C-Mn-Si 계 변태유기소성강의 성형상에 미치는 베이나이트 변태 온도 및 응력상태의 영향

박찬경,전현조,오진후,홍승갑 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.9

The effects of TRansformation Induced Plasticity(TRIP) phenomena on the plastic deformation of 0.2C-1.5Si-1.5Mn multiphase steel have been investigated at various heat treatment and stress conditions. In order to estimate a deformation behavior under multi-axial stress rotate, the hole expansion(HE) tests were carried out. It is shown that the formability evaluation from the uni-axial tensile tests was quite different from the formability measured from multi-axial HE-tests because of different stress state. The formability in the multi-axial stress state decreased due to the extinction of the transformable retained austenite at relatively earlier deformation stage and the production of irregular α' martensite. The voids of TRIP steel were initiated exactly at the interface between transformed martensite and ferrite matrix regardless of stress state. In addition, new form of experimental formula is proposed in order to predict the multi-axial formability of the TRIP steel from the results of uniaxial tensile test.

양산단층 중앙부의 활단층 지형과 Trench 조사

조화룡,강전독정,전명순,김성작,도변만구,좌등비여지,전정수,지헌철,미지화부 한국지형학회 1994 한국지형학회지 Vol.1 No.2

梁山斷層系의 중앙부에 대하여 항공사진 판독과 현지 지형, 지질 조사를 통하여 다음과 같은 사실이 밝혀졌다. 1. 梁山斷層系는 第脚紀(後期)에도 활동을 반복하고 있는 活斷層이다. 따라서 이 단충은 그 좌우에 분포하는 高位, 中位, 低位의 각 河岸段丘面 모두를 상, 하방향으로 누적적으로 변화시키고 있다. 2. 梁山斷層系의 중앙부에서 段丘面의 變位로 미루어 볼 때 동측이 상대적으로 隆起하고 있다. 이것은 이 지역의 中地形的 山地高度의 분포와는 逆이다. 3. 斷層線온 현저하게 直線的으로 연장되어 있고, 斷層面은 거의 수직이다. 이 斷層系에 수반되는 破碑帶도 폭 수십 m 이상으로 넓고, 현저한 斷層粘土帶와 變形帶를 동반한다. 4. 偏平礫의 변형 형태에 의하면 走向移動이 탁월한 단층운동이 추정된다. 斷層粘土帶의 破碎物質의 관찰에 의하여 右橫變位走向移動(right strike slip)이 인정된다. 5. 이들의 특징으로부터 梁山斷層系는 走商移動(右橫變位)이 탁월한 活斷層으로 판명되었다. 段丘面 및 堆積物의 추정 계산치로부터 梁山斷層系의 평균 상, 하 變位 速度는 0.02-0.03㎜/y. 정도이고, 右橫變位의 평균 속도는 적어도 C급 상위(0.05∼0.1㎜/y.) 정도이든지 이것을 약간 상회하는 정도일 것으로 추정된다. 6. 低位 및 最低位의 段丘面에서는 上位變位를 밝히기 어려웠다. 이들의 段丘面 위에는 논으로 이용되고 있기 때문에 오랜 기간 동안 인공적으로 改變을 받아왔으며 이들 단구면 위에서 1 ∼2m 정도의 상·하 변위가 있었다고 해도 인공적 개변이 이를 지워버렸을 것이다. 따라서 이들의 최근에 형성된 단구면에서는 변위의 유무를 언급할 수 없었다. Many distinct lineaments have been recognized by Landsat images In Korea Peninsula. The Yangsan fault system situated in the southeastern part of Korea is especially linear, continuously traceable for a long distance(about 200㎞), and particularly remarkable among these linearnent. The topographic expression of the Yangsan fault system is derived from the straightly stretching fault valley with wide shattered zones in the direction of NNE-SSW. This fault system extends for about 200㎞ from the mouth of the Nagdong River west of Busan in the south to Yeondong in the north, and geologically separates Korean Peninsula from the East Sea. The amount of horizontal displacement may reach 30㎞. It is recognized as one of the most important faults in Korea Peninsula. From the interpretations of aerial photographs, and field surveys along the central part of the Yangsan fault system, the main results are summarized as follows; 1. The Yangsan fault system has repeatedly moved in the late Quaternary. The lower to higher river terrace surface on this system show cumulative vertical offsets. 2. The vertical component is upthrown on the east side from considering the terrace offset and the distribution of the mountainous lands. This vertical movement is reverse to the topographical situation on the meso-scale. 3. The fault trace is extremely straight. The fault plane is almost vertical. The shattered zone exceeds tens of meters in width with a remarkable fault gouge. 4. The longer axis of flat clasts within the gravel excavated in the exploratory trench showed the rearrangement along the fault. The predominantly right-lateral movements were recognized as the elongation of clayey parts and breccias in the fault gouge. 5. From these characteristics, the Yangsan fault was clarified to be active with predominantly right-lateral movement. Estimated ages of terraces and its deposits give average rates of vertical and right slip on the Yangsan fault system at about 0.02~0.03&/y., respectively. 6. The fault topography is not found on the lower terraces. As the surface of lower fault scarplets less than a few meters high might have been modified or destroyed by the human actions. Therefore, we cannot mention the existence of the younger movement on the lower terraces.

