Effects of I- and W-Phases Under Identical Conditions on Microstructure and Mechanical Properties of As-Cast Mg–Zn–Y Alloys at Room and Elevated Temperatures

Young‑Gil Jung,Wonseok Yang,Jae Ik Hyun,Shae K. Kim,Hyunkyu Lim,Do Hyang Kim 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.12

Three alloys (Mg–6Zn–1.2Y, Alloy I; Mg–3.65Zn–1.65Y, Alloy II; and Mg–4.3Zn–1.4Y, Alloy III) with same volume fractionand grain size were designed to evaluate the effects of the I-phase (Mg3Zn6Y) and W-phase (Mg3Zn3Y2), which are themajor phases in Mg–Zn–Y alloys, on the mechanical properties. The tensile strength of Alloy I with the I-phase at roomtemperature was the highest among the tested alloys because the coherent interface between the I-phase and the α-Mg phasewas more resistant to cracking than the incoherent interface between the W-phase and the α-Mg phase. A cross-sectionalmicrostructure analysis of a sample that was tensile-tested at 423 K revealed that the morphology of the I-phase remainedrelatively stable. In contrast, the W-phase was broken and fragmented during the tensile test at 423 K because it had higherbrittleness under the test conditions. Therefore, the tensile and creep properties of Alloy I at 423 K were better than thoseof Alloys II and III containing the W-phase. According to the results, the I-phase in the Mg-Zn-Y alloy was more beneficialto the mechanical properties at room temperature and 423 K than the W-phase.

주편 연속주조시 Thermal Soft Reduction 적용에 의한 중심 편석 개선

정영진,김지준,김선구,강충길 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.11

Centerline macrosegregation is one of the most significant problems in continuous casting on stainless steel slabs. Numerical model have been developed in order to decrease centerline macrosegregation during continuous casting of STS 420J2 stainless steel slab. Extra cooling zone and extra cooling water quantity are determined by iterative coupled analysis of heat transfer and segregation. Segregation ratio is decreased by the intensive cooling at the extra cooling zone above the solid fraction of the slab center 0.7, so called thermal soft reduction (TSR). The experimental results show good agreements with numerical results.

고소성 해성점토지반의 압축지수에 대한 비교 연구

정길수,박병수,홍영길,유남재 江原大學校 産業技術硏究所 2005 産業技術硏究 Vol.25 No.A

In this paper, for the highly plastic marine soft clay distributed in west and southern coast of Korean peninsula of Kwangyang and Busan New Port areas, correlation between compression index and other indices representing geotechnical engineering properties such as liquid limit, void ratio and natural water content were analyzed. Appropriate empirical equations of being able to estimate the compressibility of clays in the specific areas were proposed and compared with other existing empirical ones. For analyses of the data and test results, data for marine clays were used from areas of the South Container Port of the Busan New Port, East Breakwater, Passenger Quay, Jungma Reclamation and Reclamation Containment in the 3rd stage in Kwangyang. In order to find the best regression model by using the commercially available software, MS EXCEL 2000, results obtained from the simple linear regression analysis, using the values of liquid limit, initial void ratio and natural water content as independent variables, were compared with the existing empirical equations. Multiple linear regression was also performed to find the best fit regression curves for compression index and other soil properties by combining those independent variables. On the other hands, another software of SPSS for non-linear regression was used to analyze the correlations between compression index and other soil properties.

부산광역시 일부하천의 계절적·년도별 수질특성 비교분석

정유진,문종익,성낙창,김부길,이영형 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.1

This study is carried out to investigate the water quality change trends in Pusan Metropolitan streams. The temperature of the streams are moderate except in winter period and this can be explained by the Korean meterological characteristics. The pH does not vary by the time but some points are a little low. BOD_(5) and COD_(Mn), the index of water contaminants, be shown as characteristic domestic waste water patterns. The nutrient matters, such as total nitrogen and total phosphate, are appeared to be low. The chronic water quality, as BOD_(5) and COD_(Mn), shows that the loading rates in 1998 are smaller than the past(1983, 1992). Some points show a little high loading in autumn, but this needs more investigation to make clear the cause(s).

