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Korean Enterprise Export Strategies to China Dependent on Trade Environment Changes
함기수,Sang-Youn Lee 한국유통과학회 2015 유통과학연구 Vol.13 No.10
Purpose – Currently, the foreign trade environment in China has shifted to a very different system. Korean enterprises have been forced to compete with Chinese enterprises in today’s world market owing to the economic growth and technical improvement in China. Research design, data, and methodology – The author visited Korean export enterprises in Shanghai from January 5 to 12, 2014 to implement a questionnaire survey and conduct in-depth interviews with the local enterprises. The author investigated the Shenyang area using e-mail communication. For the questionnaire, one copy of the questionnaire was given to each business and to a staff member for each of the products when a company sold multiple products. Results – Selling cost advantage, efficiency of economic scale, and product differentiation had the most influence on Korean enterprises' export strategy to China. Additionally, entry barrier, product differentiation, and concentration all had an influence on Korean enterprise export strategy to China as well. Conclusion – Korean enterprises developed strategies for price priority, economies of scale, and product differentiation based on changes in the competitive structure in the Chinese market.
Selective laser melting 공정으로 제조된 AISI 316L 합금의 상온 및 고온 압축 변형 거동
함기수,박순홍,이기안 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.5
This study investigated the microstructure and compressive properties (at room & high temperatures) of Fe-Cr-Ni based AISI 316L alloy, manufactured by selective laser melting process. The effect of stress relieving heat treatment on the microstructure and mechanical properties also examined. Regardless of the stress relieving heat treatment, the SLMed AISI 316L alloy exhibited typical molten pools and fine columnar structures which grew along the laser heat source. A cellular type dendrite structure was also observed inside the molten pool. After heat treatment, the low angle boundary fraction decreased and the high angle boundary fraction increased in the SLMed AISI 316L alloy. In the 25 oC, 500 oC, 700 oC, 900 oC compressive results, the heat treated 316L alloy showed lower yield strengths than the as fabricated alloy at all temperature conditions. However, the difference in yield strength between the as fabricated and heat treated alloys gradually decreased with increasing temperature. Surface and cross-sectional fractographies showed that the heat treated alloy accommodated more plastic deformation. This was considered the cause of the more pronounced work hardening of the heat treated alloy, as identified in the stress versus strain curves. The correlations between microstructure, temperature dependent mechanical properties and stress relieving heat treatment were also discussed based on these findings.
Effect of Heat Treatment on Tensile and Fatigue Deformation Behavior of Extruded Al-12 wt%Si Alloy
함기수,백민석,김종호,이시우,이기안 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.1
This study investigated the effect of heat treatment on tensile and high-cycle fatigue deformation behavior of extruded Al-12 wt%Si alloy. The material used in this study was extruded at a ratio of 17.7 : 1 through extrusion process. To identify the effects of heat treatment, T6 heat treatment (515 °C/1 h, water quenching, and then 175 °C/10 h) was performed. Microstructural observation identified Si phases aligned in the extrusion direction in both extruded alloy (F) and heat treated alloy (T6). The average grain size of F alloy was 8.15 °C, and that of T6 alloy was 8.22 °C. Both alloys were composed of Al matrix, Si, Al2Cu, Al3Ni and AlFeSi phases. As T6 heat treatment was applied, Al2Cu phases became more finely and evenly distributed. Tensile results confirmed that yield strength increased from 119.0 MPa to 329.0 MPa, ultimate tensile strength increased from 226.8 MPa to 391.4 MPa, and the elongation decreased from 16.1% to 5.0% as T6 heat treatment was applied. High-cycle fatigue results represented F alloy’s fatigue limit as 185 MPa and T6 alloy’s fatigue limit as 275 MPa, indicating that high-cycle fatigue properties increased significantly as heat treatment was conducted. Through tensile and fatigue fracture surface analysis, this study considered the deformation behaviors of extruded and heat treated Al-Si alloys in relation to their microstructures.
AISI 1045 강의 인장 및 고주기 피로 특성에 미치는 Cr 도금층 두께의 영향
함기수,강연지,김형준,윤상훈,이기안 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.3
This study investigated and compared the tensile and high-cycle fatigue properties of AISI 1045 steel and Cr electroplated AISI 1045 steel. First, tensile and fatigue specimens were machined from AISI 1045 steel (substrate), and two kinds of Cr electroplating layers with different layer thickness were applied. The substrate, AISI 1045 steel consisted of an a-Fe matrix and pearlite, and the two Cr electroplating layers were measured to have thicknesses of 13.1 μm and 53.9 μm, respectively. The Cr layer did not show signs of peeling from the substrate, but initial micro cracks were present within the Cr electroplating layer. Tensile test results confirmed that the Cr electroplated specimens had similar yield strengths and tensile strengths to those of the substrate AISI 1045 steel, but elongation decreased significantly. High cycle fatigue results confirmed that the fatigue limit (~107 cycles to fatigue failure) of the substrate steel was 600 MPa, and the fatigue limit decreased significantly to 500 MPa (13.1 μm thickness) and 325 MPa (53.9 μm thickness) as the Cr electroplating layers were formed. This study also observed fracture surfaces of tensile and high cycle fatigue fractured specimens, and the deformation mechanisms of the Cr electroplated steel were suggested in connection with microstructures.
