• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.167-167
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• 2013

최근에 산화물 형광체는 황화물 형광체에 비해 높은 화학적 안정성을 나타내기 때문에 백색 발광 다이오드, 전계방출 디스플레이와 플라즈마 디스플레이 패널에 그 응용성을 넓히고 있다. 마그네슘 니오베이트(magnesium niobate, MgNb2O6)는 우수한 유전 특성(상대 유전상수=18.4)을 나타내기 때문에 마이크로파 유전체로 응용 가능하며, 단일상 릴랙서 페라브스카이트(relaxor perovskite) Pb(Mg1/3Nb2/3)O3을 합성하기 위한 전구체 (precursor)로 널리 사용되고 있으며, 나이오븀산염 이온에서 다양한 색상을 방출하는 활성제 이온으로 효율적인 에너지 전달이 일어남으로써 Sm3+, Dy3+, Eu3+와 같은 희토류 이온의 좋은 모체 격자로 개발할 수 있다. 본 연구에서는 마그네슘 니오베이트 MgNb2O6 모체 결정에 다양한 활성제 이온, 즉 Eu3+, Sm3+, Dy3+, Tb3+를 선택적으로 주입하여 발광 효율이 높은 천연색 형광체를 합성하고자 한다. 특히, 모체 결정에 주입되는 활성제 이온 주위의 국소적인 환경이 반전 대칭에서 변형되는 척도를 조사하여 활성제의 주 발광 파장의 세기가 최대가 되는 최적의 조건을 결정하고자 한다. Mg1-1.5xNb2O6:REx3+ 형광체 분말 시료는 초기 물질 MgO, Nb2O5와 희토류 이온을 화학 반응식에 맞게 정밀 저울로 측량하여 플라스틱 용기에 ZrO2 볼과 함께 넣고, 소정의 에탄올을 채운 뒤 밀봉하고서, 300 rpm의 속도로 20시간 볼밀 (ball-mill) 작업을 수행하였다. 그 후, 체(sieve)로 ZrO2 볼을 걸러낸 다음에 혼합된 용액을 각 비커에 담아서 $40^{\circ}C$의 건조기에서 24시간 건조하였고, 건조된 시료를 막자 사발에 넣고 잘게 갈고 80 ${\mu}m$의 체로 걸러낸 후에, 알루미나 도가니에 활성제 이온별로 각각 담아, 전기로에 장입하여 매분당 $5^{\circ}C$의 비율로 온도를 상승시켜 $350^{\circ}C$에서 5시간 동안 하소 공정을 실시한 후에, 온도를 계속 일정한 율로 증가시켜 $1,200^{\circ}C$에서 5시간 동안 소성하여 합성하였다. 합성된 형광체 분말의 결정 구조는 $Cu-K{\alpha}$ 복사선(파장: 1.5406)을 사용하여 X-선회절장치로 측정하였으며, 형광체의 표면 형상은 전계형 주사전자현미경으로 관측하였다. 흡광와 발광스펙트럼은 제논 램프를 광원으로 갖는 형광 광도계를 사용하여 측정하였다. 모체 결정에 활성제 이온 Eu3+, Sm3+, Dy3+, Tb3+가 도핑된 형광체 분말은 각각 적색, 주황색, 황색, 녹색 발광이 관측되었다. 각 발광 스펙트럼과 결정 입자의 크기와 형상 사이의 상호 관계를 조사하였다. 실험 결과로부터, 각 형광체의 발광 파장은 활성제 이온의 종류 와 서로 밀접하게 관련되어 있으며, 형광체 시료 합성시 활성제 이온의 농도를 선택적으로 조절함으로써 발광의 세기를 제어할 수 있음을 확인하였다.

• Economic and Environmental Geology
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• v.37 no.3
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• pp.365-373
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• 2004

This survey was conducted on KOSEF's research internship awardees (FY 1998 to 2001) in order to investigate the employment status of doctoral and master's degree holders in Geosciences in Korea. An unemployment rate of KOSEF's research internship awardees (FY 1998 to 2001) was 32.0 percent for the doctoral and master's degree holders in Geosciences. 37.2 percent of employed doctoral and master's degree holders only obtained employment as a full-time and part-time status in industry, research institutions and academia in Korea. The U.S. Census Bureau conducted the 2001 survey of doctoral recipients (SDR). Based on this survey, most U.S. doctoral holders were employed and an unemployment rate for 2001 was only 1.3 percent of the Geosciences doctoral holders. KOSEF or related academic societies should be able to provide a more precise information of the employment status for new doctoral and master's degree holders in Geosciences by conducting the survey of doctoral and master's degree recipients. The results of this survey will be used to understand and to predict trends in employment opportunities in Geosciences for doctoral and master's degree holders.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.74-82
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• 2016