서키트 웨이트트레이닝 운동이 혈중지질 및 지단백 콜레스테롤에 미치는 영향

정성림,김영길 창원대학교 체육과학연구소 1998 경남 체육연구 Vol.3 No.1

본 연구는 서키트 웨이트트레이닝이 혈중 지질 및 지단백 콜레스테롤 농도에 미치는 영향을 알아보기 위하여 C대학교 학생(10)명을 대상으로 주당 4일간 1일 60분씩 총 8주간 서키트 웨이트 트레이닝을 실시한 결과 다음과 같은 결론을 얻었다. 1) 총-콜레스테롤(T-cholesterol)은 서키트 웨이트트레이닝 전·후간에 통계적으로 유의한 차이가 나타났다. 2) 고밀도 지단백(HDL-Cholesterol)은 서키트 웨이트트레이닝 전·후간에 통계적으로 유의한 차 이가 없는 것으로 나타났다. 3) 중성지방(Triglyceride)은 서키트 웨이트트레이닝 전·후간에 통계적으로 유의한 차이가 없는 것으로 나타났다. 일반적으로 운동선수들의 체력향상을 위해 이용되어 왔던 서키트 웨이트트레이닝에 대한 관심이 최근에 들어 CWT의 효과가 일반인에게도 알려지면서 일반인에게도 건강관리 방법의 하나로 많이 이용되고 있다. 특히 규칙적인 서키트 웨이트트레이닝으로 관상동맥질환의 주요 원인이 되는 혈중 콜레스테롤의 농도를 감소시키는 것으로 나타남으로써 일반인 특히 40대이후의 성인병환자들에게 적극 권장될 수 있는 운동종목의 하나로 판단 되어진다.

해양레저스포츠 활성화에 관한 연구

정명수,백승헌,황영길 朝鮮大學校 스포츠科學硏究所 2004 스포츠科學硏究 Vol.15 No.-

With carrying out a five-day work week, workers need to use their leisure time more efficiently. The purpose of this study was to vitalize marine leisure sports by providing virtual and effective materials of marine leisure sports. To do this, this study presented the present state of marine leisure sports, favorite events, the forms of participation, the factors of impediment, satisfaction, and methods for vitalizing according to the nature of sociology of population. The subjects of this study were 400 respondents who resided in G metropolitan city and C province and had experienced marine sports. They were given questionnaires and the followings were obtained. 1. The most favorite event in marine sports was scuba diving, followed by water skiing and windsurfing. 2. In the forms of participation, people moved using a car for two or less days in legal holidays or vacations. For 3-4 days accommodation, a hotel, a guesthouse, and a condominium were preferred most. A female group went with their family and a male group went with friends or seniors and juniors in school. 3. In the factors of impeding mahne leisure sports, the age and academic background group responded expense, time, safety accidents, and location, while the income group answered expense and location. There were no factors of impediment in the sex group. 4. In the satisfaction in participation in marine leisure sports, the sex and age group had high satisfactory in all factors such as program, transportation, facilities, and information. While the academic background group was satisfied with transportation and information, the income group was satisfied with program and facilities. 5. In the methods of vitalizing marine leisure sports, the sex, age, and academic background group indicated investing in facilities, developing new programs, Providing marine leisure sports-related information, and training professional coaches. The income group answered investing in facilities, providing information, and training professional coaches except developing new programs.

폐전선 피복재 건류탄을 이용한 제강분진처리를 위한 기초연구

황용길,이상화,이성룡,정석수,최재신,조충형 東亞大學校 1995 東亞論叢 Vol.32 No.-

Distilled carbon from waste electric wire coated by vinyl is used to recover valuable metal such zinc, lead and iron in dust. Pemeability and compressive tests are who done to present basic data on extraction of zinc in dust. Experimental results obtained from sintering property of steelmaking dust, distilled carbon from waste electric wire coated by vinyl and waste pulp sludge mixture briquet at various sintering temperature are as followings; Permeability is increased as increasing distilled carbon and pulp amount at higher temperature than room temperature condition. Compressive strength at room temperature is increased as increasing distilled carbon and decreasing waste pulp amount, but decreased as increasing temperature and waste pulp amount. Weight Loss reaction experiment is increased a increasing distilled carbon and waste pulp amount. ZnO and Fe₃O₄ are obtained from sample containing ZnO, Fe₂O₃ and ZnO at 800℃. Permeability test at 500℃ and 800℃ did not well, because of 13.3% CaO in distilled carbon. Sample because semmi melted state at 1000℃. Distilled carbon obtained from waste electric wire showed effect of reduction and flux material.

방위특징 탐지 단순신경세포들의 배열순서에 관한 연구

김길중,김정국,서광명,서용수 동서대학교부설연구소 1998 연구소 논문집 Vol.3 No.-

Cells in avisual cortex line in columns which are perpendicular to the cortical surface and the cortical cells in a column prefer to respond to an orientation of each line segments of an sesory image. orientation preference of each cortical column is highly correlated to those of nearbycolumns and varies smoothly anlong the surface of the cortex. To elucidate the mechanism of this columnar organization, we propose a simple model consisting of orientation selective neruons(OSNs) with local facilitation and lateral inhibition. it is playsible that modifiable connections play an important role in forming and refining the organization togher with the sensory experience. Thus the feed-forward connections between OSNs and LGN cells are modifiable. The interactions between OSNs in the same layer take place by way of feedback pathways and are excitatory and inhibitory. The behavior of the model is described by a STM equations of Growwberg and critical parameter of negative one dimensional ??G function, σ would give variety to the differences in detected orientations.

에타놀 섭취 후 두부 상하위시 혈역학적 변화

김지영,김형진,홍정길 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.1

냉기 치료에 따른 둔근에서의 피부 및 근육내 온도 변화

정우성,김미정,박시복,이상건,김영호,양길태,장윤희 大韓再活醫學會 1998 Annals of Rehabilitation Medicine Vol.22 No.2