• Reproductive and Developmental Biology
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• v.31 no.2
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• pp.61-69
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• 2007

This study was designed to evaluate effects of BSA, PVA, gonadotropins and follicle shell during IVM of porcine oocytes and subsequent development to the blastocyst stage after IVF. Cumulus oocyte complexes (COCs) were cultured in TCM-199 media containing 4 mg/ml BSA and 1 mg/ml PVA during IVM for 44 hr. To compare the effect of gonadotropins on oocyte maturation, COCs were cultured with FSH+LH, FSH, LH and FSH-LH-free media during IVM. respectively. Also, different number of follicle shells (0, 2, 4 and 6) was used to examine whether the presence of follicle shell in culture medium affects oocyte maturation. The percentages of fertilization and blastocyst formation, respectively, were higher in the medium containing the PVA (49.0 and 17.9%) than those containing the BSA (40.0 and 12.2%). Significantly higher rates of Mil oocytes were in the presence of FSH+LH and FSH (88.6 and 85.1 %) compared to other treatments (64.0 and 53.4% at LH and FSH-LH-free media). Co-culture with inverted follicle shells in 2 ml maturation medium enhanced the developmental competence of porcine oocytes. In conclusion, PVA could be used as a macromolecules instead of BSA, and FSH and follicle shell played important roles in maturation of porcine oocytes.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.468-475
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• 2018

In medical ultrasound imaging, frequency-dependent attenuation downshifts and reduces a center frequency and a frequency bandwidth of received echo signals, respectively. This causes considerable errors in quadrature demodulation (QDM), result in lowering signal-to-noise ratio (SNR) and contrast resolution (CR). To address this problem, adaptive dynamic QDM (ADQDM) that estimates center frequencies along depth was introduced. However, the ADQDM often fails when imaging regions contain hypoechoic regions. In this paper, we introduce a valid region-based ADQDM (VR-ADQDM) method to reject the misestimated center frequencies to further improve SNR and CR. The valid regions are regions where the center frequency decreases monotonically along depth. In addition, as a low-pass filter of QDM, Gaussian wavelet based dynamic filtering was adopted. From the phantom experiments, average SNR improvements of the ADQDM and the VR-ADQDM over the traditional QDM were 1.22 and 5.27 dB, respectively, and the corresponding maximum SNR improvements were 2.56 and 10.58 dB. The contrast resolution of the VR-ADQDM was also improved by 0.68 compared to that of the ADQDM. Similar results were obtained from in vivo experiments. These results indicate that the proposed method would offer promises for imaging technically-difficult patients due to its capability in improving SNR and CR.

• International Journal of Oral Biology
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• v.39 no.3
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• pp.145-151
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• 2014

During bone remodeling, there is requirement of differentiation of osteoblastic cells. Previously, we identified proteins differentially expressed in soft tissue during bone healing. Of these proteins, we focused the effect of LTF on differentiation of osteoblast. In order to analyze the osteogenic ability of LTF, we treated conditioned media collected from human LTF-stably transfected HEK293T cells into osteoblastic MC3T3-E1. The results showed that the activity and expression of alkaline phosphatase were increased in MC3T3-E1 cells treated with conditioned media containing LTF in dose- and time-dependent manner. At the same time, we observed the significant increase of the expression of osteoblastic genes, such as ALP, BSP, COL1A1, and OCN, and along with matrix mineralization genes, such as DMP1 and DMP2, in LTF conditioned media-treated groups. Moreover, the result of treating recombinant human LTF directly into osteoblastic MC3T3-E1 showed the same pattern of treating conditioned media containing LTF. Our study demonstrated that LTF constitutively enhances osteoblastic differentiation via induction of osteoblastic genes and activation of matrix mineralization in MC3T3-E1 cells.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.354-361
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• 2005

Physical parameters such as porosity and effective porosity are important physical parameters that determine the transfer and movement of water and solutes in porous media. Various methods of determining these parameters have been developed, with varying degrees of accuracy and applicability. Most of the existing methods produce static results. They do not produce instantaneous and real time of porosity and effective porosity in a porous media. In this study, a new permittivity method called Frequency Domain Reflectometry with Vector analyzer (FDR-V) is proposed to determine the porosity and effective porosity of some sand samples in the laboratory. The advantage of the FDR-V method is that it instantaneously determines the temporal variation of dielectric constants of porous media. Then, the porosity and the effective porosity of porous media are computed using well established empirical equations. Results obtained from the FDR-V method compared favorably with results from other permittivity methods such as gravimetric, injection and replacement tests. The ratio of effective porosity to porosity was $85{\sim}92%$, when FDR-V was used. This value compared favourably with 90%, which has been usually quoted in previous studies. Considering the convenience and its applicability, the measurement system of FDR-V permittivity holds a great potential in porous media and contaminant transport studies.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.13 no.2
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• pp.265-282
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• 2002

The purpose of this study is to investigate the principles of school library media center program and to finds out present level and future outlook of the program implementation in primary and middle school. The fundamental objective of school is learning and school library functions as a link to support this objective. Therefore quality of education must always be linked to the library media programs. A questionaire which consists of 13 questions covering school library media center operation was designed to final out how learning-teaching media program is being practiced in Korea. Based on this study, it is concluded that there is significant difference between present practice level and desired future-oriented practice. It is hoped that this study will help planners in formulating school library policy to achieve educational goal of the school.

