Simple Synthesis of SiOx by High-Energy Ball Milling as a Promising Anode Material for Li-Ion Batteries

남승훈,홍성주 한국부식방식학회 2022 Corrosion Science and Technology Vol.21 No.6

SiOx was prepared from a mixture of Si and SiO2 via high-energy ball milling as a negative electrode material for Li-ion batteries. The molar ratio of Si to SiO2 as precursors and the milling time were varied to identify the synthetic condition that could exhibit desirable anode performances. With an appropriate milling time, the material showed a unique microstructure in which amorphous Si nanoparticles were intimately embedded within the SiO2 matrix. The interface between the Si and SiO2 was composed of silicon suboxides with Si oxidation states from 0 to +4 as proven by X-ray photoelectron spectroscopy and electrochemical analysis. With the addition of a conductive carbon (Super P carbon black) as a coating material, the SiOx/C manifested superior specific capacity to a commercial SiOx/C composite without compromising its cycle-life performance. The simple mechanochemical method described in this study will shed light on cost-effective synthesis of high-capacity silicon oxides as promising anode materials.

Retirement For Cause 개념에 의한 가스터빈 디스크 수명의 평가

남승훈,박종화,김종엽,Nam, Seung-Hun,Park, Jong-Hwa,Kim, Jong-Yeop 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.2

For gas turbine engines, the safe life methodology has historically been used fur fatigue life management of failure critical engine components. The safe retirement limit is necessarily determined by a conservative life evaluation procedure, thereby many components which have a long residual life are discarded. The objective of this study is to introduce the damage tolerant design concept into the life management for aircraft engine component instead of conservative fatigue life methodology which has been used for both design and maintenance. Crack growth data were collected on a nickel base superalloy which have been subjected to combined static and cyclic loading at elevated temperatures. Stress analysis fur turbine disk was carried out. The program for computing creep-fatigue crack growth was developed. The residual lifes of turbine disk component under various temperatures and conditions using creep-fatigue crack growth data were estimated. As the result of analysis, it was confirmed that retirement fur cause concept was applicable to the evaluation of residual life of retired turbine disk which had been designed based on the conventional fatigue life methodology.

전기비저항을 이용한 Cr-Mo-V 강의 인성 열화도 평가 ( Evaluation of Toughness Degradation of Cr-Mo-V Steel Using Electric Resistivity )

남승훈,김엄기,유광민,서창민,박종서 대한기계학회 1996 대한기계학회 춘추학술대회 Vol.- No.-

베이나이트 및 템퍼드 마르텐사이트 스프링강의 VHCF, 트라이볼로지 및 충격특성

남승훈,조인식,서창민,박노근 대한기계학회 2024 대한기계학회논문집A Vol.48 No.8

스프링강에 austempering을 실시하여 얻는 베이나이트 조직이 Q/T 처리된 템퍼드 마르텐사이트 조직보다 높은 강도와 연성을 보인다는 보고가 있다. 그러나 차세대 스프링의 내구성 설계에 필요한 베이나이트 조직강의 VHCF, 트라이볼로지 및 충격에 관한 정량적인 연구가 너무 적다. 따라서 본 연구에서는 베이나이트 조직인 스프링강으로 새로운 VHCF의 설계기준이 되는 피로특성을 구하였다. 즉 열처리 사이클에 따른 미세조직 변태의 조직학적인 특성을 EBSD로 정량적으로 분석하면서 SEM과 EDS를 통하여 베이나이트 조직과 템퍼드 마르텐사이트 조직인 스프링강의 피로, VHCF, 트라이볼로지, 충격 및 재료강도특성을 파괴역학적기법과 파면해석적으로 연구, 분석하였다. Studies have reported that the bainitic structure obtained by austempering spring steels exhibits higher strength and ductility than the Q/T-treated tempered martensite structure. However, quantitative studies on VHCF, tribology, and impact characteristics of bainitic steel required for the durability design of next-generation springs are insufficient. Therefore, in this study, fatigue characteristics of VHCF that is a new VHCF design standard with spring steel of bainite and tempered martensite structures were obtained. We quantitatively analyzed the characteristics of microstructure transformation associated with heat treatment cycles and studied and analyzed the fatigue, VHCF, tribology, and impact characteristics using the fracture mechanics method and fracture surface analysis through EBSD, SEM, and EDS.

