• Journal of the Korean Chemical Society
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• v.27 no.3
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• pp.178-182
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• 1983

The conductances of sodium, potassium, ammonium, tetramethylammonium, and tetraethylammonium iodides, picrates(Pic) of sodium and potassium, and tetrabutylammonium tetraphenyl-boride have been measured in ethylene carbonate-acetone mixtures at $25{\circ}C$. The limiting equivalent conductances of the electolytes were computed by Fuoss-Kraus equation and the order was $(C_4H_9)_4NB(ph)_4 at any composition of the mixtures. The dissociation constants of the salts showed that the mixtures are good ionizing solvents for the salts. The order of limiting ionic equivalent conductance, $Na^+, is consistent with exactly the reverse order found for solvation number. Effective solvated radii calibrated by the Nightingale method showed that picrate ion seems to be unsolvated and that iodide ion seems to be solvated to some extent in the mixtures.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.2
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• pp.179-185
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• 2013

The behavior of surface film formation was greatly dependent on the speed of potential cycling. In $LiClO_4$ / EC + DEC, cyclic voltammetry results showed that the peaks originated from surface film formation on graphite electrode at the high charge-discharge rate was shifted to the lower potentials as the charge-discharge rate decrease. This indicates that surface films with different morphology and thickness were formed by different charge-discharge rate. Transmission electron microscopy (TEM) results indicated that the properties such as thickness and morphology of the surface film were greatly affected by the charge-discharge rate. Electrochemical impedance spectroscopy (EIS) showed that the resistance of surface film was affected by the speed of potential cycling. In addition, the charge transfer resistance was also dependent on the charge-discharge rate indicating that the charge transfer reaction was affected by the nature of surface film. TEM and EIS results suggested that the chemical property as well as the physical property of the surface film was affected by the charge-discharge rate.

• Food preservation and processing industry
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• v.3 no.1
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• pp.68-80
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• 2004

매실을 다양하게 이용하고 부가가치를 높이며 매실의 품질저하 방지 및 이용성 증대를 도모하기 위하여 실시된 지금까지의 매실의 가공, 저장 및 포장 방법에 대한 것을 조사하였다. 매실의 저온저장 시청매실은 $0\~1^{\circ}C$의 저온보다도 $5\~8^{\circ}C$에서 저온 장해가 발생하기가 쉽다고 보고되었다. 이러한 장해를 방지하기 위하여 수확직후에 $0^{\circ}C$정도의 냉수로 급속히 청매실의 품온을 저하시키면 $5\~8^{\circ}C$의 저장에서도 저온장해가 경감되고 추숙도 억제한다고 한다. 상온 CA저장 조건 하에서 청매실의 선도를 유지하기 하는데 대량으로 발생하는 에틸렌의 제거와 저산소($2\%$ 하한), 고이산화탄소($8\%$)의 가스조성이 효과적이라고 보고되었다. 청매실의 저장 중 선도유지를 위하여 청매실을 저밀도폴리에틸렌(LDPE 20${\mu}m$) 필름 봉투에 포장하여 에틸렌 제거제를 넣고 $20^{\circ}C$에 저장한 결과, 에틸렌생성량은 낮은 수준으로 유지되었고 연화에 의한 품질저하가 현저히 억제된는 것을 볼 수 있다. 그리고 MA포장(LDPE 30${\mu}m+$에틸렌제거제)에서도 청매실의 녹색유지 효과가 탁월하였고 이산화탄소 농도가 높을수록 황화가 억제된 것이 연구에 의하여 밝혀졌다. 포장재의 두께를 달리할 때 청매실의 선도유지 효과도 서로 다르게 나타난다고 보고되었다. 청매실을 두께가 다른 필름에 포장, $25^{\circ}C$에서 8일간 저장한 매실은 LDPE 20, 30 필름에 포장한 것이 저장 8일에도 녹색을 그대로 유지한 것을 보아 선도유지 효과가 있음을 알 수 있다. 그리고 중량감소은 LDPE 30, 40이 적게 나타났고 장해정도는 LDPE 20, 30 적게 나타났다. 청매실의 저장 중 선도유지가 가장 양호한 LDPE 30 포장재에 청매실과 함께 탄산가스흡수제, 에틸렌제거제를 각각 또는 혼합첨가하고 밀봉한 후 $25^{\circ}C$에서 10일간 저장한 매실은 에틸렌제거제 첨가한 것이 녹색유지효과와 선도유지효과가 좋았으며 매실의 장해발생도 가장 낮은 것으로 보고되었다. 매실을 이용하여 제조되는 가공식품으로는 매실주, 매실차, 매실 Fruit leather, 매실절임, 고추장장아찌, 매실식초, 매실잼, 매실김치 등이 있다. 앞으로 매실의 이용을 증진시키고 소비를 더욱 촉진시키기 위해서는 매실의 생리학적특성을 이해하여 더욱 효과적인 저장 및 포장방법을 개발하고 생리활성을 이용한 새로운 매실제품의 개발에 대한 연구가 뒤따라야 할 것이다.

