밀도함수 이론법을 이용한 마그네슘 합금의 재료특성 예측에 관한 연구

백민숙,원대희,김병일,Baek, Min-Sook,Won, Dae-Hee,Kim, Byung-Il 한국재료학회 2007 한국재료학회지 Vol.17 No.12

The total energy and strength of Mg alloy doped with Al, Ca and Zn, were calculated using the density functional theory. The calculations was performed by two programs; the discrete variational $X{\alpha}\;(DV-X{\alpha})$ method, which is a sort of molecular orbital full potential method; Vienna Ab-initio Simulation Package (VASP), which is a sort of pseudo potential method. The fundamental mixed orbital structure in each energy level near the Fermi level was investigated with simple model using $DV-X{\alpha}$. The optimized crystal structures calculated by VASP were compared to the measured structure. The density of state and the energy levels of dopant elements was discussed in association with properties. When the lattice parameter obtained from this study was compared, it was slightly different from the theoretical value but it was similar to Mk, and we obtained the reliability of data. A parameter Mk obtained by the $DV-X{\alpha}$ method was proportional to electronegativity and inversely proportional to ionic radii. We can predict the mechanical properties because $\Delta{\overline{Mk}}$is proportional to hardness.

Al 2013-T8 합금에서 Zr 첨가에 따른 기계적 특성 분석

백민숙,조사현,박만복,윤동주,허기복,Baek, Min-Sook,Cho, Sa-Hyeon,Park, Man-Bok,Yoon, Dong-Joo,Heo, Ki-Bok 한국재료학회 2016 한국재료학회지 Vol.26 No.8

In this study, the recently developed Al 2013 alloy was T8-tempered and, to improve the strength and corrosion-resistance, slight amounts of Zr of 0.2 wt% and 0.5 wt%, respectively, were added and the mechanical properties were analyzed. For microstructure and precipitate analysis, OM observation, XRD analysis, and TEM analysis were performed, and for the mechanical property analysis, hardness and tensile strength tests were done. Also, in order to determine the corrosion rate according to the Zr content, a potentiodynamic polarization test was performed and the properties were compared and analyzed. The size of the precipitate varied with the content of Zr and was finest at Zr content of 0.2 wt%; it grew larger at 0.5 wt%, at which point the hardness value accordingly showed the same trend. On the other hand, as calculated from the aspect of chemical bonding among atoms, it was confirmed that the tensile strength and the corrosion-resistance increased with the same trend.

AIP법으로 형성된 TiAgN 코팅필름의 바이어스전압에 따른 표면 특성 분석

백민숙,윤동주,강병모,정운조,김병일,Baek, Min-Sook,Yoon, Dong-Joo,Kang, Byeong-Mo,Jeong, Woon-Jo,Kim, Byung-Il 한국재료학회 2015 한국재료학회지 Vol.25 No.5

The implanting of metal products is performed with numerous surface treatments because of toxicity and adhesion. Recently, the surface modification of metal products has been actively studied by coating the surface of the TiC or TiN film. We prepared a Ti(10%)Ag Target which may be used in dental oral material by, using the AIP(arc ion plating) system TiAgN coating layer that was deposited on Ti g.23. The purpose of this study was to establish the optimal bias voltage conditions of the coated TiAgN layer formed by the AIP process. The TiAgN coatings were prepared with different bias voltage parameters (0V to -500V) to investigate the effect of bias voltage on their mechanical and chemical properties. The SEM(scanning electron microscope), EDS(energy dispersive X-ray spectrometer), XRD(X-ray diffraction), micro-hardness, and potentiodynamic polarization were measured and the surface characteristics of the TiAgN coating layers were evaluated. The TiAgN coating layer had different mechanical characteristics based on the bias voltage, which also showed differences in thickness and composition.

