• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.4
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• pp.173-178
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• 2003

In this paper, we studied the physical and electrical characteristics of $\textrm{WSi}_{x}$ thin film with respect to the adoption of the DCS (dichlorosiliane) post flow and the variation of deposition temperature. XRD measurements show that as deposited thin film has a hexagonal structure regardless of deposition Process. However, we find that the phase of thin film has changed to a tetragonal structure after the heat treatment at $680^{\circ}C$. Adoption of DCS post flow and increment of deposition temperature result in the increments of Si/W composition ratio. These conditions also result in the increment of sheet resistance by the amount 3.0~4.2$\Omega$/$\square$, but give the tendency in the decrement of stress by 0.27~0.3 E10dyne/$\textrm{cm}^2$. We also find that the contact resistance of word line and bit line interconnection was decreased by the amount 5.33~16.43$\mu$$\Omega$-$\textrm{cm}^2$, when applying DCS post flow and increasing deposition temperature.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.343-349
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• 2009

This study was designed to simplify a cryopreservation program for embryonic stem cells (ESCs) by selection of cooling method and cryoprotectant. Commercially available mouse E14 embryonic stem cells (ESCs) were cryopreserved with various protocols, and morphology and viability of the frozen-thawed ESCs and their reactive oxygen species (ROS) production were subsequently monitored. Post-thaw colony-formation of ESCs was detected only after a slow freezing using dimethyl sulfoxide (DMSO) by stepwise placement of a freezing container into a $-80^{\circ}C$ deep freezer and subsequently into -$196^{\circ}C$ liquid nitrogen, while no proliferation was detected after vitrification. When the simplified protocol was employed, the replacement of DMSO with a mixture of DMSO and ethylene glycol (EG) further improved the post-thaw survival. ROS generation in ESCs frozen-thawed with the optimized protocol was not increased compared with non-frozen ESCs. The use of fresh mouse embryonic fibroblasts as feeder cells for post-thaw subculture did not further increase post-thaw cell viability. In conclusion, a simplified slow-freezing program without employing programmable freezer but using DMSO and EG was developed which maintains cell viability and colony-forming activity of ESCs during post-thaw subculture.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.23 no.4
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• pp.301-327
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• 2019

The proper orthogonal decomposition (POD) method for time-dependent problems significantly reduces the computational time as it reduces the original problem to the lower dimensional space. Even a higher degree of reduction can be reached if the solution is smooth in space and time. However, if the solution is discontinuous and the discontinuity is parameterized e.g. with time, the POD approximations are not accurate in the reduced space due to the lack of ability to represent the discontinuous solution as a finite linear combination of smooth bases. In this paper, we propose to post-process the sample solutions and re-initialize the POD approximations to deal with discontinuous solutions and provide accurate approximations while the computational time is reduced. For the post-processing, we use the Gegenbauer reconstruction method. Then we regularize the Gegenbauer reconstruction for the construction of POD bases. With the constructed POD bases, we solve the given PDE in the reduced space. For the POD approximation, we re-initialize the POD solution so that the post-processed sample solution is used as the initial condition at each sampling time. As a proof-of-concept, we solve both one-dimensional linear and nonlinear hyperbolic problems. The numerical results show that the proposed method is efficient and accurate.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.419-432
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• 2023

This paper studies the effects of porosity distributions on buckling and post-buckling behaviors of a functionally graded saturated porous (FGSP) circular plate. The plate is under the uniformly distributed radial loading and simply supported and clamped boundary conditions. Pores are saturated with compressible fluid (e.g., gases) that cannot escape from the porous solid. Elastic modulus is assumed to vary continuously through the thickness according to three different functions corresponding to three different cases of porosity distributions, including monotonous, symmetric, and asymmetric cases. Governing equations are derived utilizing the classical plate theory and Sanders nonlinear strain-displacement relations, and they are solved numerically via shooting method. Results are verified with the known results in the literature. The obtained results for the monotonous and symmetric cases with the asymmetric case presented in the literature are shown in comparative figures. Effects of the poroelastic material parameters, boundary conditions, and thickness change on the post-buckling behavior of the plate are discussed in details. The results reveal that buckling and post-buckling behaviors of the plate in the monotonous and symmetric cases differ from the asymmetric case, especially in small deflections, that asymmetric distribution of elastic moduli can be the cause.

• Computers and Concrete
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• v.32 no.2
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• pp.173-184
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• 2023

In this study, mechanical, flexural post-cracking, and torsional behaviors of recycled steel fiber-reinforced concrete (RSFRC) incorporating steel fibers obtained from recycling of waste tires were investigated. Initially, three concrete mixes with different fiber contents (0, 40, and 80 kg/m³) were designed and tested in fresh and hardened states. Subsequently, the flexural post-cracking behaviors of RSFRCs were assessed by conducting three-point bending tests on notched beams. It was observed that recycled steel fibers improve the post-cracking flexural behavior in terms of energy absorption, ductility, and residual flexural strength. What's more, torsional behaviors of four RSFRC concrete beams with varying reinforcement configurations were investigated. The results indicated that RSFRCs exhibited an improved post-elastic torsional behaviors, both in terms of the torsional capacity and ductility of the beams. Additionally, numerical analyses were performed to capture the behaviors of RSFRCs in flexure and torsion. At first, inverse analyses were carried out on the results of the three-point bending tests to determine the tensile functions of RSFRC specimens. Additionally, the applicability of the obtained RSFRC tensile functions was verified by comparing the results of the conducted experiments to their numerical counterparts. Finally, it is noteworthy that, despite the scatter (i.e., non-uniqueness) in the aspect ratio of recycled steel fiber (as opposed to industrial steel fiber), their inclusion contributed to the improvement of post-cracking flexural and torsional capacities.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.1
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• pp.64-71
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• 2020

