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본 연구에서는 송배전 계통에서 변성기의 몰드 재료로서 널리 사용되고 있는 에폭시 수지를 시료로 하여 설정해 높은 배합비에 따라 5종으로 제작한 각 시편에 대해 절연 파괴 실험을 하였다. 절연파괴 데이터를 가지고 와이블 분포식을 이용하여 임의의 허용 파괴 확률에서의 허용인가 전계의 값을 추정하였으며 절연 안전성을 판단하기 위하여 경년 열화(經年劣化) 데이터의 통계 처리를 행한 결과 허용 파괴 확률을 0.1[%]로 하였을 때, 허용 인가 전계는 21.5[kV/mm] 이하가 되어야 함을 확인할 수 있었다. In this study, the dielectric breakdown of epoxy composites used for transformers was experimented and then its data were simulated by Weibull distribution probability. The more hardener increased the stronger breakdown strength at low temperature because of cross-linked density by the virtue of ester radical, and the breakdown strength of specimens with filler was lower than it of non-filler specimens because it is believed that the adding filler forms interface and charge is accumulated in it, therefore the molecular motility is raised, the electric field is concentrated, and the acceleration of electron and the growth of electron avalanche are early accomplished. From the analysis of Weibull distribution, it was confirmed that as the allowed breakdown probability was given by 0.1[%], the applied field value needed to be under 21.5[kV/mm].
영어논문 MnAPSO-34 and Mn-impregnated SAPO-34(Mn-SAPO-34) sample were prepared with various manganese contents and studied by electron spin resonance(ESR) and electron spin echo modulation(ESEM). Electron spin echo modulation analysis of 0.07mol % Mn(relative to p) in MnAPSO-34 with adsorbed D2O shows two deuteriums at 0.26 nm and two at 0.36 nm from Mn. This suggests that two waters hydrate an MnO4 configuration with a D-O bond orientation for the waters as expect for a negatively charged site at low manganese content (0.1 mol%), the ESR spectra of MnAPSO-34 and MnH-SAPO-34 exhibit the same parameters(g 2.01 and A 89 G), but the spectra obtained from MnAPSO-34 samples are better resolved. The decomposition temperature of as-synthesized MnAPSO-34 were in the range of 200 – 600 oC of the morpholine which is 12 oC higher than that in as-synthesized MnH-SAPO-34. Infrared spectra showed that the position of a band at 3450 cm-1 shifted about 15 cm-1 toward higher energy in MnAPSO-34 versus MnH-SAPO-34. The modulation depth of the two-pulse ESE of MnAPSO-34 with adsorbed D2O is deeper than that of MnH-SAPO-34 with adsorbed D2O. Three-pulse ESEM of MnAPSO-34 and MnH-SAPO-34 with adsorbed deuterium oxide shows that the local environments of manganese in the hydrated samples are different, suggesting that Mn(II) is framework substituted in MnAPSO-34 since it obviously occupies an extraframework position in MnH-SAPO-34.
Manganese-doped H-SAPO-34 samples were prepared by an ion-exchanged reaction between H-SAPO-34 and paramagnetic Mn(II) species in methanol media and characterized by ESR and Electron Spin-Echo Modulation(ESEM) studies. In the hydrated (W)MnH-SAPO-34 measured in water, the Mn(II) ion was octahedrally coordinated with four framework oxygens and two water molecules at a displaced site IV of the eight membered ring window in the ellipsoidal cavity, while the Mn(II) ion was octahedrally coordinated to three framework oxygens and three water molecules at a displaced site I’ of the six membered ring window in the ellipsoidal cavity in hydrated(M)MnH-SAPO-34 measured in methanol. The similar result was found in the experiments with methanol adsorbents except ethanol. 영어논문
