• 한국산학기술학회논문지
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• 제14권7호
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• pp.3151-3157
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• 2013

본 연구에서는 전자부품 및 소형 플라스틱제품에서 많이 사용하는 리브(rib) 가공에 있어 기존 플렛형 2날(2F)공구와 외날형 공구(1F)의 비교실험을 통해 다음과 같은 결과를 얻었다. 직선가공의 표면거칠기 및 공구마모는 기존 플렛형의 스트레이트 구조를 갖는 공구가 좋은 결과를 보였다. 깊이 7mm 리브 가공이 기존 공구에 비해 개발공구의 표면거칠기가 약 50%정도 양호하게 나타났다. 가공시간 또한 리브 형상별 차이는 있을 수 있으나, 기존 공구에 비해 약 3배 정도 빠르게 가공할 수 있었다.

• 한국환경과학회지
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• 제13권2호
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• pp.161-165
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• 2004

This study has been conducted to develop a new recycling technology of sewage sludge using a carbonization process. The carbonizing yield, the calorific value and EC(electric conductivity) of carbonized sewage sludge had a tendency to be decreased with increase of the carbonizing temperature and time, but pH and the C/N were increased with increase the carbonizing temperature and time. The whole pore volume of carbonized sludge processed in the carbonizing furnace was /g, which was smaller than that in the electric furnace. But, the rates of mesopore and macropore were found to account for 100% therein. Rate of color and organic materials removal for dyeing wastewater were determined 70~97%, 78~83% on cotton yarn, 88~96%, 69~80% on wool wastewater and 77~89%, 77~87% on towel compared with powder activated carbon. Effect of carbonized sludge on chrysanthemum growth was investigated. Plant height and number of leaves was better mixture of carbonized sludge than comparison.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.32-37
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• 2002

High speed machining is one of most effective technologies to improve productivity. It can give great advantage for manufacture of die and Moulds. However, when the high speed machining of materials, especially in machining of micro groove, a severely thermal demage was generated on workpiece and tool. Generally, the cutting fluid is used to improve penetration, lubrication, and cooling effect. In order to rise the performance of lubrication, it contains extreme pressure agents (Cl, S, P). But the environment of work room go bad by those additive Therefore, the compressed chilly air with Oil mist system was developed to replace the conventional cutting fluid system. This paper carried out the tests to evaluate the machinability by the cutting environment in high speed micro groove machining of NAK80 (HRC40). Compressed chilly air with oil mist was ejected on the contact area between cutting edge and workpiece. The effectiveness of this developed compressed chilly air with oil mist system was evaluated in terms of tool life. The results showed that the tool life of carbide tool coated TiAIN with compressed chilly air mist cooling was much longer than with dry and flood coolant when cutting the material.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.172-175
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• 2002

High speed machining is one of the most effective technologies to improve productivity. It can give great advantage for manufacture of die and Moulds. However, when machining of micro groove in high speed machining a severely thermal damage was generated on workpiece and cutting tool. Generally, the cutting fluid is used to improve penetration. lubrication. and cooling effect. In order to rise the performance of lubrication. it contains extreme pressure agents (Cl, S, P). But the environment of work room go bad by those additive. Therefore, the compressed chilly air with oil mist system was developed to replace the conventional cutting fluid system. This paper carried out the tests to evaluate the machinability by the cutting environment in high speed micro groove machining of NAK80 (HrC40). Compressed chilly air with oil mist was ejected on the contact area between cutting edge and workpiece. The effect of this developed compressed chilly air with oil mist system was evaluated in terms of tool life. The results showed that the tool lift of carbide tool coated TiAlN with compressed chilly air mist cooling was much longer than that of the dry and flood coolant when cutting the material.

• Bulletin of the Korean Chemical Society
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• 제24권12호
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• pp.1793-1798
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• 2003

A series of amorphous molecules that possess both photoconductive and electro-optic properties was synthesized in order to investigate photorefractive properties of bifunctional organic-glasses. Diethylaminobenzaldehyde-diphenylhydrazone was covalently attached to 5-(4-diethylamino-benzylidene)-1,3-dimethylpyrimidine-2,4,6-trione through a flexible alkyl chain (3, 4, 5, 6 and 10 carbons) containing two ether linkages. The longer linkage not only lowered the glass transition temperature ($T_g$) of the molecules, but also allowed faster orientation of the chromophore. To examine the photorefractive properties, a 50 ${\mu}$m-thick film was prepared from the mixture of a bifunctional molecule, butyl benzyl phthalate, and $C_{60}$. The photoconductivity of this composite was as high as $8.01\;{\times}\;10^{-12}$ S/cm at 60 V/ ${\mu}$m, and the maximum diffraction efficiency ( ${\eta}_{max}$) of 50 ${\mu}$m-thick film was about 5% at 80 V/ ${\mu}$m.

