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        검색결과 28

        1.
        2024.04 구독 인증기관·개인회원 무료
        Spider silk, which combines strength and lightness, emerges as an ideal candidate for non-woven fabric production. Unlike synthetic polymeric materials, silk are nontoxic and biocompatible and cause no allergic reaction. In particular, the dragline silk produced by the golden orb-web spider, Trichoephila clavata, is renowned for its superior strength and exceptional mechanical properties compared to other spider silks. Non-woven fabrics have found extensive applications in diverse industrial sectors, owing to their advantageous qualities such as breathability, durability, and lightweight characteristics. Natural dragline silk was extracted from the orb-weaving spider and subsequently randomly arranged. Compressing into a sheet-plane form, in addition to inducing the formation of water-resistant, stable β-sheet structures through ethanol vapor treatment or direct treatment, preserved the morphology of the silk fibers. The resulting non-woven sheets were analyzed with an field emission scanning electron microscope (FESEM) to observe their fine structures and mesh size were measured through image analysis.
        2.
        2024.04 구독 인증기관·개인회원 무료
        The genus Argiope are known to decorate their webs with various patterns. The purpose of these web decorations, referred to as stabilimenta, is still a subject of debate. They are believed to serve either as lures to attract prey insects or as a means of providing protection to the spider by enhancing the web's visibility to deter potential predators. In this study, we observed spider orientation with respect to the direction of the sun in a controlled laboratory environment. To assess the orientation preference of the spider, the frame was repositioned daily by reversing its direction. Over a period of 21 days, the orientation of the spider was meticulously recorded, distinguishing between the illuminated side (open side) and the shaded side (closed side). field emission scanning electron microscopy (FESEM) visualization were used to investigate the microstructural characterization of stabilimenta in both juvenile and adult spiders. Our results represent that the decorative structure of stabilimentum shows diverse microstructural features according to the maturation level of the spider. In addition, it has been confirmed that spiders tend to prefer the open side direction when stabilimentum is present.
        3.
        2021.12 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 과불화합물 PFOA와 PFOS potassium salt가 Mesocentrotus nudus의 10 min-수 정률과 48 h-정상유생발생률에 미치는 독성영향을 반수영향농도, 무영향농도, 최소영향농도 등 의 독성값 계산을 통해 확인하였다. PFOA와 PFOS potassium salt에 대한 10 min-수정률의 EC50 값은 각각 1346.43 mg/l와 536.18 mg/l로 나타났으며, 48 h-정상유생발생률의 EC50 값은 각각 42.67 mg/l와 17.81 mg/l로 나타났다. 최근 연구에 의하면, 환경 내의 PFOA와 PFOS의 농도는 지속적으로 감소하였으며, 성게류에게 급성독성을 나타낼 정도는 아닌 것으로 나타났다. 하지 만 생물체내에서는 여전히 높은 농도로 관측되고 있다. 결국, PFOA와 PFOS는 생물체의 생애 전주기에 걸쳐 체내 축적이 가능하기 때문에, 연안환경에 서식하는 해양생물을 이용한 생애 전주기적 만성독성 연구가 필요할 것이다.
        4,000원
        4.
        2020.12 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 살균제, 항진균제 등의 의약품을 포함하여 다양한 목적으로 사용되며, 신방오도 료로서의 가능성이 확인된 바 있는 Zinc undecylenate (ZU)를 이용해 연안환경 내 1차 소비자를 대표할 수 있는 성게 2종(H. pulcherrimus, M. nudus)에 대한 독성평가를 실시하였다. 실험결과 ZU에 대한 H. pulcherrimus와 M. nudus의 수정률 EC50은, 각각 11.27 mgl-1과 1.48 mgl-1로 나 타났다. 또한, 정상배아 발생률의 EC50은 각각 0.94 mgl-1와 3.78 mgl-1로 나타났으며, NOEC는 0.20 mgl-1, 0.78 mgl-1를 나타내었다. 본 연구에서 도출된 성게 2종과 문헌조사를 통한 연안양 식생물 2종의 급성독성결과를 이용하여 Predicted No Effect Concentration (PNEC)를 계산하였 다. PNEC 값은 0.0094 mgl-1로 나타났으며, 위와 같은 결과는 해양환경 오염물질에 대한 환경 보호전략 수립을 위한 기초자료로 활용될 것이다.
        4,000원
        5.
