• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.84-84
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• 2009

$BaTiO_3$는 perovskite 구조를 가지는 대표적인 강유전체 재료로서 MLCC (Multi Layer Ceramic Capacitor), PTC thermistor등에 널리 사용되어지고 있다. 최근 고용량 MLCC의 상업화와 함께 나노크기를 갖는 tetragonal phase의 $BaTiO_3$ 입자를 합성하기 위한 다양한 제조방법이 제시되고 있다. 또한 유전특성과 온도특성 및 신뢰성을 향상시키기 위해 많은 첨가제들이 연구되어지고 있다. 따라서 본 연구에서는 희토류 원소인 $Y_2O_3$를 첨가하여 유전특성 및 온도특성을 향상시키고자 하였다. 본 실험에서는 150nm 크기를 갖는 pure $BaTiO_3$ 분말을 사용하고 $Y_2O_3$의 양은 0.02 ~ 0.1wt%로 변수를 주어 첨가하였으며, 최적의 소결 조건을 찾기 위하여 1200, 1230, $1250^{\circ}C$에서 소결을 진행하였다. 실험방법으로는 균일한 혼합을 위하여 Iso-alcohol을 이용하여 48시간 ball-mill 하였으며 오븐에서 건조 후 ${\Phi}15$로 성형하여 소결을 진행하였다. 실험결과로는 $Y_2O_3$ 첨가량이 0.02wt% 부터 상온부터 상전이 온도 부근의 유전율 기울기는 완만해 지는 것을 확인할 수 있었으며, 소결시편의 정방정비 (tetragonality)도 뚜렷하게 나타났다. $Y_2O_3$ 첨가랑이 0.1 wt% 일 때는 첨가량의 증가로 인해 강유전성이 상쇄됨을 나타냈다. 이는 $2450^{\circ}C$에 이르는 매우 높은 용융온도와 $2350^{\circ}C$까지 상전이가 는 $Y_2O_3$를 미량 첨가할 때, 고온에서 높은 화학적 안정성과 내열성을 가져 온도 안정성이 향상된 것으로 판단된다.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.179-179
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• 2012

국내에는 나노 분말 제조를 위한 RF 열플라즈마 시스템 제조 기술이 확보되어 있지 않고, 또한 나노 파우더 제조를 위한 공정 기술 역시 외국 업체에 전적으로 의존하고 있다. 본 연구에서는 나노 분말 제조를 위한 RF 열 플라즈마 토치 시스템 개발과 고품질의 나노 파우더 합성 공정 기술을 확립하여 필요 기관에 제공하는데 있다. 80 kW RF Plasma torch system의 설계 및 제작을 위해 플라즈마 Simulator인 CFD-ACE+를 이용하여 플라즈마 토치 및 반응로 내의 온도 분포, 유체 유동, 열전달 등의 해석을 통해 플라즈마 토치 및 반응로의 반경 및 길이, 구조의 설계 값을 도출하여 반응로를 설계하여 RF 파워, RF 플라즈마 토치(Torch), 반응기(Reactor), 사이클론(Cyclone), 포집부(Collector), 열교환기 및 진공배기 시스템으로 구성하였다. Si 나노 소재의 경우, 이차전지 음극재에 적용이 가능한 대표적인 소재로서 높음 비용량과 충/방전시 부피팽창을 감소시킬 수 있어 이차전지의 고용량 구현을 위해서는 가장 중요한 소재중 하나로 많은 관심 재료로 평가 받고 있다. 따라서 본 연구에서는 상용화된 Si 원료 powder를 사용하여 고상 분체 공급 장치를 통하여 고온의 플라즈마를 통과시켜 기상화 및 결정화과정을 통해 Si 나노분말을 제조하였다. 공정 변수로서 공정압력 및 플라즈마 power, Gas의 변화량에 따른 나노 분말의 제조 특성에 대한 실험을 진행한 후 제조된 나노 분말을 비표면적측정(BET) 및 SEM 측정 결과 분석을 통하여 시스템 특성을 파악하였으며 제조된 Si 나노 파우더는 이차전지 음극재로서 770 mAh/g의 용량과 93%@50 cycle 수준의 유지율을 나타내었다.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.4
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• pp.35-40
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• 2010

In this study, the reliability of thermal shock, thermal cycle, and complex vibration test at high temperature were examined for 3 types of lead-free solder alloys, Sn-3.5Ag, Sn-0.7Cu and Sn-5.0Sb. For the reliability test, daisychained BGA chips with ENIG-finished Cu pad was assembled with the three lead-free solders on OSP-finished PCBs. Among the 3 types solder alloys, Sn-3.5Ag solder alloy showed the highest degradation rate of electrical resistance and joint strength. On the other hand, Sn-0.7Cu solder alloy had high stability after the reliability tests.

