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        검색결과 31

        1.
        2022.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this study, the removal efficiency of PFCs(perfluorinated compounds) in the GAC(granule activated carbon) process based on the superheated steam automatic regeneration system was investigated in laboratory scale and pilot-scale reactor. Among PFCs, PFHxS(perfluorohexyl sulfonate) was most effectively removed. The removal efficiency of PFCs was found to be closely related to the EBCT, and the removal efficiencies of PFOA(perfluorooctanoic acid), PFOS(perfluorooctyl sulfonate), and PFHxS were 43.7, 75, and 100%, respectively, under the condition of EBCT of 6 min. Afterward, PFOA, PFOS, and PFHxS exhibited the earlier breakthrough time in the order. After that, GAC was regenerated, and the removal efficiency of the PFCs before and after regeneration was compared. As a result, it was shown that the PFCs removal efficiency in the regenerated GAC process were higher, and that of PFOA was improved to 75%. The findings of this study indicate the feasibility of the superheated steam automatic regeneration system for the stable removal of the PFCs, and it was verified that this technology can be applied stably enough even in field conditions.
        4,600원
        2.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The activity of anaerobic ammonium oxidation (ANAMMOX) immobilized in synthetic media (Poly Ethylene Glycol, PEG) and granular form was evaluated comparatively to investigate the effect of influent nitrogen concentration and exposure of oxygen. In ANAMMOX granule reactor, when concentration of influent total nitrogen increased to 500mg/L, removal efficiency of ammonium, nitrite and nitrate were shown to 90.5±6.5, 96.6±4.9, and 93.2±6.1%, respectively. In the case of the PEG gel, it showed lower nitrogen removal performance, resulting in that the removal efficiency of ammonium, nitrite and nitrate were shown to 83.3±13.0, 96.4±6.1, and 90.3±7.5%, respectively. In second step, when exposed to oxygen, the nitrogen removal performance in the ANAMMOX granule reactor also remained stable, but the activity of PEG gel ANAMMOX was found to be inhibited. Consequently, the PEG gel ANAMMOX was a higher sensitivity than that of granular ANAMMOX with two variables applied in this study.
        4,000원
        5.
        2018.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The lack of seed sludges for Ammonium Oxidizing Bacteria (AOB) and slow-growing ANaerobic AMMonium OXidation (ANAMMOX) bacteria is one of the major problem for large-scale application. In this study, 24m3 of single-stage SBR (Sequencing Batch Reactor) was operated to remove nitrogen from reject water using AOB and ANAMMOX bacteria cultivated from activated sludge in the field. The ANAMMOX activity was found after 44 days of cultivation in the ANAMMOX cultivation reactor, and then 0.66 kg N/m3/d of the nitrogen removal rate was achieved at 0.78 kg N/m3/d of the nitrogen loading rate at 153 days of cultivation. The AOB cultivation reactor showed 0.2 kg N/m3/d of nitrite production rate at 0.4 kg N/m3/d of nitrogen loading rate after 36 days of operation. The cultivated ANAMMOX bacteria and AOB was mixed into the single-stage SBR. The feed distribution was applied to remove total nitrogen stably in the single-stage SBR. The nitrogen removal rate in the single-stage SBR was gradually enhanced with an increase of specific activities of both AOB and ANAMMOX bacteria by showing 0.49 kg N/m3/d of the nitrogen removal rate at 0.56 kg N/m3/d of the nitrogen loading rate at 54 days of operation.
        4,000원
        6.
        2018.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 강성 개폐식 대공간 건축물의 비정형 입체트러스를 파라메트릭 기법을 적용하여 모델링을 구현하는데 있다. 개폐식 대공간 건축물은 비선형성 형상을 모델링하거나 다수의 모델을 대안별로 생성, 해석, 검토하는 과정에 많은 시 간과 기술이 소요되는 것이 현 실정이다. 이러한 문제점을 해결하기 위해서 첫째로, 개발에 사용된 파라메트릭 모델링 전산 도구를 소개하고, 강성 개폐식 대공간 건축물의 비정형 입체트러스를 분석하며, 개발한 입체트러스의 파라메트릭 컴포넌트 로 모델링을 구현하게 된다. 따라서 지붕이 개폐되는 방식으로 구분한 입체 트러스 종류의 모델링을 구현해 낼 수 있는 컴포 넌트를 형상이나 기능에 따른 각각 대안별로 개발하여 효율적인 개폐식 지붕의 모델링을 가능하게 하는 것이 추후 연구사항 이다.
