13.56 MHz 유도 결합 플라즈마에서의 강자성체 페라이트 코어의 효과

이원기,이경효,정진욱,Lee, Won-Ki,Lee, Kyeong-Hyo,Chung, Chin-Wook 한국반도체디스플레이기술학회 2005 반도체디스플레이기술학회지 Vol.4 No.3

Due to high permeability of the ferrite cores, the characteristics of the inductively coupled plasma(ICP) are expected to be greatly improved. We investigated the effect of the ferrite cores on conventional inductively coupled plasma. It was observed that the current and voltage in the ICP antenna are slightly decreased and the power transfer efficiency is increased. However, due to eddy current and hysteresis loss, plasma density in the ICP with the ferrite cores is not increased. It seems that the ICP with the ferrite cores at low frequency ($\∼$100 kHz) will be greatly improved since the losses at the low frequency can be negligible.

원자력간 현미경을 이용한 Poly(vinylidene fluoride)계 고분자 블렌드의 표면 모폴로지 연구

이원기,박찬영,조원제,하창식,Lee, Won-Ki,Park, Chan-Young,Cho, Won-Jei,Ha, Chang-Sik 한국접착및계면학회 2001 접착 및 계면 Vol.2 No.1

Poly(vinylidene fluoride)(PVDF)를 포함하는 고분자 블렌드 필름의 표면층의 모폴로지를 원자력간 현미경과 시차주사열량계 측정을 토대로 연구하였다. ${\alpha}$ 및 ${\gamma}$형 결정상을 가진 PVDF는 Poly(methyl methacrylate)(PMMA) 및 가수분해된 PMMA(carboxyl content:14wt%)와의 블렌딩에서 표면층은 PVDF의 결정상만으로 이루어져 있음을 확인하였다. 그러나 PMMA의 결정상이 가수분해율이 증가함에 따라 표면 자유에너지의 차이도 증가함에도 불구하고 가수분해된 PMMA의 존재를 확인하였다. 이러한 결과는 표면층에서의 낮은 표면 자유에너지 성분인 PVDF의 농축 정도는 자유에너지 차보다 상호작용력의 크기에 밀접히 관련되어 있음을 알 수 있었다. 한편, carboxyl group의 도입은 PVDF와 PMMA의 상용성을 저해하는 것으로 밝혀졌다. Surface morphology of [poly(vinylidene fluoride)/poly(methyl methacrylate)] (PVDF/PMMA) was investigated on the basis of atomic force microscopy and differential scanning calorimeter measurements. The surface of (PMMA/PVDF) and (H14-PMMA/PVDF) blend films was fully composed with PVDF crystals. Although the difference of surface free energy between PMMA and PVDF is increased with increasing carboxyl group content in PMMA, however, in the case of (H24-PMMA/PVDF) blend film surface, the existence of aggregated H-PMMA was observed. It was found that the degree of surface enrichment of the blend is more affected by the magnitude of intermolecular interaction than the surface free energy difference, Besides, the introduction of carboxyl group for miscible (PVDF/PMMA) blend decreased the miscibility in the blend.

순환골재의 부착 모르타르량이 콘크리트의 특성에 미치는 영향

이원기,최종오,정용욱,Lee, Won-Ki,Choi, Jong-Oh,Jung, Yong-Wook 한국건설순환자원학회 2015 한국건설순환자원학회 논문집 Vol.3 No.2