특전사 기원의 재조명 - 8240부대의 유산과 과제 -

남승훈,고태식 육군군사연구소 2021 군사연구 Vol.- No.152

This study explains the activation process and activities of Army Unit 8240, and illustrates its impact on the foundation of the ROK 1st Combat Group, the predecessor of the ROK Special Warfare Command, and suggests implications. To do so, this study deals with the period from 1951 to 1959. AU 8240 was an official “unit” under the UN during the Korean War, and after the armistice, it was re-named Unit 8250 under the ROK Ministry of National Defense. At that time, partisans from AU 8240 got inducted into the ROK army again. However, some of them received order to form the basis for the foundation of the ROK 1st combat group, the first “airborne unit” of the ROK army, and have continued its legitimacy to this day. The tasks AU 8240 left for us are as follows. First, it is necessary to inherit the tradition of AU 8240 and retain our efforts on honoring their achievements. Second, it is necessary to secure foreign historical data related on AU 8240 and strive to revitalize related warrior research. Third, attention and efforts at the national defense level are needed to create a ROK Joint Special Operations Command. 오늘날 육군 특수전사령부의 기원은 8240부대로 알려졌지만, 그동안 그것의 ‘기원적성격’에 대한 구체적인 논의는 부족했다. 이 연구는 8240부대에 대한 기존 연구성과를보완하는 차원에서 8240부대 창설과정과 활동을 정리하고, 특수전사령부의 전신인 1전투단의 창설에 미친 영향과 오늘날 주어진 유산과 과제를 그동안의 연구성과들을 통해제시한다. 이를 위해 이 연구는 8240부대가 창설된 1951년부터 특수전사령부의 전신인1전투단이 창설되고 발전되는 1959년까지를 다룬다. 8240부대는 6‧25전쟁 중 유엔군 산하에 조직된 공식적인 부대였으며, 정전협정 이후에는 8250부대로 재명명되어 국방부 직할로 편입된 부대이기도 했다. 당시 8240부대출신 유격대원들은 명령에 따라 다시 육군으로 편입되는 과정을 거쳤고, 그 과정에서불가피한 이유로 분산 배치되어 그들의 ‘정통성’이 단절되기도 하였다. 그러나 그들 중일부는 다시 국가의 명령을 받아 한국군 최초 공수부대인 1전투단 창설의 근간이 되어오늘날까지 그 정통성을 이어오고 있다. 8240부대가 우리에게 남긴 과제는 다음과 같다. 첫째, 8240부대의 전통을 계승하고, 그들의 업적을 기리기 위한 노력을 이어나가야 한다. 둘째, 8240부대와 관련된 국외 역사자료들을 확보하고, 관련된 전사연구 활성화를 위해 노력해야 한다. 셋째, 8240 부대가 남긴 미완의 과제인 ‘합동특수작전사령부’ 창설을 위해 국방 차원의 관심과 노력이 필요하다. 8240부대 전사와 전략적, 작전적 수준의 특수작전 발전을 위한 요소들을 접목한 추가적인 연구가 필요하다. 당시 ‘유격전’으로 불렸던 8240부대의 작전은 오늘날 현대적개념의 특수작전으로서 그 특성을 같이한다. 이러한 관점에서, 미국에 보관되어 있어한국에 공개되지 못한 다양한 자료들을 바탕으로 추가적인 연구과제로 다루어질 필요가 있다.

부가응력과 반발경도와의 관계

남승훈,김시천,전승범 ( S . H . Nahm,S . C . Kim,S . B . Jeon ) 한국열처리공학회 1995 열처리공학회지 Vol.8 No.4

Information of change of hardness values during applying load is needed often to control the quality of metal products efficiently, but the relation between applied stress and hardness has not been established. In this paper the theoretical relation between the rebound hardness and stress was examined briefly and the experiment was performed with some materials. Materials used in test were mild steel(SB41), 7-3 brass and copper, which were widely used in the commercial plants. Hardness was measured during stress applied using the Equo-Tip hardness tester as a kind of rebound hardness tester. Hardness values decreased as tensile stress increased, the decreasing rate was effected by the Young`s modulus of each material, and the rebound hardness values showed linear relationship with the applied stress in elastic region.

Environmental Impact Assessment of Composite Small Craft Manufacturing Using the Generic Work Breakdown Structure

남승훈,이동건,정용국,이필립,신종계 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.3 No.3

The number of studies on the environmental impact of products and services has increased in order to protect the environment. Recently, environmental impact assessments (EIA) and life cycle assessments (LCA), typically used for evaluating environmental impacts, have been gaining in popularity. Accordingly, this study performed an EIA using LCA methodology focusing on the manufacture of composite small craft. A work breakdown structure (WBS) is used in most shipyards to manage the overall life cycle of a craft. Therefore, for the EIA performed as part of this study, the generic WBS for environment (GWBSE) was defined by utilizing existing shipyard information. Unlike a general WBS with a determined structure, the GWBSE structure supports different combinations depending on the objectives; the EIA can be performed by combining different methods, materials, and product structures used in the manufacturing process for composite craft. Further, this study developed an application to effectively perform EIA utilizing GWBSE. The EIA was performed according to the manufacturing method and the combination of materials used for small leisure craft; the results were then analyzed.

열화시간에 따른 1Cr-1Mo-0.25V강의 기계적 성질의 변화 ( Change of Mechanical Properites of 1Cr-1Mo-0.25V Steel Depending on Aging Time )

남승훈,김용일,유광민,김시천 대한기계학회 1997 대한기계학회 춘추학술대회 Vol.- No.-

Environmental Impact Assessment of Composite Small Craft Manufacturing Using the Generic Work Breakdown Structure

남승훈,이동건,정용국,Philippe Lee,신종계 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.3 No.4

The number of studies on the environmental impact of products and services has increased in order to protect the environment. Recently, environmental impact assessments (EIA) and life cycle assessments (LCA), typically used for evaluating environmental impacts, have been gaining in popularity. Accordingly, this study performed an EIA using LCA methodology focusing on the manufacture of composite small craft. A work breakdown structure (WBS) is used in most shipyards to manage the overall life cycle of a craft. Therefore, for the EIA performed as part of this study, the generic WBS for environment (GWBSE) was defined by utilizing existing shipyard information. Unlike a general WBS with a determined structure, the GWBSE structure supports different combinations depending on the objectives; the EIA can be performed by combining different methods, materials, and product structures used in the manufacturing process for composite craft. Further, this study developed an application to effectively perform EIA utilizing GWBSE. The EIA was performed according to the manufacturing method and the combination of materials used for small leisure craft; the results were then analyzed.

소형 Charpy 충격시험편을 이용한 1Cr-1Mo-0.25V강의 인성 열화도 평가 ( Toughness Degradation Evaluation of 1Cr-1Mo-0.25V Steel Using Miniaturized Charpy Impact Specimen )

남승훈,김시천,박종서,김엄기 대한기계학회 1998 대한기계학회 춘추학술대회 Vol.- No.-