Sc₂O₃와 CeO₂가 첨가된 ZrO₂의 전기전도도

이동석,허장원,김재동,김주선,이해원,김긍호,김대준,이종호,Lee, Dong-Suek,Heo, Jang-Weon,Kim, Jae-Dong,Kim, Joo-Sun,Lee, Hae-Weon,Kim, Gyeung-Ho,Kim, Dae-Jun,Lee, Jong-Ho 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.4

중저온 영역에서 작동 가능한 고체산화물연료전지(SOFC)의 전해질 재료를 탐색하기 위해 $Sc_2O_3$와 $CeO_2$를 동시에 첨가하여 안정화시킨 $CeO_2$의 상안전성과 전기적 물성을 분석하였다. 분석결과 $Sc_2O_3$와 $CeO_2$를 동시에 첨가하여 안정화시킨 $ZrO_2$는 $1350^{Circ}C∼1550^{Circ}C$까지의 열처리과정중 다른 상전이 없이 상온에서 안정한 입방정상을 유지하였으며 넓은 온도영역($300∼^{Circ}C$)에서 기존의 YSZ보다 훨씬 높은 전기전도도값을 나타냈다. 또한 $Sc_2O_3$와 $CeO_2$가 동시에 첨가된 $ZrO_2$는 기존의 Sc-$ZrO_2$계 전해질 물질보다 훨씬 향상된 장기안정성을 나타내 중저온형 고체산화물 연료전지의 전해질재료로 적합함을 알 수 있었다. The electrical conductivity and phase stability of $ZrO_2$ doped with $Sc_2O_3$ and $CeO_2$ were investigated in order to search for better solid electrolyte material for solid oxide fuel cell. Present study showed that $ZrO_2$ doped with $Sc_2O_3$ and $CeO_2$ exhibited no phase transition during the heat treatment up to $1350^{Circ}C∼1550^{Circ}C$ and was stable as a cubic phase in whole temperature ranges. The $ZrO_2$ doped with $Sc_2O_3$ and $CeO_2$ showed much higher electrical conductivity than YSZ in the temperature range of $300∼^{Circ}C$ and better long term stability than other sc-$ZrO_2$ based electrolyte that showed the possibility as a strong candidate electrolyte material for intermediate-or low-temperature SOFC.

Haemophilus Influenzae TPx-GRX의 생화학적 특성연구

이동석,김일한,Lee, Dong-Suk,Kim, Il-Han 배재대학교 자연과학연구소 2004 自然科學論文集 Vol.14 No.1

Thiol peroxidase인 E.coli AhpC의 아미노산 서열을 database를 이용해 분석하여, TPx와 상동성이 있는 새로운 형태의 Thiol peroxidase를 찾아내었다. 그 중 병원성을 갖는 박테리아인 Haemophilus Influenzae에서 존재하는 TPx와 유사하고, GRX와 함께 fusion 되어있는 새로운 형태의 단백질의 유전자를 클로닝하여 E.coli에서 과발현시켜 분리정제 하였다. 정제된 TPx-GRX는 환원제로 thiol 성분을 갖는 MCO system(Fe, DTT, Oxygen)에 의하여 Glutamine Synthetase(GS)의 불활성화를 방어하는 티올 특이적 향산화활성을 갖고, peroxides를 제거하는 peroxidase 활성을 갖는 것을 밝혔다. 이 결과들로부터 TPx-GRX는 새로운 형태의 Thiol perosidase임을 알 수 있었다. 더 나아가서 이 결과들은 TPx-GRX가 병원성 박테리아에서 oxidative stress를 막는 생리적으로 중요한 역할을 할 것이라는 것을 시사한다. We found new type of thiol peroxidase, fused with GRX.(TPx-GRX) The TPx-GRX exists in pathogenic bacteria including -. This protein was homogeneously purified from the E.coli recombinant overexpressing TPx-GRX. In the presence of a thiol-containing electron donor such as DTT, the purified TPx-GRX has potent the antioxidant to prevent the inactivation of GS by the MCO system, which is comprised of DTT, $Fe^{3+}$, and $O^2$. The antioxidant activity is much higher that other thiol peroxidase. The investigate the peroxidase activity of TPx-GRX, we directly measured the peroxidase activity of TPx-GRX toward peroxides in terms of the removal of peroxides in the presence of GSH. This result demonstrates that the peroxidase activity of TPx-GRX. These taken together results suggest that TPx-GRX is a new member of thiol peroxidase. These observations also suggest that in the pathogenic bacteria, TPx-GRX plays an important antioxidative role as a multiple array defence mechanism against oxidative stress.