본 연구는 파쇄처리 순환골재를 사용한 콘크리트의 특성을 검토하기 위하여 순환골재의 흡수율별 단위시멘트량 및 물시멘트비를 변화시켜 콘크리트의 특성에 미치는 영향을 검토하였다. 실험결과 물시멘트비가 높은 저강도 배합에서는 파쇄처리 순환골재를 사용한 콘크리트와 쇄석 콘크리트의 압축강도가 동등한 수준으로 나타나 순환골재의 부착모르타르 영향이 작은 것으로 나타났다. 그러나, 물시멘트비가 낮은 고강도 배합에서는 파쇄처리 순환골재를 사용한 콘크리트가 부착모르타르의 영향으로 쇄석을 사용한 콘크리트보다 약 40%의 압축강도저하를 나타내었다. 한편, 흡수율 7%인 순환골재의 건조수축량은 재령 10주에서 흡수율 1%인 쇄석의 $-310{\times}10^{-6}$보다 2배 증가된 $-700{\times}10^{-6}$을 나타내어 콘크리트용 골재로의 재활용시 건조수축에 대한 검토가 선행되어야 할 것으로 사료된다. 또한 단위시멘트량 $450kg/m^3$인 부배합 콘크리트의 압축강도는 흡수율 3%인 순환골재 사용시 쇄석 사용 콘크리트와 동등하게 나타난 반면, 흡수율 7%인 순환골재를 사용한 경우에는 쇄석 사용 콘크리트에 비해 약 7%정도 낮게 나타났다. 그러나, 단위시멘트량 $350kg/m^3$인 일반배합 콘크리트의 압축강도는 쇄석 사용 콘크리트에 비해 압축강도 저하가 현저하게 나타났다. In this study, the different unit cement content by the ratio of water absorption and water-cement ratio are applied to examine the properties of the concrete used the aggregate recycled by the crushing treatment. According to the experimental results, in the mix of low strength and high water-cement ratio, both of the compressive strength is almost equal in the concrete using the recycled aggregate by the crushing treatment and the concrete using broken stones. It means that the recycled aggregate has the low effect of the amount of bonded mortar. But, in the mix of high strength and low water-cement ratio, the concrete using the recycled aggregate by the crushing treatment has 40% less of the compressive strength than that using broken stones by the effect of the amount of bonded mortar. On the other hand, after 8 weeks, the dry shrinkage of the recycled aggregate with 7% of the ratio of water absorption doubles that of the broken stones with 1% ($-350{\times}10^{-6}$), in other words $-700{\times}10^{-6}$. Thus, the dry shrinkage should be prior to any other conditions in recycling waste concrete for the aggregate for concrete. When the recycled aggregate with 3% of the ratio of water absorption is used, the compressive strength of the rich mix concrete ($450kg/m^3$ of the unit cement content) is equivalent to that of the concrete using broken stones, while in using the recycled aggregate with 7% of the ratio of water absorption, the rich mix concrete has 7% lower compressive strength than the concrete using broken stones. But, the compressive strength of the ordinary mix concrete ($350kg/m^3$ of the unit cement content) is far lower than that using broken stones.

주사형 프루브현미경을 이용한 고분자의 표면구조 및 표면분자운동 특성 평가

이원기,조원제,하창식,Lee, Won-Ki,Cho, Won-Jei,Ha, Chang-Sik 한국고분자학회 1998 고분자 과학과 기술 Vol.9 No.2

아크릴계 점착제의 제조와 가교물성에 관한 연구

김판수 ( Pan Soo Kim ),이상무 ( Sang Mu Lee ),정신혜 ( Sin Hye Jung ),이원기 ( Won Ki Lee1 ) 한국접착및계면학회 2013 접착 및 계면 Vol.14 No.1

압력감응성 아크릴 점착제의 물성은 가교를 위한 관능성그룹을 가진 단량체를 이용하여 쉽게 물성을 조절할 수 있다. 본 연구에서는 두개의 다른 가교제, isocyanate 및 epoxy형 가교제에 따른 아크릴 점착제의 가교특성과 물성을 연구하였다. 2-Ethylhexyl acrylate, acrylic acid (AA)와 2-hydroxyethyl methacrylate를 주 단량체로 하여 이소시아네이트 또는 에폭시형 가교제로 가교한 점착제의 박리점착 특성, 볼텍, 유지력 및 수축성을 고찰하였다. 점착특성은 AA함량 증가와 더불어 증가하였고 가교점이 많고 ether와 같은 유연한 결합을 생성하는 에폭시형 가교제에서 우수한 물성을 나타내었다. The physical properties of the acrylic pressure sensitive adhesives (PSAs) can be easily controlled by a proper functional monomer which has functional groups for crosslinking. This study was to investigate the effect of crosslinking agents, isocyanate and epoxy types, of acrylic PSAs on adhesive properties. 2-Ethylhexyl acrylate, acrylic acid (AA), and 2-hydroxy ethyl methacrylate as monomer were used. The obtained samples with different AA contents were partially crosslinked with epoxy- or isocyanate-typed agent. Peel strength, balltack, holding power test and contraction percentage of the obtained PSA were evaluated. Most properties of acrylic PSAs were increased with AA content and acrylic PSAs with epoxy-typed crosslinking agent (4 crosslinking sites) which produces flexible link (ether), showed better properties than those of isocyanate-typed one (3 crosslinking sites).