• Resources Recycling
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• v.5 no.3
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• pp.56-64
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• 1996

C,H,OH system is widely used for producing synthetic beverages and pharmaceuticals. Calcium hydroxide suspension was used to callhol the morphology of calcium carbonate, and the charactenstics of the formahan and crystsllizatian of calcium cilrbonate by adding ethylenc glycol were determined A reaclor was made with attaching a ceramic bubble plate, and lhe eleclrical conductivity was continously monitored during the rcaction with CO, gas. A part of the suspension was separated and powdered at the transition point. XRD and electron microscopic observation showed that the intermedmte and final products were vilterite, ;~r;lganite and calcite. In this study, the volumc of the ethylene glycol added to CH,OH was fixed a1 10 vol\ulcornerh. The valumc of the suspension was 500 ml, and the changes oi characteristics were shdied along with variims cnntents(l0-50 g) of calcium hydroxide. Except m the case of 10 g of calcium hydroxide at the crystallization stagc, all of products showed gelation. Tne marc the calcium hydroxide the shorter the formation time. Alsa. the farmalion of spherical valcrile ivas obsemcd when 30 g Ca(OH), was added. Tne vaterite(a compound material) can bc synthesised under alnbienl pressure and lempcmhre m a C,H,OH system by morphology control. Even though the vateritc was meta-stable phasc and could bc changed to calcitc easily, the stable and spherical vateritc was observed by using G5 glass fillers and vacuum dricrs.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.635-640
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• 2005

Mediated electrochemical oxidation (MEO) is an aqueous process which oxidizes organics electrochemicallly at low temperatures and pressures. The useful process can be used to treat mixed wastes containing hazardous organics. This paper have studied MEO of ethylene glycol (EG) in nitric acids by Fe(III)/Fe(II) and Co(III)/Co(II) system. It investigated current density, supporting electrolyte concentration, hydraulic retention time, removal efficiency of EG by MEO. Removal efficiency of EG by MEO was superior in Co(III)/Co(II) redox system than Fe(III)/Fe(II) redox system, where MEO removal efficiency was 100 percent. In case of EG, the reactions were fast and good yields of carbon dioxide formation was observed.

• Journal of the Korean Chemical Society
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• v.23 no.4
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• pp.237-242
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• 1979

The equivalent conductances of sodium, potassium, ammonium, tetramethylammonium, triethylammonium, diethylammonium and ethylammonium iodide, and picrate salts of sodium and potassium in ethylene carbonate have been measured at 40.0 $^{\circ}C. The limiting equivalent conductances of the salts have been computed by Fuoss-Onsager-Skinner equation. The limiting ionic equivalent conductances of $Na^+,\;K^+,\;and\;NH^+$ are in order of $Na^+ which is the reverse order of solvation for the ions in any solution, And the order of limiting ionic equivalent conductances for alkylammonium ions is $(C_2H_5)_4N^+<(C_2H_5)_3NH^+<(CH_3)_4N^+<(C_2H_5)_2NH_2^+<(C_2H_5)NH_3^+$ which coincides with the order of mass transfer. From the dissociation constants of the saltss determinde by Fuoss-Kraus method, it is found that ethyene carbonate is a good ionizing solvent for the salts. In addition, Stokes radii and effective fadii of ions have been calculated by Stokes law and Nightingale method, repectively. From the results, it appears tha alkylammonium ions and picrate ion seem to be not solvated, and tha iodide ion is fairly solvated in ethylene carbonate.

