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        검색결과 407

        81.
        2018.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examined the effects of drying methods of Aronia melanocarpa on contents of total polyphenols and flavonoids, antioxidant activity and anti-inflammatory activity. As a result, freeze-dried aronia extract (FDAE) significantly exhibited higher contents of total polyphenols and flavonoids (155.76 mg GAE/g and 105.70 mg QE/g) than hot-air dried aronia extract (HDAE) (134.93 mg GAE/g and 82.29 mg QE/g). Also, FDAE showed greater antioxidant activity than HDAE in both DPPH and ABTS. For anti-inflammatory activity, NO production from lipopolysaccharide activated RAW264.7 cell reduced at a dose-dependent manner in both FDAE and HDAE. However, reduction rate of NO production is higher in FDAE (62.7%) than in HDAE (33.5%). These results suggest that comparatively, freezedrying is a better method for preserving the antioxidant and anti-inflammatory activities and of aronia.
        4,000원
        82.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The role played by reservoirs in the biogeochemical cycles of elements is a subject of ongoing debate. Recent research has revealed that reservoirs emit significant levels of greenhouse gases. To assess the importance of reservoirs in monsoon climate areas as a source of methane gas into the atmosphere, we investigated variations in organic carbon (OC) input into the reservoir, oxic state changes, and finally the amount of methane emitted (focusing on the ebullition pathway) in Lake Soyang, which is the largest reservoir in South Korea. Total organic carbon (TOC) concentrations were higher during summer after two years of heavy rainfall. The sedimentation rates of particulate organic carbon (POC) and particulate organic nitrogen (PON) were higher in the epilimnion and hypolimnion than the metalimnioin, indicating that autochthonous and allochthonous carbon made separate contributions to the TOC. During stratification, oxygen depletion occurred in the hypolimnion due to the decomposition of organic matter. Under these conditions, H2S and CH4 can be released from sediment. The methane emissions from the reservoir were much higher than from other natural lakes. However, the temporal and spatial variations of methane ebullition were huge, and were clearly dependent on many factors. Therefore, more research via a well-organized field campaign is needed to investigate methane emissions.
        4,000원
        84.
        2018.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The objective of this study was to develop a standard for setting a legal system for senior-friendly food. We conducted a web-based survey on 95 food industry workers. Answers to 10 questions in the survey were analyzed using SPSS 19.0. Important factors to consider when it comes to food for seniors are the supply of balanced nutrition, enhancement of functionality, and promotion of convenience. A total of 47 respondents (51.1%) felt the need for a legal system for senior food, and they thought that a certification for senior-friendly food would be advantageous for companies. They said that there should be texture standards to promote ease of chewing, standards for functionality, nutritional standards, and safety standards to certify senior-friendly foods. A total of 41 people (44.6%) said that it was reasonable to classify Japanese food into five levels of senior-friendly foods according to ease of chewing. Certification management received the highest score in implementing an activation plan for senior-friendly food.
        4,200원
        85.
        2018.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Stroke patients show abnormal walking patterns due to brain injury. In order to have the desired walking pattern, appropriate stimulation is required to activate the central pattern generator. For this reason, our study performed treadmill ambulatory training with rhythmic auditory stimulation. However we did not consider the influence of visual feedback. Objects: The purpose of this study was to compare the gait abilities in chronic stroke patients following either treadmill walking training with rhythmic auditory stimulation and visual feedback (TRASVF) or treadmill walking training with rhythmic auditory stimulation (TRAS) alone. Methods: Twenty-one stroke patients were divided into two groups: A TRASVF group (10 subjects) and a TRAS group (11 subjects). They received 30 minutes of neuro-developmental therapy (NDT) and walking training for 30 minutes, five times a week for three weeks. Temporal and spatial gait parameters were measured before and after the training period. The Biodex gait trainer treadmill system measured gait parameters. Results: After the training periods, the TRASVF group showed a significant improvement in walking speed, the step length of the affected limb, and time on each foot of the affected limb when compared to the TRAS group (p<.05). Conclusion: The results of this study showed that the treadmill walking training with rhythmic auditory stimulation and visual feedback improved individual gait ability more than the treadmill walking training with rhythmic auditory stimulation alone. Therefore, visual feedback should be considered along with rhythmic auditory stimulation training.
