• 자원리싸이클링
• /
• 제6권1호
• /
• pp.5-10
• /
• 1997

알루미늄 드로스로부터 알루미늄 회수에 관한 연구를 행하였다. 알루미늄 드로스의 발생량이 가장 많은 중립(1.0~12.0mm)의 드로스를 시료로 하여 $850^{\circ}C$의 용해온도와 용해 2시간에서 염화나트륨과 염화칼륨의 첨가 영향은 40% 첨가시 약 76.9%로 최대 회수율을 얻었으며, 그 이상 첨가는 점성의 증가로 회수율에 별 영향을 미치지 않았다. 한편, 40%의 기본염용제에 NaF, $CaF_2$, $AlF_3$ 및 ${Na}_{3}{AlF}_{6}$ 첨가시 5%에서 최대 회수율을 나타내었으며, 특히 5%의 빙정석 첨가시 약 83.5%의 최대 회수율을 얻을 수 있었다. 그러나 불화물을 5% 이상 첨가시에는 점성이 증가하여 알루미늄 회수율에 큰 영향을 미치지 않았다.

• 한국세라믹학회지
• /
• 제43권6호
• /
• pp.338-343
• /
• 2006

The effects of lead-borosilicate glass frits on the sintering behavior and microwave dielectric properties of ceramic-glass composites were investigated as functions of glass composition of glass addition ($10{\sim}50vol%$), softening point (Ts) of the glass, and sintering temperature of the composites ($500{\sim}900^{\circ}C$ for 2 h). The addition of 50 vol% glass ensured successful sintering below $900^{\circ}C$. Sintering characteristics of the composites were well described in terms of Ts. PbO addition in to the glass enhanced the reaction with $Al_{2}O_3$ to form liquid phase and $PbAl_{2}Si_{2}O_8$, which was responsible to lower Ts. Dielectric constant(${\epsilon}_r$), $Q{\times}f_0$ and temperature coefficient of resonant frequency (${\tau}_f$) of the composite with 50 vol% glass contents ($B_{2}O_{3}:PbO:SiO_{2}:CaO:Al_{2}O_3$ = 5:40:45:5:5) demonstrated 8.5, 6,000 GHz, $-70\;ppm/^{\circ}C$, respectively, which is applicable to substrate requiring a low dielectric constant. When the same glass composition was applied sinter $MgTiO_3\;and\;TiO_2,\;at\;900^{\circ}C$ (50 vol% glass in total), the properties were 23.8, 4,000 GHz, $-65ppm/^{\circ}C$ and 31.1, 2,500 GHz, $+80ppm/^{\circ}C$ respectively, which is applicable to filter requiring an intermidiate dielectric constant.

• Environmental Engineering Research
• /
• 제17권3호
• /
• pp.133-138
• /
• 2012

Polyvinyl alcohol/alginate hydrogel beads containing Mg-Al layered double hydroxide (LDH-PVA/alginate beads) were synthesized for phosphate removal. Results showed that blending PVA with the LDH-alginate beads significantly improved their stability in a phosphate solution. The kinetic reaction in LDH-PVA/alginate beads reached equilibrium at 12 hr-post reaction with 99.2% removal. The amount of phosphate removed at equilibrium ($q_e$) was determined to be 0.389 mgP/g. The equilibrium data were described well by the Freundlich isotherm with the distribution coefficient ($K_F$, 0.638) and the constant (n, 0.396). Phosphate removal in LDH-PVA/alginate beads was not sensitive to solution pH. Also, the removal capacity of LDH-PVA/alginate beads ($q_e$, 1.543 mgP/g) was two orders of magnitude greater than that of PVA/alginate beads ($q_e$, 0.016 mgP/g) in column experiments. This study demonstrates that LDH-PVA/alginate beads with a higher chemical stability against phosphate compared to LDH-alginate beads have the potential for phosphate removal as adsorptive media.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제27권6호
• /
• pp.47-57
• /
• 2022

