Determining the coefficients of a homogeneous anisotropic hardening model for ultrathin steel sheets

Choi, J.H.,Zang, S.L.,Lee, M.G.,Kim, J.H.,Barlat, F. Elsevier 2019 International journal of mechanical sciences Vol.157 No.-

<P><B>Abstract</B></P> <P>In the present work, the constitutive description of a 0.1-mm-thick ferritic stainless steel sheet was optimized for application to springback simulations after bending. Springback simulations require Bauschinger effects to be characterized carefully, which is a challenging task with an ultrathin sheet. The coefficients of the homogeneous anisotropic hardening (HAH) distortional plasticity model were calibrated with Zang's novel approach based on three-point bending conducted on pre-strained sheets (Zang et al., 2014). The Hockett–Sherby isotropic hardening law and the Yld2000-2d non-quadratic yield function were considered in this work to complete the HAH approach. Moreover, the degradation of elastic modulus was also accounted for in the finite-element simulations. The coefficients of the HAH model were calibrated using an inverse method by minimizing the difference between experimental and predicted specimen profiles after three-point bending and springback of pre-strained sheets. To validate the coefficients determined with this three-point bending test, U-draw bending tests were conducted and finite-element simulations were carried out. The springback predictions were found to agree well with the experimental results for all three pre-strains investigated, namely, 0% (as-received material) and 7.5% and 12.5% pre-strained ferritic stainless steel sheets.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Mechanical behavior of ultrathin steel sheet was characterized in three-point bending. </LI> <LI> Specimens were pre-strained in uniaxial tension to produce strain path changes. </LI> <LI> A distortional plasticity model was used to describe the plastic behavior. </LI> <LI> An inverse method was adopted to optimize the coefficients of the plasticity model. </LI> <LI> The optimized coefficients were validated with U-draw bending test. </LI> </UL> </P>

同位元素 質量分析機에 의한 植物體中 ??N 測定法 確立 및 온주밀감의 尿素 葉面吸收量 測定에 관한 연구

유장걸,오상호 濟州大學校 亞熱帶農業硏究所 1998 亞熱帶農業硏究 Vol.15 No.-

ABSTRACT This study was conducted to establish the analytical conditions for determining 15N abundance ratio in plant leaves by the isotope ratio mass spectrometer. Effect of some factors related to the equipment performance such as tin capsule cleaning, ion source tunning, sample size and K-factor for total N analysis by the elemental analyzer were investigated using the standard reagents (urea and acetanilide), and citrus leaves. In addition, urea uptake by citrus leaves was measured with 8 and 20-month old leaves were dipped in 15N labelled urea solution(1.776 atom excess %) mixed with 0.05% surfactant and harvested 1, 2, 3, 10 and 17 days after 15N labelled urea application. 1. The analytical conditions for determining 15N isotope ratio in plant leaves a. N-peak was observed from the blank sample of tin capsule which is not cleaned. However, N-peak disappeared after cleaning tin capsules with acetone. b. K-factor for total N determination by the elemental aniyzer was evaluated in terms of the instrument stability. The result showed that the coefficient of variation for K-factor was low enough to obtain a good reproducibility. c. The optimal amount of standard reagents, (urea and acetanilide) and leaf sample for N analysis was in the range of 1 to 3 mg. d. The optimal N amount for 15N isotope ratio analysis was in the range of 0.359 to 0.424 mg. 2. The urea uptake by citrus leaves a. The amount of N absorbed by citrus leaves was increased by elevating the applied urea concentrations and had a maximum at 0.8-1.2% of urea concentrations. b. N amount contained in the leaves increased until 2 days after foliar application but thereafter decreased because N-translocation to the shoot became much more than N-uptake from leaf surface. c. N absorption by 8-month-old leaves was higher than 20-month-old leaves.

