Effect of Ti Addition on the Microstructure and High-Temperature Oxidation Property of AlCoCrFeNi High-Entropy Alloy

Gi‑Su Ham,Young‑Kyun Kim,Young Sang Na,Kee‑Ahn Lee 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.1

This study investigated the effect of Ti addition on microstructure and high-temperature oxidation property of AlCoCrFeNihigh-entropy alloy. Ti content was controlled at 0 at% and 1 at%. The two alloys were found to have BCC single phase, andthe average grain sizes of Ti0.0 and Ti1.0 were 47.3 μm and 49.7 μm, respectively, showing similarity. The EDS mappingof the inside of grains found that both alloys were characterized to be divided into Al-Ni element rich region and Cr–Feelement rich region. As a result of high-temperature oxidation test at 1100 °C, oxidation weight gains were measured atTi0.0: 0.75 mg/cm2 and Ti1.0: 0.17 mg/cm2, respectively. The results indicate that Ti addition largely improved high temperatureoxidation resistance of AlCoCrFeNi HEA. Ti1.0 alloy, in particular, showed remarkably more excellent 1100 °Chigh-temperature oxidation resistance than other previously reported major ones such as NiCrAl and FeCrAl. In the surfaceand cross-section observations after oxidation tests, both alloys were found to have Al2O3oxides mostly. While the Ti0.0material was observed to have Al2O3spallation macroscopically, the Ti1.0 alloy showed Al2O3spallation only in some localareas. In addition, a unique result was found in AlCoCrFeNiTix(x=0,1) alloy that BCC → FCC phase transformation was accelerated,and FCC phase layer was formed in the surficial area where Al element had been depleted due to high-temperatureoxidation. Moreover, as Ti was added, the thickness of FCC layer induced by high-temperature oxidation decreased. Basedon the results, it was also discussed on how to improve the high-temperature oxidation resistance of AlCoCrFeNiTixHEA.

황색포도상구균 신속 검출용 간이 진단키트

김기영,박샛별,문지혜,이상대,이새롬,장윤정 충남대학교 농업과학연구소 2013 농업과학연구 Vol.40 No.2

This study was performed to develop a rapid test kit for pathogenic Staphylococcus in various samples. The rapid detection kit has been fabricated based on nitrocellulose lateral-flow strip. Colloidal gold and Staphylococcus antibodies were used as a tag and a receptor, respectively. Manually spotted Staphylococcus antibody and anti-mouse antibody on the surface of nitrocellulose membrane were used as test and control lines, espectively. Feasibility of the rapid kit to detect Staphylococcus aureus in samples were evaluated. The intensity of the color of the tes line started to increase with the samples in which higher concentration of the cells were contained. The sensitivity of the sensor was 106 cfu/mL Staphylococcus spiked in PBS. Also, the rapid test kit could detect 105 cfu/mL of Staphylococcus in chicken meat extract.

간세포성 암종과 담관암종에서 Glutathione S-Transferase π의 면역조직화학적 발현

한상영,손영기,이종훈,박희승,노명환,최석렬,최홍조,허기영 大韓消化器病學會 1998 大韓消化器病學會誌 Vol.31 No.1

근골격계 질환에 있어 초음파 검사의 유용성

박기영,김현리,이성문 大韓再活醫學會 2000 Annals of Rehabilitation Medicine Vol.24 No.6

Ad-Hoc 네트워크에서 링크 장애를 고려한 효율적인 키 협정 방법

이영준,민성기,이성준 한국컴퓨터교육학회 2004 컴퓨터교육학회 논문지 Vol.7 No.1

Ad-Hoc네트워크에서는 기존의 인프라를 사용하지 않기 때문에 공개 키 기반 구조 또는 제삼자 키 관리 서비스를 지원하지 않는다. 따라서 여러 유형의 보안문제가 발생할 수 있다. 그래서 보안 문제를 해결하기 위한 방법인 키 협정(key agreement)에 대하여 많은 프로토콜들이 제안되어 왔다. 가장 대표적인 것이 디피 헬만(Diffie-Hellman)이 제안한 프로토콜이다. 그러나 이 방법은 두명의 사용자간에서만 사용될 수 있다. 이 논문에서는 디피 헬만 방법을 확장하여 다자간에도 사용될 수 있는, 그룹 키 협정에 대하여 알아보고, 그룹 키 협정 진행 중에 링크 장애가 발생했을 때 그룹 키 협정을 성공적으로 수행하기 위한 효율적인 방법을 제안하였다. Ad-Hoc network is wireless network architecture without infrastructure. We encounter new types of security problems in Ad-Hoc networks because such networks have little or no support from infrastructure. Thus, wireless communications need security mechanisms in order to guarantee the integrity and the privacy of the communication, as well as the authentication of the entities involved. Many practical systems have been proposed. The most familiar system is the Diffie-Hellman key distribution system. This algorithm allows the establishment of a cryptographic secret key between two entities. If more than two users want to compute a common key, then a group key agreement system is used. This paper discusses several group key agreement systems and presents two efficient fault tolerant methods to perform successful group key agreement.

