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.

개질 아스팔트 혼합물의 변형강도 측정 연구

김광우,도영수,이기호,조문진,최선주 강원대학교 부설 석재복합신소재 제품연구센터 2004 석재연 논문집 Vol.9 No.-

본 논문은 아스팔트 혼합물의 소성변형 저항성과 상관성이 높은 특성치를 찾고자 Kim test를 개발하여 현재 적용성 연구결과를 다루고 있다. 이 논문은 새로운 강도특성치인 변형강도(S_(D))를 개발하는 Kim, test 연구의 4단계 연구 결과이다. 13 mm 골재(편마암, 화강암)와 입도(밀입도, 갭입도) 5가지 폴리머로 제조한 8가지 바인더로 두 가지 입도에서 소성변형 저항성이 다른 32가지 혼합물을 만들었다. 슬래브(305㎜×305㎜×62㎜)공시체를 제조하여 한쪽은 Kim, test를 수행하기 위하여 18 cm정도로 잘라서 코어를 3개 채취하고 다른 한쪽은 12cm크기로 하여 반복주행시험을 실시하였다. Kim, test는 하중봉 3(0.75), 4(1.0)을 사용하였다. W/T시험으로부터 최종 침하 깊이와 동적안정도의 두 가지 소성변형 계수를 각 혼합물별로 구했다. 각 하중봉과 골재별, 입도별로 S_(D)와 소성변형 계수간의 통계적 상관관계 분석을 수행한 결과 S_(D)와 소성변형 계수와의 결정계수가 매우 높게 (R²>0.95) 나타났다. 하중봉 4(1.0)이 3(0.75)보다 다소 높은 상관성을 보였다. 향후 Kim test실험에서 하중봉 4(1.0)을 사용하고 4단계 방법을 이용한다면 소성변형 특성치인 침하깊이(DR)와 동적안정도(DS)와의 상관성이 매우 큰 시험법이 될 것이다. 또한 변형강도의 파괴 메커니즘은 콘크리트의 펀칭파괴와 유사하여 콘크리트의 전단강도 추정식을 근거로 아스팔트 콘크리트의 재료 특성에 적합한 추정식 계수 ◁ 원문 수식 참조 ▷ 를 얻었다. 이 식을 이용한다면 아스팔트 콘크리트가 견딜 수 있는 임계하중을 변형강도에 근거하여 추정할 수 있을 것이다. This study shows predictability of rut parameters of modified and unmodified asphalt concretes based on the deformation strength (S_(D)) which is calculated from the maximum load, deformation and size variables of loading head under simple static loading. This paper is the result of latest studies, phase 4 which is a part of Kim, Test studies for developing a new strength property for asphalt concrete. Two aggregates, gneiss and granite, two gradations, dense-graded, gap-graded, with maximum, size of 13mm and eight binders using different contents of five polymers (RLDPE, RHDPE, LDPE, SBS, SBR) were used to produce 32 different mixtures. A slab (305㎜×305㎜×62㎜) was cut into two pieces(18cm and 12cm width) and three 10cm cores were taken for S_(D) test from the larger piece and wheel tracking test was performed on the smaller piece. Kim test was performed using loading head 4(1.0), 3(0.75). Two rut parameters, depth of rut and dynamic stability, from the rut depth-cycle curve from a WT test were obtained for each mixture. Statistical analysis were performed for each loading head, aggregate, and gradation to find out correlation between S_(D) values and each rut parameter. The analysis results showed that S_(D) had high R² (over 0.95) on the average with rut parameters. The loading head 4(1.0) showed R² better than 3(0.75). It is concluded that S_(D) is the property that has excellent predictability for rut parameter of asphalt concretes. An equation, ◁ 원문 수식 참조 ▷ was obtained based on the equation of concrete shear load creating punching failure and current test data, because the failure mechanism of S_(D) is similar to punching failure of concrete. In the equation, P is shearing force creating punching effect, b is length of perimeter of punching area and d is depth of specimen. If this formula is used, a critical load for deformation failure will be predicted based on the S_(D).