AIP법으로 증착된 TiN/CrN 다층박막의 특성 분석

백민숙,윤동주,허기복,김병일,Baek, Min-Sook,Yoon, Dong-Joo,Heo, Ki-Bok,Kim, Byung-Il 한국재료학회 2018 한국재료학회지 Vol.28 No.7

TiN and CrN thin films are among the most used coatings in machine and tool steels. TiN and CrN are deposited by arc ion plating(AIP) method. The AIP method inhibits the reaction by depositing a hard, protective coating on the material surface. In this study, the characteristics of multi-layer(TiN/CrN/TiN(TCT), CrN/TiN/CrN(CTC)) are investigated. For comparison, TiN with the same thickness as the multilayer is formed as a single layer and analyzed. Thin films formed as multilayers are well stacked. The characteristics of micro hardness and corrosion resistance are better than those of single layer TiN. The TiN/CrN peak is confirmed because both TCT and CTC are formed of the same component(TiN, CrN), and the phase is first grown in the (111) direction, which is the growth direction. However, the adhesion and abrasion resistance of the multilayer films are somewhat lower.

에너지 전자상태 계산으로 도출된 이론값을 이용한 니켈 합금 설계

백민숙,강법성,백경철,김병일,윤동주,Baek, Min-Sook,Kang, Pub-Sung,Baek, Kyeong-Cheol,Kim, Byung-Il,Yoon, Dong-Joo 한국재료학회 2015 한국재료학회지 Vol.25 No.11

Super alloys, which can be divided into three categories, i.e. Ni-base, Co-base, and Fe-base alloys, are widely used for high temperature applications. Since superalloys contain many alloying elements and precipitates, their chemistry and processing parameters need to be carefully designed. In this study, we designed a new Ni alloy to prevent corrosion due to water vapor and gases at high temperatures. The new alloy was designed using the theoretical value of the resulting energy electronic state calculation($DV-X{\alpha}$ method). The components that were finally used were Cr, Mo, and Ti, with Ni as a base. For these alloys, elements were selected in order to compare their values with that of the average theoretical basis for an Inconel 625 alloy. Finally, two kinds of Ni alloy were designed: Ni-28Cr-4Mo-2Ti and Ni-20Cr-10Mo-1Ti.

DV-Xα 분자궤도법으로 설계한 생체용 Ti-Ag-Zr 합금 특성 평가

백민숙,윤동주,김병일,Baek, Min-Sook,Yoon, Dong-Joo,Kim, Byung-Il 한국재료학회 2014 한국재료학회지 Vol.24 No.4

Ti and Ti alloys have been extensively used in the medical and dental fields because of their good corrosion resistance, high strength to density ratio and especially, their low elastic modulus compared to other metallic materials. Recent trends in biomaterials research have focused on development of metallic alloys with elastic modulus similar to natural bone, however, many candidate materials also contain toxic elements that would be biologically harmful. In this study, new Ti based alloys which do not contain the toxic metallic components were developed using a theoretical method (DV-$X{\alpha}$). In addition, alloys were developed with improved mechanical properties and corrosion resistance. Ternary Ti-Ag-Zr alloys consisting of biocompatible alloying elements were produced to investigate the alloying effect on microstructure, corrosion resistance, mechanical properties and biocompatibility. The effects of various contents of Zr on the mechanical properties and biocompatibility were compared. The alloys exhibited higher strength and corrosion resistance than pure Ti, had antibacterial properties, and were not observed to be cytotoxic. Of the designed alloys' mechanical properties and biocompatibility, the Ti-3Ag-0.5Zr alloy had the best results.

밀도함수 이론법으로 설계한 고강도 Ti 합금 특성 분석

백민숙 ( Min Sook Baek ),윤동주 ( Dong Joo Yoon ),김기빈 ( Ki Bin Kim ),김영준 ( Young Jun Kim ),김병일 ( Byung Il Kim ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.7

Titanium and its alloys offer the highest strength, excellent corrosion resistance and the highest strength to weight, but their disadvantage is a higher cost. This study was made to obtain useful information on their high-strength properteis for designing beta type titanium alloys using the DV-Xα method. To lower prices low-cost elements (Mo, Al, Fe) were used. The Mechanical properties of these alloys are compared to commercial alloys in order to investigate the characteristics of the alloys. The results showed strength of the titanium alloys was somewhat higher (30-90 MPa) than conventional alloys.

