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.

태양 추적 장치를 갖는 집광 시스템의 집열 특성

이용훈,최석천,지명국,이상철,정효민,정한식 경상대학교 해양산업연구소 2002 해양산업연구소보 Vol.15 No.-

The purpose of this research is to obtain the heat transfer characteristics of the absorber type solar collector. This new system moving by time and degree. The second system had the solar tracking system. The x-y axis were designed at intervals of 0.33˚/min and 0.16˚/min respectively. In this system the absorber specification was 1OOLX80Φ1.4t. This experiment was conducted from July to August. 2002. The temperature of solar collector was reached about mean temperature 250℃.

인공 치아우식 발생 모델에서 디지털 방사선 공제술을 이용한 인접면 치아우식증의 진단

박정훈,최용석,황의환,이기자,최삼진,박영호,김경숙,진현석,홍경원,오범석,박헌국 대한구강악안면방사선학회 2009 Imaging Science in Dentistry Vol.39 No.1

Purpose : The purpose of the experiment was to evaluating the diagnostic ability of dental caries detection using digital subtraction in the artificial caries activity model. Materials and Methods : Digital radiographies of five teeth with 8 proximal surfaces were obtained by CCD sensor (Kodak RVG 6100 using a size #2). The digital radiographic images and subtraction images from artificial proximal caries were examined and interpreted. In this study, we proposed novel caries detection method which could diagnose the dental proximal caries from single digital radiographic image. Results : In artificial caries activity model, the range of lesional depth was 572-1,374 μm and the range of lesional area was 36.95-138.52mm². The lesional depth and the area were significantly increased with demineralization time (p<0.001). Furthermore, the proximal caries detection using digital subtraction radiography showed high detection rate compared to the proximal caries examination using simple digital radiograph. Conclusion : The results demonstrated that the digital subtraction radiography from single radiographic image of artificial caries was highly efficient in the detection of dental caries compared to the data from simple digital radiograph.

비정형 향정신병약물을 투여 중인 정신분열병 환자의 주관적 삶의 질 : 정신병리, 약물 부작용 및 약물에 대한 주관적 반응과의 관련성

김종훈,윤정희,이자영,노경희,홍성극,윤세창,강웅구,김용식 大韓神經精神醫學會 2003 신경정신의학 Vol.42 No.2

Objectives : The purpose of this study was to evaluate the characteristics of psychopathology, adverse drug effects, and Subjective response to drugs that have a significant impact on the subjective quality of life in schizophrenic patients receiving atypical antipsychotics. Methods : One hundred and one schizophrenic patients, who were receiving maintenance treatment with atypical antipsychotics, were evaluated. Subjective quality of life was assessed using the standardized Korean modification of a self-rating scale to measure subjective well-being under neuroleptics (KmSWN). Patients' psychopathology was evaluated using the Positive and Negative Syndrome Scale. Adverse effects and subjective response to drug were evaluated using the Liverpool University Neuroleptic Side Effect Rating Scale and the Drug Attitude Inventory-10, respectively. Correlation analysis and stepwise multiple regression analysis were conducted. Results : In psychopathology, the severity of depression and anxiety showed the most significant correlation with the score ofKmSWN. In adverse drug effects, the severity of psychic side effect and extrapyramidal side effect showed the most significant correlation with the score ofKmSWN. Regarding subjective response to drug, significant correlation was observed between the severity of subjective negative response and the score of KmSWN. Stepwise multiple regression analysis revealed that psychic side effect, extrapyramidal side effect, and depression contributed significantly to the total score of KmSWN. These variables accounted for 59.7% of the total variance. Conclusion : The results of the present study suggest that psychic side effect, extrapyramidal side effect and depressive symptom are the clinical characteristics that are significantly associated with the subjective quality of life. An effective management strategy for these variables should be established in developing a treatment program to enhance the quality of life of patients with schizophrenia.