        4,000원
        7.
        2016.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Although it has been well known that the Saemaul Undong had a direct relation with the water resources development during 1970’s, its contribution to the water resources and increased income in rural communities has not been thoroughly quantified so far. In order to assess the contribution of the Saemaul Undong in terms of rural water resources development, we investigated various historical data produced by the central and local governments in relation to water resources development. The results show the direct and indirect contribution of the Saemaul Undong to the water resources development in rural communities such as sewage works, water supply facilities, shared wells, and river works. The results also showed a positive relation between per-house income in rural communities and areas of irrigated paddies, which were rapidly increased during 1970’s. These results can be utilized to transplant the positive aspect of the Saemaul Undong to developing countries focusing on water resources development in rural areas.
        4,000원
        9.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For evaluating the boar semen quality, sperm motility is an important parameter because the movement of sperm indicates active metabolism, membrane integrity and fertilizing capacity. Phospholipase C zeta (PLCz) is important enzyme in spermatogenesis, but the effect has not been confirmed in pigs yet. Therefore, this study was aimed to analyze their association with sperm motility and kinematic characteristics. DNA samples from 124 Duroc pigs with records of sperm motility and kinematic characteristics [total motile spermatozoa (MOT), curvilinear velocity (VCL), straight-line velocity (VSL), the ratio between VSL and VCL (LIN), amplitude of lateral head displacement (ALH)] were subjected. A SNP in non-coding region of PLCz g.158 A > C was associated with MOT (p < 0.05), VCL (p < 0.01), LIN (p < 0.01) and ALH (p < 0.05) in Duroc population. Therefore, we suggest that the intron region of the porcine PLCz gene may be used as a molecular marker for Duroc boar semen quality, although its functional effect was not defined yet. Whether the association is due to the candidate gene or not require further verification. Thus, it will be of interest to continue association studies in the regions surrounding those genes.
        4,000원
        10.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        For evaluating the boar semen quality, sperm motility (MOT) is an important parameter because the movement of spermatozoa indicates active metabolism, membrane integrity and fertilizing capacity. Estrogen receptors 2(ESR2) is involved in estrogen related apoptosis in cell cycle spermatogenesis, but their functions have not been confirmed in pig until now. Therefore, this study was conducted to analyze their association with sperm motility and kinematic characteristics. DNA samples from 105 Duroc pigs with records of semen motility and kinematic characteristics [Total motile spermatozoa (MOT), Curvilinear velocity(VCL), Straight-line velocity(VSL), the ratio between VSL and VCL(LIN), Amplitude of Lateral Head displacement(ALH)] were analyzed. A SNP in coding region of ESR2 g.35547A > G in exon 5 was associated with MOT (p < 0.05) in Duroc population. Therefore, we suggest that the porcine ESR2 gene may be used as a molecular marker for Duroc boar semen quality, although its functional effects were not defined yet. These results might shed new light on the roles of ESR2 in spermatogenesis as candidate gene for boar fertility, but still the lack of association across populations should be considered.
        4,000원
        11.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cluster-of-differentiation antigen 9 (CD9) gene expressed in the male germ line stem cells is crucial for sperm–egg fusion, and was therefore selected as a candidate gene to investigate Duroc boar semen motility and kinematic characteristics. This study was performed to investigatetheir association with semen motility and kinematic characteristics. DNA samples from 96 Duroc pigs with records of sperm motility and kinematic characteristics [Total motile spermatozoa (MOT, 82.27±5.58), Curvilinear velocity(VCL, 68.37±14.58), Straight-line velocity(VSL, 29.06±6.58), the ratio between VSL and VCL(LIN, 47.36±8.42), Amplitude of Lateral Head displacement(ALH, 2.88±0.70)] were used in present study. A single nucleotide polymorphism (g.358A>T) in intron 6 was associated with MOT, VCL, VAP and ALH in Duroc population (p<0.05). Therefore, we suggest that the porcine CD9 may be used as a molecular marker for Duroc boar semen quality, although its functional effect was not clear yet. These results will improve the understanding of the functions of the CD9 in spermatogenesis within the reproductive tracts, and will shed light on CD9 as a candidate gene in the selection of good sperm quality boars.
