Highly selective iron-based Fischer-Tropsch catalysts activated by CO₂-containing syngas

Chun, D.H.,Park, J.C.,Hong, S.Y.,Lim, J.T.,Kim, C.S.,Lee, H.T.,Yang, J.I.,Hong, S.,Jung, H. Academic Press 2014 Journal of catalysis Vol.317 No.-

Fischer-Tropsch synthesis (FTS) was carried out over precipitated iron-based catalysts activated by syngas (H<SUB>2</SUB>+CO) with different amounts of CO<SUB>2</SUB> (0%, 20%, 33%, and 50%). The activation using CO<SUB>2</SUB>-containing syngas significantly suppressed the production of undesired products, CH<SUB>4</SUB> and C<SUB>2</SUB>-C<SUB>4</SUB> hydrocarbons, but facilitated the production of valuable products, C<SUB>5+</SUB> hydrocarbons. In particular, in the case of C<SUB>19+</SUB> hydrocarbons, the target products of low-temperature FTS (≤280<SUP>o</SUP>C), both selectivity and productivity showed a great increase with an increased inlet CO<SUB>2</SUB> content during activation. We attribute the advantageous performance of the catalysts activated by CO<SUB>2</SUB>-containing syngas to the improvement in the effective performance of active iron carbides, possibly induced by an increased ratio of ε'-carbide (Fe<SUB>2.2</SUB>C) to χ-carbide (Fe<SUB>2.5</SUB>C) and a decreased fraction of inactive bulk carbons.

Microstructural evolution and tensile properties of oxide dispersion strengthened Alloy 617 at elevated temperatures

Chun, Y.B.,Mao, X.,Han, C.H.,Jang, J. Elsevier Sequoia 2017 Materials science & engineering Structural materia Vol.706 No.-

<P><B>Abstract</B></P> <P>This study investigated evolution of the microstructure of oxide dispersion strengthened Alloy 617 with annealing temperature. A mixture of prealloyed Alloy 617 and Y<SUB>2</SUB>O<SUB>3</SUB> powders was mechanically alloyed and consolidated by hot-extrusion at 1100°C. Hot extrusion developed a submicron-sized grain structure with M<SUB>23</SUB>C<SUB>6</SUB> carbides and finely dispersed Al<SUB>2</SUB>O<SUB>3</SUB> and Y<SUB>2</SUB>Ti<SUB>2</SUB>O<SUB>7</SUB> oxides. The fine-grained structure was stable during subsequent annealing at temperatures up to 1250°C. Further increase of annealing temperature to 1300°C resulted in a significantly coarsened grain structure, which was coincident with the abrupt coarsening of oxides. M<SUB>23</SUB>C<SUB>6</SUB> carbides in the as-extruded conditions were transformed to M<SUB>7</SUB>C<SUB>3</SUB> carbides with complex shapes when annealed at 1200°C, and their shapes changed to very coarse hexagonal prisms at 1250°C, which was followed by the formation of eutectic M<SUB>2</SUB>C carbides at grain boundaries at 1300°C. Tensile tests of the as-extruded ODS Alloy 617 showed that the yield strength decreased steeply at a transition temperature of around 600°C, which can be attributed to diffusional creep along the grain boundaries.</P>

Diamond 박막 성장에 미치는 Si 표면 영향의 AES에 의한 연구

이철로(C. R. Lee),신용현(Y. H. Shin),임재영(J. Y. Leem),정광화(K. H. Chung),천병선(B. S. Chun) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.2

