기계적 합금화 및 열처리에 의한 Al-Cu-Fe 합금계에서 준결정상의 형성에 미치는 Si 의 영향

김원태,김석환,홍경태,김도향,김기범 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.9

The effect Si addition on structural evolution during heat treatment was studied in mechanically alloyed Al_(65)Cu_(20)Fe_(15) and Al_(65)Cu_(20)Fe_(10)Si_5 Powders using X-ray diffractometry, transmission electron microscopy and differential scanning calrorimetry. Both alloy powders processed for 10 hr showed a layered microstructure of Al, Cu and Fe. Mechanical alloyed powders for 10 hr transformed into several different phases depending on heat treatment conditions: Both alloy powders, heat treated for 10 hr at 335℃, showed a mixed structure of Al₂Cu, Al_7Cu₂Fe and unreacted Fe; Both alloy specimens heat treated for 10 hr at 550℃ showed 1/1 cubic approximant phase as a major phase; Al_(65)Cu_(20)Fe_(15) and Al_(65)Cu_(20)Fe_(10)Si_5 alloy powders heat treated for 5 hr at 750℃ showed a mixture of Al(Fe, Cu) and Al_(13)Fe₄ and 1/1 cubic approximant phase as a major phase with some icosahedral phase and other approximant phases, respectively. Addition of Si promotes the stability of quasicrystalline and approximant phases. No icosahedral phase or approximant phases were observed in both alloy powders heat treated either at 550℃ or at 750℃ after 120 hr Mechanical alloying.

기계적 합금화와 열처리에 따른 Al65Cu20Fe15 합금의 조직변화

김원태,홍경태,김도향,김석환,김기범 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.12

Structural changes during mechanical alloying and post-heat treatment of Al_(65)Cu_(20)Fe_(15) alloy powder were studied by using X-ray diffractometry, transmission electron microscopy and thermal analysis. Al_(65)Cu_(20)Fe_(15) alloy sample precessed for 10 hrs showed a layered structure consisted of Al, Cu and Fe containing layers. DSC of the specimens showed two broad exothermic peaks: one is weak in the temperature range of 300∼390℃ and the other strong 390∼480℃. The first exothermic peak seems to correspond to the formation of Al₂Cu and Al_7Cu₂Fe phases and the second peak to the formation of mixture of quasicrystalline approximant and ordered Al(Fe, Cu) β phases from the previously formed Al₂Cu, Al_7Cu₂Fe and unreacted Fe phases. Al_(65)Cu_(20)Fe_(15) alloy sample processed for 120 hrs showed a homogeneous distribution of nano scaled Al(Fe, Cu) β particle in an amorphous matrix. During heat treatment of the sample, the microstructure transformed into a mixture of ordered Al(Fe, Cu) β phase and Al_13Fe₄. Direct formation of quasicrystalline phase was not observed in as-mechanically alloyed Al_(65)Cu_(20)Fe_(15) alloy powder.

Influence of Nb on Microstructure and Mechanical Properties of Ti-Sn Ultrafine Eutectic Alloy

Kim, Young Seok,Park, Hae Jin,Kim, Jeong Tae,Hong, Sung Hwan,Park, Gyu Hyeon,Park, Jin Man,Suh, Jin Yoo,Kim, Ki Buem Hanrimwon Publishing Co. 2017 METALS AND MATERIALS International Vol.13 No.4

Effect of Ca addition on the plastic deformation behavior of extruded Mg-11Li-3Al-1Sn-0.4Mn alloy

Kim, Jeong Tae,Park, Gyu Hyeon,Kim, Young Seok,Hong, Sung Hwan,Park, Hae Jin,Suh, Jin You,Son, Hyeon Taech,Lee, Min-Ha,Park, Jin Man,Kim, Ki Buem Elsevier 2016 JOURNAL OF ALLOYS AND COMPOUNDS Vol.687 No.-