        4,000원
        87.
        2018.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Rare earth elements (REEs) are considered to be vital to modern industry due to their important roles in applications such as permanent magnets, automobile production, displays, and many more. The imbalance between demand and supply of REEs can be solved by recycling processes. Regarding the needs of industry and society, the International Organization for Standardization, Technical Committee 298 (ISO/TC298) Rare Earths has been recently launched for developing international standards on rare earth elements. In accordance with the suggestion of its constituents, it is tentatively working to develop the appropriate standards under five working groups (WG) on terms and definitions (WG1), element recycling (WG2), environmental stewardship (WG3), packaging, labelling, marking, transport, and storage (WG4), and testing analysis (WG5). The scope and structure of ISO/TC298 on the topic of rare earths is discussed in this document.
        4,000원
        88.
        2018.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Long-term variation of zooplankton community and species composition was studied from 2003 to 2014 in a deep reservoir, Lake Soyang, in monsoon climate region, Korea. In addition, we examined the correlation with environmental factors. Annual precipitation of watershed showed a large variation in the 705~1,779 mm yr-1 and more than 70% of it was being concentrated from June to September. The water quality of Lake Soyang was shown a clearly seasonal variations and particularly turbid water flowing into the lake during rainy season was the most important environmental factors. Zooplankton community in Lake Soyang showed a significant difference before and after 2006. Zooplankton biomass has shown a large increase and also showed a change in the zooplankton community structure since 2006. The of zooplankton showed positive correlation with temperature and BOD, Chl. a, TP concentration. These results are considered that nutrient and organic matter contained in the turbid water influences the increase in zooplankton biomass and species composition. However, water quality was limited to account for the increase in biomass of zooplankton. For example, increase of small zooplankton density (rotifer; Keratella cochlearis, Polyarthra vulgaris) in spring which is dominated by diatoms (large size; Melosira, Synedra etc.) is considered as a bottom-up effect by the microbial loop. And increased density of crustaceans in autumn was considered a top-down effects by the relationship between predator and prey of microzooplankton and mesozooplankton. In other words the inflow of allochthonous organic matter during rainy season also affected to zooplankton food web in Lake Soyang. In conclusion, biomass, diversity and long-term variations of zooplankton in Lake Soyang were determined by physico-chemical factors but also it is considered that biological interactions is important.
        4,200원
        89.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        시중에 유통 중인 물휴지 62 품목을 선정하여 살균보존 제 성분 및 유해물질 함유 여부 등의 안전성을 조사하였다. 일반적으로 화장품 및 식품에 가장 많이 사용하는 살균 보존제인 안식향산나트륨은 46 품목에서 200~3500 ppm 검출되었고 파라벤류는 1품목에서 파라옥시안식향산메칠이 9 ppm 검출되었다. 사용할 수 없는 살균보존제인 메칠클로로이소치아졸리 논과 메칠이소치아졸리논(3:1)혼합물이 1 품목에서 검출되어 부적합 판정되었으며, 메칠클로로이소치아졸리논 5 ppm, 메칠이소치아졸리논 140 ppm 검출되었다. 염화세틸피리디늄은 5 품목에서 7~13 ppm 검출되었으 며, 모두 허용기준 이내로 나타났다. 잔류유해물질인 포름알데히드 검사결과는 0.069~1.796 μg/ g로 허용기준인 20 μg/g 이하였다. 메탄올은 5~51 ppm 검출되었으며, 이 중 4 품목에서 허용기준인 20 ppm보다 2배 이상의 농도가 나타났다. 안전한 제품이 유통될 수 있 도록 메탄올의 잔류경로에 대한 지속적인 조사 및 모니터 링이 필요하다고 판단된다. 물휴지의 pH를 측정한 결과 4.0~8.2로 나타나 유통화장 품의 pH 3.0~9.0 기준에 적합하였으나, 물휴지에는 pH 기 준이 설정되어 있지 않으므로 안전관리를 위해서는 pH 기준을 설정하는 고시개정이 필요할 것이다.
        4,000원
        90.
