• Journal of the KSME
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• v.56 no.9
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• pp.38-43
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• 2016

초임계 난류유동이 활용되고 있는 가장 대표적인 시스템은 액체로켓연소기이다. 액체로켓엔진은 목적하는 임무에 따라 추력이 결정되고 엔진의 추력이 결정된다. 이러한 추력을 결정하는 핵심부품이 분사기(injector)이다. 실용 인공위성을 발사하기 위한 액체로켓엔진의 연소기는 수백 개의 분사기를 통해 연료와 산화제가 혼합되는 구조를 가지고 있다. 따라서 로켓연소기의 연소특성 및 성능은 분사기의 혼합특성에 좌우된다. 그러므로 단일 분사기의 연료/산화제 혼합특성에 대한 많은 실험과 해석연구가 진행되고 있다. 그런데 초임계압력에서는 액체의 표면장력이 사라지게 되어 독특한 혼합특성을 가지고 있기 때문에 성능을 높여주기 위하여 초임계 압력을 선택할 경우 분사기에 대한 연구가 선행되어야 한다. 이 글에서는 이러한 초임계 작동압력에서 분사기에 대한 연구들을 소개하고자 한다.

• Korean Journal of Weed Science
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• v.5 no.2
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• pp.187-193
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• 1985

The experiment was carried out to evaluated the interaction between perfluidone(2-methyl-4-phenylsulphonyltrifluoromethylsulphoanilide) and bifenox(2,4-dichlorophenyl-3-methoxycarbonyl-4-nitrophenylether). A synergistic effect was found between perfluidone and bifenox. The highest synergistic effect on Echinochloa crus-galli (L.). Beauv. was obtained when 10 g a.i./10a of perfluidone was combined with 24.9 g a.i./10a of bifenox. However, bifenox should be increased to 33.3, g a.i./10a to obtain the highest synergistic effect when applied to Cyperus serotinus Rottb. at 1.0-1.5 leaf stage. Sagittaria pygmaea Miq. at 0.5-1.0sleaf stage was completely controlled by the lowest combination rate employed.

• Journal of the Korean Chemical Society
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• v.53 no.5
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• pp.491-498
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• 2009

The critical micelle concentration (CMC) and the counter ion binding constant (B) for the mixed micellizations of DBS (sodium dodecylbenzenesulfonate) with Brij 30 (polyoxyethylene(4) lauryl ether) and Brij 35 (polyoxyethylene (23) lauryl ehter) at 25 ${^{\circ}C}$ in pure water and in aqueous solutions of n-butanol were determined as a function of $\alpha$1 (the overall mole fraction of DBS) by the use of electric conductivity method. Various thermodynamic parameters (Xi, $\gamma$i, Ci, aiM, $\beta$, and ${\Delta}H_{mix}$) were calculated and compared for each mixed surfactant system by means of the equations derived from the nonideal mixed micellar model. There sults show that the molecules of DBS interact more strongly with Brij 35 than Brij 30 and that the DBS/Brij35 mixed system has greater negative deviation from the ideal mixed micellar model than the DBS/Brij 30mixed system.

• Korean Journal of Clinical Pharmacy
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• v.23 no.1
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• pp.14-19
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• 2013

Background :긴 측쇄의 트리글리세라이드(long chain triglyceride, LCT)는 대두 또는 홍화씨로부터 제조된 지방유제의 주요 성분이다. 중 측쇄 트리글리세라이드(medium chain triglyceride, MCT)는 LCT와 다른 물리적 성질을 가지고 있다. MCT의 지방산은 LCT의 지방산 보다 작은 분자량을 가지기 때문에 물에 더 잘 녹으며 다른 경로를 통하여 더 빨리 대사된다. Objectives & Methods :본 연구에서는 지방산의 길이에 따른 고영양수액제(total nutrient admixture, TNA)의 안정성을 비교하기 위하여 서로 다른 LCT와 MCT 조성을 가지는 4 가지 TNA 처방의 안정성을 실온 및 냉장 조건에서 측정하였다. Results :그 결과 MCT와 LCT의 혼합 조성의 TNA는 LCT 단독 조성의 TNA 와 유사한 안정성을 나타내었다. MCT와 LCT 혼합 TNA는 LCT 단독 TNA에 비하여 작은 입자크기를 보였지만 외관, 산도, 과산화수소가, 삼투농도, 아연 농도, 니코틴아미드 및 리보플라빈 농도에서는 의미 있는 차이를 보이지 않았다. Conclusion : 따라서 MCT와 LCT의 혼합 TNA는 LCT 단독 조성 TNA에 상응하는 안정성을 가지고 LCT단독 TNA을 대체제로 사용할 수 있다. 결론적으로, TNA의 2가지 타입 모두 3일 동안 실온과 냉장에서 안정하고, MCT와 LCT의 혼합 TNA는 LCT 단독 조성 TNA보다 생리화학적으로 더 안정하므로 환자들에게 좀 더 효과적인 에너지원이 될 것으로 전망된다.

