Effect of sintering temperature on nonlinearity and surge degradation characteristics of Mn3O4/ Nb2O5/Er2O3‑doped ZnO–V2O5‑based varistors

Choon‑W. Nahm 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.1

This study elucidates the effect of sintering temperature on the nonlinearity and surge degradation characteristics of Mn3O4/ Nb2O5/Er2O3–doped ZnO–V2O5-based varistors. With increasing sintering temperature, the average grain size increased from 6.3 to 16.6 μm and the ceramic density decreased from 5.51 to 5.41 g/cm3. The highest nonlinearity (α1 = 45.6) was obtained when the sintering temperature reached 900 °C. The sample sintered at 900 °C exhibited the best clamp characteristics, where the clamp voltage ratio was 1.84–2.44 at a surge current of 1–25 A. By contrast, the sample sintered at 925 °C exhibited the highest electrical stability, where ΔE 1 mA/cm2E 1 mA/cm2 = −10.6% , Δ1∕1 = −37.2% and ΔJL/JL = 10.2% after applying a surge current of 200 A.

The Composition and Productivity of a Grassland in Korea

Kim, Choon M.,Lee, Il K.,Park, Bong k.,Chang, Nam K. 서울대학교 교육대학원 1969 論文集 - 서울대학교 교육대학원 Vol.6 No.-

The vascular florae of the north, northwest and south sides of a stand in the piedmont on the Choon-sung area were composed of 50, 41, and 34 species respectively. The most important of these were Arundinella hirta and Miscanthus sinensis. These two species contributed greatly to the standing crop of live material, which was in excess of 308.66g/m² during the growing season. The peak net productions of organic matter of 61.53g/m, 231.40g/m², and 214.65g/m² for these grasslands were reached in July-August under abundant water conditions, and were largely due to the high productivity of the dominant species such as A. hirta and M. sinensis. The average standing crop of this grassland plant communities was in excess of 571.01g/m² for the one growing season. This value would be increased if the productivity of the moss and algal mats which cover the soil surface during the growing season were included.

동학가사에 나타난 근대의식과 남녀평등

류해춘(Ryoo, Hae-Choon) 한국어문학회 2018 語文學 Vol.0 No.140

The Donghak-Gasa provides a rationale for reforming and overcoming the feudal system in order to achieve the task of establishing a new nation state and building a modern nation based on nationalism and popularism. Donghak ideology was not rejecting and opposing Western studies unconditionally, but instead acknowledging the modernity and universality of the West. Rather than accepting the modernity and universality of the West, Donghak-Gasa has tried to overcome the imperialist and invasive character of Western ideals and to create a dynamic Donghak ideology better suited to Korean history and tradition. In the history of Donghak, citizen equality is key. The equality ideology that is claimed in the world of religion becomes a new hope from the ordinary person’s perspective. People have the belief and philosophy that they can emerge as an active member in a new era of the coming future. The ideology of Donghak-Gasa gave women who were oppressed in the late 19th century feudal society almost the same human rights as men. In 1894, the Donghak Peasant Movement succeeded in the idea of “Yongdam-Yusa” and developed the human rights of women. Modern consciousness and ideology of gender equality embodied through the lyrics of the 19th century Donghak-Gasa became the driving force of the Donghak Peasant Movement. That force to break the feudal society and, after liberation the Republic of Korea retained the basic spirit of the democratic state which holds true even today.

북한체제의 군부 핵심요직 변화

이성춘(Lee, Sung?choon) 한국공공사회학회 2017 공공사회연구 Vol.7 No.2

인터넷뱅킹의 수용태도에 대한 영향요인에 관한 연구 : 거래빈도와 거래금액의 조절효과를 중심으로 Focusing on the Moderating Effect of Financial Transaction Frequencies and Amount

노춘섭,신정신,이유춘 한국정보전략학회 2002 한국정보전략학회지 Vol.5 No.1

Internet banking has been adopted by many bank clients and forecasted as the most preferred means of financial transactions in the coming years. The study identifies, through the extensive literature review, the factors that influence the adoption of internet banking, and proposes a research model based on the theory of reasoned action. It tests each path of the model with the data gathered from 301 bank clients. The study finds that factors such as spatial convenience, availability of various information, cost saving needs, safety and innovativeness influence the adoption attitude for internet banking. It also identifies bank transaction frequencies and amount moderate several influencing factors' effect on the adoption attitude. In addition, the study confirms the effect of the adoption attitude on the adoption behavior of internet banking.

林土의 有機物의 分解速度와 無機養料의 垂直分布에 關한 考察

金遵敏,張楠基,鄭玩鎬 서울대학교 교육대학원 학술연구회 1966 論文集 - 서울대학교 교육대학원 Vol.3 No.-

Kim Choon Min, Chang Nam Kee and Chung Whan Ho: Decomposition rate of plant residue and the vertical distibution of mineral nutrients in the woodland soil. The relationship between decomposition rate of litter and the amount of mineral nutrients dispersed to the soil horizons were studied on the oak and pine forest stand. The results are as follows: 1. Decomposition rate of litter was highest in the F horizon of the oak stand, however in the pine stand it was highest in H horizon. 2. The correlation coefficients between decomposition rate and humus, organic carbon, moisture content, calcium, phosphorus, and nitrogen in the pine stand are; 0.90, 0.98, 0.76, 0.98, and 0.88, in oak stand; 0.97, 0.93, 0.92, 0.97, 0.74 and 0.73. 3. Factors which affect the decomposition rate of litter are humus, organic carbon, moisture content, calcium, phosphorus and nitrogen. 4. Among the variables, PH, moisture content and phosphorus under the oak and pine forest showed significant differences in each horizon. 5. C/N ratio of pine stands is higher than that of oak stands studied. 6. The vertical distribution of mineral nutrients is highly related with the amount of humus accumulated on top soil.

