도서관정책과 도서관문화의 발전

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

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).

원형강관 X-이음 트러스접합부의 압축 주강관소성화 평가

이경구,신용섭,손은지,Lee, Kyungkoo,Sin, Yong Sup,Son, Eun Ji 한국강구조학회 2015 韓國鋼構造學會 論文集 Vol.27 No.5

원형강관구조 접합부는 재료의 발전과 접합부의 복잡한 국부 거동 때문에 지속적인 연구되고 있다. 이 연구는 지강관에 압축력이 작용하는 원형강관 X-이음 트러스접합부의 주강관 소성화변형과 접합부 강도에 재료강도와 주강관벽세장비가 미치는 영향을 파악하는 것을 목적으로 한다. 이를 위하여 재료강도와 주강관벽세장비를 변수로 하여 다양한 원형강관 X-이음 트러스접합부에 대하여 범용 유한요소해석 프로그램인 ANSYS Mechanical APDL을 사용하여 정밀유한요소해석을 수행하였다. 해석결과를 토대로 현행 건축구조기준에서 제시하는 주강관소성화 한계상태의 접합부 설계강도를 검토하였다. 결론적으로 원형강관 X-이음 트러스접합부 설계에서 고려해야 할 사항을 제시하였다. The researches on circular hollow section(CHS) connections have been conducted continuously because of development of material properties and complex local behavior of the connections. The purpose of this study is that the effects of material strength and chord wall slenderness on chord plastification and strength of CHS X-joint truss connection under compression on branch member were evaluated. To this end, finite element analyses were performed for various connections, using ANSYS Mechanical APDL program. Based on the analysis results, the design strength of the connections according to chord plastification limit state in KBC were examined. Finally, special considerations for CHS X-joint connection design were suggested.

비탄성 국부좌굴을 고려한 철골 모멘트 접합부의 회전능력에 대한 변수 연구

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

동반논문(모델개발)에서는 특별철골모멘트골조의 강접합 보-기둥 접합부의 회전능력을 예측하기 위한 해석모델을 제안하였다. 본 논문에서는 접합부 회전능력 기준으로 두 개의 극한상태를 고려하였다. 첫째, 보 단면의 국부좌굴로 인해 공칭소성강도까지 강도저하가 발생하였을 때를 회전능력으로 보는 강도저하 극한상태를 고려하였다. 둘째, 큰 진폭의 변형이 몇 번 반복 후에 좌굴된 플랜지에서 소성변형률 축적으로 야기 되는 저주기 피로 파단을 극한상태로 고려하였다. 두 극한상태까지 제안한 모델을 이용하여 단조증가하중 및 반복하중하에 일련의 해석을 수행하였다. 실무설계에서 사용되는 범위안의 다양한 H-형강 보를 모델링한 후, 플랜지 및 웨브 폭-두께비와 같은 보 단면의 기하학적 변수가 WUF-W 접합부의 회전능력과 저주기 피로수명에 미치는 영향을 관찰하였다. In the companion paper (Model Development), an analytical model estimating the available rotation capacity of fully restrained beam-column connections in special steel moment-resisting frames was proposed. In this paper, two limit states were considered as the connection rotation capacity criteria: (i) strength degradation failure when the strength falls below the nominal plastic strength due to the local buckling of the beam's cross-section and (ii) low-cycle fatigue fracture caused by plastic strain accumulation at the buckled flange after only a few cycles of high-amplitude deformation. A series of analyses are conducted using the proposed model with two limit states under monotonic and cyclic loadings. Beam section geometric parameters, such as flange and web slenderness ratios, varied over the practical ranges of H-shapedbeams to observe their effect on the rotation capacity and low-cycle fatigue life of pre-qualified WUF-W connections.

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.

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.

'도서관정책' 이대로 좋은가

이경구,Lee, Gyeong-Gu 한국도서관협회 1990 圖協會報 Vol.31 No.5