The term research institute spin-offs refers to new firms created by public research institutes. These spin-offs are different from other start-ups in two respects: on the one hand, they should be located in the Special Research and Development Zones and, on the other hand, these firms are supposed to commercialize the results of public R&D activities. These spin-off firms show higher rates of survival and job creation than general new firms, which means that their contribution to economic growth is not negligible. The present study analyzes the factors affecting research institute spin-offs using a random effect panel logit model and negative binomial model. From previous studies, four elements are identified as playing an important role in the commercialization of public R&D through spin-offs, namely their organizational character, research capability, technological character, and geographical location. The empirical results demonstrate that government research institutes with more researchers and patents are more likely to create new firms. In addition, the location of the institutes significantly affects the probability of their creating spin-offs and their number. When the technological stage and TLO size are considered, however, it turns out that the number of researchers and technological stage play important roles in the spin-offs.

• Journal of the Korea Society of Computer and Information
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• v.26 no.11
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• pp.1-9
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• 2021

3D-NAND flash memory provides high capacity per unit area by stacking 2D-NAND cells having a planar structure. However, due to the nature of the lamination process, there is a problem that the frequency of error occurrence may vary depending on each layer or physical cell location. This phenomenon becomes more pronounced as the number of write/erase(P/E) operations of the flash memory increases. Most flash-based storage devices such as SSDs use ECC for error correction. Since this method provides a fixed strength of data protection for all flash memory pages, it has limitations in 3D NAND flash memory, where the error rate varies depending on the physical location. Therefore, in this paper, pages and layers with different error rates are classified into clusters through the K-means machine learning algorithm, and differentiated data protection strength is applied to each cluster. We classify pages and layers based on the number of errors measured after endurance test, where the error rate varies significantly for each page and layer, and add parity data to stripes for areas vulnerable to errors to provides differentiate data protection strength. We show the possibility that this differentiated data protection policy can contribute to the improvement of reliability and lifespan of 3D NAND flash memory compared to the protection techniques using RAID-like or ECC alone.

• International Area Studies Review
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• v.15 no.3
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• pp.239-261
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• 2011

The cyclicality of productivity has been one of the essential issues in macroeconomics. Since Solow(1957) developed the dominant approach to the measurement of productivity growth, Solow's approach, which assumes the perfect competition, the constant returns to scale, and the full use of input factor has been modified particularly in Hall's(1990) and Basu's(1996) works. Their researches take account of market power, returns to scale, and variable factor utilization. This paper establishes the empirical model based on Hall's(1990) and Basu's(1996) models, estimates 4 types of Solow's reidual in manufacturing and 2 service industries over the period 1975:1-2010:4, and analyzes the cyclicality of measured productivity. The result proved the measured productivity to be procyclical in manufacturing industries and electricity and water industry, and in contrast to the Basu's, the variable factor utilization transformed the countercyclicality of measured productivity into its procyclicality in the Korean economy.

• Journal of vocational education research
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• v.37 no.6
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• pp.85-104
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• 2018

The purpose of this study was to identify the meditating effect of self leadership on the relationship between protean career attitude and subjective career success of lifelong learning educators. Based upon the results, several theoretical and practical suggestions were made to enhance self leadership, protean career attitude and subjective career success of lifelong learning educators. A survey questionnaire for this study was composed of four parts, such as the measurement tool of Protean Career Attitude(Briscoe, Hall & Demuth, 2006), Self Leadership Scale(Houghton & Neck, 2002), Subjective Career Success(Career satisfaction Scale: Greenhaus, Parasuraman & Wormley, 1990; Job Satisfaction Scale: Mobley, Jarret, Marsh & Lim, 1994; Employability Inventory: Johnson, 2001) and demographics. The subjects in this study were lifelong learning educators in Incheon. The survey questionnaires from 450 respondents were gathered, and the data from 426 respondents were used for analysis. The results of this study were as follows: First, protean career attitude of the lifelong learning educators had direct effect on subjective career success positively. Second, protean career attitude of the lifelong learning educators had indirect effect on the subjective career success with the partial mediating effect of self-leadership. Finally, based upon the above results, some implications and limitations of this study were discussed.

