도서관정책과 도서관문화의 발전

이경구,Lee, Gyeong-Gu 대한출판문화협회 1990 출판저널 Vol.74 No.-

보강재에 도금된 Cu층이 Al/SiC복합재료의 젖음성에 미치는 영향

이경구,조규종,이도재,Lee, Gyeong-Gu,Jo, Gyu-Jong,Lee, Do-Jae 한국재료학회 2001 한국재료학회지 Vol.11 No.5

SiC 보강재 표면에 도금된 Cu금속층이 Al/SiC복합재료의 젖음성에 미치는 영향을 검토하였다. 보강재에 대한 금속층의 도금은 무전해도금법을 이용하였으며, Al/SiC 복합재료의 제조는 텅스텐 발열체 진공로의$ 670^{\circ}C$~$900^{\circ}C$에서 제조하여 보강재와 기지간의 접촉부위를 촬영하여 젖음성을 측정하였다 젖음성 측정 결과 보강재에 도금된 Cu층은 젖음성을 향상시켰고, 젖음성의 개선은 보강재에 도금된 금속층과 기지간의 반응에 의해 계면에너지를 변화시킴으로서 나타난 결과이며. 반응을 통한 산화피막의 배제도 영향을 미친 것으로 판단된다 Effects of coating treatment of metallic Cu film on SiC for Al/SiC composite were studied. The Copper was deposited on SiC by electroless plating method. Al/sic composite was fabricated at temperature range of $670^{\circ}C$ to 90$0^{\circ}C$ under vacuum atmosphere. The wetting behavior of Al/SiC composite were analysed by SEM and XRD. The coating treatment on SiC improved wettability of Al melt on SiC considerably comparing to the non coated SiC. This improved wettability seems strongly concerned to the increase of chemical reactivity between coated layer and Al matrix. The improvement of wettability of Al melt on the Cu coated SiC was closely related to in the initial stage of reaction. The metallic film played an important role in reducing the interfacial free energy and breaking down the aluminum oxide film through the reaction with Al melt. The wetting behavior of the as-received SiC with Al melt was not uniform, indicated by the contact angles from less than $97^{\circ}$to more than $97^{\circ}$.

DVD-ROM 시스템에 적용한 신경망 등화기에 관한 성능

이경구,최수용,옹성환,유철우,홍대식,Lee, Kyung-Goo,Choi, Soo-Yong,Ong, Sung-Hwan,You, Cheol-Woo,Hong, Dae-Sik 대한전자공학회 1998 電子工學會論文誌, S Vol.s35 No.10

차세대 저장매체로서 이미 그 규격이 확정된 재생 전용 디지털 다기능 디스크 시스템에 등화기를 적용하여 그 성능을 분석한다. 재생 전용 디지털 다기능 디스크 시스템에서는 정보 기록 시에 비선형 왜곡현상을 유발할 수 있으므로 이의 보상을 위해 비선형 입출력 사상능력이 뛰어나다고 알려져 있는 신경망 등화기를 적용한다. 또한, 결정궤환 구조의 등화기는 변조부호와 결합하여 사용하면 성능 개선을 보장할 수 없다는 것을 확인하기 위한 실험을 한다. 두 종류의 시스템에 대한 등화 실험으로 신경망을 이용한 등화기가 기존의 등화기에 비해 더 좋은 등화성능을 보이며 이는 채널의 비선형성이 증가할수록 확연해지는 결과를 얻었다. 또한, 랜덤한 데이터열의 간섭 보상에는 결정궤환 구조의 등화기가 우수한 성능을 보이지만 변조 부호화된 데이터열의 간섭 보상에는 결정궤환이 없는 구조와 비교하여 성능 개선이 없다는 결과를 얻었다. Several equalizers are applied to the DVD-ROM(Digital Versatile Disc-Read Only Memory) system. Because imperfect writing process may cause nonlinear distortion in the reply signal, neural equalizers which have strong nonlinear mapping capability are applied to the system to compensate the nonlinear distortion. Experimental results to verify that the combination of decision-feedback type equalizers and modulation code is formidable are also given. The experimental results shwo that the SNR gain of the neural equalizers over the conventional equalizers becomes much as the nonlinearity in the channel increases. Furthermore, the decision-feedback type equalizers outperform the equalizers which have no decision-feedback in eliminating ISI(Intersymbol Interference) of random data sequence but there is no performance gain of the decision-feedback type equalizers over the equalizers without decision-feedback when these are applied to compensate the ISI of modulation-encoded data sequence.

