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.

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.

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).

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.

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

알코올 의존 환자에서 갈근이 혈중 알코올 농도와 음주 효과에 미치는 영향

김명정,정영인,박제민,김성곤,최영길 大韓神經精神醫學會 1996 신경정신의학 Vol.35 No.6

갈근의 장기 투여가 혈중 알코올 농도와 음주 효과에 미치는 영향을 알아 보기 위하여 알코올 의존으로 입원하여 급성 알코올 중독과 금단 증상에서 회복된 남자 환자를 대상으로 갈근 투여군과 대조약 투여군으로 나누어 갈근과 대조약을 4주간 투여하였다. 갈근 혹은 대조약 투여 전후에 우울과 불안을 측정하고, 알코올 함량이 25%인 소주를 체중 kg당 ml를 음주하게 한 후 음주 전, 음주 후 10, 30, 60, 90, 120분에 각각 혈중 알코올 농도와 음주 효과를 측정하고 4주 동안의 일일 음식 섭취량을 측정하여 다음과 같은 결과를 얻었다. 1) 갈근 투여 전후 사이 그리고 실험군과 대조군 사이에 음주 후 혈중 알코올 농도에 유의한 차이가 없었다. 2) 갈근 투여 전에 비하여 투여 후에 음주 후 수축기 혈압은 음주 후 10, 30, 60, 90분에 그리고 이완기 혈압은 음주 후 10, 30, 60, 90, 120분에서 유의하게 낮았다. 갈근 투여 전의 수축기 혈압은 음주 후 10분에서 그리고 이완기 혈압은 음주 후 10, 30, 60분에서 음주 전에 비해 유의하게 상승하였으나 갈근 투여 후에는 알코올에 의한 위의 혈압 상승 효과가 차단되었다. 3) 갈근 투여 전에 비하여 투여 후에 운동량은 음주 60, 90분에서 유의하게 낮았고 목소리는 음주 후 10, 30, 60, 90분에서 유의하게 작았다. 갈근 투여 전의 운동량은 음주 후 10분부터 음주 전에 비하여 유의하게 상승하였으나 갈근 투여 후의 운동량은 음주 후 60분부터 유의하게 상승하여 알코올에 의한 상승 효과가 지연되었다. 4) 우울과 불안은 갈근 투여 전과 위약 투여 전 그리고 갈근 투여 후와 대조약 투여 후 간에는 유의한 차이가 없었다. 5) 음식 섭취량은 갈근 투여군과 대조약 투여군 모두에서 실험 기간 동안 유의한 변화가 없었다. Effect of radix puerariae on blood alcohol concentration and on alcohol effect in alcoholic patients was studied. The subjects were 57 hospitalized male alcoholics recovered from acute intoxication and withdrawal symptoms. They were divided into two groups of 29 subjects of experimental group and 28 control group. The experimental group was adminitrered with 10g/day of powder of radix puerarize and the control group with mixture of 4g/day of radix glycyrrhizae and 6g/day of flour for 4 weeks, respectively. Before and after treatment of the drugs, blood alcohol concentration, vital signs, and mania rating scale were measured at -5, 10, 30, 60, 90 and 120 minutes after administration of 25% alcohol at a dose of 6ml/kg b.w.p.o. The results were as follows: 1) Blood alcohol concentration was not changed by four weeks of radix puerariae treatment and no difference in the blood alcohol concentration was noted between the radix puerariae and the control groups. 2) Radix puerariae significantly lowered systolic blood pressures at 10, 30, 60 and 90 minutes after alcohol intake and diastolic blood pressures at 10, 30, 60, 90 and 120 minutes after alcohol intake as compared to the corresponding pre-treatment levels. Moreover, before radix puerariae treatment, alcohol-induced elevation of systolic blood pressure was significant at 10 minutes after alcohol intake and that of diastolic blood pressure was significant at 10, 30 and 60 minutes after alcohol intake. But after radix puerariae treatment, such elevation was abolished. 3) Radix puerariae reduced significantly levels of motor activity at 60 and 90 minutes after alcochol intake and levels of voice at 10, 30, 60 and 90 minutes after alcohol intake as compared to the respective pre-treatment levels. Alcohol-induced enhancement of motor activity was significantly increased from 10 minutes after alcohol intake before radix puerariae treatment. But after the drug treatment, it was significantly increased from 60 minutes after alcohol intake. Thus radix puerariae delayed the development of alcohol-induced enhancement of motor activity. 4) No significant differences were noted in the levels of anxiety and depression between the index group and the control, either before or after respective drug treatment. 5) Food intake was not changed during the experimental period in both groups.

에타놀 섭취 후 두부 상하위시 혈역학적 변화

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

출생후 흰쥐 구치의 발육에 따른 치수의 신경지배 발달에 관한 면역조직화학적 연구

김영진,남순현,배용철,김동길,김현정 大韓小兒齒科學會 1996 大韓小兒齒科學會誌 Vol.23 No.4

The purpose of this study was to investigate the postnatal development of pulpal innervation with the tooth development and eruption process in developing rat mandibular molars (postnatal 1, 5, 10, 15, 20, 25, 35day-old and adult rats). Immunohistochemical method was carried out for the detection of nerve fibers, using the antibody against calcitonin gene-related peptide(CGRP). The results were as follows: The feature of CGRP-IR nerve fibers were shown in a bead-like appearance. The time of nerve entering into the dental papilla of tooth follicle began at the occured advanced dentinogenesis. The development of Raschkow plexus began at the formative stage of the roots and was accelerated at the stage of the crown emerged into the oral cavity. The number of nerve fibers entering the odontoblastic layer increased with the tooth eruption and mastication. The development of innervation was shown to be related with the stage of the development of individual teeth rather than the chronological age of the rat.