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        검색결과 22

        2.
        2022.10 구독 인증기관·개인회원 무료
        Niobium (Nb) is present in Ni-based alloys and stainless steels used in nuclear reactors as structural materials. Nb-93 is a naturally occurring and stable isotope of niobium and Nb-94 (half-life = 20,000 years) is produced by neutron activation of Nb-93. Nb-94 can be present in waste streams from dismantling of nuclear power plants and treatment of the primary coolant circuit. Hence, the radioactive wastes containing active Nb-94 are disposed of in the repositories for low- and intermediate-level waste (LILW). Nb predominantly exhibits a pentavalent oxidation state (i.e., +V) within the stability field of water. Cementitious materials (concrete, mortar, and grout) are extensively utilized in LILW disposal systems as structural components and chemical agents for the stabilization of waste. Solubility defines the source term (i.e., upper concentration limit) in the repository system. However, the solubility behavior of Nb in cementitious systems at high pH remains ill-defined, and information available on the Nb solid phases controlling the solubility is scarce and often ambiguous. Sorption on cementbased materials is one of the main mechanisms controlling the retention of niobium(V) in a LILW repository, and distribution coefficients (Rd) are necessary to evaluate the retention capacity by sorption in the safety assessment of disposal systems. Available sorption data of Nb(V) on cement showed a large discrepancy in Rd, moreover, no sorption data is available for Nb(V) under conditions characterizing the first degradation stage of cement (young cement condition) at pH 13 – 13.5. In this context, the solubility of Nb was extensively investigated in porewater conditions representative of the cement degradation stage I, as well as in CaCl2-Ca(OH)2 systems. Special focus was given to the accurate characterization of the solubility-controlling solid niobium phases. We also studied the sorption of Nb(V) by hardened cement pastes (HCP) and calcium silicate hydrates (CSH, major hydrate of HCP). This work provides the results on Rd, sorption isotherm and sorption mechanisms of Nb(V). Besides, the impact of ISA (polyhydroxycarboxylic acid generated by the degradation of cellulose) on Nb(V) sorption and the dissolution of cement materials was investigated.
        4.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Chungyuk-jang is one of korean traditional soy food made by boiling with meat, seafood and soybean which is fermented after roasting. To investigate the difference in the physicochemical characteristics of the Chungyuk-jang fermented with roasted soybean in different conditions, Chungyuk-jang was made from soybean roasted on the three condition, 140oC for 21 min (CY140), 180oC 9.5 min (CY180), 220oC 6 min (CY220) which was decided by pre-test and compared to one made without roasting (CY0). The moisture of Chungyuk-jang was 79.98~81.87% and pH was 6.15~6.25. The lightness and yellowness of CY0 was higher than Chungyuk-jang made of roasted bean whereas redness and brown pigment was the highest on CY220. The contents of free sugar of CY140 was the highest among the treatment. The contents of amino-N of Chungyuk-jang (CY140, CY190, CY220) was higher significantly than CY0. The contents of total free amino acid and glutamic acid was highest on fermented soybean roasted for 140oC, 21 min (CY140) and followed by fermented soybean roasted on 180oC 9.5 min (CY180), 220oC 6 min (CY220) and CY0 (without roasting).
        4,000원
        5.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was investigated the difference in the quality characteristics of the fermented soybean roasted with different conditions for making chungyukjang. Roasted condition of soybean was decided by pre-test, which was on 140oC for 21 min, 180oC 9.5 min, and 220oC 6 min. Fermented soybean with different roasted condition and conventionally made cheonggukjang were measured for proximate composition, color, pH, amino nitrogen, ammonia nitrogen, free sugar and amino acids. The lightness and yellowness of soybean fermented by conventional method was higher than those of the fermented soybean with roasted soybean. The contents of free sugar of fermented soybean roasted on 220oC for 6 min (FS220) was the highest among the group and followed by fermented soybean roasted on 180oC for 9.5 min (FS180), 140oC 21 min (FS140) and conventional cheonggukjang (FS0). The contents of total free amino acid was highest on fermented soybean roasted on 140oC for 21 min (FS140) and followed by fermented soybean roasted on 180oC for 9.5 min (FS180), 220oC 6 min (FS220) and conventional cheonggukjang (FS0).
        4,000원
        6.