STS 304 , 316 강의 열처리에 따른 산화거동

이경구,윤동주,기회봉,강창석,이도재 ( Kyung Ku Lee,Dong Ju Yoon,Whe Bong Ghi,Chang Sug Kang,Doh Jae Lee ) 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.3

N/A An oxidation behavior of 304 and 316 stainless steels were studied in dry air. After solution treatment, specimens were polished up to 1㎛ A1₂O₃ grade and then subjected to oxidation treatment in dry air at 800℃∼1200℃. The oxidation behavior between matrix and oxide scale was analyzed with SEM, EDS and XRD. When oxidation treatment was conducted at 1200℃, large thickness of Fe oxide scale was formed on top of surface and fine (Cr,Fe)₂O₃oxide film was formed below it. Cr rich zone existed at interface between metal and (Cr,Fe)₂O₃oxide layer, and it was believed that this zone acted as obstacle to oxidation. Most of Ni was detected at the interface between metal and (Cr,Fe)₂O₃and also detected at the interface between Fe₂O₃and (Cr,Fe)₂O₃.

비탄성 국부좌굴을 고려한 철골 모멘트 접합부 회전능력 평가를 위한 모델 개발

이경구,Lee, Kyung Koo 한국강구조학회 2008 韓國鋼構造學會 論文集 Vol.20 No.5

잘 설계된 철골 모멘트 접합부의 경우, 유효회전능력에 도달하기 전에 국부좌굴이 발생하고 비탄성 후좌굴 변형이 접합부 회전능력을 정의하는데 중대한 역할을 한다. 이 연구에서는 국부좌굴로 인한 강도저하와 보 소성힌지의 회전을 모델링하여, 단조증가하중 및 반복하중이 작 용하는 특별철골모멘트골조의 강접합 보-기둥 접합부의 회전능력을 예측하기 위한 근사적 해석모델을 제안한다. 제안된 항복선 소성힌지 모델은 좌굴된 소성힌지부의 형상에 기초하여 항복선과 소성존으로 구성되고, 소성메커니즘을 통해 국부좌굴후의 거동까지 포함한 모멘트-회전각 관계를 제 공한다. 향상된 WUF-W 와 RBS 접합부를 위해 제안된 모델을 개발한 후 실험결과와 비교를 통해 검증하였다. 동반논문(변수연구)에서는 광범위 한 H-형강의 기하학적 변수 따른 접합부 회전능력에 대하여 논의하였다. Well-designed steel moment connections will undergo local buckling before they exhaust their available rotation capacity, and inelastic post-buckling deformation plays a major role in defining the connection rotation capacity. An approximate analytical method to model strength degradation and failure of beam plastic hinges due to local buckling and estimation of the seismic rotation capacity of fully restrained beam-column connections in special steel moment-resisting frames under both monotonic and cyclic loading conditions is proposed in this study. This method is based on the plastic mechanism and a yield line plastic hinge (YLPH) model whose geometry is determined using the shapes of the buckled plastic hinges observed in experiments. The proposed YLPH model was developed for the improved WUF-W and RBS connections and validated in comparison with experimental data. The effects of the beam section geometric parameters on the rotation capacity were discussed in the companion paper (parametric studies).

뇌신경질환에 사용된 레이저 및 광선치료에 대한 임상 연구 고찰

이경구,신종훈,이경진,선승호,한창호,장인수,Lee, Kyung-Goo,Shin, Jong-Hun,Lee, Kyung-Jin,Sun, Seung-Ho,Han, Chang-Ho,Jang, In-Soo 대한한방내과학회 2014 大韓韓方內科學會誌 Vol.35 No.4

Objectives: Recently, many studies have reported beneficial effects from the application of laser and light-emitting diode (LED) therapy for cerebral nervous disease. Transcranial laser therapy and LED therapy may be an effective method to treat diseases of the cerebral nervous system. This study aims to discuss the possibility of laser and LED therapy for cerebral nervous disease by reviewing literature about its effectiveness. Methods: We searched papers using PubMed, Science Direct, CINAHL, KTKP, Oasis and NDSL, using the keywords "Laser therapy, low-level", "Transcranial laser", "Transcranial light emitting diode" and "stroke", "traumatic brain injury", "dementia", "anxiety", "cognitive", "emotional effects", "psychiatric disorder", "multiple sclerosis", "Parkinson's disease". The search range included randomized controlled trials (RCTs) and clinical case series. Reviews and animal experiments were not included. Studies not matched with inclusion criteria were excluded. Results: A total 1,119 studies were found. 1,100 were excluded from scanning titles and abstracts and finally 9 articles were selected. Among the 9 articles, 5 were RCTs, one was a controlled study, and the other 3 were case reports. They reported that transcranial laser therapy and LED treatment had beneficial effects from photobiomodulation to the cerebral nervous system. Clinical evaluation factors showed favorable trends. Conclusions: Transcranial laser therapy and LED therapy seem to be effective to the cerebral nervous system and they may be a favorable choice for cerebral nervous disease.

