• 멤브레인
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• 제32권2호
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• pp.91-99
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• 2022

모든 인구 계층에 저렴한 비용으로 깨끗한 물의 수요를 충족시키는 것은 해결해야 할 세계적인 문제이다. 막 분리 공정을 통한 해수 및 기수의 탈염은 효율이 높고 확립된 방법이다. 그러나 막 분리 공정은 막 오염, 제거된 오염물의 처리, 그리고 자본집약적 공정이라는 본질적인 문제가 있다. 전기투석은 전위차가 구동력인 막 기반 분리 공정이다. 전기투석막의 장점은 뛰어난 효율과 저렴한 운영 비용이다. 전기투석공정에서 사용되는 이온교환막은 장기간 효율을 잃지 않기 위해 내화학성과 내열성, 그리고 기계적 안정성이 필요하다. 이 때, 전기투석막의 이온교환용량은 이온교환막의 전도도에 따라 크게 달라진다. 본 리뷰에서는 이온 전도도과 안정성을 향상시키기 위한 양이온 교환막과 음이온 교환막의 개조를 중점적으로 논의하였다.

• 한국식생활문화학회지
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• 제23권1호
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• pp.26-32
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• 2008

: In this experiment, three samples of oils were used. These oils were hydrated soybean oil, pure soybean oil and regular soybean oil. Oil was used after heating at $235-240^{\circ}C$ every four hours term and total heating hours was 16 hours. The physio-chemical analysis and sensory evaluation were performed on these oils. The hydrated soybean oil showed lower acid, peroxide and carbonyl value than the other two oils (p<0.05 or p<0.001). The other two oils were more affected in rancidity than the hydrated soybean oil. In color test, whereas L value lowed during the heating time, a and b value increased during the heating time. The tendency of high L value and low b value in a long-time heating was more apparant on the pure soybean oil and the regular soybean oil than on the hydrated soybean oil (p<0.05). In sensory evaluation, color and rancidity order increased during the heating time. The hydrated soybean oil showed color and rancidity order than the other two oils. In overall quality test, the pure and regular soybean oil that had been used for 12 and 16 hour were not preferable. The hydrated soybean oil that had been used for 16 hour were not preferable. In sensory evaluation, the hydrated soybean oil, the pure and regular soybean oil did not show a apparent difference, although the hydrated soybean oil had a little better scores on the overall quality.

• Asian-Australasian Journal of Animal Sciences
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• 제26권2호
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• pp.282-286
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• 2013

Many manufacturing processes damage the structure of meat products and this often contributes to lipid oxidation which could influence warmed-over flavor (WOF) in precooked beef that is reheated beef. Electrical stimulation causes contraction of muscles and improves tissue tenderization. The purpose of this study was to evaluate the rate of lipid oxidation or warmed-over flavor that could be affected by electrical stimulation of precooked roast beef after refrigerated storage and reheating. The results show that there was no significant difference between chemical compositions and cooking yields when comparing non-electrically stimulated and electrically stimulated roast beef. Moreover, electrical stimulation had no significant effect on oxidative stability and off-flavor problems of precooked roast beef as evaluated by thiobarbituric acid reactive substances (TBARS) and sensory test (warmed-over aroma and warmed-over flavor). However, there was an increased undesirable WOF and a decrease in tenderness for both ES and Non-ES treatments over refrigerated storage time. Electrical stimulation did cause reactions of amino acids or other compounds to decrease the desirable beef flavor in re-cooked meat.

• 한국식품조리과학회지
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• 제14권1호
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• pp.97-105
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• 1998

This study was carried out in order to standardize the processing method of spiced soy sauce, to get the sensory scores for organoleptic properties in different cooking of each food items, and to analyze the microbiological and chemical properties during storage periods. In determining the optimum conditions for standardizing of spiced soy sauce, the best sensory score was found in the ratio of soy sauce to sugar of 1:0.7. In the result of microbial experiment on standardized spiced soy sauce, the stability of storage at 40$^{\circ}C$ up to 6 weeks was proved. The standardized spiced soy sauce which was composed of about 45.5% water, 6% crude protein, 11.7% reducing sugar and 32.1% invert sugar has not shown any significant difference during storage for 6 weeks at 40$^{\circ}C$ compared with the state immediately after processing. In the test of saltiness, specific gravity, viscosity and Hunter's color value, there was no notable change during storage at 40$^{\circ}C$. In the experiment of free amino acid and total amino acid, main amino acids were glutamic acid and aspartic acid, which were not significantly changed during storage compared with processing state. In the analysis of mineral contents, sodium accounts for 95% of the total minerals, followed by phosphorus, magnesium, etc., in order, and there was no change during storage.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.133-133
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• 2013