뉴실버 세대 패션 브랜드에 관한 연구

백민숙(Min Sook Baek),변미연(Mi Yeon Byun) 한국디자인문화학회 2011 한국디자인문화학회지 Vol.17 No.2

현재 트렌드로 대두되고 있는 뉴실버 세대는 기존의 중·장년층과는 달리 고학력이며 경제적 여유가 있고, 제3의 인생으로 계속적인 사회참여나 경제적인 활동 및 자아실현을 추구하며, 높은 구매력과 자립적 가치관을 가진 핵심 소비자 계층으로 현대 사회의 각 계층에 큰 영향력을 행사하고 있다. 또한 이들은 자신의 나이보다 젊어 보이기 위해 노력하고 젊은이처럼 행동하고 싶어 하는 연소화(down-again)욕구를 충족시키고자 하는 특성을 지니며, 이러한 특성은 중년층을 대상으로 한 패션, 미용, 건강, 외모 관련 산업의 전망을 밝게 하고 있다. 이에 본 연구에서는 새로운 소비층으로 떠오르며 패션 마켓의 활성화를 가져올 수 있는 뉴실버 세대 패션 브랜드에 관한 연구를 통해 뉴실버 세대를 중심으로 하는 패션업계 및 학계에 디자인 관련 기초자료를 제공하고자 한다. 연구방법 및 범위로는 다음과 같다. 선행 연구, 통계청 보도자료, 인터넷 자료 등을 통해 문헌 연구를 실시하여 사회적 변화에 따라 나타난 신조어인 ``뉴실버 세대``의 개념을 정립하고, 뉴실버 세대 패션 산업의 현황과 전망을 고찰하였으며 설문 조사 연구, 시장 조사 연구를 통해 브랜드 선정 및 선정된 브랜드의 디자인에 대한 분석을 실시하였다. 설문 대상은 뉴실버 세대로 인지하고 있는 여성 300인을 대상으로 하였으며 패션에 대한 접근성을 높이기 위해 서울, 경기, 대전, 광주, 부산 등 대도시 여성으로 한정하였다. 또한 구체적인 브랜드의 선정 및 이들이 추구하는 브랜드의 이상도를 파악하기 위해 포커스 그룹 인터뷰를 실시하였다. 상위의 과정을 통해 선정된 브랜드를 중심으로 디자인 분석을 실시하여 패션 디자인 요소별 결과를 도출하였다. 분석 방법은 본사 및 매장 방문을 통해 디자이너 및 MD, VIP 소비자를 대상으로 전문가 인터뷰, 사진자료 분석법이 사용되었다. 이상의 과정을 토대로 진행된 연구결과는 다음과 같다. 뉴실버 세대는 기존 세대와는 달리 패션 연출에 대해 긍정적으로 생각하는 세대로, 현재 내셔널 브랜드에 대해 불만족을 표출하고 있었으며 이들의 니즈를 반영한 새로운 브랜드가 런칭 되기를 고대하고 있었다. 뉴실버 세대의 대표 브랜드인 쉐르치는 실질적인 구매가 이루어지고 있는 브랜드이나, 이들의 심미적 관점에 기준하였을 때 새로운 디자인의 요구가 나타남을 확인할 수 있었다. New silver generation which appeared as a current trend is different from the existing generations such as high education and purchasing power. They are a main consume population with continuous social participation, their independent own faith. This generation`s traits influences on other generation of the current society. Also, they make an effort to looks younger and have the down-again tendency to do their behavior like young generation. These traits show bright prospect of related industries for middle-aged, such as fashion, beauty, health and appearance. This study tries to provide fashion brands of new silver generation which will invigorate fashion market as a new consume population, and can provide basic materials targeting new silver generation for a fashion industry and academic world. The methods and the range of this study are as in the following. The concept of ``New silver generation``, which is new words came from the social change, is established and the status of New silver generation`s fashion industry deeply is studied by document study using previous studies, the report from 통계청, some information through internet. Also, the survey and market research of this study are able to select the brands and analysis the designs of the selected brands. The participants of the survey are focused on 300 females realizing themselves as New silver generation and living in metropolitan area, such as Seoul, Kyeong-gi province, Dae-jeon, Kwang-ju, Bu-san in order to enhance fashion accessibility. Moreover, FGI was implemented to select a concrete brand and to grasp what is an ideal brand for them. The results of the design analysis for each element are drawn with focusing the selected brands through the higher level procedure. The methods of the analysis are consisted of an analysis of an image and an expert interview through a visit in stores and head quarters with designers, MD, and VIP customers. The results of this study based on these procedures are as in the following. Different from existing generations, new silver generation realize fashion and coordination in positive way. They are dissatisfied with national brand and looking forward to launching new brand reflecting their needs. SHWAEREUCHEE, the representative of new silver generation, practically has sold until now. However, this study can check that new fashion designs are needed according to their aesthetic point of view.