性別 및 年齡에 따른 體格과 體力의 特性과 變化에 關한 縱斷的 硏究Ⅱ : Emphasised on College Men of Department of Physical Education 體育專功 大學生을 中心으로

金尙國,姜東洹,張周鎬,金昇一,徐再均,金耕知,孫斗玉,鮮于攝,崔榮烈,尹宇相,金亨燉,方永鎭,朴英震,柳在忠 慶熙大學校 體育科學大學 1989 體育科學論叢 Vol.- No.2

The purpose of this study was to compare the characteristics, change in physique and physical function of college students majoring physical education and Taekwondo (454 males and 64 females of age groups ranging from 18 to 26). The results are as following: 1. The male group of 23yrs old in physical education showed highest values in 7 items(Weight, Chest Girth, Fore Arm Girth, Thigh Girth, Calf Girth, Scapular Skinfold Thickness and Suprailiac Skinfold Thickness). 2. In the Physical function, the male group of 18yrs old showed highest values in Power, Flexibility, and then 21yrs old at Back Strength, Vital Capacity, and 23yrs old at Grip Strength, and 25yrs old at Blood Pressure, respectively. 3. In the physique, the male group of 22yrs old showed highest values in Weight, Chest Girth, Thigh Girth, Calf Girth, and then 24yrs old Upper Arm Girth, Fore Arm Girth, and 19yrs old at Height, Upper Limb Length, respectively. 4. In Physical Function, the 22yrs old showed highest values in Back Strength, Vital Capacity, and then 23yrs old at Side Step, Trunk Extension, but 18yrs old showed lower Values in Grip Strength, Side Step, Vital Capacity and Blood Pressure. 5. The female group of 22yrs old showed highest values in 8 items(Height, Sitting Height, Waist Girth, Upper Limb Length, Lower Limb Length, Skinfold Thickness), and then 18yrs old at 5 items (Weight, Upper Arm Girth, Fore Arm Girth, Thigh Girth, Calf Girth), respectively. 6. In the physical function, the 22yrs old showed highest Values in Grip strength, Back Strength, Power, 5 Minute Run, and 18yrs old at flexibility, Harvard Step Test, respectively. 7. In the change of the physique for two years(1988-1989) in the male group, majoring Physical education the 22yrs old showed increase in 4 items, and the 20yrs old in 3 items, but 18yrs old showed decrease in 3 items. 8. In the change of the physical function for two years in the male group, the 20yrs old showed increase in 4 items, and the 21, 25, 26yrs old in 3 items, but the 19yrs old showed decrease in 6 items, and 18, 22 yrs old in 5 items, respectively. 9. The change of the physique for two years in all female group, of 18, 19, 20, 21yrs old showed increase in 11 items except Skinfold Thickness. 10. In the change of physical function for two years in female group, the 18yrs old showed increase in 3 items, and then 20yrs old in 5 items, but 19, 22yrs old decreased 12 items, respectively. 11. The highest significant difference in physique between male and female was found in weight(mean Value 17.5%), and the lowest difference was found Thigh Girth, Calf Girth(1,3%), Upper Limb Length, Lower Limb Length(2.5%). 12. The Highest difference in physical function was Strength (mean Value 40%), Vital Capacity (33%), Power(22%), but Lower Trunk Flexion, Foot Balance(3.4%). 13. In the difference of Physique and physical function between physical education major and taekwondo major, the physical education showed higher values in skinfold Thickines (mean Value 16.5%), Weight, Waist Girth(4.7%) and Strength(33%), Endurance(5.6%), but subjects majoring Taekwondo showed higher values in Flexibility and Foot Balance. 14. In all male groups, Waist Girth, Scapular Skinfold Thickness, Back Strength, Sargent Jump, Trunk Extension and Diastolic Blood Pressure were showed a significantly related at 0.001 level.

