• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2018년도 춘계학술대회 논문집
• /
• pp.141-141
• /
• 2018

Copper is one of the most abundant metals on earth. Its oxide (CuO) is an intrinsically p-type metal-oxide semiconductor with a bandgap ($E_g$) of 1.2-2.0 eV 1. Copper oxide nanomaterials are considered as promising materials for a wide range of applications e.g., lithium ion batteries, dye-sensitized solar cells, photocatalytic hydrogen production, photodetectors, and biogas sensors 2-7. Recently, high-density and uniform CuO nanostructures have been grown on Cu foils in alkaline solutions 3. In 2011, T. Soejima et al. proposed a facile process for the oxidation synthesis of CuO nanobelt arrays using $NH_3-H_2O_2$ aqueous solution 8. In 2017, G. Kaur et al. synthesized CuO nanostructures by treating Cu foils in $NH_4OH$ at room temperature for different treatment times 9. The surface treatment of Cu in alkaline aqueous solutions is a potential method for the mass fabrication of CuO nanostructures with high uniformity and density. It is interesting to compare the gas sensing properties among CuO nanomaterials synthesized by this approach and by others. Nevertheless, none of above studies investigated the gas sensing properties of as-synthesized CuO nanomaterials. In this study, CuO nanowalls versus nanoparticles were synthesized via the oxidation process of Cu foil in NH4OH solution at $50-70^{\circ}C$. The gas sensing properties of the as-prepared CuO nanoplates were examined with $C_2H_5OH$, $CH_3COCH_3$, and $NH_3$ at $200-360^{\circ}C$.

• 한국토양비료학회지
• /
• 제34권6호
• /
• pp.373-379
• /
• 2001

우리 나라 산지토양의 주요 모암에서 발달된 잔적층 암쇄를 대상으로 토양의 단면 특성, 이화학적 특성 X-선 형광분석 (XRF)을 통하여 모재에 따른 토양의 화학조성 변화와 주요한 구성원소의 풍화량을 토양층위 및 모암별로 비교하였다. 모암에 관계없이 토양의 C층에 비하여 A층에서 점토함량, 양이온 치환용량 (CEC), 유기물 함량은 높았으며, 용적밀도 ($kg\;m^{-3}$)와 pH는 낮은 경향을 보였다. 그러나 사암모재의 의성통에서는 점토함량이 감소하였는데 이는 토양과 함께 유실 되었거나 하부로 이동한 것으로 보였다. 토양 중 $SiO_2$함량은 화강암, 화강편마암, 석회암, 혈암 유래 토양에서, $Fe_2O_3$와 MgO는 현무암, 석회암, 혈암 유래 토양에서, CaO는 석회암 유래 토양에서 각각 높았다. 현무암 모재의 구좌통과 석회암 모재의 장성통 토양에서 작열감량(Igniton loss)이 크게 나타났다. 토양 화학성분별 풍화 정도는 공시 토양의 모암에 관계없이 염기이온(K, Ca, Mg, Na)들의 풍화량이 Si, Al, Fe 보다 크게 나타났다. C층과 비교하여 A층의 $TiO_2$의 함량비가 클수록 화학성분의 풍화정도가 큰 토양으로 나타났으며, 이는 $TiO_2$가 다른 원소보다 풍화에 상대적으로 안정된 광물이기 때문인 것으로 보인다. 각 원소의 절대적 함량비를 고려할 때 화강암, 화강편마암, 사암, 혈암, 현무암 유래 토양에서는 Si, Al의 유실이 심했으나 석회암 유래 토양에서는 탄산염의 빠른 풍화로 Ca, Mg이온의 풍화량이 많았다. 화학 성분의 풍회가 큰 토양은 사암 유래 의 성통과 화강암 유래 도산통 >> 혈암 유래 음성통과 석회암 유래 장성통 > 화강편마암 유래 덕산통 > 현무암 유래의 구좌통 순이었다.

• 청정기술
• /
• 제25권3호
• /
• pp.179-188
• /
• 2019

석탄화력 발전시 석탄은 석탄회로 발생하게 되는데 비회(fly ash)가 80%, 저회(bottom ash)가 20% 비율로 발생된다. 그러나 이들 대부분은 재활용되지 못하고 매립장에 전량 폐기되고 있고, 비회 및 저희를 매립하는 매립장이 포화될 경우 새로운 대체 매립장을 건설하지 못하는 한 석탄화력발전소의 운영을 중지해야 하는 경우가 발생할 수 있다. 본 연구에서는 비회를 재활용하여 자원화하기 위해 습식 부유선별기술(부선과정)을 이용하여 비회 내 유용성분{미연탄소(unburned carbon, UC), 뮬라이트(ceramic microsphere, CM), 실리카(cleaned ash, CA)}을 회수하였으며, 회수된 유용성분들의 특성분석으로 산업 소재로 재활용 가능성을 조사하였다. 비회로부터 회수된 유용성분의 회수율은 UC 92.10%, CM 75.75%, CA 69.71%로 부선과정을 통하여 UC가 다른 성분보다 회수율이 16 ~ 22% 더 우수한 것으로 나타났다. UC의 연소가능성분(combustible component, CC)은 52.54wt%, 발열량도 $4,232kcal\;kg^{-1}$로 높아서 석탄 기준 C의 함량 100%일 경우 $8,100kcal\;kg^{-1}$로 감안할 때 산업용 연료로 사용이 가능할 것으로 사료된다. CM과 CA의 분리는 pH의 영향으로 UC 보다는 화학적 분리가 효과적이었으며, 회수된 CA의 $SiO_2$ 함량은 78.66wt%, CM의 $SiO_2$ 함량은 53.55wt%로 나타나 산업용 소재로 재활용 가능성을 확인할 수 있었다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
• /
• pp.452-455
• /
• 2003