뇌혈관의 미만성 방추형 동맥류 : 1예 보고

한기석,신환식,박길선,김대영,김성진,차상훈 충북대학교 의과대학 충북대학교 의학연구소 1998 忠北醫大學術誌 Vol.8 No.2

저자들은 뇌동맥의 광범위한 확장을 보이는 희귀한 방추형 동맥류의 증례를 경험하였기에 전산화단층촬영영상과 자기공명영상 소견을 중심으로 보고하고자 한다. 49세 남자환자로 20 년전 고혈압으로 진단 받고 치료받던 환자로 현기증과 언어장애로 내원하였다. 내원 후 시행한 조영증강후 뇌 전산화 단층촬영에서 뇌저동맥, 중뇌동맥, 후뇌동맥 등이 확장되어 있고 구불구불하였으며, 확장된 뇌저동맥은 뇌교를 압박하고 있었다. 삼차원 구성기법을 이용한 전산화단층촬영 혈관조영술에서 뇌동맥이 광범위한 확장을 쉽게 이해할 수 있었다. 자기공명영상 T2강조영상에서 확장된 뇌동맥이 신호소실로 보였으며, 뇌저동맥이 뇌교를 오른쪽으로 압박하고 뇌교의 중앙부분에 뇌경색이나 허혈로 보이는 높은 신호강도를 보이는 부분이 있었다. 미만성 방추형 동맥류에 있어 전산화 단층촬영, 자기공명영상은 동맥확장의 범위와 정도를 평가하는데 도움을 주며, 혈전형성, 허혈, 주위 뇌조직의 압박 등의 소견을 잘 보여준다 Authors report a case of diffuse fusiform aneurysm of cerebral arteries, focusing findings of CT and MRI. A 49 year old male suffered by hypertension was presented by dysarthria, right hand tingling sensation and dizziness. Contrast media enhanced CT images showed markedly dilated and tortuous basilar artery and middle, posterior cerebral arteries. The location and extent of arterial dilatation was well depicted by CT angiogram. On T2 weighted MR image, dilated arteries were depicted as signal void and the compressed pons by dilated basilar artery and adjacent ischemic changes were also well depicted. CT and MRI are excellent imaging modality in the evaluation of extent and degree of diffuse fusiform aneurysm of cerebral arteries.

토양침식량 산정에서 토양도 축척에 따른 적정 해상도 분석에 관한 연구

이근상,장영률,조기성 한국지리정보학회 2003 한국지리정보학회지 Vol.6 No.3

최근 수정범용토양유실공식을 활용한 토양침식 연구가 활발히 진행중에 있으나, 실측자료와의 비교가 어렵기 때문에 계산된 결과를 정량적으로 검증하지는 못하였다. 본 연구에서는 RUSLE 모형을 구성하고 있는 인자들을 GIS 격자분석기법으로 분석하였으며, 특히 1:250,000 개략토양도를 주로 활용하였던 기존의 연구와 달리 1:25,000 정밀토양도를 활용한 토양침식인자를 제시하였다. 그리고 RUSLE 모형으로 계산한 토양침식량의 검증을 위해 보성강 유역의 비퇴사량 실측자료를 이용하였으며, 토양도의 축척을 고려한 결과 1:250,000 개략토양도의 경우는 120m의 해상도가 적합한 것으로 평가되었고 1:25,000 정밀토양도를 고려한 경우는 150m 해상도가 적합한 것으로 평가되었다. RUSLE(revised universal soil loss equation) has been widely used for estimating soil loss. It is very difficult to validate the model estimation since the calculate soil loss should be compared with the survey data for quantification. The input variables for RUSLE modle were estimated to grid cell for raster analysis in Bosung basin. Both reconnaissance(1:250,000) and detailed(1:25,000) soil maps were used to derive the input variables for soil erodibility factor. Soil loss calculated using RUSLE were compared to the unit sediment deposit surveyed by KICT(Korea Institute of Construction Technology, 1992) in Bosung basin for assessment. Unit sediment deposit from the cell size of 120m and 150m were the closest to the survey data 1:250,000 and 1:25,000 map scale, respectively.

한국 성인에서의 후두개염의 방사선학적 진단기준

민영기,정윤석,윤상규,박인철,조준필 대한응급의학회 2000 대한응급의학회지 Vol.11 No.3

Backgrounds: A retrospective study was performed to define objective radiologic parameters in diagnosing epiglottitis on soft-tissue lateral neck radiographic study. Methods: Parameters of soft-tissue structures(epiglottis width, third vertebral body width, ratio of epiglottic width to third vertebral body width) in 30 adult patients compared with those of age and sexmatched controls with foreign body in throat whose radiographic reading was normal. Results: Epiglottis width of more than 11mm, ratio of epiglottis width(EW) to the third vertebral body width(C3W) of more than 0.5 were, respectively, found to be 100% sensitive and specific in differentiating between patients with and without epiglottitis. Conclusion: These preliminary results suggest that EW/C3W ratio of more than 0.5, EW of more than 11mm, respectively, may be useful in the diagnosis of epiglottitis in adult patients.

제주도 동남방 신천해안역 해수의 이화학적 특성과 저질분포

최영찬,고기원,김상현 제주대학교 해양연구소 1987 해양자원연구소연구보고 Vol.11 No.-

산소과급 시스템을 이용한 대형디젤기관의 연소 및 유동특성 예측에 관한 연구

한영출,백두성,오상기 국민대학교 생산기술연구소 2003 공학기술논문집 Vol.26 No.-

Many diesel engine manufactures make an efforts to reduce NOx and soot emissions exhausted from engines under pressure. Also, it has been required to comply with new stringent emission standards while improving engine efficiencies. The optimized oxygen enrichment level has been studied as well as a retardation of injection timing and a swirl ratio. Based on this parameter study, a numerical simulation has been conducted to analyze a heavy-duty diesel engine combustion in multidimensional models. A reduced chemistry approach is applied by using computational fluid dynamics techniques. The models under current development are incorporated into KIVA-3V code for validation. As a result, combustion and inside flow characteristics have been well predicted by suggesting various engine parameters and optimal condition.