레이저 클래딩 공정을 이용한 Ni-Cr-B-Si + WC/12Co 복합 코팅층의 제조 및 기계적 특성
함기수,김철오,박순홍,이기안,Ham, Gi-Su,Kim, Chul-O,Park, Soon-Hong,Lee, Kee-Ahn 한국분말야금학회 2017 한국분말재료학회지 (KPMI) Vol.24 No.5
In this study we manufacture a Ni-Cr-B-Si +WC/12Co composite coating layer on a Cu base material using a laser cladding (LC) process, and investigate the microstructural and mechanical properties of the LC coating and Ni electroplating layers (reference material). The initial powder used for the LC coating layer is a powder feedstock with an average particle size of $125{\mu}m$. To identify the microstructural and mechanical properties, OM, SEM, XRD, room and high temperature hardness, and wear tests are implemented. Microstructural observation of the initial powder and LC coating layer confirm the layer is composed mainly of ${\gamma}-Ni$ phases and WC and $Cr_{23}C_6$ carbides. The measured hardness of the LC coating and Ni electroplating layers are 653 and 154 Hv, respectively. The hardness measurement from room up to high temperatures of $700^{\circ}C$ result in a hardness decrease as the temperature increases, but the hardness of the LC coating layer is higher for all temperature conditions. Room temperature wear results show that the wear loss of the LC coating layer is 1/12 of the wear level of the Ni electroplating layer. The measured bond strength is also greater in the LC coating than the Ni electroplating.
Modified Al-Si-Mg 계 조조용 합금의 ECO-Mg 함량 변화에 따른 인장 및 피로 변형 거동
함기수(G.S. Ham),백상우(S.W. Baek),김민종(M.J. Kim),김세광(S.K. Kim),윤영옥(Y.O. Yoon),조규상(K.S. Cho),이기안(K.A. Lee) 한국소성가공학회 2014 한국소성가공학회 학술대회 논문집 Vol.2014 No.5
The effect of ECO-Mg addition on the microstructure, tensile and fatigue deformation behaviors of modified Al-Si-Mg casting alloy was investigated. Four different alloys having various amounts of ECO-Mg (0.3, 0.4, 1.0 and 1.5 wt.%) were prepared though sand casting process. OM microscopy, Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) and X-ray Diffraction (XRD) analyses was examined as well as hardness, tensile, and fatigue tests. Modified aluminum alloy consisted of α-Aluminum (dendrite shape), eutectic Si, Mg₂Si and Fe-intermetallic phases. It was found that DAS(Dendrite Ann Spacing) gradually decreased and eutectic Si, Fe-intermetallic phases were more finely distributed in the matrix with increasing the amount of ECO-Mg. Tensile and fatigue properties were also improved with increasing ECO-Mg content. The micro-mechanisms of tensile and fatigue deformations of the alloy were also discussed based on the fractography observation results.
Twin roll strip casting 공정으로 제조된 Al 3527K 합금의 인장 및 피로 변형 거동
함기수(G. S. Ham),백민석(M. S. Baek),어광준(K. J. Euh),임영목(Y. M. Rhyim),이기안(K. A. Lee) 한국소성가공학회 2016 한국소성가공학회 학술대회 논문집 Vol.2016 No.4
This study investigated tensile and fatigue properties of Al 3527K alloy manufactured by strip casting process. Al 3527K alloy (as strip casted (F material)) produced by twin roll strip casting and H heat treated (480°C, 6hr, AC) alloy were examined and compared. Microstructure observation results revealed that both alloys (F and H) featured rapid solidification microstructures. In addition, both alloys were identified to be composed of Al, Al6(Mn, Fe) and AlFeMnSi phases. As H heat treatment was applied, Al 3527K-H alloy formed a more even phase distribution than Al 3527K-F alloy. The tensile properties showed that H heat treatment resulted in increase of strength and decrease of elongation. In tensile fracture surface observation, both alloys showed typical ductile fracture modes. The F alloy was measured to have a dimple size of 6.8㎛ on average, and the H alloy measured 4.2㎛ on average in fracture surfaces. High-cycle fatigue tests were performed using ISTRON 8501, and the test conditions were stress ratio R=0.1, 10 Hz at room temperature. The fatigue limit showed that H heat treatment resulted in increase of fatigue properties at all stress condition. Furthermore, F alloy featured a larger deviation in fatigue life in all identical stress conditions compared to the O alloy. This study also discussed the fatigue deformation behavior of Al 3527K alloy manufactured by strip casting through the abovementioned mechanical properties as well as the tensile and fatigue fractographies.