        2016.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 홀스타인 거세육우(총 18두, 생후 4개월령, 체중 160kg)의 성장단계별 농산부산물 TMR 사 료의 에너지 수준(T1, TDN 75~84%; T2, TDN 77~85%)과 출하월령(18, 20 및 22개월)별로 배치하여 각 출하월령별 등심과 우둔육의 육질 및 관능특성을 조사하였다. 등심육의 경우 근내지방함량은 처리구 1은 22개월령 그룹이, 처리구 2는 20개월 및 22개월령 그룹이 유의적으로 가장 높았다(P<0.05). 우둔 육의 경우 처리구 1과 2가 모두 22개월령 그룹이 근내지방 함량이 가장 높았다(P<0.05). 처리구 2는 18개월령 그룹이 단백질 및 수분함량이 유의적으로 가장 높았다(P<0.05). 콜라겐 함량은 처리구 모두 출하월령간에 유의적인 차이가 없었다(P>0.05). 육질특성에서 등심육은 처리구 1의 경우 보수력, 전단 력, 가열감량, 육색에 있어서 급여기간 그룹간 유의적인 차이가 없었다(P>0.05). 처리구 2에서는 보수 력만 18개월과 20개월령 그룹이 가장 높았다(P>0.05). 우둔육은 처리구 1의 경우 보수력, 전단력, 가열 감량, 육색의 백색도에 있어서 급여기간 그룹간 유의적인 차이가 없었으며 단지 육색에서 적색도와 황 색도만 22개월령이 가장 높았다(P>0.05). 처리구 2의 경우 18개월령 그룹이 보수력이 가장 높았고 전 단력은 가장 낮았으며 가열감량은 18개월과 20개월령 그룹이 낮았다(P<0.05). 관능특성에 있어서 등심 육의 경우 처리구 1은 18개월과 20개월령이 연도점수가 높았고 20개월령 처리구가 향미 및 전반적인 기호도 점수가 유의적으로 높았다(P<0.05). 처리구 2는 연도, 다즙성, 향미 및 전반적인 기호도 점수 모두 20개월과 22개월령이 유의적으로 높았다(P<0.05). 우둔육의 경우 처리구 1은 연도가 18개월과 20 개월령이 유의적으로 높았고 전반적인 기호도는 20개월령이 유의적으로 높았다. 처리구 2는 18개월령 이 연도만 유의적으로 높았다(P<0.05). 결론적으로 홀스타인 거세육우는 농산부산물 TMR 사료를 22개 월령까지 급여한 그룹이 근내지방도는 높았으나 육질 및 관능특성은 18개월령 또는 20개월령이 더 우 수하였으므로 이러한 점을 고려하여 출하하는 것이 바람직할 것으로 생각된다.
        4,300원
        7.
        2015.11 구독 인증기관·개인회원 무료
        기존 정수처리 공정은 나날이 발현빈도 및 농도가 증가하고 있는 신규오염물질을 대처할 수 없는 실정이다. 이를 위하여 다양한 고도처리공정이 도입되고 있으며 이 중 막여과공정은 최근 설치비율이 급격하게 상승하고 있다. 본 연구에서는 망간이 발현되고 있는 U정수장을 대상으로 MF막을 설치한 파일롯 플랜트를 운영하여, 막여과공정에서의 화학세척조건에 따른 회복성능을 평가하고 이온분석을 실시하였다. 이는 망간발현지역을 대상으로 한 최적의 분리막 세척조건 도출을 위한 기초자료로 활용할 수 있다.
        8.
        2015.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study analyzes the chemical composition of green tea, white tea, yellow tea, oolong tea and black tea with respect to extraction temperature and time. The optimum extraction conditions for these teas were determined by assessing the chemical composition of tea brewed at different temperature (50, 60, 70, 80℃) and extraction times (1, 3, 5, 10 minute). Catechins contents were the largest at 5 minutes and generally declined by 10 minutes. Green tea catechins contents were highest when brewed at 70℃ and besides other teas a change of the trend variation at 70 and 80℃. These temperatures did not extract theaflavins in green tea. Extract temperature and time did not significantly affect theaflavins content of white tea, yellow tea, and oolong tea. Black tea, however, was noticeably dependent on extract conditions, which were most effective at 70℃, brewed for 5 minutes. Caffeine content of green tea, yellow tea, and oolong tea was highest at 5 minutes, but temperature did not appear to affect the content. White tea and black tea caffeine content was highest when brewed at 70℃ for 5 minutes. Theobromine content of green tea, yellow tea, oolong tea, and black tea did not show major differences between the study times or temperature, though the content in white tea increased with higher temperatures when brewed for 5 minutes. The extraction of phenolic compounds increased until 5 minutes, and showed not further increase at 10 minutes. Antioxidant capacity of green tea, white tea, and yellow tea were maximized at 70℃ for 5 minutes or 80℃ for 3 minutes, while oolong and black tea were reached maximum antioxidants at 70℃ for 5 minutes. In general, to optimize the beneficial chemical content of brewed tea, a water temperature of 70℃ for 5 minutes is recommended.
