• Current Industrial and Technological Trends in Aerospace
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• v.6 no.2
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• pp.109-115
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• 2008

There would be a long-waited launch of a Korean space launch vehicle(KSLV-I) in NARO Space Center which is located in Goheung, Jeol La Nam Do in Korea. Korea would be the nineth country in the world which could launch space launch vehicle itself. The launch of the 2nd technology satellite of 100kg with KSLV-I would give Korean hope and dream. In addition to the traditional space activities of U.S.A. and Russia, Japan launched the lunar satellite, Kaguya in 2007, China launched the lunar satellite, Change and succeeded in space walk and India launched the lunar satellite Chandrayaan in October, 2008. In this paper we study on the trend of domestic and international development of space launch vehicle considering all these space development activities.

• Korean Journal of Materials Research
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• v.13 no.6
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• pp.369-373
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• 2003

Magneto-optic Kerr Effect(MOKE), AFM and magnetoresistance measurements have been carried out on as-deposited and annealed Magnetic Tunnel Junctions(MTJs) with junction sizes 180, 250, 320 and 380 $\mu\textrm{m}$ in order to investigate the correlation among interlayer exchange coupling, surface roughness and junction size. Relatively irregular variations of coercivity $H_{c}$ (∼17.5 Oe) and interlayer exchange coupling $H_{E}$ (∼17.5 Oe) are observed over the junction in as-deposited sample prepared by DC magnetron sputtering. After annealing at $200^{\circ}C$, $H_{c}$ decreases to 15 Oe, while $H_{ E}$ increases to 20 Oe with smooth local variation. $H_{E}$ shows very good correlation with surface roughness across the junction in agreement with Neel's orange peel coupling. The increasing slope per $\mu\textrm{m}$ of normalized $H_{c}$ and $H_{E}$ are same near junction edge along free-layer direction irrespective of junction size, giving relatively uniform $H_{c}$ and $H_{ E}$ for wider junction size. Thickness profiles of the junctions measured with $\alpha$-step show increasingly flat top surface for larger junctions, indicating better uniformity for large. junctions in agreement with the normalized$ H_{c}$ and H$/_{E}$ curves. TMR ratios also increase with increasing junction size, indicating improvement for larger uniform junctions.

• Journal of the Korean Magnetics Society
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• v.8 no.3
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• pp.111-117
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• 1998

Recent discovery of colossal magnetoresistance (CMR) phenomena in perovskite manganese oxides has evoked great interest for its physical peculiarity and the possible industrial application. Besides manganese oxides, CMR phenomena is also observed in $Tl_2Mn_2O_7$ with pyrochlore structure and in Cr-based chalcogenide with spinel structure. In this paper, we have studied electronic structures of Cr-based chalcogenide spindles $Fe_{1-x}Cu_xCr_2S_4$ at x=0.0, 0.5, 1.0 using the linearized muffin-tin orbital (LMTO) band method within the local density approximation (LDA). The characteristic resistivity for x=0.0, 0.5 could be explained qualitatively in terms of the half-metalic electronic structure and the Jahn-Teller effect. Especially, the half-metallic nature appearing in the metallic temperature regime is well descibed by the proposed conduction model for x=0.0, 0.5, 1.0. We have suggested, based on the conduction model, that the CMR phenomena observed in these compounds are closely correlated with the obtained half-metallic electronic structure.

• KSBB Journal
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• v.8 no.3
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• pp.200-208
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• 1993

As a separation membrane for water-ethanol mixtures, alginic acid has been used which is hydrophilic polysaccharide and has excellent bonding capacity with divalent metal ions. Pervaporation characteristics of the alginic acid membrane were examined. The membrane was crosslinked with metal ions for the improvement of mechanical strength and chemical affinity. And its pervaporation characteristics were investigated. The first group(I A) metal complexed membrane cannot be used because of their brittleness and excessive swelling in low concentrations of ethanol solution. But the permeation characteristics of other metal complexed membrane were more improved than that of the alginic acid membrane because of their contraction of the membrane and hydrophilic property of metal ion.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.418-418
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• 2010