Fe-Mn 합금의 방진특성 및 변태특성에 미치는 냉간가공의 영향

최종술,백승한,지광구,신명철,전선우 대한금속재료학회(대한금속학회) 1999 대한금속·재료학회지 Vol.37 No.7

The objective of this study is to investigate the effect of deformation degree on damping capacity, transformation behavior and mechanical property in Fe-16%Mn-2%Cr and Fe-22%Mn alloys. The Fe-16%Mn2%Cr and Fe-22%Mn alloys undergo γ→ε→α' and γ→ε martensitic transformation by deformation, respectively. In the two alloys, the increase in degree of cold rolling cause an increase of reverse transformation temperatures of ε→γ because the dislocations introduced by cold rolling hinder the movement of γ→ε boundaries. The decrease in mobility of γ→ε boundary is responsible for a rise in driving force, raising the reverse transformation temperature. At low strain amplitudes of 1×10^(-4)∼4×10^(-4), damping capacity increases with increasing rolling degree up to 5-10%. At a high strain amplitude, the 0% rolled alloy exhibits good damping property. The results indicate that area of γ→εboundaries at a low strain amplitude is more dominant than their mobility. With a higher strain amplitude, however, mobility becomes a major factor for damping capacity.

변단면(變斷面) Beam-Column 에 대한 축하중(軸荷重)과 Moment 의 상관관계

유철수,전홍건 고려대학교 공학기술연구소 1985 고려대학교 생산기술연구소 생기연논문집 Vol.21 No.1

The analytical method finding interaction relationship among axial load, moment, and slenderness for tapered beam-column is quite complicated. Moreover, analysis for some shapes of cross-section is impossible. Newmark's integration method can be used as numerical analysis which is applicable for any shape factors. Using Newmark's method Interaction relationships between axial load and moment for simply supported case were obtained and represented by figures.

Fe3Al 금속간화합물의 항복강도 이상거동과 변형기구 고찰

박찬경,장영원,전현조 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.8

It is well known that Fe₃Al intermetallic compound shows an anomalous peak of the yield strength at about 500℃. That is, the yield strengths increase with increasing deformation temperature in the range of 300℃-500$quot;℃, and then decrease at higher temperatures. The dislocation structure was examined by transmission electron microscopy, and high temperature mechanical properties were examined by tensile and load relaxation tests. The flow stress curves obtained from lead relaxation bests were then analyzed in terms of internal variable deformation theory. It was found that the flow curves consisted of three micro-deformation mechanisms i.e inelastic deformation mode, plastic deformation mode and dislocation creep deformation mode, depending on both dislocation structure and deformation temperature. The flow curves could be well described by the constitutive equations of these three micro-deformation mechanisms based on the internal variable deformation theory.

제주재래돼지와 듀록 참조축군에서 Melanocortin 4 Receptor (MC4R) 유전자형과 지방산 조성간의 관련성 분석

강용준(Yong-Jun Kang),김상금(Sang-Geum Kim),김수연(Su-Yeon Kim),신문철(Moon-Cheol Shin),우제훈(Jae-Hoon Woo),김남영(Nam-Young Kim),신상민(Sang-Min Shin),최재영(Jae-Young Choi),유지현(Ji-Hyun Yoo),박남건(Nam-Geon Park),양병철(Byoung-C 한국생명과학회 2020 생명과학회지 Vol.30 No.1