        4,000원
        9.
        2012.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 Y 정수장의 세라믹 정밀여과막 공정을 위한 최적의 약품세척 조건을 도출하고자 수행되었다. 세라믹 막 공정의 전처리로 오존과 응집공정이 있는 A계열의 경우 응집공정만 있는 B계열에 비해 9배 정도 잦은 약품세척(CIP)를 실시하였다. 이는 전처리 공정의 차이로 인하여 A와 B계열의 막오염현상이 다르게 나타난 근본적인 원인 이외에 막제조업체가 제시한 CIP 방법이 부적절한 것으로 조사되었다. 즉, CIP 회복률이 보정여과유속이 아니라 보정차압을 기준으로 계산되어 과대평가되었을 뿐만 아니라 구연산이 철산화물에 의한 파울링을 효과적으로 제거하지 못했기 때문이었다. 따라서 1단계 산세척 약품종류를 달리하여 CIP 효율을 평가한 결과 황산(0.1 N)과 구연산(1%)를 혼합하여 사용한 경우 회복률이 가장 높았고, 황산(0.1 N)만을 사용한 경우 회복률이 가장 낮은 것으로 나타났다. 그러나 황산의 농도를 0.3 N로 높인 결과 산세척 효율은 증가하였으나 알칼리세척 회복률이 낮아져 총회복률은 0.1 N 황산을 사용한 것과 유사하였다. 산과 알칼리세척 순서를 바꿔서 CIP를 수행한 결과 산세척을 먼저 수행시 CIP 효율이 더 높은 것으로 나타났다.
        4,000원
        10.
        2006.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Generally, it has been known that positive plate efficiency is the most influential effect on the initial current capacity of lead acid battery. Thus, in this study, we have investigated the curing effect of the positive plate, which is one of the important lead acid battery processes. The curing process of the positive plate is performed either with the separation of each plate with 1mm gap or with no gap of plate. As a result, when there is no interval between each plate, the higher temperature current happened than expected, resulting in the changes in the initial current efficiency of the lead acid battery. The chemical composition and crystal structure of a material coated on the positive plate were identified with XRD and SEM. It was resulted that were only there not a lot of 4BS (tetrabasic-lead sulfate, 4PbO·PbSO4) on the plate in case of curing of plates without interval, but a large quantity of Pb3O4 also formed on the surface. On the other hand, it was observed that 3BS (tribasic-lead sulface, 3PbO·PbSO4·H2O) was the main product on the plate in case of typical curing process with some interval. From the initial current capacity test, the positive plate having 3BS was approximately 40% higher in initial current capacity than that having 4BS. It was concluded that 4BS and Pb3O4 on the plate surface were harmful to the initial current capacity of lead acid battery.
        4,000원
        16.
        1994.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목장에서 가축음용수 빛 세척수로 사용하는 목장용수에 대한 위생화학척 상태률 계절척으로 조사하기 위하여 강훤도 및 충청도에 소재한 유우목장 58 곳에서 채취한 목장용수에 대하여 pH, 총경도, 과망간산칼륨소비량, 질산성 질소, 암모니아성 질소, 염소이온, 황산이온, 불소, 철, 납, 카드융, 아연, 망간, 동 및 크롬올 봄과 여름 2 회 조사하였다. 충남지역과 강원지역 목장용수의 pH 는각각 6.49:t 0.09, 6.70 :t 0.06 이었으며, 총경도 9O.2l:t 7.07, 64.53:t 6.38 mg/l, KMn04 소비량 4.13:t 0.62, 4.34 :t 0.26 mg/l , 질산성질소 6.51:t 0.55, 3.6l:t 0.58 mg/l , 염소이온 20.51 :t 1.99, 5.41 :t 1.36 mg/l 그리고 황산이온 6.61 :t 1.02, 7.28:t 1.30 m g/l이었으며, 암모니아성 질소는 거의 검출되지 않았다. 검사한 중금속 불소, 철, 납, 카드륨, 아연, 망간, 동 및 크롬은 검출되지 않았거나 극미량만 검출되었다. 검사항목간의 관계를 비교하면 총갱도, 철산성질소, 염소이용 및 황산이 옹은 검사항목간 상관관계를 나타내었다. 검사항목 중 충남과 강훤 목장용수간 지역켜 차이률 나타낸 항목은 총갱도, 질산성질소 및 염소이온이였으며, 봄과 여름에 차이를 나타낸 항목은 질산성질소 뿐이었다.
        4,000원
        17.
