Effects of Cooling Rate on the Microstructure and Tensile Properties of Wire-Arc Additive Manufactured Ti–6Al–4V Alloy

Hui‑Jun Yi,Jin‑Woo Kim,Young‑Lak Kim,Sangyong Shin 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.8

Wire-arc additive manufacturing has emerged as a technology that could replace the conventional manufacturing processof titanium alloys. However, it produces a coarse β grain, which can accumulate via several deposited materials, resulting isstrong texture and anisotropy. To investigate potential solutions, the effects of the cooling rate on the resulting microstructureand tensile properties were studied. The cooling rate of the deposited materials was adjusted by interpass temperaturecontrol. Under rapid cooling, fine α + α′ grain with a low aspect ratio were observed and tensile and hardness propertieswere also improved.

Four new compounds from the bulbs of Lycoris aurea with neuroprotective effects against CoCl2 and H2O2-induced SH-SY5Y cell injuries

An Jin,Xuelian Xiang,Yun-Yun Zhu,Heng-Yi Yu,Hui-Fang Pi,Peng Zhang,Han-Li Ruan 대한약학회 2014 Archives of Pharmacal Research Vol.37 No.3

Three new alkaloids, 2a-hydroxy-6-O-n-butyloduline,O-n-butyllycorenine, (-)-N-(chloromethyl)lycoramine(1–3), and a new phenolic compound, ((7S)-7-(4-hydroxyphenyl)-7-hydroxypropyl)-20-methylbenzene-30,60-diol (14), along with ten known alkaloids (4–13), wereisolated from the bulbs of Lycoris aurea collected fromHuaihua County of Hunan Province, China. Their structureswere elucidated by spectroscopic methods includingHRESIMS, UV, IR, and NMR. All the isolated compoundswere tested for their neuroprotective effects against CoCl2and H2O2-induced SH-SY5Y cell death. Compounds 1–7and 10 exhibited significant neuroprotective effects againstCoCl2-induced SH-SY5Y cell injury, while compounds1–5, 7, 10 and 12 showed obvious neuroprotective effectsagainst H2O2-induced SH-SY5Y cell death.

Effects of Quenching Methods and Aging Processes on the Crushing Properties and Microstructure of Al–Zn–Mg Alloy Thin-Walled Square Extrusions

Hui Guo,Jin Zhang,Cheng Wang,Yun‑lai Deng 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

In this study, the effects of different (online quenching and offline quenching) quenching methods and aging processes (T6and T73) on the crashworthiness and microstructural evolution of three Al–Zn–Mg alloys (G1–G3) were studied by conductingtensile test and axial compression tests at room temperature, combined with optical metallography, electron back scattereddiffraction, and transmission electron microscopy microstructural observations. The obtained results revealed that thecrushing properties of three different Al–Zn–Mg alloys subjected to different quenching methods and aging processes weresignificantly different. Their crushing energy absorption of are ranked as follows: G1 > G3 > G2. The highest total energyabsorption gap (between T6 and T73) is the G1 alloy, and the lowest one is the G3 alloy. The largest total energy absorptiongap between the two quenching methods is the G3 alloy, and the smallest one is the G1 alloy. The G2 alloy with the largesttotal amount of Zn + Mg has the highest number density of matrix precipitates, the largest precipitate gap (between T6 andT73) and the smallest precipitate gap between the two quenching methods. The G3 alloy with the largest Zn/Mg ratio hasthe smallest number density of matrix precipitates, the minimum precipitation gap (between T6 and T73) and the maximumprecipitation gap between the two quenching methods. The G1 alloy with the lowest Zn/Mg ratio has the smallest size ofgrain boundary precipitates and PFZ width, while their largest values are obtained for the G3 alloy with the maximum Zn/Mg ratio. As a crushing resistant structural material, the crushing properties is improved without reducing the strength. Theratio of Zn/Mg should be controlled within the range of 4.57–6.15, while the total amount of Zn + Mg should be controlledwithin the range of 6.18–7.01.

Sol-Gel법을 이용한 Silica Membrane의 제조 공정에 관한 조사연구

이진휘,이준,김화중 서울産業大學校 1990 논문집 Vol.32 No.1

졸 -겔 공정에 대한 일반적인 문헌들을 검토하였다. 이와같은 문헌들을 성공적으로 적용하려면 공정에 대한 여러가지 단계와, 영향을 미치는 인자들에 관한 체계적인 이해가 먼저 요구된다. 겔화하는 동안 구조 및 미세구조의 전개에 영향을 미치는 몇가지 인자와 더불어 건조 및 열처리 조건을 조사하였다. 혼합물, 다공성 고체 및 코팅분야에 적용하기 위한 몇가지 예들을 기술하였다. 현재 이 분야의 발전에 기여할 새로운 응용기회는 많다. The general informations of the sol-gel process are reviewed. Successful applications are dependent on sufficient scientific understanding of the various stages and factors of the process. A number of factors governing the development of the structure and microstructure during gelation and subsequent drying and firing conditions are mentioned. Examples are described for applications in the areas of composites, porous solids and coatings. Opportunities for many new applications are presently available for exploitations.