• Journal of Microbiology
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• v.38 no.1
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• pp.48-51
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• 2000

In liquid cultures using sucrose media, the coculture of Monascus with recombinant Saccharomyces cerevisiae expressing the glucoamylase gene from Aspergillus niger enhanced red pigment production by approx. 19％, compared with the coculture of wild type S. cerevisiae. Coculture with recombinant S. cerevisiae was more effective than with wild type S. cerevisiae for Monascus red pigment production. Cocultures of Monascus with commercial amylases of Aspergillus also induced high production of pigment and morphological changes in a solid culture using sucrose media.

• Korean Journal of Optics and Photonics
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• v.25 no.4
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• pp.169-192
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• 2014

In this paper, state-of-the-art digital holography and integral imaging have been introduced as practical three-dimensional imaging and display technology. Operational principles and recent research and development activities of these technologies have been discussed, as well as a vision of their future.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.6 no.4
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• pp.53-66
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• 1996

World Wide Web is a total solution for multi-media data transmission on Internet. Because of its characteristics like ease of use, support for multi-media data and smart graphic user interface, WWW has extended to cover all kinds of applications. The Secure Information Center(SIC) is a data transmission system using conventional cryptography between client and server on WWW. It's main function is to support the encryption of sending data. For encryption of data IDEA(International Data Encryption Algorithm) is used and for authentication mechanism MD5 hash function is used. Since Secure Information Center is used by many users, conventional cryptosystem is efficient in managing their secure interactions. However, there are some restrictions on sharing of same key and data transmission between client and server, for example the risk of key exposure and the difficulty of key sharing mechanisms. To solve these problems, the Secure Information Center provides encryption mechanisms and key management policies.

• Journal of Magnetics
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• v.7 no.3
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• pp.115-125
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• 2002

We proposed a novel method to evaluate the magnetic properties of the initial layer and the columnar structure separately for CoCr-based perpendicular recording media. We show that the thickness of the initial layer and the intrinsic magnetocrystalline anisotropy of columnar structure can be quantitatively evaluated using the plotted product of perpendicular anisotropy to magnetic film thickness versus magnetic film thickness ($K_{u{\bot}}^{ex{p.}}$ $\times$ d$_{mag.}$ vs. d$_{mag.}$ plot). Based on the analyses, it is found that: (1) compared with CoCrPtTa media, CoCrPtB media have relatively thin initial layer, and have fine grains with homogeneous columnar structure with c-plane crystallographic orientation; (2) CoCrPtB media can be grown epitaxially on Ru or CoCr/C intermediate layer, and as the result, the magnetic properties of the media within thin thickness region of d$_{mag.}$ $\leq$ 20 nm is significantly improved; (3) the key issue of material investigation for CoCr-based perpendicular recording media will be focused on how to fabricate c-plane-oriented columnar grains well isolated with nonmagnetic substance in epitaxial-growth media, while maintaining the thermal stability of the media.

• Asian Journal for Public Opinion Research
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• v.1 no.4
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• pp.249-267
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• 2014

Social media is being increasingly utilized in disaster relief work to identify safety issues, locate displaced-victims, and seek or provide support for those who need help. The presence of social media in disaster management has changed significantly in recent years, as it was not prevalent in the 2008 Wenchuan earthquake, but had become a powerful force in the 2013 Ya'an earthquake. This paper discusses the development of social media in disaster management via making a comparison between how it functioned in the two earthquakes. It examines the following aspects: who are the stakeholders that use social media in the earthquake management; how do they adopt this means in response to the earthquakes; and what are the outcomes of adopting social media with regards to public engagement and collaboration in an emergency event. As Sina Weibo acts as the equivalent of China's Twitter, the methodology relies on an analysis of posts in Weibo. The outcomes primarily show that: (1) authorities, celebrities and the public actively adopted social media for the purpose of information dissemination and resource mobilization; and (2) social media users are both content consumers and content generators in the times of earthquakes. The study concludes that social media as a backchannel communication tool is helpful for government institutions, corporations, and nonprofit organizations to build relationships with their stakeholders in the disaster management cycle. The result will interest academics and emergency management practitioners who are concerned with improving disaster communication.