• Journal of Electrochemical Science and Technology
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• 제11권1호
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• pp.84-91
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• 2020

The PtBi/C and PtBiPd/C electrocatalysts were synthesized via the irreversible adsorption of Pd and Bi ions precursors on commercial Pt/C catalysts. XRD and XPS revealed the formation of an alloy structure among Pt, Bi, and Pd atoms. The current of direct formic acid oxidation (I_d) increased ~ 8 and 16 times for the PtBi/C and PtBiPd/C catalysts, respectively, than that of commercial Pt/C because of the electronic, geometric, and third body effects. In addition, the increased ratio between the current of direct formic acid oxidation (I_d) and the current of indirect formic acid oxidation (I_ind) for the PtBi/C and PtBiPd/C catalysts suggest that the dehydrogenation pathway is dominant with less CO formation on these catalysts.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2007년도 동계학술연구발표회 및 스핀트로닉스와 나노물리에관한 국제심포지움
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• pp.196-197
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• 2007

• 한국자동차공학회논문집
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• 제14권1호
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• pp.8-16
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• 2006

The research was conducted to characterize of Rh-Pd-Pt TWC with a double-layer washcoat for gasoline vehicle. The physical characteristics on surface of catalyst were inspected by BET, SEM and TEM. The characteristics of catalytic reaction were examined by the TPD/TPR and CO-pulse chemisorption. The catalyst $6Hx(0.35\times11\times3)$ showed superior conversion performance after hydrothermal aging process, which was due to small difference of the surface area between. the fresh and the aged catalyst. The CO-chemisorption and surface area were superior in the 600 cpsi catalyst than other catalysts, this catalyst also shown the higher conversion efficiency of the exhaust emissions. From the TPR test, the conversion performance of the aged catalyst was decreased by the agglomeration and sintering of the PM and metal oxides. From the TPD result, it was found that the NO chemisorption was happed on the bottom-layer washcoat with Pd, and the NO chemisorption was re-happened on the upper-layer washcoat with Pt and Rh in the desorption process.

• 반도체디스플레이기술학회지
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• 제7권4호
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• pp.41-44
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• 2008

NiSi is less stable than the previously-used $CoSi_2$ at high temperature. Some noble metals, such as Pd and Pt, have been added to NiSi to improve its thermal stability. We employed a first principles calculation to understand the Pd segregation at the interface. An orthorhombic structure of NiSi was used to construct an orthorhombic-NiSi/Si (010). Lattice parameters along a- and c-axes in orthorhombic-NiSi were matched with those of Si for epitaxy contact. The optimized $1\times4\times1$ orthorhombic-NiSi (010) and $1\times2\times1$ Si (010) superstructures were put together to construct the orthorhombic-NiSi/Si (010), and the superstructure was relieved in calculation to minimize its total free energy. The optimized interface thickness of the superstructure was $1.59\AA$. Pd atom was substituted in Ni and Si sites located near interface. Both Ni and Si sites located at the interface were favorable for Pd substitution.

• Journal of Advanced Marine Engineering and Technology
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• 제20권4호
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• pp.43-49
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• 1996

With the recent interest in methanol as a SI engine fuel, aldehyde emissions have become a greater concern. A M-90 fueled passenger car was operated in a chassis dynamometer using FTP 75 driving cycle to examine formaldehyde emissions. Formation process of aldehyde and methods to reduce them are discussed in this paper for a SI-engine passenger car operating by M-90. Aldehyde emissions have been found to be 3 to 7 times higher from M-90 than from gasoline, while CO, NOx, THC are as low or lower than gasoline. Noble metal compositions appeared to play a role in formaldehyde and unburned methanol emission performance. For example, catalyst Pd showed better reduction of both formaldehyde and methanol than catalyst Pt. however, emission rates of formaldehyde and methanol for catalyst Pt were relatively similar to catalyst Pt/Rh.

