• 한국결정성장학회지
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• 제24권3호
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• pp.111-119
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• 2014

A novel pulsed laser ablation process in liquid was investigated to prepare scheelite-type ceramic [calcium tungstate ($CaWO_4$) and calcium molybdate ($CaMoO_4$)] nanocolloidal particles. The crystalline phase, particle morphology, particle size distribution, absorbance and optical band-gap were investigated. Stable colloidal suspensions consisting of well-dispersed $CaWO_4$ and $CaMoO_4$ nanoparticles with narrow size distribution could be obtained without any surfactant. Particle tracking analysis using optical microscope combined with image analysis was applied for a fast determination of particle size distribution in the prepared nanocolloidal suspensions. The mean nanoparticle size of $CaWO_4$ and $CaMoO_4$ colloidal nanoparticles were 16 nm and 30 nm, with the standard deviations of 2.1 and 5.2 nm, respectively. The optical absorption edges showed blue-shifted values about 60~70 nm than those of reported in bulk crystals. And also, the estimated optical energy band-gaps of $CaWO_4$ and $CaMoO_4$ colloidal particles were 5.2 and 4.7 eV. The observed band-gap widening and blue-shift of the optical absorbance could be ascribed to the quantum confinement effect due to the very small size of the $CaWO_4$ and $CaMoO_4$ nanocolloidal particles prepared by pulsed laser ablation in liquid.

• 대한치과교정학회지
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• 제31권5호
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• pp.499-504
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• 2001

하악골 횡적 성장결핍에 의한 하악 전치부의 총생을 치료하는데 성인의 경우 발치가 종종 요구된다. 그러나 발치에 의한 안모 변화가 바람직하지 않을 때 견인골 신장술을 시행하여 하악 정중부의 확장은 횡적 공간을 확보하여 빠른 교정치료 및 안정성을 확보할 수 있는 방법으로 고려된다. 하악 정중부 견인골 신장술을 시행한 후 tooth-borne type 과 tooth & bone-borne type distractor를 사용하여 latency, distraction, consolidation period를 거쳐 하악 정중부 횡적 확장을 시행하여 전치부 총생을 빠르게 치료할 수 있었으며, 두가지 방법에 의한 치유과정을 비교한 결과 치주적인 요소와 골 형성과정은 유사하였으며, 악관절 부위의 퇴행적 증상변화는 관찰되지 않았다.

• 농촌계획
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• 제22권3호
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• pp.71-80
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• 2016

Korea is becoming a model country for the developing countries' agricultural and rural development. Drawing implications for Vietnam from Korea's experiences can help make development strategies and policies for other developing countries including North Korea as well as for Vietnam itself. Vietnam is facing an inefficiency in agricultural production and the gap between urban and rural growth has been widening. Farm sizes per household are small and farmlands are scattered. Diversification in rural industry is very restricted. To attack these problems, investment is urgently needed for rural infrastructure building as well as agricultural structure adjustment. In the process of rural development, there have been also encountered such problems as financial procurement, community's spontaneous participation, manpower development for adjusting to industrial structural change. Korea's experiences may be helpful for establishing rural development strategies and policies in Vietnam. Benchmark scopes can go beyond Saemaul Undong in 1970s. Korea's pre- and post-Saemaul Undong era as well as the Saemaul Undong era can be referred. In the wake of globalization, Vietnam has not only experienced compressed rapid economic growth but also encountered policy tasks to eradicate poverty, to realize self-reliance and income increase, and to lessen urban-rural development gap, at the same time. Korea's experiences show that priority needs to be put on the establishment of national and rural development strategies based on Vietnam-specific conditions, utilization of village's resources including community tradition and social capital, fund raising for rural development, farmland development and mobilization, production and living infrastructure building, technology transfer for farmers and vocational training for new job seekers.

• 한국언론정보학보
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• 제31권
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• pp.295-325
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• 2005

이 연구는 방송과 통신의 융합과정에서 나타나고 있는 갈등이 과거의 사업자간 갈등이나 규제기구 간 갈등 혹은 사업자와 규제기구 간의 갈등과 같은 단면적 갈등을 넘어서서 사업자간 갈등과 규제기구 간 갈등이 복합되는 <복합적 갈등>의 양상을 보이고 있음을 보여주고자 하며, 이와 같은 상황에서 갈등 관리는 어떻게 이루어지고 있는지 알아봄으로써, 향후 신매체 도입과정에서 재현될 수 있는 갈등해결을 위한 바람직한 대안을 제시하는데 연구목적을 두고 있다. 이를 위해 IPTV 도입을 둘러싼 정책갈등을 사례 분석하였다. 방법론으로는 IPTV에 대한 정부의 입장 표명 등이 이루어진 시점인 2004년 12월부터 2005년 8월까지 관련 정책주체들이 공식, 비공식적으로 발표한 문헌을 분석하였으며, 이와 함께 정책주체들 간의 갈등관계를 파악하기 위해 관련 주체 10인에 대한 심층인터뷰를 실시하였다.

