• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.94-94
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• 2009

전기 에너지를 기계적 에너지 변환하고 또한, 기계적 에너지를 전기 에너지로 변환할 수 있는 압전 세라믹스는 압전 변압기 (piezoelectric transformer), 초음파모터, 센서등과 같은 응용분야에 넓게 사용되고 있다. 특히, 압전 변압기의 설계와 제조방법에 대해서는 이미 상당히 많은 연구가 수행되어 왔다. 특히, 전원장치에 있어서는 현재 주요부품으로 사용되고 있는 권선형 변압기와 같은 전자 변환기의 대체품으로서 누설손실이 없는 압전세라믹스 소재의 특성을 이용한 압전변압기의 개발과 응용연구가 국내외적으로 활발히 진행 중이다. 하지만 지금 까지 널리 사용된 PZT계 압전 세라믹스는 환경문제에 있어서 문제점을 가지고 있다. $1200^{\circ}C$ 이상에서 소결되는 PZT계열의 압전세라믹스 소재를 사용한 전자부품의 60~70%이상이 PbO로 구성되어 있기 때문에 $1000^{\circ}C$ 부근에서 급격한 휘발특성을 보이는 PbO로 인한 환경오염문제가 대두되고 있다. 압전변압기, 초음파모터등에 사용될 수 있는 무연계 압전재료 중에 PZT 압전소자의 기능을 대체할 만한 물질로는 높은 큐리온도와 우수한 압전특성을 보이는 $(Na,K)NbO_3$세라믹스가 가장 유력한 것으로 알려져 있다. 즉, 압전변압기용 조성 세라믹스는 높은 에너지 변환효율을 위해서 전기기계 결합계수($k_p$)가 커야 되며, 발열에 의한 온도 상승을 억제하기 위하여 기계적 품질계수($Q_m$)가 큰 것이 바람직하다. 또한, 높은 전류를 발생하기 위해서는 유전상수가 커, 압전변압기의 출력측 정전용량을 크게 하여야 한다. 본 연구에서는 무연계 압전세라믹스를 개발하고, 이를 이용한 전력밀도(power density)가 높은 무연계 압전변압기를 제작하여 그에 대한 전기적 특성을 조사하였다. 따라서 본 연구에서는 무연 압전변압기용 압전 세라믹스를 개발하기 위해 뛰어난 압전 및 유전특성을 가진 무연$(Na,K)NbO_3$계 세라믹스를 기본조성으로 하였고, KCN을 복합 첨가하여 볼 변화에 따른 미세구조, 압전 및 유전특성을 조사하고. 가장 우수한 조성으로 비납 압전변압기를 제작하여 전기적특성을 조사하였다.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.10
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• pp.1360-1365
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• 2004

Using the method of 'random sampling in typical colonies of the central area of the habitat', 60 Small-tailed Han sheep were obtained in Jining city, Shangdong province. The variations of Small-tailed Han sheep at 12 structural loci encoding blood proteins were detected by several electrophoresis techniques and their gene frequencies were then estimated. The same data of four other sheep populations from Near-sea Mainland in East Asia were cited for the analysis of genetic differentiation. The average heterozygosities of five populations, namely Kharkhorin sheep, Ulaanbaatar sheep, Small-tailed Han sheep, Hu sheep and Cham Tribe sheep were 0.3447, 0.3285, 0.3157, 0.3884 and 0.2300, respectively. The coefficient of gene differentiation among four populations, Kharkhorin sheep, Ulaanbaatar sheep, Small-tailed Han sheep and Hu sheep, was 0.045557, and that between these four breeds and Cham Tribe sheep was 0.088005, indicating that the level of gene differentiation among the former four sheep populations of Mongolian group was comparatively lower than that between Cham Tribe sheep and other four sheep populations. The origin of Cham Tribe sheep deserve further research. The documentary research on the evolution of Small-tailed Han sheep and Hu sheep from Mongolian sheep was further verified by the biochemical experiments in the study. It was reasonably deduced that Hu sheep, Small Tailed Han sheep and Cham Tribe sheep were decreasingly influenced by the bloodline of Mongolian sheep.

• IMMUNE NETWORK
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• v.4 no.3
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• pp.143-154
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• 2004

Background: CD27 is recently known as a memory B cell marker and is mainly expressed in activated T cells, some B cell population and NK cells. CD27 is a member of tumor necrosis factor receptor family. Like CD40 molecule, CD27 has (P/S/T/A) X(Q/E)E motif for interacting with TNF receptor-associated factors (TRAFs), and TRAF2 and TRAF5 bindings to CD27 in 293T cells were reported. Methods: To investigate the CD27 signaling effect in B cells, human CD40 extracellular domain containing mouse CD27 cytoplamic domain construct (hCD40-mCD27) was transfected into mouse B cell line CH12.LX and M12.4.1. Results: Through the stimulation of hCD40-mCD27 molecule via anti-human CD40 antibody or CD154 ligation, expression of CD11a, CD23, CD54, CD70 and CD80 were increased and secretion of IgM was induced, which were comparable to the effect of CD40 stimulation. TRAF2 and TRAF3 were recruited into lipid-enriched membrane raft and were bound to CD27 in M12.4.1 cells. CD27 stimulation, however, did not increase TRAF2 or TRAF3 degradation. Conclusion: In contrast to CD40 signaling pathway, TRAF2 and TRAF3 degradation was not observed after CD27 stimulation and it might contribute to prolonged B cell activation through CD27 signaling.

