• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2011년도 제40회 동계학술대회 초록집
• /
• pp.59-59
• /
• 2011

We will report atomically sharp epitaxial growth of $Bi_2Se_3$ three-dimensional topological insulator films on Si(111) substrate with molecular beam epitaxy (MBE). It was achieved by employing two step growth temperatures to prevent any formation of second phase, like as $SiSe_2$ clusters, between $Bi_2Se_3$ and Si substrate at the early stage of growth. The growth rate was determined completely by Bi flux and the Bi:Se flux ratio was kept ~1:15. The second-phase-free atomically sharp interface was verified by RHEED, TEM and XRD. Based on the RHEED analysis, the lattice constant of $Bi_2Se_3$ relaxed to its bulk value during the first quintuple layer implying the absence of strain from the substrate. Single-crystalline XRD peaks of $Bi_2Se_3$ were observed in films as thin as 4 QL. TEM shows full epitaxial structure of $Bi_2Se_3$ film down to the first quintuple layer without any second phases. This growth method was used to grow high quality epitaxial $Bi_2Se_3$ films from 3 QL to 3600 QL. The magneto-transport properties of these thin films show a robust 2D surface state which is thickness independent.

• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
• /
• pp.332-332
• /
• 2012

분자선 에피탁시(molecular beam epitaxy)를 이용하여 GaAs 기판에 성장한 InAs 양자점(QDs: quantum dots)은 성장 온도, 압력, As/In의 공급비 등의 성장 조건에 따라 다른 변수(parameter)를 갖는다. 따라서 성장변수에 따라 양자점의 모양과 크기, 밀도가 달라져 균일한 양자점 형성에 어려움이 있어 많은 연구가 진행되고 있다. 예를 들면 In-interruption 법으로 성장한 양자점의 특성이 S-K mode (Stranski-Krastanov mode)로 성장한 양자점에 비해 광학적 특성이 향상되었다. 본 연구에서는 In pre-deposition (IPD) 법으로 성장한 InAs/GaAs 양자점의 광학적 특성을 PL(photoluminescence)와 TRPL (time-resolved PL)을 이용하여 분석하였다. InAs QDs 시료들은 In과 As 공급시간을 각각 1초와 19초 (QD1), 2초와 18초 (QD2), 3초와 17초 (QD3)로 조절하여 성장하였으며, In이 공급되는 시간 동안 As shutter를 차단하여 As 공급을 중단하였다. In과 As의 차단 없이 S-K mode로 성장한 시료를 기준시료로 사용하였다 (QD0). AFM (atomic force microscope) 측정결과, In 공급시간이 1초에서 2초로 증가할 때, 양자점의 밀도와 종횡비(aspect ratio)가 증가하였고, 양자점의 균일도가 증가하였다. 그러나 QD3 시료는 QD1 시료에 비해 밀도와 종횡비, 균일도가 감소하였다. 10 K에서 PL 피크는 In 공급 시간이 증가할 때, 970 nm에서 1020 nm로 적색편이 하였고 반치폭 (FWHM: full width at half maximum)은 75 meV에서 85 meV로 증가하였다. QD2 시료의 PL 피크 에너지가 가장 낮았고, 가장 강한 PL 세기를 보였다. IPD 시간이 증가함에 따라 PL 피크에서 측정한 PL 소멸은 점차 빨라졌다. IPD 기법으로 성장한 양자점의 빠른 PL 소멸은 양자점 밀도와 종횡비 향상에 의한 파동함수 중첩의 증가와 구속 에너지 증가에 의한 것으로 설명된다.

• Journal of the military operations research society of Korea
• /
• 제33권2호
• /
• pp.75-86
• /
• 2007

This paper presents the overall valuation framework of the Army Tactical Command Information System(ATCIS) with its empirical data which is developed by the ROK Army in 2005 with its own R&D efforts over the past 10 years. The valuation with the appropriate methods is conducted through the full and relentless support of ROK Army HQs, defense agencies, and related firms. And the results include both qualitative and quantitative values of the ATCIS in perspectives of economic, technical, and defense strength effects. As a result, the development of ATCIS is valued over 1.7291 trillion Won which is over 6.55 times benefit and cost ratio comparing with other country's similar system. The worth of this paper includes the actual framework and methods to apply the valuation of other weapon systems and its preliminary research, defense offset valuation, performance evaluation and others.

