• 한국음향학회지
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• 제22권4호
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• pp.276-285
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• 2003

본 논문에서는 고성능 DSP (Digital Signal Processor)를 사용하여 R2MFC/DTMF (R2 Multi Frequency Combinations/Dual Tone Multiple Frequency) 톤 송수신기를 실시간 구현하여 대용량 VoIP (Voice over Internet Protocol) 게이트웨이 시스템에 적용한다. 수신기는 Goertzel 필터를, 송출기는 고조파 공명 필터를 이용한다. DMA (Direct Memory Access)와 McBSP(Multi Channel Buffered Serial Port)를 사용한 효과적인 PCM 입출력, HPI (Host Port Interface)를 통한 MPU (Main Processing Unit)와의 메시지 통신 등 Texas Instruments TMS320C62x DSP를 이용한 다채널 실시간 구현 기법에 관하여 상세히 기술한다. 실험 결과, 구현된 R2MFC/DTMF 송수신기는 ITU-T(International Telecommunication Union-Telecommunication) 조건을 만족하며, 최적화 된 코드는 250 ㎒ C62x에서 780 채널을 수용할 수 있는 계산량을 보였다.

• Kyungpook Mathematical Journal
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• 제62권1호
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• pp.133-166
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• 2022

Let M be a semi-invariant submanifold with almost contact metric structure (𝜙, 𝜉, 𝜂, g) of codimension 3 in a complex space form M_n+1(c) for c ≠ 0. We denote by S and R_𝜉 be the Ricci tensor of M and the structure Jacobi operator in the direction of the structure vector 𝜉, respectively. Suppose that the third fundamental form t satisfies dt(X, Y) = 2𝜃g(𝜙X, Y) for a certain scalar 𝜃 ≠ 2c and any vector fields X and Y on M. In this paper, we prove that if it satisfies R_𝜉𝜙 = 𝜙R_𝜉 and at the same time S𝜉 = g(S𝜉, 𝜉)𝜉, then M is a real hypersurface in M_n(c) (⊂ M_n+1(c)) provided that $\bar{r}-2(n-1)c{\leq}0$, where $\bar{r}$ denotes the scalar curvature of M.

• Transactions on Electrical and Electronic Materials
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• 제15권3호
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• pp.155-158
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• 2014

The phase transformation of Sn-Pb-Bi solder for photovoltaic ribbon during soldering was studied using real-time synchrotron x-ray scattering. At room temperature, Sn and Pb crystal phases in the solder existed separately. By heating to $92^{\circ}C$, a new PbBi alloy crystal phase was formed, which grew further up to $160^{\circ}C$. The Sn crystal phase first started to melt at $160^{\circ}C$, and was mostly melted at $165^{\circ}C$. In contrast, the Pb and PbBi crystal phases started to melt at $165^{\circ}C$, and were mostly melted at $170^{\circ}C$. The useful result was obtained, that the solder's melting temperature decreased from $183^{\circ}C$ to $170^{\circ}C$ by addition of a small amount of Bi atoms to the eutectic Sn62-Pb38 (wt%) solder. Our study first revealed the detailed in-situ phase transformation of Sn-Pb-Bi solder during heating to the eutectic temperature. Considering the results of peel strength and hardness, adding 1 wt% of Bi atoms to the Sn62-Pb38 (wt%) solder produced an appropriate composition.

• Reproductive and Developmental Biology
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• 제34권3호
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• pp.229-233
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• 2010

Pluripotency and self-renewal capacity of human embryonic stem cells (hESCs) are retained by hESCs related genes as OCT4, SOX2 and NANOG. These genes are shown high expression level in diverse cancer cells and have potential role in the carcinogenesis. On the contrary to this, several genes which are up-regulated in the differentiated hESCs are involved to suppress the carcinogenesis or proliferation of cells. We discovered several genes in immortalized lung fibroblast (WI-38 VA13) by suppression subtractive hybridization. Among them, we focused chromosome 6 open reading frame 62 (C6orf62) which is uncharacterized, mapped to 6p22.3 and generated to Hepatitis B virus X-transactivated proteins (HBVx-transactivated proteins, XTP). Aim of this study was to characterize C6orf62 through analyzing of expression pattern in various cell lines. Expression of C6orf62 was significantly upregulated in diverse normal cell lines than cancer cell lines. And C6orf62 was up-regulated in differentiated hESCs (endothelial cells, neural cells) compared to those of undifferentiated hESCs. Also, C6orf62 in WI-38 cells was highly up-regulated during G1/S transition of the cell cycle. Taken together, C6orf62 is shown expression pattern similar to differentiated hESCs-associated genes which down-regulated in cancer cells. Therefore, we assume that C6orf62 may participate to suppress the proliferation and to induce differentiation through regulating the cell cycle.