본 연구에서는 제주재래돼지와 듀록 품종 사이에서 생산된 F₂ 참조축군에서 melanocortin-4-receptor (MC4R) 유전자형과 지방산 조성간의 관련성을 연구하였다. 전체 290 여두의 F₂ 자손을 이용하여 14개의 지방산 조성을 측정하였다. Taq Ⅰ PCR-RFLP 방법을 이용하여 MC4R c.1426A>G (p.Asp298Asn)의 단일염기다형성(single nucleotide polymorphism, SNP)을 확인하였다. MC4R 세 가지 유전자형(AA, AB, BB)이 모두 발견되었고, 그 빈도는 각각 0.299, 0.542, 0.159로 확인되었다. AA 유전자형을 가진 개체에서 palmitic acid (C16:0, p<0.05), stearic acid (C18:0, p<0.01), eicosenoic acid (C20:1n9, p<0.05), saturated fatty acid (SFA, p<0.01) 함량이 GG 유전자형을 가진 개체보다 더 높은 것으로 확인되었다. 반면에 GG 유전자형을 가진 개체는 linoleic acid (C18:2n6, p<0.001), linolenic acid (C18:3n3, p<0.001), linolenic acid (C18:3n6, p<0.001), arachidonic acid (C20:4n6, p<0.001)과 같은 불포화지방산(unsaturated fatty acid) 함량이 AA 유전자형을 가진 개체보다 더 높은 것을 확인하였다. 제주재래돼지와 듀록 품종 사이에서 생산된 F₂ 참조축군에서 MC4R GG 유전자형이 포화지방산은 낮추고, 불포화지방산은 높이는 것으로 확인되었다. 본 연구 결과 MC4R의 유전적 다형성이 듀록과 제주재래돼지 교배 프로그램에서 육질향상과, 고기내의 지방산 함량을 조절할 수 있는 유전적 표지 인자로 활용될 수 있을 것이라 사료된다. This study was conducted to examine association between melanocortin-4-receptor (MC4R) genotypes and fatty acid (FA) composition in an F₂ intercross between Duroc and Jeju (South Korea) Native pigs (JNP). Fourteen FA composition traits were measured in more than 290 F₂ progeny population produced between Duroc and JNP. All experimental pigs were successfully genotyped for the MC4R c.1426A>G (p.Asp298Asn) single nucleotide polymorphism (SNP) by using Taq Ⅰ PCR-RFLP methods. We detected three MC4R genotypes, AA, AG, and GG with 0.299, 0.542, and 0.159 genotype frequencies, respectively. The MC4R AA genotype animals showed higher levels in palmitic acid (C16:0, p<0.05), stearic acid (C18:0, p<0.01), eicosenoic acid (C20:1n9, p<0.05), saturated fatty acid (SFA, p<0.01) than GG homozygotes, respectively. Whereas MC4R GG genotype showed higher values in linoleic acid (C18:2n6, p<0.001), linolenic acid (C18:3n3, p<0.001), linolenic acid (C18:3n6, p<0.001), arachidonic acid (C20:4n6, p<0.001) and unsaturated fatty acid (USFA, p<0.01) than AA pigs, respectively. The MC4R GG genotype was associated with increasing USFA and decreasing SFA in the F₂ progeny population produced between Duroc and JNP. Our finding suggests that the MC4R polymorphisms can be used as a valuable genetic marker for Duroc and JNP breeding programs to improve meat quality and to control FA compositions.

T_c and J_c distribution in in situ processed MgB₂ bulk superconductors with/without C doping

Kim, C.J.,Kim, Y.J.,Lim, C.Y.,Jun, B.H.,Park, S.D.,Choo, K.N. The Korea Institute of Applied Superconductivity a 2014 한국초전도저온공학회논문지 Vol.16 No.2

Temperature dependence of magnetic moment (m-T) and the magnetization (M-H) at 5 K and 20 K of the in situ processed $MgB_2$ bulk pellets with/without carbon (C) doping were examined. The superconducting critical temperature ($T_c$), the superconducting transition width (${\delta}T$) and the critical current density ($J_c$) were estimated for ten test samples taken from the $MgB_2$ bulk pellets. The reliable m-T characteristics associated with the uniform $MgB_2$ formation were obtained for both $MgB_2$ pellets. The $T_cs$ and ${\delta}Ts$ of all test samples of the undoped $MgB_2$ were the same each other as 37.5 K and 1.5 K, respectively. The $T_cs$ and ${\delta}Ts$ of the C-doped $MgB_2$ were 36.5 K and 2.5 K, respectively. Unlike the m-T characteristics, there existed the difference among the M-H curves of the test samples, which might be caused by the microstructure variation. In spite of the slight $T_c$ decrease, the C doping was effective in enhancing the $J_c$ at 5 K.