• 한국식품과학회지
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• 제41권1호
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• pp.77-81
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• 2009

Streptozotocin-유도 당뇨병 모델을 이용하여 흑삼의 혈당강하작용에 대한 효과를 연구하고 증포과정에 따른 ginsenoside의 조성 변화를 분석하였다. 증포별 ginsenoside의 정량분석 결과, 증포 횟수가 증가할수록 조사포닌의 총량과 대부분의 ginsenoside는 줄어든 반면 ginsenoside-$Rg_3$ 함량 및 PD/PT 비율은 증가하는 경향을 보였는데, 이러한 조성은 다른 인삼제품과는 차별성 있는 특징이다. 또한, streptozotocin-당뇨병 유발쥐를 이용한 모델실험에서 흑삼추출물의 투여는 고혈당 준위(300 mg/dL이상)를 정상 수준(102 mg/dL)으로 감소시켰으며, 혈당 수준의 감소는 glycolysis나 HMT shunt 및 지방산 합성에 관여하는 glucokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, acetyl CoA carboxylase 등의 효소의 활성증대에 기인하는 것으로 판단되었다. 이러한 결과는 흑삼추출물의 유의적인 혈당강하 효과를 입증하며 이에 따라 신약이나 식이보조제의 항당뇨물질로서의 이용가능성을 시사한다.

• 한국반도체및디스플레이장비학회:학술대회논문집
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• 한국반도체및디스플레이장비학회 2003년도 추계학술대회 발표 논문집
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• pp.163-168
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• 2003

In the present study, the piezoelectricity and polarization of multilayer ceramic actuator, being designed to stack PMN-PZ-PT ceramic layers and Ag-Pd electrode layers alternatively, were investigated under a consideration of geometric factor, the volume ratio of the ceramic to the electrode layers. The actuators were fabricated by tape casting of $0.2Pb(Mg_{1/3}Nb_{2/3)O_3-0.38PbZrO_3-0,42PbTiO_3$ followed by lamination and burnout & co-firing processes. The actuators of $10\times10\times0.6~2\textrm{mm}^3$ in size were formed in a way that $60 ~ 200\mu\textrm{m}$ thick were stacked alternatively with $5\mu\textrm{m}$ thick electrode layer. Increases in polarization and electric field-induced displacement with thickness of the ceramic layer were attributed to change of $90^{\circ}$/$180^{\circ}$ domain ratio, which was affected by interlayer internal stress. The piezoelectricity and actuation behaviors were found to depend upon the volume ratio (or thickness ratio) of ceramic to electrode layers.

• 한국약용작물학회지
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• 제20권1호
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• pp.27-35
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• 2012

This study was conducted to investigate changes in composition of ginsenosides and color of processed ginsengs prepared by different steaming-drying times. Processed ginsengs were prepared from white ginseng with skin by 9-time repeated steaming at $96^{\circ}C$ for 3 hours and followed by hot air-drying at $50^{\circ}C$ for 24 hours. As the times of steaming processes increased, lightness (L value) decreased and redness (a value) increased in color of ginseng powders. Crude saponin contents and ginsenosides compositions in processed ginsengs prepared by different steaming-drying times were investigated using the HPLC method, respecively. Crude saponin contents according to increasing steaming-drying times decreased in some degree. In the case of major ginsenosides, the contents of $Rb_1$, $Rb_2$, Rc, Rd, Rf, Re, $RG_1$, Re were decreased with increase in steamimg times, but those of $Rh_1$, $Rg_3$, $Rk_1$ were increased after especially 3 times of steaming processes. Interestingly, in black ginseng were prepared by 9 times steaming processes, the content of ginsenoside $Rg_3$ was 8.20 mg/g, approximately 18 times higher than that (0.46 mg/g) in red ginseng. In addition, the ratio of the protopanaxadiol group and protopanaxatiol group (PD/PT) were increased from 1.9 to 8.4 due to increasing times of steamming process.

