Study on Microstructure and Mechanical Properties of the Al–25Cr–5Si (at%) Alloy Powder Using Gas-Atomization and SPS Process

Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.

유자과즙을 이용한 식초제조

김용택,서권일,정용진,이용수,심기환 동아시아식생활학회 1997 동아시아식생활학회지 Vol.7 No.3

To enhance the utility value of citron, vinegars were made of citron juice, their properities were investigated, the results are as following. Optimum bacteria was Acetobacter sp. PA 97 for the citron vinegar fermentation, optimum temperature, initial acidity and alcohol concentration were 30℃, 1.5% and 8%, respectively. The lower citron juice was added, the more citric acid was produced, the acidity of sample added sub-nutrition source was higher than that of sample no added. In samples added citron juice of 10, 20 and 30%, and sub-nutrition source, total acidity were 5.42, 5.36 and 5.04%, pure acetic acid yields were 52.69, 45.25 and 35.10%, respectively. Remained alcohol of sample no added sub-nutrition source was more than that of added. In the sensory test, the most suitable concentration of citron juice for vinegar fermentation was 30%.

Hybrid Light‐Emitting Diodes: Electrically Driven Quantum Dot/Wire/Well Hybrid Light‐Emitting Diodes (Adv. Mater. 45/2011)

Ko, Young‐,Ho,Kim, Je‐,Hyung,Jin, Li‐,Hua,Ko, Suk‐,Min,Kwon, Bong‐,Joon,Kim, Joosung,Kim, Taek,Cho, Yong‐,Hoon WILEY‐VCH Verlag 2011 ADVANCED MATERIALS Vol.23 No.45

<P>Electrically driven hybrid light‐emitting diodes (LEDs) consisting of quantum dots, wires, and wells based on the nanometer‐sized pyramid GaN structure are reported by Taek Kim, Yong‐Hoon Cho, and co‐workers on page 5364. The LEDs exhibit mixed emissions from InGaN quantum dots, wires, and wells formed at the tops, edges, and sidewalls of the pyramids, respectively. The hybrid LEDs containing low‐dimensional quantum structures provide a broad‐band, highly efficient visible lighting source. </P>

대학생의 운동참여수준에 따른 신체상 지각과 우울 및 불안의 관계

임용택,김덕진 남서울대학교 2017 남서울대학교 논문집 Vol.23 No.-

경막내 척수 섬유지방성 과오종 치험 1례 - 증 례 보 고 -

이용근,조준,문창택,장상근 대한신경외과학회 1998 Journal of Korean neurosurgical society Vol.27 No.10

외국문화 이식을 위한 외국어 실력을 대학교육기간내에 기를 수 있는 교과과정 및 교재와 설비에 관한 연구

최용재,박재만,박윤환,정봉택,최용섭 朝鮮大學校 1977 綜合論文集 Vol.1977 No.-

This paper aims to find ways of tackling stagnant factors in the foreign language education on the college level. Here the foreign language learning is geared to a working command of the foreign language with the view to having access of the advanced foreign technology. And the working command of the foreign language requires not only language skills but a thorough understanding of the cultural background of the language. However, to incorporate all of the cultural aspects into a textbook is a really exhaustive work and is too bulky for a short course to handle all the aspect of the culture. A partial mastery is to be recommended with a condition that a spiral approach must be used to cover pertinant aspects and, in some cases, peripheral aspects which play important key roles. As to the methodology of the lesson, this paper is not to side any one method and it rather intends to persuade using any method out of the whole spectrum of the methodolgy which comes handiest in the specific occasion. This paper also believes that "All methods are best!" However, the present situation in Korea seems to draw a conclusion on the foreign language education as a reading skill is most desirable. Reading materials must indeed be ones which cover all the aspects of the foreign culture in question and must also be such day-by-day reading materials as newspapers, magezines, and everyday documents. This paper eventually tries to make suggestions that; (1) the foreign language education should be extended over the full-four-year period of time with five to ten hours of the foreign language class a week; (2) only the elites should be admitted to the foreign language class who are to be screened by tests of aptitude, intelligence, motivation, and attitude; (3) the size of a class should not exceed the limit of ten students; (4) the text book should not be limited to a book, though it encloses every items of a culture, but be flexible to permit other every day reading materials come into the class; (5) language laboratory should be exploited; (6) a bilingual education is strongly recommended. This paper also gives way to textbook developers and teachers in the classrooms as to the efforts and merits of materializing and realizing the ideas enumerated here.

Phenylmercuric-8-oxyquinolinate의 土壤透過力에 對하여

徐鎔澤 全南大學校 農漁村開發硏究所 1965 農業科學技術硏究 Vol.3 No.-

Phenylmercuric-8-oxyquinolinate, known to have superior fungicidal action to P.M.A. by writer was studed whether it can be a good soil fungicide or not. Good soil fungicide should permeate well into the soil layer and should not decompose in the soil layer. Permeability and degree of decomposition of the chemicals in the soil layer, using Cochliobolus Miyabeanus was studed and the results are as follow. 1. P.M.Q. was more tightly absorbed than P.M.A. in the soil particles. 2. P.M.A. was decomposed well than P.M.Q. in the soil. 3. From above results, P.M.Q. is thought not to be a good soil fungicide.