스피넬상 $Li{Mn_2}{O_4}$를 이용한 $CO_2$ 분해의 최적조건

이동석,임병오,양천회,이풍헌,Lee, Dong-Suek,Rim, Byung-O,Yang, Chun-Hoe,Lee, Poong-Hun 한국세라믹학회 2001 한국세라믹학회지 Vol.38 No.10

이산화탄소 분해를 위한 촉매 $Li{Mn_2}{O_4}$는 졸-겔법에 의해서 망간아세테이트와 수산화리튬을 출발물질로 사용하여 $150^{\circ}C$의 공기분위기에서 12시간 동안의 건조과정과 $480^{\circ}C$에서 12시간 동안의 열처리과정을 통해서 합성하였다. 합성한 촉매를 수소환원시키기 위해서 다른 온도에서 수소($H_2$)로 3시간동안 환원하였고, 이 수소에 의해 환원된 촉매를 이용해 $300^{\circ}C$, $325^{\circ}C$, $350^{\circ}C$, $375^{\circ}C$, $400^{\circ}C$에서 이산화탄소($CO_2$) 분해율을 조사하였다. 실험결과 수소환원과 이산화탄소 분해의 온도최적조건은 $350^{\circ}C$임을 알 수 있었다. 합성촉매를 포함해 수소에 의한 환원과 이산화탄소분해 후 촉매에 대하여 XRD분석, SEM관찰, TGA 분석을 하였다. The spinel $Li{Mn_2}{O_4}$ catalysts for $CO_2$ decomposition were synthesized by a sol-gel method using manganese acetate and lithium hydroxide as starting materials through drying at $150^{\circ}C$ for 12 hrs under oxygen atmosphere followed by heat treatment at $480^{\circ}C$ for 12 hrs. The synthesized $Li{Mn_2}{O_4}$ were reduced by hydrogen for 3 hrs at various temperatures and the decomposition rate of carbon dioxide was investigated at 300, 325, 350, 375 and $400^{\circ}C$ using the $Li{Mn_2}{O_4}$ reduced by hydrogen gases. As a result of experiment, the optimum temperature of hydrogen reduction and $CO_2$ decomposition was shown $350^{\circ}C$. The physicochemical properties of the spinel $Li{Mn_2}{O_4}$ the reduced $Li{Mn_2}{O_4}$ and the $Li{Mn_2}{O_4}$ after $CO_2$ decomposition were examined with XRD, SEM and TGA.

축소모형실험을 이용한 연약대층 근접 터널의 거동

이동석,전재현,박종덕,이석원,Lee, Dong-Seok,Joen, Jae-Hyun,Park, Jong-Deok,Lee, Seok-Won 한국터널지하공간학회 2012 한국터널지하공간학회논문집 Vol.14 No.3