위암 환자에서 세포성 면역 기능에 관한 연구

이재익,윤일국,이종선,김종완,장준,안정기,송민호,정현용,이헌영,김삼용,김영건 충남대학교 암연구소 1991 癌共同硏究所 硏究誌 Vol.1 No.1

We performed a variety of lymphocyte stimulation tests, delayed hypersensitivity skin tests, and enumeration of several lymphocyte subpopulations in 21 patients with gastric cancer who did not receive any form of anticancer therapy, and in 20 healthy controls. The gastric cancer patients had significantly decreased number and total score of positive reactions in delayed hypersensitivity skin tests compared with the healthy controls. The percent of CD_(4) positive lymphocytes in the gastric cancer patients was significantly decreased compared to the normal control subjects, but it had no correlation with the total score of delayed cutaneous hypersensitivity reactions. The ratio of helper to suppressor cells was lower in the cancer group. The uptake of 3H-thymidine was markedly depressed in cancer patients when stimulated with various mitogens. There was little correlation between any of the stimulation tests and any of the lymphocyte subpopulation proportions to delayed hypersensitivity cutaneous reactions. Optimal proliferative response was found in lymphocytes stimulated with 10 micrograms of concanavalin-A and 10 microgram of phytohemagglutinin. Advanced stage patients had greatly depressed delayed hypersensitivity skin reactions and proliferative responses to mitogens compared with localized diseases. These results suggest that gastric cancer patients have depressed cellular immune functions, which mainly result from the decreased helper cells and defects in functional proliferative response to mitogens. Interleukin-2 and interferon-gamma restored the in vitro proliferative response of lymphocyte in patients with gastric cancer.

과학자에 대한 초등학교 일반 학생과 과학 영재반 학생의 인식 비교 분석

김소형,박재일,정진수,이혜정,권용주,박국태 한국초등과학교육학회 2005 초등과학교육 Vol.24 No.1

This study was designed to compare the understanding of ordinary elementary school students and scientifically gifted students about scientists. 473 fourth, fifth, and sixth graders in ordinary elementary schools and 40 students attending scientific educational institutions for the gifted were studied with the help of questionnaires and interviews. The survey showed that there were no significant differences between the two subject groups in relation to the external images of scientists. The subjects turned out to have four fixed external images. The scientifically gifted students had a better understanding of the internal images of scientists than ordinary elementary school students. Both the subject groups turned out to be influenced by the press media and off-campus education, thinking that scientists served as inventors producing something useful in daily life rather than as researchers studying natural phenomena or laws. It was found out that both groups admired Edison. The ordinary students respected Einstein and Jang Yeong-Sil whereas the scientifically gifted students respected Curie, Jang Yeong-Sil, and Nobel. The subjects admired them because of their achievements instead of their backgrounds or individual characteristics.

마우스에서 고려홍삼 추출물의 단회 및 반복투여독성 평가

임숙희, 신선희, 장자영, 변상국, 이예은, 박동선, 전정희, 이용경, 이동만, 이세라, 김재승, 황방연, 노재섭, 남상윤, 윤영원, 김윤배 충북대학교 동물의학연구소 2005 Journal of Biomedical and Translational Research Vol.6 No.2

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방사선사진의 인덱스-순서 분석을 통한 치아경조직의 탈염화 검출

박동현,박영호,김경숙,박정훈,이기자,최삼진,최용석,황의환,박헌국 대한구강악안면방사선학회 2009 Imaging Science in Dentistry Vol.39 No.2

Purpose : The purpose of this study was to develop the radiographic technique for detecting the demineralization which is known as indication of dental caries. Materials and Methods : This technique was based on the comparing of multiple radiographs which was irradiated by multiple X-ray spectra. For the meaningful comparing, the multiple radiographs were reconstructed to the dosimetrically consistent images using a standard material. The difference of resulting images of same target with multiple spectra represents the difference of response of material as regards the spectra. Results : We have found about 10% of demineralization of dental hard tissues particularly in the proximal region through the analyzing of differences. Conclusion : Most intriguing thing in this investigation was that the method to analyze difference shows us to an anatomic structure of dental hard tissues even if absolute values of optical density were excluded during the procedures.