Kasugamycin이 稻熱病菌 菌絲의 glucose 吸收에 미치는 影響

徐鎔澤 全南大學校 農漁村開發硏究所 1970 農業科學技術硏究 Vol.5 No.-

Kasagamycin이 稻熱病菌菌絲의 glucose의 吸收에 미치는 影響 및 菌體內의 70% Ethanol 不溶性 polysaccharide의 含量을 조사하였으며 그 結果를 要約하면 다음과 같다. 1) 藥劑의 濃度가 증가함에 따라 glucose의 吸收量이 감소되었다. 2) 藥劑의 濃度가 증가함에 따라 體內의 70% Ethanol 不溶性 polysaccharide의 含量이 減少되었다. 3) 以上의 結果로서 Kasugamycin이 稻熱病菌菌絲의 glucose의 吸收沮害 및 菌體內에서의 polysaccharide의 合成은 沮害시키는 것으로 豫想된다 The effects of Ksaugamycin on the glucose uptake by the mycellia of piricularia oryzae and on the content of 70% Ethanol insoluble polysaccharide in the mycellia of P. oryzae were studied and the results are summarized as follow. 1. The uptake of glucose was decreased as the cncentration of chemicals increased. 2. The content of 70% Ethanol insoluble polysaccharide was decreased as the concentration of chemicals increased. 3. From above results, it is thought the glucose uptake and the synthesis of polysaccharide in the P. oryzae are inhibited.

강도별 운동 전·후 혈청 LDH, 및 CK의 활성도 변화

임용택,송분도,이충영,박명수 한국스포츠리서치 2005 한국 스포츠 리서치 Vol.16 No.2

The purpose of this study was to investigate the changes of Creatine Kinase(CK) and Lactate Dehydrogenase(LDH) activity following different exercise intensities. Each subject(N=G) performed 30min's running with different exercise intensities- 10% VO₂max, 60%VO₂max, 80VO₂max - using treadmill. To measure the blood concentration of CK and LDH, we collected blood three times - pre-exercise, post-exercise and 30min after cessation of exercise. Using this experimental method. following results were obtained; First, There was significant difference between pre- and post-exercise CK concentration in 40%VO₂max exercise group and 60%VO₂max exercise group(p<.05), but no significant difference in 80%VO₂max exercise group. Second, There was no significant difference between pre- and post-exercise LDH concentration in 40%VO₂max exercise group and 60%VO₂max exercise group. but significant difference in 80%VO₂max exercise group. This result suggested that the concentration of CK and LDH following exercise depend on exercise intensities.

Silicone-pyridine에 대한 Chlorophyll-a와 -b의 혼합착물의 형광연구(Ⅳ)

박면용,박택규,정구춘 建國大學校基礎科學硏究所 1987 理學論集 Vol.12 No.-

클로필-a와 -b를 혼합물의 상태로 1:2, 1:4, 1:6의 polydimethylethylsilane(0-2 -pyridylethyl methylsilane)에 Mg-pyridine 착물로 디에틸에테르중에서 결합시키고 중합체 사슬을 통한 에너지 이동을 연구하였다. Chl-b에 대한 Chl-a의 첨가량이 증가할수록 Chl-a의 혼합비(5:1, 3:1, 1:1)에 따라 형광수득율이 증가하였다. 반대로 Chl-b가 Chl-a에 비하여 첨가량이 증가할수록 형광수득율이 감소하였다. 최대 형광세기는 Chl-a와 Chl-b에 대하여 결합한 pyridine의 당량농도에서 나타났다. Chl-a에 의하여 흡수된 에너지는 중합체의 사슬을 통하여 Chl-b로 이동하였고 그 이동경향은 dimer>tetramer>hexamer의 순서로 증가하였다. The chlorophyll-a and -b have been bound 1:2, 1:4 and 1:6 polydimethyl ethyl silane(0-2-pyridylehylmethylsilane) as the mixed state to form the complex compound of Mg atom on chlorophyll and pyridine on the polymer in diethyl ether, and studied about the energy migration through the polymer chain in the same solvent. The more chl-a were added to chl-b the more increased fluorescence yields of chl-b were shown it to match for the mixed ratios of chl-a: chl-b in the order of 5:1, 3:1 and 1:1, while chl-a was shown the more decreased fluorescence yields according as the more chl-b were added. The maximum fluorescence intensity were appeared at equivalent pyridine concentration bound to the chl-a and -b. The absorbed energy by chl-a were transfered to chl-b through the chain, and the migration tendencies were on the increase of dimer>tetramer>hexamer.