Si 기판 표면상태 변화와 관련된 핵생성 자유에너지 증가에 따른 다이아몬드 박막성장 거동을 관찰하였다. 표면 연마조건 변화에 따른 3가지 기판(A-Si, B-Si, C-Si) 위에 동일한 성장조건으로 다이아몬드를 성장하였으며, 이때 형상인자와 관련된 자유에너지 관계는 ΔG_(A-Si)<ΔG_(B-Si)<ΔG_(C-Si)이다. AES, SEM, XRD, RHEED에 의해 각각의 박막 A, B, C를 조사한 결과, 핵생성 자유에너지가 가장 적은 A 박막은 (100) (110) 면이 지배적인 고품위 다이아몬드 박막이다. 자유에너지가 A에 비해 다소 적은 B 박막은 (111) 면이 지배적인 8면체 다이아몬드 박막이고, 자유에너지가 가장 적은 C 박막은 흑연이 많이 함유된 구상의 다이아몬드이다. The effect of nucleation free energy related to Si surface states on diamond film growth behavior has been studied. At first, the three kinds of diamond thin films (A, B, C) were deposited on various Si substrates (A-Si, B-Si, C-Si) whose surfaces were polished with 1 ㎛ diamond paste, 6 ㎛ Al₂O₃ powder and 12 ㎛ Al₂O₃ powder respectively. And then, relative nucleation free energy calculated is ΔG_(A-Si)<ΔG_(B-Si)<ΔG_(c-Si) Although there are some difference in grain size, shape and nucleation site, the thin films on A-Si and B-Si were diamond including a small amount of DLC which was confirmed by AES, SEM, XRD and RHEED. Namely, the diamonds of films (B) were not nucleated in scratches but in dents and larger in grain size compare with the film (C) of which diamond were nucleated not only scratches but also dents. And, the sphere diamond which is not general shape was grown on C-Si. After all, the sphere was turned out to be the diamond including much graphite as a result of the AES in situ depth profiling. Consequently, the diamond shape and quality grown on Si were changed from the crystal which the (100) and (110) planes were predominent to the crystal in which (111) plane was predominent, and next to sphere shape diamond including much graphite according as the nucleation free energy increases.

EACVD로 Si 위에 성장한 다이아몬드 박막의 계면 접합강도

이철로(C. R. Lee),박재홍(J. H. Park),임재영(J. Y. Leem),김관식(K. S. Kim),천병선(B. S. Chun) 한국진공학회(ASCT) 1993 Applied Science and Convergence Technology Vol.2 No.3

필라멘트와 Si 기판 사이의 기전력을 20, 80, 140, 200V로 증가시키면서 EACVD에 의하여 성장된 다이아몬드 박막에 대하여 다이아몬드/Si 계면분석 및 계면강도를 측정하였다. 주사형전자현미경(SEM), 고분해능투과형전자현미경(HRTEM), 오제이전자분석기(AES)에 의해 계면상태를 분석한 결과, 기전력 증가에 따라 활성탄화수소 이온(C_mH_n^-) 에너지가 증가되어져 C_mH_n^-이 Si내로 침투(Impringement)가 증가되고 침투된 높은 에너지의 C_mH_n^-이 Si과 화학결합하여 생성되는 SiC층 깊이 및 농도 분포도 증가된다. 풀 시험(Pull test)에 의한 계면강도 측정 결과, SiC층 깊이 및 농도분포가 증가할수록 계면강도가 증가하였다. 관찰된 파면과 파면의 X-선 메핑 결과 및 HRTEM과 AES에 의한 분석 결과, 기전력 증가에 따라 공극율이 적고 치밀한 다이아몬드 박막이 성장된다. 그리고 생성되는 SiC층 농도 및 깊이 분포가 증가함에 따라 다이아몬드/Si 계면이 강화되고, 상대적으로 파괴는 다이아몬드/Si 계면이 아닌 SiC층이나 Si 내부에서 발생된다. 결국, 기전력을 증가하여 활성탄화수소 이온의 에너지를 증가함으로써 계면강도가 우수하며 공극율이 매우 적고 치밀한 다이아몬드 박막을 성장할 수 있다. The diamond thin films on Si which 20 V (Film A), 80 V (Film B), 140 V (Film C) and 200 V (Film D) had been applied respectively between filament and Si substrates during growth were analysed with SEM, HRTEM and AES. Judging from those results, the diffusion of carbon increased due to the increment of the energy of active hydrocarbon ion (C_mH_n^-) and also the SiC layers were formed as the result of chemical bonding of C_mH_n^- with Si. The amount and depth of SiC layer increased as the potentials increased. The interface adhesion of these films were also measured with Pull test which is the most accurate and general method in evaluation of thin film adhesion. The film (D) which SiC was formed most deeply and widely exhibited the most adhesion in diamond/Si interface. Meanwhiles, the film (A) which had most shallow SiC layer and low SiC concentration exhibited very weak adhesion compare to film (D). Judging from the observation and X-Ray Mapping of fracture surface, the film (D) was fractured in Si below interface and the film (A) was fractured in diamond thin film/Si interface. Also, there are many voids in film (A) and a little in film (D). Conclusively, it is possible to grow the high strength and condensed diamond thin film without pores because the energy of active hydrocarbon ion was increased by elevation of potentials during growth.

