• 한국재난정보학회 논문집
• /
• 제13권3호
• /
• pp.332-339
• /
• 2017

노후화된 구조물의 경우 준공 후 시간이 지나 구조물의 정보가 유실되는 경우가 많으며, 시공관련 자료에 대한 정보 부족으로 인해 구조물의 잔존수명을 예측하는데 큰 어려움이 있다. 본 연구에서는 현장에서 채취한 코어 시험체를 기반으로 각종 현장 및 실내시험법을 통한 내구성을 평가하고 이를 토대로 FEM 해석기법을 활용하여 콘크리트 구조물의 내구수명을 예측하였다. 그 결과, 중성화 속도계수는 $5.38E-6(cm^2/day)$로 매우 진행 속도가 낮은 것으로 나타났으며, 탄산화 및 염해에 의한 복합열화의 발생 가능성은 매우 낮은 것으로 확인되었다

• Applied Biological Chemistry
• /
• 제35권5호
• /
• pp.399-403
• /
• 1992

무의 염절임 과정에서 일어나는 염의 침투와 관련하여 무의 응력완화 변화를 측정하고 점탄성의 변화를 제시하였다. 침지 염용액의 농도와 침지온도가 증가할수록 염의 확산은 더 잘 일어났으나 염용액의 온도에 따른 염의 침투 정도는 낮은 염용액의 농도에 의해서 더 많은 영향을 미쳤다. 염장하지 않은 무의 높은 조직의 강도와 점탄성은 염용액의 온도를 증가시킴에 따라 초기 응력에 대한 조직의 강도약화를 보여 주었으며 응력완화의 정도도 빨라졌고 평형상태에서 잔여응력 양도 감소하였다. 또한 염용액의 농도가 증가할수록 무 조직의 응력완화정도와 잔존응력양의 변화가 거의 일치함을 보였다. 염용액의 온도와 농도를 증가시킴에 따라 염절인 무조직의 점탄성 성분들도 낮아졌는데, 온도에 따른 무의 점탄성의 낮아지는 정도는 염침투나 초기응력과 마찬가지로 낮은 염용액의 농도에서 더 많은 영향을 받았다.

• 멤브레인
• /
• 제25권5호
• /
• pp.391-397
• /
• 2015

다공성 지지체인 Polyvinylidene fluoride (PVDF) 중공사막에 염석법을 기반으로 하여 Polyethyleneimine (PEI)와 Polyvinylsulfonic acid (PVSA)를 가압법(phase separated and pressurization, PSP)으로 코팅시켜 다층막을 제조하였다. 이에 열처리 온도, 코팅농도, 유입수 농도, 가교시간 및 가교제 농도에 대하여 NaCl 100 ppm을 공급액으로 하여 4 atm에서 투과도와 제거율을 알아보고자 하였다. 가장 좋은 결과로는 PEI 20,000 ppm과 PVSA 1,000 ppm, PEI 15%에 말산 2% 수용액으로 가압코팅 후 열처리하였을 때 투과도 24.3 LMH, 제거율 82.1%의 결과를 얻을 수 있었다.

• 한국식품영양과학회지
• /
• 제27권5호
• /
• pp.808-812
• /
• 1998

Melania snail(Semisulcopira bensoni) is used as ingredient in Korean traditional soup and nutritional foods. Generally, lipoxygenase in several food products may produce off-flavors during their processing and storage. Therefore, the inactivation of lipoxygenase is required to make the better extracts from Melania sanil. Also, the quality on freshness of Melania snail may be evaluated by lipoxygenase activity. The lipoxygenae activity was the highest at 40~60% saturation among several concentrations in salting-ouot saturated solution of ammonium sulfate. The partial purification of lipoxygenase was successfully obtained by Sephacryl S-200 gel chromatography. The first peak among three peaks for protein determination showed the highest activity of lipoxygenase in 13~16 fractions among 100 fractions. The highest peak of lipoxygenase activity by ion exchange chromatography was shown at 0.1M NaCl. In the purification step, the specific activity was 20.8U/mg and activity yield was 19.8%. The optimum pH and temperature were pH6.0~8.0 and 3$0^{\circ}C$, respectively. Molecular weight of the lipoxygenase was estimated about 35kDa by SDS-PAGE.

• Membrane and Water Treatment
• /
• 제10권6호
• /
• pp.451-460
• /
• 2019

Thin film composite membranes incorporated with nano-sized hydrophilic zeolite -A were successfully prepared via interfacial polymerization (IP) on porous blend PES/PAN support for water desalination. The thin film nanocomposite membranes were characterized by SEM, contact angle and performance test with 7000 ppm NaCl solution at 7bar. The results showed that the optimum zeolite loading amount was determined to be 0.1wt% with permeate flux 29LMH.NaCl rejection was improved from 69% to 92% compared to the pristine polyamide membrane where the modified PA surface was more selective than that of the pristine PA. In addition, there was no significant change in the permeate flux of the thin film nanocomposite membrane compared with that of the pristine PA in spite of the formation of the dense polyamide layer. The stability of the polyamide layer was investigated for 15 days and the optimized membrane presented the highest durability and stability.