감초로부터 글리시리진의 추출 및 정제

이진휘,서성조,서동호 서울産業大學校 1999 논문집 Vol.49 No.2

시장에서 구입한 감초를 70∼80℃의 물에 하루 동안 담가두어 감초내의 혼합 성분들을 추출한 후, 글리시리진이외의 성분들(sugars, starches, flavonoids, saponoids, aminoacids, gums and essential oil 등)이 에탄올에 용해되는 성질을 이용하여 글리시리진만을 선택적으로 분리해내기 위하여 에탄올 및 에탄올/아세트산 혼합액(99:1)을 각각 사용하였다. 글리시리진의 정성 및 정량분석은 HPLC(Waters 600 controller)를 사용하였다. 사용된 column은 μbondapak C??, 이동상은 물/아세트산/아세트나이트릴을 61:1:38로 만들어 유속 1.5㎖/min.을 적용하였다. 글리시리진 표준물질은 일양약품에서 제공한 글리시리진 암모늄염을 사용하였다. 정제 효과를 알아보기 위해 감초에서 물로 추출한 경우, 에탄올로 처리한 경우, 그리고 에탄올/아세트산(99:1) 혼합액으로 처리한 경우의 각각에 대한 글리시리진 함량을 비교 분석한 결과 순서대로 22.4%, 25.0% 및 29.5%로 나타났다. Glycyrrhizin was extracted from Glycyrrhiza uralensis(Licorice) with water at 70~80℃ for 24hours. To remove another components(usually sugars, starches, flavonoids, saponoids, aminoacids, gums, and essential oil etc.), extracted glycyrrhizin was purified with ethanol or ethanol/acetic acid (99:1). HPLC was used to quantitative and qualitative analysis. The colume used was μ bondapak C??(Waters) and mobile phase was water/acetic acid/acetonitrile(61:1:38) with 1.5㎖/min. flow rate. The amounts of glycyrrhizin Prepared after extracted by water, ethanol and ethanol/acetic acid(99:1) were 22.4%, 25.0% and 29.5% individually.

SPOT을 통한 문법항목의 난이도 고찰

최진희 배재대학교 주시경교양교육연구소 2017 대학교양교육연구 Vol.2 No.1

본 고에서는 전공 및 교양 초급 클래스에서 다양한 배경을 가진 일본어 학습자를 대상으로 SPOT 테스트를 이용하여 문법 항목의 난이도를 조사한 것이다. SPOT는 자연 발화 속도로 언어를 처리하는 능력이 있어야만 해답할 수 있는 테스트이다. 정답률이 50%이하인 경우는 8개(13.3%)로 で(お)いてください가 가장 정답률이 낮았다. 다음으로는 なに(が), どこに(も), (し)かない,(お)持ちする가 낮았다. 발음 상 듣기 어려운 표현과 부정 표현을 동반하는 관용 표현, 겸양 표현이 습득하기 어려운 항목으로 분류된다. 부정 표현과 동반하는 표현은 습득하지 못한 것으로 특히 주의하여 지도할 필요가 있겠다. 주로 초급 문법 항목 중 이른 시기에 도입되는 표현들이 잘 습득할 수 있도록 지도법을 개선 보완할 필요가 있겠다. In this paper, I have researched the level of difficulty on Japanese grammar in SPOT test, which is taken by Japanese learners who have various background. SPOT is a test which can be answered by the people who have capabilities to understand in natural discourse speed. As the result of the test, there were 8 questions which have less than 50 percents of the rate of correct answers. The question "deoitekudasai" had the lowest rate because listening to "de+oi" sound was very difficult. The correct answer rates of idiomatic expression and honorific expression were also pretty low compared to other questions. Even though the learners acquired the negative expression at the beginning stage, acquisition of the negative expressions was low. Therefore, teaching methods of negative grammar need to be revised.

Sol-Gel법을 이용한 Silica Ceramic합성에 있어서 화학 구조 변화에 관한 연구

이진휘,정은정 서울産業大學校 1995 논문집 Vol.42 No.1

Sol-gel공정에 의하여 TEOS를 이용하여 silica ceramic을 합성하는 공정중 건조 및 소성공정중의 중간생성물의 변화를 20℃, 40℃ 및 60℃로 반응시킨 시료에 대하여 TG/DTA, FT-IR 및 X-ray diffraction에 의하여 실험하였다. 실험 결과 반응온도가 높을수록 가수분해 속도가 증가되었으며 중간 생성물의 양도 증가하였다. 고립된 Si-OH중 -OH의 증발은 700∼800℃정도에서 일어나며, 60℃에서 건조한 시료의 경우 급격한 가수분해 및 축중합반응으로 인하여 역반응에 의한 약간의 불완전한 치환형태의 alkoxide가 잔류하는 것으로 사료된다. The chemical components produced by drying and sintering process during synthesizing of silica ceramic by sol-gel process were characterized by using TG/DTA, FT-IR and X-ray diffraction to evaluate the changing intermediates for the samples treated by three different drying temperatures, 20℃, 40℃ and 60℃. The results showed that the higher the reaction temperature, the faster the rate of hydrolysis and the large the concentration of intermediates. Dehydroxylation of Si-OH starts in the early stage of the thermal treatment and continues up to 700∼800℃. It is supposed that alkoxides might be formed by backward reaction derived by hydrolysis and condensation-polymerization abruptly in case of dried at 60℃.