강남콩과 귀리뿌리중의 APTase活性의 特性에 關한 硏究

柳長杰 제주대학교 1982 논문집 Vol.14 No.-

강남콩(Phaseolus vulgaris)과 귀리(Avena sativa)뿌리를 마쇄하고 0.25 M-sucrose완충용액으로 추출한다음 80.000g로 원심분리하여 microsomal 분획내에 존재하는 APTase의 용액을 조제해서 칼륨과 마그네슘 및 몇가지 요인에 의해 달라지는 ATPase활성의 특성을 조사했다. 강남콩과 귀리에서 모두 마그네슘 및 칼륨에 의해서 ATPase는 활성화 되었는데 마그네슘에 의한 활성화가 더욱 현저했다. 효소를 최고로 활성화 시키는 칼륨의 농도는 강남콩의 경우가 1.6몰인 반면 귀리에서는 0.4몰농도였다. ATPase의 반응을 위한 적정 PH값은 강남콩의 경우 7인 반면에 귀리에서는 9였다. 귀리뿌리중의 ATPase활성은 발아후 5일에서 7일 사이에 급격히 증가하였다. 효소반응에 의한 온도와 시간을 증가시키면 ATPase의 활성이 증가했으며 마그네슘과 칼륨에 의한 활성은 그대로 유지되었다. Soluble adenosine triphosphatase(ATPase) from plant roots was investigated in relation to the enzyme activation by Mg??K??, and the other reaction factors such as pH, temperature, and tome. The ATPase solution was prepared from the roots of bean(Phaseolus vulgaris) and oat(Avena sativa) by centrifuging at 80.000g after extraction of 0.25M-sucrose buffer solution. The ATPases in both bean and oat roots were activated by Mg??and K?? The ATPase from bean roots had and optimum pH of 7 for ATP hydrolysis reaction while ATPase form oat roots gave a pH 9. The maximum activation of ATPase was shown at 1.6M-KCL in bean roots and 0.4M-KCO in oat roots. The activity of ATPase in oat roots was increased rapidly from 5 days after germination. Higher temperature and longer reaction time raised ATPase activity but did not change the characteristics of Mg+K dependent ATPase activation.

세포벽을 통한 유전물질 전이와 체세포 잡종의 재생

유장걸,소인섭,홍경애 제주대학교 1993 논문집 Vol.37 No.-

. The enzymatically isolated protoplasts generally give difficulties in cell differentiation and regeneration because the enzymes used could alter the physiological properties of protoplasts. In this study, the possibility that DNA could move out out of the cell isolated from radish hypocotyl callus was investigated after treatments with low pH, high concentration K??,GA₃combined with centrifugal force, all of which are known to affecct the physico-chemical properties of cells. 1. Treatment with 1.0% NaOCL for 20 min. by infiltration was found to be effective for the surface sterilization of radish seeds and the improvement of germination rate. 2. MS medium containing BA 0.5ppm and 2,4-D 1.0ppm gave the best callus formation from the radish hypocotyls. 3. The working concentration of SDS as an anion detergent which minimize the cell deterioration and function was 1ppm. 4. High K?? concentration(0.1% to 2.0%) and low pH(pH 4 tk 5) treatments resulted in the movement of DNA out of the radish hypocotyl callus cells. 5. The GA treatment was less effective than that of K??, but the DNA band appeared in the gel electrophoresis.

도시의 환원 황 화합물의 이산화황으로의 광화학적 변환

손장호,김기현 한국대기환경학회 2004 한국대기환경학회지 Vol.20 No.5

This study examines the local oxidation chemistry of reduced sulfur compounds (RSC) in the urban air. The chemical conversion of RSC (such as DMS, CS₂, H₂S, DMDS, and CH₃SH) to SO₂ was modeled using a photochemical box model. For our model prediction of the RSC oxidation, measurements were carried out from an urban monitoring station in Seoul (37.6˚N, 127.0˚E), Korea for three separate time periods (Sep. 17~18; Oct 23; and Oct. 27~28, 2003). The results of our measurements indicated that DMS and H₂S were the dominant RSC with their concentrations of 370±140 and 110±60 pptv, respectively. The conversion of DMDS to SO₂ can occur efficiently in comparison to other RSC, but it is not abundant enough to affect their cycles. The overall results of our study indicate that the photochemical conversion of the RSC can contribute < 20% of the observed SO₂.

유전자재조합 인간 골형성단백2 및 생흡수성고분자를 이용한 골형성유도체의 개발

이장희,김각균,안강민,김종원,이종호 大韓顎顔面成形再建外科學會 1999 Maxillofacial Plastic Reconstructive Surgery Vol.21 No.4