eFuse OTP memory IP is required to trim the analog circuit of the gate driving chip of the power semiconductor device. Conventional NMOS diode-type eFuse OTP memory cells have a small cell size, but require one more deep N-well (DNW) mask. In this paper, we propose a small PMOS-diode type eFuse OTP memory cell without the need for additional processing in the CMOS process. The proposed PMOS-diode type eFuse OTP memory cell is composed of a PMOS transistor formed in the N-WELL and an eFuse link, which is a memory element and uses a pn junction diode parasitic in the PMOS transistor. A core driving circuit for driving the array of PMOS diode-type eFuse memory cells is proposed, and the SPICE simulation results show that the proposed core circuit can be used to sense post-program resistance of 61㏀. The layout sizes of PMOS-diode type eFuse OTP memory cell and 512b eFuse OTP memory IP designed using 0.13㎛ BCD process are 3.475㎛ × 4.21㎛ (= 14.62975㎛2) and 119.315㎛ × 341.95㎛ (= 0.0408mm2), respectively. After testing at the wafer level, it was confirmed that it was normally programmed.

• Korean System Dynamics Review
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• v.5 no.1
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• pp.99-110
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• 2004

Building trust assurance particularly in case of commercial practices in cyber space without physical contact is a very complex task to tackle. Several factors are interrelated in not necessarily technical but also societal dimensions over the entire process of e-commerce firm ex-ante through ex-post transactions. This paper attempts first to brief the substance of e-trust and examine the natuure of its complexity by using system dynamics simulation technique, followed by its current address and the future directions to move. A framework of 3 x 3 matrixes is deviaed and the key issues of e-trust are mapped into cross-cells of the table. The paper also includes some possible suggestions on the matter of trust assurance especially for B2C and B2B in policy wise and organizational perspective from the context of international collaboration.

• Journal of the Korean Association of Geographic Information Studies
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• v.7 no.3
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• pp.35-47
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• 2004

Telematics and LBS is one of rapidly emerged technology domains. In order to efficiently construct them, moving object technology which manages huge volume of real-time location data is required. Especially, the query which obtains special sorts of information closely related to the detailed applications is required in order to effectively retrieve and analyze the location data for moving object in logistics domain. It has also complex query structure comparing to the conventional database query. The approach using the standard database query language, like SQL, can be considered as an effective alternative choice. In this paper, we not only propose a new query language, entitled as MOQL based on SQL, for the query processing of the vehicle monitoring and control in e-Logistics but also design and implement the query processor.

• Korean Journal of Applied Biomechanics
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• v.33 no.1
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• pp.17-24
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• 2023

Objective: The purpose of this study was to investigate the effects of different frequency on of knee extensors muscle function during electrical muscle stimulation (EMS). Method: In this research, 40 subjects who have no musculoskeletal disorder, and less than a year workout experience were recruited in order to analyze effects of EMS with different stimulus frequency. Forty subjects were randomly divided into four groups of ten subjects in each group. A EMS training program with different frequencies (without EMS [WE], EMS with frequency 30 Hz [E30], EMS with frequency 60 Hz [E60], EMS with frequency 90 Hz [E90]) was assigned to each group. Throughout eight weeks of training, test subjects were simultaneously carried out knee extension exercises such as squat, leg extension, and leg-press while using EMS with different frequency (20 min, pulse width 250 ㎲, on-off ratio 1:1). Isokinetic knee extension strength, muscle activity of the rectus femoris (RF), the vastus medialis (VM), and the vastus lateralis (VL), and the median frequency of the RF, the VM, and the VL were collected and compared between pre and post training in order to find effects of applying EMS with different frequencies. For each dependent variable, a one-way ANOVA was to determine whether there were significant differences among four different conditions (p<.05). When a significant difference was found, post hoc analyses were performed using the contrast procedure. Results: When compared to WE and E90, E30 causes significant increase in isokinetic knee extension strength. No significant differences were found in EMG values across different EMS conditions. However, the median frequency of the VM in E30 was significantly increased than the corresponding value for WE. Conclusion: The results of this study showed that EMS training with 30 Hz frequency had positive effect on knee extensor. Based of the findings of the present study, EMS training with lower frequency may help the performer to focus on developing strength in knee extensor muscles.

• Economic and Environmental Geology
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• v.28 no.6
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• pp.559-569
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• 1995

Paleomagnetic data have been obtained from the Upper Carboniferous-Permian Komok and Cheolam Groups which are exposed in the E-W trending Baekunsan syncline comprising the Pyongan Supergroup in eastern Korea. Two ancient components of magnetization are recovered in these groups by detailed thermal demagnetization: a post-folding component and a pre-folding component. The post-folding component $(D/I=54.0/54.6^{\circ},\;{\alpha}_{95}=14.6^{\circ})$ is a magnetic signature of the Oaebo Orogeny and appears to have been confined mainly to Cretaceous Normal Superchron. It has been rotated clockwise since this magnetization has been acquired. The pre-folding components ($D/I=341/-9.2^{\circ},\;{\alpha}_{95}=7.2^{\circ})$, paleopole at $335.7^{\circ}E$, $44.6^{\circ}N$ for Upper Carboniferous; $D/I=358.3/11.5^{\circ},\;{\alpha}_{95}=6.3^{\circ})$, paleopole at $311.9^{\circ}E$, $58.7^{\circ}N$ for Permian) pass fold and reversal tests. These paleopoles correspond only with the contemporaneous poles from the North China Block: they are removed from the poles from the South China Block. If the results of this study are corrected for the clockwise rotation deduced from the prefolding component, the enhanced agreement with North China Block can be achieved. Therefore, a first-order correlation between the Korean Peninsula and North China at least since Upper Paleozoic times is identified in this study.