[ $ZrO_2$ ] dielectric layers were grown on the p-type Si (100) substrate by metalorganic molecular beam epitaxy(MOMBE). Zrconium t-butoxide, $Zr(O{\cdot}t-C_4H_9)_4$ was used as a Zr precursor and Argon gas was used as a carrier gas. The thickness of the layers was measured by scanning electron microscopy (SEM) and the properties of the $ZrO_2$ layers were evaluated by X-ray diffraction, high frequency capacitance-voltage measurement. and HF C-V measurements have shown that $ZrO_2$ layer grown by MOMBE has a high dielectric constant (k=18-19). The growth rate is affected by various process variables such as substrate temperature, bubbler temperature, Ar, and $O_2$ gas flows.

• Journal of Ginseng Research
• /
• 제43권1호
• /
• pp.135-142
• /
• 2019

Background: Panax ginseng Meyer, known as Korean Red Ginseng (KRG), is one of the important age-old traditional herbs used in boosting libido and improving male fertility. In this study, the effects of Rg3-enriched KRG extract (KGC04P) on heat stress-induced testicular damage in experimental rats was evaluated. Methods: Male rats (Sprague-Dawley) were divided into four groups (n = 10): normal control (NC), heat-stressed control (HC), heat-stressed plus KGC04P-100 mg/kg (HK100), and heat-stressed plus KGC04P-200 mg/kg (HK200) groups. Starting 1 week prior to heat stress, animals were administered orally with KGC04P (100 and 200 mg/kg) mixed with a regular pellet diet and continued for 25 weeks. Heat stress was induced to HC, HK100, and HK200 groups by intermittently exposing the animals to high temperatures ($32{\pm}1^{\circ}C$, 2 h/day). After 6 months, animals were euthanized under general anesthesia with carbon dioxide and evaluated for various parameters in serum and testicular tissue by using Western blotting, biochemical kits, and reverse transcription-polymerase chain reaction. Results: Significant (p < 0.05) alterations in several parameters, such as body/organ weight, sperm kinematics, and lipid metabolism marker levels, in the serum and testis of rats were observed. Further, the expression of testicular antioxidant enzymes, inflammatory cytokines, sex hormonal receptors, and spermatogenesis-related genes were also affected significantly (p < 0.05) in the heat-stressed group. However, KGC04P prevented the heat stress-induced changes in rats significantly (p < 0.05) at both concentrations. Conclusion: KGC04P attenuated heat stress-induced testicular damage by a multifunctional approach and can be developed as an excellent therapeutic agent for hyperthermia-mediated male infertility.

• 한국재료학회지
• /
• 제17권2호
• /
• pp.96-99
• /
• 2007

The effects of post-annealing of high-k $HfO_2$ thin films grown by atomic layer deposition method were investigated by the annealing treatments of $400-600^{\circ}C$. $Pt/HfO_2/p-Si\;MOS$ capacitor structures were fabricated, and then the capacitance-voltage and current-voltage characteristics were measured to analyze the electrical characteristics of dielectric layers. The X-ray diffraction analyses revealed that the $500^{\circ}C-annealed\;HfO_2$ film remained to be amorphous, and the $600^{\circ}C-annealed\;HfO_2$ film was crystallized. The annealing treatment at $500^{\circ}C$ resulted in the highest capacitance and the lowest leakage current due to the reduction of defects in the $HfO_2$ films and non-crystallization. Our results suggest that post-annealing treatments are a critical factor in improving the characteristics of gate dielectric layer.