<P><B>Abstract</B></P> <P>Effects of Ca addition on the microstructure and mechanical properties of as-extruded Mg-11Li-3Al-1Sn-0.4Mn-xCa alloys with x = 0 and 0.8 were investigated. The Ca addition on the Mg-11Li-3Al-1Sn-0.4Mn alloy can lead to no change in the constituent phases, which consist of <I>β</I>-Li, <I>α</I>-Mg, MgLi<SUB>2</SUB>Al and MgLi<SUB>2</SUB>Sn. However, the microstructure obtained after the extrusion process clearly exhibits different morphologies, of which Ca free alloy shows homogeneously distributed intermetallic compounds and Ca containing alloy display well-arranged intermetallic compounds along the extrusion direction. From these microstructural evolutions, even though the tensile strength decreased, the tensile elongation was significantly improved from 35.1 to 88.6%. The effect of Ca addition on the microstructural evolution and increased plastic deformability have been discussed using grain refinement, grain boundary sliding and micro crack propagation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The extruded microstructure is distinctly alternated by additional Ca content. </LI> <LI> The Ca added Mg-11Li-based alloy indeed shows a highly increased ductility. </LI> <LI> The grain refinement, occurrence of DRX, GBS and intermetallic compound significantly contribute to super-plastic behavior. </LI> <LI> The additional Ca induced microstructural evolution after hot-extrusion is the key to decide yielding behavior. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

제13장 기본적 인권의 토착화

김기범 ( Ki Buem Kim ) 연세대학교 사회과학연구소 1972 社會科學論集 Vol.5 No.-

Flexible polymer dispersed liquid crystal film with graphene transparent electrodes

Yura Kim,Kwangyoon Kim,Ki Buem Kim,Jun-Young Park,Naesung Lee,Yongho Seo 한국물리학회 2016 Current Applied Physics Vol.16 No.3

A flexible polymer-dispersed liquid crystal (PDLC) film with graphene layers as transparent electrodes was fabricated by combining a UV curable polymer and a nematic liquid crystal. The PDLC film with a dimension of 5 10 cm2 was flexible and operated normally with no damage when it was bent with a radius of 2 mm. Instead of using conventional transparent conducting film, the single-layer-graphene transferred on PET film was used as transparent electrodes. The thickness of the graphene-PDLC was about 210e220 mm. The single-layer-graphene grown by thermal chemical vapor deposition was transferred onto the PET film, and its sheet resistance was about 1.2 kU/,. The controllable transmission range between the on and off states was about 60% in the visible range. The response time for the turnon and off processes were estimated to be 0.3 and 32 ms, respectively. This successful fabrication of graphene based PDLC is a crucial step toward paving the way for the commercialization of the emerging material, graphene.

Development of High Entropy Alloy Film using Magnetron Sputtering

Young Seok Kim,Ki Seong Lim,Ki Buem Kim 한국표면공학회 2018 한국표면공학회 학술발표회 초록집 Vol.2018 No.6

청소년들의 골연령과 역연령을 통한 체격과 체력의 차이 검증

김대훈(Dae-Hoon Kim)윤형기(Hyoung-Ki Yoon),오세이(Sei-Yi Oh),이영준(Young-Jun Lee),김범준(Buem-Jun Kim),최영민(Young-Min Choi),송대식(Dae-Sik Song)안주호(Ju-Ho An),서동녘(Dong-Nyeuck Seo),김주원(Ju-Won Kim),나규민(Gyu-Min Na),오경아(Kyu 한국응용과학기술학회 (구.한국유화학회) 2021 한국응용과학기술학회지 Vol.38 No.1

