• Korean Chemical Engineering Research
• /
• 제53권1호
• /
• pp.39-45
• /
• 2015

We produced magnetite nanoparticles (MNPs) and a Mg-rich solution as a nano-adsorbent and a coagulant for water treatment, respectively, using a low-grade iron ore. The ore was leached with aqueous hydrochloric acid and its impurities were removed by solvent extraction of the leachate using tri-n-butyl phosphate as an extractant. The content of Si and Mg, which inhibit the formation of MNPs, was reduced from 10.3 wt% and 15.5 wt% to 28.1 mg/L and < 1.4 mg/L, respectively. Consequently, the Fe content increased from 68.6 wt% to 99.8 wt%. The high-purity $Fe^{3+}$ solution recovered was used to prepare 5-15-nm MNPs by coprecipitation. The wastewater produced contained a large amount of $Mg^{2+}$ and can be used to precipitate struvite in sewage treatment. This process helps reduce the cost of both sewage and iron-orewastewater treatments, as well as in the economic production of the nano-adsorbent.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1993년도 지하공간 건설기술에 관한 서울 심포지움 논문집
• /
• pp.235-247
• /
• 1993

The 62 m span Olympic lee Hockey cavern in Gjovik, Norway, is located in jointed gneiss of average RaD = 70% and has a rock cover of only 25 to 50m, thus posing challenging design p problems. The investigations prior to construction included two types of stress measurements, cross-hole seismic tomography, special coe logging, Q-system classification and numerical modelling with UDEC-BB. Predicted maximum deformations were 4 to 8 mm; surprisingly small due to the high horizontal stresses recorded. Extensometer (MPBX) installations from the surface prior to construction, precision surface levelling and MPBX installed from inside the cavern give a combined measure of maximum deformations in the range 7 to 8 mm with the 62 m span fully e excavated, and three adjacent caverns for the Postal Services also completed.

• 한국세라믹학회지
• /
• 제49권1호
• /
• pp.105-110
• /
• 2012

In this paper, a yellow phosphor $Sr_3SiO_5:Eu^{2+}$ that emits efficiently at the 450 nm excitation for warm white LED is studied. In addition, the effects of various flux $BaF_2$, $NH_4Cl$ on the emission spectra were investigated. The samples were synthesized through conventional solid state reaction under reducing atmosphere of 95% $N_2$-5% $H_2$ mixture at the high temperature. All phosphors showed a excitation band from 450 nm and broad band emission peaking at region of 580 nm. The optimal concentration of $BaF_2$ flux is 3 wt% for $Sr_3SiO_5$ with doping 0.05mol Eu phosphors fired in a reductive atmosphere. The phosphor showed highest emission peaking at 582 nm.

• 한국군사과학기술학회지
• /
• 제27권3호
• /
• pp.338-345
• /
• 2024

Magnetic anomaly signals from the ferromagnetic targets such as ships in the sea are measured by drone-based magnetic anomaly detection. A quantum magnetometer is suspended from the drone by 4 strings. Flight altitude and speed of drone are 100 m and 5 m/s, respectively. We obtain magnetic anomaly signals of few nT from the ships clearly. We analyze the signal characteristics by the ferromagnetic target through simulation using COMSOL multiphysics.

• 폴리머
• /
• 제25권2호
• /
• pp.263-269
• /
• 2001

나트륨 몬모릴로나이트($Na^{+}$-MMT)의 양이온을 3-(methacryloyl amino) propyl trimethyl ammonium chloride (MAPTAC)와 교환반응시켜 몬모릴로나이트의 표면을 친유성으로 개질시키는 동시에, 단량체와 공중합을 할 수 있는 이중결합이 부착된 MAPTAC-MMT를 제조하였다. 상온에서 MAPTAC-MMT가 분산된 수용액에서 N-isopropyl acryl amide (NIPAM)를 중합하여 열응답성 나노복합재료(PNIPAM-MMT)를 제조하였다. MAPTAC-MMT으로부터 제조된 열응답성 나노복합재료는 열응답성 고분자인 poly(N-isopropyl acrylamide) (PNIPAM)와 마찬가지 하한임계용액온도(LCST)를 나타내었으며, MAPTAC-MMT의 양이 증가함에 따라 PNIPAM-MMT의 LCST는 감소하였다. 또한 TGA실험 결과에서 열응답성 나노복합재료의 열안정성이 열응답성 고분자에 비하여 우수하였음을 보였다.

