• 한국결정학회지
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• 제4권1호
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• pp.42-48
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• 1993

K6P4Ol3 응제를 사용하여 TSSG법에 의해 KTP(K Tiop04) 단결정을 성장시켰다. 가열로의 내부에 heatpipe와 복사방열판을 설치하여 도가니 내의 온도 안정성 및 균일도를 향상시켰다. 크고 양질의 단결정을 얻기 위한 목적으로 조업온도 구간,초기 냉각속도, 강제교반, 융제의 재사용과 같은 몇 가지 조업변수들에 따른 영향을 비교 고찰하였다. 본 융제의 조건하에서(0.6g KTP/lg flux), 초기 냉각속도가 0.1℃/hr 이하까지 느릴수록, 적절한 결정 회전이 수반될수록 양질의 단결정성장에 유리하였다. 최대 44 × 39 ×17체 크기의 KTP단결정을 얻을 수 있었으며, 단순가공 상태하에서도 21.3% SHG 변환효율을 나타내었다.

• Journal of Pharmaceutical Investigation
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• 제12권3호
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• pp.55-63
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• 1982

The dissolution kinetics for polymorphs of sulpiride, the effect of polyethylene glycol 4000 on the dissolution kinetics of sulpiride polymorphs and the dissolution rate difference between the tablets of polymorph form I and form II were investigated. The results could be summerized as followings: 1. The dissolution rates of two polymorphs of sulpiride were significantly different and the thermodynamic parameters calculated from dissolution kinetics were as follows; transition temperature $98^{\circ}C$, enthalpy change, -2.108 kcal/mole, free energy change, -783 cal/mole $(31.0^{\circ}C)$. 2. The dissolution rates of the two polymorphs of sulpiride containing polyethylene glycol 4000 were significantly diefferent in 0.01N HCl but the effect of polyethylene glycol on the dissolution rates of two polymorphs was not significant at low concentration of polyethylene glycol 4000. The study on the effect by stirring speed showed that at lower stirring speed the promotion rate of dissolution of polymorph form I is greater than that of form II. 3. In the case of tablets the dissolution rates of polymorph form I of sulpiride was two fold as compared with the results obtained from form II.

• Membrane and Water Treatment
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• 제4권4호
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• pp.277-291
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• 2013

The transport and recovery of Levafix brilliant red E-4BA and Levafix brilliant red E-6BA were investigated using polytetrafluoroethylene (PTFE) fiber based supported liquid membrane containing tetra butyl ammonium bromide (TBAB) in coconut oil as a carrier. The influencing parameters studied are: pH of the feed solution, concentration of dye in the feed solution, extractant concentration, and various kind of stripping agent, rate of stirring, time of transport, reusability of membrane and stability of membrane. Increase in TBAB concentration inside the membrane enhances the flux with its maximum value at $1.553{\times}10^{-4}$ M TBAB. Further increase in the concentration of TBAB leads to decreased rate of transport due to increase in viscosity of membrane liquid. The optimum conditions for dye transport are: pH of feed ($7{\pm}0.1$), $1.553{\times}10^{-4}$ M extractant concentration, 350 rpm for stirring, $4.9{\times}10^{-1}$ M potassium hydrogen phthalate as a stripping solution, the time of transport 6 h. It was noticed that flux values were increased with increasing dye concentration in the feed phase. Applying this study to textile wastewater, dyes were transported up to 98% in 6 h. This recovery technique is rewarding to environment and economic.

• KSBB Journal
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• 제19권3호
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• pp.226-230
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• 2004

볏짚 가수분해물로부터 xylitol 생산능력이 가장 우수하다고 알려진 Candida mogii ATCC 18364의 xylose 발효특성에 관한 기초연구를 수행하였다. 상업적인 자일로즈로부터 C. mogii게 의해 xylitol을 생산할 때 수율과 속도에 미치는 여러 영향을 검토한 결과, 포도당을 함유한 기질에서 12시간 배양한 종균을 3.0 g/L의 농도로 접종하여 발효시켰을 때 가장 좋은 결과를 얻었다. 또한 xylose 발효에서 가장 중요한 요인인 용존산소 농도의 영향을 알아보기 위해, 2 L 발효조에서 통기량과 교반속도를 조절해 가면서 xylitol 생산을 비교 검토하였다. 농축균과 10% 접종균을 사용했을 경우 모두, 1 vvm의 통기량과 200 rpm의 교반속도에서 xylitol 생산이 가장 우수하였다.

• Journal of Microbiology and Biotechnology
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• 제19권11호
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• pp.1374-1378
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• 2009

Response surface methodology (RSM) examining the effects of five-level-three-factors and their mutual interactions was utilized to optimize the fermentation conditions to enhance capsular polysaccharide (CPS) production of Streptococcus pneumoniae type 3. Twenty experiments conducted in an 8-l lab-scale fermentor were designed to assess fermentation pH, supplemented glucose concentration, and stirring rate. The predicted highest CPS production by the obtained optimization model equation was 256.14 mg/l at optimal conditions [pH 7.5, stirring rate 180 rpm, and supplemented glucose concentration 1% (w/v)]. The validity of the response model was confirmed by the good agreement between the predicted and experimental results. The maximum amount of CPS obtained was $255.03\pm2.23$ mg/l.