• 대한지리학회지
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• 제39권4호
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• pp.633-642
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• 2004

본 연구의 목적은 규칙기반 모델링을 구성하여 하계망을 일반화하고자 하였다. 그 동안 지도 일반화에 대한 연구는 제한된 지도요소를 대상으로 선형사상의 형태변형을 위한 알고리즘 개발과 평가에 집중되었다. 규칙 기반 모델링은 지도제작 원리와 공간현상의 분포패턴을 분석하여, 그 결과를 일반화 과정에 적용하기 때문에 기존의 일반화 알고리즘 개선에 도움이 된다. 규칙기반 모델링은 다양한 지도요소들을 대상으로 일반화를 적용할 수 있고, 디지털 환경하에서 다축척 지도제작에 효과적이다. 본 연구에서 개발된 하계망 규칙기반 모델링은 일반화 규칙, 중심선 추출 그리고 선형사상 일반화 알고리즘으로 구성된다. 일반화를 적용하기 앞서, 하계망은 논리적 오류를 최소화하기 위해 저수지와의 연결관계를 분석하였다. 모델을 적용한 결과, 108개의 실폭 하천 중 17개 하천이 중심선으로 추출되었다. 하천의 총길이는 1:25,000에서 17%, 1:50,000에서는 29%로 감소하였다. 선형사상 일반화를 위해 개발된 Simoo 알고리즘은 Douglas-Peucker 알고리즘과 비교하였다. Doug]as-Peucker 알고리즘은 자료점 간격과 편각이 커지게 되어 선의 형태가 거칠어지는 반면, Simoo 알고리즘에서 선형사상은 축척이 감소함에 따라 보다 완만해진다.

• 한국사회복지학
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• 제46권
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• pp.37-59
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• 2001

This paper investigates the long-term social changes and the emerging issues in social insurance that such changes will entail, It does not attempt to resolve the conflict between neo-liberal reforms and neo-corporalist reforms. Nor does it confine itself to proposing the options to secure the financial stability of social insurance schemes. The aim of this paper lies in anticipating various problems that result from social development, analyzing the impacts of these problems on social insurance schemes, and delineating the solutions to these problems. This paper is comprised of three parts. First, it describes the expected long-term changes in society and the ensuing problems. Second, it asks whether these problems can be solved with increased public expenditures. For this purpose, an analysis of the trend in the expenditures by welfare states is attempted. Third, it summarizes the issues in social insurance and presents the possible solutions to the problems. In the chapter that deals with social changes and social problems, various aspects are reviewed, including the globalization process, the development of It industries, the uncertainty in the classification of incomes, the widening gap in earnings due to the bio-economy, and the relation between social insurance schemes and the tax system. It is concluded that there are limits to the role that increased public expenditures can play to solve the social problems. This paper argues for a structural change in the social insurance system. In every social insurance scheme, the state should foe-us its effect on the provision of basic protection against social risks for the whole population. At the same time, the state should improve the financial stability of the scheme and avoid large-scale deficits.

• 대한토목학회논문집
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• 제9권3호
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• pp.75-88
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• 1989

본(本) 연구(硏究)에서는 도로기하구조(道路幾何構造) 개량(改良)이 발생(發生)하게 될 performance 분석(分析) 모형(模型)을 최근(最近) 기법(技法)을 통하여 개발(開發)하였고 그 절차상(節次上)의 산정(算定) 과정(過程)을 전산화(電算化)하여 GUCAM(Geometric-specific User Cost Analysis Moded)을 개발(開發)하였다. GUCAM과 HIAP 모형간(模型間)의 비교(比較)를 위하여 지방부(地方部) 2차선도로(車線道路)를 4차선도로(車線道路)로 확장하는 현장(現場) 자료(資料)를 입력(入力)하였다. 그 결과(結果) GUCAM이 도로(道路)의 기하구조개량(幾何構造改良)에 보다 실제적(實際的)이고 민감하게 반응(反應)하는 것으로 나타났으며 그 이유는 도로(道路)의 평면곡선(平面曲線)과 구배를 반영하는 절차(節次) 개선(改善)하였기 때문인 것으로 판단되었다. 향후의 과제(課題)로는 GUCAM이 아직도 한 평면곡선(平面曲線)이나 구배의 개량(改良)을 충분히 고려하지 못하고 있는 점을 생각하여 이에 대한 보다 정확(正確)한 performance 분석(分析)에 관한 연구(硏究)가 될 것이다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 제5회 영호남 학술대회 논문집
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• pp.93-93
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• 2003