A number of different methods have been used for modeling the sorption of volatile organic chlorinated compounds such as tetrachloroethylene/perchloroethylene (PCE). In this study, PCE was adsorbed in several natural sorbents, i.e., Pahokee peat, vermicompost, BionSoil^®, and natural soil, in the batch experiments. Several sorption models such as linear, Freundlich, solubility-normalized Freundlich model, and Polanyi-Manes model (PMM) were used to analyze sorption isotherms. The relationship between sorption model parameters, organic carbon content (f_oc), and elemental C/N ratio was studied. The organic carbon normalized partition coefficient values (log K_oc = 1.50-3.13) in four different sorbents were less than the logarithm of the octanol-water partition coefficient (log K_ow = 3.40) of PCE due to high organic carbon contents. The log K_oc decreased linearly with log f_oc and log C/N ratio, but increased linearly with log O/C, log H/C, and log (N+O)/C ratio. Both log K_F,oc or log K_F,oc decreased linearly with log f_oc (R² = 0.88-0.92) and log C/N ratio (R² = 0.57-0.76), but increased linearly with log (N+O)/C (R² = 0.93-0.95). The log q_max,oc decreased linearly as log f_oc and log C/N increased, whereas it increased with log O/C, log H/C and log (N+O)/C ratios. The log q_max,oc increased linearly with (N+O)/C indicating a strong dependence of q_max,oc on the polarity index. The results showed that PCE sorption behaviors were strongly correlated with the physicochemical properties of soil organic matter (SOM).

• 천문학회보
• /
• 제42권1호
• /
• pp.49.3-50
• /
• 2017

Metallicity is one of the most important properties in understanding galaxy evolution. However, measuring metallicity is limited to low redshift (z<3.5) due to the faintness of the metallicity indicators in normal galaxies. For high redshift universe, active galactic nuclei (AGN) can be used to constrain the host galaxy metallicity. Previous studies investigated AGN metallicity using emission line flux ratios (i.e., NV/CIV and FeII/MgII), finding no evolution up to z~6. Those results might be due to selection effect since previous studies are based on very luminous AGNs. The observed luminosity-metallicity relation of AGNs (e.g., Nagao et al. 2006) suggests that luminous AGNs may be already matured at the observed epoch. Considering the luminosity-metallicty relation, we focused on low luminosity AGNs to find young AGNs (i.e., low metallicity). Through the Gemini/GNIRS observation in 2012A and 2015A (K-GMT GN-2015A-Q-203 PI: Shin, J.), we obtained the Gemini/GNIRS data for 7 high redshift AGNs (3.0

• 한국농림기상학회지
• /
• 제4권1호
• /
• pp.49-57
• /
• 2002

본 연구는 경기도 광주군 퇴촌면 소재 경희대 연습림의 산림토양을 대상으로 인공산성우의 회수별 유입에 따른 산림토양의 완충능에 미치는 영향을 구명하고자 pH 3.0, pH 4.0, pH 5.0 인공산성우를 하루에 1시간 간격으로 10회 유입하여 얻은 결과는 다음과 같다. 각 임지(활엽수, 리기다소나무, 잣나무, 낙엽송)의 토심별(0~15 cn, 15~30 cm) pH를 측정한 결과 모든 임지에서 토심이 깊을수록 토양 pH가 높았다. 또한 각 임지별 염기포화도를 살펴보면 리기다소나무 임지에서 17.42%로 가장 높게 나타났으며 C.E.C는 활엽수임지의 경우 29.87 me/100 g으로 가장 높았다. 인공산성우 회수별 유입 토양용탈수의 pH 변화를 보면 pH 3.0 처리에서 인공산성우 유입회수가 증가함에 따라 초기에는 일시적으로 높아지다가 다시 낮아지는 변곡성을 보였으며, 나머지 pH 4.0과 pH 5.0에서는 토양 용탈수의 pH가 비례적으로 증가하였다. 인공산성우의 pH 수준과 임지에 따라 초기 용탈량은 차이가 있으나 모든 처리에서 인공산성우의 유입회수가 증가함에 따라 염기성 이온의 용탈량은 감소하였다. 또한 pH 5.0 처리에 비하여 pH 3.0과 pH 4.0의 인공산성우 처리에서 총 염기성 양이온의 초기 용탈량이 더 컸으며 이러한 경향은 토양 산성도가 낮고 토양의 염기성 양이온이 높은 임지일수록 뚜렷한 차이를 보였다. 활성 Al의 초기 용탈은 토양 산성도가 높은 지역일수록, 인공산성우의 유입산도가 클수록 높게 나타났다. 또한 토심별로 확인해 본 결과 A층과 AB층간의 Al 용탈량도 소폭의 차이가 있음이 확인되었다. 인공산성우 pH 3.0 처리에서는 모든 임지에서 Al 활성 변화가 정의 관계를 나타내었는데 이는 pH 4.0과 pH 5.0에서의 용탈수와는 반대되는 경향이었으며, 총 염기성 양이온과도 반대되는 경향이 나타났다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
• /
• 제52권11호
• /
• pp.501-507
• /
• 2003