• Journal of Korean Academy of Nursing
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• v.35 no.3
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• pp.546-554
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• 2005

Purpose: This study was a systematic review and meta-analysis of the effects of exercise programs in patients with type II diabetes mellitus. Method: Two investigators systematically searched and reviewed English articles from PUBMED from 1988 to 2004, selecting randomized controlled trials on structured exercise programs for DM patients. Out of 87 studies identified, a meta analysis was done for eleven studies which satisfied inclusion criteria and focused on glycemic indices, lipid indices, and cardiac function indices. Results: The means and standard deviations were compared for experimental groups that received exercise-only or exercise and diet programs and control groups that received no intervention or only diet education. The groups were considered homogeneous as the p value of the Q score in each variable group was over 0.05. The experimental groups demonstrated a moderate positive effect on HbA,c and $VO_{2max}$ (d=0.55 & 0.5), and a small positive effect on fasting blood glucose and cholesterol (d=0.38 & 0.27) compared to the control groups. HDL and LDL cholesterol levels, however, showed a very low positive effect (d=0.11 & 0.12) in the experimental groups. Aerobic exercise was more beneficial than resistance exercise on $HbA_1c$ (d=0.59 vs 0.28) in the groups. Conclusions: Regular exercise has a positive effect on $HbA_1c$, fasting blood glucose, total cholesterol, HDL cholesterol, LDL cholesterol, and $VO_{2max}$ in Type 2 diabetic patients.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2508-2512
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• 2012

Cold shock proteins (CSPs) are a family of proteins induced at low temperatures. CSPs bind to single-stranded nucleic acids through the ribonucleoprotein 1 and 2 (RNP 1 and 2) binding motifs. CSPs play an essential role in cold adaptation by regulating transcription and translation via molecular chaperones. The solution nuclear magnetic resonance (NMR) or X-ray crystal structures of several CSPs from various microorganisms have been determined, but structural characteristics of psychrophilic CSPs have not been studied. Therefore, we optimized the purification process to obtain highly pure Lm-Csp and determined the three-dimensional structure model of Lm-Csp by comparative homology modeling using MODELLER on the basis of the solution NMR structure of Bs-CspB. Lm-Csp consists of a ${\beta}$-barrel structure, which includes antiparallel ${\beta}$ strands (G4-N10, F15-I18, V26-H29, A46-D50, and P58-Q64). The template protein, Bs-CspB, shares a similar ${\beta}$ sheet structure and an identical chain fold to Lm-Csp. However, the sheets in Lm-Csp were much shorter than those of Bs-CspB. The Lm-Csp side chains, E2 and R20 form a salt bridge, thus, stabilizing the Lm-Csp structure. To evaluate the contribution of this ionic interaction as well as that of the hydrophobic patch on protein stability, we investigated the secondary structures of wild type and mutant protein (W8, F15, and R20) of Lm-Csp using circular dichroism (CD) spectroscopy. The results showed that solvent-exposed aromatic side chains as well as residues participating in ionic interactions are very important for structural stability. Further studies on the three-dimensional structure and dynamics of Lm-Csp using NMR spectroscopy are required.

• Journal of Korean Neurosurgical Society
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• v.59 no.2
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• pp.83-90
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• 2016

Ependymomas occur in both the brain and spine. The prognosis of these tumors sometimes differs for different locations. The genetic landscape of ependymoma is very heterogeneous despite the similarity of histopathologic findings. In this review, we describe the genetic differences between spinal ependymomas and their intracranial counterparts to better understand their prognosis. From the literature review, many studies have reported that spinal cord ependymoma might be associated with NF2 mutation, NEFL overexpression, Merlin loss, and 9q gain. In myxopapillary ependymoma, NEFL and HOXB13 overexpression were reported to be associated. Prior studies have identified HIC-1 methylation, 4.1B deletion, and 4.1R loss as common features in intracranial ependymoma. Supratentorial ependymoma is usually characterized by NOTCH-1 mutation and p75 expression. TNC mutation, no hypermethylation of RASSF1A, and GFAP/NeuN expression may be diagnostic clues of posterior fossa ependymoma. Although MEN1, TP53, and PTEN mutations are rarely reported in ependymoma, they may be related to a poor prognosis, such as recurrence or metastasis. Spinal ependymoma has been found to be quite different from intracranial ependymoma in genetic studies, and the favorable prognosis in spinal ependymoma may be the result of the genetic differences. A more detailed understanding of these various genetic aberrations may enable the identification of more specific prognostic markers as well as the development of customized targeted therapies.

