Stoichiometric Layered Potassium Transition Metal Oxide for Rechargeable Potassium Batteries

Kim, Haegyeom,Seo, Dong-Hwa,Urban, Alexander,Lee, Jinhyuk,Kwon, Deok-Hwang,Bo, Shou-Hang,Shi, Tan,Papp, Joseph K.,McCloskey, Bryan D.,Ceder, Gerbrand American Chemical Society 2018 Chemistry of materials Vol.30 No.18

<P>K-ion batteries are promising alternative energy storage systems for large-scale applications because of the globally abundant K reserves. K-ion batteries benefit from the lower standard redox potential of K/K<SUP>+</SUP> than that of Na/Na<SUP>+</SUP> and even Li/Li<SUP>+</SUP>, which can translate into a higher working voltage. Stable KC<SUB>8</SUB> can also be formed via K intercalation into a graphite anode, which contrasts with the thermodynamically unfavorable Na intercalation into graphite, making graphite a readily available anode for K-ion battery technology. However, to construct practical rocking-chair K-ion batteries, an appropriate cathode material that can accommodate reversible K release and storage is still needed. We show that stoichiometric KCrO<SUB>2</SUB> with a layered O3-type structure can function as a cathode for K-ion batteries and demonstrate a practical rocking-chair K-ion battery. In situ X-ray diffraction and electrochemical titration demonstrate that K<SUB><I>x</I></SUB>CrO<SUB>2</SUB> is stable for a wide K content, allowing for topotactic K extraction and reinsertion. We further explain why stoichiometric KCrO<SUB>2</SUB> is unique in forming the layered structure unlike other stoichiometric K-transition metal oxide compounds, which form nonlayered structures; this fundamental understanding provides insight for the future design of other layered cathodes for K-ion batteries.</P> [FIG OMISSION]</BR>

유리系 內의 Ferrite의 Mossbauer Spectra

安振盛,金俊植,李敬行,趙壽烈,董徹,洪致裕 동국대학교 자연과학연구소 1984 자연과학연구 논문집 Vol.4 No.-

本 硏究는 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %)유리계에 대한 Mossbauer parameter의 溫度依存性을 조사하였다. Mossbauer spectrum은 한쌍의 Quadrupole doublet의 중첩으로 fitting하였으며 이중 하나는 tetrahedral site,다른 하나는 octahedral site이다. 상대적인 共鳴吸收面積比로부터 octahedral site와 tetrahedral site에 대한 Debye temperature를 계산하여 본 결과 각각 418K, 449K 임을 알았다. 또한 θ?값들을 이용해 least square method로 isomer shiftdral site의 壓力依存系數 α와 2.97×10?mm/sec K, I.S(0)일때의 를 평가해본 결과 octahedral site의 α는 2.97×10?mm/sec K,I.S(0)는 tetrahedral site이고 α의 3.2305×10?mm/sec K, I.S(0)는 0.276mm/sec임을 알았다. 그리고 quadrupole splitting은 측정온도가 증가함에 따라 서서히 감소함을 알았다. The temperature dependence of the Mossbauer parameter for 5NiO-5CdO-10Fe₂O₃-30Na₂CO₃-10SiO₂(mole %) quenched glass system was investigated. The spectra were fitted as superposition of a pair of quadrupole double ; One is for the tetrahedral site and the other is for the octahedral site. From the relative absorption area ratios of the spectra, the Debye erature of two sites were calculated to be 418K and 449K for the octahedral site and the ?edrai site, respectively. From these Debye temperatures, We can see that the isomer shifts and the coefficients αof the pressure dependence of the isomer shift are 0.456mm/sec, 2.97×10?mm/sec K for octahedral site and 0.276mm/sec K, 3.2305×10?mm/sec K for ?edral site. Also, we can see that the quadrupole splittings of two sites are gradually decresed the increase of the measuring temperature.