최근 터널 건설은 종종 연약대층을 인접하여 계획하게 된다. 이러한 경우 터널 굴착은 안정화되어 있던 지반을 이완시키고 따라서 터널의 안정성에 문제를 일으킬 수 있다. 안정성에 문제를 일으킬 수 있는 주요 영향인자들을 보면 연약대층이 지표면과 이루는 각도, 연약대층과 터널의 이격거리 등을 들 수 있다. 본 연구에서는 연약대층을 인접하여 건설되는 터널의 굴착과정에서 발생하는 변위량과 균열발생 양상을 조사함으로써, 연약대층이 지표면과 이루는 각도 및 연약대층과 터널의 이격거리가 터널의 역학적 거동에 미치는 영향을 조사하였다. 연약대층이 지표면과 이루는 각도 및 연약대층과 터널의 이격거리를 변화시켜 가면서 균질한 재료를 가지고 실내 축소 모형실험을 수행하고 이를 분석하였다. 실험결과, 연약대층이 지표면과 이루는 각도가 수평에서 수직으로 변화함에 따라 터널 주변의 변위 발생량이 증가하였다. 연약대층과 터널의 이격거리가 증가함에 따라 터널 주변의 변위 발생량이 감소하였고, 특정 이격거리 이상에서 안정화되었다. 이러한 발견들은 기존의 연구결과들을 정량적으로 검증하고 확장하는 것이라 판단된다. 최종적으로 연약대층이 지표면과 이루는 각도 변화에 따른 연약대층과 터널의 적정 이격거리를 정의하였다. 이러한 기초적인 연구는 연약대층을 인접하여 신설되는 터널 설계에 보다 합리적인 제안을 할 수 있을 것으로 판단된다. Recently, the construction of tunnel frequently involves neighboring weak ground conditions. In this case, the stabilized ground could be relaxed by the excavation of tunnel. This will create issues in terms of stability of tunnel. Major factors determining the stability of tunnel can be the direction (angle) of weak zone, the distance between tunnel and boundary of weak zone and so on. In this study, by quantifying the displacement and crack propagation during the excavation of tunnel constructed neighboring weak zone, the influence of the direction of weak zone and the distance between tunnel and boundary of weak zone on the mechanical behavior of tunnel is investigated. A series of experimental scaled model tests by changing the direction of weak zone and the distance between tunnel and boundary of weak zone, are performed and analyzed under the condition of homogeneous material. The results show that as the angle between ground surface and boundary of weak zone moves from horizontal to perpendicular plane, displacement near tunnel increases. An increased distance between tunnel and boundary of weak zone induces displacements near tunnel to decrease and stabilizes beyond a certain level of distance. These findings verify and extend the earlier studies quantitatively. Finally, an appropriate distance between tunnel and boundary of weak zone according to the angle of weak zone is justified. This fundamental insight provides the basis for a more rational design of tunnel neighboring weak ground conditions.

산화구리 나노선 센서의 황화수소 감지특성

이동석,김도진,김효진,Lee, Dongsuk,Kim, Dojin,Kim, Hyojin 한국재료학회 2015 한국재료학회지 Vol.25 No.5

$H_2S$ is a flammable toxic gas that can be produced in plants, mines, and industries and is especially fatal to human body. In this study, CuO nanowire structure with high porosity was fabricated by deposition of copper on highly porous singlewall carbon nanotube (SWCNT) template followed by oxidation. The SWCNT template was formed on alumina substrates by the arc-discharge method. The oxidation temperatures for Cu nanowires were varied from 400 to $800^{\circ}C$. The morphology and sensing properties of the CuO nanowire sensor were characterized by FESEM, Raman spectroscopy, XPS, XRD, and currentvoltage examination. The $H_2S$ gas sensing properties were carried out at different operating temperatures using dry air as the carrier gas. The CuO nanowire structure oxidized at $800^{\circ}C$ showed the highest response at the lowest operating temperature of $150^{\circ}C$. The optimum operating temperature was shifted to higher temperature to $300^{\circ}C$ as the oxidation temperature was lowered. The results were discussed based on the mechanisms of the reaction with ionosorbed oxygen and the CuS formation reaction on the surface.

수도(水稻)에 처리(處理)된 유기수은제(有機水銀劑)의 잔류성(殘留性)에 관(關)한 연구(硏究) -제3보(第3報) : 가토(家兎)에 있어서 PMA투여(投與)에 의(依)한 주요장기(主要臟器)의 병리조직학적(病理組織學的) 변화(變化) 및 체내(體內)에서의 동태(動態)에 관(關)한 연구

이동석,Lee, Dong-Suk 한국응용생명화학회 1967 Applied Biological Chemistry (Appl Biol Chem) Vol.8 No.1

