FCC {111} 선과 오일러 각(1) : 결정입방위 (結晶粒方位) Grain Orientation

백동규 대한금속재료학회(대한금속학회) 1984 대한금속·재료학회지 Vol.22 No.2

This is the first of two articles dealing with the orientation determination of the FCC structure using non-parallel {111} traces. In this first article, the Hoekstra equations are deduced on the basis of the Euler angles between the specimen and crystal coordinate systems. A method of computerization of calculations relative to crystal orientation as well as of the stereographic projection drawing is also presented.

Fcc 다결정금속의 소성변형에 따른 결정립회전 : 실험적관찰과 이론적해석 Experimental Observations and theoretical analysis

백동규 대한금속재료학회(대한금속학회) 1989 대한금속·재료학회지 Vol.27 No.4

A Cu-6Al-2Ni tricrystal was rolled to 20 % of thickness reduction. The lattice orientation was determined by means of the mutual angles of the slip traces produced by microhardness indentation, at one site of each crystal before rolling, and at two, after rolling, respectively at interior of the crystals and near grain boundary regions. All sites are near the triple point of the tricrystal. From this double determination of the crystals orientation after rolling, inhomogeneous lattice rotation of the crystals is observed. The experimental lattice orientation changes are compared with the prediction of the FC, RC models. Those of two crystals are in good agreement with the prediction, while those of the third crystal, which is smaller than the other two and surrounded by them, are in disagreement. From this disagreement, together with a slip line system observed in a microstructural examination at the triple point region, which is in contradiction with the FC, RC models, it is concluded that these simplified models, although remarkable in their ability to predict lattice relations in certain cases, are not applicable to regions of high strain accommodation such as the triple grain boundary region or to grains of small size such as exist in ordinary polycrystalline metallic materials.

Upregulation of monooxygenase DBH like 1 levels in the lungs of idiopathic pulmonary fibrosis

백동규,( Choon-sik Park ),( Hun Soo Chang ),( Jong-sook Park ),( Soo-taek Uh ),( Young Hoon Kim ) 대한결핵 및 호흡기학회 2018 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.126 No.-

Background: Our previous transcriptome study of cultured fibroblasts identified 178 genes that were differentially expressed by IPF fibroblasts compared with controls. Among them, MOXD1 was reported increased expression in non-cultured fibroblast from Emblom-Callahan MC`s study. However, the functional importance of MOXD1 has not been evaluated in IPF. Methods: MOXD1 mRNA expression was measured using real time PCR. The protein concentration was measured by enzyme- linked immunosorbent assay in bronchoalveolar lavage fluids obtained from normal controls and from patients with idiopathic pulmonary fibrosis, non-specific interstitial pneumonia, hypersensitivity pneumonitis, and sarcoidosis. Results: MOXD1 mRNA levels were significantly higher in IPF-fibroblasts than those in controls. MOXD1 protein levels were significantly higher in the IPF patients than those in the NC [2.07 (1.24-3.45 ng/mL) vs. 5.05 (2.26-15.84 ng/mL), p=0.0005], those in the NSIP [0.86 (0.31-1.88 ng/mL), p=0.0002], those in the sarcoidosis [0.7 (0.14-9.95 ng/mL), p=0.006], but there were no difference to compared HP (p=0.653). Cut-off values of 3.9 ug/mL and 3.73 ug/mL possessed 71.6% and 72.2% accuracy for the discrimination of IPF from NC and the other lung diseases, respectively. IPF subjects with MOXD1 levels >5.968 ug/mL showed shorter survival compared to those with lower levels (p=0.0000083). Conclusion: MOXD1 may be associated with the development of IPF. Furthermore, the MOXD1 in BAL fluids may be useful for differentiating IPF from other chronic interstitial lung diseases.

Cu-30 Zn 황동의 30 % 냉간압연에 따른 변형의 결정입별관찰

백동규 대한금속재료학회(대한금속학회) 1982 대한금속·재료학회지 Vol.20 No.12

From slip traces produced by microhardness indentation, orientation of grains in a commercial Cu-30 Zn brass has been determined before and after rolling reduction of 30% at room temperature. Different deformation structures were observed on grains, where the Schmid factor analysis shows that they depend on the number of active slip systems at rolling. When the primary slip system is unique, deformation is homogeneous, but when more than one slip system are equally active, deformation is heterogeneous; in particular, large, distinct subgrains can be formed. It was also observed that when a twin axis is parallel to the transverse direction, regions contiguous to the twin boundary rotate together, thus remaining a narrow band of twin couple after rolling. From these observations, it was concluded that slip mechanism, during the first stage of cold-rolling, may include (1) multi-directional rotations on the same grain and (2) a binding force of the twin boundary on contiguous regions.