고온 및 Zn Fume에 의한 소재들의 부식성 분석

백민숙(Baek Min Sook) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.5

대부분의 용융 아연 도금 설비에 사용되고 있는 소재는 SM45C(기계구조용 탄소강, KS규격)으로, 주로 저렴한 가격적인 측면에 의해 사용되고 있다. 용융 아연 도금의 특성상 해당 용탕에서 발생되어 올라오는 Zn Fume과 고온의 열에 의한 도금 설비의 산화가 발생되고 있으며 현재 용융 아연 도금 설비의 교체 주기의 시기는 6개월으로 많은 시간과 설비 비용이 낭비 되어오고 있다. 이에 본 연구에서는 다양한 소재들(Inconel625, STS304, SM45C)을 이용하여 고온과 Zn Fume 환경에서 강제로 산화 시켜 각각의 부식성을 확인하고 비교 분석하였으며, 각 소재들의 용융 아연 도금 현장 설비에 적용 가능성을 파악하고자 진행하였다. 강제 산화 실험은 650도의 대기로 내에 Zn 용탕을 두고, Ar 가스를 용탕 내에서 직접 버블링하여 Zn fume를 발생시켜 고온, Zn fume에 의한 부식을 행하는 실험을 하였다. 30일 후 Sample들을 꺼내어 표면의 산화층을 EDS, SEM으로 확인하고, 동전위분극 시험을 이용하여 부식성을 비교 분석하였다. The material normally used in hot dip galvanizing facilities is SM45C (carbon steel for mechanical structure, KS standard), mainly because of its price. During this process, the oxidation of the plating facility occurs due to the heat of the Zn fumes coming from the molten zinc. Since the cycle time of the current facilities is 6 months, much time and money are wasted. In this study, the corrosive properties of various materials (Inconel625, STS304, SM45C) were investigated by oxidation in a high temperature and Zn fumes environment. The possibility of applying the hot-dip galvanizing equipment was investigated for each material. The Zn fumes were generated by directly bubbling Ar gas into Zn molten metal in a 650 degree furnace. High-temperature, Zn fumes corrosion was conducted for 30 days. The sample was removed after 30 days and the oxidation of the surface was confirmed with EDS and SEM, and the corrosion properties were examined using potentiodynamic polarization tests.

DV-Xα 분자 궤도법을 이용한 고강도 타이타늄 합금 설계

백민숙 ( Min Sook Baek ),윤동주 ( Dong Joo Yoon ),원대희 ( Dae Hee Won ),김병일 ( Byung Il Kim ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.9

Beta-type alloys are the most versatile class of titanium alloys. They offer the highest strength to weight ratios and very attractive combinations of strength, toughness, and fatigue resistance inlarge cross sections [1]. The present study was made to obtain useful information for the design of β-type titanium alloys with high-strength properties by using the DV-Xα method. Employing two calculated parameters, the bond order (Bo) and the d-orbital energy level (Md) of alloying elements in β-type titanium alloy was introduced and used for prediction of mechanical properties. Thus, high-strength titanium alloys were designed by calculating the Md and Bo values of the previous and present titanium alloys.