• 자원환경지질
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• 제44권5호
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• pp.373-386
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• 2011

옥천변성대의 대표적인 우라늄 광화대인 괴산군 덕평리 일대의 흑색점판암과 이에 협재하는 함우라늄 탄질점판암을 상호 구분하여 이들에 대한 지구화학적 연구를 수행함으로써 우라늄 광상의 생성환경에 대해 고찰하였다. 희토류원소 함량은 탄칠점판암이 평균 254 ppm로서 혹색점판암(169 ppm) 보다 높고, 표준시료로 표준화한 결과 탄질시료의 Eu이 현저히 부화되어 나타난다. 산화환원지시원소에 해당하는 원소들의 경우 V, Cr, Co, Ni, Mo, 및 U 등이 흑색점판암에 비해 탄질점판암에서 현저히 부화되어 있는데, 특히, V은 흑색점판암에 비해 24배, Mo은 62배, U은 60배 가량 높게 산출된다. 이 밖에 백금족원소의 경우 Pd와 Pt가 탄질점판암에서 높은 함량을 나타낸다. 정의 Eu 이상을 비롯해 표준 해수기원 셰일에 비해 현저히 부화된 상기 원소들의 산출은 이들이 단순한 해수로부터 침전된 것이 아닌 고온의 환원환경인 해저열수활동과 관련된 퇴적환경에서 생성되었음을 시사한다. 넓은 조성변화를 나타내는 주성분 원소비 ($SiO_2/Al_2O_3$: 3.98~11.88, $Al_2O_3/Na_2O$: 25.6~139.06, $K_2O/Na_2O$: 6.80~46.85)도 퇴적물의 근원암이 퇴적암과 화성암이 혼재되었을 가능성을 나타내며, 또한 황의 함량이 흑색점판암에서 평균 0.6 wt.%인 반면, 탄질점판 암에서는 2.6 wt.%로 높게 나타나는 것은 탄질점판암이 황을 다량 포함하는 열수환경의 영향을 받았음을 보여준다. 이와 같은 지화학적 특징은 옥천변성대와 지구조적으로 대비되며 퇴적분기성 기원으로 알려진 남중국형 백금족광상(Mo-Ni-Zn-PGE)의 생성환경과도 유사한 특징이다. 이상으로 보아 덕평려 일대 우라늄광화작용은 해저열수활동의 영향을 받고 산소가 결핍된 유기물이 풍부한 퇴적분지에서 형성된 것으로 해석된다.

• 한국식품과학회지
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• 제35권3호
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• pp.536-539
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• 2003

백삼 가공품과 홍삼 가공품의 사포닌 분포 내용과 함량을 비교하기 위하여 시판되고 있는 백삼 농축액(WGC)과 홍삼 농축액(RGC)을 각각 1종 선정하여 조 사포닌의 함량과 개별 ginsenoside의 함량분포를 조사하였다. Shibata의 방법과 우리나라 식품공전에 따라 측정한 조 사포닌의 양은 WGC가 각각 10.65와 21.77%이었으며 RGC는 5.80와 10.94%이였고, HPLC에 의한 총 사포닌의 양은 WGC가 7.40와 10.64%, RGC는 3.31와 3.13%로서 백삼 농축액의 사포닌 함량이 홍삼 농축액의 경우 보다 전반적으로 높았다. HPLC로 분석한 인삼 사포닌, ginsenoside $Rb_1,\;Rb_2,\;Rc,\;Rd,\;Re,\;Rf,\;Rg_1,\;20(S)\;Rg_3,\;20(R)Rg_3,\;20(S)\;Rh_1$ 그리고 $20(R)\;Rh_1$ 이었으며 대부분 홍삼농축액 보다는 백삼농축액의 함량이 높았으며, 특히 ginsenoside $Rb_1,\;Rg_1$ 그리고 $Rb_2$은 백삼 농축액에 3배 이상 더 함유되어 있었다. 또한 protopanaxadiol group과 protopanaxatriol group의 비율(PD/PT)에 있어서는 농축액간의 차이는 크지 않았다. 홍삼의 특유 사포닌으로 알려진 20(S)- 및 20(R)-ginsenoside $Rg_3$가 WGC와 RGC에 비슷하게 분포하는 것으로 확인되었다. 20(S)-ginsenoside $Rg_3$의 조 사포닌 조제법에 따라 RGC에서 0.48과 0.47% WGC에 0.40와 0.53%, 20(R)-ginsenoside $Rg_3$도 RGC에 0.10과 0.11%, WGC에 0.14와 0.22%이었다.