일당(日當) PMA $30{\gamma}$제I군(第I群), $3{\gamma}$제II군(第II群),그리고 $0.3{\gamma}$제III군(第III群)씩 90 일간(日間) 투여(投與)한 가토(家兎)에 있어서, 주요(主要) 장기(臟器)에 일어난 병리조직학적변화(病理組織學的變化)와 배설물(排泄物) 및 간장중(肝臟中)의 수은함유량(水銀含有量) 분석결과(分析結果)는 다음과 같다. 1. 신장(腎臟) : 제I군(第I群)에 있어서는 근위곡뇨세관상피세포(近位曲尿細管上皮細胞)에 심(甚)한 공포형성(空胞形成)과 혼탁종창(混濁腫脹)이 있었고, 근위직뇨세관상피세포(近位直尿細管上皮細胞)에 심(甚)한 혼탁종창(混濁腫脹) 및 응고괴사(凝固壞死)가 있었다. 또한 다수(多數)의 초자양원주(硝子樣圓柱)를 집합관내(集合管內)에서 볼수 있다. 제II군(第II群)에있어서나 위곡뇨세관상피세포(爲曲尿細管上皮細胞)에 중정도(中程度)의 공포형성(空胞形成) 및 혼탁종창((混濁腫脹)이있었고, 근위직뇨세관상피세포(近位直尿細管上皮細胞)에 중정도(中程度)의 혼탁혼탁종창(混濁混濁腫脹) 및 응고괴사(凝固壞死)가 있었다. 집합관내(集合管內)에는 소수(少數)의 초자양원주(硝子樣圓柱)가 있었다. 제II군(第II群)에 있어서는 근위곡세뇨관(近位曲細尿管) 및 근위직세뇨관상피세포(近位直尿細管上皮細胞)에 경도(輕度)의 혼탁종창(混濁腫脹)만을 보였다. 2. 간장(肝臟): 제I군(第I群)에 있어서, 간소엽(肝小葉)은 중심(中心)으로 혼탁종창(混濁腫脹), 지방변화(脂肪變化) 및 응고괴사(凝固壞死)를 보였고, 간세포색(肝細胞索)의 해리(解離)가 있었다. 제II군(第II群)에 있어서는 간소엽(肝小葉)은 간세포색(簡細胞索)의 정상구조(正常構造)를 유지(維持)하면서 활발(活潑)한 간세포증생(肝細胞增生)을 보였다. 제III군(第III群)의 간장조직(肝臟組織)은 병리학적변화(病理學的變化)를 보이지 않았다. 3. 비장(脾臟): 제I군(第I群)에있어서 혈철소(血鐵素)의 침착(沈着)이 현저(顯著)하였고 제II군(第II群)에서는 소량(小量)의 혈철소침착(血鐵素沈着)을 보였다. 제III군(第III群)에서는 별(別)다른 병리학적소견(病理學的所見)이 없었다. 4. 부신(副腎), 결장(結腸) 및 심장(心臟)은 각군(各群)에 있어서 아무런 병리적변화(病理的變化)를 보이지 안항T다. 5. 배설물중(排泄物中)의 수은함유량(水銀含有量)은 제I군(第I群)에 있어서는 총급여수은량(總給與水銀量) 0.45g에 대(對)해서 약(約) 76.5%가 배설(排泄)되었고 제II군(第II群)에 있어서는 85.44%, 제(第)III에 있어서는 79.89%가 각각(各各) 배설(排泄)되었다. 6. 간장중(肝臟中)의 수은함유량(水銀含有量)을 보면 제I군(第I群)에서 0.0348 g, 제II군(第II群)에서는 0.00378 g, 그리고 제III군(第III群)에서 0.00066 g이었다. 7. 일반적(一般的)으로 수은(水銀) 투여량(投與量)이 많으면 많을수록간장(肝臟)에서의 수은(水銀) 축적농도(蓄積濃度)가 높으나 총투여량(總投與量)에 대(對)한 축적량(蓄積量)은 이와 반대(反對)의 경향(傾向)을 보였다. Daily doses of phenylmercuric acetate arranged in $30{\gamma}\;(group\;I)$, 3{\gamma}\;(group\;II)$ and $0.3{\gamma}\;(group\;III)$ were administered respectively to rabbits for 90 days. The chief histopathological changes in the organs and the analytical data on mercury residues in the excretion and liver were as follows. 1. Kidney: In group I, severe degrees of vacuolization and cloudy swelling were occurred in the epithelial cells of proximal convoluted tubules and severe cloudy swelling and coagulative necrosis were observed in the proximal straight tubules. There were many hyaline casts in the collecting tubules. In group II, moderate degrees of vacuolization and cloudy swelling were observed in the epithelial cells of proximal convoluted tubules and moderate cloudy swelling and coagulative necrosis were encountered in the proximal straight tubules. A little numbers of hyaline casts were located in the lumen of collecting tubules. In group III, slight degree of cloudy swelling were observed in the epithelial cells of proximal convoluted and straight tubules. 2. Liver: In group I, cloudy swelling, fatty changes and coagulative necrosis were observed in the central zone of hepatic lobules. Dissociation of hepatic cell cords was encountered. Hyperplsia of hepatic cells were remarkable in group II. No Pathological changes were observed in group III. 3. Spleen: Deposition of hemosiderin pigment was prominant in group I and small amount of the pigment was observed in group II. There were no pathological changes in group III. 4. Adrenal, colon and heart: No pathological changes were detected in all 3 groups. 5. In an average about 76.5% of mercury was excreted from group I, 85.4% from group II and 79.8% from group III. 6. Mercury content in the liver was 0.0348 g in group I, 0.00378 g and 0.00066 g in group II and group III respectively. 7. In general, as to increased mercury doses the concentration of mercury accumulation in the liver became higher, how·ever, the accumulation quantity against a total amount of mercury doses showed an adverse trend. In other word, the quantity of mercury accumulation was not increased proportionately by higher dose of mercury.