We tested the bone regenerating capacity and histologic response of bioresorbable matrix-type implant, which was made with Poly(lactide-co-glycolide)(PLGA) and bone apatite for the carrier of bone morphogenetic protein(BMP). The critical size defect of 8mm in diameter was created at the calvaria of SD rats(n=18), and repaired with polymer implant with 15㎍ of rhBMP-2(n=9) or without it(n=9). At 2 weeks, 1 months after implantation, the animals were sacrified(3 animals at every interval and group) and histologically evaluted. The calvarial defect which was repaired with polymer with BMP healed with newly formed bone about 70% of total defect. But that without BMP showed only 0 to under 30% bony healing. Inflammtory response was absent in both group through the experimental period, but there's marked foreign body giant response though it was a little less significant in polymer with BMP group. As the polymer was resorbed, the space was infiltrated and replaced by fibrovascular tissue, not by bone. In conclusion, our formulation of bioresorbable matrix implant loaded with bone morphogenetic protein works good as a bone regenerating material. However, it is mandatory to devise our system to have better osteoinductive and osteoconductive property, and less mutinucleated giant cell response.

액체 섬광 계수를 위한 식물체 시료 조제방법

유장걸,송성준 제주대학교 1984 논문집 Vol.17 No.-

Quenching is very important factor for liquid scintillation counting and depends on the sample prepara-tion method, especially when soft-beta emitters such as H-3, C-14 or S.35 are used as a tracer. Undability of natural background and quenching caused by the different sample preparation procedures were discussed. 1. The background level of plant samples appeared to increase by NCS treatment because of the chemical luminescent effect. Hlgher than 10000 cpm of background, especially in case of the fresh plant sample, was observed after 24 hours keeping the counting samples in the dark place. Although most of this high background disappeared after 5 days leaving, NCS treatment for the plant sample preparation in liquid scintillation counting proved not to be desirable. 2. The samples prepared by ashing or 95% alcohol extraction showed much low background counting. 3. A proper dilution should be done to reduce the degree of color quenching when plant leaves are extrac-ted by 95% alcohol or treated by NCS. 4. The plant samples from the water culture generally gave higher background counting than those from the soil culture, though the reason could not be understood at present.

Cl과 SO₂처리가 감귤의 無機物과 糖 및 有機物의 조성에 미치는 영향

柳長杰,宋成俊 제주대학교 방사능이용연구소 1986 연구보고 Vol.2 No.-

본 연구는 Cl과 SO₄처리가 감귤품질의 指標가 되는 糖과 有機酸함량에 미치는 영향을 알아 보기 위하여 與津早生을 시험재료로 하여 遂行된 것으로, 1984년도에는 砂耕재배와 葉面施肥를 통하여 Cl과 SO₄를 처리했을 때 감귤잎중의 無機物, 糖함량이 어떻게 변하는가를 조사하였고, 1985년도에는 Cl과 SO₄를 엽면시비 했을 경우 감귤果肉중의 당과 유기산함량에 미치는 영향을 조사하였으며, 그 결과는 다음과 같다. 1. Cl과 SO₄를 엽면시비했을 경우 감귤잎중의 Cl또는 SO₄함량이 증가되었다. SO₄처리에 의해서 P, Fe의 엽중함량이 증가되었고, Cl처리에 의해서 Ca, K, Zn, Cu등의 엽중함량이 높아짐을 볼 수 있었다. 2. 사경재배시에는 Cl과 SO₄처리에 의하여 Cl과 SO₄의 엽중함량이 증가되었으며, SO₄처리에 의해서 N, Ca, Mg, Fe, Cu등의 엽중함량이 증가되었고 Cl처리에 의해서 신엽의 Fe함량이 감소되었다. 3. 사경재배시 Cl처리보다 SO₄처리를 했을 때, 신엽중의 환원당, 비환원당, 전당 함량이 증가되었다. 4. Cl과 SO₄를 엽면시비했을시, 당의 경우에는 Cl보다 SO₄처리를 했을 때 감귤과육중의 환원당, 비환원당이 증가되었는데, 당을 HPLC로 분획정량해 본 결과 fructose, glucose, sucrose 함량이 전반적으로 증가됨을 알 수 있었고, 이같은 결과가 당도증진에 기여할 것이라 생각된다. 5. 유기산의 경우를 보면, Cl과 SO₄를 엽면 시비했을 때 SO₄에 의해 과육중의 적정산, 전산함량이 감소되었고, 또한 HPLC분석에 의하면 citric acid, oxalic acid는 SO₄에 의해 감소되나 malic acid는 증가됨을 알 수 있었다. 따라서 Cl보다 SO₄처리가 감미비증가라는 감귤 품질향상 측면에서 효과가 있는 것으로 생각된다. The effect of Cl and SO₄treatment on the contents of sugars and organic acids in mandarin juice was investigated from 1984 to 1985. In 1984, Cl and SO₄were supplied by foliar spraying and the sand culture method to determine the change of inorganic elements and sugar contents in the leaves. In the second year, the contents of sugars and organic acids in the fruit juice were analyzed to determine the effect of the Cl and SO₄foliar application. 1. Separate foliar applications of Cl and SO₄increased the contents of Cl and SO₄in leaves, respectively. The P and Fe contents of leaves were higher in the SO₄treatment than in the Cl treatment but the contents of Ca, K, Zn and Cu were higher in the Cl treatment. 2. When Cl and SO₄were applied individually to the sand culture, the contents of N, Ca, Mg, Fe, and Cu as well as SO₄in leaves were higher in the SO₄treatment than in the Cl treatment. The reduction and non-reducing sugars in the leaves increased more with the SO₄treatment than with the Cl treatment. 3. The foliar application of SO₄increased the contents of reducing sugars and total sugars in the fruit juice. HPLC analysis showed that the concentrations of fructose, glucose, and sucrose in the fruit juice were higher in the SO₄ treatment than in the Cl treatment. 4. The concentrations of titratable acid and total acid in the fruit juice were lower in the foliar application of SO₄than Cl. According to HPLC anaysis, SO₄ treatment decreased the citric acid and oxalic acid contents of the fruit juice but increased the malic acid. Consequently it can be concluded that a foliar application of SO₄is preferable to Cl as it increases the ratio of sugar to organic acid in mandarin juice.