Shipyard Block Logistics Simulation Using Process-centric Discrete Event Simulation Method

Jeong, Yong-Kuk,Lee, Philippe,Woo, Jong Hun The Society of Naval Architects and Marine Enginee 2018 Journal of ship production and design Vol.34 No.2

An outbreak of avian influenza subtype H9N8 among chickens in South Korea

Kuk Kwon, Yong,Jeong Lee, Youn,Gu Choi, Jun,Kyoung Lee, Eun,Jin Jeon, Woo,Mi Jeong, Ok,Chul Kim, Min,Joon Joh, Seong,Hun Kwon, Jun,Hong Kim, Jae World Veterinary Poultry Association 2006 Avian pathology Vol.35 No.6

<P>Low pathogenic avian influenza subtype H9N8 was diagnosed on a Korean native chicken farm in Gyeonggi province, South Korea, in late April 2004. Clinical signs included moderate respiratory distress, depression, mild diarrhoea, loss of appetite and a slightly elevated mortality (1.4% in 5 days). Pathologically, mucopurulent tracheitis and air sacculitis were prominently found with urate renal deposition. The isolated A/chicken/Kr/164/04 (H9N8) had an Ala-Ser-Gly-Arg (A/S/G/R) motif at the cleavage site of haemagglutinin, which has been commonly found in H9N2 isolated from Korean poultry. Phylogenetic analysis of the haemagglutinin and neuraminidase genes of the H9N8 avian influenza virus (AIV) isolate showed that reassortment had occurred. Its haemagglutinin gene was similar to that of Korean H9N2 AIVs, but its neuraminidase gene was closely related to that of A/WBF/Kr/KCA16/03 (H3N8) isolated from the faeces of wild birds in Korea. The pathogenicity of the isolate was tested on 6-week-old specific pathogen free chickens. The inoculated virus (H9N8) was recovered from most tested organs, including the trachea, lung, kidney, spleen, and caecal tonsil. This is the first report of an outbreak of low pathogenic avian influenza in chickens caused by AIV subtype H9N8.</P><P>Un cas d'influenza aviaire faiblement pathogène (LPAI) de sous type H9N8 a été diagnostiqué dans une ferme de poulets indigènes, dans la province de Gyeonggi, en Corée du Sud, en Avril 2004. Les symptômes consistaient en une détresse respiratoire modérée, une diarrhée peu importante, une perte d'appétit et une mortalité légèrement élevée (1,4% en 5 jours). Sur le plan pathologique, une trachéite mucopurulente et une aérosacculite ont été les lésions les plus souvent observées avec un dépôt d'urate au niveau des reins. La souche isolée A/chicken/Kr/164/04 (H9N8) présentait un motif Ala-Ser-Gly-Arg (A/S/G/R) au niveau du site de clivage de l'hémagglutinine (HA) qui a souvent été observé chez les souches H9N2 isolées de volailles en Corée. L'analyse phylogénétique des gènes de HA et de la neuraminidase (NA) de la souche de virus de l'influenza aviaire (AIV) H9N8 a montré qu'il s'était produit un réassortiment. Son gène HA était similaire à celui des AIVs coréens H9N2, mais son gène NA était très proche de celui de la souche A/WBF/Kr/KCA16/03 (H3N8) isolée de fèces d'oiseaux sauvage en Corée. La pathogénicité de l'isolat a été testée chez des poulets exempts de microorganismes pathogènes spécifiés âgés de 6 semaines. Le virus inoculé (H9N8) a été réisolé de la plupart des organes testés incluant la trachée, les poumons, les reins, la rate et les amygdales cæcales. C'est le premier rapport d'un cas de LPAI chez des poulets causé par un AIV de sous type H9N8.</P><P>Im späten April 2004 wurde auf einer koreanischen Farm mit einheimischen Hühnern in der Gyeonggi-Provinz ein schwach pathogenes aviäres Influenzavirus (LPAI) Subtyp H9N8 isoliert. Die klinischen Symptome umfassten geringe Atembeschwerden, Störung des Allgemeinbefindens, milde Diarrhoe, Appetitlosigkeit und eine geringfügig erhöhte Mortalität (1,4 % in 5 Tagen). Pathologisch-anatomisch wurden als herausragende Veränderungen eine mukopurulente Tracheitis und Aerosacculitis sowie renale Harnsäureablagerungen gefunden. Das Isolat A/chicken/Kr/164/04 (H9N8) besaß ein Ala-Ser-Gly-Arg (A/S/G/R)-Motiv an der Spaltstelle des Hämagglutinins (HA), das auch üblicherweise bei den aus Geflüg