• 한국전기전자재료학회논문지
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• 제11권2호
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• pp.128-132
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• 1998

2/65/35 PLZT stock solution prepared by Sol-Gel processing was spin-coated on ITO coated glass and annealed by RTA(Rapid Thermal Annealing). The crystal structure of films was reported based on the observation of crystallization process and microstructure of the film fabricated at different fabrication condition. Films were crystallized into rhombohedral structure by annealing at $750^{\circ}C$ for 5 min. As the annealing temperature increased, the size of rosette structure of the films was grown up from $2.4{\mu}m$ to $15{\mu}m$, dielectric constant was increased, coercive field was decreased 33.82 kV/cm, remnant polarization was increased to 39.84 ${\mu}C/cm^2$ and Optical transmittance was decreased.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.383-383
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• 2011

We fabricated thermal annealing-free polymer solar cells (PSC) by processing with additive and applied to flexible substrates. The 1, 8-Diiodooctane of 3 vol% blended with active solution resulted in enhancement of $J_{SC}$ due to increase of light absorption and hole mobility as improving the crystallinity of P3HT. In addition, the $V_{OC}$ of PSCs with additive was improved by inserting $TiO_2$ layer without any treatment. The $TiO_2$ layer prevented the direct contact between active layer and Al electrode and reduced the charge recombination near Active/Al interface. It was confirmed by calculation of J0 and photo-voltage transient measurement. The power conversion efficiencies of annealing-free PSCs using additive for ITO glass and flexible (ITO PEN) substrate were obtained 3.03% and 2.45%, respectively.

• 산업경영시스템학회지
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• 제40권2호
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• pp.92-98
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• 2017

Data clustering determines a group of patterns using similarity measure in a dataset and is one of the most important and difficult technique in data mining. Clustering can be formally considered as a particular kind of NP-hard grouping problem. K-means algorithm which is popular and efficient, is sensitive for initialization and has the possibility to be stuck in local optimum because of hill climbing clustering method. This method is also not computationally feasible in practice, especially for large datasets and large number of clusters. Therefore, we need a robust and efficient clustering algorithm to find the global optimum (not local optimum) especially when much data is collected from many IoT (Internet of Things) devices in these days. The objective of this paper is to propose new Hybrid Simulated Annealing (HSA) which is combined simulated annealing with K-means for non-hierarchical clustering of big data. Simulated annealing (SA) is useful for diversified search in large search space and K-means is useful for converged search in predetermined search space. Our proposed method can balance the intensification and diversification to find the global optimal solution in big data clustering. The performance of HSA is validated using Iris, Wine, Glass, and Vowel UCI machine learning repository datasets comparing to previous studies by experiment and analysis. Our proposed KSAK (K-means+SA+K-means) and SAK (SA+K-means) are better than KSA(K-means+SA), SA, and K-means in our simulations. Our method has significantly improved accuracy and efficiency to find the global optimal data clustering solution for complex, real time, and costly data mining process.

• Bulletin of the Korean Chemical Society
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• 제20권8호
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• pp.875-878
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• 1999

A new concept ？？soft solution processing？？ has been introduced to fabricate advanced solid state materials in an economical, environmentally friendly, and energy and material efficient way. The prepared films show the desired and prospective properties despite of low temperature synthesis and no post-synthesis annealing. Successful examples demonstrate that soft solution processing is capable of preparing advanced materials with planned properties through the easy control of reaction conditions in a suitable aqueous solution in a single synthetic step without huge energy consumption and without any sophisticated equipment.

• Journal of Magnetics
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• 제16권1호
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• pp.10-14
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• 2011

This study reports on Co/$Co_2$MnSn two-phase magnets. The Co/$Co_2$MnSn two-phase magnet has Co precipitates in a $Co_2MnSn$ Heusler alloy matrix, in which the two phases are exchange-coupled at the phase boundary. The as-casted Co/$Co_2$MnSn system, which has Co-Mn solid solution precipitates in a $Co_2$MnSn Heusler alloy matrix, showed that the Co solid solution precipitates are crystallographically coherent and there is exchange coupling at the phase boundary. To form pure Co precipitates by removal of Mn solute atoms in Co-Mn solid solution, annealing was carried out 48 hours at $870^{\circ}C$. After annealing, the low $T_c$ and low magnetization phase of the Co-Mn solid solution became a high $T_c$ and high magnetization phase of hexagonal Co.