• Transactions of the Korean Society of Automotive Engineers
• /
• 제17권3호
• /
• pp.74-80
• /
• 2009

The objective of this paper was to investigate the slip rate and the slip frequency number of damper clutch of torque converter in 2.4L passenger vehicle with 5-speed A/T and analyze the effect of slip control and control strategy on driving characteristics and the fuel economy. The newly developed torque converter with the more durable wet friction material and the slip-controlled damper clutch system, the DCC system, was installed, which was easily compatible and amendable of the lock-up clutch of the base system. The vehicle has been tested on the fuel economy modes such as FTP-75, HWFET and NEDC (ECE15+EUDC) driving cycle at chassis dynamometer. The DCC mode (II), of which the control strategy had both the lock-up and the slip-controlled clutch, and the DCC mode (I) with full slip-controlled clutch were compared with the base system with only the lock-up clutch. As the research result, comparison to base system, the fuel consumption of the vehicle with the DCC control (II) was effectively improved by 6.6% and 7.7% on FTP-75 and NEDC mode.

• Environmental and Resource Economics Review
• /
• 제24권1호
• /
• pp.85-107
• /
• 2015

This study analyzes the effect of applying hyperbolic social discount rate onto the results of benefit-cost analysis of environmental public investment projects in Korea. In order to check the application possibility to the actual feasibility study, the discount factors generated by hyperbolic function, rather than traditional exponential one, would be applied to the benefit and cost data from the pre-feasibility studies which peformed for environmental public investment projects. The results of this study shows that using hyperbolic social discount rate is effective for enhancing test results, only under the condition of which the full expansion of the time periods of analysis is satisfied. According to the simulation results of this study, to achieve higher benefit/cost ratio by using hyperbolic social discount rate, the period should be increased up to 120 to 150 years at least.

• Journal of Korean Home Economics Education Association
• /
• 제10권2호
• /
• pp.87-99
• /
• 1998

The purposes of the study are to see as to how much of changes has occurred in the newly revised high school Home Economics Textbooks required by the 6th Curriculum and to seek future policy directions which can be improved even better, if any, for further revision. To implement this proposal, the study employs 6 different textbooks published in 1996 geared for the 6th Curriculum for data base. The components of the contents divides into two major parts. The first part faUs into a category of holistic analysis of the textbooks, which gives a general perspective of the changes in the textbook revised. It includes those areas of changes in the total number of pacover page, illustrations, table of contents, appendices, unit cover, introductory remarks, summary and evaluation, etc. It also covers the information on authors of textbook. The latter part consists of several specific areas of major changes occurred in the textbooks for the 6th Curriculum. It covers such areas of changes in the composition of category and its weigh laboratory experiences, and illustrations and tables. To conclude the study, there found followings key features : 1) The new textbooks have adopted more of varieties in physical appearances and contents per se as to the older ones. And yet, there still found a weakness in numbers of authors participated to a full reflection of contents variety. In addition, the background of authors reflected on an unrealistic idealism which lacks the on-site information provided by the school teachers. 2) The content area consists of 3 major areas of Human Development & Family Relationship. Food and Nutrition. Clothing and Textiles with ratio of 23.8%, 23.1%, and 21.9% respectively. 3) Human Development & Family Relationship area ranked first with 71 times in the numbers of laboratory activities for each content area. followed by Food and Nutrition with 56 and Family Resorces & Consumerism with 54. These increased numbers of laboratory activities in textbooks represent the changing contents of Home Economics and imply the desirable and positive directions of Home Economics education in Korea. numbers of laboratory activities for each content area. followed by Food and Nutrition with 56 and Family Resorces & Consumerism with 54. These increased numbers of laboratory activities in textbooks represent the changing contents of Home Economics and imply the desirable and positive directions of Home Economics education in Korea.

• Reproductive and Developmental Biology
• /
• 제36권2호
• /
• pp.133-139
• /
• 2012

This study aims to examine the effect of Genetically Modified ${\beta}$-Carotene Biofortified Rice rice developed by simultaneous expression technology in NAAS on biological immunity. Accordingly, this study added Genetically Modified ${\beta}$-Carotene Biofortified Rice 25, 50% and general rice 50% as control group into diet and provided rats with the prescribed feeds and then measured the contents of immunoglobulin and cytokine in blood. As a result, male and female IgM, IgE, male IgG1, female IgG2a and TNF-a, IL5 and IL12 showed no significant difference; male IgG2a tended to decrease dependently on the combined concentration of Genetically Modified ${\beta}$-Carotene Biofortified Rice; female IgG1 showed significance with control group, but its association with diet was not found. The higher the dietary mixing ratio, the more the male and female IFN-a and female IL-4 contents, regardless of rice variety, and it was found that female IL6 content decreased significantly, but its association with diet was not found. The risk of beta carotene-enriched rice into environment and human body has not been reported yet. The digestion of Genetically Modified ${\beta}$-Carotene Biofortified Rice can be seen as "safe" as this test result showed no big difference between general rice and Genetically Modified ${\beta}$-Carotene Biofortified Rice, and its usability is full of suggestions.