비가츠키이론에 따르면, 놀이가 아동에게 주는 역할과 같이 시뮬레이션은 학습자의 발달을 위한 훌륭한 도구(tool)가 된다. 즉, 시뮬레이션은 학습자에게 사회에서 이용가능한 지식과 기능을 습득시킬 수 있고, 의사 결정을 위해 필요한 정보를 수집하고 이를 재구성하도록 유도할 수 있으며, 문제 해결 과정을 통해 잠재적 발달수준(potential development level)을 향상시킬 수 있다. 사회과에서의 의사결정력은 사회적 상황에 대한 올바른 이해와 문제 파악이 전제되어야 하는데, 시뮬레이션은 학습자에게 사회적 상황을 체험할 수 있는 기회를 제공한다. 그러므로, 사회과 교수-학습에서 시뮬레이션의 역할은 학습자가 보다 진전된 다른 상황이나 실제상황에 직면했을 때, 그 상황에서 발생하는 문제를 해결할 수 있는 의사결정력을 향상시키는 '받침대(scaffold)'로써 기능하게 된다. 비가츠키이론을 바탕으로 시뮬레이션프로그램의 개발 방향을 제시하면 다음과 같다. 첫째, 제시하는 개념과 상황은 학습자의 잠재적 발달수준에 상응하여 다른 난이도를 가지고 단계적으로 제공되어야 한다. 둘째, 제시한 문제를 해결하는 과정에서 협동학습을 통해 타자와의 상호작용이 이루어지도록 대화식으로 설계해야 한다. 셋째, 시각적 화상들을 다양하게 제시하고 의사결정 사례들의 획일적이 되지 않도록 제공해야 한다. 넷째, 학습자의 의사결정력을 평가하는 수행평가과정이 포함되도록 제작해야 한다. According to Vygotsky's theory, simulation is an effective tool on learners, just as the role of play in childhood. That is to say, simulation can help learners acquire some useful knowledge and skills in society, and promote learner to collect and reconstruct informations for decision making, and raise the potential development level. Decision making ability in social studies is premised on proper understanding problems in social context, and simulation gives learners an opportunity of undergoing social situation. Therefore, simulation in social studies education, when learners are faced with more advanced situation or actual one, is functioned as a scaffold for decision making to solve some problems in the situation. Based on Vygotskian theory, several suggestions could be made in programming simulation. First, simulation program can give learners, different levels of concepts and situations corresponding to learner's potential development level. Second, simulation program must be designed dialogically for the cooperation learning, in which interactions are made with others during the decision making process to solve problems. Third, simulation program can suggest various visual displays and examples of decision making. Fourth, simulation program must include the performance assessment procedure which evaluates learner's decision making ability.
Sertoli-Leydig cell tumor는 드문 성색간질성 종양으로 양측성의 소견은 1% 미만으로 드물고 low grade malignancy에 속한다. 재발은 드물다고 알려져 있는데, 2/3가 초기 치료 후 1년 이내에 발생되고 복강내부와 후복막 림프절이 재발의 호발부위이다. 조직학적 분화도가 나쁘고 retiform pattern과 tumor rupture인 경우 악성화의빈도가 높다고 알려져 있다. 치료는 젊은 여성의 경우 병기 I일 때에는 자궁과 임신기능을 보존하는 편측 난소난관절제술을 시행한다. 1기보다 높은 병기일 경우 전자궁적출술 및 양측난소난관절제술, 골반림프절 곽청술을 시행하고 항암화학요법을 시행하기도 한다. 저자 등은 악성전이를 한 양측성 Sertoli-Leydig cell tumor를 경험하였기에 간단한 문헌 고찰과 함께 보고하는 바이다. The Sertoli-Leydig cell tumor is a rare sex cord stromal tumor that has low grade malignancy and low bilateral occurrence rate. About two third of recurrence appears within 1 year after the initial treatment and most common recurrence sites are intraperitoneal cavity and retroperitoneal lymph nodes. The frequency of malignant transformation is high in the poor differentiated cell type, retiform pattern, and tumor rupture. In young women with stage I, unilateral salpingo-oophorectomy is performed to preserve uterus and reproductive function. In more advanced stages, hysterectomy, bilateral salpingo-oophorectomy, and pelvic lymph node dissection are performed and occasionally chemotherapy can be combined. We experienced a rare case of malignant metastasis in Sertoli-Leydig cell tumor, and presented with a brief review of literature.
On a newly reclamed soil an experiment was carried out to find out the proper measure of amount of phosphorus fertilizer and application method for improved of yield in Honam area. Results are summarized as follows; 1. The yield was high in whole layer placement of phosphorus fertilizer and low in deep placement in application methods. 2. In the amount of phosphorus fertilizer, broadcasting with 15% of phosphate fixation coefficient, whole layer and deep placement of fertilizer with 10% of phosphate fixation coefficient were maximum yield respectively. 3. In a large quantity of application phosphate, stem diameter of soybean was thicker and blanch and pod number were increase more than the another plot. 4. Application of phosphorus fertilizer 9 ppm of phosphate before experiment become 48 to 123 ppm after and contents of base inclined high. 5. In plant analysis, there was positive correlation between the yield of soybean and the content of phosphate in plant, and a large quantity of phosphate will be absorbed into the plant and utilized it at generative growth after blooming stage.
