활성탄화에 의한 은의 흡착에 관한 수학적 모델

한윤봉,임석중,한규진 대한금속재료학회(대한금속학회) 1986 대한금속·재료학회지 Vol.24 No.8

Experiments were carried out to study the adsorption of silver from a cyanide solution on activated carbon. The tests were conducted on a variation of inital silver concentration (Co), carbon amount(W). mixing speed, particle size and adsorption temperature. The experimental data were found to fit Freundlich adsorption isotherm as well as Langmuir adsorption isotherm. It was found that the loading carpacity of the carbon was 20 ㎎ Ag/g carbon. The isosteric heat of adsorption was found to be 1.48 ㎉/g-mole, indicating physical adsorption. The experimental results were finally compared with the theoretical results obtained by the mathematical modeling equation. A correlation equation was also developed to predict the late of apparent adsorption. Good agreements were obtained.

P 첨가 냉간압연 고강도강의 성형성 및 집합조직에 미치는 열간압연 코일링 온도의 영향

한봉희,임태홍,박영구 대한금속재료학회(대한금속학회) 1985 대한금속·재료학회지 Vol.23 No.8

Cold-rolled sheet steel for automobiles requires high strength and good drawability, for that purpose P-bearing low carbon, low maganese Al-killed steel is investigated. For various coiling temperatures on hot rolling stage, the effects of coiling temperatures on textures and deer-drawability of P-bearning steel were investigated by 1) pole intensity analysis 2) Transmission Electron Microscopy 3) plastic strain ratio determination from tensile test. No apparent changes in textures of hot-rolled sheet and cold-rolled sheet were detected within the range of coiling temperatures examined. The optimum coiling temperature for good recrystalization texture, high average strain ratio (R) and low planar anisotropy (ΔR) after recrystallization annealing was 600℃. However, differences in their characteristics were very slight except the specimen of coiling temperature 700℃ However, since the maximum tensile strength of the specimen was obtained when coiled at 600℃, optimum coiling temperature which could provide good deep-drawability while sustaining high strength might be concluded to be around 600℃ in this steel.

활성화 반응성 증착에 의한 탄화물 막 구조 및 성질에 관한 연구

한봉희,송요승,윤의준 대한금속재료학회(대한금속학회) 1984 대한금속·재료학회지 Vol.22 No.6

TiC films, through A.R.E. (Activated Reactive Evaporation), were deposited on 304 stainless steel substrate. The structure and properties of TiC films were analyzed according to the substrate temperatures and the partial pressures of the reactive gas (C₂H₂). Coated surfaces and cross sections were examined by S.E.M., and the pole intensity were measured by x-ray diffraction. Hardness was measured by a Micro Vickers Hardness Tester with 10 gr load. Surface structure was of micro-dome structure at low temperature (=0.23 T_m) and the micro-dome structure changed to smooth dome-structure at 650℃ (=0.28 T_m). The intergrated pole intensities of (200) and (220) increased with temperature, but that of (111) were strong at all temperatures. Hardness decreased from 3000 to 1875 ㎏/㎟ and C/M ratio decreased from 0.701 to 0.667, with decreasing temperature and partial pressure.

Cr 강에서 석출된 복합탄화물의 조대화거동에 미치는 Si의 역할

김영희,한봉희,이상윤 대한금속재료학회(대한금속학회) 1986 대한금속·재료학회지 Vol.24 No.5

The role of Si on the coarsening behaviors of complex carbide particles precipitated in Cr and Cr-Si steels has been investigated using various quantitative metallographic techniques after spheroidizing over the holding time range 300 to 1800 hours at three different temperatures 650, 680 and 710℃. Most of M₃C type complex carbides precipitated in Cr-Si steel are shown to form along grain boundaries and their average particle sizes appear to be smaller in finer ferrite grains, as compared to those in Cr steel. The value for the slope of each straight line obtained from the relation between the log of average particle size find spheroidizing time is approximately 1/3, which is in agreement with diffusion-controlled growth mechanism. The addition of Si to Cr steel does not change the mode of growth equation for M₃C type complex carbide precipitates Activation energes of 195 KJ mol^(-1) for Cr steel and 227 KJ mol^(-1) for Cr-Si steel are found to give rise to the interdiffusion mechanism of Fe, C, Cr and Si involved in each steel. The experimentally determied particle size distributions approach the steady-state distribution curve as spheroidizing treatment proceeds. The shape of curves, however, shows 3 tendency that the range of particle size distribution is wide with a lowered height of the distribution curve.

Cr 첨가 저탄소 보론강의 기계적 성질에 관한 연구

김영희,이종민,한봉희 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.12

The hardenability and mechanical properties of Low-carbon steels containing Cr were investigated and the results were correlated with Cr content. The hardenability decreased with increasing the austenitizing temperature and increased with Cr content. But the hardness was increased slightly by dereasing the tempering temperature and increasing Cr content. And the softening of boron steels by adding Cr was delayed during tempering. There was one step embrittlement in notch toughness test, the thin and long particles precipitated along the lath boundary may be a major factor. The tensile properties were improved by adding Cr. Impat energy increased when tempered at higher temperatures, hut tensile strength and yield strength decreased continously with tempering temperature.