전신성 흥반성 루푸스 환자에서 임상적 질병 활성도와 혈청 인터루킨 8 과의 연관성

이원기(Won Ki Lee),송창호(Chang Ho Song),박용범(Yong Beom Park),이충원(Choong Won Lee),서창희(Chang Hee Suh),이찬희(Chan Hee Lee),이지수(Ji Soo Lee),김동수(Dong Soo Kim),이수곤(Soo Kon Lee) 대한내과학회 1998 대한내과학회지 Vol.54 No.6

N/A Objectives To evaluate serum Interleukin 8 (IL-8) as a predictor of disease activity in SLE and to provide insight into the potential role of IL-8 in the pathogenesis of SLE. Methods: Sixty-four paired from the 32 SLE patients and 10 healthy control were obtained. Serum IL-8 levels were determined by EUSA technique. Tests for other laboratory parameters, such as circulating immune complex (CIC), C3, C4 ANA, anti-dsDNA, Hb, Hct, leukocyte, lymphocyte, platelet and KSH, were performed for every sample coincidently with assessment of clinical disease activity by the Lahita scales, Results: We found that serum IL-8 levels in SLE patients were significantly higher than those of healthy controls. Serum IL-8 levels significantly correlated with clinical disease activity. Serum IL-8 levels correlated with CIC, but it had no correlation with other laboratory parameters. Conclusion: These findings suggest that serum IL-8 can be used as a marker of disease activity in patients with SLE. These results may have implication in the pathogenesis of SLE.

관리회계정보와 기업전략의 관련성 탐색

이원기(Lee, Won-Ki) 한국산업경제학회 2015 한국산업경제학회 정기학술발표대회 논문집 Vol.2015 No.05

This study examined the characteristics of management accounting informations according to the stages of Firm Life-Cycle based on Contingency Theory. This study divided Firm Life-Cycle into start-up stage, growth stage, mature stage and decline stage and investigates the business strategy related with each stage of Firm Life-Cycle. The types of business strategy regarded in this study are product differentiation and cost leadership. We find out there is a relationship between the stages of Firm Life-Cycle and the types of business strategies and it is necessary to provide different management accounting informations according to the selected strategy. This study proposes that management accounting informations have to be provided according to the firm"s strategy and the stage of firm"s Life-Cycle.

고속회전 아크센서를 이용한 필렛 용접선 추적에 관한 연구

이원기(Won-Ki Lee),이근유(Gun-You Lee),오명석(Myung-Seok Oh),김상봉(Sang-Bong Kim) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4

In this paper, a high speed rotating arc sensor for automatic fillet welding is introduced. In order to track the welding seam, The high speed rotating arc sensor is used. The welding tip of a high speed rotating arc sensor rotates about 3000 rpm using DC Motor. The rotating torch is driven by gear between welding torch body and wire guide. The welding current is measured by using the current sensor and rotating position sensor. To realize the welding current is measured by using the current sensor and rotating position sensor. To realize the welding seam tracking algorithm with accuracy, a software filter algorithm using the moving average method is applied to the measured welding current in the microprocessor. The welding mobile robot with two wheels and two sliders is developed for fillet welding. The welding mobile robot can control its traveling direction and turn itself around the corner. the effectiveness is proven through the experimental results conducted with varied fillet tracking patterns.

결절성맥락막혈관병증

이원기(Won Ki Lee),권순일(Soon Il Kwon) 대한안과학회 2000 대한안과학회지 Vol.41 No.12

TN접지방식 직류배전에서의 인체 및 설비 보호를 위한 누설전류 검출기

이원기(Won-Ki Lee),김효성(Hyosung Kim) 전력전자학회 2014 전력전자학술대회 논문집 Vol.2014 No.11