CdTe의 Trap 準位

李京錫,李海翼,李載珍,董徹,金榮咸,姜泰遠 동국대학교 자연과학연구소 1984 자연과학연구 논문집 Vol.4 No.-

本 硏究에서는 Iodine을 dope시켜 Bridgman法으로 成長시킨 n-type CdTe를 admittance分光法을 이용하여 溫度變化에 따른 capacitance와 donductance를 測定하였다. capacitance와 conductance는 溫度增加에 따라 一般的으로 增加하나, 250K 근처에서 capacitance는 급격한 增加를 보이고 conductance는 極大値를 보인다. 이 conductance의 極大値 測定 周波數를 增加시키면 높은 溫度쪽으로 shift하는 것을 볼 수 있었고, 이것으로부터 구한 trap에너지準位, 電子放出率, trap濃度는 각각 E-0.42eV 2.14×10sec, 6.57×10cm이었다. Measurememts of the capacitance and the conductance as a function of tmeperature of I-doped n-type CdTe grown by the Bridgman method has been performed by means of the admittance spectroscopy. It is found that the capacitance and the conductance normally show trend of increase with temperature and the increase of the capacitance shows rapid change near 250K, whereas the conductance shows a peak there. This peak of the conductance shows shift toward the higher temperature with the measured frequency. The trap energy level, the electron emission rate and the trap concentration obtained from the set of these results are E-0.42eV 2.14×10sec, 6.57×10cm respectively.

선택적 남성 호르몬 분비 부신피질 종양 1예

김동수,박정수,이상주,이병석,박기현,박찬규,허갑범,이현철,이관우,김미림,이명래 대한내분비학회 1989 Endocrinology and metabolism Vol.4 No.2

Deletions of 9p21 and TP53 in Bladder Cancer

Park, W.-S Korean Academy of Medical Science 1996 Journal of Korean medical science Vol.11 No.3

Thermodynamic and kinetic analysis of gas hydrates for desalination of saturated salinity water

Seo, Seong Deok,Hong, Sang Yeon,Sum, Amadeu K.,Lee, Kun-Hong,Lee, Ju Dong,Lee, Bo Ram Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.370 No.-

<P><B>Abstract</B></P> <P>The shortage of fresh water is among the most serious issues in the world. A representative technology to overcome the problem is desalination, but most conventional methods (RO membrane or thermal distillation) have been focused on the treatment of relatively low salinity water, such as seawater or brackish water. To strengthen water security, in this study, we introduce a possibly economic technology for desalination of high salinity water (over-saturated concentration, in this study, a 30 wt% NaCl system) via gas hydrate formation by coupling LNG waste cold energy. First, the thermodynamic effects of NaCl on CH<SUB>4</SUB> (methane), SF<SUB>6</SUB> (sulfur hexafluoride), and HFC-134a hydrates were investigated. Based on the phase equilibrium of each hydrate, experimental pressures for kinetic experiments were selected under vapor pressure boundaries as follows: 4.5 MPa for CH<SUB>4</SUB>, 0.75 MPa for SF<SUB>6</SUB>, and 0.16 MPa for HFC-134a at 258.15 K (assuming the use of LNG waste cold energy). The results of the formation kinetics on the basis of gas moles consumed for hydrates showed the order CH<SUB>4</SUB> > HFC-134a > SF<SUB>6</SUB>; however, after considering the hydration numbers and structures for each hydrate, surprisingly, the conversion rate of water to gas hydrates showed the order HFC-134a > CH<SUB>4</SUB> > SF<SUB>6</SUB>, even though the experimental pressure condition for HFC-134a was very mild (0.16 MPa) compared to CH<SUB>4</SUB> (4.5 MPa). For this interesting phenomenon, we suggest a possible mechanism through visual observations during hydrate formation. We believe these thermodynamic, kinetic, and morphological results show potential as an alternative desalination technology, especially for saturated salinity water, with lower energy consumption.</P> <P><B>Highlight</B></P> <P> <UL> <LI> Thermodynamics and kinetics of gas hydrates were studied in saturated NaCl system. </LI> <LI> Using LNG waste cold energy was assumed for hydrate formation kinetics experiments. </LI> <LI> HFC-134a hydrates in saturated NaCl system formed at 0.16 MPa and 258.15 K. </LI> <LI> The kinetics of hydrates conversion showed the order HFC-134a > CH<SUB>4</SUB> > SF<SUB>6</SUB>. </LI> <LI> HBD process with HFC-134a is possibly economic in over-saturated salinity system. </LI> </UL> </P>