        2020.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 다환방향족탄화수소 (PAHs) 중, phenanthrene이 둥근성게 (Mesocentrotus nudus)와 말똥성게 (Hemicentrotus pulcherrimus)의 수정률과 정상유생 발생률에 미치는 독성 효과를 확인하고자 하였다. H. pulcherrimus와 M. nudus의 모체에서 각각 획득한 정자와, 인공수정을 통하여 획득된 수정란을 phenanthrene에 노출시킨 후, 수정률과 정상배아 발생률을 측정하였다. 시험결과, H. pulcherrimus 와 M. nudus의 수정률과 정상배아 발생률은, 농도 의존적으로 감소하였으며, H. pulcherrimus와 M. nudus의 수정률에 대한 EC50값은 17.48 mg L-1과 16.21 mg L-1이었고, 정상배 아 발생률의 EC50값은 각각 2.99 mg L-1과 0.36 mg L-1인 것 으로 나타났다. 연구결과, H. pulcherrimus는 M. nudus보다 phenanthrene 노출에 대하여 더 민감하게 반응하는 것으로 나타났으며, 정상배아 발생률은 수정률에 비하여 더 민감한 종말점인 것으로 나타났다. 따라서, phenanthrene은 두 종의 성게 정자의 수정과 초기발달 단계를 포함한, 연안에 서식하는 다양한 생물종에 영향을 미치는 것으로 보여진다. 그중, 두 종의 성게는 다른 연안 서식 생물 종들에 비하여, Phenanthrene의 bio-monitoring을 위한 민감한 생물종일 수 있다고 사료된다. 또한, 본 연구를 통하여 도출된 결과와 독성값 (NOEC, LOEC 및 EC50)은 Phenanthrene 을 포함한 PAHs의 환경 기준농도 설정을 위한 유용한 기 초 자료로 활용될 수 있다.
        4,000원
        6.
        2020.06 구독 인증기관 무료, 개인회원 유료
        Irgarol과 diuron에 각각 노출된 해산규조류(Skeletonema costatum)의 개체군 성장률(r )을 분석 하여 독성평가를 실시하였다. S. costatum을 irgarol (0, 0.31, 0.63, 1.25, 2.5, 5 μg l-1)과 diuron (0, 7.81, 15.63, 31.25, 62.5, 125 μg l-1)에 각각 96시간 노출하여 r 을 계산하였고, 대조구의 r 은 0.04 이상으로 시험기준에 적합하였다. S. costatum의 r은 irgarol에서 0.63 μg l-1, diuron은 15.63 μg l-1 이상에서 대조구 대비 유의하게 감소하기 시작하여 irgarol과 diuron의 농도가 증가할수록 r이 감소하는 농도의존적인 반응을 나타냈고, 시험 최고농도 5와 125 μg l-1에서 r이 대조구 대비 80% 이상 감소하였다. Irgarol과 diuron에 노출시킨 S. costatum r의 반수영향농도(EC50)는 1.09, 45.45 μg l-1, 무영향농도(NOEC)는 0.31, 7.81 μg l-1, 최소영향농도(LOEC)는 0.63, 15.63 μg l-1으로 나타났으며, EC50 기준으로 irgarol이 diuron보다 독성이 큰 것으로 나타났다. 본 연구결과로 해양 생태계에서 Irgarol과 diuron의 농도가 0.63과 15.63 μg l-1 이상이 되면, 해산 규조류 S. costatum 의 r은 독성영향을 받을 것으로 판단된다. 또한, 독성 값으로 제시된 결과들은 irgarol과 diuron 의 기준농도 설정을 위한 기초자료로 유용하게 활용될 것이다.
        4,000원
        8.
        2017.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The acidity of soy curd fermented by lactic acid bacteria is a major factor degrading the sensory properties of soy curd. For preparation of soy curd with low sour taste, lactic acid bacteria were separated from kimchi. The lactic acid bacteria which showed yellow-clear zone around the colonies on BCP plate and formed soy curd with low level of acidity were selected. The selected strain was analyzed by 16S rDNA sequence and named as Pediococcus inopinatus Y2. The maximum viable cell number of the soy curd fermented by P. inopinatus Y2 was obtained at 10.73 log CFU/mL at 25°C for 24 h of fermentation. By the results of panel test, the overall sensory quality of the soy curd produced by P. inopinatus Y2 was higher than that of Leuconostoc mesenteroides No. 4395 and Lactobacillus sakei strain No. 383.
        4,000원
        9.
