• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.821-825
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• 2009

Recently, transparent ZnO-based TFTs have attracted much attention for flexible displays because they can be fabricated on plastic substrates at low temperature. We report the fabrication and characteristics of ZnO TFTs having different channel thicknesses deposited at low temperature. The ZnO films were deposited as active channel layer on $Si_3N_4/Ti/SiO_2/p-Si$ substrates by RF magnetron sputtering at $100^{\circ}C$ without additional annealing. Also, the ZnO thin films deposited at oxygen partial pressures of 40%. ZnO TFTs using a bottom-gate configuration were investigated. The $Si_3N_4$ film was deposited as gate insulator by PE-CVD at $150^{\circ}C$. All Processes were processed below $150^{\circ}C$ which is optimal temperature for flexible display and were used dry etching method. The fabricated devices have different threshold slop, field effect mobility and subthreshold slop according to channel thickness. This characteristics are related with ZnO crystal properties analyzed with XRD and SPM. Electrical characteristics of 60 nm ZnO TFT (W/L = $20\;{\mu}m/20\;{\mu}m$) exhibited a field-effect mobility of $0.26\;cm^2/Vs$, a threshold voltage of 8.3 V, a subthreshold slop of 2.2 V/decade, and a $I_{ON/OFF}$ ratio of $7.5\times10^2$.

• Proceedings of the IEEK Conference
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• 2004.06b
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• pp.363-366
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• 2004

PZT thin films were formed by rf-magnetron sputtering on $Pt/Ti/SiO_2/Si$ substrate. Bulk PZT target containing $5\%$ excess PbO was used. They were formed with in-situ process at $650^{\circ}C$ as total thickness of 175 and 250 nm after the depositing of thin PZT films at room temperature, i. e. 2-step Sputtering. It was found that the ferroelectric perovskite phase is formed at $650^{\circ}C$ by XRD and the interface between room temp.-layer and $650^{\circ}C$ -layer is not existent. In the samples undergoing 2-step sputtering the dielectric constant was 600 or more and the leakage current density was $2{\times}10^{-7}A/cm^2$. So, we found that the room temp.-layer on the bottom electrode stabilize the underlaid layers.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.533-534
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• 2010

• The Korean Journal of Archival Studies
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• no.3
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• pp.65-89
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• 2001

We, at The Korea Democracy Movement Archives opened temporarily at SungKongHoe University(SKHU), have currently collected about 100,000 recorded materials of democratization movement related with labor, farmer, civilian, human rights, peace, unification, young people, student and women's movements by investigating, collecting and receiving donations from civil organizations and individuals, and about 70,000 data out of this 100,000 data were converted into computer files. The Korea Democracy Movement Archives(temp) at SKHU has a significance in that it is the first archive opened by an organization. Furthermore, the opening of this Archive means the expansion of awareness on recording culture and accumulation of the achievements of the democratization movement in Korea. However, many obstacles still remain in the establishment of this Archive in a full-scale. This article examined many theoretical and realistic obstacles posed to the archivists, who are the professionals responsible for record management, in process of establishing the Archive, and the role and future perspectives of the archivists at The Korea Democracy Movement Archives(temp). The first obstacles in the process of organizing and separating the recorded materials at the Archive is a difficulty in the description of classifying the different movement organizations. The second obstacle is a difficulty in specifically applying the international standard, ISAD(G), of record description in the process of establishing the description items. Through many trials and errors, we need to try to confirm the description befitting. The Korea Democracy Movement Archives through continuous adjustment and complementary measures. The third obstacle is a difficulty in estimating the range and physical and quantitative amount of the recorded materials since the collection of recorded materials is complete. Thus, the answers to these problems lie in continuous efforts to establish a creative classification system befitting the democratization movement in Korea in the process of many trials and errors and endeavor. The evaluation classification done by archivists is a creative act forming record heritage, and archivists need to form record heritage reflecting the evaluation system of a certain period. Moreover, they transmit the shape of the current era in a maximum scale to the future by using the minimum amount of records. An archivist is responsible for two tasks, i.e., preserving a record and making other people to utilize the record by working with record. However, We, at The Korea Democracy Movement Archives(temp), have an additional task of contributing to the democratization movement in korea that has not ended by collecting, preserving and making people to utilize the fragments of memory in the recent history of Korea by establishing the Archives.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.530-535
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• 1999

In recently, annealing process of cold rolled sheet tend to change to continuous annealing process for improving quality, saving yield. In the meantime as demand for various kind and small lot of products has been increasing, batch annealing has been appreciated for its small restriction for the operation. So, we tested on the effect for the proper heating temperatures, heating time of cycle, cooling time and total cycle time in this annealing process of hi tensile strength steel for automobile. As a result of several investigation. we confirmed for the following characteristics; In this process, we knew that 68$0^{\circ}C$ is suitable for this heating temp. cycle heating time of 38 Hr, cooling time of 31 Hr and total cycle time of 70 Hr. Still more, we could know that it is proper for cold rolling before annealing to be managed by 7 pass because of the act on high pressure.