Marker Gene의 직접삽입에 의한 Transgenic Plant의 제조 및 전기융합

유장걸,소인섭,홍경애 제주대학교 1993 논문집 Vol.37 No.-

. The conditions required for plant transformation through the Agrobacterium tumefaciens system and the electroporation method were investigated for Raphanus sativus L. and Brassica rapa L. 1. The highest viability of protoplasts was obtained when 7 days and 10 day-old seedlings were used. 2. The optimum conditions for electroporation was 1.77kV/cm for 40 μsec under which 70% of the protoplasts were viable and 58% of the viable protoplasts were stained with methylene blue. 3. The pBin19 plasmid used as a carrier vector was isolated from E.coli DH5α, purified and identified on the electrophoresis agarose gel. 4. The triparental mating was performed for pBin19/DH5α(kana+), pRK202013/HB101(kana+), and LBA4404(strep+) of Agrobacterium tumefaciens, and confirmed using the mixture medium of kanamycin and streptomycin. The band of pBin19 isolated from the transconjugated Agrobacterium tumefaciens was also observed on the agarose gel electrophoresis. 5. Cell differentiation was observed from the leaf disks infected with the transconjugated Agrobacterium tumefaciens after 15 days cocultivation on the medium containing cefotaxime 200ppm and kanamycin 100ppm.

인광석의 인산비효증진에 관한 연구-토양중 mycorrhizae 포자밀도조사 및 인광석용해성사상균의 분리와 배양-

유장걸,김형옥,이신찬 제주대학교 1985 논문집 Vol.20 No.-

To make a survey on the distribution of V. A. mycorrhizae on Cheju-Island. 60 soil samples were taken from the cultivated and non-cultivated lands (27 volcanic soils and 33 non-volcanic soils). Spore densities (spore number/100g soil) were measured by the floating method Phosphate-solubilizing fungi were isolated from 18 soil samples and selected by the pure cultivation method on PDA-calcium phosphate media Adaptation cultivations of the selected fungi were conducted in the rock phosphate-liquid media succeesive- ly with the change of sugar to straw composition. 1. Low spore density below 100 was observed in 19 sampling sites and high density above 500 was shown in only five fields, rest of the locations being ordinary levels. It seemed that spore density was related to the locality but not to pH. water content, total nitrogen and phosphate percentage of the soil. 2. Phosphate solubilizing fungi were found on PDA-calcium phosphate media in 41 soil samples. 3. After 6-day pure cultivatin on PDA-media. fungi having 8-15mm of colony radii(R). 14-22mm of halo radii(H) and higher H/R ratio than 1.2. were obtained in 18 soil samples. 4. Five successive cultivations in the liquid media containing powdered rock phosphate were undertaken to adapt the selected fungi to the low sugar/straw condition (sugar 0.35%. straw 1.15%). At the end of 5 th cultivation, seven fungi (from soil No. 1. 8. 24, 26. 31, 43 and 45) remained and showed about 29 percentage of rock phosphate solubility making the liquid media neutral.