Effect of $Y_2O_3$ Nanoparticles on Critical Current Density of $YBa_2Cu_3O_{7-x}$ Thin Films

위창환,강병원,오상준,이성익,Tran, H.D.,Reddy, D.Sreekantha,Wie, C.H.,Kang, B.,Oh, Sang-Jun,Lee, Sung-Ik 한국초전도학회 2009 Progress in superconductivity Vol.11 No.1

Introduction of proper impurity into $YBa_2Cu_3O_{7-x}$ (YBCO) thin films is an effective way to enhance its flux-pinning properties. We investigate effect of $Y_2O_3$ nanoparticles on the critical current density $J_c$ of the YBCO thin films. The $Y_2O_3$ nanoparticles were created perpendicular to the film surface (parallel with the c-axis) either between YBCO and substrate or on top of YBCO, YBCO/$Y_2O_3$/LAO or $Y_2O_3$/YBCO/STO, by pulsed laser deposition. The deposition temperature of the YBCO films were varied ($780^{\circ}C$ and $800^{\circ}C$) to modify surface morphology of the YBCO films. Surface morphology characterization revealed that the lower deposition temperature of $780^{\circ}C$ created nano-sized holes on the YBCO film surface which may behave as intrinsic pinning centers, while the higher deposition temperature produced much denser and smoother surface. $J_c$ values of the YBCO films with $Y_2O_3$ particles were either remained nearly the same or decreased for the samples in which YBCO is grown at $780^{\circ}C$. On the other hand, $J_c$ values were enhanced for the samples in which YBCO is grown at higher temperature of $800^{\circ}C$. The difference in the effect of $Y_2O_3$ can be explained by the fact that the higher deposition temperature of $800^{\circ}C$ reduces intrinsic pinning centers and $J_c$ is enhanced by introduction of artificial pinning centers in the form of $Y_2O_3$ nanoparticles.

Synthesis, characterization, and electrochemical study of Os₃(CO)₇(1,2-dppm)(μ₃-η²:η²:η²-C₆₀) and Os₃(CO)₇(1,1-dppm)(μ₃-η²:η<s

Jun, T.,Park, B.K.,Lee, C.Y. Elsevier Sequoia 2014 Journal of organometallic chemistry Vol.763 No.-

Os<SUB>3</SUB>(CO)<SUB>7</SUB>(1,2-dppm)(μ<SUB>3</SUB>-η<SUP>2</SUP>:η<SUP>2</SUP>:η<SUP>2</SUP>-C<SUB>60</SUB>) (1) and Os<SUB>3</SUB>(CO)<SUB>7</SUB>(1,1-dppm)(μ<SUB>3</SUB>-η<SUP>2</SUP>:η<SUP>2</SUP>:η<SUP>2</SUP>-C<SUB>60</SUB>) (2) were prepared by decarbonylation of Os<SUB>3</SUB>(CO)<SUB>9</SUB>(μ<SUB>3</SUB>-η<SUP>2</SUP>:η<SUP>2</SUP>:η<SUP>2</SUP>-C<SUB>60</SUB>) (3) with Me<SUB>3</SUB>NO/MeCN in the presence of excess dppm (bis(diphenylphosphino)methane) in chlorobenzene. Then, compounds 1 and 2 were characterized by obtaining spectroscopic and microanalytical data, as well as by performing single-crystal X-ray diffraction studies. In addition, the electrochemical properties of 1 and 2 were examined by performing cyclic voltammetry. The cyclic voltammograms suggest that a C<SUB>60</SUB>-mediated electron transfer to the osmium cluster center takes place for species 1<SUP>3-</SUP> and 2<SUP>3-</SUP> in compounds 1 and 2.

Magnetic levitation properties of single- and multi-grain YBCO bulk superconductors

C.-J. Kim,A. Y. Yang,S. H. Lee,B.-H. Jun 한국초전도저온학회 2022 한국초전도저온공학회논문지 Vol.24 No.3

Single-grain (c-normal or c-parallel) and multi-grain YBCO superconductors were prepared by a melt growth processwith/without seeding. The magnetic levitation force and trapped magnetic field at liquid N2 temperature (77 K) of the YBCOsuperconductors were investigated. Samples for the levitation force measurement were zero-field cooled (ZFC) to 77 K, andsamples for trapped field measurement were field-cooled (FC) using Nd magnets. As for the magnetic levitation force, the c-normal,single grain sample showed the largest value, whereas the multi-grain sample showed the lowest value. The trapped magnetic fieldof the c-normal and c-parallel single-grain samples was 4-5 times that of the multi-grain sample. In addition, as the externalmagnetic field (the number of magnets) increased, the both properties increased proportionally. These results were explained interms of the orientation dependence of the levitation forces and the magnetic field trapping capability of the YBCO superconductor.