• 한국전기전자재료학회논문지
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• 제12권1호
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• pp.62-68
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• 1999

Ferroelectric $Sr_{0.7}/B_{2.3}(Ta_{1-x}Nb_x)_2O_9$(x=0, 0.1, 0.2, 0.3) thin films were deposited on $Pt/SiO_2/Si$ substrate by MOD(Metalorganic Decomposition) process. Metal carboxylate and metal alkoxide were used as precursors, and 2-methoxyethanol, xylene as solvents. After spin coating, thin films were pre-annealed at $400^{\circ}C$, followed by RTA(Rapid Thermal Annealing) and final annealing at $800^{\circ}C$ in oxygen atmosphere. These procedures were repeated three times to obtain thin films with the thickness of $2000{\AA}$. To enhance the nucleation and growth of layered-perovskite phase, thin films were rapid-thermally annealed above $720^{\circ}C$ in oxygen atmosphere. As RTA temperature increased, fluorite phase was transformed to layered-perovskite phase. And the change of Nb contents affected dielectric / electrical properties and microstructure. The ferroelectric characteristics of $Sr_{0.7}/B_{2.3}(Ta_{1-x}Nb_x)_2O_9$ thin film were Pr=8.67 $\mu{C}/cm^2$, Ec=62.4kV/cm and $I_{L}=1.4\times10^{-7}A/cm^2$ at the applied voltage of 5V, respectively.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2015년도 자성 및 자성재료 국제학술대회
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• pp.61-62
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• 2015

• 한국재료학회지
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• 제5권1호
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• pp.36-41
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• 1995

$(Pb_{0.62}Ca_{0.38})ZrO_{3}$계에서의 조성 x=0.38의 $(Pb_{0.62}Ca_{0.38})ZrO_{3}$에 Mn 성분을 첨가하여 $1300^{\circ}C$에서 2시간 소결한 세라믹스의 소결성 및 고주파 유전특성을 연구하였다. Mn의 첨가로 소결온도가 낮아지며 치밀한 소결체를 얻을 수 있었다. 하소온도가 높아짐에 따라 하소과정에서 합성반응이 충분히 이루어져 소결체의 최종 소결과정에 영향을 미처 유전체의 유전상수와 품질계수 Q값이 증가하였다. Mn의 첨가량에 따른 물성변화는 Mn의 첨가량이 0.15wt%까지의 첨가범위에서는 $Mn^{4+}$가 $Mn^{3+}$ 또는 $Mn^{2+}$로 환원됨에 따라 산소공공이 생성되며, 억셉터로 작용하여 품질계수 Q값이 1300정도까지 증가하였고, 유전율은 90-100 정도로 변화가 없었다. 그러나 Mn 첨가량이 0.5 wt%이상일때 유전손실이 매우 증가되며 동시에 품질계수 Q값이 점차 감소하였다.

• 한국전기전자재료학회논문지
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• 제11권5호
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• pp.413-417
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• 1998

In this paper, we investigate frequency dependance of inductance of FeCoB amorphous magnetic films. $(Fe_{1-x}Co_x)_{79}Si_2B_{19}$ was used as the basic composition of amorphous magnetic film having near zero magnetostriction. The amorphous magnetic films were fabricated with x=0.94 and x=0.95 by using sputtering method at high frequency. The films were anneald under non-magnetic field and near crystallization temperatures(30min at $280^{\circ}C$, 30min and 1hr at $400^{\circ}C$, respectively). As the results of the experiments with the fabricated films, the lowest coercive force was 0.084[Oe] at 400[W] of the input power and the crystallization temperature was $360^{\circ}C$ . In the case 30min at 40$0^{\circ}C$ the inductance value in the low frequency with x=0.95 was higher by 488% than that with x=0.94. The quality factor Q was below 0.7 for all samples. We obtained the highest quality value at 400[KHz] with 30min at $280^{\circ}C$ and x=0.94. The value was about 0.62. Also, the quality factor value was about 0.35 at 1[MHz] with 30min at $280^{\circ}C$ and x=0.95.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.5.2-8
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• 1995

0.15($Ba_{1-x}Sr_{x}$)O-$0.15Sm_2O_3$-$0.7TiO_2$(x=0∼9[m/o]ceramics were fabricated by mixed-oxide method. Microwave dielectric properties were investigated with sintering conditions aid Sr addictive. In the specimen with x=0[m/o] sintered at 1350∼1470[$^{\circ}C$], dielectric constant, quality factor and temperature coefficient of resonant frequency were 70∼74, 2800∼3300(at 3[GHz]), -1.33∼+l.66[ppm/$^{\circ}C$, respectively. Increasing the Sr additive from 0 to 5[m/o], dielectric constant and temperature coefficient of resonant frequency were increased and quality factor was decreased. In the specimen with x=r[m/o] sintered at 1375[$^{\circ}C$], 6[hr], dielectric constant, quality factor and temperature coefficient resonant frequency were 75.62, 2785(at 3[GHz]), +8.39[ppm/$^{\circ}C$], respectively.

• Journal of Ginseng Research
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• 제9권2호
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• pp.248-255
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• 1985

In order to investigate the optimal drying condition of white ginseng by using bulk air drier(130 x 62 x 65cm), drying curves, diffusion coefficient at various drying temperature, the energy of activation, variation of color intensity and chemical components during drying of white ginseng were studied. Fick's second low of diffusion for diffusion out of spheres was successfully applied to describe the drying of white ginseng. It was found that the diffusion coefficient of water was 2.2x107, 9.0x107 cm2/sec at drying temperature 4$0^{\circ}C$, 55$^{\circ}C$, respectively. An Arrhenius type temperature dependency of moisture diffusivity was found, the energy of activation being 18.8 Kcal/g mol. Color intensity of white ginseng dried at various drying temperature was increased with an increase in drying temperature. The contents of crude protein, reducing sugar and crude saponin during drying of white ginseng were gradually decreased as increasing of drying time. And with the sensory evaluation by multiple comparison difference analysis, the optimal drying temperature of white ginseng was between 45$^{\circ}C$ and 5$0^{\circ}C$.