HDPE 개질 아스팔트 혼합물의 강도 및 변형특성

김광우,이기호,권오선,고태영 강원대학교 부설 석재복합신소재 제품연구센터 2004 석재연 논문집 Vol.9 No.-

본 연구는 폐비닐 펠렛을 도로포장재료로 재활용하여 자원절약 및 아스팔트 혼합물의 품질향상을 위한 연구이다. 이를 위하여 폐비닐의 첨가량별 배합설계를 수행하여 적정 폐비닐 첨가량과 최적 아스팔트 함량으로 편마암과 화강암 2가지 골재와 폐비닐인 RHDPE의 함량을 4가지로 혼합물을 제작하여 8종류의 재질 혼합물과 2종류의 무개질 혼합물을 제작하였다. 그리고 이 공시체에 대하여 마샬안정도, 간접인장강도 및 Kim test와 반복주행시험 등 실내시험을 통하여 혼합물의 특성을 분석하였다. 폐비닐 첨가량은 RHDPE가 8%일 때 안정도와 간접인장강도 모두 가장 우수한 것으로 나타났고 취성도 나타나지 않았다. RHDPE를 첨가한 혼합물에 대하여 Kim test를 수행한 결과 DR과 DS 모두 높은 상관성을 보였다. 그리고 반복주행시험에서는 RHDPE를 첨가한 혼합물이 일반 혼합물보다 우수하였다. 향후 많은 실험을 통해 RHDPE의 우수성을 입증한다면 소성변형 저항성에 우수한 재료로 이용될 수 있을 것이다. This study is a fundamental research for recycled high-density polyethylene (RHDPE) in asphalt mixture for improving roadway pavement. Marshall mix design was conducted and optimum asphalt content(OAC) was determined for dense-graded surface course mixture by RHDPE content. Marshall stability test, indirect tensile strength (ITS) test, wheel tracking trest and Kim-test were carried out to measure the characteristics of RHDPE-added asphalt concretes. From the results of this study, RHDPE in asphalt mixture if possible. It could be considered that adding too much RHDPE in asphalt mixture is not proper. The optimum content of RHDPE was appeared to be 8%. In Kim-test, statistical analysis was performed for each loading head and aggregate to find out correlation between S_(D) values and each rut parameter. The analysis result showed that S_(D) had very high coefficient of determination with rut parameters on the average.

Effect of Saline Concentrations on Biological Nitrification in Batch Reactor

Young Joon Lee, Nguyen Viet Hoang, Nguyen Hong Khanh, Pham Tuan Linh, Gi Youn Kim 조선대학교 기초과학연구원 2011 조선자연과학논문집 Vol.4 No.2

Pham Tuan Linh2 and Gi Youn Kim This study was carried out on 4 batch reactors to determine the specific ammonium oxidizing rate (SAOR), specific nitrate forming rate (SNFR) and inhibitory degree of nitrifying activities with saline concentrations. Under salt free condition ammonia was consumed during the reaction period within 200 min. When the salt level increased to 10, 20 and 30 g NaClL-1 in reactor, ammonia depletion took 250, 300 and above 350 min, respectively. During concentration above 10 g NaClL-1, there was nitrite accumulation. Also, at 30 g NaClL-1 ammonia did not depleted and NO2 --N accumulated until the final reaction. Nitrate formation rates decreased with increasing salt concentration. SAOR and SNFR showed a decreasing trend as salinity concentrations were increased. The SAOR was reduced from 0.2 to 0.08 mg NH4+-N g-1VSS day-1 as the salt concentration increased from 0 to 30 g NaCLL-1. Similarly, the SNFR decreased from 0.26 kg NO3--N kg-1VSS day-1 at saline free to 0.1 kg NO3--N kg-1VSS day-1 at saline 30 g L-1. A severe inhibition of nitrifiers activity was observed at increased salt concentrations. The inhibition ratio of specific ammonium oxidation rates were 17, 47 and 60% on the reactor of 10, 20 and 30 g NaClL-1 added, respectively. The inhibition ratio of specific nitrate forming rates also were inhibited 30, 53 and 62% on the reactor of 10, 20 and 30 g NaClL-1 added, respectively. As the salinity concentrations increased from 0 to 30 mg NaClL-1, the average MLSS concentration increased from 1,245 to 1,735 mgL-1. The SS concentration of supernatant in reactor which settled about 30 minutes was not severely difference between concentration of salt free reactor and one of those high salt contained reactors