        2017.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was carried out to investigate antimicrobial activity and characteristics of Asparagus cochinchinenesis which was steamed and fermented with lactic acid bacteria. A. cochinchinensis was prepared to steaming process which was washed and freeze dried. A. cochinchinensis was steamed at 95oC for 12 h and dried by hot air at 50oC for 24 h. After steaming process, A. cochinchinensis was fermented with lactic acid bacteria (Leuconostoc mesenteroides 4395, Lactobacillus sakei 383 and Lactobacillus plantarum KCCM 11322). Ethyl acetate extracts of fermented A. cochinchinensis had antimicrobial activities for the respiratory disease bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli). A. cochinchinensis had highest antimicrobial activity for the P. aeruginosa which fermented with L. mesenteroides 4395. The minimum inhibition concentration (MIC) of A. cochinchinensis fermented with L. mesenteroides 4395 was 10 mg/mL for S. aureus, S. epidermidis, E. coli and 5 mg/mL for P. aeruginosa. The MIC of A. cochinchinensis fermented with L. sakei 383 and A. cochinchinensis fermented with L. plantarum KCCM 11322 were the same. Total sugar was decreased from 863.33±17.47 mg/mL to 722.67±5.51 mg/mL during the steaming process. But reducing sugar was increased from 99.36±1.32 mg/mL to 109.29±2.71 mg/mL during the steaming process. Total sugar was decreased to 301.50-361.42 mg/mL and reducing sugar was decreased to 27.39-62.20 mg/mL during the fermentation process.
        4,000원
        10.
        2014.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        해산규조류 Skeletonema cosatatum의 개체군성장률 (r) 을 사용하여 중금속 3종(Cd, Cu, Zn)의 독성영향 평가를 수행하였다. S. costatum을 Cd (0, 0.63, 1.25, 2.50, 5.00, 10.00 ppm), Cu (0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50 ppm) 그리고 Zn (0, 0.31, 0.63, 1.25, 2.00, 2.50, 5.00 ppm)에 노 출하고 96 h 이후에 r 값을 도출하였다. 대조구(Cd, Cu 그 리고 Zn을 포함하지 않은)에서 r은 0.05보다 높았으며 중금속 농도가 증가할수록 r은 감소하였다. 중금속에 의 해 농도의존적으로 r이 감소되었고 Cd 농도 1.25, Cu 농 도 1.25 그리고 Zn 농도 2.50 ppm 이상의 농도에서 명확 한 감소를 나타냈다. 중금속의 독성영향은 Cu¤Zn¤Cd 순서이며, 이때 EC50 값은 각각 1.11, 2.13 그리고 6.84 ppm으로 나타났다. 중금속 3종(Cd, Cu 그리고 Zn)에 노 출된 r의 최소영향농도는 각각 1.25, 1.00, 2.00 ppm으로 나타났다. 이 결과를 바탕으로, 해양환경에서 S. costatum 의 r은 Cd 농도가 1.25 ppm 이상, Cu 농도가 1.00 ppm 이 상, Zn 농도가 2.00 ppm 이상인 경우에 독성영향을 받았 다. 그러므로 S. costatum의 r은 해양환경에서 중금속 독 성영향 평가를 위한 매우 유용한 방법으로 판단된다.
        4,000원
        13.
        2007.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study reports on a classroom observation of the language produced by intermediate EFL learners in a Korean university, especially in terms of negotiation of meaning. Negotiation of meaning during task interactions makes certain that task participants receive comprehensible input and produce comprehensible output, which have been argued as essential elements for foreign language learning. Task type is also considered important, with those tasks requiring an exchange of information most likely to facilitate the negotiation of meaning. The purposes of this study was to compare successful meaning negotiation in four types of task(information gap, jigsaw, problem solving, and sharing personal experiences tasks) in terms of qualitative meaning negotiation. For this study, I recorded eight different tasks involving twenty-four students, a total of around five hours of learner interaction. This study showed that qualitative meaning negotiation is more important than the mere evidence of meaning negotiation indices for foreign language development. In terms of task type, open tasks such as problem solving and sharing personal experiences tasks may facilitate a higher qualitative negotiation than information gap tasks and jigsaw tasks, especially in intermediate or advanced English classes.
        6,000원
        14.
        2005.12 구독 인증기관 무료, 개인회원 유료
        Porcine oviduct epithelial cells (POEC) are widely used in co-culture experiments to improve early embryonic development, in vitro fertilization in embryo transfer programs for domestic animals and in vitro maturation of immature germ cells. POEC were mechanically isolated and cultured in tissue culture medium 199. Cells grew continuously, and confluent monolayers were formed after 7 days. After forming confluent monolayer of epithelial cells, supernatant was collected as the condition medium for maturing round spermatids in vitro. Round spermatids were also separated mechanically and cultured in the POEC condition medium. In this study we observed that 20% of round spermatid cultured were matured into elongating spermatid after 24 h, and about 10% of round spermatid cultured showed complete elongation (elongated spermatid) within 24~48 h of in vitro culture. No further development was observed within 50~72 h and transformed cells lost their viability after 72 h. These preliminary findings suggest that the condition medium from POEC may be possible to overcome the round spermatid block by improving the milieu of culture system.
        4,000원
        15.
        2005.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        5,700원
        16.