Sol-Gel법을 이용한 다공성 Silica Ceramic 합성에 있어서 물이 겔화시간 및 평형농도에 미치는 영향에 관한 연구

이진휘,김화중,이준 서울産業大學校 1992 논문집 Vol.35 No.1

본 연구에서는 sol-gel process에 의하여 silcon계 다공성 ceramic물질을 합성하고, 합성 과정에서 중요하게 작용하는 인자들을 조사하였다. 중요한 인자들로 여러가지를 들수 있는데, 본 연구에서는 gelation time과 FT-IR을 이용한 최종 생성물의 화학 구조 조사에 의하여, 반응이 평형 상태에 도달하는 데 요구되는 물의 영향에 대하여 조사하였다. 실험 결과 EtOH/TEOS molar ratio가 7.6일 때, 반응이 평형에 도달하는데 소요되는 물의 양은 약 11mole인 것으로 사료되었다. The synthesis of porous silica ceramic material using sol-gel process was performed and the influencing factors during the synthesis were evaluated. Among several influencing factors, however, in this research program, the equilibrium concentrations of H₂O during hydrolysis and poly-condensation were studied based on the investigations of gelation time and chemical structures for the final porous ceramic materials using FT-IR. The results suggested that the equilibrium concentration of H₂O was about 11 moles for 7.6 of EtOH/TEOS molar ratio.

감초로부터 Glycyrrhizin 추출

이진휘,장향동,최하영,서동호,이성미,김경하 서울産業大學校 1998 논문집 Vol.47 No.1

Glycyrrhiza uralensis계의 원감초 뿌리에서 추출도는 감초는 여러가지 질병의 약제로 널리 이용되어 왔다. 그 주성분인 gliycyrrhizin은 항염증 활성 및 anti-allergic activity를 갖고 있으며 이러한 생리활성은 aglycone β-gliycyrrhetinic acid 의 활성에 의한 것으로 알려져 있고, β-gliycyrrhetinic acid는 steroid 구조와 유사하며, 면역조절 특성을 갖는 것으로 인식되고 있다. 이러한 β-gliycyrrhetinic acid 의 면역조절 활성에 기여하는 인자와 그 경로에 대하여 조사된 바 있다 Glycyrrhizin은 감초뿌리의 주성분중 하나이며, 그외에도 surgars(14%), starches(30%), flavonoids, saponoids, amonoacids, gums 및 essential oil 등을 포함하고 있다. Licorice, the root extract of Glycyrrhiza uralensis, is used as a medicine for various diseases. Antiinflammatory as well as anti-allergic activities have been attributed to one of its main constituents, glycyrrhizin. These activities are mainly ascribed to the action of the aglycome β-glycyrrhetinic acid. βGlyeyrrhetinic acid has a steroid-like structure and is believed to have immunomodulatory properties, To determine whether interference with complement functions may contribute to the immunomdulatory activity of β-glycyrrbetinic acid. its effect on the classical and alternative activation pathways of human complement were investigated. The main constituent found in the root is glycyrrhizin. The plant also contains various sugars(14%), starches(30%), flavonoids, saponoids, aminoacids, gums, and essential oil etc.

전기분해에 의한 염색폐수의 탈색에 관한 연구

이진휘,이진희,연만형,조성국 서울産業大學校 1997 논문집 Vol.46 No.1

전기분해에 의한 염색폐수의 탈색효과를 규명하기 위하여 Fe, Al 및 Cu극판을 단일 또는 혼용하여 적색, 황색 및 청색산성염료 200ppm에 대하여 탈색실험을 수행한 결과 Fe(+)와 Al(-)전극을 혼용하고, 극간거리가 1.5㎝일 때 가장 제거율이 좋았다. 염색폐수의 농도 50∼250ppm에 대하여 전해질로써 NaCl을 0.1∼0.5% 사용하고 전류밀도 0.033∼0.166A/㎠로 실험한 결과 6분이상의 시간 경과후 95%이상 색도가 제거되었고, 전해질의 농도가 높을수록 소비전력은 높아지고 제거율은 향상되었으나 시간이 지남에 따라서 전력소비는 거의 일정하였다. This experiment is performed to investigate the decoloration of dye wastewater by using the same or different electrodes of Fe, Al and Cu. The waste solution consists of a single colored acidic dye of red, yellow or blue with a concentration of 200ppm. The results showed that the combination of Fe(+) and Al(-) electrodes and a distanced of 1.5㎝s between the electrodes was best for the decoloration process. It showed more than 95% decoloration occurred after 6 min. when we used NaCl solution of 0.1∼0.5% for electrolysis and current densities of 0.033∼0.166A/㎠ with solutions of 50∼250ppm. The higher the concentration of electrolyte, the higher the consumption of power becomes constant after a period of time.