        4,000원
        12.
        2016.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Value of excellent breeding animals is important in livestock industry, but their economic life time is limited. And, many countries have been trying procuration of genetic resource in good animals. Therefore, this study was conducted to determine embryo production and to test efficiency of embryo transfer via non-surgical artificial insemination (AI) in different breed of superior sows. A total of 17 sows were used in this experiment (Duroc, n=10; Landrace, n=4; Yorkshire, n=3). The sows were artificially inseminated by semen of same breed boars. After 4 or 5 days following the AI, the embryos were obtained from the sows and then transferred to Landrace and Yorkshire recipients (n=3, respectively) by non-surgical method. The corpora lutea tended to be increased in Yorkshire and Landrace than Duroc(28 and 26 vs. 17, respectively). The recovery of embryo was 78.8% in Landrace, 65.4% in Duroc and 51.4% in Yorkshire. Duroc showed lower morulaes and early blastocyst embryos than 2, 4 ,8 and 16 cell. The morula in Yorkshire was higher (P<0.05) than that of Duroc (4.7 vs. 3.4). Similarly, the morulaes and early blastocyst embryos presented greater (P<0.05) in Landrace compared with other breed sows. The recipient sows were pregnant in a Landrace only. This reason may be due to little embryos inserted in the recipients. In addition, pregnancy results were limited because of the little sows. In conclusion, ovulated ovum in sows can be affected by different breed. Also, further study needed pregnant test by using the many embryo in each breed.
        4,000원
        13.
        2014.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Immobilization of anaerobic ammonium oxidizing bacteria has been studied to enhance the biomass retention of the slowly growing bacteria and the process stability. The purpose of this study was to compare the nitrogen removal efficiency of granular and immobilized anammox bacteria with poly vinyl alcohol and alginate. The specific anammox activity of the granular, homoginized and immobilized anammox bacteria were 0.016±0.0002 gN/gVSS/d, 0.011±0.001 gN/gVSS/d and 0.007±0.0005 gN/gVSS/d, respectively. Although the activity decreased to 43.7 % of the original one due to low pH and O2 exposure during the homogination and the immobilization, it was rapidly recovered within 7 days in the following continuous culture. When synthetic T-N concentrations of 100, 200, 400, 800 mg/L were fed, the immobilized anammox bacteria showed higher nitrogen removal efficiencies at all operational conditions than those of granular anammox bacteria. When the sludge retention time was shorten below 30.7 days and the reject water was fed, the nitrite removal efficiency of the granular anammox bacteria dropped to 8 % of the initial value, while that of the immobilized anammox bacteria was maintained over 95 % of the initial one. The immobilization with poly vinyl alcohol and alginate would be a feasible method to improve the performance and stability of the anammox process.
        4,300원
        20.
        1999.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        A study was made on the fabrication of nanostructured Fe-Co powders by mechanical alloying and their magnetic properties. Microstrural development during the process of MA was inverstigated by means of X-ray diffraction, differential thermal analyzer, scanning electron microscopy and transmission electron microscopy. The magnetic properties of NS Fe-Co powders were evaluated through the measurements of the saturation magnetization as well as the coercivity . The average grain size calculated from line braodening in XRD peak was about 10nm or less and confirmed by TEM. In this experiment, two different milling methods (cycle opertion and conventional milling) were used. Cycle operation had an advantage over the conventional milling method in that more refined powders can be obtained. Solid state alloying of the components was confirmed from both the change of the saturation magnetization and the change of lattice parameter with Co contentration. Maxium was obtained at the composition of 30at.%Co. Relatively high coercivities of 10~150e were obtained for the compositions investigated, and this seems to be due to the high amount of internal strain introduced during milling.
        4,000원
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