• Horticultural Science & Technology
• /
• 제32권5호
• /
• pp.584-589
• /
• 2014

Jeffersonia dubia is a spring-flowering perennial found in rich forests in Korea and Northern China and has potential as an ornamental or medicinal plant. However, illegal picking and land use change have decreased the number of populations and overall population size of this plant in its natural habitat. Although J. dubia has been reported to be a shade-preferring plant, no study has determined the optimum light intensity for its growth. The objectives of this work were to observe the effects of various shading levels on the physiological responses of J. dubia and to determine the proper shading level for cultivation. Treatments consisted of four shading levels (0%, 50%, 75%, and 95% shade) imposed using black mesh cloth. The number of leaves and dry weight increased with decreased shading. The shoot-to-root ratio increased with increased shading, mainly due to decreased root dry weight under shading. Plants showed low net $CO_2$ assimilation rates and $F_v/F_m$ values combined with low dry matter levels when grown under 0% shade (full sunlight). These results indicate that J. dubia plants experience excessive irradiance without shading, resulting in damage to the photosynthetic apparatus. By contrast, the net photosynthesis rate increased as the shading level increased. $F_v/F_m$, the potential efficiency of PSII, was 0.8 under 95% shade, indicating that J. dubia is well-adapted under heavy shading. However, the low dry matter of plants in the 95% shade treatment indicated that the low light intensity under 95% shade led to a decline in plant growth. Thus, moderate light (50% shading) is recommended for cultivating J. dubia without physiological defects.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제12권9호
• /
• pp.4103-4121
• /
• 2018

Quality of Service (QoS) awareness is recognized as a key point for the success of Internet of Things (IOT).Realizing the full potential of the Internet of Things requires, a real-time task scheduling algorithm must be designed to meet the QoS need. In order to schedule tasks with diverse QoS requirements in cloud environment efficiently, we propose a task scheduling strategy based on dynamic priority and load balancing (DPLB) in this paper. The dynamic priority consisted of task value density and the urgency of the task execution, the priority is increased over time to insure that each task can be implemented in time. The scheduling decision variable is composed of time attractiveness considered earliest completion time (ECT) and load brightness considered load status information which by obtain from each virtual machine by topic-based publish/subscribe mechanism. Then sorting tasks by priority and first schedule the task with highest priority to the virtual machine in feasible VMs group which satisfy the QoS requirements of task with maximal. Finally, after this patch tasks are scheduled over, the task migration manager will start work to reduce the load balancing degree.The experimental results show that, compared with the Min-Min, Max-Min, WRR, GAs, and HBB-LB algorithm, the DPLB is more effective, it reduces the Makespan, balances the load of VMs, augments the success completed ratio of tasks before deadline and raises the profit of cloud service per second.

• Journal of the Korean Society of Food Culture
• /
• 제4권2호
• /
• pp.145-153
• /
• 1989

Of 1,244 junior high school students of boys and girls and their families in Tokyo and Seoul, we investigated the present situations of the participation in cooking and table manners. In both countries, the average age of parents was 40's, and the ratio of the kinds of fathers' job was similar including 75% of full-time salaried workers, while that of mothers' in Japan was 63%, in Korea 23%. The male participation in cooking in both countries was found in younger generations and that of fathers and boys in Korea was significantly fewer than in Japan, which is regarded as the influence of Confucianism and employment of housekeepers. The figure of frequency of supper taken together daily was 27% in Japan and 54% in Korea where they didn't begin eating until all families gathered or the elders began. In Japan the civilities before and after meals were so often customarily expressed and they had the regular order of seats. The figure of frequency of taking meals with TV watching was about 45% in Japan of breakfast and supper and more than 30% in Korea of supper. As for the participation in cooking and table manners, national characteristics were clearly found out. In both countries, the newly modernized and democratized style of dietary behaviors was being made, rather sooner in Japan, out of the specific East-Asian traditional dining culture.