        2017.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the surface passivation process for InP-based quantum dots (QDs) is investigated. Surface coating is performed with poly(methylmethacrylate) (PMMA) and thioglycolic acid. The quantum yield (QY) of a PMMA-coated sample slightly increases by approximately 1.3% relative to that of the as-synthesized InP/ZnS QDs. The QYs of the uncoated and PMMA-coated samples drastically decrease after 16 days because of the high defect state density of the InP-based QDs. PMMA does not have a significant effect on the defect passivation. Thioglycolic acid is investigated in this study for the effective surface passivation of InP-based QDs. Surface passivation with thioglycolic acid is more effective than that with the PMMA coating, and the QY increases from 1.7% to 11.3%. ZnS formed on the surface of the InP QDs and S in thioglycolic acid show strong bonding property. Additionally, the QY is further increased up to 21.0% by the photochemical reaction. Electron–hole pairs are formed by light irradiation and lead to strong bonding between the inorganic and thioglycolic acid sulfur. The surface of the InP core QDs, which does not emit light, is passivated by the irradiated light and emits green light after the photochemical reaction.
        4,000원
        91.
        2017.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Recently, weight lightening is a key issue for various mechanical components to improve the fuel efficiency. For this reason, many researchers have been studying focused on the development of surface hardening treatment and metallic materials with high strength and wear resistance. In this study, we examine the formation of carbide at the surface of the gear machined by SCM420H steel after super-carburizing in order to improve the wear resistance of gear. The experimental results show that super-carburizing heat treatment gives rise to carbide dispersion across wider range of depth and higher carbon concentration than general carburizing heat treatment. Carbide having spheroidal or spherical shape had a size under 2 micro-meter produced in austenite grain boundaries or within austenite grains during super-carburizing. The super-carburized specimen maintained the hardness, HV700 above, at the 0.6mm depth and had a 10.4% lower coefficient of friction which was 0.766. This results from the dispersed carbide which lowered the coefficient of friction and ended up affecting wear resistance. Consequently, we conclude that super-carburizing heat treatment has more influence on the improvement of hardness, wear resistance compared to general carburizing heat treatment.
        4,000원
        92.
        2017.10 구독 인증기관·개인회원 무료
        만석골저수지 수계의 수서곤충의 군집과 그에 따른 수질을 알아보기 위하여 2017년 9월 9일~9월 17일 까지채집을 하였다. 채집은 그물망을 이용하였고 총 6개의 지점을 선정하였으며 각 지점에서 채집된 곤충은 총 7목18과 30종이었다. 노린재목이 31.8%, 잠자리목이 21.9%였다. 그 뒤로 날도래목 18.7%, 딱정벌레목 11.3%, 뱀잠자리목5.7%, 강도래목과 파리목은 5.3%였다. 우점도지수로 살펴본 결과 전체에서는 장구애비가 최고우점종이었고 물자라가2차 우점종이었으며 우점도지수는 7.4%였다. 조사지점별로는 조사지점 1~4까지의 최고우점종은 날도래류였으며그뒤는 강도래류, 뱀잠자리류, 잠자리류 등 다양했다. 5~6지점은 물자라, 줄동애등에가 각각 최고 우점종이었다.1~4까지의 지점의 최고우점종을 봤을때는 수질이 청정함을 알 수 있었고 5~6의 수질도 2~3급수 정도이나 줄동애등에의개채수로 봤을 때는 수질에 의심이 가나 수질조사와 충분한 개채수가 확보될 떄 판단이 가능하다.
        93.
        2017.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Caesalpinia sappan L. is an oriental medicinal plant distributed in the Asia Pacific region including India, Malaysia, and China. The dried heartwood of Caesalpinia sappan has been traditionally used as an analgesic and anti-inflammatory drug. In this study, the effects of extract methods of C. sappan on contents of total polyphenols and flavonoids, antioxidant activity, and cytotoxic activity were evaluated. As a result, hot water extract from C. sappan (CSWE) significantly exhibited contents of total polyphenols and flavonoids (22.6 mg GAE/g and 14.5 mg QE/g) higher than 70% ethanol extract (CSEE) (17.6 mg GAE/g and 13.2 mg QE/g). However, CSEE showed greater antioxidant activity than CSWE in both DPPH and ABTS. Also, the cytotoxicity of C. sappan against three kinds of cancer cell lines was higher in CSEE than in CSWE. These results show that ethanol extract is a better extract method than hot water method to maintain antioxidant and anti-cancer activities.