디젤엔진 피스톤용 SCM440 의 레이저 표면경화부의 잔류응력

이동석,유웅재,김재도 ( D . S . Lee,W . J . Yoo,J . D . Kim ) 한국열처리공학회 1995 熱處理工學會誌 Vol.8 No.3

SCM440, which is widely used as the diesel engine piston of vessel, has been hardened by a CO₂laser with the wavelength of 10.6㎛. Laser hardening experiment has been carried out for the condition of a laser power 1㎾, the travel speed between 0.4 and 1.5m/min, and a rectangular-Gaussian beam. Residual stress has been measured by using middle point technique of half value width of X-ray diffraction method. It was found that the compressive residual stress with the range between 400 and 600㎒ has distributed in the laser hardening zones and the tensile residual stress between 100 and 200㎒ has distributed in the boundary of hardening zones.

효과적인 표준 발음 교육

이동석,Lee Dong-Seok 대한음성학회 2004 말소리 Vol.51 No.-

The purpose of this dissertation is to make the general korean speakers to learn the standard pronunciations. But it is in existence that the obstructions of the command of the standard pronunciations. They are the mistake in the education course on the korean pronunciations, the teacher's capability and the mass communications's duplicity. To overcome this obstructions, we must concentrate our efforts on the propagation of the standard pronunciations. To propagate of the standard pronunciations we can take a several method. These are the presentation of the pronunciation mistakes, audio-visual teaching, the presentation of the pronunciation principles and the use of the korean dictionary. The standard pronunciations are different from the pronunciations of the general korean speakers in many respects. So we can't make an accurate estimate of the pronunciation's changes. No one knows what will happen in the future about the korean pronunciations. But we must teach the standard pronunciations to the general korean speakers. The standard pronunciations are offically valid in the present time.

대학 구조조정 - 대학구조개혁과 대학 특성화 병행에 대한 소고

이동석,Lee, Dong-Seok 한국대학교육협의회 2014 大學敎育 Vol.184 No.-

한글 맞춤법 조항에 대한 몇 가지 쟁점-전문가의 의식 조사를 바탕으로-

이동석 ( Dongseok Lee ),이경숙 ( Gyeongsuk Lee ),이지현 ( Jihyeon Lee ) 한국문법교육학회 2015 문법 교육 Vol.23 No.-

The purpose of this study it to investigate some issues arising from certain spelling conventions in Korean, using a survey of experts`` consciousness of these conventions as a foundation. The group of experts used in the study was composed of Korean linguists, journalists, publishers, teachers, and Korean language policy experts. The Delphi method was used in two different rounds. Fifty-three experts participated in the first round (Delphi I) and fifty-two participated in the second round (Delphi II). Delphi I consisted of a series of structured open-ended questions, while Delphi II consisted of twenty multiple choice questions. The results showed the experts`` opinions regarding the revision of the spelling conventions for [s](``ㅅ``) epenthesis, word spacing, and the adverbial derivational suffixes ``-i’, and ‘-hi’. Experts agree with the abolition or reduction of [s](``ㅅ``) epenthesis, and further agree that the adverbial derivational suffixes ``-i’ and ‘-hi’ should follow spelling rather than pronunciation rules. However, although the experts were in agreement regarding the revision of word spacing, they were not able to agree on a specific method. This study can be used as a basis in revising Korean orthography.