• 한국재료학회지
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• 제27권3호
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• pp.172-178
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• 2017

The aim of this study is to consider the effect hydrogen on dezincification behavior of Cu-Zn alloys. The investigations include microstructural observations with scanning electron microscope and chemical composition analysis with energy dispersive spectrometer. The dezincification layer was found to occur in high pressure hydrogen atmosphere, not in air atmosphere. In addition, the layers penetrated into the inner side along the grain boundaries in the case of hydrogen condition. The shape of the dezincification layers was porous because of Zn dissolution from the ${\alpha}$ or ${\beta}$ phase. In the case of stress corrosion cracks formed in the Cu-Zn microstructure, the dezincification phenomenon with porous voids was also accompanied by grain boundary cracking.

• Journal of Pharmaceutical Investigation
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• 제24권3호
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• pp.109-113
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• 1994

Effects of various formulation factors using $L_8$ orthogonal arrays with the stability of doxorubicin hydrochloride injections(DHls) were investigated. The degradation of DHI may be occured by pH, temperature, light and metal ions. It is known that DHI should be stored on refrigerated condition of $4{\sim}8^{\circ}C$ because of its unstability on the room temperature. The employed factors were sodium chloride as isotonic solution, sodium bisulfite or sodium pyrosulfite as an antioxidant, disodium edetate as a chelating agent, methyl parahydroxybenzoate as a dissolution time shortening agent, and hydrochloric acid or citric acid as a pH adjusting agent at $22^{\circ}C$. From the results of $L_8$ orthogonal arrays, an optimal formula, including sodium chloride, disodium edetate, sodium bisulfite and hydrochloric acid, was obtained and the shelf-life of the formula was determined as 560 days approximately.

• 분석과학
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• 제6권1호
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• pp.141-147
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• 1993

Fe-Ni-Mn-(Ti)계 마르에이징강을 용체화처리한 후 $400^{\circ}C$부터 $550^{\circ}C$ 사이에서 장시간 시효처리할 때 생성되는 역변태 오스테나이트의 거동을 투과전자현미경 및 분석전자현미경을 이용하여 관찰하였다. 시효온도와 시간에 따라 Widmanstatten, granular, lath-like 및 재결정 오스테나이트 등 4 종류의 역변태 오스테나이트가 관찰되었으며, 역변태 오스테나이트들은 기지조직인 마르텐사이트보다 많은 니켈과 망간을 함유하고 있었다. Widmanstatten과 lath-like 오스테나이트는 기지 조직과 일정한 방위관계를 이루고 있으며 방위관계는 시효조건과 합금조성에 따라 달라진다. 재결정 오스테나이트는 $550^{\circ}C$ 이상의 고온에서 시효할 때 생기지만 불안정하여 냉각시 다시 마르텐사이트로 변태되는 경우도 발견되었다.

• 열처리공학회지
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• 제6권4호
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• pp.185-193
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• 1993

The effect and Condition of heat treatment on the tensile strength of welded joint was investigated in 300 grade 18% Ni-Co-Mo-Ti maraging steel sheets welded with electron beam. A good tensile strength of welded joint was obtained by following heat treatment cycle ; At $1100^{\circ}C$ the specimen was high temperature solution treated for 1 hour and then it was repeated solution treated at $900^{\circ}C$, $820^{\circ}C$ for 1 hour respectively to recrystallize the coarsened ${\gamma}$ grain. These heat treatment cycle was completed by an final aging heat treatment at $480^{\circ}C$ for 4 hour. Moreover, dissolution of dendrite, a significant decrease in seregation of Mo, Ti in weld metal were observed and also the coarsened ${\gamma}$ grain formed at $1100^{\circ}C$, $1200^{\circ}C$ changed to fine grain due to the effect of recrystallization.

• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3233-3237
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• 2010

A $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode was modified by coating with Li-La-Ti-O, and the effect of the coating thickness on their electrochemical properties was studied. The thickness of the coating on the surface of $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ was increased by increasing the wt % of the coating material. The rate capability of the Li-La-Ti-O-coated electrode was superior to that of the pristine sample. 1- and 2-wt %-coated samples showed considerable improvement in capacity retention at high C rates. However, the rate capability of a 5-wt %-coated sample decreased. All the coated samples showed a high discharge capacity and slightly improved cyclic performance under a high cut-off voltage (4.8 V) condition. Results of a storage test confirmed that the Li-La-Ti-O coating layer was effective in suppressing the dissolution of the transition metals as it offered protection from the attack of the acidic electrolyte. In particular, the 2- and 5-wt %-coated samples showed a better protection effect than the 1-wt %-coated sample.