본 연구는 청소년들의 체격과 체력을 평가하는 데 있어 골연령이 더욱 효과적일 것이라는 점을 가정으로 진행하였으며, 본 연구의 목적은 청소년기의 학생들을 대상으로 골연령과 역연령을 통해 체격과 체력의 차이를 규명하여 청소년들의 체격, 체력의 균형적 발달과 학생들의 건강증진에 기여하는 데 있다. 연구 대상은 6세부터 16세까지의 총 1100명의 모집단 중 PAPS(학생건강체력평가)와 TW3 방법 연령 기준 에 따라 총 874명(남자 483명, 여자 391명)의 11세∼16세 청소년을 대상으로 하였으며, 생물학적 성숙지표를 나타내는 골격성숙도는 X-ray 촬영 후 TW3(Tanner-Whitehouse 3) 방법을 이용하여 평가하였고 역연령은 출생년월을 사용하였다. 체격은 신장계, InBody270(Biospace, Korea)을 이용하여 2개 항목을 측정하였고 체력측정은 총 7개 항목으로 근력, 평형성, 민첩성, 순발력, 유연성, 근지구력, 심폐지구력을 측정하였다. 자료처리 방법으로는 SPSS 25.0을 사용하여 독립표본 t-test를 실시하였고, p< .05 수준에서 유의한 것으로 간주하였다. 본 연구의 결과는 다음과 같다. 첫째, 골연령과 역연령을 이용한 체격의 비교에서 11세, 12세 남자는 키와 체중에서 유의한 차이가 나타났으며, 13세 남자는 체중에서 유의한 차이가 나타났다. 11세 여자는 체중과 신장, 12세 여자는 신장에서 유의한 차이가 나타났다. 둘째, 골연령과 역연령을 이용한 체력의 비교에서 11세 남자는 근력, 순발력, 유연성, 심폐지구력에서 유의한 차이가 나타났고 12세 남자는 근력, 순발력, 심폐지구력, 13세 남자는 유연성에서 유의한 차이가 나타났다. 11세 여자는 근력, 순발력, 유연성, 근지구력, 심폐지구력, 14세 여자는 유연성에서 유의한 차이가 나타났다. 이러한 결과로 본 연구에서는 급격한 골 성장이 이루어지는 시기에는 골연령을 기준으로 체격과 체력을 평가하는 것이 역연령 기준으로의 평가보다 정확하다는 결과를 도출하였다. This study was conducted on the assumption that bone age would be more effective when it comes to physique and physical fitness assessment for adolescents, and the purpose of this study was to identify the differences in physique and physical fitness for students in their adolescence through bone age and chronological age in order to contribute to the well-balanced physique and physical fitness development in adolescents and the health improvement in students. Total 874 adolescents(483 males, 391 females) aged 11∼16 were selected as subjects out of the total population of 1100 adolescents aged 6∼16 based on the PAPS(Physical Activity Promotion System) and age standards of the TW3 method; and skeletal maturation, which symbolize the indicators of biological maturation, were evaluated by using the TW3(Tanner-Whitehouse 3) method after hand-wrist radiographs, and birth date was used for chronological age. A stadiometer and InBody 270 (Biospace, Korea) were used to measure 2 components in physique. A total of 7 components in physical fitness, which included muscular strength, muscular endurance, flexibility, power, cardiovascular endurance, balance, agility, were measured as well. A independent samples t-test was conducted for data processing using SPSS 25.0, and the significance level was set at p< .05. The study results are as follows. First, bone age and chronological age used for physique comparison in males aged 11 and 12, height and weight showed significant difference; in males aged 13, weight showed signicant difference. Weight and height in females aged 11, and height in females aged 12 showed significant difference. Second, bone age and chronological age used for physical fitness comparison in males aged 11, muscular strength, power, flexibility, cardiovascular endurance showed significant difference; in males aged 12, muscular strength. power, cardiovascular endurance; in males aged 13, flexibility showed significant difference. Muscular strength, power, flexibility, muscular endurance, cardiovascular endurance in females aged 11, and flexibility in females aged 14 showed significant difference. As a result, this study concluded that in a period of rapid skeletal growth, evaluating physique and physical fitness based on bone age is more accurate than evaluating based on chronological age.