몰리브덴인산화물 촉매에 의한 메틸피라진의 가암모니아 산화반응

신채호,장태선,조득희,이동구,이영길 ( Chae Ho Shin,Tae Sun Chang,Deug Hee Cho,Dong Koo Lee,Young K . Lee ) 한국공업화학회 1997 공업화학 Vol.8 No.5

몰리브덴산암모늄염과 인산의 반응으로 P/Mo=0.6의 비율을 가진 몰리브덴인산화물을 제조하고 이를 촉매로 사용하여 메틸피라진의 가암모니아 산화반응에 대한 메틸피라진, 산소, 암모니아의 각각의 분압과 반응온도 등의 반응변수의 영향을 살펴보았다. 표준실험조건하의 반응에서 300시간까지의 촉매활성은 안정상태를 유지하였다. 안정화 상태에서의 메틸피라진의 가암모니아 산화반응 속도식은 -r=kP_MPP_NH3 °P_02^γ(γ=2.2;1.3≤P_02(kPa)≤4)으로 메틸피라진에 대해서는 1차, 암모니아에 대해서는 0차, 산소에 대해서는 분압 4kPa이하에서 2.2차로 나타났다. 623 K이하의 반응온도 하에서의 겉보기 활성화에너지는 29.6㎉/㏖이었다. 메틸피라진의 주생성물은 시아노피라진으로서 선택도는 전환율에 관계없이 항상 90%이상을 유지하였다. Molybdenum phosphate(P/Mo = 0.6) has been synthesized with ammonium molybdate and phosphoric acid under aqueous solution. The kinetics of the ammoxidation of methylpyrazine over molybdenum phosphate catalyst was investigated with the variation of reaction temperature and partial pressure of methylpyrazine, oxygen and ammonia, respectively at atmospheric pressure. The catalytic activity was constant for 300hrs operation under our experimental conditions. Under the steady-state condition, the rate equation of methylpyrazine was shown as -r=kP_MPP_NH3 °P_02^γ(γ=2.2;1.3≤P_02(kPa)≤4). The apparent activation energy was 29.6㎉/㏖ below 623K. The main product obtained in the ammoxidation of methylpyrazine is cyanopyrazine whose selectivity was kept always over 90% regardless of conversion.

연속주조 턴디쉬 댐 설계를 위한 수 모델 연구

이성우,구윤서,김동식,신영길 대한금속재료학회(대한금속학회) 1986 대한금속·재료학회지 Vol.24 No.7

Understanding of the flow pattern of a molten steel through tundish is an essential precondition for estimating and avoiding negative effects on steel cleanliness. To study removal of inclusion in the tundish, experiments were carried out using a one third scale water model of the tundish with a dam and a weir. The flow patterns were determined by a flow visualization technique and by a theoretical analysis of the tundish system. The velocity field was predicted by solving the turbulent Navier-Stokes equations using the K-ε model for turbulent viscosity. There was a good agreement between the experimental results and the predictions. A plant test revealed significant improvements on slab quality such as reduction of surface defects of the cold-rolled sheets.

開放性動脈管 : 31例手術報告 Report of 31 Cases

徐景弼,申漢壽,沈台燮,洪彰義,朱東雲,李寧均 최신의학사 1967 最新醫學 Vol.10 No.5

Thirty one cases, 18 females and 13 males, were operated on for patent ductus arteriosus. There were three adult cases. Patent ductus arteriosus alone was present in 27, while in 4 there were significant associated cardiovascular anomalies. No deaths occurred in 24 patients isolated patent ductus a' eriosus without and with mild to moderate pulmonary hypertension. Severe pulmonary hypertension was present in 4 patients with an isolated patent ductus. An operative death occurred in the 2 patients in this group. One of them died as result of the tearing of the ductus during surgery. The remaining case died 3 days postoperatively., Patent ductus arteriosus with congenital cardiovascular anomalies was present in 4 patients. Single operative death occurred 7 days postoperatively because of bronchopneumonia of right lung and atelectasis of the left lung. There was an increased mortality when patent ductus arteriosus was associated with severe pulmonary hypertension. All survival patients showed very satisfactory postoperative results.

작용기를 포함하는 새로운 거대고리 폴리에테르의 합성

장승현,김동준,이갑득 대구대학교 부설 과학교육연구소 1993 과학교육 Vol.6 No.-