칡소의 염색체 양상과 핵형 분석

손시환,고영두,김두환,박구부,이정규,이철영,신철교,정희식,곽석준,박명구,천민성,백철승 한국축산학회 2000 한국축산학회지 Vol.42 No.1

The Korean Native Stripped Cattle known as Chickso have distinctive black hair belts all over the body to varying extents on a Hanwoo(Korean Cattle)-like yellowish brown background. These Battle are remaining only in a limited area of this country and are known to yield a flavorful meat somewhat distinct from that of Hanwoo, but their genetic lineage has not been identified. We have carried out karyotyping of these cattle firm the lymphocyte culture. Blood samples were collected from 20 of male and female cattle that had been bred at Poongjeon Farm located in Kosong, Kyongnam, and were subjected to chromosomal morphology and G- and C-banding analysis. Chickso, like Hanwoo, had 58 autosomes and X and Y sex chromosomes which were morphologically very similar to those of the latter. All the 58 autosomes revealed almost a zero value of centromeric index, suggesting that they are acrocentric; sex chromosomes X and Y were submetacentric and metacentric, respectively. Following G-banding, the light bands appeared near the centromeric site in all the autosomes whereas the specific dark bands were consistently visible in each homologous chromosome. Overall, the G-banding pattern was nearly identical between the Chickso and Hanwoo. C-bands representing the heterochromatin were present at or near the centromere in all the autosomes, whereas in sex chromosomes, they were found distributed on variable sites. The proportion of constitutive heterochromatin ranged 20∼30%. These patterns were not significantly different between the two subspecies. All of these cytogenetic results suggest that the distinctive traits of Chickso did not arise from a cytogenetic variation from Hanwoo, i. e. the former is simply a subpopulation of the latter. As such, we propose that selection and propagation of the Chickso based on economic traits may be advantageous to the domestic beef industry.

콘크리트 Pump Car의 구조 개선을 위한 유한요소해석

전종균,엄호성,김도형,김영해 선문대학교 ·중소기업기술지원연구소 2002 선문공대 연구/기술 논문집 Vol.7 No.1

유한요소 해석법은 컴퓨터의 발달로 인해 근래에 들어 많은 진보를 거듭하고 있다. 또한, 이를 이용한 제품 개발과 많은 연구가 진행되고 있는 실정에 있다. 본 논문은 콘크리트 Pump Car의 구조 개선을 위해 FEM해석을 실시하였다. 각 BOOM과 Swing post를 단순화, 모델링하여 각 Boom에 작용하는 응력 및 변형률을 해석하였고, Swing post의 Bolt 부분의 위치 변화에 따른 응력 분포와 변형률을 계산하였으며, 해석 값은 등가응력 Von-Mises Stress 과 변형률 USUM 로 측정하였다. Recently FEA has been improved by the growth of computer technology. Also research for solid mechanics is more activated and new product has been developed by the support of FEA. In this study, the structure of pump car for concrete has been analyzed using FEA for the optimal performance. Each structure of boom and swing post are simplified for modelling and the stress and strain on the elements of them has been analyzed. The stress distribution and strain of swing post for various position of bolt has been determined and analytic value for the equvalent stress Von-Mises Stress and strain USUM has been calculated.