For both oxygen reduction (ORR) and hydrogen oxidation reactions (HOR) of proton electrolyte membrane fuel cells (PEMFCs), alloying Pt with another transition metal usually results in a higher activity relative to pure Pt, mainly due to electronic modification of Pt and bifunctional behaviour of alloy surface for ORR and HOR, respectively. However, activity and stability are closely related to the preparation of alloy nanoparticles. Preparation conditions of alloy nanoparticles have strong influence on surface composition, oxidation state, nanoparticle size, shape, and contamination, which result from a large difference in redox priority of metal precursors, intrinsic properties of metals, increasedreactivity of nanocrystallites, and interactions with constituents for the synthesis such as solvent, stabilizer, and reducing agent, etc. Carbon-supported Pt-Ni alloy nanoparticles were prepared by the borohydride reduction method in anhydrous solvent. Pt-Ru alloy nanoparticles supported on carbon black were also prepared by the similar synthetic method to that of Pt-Ni. Since electrocatalytic reactions are strongly dependent on the surface structure of metal catalysts, the atom-leveled design of the surface structure plays a significant role in a high catalytic activity and the utilization of electrocatalysts. Therefore, surface-modified electrocatalysts have attracted much attention due to their unique structure and new electronic and electrocatalytic properties. The carbon-supported Au and Pd nanoparticles were adapted as the substrate and the successive reduction process was used for depositing Pt and PtM (M=Ru, Pd, and Rh) bimetallic elements on the surface of Au and Pd nanoparticles. Distinct features of the overlayers for electrocatalytic activities including methanol oxidation, formic acid oxidation, and oxygen reduction were investigated.

• Fibers and Polymers
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• 제1권1호
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• pp.12-17
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• 2000

Thermotropic polyurethanes were synthesized from 1,6-hexane diisocyanate (HDI) as a diisocyanate, 1,6-hexane diol (HD), and rigid diols containing imide unit such as N,N＇-bis(4-hydroxyphenyl)-3,4,3＇,4＇-biphenyl-dicarboxyimide (BPDI) or bis-N-(4-hydroxyphenyl)-4,4＇-oxydiphthalimide (ODPI). The effects of structure difference between BPDI and ODPI and composition of HD/BPDl (ODPI) on the thermal and liquid crystalline behavior were studied. Thermotropic polyurethanes with an inherent viscosity of 0.59~0.70 were obtained. The melting temperature of BPDI-based polyurethanes were in the range of 150~$290^{\circ}C$, however, those of ODPI-based polyurethanes were in the range of 150~$190^{\circ}C$. All the polyurethanes based on ODPI (25~100 mole %) clearly exhibited a stable liquid crystalline phase, and BPDI-based polyurethane having 5-25% of BPDT showed a mesophase. The melting and isotropization temperatures ($T_m$, $T_i$) and ΔT($T_i$ - $T_m$) increased with increasing BPDI and ODPI content. The polyurethanes based on BPDI has higher melting points and thermal stability compared to ODPI-based polyurethanes.

• 한국염색가공학회지
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• 제30권3호
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• pp.180-189
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• 2018

To study the effect of stereoisomeric structures of curing agents on curing behaviors, thermal and mechanical properties of epoxy resins, DGEBA(diglycidyl ether of bisphenol A) epoxy resin and 3,3'- and 4,4'-DDS(diaminodiphenyl sulfone) curing agents were selected. The curing initiation temperature and activation energy of DGEBA/3,3'-DDS was lower than DGEBA/4,4'-DDS. DGEBA/3,3'-DDS has a faster curing rate and higher degree of cure than DGEBA/4,4'-DDS, suggesting that 3,3'-DDS has higher reactivity than 4,4'-DDS. Tensile strength and fracture toughness of DGEBA/3,3'-DDS was lower than those of DGEBA/4,4'-DDS, indicating that mechanical properties of the epoxy resin can be different only by the stereoisomeric difference in chemical structure of the curing agent.

