• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.464-470
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• 2010

A new method for the poling of piezoelectric ceramics with an air insulation medium in stead of silicon oil is described. A similar variation of electromechanical coupling coefficient $K_t$, for an air medium is observed in comparison to that of the material poled by the conventional poling method using a silicon oil medium. Different poling parameters such as dielectric constant $\varepsilon^T$ and frequency deviation ${\Delta}f$ are studied as well as the influence on the aging effect. The required poling factors to achieve the optimal piezoelectric characteristics are electric field, 2 kV/mm, temperature $100^{\circ}C$, and poling time 30 Min. From this result electric field 3 kV/mm atmosphere airs there being will be able to use with the polarization insulation medium about the piezoelectric material, confirmed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.916-923
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• 2005

In this study, to observe aging effect of undrained shear behavior for Nak-Dong River sand, undrained static and cyclic triaxial tests were performed with changing relative density ($D_r$), consolidation stress ratio($K_c$) and consolidation time. As a result of the test, the modulus of elasticity to all samples estimated within elastic zone by the micro strain of about 0.05% in case of static shear behavior increased with the lapse of consolidation time significantly, so aging effect was shown largely. Also strength of phase transformation point(S_{PT}$) and strength of critical stress ratio point($S_{CSR}$) increased with the lapse of consolidation time. Undrained cyclic shear strength($R_f$) obtained from the failure strain 5% increased in proportion to relative density($D_r$) and initial static shear stress($q_{st}$), $R_f$ of consolidated sample for 1,000 minutes increased about 10.6% compared to that for 10 minutes at the loose sand, and $R_f$ increased about 7.0% at the medium sand. In situ application range of $R_f$ to the magnitude of earthquake for Nak-Dong River sand was proposed by using a increasing rate of $R_f$ as being aging effect shown from this test result.

• Reproductive and Developmental Biology
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• 제37권4호
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• pp.281-287
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• 2013

In mammal, unfertilized oocytes remain in the oviduct or under in vitro culture, which is called "oocyte aging". This asynchrony negatively affects fertilization in pre- and post-implantation embryo development. Caffeine a phosphodiesterase inhibitor is known to rescue oocyte aging in several species. The objective of this study is to determine the cytoskeleton distribution in aged oocytes and the embryo developmental ability of aged oocytes in the present or absence of caffeine during maturation. Caffeine treatment increased the incidence of normal spindle assembly of aged oocytes (treatment, $67.57{\pm}4.11%$ aging, $44.61{\pm}6.4%$) and no significant differences compared to control group. Fluorescence values were compared using ROS (Reactive oxidation species) stain. Fluorescence values appear of control group intensity rate ($51.53.{\pm}3.80$), aging group ($68.10{\pm}5.54$) and treatment of caffeine ($45.04{\pm}2.98$). Aged oocytes that were derived from addition of caffeine to the IVM (in vitro maturation) medium had significantly increased 2-cell that developed to the blastocyst stage compared to the aging group. Blastocysts, derived from caffeine treatment group, significantly increased the total cell number compare aging ($90.44{\pm}10.18$ VS $67.88{\pm}7.72$). Apoptotic fragments of genomic DNA were measured in individual embryo using TUNEL assay. Blastocyst derived from caffeine treatment group decreased significantly the apoptotic index compared to blastocyst derived from aging group. In conclusion, we inferred that the caffeine treatment during oocyte aging can improve the developmental rate and quality in bovine embryos developing in vitro.

• 조명전기설비학회논문지
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• 제17권3호
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• pp.80-86
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• 2003

본 논문에서는 육상의 지중전력케이블에 비해 유지보수가 힘들고 사고의 파급효과나 사고복구에 큰 어려움이 따르는 해저케이블을 대상으로 진단시험 및 유지보수에 대한 연구를 수행하였다. 본 연구의 목적은 사고위험이 높은 해저선로에 대한 경제적이고 효율적인 열화진단 및 유지보수에 있다. 진단시험 결과, 해저케이블의 열화정도는 매우 심각하며 열화가 계속 진전되고 있음을 확인하였다. 단말부 교체시공 후 재 진단시험을 실시한 결과, 전체적인 열화상태가 개선되었음을 확인하였으며 단말부 및 케이블 절연부에 대한 전기적 특성시험과 화학구조분석 시험 결과, 전체 케이블 시스템의 열화는 주로 단말부 열화에 기인함을 알았다. 상기 결과에 따라 본 연구에 사용된 진단기법 및 유지보수 절차가 해저케이블시스템의 경제적인 관리에 매우 효과적임을 학인하였다.

• 한국주조공학회지
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• 제22권2호
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• pp.89-96
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• 2002

This study examined the effects of adding Zn to Sn-3.5Ag solder on the microstructure changes and behavior of interface reaction of the solder joint with Cu substrate. The solder/Cu joints were examined with microscope to observe the characteristics of microstructure changes and interfacial reaction layer with aging treatment for up to 120 days at $150^{\circ}C$. Results of the microstructure changes showed that the microstructures were coarsened with aging treatment, while adding 1%Zn suppresses coarsening microstructures. The Sn-3.5Ag/Cu had a fast growth rate of the reaction layer in comparison with the Sn-3.5Ag-1Zn at the aging temperature of $150^{\circ}C$. Through the SEM/EDS analysis of solder joint, it was proved that intermetallic layer was $Cu_6Sn_5$ phase and aged specimens showed that intermetallic layer grew in proportion to $t^{1/2}$, and the precipitate of $Ag_3Sn$ occur to both inner layer and interface of layer and solder. In case of Zn-containing composite solder, $Cu_6Sn_5$ phase formed at the side of substrate and Cu-Zn-Sn phase formed at the other side in double layer. It seems that Cu-Zn-Sn phase formed at solder side did a roll of banrier to suppress the growth of the $Cu_6Sn_5$ layer during the aging treatment.