최근 친환경 저전력 차세대 조명소자로 발광다이오드가 각광을 받고 있다. 하지만 종래의 수평형 발광다이오드는 사파이어 기판의 열악한 열전도도 및 전기전도도 특성으로 인하여 효율적인 열방출의 저하가 생기게 되고, 양전극과 음전극의 수평배치에 기인한 심각한 전류쏠림현상 등이 수평형 발광다이오드의 고전력 소자로서의 응용에 걸림돌로 작용하고 있다. 근래에 수평형 발광다이오드의 대안 중 하나로 수직형 발광다이오드에 대한 연구가 활발히 진행되고 있다. 수직형 발광다이오드에서는, 수평형 발광다이오드에서의 전류쏠림현상을 향상시키기 위해 얀전극과 음전극을 수직으로 배치시킨다. 그리고 열전도도 및 전기전도도 특성이 떨어지는 사파이어를 제거하기 위해 LLO(Laser Lift Off)공정이 사용된다. LLO공정으로 인해 수직형 발광다이오드의 구조는 수평형 발광다이오드와 달리 n-GaN이 위로 배치되는 특성을 가진다. 본 연구에서는, 수직형 발광다이오드의 광추출 효율을 증가시키기 위해 SiO2 나노입자를 이용한 GaN 표면요철 형성기술을 개발, 적용 하였다. SiO2 나노입자를 n-GaN상에 단일층으로 분산시키기 위해 PR(PhotoResist), 나노입자, IPA(Isopropyl Alcohol)이 혼합된 용액을 스핀코팅시켰고 그 결과를 SEM으로 확인할 수 있었다. GaN 식각을 위해 SiO2 나노입자를 마스크로 사용하였고, BCl3가스를 사용한 건식식각을 진행하였다. 그 결과 조밀하고 균일한 크기의 Cylinderical Trapezoid 식각 형상이 n-GaN표면에 형성되었음을 SEM으로 확인할 수 있었다. 우리는 표면요철이 없는 발광다이오드와 SiO2 나노입자를 이용한 표면요철이 형성된 발광다이오드의 특성을 비교하였다. 그 결과 표면요철이 있을 때 광출력이 증가함을 확인할 수 있었다. 거기에 더하여 표면요철의 높이가 300nm~1000nm로 변화함에 따른 소자의 특성변화 또한 관찰할 수 있었다.

• Korean Journal of Community Nutrition
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• v.26 no.2
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• pp.93-102
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• 2021

Objectives: This study was conducted to investigate the relationship between watching mukbang (eating broadcasts) and dietary and health behavior in adults who watch mukbang. Methods: The questionnaire was administered on a self-written basis through online and offline formats to 800 adults (400 men and 400 women). The contents of the survey consisted of general characteristics, mukbang viewing time per week, breakfast intake frequency, preference for menus when viewing mukbang, delivery food intake frequency per week, late meal intake frequency per week, and health behavior. The subjects were divided into three groups according to mukbang viewing time. Results: The body weight of viewers was significantly higher when mukbang viewing time was over 14 hours for both men and women. In particular, based on the BMI (body mass index), those who watched mukbang for more than 14 hours were found to be overweight. People with more than 14 hours of mukbang viewing time per week were found to prefer mostly carbohydrate-rich food and meat, while those with less than 7 hours of mukbang viewing time per week showed a higher preference for vegetables and fruits. An analysis of the frequency of breakfast eaten showed that the rate of skipping breakfast was the highest for those who watched mukbang for more than 14 hours per week, and the rate of eating breakfast daily was the highest in the case of fewer than 7 hours of viewing. In the case of high mukbang viewing time per week, the frequency of food delivery and night eating was high. When mukbang viewing time was high, the viewer's interest in health was low and the frequency of exercising too was low. Conclusions: Viewers with high mukbang viewing time showed undesirable health and eating behavior. Thus, it is believed that proper nutrition education on improving eating habits and raising the awareness of correct eating habits is necessary for such viewers.