• Transactions of Materials Processing
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• v.27 no.5
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• pp.281-288
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• 2018

This study deals with the microstructure and tensile properties of 600 and 700 MPa-grade high-strength seismic reinforced steel bars. High-strength seismic resistant reinforced steel bars (SD 600S and SD 700S) were fabricated by TempCore process, especially the SD 700S specimen was more rapid cooled than the SD 600S specimen during the TempCore process. Although two specimens had microstructure of tempered martensite in the surface region, the SD 600S specimen had ferrite-degenerated pearlite in the center region, whereas the SD 700S specimen had bainite-ferrite-degenerated pearlite in the center region. Therefore, their hardness was highest in the surface region and revealed a tendency to decrease from the surface region to the center region because tempered martensite has higher hardness than ferrite-degenerated pearlite or bainite. The SD 700S specimen revealed higher hardness in the center region than SD 600S specimen because it contained a larger amount of bainite as well as ferrite-degenerated pearlite. On the other hand, tensile test results indicated the SD 600S and SD 700S specimens revealed continuous yielding behavior because of formation of degenerated pearlite or bainite in the center region. The SD 600S specimen had a little higher tensile-to-yield ratio because the presence of ferrite and degenerated pearlite in the center region and the lower fraction of tempered martensite enhance work hardening.

• Korean Journal of Materials Research
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• v.28 no.7
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• pp.391-397
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• 2018

This study deals with the microstructure and tensile properties of 700 MPa-grade high-strength and seismic reinforced steel bars. The high-strength reinforced steel bars (600 D13, 600 D16 and 700 D13 specimens) are fabricated by a TempCore process, while the seismic reinforced steel bar (600S D16 specimen) is fabricated by air cooling after hot rolling. For specimens fabricated by the TempCore process, the 600 D13 and 600 D16 specimens have a microstructure of tempered martensite in the surface region and ferrite-pearlite in the center region, while the 700 D13 specimen has a microstructure of tempered martensite in the surface region and bainite in the center region. Therefore, their hardness is the highest in the surface region and shows a tendency to decrease from the surface region to the center region because tempered martensite has a higher hardness than ferrite-pearlite or bainite. However, the hardness of the 600S D16 specimen, which is composed of fully ferrite-pearlite, increases from the surface region to the center region because the pearlite volume fraction increases from the surface region to the center region. On the other hand, the tensile test results indicate that only the 700 D13 specimen with a higher carbon content exhibits continuous yielding behavior due to the formation of bainite in the center region. The 600S D16 specimen has the highest tensile-to-yield ratio because the presence of ferrite-pearlite and precipitates caused by vanadium addition largely enhances work hardening.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.141-148
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• 2016

This paper presents an overview of worldwide electric power development and National $700^{\circ}C$ Hyper Supercritical coal-fired power generation(HSC) focus on materials and manufacturing process. To Increase the efficiency of electric power generation, It is necessary to increase steam temperature and pressure. In that case, New material and manufacturing process shall be developed for boiler and turbine component in high temperature and pressure operating condition. Therefore, Much Efforts in worldwide are progressing to develop materials and manufacturing technology and to build and operate an HSC.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.32-40
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• 2001

It is desirable to reduce the amounts of fresh water and reuse the recycled water in papermaking process. In an attempt to improve the efficiency of recycling water refining treatment and to enhance the productivity of OCC recycling mill, up flow anaerobic sludge blanket(UASB) reactor was developed and introduced to Korea recently. In order to maximize the operating efficiency and minimize the adverse side effects it is imperative to estimate and evaluate the total effects of new system, UASB on the whole OCC recycling process. This study was carried out with a view to investigate the effects of the high temperature and alkalinity of process water on the quality ad productivity of testliner of OCC recycling mill which is equipped with UASB reactor and almost closed. Another object of this study was searching for the best available use of UASB treated process water. The results were as follows; Reuse of UASB treated water characterized with high temp and alkalinity was useful to improve the strength and drainage properties of recycled OCC owing to its good points of promoting OCC disintegration and reducing the calcium hardness of process water. However, it might not be avoidable to induce the increase of dissolved solids in process water in accordance with direct introducing of UASB treated water into the former stage of OCC stock preparation. So it would be advisable to adopt the UASB treated water in the stage of clean, screened OCC stock.

• Korean Chemical Engineering Research
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• v.59 no.4
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• pp.611-625
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• 2021

Mg crowns were manufactured using domestic dolomite (Ca·Mg(CO₃)₂) (20~30 mm). In order to manufacture the calcined dolomite (CaO·MgO), (a) electric furnace (950 ℃, 480 min) and (b) microwave furnace (950 ℃, 60 min) processes were used. As a result of XRD analysis, it was analyzed as (a) CaO 56.9 wt%, MgO 43.1 wt% by electric furnace process and (b) CaO 55 wt%, MgO 45 wt% by microwave furnace process. Even when the decarbonation reaction time of dolomite was shortened by 1/8 in microwave furnace process compare with electric furnace process, the calcined dolomite could be produced. The hydration reaction (ASTM C 110) is a standard for the hydration reactivity of calcined dolomite, and the calcined dolomite produced by electric furnace process showed a high hydration reactivity (max temp 79.8 ℃/1.5 minutes). Such hydration reactivity was occurred by only CaO hydration reaction and that was confirmed by XRD analysis. The calcined dolomite produced by microwave furnace process showed low hydration reactivity (max temp 81.7 ℃/19.5 minutes). Such low hydration reactivity was occurred by CaO and MgO hydration reaction due to the hydration reaction of CaO thereafter occurring of the hydration reaction of MgO, and that was confirmed by XRD analysis. The prepared Mg crown were 58.8 g and 74.6 g by electric furnace and microwave furnace processes, respectively, under the reaction conditions of 1,230 ℃, 60 min, 5 × 10^-2 torr by silicothermic reduction.