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주조용 Al-Si-Cu-Mg 계 합금의 파괴인성에 관한 연구
마동준,강인찬 ( Dong Jun Ma,In Chan Kang ) 한국주조공학회 1987 한국주조공학회지 Vol.7 No.2
In order to determine the plane strain fracture toughness of Al-Si-Cu-Mg alloy castings, solution heat treatments have been conducted at 530℃ for 8hr and aged for 10hr at 145℃, 160℃ and 175℃. Effects of aging treatment and of Si contents on the fracture toughness have been investigated by a three point loaded bend test, using the artificial notch. The results obtained are as follows; 1) The fracture toughness is appreciably affected by the aging treatment temperature and Si contents. The specimen aged for 10hr at 145℃ has the highest fracture toughness. 2) Increasing Si contents from 5% to 9% results in decrease of fracture toughness. 3) Increasing the aging temperature and Si contents, C.O.D. value was decreased. The specimen aged for 10hr at 145℃ has the highest C.O.D. value. 4) Dimple patterns were observed in the specimens of containing under 7 % Si, while mixed cleavage-dimple patterns in those of over 8% Si.
간략하고 정확한 장방형 각형강관 가새부재 이력거동 예측 위한 해석모델
한상환,성민수,마동준 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.3
The objective of this study is to propose a simple and accurate analytical model for HSS braces. For this purpose, a physical theory model is adopted. Rectangular hollow section steel (HSS) braces are considered in this study. To accurately simulate the cyclic behavior of braces using the physical theory model, empirical equations calculating constituent parameters are implemented on the analytical model, which were proposed in the companion paper. The constituent parameters are cyclic brace growth, cyclic buckling load, and the incidence of local buckling and fracture. The analytical model proposed in this study was verified by comparing actual and simulated cyclic curves of brace specimens. It is observed that the proposed model accurately simulates the cyclic behavior of the braces throughout whole response range.
장방형 각형강관 가새부재 이력거동 예측을 위한 주요변수의 경험식 제안
한상환,성민수,마동준 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.3
The cyclic behavior of braces is complex due to their asymmetric properties in tension and compression. For accurately simulating the cyclic curves of braces, it is important to predict the major parameters such as cyclic brace growth, cyclic buckling load, incidence local buckling and fracture with good precision. For a given brace, the most accurate values of these parameters can be estimated throughout experiments. However, it is almost impossible to conduct experiments whenever an analytical model has to be established for many braces in building structures due to enormous cost and time. For avoid such difficulties, empirical equations for predicting constituent parameters are proposed from regression analyses based on test results of various braces. This study focuses on rectangular hollow structural section(HSS) steel braces, which have been popularly used in construction practice owing to its sectional efficiency.
이성국,김용훈,마동준,한재용,박성수,이상학,Lee, Seong-Guk,Kim, Yong-Hun,Ma, Dong-Jun,Han, Jae-Yong,Park, Seong-Su,Lee, Sang-Hak 한국재료학회 1995 한국재료학회지 Vol.5 No.7
from the $K_{6}$P$_4$ $O_{13}$ flux using a temperature cooling method. According to SHG outpower measurement, phase matching angle is $\theta$=90$^{\circ}$, $\Phi$=23.3$^{\circ}$and angular acceptance of $\Phi$ direction is about 2 degree, Deviation of phase matching angle due to index inhomogeneity in KTP crystal is 0.17 degree. A 20mW green laser was obtained with the combination of a intracavity Nd ; YAG and KTP crystal. K$_{6}$P$_4$ $O_{13}$ flux로부터 30$\times$40$\times$70㎣ 크기의 inclusion이 없는 KTP 단결성을 성장시켰다 성장된 KTP 결정의 SHG 출력 특성 측정 결과 위상정합각은 $\theta$=90$^{\circ}$, $\Phi$=23.3$^{\circ}$이었고, $\Phi$방향의 angular acceptance는 약 2$^{\circ}$이었다. KTP 결정내 굴절율 변화에 따른 위상정합각 편차는 최대 0.17$^{\circ}$까지 변하였다. 또한 Nd : YAG와 brewster plate를 채용한 내부공진형의 diode pumped SHG module에 KTP 결정을 삽입하여 20mW의 녹색 laser를 얻었다.
RF 스퍼터링방법에 의한 제2고조파소자의 광학박막 제작
김용훈,이성국,마동준,한재용,박성수,이상학,Kim, Yong-Hun,Lee, Seong-Guk,Ma, Dong-Jun,Han, Jae-Yong,Park, Seong-Su,Lee, Sang-Hak 한국재료학회 1996 한국재료학회지 Vol.6 No.6
공진기형 제 2고조파소자(SHG)는 레이저 빔의 에너지 밀도가 높아 고내구성 박막이 필요하다. 본 연구에서는 광학박막 재료로 고융점 산화물인 ZrO2, TiO2, SiO2를 사용하였다. 반응성 스퍼터링 방법으로 제작한 ZrO2, TiO2, SiO2 박막을 XRD, SAM을 사용하여 분석하였고, 박막의 광학적 특성을 평가하였다. SHG 소자의 KTP 및 Nd:YAG 결정의 반사방지막(A/R 코팅)구성은 ZrO2와 SiO2를 사용하여 컴퓨터로 계산하였는데 기본파인 1064nm와 제 2고조파인 532nm에서 각각 0.1%, 0.5%이하의 반사율을 갖도록 하였다. 또한 고반사막(H/R 코팅)의 경우 1064nm에서 99.9%의 반사율을 갖도록 TiO2와 SiO2로 디자인하였다. 제작한 광학박막의 광학적 특성, 레이저 내구성(laser damage threshold), 온습도 안정성 실험 등을 통해 광학박막을 평가하였다.
대형 KTP 단결정 성장 및 광학적 불균일성에 관한 연구
한재용,이성국,마동준,김용훈,박성수,이상학,Han, J.Y.,Lee, S.K.,Ma, D.J.,Kim, Y.H.,Park, S.S.,Lee, S.H. 한국결정성장학회 1994 한국결정성장학회지 Vol.4 No.1
고온용액법(high temperature solution grwth)에 의해 $K_6P_4O_13$의 flux로 부터 KTP 단결정을 성장시켰다. Inclusion이 없는 KTP 단결정을 성장시키기 위해 성방로내 온도기울기, 결정의 회전, 종자결정의 방위, 냉각속도를 조절하였다. 성장된 KTP 단결정은 inclusion이 없었으며, 크기는 $10(a){\times}28(b){\times}33(c)mm^3$ 이었다. 또한 KTP 단결정 boule의 위치에 따른 SHG 출력 특성 측정 및 TEM 분석에 의해 종자결정 주위의 광학적 불균일성의 원인을 조사하였다. Single crystals of Potassium Titanyl Phosphate (KTP) were grown from the flux of $K_6P_4O_13(K_6)$ using a high temperatures solution growth method. To grow the large KTP crystal without inclusion, the temperature gradient in furnace, crystal rotation, orientation of seed crystal, and the cooling rate were controled. The KTP crystals are up to $10(a){\times}28(b){\times}33(c)mm^3$ in size. We investigated the optical inhomogeneity in this KTP crystal by the SHG power measurement and TEM analysis.