In this study, microscale, high-performance, solenoid-type RF chip inductors were investigated. The size of the RF chip inductors fabricated in this work was 1.0${\times}$0.5${\times}$0.5㎣. 96% $Al_2$ $O_3$and I-type were used as the material and shape of the core, respectively. The copper (Cu) wire with 6 turns was employed as the coils. The diameter (40${\mu}{\textrm}{m}$) and position (middle) of the coil and the length (0.35mm) of solenoid were determined by a high-frequency structure simulator (HFSS) to maximize the performance of the inductors. High frequency characteristics of the inductance (L) and quality-factor (Q) of developed inductors were measured using an RF Impedance/Material Analyzer (HP4291B with HP16193A test fixture). The inductors developed have inductances of 10.8nH and quality factors of 25.2 to 50 over the frequency ranges of 250MHz to l GHz, and show results comparable to those measured for the inductors prepared by CoilCraf $t^{Tm}$ . The simulated data predicted the high-frequency data of the L and Q of the inductors developed well.l.

• 유통과학연구
• /
• 제22권3호
• /
• pp.59-70
• /
• 2024

Purpose: This study aimed to develop a strategic business conceptual model for large state plantations in West Java Province and Banten Province, Indonesia. The model was built through causal relationships and interrelationships between marketing strategies and business strategies that affect business performance on large state plantations. The plantation sector provides the largest contribution to gross domestic product and is an important part of national food distribution efforts. Research design, data, and methodology: This study used a literature review adapted from Pret and Logan (2019), which followed the guidelines of Tranfield et al. (2003), derived from the Scopus website with Q1/Q2 quartiles and inclusion/exclusion criteria published from 2012 to 2021. Results: Based on a systematic literature review approach, we constructed the strategic business conceptual model for large state plantations based on a combination of four causal and interrelationship variables that affect business performance, namely, industry attractiveness, unique capabilities, innovation management, and collaboration strategy. Conclusions: This research explains the relationship between industry attractiveness variables and unique capability as independent variables that can affect business performance through collaboration strategy and innovation management as intervening variables in the plantation sector, especially large state plantations, which have not been found in previous studies.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 추계학술대회 논문집
• /
• pp.103-106
• /
• 1999

Organic electroluminescent devices (OELDs) have received a great deal of attention due to their potential application as full-color displays. Europium complexes are known as excellent red light-emitting materials for OELDs since they show intense photoluminescence at around 612 nm with a narrow spectral bandwidth. In this study, a novel curopium complex, Eu(TTA)$_3$(TPPO) was synthcsizcd and its photoluminescent and electroluminescent characteristics were investigated with a device structure of ITO/TPD/Eu(TTA)3(TPPO)/A1q$_{3}$ Al, where sharp emission at the wavelength of 615 nm has been observed. Details on the electrical properties of these structures will be also discussed.

• Journal of Astronomy and Space Sciences
• /
• 제10권2호
• /
• pp.123-145
• /
• 1993

충북대학교 천문우주학과의 UBVRI 측광기가 부착된 20 cm 망원경을 이용하여 1988년 12월부터 1991년 3월 사이의 33일밤 동안 Algol을 광전측광 관측하여 총 3465점의 관측값을 얻었다. 이 관측값을 이용하여 UBVRI 광도곡선을 만들었고 5개의 극심시각 JDHel 2447898.0938, JDHel 2447908.1014, JDHel 2448265.1205, JDHel 2448288.0598, JDHel 2448275.146 을 결정하였다. 우리가 얻은 UBVRI 광도곡선을 동시에 Wilson-Devinney 방법으로 분석하여 측광학적 해를 구했다. 이 해로 부터 얻은 i= $82.{\circ}47$, q=0.227, $r_1$=0.2102, $r_2$=0.2512와 Hill et al.(1971)의 분광학적 해의 인수들을 이용하여 Algol A,B,C, 각각에 대한 질량에 반경을 $m_1$=3.36, $m_2$=0.76, $m_3$=1.6, $R_1$=2.97, $R_2$=0.76과 같이 구했다. 여기서 사용한 단위는 태양질량 단위와 태양반경 단위이다. 이러한 우리의 결과들은 Kim(1989)이 보고한 값들과 대체로 비슷하다. 우리의 해로 부터 은 5색의 $l_1$, $l_2$, $l_3$ 값들을 Planck 곡선에 fitting 시키는 방법에 의해 Algol C의 온도를 $T_3$=8800로, 그리고 $R_3$=$1.6R_\odot$을 유도했다. Algol A와 B의 배치 형태가 준접촉형인 것은 case B 질량 이동에 의해 생긴 결과로 믿어지며, 질량-반경동에 나타난 이들의 위치에 의하면 Algol B는 수소연소 단계에서도 상당히 진화된 상태에 있는 것으로 추정된다.로 추정된다.