지체장애인의 사회인구학적 특성과 생활체육 참여 간의 인과모형

김기영,문용 한국특수체육학회 1999 한국특수체육학회지 Vol.7 No.2

The principal purpose of this study is to analyze closely the causal effects between personal traits and participation of the physically handicapped in mass sports. For this purpose the research was administered to 368 male and female adults dwelling in both Kyeonggi Province and Seoul. Data were collected through samples by means of cluster sampling method. The questionnaire for data collection of this study was based on those used in domestic previous studies of Kim Jeong Sun's(1987), Lee Jeong Young's(1989, 1991), Park Young Kwan's(1992), Lee Jae Hong's(1993). McPerson's(1977), and Greendorfer's(1974), and used them after examing the verification of validity and reliability through pilot test. The methods of Statistics used to analyze the collected datas were structural equation modeling analysis. The following is conlusions brought through these analyzing methods and process in this study. 1. There was partialy supported by hypothesis 1 of the relationship between personal traits and participation of the physically handicapped in mass sports. 2. There was partialy supported by hypothesis 2 of the relationship between personal traits and participation of the physically handicapped in mass sports. 3. There was supported by hypothesis 3 of the relationship between personal traits and participation of the physically handicapped in mass sports. 4. There was not supported by hypothesis 4 of the relationship between personal traits and participation of the physically handicapped in mass sports. 5. There was not supported by hypothesis 5 of the relationship between personal traits and participation of the physically handicapped in mass sports. 6. There was partialy supported by hypothesis 6 of the relationship between personal traits and participation of the physically handicapped in mass sports. 7. There was supported by hypothesis 7 of the relationship between personal traits and participation of the physically handicapped in mass sports.

자폐성 장애아동의 수중운동에 대한 지도자의 인식

김기영 한국특수체육학회 2004 한국특수체육학회지 Vol.12 No.4

The purpose of this study was to investigate leaders' perceptions toward aquatic exercise for children with autistic disorder as well as to find out several dominant variables(i.e., gender, age, marriage, academic background, license for swimming, career for teaching swimming, the attending classes and seminars regarding disability, the experience of volunteer work for people with a disability) affecting the leaders' perceptions about the effect of aquatic exercise. The participants consisted of 331 leaders who were teaching swimming in Seoul and Kyonggi Province. The questionnaire for data collection of this study was based on those used in previous studies of Kim(1994), Park(1998), Kim(1999), Jung(2002), Lee·Yeo·Kim(2004) and used them after examining the verification of validity and reliability through a pilot test. The statistical methods used to analyze the collected datas were the frequency analysis, independent t-test, and one-way ANOVA using SPSS 11.0. The following conclusion was warranted; first, leaders' perceptions toward the psycho-motor effect of aquatic exercise for children with autistic disorder depend on gender, age, academic background, the attending classes and seminars regarding disability, the experience of volunteer work for people with a disability. Second, leaders' perceptions toward the cognitive effect of aquatic exercise for children with autistic disorder depend on age, academic background, the attending classes and seminars regarding disability, the experience of volunteer work for people with a disability. Third, leaders' perceptions toward the affective effect of aquatic exercise for children with autistic disorder depend on academic background, license for swimming, career for teaching swimming, the experience of volunteer work for people with a disability.

性別 및 年齡에 따른 體格과 體力의 特性과 變化에 關한 縱斷的 硏究 Ⅰ : 體育專攻 大學生을 中心으로 Emphasised on College Men of Physical Education

金尙國,姜東洹,金昇一,徐再均,金耕知,孫斗玉,鮮于攝,崔榮烈,尹宇相,金亨燉,方永鎭,李錫元 慶熙大學校 體育科學大學 1988 體育科學論叢 Vol.- No.1

The purpose of this study was to compare the characterists and change in physique and physical function by college student of physical education major(287males and 40 females of age groups ranging from 18 to 26). The results were as following; 1) The characteristics of physique and physical function by sex and age. ① The male group of 18yrs old showed higher values in Height, Weight, Upper Limb Length, Strength, Flexibility, and Vital Capacity than any other groups, but female group showed lower values in Height, Weight, Chest Girth, Lower Limb Length, Thigh, Girth, Calf Girth and all of the Physical function. ② The male group of 19yrs old showed high values in power and Agility, then female group showed in Strength and Flexibility. ③ The male group of 20yrs old showed the lower values in Weight, Waist Girth, Upper Limb Length, Fore Arm Girth, Thigh Girh.Calf Girth, Vital Capacity, and female group are very lowed in Upper Arm Lenght, Fore Arm Length, Skin Fold Thickness and 5 minute Run. ④ The male group of 23yrs old showed the high values in Upper Arm Girth, Fore Arm Girth and Balance, and then female group higher in Weight, Chest Girth, Waist Girth, Upper Arm Girth, Fore Arm Girth, Thigh Girth, Power, Shuttle Run, Balance and vital capacity than any other age Groups. ⑤ In male group, Chest Girth, and Blood Pressure were significantly related, and Side Step and Trunk Extension were nagatively related to the age at 0.1% level, and then in female group, Sargent Jump, Standing Long Jump and Vital Capacity were showed a significantly related at 0.5% level. 2) The difference of physique and physical function between male and female by age. ① Everage difference in whole physique items except skinfold thickness was 9.8%, and that 21.1% in all of physical function except Trunk Flextion between male and female group subjects. ② About the ages, the 18yrs old male group showed the 22.8% higher values of 26 items, but 22yrs old male group were about 12.2% in 23 items, thus it is very lower than any other groups. 3) The difference of physique and physical function between General group and physical education group in age-matched. ① In the physique male physical education groups showed about 7% higher in Weight, Chest Girth, Upper Limb Length, Upper Arm Girth, Thigh Girth, and female group showed about 7% higher in Weight and Upper Limb Length. ② In the physical function, Trunk Flextion, 5 minute Run, and Blood Pressure(Diastolic) were about 8% high values in whole group, and female group showed about 8% higher in Standing Long Jump, Shuttle Run, and Trunk Extension. ③ In 22yrs old male and female physical education group were very dominated in physique and physical function than the other age group against the general group.