• Journal of Ginseng Research
• /
• 제7권1호
• /
• pp.74-79
• /
• 1983

Effect of soil moisture on content and partition of mineral nutients in panax ginseng (2 years old) was investigated. Similarity was found between N and p, Ca and Mg, K and Fe. Mn and Zn were quite different each other and from others. Nutrient partition was affected more by nutrient content than by dry matter. Under suboptimal moisture condition partition to shoot was inhibited in order of Mg, Zn, Ca, Mg, N and P while accelerated in odor of Fe. K and Mn. Under supraoptimal moisture condition Partition to shoot was inhibited in order of Zn, Fe, K, and Ca, while accelerated in order of Mg, N, Mn and p.

• 한국분말재료학회지
• /
• 제12권3호
• /
• pp.192-200
• /
• 2005

Ultrafine copper powder was prepared from $CuO-H_2O$ slurry with hydrazine, a reductant, under $70^{\circ}C$. The influence of various reaction parameters such as temperature, reaction time, molar ratio of $N_2H_4$, PvP and NaOH to Cu in aqueous solution had been studied on the morphology and powder phase of Cu powders obtained. The production ratio of Cu from CuO was increased with the ratio of $N_2H_4/Cu$ and the temperature. When the ratio of $N_2H_4/Cu$ was higher than 2.5 and the temperature was higher than $60^{\circ}C$, CuO was completely reduced into Cu within 40 min. The crystalline size of Cu obtained became fine as the temperature increase, whereas the aggregation degree of particles was increased with the reaction time. The morphology of Cu powder depended on that of the precursor of CuO and processing conditions. The average particle size was about $0.5{\mu}m$.

• 대한지역사회영양학회지
• /
• 제7권1호
• /
• pp.111-120
• /
• 2002

Postmenopausal women lose more bone mass than men as a result of estrogen deprivation. The resultant low bone mineral density (BMD) is a major risk factor in the development of osteoporosis. Calcium, phosphorus and magnesium are main components of bone. The purpose of this study is to investigate nutrient intake and serum osteocalcin, Ca, P and Mg and their correlation to bone mineral density in Korean postmenopausal women residing in rural areas. We conducted 24 hour dietary recalls, anthropometric measurements and blood analysis on 60 postmenopausal women. The BMD of the lumbar spine (L2$\rightarrow$L4) and the femoral neck were measured by dual energy X-ray absorptiometry (DEXA). Subjects were assigned to one of three groups:normal (T-score> -1, n=20), osteopenia (-2.5> T-score $\leq$ -1, n=23), and osteoporosis ( T-score $\leq$ -2.5, n=17). The mean age, height, weight and BMI were 62.37 yr, 154.36 cm, 55.28 kg and 23.18 $kg/m^2$ respectively. The mean daily energy and protein intakes were 76.35% and 87.41% of RDA for Koreans. The mean intakes of calcium, phosphorus, and magnesium were 463.62 mg (66.23% of RDA), 955.32 mg (136.47% of RDA), 345.87 mg respectively. The mean serum levels of calcium, phosphorus and magnesium were 8.76 mg/dl, 3.80 mg/dl, and 2.10 mg/dl, respectively, and there were no significant differences among the three groups. However, the BMD of the femoral neck showed a significantly negative correlation with serum magnesium (p<0.05). To summarize the results, most nutrient intakes (especially calcium) in postmenopausal women did not reach the RDA values for Koreans. Also, increase of serum magnesium levels may be related to bone loss.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
• /
• pp.303-306
• /
• 2004

The objective of this study was to examine the infiltration pattern in a soil developed from granite using tile nonfluorescent and nontoxic food dye, Brilliant Blue FCF (C$_{37}$ $H_{34}$$N_2$Na$_2$$O_{9}$S$_3$) as the dye tracer. A homogeneous matrix flow occurred in the A horizon with weak, medium granular structure and fingering at the interface of finer-textured A horizon and coarser-textured C horizon. Pegmatitic vein originated from the granite and plant root in C horizon induced preferential flow.w.

• 생명과학회지
• /
• 제10권6호
• /
• pp.543-547
• /
• 2000

Quartz porphyry (QP) on the contents of mineral tissues of male common finch by feeding the basal diet (Control group) containing 3.0% QP (QP group) for 14 days was studied. The relative weight (mg/10 g body weight) of kidney and gizzard in the QP group were higher and lower than in the control group, respectively. However, the relative weight of liver and heart were not significantly different in the both groups. The mineral contents of liver, kidney, heart and gizzard were significantly higher in common finch fed with the diet containing quartz porphyry than that of control diet. The major minerals of these tissues were P, Ca and Fe.