• 한국물환경학회지
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• 제22권1호
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• pp.172-176
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• 2006

Fe(III)-Coated Star Fish (ICSF) was prepared by reaction of calcined Star Fish (SF) with Fe(III) solution at an elevated temperature. To investigate the stability of ICSF at acidic condition, dissolution of Fe was studied at pH 2 as a function of time. Extracted iron was negligible over the entire reaction time. This stability test suggests the applicability of ICSF in the treatment of wastewater even at low pH. Adsorption capacity of Cu(II) onto SF and ICSF was investigated in a batch and a column test. In the pH-edge adsorption, adsorption of copper onto SF and ICSF was quite similar over the entire pH range due to the presence of an important amount of Fe in SF itself. From the adsorption isotherm obtained with variation of the concentration of Cu(II), ICSF showed 1.6 times greater adsorption capacity than SF. Also, ICSF showed a greater removal capacity of Cu(II) in the column test.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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• pp.183-188
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• 2002

With the contact pad consisted of $0.5{\mu}{\textrm}{m}$ $Au/5{\mu}{\textrm}{m}$ Ni/Cu layers on a conventional ball grid array(BGA) substrate, metallurgical reaction properties between the pad and In-15(wt.%)Pb-5Ag solder alloy were studied after reflow and solid aging. In as-reflow condition, thin AuIn$_2$or Ni$_{28}$In$_{72}$ intermetallic layer was formed at the solder/pad interface according to reflow time. Dissolution of the Au layer into the molten solder was remarkably limited in comparison with eutectic Sn-37Pb alloy. After solid aging of 300 hrs, thickness of In-Ni layer increased to about $2{\mu}{\textrm}{m}$ in the both as-reflow case. It was observed that In atoms diffuse through the AuIn$_2$phase to react with underlaying Ni layer. The metallurgical reaction properties between In-l5Pb-7Ag alloy and Au/Ni surface finish were analysed to result in suppression of Au-embrittlement in the solder joints.

• 생명과학회지
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• 제9권3호
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• pp.241-247
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• 1999

Antibiotics have been routinely used to control the disease of farm-raised animals in the aquaculture facilities without any criterion based on a pharmacokinetic study. This lack of information on the effective usage of antibiotics would have brought the farmers to use excessive and/or less dosages, causing the advent of drug-resistant bacteria as well as economic loss and possible contamination of the local farming area. Until recently, few studies on a detailed manual for the antibiotic usage including chemotherapy procedure, dosage, and treatment schedule of the aquatic antibiotics have been conducted throughout the world. To the worse, there is no available criterion for optimal usage of aquatic antibiotics to control diseases in aquatic farms in this country because every country has its own aquacultural system. Therefore, based on the previous studies on the usage of the various antibiotics, our studies are to focus on the development of optimal method for the detection of various antibiotics on the fate of antibiotics applied to the fish, including absorption, circulation, and secretion physiology. Pharmacokinetic study were to sep up the optimal detective condition against residual antibiotics of fish by HPLC. The grinding pefloxacin for 15 min is most effective in dissolution test and pharmacokinetic parameters. Pharmacokinetic parameters were satisfactory for 15 min-grinding products and they can be explained as one-compartment model.

• 한국환경복원기술학회지
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• 제8권5호
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• pp.1-9
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• 2005

This study was conducted to investigate the effect of aquatic plant as a botanical air purification on the indoor air pollution by formaldehyde. Three aquatic plants such as Eichhornia crassipes, Cyperus alternifolius, Echinodorus cordifolius, were selected for this study and they were placed in the artificially contaminated chamber under laboratory condition. The results showed that all three plants could remove the formaldehyde from the contaminated air system effectively. Reduction in the formaldehyde levels by Eichhornia crassipes, which is the floating plant, might be associated with the factors of plant and water. Reduction in the formaldehyde levels by Cyperus helferi and Echinodorus cordifolius, which were emergent plant, was due to the complex effect of plant, soil medium and water. In aquatic plant system, dissolution, microbial degradation in rhizosphere, uptake through root and shoot, sorption to soil and shoot, hydrolysis are known as the main mechanisms of water soluble pollutants in the given system. The advantages of indoor air quality control system using aquatic plants can be; 1) various purifying mechanisms than foliage plants, 2) effective for decontamination of water soluble pollutants; 3) easy for maintenance; 4) diverse application potential. Therefore it was suggested from the results that indoor air control system of aquatic plants should be more effective for reduction of indoor air pollutants.

• 자원환경지질
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• 제24권3호
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• pp.219-226
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• 1991

High quality quartz crystals are grown in 0.5N NaOH + LiOH solution on the seed crystal at $370-395^{\circ}C$ and $1200-1300kg/cm^2$ condition. Growth rates are determined by the crystal thickness grown on the seed crystals with Z(0001) and X($11\bar{2}0$) direction. Relatively high growth rate of Z(0001) direction gradually changes as the temperaure difference (${\Delta}$ Ti) between growth and dissolution zones from 25 to $10^{\circ}C$. The X axis direction is affeced by ${\Delta}$ Ti, and +X($11\bar{2}0$) direction shows a high growth rate than -X($\bar{1}\bar{1}20$) direction. According to the variation with kinds of solutions used, the crystal growth that in NaOH solution is found to be slower than that in $Na_2CO_3$ solution. However, for the case in the NaOH solution mixed with LiOH, it shows a favorable growth rate in terms of grown crystal quality.