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고분자 세라믹 전구체를 이용한 반응 소결 탄화규소의 접합
이동화,김득중,Lee, Dong-Hwa,Kim, Deug-Jooug 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.1
Reaction bonded silicon carbide (RBSiC) is an important engineering ceramic because of its high strength and stability at elevated temperatures, and it is currently fabricated using reasonably cheap manufacturing processes, some of which have been used since the 1960s. However, forming complicated shapes from these materials is difficult because of their poor workability. The purpose of this work is to join the reaction-bonded SiC parts using a preceramic polymer as joint material. The manufacturing of ceramic material in the system Si-O-C from preceramic silicon containing polymers such as polysiloxanes has attained particular interest. The mixtures of preceramic polymer and filler materials, such as SiC, Si and MoSi, were used as a paste for the joining of reaction sintered SiC parts. The joining process during the annealing in Ar atmosphere at $1450^{\circ}C$ were described. The maximum strength of the joints was 63 MPa for the specimen joined with 10 vol.% of $MoSi_2$ and 30 vol.% of SiC as filler materials. Fracture occurred in the joining layer. This indicates that the joining strength is limited by the strength of the joint materials.
비협동 양상태 소나에서 적함 송신기의 단일 능동 신호와 해저 지형 정보를 이용한 송신기 정보 추정
이동화,남종근,정태진,이균경,Lee, Dong-Hwa,Nam, Jong-Geun,Jung, Tae-Jin,Lee, Kyun-Kyung 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.2
The bistatic sonar operations using a spatially-separated source and receiver are classified into cooperative and non-cooperative operations. In the cooperative operation, an active signal of a friendly ship is used and the source information is known previously. In the non-cooperative operation, an active signal of the enemy is used and it is difficult to find out the source information. The source information consists of the range, speed, course and frequency of the source. It gives advantage to operating bistatic sonar. This paper suggests a method of estimating the source information with geographic information in the sea and the single-ping of the enemy. The source range is given using one geographic point. And the source speed, course and the frequency of the enemy's source signal are given using two geographic points. Finally, the validity of the scheme is confirmed through a simulation study.
이동화 ( Lee Dong Hwa ),왕문무 ( Wang Mun Mu ),노수영 ( No Su Yeong ) 한국분무공학회 2003 한국액체미립화학회지 Vol.8 No.3
N/A It is important to improve the efficiency of the existing small scale burner which used in agricultural product dry system and gardening dry system. In order to economize fuel Consumption and decrease the exhaust emission especially CO₂, the better design for the small scale burner is needed. Spray characteristics are the essential element for the design. Macroscopic spray characteristics such as spray angle and breakup length were measured. SMD which is contained the Microscopic spray characteristics was measured too. SMD was measured at 8㎜, 12㎜, 16㎜ downstream of the nozzle tip for both Hago and Danfoss nozzles by the Malvern Particle Sizer.
이동화(Dong-Hwa Lee),안근배(Keunbae Ahn) 한국자료분석학회 2024 Journal of the Korean Data Analysis Society Vol.26 No.2
최근 정부는 중소기업퇴직연금기금제도, 사전지정운용제도 등 퇴직연금제도의 납입단계에 중점을 둔 제도 개혁을 단행해 온 반면 수령단계에 대한 제도개선 논의는 상대적으로 미흡하였다. 이에 본 연구는 퇴직연금제도 수령단계의 인출방안 다양화를 제안하기 위해 퇴직연금 인출방안별 생애효용을 극대화하는 최적 자산배분을 분석하고 생애효용을 중심으로 인출방안을 비교 분석하였다. 여기서, 생애효용은 퇴직자의 소비효용과 상속효용을 구성된다. 분석결과 첫째, 퇴직자는 생애효용을 극대화하기 위해 인출전략 및 상속 동기에 따라 보유자산의 최소 20%에서 최대 100% 수준의 적립금을 위험자산에 투자해야 한다. 둘째, 인출금액과 상속 동기가 증가할수록 위험자산의 최적 투자 비중은 증가하는 것으로 나타났다. 셋째, 연금을 구매하는 전략은 생애기간 동안 안정적으로 현금흐름을 창출할 수 있는 장점이 존재하나 상속효용이 0이 되기 때문에 생애효용의 기댓값 관점에서 타 전략 대비 열위한 것으로 나타났다. 인출방안 및 자산배분에 따라 퇴직자의 생애효용은 다양하게 변화하기 때문에 정부는 퇴직자가 퇴직 이후 소비활동을 안정적으로 영위할 수 있도록 인출방안에 대한 가이드라인을 구체적으로 제공할 필요가 있다. The government has recently implemented reforms focusing on the accumulation phase of the retirement pension scheme, while discussions on improvements to the decumulation phase have been relatively inadequate. In this regard, this study analyzes the optimal asset allocation to maximize the utility of retirement pension withdrawal plans and compares and analyzes withdrawal plans based on utility, aiming to propose diversification of withdrawal methods in the retirement pension system. To achieve this, the study utilizes a utility function that considers both consumption utility and inheritance utility of retirees. The analysis shows the following results: Firstly, retirees should invest a minimum of 20% to a maximum of 100% of accumulated funds in risky assets, depending on the withdrawal strategy and bequest motivation, to maximize lifetime utility. Secondly, as withdrawal amounts and bequest motivations increase, the optimal allocation to risky assets also increases. Thirdly, while the strategy of purchasing annuities offers the advantage of generating stable cash flows throughout the lifespan, it ranks lower in terms of expected lifetime utility compared to other strategies due to the absence of bequest utility. Since lifetime utility varies depending on withdrawal strategies and asset allocation, the government needs to provide guidelines for withdrawal strategies to ensure retirees can sustain stable consumption.