火傷 患兒의 간호

전춘영,심치정 대한간호협회 1976 대한간호 Vol.15 No.5

洋蘭 生長點 培養에 關한 硏究 : (Ⅳ) Auxin 과 kinetin의 單用및 混用處理가 Cymbidium의 生育에 미치는 影響 (Ⅳ) Effect of auxin alone or combined with kinetin on growth of Cymbidium species

全在琪,徐榮敎,鄭載東 慶北大學校 1979 論文集 Vol.28 No.-

The promoting effects in the previous papers were obtained on the several Cymbidium varieties by treatment of auxin or kinetin alone. The concentrations of auxin and kinetin promoting growth of mericlones and proliferation of protocorms were chosen. Now, auxin or kinetin alone and in combination were applicated in this experiment to examine the effects on growth of Cymbidium and Cymbidium elcapitan. The results obtained were as follows. ① Survival ratio of Cymbidium wakakusa was higher in auxin alone, while that of Cymbidium elcapitan did in auxin and kinetin combined, but plant height of both varieties was retarded in combined medium with auxin and kinetin. ② Rooting was promoted by addition of growth regulators than control plot, especially, 0.5ppm NAA and 15.0ppm IBA showed high rooting ratio by 100%. ③ 1.0ppm IAA promoted plant height, 0.1ppm NAA, root growth, but protocorm proliferation was good at control and 1.5ppm kinetin in Cymbidium wakakusa, while plant height was higher in 15.0ppm IBA, root growth, in 0.5ppm NAA, and protocorm proliferation, 1.0ppm NAA and 15.0ppm IBA+1.5ppm kinetin in Cymbidium elcapitan.

서울地方의 TROMBICULID MITES : 特히 그 醫學的 意義에 對하여

全鍾暉,鄭喜泳 서울대학교 1958 서울대학교 論文集 Vol.7 No.-

The purpose of this study is to investigate the vector species of trombiculid mites of Scrub typhus and Epidemic hemorrhagic fever from the medical entomological viewpoint in Korea. The authors made a careful survey of the trombiculid mites on the indigeneous Rodentia, Insectivora, Chiroptera, Aves, Amphibia and Reptilia n the vicinity of Seoul during the period from January 1956 to December 1956. 1. A total of 5666 trombiculid mites were collected from a total of 3349 animals. The species of these hosts are shown table 1. 2. The following species of trombiculid mites were identified, Trombicula tamiyai T. nagayoi T. japonica T. mitamurai (collected for the first time in Korea) T. pomeranzevi ( ¨) T. orientalis T. palpalis T. pallida T. subintermedius T. myotis T. scutellaris (collected for the first time in Korea) Euschongastia kitajimai E. koreaensis E. miyagawai (collected for the first time in Korea) Gahrliepia brennani var. ventralis

부비동 점액낭종의 수술적 치험 : 4 Cases

장영록,정석원,김창수,전병찬,박용구,유태현,천태상,이화동 대한신경외과학회 1988 Journal of Korean neurosurgical society Vol.17 No.5

Mucocele is collection of mucus enclosed in a sac of lining sinus epithelium within an air sinus resulting from an obstruction to the outlet of the cavity which may cause an expansion of the bony walls. The condition commonly occurs in the frontal or anterior ethmoidal sinuses but, rare in sphenoid sinuses. Mucocele of the sinus is an uncommon cause of unilateral proptosis which may produce considerable difficulty in diagnosis. Ocular disturbances and headache are among the characteristic complaints and patients often first consult an ophyhalmologist or otolaryngologist. The authors experienced four cases of paranasal sinuse mucocele. There were 2 posterior ethmoid sinus mucoceles, 1 giant frontal sinus mucocele and 1 sphenoid sinus mucocele. These cases presented with exophthalmos, proptosis, headache or frontal mass. All cases removed by surgical procedures and good result was obstained.