• Journal of Korean Library and Information Science Society
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• v.38 no.1
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• pp.211-230
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• 2007

The purpose of this study is to survey the reference information service participation to school library human resources, to compare the independent variables with reference information service participation, and to discern what the important impacts on the differences of reference information service participation are. The 254 questionaries used were collected from December 1, 2006 to December 31, 2006 to the 327 school library employees. In this study, it is proved that there are differences between the Reference Information Service Participation of school library human resources and independent variables: gender, the level of school library, length of service, employment style. Tips for the reference information service participation of school library human resources were provided based on inadequacies and other findings revealed through this study.

• Korean Business Review
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• v.12
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• pp.275-301
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• 1999

The year of 1998 was a very hard time for the most of Koreans. The rate of unemployment, which had averaged between 2 and 2.5 percent for many years, has continued to rise as the industrial production declined from the first quarter of 1998. The seasonally unadjusted unemployment rate recorded high of 8.4 percent in the first quarter of 1999, and the number of the unemployed as 1.75 million. On the other hand, the unemployment rate in Kangwondo used to be smaller than the nation-wide rate. However, this should not be taken as evidence that Kangwondo's economy used to perform better than others, because the participation rate also used to be smaller in Kangwondo than other regions. Anyhow, the unemployment problem is one of urgent issues in Korean society. The purpose of this paper is to overall review Kangwondo's unemployment counterplan and to make priorities about what we have to do against the long-run unemployment. In addition to implementing unemployment countermeasure of the central government, Kangwondo has to devise in itself unemployment counterplan reflecting local attributes.

• Korean Journal of Health Education and Promotion
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• v.28 no.4
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• pp.15-25
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• 2011

Objectives: The present study examined whether smoking rate has declined in 1992-2006 and who the high risk groups were on industry classification and employment type. Methods: Data from 91,263 persons aged 25-64 years were analyzed from three rounds of the Social Statistical Surveys of Korea between 1992 and 2006. Industry indicators were divided by the 9th Korean Standard Industrial Classification. Age-adjusted prevalence of smoking was calculated. Prevalence ratios(PR) and differences(PD) were estimated using log-binomial regression analysis. Results: Age-adjusted prevalence of smoking decreased between 1992 and 2006, specially the smoking prevalence of regular employees decreased most. PD in age-adjusted prevalence of smoking were the biggest between regular and daily employees. PR of the temporary employees', daily employees', self-employed persons' in order was wider than that of regular employees. PR increased significantly increased between 1999 and 2006 for those in manufacturing, construction, wholesale & retail trade, service industries. Increases in PR(regular/irregular) for women in service industry were statistically significant. Conclusions: Despite reducing overall cigarette smoking rates in males, the smoking rate was not reduced equally by industry classification and employment type in both genders. More adjustable antismoking policies and consideration of employment type are requested to reduce inequalities in smoking.

• Korean Journal of Microbiology
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• v.35 no.4
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• pp.283-288
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• 1999

The effect of dissolved oxygen(DO) concentration on the growth of Pseudomonas aeruginosa and it's mutant M-10 was studied the growth kinetics and the possibility of waste treatment for reducing the amount of excess sludge. Different DO concentrations on the growth of wild type Pseudomonas aeruginosa affected to cellular yields, decreasing with increasing DO concentrations. Under these conditions, the maximum 14 folds decrease of cellular yield was achieved at 90 ppm DO levels by screened, being able to reduce their cellular yields under low DO concentration. The optimum mutation conditions were obtained by the treatment of NTG mutagen at 30${\circ}C$ for 1 hr. The growth characteristics of the selected mutant M-10 showed the same as the wild type growth kinetics. However, cellular yields are significantly decreased to 55% compared with those of wild type under DO concentrations increased. We, therefore, expect the application of the mutants to waste treatment for reducing excess sludge.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.313-313
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• 1994