• 한국광물학회지
• /
• 제11권1호
• /
• pp.20-31
• /
• 1998

Adsorption of metal elements onto illite and halloysite was investigated at $25^{\circ}C$ using pollutant water collected from the gold-bearing metal mine. Incipient solution of pH 3.19 was reacted with clay minerals as a function of time: 10 minute, 30 minute, 1 hour, 12 hour, 24 hour, 1 day, 2 day, 1 week, and 2 week. Twenty-seven cations and six anions from solutions were analyzed by AAs (atomic absorption spectrometer), ICP(induced-coupled plasma), and IC (ion chromatography). Speciation and saturation index of solutions were calculated by WATEQ4F and MINTEQA2 codes, indicating that most of metal ions exist as free ions and that there is little difference in chemical species and relative abundances between initial solution and reacted solutions. The adsorption results showed that the adsorption extent of elements varies depending on mineral types and reaction time. As for illite, adsorption after 1 hour-reaction occurs in the order of As>Pb>Ge>Li>Co, Pb, Cr, Ba>Cs for trace elements and Fe>K>Na>Mn>Al>Ca>Si for major elements, respectively. As for halloysite, adsorption after 1 hour-reaction occurs in the order of Cu>Pb>Li>Ge>Cr>Zn>As>Ba>Ti>Cd>Co for trace elements and Fe>K>Mn>Ca>Al>Na>Si for major elements, respectively. After 2 week-reaction, the adsorption occurs in the order of Cu>As>Zn>Li>Ge>Co>Ti>Ba>Ni>Pb>Cr>Cd>Se for trace elements and Fe>K>Mn>Al, Mg>Ca>Na, Si for major elements, respectively. No significant adsorption as well as selectivity was found for anions. Although halloysite has a 1:1 layer structure, its capacity of adsorption is greater than that of illite with 2:1 structure, probably due to its peculiar mineralogical characteristics. According to FTIR (Fourier transform infrared spectroscopy) results, there was no shift in the OH-stretching bond for illite, but the ν1 bond at 3695 cm-1 for halloysite was found to be stronger. In the viewpoint of adsorption, illite is characterized by an inner-sphere complex, whereas halloysite by an outer-sphere complex, respectively. Initial ion activity and dissociation constant of metal elements are regarded as the main factors that control the adsorption behaviors in a natural system containing multicomponents at the acidic condition.

• Biomolecules & Therapeutics
• /
• 제24권5호
• /
• pp.501-509
• /
• 2016

Shikonin, which derives from Lithospermum erythrorhizon, has been traditionally used against a variety of diseases, including cancer, in Eastern Asia. Here we determined that shikonin inhibits proliferation of gastric cancer cells by inducing apoptosis. Shikonin's biological activity was validated by observing cell viability, caspase 3 activity, reactive oxygen species (ROS) generation, and apoptotic marker expressions in AGS stomach cancer cells. The concentration range of shikonin was 35-250 nM with the incubation time of 6 h. Protein levels of Nrf2 and p53 were evaluated by western blotting and confirmed by real-time PCR. Our results revealed that shikonin induced the generation of ROS as well as caspase 3-dependent apoptosis. c-Jun-N-terminal kinases (JNK) activity was significantly elevated in shikonin-treated cells, thereby linking JNK to apoptosis. Furthermore, our results revealed that shikonin induced p53 expression but repressed Nrf2 expression. Moreover, our results suggested that there may be a co-regulation between p53 and Nrf2, in which transfection with siNrf2 induced the p53 expression. We demonstrated for the first time that shikonin activated cell apoptosis in AGS cells via caspase 3- and JNK-dependent pathways, as well as through the p53-Nrf2 mediated signal pathway. Our study validates in partly the contribution of shikonin as a new therapeutic approaches/agent for cancer chemotherapy.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
• /
• pp.332-335
• /
• 2004

Boron Phosphide films were deposited on(III) Si substrate at $650^{\circ}C$, by the reaction of $B_2H_6$ with $PH_3$ using CVD. $N_2$ was employed as carrier gas. The optimal gas rates were 20 ml/min for $B_2H_6$, 60 ml/min for $PH_3$ ml/min and $1{\ell}/min$ for $N_2$. The films were annealed for 1hour in $N_2$ ambient at $550^{\circ}C$ and measured. The measurement of AFM shows that the average surface roughness is each $10.108{\AA}$ and $29.626{\AA}$. So, we could know every commonplace thing. The measurement of XRD shows that the films have the preferred orientation of(1 0 1). From SEM images, we could see that Boron Phosphide is showed of a structure, which is grain size, which is grain boundary size. Also, the measurement of AES is shown the films have $B_{13}P_2$ Stoichiometry. From WDX See that ingredient is detected each Boron and Phosporus. So, we could see that deposited BP thin film. In this study, we obtained the BP thin film by deposited in atmosphere pressure, and known to applicate as microwave absorbtion material of BP thin film.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
• /
• pp.162-162
• /
• 2000

We have studied magnetic properties of Co/Pt multilayered films which have attracted great interest as high-density magneto-optical (MO) recording media due to their good MO properties. For this study, [Pt(45 )/Co(35 )]$\times$8 films were deposited with a Pt buffer layer of 60 on Si(100) substrate by alternating electron-beam evaporation in a high vacuum and were ion beam mixed by using 80keV Ar+ at 25$0^{\circ}C$. Especially, an external magnetic field was added to help changing magnetic property during ion beam mixing (IBM). The intermixing of Co and Pt layers after IBM was confirmed with Rutherford Backscattering Spectroscopy (RBS) and Transmission Electron Microscopy (TEM). The MO property of the film was measured with magneto-optical Kerr spectrometer and the change of magnetic easy axis in the film plane was observed from Ker loop data. This anomalous result might be correlated with the change of atomic structure due to the intermixing effect.