• The Journal of the Korea Contents Association
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• v.19 no.1
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• pp.339-349
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• 2019

The purpose of this study is to analyze the influential factors on the change in life satisfaction of elderly households. In this study, single and couple elderly households were defined as elderly households and the 2nd, 3rd, and 4th data of the Korean Longitudinal Survey of Ageing (KLoSA) provided by the Korea Employment Information Service (KEIS) were used. And 677 respondents aged 65 and over who had replied to all 3 sessions were included in the final subjects. multinomial logistic regression analysis was conducted to examine the influential factors on life satisfaction by the type of elderly households according to consumption pattern and the result showed that there were common influential factors such as house owning status and subjective health status and the factors that influence specific types such as expectancy of standard of living. In addition, in the longitudinal analysis of life satisfaction of elderly households, individual satisfaction level was confirmed to reduce with time and the factors that influence the longitudinal change in the level of life satisfaction of elderly households was analyzed through the conditional model of a latent growth model. The analysis results showed that household type, house owning status, and subjective health status influenced the initial value of life satisfaction of elderly households while household type and expectancy of living standard influenced the change rate of life satisfaction of elderly households. Based on the results of this study, the followings are suggested. There is a need to improve the life satisfaction of old age by increasing the opportunity for self-realization of elderly households and also policy approach should be made selectively taking various types into consideration.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.123-128
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• 2018

Effect of activators in flux on the printability and wettability of a solder paste was evaluated in this study. The activators in this study were dicarboxylic acids, which were oxalic acid (n = 0), malonic acid (n = 1), succinic acid (n = 2), glutaric acid (n = 3), adipic acid (n = 4), and pimelic acid (n = 5). When the solder pastes were observed with a SMT scope, solder with glutaric acid showed clean and shiny surface when it was melted. Slump ratio of the solder pastes was low when the carbon numbers of the dicarboxylic acid were 1-3. Spreadability was high when the carbon number was over 2. Zero cross time of wetting balance test was under 1 sec when the carbon number was over 3. When activator was oxalic acid or malonic acid, zero cross time was over 1 sec and maximum wetting force was low. Fluxes with the oxalic acid and malonic acid showed decomposition at the temperature close to melting point. Among the dicarboxylic acids, glutaric acid provided excellent slump, spreadability, and wettability.

• Journal of the Economic Geographical Society of Korea
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• v.23 no.4
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• pp.425-437
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• 2020

In Korea, the proportion of self-employed and unpaid family workers is relatively higher than other OECD countries and the operation periods of their businesses are generally shorter than others. This indicates frequent startups and closures and thus unstable employment status and income, which inevitably generates huge social costs. Restaurants are a representative business that self-employed workers easily enter and their 5-year survival rate is found to be lower than 20%. This is shorter survival period than other business sectors. This study aims to examine the associations of transport accessibility with restaurants' survival in Gwangju metropolitan area. Convenient location has been known to be a crucial factor for sales improvements and longer operation and such location is closely linked with good transport accessibility. Results from survival analysis on empirical data show that better access to road networks is significantly associated with longer survival of restaurants though subway accessibility is not. This can be explained by low modal share of subway in the study area and at the same time, requires further case studies where more developed and matured subway systems are in operation.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.16 no.3
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• pp.87-103
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• 2021

The government is trying to create jobs by providing 160 billion won in 2021 to revitalize youth start-ups, but the number of youth unemployment and potential unemployment is hitting a record high of 1.2 million due to the shock of employment due to COVID-19. Although start-ups are encouraged as an alternative to revitalizing jobs, the success rate of young start-ups is low due to lack of start-up funds and experience. The purpose of this study is to understand the need to diversify start-up education and career education by understanding start-up policies through one-time funding and short-term education. The results of the study on the factors affecting the willingness to start a business were as follows, by sampling 344 students from specialized high schools preparing for employment and 344 young people in their 20s who are seeking jobs. First, among the entrepreneurship subvariables, innovation, autonomy of job value, and desire for economic achievement are significant, and the older the person surveyed, the more positive the perception of the entrepreneur was. Second, as you get older, your will to start a business decreases, and your experience in successful start-up models and start-up education has an impact on your will to start a business. Third, perception of entrepreneurs is a partial medium effect, which indirectly influences the willingness to start a business and directly or indirectly influences the willingness to start a business through the autonomy of job values, the desire to achieve economic and entrepreneurship.