• 한국실내디자인학회논문집
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• 제15권2호
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• pp.73-80
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• 2006

The purpose of this study is to analyze the characteristics of structural expression in the works of Louis I. Kahn. Kahn's main architectural thoughts of 'what it wants to be' and 'how it was done' are important in this research because these statements act as a clue to understand the relationship between structural expression and space. 'What it wants to be' means the essence and existence of architecture and 'how it was done' shows the tectonic of architecture and construction process to enhance its presence. Kahn's emphasis of structural expression stems from the fact that structure is the logical part of whole building system rather than the concealed object for the exterior of buildings. Therefore structure of Kahn's architecture is not a structure only to support building but a mean to express his thoughts in a corporeal way. In Kahn's works, the characteristics of structural expressions are summarized as the visualization of the order in dynamics, construction process, spatial system, and the relationship between structure and light in the space.

• Journal of the Optical Society of Korea
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• 제13권1호
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• pp.75-79
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• 2009

A four beam interference optical system for laser micro structuring using a pulse laser was demonstrated. The four beam interference optical system using a pulse laser(picosecond laser) can fabricate micro structure on mold material(NAK80) directly. Micro structure on the polymer can be reproduced economically by injection molding of the micro structure on the mold material. The four beam interference optical system was composed by the DOE(Diffractive Optical Element) and two lenses. The laser intensity distribution of four beam interference was explained by an interference optics point of view and by the image optics point of view. We revealed that both views showed the same result. The laser power distribution of a $1{\mu}m$ peak pattern was made by the four beam interference optical system and measured by the objective lens and CCD. A $1{\mu}m$ pitch dot pattern on the mold material was fabricated and measured by SEM(Scanning Electron Microscopy).

• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.887-890
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• 2009

Hydroxyapatite (HAp)-based materials have attracted considerable attention on account of their excellent stability and recrystallization. Nanoscale HAp powders with a mean particle size of 200 nm were used to regenerate the enamel layers of damaged teeth. An artificially scratched tooth was immersed in a nanoscale HAp powder suspension in d.i. water (HAp of 70 wt%) at 37 ${^{\circ}C}$ for a period of 1~3 months. SEM and AFM showed that the scratched surface was ultimately inlaid with HAp after three months and the roughness increased from 2.80 to 5.51. Moreover, the hardness of the neo-generated HAp layer on the crown was similar to that of the innate layer. $Ca^{2+}$ and ${PO_4}^{3-}$ ions from the HAp powders dissolved in d.i. water were precipitated on the tooth to produce cemented pasteson the enamel surface due to its high recrystallizing characteristics, resulting in a hard neo-regenerated HAp layer on the enamel layer. This nanoscale HAp powder solution might be used to heal decayed teeth as well as to develop tooth whitening appliances.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2008년도 정기총회 및 학술발표대회
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• pp.329-332
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• 2008

This study presents a viscoelastic characterization of flexible pavement subjected to moving loads. A series of field tests have been conducted on three pavement sections (A2, A5, and A8) at the Korea Expressway Corporation (KEC) test road. The effect of vehicle speed on the responses of each test section was investigated at three speeds: 25km/hr, 50km/hr, and 80km/hr. During the test, both longitudinal and lateral strains were measured at the bottom of asphalt layers and in-situ measurements were compared with the results of finite element (FE) analyses. A commercial FE package was used to model each test section and a step loading approximation has been adopted to simulate the effect a moving vehicle. Field responses reveal the strain anisotropy (i.e., discrepancy between longitudinal and lateral strains) and the amplitude of strain normally decreases as the vehicle speed increases. In most cases, lateral strain was smaller than the longitudinal strain, and strain reduction was more significant in lateral direction.

• 한국방재학회 논문집
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• 제11권2호
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• pp.75-80
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• 2011

본 연구의 주목적은 에너지 비율 인자와 위상각을 이용한 연성포장의 피로예측 모델을 개발하는 것이다. 본 연구에서 도입된 에너지 비율 인자와 위상각은 점탄성 재료의 기본적인 성질을 반영하기 위하여 사용되었다. 에너지 비율 인자는 가상 방출 에너지와 시험 중 파괴시 까지의 누적 방출 에너지의 비로 정의된다. 위상각은 아스팔트 혼합물의 응력과 변형률의 차이로부터 발생한다. 아스팔트 콘크리트 혼합물의 실험결과를 이용하여 위상각이 측정 되었으며 초기 stiffness와 초기 위상각의 관계가 제시 되었다. 본 연구 결과 아스팔트 콘크리트 혼합물의 점탄성 재료라는 고유한 성질을 반영할 수 있는 에너지 비율 인자와 위상각을 활용한 연성포장용 피로 예측 모델이 제안되었다.