        4,000원
        94.
        2017.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        목 적 : 공기와 인체조직 간에 경계면에서 자화율 차이로 인한 자장의 불균일은 불균질한 지방소거(fat suppression)을 일으 킨다. 이에 본 연구는 폴리스티렌(polystyrene) 적용 전·후에 따른 자장의 불균일 보정을 통해 fat suppression 개선 효과를 알아보고자 하였다. 대상 및 방법 : Phantom study는 본 연구를 위해 자체 제작한 fat phantom에 테스트물질 공기, 쌀, 폴리스티렌(polystyrene ball bullet), 발포성 폴리스티렌(expandable poly-styrene beads), 폴리프로필렌 칩형태(polypropylene chip type), 폴리프 로필렌 작은 칩형태(polypropylene small chip type)을 각각 넣고, 자화율 차이에 민감한 SPIR T1 weighted image(T1WI) 영상을 획득하여 Fat과 테스트 물질 경계면의 signal intensity(SI)를 측정하였다. Patient study는 2016년 11월부터 동년 12 월까지 neck 검사를 시행한 환자 12명을 대상으로 하였으며, 폴리스티렌(polystyrene ball bullet)을 목에 감쌀 수 있게 자체 제작하여 착용 전·후 SPIR T1WI을 획득하였다. Phantom study의 평가방법은 fat과 테스트 물질 경계면의 SI변화를 알아 보고 SNR을 비교평가 하였고, Patient study는 MRI 전문방사선사 3명이 neck 부분영상의 fat suppression 정도에 대해 리 커트(Likert scale) 5점 척도로 영상을 평가하였다. 통계적 분석은 대응표본 T검정을 이용하여 유의성을 검증하였다. 결 과 : Phantom 영상에서 평균 SI는 공기 1516.5±121.46, 쌀 240.5±4.46, 폴리스티렌 183.83±29.38, 발포성 폴리스티렌 1483.67±155.36, 폴리프로필렌 칩 형태 258.17±3.6, 폴리프로필렌 작은 칩 형태 140±26.07으로 측정되었다. SNR의 경우 는 공기(1495.55) > 발포성 폴리스티렌(1406.32) > 폴리스티렌(660.48) > 쌀(621.98) > 폴리프로필렌 칩 형태(512.91) > 폴리 프로필렌 작은 칩 형태(506.02)의 순으로 확인되었다. Patient study SPIR T1WI 영상의 정성적 평가 결과는 착용 전 평균값 3.38±0.79점, 착용 후 평균값 4.33±0.54점으로 나타났으며, 통계적 분석은 유의확률이 0.002으로 유의한 결과를 보였다. 결 론 : 폴리스티렌은 MRI 이미지 신호에 영향이 없고 위생적이며 가볍고 인체에 적용하기 쉽다. 공기와 인체조직 간의 자 화율 차이를 보상할 수 있는 폴리스티렌 보정물을 이용한다면 fat suppression을 개선하여 진단적 가치가 높은 영상을 구현 할 수 있을 것으로 사료된다.
        4,000원
        95.
        2017.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, we investigate the optical properties of InP/ZnS core/shell quantum dots (QDs) by controlling the synthesis temperature of InP. The size of InP determined by the empirical formula tends to increase with temperature: the size of InP synthesized at 140oC and 220oC is 2.46 nm and 4.52 nm, respectively. However, the photoluminescence (PL) spectrum of InP is not observed because of the formation of defects on the InP surface. The growth of InP is observed during the deposition of the shell (ZnS) on the synthesized InP, which is ended up with green-red PL spectrum. We can adjust the PL spectrum and absorption spectrum of InP/ZnS by simply adjusting the core temperature. Thus, we conclude that there exists an optimum shell thickness for the QDs according to the size.