Voxel머리팬텀 제작 및 붕소중성자포획요법 선량계산에의 응용

이춘식,이춘익,이재기 대한방사선 방어학회 2001 방사선방어학회지 Vol.26 No.2

해부학적으로 단순한 수학적인형팬텀의 한계를 극복하기 위한 voxel머리팬텀을 제작하고 BNCT(Boron Neutron Capture Therapy) 시행 시 선량분포를 계산하였다. 일반목적 몬테칼로 코드인 MCNP4B의 반복구조 알고리즘을 이용하여 voxel몬테칼로 계산체계를 수립하였고 두 가지 물질로 구성된 예시적 voxel팬텀과 기하체조합팬텀의 계산값 비교를 통해 계산체계를 검증하였다. 미국 NLM(National Library of Medicine)에서 제공하는 VHP man 인체단층사진에 대한 분할 및 색인작업을 통해 voxel머리팬텀을 제작하여 AP 및 PA 방향에서 입사하는 넓고 평행한 광자 및 중성자빔에 대한 선량값을 MIRD팬텀의 계산값과 비교한 결과 중성자빔 AP방향조사 시 MIRD팬텀에서는 볼 수 없는 안구로 인한 중성자 감쇠현상을 확인할 수 있었다. 3차원 정밀계산이 필요한 BNCT 시술시 선량분포계산을 위해 뇌 중앙에 직경 5cm의 구형 뇌종양 체적을 정의하고 뇌와 종양의 붕소 함량을 조정하여 10keV 및 40keV 상부입사 중성자에 의한 장기별 흡수선량을 계산한 결과 종양에 30㎍/g, 정상세포에 3㎍/g 의 붕소를 주입한 경우 붕소함량이 없을 때에 비해 2배 가량 큰 선량을 보였다. 본 연구를 통해 voxel몬테칼로기법을 이용한 선량평가체계를 수립하였고 정밀한 선량계산을 필요로 하는 치료방사선분야 선량계산에 실제 인체에 가까운 voxel팬텀의 응용가능성을 제시하였다. Voxel head phantom for overcoming the limitation of mathematical phantom in depicting anatomical details was constructed and example dose calculation for BNCT was performed. The repeated structure algorithm of the general purpose Monte Carlo code, MCNP4B was applied for voxel Monte Carlo calculation. Simple binary voxel phantom and combinatorial geometry phantom composed of two materials were constructed for validating the voxel Monte Carlo calculation system. The tomographic images of VHP man provided by NLM(National Library of Medicine) were segmented and indexed to construct voxel head phantom. Comparison of doses for broad parallel gamma and neutron beams in AP and PA directions showed decrease of brain dose due to the attenuation of neutron in eye balls in case of voxel head phantom. The spherical tumor volume with diameter, 5cm was defined in the center of brain for BNCT dose calculation for downward neutron beam of 10keV and 40keV, the tumor dose is about doubled when boron concentration ratio between the tumor to the normal tissue is 30㎍/g to 3㎍/g. This study established the voxel Monte Carlo calculation system and suggested the feasibility of precise dose calculation in therapeutic radiology.

頭鍼이 中風患者의 단기간 NIHSS와 MBI에 미치는 영향

류재춘,박인범,김상우,김철홍,서정철,윤현민,장경전,송춘호,안창범 동의대학교 한의학연구소 2002 동의한의연구 Vol.6 No.-

Objective ; The aim of this study was to investigate the effect of Scalp acupuncture on recovery of motor disorders in stroke patients. Methods ; Twenty two patients with poststroke-hemiplegia were randomized into two groups. Ten patients(test group) treated by 2 methods-Scalp acupuncture and body acupuncture. The other twelve patients(control group) treated only by body acupuncture. The activity of daily living was measured with a National Institutes of Health stroke scale(NIHSS) and Modified Barthel Index(MBI). The therapy was performed one a day for 2 weeks. Results ; In terms of score of NIHSS, the test group showed statistically meaningful decrease after 2 week treatment, but the control group showed statistically meaningful decrease after 1 week(p<0.05). And in terms of score of MBI, the test group did not show statistically meaningful increase but the control group showed statistically meaningful increase after 1 week(p<O.05). There was no statistically meaningful difference after 1 and 2 week treatment between the groups. Conclusions ; These results support that test group has almost same effectness compared with control group in improvement of the activity of daily living of poststroke-hemiplegic patients.

石灰 및 시멘트에 依한 安定處理土의 構造와 工學的 性質의 相關性에 關한 硏究

朴春洙,宋寅春 충남대학교 공업교육연구소 1984 論文集 Vol.7 No.1

Granite weathered soil(GS), Kaoline(KC), Quartz(Q) and Feldspar(F), namely, sample soils were experimented with physical and chemical way as well as lime and cement as stabilized materials in this study. Sample soils were stably treated, testing reaction and dynamics. While the for mation of generative minerals was analyzed by x-ray diffraction experiment, the variation of formation which has an effect on the revealing intensity of treated soil was tested with quantitative and qualitative analysis, thus, the above properties was studied.

最近 3年間 本敎室에서 經驗한 腫瘍 253例에 對한 臨床病理組織學的 考察

李揆鶴,高永春,李廷鎭,朴鍾雲,李鍾元,林鍾福,林春悅,朴順道 최신의학사 1964 最新醫學 Vol.7 No.4