• Journal of Advanced Marine Engineering and Technology
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• 제31권4호
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• pp.401-409
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• 2007

Because of the various excellent characteristics of cast basalt materials. such as, anti-corrosion, anti-wearing, good hardness. high chemical stability, of which steel may not possess, the steel-basalt composite pipes are used in severe environments for compensating the defects of steel. However. without sufficient mechanical investigation prior to application. the basalt liners in steel-basalt composite pipes may be cracked and broken or the basalt liners are omitted from steel pipes in applications. In these cases, the merits of basalt materials may disappear and the basalt liners may not play their good roles as expected. Therefore, it is required that mechanical behavior of steel-basalt composite pipes and surrounding environments be fully examined before installation. The limit of bending moment with which steel-basalt composite pipe may safely endure is calculated and the limit curvature of the composite pipe in the safe range is presented in this paper. The temperature distributions and the thermal stresses are also computed and the limit difference of temperatures between inner and outer side of composite pipe is given together.

• 환경생물
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• 제39권1호
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• pp.88-99
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• 2021

본 연구에서는 해양생태계 위해성 평가 시 생물학적, 비생물학적 요인에 대한 인공생태계 실험의 초기 안정성을 객관적으로 평가하기 위해 육상 기반 해양 폐쇄형 메조코즘(LMCM) 실험을 수행하였다. 변동계수(CV)의 진폭 변화는 실험의 안정성 분석 자료로 사용하였다. 본 연구에서 LMCM 그룹(200, 400, 600, 1,000 L) 내 비생물학적 실험변수에 대한 CV 값은 20~30% 범위로 유지되었다. 그러나 엽록소-a, 식물플랑크톤 및 동물플랑크톤과 같은 생물학적 요인의 CV 진폭 파이는 600L와 1,000L LMCM 그룹에서 높게 분석되었다. 이와 같은 결과는 실험 초기에 생물학적 변수에 대한 제어가 부족하여 발생한 것으로 해석된다. 또한 ANOVA 분석에 따르면, LMCM 그룹 간 CV 값은 생물학적 요인과 연관된 실험변수들에서 유의한 차이를 보였다(p<0.05). 본 연구에서 생물학적 변수의 안정화는 LMCM 그룹의 크기와 그룹 내 생물의 생태-생리학적 활동의 복잡성을 감안할 때 수질 및 영양염 성분을 제외하면 실험 초기 생물학적 변수의 변동성을 제어하고 유지할 필요가 있으나 현실적으로 어려운 부분이 많았다. 결론적으로 해양에서 과학적 도구로써 인공생태계 실험은 생물학적, 비생물학적 요인을 구분하여 명확한 측정요소(endpoint)를 비교 분석할 수 있는 연구목적 수립, 실험조건의 안정성 유지 및 실험결과를 객관적으로 해석할 수 있는 표준화된 분석 기법의 도입이 필요한 것으로 판단된다.

• 대한토목학회논문집
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• 제32권6D호
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• pp.599-605
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• 2012

교통개방시점의 예측은 공사 계획을 위해 중요하며 이를 위해 에폭시 아스팔트 혼합물의 양생에 따른 강도를 예측하는 것이 필요하다. 본 연구에서는 에폭시 아스팔트 혼합물의 양생온도와 시간에 따른 마샬안정도를 측정하고 이를 이용해 강도 발현식을 구하였으며, 변화하는 온도와 강도에 따른 반응속도를 반영할 수 있도록 화학적 반응속도론을 이용하여 에폭시 아스팔트 강도 예측모델을 개발하였다. 예측모델을 사용하여 에폭시 아스팔트 포장이 적용된 국내 교량에 대해 교통개방시기를 예측하였다. 2009년~2011년의 기상조건에 따라 가정된 포장체 온도를 사용한 예측결과는 실제 교통개방일과 17일의 차이가 발생했으나 이는 2012년의 실제 기상상태와의 차이 때문이다. 실제 측정된 포장 온도를 예측모델에 대입할 경우 2일의 교통개방가능일 차이가 있었으며, 상관관계 분석 결과 R2가 0.95로 실제 강도값과 매우 유사한 결과를 얻을 수 있었다. 기상상태와 포장체의 온도에 대한 충분한 데이터를 확보한다면 에폭시 아스팔트 강도 예측모델을 사용하여 상당히 신뢰도 있는 교통개방 가능 시기의 예측이 가능한 것으로 나타났다.