• 한국수산과학회지
• /
• 제54권6호
• /
• pp.841-848
• /
• 2021

To develop a value-added low-salt fermented seafood with a long shelf-life, we prepared seasoned low-salt fermented Omandungi Styela plicata supplemented with fermentation alcohol (SOE). The SOE was produced by washing and dewatering shelled Omandungi, followed by cutting and salting for 24 h at 0±1℃. The salted Omandungi was seasoned and fermented with garlic, ginger, monosodium glutamate, red pepper, sesame, sorbitol, and sugar, for 7-8 days at 0±1℃. After adding 3-5% fermentation alcohol, the seasoned fermented Omandungi was packed in a polyester container. The salinity, volatile basic nitrogen content, and viable cell count of SOE were 4.8%, 22.1-22.2 mg/100 g, and (1.2-1.9)×10³ CFU/g, respectively. Compared with the control, addition of 3-5% fermentation alcohol inhibited the decrease in freshness, texture degradation, and growth of residual bacteria. Additionally, the SOE showed good storage stability and organoleptic qualities when stored at 4±1℃ for 40 days. The total amino acid content of SOE was 2,186.0 mg/100 g, mainly comprising glutamic acid, aspartic acid, lysine, and phenylalanine. The free amino acid content was 189.0 mg/100 g, and mainly included taurine, glutamic acid, methionine, alanine, and proline.

• 분석과학
• /
• 제35권5호
• /
• pp.197-204
• /
• 2022

A gas chromatography-mass spectrometric method was developed for determining 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT), 2-methyl-4-isothiazolin-3-one (MIT), 1,2-benzisothiazolin-3-one (BIT), 3-iodo-2-propynyl butyl carbamic acid (IPBC) and benzoic acid (BA) in household products. A 0.5 g sample was placed in a test tube and dissolved with 5 mL water, 5 mL methylene chloride and 1.0 mL methanol. The solution was extracted by ultra-sonication followed by mechanical shaking using the salting out effect. Under the established condition, the lowest quantification limits of all analytes were in the range of 0.04-10 mg/kg and their relative standard deviations were less than 8.0 %. The method was used to analyze 10 household products. As a result of analyzing 10 household products, MIT was detected in the range of 1.2-3.5 mg/kg in 3 of 10 samples, CMIT was detected in the range of 2.6-8.2 mg/kg in 3 of 10 samples, and BA was detected in the range of 5.0-15 mg/kg in 4 of 10 samples. Meanwhile, BIT and IPBC were not detected in any of the products. It has been shown that this method can be used for the simultaneous determination of biocides with various physical and chemical properties in household products.

• 분석과학
• /
• 제20권1호
• /
• pp.70-77
• /
• 2007

클로로페놀 12종을 폐수로부터 LPME법을 사용하여 추출하였고, GC/MS로 분석하였다. 최적의 추출조건을 확립하기 위해 추출용매의 종류, 시료의 양, pH, 염석 효과, 플런저 왕복 횟수 및 속도를 고려하여 최적의 조건을 확립하였다. 그 결과, 직선성이 0.9913에서 0.9999를 가지는 12가지의 검정곡선을 얻을 수 있었고, 검출한계와 정량한계도 2,3,4,5-테트라클로로페놀과 펜타클로로페놀(0.05-500 ng/mL)을 제외하고 0.05~10.0 ng/mL범위에서 얻을 수 있었다. 실제 폐수에서 4-클로로-3-메틸페놀(784 ng/mL)을 확인할 수 있었다.

• 한국응용과학기술학회지
• /
• 제34권2호
• /
• pp.289-295
• /
• 2017

현 국제해사기구(IMO)에서의 선박엔진에서 발생되는 NOx와 SOx 등의 연소 가스 배출에 대한 규제 강화에 따라, 발트 해 연안을 지나는 모든 선박들은 배출되는 연소가스 저감장치를 장착해야 된다. 국내에서도 IMO의 규제에 따른 NOx와 SOx를 저감장치를 개발하고 있으며, 그중에 대표적인 장치인 Scrubber는 세정액으로 암모니아수와 요소수를 사용하게 되고 사용된 폐 세정액에는 NOx와 SOx와 반응한 질산암모늄과 황산암모늄이 포함되어 있다. 본 연구에서는 폐 세정액이 포함하고 있는 유용한 부산물을 유기용매를 사용하는 염석법을 적용하여 회수하였다. 질산암모늄과 황산암모늄의 회수방법과 질안석회를 추출 후 회수된 부산물의 정성분석을 위하여, FT-IR 분석을 통하여 물질의 정성적 특성과 화학적 조성을 평가해 보았다. 한편 응집제를 투입하여 질안석회를 침전시켜 비료상의 물질로 회수하였다. $FeSO_4$ 응집제와 $CaCl_2$를 응집보조제로 사용하고 입자의 크기를 키우기 위해 $CaCO_3$를 사용하였다.

• Preventive Nutrition and Food Science
• /
• 제8권3호
• /
• pp.270-277
• /
• 2003

In order to enhance the firmness and shelf-life of kimchi, as well as to increase the content of well-absorbed digestible calcium, the effect of calcium lactate (CaL) treatment of salted Chinese cabbage on pH, tit ratable acidity, total microbes, lactic acid bacteria, alcohol insoluble substance (AIS) content, firmness, mineral content and tissue structure were investigated. Treatment with the Cal solution increased pH and decreased titratable acidity, which was more pronounced at higher concentrations. The edible period evaluated by pH was 7～8 days for non-treated kimchi, 10 days for 1 % treated kimchi, 15 days for 2% treated kimchi and 20 days for 3% treated kimchi. Total microbes were reduced, but lactic acid bacteria counts were higher in the treated group. CaL treated kimchi showed higher AIS content and firmer texture, which was more conspicuous in the 2 and 3% CaL treated groups. Calcium content in kimchi fermented for 15 days was 40.75～41.53 mg%, which is 42～45% higher than that in the control group. The sodium content was 23～54% less in the treated groups. The epidermis and vascular bundle tissue of kimchi fermented for 15 day was damaged more severely in the control group than in the treated group. CaL treated kimchi has a crispier taste and the development of sour taste was delayed. Therefore, addition of CaL can produces a kimchi with high calcium as well as superior texture and shelf-life, when adjusting the concentration according to the fermentation periods.