아동의 골연령과 역연령이 체격, 체력 및 운동협응에 미치는 영향

김대훈(Dae-Hoon Kim),윤형기(Hyoung-Ki Yoon),오세이(Sei-Yi Oh),김범준(Buem-Jun Kim),최영민(Young-Min Choi),송대식(Dae-Sik Song),안주호(Ju-Ho An),서동녘(Dong-Nyeuck Seo),김주원(Ju-Won Kim),나규민(Gyu-Min Na),오경아(Kyung-A Oh) 한국발육발달학회 2020 한국발육발달학회지 Vol.28 No.3

The aim of this study was to analyze the relative importance of bone age and chronological age in physique according to gender and to identify the relative importance of bone age, chronological age, and physique in physical fitness and motor coordination according to gender in order to alleviate the imbalance between physique and physical fitness in children. A total of 666 children(346 males, 320 females) between the ages of 11-14 were enrolled as subjects, and the skeletal maturation, which is proven and used most often as indicators of biological maturation, were measured in order to calculate the bone age. The skeletal maturation were measured by taking hand-wrist radiographs of children and were calculated in order to reflect bone maturities of each part by calculating the bone age using the TW3 method, which determines skeletal maturation. The calculation method of chronological age was done by dividing 12 months into 10 points, giving scores ranging from 0 points in December to 0.91 points in January, starting with the month of the child"s birth. A stadiometer and InBody 270(Biospace, Korea) were used to measure 8 components in physique. Physical fitness were measured through a total of 4 components: muscular strength, flexibility, muscular endurance, cardiovascular endurance; and motor coordination were measured through a total of 3 components: balance, agility, power. The data processing was performed using SPSS 25.0 with descriptive statistics, stepwise regression, and it was considered significant at the level of P< 0.05. The results of this study may be summarized as follows. First, physique variables for both males and females aged 11-14 were found to be more significant predictors of bone age than chronological age. Second, for physical fitness in males, in the order of %fat, body water, waist-hip ratio, weight, fat-free mass, and chronological age were more significant predictor variables; and in females, in the order of %fat, fat-free mass, height, chronological age, weight, bone age, fat mass, and body water were more significant predictor variables. For bone age and chronological age in physical fitness, bone age in males and chronological age in females found to be the more representative variables respectively.

저융점 원소의 첨가에 따른 Ti₆₅Fe₃₅ 과공정 합금의 미세구조와 기계적 특성의 변화

황윤중,홍성환,김정태,김영석,박혜진,김희진,정연범,이영훈,김기범,Hwang, Yun Jung,Hong, Sung Hwan,Kim, Jeong Tae,Kim, Young Seok,Park, Hae Jin,Kim, Hee Jin,Jeong, Yeon Beom,Lee, Young Hoon,Kim, Ki Buem 한국재료학회 2017 한국재료학회지 Vol.27 No.10

The microstructural evolution and modulation of mechanical properties were investigated for a $Ti_{65}Fe_{35}$ hypereutectic alloy by addition of $Bi_{53}In_{47}$ eutectic alloys. The microstructure of these alloys changed with the additional BiIn elements from a typical dendrite-eutectic composite to a bimodal eutectic structure with primary dendrite phases. In particular, the primary dendrite phase changed from a TiFe intermetallic compound into a ${\beta}$-Ti solid solution despite their higher Fe content. Compressive tests at room temperature demonstrated that the yield strength slightly decreased but the plasticity evidently increased with an increasing Bi-In content, which led to the formation of a bimodal eutectic structure (${\beta}$-Ti/TiFe + ${\beta}$-Ti/BiIn containing phase). Furthermore, the (Ti65Fe35)95(Bi53In47)5 alloy exhibited optimized mechanical properties with high strength (1319MPa) and reasonable plasticity (14.2 %). The results of this study indicate that the transition of the eutectic structure, the type of primary phases and the supersaturation in the ${\beta}$-Ti phase are crucial factors for controlling the mechanical properties of the ultrafine dendrite-eutectic composites.