Photoluminescence(PL) properties of Silicon nanocrystals (nc-Si) as a function of temperature is reported to consider the mechanism of PL. Nc-Si has been made by $Si^+$ ion-implantation into thermal $SiO_2$ and subsequent annealing. And after gold had been diffused at the same samples above, the resultant PL spectra has been compared to the PL spectra from the non-gold doped nc-Si. PL peak energy variation from nc-Si is same with the variation of energy bandgap of bulk silicon as temperature changes from 6 K to room temperature. This result may mean nc-Si is still indirect transition material like bulk silicon. Gold doped nc-Si reveals short peak wavelength of PL spectrum than gold undoped one. PL peak shift through gold doing process shows clearly the PL mechanism is not from defect or interface states. PL intensity increases from 6K to a certain temperature and then decrease to room temperature. This characteristic with temperature shows that phonon have a role for the luminescence as theory explains that electron and hole can be recombined radiatively by phonon's assist in nc-Si, which is almost impossible in bulk silicon. Therefore luminescence is observed in nc-Si constructed less than a few of unit cell and the peak energy of luminescence can be higher than the bulk bandgap energy by the bandgap widening effect occurs in nanostructure.

• Restorative Dentistry and Endodontics
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• 제25권3호
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• pp.459-473
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• 2000

Dental caries is the most common disease in the maxillofacial area. There are many factors contributing to its development, but complete understanding and prevention is not fully known. Since the structure of the coronal and root portion of the tooth is different, the remineralization and demineralization process is also known to be different. In this study, by using a partially saturated buffer solution, we created artificial enamel and dentin caries and evaluated mineral loss. A remineralization solution with four different degrees of saturation (degree of saturation ; group 1, 0.268, group 2, 0.309, group 3, 0.339, group 4, 0.390, PH 4.3, F-2ppm) was used on a demineralized specimen. The mineral precipitating quantity and depth was evaluated by using microradiography. Using an atomic force microscope (AFM), hydroxyapatite crystals of normal, demineralized, and remineralized enamel and dentin were evaluated. The results were as follows: 1. As the degree of saturation of the remineralizing solution increased, the mineral precipitation in the enamel was increased. In group 4, mineral precipitation was limited near the surface. 2. As the degree of saturation of the remineralizing solution increased, the mineral precipitation in the dentin was decreased and it occurred in a deeper portion. In group 4, however, mineral precipitation occurred on the surface and its quantity increased. 3. There was a statistically significant interaction between enamel and dentin mineral content changes on specimens treated with remineralization and demineralization solution (demineralization r=0.44, remineralization r=0.44, p<0.05). 4. Demineralized hydroxyapatite crystals showed central and peripheral dissolving and widening of intercrystal spaces under the AFM. 5. In dentin remineralization small crystal precipitation occurred between the large crystals. We conclude that by adjusting acidulated buffer solution's degree of saturation, we can control enamel and dentin remineralization. In addition, the AFM is highly useful in evaluating changes in remineralized and demineralized hydroxyapatite crystals.

• 한국전기전자재료학회논문지
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• 제26권3호
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• pp.246-251
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• 2013

Screen printing is commonly used to form the front/back electrodes in silicon solar cell. But it has caused high resistance and low aspect ratio, resulting in decreased conversion efficiency in solar cell. Recently the plating method has been combined with screen-printed c-Si solar cell to reduce the resistance and improve the aspect ratio. In this paper, we investigated the effect of light induced silver plating with screen-printed c-Si solar cells and compared their electrical properties. All wafers were textured, doped, and coated with anti-reflection layer. The metallization process was carried out with screen-printing, followed by co-fired. Then we performed light induced Ag plating by changing the plating time in the range of 20 sec~5min with/without external light. For comparison, we measured the light I-V characteristics and electrode width by optical microscope. During plating, silver ions fill the porous structure established in rapid silver particle sintering during co-firing step, which results in resistance decrease and efficiency improvement. The plating rate was increased in presence of light lamp, resulting in widening the electrode with and reducing the short-circuit current by shadowing loss. With the optimized plating condition, the conversion efficiency of solar cells was increased by 0.4% due to decreased series resistance. Finally we obtained the short-circuit current of 8.66 A, open-circuit voltage of 0.632 V, fill factor of 78.2%, and efficiency of 17.8% on a silicon solar cell.