        4,000원
        98.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구는 2014년 7월부터 2015년 9월까지 제주 한국마 사회 제주육성목장(해발 450m) 시험포장에서 여름 동안 생산성이 유지될 수 있는 남방형 목초를 도입하여 재배에 이용하기 위하여 Bermudagrass 품종(Cynodon dactylon (L.) Pers. : Giant, Cheyene, Mohawk, Panchero Frio, Common) 과 Bahiagrass 품종(Paspalum notatum : TifQuik, Tifton 9, Argentine), 그리고 Teff grass(Eragrostis tef : Tiffany) 품종 의 생육특성 및 건물 수량을 평가하기 위하여 실시하였다. 실험설계는 품종을 처리로 10처리 3반복 난괴법으로 배치 하였다. 1차년도 1차 수확은 8월 31일, 2차 수확은 9월 21일이며 2차년도 1차 수확은 7월 22일, 2차 수확은 8월 14 일, 3차 수확은 9월 11일로 성장단계를 고려하여 수확하였 다. 1차년도 남방형 품종의 건물 수량은 Teff grass의 Tiffany가 산파와 조파 각각에서 2.59와 2.00Ton/ha로 가 장 높은 건물수량을 나타내었으며, Bermudagrass의 Common이 산파에서 1.21Ton/ha로 다년생 남방형 목초 중 가장 높은 수량을 나타내었다. 2차년도 남방형 품종의 건물 수량은 Bahiagrass의 Tifton9이 산파에서 15.06Ton/ ha로 가장 높은 수량을 나타내었으며 Bahiagrass의 Tifquik이 산파에서 14.68Ton/ha로 두 번째로 높은 수량을 나타내었다. 조단백질 함량은 Bahiagrass의 Argentine이 19.75%로 가장 높게 나타났으며 NDF 함량은 Bermudagrass 의 common이 61.69%로 가장 높은 것으로 나타났다. 한해 에 의한 피해의 경우 대부분의 Bermudagrass 품종의 경우 에 동절기 적응성이 떨어졌으나 Bahiagrass의 Tifton 9 품 종의 경우 한해에 대한 피해를 거의 받지 않았으며 출현, 내병성, 내습성, 도복성은 품종 간 차이가 거의 없었으며 Teff grass의 Tiffany이 도복과 습해에 의한 피해가 나타났다. 이상의 결과를 종합해 볼 때 제주지역에서 Bermudagrass와 Bahiagrass의 일부 품종은 월동할 수 있어 여름철 조사료자 원으로 활용이 가능하지만, 품종 간 내한성 능력과 재생능 력이 다르므로 이를 고려하여 품종을 선택할 필요가 있다.
        4,000원
        99.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates the main growth mechanism of InP during InP/ZnS reaction of quantum dots (QDs). The size of the InP core, considering a synthesis time of 1-30 min, increased from the initial 2.56 nm to 3.97 nm. As a result of applying the proposed particle growth model, the migration mechanism, with time index 7, was found to be the main reaction. In addition, after the removal of unreacted In and P precursors from bath, further InP growth (of up to 4.19 nm (5%)), was observed when ZnS was added. The full width at half maximum (FWHM) of the synthesized InP/ZnS quantum dots was found to be relatively uniform, measuring about 59 nm. However, kinetic growth mechanism provides limited information for InP / ZnS core shell QDs, because the surface state of InP changes with reaction time. Further study is necessary, in order to clearly determine the kinetic growth mechanism of InP / ZnS core shell QDs.
        4,000원
        100.
        2017.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We have investigated the washing method of as-synthesized CdSe/ZnS core/shell structure quantum dots (QDs) and the effective surface passivation method of the washed QDs using PMMA. The quantum yield (QY%) of assynthesized QDs decreases with time, from 79.3% to 21.1%, owing to surface reaction with residual organics. The decreased QY% is restored to the QY% of as-synthesized QDs by washing. However, the QY% of washed QDs also decreases with time, owing to the absence of surface passivation layer. On the other hand, the PMMA-treated QDs maintained a relatively higher QY% after washing than that of the washed QDs that were kept in toluene solution for 30 days. Formation of the PMMA coating layer on CdSe/ZnS QD surface is confirmed by HR-TEM and FT-IR. It is found that the PMMA surface coating, when combined with washing, is useful to be applied in the storage of QDs, owing to its long-term stability.
        4,000원
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