        2005.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The task-based approach to second or foreign language pedagogy aims to provide learners with a natural context for authentic language use. While learners are performing real-world or pedagogical tasks, they have opportunities not only to get a rich and comprehensible input of real language, but also to produce target language items to exchange meanings. Interaction in doing the tasks is thought to facilitate language learning process. Thus, one of the important things that teachers have to do first for their task-based English classes is to design tasks for target language items reflecting native speakers’ authentic language use. It is expected that learners can communicate with foreigners using the prescriptive target language items outside the classroom. This research attempted to find out if non-native English teachers would be able to make accurate predictions about target language items in terms of language forms and lexical phrases that would naturally occur when English native speakers carried out two types of tasks (closed tasks and open tasks). The results showed that many language items predicted by non-native English teachers did not appear in the recorded data by English native speakers, especially for open tasks. Thus, this research called into question the practice of setting tasks at the end of a PPP cycle (presentation, practice, and production), to allow students to put into use target language items that has previously been practised.
        5,100원
        17.
        2004.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study investigates how language teachers' pedagogical concerns can find a suitable framework for learner corpora-based error analysis in English classes. It demonstrates the ways in which teachers can benefit from compiling learner corpora and the ways in which they can transfer learner corpus findings to pedagogy. By analyzing the learner corpora and investigating common patterns of learners' errors, teachers can gain insights into learners' interlanguage development and provide feedback in the form of remedial teaching to cater for learners' linguistic needs. Consequently, this will help classroom instruction to be more effectively focused. The method of this study is both quantitative and qualitative in that it starts with a word-based method of analysis and ends with a category-oriented display of results. In addition, some classroom concordancing activities are suggested to present the idea of recycling learners' language output and transforming the output into a new form of input which is assumed to be comprehensible to learners.
        6,300원
        18.
        2002.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        6,400원
        19.
        2019.11 KCI 등재 서비스 종료(열람 제한)
        Environmental factors and changes in phytoplankton community structure before (August 5, 2017), during (August 18 and 25) and after (August 30 and September 15) freshwater input were analyzed to investigate the effects of freshwater input from Ganwol and Bunam lakes located in the upper part of Cheonsu Bay. Due to the large amount of freshwater input in the Cheonsu Bay, the surface salinity of the bay decreased by more than 8 psu, and the thermocline existing in the bay during August weakened. In addition, hypoxic phenomena occurred temporarily in the bay as the low oxygen water mass from the freshwater lakes flowed into the bay, and chemical oxygen demand, nutrients, and N/P increased with freshwater inflow. The density of phytoplankton during the freshwater inflow increased owing to their input from the freshwater lakes. Diatom species (Eucampia zodiacus) dominated the phytoplankton community in the bay before freshwater input; nanoflagellates, chlorophyta, cyanobacteria, and diatoms (Pseudonitzschia delicatissima, Chateocceros spp.) entered during freshwater input; and after freshwater inflow ended, diatoms (Chateocceros spp.) again became predominant indicating a return to previous conditions. The amount of phytoplankton standing crops increased sharply due to the inflow of freshwater species into the bay on the second day of discharge compared to before freshwater input; pre-discharge conditions were restored at most stations except at some sites close to the Bunam Lake three days after discharge. Therefore, the large amount of freshwater flowing into the bay affects not only the geochemical circulation in the bay but also the phytoplankton community structure. In particular, the high concentration of nutrients in the freshwater lake affect the marine ecosystem of the bay during August.
        20.
        2015.08 KCI 등재 서비스 종료(열람 제한)
        Purpose: Functional recovery of the paretic upper extremity post stroke continues to be one the greatest challenges faced by rehabilitation professionals. Although many tasks require the coordinated participation of both hands, rehabilitation strategies for the most part have focused on the paretic limb. This study investigated whether coupled bilateral coordinated movements and repetitive high frequency TMS enhanced upper limb corticomotor excitability and motor function poststroke. Methods: For this study, we compared the neurophysiological and behavioral changes associated with two such rehabilitation protocols: coupled bilateral training and coupled unilateral training. Twenty chronic stroke patients were randomly assigned to the two training group over 8-week period. For this experiment, transcranial magnetic stumulation, EMG, Ag/AgCI suface electrode, rehabilitation training equipment, jebsen-talyer hand function kit, box & block, and pinch & power grip test kit were used. Results: First, in the box & block and JTT task, coupled bimanual group showed a reduction in movement time in comparision to receiving coupled unilateral group. Second, in the cortical excitability within affected hemisphere, using TMS, an increased in map volume, and map number following coupled bilateral group. Overall, these finding suggest that a coupled bilateral movement and high frequency repetitive TMS protocol effective in recovering upper limb motor function and cortical excitability in chronic stroke patients.
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