FCC 금속 표면의 결정방향 분석을 위한 Microhardness 의 이용

백동규 대한금속재료학회(대한금속학회) 1980 대한금속·재료학회지 Vol.18 No.3

Microhardness로 발생시킨 slip trace를 다결정 FCC금속표면의 결정방향규명에 이용하는 한 구체적기술과 {111} pole궤도망을 사용하는 새로운 그라프방법을 제시하였다. 한개 Cu-6% Al시편을 실예로 하여 microhardness indentation주입방법, slip trace에서 얻을 수 있는 분석자료의 종류와 처리방법, 규명가능한 결정체 최소면적, 분석결과의 정밀도 등을 설명하고 또 한편으로 microhardness에 의한 slip trace분석에서는 slip trace의 수가 3개뿐일 때에도 유일한 해를 선별할 수 있음을 보여준다. 본 실예의 분석결과 twin의 현저한 불완전성 및 부식현미경사진상 결정체의 명암과 결정방향간의 연관성이 있음을 관찰하게 된다. A method is given for the determination of the surface orientation of polycrystalline face centered cubic metals from slip traces produced by the microhardness. At the same time, a new graphical method using a loci net of the {111} poles is proposed. An example of the use of the microhardness is presented on a Cu-6% Al specimen, where relevant matters such as the locating of the microhardness indentations, the kind and processing of informations obtainable from the slip traces, the minimum surface area of a crystal required and the accuracy of results are described. It is seen that when slip traces by the microhardness are concerned, the orientation of a crystal can be determined unambiguously even if there are only three slip trace directions. Observation of a considerable twin imperfection and of a correlation between the bright-dark separation of crystals on the etched surface and the crystal orientations is made as result of the determination of the orientation in this example.

FCC {111} 선과 오일러 각 (2) : 결정입회전 Grain Rotation

백동규 대한금속재료학회(대한금속학회) 1986 대한금속·재료학회지 Vol.24 No.5

In this second part of two articles dealing with the orientation determination of the FCC structure using non-parallel {111} traces, a method of calculation is given for the determination of the elation of grains, defined by the Euler angles of the orientations of the grains before and after the rotation. In the calculation of these Euler angles, two equally plausible solutions result in general. This ambiguity is due to the inherent existence of the mirror-image in the determination of the FCC crystal orientation using non-parallel {111} traces. In cases where rotation is by single slip deformation, however, this state of double solutions may be overcome so that the rotation is determined unambiguously.

기동륜 스프라켓 재료이용률 향상 Near Net Shape 형단조 공정 연구

백동규,최성규,김현민,박용복,김대원,박훈재,최호준,최석우,임성주 한국소성가공학회 2010 단조 심포지엄 Vol.2010 No.6

A . C . 통전 열간압축법에 의한 n형 95%Bi2Te3 + 5% Bi2Se3 열전재료의 열전특성

백동규,김익수,황창원 대한금속재료학회(대한금속학회) 1998 대한금속·재료학회지 Vol.36 No.4

The n-type thermoelectric material of 95% Bi₂Te₃+5% Bi₂Se₃ doped with CuBr were prepared by hot pressing method assited A. C current. Property variations of materials were investigated as a function of variables, such as hot pressing time and powder size. By this method, it is possible to minimize the defects arising from the vaporization of Te due to the very short processing time. At the conditions of hot pressing at 400℃ for 2 min. under 150Kgf/㎠, and the particle size of 70 to 125㎛ range of powder, the maximum Z value (figure of merit) was 2.2 x 10^(-3)K^(-1).

피스톤크라운 성형기술개발

최성규,백동규,민규영,박용복,최호준,임성주,최석우 한국소성가공학회 2008 단조 심포지엄 Vol.2008 No.6

가압소결된 다결정 $Bi_2Te_3-Bi_2Se_3$ 열전재료의 열전특성

황창원,홍인근,백동규,최승철,Hwang, C.W.,Hong, I.G.,Paik, D.K.,Choi, S.C. 한국결정성장학회 1994 한국결정성장학회지 Vol.4 No.4

$Bi_2Te_3$계 열전반도체에서 단결정재료는 성능이 우수한 반면에 그 제조에 있어서 긴 공정시간과 그에 따른 구성성분의 손실이 있다. 본 연구에서는 짧은 공정시간으로 단결정 $Bi_2Te_3$계 열전반도체 제조 공저으이 단점을 극복하기 위해서 $Bi_2Te_3$계 열전반도체 제조 공저의 단점을 극복하기 위해서 $Bi_2Te_3$계 열전반도체를 교류 통전 가압법으로 제작하였다. 이 소결 방법에서는 소결시간이 다른 방법과 비교하여 짧기 때문에 Te의 증발로 인한 결함의 발생을 줄일 수 있었으며 제조공정시 재료의 손실도 최소화할 수있었다. 가압 소결한 95 mol% $Bi_2Te_3-5 mol% Bi_2Se_3$ 다결정 열전반도체의 최적의 소결조건은 분말입도, 소결온도, 시간, 압력별로 각각 $125~250 {\mu}m, 400^{\circ}C$, 2분, $1500Kgf/cm^2$이고, 이조건에서 열전성능지수 $Z=2.2{\times}10^{-3}/K$이다. Bimuth telluride base thermoelectrics are prepared by AC current applied hot pressing method. It is possible to minimize the defects arising from the vaporization of Te, thanks to the very short processing time compared to the single crystal growing method. The optimum conditions for the AC applied hot pressing of 95 mol% $Bi_2Te_3-5 mol% Bi_2Se_3$ thermoelectrics are sintering at $400^{\circ}C$, for 2 minutes, under 1500 kgf/$\textrm{cm}^2$, with the particle size of $125 to 250 {\mu}m$, range of powder. The resultant Z value (figure of merit) was $2.2{\times}10^{-3}/K$.