        2018.05 서비스 종료(열람 제한)
        Background : Oplopanax elatus has many compounds such as essential oils, saponin, flavonoids, anthraquinones, and polyacetylenes etc. in all part of stems, roots, and leaves. It is traditionally used to treat asthma, depressive states, chronic fatigue syndrome, diabetes mellitus, rheumatism, arthritis, gastrointestinal disorders, and wounds. In this study, the evaluation of several factors affecting the variation of chemical constituents and antioxidant activity in stem of O. elatus. Methods and Results : Five compounds (uracil, adenosine, protocatechuic acid, syringin, and scoparone) were isolated from the water extract of in stems of O. elatus. We extracted stems of them with hot water by different temperature (85 and 100℃) and times (1, 4, and 7 hrs.) and analyzed contents of five compounds by HPLC and antioxidant activity such as DPPH, ABTS and reducing power assay. The contents of five compounds varied depending on the extraction time and extraction temperature, the contents of uracil and protocatechuic acid in extracts of stems reduced with times. However, there is no difference the amount of variation in chemical constituents in stems of O. elatus. The antioxidant free radical scavenging activities of its stem extracts in 85℃ water (IC50 = 34.56 ± 0.8 ㎍/㎖ of extracts) showed more activity than extracts in 100℃ water (IC50 = 39.58 ± 1.6 ㎍/㎖ of extracts) in ABTS assay. Conclusion : In conclusion, the contents of five compounds were not significantly affected by extraction time and extraction temperature. Therefore, these results could be basic data for the quality management of five compounds in stems of O. elatus extracted with hot water.
        18.
        2016.07 KCI 등재 서비스 종료(열람 제한)
        The initial and boundary conditions are important factors in regional chemical transport modeling systems. The method of generating the chemical boundary conditions for regional air quality models tends to be different from the dynamically varying boundary conditions in global chemical transport models. In this study, the impact of real time Copernicus atmosphere monitoring service (CAMS) re-analysis data from the modeling atmospheric composition and climate project interim implementation (MACC) on the regional air quality in the Korean Peninsula was carried out using the community multi-scale air quality modeling system (CMAQ). A comparison between conventional global data and CAMS for numerical assessments was also conducted. Although the horizontal resolution of the CAMS re-analysis data is not higher than the conventionally provided data, the simulated particulate matter (PM) concentrations with boundary conditions for CAMS re-analysis is more reasonable than any other data, and the estimation accuracy over the entire Korean peninsula, including the Seoul and Daegu metropolitan areas, was improved. Although an inland area such as the Daegu metropolitan area often has large uncertainty in PM prediction, the level of improvement in the prediction for the Daegu metropolitan area is higher than in the coastal area of the western part of the Korean peninsula.
        19.
        2016.04 KCI 등재 서비스 종료(열람 제한)
        Factors affecting germination of seeds in the forms of various environment and chemical compounds. The present study was aim to produced effective seed propagation method of Astilbe koreana (Kom.) Nakai which had expected high value for the cut flower, ornamental and pharmaceutical material. Seed width and length ranged 0.62, 2.22 ㎜, respectively, and weight of thousand seeds was 40.5 ㎎. As result of imbibition test, showed moisture content of fresh seed (2.57%) increased rapidly by water-soaking treatment under 24 hours, recording to maximum value of 29.8%, and expansion of the seed coat was observed. Seed germination was the best at 15℃ and light conditions (40.8%) among temperature and light conditions treated. Percent germination of seeds was improved under the low (15, 20℃) than high temperature (25, 30℃). In addition, the seed was not germinated at dark condition regardless of temperature. Seeds of A. koreana thus seemed that it had low temperature germinability conditions. To improve germination rate, seeds were submerged in various concentrations of growth regulators such as GA3 and kinetin, and minerals as KNO3 and KCl. As a results, KNO3 treatment, regardless of concentrations, promoted germination compared to control. Especially, percent of germination (77.8%), germination energy (96.1%), mean germination time (11.3 days) and T50 (6.5 days) were effectively improved by treatment of KNO3 20 mM.
        20.
        2009.10 KCI 등재 SCOPUS 서비스 종료(열람 제한)
        배추김치의 저장 온도와 저장 기간별 total GSLs 함량을 분석하기 위하여 2007년 6~7월, 8~9월, 10~11월, 12~4월 및 5월(2008년) 수확하여 제조한 배추김치를 anion-exchange column을 통과시키고 아세톤 침전법을 사용하여 제조한 crude myrosinase로 반응시켜 함량 변화를 측정하였다. 수분 함량의 경우 8~9월 배추김치가 다른 기간에 제조된 배추김치에 비해 높게 나타났으며 pH의 경우 저장 3일,
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