can be used as an interjection, and “Yu (于)” in proper nouns cannot be written as “Yu (於)”. It can be seen that, different from the pre-Qin period, the grammatical function of “Yu (於)” in The History of the Three Kingdoms is much stronger than that of “Yu (于)”, which reflects the trend that the weakening of the usages of “Yu (于)” in the Wei, Jin, Southern and Northern Dynasties, while the function of “Yu (於)” is gradually becoming stronger. Besides, there are many usages preserved through “Yu (於)” from ancient Chinese to modern Chinese.

폴리카보실란 에멀젼의 동결건조를 이용한 다공체 SiC 제조

황연,Hwang, Yeon 한국재료학회 2016 한국재료학회지 Vol.26 No.6

Porous SiC beads were prepared by freeze-drying a polycarbosilane (PCS) emulsion. The water-in-oil (w/o) emulsion, which was composed of water, PCS dissolved p-xylene, and sodium xylenesulfonate (SXS) as an emulsifier, was frozen by dropping it onto a liquid $N_2$ bath; this process resulted in 1~2 mm sized beads. Beads were cured at $200^{\circ}C$ for 1 h in air and heat-treated at $800^{\circ}C$ and $1400^{\circ}C$ for 1 h in an Ar gas flow. Two types of pores, lamella-shaped and spherical pores, were observed. Lamellar-shaped pores were found to develop during the freezing of the xylene solvent. Water droplets in the w/o emulsion were changed into spherical pores under freeze-drying. At $1400^{\circ}C$ of heat-treatment, porous SiC was synthesized with a low level of impurities.

고분해능 전자에너지손실 및 자외선광전자분광법을 이용한 ZrC(111)면의 산소흡착 연구

황연,박순자,아이자와 타카시,하야미 와타루,오타니 시게키,이시자와 요시오,Hwang, Yeon,Park, Soon-Ja,Aizawa, Takashi,Hayami, Wataru,Otani, Shigeki,Ishizawa, Yoshio 한국재료학회 1991 한국재료학회지 Vol.1 No.4

고분해능 전자에너지손실과 자외선광전자분광법을 사용하여 단결정 ZrC(111)면의 산소흡착을 연구하였다. 산소는 낮은 산소노출량에서 $(\sqrt{3}{\times}\sqrt{3})R30^{\circ}$ 구조로 흡착된다. 노출량이 승가하면 $1{\times}1$ 구조로 바뀌는데 이때 흡착하는 산소원자는 $(\sqrt{3}{\times}\sqrt{3})R30^{\circ}$ 구조에서보다 흡착높이가 낮으며 3-fold hollow site의 중심에 놓이지 않고 bridge site에 가까와진다. 서로 다른 산소흡착 거동은 개끗한 ZrC(111) 표면에서 두개의 표면전자상태에 기인한다. Oxygen chemisorption on single crystal ZrC(111) surface was studied by high-resolution electron energy loss and ultraviolet photoelectron spectroscopy. At a low amount of oxygen exposure, adsorbed oxygen atoms construct $(\sqrt{3}{\times}\sqrt{3})R30^{\circ}$ structure. On the other hand, oxygen adsorption changes into $1{\times}1$ structure as the amount of oxygen exposure increases. The adsorbed oxygen atoms show smaller vertical distance from the Zr topmost layer in the $1{\times}1$ structure than in the $(\sqrt{3}{\times}\sqrt{3})R30^{\circ}$ structure and approach to the bridge site rather than 3-fold hollow site. The two different oxygen adsorption behavior comes from the two different surface stales of the clean ZrC(111) surface.

『三國志』裴松之注語言文字學價值探究

黃娟 대한중국학회 2022 중국학 Vol.81 No.-

裴松之(372年-451年)爲『三國志』做的注極大地修正、完善和豐富了陳壽『三國志』原文的內容。裴注的語言文字學價值顯著,體現在以下三個方面。首先,語音學方面,『三國志』裴注中有注音99條,共爲96個字頭進行了注音,注音方法主要爲直音(含“音如”)、反切,注音體例爲隨文注音,體現了後漢至東晉時期的語音特點。其次,詞彙學注釋共98條,產生了新詞新義,裴氏對首次出現及賦予了新的內涵的詞語進行了相關補充和說明,多數爲後世沿用。最後,文字學注釋共39條,裴注對生僻的,難以理解的文字加以說明,補充釋義,且關注到了漢字字形對字義的影響,注重從文字學的角度切入,分析詞語和文意。裴松之做注,行文簡潔,脈絡清晰,細緻嚴謹,且常用案語表達自己的觀點和看法,個人特色鮮明。『三國志』裴注具有深刻的語言文字學研究價值,值得仔細挖掘,這對豐富漢語史研究內容方面有着重要作用。