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Analysis of the Optimal Frequency Band for a Ballistic Missile Defense Radar System
Jeongho Park,Dong-Hui Lee,Chulhun Seo,Byoungho Cho,Dang-An Nguyen 한국전자파학회JEES 2018 Journal of Electromagnetic Engineering and Science Vol.18 No.4
In this paper, we consider the anti-attack procedure of a ballistic missile defense system (BMDS) at different operating frequencies at its phased-array radar station. The interception performance is measured in terms of lateral divert (LD), which denotes the minimum acceleration amount available in an interceptor to compensate for prediction error for a successful intercept. Dependence of the frequency on estimation accuracy that leads directly to prediction error is taken into account, in terms of angular measurement noises. The estimation extraction is performed by means of an extended Kalman filter (EKF), considering two typical re-entry trajectories of a non-maneuvering ballistic missile (BM). The simulation results show better performance at higher frequency for both tracking and intercepting aspects.
한랭지역 기후조건에서 철도교량기초 거동 및 단열재 적용성 평가
오정호(Jeongho Oh),김서연(Seo Yeon Kim),팽재엽(Jaeyeop Paeng) 한국방재학회 2023 한국방재학회논문집 Vol.23 No.4
제3차 국가철도망 구축계획(2016년~2025년) 및 철도산업발전 기본계획에 제시된 통일시대를 대비한 한반도 통합철도망 구축을위해서는 북한의 동절기 낮은 온도조건을 고려한 철도 인프라 구축을 위한 선제적 대응이 필요하다. 본 연구에서는 수치해석수행을 통해 북한의 기후 및 지반조건을 고려한 철도교량 기초 거동을 검토하여, 현재 철도노반 설계기준에서 추가적으로고려할 필요가 있는 사항등을 제안하였다. 검토 결과, 동결지수가 1,000 ℃⋅일 이상 되는 한랭지역에서는 철도교량 기초의동착력 증가로 인한 동상방지 대책이 필요한 것으로 확인되었으며, 이와 관련한 단열재 적용에 대한 설계기준을 제안하였다. To establish an integrated railroad network in the Korean Peninsula, in preparation for the unification era presented in the 3rd National Rail Network Construction Plan (2016–2025) and the Railroad Industry Development Basic Plan, a preemptive response to construct railroad infrastructure considering the low temperature in North Korea during winter is essential. In this study, extensive numerical analyses were conducted to evaluate the behavior of railroad bridge foundations while accounting for the climate and geological conditions of North Korea. Furthermore, we proposed additional items that need to be addressed in the current railroad roadbed design standards. Eventually, we found that taking measures, such as application of insulation, to alleviate frost damage due to the increase in the adfreezing strength of railroad bridge foundations in cold regions where the freezing index is more than 1,000 ℃ day is necessary.
Han, Jeongho,Lee, Seung-Joon,Lee, Chan-Young,Lee, Sukjin,Jo, Seo Yeon,Lee, Young-Kook Elsevier 2015 Materials science & engineering. properties, micro Vol.633 No.-
<P><B>Abstract</B></P> <P>The size effect of <I>α</I>′ martensite constituents before annealing on the microstructure and tensile properties of intercritically annealed medium Mn steel was systematically investigated. The cold-rolled Fe–9Mn–0.05C (wt%) steel was austenized at three different temperatures, water-quenched to room temperature to vary the sizes of the martensite constituents, and then annealed at 640°C for 10min. When the austenizing temperature increased, the sizes of the prior austenite (<I>γ</I>) grains and of the packets and blocks of <I>α</I>′ martensite increased; however, the width of the laths changed only insignificantly. The annealed specimens had a dual-phase microstructure with lath-shaped ferrite (<I>α</I>) and retained <I>γ</I> (<I>γ</I> <SUB> <I>R</I> </SUB>) phases. The volume fraction of <I>γ</I> <SUB> <I>R</I> </SUB> decreased with increasing austenizing temperature because the specimen austenized at the higher temperature underwent a slower reverse transformation in the early stage of intercritical annealing. The slowed kinetics of the reverse transformation with increasing austenizing temperature was attributed to the reduction in area of block boundaries which provide nucleation sites for the reverted <I>γ</I>. The widths of the <I>α</I> and <I>γ</I> <SUB> <I>R</I> </SUB> laths were almost independent of the austenizing temperature. The partitioning of Mn and C atoms from <I>α</I> into <I>γ</I> <SUB> <I>R</I> </SUB> laths became active with increasing austenizing temperature, resulting in a more stable <I>γ</I> <SUB> <I>R</I> </SUB>. The specimen austenized at higher temperature exhibited a lower strain hardening rate (SHR) due to the less active transformation-induced plasticity (TRIP) in <I>γ</I> <SUB> <I>R</I> </SUB> with the higher phase stability. The ultimate tensile strength decreased with increasing austenizing temperature because the SHR was lowered by the less active TRIP with increasing austenizing temperature. The uniform elongation increased with increasing austenizing temperature due to delayed necking caused primarily by the flow stress, which dropped with increasing austenizing temperature.</P>
Assurance of mitochondrial integrity and mammalian longevity by the p62-Keap1-Nrf2-Nqo1 cascade
Kwon, Jeongho,Han, Eunhye,Bui, Chi‐,Bao,Shin, Woochul,Lee, Junho,Lee, Sejeong,Choi, Young‐,Bong,Lee, Ann‐,Hwee,Lee, Kyong‐,Hoon,Park, Chankyu,Obin, Martin S,Park, Sung Kyu,Seo, EMBO 2012 EMBO reports Vol.13 No.2