• 대한기계학회논문집
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• 제17권5호
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• pp.1183-1192
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• 1993

본 연구에서는 다음과 같은 두가지 관점에서 공구경로 최적화를 위한 기존 방 법의 문제점을 검토하고 이의 개선 방안을 제시하였다. 첫째, 기존의 공구경로 산출 방법에서는 고려되지 않는 공구대의 공구 장착 현황(turret configuration)이 최적화 과정에서 고려되어야 한다. 둘째로, 제작과 관련한 구속조건(manufacturing con- straints)이 최적화 과정에 직접 반영되어야 한다.

• Smart Structures and Systems
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• 제13권3호
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• pp.389-406
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• 2014

Optimal sensor placement techniques play a significant role in enhancing the quality of modal data during the vibration based health monitoring of civil structures, where many degrees of freedom are available despite a limited number of sensors. The literature has shown a shift in the trends for solving such problems, from expansion or elimination approach to the employment of heuristic algorithms. Although these heuristic algorithms are capable of providing a global optimal solution, their greatest drawback is the requirement of high computational effort. Because a highly efficient optimisation method is crucial for better accuracy and wider use, this paper presents an improved simulated annealing (SA) algorithm to solve the sensor placement problem. The algorithm is developed based on the sensor locations' coordinate system to allow for the searching in additional dimensions and to increase SA's random search performance while minimising the computation efforts. The proposed method is tested on a numerical slab model that consists of two hundred sensor location candidates using three types of objective functions; the determinant of the Fisher information matrix (FIM), modal assurance criterion (MAC), and mean square error (MSE) of mode shapes. Detailed study on the effects of the sensor numbers and cooling factors on the performance of the algorithm are also investigated. The results indicate that the proposed method outperforms conventional SA and Genetic Algorithm (GA) in the search for optimal sensor placement.

• 한국전기전자재료학회논문지
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• 제33권2호
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• pp.93-98
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• 2020

We investigated the effect of a post-annealing process using ultraviolet (UV) light on the electrical properties of solution-processed InZnO (IZO) thin-film transistors (TFTs). UV light was irradiated on IZO TFTs for different time periods of 0s, 30s, and 90s. We measured transfer and retention stability curves to evaluate the performance of the fabricated TFTs. In addition, we measured height, amplitude, and phase AFM images to analyze changes in the surface and morphology of the devices. AFM measurements were performed by setting the drive amplitude of the cantilever tip to 47.9 mV in tapping mode, then dividing the device surface into 500 nm × 500 nm. In the case of IZO TFT irradiated with UV for 30s, the electron mobility and I_on/I_off ratio were improved, the threshold voltage was reduced by approximately 2 V, and the subthreshold swing also decreased form 1.34 V/dec to 1.11 V/dec.

• 열처리공학회지
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• 제17권5호
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• pp.283-292
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• 2004

The effects of the annealing parameters on microstructures were examined in a cold-rolled high strength steel containing 0.1% C, 0.5% Si, 1.5% Mn, and 0.04% Nb. It was impossible to avoid martensite in the microstructure even though the continuous annealing parameters were controlled. This indicates that the alloying elements such as silicon and manganese contributing to manganese equivalent($Mn_{eq}$) should be reduced to produce the ferrite-pearlite microstructure for the solid solution and precipitation hardened steel. It was found that a decrease in the rapid cooling temperature to $520^{\circ}C$ was effective to change the microstructure from ferrite-martensite to ferrite-pearlite-martensite. Typical dual-phase properties exhibiting a low yield ratio and a continuous yielding behavior were obtained when the rapid cooling temperature was in the range of $680^{\circ}C$ to $600^{\circ}C$. The critical volume fraction of martensite for the typical properties of dual-phase steel was about 11 percent.

• 국제학술발표논문집
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• The 2th International Conference on Construction Engineering and Project Management
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• pp.530-539
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• 2007

Many construction projects such as highways, pipelines, tunnels, and high-rise buildings typically contain repetitive activities. Research has shown that the Critical Path Method (CPM) is not efficient in scheduling linear construction projects that involve repetitive tasks. Linear Scheduling Method (LSM) is one of the techniques that have been developed since 1960s to handle projects with repetitive characteristics. Although LSM has been regarded as a technique that provides significant advantages over CPM in linear construction projects, it has been mainly viewed as a graphical complement to the CPM. Studies of scheduling linear construction projects with resource consideration are rare, especially with multiple resource constraints. The objective of this proposed research is to explore a resource assignment mechanism, which assigns multiple critical resources to all activities to minimize the project duration while satisfying the activities precedence relationship and resource limitations. Resources assigned to an activity are allowed to vary within a range at different stations, which is a combinatorial optimization problem in nature. A heuristic multiple resource allocation algorithm is explored to obtain a feasible initial solution. The Simulated Annealing search algorithm is then utilized to improve the initial solution for obtaining near-optimum solutions. A housing example is studied to demonstrate the resource assignment mechanism.