• 고려인삼학회:학술대회논문집
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• 고려인삼학회 1980년도 학술대회지
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• pp.21-25
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• 1980

Callus culture was initiated from explants of mature root tissues of ginseng (Panax ginseng C. A. Meyer) on MS medium enriched with 2, 4-D. The aging callus produced numerious embryoids in the same medium. Reculture of these embryoids in the media (1/2 MS or B5) supplemented with benzyladenine and gibberellic acid resulted in profuse plantlet regeneration.

• 대한건축학회논문집:계획계
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• 제35권4호
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• pp.127-134
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• 2019

Recently, the city development policies are being switched to the policies focusing on recession worldwide. Even though South Korea is also facing the phenomena that small and medium-sized cities are downsized because of a decrease in population and an aging society problem, there is lack of solutions and even they are still planning city development policies based on prospect of high growth. This study is featuring 4 viewpoints depending on shrinking population trend in 7 small and medium sized local cities, which are chosen as downsized cities. It is dealing with population peak, current population, 2030 population, and 2040 population viewpoints. And this study uses downsizing simulation that suggests optimum area that fits population and then shows visual check of the status of the small and medium sized local cities. The area of the small and medium sized local cities are expanded more than needs when they are on population peak point. However, they need only 20% to 25% of current area in 2030 and 2040. The most important thing is realizing the seriousness and facing up to the 'shrinking' phenomena that each small and medium-sized cities suffer. Therefore, this study has significance for presenting the status of small and medium-sized cities' problems in South Korea.

• 디지털융복합연구
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• 제13권8호
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• pp.337-344
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• 2015

본 연구는 간호사들의 노후 인식정도와 이직의도를 파악하여 성공적인 노후를 위해 안정적인 노후대책의 필요성을 인식 시키고자 시도 되었다. 연구대상자는 G시에 소재하는 간호사 290명이었다. 자료수집을 위한 설문조사는 2014년 8월 5일부터 8월 31일까지 실시되었고, 자료 분석은 SPSS WIN 18.0프로그램을 이용하여 기술적 통계, t-test, One way-ANOVA, 변수간의 상관관계는 Pearson Correlation Coefficien 로 분석하였다. 연구결과 성공적 노후인식과 노후대책 정도는 정적상관관계(r=.13. p=.022)를 보였고, 정서적 노후대책과 성공적 노후인식도 정적상관관계 (r=.16, p=.007)를 보였다. 본 연구에 의하면 융복합시대의 간호사들은 안정적인 직장에서 이직하지 않고 입사 하는 시점부터 노후준비의 필요성을 인식하고 장, 단기적 관점에서 경제적, 신체적, 정서적 측면에서 노후 대책을 실천해 나갈 수 있는 교육프로그램이 요구된다.

• The Korean Journal of Physiology and Pharmacology
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• 제22권5호
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• pp.503-511
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• 2018

Lysophosphatidic acid (LPA) is known to play a critical role in breast cancer metastasis to bone. In this study, we tried to investigate any role of LPA in the regulation of osteoclastogenic cytokines from breast cancer cells and the possibility of these secretory factors in affecting osteoclastogenesis. Effect of secreted cytokines on osteoclastogenesis was analyzed by treating conditioned media from LPA-stimulated breast cancer cells to differentiating osteoclasts. Result demonstrated that IL-8 and IL-11 expression were upregulated in LPA-treated MDA-MB-231 cells. IL-8 was induced in both MDA-MB-231 and MDA-MB-468, however, IL-11 was induced only in MDA-MB-231, suggesting differential LPARs participation in the expression of these cytokines. Expression of IL-8 but not IL-11 was suppressed by inhibitors of PI3K, NF-kB, ROCK and PKC pathways. In the case of PKC activation, it was observed that $PKC{\delta}$ and $PKC{\mu}$ might regulate LPA-induced expression of IL-11 and IL-8, respectively, by using specific PKC subtype inhibitors. Finally, conditioned Medium from LPA-stimulated breast cancer cells induced osteoclastogenesis. In conclusion, LPA induced the expression of osteolytic cytokines (IL-8 and IL-11) in breast cancer cells by involving different LPA receptors. Enhanced expression of IL-8 by LPA may be via ROCK, PKCu, PI3K, and NFkB signaling pathways, while enhanced expression of IL-11 might involve $PKC{\delta}$ signaling pathway. LPA has the ability to enhance breast cancer cells-mediated osteoclastogenesis by inducing the secretion of cytokines such as IL-8 and IL-11.

• 조명전기설비학회논문지
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• 제17권2호
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• pp.66-72
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• 2003

본 연구에서는 국내 배전계통에 사용 중인 전력케이블에 대한 평균열화평가시스템을 개발하였다. 절연진단의 최소한의 목적은 전력공급의 중단을 초래할 수 있는 열화 즉, 사고가능성이 논은 전력케이블을 효율적으로 선별하고 경제적으로 관리하는데 있다. 따라서 이러한 최소한의 진단 목표를 달성하기 위한 가장 효율적인 진단원리로 열화시정수법을 채택하고 감쇠전압을 측정변수로 하여 진단설비를 개발하였다. 현장적용성 시험 및 파괴강도 시험 결과 열화상태 평가결과와 파괴강도의 상관관계를 확인하였으며 본 연구를 통해 개발된 진단장치는 사고를 초래할 수 있는 열화의 효율적이고 경제적인 선별 및 관리에 유용한 설비가 될 수 있음을 알았다.