• Polymer(Korea)
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• v.35 no.5
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• pp.458-466
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• 2011

In the mixed system of supercritical carbon dioxide/organic solvents, poly(vinyl alcohol)(PVA) film of high degree of hydrolysis could be dyed with a dichroic dye of C. I. direct black 22(DB22) and as a result, high durability was obtained. Especially, as a dye dispersant in a supercritical fluid phase, a mixed solvent system of ethylene glycol: dimethyl sulfoxide=4 : 6 weight ratio was investigated. Then the optimum pressure for dyeing could be reduced down to 200 bar. Using this supercritical fluid system, the maximum dyeing appeared as the transmittance of less than 1% and the waste amount was reduced to the level of 1/10. After 500% drawing of this PVA film, both the polarizing efficiency of 94% and the single piece transmittance of 30% were obtained. The limitation of DB22 and further improvements were also discussed.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.1036-1042
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• 2002

During storage at $25^{\circ}C$, the effect of gas absorbents, such as carbon dioxide scavenger, ethylene absorber, and their combinations, on respiration characteristics and quality attributes of mature-green Mume fruits packaged in $30\;{\mu}m$ low density polyethylene (LDPE) film was examined. Changes in quality attributes of the fruits were observed in terms of weight loss, titratable acidity, pH, fish firmness, color, water-soluble solid, and chlorophyll contents. In the presence of ethylene absorber $(KMnO_4)$, the physiological injury was remarkably suppressed, and there was no significant injury in Mume fruits at $25^{\circ}C$ for 10 days. Yellowing and softening were also noticeably reduced by the combination of plastic film packaging and inclusion of ethylene absorber. The respiration rate was slower in fruits sealed with ethylene absorber than in those with absorbent-free packaging. Using ethylene absorber, levels of oxygen and carbon dioxide were maintained at 2-3 and 7-8%, respectively, during storage at $25^{\circ}C$ for 10 days. The addition of carbon dioxide scavenger $(Ca(OH)_2)$, negatively affected the quality attributes and respiration characteristics of the fruits. Overall results showed that ethylene removal by gas absorbent in the film packages significantly prolonged the shelf life of the fruits at ambient temperature.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.140-145
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• 2017

This study was conducted to find out the effects of $CO_2$ fertilization (1,000ppm) on the quality and storability of 'Maehyang' strawberry fruits. Qualities such as firmness, soluble solid, and acidity of strawberry fruits showed higher numbers in those treated with $CO_2$ fertilization compared to those after harvest. Strawberry fruits were stored at $8^{\circ}C$; MA condition using $20,000cc{\cdot}m^{-2}{\cdot}day^{-1}{\cdot}atm^{-1}$ OTR (oxygen transmission rate) films and conventional condition using unsealed PE box stored for 20 and 10 days, respectively. Fresh weight loss rate was less than 1.0% in MA storage regardless of $CO_2$ fertilization treatment. Concentrations of oxygen, carbon dioxide, and ethylene in OTR films did not show any significant difference between $CO_2$ fertilization treatment and control (nontreatment) during storage. $CO_2$ fertilization treatments maintained higher firmness after storage regardless of storage methods, but soluble solid, acidity, and surface color did not differ among the treatments. Visual quality and off-flavor based on sensory evaluation was the highest in $CO_2$ fertilization treated strawberry and stored at a MA condition, and was the lowest in $CO_2$ fertilization treated strawberry and those stored in a conventional condition, respectively. The fungal incidence rate of strawberry fruits showed less in $CO_2$ fertilization treatment than control during both MA and conventional storage. These results suggest that $CO_2$ fertilization can improve firmness, increase visual quality after harvest and storage at $8^{\circ}C$, and the MA storage method enhances the shelf-life of 'Maehyang' strawberry fruits.

• Polymer(Korea)
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• v.29 no.1
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• pp.32-35
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• 2005

In this paper, the carbon nanotubes (CNTs) were ozonized and the positive temperature coefficient (PTC) behaviors of CNTs-filled high-density polyethylene (HDPE) conductive composites were studied. The results of element analysis (EA) and FT-IR indicate that the oxygen-containing functional groups on the CNTs surfaces, such as O-H, C-O, and C＝O groups, were increased with the ozonization. Electrical resistivities of the CNTs/HDPE composites were measured by using a digital multimeter. The resistivity of the composites was increased abruptly near the crystalline melting temperature of the HDPE used as matrix, which could be attributed to the destruction of conductive network by the thermal expansion of HDPE. And, the PTC intensity of the CNTs/HDPE composites was increased with the increase of the ozone treatment time. It was probably due to the growing of maximum volume resistivity of the composites induced by the increased oxygen-containing functional groups in the CNTs surfaces.