• Journal of Pharmaceutical Investigation
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• 제29권4호
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• pp.315-321
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• 1999

Poly (lactide-co-glycolide) (PLGA) microspheres containing ovalbumin (OVA) as a model protein drug were prepared by double emulsification method, and various conditions such as mixing rate, volume of outer phase and isopropyl alcohol concentration in outer phase during secondary emulsification were observed to control the size of microspheres. In addition, entrapment efficiency of OVA and protein denaturation were also evaluated. As the rate of stirring was increased, the size of particles was decreased. But excessive stirring increased the particle size of microspheres. In a preparation condition of small volume of outer phase, the particle size was decreased but the entrapment efficiency was increased. Adding isopropyl alcohol to outer phase decreased the size of particles, but increased the entrapment efficiency. Microparticles should have smaller size than $10\;{\mu}m$ to be uptaked by Peyer's patch in small intestine. High speed of mixing and relatively small volume of outer phase are needed to reduce the size. In addition, appropriate amount of isopropyl alcohol in outer phase also plays an important role in size reduction of PLGA microspheres.

• 한국응용과학기술학회지
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• 제18권4호
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• pp.273-284
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• 2001

A series of microcapsule were synthesized by using several PCM(Phase Change Material) as a core material and gelatin/arabic gum, melamine/formaldehyde as a shell material. Coacervation technique and in situ polymerization were adopted in synthesizing microcapsules. In the microencapsulation by coacervation, tetradecane and octadecane were used as core materials. In the microencapsulation by situ polymerization tetradecane, pentadecane, hexadecane, heptadecane, octadecane, and nonadecane were used as core material. The synthesized microcapsule was examined to observe the shape of the microcapsule. The particle size analysis was performed by particle size analyzer. The thermal properties(e.g. melting point, heat of melting, crystallization temperature, heat of crystallization, differences between melting point and crystallization temperature) were obtained by DSC(Differential Scanning Calorimeter). The stirring rate effect was investigated during the microencapsulation. It was found that with increasing the stirring rate much smaller microcapule was produced. However, this did not necessarily lead to formation of spherical microcapsule.

• Corrosion Science and Technology
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• 제22권6호
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• pp.457-465
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• 2023

Irradiation-assisted stress corrosion cracking (IASCC) is one of the main degradation mechanisms of austenitic stainless steels, which are used as reactor internal materials. Slow strain rate testing (SSRT) has been widely applied to evaluate the IASCC initiation characteristics of proton-irradiated tensile specimens. Tensile specimens require low surface roughness for micro-crack observation, and electropolishing is the most important specimen pre-treatment process used for this. In this study, optimal electropolishing conditions were examined through analyzing results of polarization experiments and surface roughness measurements after electropolishing. Corrosion cell and electropolishing equipment were fabricated for polarization tests and electropolishing experiments using SSRT specimens. The experimental parameters were electropolishing time, current density, electrolyte temperature, and stirring speed. The optimal electropolishing conditions for SSRT tensile specimens made of type 316 stainless steel were evaluated as a polishing time of 180 seconds, a current density of 0.15 A/cm², an electrolyte temperature of 60 ℃, and a stirring speed of 200 RPM.

• 자원리싸이클링
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• 제31권4호
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• pp.34-39
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• 2022

본 연구에서는 약 3.5% 구리 함유 폐에칭액으로부터 구리를 회수하기 위한 철 샘플에 따른 시멘테이션 반응 시 초음파 에너지 인가에 의한 반응 속도와 구리 회수율에 미치는 영향을 조사하였다. 그 결과 단순 교반 공정에 비해 시멘테이션 반응이 효과적으로 일어나 같은 시간 대비 높은 구리 회수율을 나타냈다. 단순 교반과 초음파에너지를 가하였을 때를 비교해보면, 25분 반응에 따라 철 샘플 형태가 plate를 사용하였을 때, 약 9.5%가 56.6%로 향상되었으며, chip은 약 14.0%에서 46.1%, powder는 약 41.9%에서 77.2%로 증가하였다. 이는 시멘테이션 반응으로 생성되어 철 표면을 덮고 있던 구리가 탈착되며 연속반응이 유도되었고, 구리 회수율은 약 2배에서 6배까지 증가하였으며, 회수된 구리의 입자 크기 또한 감소하는 경향을 확인할 수 있었다.

• Journal of Biosystems Engineering
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• 제26권5호
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• pp.469-474
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• 2001

Milling the rice with low moisture requires more energy, produces more cracked rice, and results in reducing taste of cooked rice. Accordingly, it is necessary to add moisture to the rice with low moisture to obtain optimum moisture level for milling and taste of rice. This study was performed to evaluate the influence of initial moisture content and absorption rate on rice crack, milling energy and whiteness of milled rice and to obtain the information for design of rewetting system mounted on stirring device in grain bin. The tests were conducted for the four levels of initial moisture content in the range of 11.4 to 14.5%(w.b.) and six levels of absorption rate in the range of 0.04 to 1.0%, w.b./hr. In the case of lower moisture content below 12%(w.b.), crack ratios of brown rice were remarkably high regardless of initial moisture contents. Therefore, it was found that rough rice below 12%(w.b.) in initial moisture content could not rewetted by spraying water without crack generation of low level. Absorption rate must be below 0.3%, w.b./hr to maintain crack ratio increase of less than 1% regardless of initial moisture contents. In the case of allowable crack ratio increase of 2% and 5%, it was found that the maximum absorprion rate was respectively 0.6%, w.b./hr and 1.0%, w.b./hr in the initial moisture content of above 13.5%(w.b.). Rewetting the rough rice in moisture content of 11.4 to 14.5%(w.b.) to 14.3 to 16.9%(w.b.) decreased milling energy consumption by 15.9 to 22.3%. The effect of energy saving was higher in the samples of higher initial moisture content. Whiteness of milled rice was decreased by 0.5 to 1.5.