• Journal of Integrative Natural Science
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• v.10 no.2
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• pp.85-94
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• 2017

Fibroblast growth factor receptor (FGFR) belongs to the family of receptor tyrosine kinase. They play important roles in cell proliferation, differentiation, development, migration, survival, wound healing, haematopoiesis and tumorigenesis. FGFRs are reported to cause several types of cancers in humans which make it an important drug target. In the current study, HQSAR analysis was performed on a series of recently reported 1H-Pyrazolo [3,4-b]pyridine derivatives as FGFR antagonists. The model was developed with Atom (A) and bond (B) connection (C), chirality (Ch), hydrogen (H) and donor/acceptor (DA) parameters and with different set of atom counts to improve the model. A reasonable HQSAR model ($q^2=0.701$, SDEP=0.654, NOC=5, $r^2=0.926$, SEE=0.325, BHL=71) was generated which showed good predictive ability. The contribution map depicted the atom contribution in inhibitory effect. A contribution map for the most active compound (compound 24) indicated that hydrogen and nitrogen atoms in the side chains of ring B as well as hydrogen atoms in the side chain of ring C and the nitrogen atom in the ring D contributed positively to the activity in inhibitory effect whereas, the lowest active compound (compound 04) showed negative contribution to inhibitory effect. Thus results of our study can provide insights in the designing potent and selective FGFR kinase inhibitors.

• Journal of the Korean Geosynthetics Society
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• v.16 no.3
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• pp.31-39
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• 2017

Applicability of Skempton's and Hansbo's equation for estimating strength incremental ratio of Korean marine clayey soil was analyzed. These empirical equations have been commonly applied to design soft ground improvement by, especially, staged loading method. Strength incremental ratios proposed by Skempton (1954, 1957) and Hansbo (1957) using field vane tests(FVTs), measured in Scandinavia depends on plasticity index and liquid limit. Although lean clay in Scandinavia can be classified as clay based on USCS, this soil contains no clay mineral because it was produced by the glacial grinding of rock, sometimes, called rock flour. On the contrary, plasticity indices of Korean marine clayey soils increase linearly with the percentage of clay fraction (% finer than $2{\mu}m$ by weight). Except for strength incremental ratios using $q_u/2$ values in the case of soils having a low plasticity, such as Incheon, Hwaseong and Gunsan soils, these values are in the range of 0.25 to 0.35, independently of the plasticity index, $I_p$.

• Food Science of Animal Resources
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• v.38 no.4
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• pp.664-678
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• 2018

This study was carried out to establish shelf life for pork cutlet of ground meat and pork lard by using various quality indicators and to understand how quality changes in these products are accelerated by temperature. The samples were selected and purchased from markets in Korea, and the chosen quality indicators were total aerobic counts and coliform group in microbiological analyses, thiobarbituric acid reactive substances assay, volatile basic nitrogen, pH, acid value, and peroxide value in physical chemical analyses, and sensory evaluation. The pork cutlet samples were stored at $-18^{\circ}C$, $-6^{\circ}C$, and $-1^{\circ}C$, whereas pork lard samples were stored at $10^{\circ}C$, $25^{\circ}C$, $35^{\circ}C$, and $45^{\circ}C$. These temperature conditions were set to real distribution conditions. The samples were then analyzed using various models including of reaction orders, arrhenius equation, and $Q_{10}$ value. The quality limits for each sample were calculated, and shelf life was estimated. The results of this experiment highlighted the importance of temperature control during the distribution process of these products and revealed that temperature is a useful parameter for the establishment of a basic database for shelf life.

• Journal of Environmental Science International
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• v.24 no.12
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• pp.1591-1600
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• 2015

The response of the freshwater microalga, Chlorella vulgaris, to heavy metal stress was examined based on chlorophyll fluorescence analysis to assess the toxic effects of heavy metals in freshwater ecosystems. When toxic effects were analyzed using regular chlorophyll fluorescence analysis, photosystem II activity($F_v/F_m$) decreased significantly when exposed to $Cu^{2+}$ and $Hg^{2+}$ for 12 h, and decreased in the order of $Hg^{2+}>Cu^{2+}>Cd^{2+}>Ni^{2+}$ when exposed for 24h. The effective photochemical quantum yield(${\phi}{\prime}_{PSII}$), chlorophyll fluorescence decrease ratio($R_{Fd}$), minimal fluorescence yield($F_o$), and non-photochemical quenching(NPQ), but not photochemical quenching(qP), responded sensitively to $Hg^{2+}$, $Cu^{2+}$, and $Cd^{2+}$. These results suggest that $F_v/F_m$, as well as ${\phi}{\prime}_{PSII}$, $R_{Fd}$, $F_o$, and NPQ could be used to assess the effects of heavy metal ions in freshwater ecosystems. However, because many types of heavy metal ions and toxic compounds co-occur under natural conditions, it is difficult to assess heavy metal toxicity in freshwater ecosystems. When Chlorella was exposed to heavy metal ions for 12 or 24h, $F_v/F_m$ and maximal fluorescence yield($F_m$) changed in response to $Hg^{2+}$ and $Cu^{2+}$ based on image analysis. However, assessing quantitatively the toxic effects of several heavy metal ions is challenging.