• Perspectives in Nursing Science
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• v.16 no.1
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• pp.1-11
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• 2019

Purpose: This study was conducted to identify the perceptions toward school forest programs related to forest welfare services in elementary schools and suggest strategies to activate new programs. Methods: A mixed method research was performed. Four teachers and one forest therapist participated in a focus group interview; 162 teachers answered a survey. Results: The teachers were aware of the effects of the forest program, but there were some barriers, including the question of whether there was an accessible forest, school forest management problems, the risk of teachers' work overload, and the lack of program diversification for elementary students. Solutions included the expansion of school forests and forest facilities available to students, development of a variety of programs, provision of appropriate information on available facilities, and cooperation with educational institutions for institutionalization and increased effectiveness of school-based forest utilization programs. In addition, a scientific basis for data accumulation is needed. Conclusion: The Ministry of Forestry is cooperating with the Ministry of Education and local education offices to activate a forest-use health promotion program for elementary school students. Additionally, to utilize the forests in regular education courses, teachers should strive to spread positive awareness of forests.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.205-219
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• 2021

The present study identified determinants to user acceptance of artificial intelligence(AI)-based news anchor. Our conceptual model included three constructs of ability, benevolence, and integrity to determine whether these three constructs are predictive of trust perceived from AI news anchor. This work further examined the influences of social presence, anthropomorphism, perceived usefulness, understanding as well as trust as immediate determinants to user acceptance. The conceptual model was validated on survey data collected from 513 respondents. A series of scale refinement process was conducted by the examination of data normality, common method bias, structure of latent variables as well as internal consistency. In addition, a confirmatory factor analysis was performed to assess the extent to which the sample data collected from survey study measures the constructs adequately. The results from the analysis of structural equation model indicated that, (1) two constructs of ability and integrity were found to be significantly predictive of perceived trust, and (2) anthropomorphism, perceived usefulness, and trust emerged as significant and positive predictors of user acceptance of AI-based news anchor.

• Journal of Marine Life Science
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• v.2 no.2
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• pp.56-61
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• 2017

This study examined the environmental characteristics of shore pollution sources in the southern part of the Sinan, Jangsando area in the West Coast of Korea. A shoreline survey of the watershed was conducted to identify the pollution sources and measure the water discharge rate and microbial hygiene of water and finally estimate the possible impact area of pollution. Forty five of pollution sources in total were identified and they were grouped into sewage (33), agriculture waste water (1) and waste water from inland fish farm (11). Nine among them were discharged into the seawater and discharge volume was 72,857~281,250 l/min. Fecal coliforms of St. 72 (sewage) and St. 74 (shrimp farm) were 490 MPN/100 ml and 49 MPN/100 ml and the impact zones of the pollution were 4,389 m and 1,900 m respectively.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.20-20
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• 2020

Eranthis stellata Maxim. is a perennial plant that grows around the valley. E. stellata is concerned about the decline in natural habitats due to climate change in KOREA, continues to be observed and protected as an endangered species (Least Concrned, LC). Nevertheless, studies on the characteristics of the seeds of E. stellata are insufficient. So, this study analyzed the morphological characteristics and dormancy types of seeds. Seeds of E. stellata was collected in April at Gyeongsangbuk-do Arboretum and kept at 5 ℃ until using. To investigate the morphology of seeds, an optical microscope and a scanning electron microscope (SEM) were used. GA3 treated or untreated seeds (4 replicates of 25 seeds each) were observed germination and embryo growth for 1 month at 5 ℃ and 25/15 ℃ (12h day/12h night). The seed surface of E. stellata, light brown, was observed as a common characteristic of Eranthis genus, reticulate. The short axis of seeds was 1.11~1.77mm (average 1.44mm), and the long axis was 1.27~1.91mm (average 1.63mm), which was investigated in a slightly round shape (subglose). While no germination was observed at all conditions, Embryo growth was observed at 5 ℃ both in the control group and with GA3treated groups. Thus, seeds of E. stellata are classified as morphological physiological dormancy (MDP), which requires embryonic development and dormant break at the same time. These results can be useful information for determining morphological physiological seed dormancy and germination, and will be an important basic data for seed propagation of E. stellata as a resource.