대상환자는 40예중 37예에서 평가가 가능하였고 남녀비는 11:26. 중앙연령 42세 이었으며 대상질환은 위선암 12에, 유방암 10예. 골옥종 5예등 이었다. rhGM-CSF에 의한 부작용은 150.250 $\mu\textrm{g}$/$m^2$/d 용량군에서는 Grade I-II의 전신쇠약감, 근육통.심계항진등이 관찰되었으나 특별한 조치없이 회복되었다. 350$\mu\textrm{g}$/$m^2$/d 용량군에서는 8예에서 WHO grade II-III의 전신쇠약, 전신열감, 흉부압박감, 호흡곤란 등을 호소하였고 1예에서 투여 1일러 WHO gradeIII의 피부반응이 나타났으며, 이 중 2예에서는 rhGM-CSF를 250 $\mu\textrm{g}$/$m^2$/d로 감량투여후 상시 증상이 소실되었다. rhGM-CSF 투여전의 대조기와 투여기의 혈액학적 소견 비교시. 평균 중성구 최저치는 세 용량군에서 모두 관찰기에 비해 시험기어서 증가하였고. 평균 총 백혈군 최저치는 150.350 $\mu\textrm{g}$/$m^2$/d 용량군은 차이가 있었고 250 $\mu\textrm{g}$/$m^2$/d 용량군은 차이가 있었으나 통계적 유의성은 없었다. 비혈구치가 최저치에서 4.000/㎣ 이상으로 회복되는 평균일수와 호중구치가 최저치에서 2.000/㎣ 이상으로 회복되는 평균일수는 세 용량군 모두에서 관찰기어 비해 시험기에서 증가하였다. 고용량 항암약물요법후 중성구 감소에 의한 발열은 rhGM-CSF 비투여기에서 18예. rhGM-CSF 투여기에서 8예 관찰되었다고 발열기간은 각각 5-7일. 2-3일 이었다. 임상 양상은 세 용량군 간 차이가 없었으나, 시험기에서 발열의 발현율이 낮았으며, 발열일 수와 항생제 사용일 수가 짧았다. 결론: 골수억제 조절 효과는 용량에 따른 혈액소견에 미치는 영향, 부작용, 감염의 빈도, 감염발생에 따른 항생제 사용기간 등을 고려하여 그 임상 유효성 평가시, 제 3상 시험에 사용할 권장량 (recommended dose) 은 250 ug/$m^2$/d $\times$ 10d 으로 관찰되었다.

• Resources Recycling
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• v.21 no.5
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• pp.58-64
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• 2012

Ti button type ingots were prepared by recycling of Ti turning scraps using vacuum arc melting process for production of consumable arc electrode. The behavior of impurities such as Fe, W, O, and N in the Ti button ingots was investigated and the properties of the Ti button ingots were also evaluated. In the case of oxygen gaseous impurity, the oxygen layers on the surface of the Ti turning scraps were easily removed by the first vacuum arc melting. On the other hand, the solute oxygen in the Ti turning scraps was not removed by the next melting. In the case of Fe, major impurity in the Ti turning scraps, the removal degree in the final Ti button ingot refined by vacuum arc melting for 20 minutes was approximately 43 %, which is due to the vapor pressure difference between Ti and Fe. As a result, the Ti button ingots with ASTM grade 3 could be obtained by multiple vacuum arc melting from the Ti turning scraps. Therefore, it was confirmed that the preparation of consumable electrode for vacuum arc remelting could be possible by recycling of Ti turning scraps.

• Journal of Labour Economics
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• v.33 no.3
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• pp.25-46
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• 2010

The outstanding performance of some nations in Central and Northern Europe such as Denmark and the Netherlands in the labor market is much indebted to their policy to help labor flexicurity. In this study, the possibility of replicating the Dutch or Danish performance in the labor market is explored in case of adopting such policy in the 22 OECD countries. If implementing the flexicurity policy in the 22 member countries of the OECD leads to strong performance in the labor market, this policy can be globally shared as universal labor policy to provide a win-win situation among the labor, management and the authorities on the matter, paving the way for replacing the Anglo-Saxon policy characterized by high flexibility and low security, or the European alternative with a lower level of flexibility and a higher level of security. According to findings from our research, flexicurity policy can not produce any tangible accomplishments in the labor market by only itself. Therefore, we may safely reach the conclusion that flexicurity policy has a limited positive influence on the labor market of some northern or central European countries. Given the striking difference in inherent conditions between such European countries and OECD countries, it is not sensible for OECD nations to adopt labor policy in the direction of flexicurity.