For the increase of soybean yield in newly reclaimed area, this experiment was carried out in Kimje (plain area) and Jinan (hilly area) to determine the effect of nitrogen topdressing on agronomic characters. grain yields, protein and oil contents of soybean in 1982~1983. The results obtained were summarized as follows; 1. During growing period, average mean temperatures were similar, but amounts of rainfall and sunshine hours were smaller in Jinan than in Kirn je. 2. Applications of sufficient amounts of phosphates and lime increased available P20S and exchangeable Ca contents on both soils to optimum levels within one year after reclamation. 3. Days required for flowering (days from sowing to flowering) were shortened as sowing dates were later. 4. Nitrogen topdressing at flowering shortened the length of branches, but increased number of branches per plant, thus preventing over-thriving and lodging as compared with basal fertilization. 5. Nitrogen topdressing at flowering increased number of pods per plant and weight of 100 seeds. 6. Significant positive correlation were observed between grain yield and stem length, number of branches per plant, number of pods per plant, and weight of dry matter. 7. A significant negative correlation was obtained between grain yield without topdressing and yield increasing index by topdressing. The result indicates that nitrigen topdressing may be very effective practice III newly reclaimed area. 8. Soybean seeds produed in Jinan had higher protein contents than there of in Kimje. Higher protein contents in grains were noted with nitr ogen topdressing than without topdressing (only basal fertilization). Tendency of oil content was just opposite to above results of protein content. The protein content was significantly negative correlates with oil contents, regardless of area and varieties. 9. Total nitrogen content by Danyeobkong(medium type) plants was increased continuously until maturing stage, but that by Kwangkyo (limited type) plants showed the peak at 30 days after flowering. Total nitrogen content by plants at 30 days after flowering was significantly correlated with grain yield of soybeans. 10. The order of distribution ratio among plant parts in nitrogen content at maturing stage was mainstem < branch < pod < seed. The distribution ratio in seed was highest in the plants that receiving nitrogen topdressed at flowering. 11. Application of 8kg/l0a nitrogen as only basal fertilization inhibited formation of nodules in soybean roots, and nitrogen topdressing tended to decrease their sizes. 12. Topdressing of 4kg/10a nitrogen at flowering stage increased grain yields by 23-36% and 18-27% in Danyeobkong, and by 15-56% and 20-28% in Kwangkyo , III Kimje and Jinan respectively.
As the field of the application of the Internet of Things (IoT) expands, Low Power Wide Area Network (LPWAN) technologies are attracting attention. Among them, the research on Long Range (LoRa) that enables low energy consumption and long distance communication in the ISM band is actively being conducted. The frame loss and collision occur during the frame transmission in the LoRa network and the Adaptive Data Rate (ADR) mechanism is used in the LoRaWAN to resolve this problem. The ADR mechanism is a method of allocating transmission parameters to each node in consideration of the network conditions. However, the existing ADR mechanism has limitations in terms of energy consumption and frame delivery rate in the specific environments. In this paper, we propose an ADR mechanism to properly distribute transmission parameters in consideration of the energy consumption and frame delivery rate. In various simulation environments, the experiments of the proposed ADR mechanism are conducted. Through these experiments, it shows the performance and characteristics of the proposed mechanism in terms of frame delivery rate and energy efficiency. 사물인터넷의 활용 분야가 확장됨에 따라서 저전력 장거리 통신 기술인 Low Power Wide Area Network(LPWAN) 기술이 관심을 받고 있다. 그중에서도 ISM 밴드에서 적은 에너지 소모와 장거리 통신이 가능한 Long Range(LoRa)에 대한 연구가 활발히 진행 중이다. LoRa 네트워크에서 프레임 전송 중 프레임 손실과 충돌이 발생하며 이를 위하여 LoRaWAN에서 Adaptive Data Rate(ADR) 메커니즘을 사용하고 있다. ADR 메커니즘은 네트워크 상황을 고려하여 각 노드에 전송 파라미터를 할당하는 방법이다. 하지만 기존의 ADR 메커니즘은 에너지 소모와 특정 환경에서의 전송률 측면에서 한계점을 보여준다. 본 논문에서는 에너지 소모와 전송률을 고려한 ADR 메커니즘을 제안한다. 제안하는 ADR 메커니즘에 대한 실험은 다양한 시뮬레이션 환경에서 진행된다. 이를 통해 제안하는 ADR 메커니즘의 전송률과 에너지 효율성에 대한 성능과 특징을 보여준다.