65세 이상의 노령층에서 고지혈증의 위험요인

김용배,장원기,황보영,김화성,안규동,이병국,이용진,김세훈,김승수,김승훈,김영록,김웅빈,이성수 순천향의학연구소 2006 Journal of Soonchunhyang Medical Science Vol.12 No.1

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전경대원에서 발생한 결핵의 임상 양상

문창기,박상준,조민구,김영중,김소연,김윤권,정준오,안석진,김은실,서승오,김지훈,최원제,이윤영,박형기,최규영,김현근 대한감염학회 2006 감염과 화학요법 Vol.38 No.6

Background: The purpose of this study was to document the incidence and clinical characteristics of patients with tuberculosis (TB) in combat and auxiliary police, living in a group, in Korea where the incidence rate of active TB in a general population is higher than in Western countries. Materials and Methods:We retrospectively reviewed the medical records of all tuberculosis patients diagnosed at National Police Hospital from January 2002 through December 2004. Results:In 2002-2004, a total of 156 cases of tuberculosis were identified with the mean (Standard deviation) age of 20.6 (±1.0) years. Of these, 134 (85.9%) patients were registered as new cases, 11 (7.1%) as relapse, 2 (1.3%) as failure, 5 (3.1%) as treatment-after-default cases whereas 4 (2.6 %) patients were not included in any categories. Average annual new TB rate and smear-positive TB rate were 86.5/10^(5) and 17.4/10^(5) person-years, respectively. In 12 of 31 smear-positive cases, time from onset of symptoms to diagnosis was more than 30 days. Two multidrug-resistance TB cases were identified and two suspected outbreak episodes of TB had occurred during 3 years. Conclusion:There was no statistically significant difference in the incidence rate of new cases of TB between the general population aged 20 to 29 years and combat and auxiliary police in Korea. 배경 : 국내 결핵의 발생은 감소 추세에 있으나 여전히 후진국형 발생양상을 보이고 있다. 특히 집단생활을 하는 젊은이들에서 발생하는 결핵의 유행이 간헐적으로 알려지고 있어 우려를 낳고 있다. 이에 저자들은 최근 전경대원의 결핵 발병 양상에 대해 알아보고자 본 연구를 시행하였다. 재료 및 방법 : 2002년 1월부터 2004년 12월까지 3년간 경찰병원에서 결핵 진료를 받은 전경대원의 의무기록을 후향적으로 분석하여 연도별 결핵 신환발생률, 도말양성결핵 신환율, 진단 지연, 집단발병, 다제내성결핵을 조사하였다. 결과 : 연도별 결핵 신환자 수(10만명당 발생추정치)는 2002년 50명(83.6명), 2003년 42명(83.7명), 2004년 42명(93.5명)이었고 도말양성 폐결핵 신환자 수는 2002년 10명(16.7명), 2003년 11명(21.9명), 2004년 6명(13.4명)이었다. 3년간 도말양성 폐결핵 환자는 31명이 있었고 그 중 12명은 호흡기 증상 발생 30일이 지나서 진단을 받았다. 다제내성 결핵은 2명이 있었으며 결핵의 집단발병이 의심되는 사례는 2차례 있었다. 결론 : 전경대원과 20-29세 연령군 일반인의 결핵 신환발생률, 도말양성 폐결핵 발생률의 통계적으로 유의한 차이는 없었다.