• Korean Journal of Weed Science
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• v.2 no.1
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• pp.20-30
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• 1982

A field experiment was conducted in 1981 at the Crop Experiment Station, Suweon, Korea, in machine transplanted paddy rice field, to study the effectiveness of single herbicide, mixture, and systematic application of herbicides on diversity of weed control spectrum. The rice variety planted was Taebaegbyeo, Indica ${\times}$ Japonica cross bred. Experimental field was dominated by Echinochtoa crusgalli, Eleocharis kuroguwai, and Scirpus hotarui, and importance values based on dry weight of these weeds were 89%, 5%, and 3%, respectively. The mixture or systematic treatments of herbicide were generally more effective than single herbicide applications on weed control. Coefficients of similarity based on floristic composition after herbicide application between Perfluidone (5G) and Chloromethoxynil (7G), and between Pertluidone (5G) and Bifenox (7G), and between Perfluidone (5G) and three types of Butachlor (6G) were low, and these sets seemed to be a good mixture herbicide in paddy fields. While, Perfluidone (5G) had low coefficient of similarity with other single herbicides tested. The information on coefficient of similarity could be used as parameter for selecting herbicides to increase the efficiency of herbicidal performance. Simpson's indices from Butachlor (3.5G)/SL-49 (7G), Butachlor (3.5G)/Pyrazolate (6G), and Perfluidone (5G) treatments were high, and these herbicide treatments tended to the weed community type simplified, while the indices from Perfluidone (5G) + Chloromethoxynil (7G), Butachlor (6G) fb Perftuidone (5G), and Butachlor (4G)/Naproanilide (6G) treatments were low, and these herbicide treatments caused to the community type diversified in terms of floristic composition.

• Journal of the Korean Chemical Society
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• v.56 no.5
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• pp.556-562
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• 2012

The critical micelle concentration (CMC) and the counter-ion binding constant (B) for the mixed micellizations of TTAB (tetradecyltrimethylammonium bromide) with other surfactants (DTAB, CTAB, Tween-20, Tween-40, and Tween-80) in aqueous solution of 4-chlorobenzoic acid (0.5 mM) at $25^{\circ}C$ were determined as a function of ${\alpha}_1$ (the overall mole fraction of TTAB) by using the spectrophotometric method and the conductivity method. Various thermodynamic parameters ($X_i$, ${\gamma}_i$, $C_i$, $a_i^M$, ${\beta}$, and ${\Delta}H_{mix}$) were calculated for each mixed surfactant system and compared with the other mixed surfactant systems by means of the equations derived from the nonideal mixed micellar model. The results show that TTAB/DTAB mixed system has a great positive deviation from the ideal mixed micellar model and the other mixed systems have great negative deviations from the ideal mixed model.

• Journal of the Korean Magnetics Society
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• v.5 no.6
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• pp.928-936
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• 1995

In this research, the processing control of NiCuZn Ferrite has been developed. The mixing and the size reduction of raw materials have been proceeded. In order to produce NiCuZn Ferrite, highly concentrated slurry with fixed ratio and wet ball milling were used. First, the dispersion behavior of raw mixture at the region of pH4~pH11 has been studied. Using wet ball milling operation, the best conditions of mixing and size reduction have been determined. Further more, the most suitable conditions, such as, dispersant kind, dispersant amount, milling time, and slurry concentration have been studied. The poly acrylic ammonium salt (PAN) was chosen as a suitable dispersant to have effective dispersion in basic region. The slurry of raw mixture without dispersant, showed high viscosity and poor grindability. As 0.7 wt% of PAN was added, the concentrated slurry (up to 55 vol%) was possible, and showed well grindability. After 18 h ball milling of 30 vol% of mixture slurry with 0.7 wt% of PAN, the average particle size and specific surface area of raw mixture were $0.54\mu\textrm{m}$ and $12.92m^{2}/cc$, respectively. The ball milled raw mixture, calcined at $700^{\circ}C$ for 3h, was totally changed into NiCuZn Ferrite with spinel phase.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.3
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• pp.1-8
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• 1999

Mixing efficiency of the unlike Impinging split triplet injector(FOOF type) were measured to investigate the effect of the momentum ratio variation. $H_2$O/kerosene were used as a propellant simulant. The maximum mixing efficiency occured at the momentum ratio 1.5 (total mixture ratio 1.89). Calculated mixing efficiency of real propellant LOX/Kerosene showed similar trend but maximum efficiency of characteristic velocity occurs at the momentum ratio 2.0(total mixture ratio 2.17). Although there exist a little discrepancy between calculated mixing efficiency based on simulant cold test and hot fire test results, this calculated mixing efficiency can be used to predict hot fire mixing efficiency.

• Journal of Life Science
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• v.28 no.4
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• pp.472-477
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• 2018

Pravastatin sodium is a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor used in the treatment of hypercholesterolemia by reducing cholesterol biosynthesis. Pharmaceutical excipients of commonly used including water, diluents, stabilizers, disintegrants, lubricants and colorants, and were identified for compatibility. All tests were performed by means of physical mixture of pravastatin and the excipients, which were placed in a press-through-pack (PTP) and incubated under accelerated conditions ($40^{\circ}C$ and 75% relative humidity) for 3 months. The blends of pravastatin with all excipients developed white, off white, and light brown powders, which showed no changes upon visual analysis. Accelerated conditions changed the degradation profile of pravastatin calcium in the HPLC system when mixed with different excipients. Although most excipients can have minor effects on pravastatin stability, the major degradation product from pravastatin was lactone. Low-level interaction (assay and impurity) was induced by all excipients except for microcrystalline cellulose and croscarmellose sodium. These excipients increased lactone impurity in 3 months by as much as 0.22% and 0.18% respectively. The total mixture slightly increased the lactone impurity (by 0.43% in 3 months) of pravastatin. There was no change in the assays of all excipients. These results will be helpful in studying tablet size reductions for convenience of use.

• Agrochemical news magazine
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• v.25 no.5 s.198
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• pp.10-11
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• 2004