17% Cr 페라이트 스텐레스 강판에서 냉간압연율 (冷間壓延率) 에 따른 재결정집합조직이 가공성에 미치는 영향

김영희,한봉희 대한금속재료학회(대한금속학회) 1982 대한금속·재료학회지 Vol.20 No.3

The effects of recrystallized and rolling textures obtained by two kinds of double step cold rolling schedules with intermediate annealing on the formability of commercial 17% Cr ferritic stainless steel sheets were examined by the plastic strain ratios and earing behavior in deep-drawing. The relation between average plastic strain ratio and textures was qualitatively interpreted. The optimum condition of high average plastic strain ratio, low anisotropy, and high yield strength was found at 50-50% reduction for 86% of total reduction process ( r￣=1.24, Δr=0.88, Y.S.=38.4kg/㎟, U.T.S.=52.1kg/㎟), and 63%-76% reduction for non-specified total reduction process ( r￣=1.36, Δr=0.97, Y.S.=40㎏/㎟). Qualitative agreement in r￣ values between experimental and calculated values were satisfactory. With increasing total cold reduction of double step cold rolling, yield strength and ultimate tensile strength increased because of texture component, and the longitudinal strength was superior to the transverse strength due to (001) [110] texture. The hardness and work hardening exponent were not influenced by the rolling reduction and texture.

이상영역 어닐링처리한 미량합금첨가 Fe-C-1.5 Si 강의 미세조직에 관한 연구

하성룡,김영희,한봉희 대한금속재료학회(대한금속학회) 1989 대한금속·재료학회지 Vol.27 No.7

Effects of intercritical annealing on tensile properties of Fe-C-1.5 Si steels were investigated ; changes of the properties were interpreted refer to the microstructural changes due to microalloying of 0.5Mo-0.015Ti and 0.069Al and isothermal bainite transformation at 400-440℃. Increases of carbon content and the bainitic transformation temperature increased the fractional retained austenite and the volume fraction of martensite, respectively. Best tensile properties were obtained when the steels with 0.069 % Al were isothermally transformed at 420℃ after intercritical annealing at 770℃.

3 % 규소 강판의 열간압연 집합조직에 관한 연구

김정태,한봉희,박용범 대한금속재료학회(대한금속학회) 1983 대한금속·재료학회지 Vol.21 No.8

Effects of hot rolling temperature and reduction ratio on the crystal grain and texture of 3% Si steel were examined by structure observation, texture coefficient and pole figures. During 1 pass hot rolling, recrystallization was started at surface layer. The degree of recrystallization would rather depend on hot rolling temperature than reduction ratio. As hot rolling temperature was lower, the thickness of recrystallized layer was decreased. Crystal grains of surface layer of 1 passed hot rolled specimen were strongly (110) and that of middle layer were (200). About 1000℃, (110) intesity was especially strong at surface layer and ¼thickness layer. Texture were generally heterogeneous in the hot rolled state. But grains were textured more prominently in the case of 6 pass hot rolling than 1 pass hot rolling. (110) texture was especially developed at ¼thickness layer in 6 pass hot rolled state. (110) texture was, however, distinct in sample E, which rolled contrary to conventional hot rolling schedule.

저탄소 Al-킬드강의 연속 어닐링에서 과시효 처리공정 중 탄화물 석출거동에 관한 연구

김성호,한봉희,박용범 대한금속재료학회(대한금속학회) 1986 대한금속·재료학회지 Vol.24 No.8

Precipitation behavior of carbides and texture change in a deep drawing sheet steel were studied by heat treating in a production scale continuous annealing line. Effect of annealing, quenching and overaging temperatures were investigated. The site of carbides precipitated during overaging treatments became larger and the Vickers hardness number decreased as the temperatures for quenching and overaging increased. After a overaging treatment at 350℃, finely dispersed plate-like carbides were precipitated in the matrix, white at overaging treatments of 400℃, carbides precipitated along grain boundaries in a form of film and within matrix in a form of coarse particles. The recrystallized structure showed a (111) type texture with the main component of (111) [1￣1￣2]. The(111) pole intensity and I_(222) I_(200) became higher as the annealing temperature increased within the α-phase region.

Rapid preparation and single-cell analysis of concentrated blood smears using a high-throughput blood cell separator and a microfabricated grid film

You, D.,Oh, S.,Kim, B.,Hahn, Y.K.,Choi, S. Elsevier 2017 Journal of chromatography Vol.1507 No.-

<P>Cytological examination of peripheral white blood cells inhomogeneously distributed on a blood smear is currently limited by the low abundance and random sampling of the target cells. To address the challenges, we present a new approach to prepare and analyze concentrated blood smears by rapidly enriching white blood cells up to 32-fold with 92% recovery on average at a high throughput (1 mL/min) using a deterministic migration-based separator and by systematically analyzing a large number of the cells distributed over a blood slide using a microfabricated grid film. We anticipate that our approach will improve the clinical utility of blood smear tests, while offering the capability to detect rare cell populations. (C) 2017 Elsevier B.V. All rights reserved.</P>