가압주조법에 의해 제조된 AC4C Al / coated SiC 복합재료의 마모특성에 관한 연구

이경구,이도재 ( Kyung Ku Lee,Doh Jae Lee ) 한국주조공학회 1996 한국주조공학회지 Vol.16 No.4

N/A Effects of SiC particle on wear resistance of AC4C Al/SiC composite were studied. Experimental variables included were types of metallic coatings such as Cu and Ni-P, and volume fraction of SiC particle in composite. The results of wear test showed that the wear resistance of AC4C Al/SiC composite is increased linearly with volume fraction of SiC particles. In the range of our experimental conditions, there is no significant difference in wear resistance between the type of pretreatment for coating on SiC particles used for composite specimens the as-received SiC reinforced and coated SiC reinforced composite. Wear debries generated during wear test are identified as Al from matrix alloy of specimen, and iron oxide from steel block which is counter part of abrasion test. Severe subsurface plastic deformation is observed at the regions close to the wear surface, and the surface region were work hardened.

PFC 법에 있어서의 Al-Cu 다결정리본의 응고특성

이경구,이상목,홍준표 ( Kyung Ku Lee,Sang Mok Lee,Chun Pyo Hong ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.4

N/A Polycrystalline Al-Cu ribbons were produced by planar flow casting(PFC). Solidification behavior and microstructual changes of the ribbons have been investigated as a function of ribbon thickness and processing parameters. The solidification front velocity, V varies within the ribbon, decreasing with increasing the distance, S from the wheel-contact surface, as V=17.6S^(-1). In Al-4.5wt%Cu alloy, rapid decrease in solidification velocity toward the free surface causes a change in solidification morphology from planar to cellular, and finally, to dendritic. The length and inclination of columnar grains solidified with planar front were related to the wheel velocity. The transition from particulate degenerate eutectic structure to regular lamellar eutectic structure was observed to be caused by a difference of the relative growth velocites of α-Al and θ during solidification in the Al-Cu eutectic alloy.

Al / SiCp 복합재료에서 보강재 표면의 금속 피복층이 젖음성과 계면 강도에 미치는 영향

이경구,이도재 ( Kyung Ku Lee,Doh Jae Lee ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.4

N/A Effects of metal coating treatment on SiC particle on wetting behavior and interfacial strength were studied. Experimental variables are included types of coated metallic films such as Cu and Ni-P, and temperatures of heat-treatment under vacuum. The experimental results concerning wetting phenomena of liquid Al on SiC, showed that coating treatment of metallic film on SiC particles remarkably improves the wetting behavior of liquid Al on SiC, especially in the case of Ni-P coating. The interfacial strength of Al/SiC composites made of coated SiC plate was higher than that of the composite with non-coated SiC plate although the coating treatment was not perfect.

Squeeze Casting 법에 의해 제조된 A356 / coated SiC 복합재료의 미세조직과 기계적 특성에 관한 연구

이경구,이도재 ( Kyung Ku Lee,Doh Jae Lee ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.5

N/A Influence of interfacial structure between matrix and particle in A356/coated SiC composite fabricated by squeeze casting method was studied. Experimental variables are types of coated metallic film on SiC particles such as Cu, Ni-P, and applied pressure for squeeze casting. It was found that coating treatment on SiC particles improves the wetting of liquid A356 alloy on SiC particles. SiC particle distribution is very homogeneous in A356 matrix alloy which is fabricated by squeeze casting. Analysing the surface morphology of fractured A356/coated SiC, it was concluded that metallic thin film by coating treatment on SiC particle improves the interfacial bonding between particle and matrix, and so does on mechanical properties such as tensile strength. However, there was on significant difference in hardness between those composite made of as-received SiC particle and coated SiC particle.