• 소성∙가공
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• 제31권5호
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• pp.273-280
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• 2022

Although the mechanical properties of high-entropy alloys depend on the annealing conditions, limited works were established to investigate the annealing effect on the mechanical properties of Mo-added high-entropy alloys. Therefore, in the present work, the annealing effects on the microstructural evolution and mechanical properties of Mo-added high-entropy alloy were investigated. As a result, incomplete recrystallization from the limited annealing time not only suppresses deformation-induced phase transformation during cryogenic tensile test but also induces a deformation instability that results into the ductility reduction compare with the fully recrystallized sample. This result represents adjustment of annealing time is useful to control both transformation-induce plasticity and deformation instability of high-entropy alloys, and this can be applied to control the mechanical properties of metallic alloys by combining pre-straining and subsequent annealing.

• Applied Science and Convergence Technology
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• 제23권6호
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• pp.371-375
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• 2014

Diffusion coefficient of Fe in polycrystalline host ZnSe as a mid-IR gain medium has been measured in the annealing temperature ranges of 850 to $950^{\circ}C$. The synthesis of the samples was carried out in quartz ampoule in which the Fe thin film deposited by physical vapor evaporation method on the ZnSe. One can realize that the diffusion coefficient strongly depends on the surface active surfactants through the cleaning process and the substrate temperature during the thin film deposition leading to $2.04{\times}10^{-9}cm^2/s$ for $Fe^{2+}:ZnSe$. The Annealing temperature dependence of the Fe ions diffusion in ZnSe was used to evaluate the activation energy, $E_a$=1.39 eV for diffusion and the pre-exponential factor $D_0$ of $13.5cm^2/s$.

• 열처리공학회지
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• 제33권4호
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• pp.161-172
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• 2020

The tensile property of A5082 and A6060 aluminium wrought alloys was investigated, in terms of the strain rate sensitivity on alloy conditions by heat treatment and bake hardenability on pre-strain prior to strain ageing. The tensile test was carried out in a range of strain rate of 4.17 × 10^-5 s^-1 ~ 4.17 × 10^-5 s^-1 in room temperature and the nominal range of pre-strain was 3.0 ~ 10.5%. The tensile deformation of A5082 alloys is characterized as typical case of dynamic strain ageing with negative strain rate sensitivity for all conditions, and the tensile strength indicates a similar level regardless of alloy conditions, except only in full annealed condition. The stress-relief annealing on A6060 alloys can induce practical decrease in strength level of over approximately 100 MPa without any ductility loss, compared to as-rolled condition, while a full annealed and aged condition leads remarkable strengthening effect with the decrease of tensile elongation. Additionally, the bake hardenability of A5082 alloy by strain ageing indicates a negative dependence upon the increase of pre-strain, while A6060 alloy exhibits a positive sign even in low level relatively compared with conventional SPCC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.529-532
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• 1988

This paper proposes a graph matching algorithm based on simulated annealing, which assures the globally optimal solution for circuit partitioning for the placement in the rectilinear region occurring as a result of the pre-placement of some macro cells, or onto the nonplanar surface in some military or space applications. The circuit graph ($G_{C}$) denoting the circuit topology is formed by a hierarchical bottom-up clustering of cells, while another graph called region graph ($G_{R}$) represents the geometry of a planar rectilinear region or a nonplanar surface for circuit placement. Finding the optimal many-to-one vertex mapping function from $G_{C}$ to $G_{R}$, such that the total mismatch cost between two graphs is minimal, is a combinatorial optimization problem which was solved in this work for various examples using simulated annealing.

• 한국진공학회지
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• 제4권S2호
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• pp.90-94
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• 1995

Defects introduced by Si, Ge preamorphization and their effects on the dopant diffusion and electrical characteristics. Good crystalline quality are obtained after the annealing of Ge ion double implanted samples. The defect clusters under the a/c interface are expected to extend up to the deep in the Si ion implanted samples. The dislocation loops near the junction absorb the interstitial Si atoms resolving from the defect cluster and result in the prevention of enhanced boron diffusion near the tail region of boron profile and show good reverse current charactristics.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.318.1-318.1
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• 2013

Nowadays Cu2ZnSnS4 (CZTS) solar cell is attracting a lot of attention as a strong alternative to CIGS solar cell due to nontoxic and inexpensive constituent elements of CZTS. From various processes for the fabrication of CZTS solar cell, solution-based deposition of CZTS thin films is well-known non-vacuum process and many researchers are focusing on this method because of large-area deposition, high-throughput, and efficient material usage. Typically the solution-based process consists of two steps, coating of precursor solution and annealing of the precursor thin films. Unlike vacuum-based deposition, precursor solution contains unnecessary elements except Cu, Zn, Sn, and S in order to form high quality precursor thin films, and thus the precise control of precursor thin film preparation is essential for achieving high efficient CZTS solar cells. In this work, we have investigated the effect of preparation condition of CZTS precursor thin films on the performance of CZTS solar cells. The composition of CZTS precursor solution was controlled for obtaining optimized chemical composition of CZTS absorber layers for high-efficiency solar cells. Pre-annealing process of the CZTS precursor thin films was also investigated to confirm the effect of thermal treatment on chemical composition and carbon residues of CZTS absorber layers. The change of the morphology of CZTS precursor thin film by the preparation condition was also observed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집 디스플레이 광소자 분야
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• pp.173-176
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• 2005

Teijin사의 HT100-B60의 폴리카보네이트(polycarbonate) $100{\mu}m$, I-Component사의 PES(polyethersulfone) $200{\mu}m$, Ferrania사의 PAR(polyacrylate) $100{\mu}m$와 $200{\mu}m$를 사용하였다 열팽창계수의 차이로 인해 공정상 기판의 가열과 냉각시 열응력이 발생하여 기판의 크랙발생의 원인이 된다. 이를 최소화하기 위해 모든 공정이 시작하기 전에 pre-annealing을 통해 plastic 기판의 시간별 공정을 실시하였다. plastic film의 annealing time은 0h, 12h, 24, 40h, 50h, 60h, 70h, 80h으로 사간을 달리하여 오븐 안의 진공상태를 조성하여 실험하였다. Thermal evaporator로 Al을 약 170nm 증착하였으며 (주)동진 세미캠의 DTFR-1011s DR LCD용 감광액을 Spin Coating Spread(500rpm/6sec), Spin(3000rpm/20sec)으로 coating하였다.

• International Journal of Quality Innovation
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• 제6권1호
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• pp.109-118
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• 2005

The parameter design is the most emphasized measure by researchers for a new products development. It is critical for makers to achieve simultaneously in both the time-to-market production and the quality enhancement. However, there are difficulties in practical application, such as (1) complexity and nonlinear relationships co-existed among the system's inputs, outputs and control parameters, (2) interactions occurred among parameters, (3) where the adjustment factors of Taguchi's two-phase optimization procedure cannot be sure to exist in practice, and (4) for some reasons, the data became lost or were never available. For these incomplete data, the Taguchi methods cannot treat them well. Neural networks have a learning capability of fault tolerance and model free characteristics. These characteristics support the neural networks as a competitive tool in processing multivariable input-output implementation. The successful fields include diagnostics, robotics, scheduling, decision-making, prediction, etc. This research is a case study of spherical annealing model. In the beginning, an original model is used to pre-fix a model of parameter design. Then neural networks are introduced to achieve another model. Study results showed both of them could perform the highest spherical level of quality.

• Structural Engineering and Mechanics
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• 제36권6호
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• pp.759-783
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• 2010

In this paper, compressive strength of carbon fiber reinforced polymer (CFRP) confined concrete cylinders is formulated using a hybrid method coupling genetic programming (GP) and simulated annealing (SA), called GP/SA, and a robust variant of GP, namely multi expression programming (MEP). Straightforward GP/SA and MEP-based prediction equations are derived for the compressive strength of CFRP-wrapped concrete cylinders. The models are constructed using two sets of predictor variables. The first set comprises diameter of concrete cylinder, unconfined concrete strength, tensile strength of CFRP laminate, and total thickness of CFRP layer. The most widely used parameters of unconfined concrete strength and ultimate confinement pressure are included in the second set. The models are developed based on the experimental results obtained from the literature. To verify the applicability of the proposed models, they are employed to estimate the compressive strength of parts of test results that were not included in the modeling process. A sensitivity analysis is carried out to determine the contributions of the parameters affecting the compressive strength. For more verification, a parametric study is carried out and the trends of the results are confirmed via some previous studies. The GP/SA and MEP models are able to predict the ultimate compressive strength with an acceptable level of accuracy. The proposed models perform superior than several CFRP confinement models found in the literature. The derived models are particularly valuable for pre-design purposes.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.250-254
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• 2002

Intergranular corrosion of austenitic stainless steels is a conventional and momentous problem during welding and high temperature use. One of the major reasons for such intergranular corrosion is so-called sensitization, i.e., chromium depletion due to chromium carbide precipitation at grain boundaries. Conventional methods for preventing sensitization of austenitic stainless steels include reduction of carbon content in the material, stabilization of carbon atoms as non-chromium carbides by the addition of titanium, niobium or zirconium, local solution-heat-treatment by laser beam, etc. These methods, however, are not without drawbacks. Recent grain boundary structure studies have demonstrated that grain boundary phenomena strongly depend on the crystallographic nature and atomic structure of the grain boundary, and that grain boundaries with coincidence site lattices are immune to intergranular corrosion. The concept of "grain boundary design and control", which involves a desirable grain boundary character distribution, has been developed as grain boundary engineering. The feasibility of grain boundary engineering has been demonstrated mainly by thermomechanical treatments. In the present study, a thermomechanical treatment was tried to improve the resistance to the sensitization by grain boundary engineering. A type 304 austenitic stainless steel was pre-strained and heat-treated, and then sensitized, varying the parameters (pre-strain, temperature, time, etc.) during the thermomechanical treatment. The grain boundary character distribution was examined by orientation imaging microscopy. The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction. The frequency of coincidence-site-lattice boundaries indicated a maximum at a small strain. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanically-treated specimen than in the base material. An excellent intergranular corrosion resistance was obtained by a small strain annealing at a relatively low temperature for long time. The optimum parameters created a uniform distribution of a high frequency of coincidence site lattice boundaries in the specimen where corrosive random boundaries were isolated. The results suggest that the thermomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface.